Sample records for cells express gaba

  1. Insights into GABA receptor signalling in TM3 Leydig cells.

    PubMed

    Doepner, Richard F G; Geigerseder, Christof; Frungieri, Monica B; Gonzalez-Calvar, Silvia I; Calandra, Ricardo S; Raemsch, Romi; Fohr, Karl; Kunz, Lars; Mayerhofer, Artur

    2005-01-01

    Gamma-aminobutyric acid (GABA) is an emerging signalling molecule in endocrine organs, since it is produced by endocrine cells and acts via GABA(A) receptors in a paracrine/autocrine fashion. Testicular Leydig cells are producers and targets for GABA. These cells express GABA(A) receptor subunits and in the murine Leydig cell line TM3 pharmacological activation leads to increased proliferation. The signalling pathway of GABA in these cells is not known in this study. We therefore attempted to elucidate details of GABA(A) signalling in TM3 and adult mouse Leydig cells using several experimental approaches. TM3 cells not only express GABA(A )receptor subunits, but also bind the GABA agonist [(3)H]muscimol with a binding affinity in the range reported for other endocrine cells (K(d) = 2.740 +/- 0.721 nM). However, they exhibit a low B(max) value of 28.08 fmol/mg protein. Typical GABA(A) receptor-associated events, including Cl(-) currents, changes in resting membrane potential, intracellular Ca(2+) or cAMP, were not measurable with the methods employed in TM3 cells, or, as studied in part, in primary mouse Leydig cells. GABA or GABA(A) agonist isoguvacine treatment resulted in increased or decreased levels of several mRNAs, including transcription factors (c-fos, hsf-1, egr-1) and cell cycle-associated genes (Cdk2, cyclin D1). In an attempt to verify the cDNA array results and because egr-1 was recently implied in Leydig cell development, we further studied this factor. RT-PCR and Western blotting confirmed a time-dependent regulation of egr-1 in TM3. In the postnatal testis egr-1 was seen in cytoplasmic and nuclear locations of developing Leydig cells, which bear GABA(A) receptors and correspond well to TM3 cells. Thus, GABA acts via an atypical novel signalling pathway in TM3 cells. Further details of this pathway remain to be elucidated. Copyright (c) 2005 S. Karger AG, Basel.

  2. Evidence that GABA ρ subunits contribute to functional ionotropic GABA receptors in mouse cerebellar Purkinje cells

    PubMed Central

    Harvey, Victoria L; Duguid, Ian C; Krasel, Cornelius; Stephens, Gary J

    2006-01-01

    Ionotropic γ-amino butyric acid (GABA) receptors composed of heterogeneous molecular subunits are major mediators of inhibitory responses in the adult CNS. Here, we describe a novel ionotropic GABA receptor in mouse cerebellar Purkinje cells (PCs) using agents reported to have increased affinity for ρ subunit-containing GABAC over other GABA receptors. Exogenous application of the GABAC-preferring agonist cis-4-aminocrotonic acid (CACA) evoked whole-cell currents in PCs, whilst equimolar concentrations of GABA evoked larger currents. CACA-evoked currents had a greater sensitivity to the selective GABAC antagonist (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA) than GABA-evoked currents. Focal application of agonists produced a differential response profile; CACA-evoked currents displayed a much more pronounced attenuation with increasing distance from the PC soma, displayed a slower time-to-peak and exhibited less desensitization than GABA-evoked currents. However, CACA-evoked currents were also completely blocked by bicuculline, a selective agent for GABAA receptors. Thus, we describe a population of ionotropic GABA receptors with a mixed GABAA/GABAC pharmacology. TPMPA reduced inhibitory synaptic transmission at interneurone–Purkinje cell (IN–PC) synapses, causing clear reductions in miniature inhibitory postsynaptic current (mIPSC) amplitude and frequency. Combined application of NO-711 (a selective GABA transporter subtype 1 (GAT-1) antagonist) and SNAP-5114 (a GAT-(2)/3/4 antagonist) induced a tonic GABA conductance in PCs; however, TPMPA had no effect on this current. Immunohistochemical studies suggest that ρ subunits are expressed predominantly in PC soma and proximal dendritic compartments with a lower level of expression in more distal dendrites; this selective immunoreactivity contrasted with a more uniform distribution of GABAA α1 subunits in PCs. Finally, co-immunoprecipitation studies suggest that ρ subunits can form complexes

  3. Fast detection of extrasynaptic GABA with a whole-cell sniffer.

    PubMed

    Christensen, Rasmus K; Petersen, Anders V; Schmitt, Nicole; Perrier, Jean-François

    2014-01-01

    Gamma-amino-butyric acid (GABA) is the main inhibitory transmitter of the brain. It operates by binding to specific receptors located both inside and outside synapses. The extrasynaptic receptors are activated by spillover from GABAergic synapses and by ambient GABA in the extracellular space. Ambient GABA is essential for adjusting the excitability of neurons. However, due to the lack of suitable methods, little is known about its dynamics. Here we describe a new technique that allows detection of GABA transients and measurement of the steady state GABA concentration with high spatial and temporal resolution. We used a human embryonic kidney (HEK) cell line that stably expresses GABAA receptors composed of α1, β2, and γ2 subunits. We recorded from such a HEK cell with the whole-cell patch-clamp technique. The presence of GABA near the HEK cell generated a measurable electric current whose magnitude increased with concentration. A fraction of the current did not inactivate during prolonged exposition to GABA. This technique, which we refer to as a "sniffer" allows the measurement of ambient GABA concentration inside nervous tissue with a resolution of few tens of nanomolars. In addition, the sniffer detects variations in the extrasynaptic GABA concentration with millisecond time resolution. Pilot experiments demonstrate that the sniffer is able to report spillover of GABA induced by synaptic activation in real time. This is the first report on a GABA sensor that combines the ability to detect fast transients and to measure steady concentrations.

  4. Fast detection of extrasynaptic GABA with a whole-cell sniffer

    PubMed Central

    Christensen, Rasmus K.; Petersen, Anders V.; Schmitt, Nicole; Perrier, Jean-François

    2014-01-01

    Gamma-amino-butyric acid (GABA) is the main inhibitory transmitter of the brain. It operates by binding to specific receptors located both inside and outside synapses. The extrasynaptic receptors are activated by spillover from GABAergic synapses and by ambient GABA in the extracellular space. Ambient GABA is essential for adjusting the excitability of neurons. However, due to the lack of suitable methods, little is known about its dynamics. Here we describe a new technique that allows detection of GABA transients and measurement of the steady state GABA concentration with high spatial and temporal resolution. We used a human embryonic kidney (HEK) cell line that stably expresses GABAA receptors composed of α1, β2, and γ2 subunits. We recorded from such a HEK cell with the whole-cell patch-clamp technique. The presence of GABA near the HEK cell generated a measurable electric current whose magnitude increased with concentration. A fraction of the current did not inactivate during prolonged exposition to GABA. This technique, which we refer to as a “sniffer” allows the measurement of ambient GABA concentration inside nervous tissue with a resolution of few tens of nanomolars. In addition, the sniffer detects variations in the extrasynaptic GABA concentration with millisecond time resolution. Pilot experiments demonstrate that the sniffer is able to report spillover of GABA induced by synaptic activation in real time. This is the first report on a GABA sensor that combines the ability to detect fast transients and to measure steady concentrations. PMID:24860433

  5. Verification of γ-Amino-Butyric Acid (GABA) Signaling System Components in Periodontal Ligament Cells In Vivo and In Vitro.

    PubMed

    Konermann, Anna; Kantarci, Alpdogan; Wilbert, Steven; Van Dyke, Thomas; Jäger, Andreas

    2016-11-01

    CNS key neurotransmitter γ-amino-butyric acid (GABA) and its signaling components are likewise detectable in non-neuronal tissues displaying inter alia immunomodulatory functions. This study aimed at identifying potential glutamate decarboxylase (GAD)65 and GABA receptor expression in periodontal ligament (PDL) cells in vivo and in vitro, with particular regard to inflammation and mechanical loading. Gene expression was analyzed in human PDL cells at rest or in response to IL-1ß (5 ng/ml) or TNFα (5 ng/ml) challenge via qRT-PCR. Western blot determined constitutive receptor expression, and confocal laser scanning fluorescence microscopy visualized expression changes induced by inflammation. ELISA quantified GAD65 release. Immunocytochemistry was performed for GABA component detection in vitro on mechanically loaded PDL cells, and in vivo on rat upper jaw biopsies with mechanically induced root resorptions. Statistical significance was set at p < 0.05. GABA B1 , GABA B2 , GABA A1 , and GABA A3 were ubiquitously expressed both on gene and protein level. GABA A2 and GAD65 were undetectable in resting cells, but induced by inflammation. GABA B1 exhibited the highest basal gene expression (6.97 % ± 0.16). IL-1ß markedly increased GABA B2 on a transcriptional (57.28-fold ± 12.40) and protein level seen via fluorescence microscopy. TNFα-stimulated PDL cells released GAD65 (3.68 pg/ml ± 0.17 after 24 h, 5.77 pg/ml ± 0.65 after 48 h). Immunocytochemistry revealed GAD65 expression in mechanically loaded PDL cells. In vivo, GABA components were varyingly expressed in an inflammatory periodontal environment. PDL cells differentially express GABA signaling components and secrete GAD65. Inflammation and mechanical loading regulate these neurotransmitter molecules, which are also detectable in vivo and are potentially involved in periodontal pathophysiology.

  6. Synchronization by Food Access Modifies the Daily Variations in Expression and Activity of Liver GABA Transaminase

    PubMed Central

    De Ita-Pérez, Dalia; Vázquez-Martínez, Olivia; Villalobos-Leal, Mónica

    2014-01-01

    Daytime restricted feeding (DRF) is an experimental protocol that influences the circadian timing system and underlies the expression of a biological clock known as the food entrained oscillator (FEO). Liver is the organ that reacts most rapidly to food restriction by adjusting the functional relationship between the molecular circadian clock and the metabolic networks. γ-Aminobutyric acid (GABA) is a signaling molecule in the liver, and able to modulate the cell cycle and apoptosis. This study was aimed at characterizing the expression and activity of the mostly mitochondrial enzyme GABA transaminase (GABA-T) during DRF/FEO expression. We found that DRF promotes a sustained increase of GABA-T in the liver homogenate and mitochondrial fraction throughout the entire day-night cycle. The higher amount of GABA-T promoted by DRF was not associated to changes in GABA-T mRNA or GABA-T activity. The GABA-T activity in the mitochondrial fraction even tended to decrease during the light period. We concluded that DRF influences the daily variations of GABA-T mRNA levels, stability, and catalytic activity of GABA-T. These data suggest that the liver GABAergic system responds to a metabolic challenge such as DRF and the concomitant appearance of the FEO. PMID:24809054

  7. Synchronization by food access modifies the daily variations in expression and activity of liver GABA transaminase.

    PubMed

    De Ita-Pérez, Dalia; Méndez, Isabel; Vázquez-Martínez, Olivia; Villalobos-Leal, Mónica; Díaz-Muñoz, Mauricio

    2014-01-01

    Daytime restricted feeding (DRF) is an experimental protocol that influences the circadian timing system and underlies the expression of a biological clock known as the food entrained oscillator (FEO). Liver is the organ that reacts most rapidly to food restriction by adjusting the functional relationship between the molecular circadian clock and the metabolic networks. γ-Aminobutyric acid (GABA) is a signaling molecule in the liver, and able to modulate the cell cycle and apoptosis. This study was aimed at characterizing the expression and activity of the mostly mitochondrial enzyme GABA transaminase (GABA-T) during DRF/FEO expression. We found that DRF promotes a sustained increase of GABA-T in the liver homogenate and mitochondrial fraction throughout the entire day-night cycle. The higher amount of GABA-T promoted by DRF was not associated to changes in GABA-T mRNA or GABA-T activity. The GABA-T activity in the mitochondrial fraction even tended to decrease during the light period. We concluded that DRF influences the daily variations of GABA-T mRNA levels, stability, and catalytic activity of GABA-T. These data suggest that the liver GABAergic system responds to a metabolic challenge such as DRF and the concomitant appearance of the FEO.

  8. GABA, its receptors, and GABAergic inhibition in mouse taste buds

    PubMed Central

    Dvoryanchikov, Gennady; Huang, Yijen A; Barro-Soria, Rene; Chaudhari, Nirupa; Roper, Stephen D.

    2012-01-01

    Taste buds consist of at least three principal cell types that have different functions in processing gustatory signals — glial-like Type I cells, Receptor (Type II) cells, and Presynaptic (Type III) cells. Using a combination of Ca2+ imaging, single cell RT-PCR, and immunostaining, we show that γ-amino butyric acid (GABA) is an inhibitory transmitter in mouse taste buds, acting on GABA-A and GABA-B receptors to suppress transmitter (ATP) secretion from Receptor cells during taste stimulation. Specifically, Receptor cells express GABA-A receptor subunits β2, δ, π, as well as GABA-B receptors. In contrast, Presynaptic cells express the GABA-Aβ3 subunit and only occasionally GABA-B receptors. In keeping with the distinct expression pattern of GABA receptors in Presynaptic cells, we detected no GABAergic suppression of transmitter release from Presynaptic cells. We suggest that GABA may serve function(s) in taste buds in addition to synaptic inhibition. Finally, we also defined the source of GABA in taste buds: GABA is synthesized by GAD65 in Type I taste cells as well as by GAD67 in Presynaptic (Type III) taste cells and is stored in both those two cell types. We conclude that GABA is released during taste stimulation and possibly also during growth and differentiation of taste buds. PMID:21490220

  9. GABA, its receptors, and GABAergic inhibition in mouse taste buds.

    PubMed

    Dvoryanchikov, Gennady; Huang, Yijen A; Barro-Soria, Rene; Chaudhari, Nirupa; Roper, Stephen D

    2011-04-13

    Taste buds consist of at least three principal cell types that have different functions in processing gustatory signals: glial-like (type I) cells, receptor (type II) cells, and presynaptic (type III) cells. Using a combination of Ca2+ imaging, single-cell reverse transcriptase-PCR and immunostaining, we show that GABA is an inhibitory transmitter in mouse taste buds, acting on GABA(A) and GABA(B) receptors to suppress transmitter (ATP) secretion from receptor cells during taste stimulation. Specifically, receptor cells express GABA(A) receptor subunits β2, δ, and π, as well as GABA(B) receptors. In contrast, presynaptic cells express the GABA(A) β3 subunit and only occasionally GABA(B) receptors. In keeping with the distinct expression pattern of GABA receptors in presynaptic cells, we detected no GABAergic suppression of transmitter release from presynaptic cells. We suggest that GABA may serve function(s) in taste buds in addition to synaptic inhibition. Finally, we also defined the source of GABA in taste buds: GABA is synthesized by GAD65 in type I taste cells as well as by GAD67 in presynaptic (type III) taste cells and is stored in both those two cell types. We conclude that GABA is an inhibitory transmitter released during taste stimulation and possibly also during growth and differentiation of taste buds.

  10. GABA(B) receptor modulation of feedforward inhibition through hippocampal neurogliaform cells.

    PubMed

    Price, Christopher J; Scott, Ricardo; Rusakov, Dmitri A; Capogna, Marco

    2008-07-02

    Feedforward inhibition of neurons is a fundamental component of information flow control in the brain. We studied the roles played by neurogliaform cells (NGFCs) of stratum lacunosum moleculare of the hippocampus in providing feedforward inhibition to CA1 pyramidal cells. We recorded from synaptically coupled pairs of anatomically identified NGFCs and CA1 pyramidal cells and found that, strikingly, a single presynaptic action potential evoked a biphasic unitary IPSC (uIPSC), consisting of two distinct components mediated by GABA(A) and GABA(B) receptors. A GABA(B) receptor-mediated unitary response has not previously been observed in hippocampal excitatory neurons. The decay of the GABA(A) receptor-mediated response was slow (time constant = 50 ms), and was tightly regulated by presynaptic GABA(B) receptors. Surprisingly, the GABA(B) receptor ligands baclofen and (2S)-3-{[(1S)-1-(3,4-dichlorophenyl)ethyl]amino-2-hydroxypropyl}(phenylmethyl)phosphinic acid (CGP55845), while affecting the NGFC-mediated uIPSCs, had no effect on action potential-evoked presynaptic Ca2+ signals monitored in individual axonal boutons of NGFCs with two-photon microscopy. In contrast, baclofen clearly depressed presynaptic Ca2+ transients in non-NGF interneurons. Changes in extracellular Ca2+ concentration that mimicked the effects of baclofen or CGP55845 on uIPSCs significantly altered presynaptic Ca2+ transients. Electrophysiological data suggest that GABA(B) receptors expressed by NGFCs contribute to the dynamic control of the excitatory input to CA1 pyramidal neurons from the temporoammonic path. The NGFC-CA1 pyramidal cell connection therefore provides a unique and subtle mechanism to shape the integration time domain for signals arriving via a major excitatory input to CA1 pyramidal cells.

  11. Localization of a GABA transporter to glial cells in the developing and adult olfactory pathway of the moth Manduca sexta1

    PubMed Central

    Oland, Lynne A; Gibson, Nicholas J; Tolbert, Leslie P

    2010-01-01

    Glial cells have several critical roles in the developing and adult olfactory (antennal) lobe of the moth Manduca sexta. Early in development, glial cells occupy discrete regions of the developing olfactory pathway and processes of GABAergic neurons extend into some of these regions. Because GABA is known to have developmental effects in a variety of systems, we explored the possibility that the glial cells express a GABA transporter that could regulate GABA levels to which olfactory neurons and glial cells are exposed. Using an antibody raised against a characterized high-affinity M. sexta GABA transporter with high sequence homology to known mammalian GABA transporters (Mbungu et al., 1995; Umesh and Gill, 2002), we found that the GABA transporter is localized to subsets of centrally derived glial cells during metamorphic adult development. The transporter persists into adulthood in a subset of the neuropil-associated glial cells, but its distribution pattern as determined by light- and electron-microscopic-level immunocytochemistry indicates that it could not serve to regulate GABA concentration in the synaptic cleft. Rather its role is more likely to regulate extracellular GABA levels within the glomerular neuropil. Expression in the sorting zone glial cells disappears after the period of olfactory receptor axon ingrowth, but may be important during ingrowth if GABA regulates axon growth. Glial cells take up GABA, and that uptake can be blocked by DABA. This is the first molecular evidence that the central glial cell population in this pathway is heterogeneous. PMID:20058309

  12. [Effect of acupuncture at different acupoints on expression of hypothalamic GABA and GABA(A) receptor proteins in insomnia rats].

    PubMed

    Zhou, Yan-Li; Gao, Xi-Yan; Wang, Pei-Yu; Ren, Shan

    2012-08-01

    To observe the effect of acupuncture of "Shenmai" (BL 62) and "Zhaohai" (KI 6), "Shenmen" (HT 7), etc. on the expression of hypothalamic gamma-aminobutyric acid (GABA) and GABA(A) receptor (GABA(A)R) proteins in experimental insomnia rats so as to explore its mechanism underlying improving sleeping. Seventy Wistar rats were randomly divided into normal control, model, "Sanyinjiao" (SP6), "Neiguan" (PC 6), "Zusanli" (ST 36), "Shenmen" (HT7), and "Shenmai" (BL 62)-Zhaohai (KI 6, BL 62-KI 6) groups, with 10 rats in each group. Insomnia model was established by intraperitoneal injection of chlorophenylalanine solution (PCPA, 1 mL/100 g). An acupuncture needle was inserted into each of the bilateral HT 7, PC 6, SP 6, ST 36 and BL 62-KI 6 respectively and manipulated for about 1 min, once daily for 7 days. Hypothamic GABA and GABA(A)R protein expressions were detected by immunohistochemistry. The animals' physical ability was evaluated by using pole-climbing test in a water tank. In comparison with the normal control group, the numbers of hypothalamic GABA immunoreaction (IR)- and GABA(A)R IR-positive neurons and the pole-climbing time were reduced significantly in the model group (P < 0.05). While in comparison with the model group, the numbers of hypothalamic GABA IR-positive neurons and those of hypothalamic GABA(A)R IR-positive neurons in the HT 7, PC 6, SP 6, ST 36 and BL 62-KI 6 groups, as well as the pole-climbing duration in the SP 6, ST 36 and BL 62-KI 6 groups were increased considerably (P < 0.05, P < 0.01). The effects of HT 7 and BL 62-KI 6 groups were significantly superior to those of PC 6, ST 36 and SP 6 groups in up-regulating GABA and GABA(A)R expression, and the effect of BL 62-KI 6 group was remarkably better than those of HT 7, PC 6, SP 6 and ST 36 groups in lengthening the pole-climbing time (P < 0.05). Acupuncture can effectively suppress insomnia induced down-regulation of hypothalamic GABA and GABA(A)R in rats and lengthen pole-climbing time

  13. Paracrine GABA and insulin regulate pancreatic alpha cell proliferation in a mouse model of type 1 diabetes.

    PubMed

    Feng, Allen L; Xiang, Yun-Yan; Gui, Le; Kaltsidis, Gesthika; Feng, Qingping; Lu, Wei-Yang

    2017-06-01

    This study aimed to elucidate the mechanism of increased proliferation of alpha cells in recent-onset type 1 diabetes. Pancreatic beta cells express GAD and produce γ-aminobutyric acid (GABA), which inhibits alpha cell secretion of glucagon. We explored the roles of GABA in alpha cell proliferation in conditions corresponding to type 1 diabetes in a mouse model and in vitro. Type 1 diabetes was induced by injecting the mice with streptozotocin (STZ). Some of the STZ-injected mice were treated with GABA (10 mg/kg daily) for 12 days. Isolated pancreatic islets were treated with STZ or STZ together with GABA for 2 days. The effects of GABA treatment on STZ-induced alpha cell proliferation in vivo and in vitro were assessed. The effect of muscimol, a GABA receptor agonist, on αTC1-6 cell proliferation was also examined. STZ injection substantially decreased levels of GAD, GABA and insulin in pancreatic beta cells 12 h after injection; this was followed by an upsurge of phosphorylated mechanistic target of rapamycin (p-mTOR) in the alpha cells at day 1, and a significant increase in alpha cell mass at day 3. Treating STZ-injected mice with GABA largely restored the immunodetectable levels of insulin and GAD in the beta cells and significantly decreased the number of aldehyde dehydrogenase 1 family, member A3 (ALDH1a3)-positive cells, alpha cell mass and hyperglucagonaemia. STZ treatment also increased alpha cell proliferation in isolated islets, which was reversed by co-treatment with GABA. Muscimol, together with insulin, significantly lowered the level of cytosolic Ca 2+ and p-mTOR, and decreased the proliferation rate of αTC1-6 cells. GABA signalling critically controls the alpha cell population in pancreatic islets. Low intraislet GABA may contribute to alpha cell hyperplasia in early type 1 diabetes.

  14. Olfactory bulb short axon cell release of GABA and dopamine produces a temporally biphasic inhibition-excitation response in external tufted cells

    PubMed Central

    Liu, Shaolin; Plachez, Celine; Shao, Zuoyi; Puche, Adam; Shipley, Michael T.

    2013-01-01

    Evidence for co-expression of two or more classic neurotransmitters in neurons has increased but less is known about co-transmission. Ventral tegmental area (VTA) neurons, co-release dopamine (DA), the excitatory transmitter glutamate and the inhibitory transmitter GABA onto target cells in the striatum. Olfactory bulb (OB) short axon cells (SACs) form interglomerular connections and co-express markers for dopamine (DA) and GABA. Using an optogenetic approach we provide evidence that mouse OB SACs release both GABA and DA onto external tufted cells (ETCs) in other glomeruli. Optical activation of channelrhodopsin specifically expressed in DAergic SACs produced a GABAA receptor-mediated monosynaptic inhibitory response followed by DA-D1-like receptor-mediated excitatory response in ETCs. The GABAA receptor-mediated hyperpolarization activates Ih current in ETCs; synaptically released DA increases Ih, which enhances post-inhibitory rebound spiking. Thus, the opposing actions of synaptically released GABA and DA are functionally integrated by Ih to generate an inhibition-to-excitation “switch” in ETCs. Consistent with the established role of Ih in ETC burst firing, we show that endogenous DA release increases ETC spontaneous bursting frequency. ETCs transmit sensory signals to mitral/tufted output neurons and drive intraglomerular inhibition to shape glomerulus output to downstream olfactory networks. GABA and DA co-transmission from SACs to ETCs may play a key role in regulating output coding across the glomerular array. PMID:23407950

  15. GABA (γ-Aminobutyric Acid) Uptake Via the GABA Permease GabP Represses Virulence Gene Expression in Pseudomonas syringae pv. tomato DC3000.

    PubMed

    McCraw, S L; Park, D H; Jones, R; Bentley, M A; Rico, A; Ratcliffe, R G; Kruger, N J; Collmer, A; Preston, G M

    2016-12-01

    The nonprotein amino acid γ-aminobutyric acid (GABA) is the most abundant amino acid in the tomato (Solanum lycopersicum) leaf apoplast and is synthesized by Arabidopsis thaliana in response to infection by the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (hereafter called DC3000). High levels of exogenous GABA have previously been shown to repress the expression of the type III secretion system (T3SS) in DC3000, resulting in reduced elicitation of the hypersensitive response (HR) in the nonhost plant tobacco (Nicotiana tabacum). This study demonstrates that the GABA permease GabP provides the primary mechanism for GABA uptake by DC3000 and that the gabP deletion mutant ΔgabP is insensitive to GABA-mediated repression of T3SS expression. ΔgabP displayed an enhanced ability to elicit the HR in young tobacco leaves and in tobacco plants engineered to produce increased levels of GABA, which supports the hypothesis that GABA uptake via GabP acts to regulate T3SS expression in planta. The observation that P. syringae can be rendered insensitive to GABA through loss of gabP but that gabP is retained by this bacterium suggests that GabP is important for DC3000 in a natural setting, either for nutrition or as a mechanism for regulating gene expression. [Formula: see text] Copyright © 2016 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

  16. Nicotinic receptors and functional regulation of GABA cell microcircuitry in bipolar disorder and schizophrenia.

    PubMed

    Benes, Francine M

    2012-01-01

    Studies of the hippocampus in postmortem brains from patients with schizophrenia and bipolar disorder have provided evidence for a defect of GABAergic interneurons. Significant decreases in the expression of GAD67, a marker for GABA cell function, have been found repeatedly in several different brain regions that include the hippocampus. In this region, nicotinic receptors are thought to play an important role in modulating the activity of GABAergic interneurons by influences of excitatory cholinergic afferents on their activity. In bipolar disorder, this influence appears to be particularly prominent in the stratum oriens of sectors CA3/2 and CA1, two sites where these cells constitute the exclusive neuronal cell type. In sector CA3/2, this layer receives a robust excitatory projection from the basolateral amygdala (BLA) and this is thought to play a central role in regulating GABA cells at this locus. Using laser microdissection, recent studies have focused selectively on these two layers and their associated GABA cells using microarray technology. The results have provided support for the idea that nicotinic cholinergic receptors play a particularly important role in regulating the activity of GABA neurons at these loci by regulating the progression of cell cycle and the repair of damaged DNA. In bipolar disorder, there is a prominent reduction in the expression of mRNAs for several different nicotinic subunit isoforms. These decreases could reflect a diminished influence of this receptor system on these GABA cells, particularly in sector CA3/2 where a preponderance of abnormalities have been observed in postmortem studies. In patients with bipolar disorder, excitatory nicotinic cholinergic fibers from the medial septum may converge with glutamatergic fibers from the BLA on GABAergic interneurons in the stratum oriens of CA3/2 and result in disturbances of their genomic and functional integrity, ones that may induce disruptions of the integration of

  17. Gamma-aminobutyric acid (GABA) stimulates pancreatic cancer growth through overexpressing GABAA receptor pi subunit.

    PubMed

    Takehara, Akio; Hosokawa, Masayo; Eguchi, Hidetoshi; Ohigashi, Hiroaki; Ishikawa, Osamu; Nakamura, Yusuke; Nakagawa, Hidewaki

    2007-10-15

    Gamma-aminobutyric acid (GABA) functions primarily as an inhibitory neurotransmitter in the mature central nervous system, and GABA/GABA receptors are also present in nonneural tissues, including cancer, but their precise function in nonneuronal or cancerous cells has thus far been poorly defined. Through the genome-wide cDNA microarray analysis of pancreatic ductal adenocarcinoma (PDAC) cells as well as subsequent reverse transcription-PCR and Northern blot analyses, we identified the overexpression of GABA receptor pi subunit (GABRP) in PDAC cells. We also found the expression of this peripheral type GABAA receptor subunit in few adult human organs. Knockdown of endogenous GABRP expression in PDAC cells by small interfering RNA attenuated PDAC cell growth, suggesting its essential role in PDAC cell viability. Notably, the addition of GABA into the cell culture medium promoted the proliferation of GABRP-expressing PDAC cells, but not GABRP-negative cells, and GABAA receptor antagonists inhibited this growth-promoting effect by GABA. The HEK293 cells constitutively expressing exogenous GABRP revealed the growth-promoting effect of GABA treatment. Furthermore, GABA treatment in GABRP-positive cells increased intracellular Ca2+ levels and activated the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/Erk) cascade. Clinical PDAC tissues contained a higher level of GABA than normal pancreas tissues due to the up-regulation of glutamate decarboxylase 1 expression, suggesting their autocrine/paracrine growth-promoting effect in PDACs. These findings imply that GABA and GABRP could play important roles in PDAC development and progression, and that this pathway can be a promising molecular target for the development of new therapeutic strategies for PDAC.

  18. Cell and receptor type-specific alterations in markers of GABA neurotransmission in the prefrontal cortex of subjects with schizophrenia.

    PubMed

    Lewis, David A; Hashimoto, Takanori; Morris, Harvey M

    2008-10-01

    Impairments in cognitive control, such as those involved in working memory, are associated with dysfunction of the dorsolateral prefrontal cortex (DLPFC) in individuals with schizophrenia. This dysfunction appears to result, at least in part, from abnormalities in GABA-mediated neurotransmission. In this paper, we review recent findings indicating that the altered DLPFC circuitry in subjects with schizophrenia reflects changes in the expression of genes that encode selective presynaptic and postsynaptic components of GABA neurotransmission. Specifically, using a combination of methods, we found that subjects with schizophrenia exhibited expression deficits in GABA-related transcripts encoding presynaptic regulators of GABA neurotransmission, neuropeptide markers of specific subpopulations of GABA neurons, and certain subunits of the GABA(A) receptor. In particular, alterations in the expression of the neuropeptide somatostatin suggested that GABA neurotransmission is impaired in the Martinotti subset of GABA neurons that target the dendrites of pyramidal cells. In contrast, none of the GABA-related transcripts assessed to date were altered in the DLPFC of monkeys chronically exposed to antipsychotic medications, suggesting that the effects observed in the human studies reflect the disease process and not its treatment. In concert with previous findings, these data suggest that working memory dysfunction in schizophrenia may be attributable to altered GABA neurotransmission in specific DLPFC microcircuits.

  19. GABA and Glutamate Uptake and Metabolism in Retinal Glial (Müller) Cells

    PubMed Central

    Bringmann, Andreas; Grosche, Antje; Pannicke, Thomas; Reichenbach, Andreas

    2013-01-01

    Müller cells, the principal glial cells of the retina, support the synaptic activity by the uptake and metabolization of extracellular neurotransmitters. Müller cells express uptake and exchange systems for various neurotransmitters including glutamate and γ-aminobutyric acid (GABA). Müller cells remove the bulk of extracellular glutamate in the inner retina and contribute to the glutamate clearance around photoreceptor terminals. By the uptake of glutamate, Müller cells are involved in the shaping and termination of the synaptic activity, particularly in the inner retina. Reactive Müller cells are neuroprotective, e.g., by the clearance of excess extracellular glutamate, but may also contribute to neuronal degeneration by a malfunctioning or even reversal of glial glutamate transporters, or by a downregulation of the key enzyme, glutamine synthetase. This review summarizes the present knowledge about the role of Müller cells in the clearance and metabolization of extracellular glutamate and GABA. Some major pathways of GABA and glutamate metabolism in Müller cells are described; these pathways are involved in the glutamate-glutamine cycle of the retina, in the defense against oxidative stress via the production of glutathione, and in the production of substrates for the neuronal energy metabolism. PMID:23616782

  20. Connections between EM2-containing terminals and GABA/μ-opioid receptor co-expressing neurons in the rat spinal trigeminal caudal nucleus

    PubMed Central

    Li, Meng-Ying; Wu, Zhen-Yu; Lu, Ya-Cheng; Yin, Jun-Bin; Wang, Jian; Zhang, Ting; Dong, Yu-Lin; Wang, Feng

    2014-01-01

    Endomorphin-2 (EM2) demonstrates a potent antinociceptive effect via the μ-opioid receptor (MOR). To provide morphological evidence for the pain control effect of EM2, the synaptic connections between EM2-immunoreactive (IR) axonal terminals and γ-amino butyric acid (GABA)/MOR co-expressing neurons in lamina II of the spinal trigeminal caudal nucleus (Vc) were investigated in the rat. Dense EM2-, MOR- and GABA-IR fibers and terminals were mainly observed in lamina II of the Vc. Within lamina II, GABA- and MOR-neuronal cell bodies were also encountered. The results of immunofluorescent histochemical triple-staining showed that approximately 14.2 or 18.9% of GABA-IR or MOR-IR neurons also showed MOR- or GABA-immunopositive staining in lamina II; approximately 45.2 and 36.1% of the GABA-IR and MOR-IR neurons, respectively, expressed FOS protein in their nuclei induced by injecting formalin into the left lower lip of the mouth. Most of the GABA/MOR, GABA/FOS, and MOR/FOS double-labeled neurons made close contacts with EM2-IR fibers and terminals. Immuno-electron microscopy confirmed that the EM2-IR terminals formed synapses with GABA-IR or MOR-IR dendritic processes and neuronal cell bodies in lamina II of the Vc. These results suggest that EM2 might participate in pain transmission and modulation by binding to MOR-IR and GABAergic inhibitory interneuron in lamina II of the Vc to exert inhibitory effect on the excitatory interneuron in lamina II and projection neurons in laminae I and III. PMID:25386121

  1. Immunoreactivity for GABA, GAD65, GAD67 and Bestrophin-1 in the meninges and the choroid plexus: implications for non-neuronal sources for GABA in the developing mouse brain.

    PubMed

    Tochitani, Shiro; Kondo, Shigeaki

    2013-01-01

    Neural progenitors in the developing neocortex, neuroepithelial cells and radial glial cells, have a bipolar shape with a basal process contacting the basal membrane of the meninge and an apical plasma membrane facing the lateral ventricle, which the cerebrospinal fluid is filled with. Recent studies revealed that the meninges and the cerebrospinal fluid have certain roles to regulate brain development. γ-aminobutyric acid (GABA) is a neurotransmitter which appears first during development and works as a diffusible factor to regulate the properties of neural progenitors. In this study, we examined whether GABA can be released from the meninges and the choroid plexus in the developing mouse brain. Immunohistochemical analyses showed that glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67), both of which are GABA-synthesizing enzymes, are expressed in the meninges. The epithelial cells in the choroid plexus express GAD65. GABA immunoreactivity could be observed beneath the basal membrane of the meninge and in the epithelial cells of the choroid plexus. Expression analyses on Bestrophin-1, which is known as a GABA-permeable channel in differentiated glial cells, suggested that the cells in the meninges and the epithelial cells in the choroid plexus have the channels able to permeate non-synaptic GABA into the extracellular space. Further studies showed that GAD65/67-expressing meningeal cells appear in a manner with rostral to caudal and lateral to dorsal gradient to cover the entire neocortex by E14.5 during development, while the cells in the choroid plexus in the lateral ventricle start to express GAD65 on E11-E12, the time when the choroid plexus starts to develop in the developing brain. These results totally suggest that the meninges and the choroid plexus can work as non-neuronal sources for ambient GABA which can modulate the properties of neural progenitors during neocortical development.

  2. Olfactory bulb short axon cell release of GABA and dopamine produces a temporally biphasic inhibition-excitation response in external tufted cells.

    PubMed

    Liu, Shaolin; Plachez, Celine; Shao, Zuoyi; Puche, Adam; Shipley, Michael T

    2013-02-13

    Evidence for coexpression of two or more classic neurotransmitters in neurons has increased, but less is known about cotransmission. Ventral tegmental area (VTA) neurons corelease dopamine (DA), the excitatory transmitter glutamate, and the inhibitory transmitter GABA onto target cells in the striatum. Olfactory bulb (OB) short axon cells (SACs) form interglomerular connections and coexpress markers for DA and GABA. Using an optogenetic approach, we provide evidence that mouse OB SACs release both GABA and DA onto external tufted cells (ETCs) in other glomeruli. Optical activation of channelrhodopsin specifically expressed in DAergic SACs produced a GABA(A) receptor-mediated monosynaptic inhibitory response, followed by DA-D(1)-like receptor-mediated excitatory response in ETCs. The GABA(A) receptor-mediated hyperpolarization activates I(h) current in ETCs; synaptically released DA increases I(h), which enhances postinhibitory rebound spiking. Thus, the opposing actions of synaptically released GABA and DA are functionally integrated by I(h) to generate an inhibition-to-excitation "switch" in ETCs. Consistent with the established role of I(h) in ETC burst firing, we show that endogenous DA release increases ETC spontaneous bursting frequency. ETCs transmit sensory signals to mitral/tufted output neurons and drive intraglomerular inhibition to shape glomerulus output to downstream olfactory networks. GABA and DA cotransmission from SACs to ETCs may play a key role in regulating output coding across the glomerular array.

  3. Glutamate modulation of GABA transport in retinal horizontal cells of the skate

    PubMed Central

    Kreitzer, Matthew A; Andersen, Kristen A; Malchow, Robert Paul

    2003-01-01

    Transport of the amino acid GABA into neurons and glia plays a key role in regulating the effects of GABA in the vertebrate retina. We have examined the modulation of GABA-elicited transport currents of retinal horizontal cells by glutamate, the likely neurotransmitter of vertebrate photoreceptors. Enzymatically isolated external horizontal cells of skate were examined using whole-cell voltage-clamp techniques. GABA (1 mm) elicited an inward current that was completely suppressed by the GABA transport inhibitors tiagabine (10 μm) and SKF89976-A (100 μm), but was unaffected by 100 μm picrotoxin. Prior application of 100 μm glutamate significantly reduced the GABA-elicited current. Glutamate depressed the GABA dose-response curve without shifting the curve laterally or altering the voltage dependence of the current. The ionotropic glutamate receptor agonists kainate and AMPA also reduced the GABA-elicited current, and the effects of glutamate and kainate were abolished by the ionotropic glutamate receptor antagonist 6-cyano-7-nitroquinoxaline. NMDA neither elicited a current nor modified the GABA-induced current, and metabotropic glutamate analogues were also without effect. Inhibition of the GABA-elicited current by glutamate and kainate was reduced when extracellular calcium was removed and when recording pipettes contained high concentrations of the calcium chelator BAPTA. Caffeine (5 mm) and thapsigargin (2 nm), agents known to alter intracellular calcium levels, also reduced the GABA-elicited current, but increases in calcium induced by depolarization alone did not. Our data suggest that glutamate regulates GABA transport in retinal horizontal cells through a calcium-dependent process, and imply a close physical relationship between calcium-permeable glutamate receptors and GABA transporters in these cells. PMID:12562999

  4. GABA stimulates human hepatocellular carcinoma growth through overexpressed GABAA receptor theta subunit

    PubMed Central

    Li, Yue-Hui; Liu, Yan; Li, Yan-Dong; Liu, Yan-Hong; Li, Feng; Ju, Qiang; Xie, Ping-Li; Li, Guan-Cheng

    2012-01-01

    AIM: To investigate the function of gamma-aminobutyric acid (GABA) and gamma-aminobutyric acid A receptor θ subunit (GABRQ) in hepatocellular carcinoma (HCC). METHODS: Semiquantitative polymerase chain reaction was used for detecting the expression of GABRQ receptor among HCC cell line HepG2, normal liver cell line L-02, non-malignant Chang’s liver cells, 8 samples of HCC tissues and paired non-cancerous tissues. HepG2 cells were treated with GABA at serial concentrations (0, 1, 10, 20, 40 and 60 μmol/L), and their proliferating abilities were analyzed with the methyl thiazolyl tetrazolium assay, cell cycle analysis and tumor implanted in nude mice. Small interfering RNA was used for knocking down the endogenous GABRQ in HepG2. Proliferating abilities of these cells treated with or without GABA were analyzed. RESULTS: We identified the overexpression of GABRQ in HCC cell lines and half of the tested HCC tissues. Knockdown of endogenous GABRQ expression in HepG2 attenuated HCC cell growth, suggesting its role in HCC cell viability. We studied the effect of GABA in the proliferation of GABRQ-positive cell lines in vitro and in vivo, and found that GABA increased HCC growth in a dose-dependent manner. Notably, the addition of GABA into the cell culture medium promoted the proliferation of GABRQ-expressing HepG2 cells, but not GABRQ-knockdown HepG2 cells, which means that GABA stimulates HepG2 cell growth through GABRQ. CONCLUSION: GABRQ play important roles in HCC development and progression and could be a promising molecular target for the development of new diagnostic and therapeutic strategies of HCC. PMID:22690081

  5. Immunoreactivity for GABA, GAD65, GAD67 and Bestrophin-1 in the Meninges and the Choroid Plexus: Implications for Non-Neuronal Sources for GABA in the Developing Mouse Brain

    PubMed Central

    Tochitani, Shiro; Kondo, Shigeaki

    2013-01-01

    Neural progenitors in the developing neocortex, neuroepithelial cells and radial glial cells, have a bipolar shape with a basal process contacting the basal membrane of the meninge and an apical plasma membrane facing the lateral ventricle, which the cerebrospinal fluid is filled with. Recent studies revealed that the meninges and the cerebrospinal fluid have certain roles to regulate brain development. γ-aminobutyric acid (GABA) is a neurotransmitter which appears first during development and works as a diffusible factor to regulate the properties of neural progenitors. In this study, we examined whether GABA can be released from the meninges and the choroid plexus in the developing mouse brain. Immunohistochemical analyses showed that glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67), both of which are GABA-synthesizing enzymes, are expressed in the meninges. The epithelial cells in the choroid plexus express GAD65. GABA immunoreactivity could be observed beneath the basal membrane of the meninge and in the epithelial cells of the choroid plexus. Expression analyses on Bestrophin-1, which is known as a GABA-permeable channel in differentiated glial cells, suggested that the cells in the meninges and the epithelial cells in the choroid plexus have the channels able to permeate non-synaptic GABA into the extracellular space. Further studies showed that GAD65/67-expressing meningeal cells appear in a manner with rostral to caudal and lateral to dorsal gradient to cover the entire neocortex by E14.5 during development, while the cells in the choroid plexus in the lateral ventricle start to express GAD65 on E11–E12, the time when the choroid plexus starts to develop in the developing brain. These results totally suggest that the meninges and the choroid plexus can work as non-neuronal sources for ambient GABA which can modulate the properties of neural progenitors during neocortical development. PMID:23437266

  6. Aluminum-Activated Malate Transporters Can Facilitate GABA Transport.

    PubMed

    Ramesh, Sunita A; Kamran, Muhammad; Sullivan, Wendy; Chirkova, Larissa; Okamoto, Mamoru; Degryse, Fien; McLaughlin, Michael; Gilliham, Matthew; Tyerman, Stephen D

    2018-05-01

    Plant aluminum-activated malate transporters (ALMTs) are currently classified as anion channels; they are also known to be regulated by diverse signals, leading to a range of physiological responses. Gamma-aminobutyric acid (GABA) regulation of anion flux through ALMT proteins requires a specific amino acid motif in ALMTs that shares similarity with a GABA binding site in mammalian GABA A receptors. Here, we explore why TaALMT1 activation leads to a negative correlation between malate efflux and endogenous GABA concentrations ([GABA] i ) in both wheat ( Triticum aestivum ) root tips and in heterologous expression systems. We show that TaALMT1 activation reduces [GABA] i because TaALMT1 facilitates GABA efflux but GABA does not complex Al 3+ TaALMT1 also leads to GABA transport into cells, demonstrated by a yeast complementation assay and via 14 C-GABA uptake into TaALMT1 -expressing Xenopus laevis oocytes; this was found to be a general feature of all ALMTs we examined. Mutation of the GABA motif (TaALMT1 F213C ) prevented both GABA influx and efflux, and resulted in no correlation between malate efflux and [GABA] i We conclude that ALMTs are likely to act as both GABA and anion transporters in planta. GABA and malate appear to interact with ALMTs in a complex manner to regulate each other's transport, suggestive of a role for ALMTs in communicating metabolic status. © 2018 American Society of Plant Biologists. All rights reserved.

  7. MEDU-05. THE ROLE OF GABA METABOLISM IN MEDULLOBLASTOMA

    PubMed Central

    Martirosian, Vahan; Deshpande, Krutika; Shackelford, Gregory; Julian, Alex; Lin, Michelle; Erdreich-Epstein, Anat; Chen, Thomas; Neman, Josh

    2017-01-01

    Abstract BACKGROUND: Brain tumors are the most common cause of childhood oncological death, and medulloblastoma (originating in the cerebellum) is the most common malignant pediatric brain tumor. In the microenvironment of the brain, especially the cerebellum, variables related to GABA, the major inhibitory neurotransmitter in the nervous system, are particularly prominent. Abnormal GABAergic Receptor activation has been described in in aggressive MYC-driven Group 3 medulloblastoma. However these studies did not look at the metabolic contribution of GABA for the development of medulloblastomas. In addition to its role in neurotransmission through GABA receptor, GABA can act as a trophic factor during nervous system development to influence cellular events including proliferation, migration, differentiation, synapse maturation, and cell death. Under conditions that inhibit the tricarboxylic acid cycle (TCA), impair respiration, and enhance the accumulation of reactive oxygen intermediates, GABA can be used as an NADH energy source for growth through the GABA-shunt pathway regulators (ABAT, SSADH, GAT-1, GAT-3). Therefore, we hypothesize that blocking GABA-metabolic-shunt will lead to growth suppression and invasiveness of medulloblastoma in the cerebellar GABA-rich microenvironment. RESULTS: Our results show RNA microarray from patient medulloblastoma tissue have high expression of GABA-shunt regulators with ~3-fold increase in the expression of ABAT in MYC amplified versus non-amplified MYC tumors. When medulloblastomas were supplemented with GABA, there was a significant fold change in expression of GABA-shunt mediators and induction of large and stable tumor spheres with Epithelial-Mesenchymal Transition gene expression signature. We next investigated whether a novel perrilyl alcohol-based small molecule NEO216 targeted the GABA-shunt metabolic pathway. NEO216 administration significantly reduced GABA-mediated NADH levels, reversed EMT-profiling, leading to loss

  8. Endothelial cell-derived GABA signaling modulates neuronal migration and postnatal behavior

    PubMed Central

    Li, Suyan; Kumar T, Peeyush; Joshee, Sampada; Kirschstein, Timo; Subburaju, Sivan; Khalili, Jahan S; Kloepper, Jonas; Du, Chuang; Elkhal, Abdallah; Szabó, Gábor; Jain, Rakesh K; Köhling, Rüdiger; Vasudevan, Anju

    2018-01-01

    The cerebral cortex is essential for integration and processing of information that is required for most behaviors. The exquisitely precise laminar organization of the cerebral cortex arises during embryonic development when neurons migrate successively from ventricular zones to coalesce into specific cortical layers. While radial glia act as guide rails for projection neuron migration, pre-formed vascular networks provide support and guidance cues for GABAergic interneuron migration. This study provides novel conceptual and mechanistic insights into this paradigm of vascular-neuronal interactions, revealing new mechanisms of GABA and its receptor-mediated signaling via embryonic forebrain endothelial cells. With the use of two new endothelial cell specific conditional mouse models of the GABA pathway (Gabrb3ΔTie2-Cre and VgatΔTie2-Cre), we show that partial or complete loss of GABA release from endothelial cells during embryogenesis results in vascular defects and impairs long-distance migration and positioning of cortical interneurons. The downstream effects of perturbed endothelial cell-derived GABA signaling are critical, leading to lasting changes to cortical circuits and persistent behavioral deficits. Furthermore, we illustrate new mechanisms of activation of GABA signaling in forebrain endothelial cells that promotes their migration, angiogenesis and acquisition of blood-brain barrier properties. Our findings uncover and elucidate a novel endothelial GABA signaling pathway in the CNS that is distinct from the classical neuronal GABA signaling pathway and shed new light on the etiology and pathophysiology of neuropsychiatric diseases, such as autism spectrum disorders, epilepsy, anxiety, depression and schizophrenia. PMID:29086765

  9. Cell type specificity of GABA(A) receptor mediated signaling in the hippocampus.

    PubMed

    Semyanov, A

    2003-08-01

    Inhibitory signaling mediated by ionotropic GABA(1) receptors generally acts as a major brake against excessive excitability in the brain. This is especially relevant in epilepsy-prone structures such as the hippocampus, in which GABA(A) receptor mediated inhibition is critical in suppressing epileptiform activity. Indeed, potentiating GABA(A) receptor mediated signaling is an important target for antiepileptic drug therapy. GABA(A) receptor mediated inhibition has different roles in the network dependent on the target neuron. Inhibiting principal cells will thus reduce network excitability, whilst inhibiting interneurons will increase network excitability; GABAergic therapeutic agents do not distinguish between these two alternatives, which may explain why, on occasion, GABAergic antiepileptic drugs can be proconvulsant. The importance of the target-cell for the effect of neuroactive drugs has emerged from a number of recent studies. Immunocytochemical data have suggested non-uniform distribution of GABA(A) receptor subunits among hippocampal interneurons and pyramidal cells. This has been confirmed by subsequent electropharmacological data. These have demonstrated that compounds which act on GABA(A) receptors or the extracellular GABA concentration can have distinct effects in different neuronal populations. Recently, it has also been discovered that presynaptic glutamate heteroreceptors can modulate GABA release in the hippocampus in a postsynaptic cell-specific manner. Since systemically administrated drugs may act on different neuronal subtypes, they can exhibit paradoxical effects. Distinguishing compounds that have target specific effects on GABAergic signaling may lead to novel and more effective treatments against epilepsy.

  10. Conserved regional patterns of GABA-related transcript expression in the neocortex of subjects with schizophrenia.

    PubMed

    Hashimoto, Takanori; Bazmi, H Holly; Mirnics, Karoly; Wu, Qiang; Sampson, Allan R; Lewis, David A

    2008-04-01

    Individuals with schizophrenia exhibit disturbances in a number of cognitive, affective, sensory, and motor functions that depend on the circuitry of different cortical areas. The cognitive deficits associated with dysfunction of the dorsolateral prefrontal cortex result, at least in part, from abnormalities in GABA neurotransmission, as reflected in a specific pattern of altered expression of GABA-related genes. Consequently, the authors sought to determine whether this pattern of altered gene expression is restricted to the dorsolateral prefrontal cortex or could also contribute to the dysfunction of other cortical areas in subjects with schizophrenia. Real-time quantitative polymerase chain reaction was used to assess the levels of eight GABA-related transcripts in four cortical areas (dorsolateral prefrontal cortex, anterior cingulate cortex, and primary motor and primary visual cortices) of subjects (N=12) with schizophrenia and matched normal comparison subjects. Expression levels of seven transcripts were lower in subjects with schizophrenia, with the magnitude of reduction for each transcript comparable across the four areas. The largest reductions were detected for mRNA encoding somatostatin and parvalbumin, followed by moderate decreases in mRNA expression for the 67-kilodalton isoform of glutamic acid decarboxylase, the GABA membrane transporter GAT-1, and the alpha 1 and delta subunits of GABA(A) receptors. In contrast, the expression of calretinin mRNA did not differ between the subject groups in any of the four areas. Because the areas examined represent the major functional domains (e.g., association, limbic, motor, and sensory) of the cerebral cortex, our findings suggest that a conserved set of molecular alterations affecting GABA neurotransmission contribute to the pathophysiology of different clinical features of schizophrenia.

  11. Modulation of GABA receptors expressed in Xenopus oocytes by 13-L-hydroxylinoleic acid and food additives.

    PubMed

    Aoshima, H; Tenpaku, Y

    1997-12-01

    To study the effects of 13-L-hydroxylinoleic acid (LOH) and food additives on gamma-aminobutyric acid (GABA) receptors, ionotropic GABA receptors were expressed in Xenopus oocytes by injecting mRNAs prepared from rat whole brain. LOH, which was prepared by reduction of 13-L-hydroperoxylinoleic acid (LOOH), inhibited the response of GABA receptors in the presence of high concentrations of GABA. LOH also inhibited nicotinic acetylcholine, glycine, and kainate receptors, while it had little effect on NMDA receptors expressed in Xenopus oocytes. However, LOH potentiated the response of GABA receptors as well as LOOH in the presence of low concentrations of GABA, possibly increasing the affinity of GABA for the receptors, while linoleic acid did not. Since some modification of the compounds seemed to change their effects on GABA receptors, the responses of GABA receptors elicited by 10 microM GABA were measured in the presence of compounds with various kinds of functional groups or the structural isomers of pentanol. Potentiation of GABA receptors depended strongly on the species of functional groups and also depended on the structure of the isomers. Then effects of various kinds of food additives on GABA receptors were also examined; perfumes such as alcohols or esters potentiated the responses strongly, while hexylamine, nicotinamide, or caffeine inhibited the responses, mainly in a competitive manner, and vanillin inhibited the responses noncompetitively. These results suggest the possibility that production of LOOH and LOH, or intake of much of some food additives, modulates the neural transmission in the brain, especially through ionotropic GABA receptors and changes the frame of the human mind, as alcohol or tobacco does.

  12. [Schizophrenia and cortical GABA neurotransmission].

    PubMed

    Hashimoto, Takanori; Matsubara, Takuro; Lewis, David A

    2010-01-01

    Individuals with schizophrenia show disturbances in a number of brain functions that regulate cognitive, affective, motor, and sensory processing. The cognitive deficits associated with dysfunction of the dorsolateral prefrontal cortex result, at least in part, from abnormalities in GABA neurotransmission, as reflected in a specific pattern of altered expression of GABA-related molecules. First, mRNA levels for the 67-kilodalton isoform of glutamic acid decarboxylase (GAD67), an enzyme principally responsible for GABA synthesis, and the GABA membrane transporter GAT1, which regulates the reuptake of synaptically released GABA, are decreased in a subset of GABA neurons. Second, affected GABA neurons include those that express the calcium-binding protein parvalbumin (PV), because PV mRNA levels are decreased in the prefrontal cortex of subjects with schizophrenia and GAD67 mRNA is undetectable in almost half of PV-containing neurons. These changes are accompanied by decreased GAT1 expression in the presynaptic terminals of PV-containing neurons and by increased postsynaptic GABA-A receptor alpha2 subunit expression at the axon initial segments of pyramidal neurons. These findings indicate decreased GABA synthesis/release by PV-containing GABA neurons and compensatory changes at synapses formed by these neurons. Third, another subset of GABA neurons that express the neuropeptide somatostatin (SST) also appear to be affected because their specific markers, SST and neuropeptide Y mRNAs, are decreased in a manner highly correlated with the decreases in GAD67 mRNA. Finally, mRNA levels for GABA-A receptor subunits for synaptic (alpha1 and gamma2) and extra-synaptic (delta) receptors are decreased, indicating alterations in both synaptic and extra-synaptic GABA neurotransmission. Together, this pattern of changes indicates that the altered GABA neurotransmission is specific to PV-containing and SST-containing GABA neuron subsets and involves both synaptic and extra

  13. Altered cortical expression of GABA-related genes in schizophrenia: illness progression vs developmental disturbance.

    PubMed

    Hoftman, Gil D; Volk, David W; Bazmi, H Holly; Li, Siyu; Sampson, Allan R; Lewis, David A

    2015-01-01

    Schizophrenia is a neurodevelopmental disorder with altered expression of GABA-related genes in the prefrontal cortex (PFC). However, whether these gene expression abnormalities reflect disturbances in postnatal developmental processes before clinical onset or arise as a consequence of clinical illness remains unclear. Expression levels for 7 GABA-related transcripts (vesicular GABA transporter [vGAT], GABA membrane transporter [GAT1], GABAA receptor subunit α1 [GABRA1] [novel in human and monkey cohorts], glutamic acid decarboxylase 67 [GAD67], parvalbumin, calretinin, and somatostatin [previously reported in human cohort, but not in monkey cohort]) were quantified in the PFC from 42 matched pairs of schizophrenia and comparison subjects and from 49 rhesus monkeys ranging in age from 1 week postnatal to adulthood. Levels of vGAT and GABRA1, but not of GAT1, messenger RNAs (mRNAs) were lower in the PFC of the schizophrenia subjects. As previously reported, levels of GAD67, parvalbumin, and somatostatin, but not of calretinin, mRNAs were also lower in these subjects. Neither illness duration nor age accounted for the levels of the transcripts with altered expression in schizophrenia. In monkey PFC, developmental changes in expression levels of many of these transcripts were in the opposite direction of the changes observed in schizophrenia. For example, mRNA levels for vGAT, GABRA1, GAD67, and parvalbumin all increased with age. Together with published reports, these findings support the interpretation that the altered expression of GABA-related transcripts in schizophrenia reflects a blunting of normal postnatal development changes, but they cannot exclude a decline during the early stages of clinical illness. © The Author 2013. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  14. Single channel analysis of the blocking actions of BIDN and fipronil on a Drosophila melanogaster GABA receptor (RDL) stably expressed in a Drosophila cell line

    PubMed Central

    Grolleau, Françoise; Sattelle, David B

    2000-01-01

    Single channel recordings were obtained from a Drosophila S2 cell line stably expressing the wild-type RDLac Drosophila melanogaster homomer-forming ionotropic GABA receptor subunit, a product of the resistance to dieldrin gene, Rdl. GABA (50 μM) was applied by pressure ejection to outside-out patches from S2-RDL cells at a holding potential of −60 mV. The resulting inward current was completely blocked by 100 μM picrotoxin (PTX). The unitary current-voltage relationship was linear at negative potentials but showed slight inward rectification at potentials more positive than 0 mV. The reversal potential of the current (EGABA=−1.4 mV) was close to the calculated chloride equilibrium potential. The single channel conductance elicited by GABA was 36 pS. A 71 pS conductance channel was also observed when the duration of the pulse, used to eject GABA, was longer than 80 ms. The mean open time distribution of the unitary events was fitted best by two exponential functions suggesting two open channel states. When either 1 μM fipronil or 1 μM BIDN was present in the external saline, the GABA-gated channels were completely blocked. When BIDN or fipronil was applied at a concentration close to the IC50 value for suppression of open probability (281 nM, BIDN; 240 nM, fipronil), the duration of channel openings was shortened. In addition, the blocking action of BIDN resulted in the appearance of a novel channel conductance (17 pS). The effects of co-application of BIDN and fipronil were examined. Co-application of BIDN (300 nM) with various concentrations (100–1000 nM) of fipronil resulted in an additional BIDN-induced dose-dependent reduction of the maximum Po value. Thus both BIDN and fipronil shorten the duration of wild-type RDLac GABA receptor channel openings but appear to act at distinct sites. PMID:10952672

  15. Role of glutamic acid decarboxylase 67 in regulating cortical parvalbumin and GABA membrane transporter 1 expression: implications for schizophrenia.

    PubMed

    Curley, Allison A; Eggan, Stephen M; Lazarus, Matt S; Huang, Z Josh; Volk, David W; Lewis, David A

    2013-02-01

    Markers of GABA neurotransmission are altered in multiple regions of the neocortex in individuals with schizophrenia. Lower levels of glutamic acid decarboxylase 67 (GAD67) mRNA and protein, which is responsible for most cortical GABA synthesis, are accompanied by lower levels of GABA membrane transporter 1 (GAT1) mRNA. These alterations are thought to be most prominent in the parvalbumin (PV)-containing subclass of interneurons, which also contain lower levels of PV mRNA. Since GAT1 and PV each reduce the availability of GABA at postsynaptic receptors, lower levels of GAT1 and PV mRNAs have been hypothesized to represent compensatory responses to an upstream reduction in cortical GABA synthesis in schizophrenia. However, such cause-and-effect hypotheses cannot be directly tested in a human illness. Consequently, we used two mouse models with reduced GAD67 expression specifically in PV neurons (PV(GAD67+/-)) or in all interneurons (GABA(GAD67+/-)) and quantified GAD67, GAT1 and PV mRNA levels using methods identical to those employed in studies of schizophrenia. Cortical levels of PV or GAT1 mRNAs were not altered in PV(GAD67+/-) mice during postnatal development or in adulthood. Furthermore, cellular analyses confirmed the predicted reduction in GAD67 mRNA, but failed to show a deficit in PV mRNA in these animals. Levels of PV and GAT1 mRNAs were also unaltered in GABA(GAD67+/-) mice. Thus, mouse lines with cortical reductions in GAD67 mRNA that match or exceed those present in schizophrenia, and that differ in the developmental timing and cell type-specificity of the GAD67 deficit, failed to provide proof-of-concept evidence that lower PV and GAT1 expression in schizophrenia are a consequence of lower GAD67 expression. Together, these findings suggest that the correlated decrements in cortical GAD67, PV and GAT1 mRNAs in schizophrenia may be a common consequence of some other upstream factor. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Restoration of GABA production machinery in Lactobacillus brevis by accessible carbohydrates, anaerobiosis and early acidification.

    PubMed

    Wu, Qinglong; Shah, Nagendra P

    2018-02-01

    Lactobacillus brevis is an efficient cell factory for producing bioactive γ-aminobutyric acid (GABA) by its gad operon-encoded glutamic acid decarboxylase (GAD) system. However, little mechanistic insights have been reported on the effects of carbohydrate, oxygen and early acidification on GABA production machinery in Lb. brevis. In the present study, GABA production from Lb. brevis was enhanced by accessible carbohydrates. Fast growth of this organism was stimulated by maltose and xylose. However, its GABA production was highly suppressed by oxygen exposure, but was fully restored by anaerobiosis that up-regulated the expression of gad operon in Lb. brevis cells. Although the level of cytosolic acidity was suitable for the functioning of GadA and GadB, early acidification of the medium (ipH 5 and ipH 4) restored GABA synthesis strictly in aerated cells of Lb. brevis because the expression of gad operon was not up-regulated in them. We conclude that GABA production machinery in Lb. brevis could be restored by accessible carbohydrates, anaerobiosis and early acidification. This will be of interest for controlling fermentation for synthesis of GABA and manufacturing GABA-rich fermented vegetables. Copyright © 2017. Published by Elsevier Ltd.

  17. Somato-synaptic variation of GABA(A) receptors in cultured murine cerebellar granule cells: investigation of the role of the alpha6 subunit.

    PubMed

    Mellor, J R; Wisden, W; Randall, A D

    2000-07-10

    Electrophysiological investigation of cultured cerebellar murine granule cells revealed differences between the GABA(A) receptors at inhibitory synapses and those on the cell body. Specifically, mIPSCs decayed more rapidly than cell body receptors deactivated, the mean single channel conductance at the synapse (32 pS) was greater than that at cell body (21 pS) and only cell body receptors were sensitive to Zn(2+) (150 microM), which depressed response amplitude by 82+/-5% and almost doubled the rate of channel deactivation. The GABA(A) receptor alpha6 subunit is selectively expressed in cerebellar granule cells. Although concentrated at synapses, it is also found on extrasynaptic membranes. Using a mouse line (Deltaalpha6lacZ) lacking this subunit, we investigated its role in the somato-synaptic differences in GABA(A) receptor function. All differences between cell body and synaptic GABA(A) receptors observed in wild-type (WT) granule cells persisted in Deltaalpha6lacZ cells, thus demonstrating that they are not specifically due to the cellular distribution of the alpha6 subunit. However, mIPSCs from WT and Deltaalpha6lacZ cells differed in both their kinetics (faster decay in WT cells) and underlying single channel conductance (32 pS WT, 25 pS Deltaalpha6lacZ). This provides good evidence for a functional contribution of the alpha6 subunit to postsynaptic GABA(A) receptors in these cells. Despite this, deactivation kinetics of mIPSCs in WT and Deltaalpha6lacZ granule cells exhibited similar benzodiazepene (BDZ) sensitivity. This suggests that the enhanced BDZ-induced ataxia seen in Deltaalpha6lacZ mice may reflect physiological activity at extrasynaptic receptors which, unlike those at synapses, display differential BDZ-sensitivity in WT and Deltaalpha6lacZ granule cells (Jones, A.M., Korpi, E.R., McKernan, R.M., Nusser, Z., Pelz, R., Makela, R., Mellor, J.R., Pollard, S., Bahn, S., Stephenson, F.A., Randall, A.D., Sieghart, W., Somogyi, P., Smith, A.J.H., Wisden

  18. Role of GABA Release From Leptin Receptor-Expressing Neurons in Body Weight Regulation

    PubMed Central

    Xu, Yuanzhong; O'Brien, William G.; Lee, Cheng-Chi; Myers, Martin G.

    2012-01-01

    It is well established that leptin regulates energy balance largely through isoform B leptin receptor-expressing neurons (LepR neurons) in the brain and that leptin activates one subset of LepR neurons (leptin-excited neurons) while inhibiting the other (leptin-inhibited neurons). However, the neurotransmitters released from LepR neurons that mediate leptin action in the brain are not well understood. Previous results demonstrate that leptin mainly acts on γ-aminobutyric acid (GABA)ergic neurons to reduce body weight, and that leptin activates proopiomelanocortin neuron activity by reducing GABA release onto these neurons, suggesting a body weight-promoting role for GABA released from leptin-inhibited neurons. To directly examine the role of GABA release from LepR neurons in body weight regulation, mice with disruption of GABA release specifically from LepR neurons were generated by deletion of vesicular GABA transporter in LepR neurons. Interestingly, these mice developed mild obesity on chow diet and were sensitive to diet-induced obesity, which were associated with higher food intake and lower energy expenditure. Moreover, these mice showed blunted responses in both food intake and body weight to acute leptin administration. These results demonstrate that GABA plays an important role in mediating leptin action. In combination with the previous studies that leptin reduces GABA release onto proopiomelanocortin neurons through leptin-inhibited neurons and that disruption of GABA release from agouti gene-related protein neurons, one subset of LepR-inhibited neurons, leads to a lean phenotype, our results suggest that, under our experimental conditions, GABA release from leptin-excited neuron dominates over leptin-inhibited ones. PMID:22334723

  19. Valerian Inhibits Rat Hepatocarcinogenesis by Activating GABA(A) Receptor-Mediated Signaling

    PubMed Central

    Kakehashi, Anna; Kato, Ayumi; Ishii, Naomi; Wei, Min; Morimura, Keiichirou; Fukushima, Shoji; Wanibuchi, Hideki

    2014-01-01

    Valerian is widely used as a traditional medicine to improve the quality of sleep due to interaction of several active components with the γ-aminobutyric acid (GABA) A receptor (GABA(A)R) system. Recently, activation of GABA signaling in stem cells has been reported to suppress cell cycle progression in vivo. Furthermore, possible inhibitory effects of GABA(A)R agonists on hepatocarcinogenesis have been reported. The present study was performed to investigate modulating effects of Valerian on hepatocarcinogenesis using a medium-term rat liver bioassay. Male F344 rats were treated with one of the most powerful Valerian species (Valeriana sitchensis) at doses of 0, 50, 500 and 5000 ppm in their drinking water after initiation of hepatocarcinogenesis with diethylnitrosamine (DEN). Formation of glutathione S-transferase placental form positive (GST-P+) foci was significantly inhibited by Valerian at all applied doses compared with DEN initiation control rats. Generation of 8-hydroxy-2′-deoxyguanosine in the rat liver was significantly suppressed by all doses of Valerian, likely due to suppression of Nrf2, CYP7A1 and induction of catalase expression. Cell proliferation was significantly inhibited, while apoptosis was induced in areas of GST-P+ foci of Valerian groups associated with suppression of c-myc, Mafb, cyclin D1 and induction of p21Waf1/Cip1, p53 and Bax mRNA expression. Interestingly, expression of the GABA(A)R alpha 1 subunit was observed in GST-P+ foci of DEN control rats, with significant elevation associated with Valerian treatment. These results indicate that Valerian exhibits inhibitory effects on rat hepatocarcinogenesis by inhibiting oxidative DNA damage, suppressing cell proliferation and inducing apoptosis in GST-P+ foci by activating GABA(A)R-mediated signaling. PMID:25419570

  20. Neonatal maternal separation delays the GABA excitatory-to-inhibitory functional switch by inhibiting KCC2 expression.

    PubMed

    Furukawa, Minami; Tsukahara, Takao; Tomita, Kazuo; Iwai, Haruki; Sonomura, Takahiro; Miyawaki, Shouichi; Sato, Tomoaki

    2017-11-25

    The excitatory-to-inhibitory functional switch of γ-aminobutyric acid (GABA; GABA switch), which normally occurs in the first to the second postnatal week in the hippocampus, is necessary for the development of appropriate central nervous system function. A deficit in GABAergic inhibitory function could cause excitatory/inhibitory (E/I) neuron imbalance that is found in many neurodegenerative disorders. In the present study, we examined whether neonatal stress can affect the timing of the GABA functional switch and cause disorders during adolescence. Neonatal stress was induced in C57BL/6J male mouse pups by maternal separation (MS) on postnatal days (PND) 1-21. Histological quantification of K + -Cl - co-transporter (KCC2) and Ca 2+ imaging were performed to examine the timing of the GABA switch during the MS period. To evaluate the influence of neonatal MS on adolescent hippocampal function, we quantified KCC2 expression and evaluated hippocampal-related behavioral tasks at PND35-38. We showed that MS delayed the timing of the GABA switch in the hippocampus and inhibited the increase in membrane KCC2 expression, with KCC2 expression inhibition persisting until adolescence. Behavioral tests showed impaired cognition, declined attention, hyperlocomotion, and aggressive character in maternally separated mice. Taken together, our results show that neonatal stress delayed the timing of the GABA switch, which could change the E/I balance and cause neurodegenerative disorders in later life. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Short-term dopaminergic regulation of GABA release in dopamine deafferented caudate-putamen is not directly associated with glutamic acid decarboxylase gene expression.

    PubMed

    O'Connor, W T; Lindefors, N; Brené, S; Herrera-Marschitz, M; Persson, H; Ungerstedt, U

    1991-07-08

    In vivo microdialysis and in situ hybridization were combined to study dopaminergic regulation of gamma-amino butyric acid (GABA) neurons in rat caudate-putamen (CPu). Potassium-stimulated GABA release in CPu was elevated following a dopamine deafferentation. Local perfusion with exogenous dopamine (50 microM) for 3 h via the microdialysis probe attenuated the potassium-stimulated increase in extracellular GABA in CPu. Expression of glutamic acid decarboxylase (GAD) mRNA was also increased in the dopamine deafferented CPu. However, local perfusion with dopamine had no significant attenuating effect on the increased GAD mRNA expression. These findings indicate that dopaminergic regulation of GABA neurons in the dopamine deafferented CPu includes both a short-term effect at the level of GABA release independent of changes in GAD mRNA expression and a long-term modulation at the level of GAD gene expression.

  2. Expression of GABA signaling molecules KCC2, NKCC1, and GAD1 in cortical development and schizophrenia.

    PubMed

    Hyde, Thomas M; Lipska, Barbara K; Ali, Towhid; Mathew, Shiny V; Law, Amanda J; Metitiri, Ochuko E; Straub, Richard E; Ye, Tianzhang; Colantuoni, Carlo; Herman, Mary M; Bigelow, Llewellyn B; Weinberger, Daniel R; Kleinman, Joel E

    2011-07-27

    GABA signaling molecules are critical for both human brain development and the pathophysiology of schizophrenia. We examined the expression of transcripts derived from three genes related to GABA signaling [GAD1 (GAD67 and GAD25), SLC12A2 (NKCC1), and SLC12A5 (KCC2)] in the prefrontal cortex (PFC) and hippocampal formation of a large cohort of nonpsychiatric control human brains (n = 240) across the lifespan (from fetal week 14 to 80 years) and in patients with schizophrenia (n = 30-31), using quantitative RT-PCR. We also examined whether a schizophrenia risk-associated promoter SNP in GAD1 (rs3749034) is related to expression of these transcripts. Our studies revealed that development and maturation of both the PFC and hippocampal formation are characterized by progressive switches in expression from GAD25 to GAD67 and from NKCC1 to KCC2. Previous studies have demonstrated that the former leads to GABA synthesis, and the latter leads to switching from excitatory to inhibitory neurotransmission. In the hippocampal formation, GAD25/GAD67 and NKCC1/KCC2 ratios are increased in patients with schizophrenia, reflecting a potentially immature GABA physiology. Remarkably, GAD25/GAD67 and NKCC1/KCC2 expression ratios are associated with rs3749034 genotype, with risk alleles again predicting a relatively less mature pattern. These findings suggest that abnormalities in GABA signaling critical to brain development contribute to genetic risk for schizophrenia.

  3. GABA signaling stimulates α-cell-mediated β-like cell neogenesis.

    PubMed

    Napolitano, Tiziana; Avolio, Fabio; Vieira, Andhira; Ben-Othman, Nouha; Courtney, Monica; Gjernes, Elisabet; Hadzic, Biljana; Druelle, Noémie; Navarro Sanz, Sergi; Silvano, Serena; Mansouri, Ahmed; Collombat, Patrick

    2017-01-01

    Diabetes is a chronic and progressing disease, the number of patients increasing exponentially, especially in industrialized countries. Regenerating lost insulin-producing cells would represent a promising therapeutic alternative for most diabetic patients. To this end, using the mouse as a model, we reported that GABA, a food supplement, could induce insulin-producing beta-like cell neogenesis offering an attractive and innovative approach for diabetes therapeutics.

  4. GABA dramatically improves glucose tolerance in streptozotocin-induced diabetic rats fed with high-fat diet.

    PubMed

    Sohrabipour, Shahla; Sharifi, Mohammad Reza; Talebi, Ardeshir; Sharifi, Mohammadreza; Soltani, Nepton

    2018-05-05

    Skeletal muscle, hepatic insulin resistance, and beta cell dysfunction are the characteristic pathophysiological features of type 2 diabetes mellitus. GABA has an important role in pancreatic islet cells. The present study attempted to clarify the possible mechanism of GABA to improve glucose tolerance in a model of type 2 diabetes mellitus in rats. Fifty Wistar rats were divided into five groups: NDC that was fed the normal diet, CD which received a high-fat diet with streptozotocin, CD-GABA animals that received GABA via intraperitoneal injection, plus CD-Ins1 and CD-Ins2 groups which were treated with low and high doses of insulin, respectively. Body weight and blood glucose were measured weekly. Intraperitoneal glucose tolerance test (IPGTT), insulin tolerance test (ITT), urine volume, amount of water drinking, and food intake assessments were performed monthly. The hyperinsulinemic euglycemic clamp was done for assessing insulin resistance. Plasma insulin and glucagon were measured. Abdominal fat was measured. Glucagon receptor, Glucose 6 phosphatase, Phosphoenolpyruvate carboxykinase genes expression were evaluated in liver and Glucose transporter 4 (GLUT4) genes expression and protein translocation were evaluated in the muscle. GABA or insulin therapy improved blood glucose, insulin level, IPGTT, ITT, gluconeogenesis pathway, Glucagon receptor, body weight and body fat in diabetic rats. GLUT4 gene and protein expression increased. GABA whose beneficial effect was comparable to that of insulin, also increased glucose infusion rate during an euglycemic clamp. GABA could improve insulin resistance via rising GLUT4 and also decreasing the gluconeogenesis pathway and Glucagon receptor gene expression. Copyright © 2018. Published by Elsevier B.V.

  5. Hypoglycemia induced behavioural deficit and decreased GABA receptor, CREB expression in the cerebellum of streptozoticin induced diabetic rats.

    PubMed

    Sherin, A; Peeyush, K T; Naijil, G; Chinthu, R; Paulose, C S

    2010-11-20

    Intensive glycemic control during diabetes is associated with an increased incidence of hypoglycemia, which is the major barrier in blood glucose homeostasis during diabetes therapy. The CNS neurotransmitters play an important role in the regulation of glucose homeostasis. In the present study, we showed the effects of hypoglycemia in diabetic and non- diabetic rats on motor functions and alterations of GABA receptor and CREB expression in the cerebellum. Cerebellar dysfunction is associated with seizure generation, motor deficits and memory impairment. Scatchard analysis of [(3)H]GABA binding in the cerebellum of diabetic hypoglycemic and control hypoglycemic rats showed significant (P<0.01) decrease in B(max) and K(d) compared to diabetic and control rats. Real-time PCR amplification of GABA receptor subunit GABA(Aα1) and GAD showed significant (P<0.001) down-regulation in the cerebellum of hypoglycemic rats compared to diabetic and control rats. Confocal imaging study confirmed the decreased GABA receptors in hypoglycemic rats. CREB mRNA expression was down-regulated during recurrent hypoglycemia. Both diabetic and non-diabetic hypoglycemic rats showed impaired performance in grid walk test compared to diabetic and control. Impaired GABA receptor and CREB expression along with motor function deficit were more prominent in hypoglycemic rats than hyperglycemic which showed that hypoglycemia is causing more neuronal damage at molecular level. These molecular changes observed during hypo/hyperglycemia contribute to motor and learning deficits which has clinical significance in diabetes treatment. 2010 Elsevier Inc. All rights reserved.

  6. Galanin-Expressing GABA Neurons in the Lateral Hypothalamus Modulate Food Reward and Noncompulsive Locomotion.

    PubMed

    Qualls-Creekmore, Emily; Yu, Sangho; Francois, Marie; Hoang, John; Huesing, Clara; Bruce-Keller, Annadora; Burk, David; Berthoud, Hans-Rudolf; Morrison, Christopher D; Münzberg, Heike

    2017-06-21

    GABA neurons is heterogeneous and largely undefined. Here we introduce LHA Gal neurons as a subset of LHA GABA neurons that lack direct innervation of the ventral tegmental area (VTA). LHA Gal neurons are sufficient to drive motivated feeding and locomotor activity similar to LHA GABA neurons, but without inducing compulsive-like behaviors, which we propose to require direct VTA innervation. Our study integrates galanin-expressing LHA neurons into our current understanding of the neuronal circuits and molecular mechanisms of the LHA that contribute to motivated feeding behaviors. Copyright © 2017 the authors 0270-6474/17/376053-13$15.00/0.

  7. GABA transaminases from Saccharomyces cerevisiae and Arabidopsis thaliana complement function in cytosol and mitochondria.

    PubMed

    Cao, Juxiang; Barbosa, Jose M; Singh, Narendra; Locy, Robert D

    2013-07-01

    GABA transaminase (GABA-T) catalyses the conversion of GABA to succinate semialdehyde (SSA) in the GABA shunt pathway. The GABA-T from Saccharomyces cerevisiae (ScGABA-TKG) is an α-ketoglutarate-dependent enzyme encoded by the UGA1 gene, while higher plant GABA-T is a pyruvate/glyoxylate-dependent enzyme encoded by POP2 in Arabidopsis thaliana (AtGABA-T). The GABA-T from A. thaliana is localized in mitochondria and mediated by an 18-amino acid N-terminal mitochondrial targeting peptide predicated by both web-based utilities TargetP 1.1 and PSORT. Yeast UGA1 appears to lack a mitochondrial targeting peptide and is localized in the cytosol. To verify this bioinformatic analysis and examine the significance of ScGABA-TKG and AtGABA-T compartmentation and substrate specificity on physiological function, expression vectors were constructed to modify both ScGABA-TKG and AtGABA-T, so that they express in yeast mitochondria and cytosol. Physiological function was evaluated by complementing yeast ScGABA-TKG deletion mutant Δuga1 with AtGABA-T or ScGABA-TKG targeted to the cytosol or mitochondria for the phenotypes of GABA growth defect, thermosensitivity and heat-induced production of reactive oxygen species (ROS). This study demonstrates that AtGABA-T is functionally interchangeable with ScGABA-TKG for GABA growth, thermotolerance and limiting production of ROS, regardless of location in mitochondria or cytosol of yeast cells, but AtGABA-T is about half as efficient in doing so as ScGABA-TKG. These results are consistent with the hypothesis that pyruvate/glyoxylate-limited production of NADPH mediates the effect of the GABA shunt in moderating heat stress in Saccharomyces. Copyright © 2013 John Wiley & Sons, Ltd.

  8. Gene Expression in Accumbens GABA Neurons from Inbred Rats with Different Drug-Taking Behavior

    PubMed Central

    Sharp, B.M.; Chen, H.; Gong, S.; Wu, X.; Liu, Z.; Hiler, K.; Taylor, W.L.; Matta, S.G.

    2011-01-01

    Inbred Lewis and Fisher 344 rat strains differ greatly in drug self-administration; Lewis rats operantly self-administer drugs of abuse including nicotine, whereas Fisher self-administer poorly. As shown herein, operant food self-administration is similar. Based on their pivotal role in drug reward, we hypothesized that differences in basal gene expression in GABAergic neurons projecting from nucleus accumbens (NAcc) to ventral pallidum (VP) play a role in vulnerability to drug taking behavior. The transcriptomes of NAcc shell-VP GABAergic neurons from these two strains were analyzed in adolescents, using a multidisciplinary approach that combined stereotaxic ionotophoretic brain microinjections, laser-capture microdissection (LCM) and microarray measurement of transcripts. LCM enriched the gene transcripts detected in GABA neurons compared to the residual NAcc tissue: a ratio of neuron/residual > 1 and false discovery rate (FDR) <5% yielded 6,623 transcripts, whereas a ratio of >3 yielded 3,514. Strain-dependent differences in gene expression within GABA neurons were identified; 322 vs. 60 transcripts showed 1.5-fold vs. 2-fold differences in expression (FDR<5%). Classification by gene ontology showed these 322 transcripts were widely distributed, without categorical enrichment. This is most consistent with a global change in GABA neuron function. Literature-mining by Chilibot found 38 genes related to synaptic plasticity, signaling and gene transcription, all of which determine drug-abuse; 33 genes have no known association with addiction or nicotine. In Lewis rats, upregulation of Mint-1, Cask, CamkIIδ, Ncam1, Vsnl1, Hpcal1 and Car8 indicates these transcripts likely contribute to altered signaling and synaptic function in NAcc GABA projection neurons to VP. PMID:21745336

  9. GABA as a rising gliotransmitter

    PubMed Central

    Yoon, Bo-Eun; Lee, C. Justin

    2014-01-01

    Gamma-amino butyric acid (GABA) is the major inhibitory neurotransmitter that is known to be synthesized and released from GABAergic neurons in the brain. However, recent studies have shown that not only neurons but also astrocytes contain a considerable amount of GABA that can be released and activate GABA receptors in neighboring neurons. These exciting new findings for glial GABA raise further interesting questions about the source of GABA, its mechanism of release and regulation and the functional role of glial GABA. In this review, we highlight recent studies that identify the presence and release of GABA in glial cells, we show several proposed potential pathways for accumulation and modulation of glial intracellular and extracellular GABA content, and finally we discuss functional roles for glial GABA in the brain. PMID:25565970

  10. Manganese exposure alters extracellular GABA, GABA receptor and transporter protein and mRNA levels in the developing rat brain

    PubMed Central

    Anderson, Joel G.; Fordahl, Steve C.; Cooney, Paula T.; Weaver, Tara L.; Colyer, Christa L.; Erikson, Keith M.

    2011-01-01

    Unlike other essential trace elements (e.g., zinc and iron) it is the toxicity of manganese (Mn) that is more common in human populations than its deficiency. Data suggest alterations in dopamine biology may drive the effects associated with Mn neurotoxicity, though recently γ-aminobutyric acid (GABA) has been implicated. In addition, iron deficiency (ID), a common nutritional problem, may cause disturbances in neurochemistry by facilitating accumulation of Mn in the brain. Previous data from our lab have shown decreased brain tissue levels of GABA as well as decreased 3H-GABA uptake in synaptosomes as a result of Mn exposure and ID. These results indicate a possible increase in the concentration of extracellular GABA due to alterations in expression of GABA transport and receptor proteins. In this study weanling-male Sprague-Dawley rats were randomly placed into one of four dietary treatment groups: control (CN; 35 mg Fe/kg diet), iron-deficient (ID; 6 mg Fe/kg diet), CN with Mn supplementation (via the drinking water; 1 g Mn/L) (CNMn), and ID with Mn supplementation (IDMn). Using in vivo microdialysis, an increase in extracellular GABA concentrations in the striatum was observed in response to Mn exposure and ID although correlational analysis reveals that extracellular GABA is related more to extracellular iron levels and not Mn. A diverse effect of Mn exposure and ID was observed in the regions examined via Western blot and RT-PCR analysis, with effects on mRNA and protein expression of GAT-1, GABAA, and GABAB differing between and within the regions examined. For example, Mn exposure reduced GAT-1 protein expression by approximately 50% in the substantia nigra, while increasing mRNA expression approximately four-fold, while in the caudate putamen mRNA expression was decreased with no effect on protein expression. These data suggest that Mn exposure results in an increase in extracellular GABA concentrations via altered expression of transport and receptor

  11. Endogenous GABA and glutamate finely tune the bursting of olfactory bulb external tufted cells.

    PubMed

    Hayar, Abdallah; Ennis, Matthew

    2007-08-01

    In rat olfactory bulb slices, external tufted (ET) cells spontaneously generate spike bursts. Although ET cell bursting is intrinsically generated, its strength and precise timing may be regulated by synaptic input. We tested this hypothesis by analyzing whether the burst properties are modulated by activation of ionotropic gamma-aminobutyric acid (GABA) and glutamate receptors. Blocking GABA(A) receptors increased--whereas blocking ionotropic glutamate receptors decreased--the number of spikes/burst without changing the interburst frequency. The GABA(A) agonist (isoguvacine, 10 microM) completely inhibited bursting or reduced the number of spikes/burst, suggesting a shunting effect. These findings indicate that the properties of ET cell spontaneous bursting are differentially controlled by GABAergic and glutamatergic fast synaptic transmission. We suggest that ET cell excitatory and inhibitory inputs may be encoded as a change in the pattern of spike bursting in ET cells, which together with mitral/tufted cells constitute the output circuit of the olfactory bulb.

  12. Hippocampal low-frequency stimulation inhibits afterdischarge and increases GABA (A) receptor expression in amygdala-kindled pharmacoresistant epileptic rats.

    PubMed

    Wu, Guofeng; Wang, Likun; Hong, Zhen; Ren, Siying; Zhou, Feng

    2017-08-01

    The purpose of the present study was to observe the effects of hippocampal low-frequency stimulation (Hip-LFS) on amygdala afterdischarge and GABA (A) receptor expression in pharmacoresistant epileptic (PRE) rats. A total of 110 healthy adult male Wistar rats were used to generate a model of epilepsy by chronic stimulation of the amygdala. Sixteen PRE rats were selected from 70 amygdala-kindled rats by testing their response to Phenytoin and Phenobarbital, and they were randomly assigned to a pharmacoresistant stimulation group (PRS group, 8 rats) or a pharmacoresistant control group (PRC group, 8 rats). A stimulation electrode was implanted into the hippocampus of all of the rats. Hip-LFS was administered twice per day in the PRS group for two weeks. Simultaneously, amygdala stimulus-induced seizures and afterdischarge were recorded. After the hippocampal stimulation was terminated, the brain tissues were obtained to determine the GABA (A) receptors by a method of immumohistochemistry and a real-time polymerase chain reaction. The stages and duration of the amygdala stimulus-induced epileptic seizures were decreased in the PRS group. The afterdischarge threshold was increased and the duration as well as the afterdischarge frequency was decreased. Simultaneously, the GABA (A) expression was significantly increased in the PRS group. Hip-LFS may inhibit amygdala stimulus-induced epileptic seizures and up-regulate GABA (A) receptor expression in PRE rats. The antiepileptic effects of hippocampal stimulation may be partly achieved by increasing the GABA (A) receptor.

  13. New GABA modulators protect photoreceptor cells from light-induced degeneration in mouse models.

    PubMed

    Schur, Rebecca M; Gao, Songqi; Yu, Guanping; Chen, Yu; Maeda, Akiko; Palczewski, Krzysztof; Lu, Zheng-Rong

    2018-01-24

    No clinically approved therapies are currently available that prevent the onset of photoreceptor death in retinal degeneration. Signaling between retinal neurons is regulated by the release and uptake of neurotransmitters, wherein GABA is the main inhibitory neurotransmitter. In this work, novel 3-chloropropiophenone derivatives and the clinical anticonvulsants tiagabine and vigabatrin were tested to modulate GABA signaling and protect against light-induced retinal degeneration. Abca4 -/- Rdh8 -/- mice, an accelerated model of retinal degeneration, were exposed to intense light after prophylactic injections of one of these compounds. Imaging and functional assessments of the retina indicated that these compounds successfully protected photoreceptor cells from degeneration to maintain a full-visual-field response. Furthermore, these compounds demonstrated a strong safety profile in wild-type mice and did not compromise visual function or damage the retina, despite repeated administration. These results indicate that modulating inhibitory GABA signaling can offer prophylactic protection against light-induced retinal degeneration.-Schur, R. M., Gao, S., Yu, G., Chen, Y., Maeda, A., Palczewski, K., Lu, Z.-R. New GABA modulators protect photoreceptor cells from light-induced degeneration in mouse models.

  14. GABA Levels Are Decreased After Stroke and GABA Changes During Rehabilitation Correlate With Motor Improvement

    PubMed Central

    Blicher, Jakob Udby; Near, Jamie; Næss-Schmidt, Erhard; Stagg, Charlotte J.; Johansen-Berg, Heidi; Nielsen, Jørgen Feldbæk; Østergaard, Leif; Ho, Yi-Ching Lynn

    2017-01-01

    Background and Objective γ-Aminobutyric acid (GABA) is the dominant inhibitory neurotransmitter in the brain and is important in motor learning. We aimed to measure GABA content in primary motor cortex poststroke (using GABA-edited magnetic resonance spectroscopy [MRS]) and in relation to motor recovery during 2 weeks of constraint-induced movement therapy (CIMT). Methods Twenty-one patients (3-12 months poststroke) and 20 healthy subjects were recruited. Magnetic resonance imaging structural T1 and GABA-edited MRS were performed at baseline and after CIMT, and once in healthy subjects. GABA:creatine (GABA:Cr) ratio was measured by GABA-edited MRS. Motor function was measured using Wolf Motor Function Test (WMFT). Results Baseline comparison between stroke patients (n = 19) and healthy subjects showed a significantly lower GABA:Cr ratio in stroke patients (P < .001) even after correcting for gray matter content in the voxel (P < .01) and when expressing GABA relative to N-acetylaspartic acid (NAA; P = .03). After 2 weeks of CIMT patients improved significantly on WMFT, but no consistent change across the group was observed for the GABA:Cr ratio (n = 17). However, the extent of improvement on WMFT correlated significantly with the magnitude of GABA:Cr changes (P < .01), with decreases in GABA:Cr ratio being associated with better improvements in motor function. Conclusions In patients 3 to 12 months poststroke, GABA levels are lower in the primary motor cortex than in healthy subjects. The observed association between GABA and recovery warrants further studies on the potential use of GABA MRS as a biomarker in poststroke recovery. PMID:25055837

  15. Effect of progesterone on the expression of GABA(A) receptor subunits in the prefrontal cortex of rats: implications of sex differences and brain hemisphere.

    PubMed

    Andrade, Susie; Arbo, Bruno D; Batista, Bruna A M; Neves, Alice M; Branchini, Gisele; Brum, Ilma S; Barros, Helena M T; Gomez, Rosane; Ribeiro, Maria Flavia M

    2012-12-01

    Progesterone is a neuroactive hormone with non-genomic effects on GABA(A) receptors (GABA(A)R). Changes in the expression of GABA(A)R subunits are related to depressive-like behaviors in rats. Moreover, sex differences and depressive behaviors have been associated with prefrontal brain asymmetry in rodents and humans. Thus, our objective was to investigate the effect of progesterone on the GABA(A)R α1 and γ2 subunits mRNA expression in the right and left prefrontal cortex of diestrus female and male rats exposed to the forced swimming test (FST). Male and female rats (n = 8/group) were randomly selected to receive a daily dose of progesterone (0·4 mg·kg⁻¹) or vehicle, during two complete female estrous cycles (8-10 days). On the experiment day, male rats or diestrus female rats were euthanized 30 min after the FST. Our results showed that progesterone significantly increased the α1 subunit mRNA in both hemispheres of male and female rats. Moreover, there was an inverse correlation between depressive-like behaviors and GABA(A)R α1 subunit mRNA expression in the right hemisphere in female rats. Progesterone decreased the GABA(A)R γ2 mRNA expression only in the left hemisphere of male rats. Therefore, we conclude that the GABA(A) system displays an asymmetric distribution according to sex and that progesterone, at lower doses, presents an antidepressant effect after increasing the GABA(A) R α1 subunit expression in the right prefrontal cortex of female rats. Copyright © 2012 John Wiley & Sons, Ltd.

  16. Distribution of 3H-GABA uptake sites in the nematode Ascaris

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Guastella, J.; Stretton, A.O.

    1991-05-22

    The distribution of uptake sites for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the nematode Ascaris suum was examined by autoradiography of 3H-GABA uptake. Single neural processes in both the ventral and dorsal nerve cords were labeled with 3H-GABA. Serial section analysis identified the cells of origin of these processes as the RMEV-like and RMED-like neurons. These cells belong to a set of four neurons in the nerve ring, all of which are labeled by 3H-GABA. 3H-GABA labeling of at least two other sets of cephalic neurons was seen. One of these pairs consists of medium-sized lateral ganglia neurons, locatedmore » at the level of the amphid commissure bundle. A second pair is located in the lateral ganglia at the level of the deirid commissure bundle. The position and size of these lateral ganglia cells suggest that they are the GABA-immunoreactive lateral ganglia cells frequently seen in whole-mount immunocytochemical preparations. Four neuronal cell bodies located in the retrovesicular ganglion were also labeled with 3H-GABA. These cells, which are probably cholinergic excitatory motor neurons, do not contain detectable GABA-like immunoreactivity. Heavy labeling of muscle cells was also observed. The ventral and dorsal nerve cord inhibitory motor neurons, which are known to contain GABA-like immunoreactivity, were not labeled above background with 3H-GABA. Together with the experiments reported previously, these results define three classes of GABA-associated neurons in Ascaris: (1) neurons that contain endogenous GABA and possess a GABA uptake system; (2) neurons that contain endogenous GABA, but that either lack a GABA uptake system or possess a GABA uptake system of low activity; (3) neurons that possess a GABA uptake system, but that lack endogenous GABA.« less

  17. GABA type a receptor trafficking and the architecture of synaptic inhibition.

    PubMed

    Lorenz-Guertin, Joshua M; Jacob, Tija C

    2018-03-01

    Ubiquitous expression of GABA type A receptors (GABA A R) in the central nervous system establishes their central role in coordinating most aspects of neural function and development. Dysregulation of GABAergic neurotransmission manifests in a number of human health disorders and conditions that in certain cases can be alleviated by drugs targeting these receptors. Precise changes in the quantity or activity of GABA A Rs localized at the cell surface and at GABAergic postsynaptic sites directly impact the strength of inhibition. The molecular mechanisms constituting receptor trafficking to and from these compartments therefore dictate the efficacy of GABA A R function. Here we review the current understanding of how GABA A Rs traffic through biogenesis, plasma membrane transport, and degradation. Emphasis is placed on discussing novel GABAergic synaptic proteins, receptor and scaffolding post-translational modifications, activity-dependent changes in GABA A R confinement, and neuropeptide and neurosteroid mediated changes. We further highlight modern techniques currently advancing the knowledge of GABA A R trafficking and clinically relevant neurodevelopmental diseases connected to GABAergic dysfunction. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 238-270, 2018. © 2017 Wiley Periodicals, Inc.

  18. GABA and Gap Junctions in the Development of Synchronized Activity in Human Pluripotent Stem Cell-Derived Neural Networks

    PubMed Central

    Mäkinen, Meeri Eeva-Liisa; Ylä-Outinen, Laura; Narkilahti, Susanna

    2018-01-01

    The electrical activity of the brain arises from single neurons communicating with each other. However, how single neurons interact during early development to give rise to neural network activity remains poorly understood. We studied the emergence of synchronous neural activity in human pluripotent stem cell (hPSC)-derived neural networks simultaneously on a single-neuron level and network level. The contribution of gamma-aminobutyric acid (GABA) and gap junctions to the development of synchronous activity in hPSC-derived neural networks was studied with GABA agonist and antagonist and by blocking gap junctional communication, respectively. We characterized the dynamics of the network-wide synchrony in hPSC-derived neural networks with high spatial resolution (calcium imaging) and temporal resolution microelectrode array (MEA). We found that the emergence of synchrony correlates with a decrease in very strong GABA excitation. However, the synchronous network was found to consist of a heterogeneous mixture of synchronously active cells with variable responses to GABA, GABA agonists and gap junction blockers. Furthermore, we show how single-cell distributions give rise to the network effect of GABA, GABA agonists and gap junction blockers. Finally, based on our observations, we suggest that the earliest form of synchronous neuronal activity depends on gap junctions and a decrease in GABA induced depolarization but not on GABAA mediated signaling. PMID:29559893

  19. Quantitative changes of GABA-immunoreactive cells in the hindlimb representation of the rat somatosensory cortex after 14-day hindlimb unloading by tail suspension

    NASA Technical Reports Server (NTRS)

    D'Amelio, F.; Fox, R. A.; Wu, L. C.; Daunton, N. G.

    1996-01-01

    The present study was aimed at evaluating quantitatively gamma-aminobutyric acid (GABA) immunoreactivity in the hindlimb representation of the rat somatosensory cortex after 14 days of hindlimb unloading by tail suspension. A reduction in the number of GABA-immunoreactive cells with respect to the control animals was observed in layer Va and Vb. GABA-containing terminals were also reduced in the same layers, particularly those terminals surrounding the soma and apical dendrites of pyramidal cells in layer Vb. On the basis of previous morphological and behavioral studies of the neuromuscular system of hindlimb-suspended animals, it is suggested that the unloading due to hindlimb suspension alters afferent signaling and feedback information from intramuscular receptors to the cerebral cortex due to modifications in the reflex organization of hindlimb muscle groups. We propose that the reduction in immunoreactivity of local circuit GABAergic neurons and terminals is an expression of changes in their modulatory activity to compensate for the alterations in the afferent information.

  20. Genetic differences in the ethanol sensitivity of GABA sub A receptors expressed in Xenopus oocytes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wafford, K.A.; Burnett, D.M.; Dunwiddie, T.V.

    1990-07-20

    Animal lines selected for differences in drug sensitivity can be used to help determine the molecular basis of drug action. Long-sleep (LS) and short-sleep (SS) mice differ markedly in their genetic sensitivity to ethanol. To investigate the molecular basis for this difference, mRNA from brains of LS and SS mice was expressed in Xenopus oocytes and the ethanol sensitivity of gamma-aminobutyric acid A (GABA{sub A})- and N-methyl D-aspartate (NMDA) - activated ion channels was tested. Ethanol facilitated GABA responses in oocytes injected with mRNA from LS mice but antagonized responses in oocytes injected with mRNA from SS animals. Ethanol inhibitedmore » NMDA responses equally in the two lines. Thus, genes coding for the GABA{sub A} receptor or associated proteins may be critical determinants of individual differences in ethanol sensitivity.« less

  1. Efficient Production of γ-GABA Using Recombinant E. coli Expressing Glutamate Decarboxylase (GAD) Derived from Eukaryote Saccharomyces cerevisiae.

    PubMed

    Xiong, Qiang; Xu, Zheng; Xu, Lu; Yao, Zhong; Li, Sha; Xu, Hong

    2017-12-01

    γ-Aminobutyric acid (γ-GABA) is a non-proteinogenic amino acid, which acts as a major regulator in the central nervous system. Glutamate decarboxylase (namely GAD, EC 4.1.1.15) is known to be an ideal enzyme for γ-GABA production using L-glutamic acid as substrate. In this study, we cloned and expressed GAD gene from eukaryote Saccharomyces cerevisiae (ScGAD) in E. coli BL21(DE3). This enzyme was further purified and its optimal reaction temperature and pH were 37 °C and pH 4.2, respectively. The cofactor of ScGAD was verified to be either pyridoxal 5'-phosphate (PLP) or pyridoxal hydrochloride. The optimal concentration of either cofactor was 50 mg/L. The optimal medium for E. coli-ScGAD cultivation and expression were 10 g/L lactose, 5 g/L glycerol, 20 g/L yeast extract, and 10 g/L sodium chloride, resulting in an activity of 55 U/mL medium, three times higher than that of using Luria-Bertani (LB) medium. The maximal concentration of γ-GABA was 245 g/L whereas L-glutamic acid was near completely converted. These findings provided us a good example for bio-production of γ-GABA using recombinant E. coli expressing a GAD enzyme derived from eukaryote.

  2. Enhancement of GABA release through endogenous activation of axonal GABA(A) receptors in juvenile cerebellum.

    PubMed

    Trigo, Federico F; Chat, Mireille; Marty, Alain

    2007-11-14

    Recent evidence indicates the presence of presynaptic GABA(A) receptors (GABA(A)Rs) in the axon domain of several classes of central neurons, including cerebellar basket and stellate cells. Here, we investigate the possibility that these receptors could be activated in the absence of electrical or chemical stimulation. We find that low concentrations of GABA increase the frequency of miniature GABAergic synaptic currents. Submaximal concentrations of a GABA(A)R blocker, gabazine, decrease both the miniature current frequency and the probability of evoked GABA release. Zolpidem, an agonist of the benzodiazepine binding site, and NO-711 (1-[2-[[(diphenylmethylene)imino]oxy]ethyl]-1,2,5,6-tetrahydro-3-pyridinecarboxylic acid hydrochloride), a blocker of GABA uptake, both increase the frequency of miniature currents. These effects occur up to postnatal day 14, but not later. Immunohistochemistry indicates the presence of alpha1-containing GABA(A)Rs in interneuron presynaptic terminals with a similar age dependence. We conclude that, under resting conditions, axonal GABA(A)Rs are significantly activated, that this activation results in enhanced GABA release, and that it can be augmented by increasing the affinity of GABA(A)Rs or reducing GABA uptake. Our findings suggest the existence of a positive-feedback mechanism involving presynaptic GABA(A)Rs that maintains a high release rate and a high local GABA concentration in the immature cerebellar network.

  3. Effects of chronic ethanol consumption on rat GABA(A) and strychnine-sensitive glycine receptors expressed by lateral/basolateral amygdala neurons.

    PubMed

    McCool, Brian A; Frye, Gerald D; Pulido, Marisa D; Botting, Shaleen K

    2003-02-14

    It is well known that the anxiolytic potential of ethanol is maintained during chronic exposure. We have confirmed this using a light-dark box paradigm following chronic ethanol ingestion via a liquid diet. However, cessation from chronic ethanol exposure is known to cause severe withdrawal anxiety. These opposing effects on anxiety likely result from neuro-adaptations of neurotransmitter systems within the brain regions regulating anxiety. Recent work highlights the importance of amygdala ligand-gated chloride channels in the expression of anxiety. We have therefore examined the effects of chronic ethanol exposure on GABA(A) and strychnine-sensitive glycine receptors expressed by acutely isolated adult rat lateral/basolateral amygdala neurons. Chronic ethanol exposure increased the functional expression of GABA(A) receptors in acutely isolated basolateral amygdala neurons without altering strychnine-sensitive glycine receptors. Neither the acute ethanol nor benzodiazepine sensitivity of either receptor system was affected. We explored the likelihood that subunit composition might influence each receptor's response to chronic ethanol. Importantly, when expressed in a mammalian heterologous system, GABA(A) receptors composed of unique alpha subunits were differentially sensitive to acute ethanol. Likewise, the presence of the beta subunit appeared to influence the acute ethanol sensitivity of glycine receptors containing the alpha(2) subunit. Our results suggest that the facilitation of GABA(A) receptors during chronic ethanol exposure may help explain the maintenance of ethanol's anti-anxiety effects during chronic ethanol exposure. Furthermore, the subunit composition of GABA(A) and strychnine-sensitive glycine receptors may ultimately influence the response of each system to chronic ethanol exposure.

  4. Brain distribution and molecular cloning of the bovine GABA rho1 receptor.

    PubMed

    Rosas-Arellano, Abraham; Ochoa-de la Paz, Lenin David; Miledi, Ricardo; Martínez-Torres, Ataúlfo

    2007-03-01

    GABA(C) receptors were originally found in the mammalian retina and recent evidence shows that they are also expressed in several areas of the brain, including caudate nucleus, brain stem, pons and corpus callosum. In this study, plasma membranes from the caudate nucleus were microinjected into X. laevis oocytes. This led the oocyte plasma membrane to incorporate functional bicuculline-resistant, Cl(-) conducting bovine GABA receptors, similar to those of the retina. Immunolocalization of the GABA rho1 subunit revealed its expression in bovine neurons in the head of the caudate as well as in the olive, cuneiform and reticular nuclei of the brain stem. The same antibodies failed to show expression in the callosum and pons, where the GABA rho1 mRNA was previously detected. The cloned GABA rho1 sequence predicts a protein with 473 amino acids and 74-93% similarity to other GABA rho1 subunits. Oocytes injected with the cDNA express a non-desensitizing, homomeric receptor with a GABA EC(50)=6.0 microM and a Hill coefficient of 1.8. The results confirm the presence of GABA(C) receptor mRNAs in several areas of the mammalian brain and show that some of these areas express functional GABA rho1 receptors that have the classic GABA(C) receptor characteristics.

  5. Functional role of ambient GABA in refining neuronal circuits early in postnatal development

    PubMed Central

    Cellot, Giada; Cherubini, Enrico

    2013-01-01

    Early in development, γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the mature brain, depolarizes and excites targeted neurons by an outwardly directed flux of chloride, resulting from the peculiar balance between the cation-chloride importer NKCC1 and the extruder KCC2. The low expression of KCC2 at birth leads to accumulation of chloride inside the cell and to the equilibrium potential for chloride positive respect to the resting membrane potential. GABA exerts its action via synaptic and extrasynaptic GABAA receptors mediating phasic and tonic inhibition, respectively. Here, recent data on the contribution of “ambient” GABA to the refinement of neuronal circuits in the immature brain have been reviewed. In particular, we focus on the hippocampus, where, prior to the formation of conventional synapses, GABA released from growth cones and astrocytes in a calcium- and SNARE (soluble N-ethylmaleimide-sensitive-factor attachment protein receptor)-independent way, diffuses away to activate in a paracrine fashion extrasynaptic receptors localized on distal neurons. The transient increase in intracellular calcium following the depolarizing action of GABA leads to inhibition of DNA synthesis and cell proliferation. Tonic GABA exerts also a chemotropic action on cell migration. Later on, when synapses are formed, GABA spilled out from neighboring synapses, acting mainly on extrasynaptic α5, β2, β3, and γ containing GABAA receptor subunits, provides the membrane depolarization necessary for principal cells to reach the window where intrinsic bursts are generated. These are instrumental in triggering calcium transients associated with network-driven giant depolarizing potentials which act as coincident detector signals to enhance synaptic efficacy at emerging GABAergic and glutamatergic synapses. PMID:23964205

  6. Interaction of GABA-mimetics with the taurine transporter (TauT, Slc6a6) in hyperosmotic treated Caco-2, LLC-PK1 and rat renal SKPT cells.

    PubMed

    Rasmussen, Rune Nørgaard; Lagunas, Candela; Plum, Jakob; Holm, René; Nielsen, Carsten Uhd

    2016-01-20

    The aim of the present study was to investigate if basic GABA-mimetics interact with the taurine transporter (TauT, Slc6a6), and to find a suitable cell based model that is robust towards extracellular changes in osmolality during uptake studies. Taurine uptake was measured in human Caco-2 cells, porcine LLC-PK1 cells, and rat SKPT cells using radiolabelled taurine. Hyperosmotic conditions were obtained by incubation with raffinose (final osmolality of 500mOsm) for 24h prior to the uptake experiments. Expression of the taurine transporter, TauT, was investigated at the mRNA level by real-time PCR. Uptake of the GABA-mimetics gaboxadol and vigabatrin was investigated in SKPT cells, and quantified by liquid scintillation or HPLC-MS/MS analysis, respectively. The uptake rate of [(3)H]-taurine was Na(+) and Cl(-) and concentration dependent with taurine with an apparent Vmax of 6.3±1.6pmolcm(-2)min(-1) and a Km of 24.9±15.0μM. β-alanine, nipecotic acid, gaboxadol, GABA, vigabatrin, δ-ALA and guvacine inhibited the taurine uptake rate in a concentration dependent manner. The order of affinity for TauT was β-alanine>GABA>nipecotic acid>guvacine>δ-ALA>vigabatrin>gaboxadol with IC50-values of 0.04, 1.07, 2.02, 4.19, 4.94, 31.4 and 39.9mM, respectively. In conclusion, GABA mimetics inhibited taurine uptake in hyperosmotic rat renal SKPT cells. SKPT cells, which seem to be a useful model for investigating taurine transport in the short-term presence of high concentrations of osmolytes. Furthermore, analogues of β-alanine appear to have higher affinities for TauT than GABA-analogues. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. GABA-independent GABAA Receptor Openings Maintain Tonic Currents

    PubMed Central

    Wlodarczyk, Agnieszka I.; Sylantyev, Sergiy; Herd, Murray B.; Kersanté, Flavie; Lambert, Jeremy J.; Rusakov, Dmitri A.; Linthorst, Astrid C.E.; Semyanov, Alexey; Belelli, Delia; Pavlov, Ivan; Walker, Matthew C.

    2013-01-01

    Activation of GABAA receptors (GABAARs) produces two forms of inhibition: ‘phasic’ inhibition generated by the rapid, transient activation of synaptic GABAARs by presynaptic GABA release, and tonic inhibition generated by the persistent activation of peri- or extrasynaptic GABAARs which can detect extracellular GABA. Such tonic GABAAR-mediated currents are particularly evident in dentate granule cells in which they play a major role in regulating cell excitability. Here we show that in rat dentate granule cells in ex-vivo hippocampal slices, tonic currents are predominantly generated by GABA-independent GABAA receptor openings. This tonic GABAAR conductance is resistant to the competitive GABAAR antagonist SR95531, which at high concentrations acts as a partial agonist, but can be blocked by an open channel blocker picrotoxin. When slices are perfused with 200 nM GABA, a concentration that is comparable to cerebrospinal fluid concentrations but is twice that measured by us in the hippocampus in vivo using zero-net-flux microdialysis, negligible GABA is detected by dentate granule cells. Spontaneously opening GABAARs, therefore, maintain dentate granule cell tonic currents in the face of low extracellular GABA concentrations. PMID:23447601

  8. Gad1 mRNA as a reliable indicator of altered GABA release from orexigenic neurons in the hypothalamus

    PubMed Central

    Dicken, Matthew S.; Hughes, Alexander R.; Hentges, Shane T.

    2016-01-01

    The strength of γ-aminobutyric acid (GABA)-mediated inhibitory synaptic input is a principle determinant of neuronal activity. However, because of differences in the number of GABA afferent inputs and the sites of synapses, it is difficult to directly assay for altered GABA transmission between specific cells. The present study tested the hypothesis that the level of mRNA for the GABA synthetic enzyme glutamate decarboxylase (GAD) can provide a reliable proxy for GABA release. This was tested in a mouse hypothalamic circuit important in the regulation of energy balance. Fluorescent in situ hybridization results show that the expression of Gad1 mRNA (encoding the GAD67 enzyme) was increased in hypothalamic neuropeptide Y/agouti-related peptide (NPY/AgRP) neurons after an overnight fast, consistent with the ability of GABA from these neurons to stimulate food intake. Optogenetic studies confirmed that the observed increase in Gad1 mRNA correlated with an increase in the probability of GABA release from NPY/AgRP neurons onto downstream proopiomelanocortin neurons. Likewise, there was an increase in the readily releasable pool of GABA in NPY/AgRP neurons. Selective inhibition of GAD activity in NPY/AgRP neurons decreased GABA release, indicating that GAD67 activity, which is largely dictated by expression level, is a key determinant of GABA release. Altogether, it appears that Gad expression may be a reliable proxy of altered GABAergic transmission. Examining changes in Gad mRNA as a proxy for GABA release may be particularly helpful when the downstream targets are not known or when limited tools exist for detecting GABA release at a particular synapse. PMID:26370162

  9. 2-Aminoethyl Methylphosphonate, a Potent and Rapidly Acting Antagonist of GABA A-ρ1 Receptors

    DOE PAGES

    Xie, A.; Yan, J.; Yue, L.; ...

    2011-08-02

    All three classes of receptors for the inhibitory neurotransmitter GABA (GABAR) are expressed in the retina. This study investigated roles of GABAR, especially GABA(C)R (GABA(A)-rho), in retinal signaling in vivo by studying effects on the mouse electroretinogram (ERG) of genetic deletion of GABA(C)R versus pharmacological blockade using receptor antagonists. Brief full-field flash ERGs were recorded from anesthetized GABA(C)R(-/-) mice, and WT C57BL/6 (B6) mice, before and after intravitreal injection of GABA(C)R antagonists, TPMPA, 3-APMPA, or the more recently developed 2-AEMP; GABA(A)R antagonist, SR95531; GABA(B)R antagonist, CGP, and agonist, baclofen. Intravitreal injections of TPMPA and SR95531 were also made in Brownmore » Norway rats. The effect of 2-AEMP on GABA-induced current was tested directly in isolated rat rod bipolar cells, and 2-AEMP was found to preferentially block GABA(C)R in those cells. Maximum amplitudes of dark (DA) and light-adapted (LA) ERG b-waves were reduced in GABA(C)R(-/-) mice, compared to B6 mice, by 30-60%; a-waves were unaltered and oscillatory potential amplitudes were increased. In B6 mice, after injection of TPMPA (also in rats), 3-APMPA or 2-AEMP, ERGs became similar to ERGs of GABA(C)R(-/-) mice. Blockade of GABA(A)Rs and GABA(B)Rs, or agonism of GABA(B)Rs did not alter B6 DA b-wave amplitude. The negative scotopic threshold response (nSTR) was slightly less sensitive in GABA(C)R(-/-) than in B6 mice, and unaltered by 2-AEMP. However, amplitudes of nSTR and photopic negative response (PhNR), both of which originate from inner retina, were enhanced by TPMPA and 3-APMPA, each of which has GABA(B) agonist properties, and further increased by baclofen. The finding that genetic deletion of GABA(C)R, the GABA(C)R antagonist 2-AEMP, and other antagonists all reduced ERG b-wave amplitude, supports a role for CABA(C)R in determining the maximum response amplitude of bipolar cells contributing to the b-wave. GABA(C)R antagonists

  10. γ-Amino-butyric acid (GABA) receptor subunit and transporter expression in the gonad and liver of the fathead minnow (Pimephales promelas).

    PubMed

    Biggs, Katie; Seidel, Jason S; Wilson, Alex; Martyniuk, Christopher J

    2013-09-01

    γ-Amino-butyric acid (GABA) is the major inhibitory neurotransmitter in the vertebrate central nervous system. GABA receptors and synthesizing enzymes have also been localized to peripheral tissues including the liver, oviduct, uterus and ovary of mammals but the distribution and role of GABA in peripheral tissues of fish has not been fully investigated. The objectives of this study were to (1) determine if mRNA encoding GABA synthesizing enzymes (glutamic acid decarboxylase 65 and 67; gad65 and gad67), GABA transporters, and GABAA receptor subunits are localized to liver and gonad of fathead minnow (Pimephales promelas) (FHM) (2) investigate the effects of GABA on ovarian 17β-estradiol (E2) production, and (3) measure transcript responses in the ovary after in vitro incubation to GABA. Real-time PCR assays were developed for gad65, gad67, vesicular GABA transporter (vgat) and GABA transporter 1 (gat1), and select GABAA receptor subunits (gabra1, gabra5, gabrb1, gabrb2, gabrg1, gabrg2). All transcripts were localized to the brain as expected; however transcripts were also detected in the liver, ovary, and testis of FHMs. In the female liver, gad65 mRNA was significantly higher in expression compared to the male liver. Transcripts for gad67 were the highest in the brain>gonad>liver and in the gonads, gad67 was significantly higher in expression than gad65 mRNA. In the liver and gonad, the relative abundance of the subunits followed a general trend of gabrb1>gabrb2=gabrg1=gabrg2>gabra1=gabra5. To explore the effects of GABA in the ovary, tissue explants from reproductive female FHMs were treated with GABA (10(-10), 10(-8) and 10(-6)M) for 12h. GABA had no significant effect on 17β-estradiol production or on mRNA abundance for genes involved in ovarian steroidogenesis (e.g., 11βhsd, cyp17, cyp19a). There was a significant decrease in estrogen receptor 2a (esr2a) mRNA with 10(-10)M GABA. This study begins to investigate the GABA system in non-neural tissues of

  11. Rapid Substrate-Induced Charge Movements of the GABA Transporter GAT1

    PubMed Central

    Bicho, Ana; Grewer, Christof

    2005-01-01

    The GABA transporter GAT1 removes the neurotransmitter GABA from the synaptic cleft by coupling of GABA uptake to the co-transport of two sodium ions and one chloride ion. The aim of this work was to investigate the individual reaction steps of GAT1 after a GABA concentration jump. GAT1 was transiently expressed in HEK293 cells and its pre-steady-state kinetics were studied by combining the patch-clamp technique with the laser-pulse photolysis of caged GABA, which allowed us to generate GABA concentration jumps within <100 μs. Recordings of transport currents generated by GAT1, both in forward and exchange transport modes, showed multiple charge movements that can be separated along the time axis. The individual reactions associated with these charge movements differ from the well-characterized electrogenic “sodium-occlusion” reaction by GAT1. One of the observed electrogenic reactions is shown to be associated with the GABA-translocating half-cycle of the transporter, in contradiction to previous studies that showed no charge movements associated with these reactions. Interestingly, reactions of the GABA-bound transporter were not affected by the absence of extracellular chloride, suggesting that Cl− may not be co-translocated with GABA. Based on the results, a new alternating access sequential-binding model is proposed for GAT1's transport cycle that describes the results presented here and those by others. PMID:15849242

  12. GABA pharmacology: the search for analgesics.

    PubMed

    McCarson, Kenneth E; Enna, S J

    2014-10-01

    Decades of research have been devoted to defining the role of GABAergic transmission in nociceptive processing. Much of this work was performed using rigid, orthosteric GABA analogs created by Povl Krogsgaard-Larsen and his associates. A relationship between GABA and pain is suggested by the anatomical distribution of GABA receptors and the ability of some GABA agonists to alter nociceptive responsiveness. Outlined in this report are data supporting this proposition, with particular emphasis on the anatomical localization and function of GABA-containing neurons and the molecular and pharmacological properties of GABAA and GABAB receptor subtypes. Reference is made to changes in overall GABAergic tone, GABA receptor expression and activity as a function of the duration and intensity of a painful stimulus or exposure to GABAergic agents. Evidence is presented that the plasticity of this receptor system may be responsible for the variability in the antinociceptive effectiveness of compounds that influence GABA transmission. These findings demonstrate that at least some types of persistent pain are associated with a regionally selective decline in GABAergic tone, highlighting the need for agents that enhance GABA activity in the affected regions without compromising GABA function over the long-term. As subtype selective positive allosteric modulators may accomplish these goals, such compounds might represent a new class of analgesic drugs.

  13. Protein kinase and phosphatase modulation of quail brain GABA(A) and non-NMDA receptors co-expressed in Xenopus oocytes.

    PubMed

    Moon, C; Fraser, S P; Djamgoz, M B

    2000-02-01

    The GABA(A) receptor and the non-NMDA subtype of the ionotropic glutamate receptor were co-expressed in Xenopus oocytes by injection of quail brain mRNA. The oocytes were treated with various protein kinase (PK) and protein phosphatase (PP) activators and inhibitors and the effects on receptor functioning were monitored. Two phorbol esters, 4-beta-phorbol 12-myristate-13-acetate (PMA) and 4-beta-phorbol 12,13-dibutyrate (PDBu); the cGMP-dependent PK activators sodium nitroprusside (SNP) and S-nitrosoglutathione (SNOG); and the PP inhibitor okadaic acid (OA) reduced the amplitude of the GABA-induced currents, whilst the PK inhibitor staurosporine potentiated it. In addition, PMA, PDBu, SNP, and OA reduced the desensitization of the GABA-induced response. Identical treatments generally had similar but less pronounced effects on responses generated by kainate (KA) but the desensitization characteristic of the non-NMDA receptor was not affected. None of the treatments had any effect on the reversal potentials of the induced currents. Immunoblots revealed that the oocytes express endogenous PKG and guanylate cyclase. The results are discussed in terms of the molecular structures of GABA(A) and non-NMDA receptors and the potential functional consequences of phosphorylation/dephosphorylation.

  14. PDF cells are a GABA-responsive wake-promoting component of the Drosophila sleep circuit.

    PubMed

    Parisky, Katherine M; Agosto, Jose; Pulver, Stefan R; Shang, Yuhua; Kuklin, Elena; Hodge, James J L; Kang, Kyeongjin; Kang, Keongjin; Liu, Xu; Garrity, Paul A; Rosbash, Michael; Griffith, Leslie C

    2008-11-26

    Daily sleep cycles in humans are driven by a complex circuit within which GABAergic sleep-promoting neurons oppose arousal. Drosophila sleep has recently been shown to be controlled by GABA, which acts on unknown cells expressing the Rdl GABAA receptor. We identify here the relevant Rdl-containing cells as PDF-expressing small and large ventral lateral neurons (LNvs) of the circadian clock. LNv activity regulates total sleep as well as the rate of sleep onset; both large and small LNvs are part of the sleep circuit. Flies mutant for pdf or its receptor are hypersomnolent, and PDF acts on the LNvs themselves to control sleep. These features of the Drosophila sleep circuit, GABAergic control of onset and maintenance as well as peptidergic control of arousal, support the idea that features of sleep-circuit architecture as well as the mechanisms governing the behavioral transitions between sleep and wake are conserved between mammals and insects.

  15. Estradiol and luteinizing hormone regulate recognition memory following subchronic phencyclidine: Evidence for hippocampal GABA action.

    PubMed

    Riordan, Alexander J; Schaler, Ari W; Fried, Jenny; Paine, Tracie A; Thornton, Janice E

    2018-05-01

    The cognitive symptoms of schizophrenia are poorly understood and difficult to treat. Estrogens may mitigate these symptoms via unknown mechanisms. To examine these mechanisms, we tested whether increasing estradiol (E) or decreasing luteinizing hormone (LH) could mitigate short-term episodic memory loss in a phencyclidine (PCP) model of schizophrenia. We then assessed whether changes in cortical or hippocampal GABA may underlie these effects. Female rats were ovariectomized and injected subchronically with PCP. To modulate E and LH, animals received estradiol capsules or Antide injections. Short-term episodic memory was assessed using the novel object recognition task (NORT). Brain expression of GAD67 was analyzed via western blot, and parvalbumin-containing cells were counted using immunohistochemistry. Some rats received hippocampal infusions of a GABA A agonist, GABA A antagonist, or GAD inhibitor before behavioral testing. We found that PCP reduced hippocampal GAD67 and abolished recognition memory. Antide restored hippocampal GAD67 and rescued recognition memory in PCP-treated animals. Estradiol prevented PCP's amnesic effect in NORT but failed to restore hippocampal GAD67. PCP did not cause significant differences in number of parvalbumin-expressing cells or cortical expression of GAD67. Hippocampal infusions of a GABA A agonist restored recognition memory in PCP-treated rats. Blocking hippocampal GAD or GABA A receptors in ovx animals reproduced recognition memory loss similar to PCP and inhibited estradiol's protection of recognition memory in PCP-treated animals. In summary, decreasing LH or increasing E can lessen short-term episodic memory loss, as measured by novel object recognition, in a PCP model of schizophrenia. Alterations in hippocampal GABA may contribute to both PCP's effects on recognition memory and the hormones' ability to prevent or reverse them. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Presynaptic gain control by endogenous cotransmission of dopamine and GABA in the olfactory bulb.

    PubMed

    Vaaga, Christopher E; Yorgason, Jordan T; Williams, John T; Westbrook, Gary L

    2017-03-01

    In the olfactory bulb, lateral inhibition mediated by local juxtaglomerular interneurons has been proposed as a gain control mechanism, important for decorrelating odorant responses. Among juxtaglomerular interneurons, short axon cells are unique as dual-transmitter neurons that release dopamine and GABA. To examine their intraglomerular function, we expressed channelrhodopsin under control of the DAT-cre promoter and activated olfactory afferents within individual glomeruli. Optical stimulation of labeled cells triggered endogenous dopamine release as measured by cyclic voltammetry and GABA release as measured by whole cell GABA A receptor currents. Activation of short axon cells reduced the afferent presynaptic release probability via D 2 and GABA B receptor activation, resulting in reduced spiking in both mitral and external tufted cells. Our results suggest that short axon cells influence glomerular activity not only by direct inhibition of external tufted cells but also by inhibition of afferent inputs to external tufted and mitral cells. NEW & NOTEWORTHY Sensory systems, including the olfactory system, encode information across a large dynamic range, making synaptic mechanisms of gain control critical to proper function. Here we demonstrate that a dual-transmitter interneuron in the olfactory bulb controls the gain of intraglomerular afferent input via two distinct mechanisms, presynaptic inhibition as well as inhibition of a principal neuron subtype, and thereby potently controls the synaptic gain of afferent inputs. Copyright © 2017 the American Physiological Society.

  17. Gad1 mRNA as a reliable indicator of altered GABA release from orexigenic neurons in the hypothalamus.

    PubMed

    Dicken, Matthew S; Hughes, Alexander R; Hentges, Shane T

    2015-11-01

    The strength of γ-aminobutyric acid (GABA)-mediated inhibitory synaptic input is a principle determinant of neuronal activity. However, because of differences in the number of GABA afferent inputs and the sites of synapses, it is difficult to directly assay for altered GABA transmission between specific cells. The present study tested the hypothesis that the level of mRNA for the GABA synthetic enzyme glutamate decarboxylase (GAD) can provide a reliable proxy for GABA release. This was tested in a mouse hypothalamic circuit important in the regulation of energy balance. Fluorescent in situ hybridization results show that the expression of Gad1 mRNA (encoding the GAD67 enzyme) was increased in hypothalamic neuropeptide Y/agouti-related peptide (NPY/AgRP) neurons after an overnight fast, consistent with the ability of GABA from these neurons to stimulate food intake. Optogenetic studies confirmed that the observed increase in Gad1 mRNA correlated with an increase in the probability of GABA release from NPY/AgRP neurons onto downstream proopiomelanocortin neurons. Likewise, there was an increase in the readily releasable pool of GABA in NPY/AgRP neurons. Selective inhibition of GAD activity in NPY/AgRP neurons decreased GABA release, indicating that GAD67 activity, which is largely dictated by expression level, is a key determinant of GABA release. Altogether, it appears that Gad expression may be a reliable proxy of altered GABAergic transmission. Examining changes in Gad mRNA as a proxy for GABA release may be particularly helpful when the downstream targets are not known or when limited tools exist for detecting GABA release at a particular synapse. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  18. Regulation of Local Ambient GABA Levels via Transporter-Mediated GABA Import and Export for Subliminal Learning.

    PubMed

    Hoshino, Osamu

    2015-06-01

    Perception of supraliminal stimuli might in general be reflected in bursts of action potentials (spikes), and their memory traces could be formed through spike-timing-dependent plasticity (STDP). Memory traces for subliminal stimuli might be formed in a different manner, because subliminal stimulation evokes a fraction (but not a burst) of spikes. Simulations of a cortical neural network model showed that a subliminal stimulus that was too brief (10 msec) to perceive transiently (more than about 500 msec) depolarized stimulus-relevant principal cells and hyperpolarized stimulus-irrelevant principal cells in a subthreshold manner. This led to a small increase or decrease in ongoing-spontaneous spiking activity frequency (less than 1 Hz). Synaptic modification based on STDP during this period effectively enhanced relevant synaptic weights, by which subliminal learning was improved. GABA transporters on GABAergic interneurons modulated local levels of ambient GABA. Ambient GABA molecules acted on extrasynaptic receptors, provided principal cells with tonic inhibitory currents, and contributed to achieving the subthreshold neuronal state. We suggest that ongoing-spontaneous synaptic alteration through STDP following subliminal stimulation may be a possible neuronal mechanism for leaving its memory trace in cortical circuitry. Regulation of local ambient GABA levels by transporter-mediated GABA import and export may be crucial for subliminal learning.

  19. Quality components and antidepressant-like effects of GABA green tea.

    PubMed

    Teng, Jie; Zhou, Wen; Zeng, Zhen; Zhao, Wenfang; Huang, Yahui; Zhang, Xu

    2017-09-20

    Gamma (γ)-aminobutyric acid (GABA) green tea, with high GABA content, is a kind of special green tea. The goals of this study are to analyze the changes in quality components of green tea during anaerobic treatment, and to investigate whether or not the extract of GABA present in green tea can prevent depression or improve the depressive state of animals. Results showed that GABA content in green tea had increased significantly after anaerobic treatment. The contents of tea polysaccharides, total free amino acids, and water extracts were also increased whereas tea polyphenols were reduced. More importantly, the extract of GABA green tea could alleviate mouse depression and stress from desperate environments through the forced swim test (FST), tail suspension test (TST), mRNA and protein expression levels of GABA A receptors. Therefore, these results indicate that GABA green tea may have a health effect on prevention and alleviation of depression, and it works on the GABAergic neurotransmission of mouse cerebral cortex via up-regulating expression of the GABA A receptor α1 subunit, thus ameliorating depression.

  20. In vivo electroretinographic studies of the role of GABA C receptors in retinal signal processing

    DOE PAGES

    Wang, Jing; Mojumder, Deb Kumar; Yan, Jun; ...

    2015-07-08

    The retina expresses all three classes of receptors for the inhibitory neurotransmitter GABA (GABAR). Our study investigated roles of GABAR, especially GABA(C)R (GABA(A)-rho), in retinal signaling in vivo by studying effects on the mouse electroretinogram (ERG) of genetic deletion of GABA(C)R versus pharmacological blockade using receptor antagonists. Brief full-field flash ERGs were recorded from anesthetized GABA(C)R(-/-) mice, and WT C57BL/6 (B6) mice, before and after intravitreal injection of GABA(C)R antagonists, TPMPA, 3-APMPA, or the more recently developed 2-AEMP; GABA(A)R antagonist, SR95531; GABA(B)R antagonist, CGP, and agonist, baclofen. Intravitreal injections of TPMPA and SR95531 were also made in Brown Norway rats.more » The effect of 2-AEMP on GABA-induced current was tested directly in isolated rat rod bipolar cells, and 2-AEMP was found to preferentially block GABA(C)R in those cells. Maximum amplitudes of dark (DA) and light-adapted (LA) ERG b-waves were reduced in GABA(C)R(-/-) mice, compared to B6 mice, by 30-60%; a-waves were unaltered and oscillatory potential amplitudes were increased. In B6 mice, after injection of TPMPA (also in rats), 3-APMPA or 2-AEMP, ERGs became similar to ERGs of GABA(C)R(-/-) mice. Blockade of GABA(A)Rs and GABA(B)Rs, or agonism of GABA(B)Rs did not alter B6 DA b-wave amplitude. Furthermore, the negative scotopic threshold response (nSTR) was slightly less sensitive in GABA(C)R(-/-) than in B6 mice, and unaltered by 2-AEMP. However, amplitudes of nSTR and photopic negative response (PhNR), both of which originate from inner retina, were enhanced by TPMPA and 3-APMPA, each of which has GABA(B) agonist properties, and further increased by baclofen. The finding that genetic deletion of GABA(C)R, the GABA(C)R antagonist 2-AEMP, and other antagonists all reduced ERG b-wave amplitude, supports a role for CABA(C)R in determining the maximum response amplitude of bipolar cells contributing to the b-wave. GABA

  1. GABA neurons are the major cell type of the nucleus reticularis thalami.

    PubMed

    Houser, C R; Vaughn, J E; Barber, R P; Roberts, E

    1980-11-03

    Glutamic acid decarboxylase (GAD), the synthesizing enzyme for the neurotransmitter gamma-aminobutyric acid (GABA), has been localized in a large number of neuronal somata within the nucleus reticularis thalami (NR) of rat brain by light microscopic immunocytochemical methods. GAD-positive staining of neuronal somata and proximal dendrites is observed in the NR of normal (untreated) rats, and this staining is substantially enhanced following colchicine injection into the lateral cerebral ventricle. GAD-positive neuronal cell bodies are prominent throughout the dorsoventral and rostrocaudal extents of the NR and, thus, form a band around the entire lateral aspect of the thalamus. In the lateral part of the NR, oval-shaped neurons with elongated GAD-positive dendritic processes are oriented parallel to the narrow axis of the NR and lie perpendicular to the penetrating fascicles of unstained thalamocortical and corticothalamic fibers. Semithin (2 micrometers) sections confirm that GAD-positive reaction product is contain within the cytoplasm of cell bodies and proximal dendrites. In addition, GAD-positive punctate structures, representing axon terminals, are present in the neuropil and, occasionally, are observed in close proximity to positively-stained neuronal somata. This finding suggests that GABA-mediated inhibition of GABA neurons may occur in the NR. The large number of GAD-positive cell bodies within the NR contrasts with a paucity of positively-stained somata in the more internally located thalamic nuclei. Within these nuclei, GAD-positive punctate structures that represent GABAergic synaptic sites are a characteristic feature. Since previous anatomical studies have demonstrated that a large proportion or reticularis neurons project into the thalamus, it is suggested that many of these GAD-positive punctate structures are the axon terminals of reticularis neurons. Through these projections, reticularis neurons may contribute to GABA-mediated inhibition within

  2. Co-localization of glycine and gaba immunoreactivity in interneurons in Macaca monkey cerebellar cortex.

    PubMed

    Crook, J; Hendrickson, A; Robinson, F R

    2006-09-15

    Previous work demonstrates that the cerebellum uses glycine as a fast inhibitory neurotransmitter [Ottersen OP, Davanger S, Storm-Mathisen J (1987) Glycine-like immunoreactivity in the cerebellum of rat and Senegalese baboon, Papio papio: a comparison with the distribution of GABA-like immunoreactivity and with [3H]glycine and [3H]GABA uptake. Exp Brain Res 66(1):211-221; Ottersen OP, Storm-Mathisen J, Somogyi P (1988) Colocalization of glycine-like and GABA-like immunoreactivities in Golgi cell terminals in the rat cerebellum: a postembedding light and electron microscopic study. Brain Res 450(1-2):342-353; Dieudonne S (1995) Glycinergic synaptic currents in Golgi cells of the rat cerebellum. Proc Natl Acad Sci U S A 92:1441-1445; Dumoulin A, Triller A, Dieudonne S (2001) IPSC kinetics at identified GABAergic and mixed GABAergic and glycinergic synapses onto cerebellar Golgi cells. J Neurosci 21(16):6045-6057; Dugue GP, Dumoulin A, Triller A, Dieudonne S (2005) Target-dependent use of coreleased inhibitory transmitters at central synapses. J Neurosci 25(28):6490-6498; Zeilhofer HU, Studler B, Arabadzisz D, Schweizer C, Ahmadi S, Layh B, Bosl MR, Fritschy JM (2005) Glycinergic neurons expressing enhanced green fluorescent protein in bacterial artificial chromosome transgenic mice. J Comp Neurol 482(2):123-141]. In the rat cerebellum glycine is not released by itself but is released together with GABA by Lugaro cells onto Golgi cells [Dumoulin A, Triller A, Dieudonne S (2001) IPSC kinetics at identified GABAergic and mixed GABAergic and glycinergic synapses onto cerebellar Golgi cells. J Neurosci 21(16):6045-6057] and by Golgi cells onto unipolar brush and granule cells [Dugue GP, Dumoulin A, Triller A, Dieudonne S (2005) Target-dependent use of coreleased inhibitory transmitters at central synapses. J Neurosci 25(28):6490-6498]. Here we report, from immunolabeling evidence in Macaca cerebellum, that interneurons in the granular cell layer are glycine+ at a density

  3. γ-Aminobutyric acid (GABA) signalling in plants.

    PubMed

    Ramesh, Sunita A; Tyerman, Stephen D; Gilliham, Matthew; Xu, Bo

    2017-05-01

    The role of γ-aminobutyric acid (GABA) as a signal in animals has been documented for over 60 years. In contrast, evidence that GABA is a signal in plants has only emerged in the last 15 years, and it was not until last year that a mechanism by which this could occur was identified-a plant 'GABA receptor' that inhibits anion passage through the aluminium-activated malate transporter family of proteins (ALMTs). ALMTs are multigenic, expressed in different organs and present on different membranes. We propose GABA regulation of ALMT activity could function as a signal that modulates plant growth, development, and stress response. In this review, we compare and contrast the plant 'GABA receptor' with mammalian GABA A receptors in terms of their molecular identity, predicted topology, mode of action, and signalling roles. We also explore the implications of the discovery that GABA modulates anion flux in plants, its role in signal transduction for the regulation of plant physiology, and predict the possibility that there are other GABA interaction sites in the N termini of ALMT proteins through in silico evolutionary coupling analysis; we also explore the potential interactions between GABA and other signalling molecules.

  4. Plasticity of rat central inhibitory synapses through GABA metabolism

    PubMed Central

    Engel, Dominique; Pahner, Ingrid; Schulze, Katrin; Frahm, Christiane; Jarry, Hubertus; Ahnert-Hilger, Gudrun; Draguhn, Andreas

    2001-01-01

    The production of the central inhibitory transmitter GABA (γ-aminobutyric acid) varies in response to different patterns of activity. It therefore seems possible that GABA metabolism can determine inhibitory synaptic strength and that presynaptic GABA content is a regulated parameter for synaptic plasticity. We altered presynaptic GABA metabolism in cultured rat hippocampal slices using pharmacological tools. Degradation of GABA by GABA-transaminase (GABA-T) was blocked by γ-vinyl-GABA (GVG) and synthesis of GABA through glutamate decarboxylase (GAD) was suppressed with 3-mercaptopropionic acid (MPA). We measured miniature GABAergic postsynaptic currents (mIPSCs) in CA3 pyramidal cells using the whole-cell patch clamp technique. Elevated intra-synaptic GABA levels after block of GABA-T resulted in increased mIPSC amplitude and frequency. In addition, tonic GABAergic background noise was enhanced by GVG. Electron micrographs from inhibitory synapses identified by immunogold staining for GABA confirmed the enhanced GABA content but revealed no further morphological alterations. The suppression of GABA synthesis by MPA had opposite functional consequences: mIPSC amplitude and frequency decreased and current noise was reduced compared with control. However, we were unable to demonstrate the decreased GABA content in biochemical analyses of whole slices or in electron micrographs. We conclude that the transmitter content of GABAergic vesicles is variable and that postsynaptic receptors are usually not saturated, leaving room for up-regulation of inhibitory synaptic strength. Our data reveal a new mechanism of plasticity at central inhibitory synapses and provide a rationale for the activity-dependent regulation of GABA synthesis in mammals. PMID:11533137

  5. GABA[subscript A] Receptor Downregulation in Brains of Subjects with Autism

    ERIC Educational Resources Information Center

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Thuras, Paul D.

    2009-01-01

    Gamma-aminobutyric acid A (GABA[subscript A]) receptors are ligand-gated ion channels responsible for mediation of fast inhibitory action of GABA in the brain. Preliminary reports have demonstrated altered expression of GABA receptors in the brains of subjects with autism suggesting GABA/glutamate system dysregulation. We investigated the…

  6. The GABA system in schizophrenia: cells, molecules and microcircuitry.

    PubMed

    Benes, Francine M

    2015-09-01

    This is an overview of several papers that have been published in the Special Issue of Schizophrenia Research entitled The GABA System in Schizophrenia: Cells, Molecules and Microcircuitry. This issue presents a broad range of original reports and scholarly reviews regarding recent progress in studies of neural circuitry in corticolimbic brain regions in patients with schizophrenia. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Genetic manipulation of the γ-aminobutyric acid (GABA) shunt in rice: overexpression of truncated glutamate decarboxylase (GAD2) and knockdown of γ-aminobutyric acid transaminase (GABA-T) lead to sustained and high levels of GABA accumulation in rice kernels.

    PubMed

    Shimajiri, Yasuka; Oonishi, Takayuki; Ozaki, Kae; Kainou, Kumiko; Akama, Kazuhito

    2013-06-01

    Gamma-aminobutyric acid (GABA) is a non-protein amino acid commonly present in all organisms. Because cellular levels of GABA in plants are mainly regulated by synthesis (glutamate decarboxylase, GAD) and catabolism (GABA-transaminase, GABA-T), we attempted seed-specific manipulation of the GABA shunt to achieve stable GABA accumulation in rice. A truncated GAD2 sequence, one of five GAD genes, controlled by the glutelin (GluB-1) or rice embryo globulin promoters (REG) and GABA-T-based trigger sequences in RNA interference (RNAi) cassettes controlled by one of these promoters as well, was introduced into rice (cv. Koshihikari) to establish stable transgenic lines under herbicide selection using pyriminobac. T₁ and T₂ generations of rice lines displayed high GABA concentrations (2-100 mg/100 g grain). In analyses of two selected lines from the T₃ generation, there was a strong correlation between GABA level and the expression of truncated GAD2, whereas the inhibitory effect of GABA-T expression was relatively weak. In these two lines both with two T-DNA copies, their starch, amylose, and protein levels were slightly lower than non-transformed cv. Koshihikari. Free amino acid analysis of mature kernels of these lines demonstrated elevated levels of GABA (75-350 mg/100 g polished rice) and also high levels of several amino acids, such as Ala, Ser, and Val. Because these lines of seeds could sustain their GABA content after harvest (up to 6 months), the strategy in this study could lead to the accumulation GABA and for these to be sustained in the edible parts. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  8. Virus-mediated swapping of zolpidem-insensitive with zolpidem-sensitive GABA(A) receptors in cortical pyramidal cells.

    PubMed

    Sumegi, Mate; Fukazawa, Yugo; Matsui, Ko; Lorincz, Andrea; Eyre, Mark D; Nusser, Zoltan; Shigemoto, Ryuichi

    2012-04-01

    Recently developed pharmacogenetic and optogenetic approaches, with their own advantages and disadvantages, have become indispensable tools in modern neuroscience. Here, we employed a previously described knock-in mouse line (GABA(A)Rγ2(77I)lox) in which the γ2 subunit of the GABA(A) receptor (GABA(A)R) was mutated to become zolpidem insensitive (γ2(77I)) and used viral vectors to swap γ2(77I) with wild-type, zolpidem-sensitive γ2 subunits (γ2(77F)). The verification of unaltered density and subcellular distribution of the virally introduced γ2 subunits requires their selective labelling. For this we generated six N- and six C-terminal-tagged γ2 subunits, with which cortical cultures of GABA(A)Rγ2(−/−) mice were transduced using lentiviruses. We found that the N-terminal AU1 tag resulted in excellent immunodetection and unimpaired synaptic localization. Unaltered kinetic properties of the AU1-tagged γ2 ((AU1)γ2(77F)) channels were demonstrated with whole-cell patch-clamp recordings of spontaneous IPSCs from cultured cells. Next, we carried out stereotaxic injections of lenti- and adeno-associated viruses containing Cre-recombinase and the (AU1)γ2(77F) subunit (Cre-2A-(AU1)γ2(77F)) into the neocortex of GABA(A)Rγ2(77I)lox mice. Light microscopic immunofluorescence and electron microscopic freeze-fracture replica immunogold labelling demonstrated the efficient immunodetection of the AU1 tag and the normal enrichment of the (AU1)γ2(77F) subunits in perisomatic GABAergic synapses. In line with this,miniature and action potential-evoked IPSCs whole-cell recorded from transduced cells had unaltered amplitudes, kinetics and restored zolpidem sensitivity. Our results obtained with a wide range of structural and functional verification methods reveal unaltered subcellular distributions and functional properties of γ2(77I) and (AU1)γ2(77F) GABA(A)Rs in cortical pyramidal cells. This transgenic–viral pharmacogenetic approach has the advantage that it

  9. Long-term administration with levonorgestrel decreases allopregnanolone levels and alters GABA(A) receptor subunit expression and anxiety-like behavior.

    PubMed

    Porcu, Patrizia; Mostallino, Maria Cristina; Sogliano, Cristiana; Santoru, Francesca; Berretti, Roberta; Concas, Alessandra

    2012-08-01

    Fluctuations in the concentrations of the neuroactive steroid allopregnanolone are thought to influence γ-amino-butyric acid type A (GABA(A)) receptor gene expression and function. Long-term treatment with ethinyl estradiol (EE) plus levonorgestrel (LNG), two of the most widely used steroids in the hormonal contraceptive pill, decreases allopregnanolone levels in rat cerebral cortex and plasma, alters GABA(A) receptor expression and induces anxiety-like behavior. We evaluated which component of the hormonal contraceptive pill is responsible for the aforementioned changes. Female rats were injected subcutaneously (s.c.) with EE (0.030 mg) or LNG (0.125 mg) once a day for 4 weeks. Compared to the respective vehicle-treated control groups, EE decreased cerebral cortical levels of allopregnanolone, progesterone and pregnenolone by 76, 72 and 33%, respectively and hippocampal levels by 52, 56 and 50%, respectively. Likewise, LNG decreased cerebral cortical levels of allopregnanolone, progesterone and pregnenolone by 75, 68 and 33%, respectively, and hippocampal levels by 55, 65 and 60%, respectively. Administration of LNG, but not EE, increased the abundance of the γ2 subunit peptide in cerebral cortex and hippocampus by 38 and 59%, respectively. Further, LNG, but not EE, decreased the time spent and the number of entries into the open arms of the elevated plus maze by 56 and 43%, respectively, an index of anxiety-like behavior. These results suggest that alterations in GABA(A) receptor subunit expression and anxiety-like behavior induced by long-term treatment with combined EE/LNG appear to be caused by LNG. Given that both EE and LNG decrease allopregnanolone levels in a similar manner, these results further suggest that changes in allopregnanolone levels are not associated with GABA(A) receptor expression. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Reconstruction of a metabolic regulatory network in Escherichia coli for purposeful switching from cell growth mode to production mode in direct GABA fermentation from glucose.

    PubMed

    Soma, Yuki; Fujiwara, Yuri; Nakagawa, Takuya; Tsuruno, Keigo; Hanai, Taizo

    2017-09-01

    γ-aminobutyric acid (GABA) is a drug and functional food additive and is used as a monomer for producing the biodegradable plastic, polyamide 4. Recently, direct GABA fermentation from glucose has been developed as an alternative to glutamate-based whole cell bioconversion. Although total productivity in fermentation is determined by the specific productivity and cell amount responsible for GABA production, the optimal metabolic state for GABA production conflicts with that for bacterial cell growth. Herein, we demonstrated metabolic state switching from the cell growth mode based on the metabolic pathways of the wild type strain to a GABA production mode based on a synthetic metabolic pathway in Escherichia coli through rewriting of the metabolic regulatory network and pathway engineering. The GABA production mode was achieved by multiple strategies such as conditional interruption of the TCA and glyoxylate cycles, engineering of GABA production pathway including a bypass for precursor metabolite supply, and upregulation of GABA transporter. As a result, we achieved 3-fold improvement in total GABA production titer and yield (4.8g/L, 49.2% (mol/mol glucose)) in batch fermentation compared to the case without metabolic state switching (1.6g/L, 16.4% (mol/mol glucose)). This study reports the highest GABA production performance among previous reports on GABA fermentation from glucose using engineered E. coli. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  11. Acetylcholine, carbachol, and GABA induce no detectable change in the length of isolated outer hair cells.

    PubMed

    Bobbin, R P; Fallon, M; Puel, J L; Bryant, G; Bledsoe, S C; Zajic, G; Schacht, J

    1990-08-01

    The mechanical and electrical properties of cochlear outer hair cells (OHCs) are suggested to modulate transduction by inner hair cells. These properties of OHCs are presumably regulated by efferent neurons which use several transmitters including acetylcholine (Ach) and gamma aminobutyric acid (GABA). Since it had been suggested that Ach causes isolated OHCs to shorten visibly, this study was designed to investigate whether GABA also alters the length of OHCs. OHCs were isolated from the guinea pig cochlea by mechanical dispersion after collagenase treatment. Cells were initially selected by strict morphological criteria. In addition they were only included in further studies if they attained a constant length during 10 min of superfusion with buffer solution. Neither GABA (20 microM: 100 microM), Ach (5 mM; 10 microM with 10 microM eserine) or carbachol (10 microM; 100 microM) altered OHC length when applied in iso-osmotic Hank's balanced salt solution (total number of cells tested, 72). If a change in length occurred it must have been smaller than 0.3 microns, our detection ability. In contrast, high potassium and variations in osmolarity changed hair cell length by 3-10% in agreement with other reports.

  12. Effects of simulated microgravity on the expression of presynaptic proteins distorting the GABA/glutamate equilibrium--A proteomics approach.

    PubMed

    Wang, Yun; Iqbal, Javed; Liu, Yahui; Su, Rui; Lu, Song; Peng, Guang; Zhang, Yongqian; Qing, Hong; Deng, Yulin

    2015-11-01

    Microgravity may cause cognition-related changes in the animal nervous system due to the resulting uneven flow of fluids in the body. These changes may restrict the long-term stay of humans in space for various purposes. In this study, a rat tail suspension model (30°) was used to explore the effects of 21 days of prolonged simulated microgravity (SM) on the expression of proteins involved in cognitive functions in the rat hippocampus. SM decreased the content of γ-aminobutyric acid (GABA) and increased the content of glutamate (Glu) in the rat hippocampus. A comparative (18)O-labeled quantitative proteomics strategy was applied to detect the differential expression of synaptic proteins under SM. Fifty-three proteins were found to be differentially expressed under SM. Microgravity induces difficulty in the formation of the SNARE complex due to the down-regulation of vesicle-associated membrane protein 3(VAMP3) and syntaxin-1A. Synaptic vesicle recycling may also be affected due to the dysregulation of syntaxin-binding protein 5 (tomosyn), rab3A and its effector rim2. Both processes are disturbed, indicating that presynaptic proteins mediate a GABA/Glu imbalance under SM. These findings provide clues for understanding the mechanism of the GABA/Glu equilibrium in the hippocampus induced by microgravity in space and represent steps toward safe space travel. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. GABA receptors and T-type Ca2+ channels crosstalk in thalamic networks.

    PubMed

    Leresche, Nathalie; Lambert, Régis C

    2017-06-07

    Although the thalamus presents a rather limited repertoire of GABAergic cell types compare to other CNS area, this structure is a privileged system to study how GABA impacts neuronal network excitability. Indeed both glutamatergic thalamocortical (TC) and GABAergic nucleus reticularis thalami (NRT) neurons present a high expression of T-type voltage-dependent Ca 2+ channels whose activation that shapes the output of the thalamus critically depends upon a preceding hyperpolarisation. Because of this strict dependence, a tight functional link between GABA mediated hyperpolarization and T-currents characterizes the thalamic network excitability. In this review we summarize a number of studies showing that the relationships between the various thalamic GABA A/B receptors and T-channels are complex and bidirectional. We discuss how this dynamic interaction sets the global intrathalamic network activity and its long-term plasticity and highlight how the functional relationship between GABA release and T-channel-dependent excitability is finely tuned by the T-channel activation itself. Finally, we illustrate how an impaired balance between T-channels and GABA receptors can lead to pathologically abnormal cellular and network behaviours. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Multiple functions of GABA A and GABA B receptors during pattern processing in the zebrafish olfactory bulb.

    PubMed

    Tabor, Rico; Yaksi, Emre; Friedrich, Rainer W

    2008-07-01

    gamma-Aminobutyric acid (GABA)ergic synapses are thought to play pivotal roles in the processing of activity patterns in the olfactory bulb (OB), but their functions have been difficult to study during odor responses in the intact system. We pharmacologically manipulated GABA(A) and GABA(B) receptors in the OB of zebrafish and analysed the effects on odor responses of the output neurons, the mitral cells (MCs), by electrophysiological recordings and temporally deconvolved two-photon Ca2+ imaging. The blockade of GABA(B) receptors enhanced presynaptic Ca2+ influx into afferent axon terminals, and changed the amplitude and time course of a subset of MC responses, indicating that GABA(B) receptors have a modulatory influence on OB output activity. The blockade of GABA(A) receptors induced epileptiform firing, enhanced excitatory responses and abolished fast oscillations in the local field potential. Moreover, the topological reorganization and decorrelation of MC activity patterns during the initial phase of the response was perturbed. These results indicate that GABA(A) receptor-containing circuits participate in the balance of excitation and inhibition, the regulation of total OB output activity, the synchronization of odor-dependent neuronal ensembles, and the reorganization of odor-encoding activity patterns. GABA(A) and GABA(B) receptors are therefore differentially involved in multiple functions of neuronal circuits in the OB.

  15. GABA promotes elastin synthesis and elastin fiber formation in normal human dermal fibroblasts (HDFs).

    PubMed

    Uehara, Eriko; Hokazono, Hideki; Hida, Mariko; Sasaki, Takako; Yoshioka, Hidekatsu; Matsuo, Noritaka

    2017-06-01

    The multiple physiological effects of γ-aminobutyric acid (GABA) as a functional food component have been recently reported. We previously reported that GABA upregulated the expression of type I collagen in human dermal fibroblasts (HDFs), and that oral administration of GABA significantly increased skin elasticity. However, details of the regulatory mechanism still remain unknown. In this study, we further examined the effects of GABA on elastin synthesis and elastin fiber formation in HDFs. Real-time PCR indicated that GABA significantly increased the expression of tropoelastin transcript in a dose-dependent manner. Additionally, the expression of fibrillin-1, fibrillin-2, and fibulin-5/DANCE, but not lysyl oxidase and latent transforming factor-β-binding protein 4, were also significantly increased in HDFs. Finally, immunohistochemical analysis confirmed that treatment with GABA dramatically increased the formation of elastic fibers in HDFs. Taken together, our results showed that GABA improves skin elasticity in HDFs by upregulating elastin synthesis and elastin fiber formation.

  16. Parvalbumin and neuropeptide Y expressing hippocampal GABA-ergic inhibitory interneuron numbers decline in a model of Gulf War illness.

    PubMed

    Megahed, Tarick; Hattiangady, Bharathi; Shuai, Bing; Shetty, Ashok K

    2014-01-01

    Cognitive dysfunction is amongst the most conspicuous symptoms in Gulf War illness (GWI). Combined exposure to the nerve gas antidote pyridostigmine bromide (PB), pesticides and stress during the Persian Gulf War-1 (PGW-1) are presumed to be among the major causes of GWI. Indeed, our recent studies in rat models have shown that exposure to GWI-related (GWIR) chemicals and mild stress for 4 weeks engenders cognitive impairments accompanied with several detrimental changes in the hippocampus. In this study, we tested whether reduced numbers of hippocampal gamma-amino butyric acid (GABA)-ergic interneurons are among the pathological changes induced by GWIR-chemicals and stress. Animals were exposed to low doses of GWIR-chemicals and mild stress for 4 weeks. Three months after this exposure, subpopulations of GABA-ergic interneurons expressing the calcium binding protein parvalbumin (PV), the neuropeptide Y (NPY) and somatostatin (SS) in the hippocampus were stereologically quantified. Animals exposed to GWIR-chemicals and stress for 4 weeks displayed reduced numbers of PV-expressing GABA-ergic interneurons in the dentate gyrus and NPY-expressing interneurons in the CA1 and CA3 subfields. However, no changes in SS+ interneuron population were observed in the hippocampus. Furthermore, GABA-ergic interneuron deficiency in these animals was associated with greatly diminished hippocampus neurogenesis. Because PV+ and NPY+ interneurons play roles in maintaining normal cognitive function and neurogenesis, and controlling the activity of excitatory neurons in the hippocampus, reduced numbers of these interneurons may be one of the major causes of cognitive dysfunction and reduced neurogenesis observed in GWI. Hence, strategies that improve inhibitory neurotransmission in the hippocampus may prove beneficial for reversing cognitive dysfunction in GWI.

  17. Zolpidem modulation of phasic and tonic GABA currents in the rat dorsal motor nucleus of the vagus

    PubMed Central

    Gao, Hong; Smith, Bret N.

    2010-01-01

    Zolpidem is a widely prescribed sleep aid with relative selectivity for GABAA receptors containing α1–3 subunits. We examined the effects of zolpidem on the inhibitory currents mediated by GABAA receptors using whole-cell patch-clamp recordings from DMV neurons in transverse brainstem slices from rat. Zolpidem prolonged the decay time of mIPSCs and of muscimol-evoked whole-cell GABAergic currents, and it occasionally enhanced the amplitude of mIPSCs. The effects were blocked by flumazenil, a benzodiazepine antagonist. Zolpidem also hyperpolarized the resting membrane potential, with a concomitant decrease in input resistance and action potential firing activity in a subset of cells. Zolpidem did not clearly alter the GABAA receptor-mediated tonic current (Itonic) under baseline conditions, but after elevating extracellular GABA concentration with nipecotic acid, a non-selective GABA transporter blocker, zolpidem consistently and significantly increased the tonic GABA current. This increase was suppressed by flumazenil and gabazine. These results suggest that α1–3 subunits are expressed in synaptic GABAA receptors on DMV neurons. The baseline tonic GABA current is likely not mediated by these same low affinity, zolpidem-sensitive GABAA receptors. However, when the extracellular GABA concentration is increased, zolpidem-sensitive extrasynaptic GABAA receptors containing α1–3 subunits contribute to the Itonic. PMID:20226798

  18. The role of GABA(A) receptors in the development of alcoholism.

    PubMed

    Enoch, Mary-Anne

    2008-07-01

    Alcoholism is a common, heritable, chronic relapsing disorder. GABA(A) receptors undergo allosteric modulation by ethanol, anesthetics, benzodiazepines and neurosteroids and have been implicated in the acute as well as the chronic effects of ethanol including tolerance, dependence and withdrawal. Medications targeting GABA(A) receptors ameliorate the symptoms of acute withdrawal. Ethanol induces plasticity in GABA(A) receptors: tolerance is associated with generally decreased GABA(A) receptor activation and differentially altered subunit expression. The dopamine (DA) mesolimbic reward pathway originating in the ventral tegmental area (VTA), and interacting stress circuitry play an important role in the development of addiction. VTA GABAergic interneurons are the primary inhibitory regulators of DA neurons and a subset of VTA GABA(A) receptors may be implicated in the switch from heavy drinking to dependence. GABA(A) receptors modulate anxiety and response to stress; important elements of sustained drinking and relapse. The GABA(A) receptor subunit genes clustered on chromosome 4 are highly expressed in the reward pathway. Several recent studies have provided strong evidence that one of these genes, GABRA2, is implicated in alcoholism in humans. The influence of the interaction between ethanol and GABA(A) receptors in the reward pathway on the development of alcoholism together with genetic and epigenetic vulnerabilities will be explored in this review.

  19. Invasive ability of human renal cell carcinoma cell line Caki-2 is accelerated by gamma-aminobutyric acid, via sustained activation of ERK1/2 inducible matrix metalloproteinases.

    PubMed

    Inamoto, Teruo; Azuma, Haruhito; Sakamoto, Takeshi; Kiyama, Satoshi; Ubai, Takanobu; Kotake, Yatsugu; Watanabe, Masahito; Katsuoka, Yoji

    2007-10-01

    Gamma-aminobutyric acid (GABA) was first discovered as an inhibitory neurotransmitter in the central nervous system (CNS) and has been reported to have a variety of functions, including regulation of cell division, cell differentiation and maturation, and to be involved in the development of certain cancers outside the CNS. In the present study, using the human renal cell carcinoma cell line Caki-2, we demonstrated that GABA stimulation significantly increased the expression of MMP-2 and -9 and subsequently increased the invasive activity of the cancer cells. Because MAPK signaling is one of the key regulators of MMP expression, we further evaluated MAPK signaling after stimulation with GABA. It was found that GABA stimulation promoted the phosphorylation of MAPKs, including ERK1/2, JNK, and p38. ERK1/2 phosphorylation was sustained for up to 12 h, while phosphorylation of JNK and p38 returned to the endogenous level by 30 min. It was noteworthy that the ras/raf/MEK/ERK pathway inhibitor PD98059 attenuated GABA-induced MMP-9 expression and that both PD98059 and MMP inhibitors attenuated the GABA-induced invasive activity of Caki-2 cells. Moreover, data obtained by depletion of the MEK/ERK pathway using interfering RNA transfection of Caki-2 cells clearly corroborated the above results, as both MMP-9 expression and GABA-induced invasive ability were decreased significantly. We also demonstrated that the GABA-induced increase in invasive ability via ERK1/2 up-regulation was mediated mainly through the GABA-B receptor. These results indicate that GABA stimulation promotes cancer cell invasion and that the effect is partly due to ERK1/2-dependent up-regulation of MMPs.

  20. [ERK activation effects on GABA secretion inhibition induced by SDF-1 in hippocampal neurons of rats].

    PubMed

    Zhang, Zi-juan; Guo, Mei-xia; Xing, Ying

    2015-09-01

    To investigate the effect of extracellular regulating kinase (ERK) signaling pathway on the secretion of gamma-aminobutyric acid (GABA) in cultured rat hippocampal neurons induced by stromal cell derived factor-1 (SDF-1). The hippocampal neurons of newborn SD rats were cultured and identified in vitro; the phosphorylation level of ERK1/2 was examined by Western blot; ELISA was used to detect the effect of PD98059, a ERK1/2 specific blocker on GABA secretion of cultured hippocampal neurons and Western blot were adopted to measure the protein expression levels of glutamate decarboxylase (GAD65/67) and gamma aminobutyric acid transporter (GAT); after blocking ERK1/2 signaling pathway with PD98059; RT-PCR was used to detect the mRNA expression levels of GAT-1 and GAD65 after treated with PD98059. The levels of ERKl/2 phosphorylation were increased significantly by SDF1 acting on hippocampal neurons, and CX-CR4 receptor blocker AMD3100, could inhibit SDF-1 induced ERK1/2 activation; SDF-1 could inhibit the secretion of GABA in cultured hippocampal neurons, and ERK1/2 specific inhibitor PD98059, could partly reverse the inhibition of GABA secretion by SDF-1. The effects of SDF-1 on cultured hippocampal neurons was to decrease the mRNA genesis of glutamic acid decarboxylase GAD65 and GABA transporter GAT-1, besides, ERK inhibitor PD98059 could effectively flip the effect of SDF-1. The results of Western blot showed that SDF-1 could inhibit the protein expression of GAT-1 and GAD65/67 in hippocampal neurons and the inhibition of GAT-1 and GAD65/67 protein expression could be partially restored by ERK1/2 blocker. SDF-1 acts on the CXCR4 of hippocampal neurons in vitro, and inhibits the expression of GAD by activating the ERK1/2 signaling pathway, and this may represent one possible pathway of GABA secretion inhibition.

  1. An autocrine γ-aminobutyric acid signaling system exists in pancreatic β-cell progenitors of fetal and postnatal mice.

    PubMed

    Feng, Mary M; Xiang, Yun-Yan; Wang, Shuanglian; Lu, Wei-Yang

    2013-01-01

    Gamma-aminobutyric acid (GABA) is produced and secreted by adult pancreatic β-cells, which also express GABA receptors mediating autocrine signaling and regulating β-cell proliferation. However, whether the autocrine GABA signaling involves in β-cell progenitor development or maturation remains uncertain. By means of immunohistochemistry we analyzed the expression profiles of the GABA synthesizing enzyme glutamic acid decarboxylase (GAD) and the α1-subunit of type-A GABA receptor (GABAARα1) in the pancreas of mice at embryonic day 15.5 (E15.5), E18.5, postnatal day 1 (P1) and P7. Our data showed that at E15.5 the pancreatic and duodenum homeobox-1 (Pdx1) was expressed in the majority of cells in the developing pancreata. Notably, insulin immunoreactivity was identified in a subpopulation of pancreatic cells with a high level of Pdx1 expression. About 80% of the high-level Pdx-1 expressing cells in the pancreas expressed GAD and GABAARα1 at all pancreatic developmental stages. In contrast, only about 30% of the high-level Pdx-1 expressing cells in the E15.5 pancreas expressed insulin; i.e., a large number of GAD/GABAARα1-expressing cells did not express insulin at this early developmental stage. The expression level of GAD and GABAARα1 increased steadily, and progressively more GAD/GABAARα1-expressing cells expressed insulin in the course of pancreatic development. These results suggest that 1) GABA signaling proteins appear in β-cell progenitors prior to insulin expression; and 2) the increased expression of GABA signaling proteins may be involved in β-cell progenitor maturation.

  2. γ-amino butyric acid (GABA) level as an overall survival risk factor in breast cancer.

    PubMed

    Brzozowska, Anna; Burdan, Franciszek; Duma, Dariusz; Solski, Janusz; Mazurkiewicz, Maria

    2017-09-21

    The γ-amino butyric acid (GABA) plays important role in the proliferation and migration of cancer cells. The aim of the study was to evaluate the level of GABA in breast cancer, in relation to clinical and epidemiological data. The study was conducted on 89 patients with breast cancer in stage I-II. GABA level was assessed using spectrofluorometric method in tumour homogenates. Immunoexpression of E-cadherin was evaluated histologically on paraffin fixed specimens. Overall and disease-free survival was assessed for a 15-year interval period. Median overall survival was significantly longer (127.2 months) in patients with a high level of GABA (>89.3 μg/1), compared with a group with a low level of the amino acid (106.4 months). Disease-free survival was insignificantly different - 99 and 109 months, respectively. A significantly longer overall survival (131.2 months) was seen among patients with a high level of GABA and positive E-cadherin immunoexpression, compared with a group characterized by a low level of GABA and lack of E-cadherin immunorectivity (98.1 months). The co-existence of negative immunoexpression of E-cadherin and low GABA concentration resulted in a six-fold increase in the risk of death (HR=6.03). GABA has a significant prognostic value in breast cancer. Co-existence of a low level of GABA and loss of E-cadherin immune-expression seems to be a new, independent, and negative prognostic marker of the neoplasm.

  3. The endogenous GABA bioactivity of camel, bovine, goat and human milks.

    PubMed

    Limon, Agenor; Gallegos-Perez, Jose-Luis; Reyes-Ruiz, Jorge M; Aljohi, Mohammad A; Alshanqeeti, Ali S; Miledi, Ricardo

    2014-02-15

    GABA orally administered has several beneficial effects on health, including the regulation of hyperglycaemic states in humans. Those effects are similar to the effects reported for camel milk (CMk); however, it is not known whether compounds with GABAergic activity are present in milk from camels or other species. We determined CMk free-GABA concentration by LS/MS and its bioactivity on human GABA receptors. We found that camel and goat milks have significantly more bioavailable GABA than cow and human milks and are able to activate GABAρ receptors. The relationship between GABA and taurine concentrations suggests that whole camel milk may be more efficient to activate GABAρ1 receptors than goat milk. Because GABAρ receptors are normally found in enteroendocrine cells in the lumen of the digestive tract, these results suggest that GABA in camel and goat milk may participate in GABA-modulated functions of enteroendocrine cells in the GI lumen. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Improvement in verbal memory following SSRI augmentation of antipsychotic treatment is associated with changes in the expression of mRNA encoding for the GABA-A receptor and BDNF in PMC of schizophrenic patients.

    PubMed

    Silver, Henry; Mandiuk, Nina; Einoch, Reef; Susser, Ehud; Danovich, Lena; Bilker, Warren; Youdim, Moussa; Weinreb, Orly

    2015-05-01

    Verbal memory impairment in schizophrenia is associated with abnormalities in gamma-aminobutyric acid (GABA)-ergic and brain-derived neurotrophic factor (BDNF) systems. Recent evidence from animal and clinical studies that adding fluvoxamine to antipsychotics alters the expression of transcripts encoding for the GABA-A receptor and BDNF led us to postulate that fluvoxamine augmentation may improve memory in schizophrenia. To test this, we examined the effect of add-on fluvoxamine on verbal memory and other cognitive functions and related it to the expression of mRNA coding for the GABA-A receptor and BDNF in peripheral mononuclear cells (PMC) of schizophrenic patients. Twenty-nine patients completed a 6-week study in which fluvoxamine (100 mg/day) was added to ongoing antipsychotic treatment. Verbal memory, abstraction working memory, object and face recognition, and psychomotor speed and clinical symptoms were assessed at baseline and after 3 and 6 weeks of treatment. Blood samples were taken at baseline and weeks 1, 3, and 6 and PMC was assayed for the GABA-A beta3 receptor and BDNF mRNA by quantitative real-time reverse transcription-PCR. Associative and logical verbal memory improved significantly and showed a significant correlation with changes in PMC BDNF and GABA-A beta3 receptor mRNA, which increased during treatment. Abstraction and object recognition improved, but this did not correlate with PMC measures. Negative and positive symptoms improved significantly; the latter showed significant correlations with changes in PMC measures. Addition of fluvoxamine to antipsychotics improves verbal memory. It is postulated that the mechanism involves enhanced GABA-A receptor/BDNF-dependent synaptic plasticity in the hippocampus.

  5. Defining Subpopulations of Arcuate Nucleus GABA Neurons in Male, Female, and Prenatally Androgenized Female Mice.

    PubMed

    Marshall, Christopher J; Desroziers, Elodie; McLennan, Timothy; Campbell, Rebecca E

    2017-01-01

    Arcuate nucleus (ARN) γ-aminobutyric acid (GABA) neurons are implicated in many critical homeostatic mechanisms, from food intake to fertility. To determine the functional relevance of ARN GABA neurons, it is essential to define the neurotransmitters co-expressed with and potentially co-released from ARN GABA neurons. The present study investigated the expression of markers of specific signaling molecules by ARN GABA neurons in brain sections from male, female, and, in some cases, prenatally androgen-treated (PNA) female, vesicular GABA transporter (VGaT)-ires-Cre/tdTomato reporter mice. Immunofluorescence for kisspeptin, β-endorphin, neuropeptide Y (NPY), tyrosine hydroxylase (TH) and neuronal nitric oxide synthase (nNOS) was detected by confocal microscopy, and co-localization with tdTomato VGaT reporter expression throughout the ARN was quantified. GABA neurons rarely co-localized with kisspeptin (<2%) or β-endorphin (<1%), and only a small proportion of kisspeptin (∼10%) or β-endorphin (∼3%) neurons co-localized with VGaT in male and female mice. In contrast, one-third of ARN GABA neurons co-localized with NPY, and nearly all NPY neurons (>95%) co-localized with VGaT across groups. Both TH and nNOS labeling was co-localized with ∼10% of ARN GABA neurons. The proportion of TH neurons co-localized with VGaT was significantly greater in males than either control or PNA females, and the proportion of nNOS neurons co-localizing VGaT was higher in control and PNA females compared with males. These data highlight NPY as a significant subpopulation of ARN GABA neurons, demonstrate no significant impact of PNA on signal co-expression, and, for the first time, show sexually dimorphic co-expression patterns of TH and nNOS with ARN GABA neurons. © 2016 S. Karger AG, Basel.

  6. Fiat lux! Phylogeny and bioinformatics shed light on GABA functions in plants.

    PubMed

    Renault, Hugues

    2013-06-01

    The non-protein amino acid γ-aminobutyric acid (GABA) accumulates in plants in response to a wide variety of environmental cues. Recent data point toward an involvement of GABA in tricarboxylic acid (TCA) cycle activity and respiration, especially in stressed roots. To gain further insights into potential GABA functions in plants, phylogenetic and bioinformatic approaches were undertaken. Phylogenetic reconstruction of the GABA transaminase (GABA-T) protein family revealed the monophyletic nature of plant GABA-Ts. However, this analysis also pointed to the common origin of several plant aminotransferases families, which were found more similar to plant GABA-Ts than yeast and human GABA-Ts. A computational analysis of AtGABA-T co-expressed genes was performed in roots and in stress conditions. This second approach uncovered a strong connection between GABA metabolism and glyoxylate cycle during stress. Both in silico analyses open new perspectives and hypotheses for GABA metabolic functions in plants.

  7. GABA metabolism pathway genes, UGA1 and GAD1, regulate replicative lifespan in Saccharomycescerevisiae

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kamei, Yuka; Tamura, Takayuki; Yoshida, Ryo

    2011-04-01

    Highlights: {yields}We demonstrate that two genes in the yeast GABA metabolism pathway affect aging. {yields} Deletion of the UGA1 or GAD1 genes extends replicative lifespan. {yields} Addition of GABA to wild-type cultures has no effect on lifespan. {yields} Intracellular GABA levels do not differ in longevity mutants and wild-type cells. {yields} Levels of tricarboxylic acid cycle intermediates positively correlate with lifespan. -- Abstract: Many of the genes involved in aging have been identified in organisms ranging from yeast to human. Our previous study showed that deletion of the UGA3 gene-which encodes a zinc-finger transcription factor necessary for {gamma}-aminobutyric acid (GABA)-dependentmore » induction of the UGA1 (GABA aminotransferase), UGA2 (succinate semialdehyde dehydrogenase), and UGA4 (GABA permease) genes-extends replicative lifespan in the budding yeast Saccharomycescerevisiae. Here, we found that deletion of UGA1 lengthened the lifespan, as did deletion of UGA3; in contrast, strains with UGA2 or UGA4 deletions exhibited no lifespan extension. The {Delta}uga1 strain cannot deaminate GABA to succinate semialdehyde. Deletion of GAD1, which encodes the glutamate decarboxylase that converts glutamate into GABA, also increased lifespan. Therefore, two genes in the GABA metabolism pathway, UGA1 and GAD1, were identified as aging genes. Unexpectedly, intracellular GABA levels in mutant cells (except for {Delta}uga2 cells) did not differ from those in wild-type cells. Addition of GABA to culture media, which induces transcription of the UGA structural genes, had no effect on replicative lifespan of wild-type cells. Multivariate analysis of {sup 1}H nuclear magnetic resonance spectra for the whole-cell metabolite levels demonstrated a separation between long-lived and normal-lived strains. Gas chromatography-mass spectrometry analysis of identified metabolites showed that levels of tricarboxylic acid cycle intermediates positively correlated with

  8. A Sensitive Period of Mice Inhibitory System to Neonatal GABA Enhancement by Vigabatrin is Brain Region Dependent

    PubMed Central

    Levav-Rabkin, Tamar; Melamed, Osnat; Clarke, Gerard; Farber, Malca; Cryan, John F; Dinan, Timothy G; Grossman, Yoram; Golan, Hava M

    2010-01-01

    Neurodevelopmental disorders, such as schizophrenia and autism, have been associated with disturbances of the GABAergic system in the brain. We examined immediate and long-lasting influences of exposure to the GABA-potentiating drug vigabatrin (GVG) on the GABAergic system in the hippocampus and cerebral cortex, before and during the developmental switch in GABA function (postnatal days P1–7 and P4–14). GVG induced a transient elevation of GABA levels. A feedback response to GABA enhancement was evident by a short-term decrease in glutamate decarboxylase (GAD) 65 and 67 levels. However, the number of GAD65/67-immunoreactive (IR) cells was greater in 2-week-old GVG-treated mice. A long-term increase in GAD65 and GAD67 levels was dependent on brain region and treatment period. Vesicular GABA transporter was insensitive to GVG. The overall effect of GVG on the Cl− co-transporters NKCC1 and KCC2 was an enhancement of their synthesis, which was dependent on the treatment period and brain region studied. In addition, a short-term increase was followed by a long-term decrease in KCC2 oligomerization in the cell membrane of P4–14 hippocampi and cerebral cortices. Analysis of the Ca2+ binding proteins expressed in subpopulations of GABAergic cells, parvalbumin and calbindin, showed region-specific effects of GVG during P4–14 on parvalbumin-IR cell density. Moreover, calbindin levels were elevated in GVG mice compared to controls during this period. Cumulatively, these results suggest a particular susceptibility of the hippocampus to GVG when exposed during days P4–14. In conclusion, our studies have identified modifications of key components in the inhibitory system during a critical developmental period. These findings provide novel insights into the deleterious consequences observed in children following prenatal and neonatal exposure to GABA-potentiating drugs. PMID:20043003

  9. Zinc ion enhances GABA tea-mediated oxidative DNA damage.

    PubMed

    Chuang, Show-Mei; Wang, Hsueh-Fang; Hsiao, Ching-Chuan; Cherng, Shur-Hueih

    2012-02-15

    GABA tea is a tea product that contains a high level of γ-aminobutyric acid (GABA). Previous study has demonstrated a synergistic effect of GABA tea and copper ions on DNA breakage. This study further explored whether zinc (Zn), a nonredox metal, modulated DNA cleavage induced by GABA tea extract. In a cell-free system, Zn(2+) significantly enhanced GABA tea extract and (-)-epigallocatechin-3-gallate (EGCG)- or H(2)O(2)-induced DNA damage at 24 h of incubation. Additionally, low dosages of GABA tea extract (1-10 μg/mL) possessed pro-oxidant activity to increase H(2)O(2)/Zn(2+)-induced DNA cleavage in a dose-dependent profile. By use of various reactive oxygen scavengers, it was observed that glutathione, catalase, and potassium iodide effectively inhibited DNA degradation caused by the GABA tea extract/H(2)O(2)/Zn(2+) system. Moreover, the data showed that the GABA tea extract itself (0.5-5 mg/mL) could induce DNA cleavage in a long-term exposure (48 h). EGCG, but not the GABA tea extract, enhanced H(2)O(2)-induced DNA cleavage. In contrast, GABA decreased H(2)O(2)- and EGCG-induced DNA cleavage, suggesting that GABA might contribute the major effect on the antioxidant activity of GABA tea extract. Furthermore, a comet assay revealed that GABA tea extract (0.25 mg/mL) and GABA had antioxidant activity on H(2)O(2)-induced DNA breakage in human peripheral lymphocytes. Taken together, these findings indicate that GABA tea has the potential of both pro-oxidant and antioxidant. It is proposed that a balance between EGCG-induced pro-oxidation and GABA-mediated antioxidation may occur in a complex mixture of GABA tea extract.

  10. Gene expression as a sensitive endpoint to evaluate cell differentiation and maturation of the developing central nervous system in primary cultures of rat cerebellar granule cells (CGCs) exposed to pesticides

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hogberg, Helena T.; Department of Physiology, Wenner-Gren Institute, Stockholm University; Kinsner-Ovaskainen, Agnieszka

    The major advantage of primary neuronal cultures for developmental neurotoxicity (DNT) testing is their ability to replicate the crucial stages of neurodevelopment. In our studies using primary culture of cerebellar granule cells (CGCs) we have evaluated whether the gene expression relevant to the most critical developmental processes such as neuronal differentiation (NF-68 and NF-200) and functional maturation (NMDA and GABA{sub A} receptors), proliferation and differentiation of astrocytes (GFAP and S100{beta}) as well as the presence of neural precursor cells (nestin and Sox10) could be used as an endpoint for in vitro DNT. The expression of these genes was assessed aftermore » exposure to various pesticides (paraquat parathion, dichlorvos, pentachlorophenol and cycloheximide) that could induce developmental neurotoxicity through different mechanisms. All studied pesticides significantly modified the expression of selected genes, related to the different stages of neuronal and/or glial cell development and maturation. The most significant changes were observed after exposure to paraquat and parathion (i.e. down-regulation of mRNA expression of NF-68 and NF-200, NMDA and GABA{sub A} receptors). Similarly, dichlorvos affected mainly neurons (decreased mRNA expression of NF-68 and GABA{sub A} receptors) whereas cycloheximide had an effect on neurons and astrocytes, as significant decreases in the mRNA expression of both neurofilaments (NF-68 and NF-200) and the astrocyte marker (S100{beta}) were observed. Our results suggest that toxicity induced by pesticides that target multiple pathways of neurodevelopment can be identified by studying expression of genes that are involved in different stages of cell development and maturation, and that gene expression could be used as a sensitive endpoint for initial screening to identify the compounds with the potential to cause developmental neurotoxicity.« less

  11. Embryonic GABA(B) receptor blockade alters cell migration, adult hypothalamic structure, and anxiety- and depression-like behaviors sex specifically in mice.

    PubMed

    Stratton, Matthew S; Staros, Michelle; Budefeld, Tomaz; Searcy, Brian T; Nash, Connor; Eitel, Chad; Carbone, David; Handa, Robert J; Majdic, Gregor; Tobet, Stuart A

    2014-01-01

    Neurons of the paraventricular nucleus of the hypothalamus (PVN) regulate the hypothalamic- pituitary-adrenal (HPA) axis and the autonomic nervous system. Females lacking functional GABA(B) receptors because of a genetic disruption of the R1 subunit have altered cellular characteristics in and around the PVN at birth. The genetic disruption precluded appropriate assessments of physiology or behavior in adulthood. The current study was conducted to test the long term impact of a temporally restricting pharmacological blockade of the GABA(B) receptor to a 7-day critical period (E11-E17) during embryonic development. Experiments tested the role of GABA(B) receptor signaling in fetal development of the PVN and later adult capacities for adult stress related behaviors and physiology. In organotypic slices containing fetal PVN, there was a female specific, 52% increase in cell movement speeds with GABA(B) receptor antagonist treatment that was consistent with a sex-dependent lateral displacement of cells in vivo following 7 days of fetal exposure to GABA(B) receptor antagonist. Anxiety-like and depression-like behaviors, open-field activity, and HPA mediated responses to restraint stress were measured in adult offspring of mothers treated with GABA(B) receptor antagonist. Embryonic exposure to GABA(B) receptor antagonist resulted in reduced HPA axis activation following restraint stress and reduced depression-like behaviors. There was also increased anxiety-like behavior selectively in females and hyperactivity in males. A sex dependent response to disruptions of GABA(B) receptor signaling was identified for PVN formation and key aspects of physiology and behavior. These changes correspond to sex specific prevalence in similar human disorders, namely anxiety disorders and hyperactivity.

  12. Gamma-amino butyric acid (GABA) release in the ciliated protozoon Paramecium occurs by neuronal-like exocytosis.

    PubMed

    Ramoino, P; Milanese, M; Candiani, S; Diaspro, A; Fato, M; Usai, C; Bonanno, G

    2010-04-01

    Paramecium primaurelia expresses a significant amount of gamma-amino butyric acid (GABA). Paramecia possess both glutamate decarboxylase (GAD)-like and vesicular GABA transporter (vGAT)-like proteins, indicating the ability to synthesize GABA from glutamate and to transport GABA into vesicles. Using antibodies raised against mammalian GAD and vGAT, bands with an apparent molecular weight of about 67 kDa and 57 kDa were detected. The presence of these bands indicated a similarity between the proteins in Paramecium and in mammals. VAMP, syntaxin and SNAP, putative proteins of the release machinery that form the so-called SNARE complex, are present in Paramecium. Most VAMP, syntaxin and SNAP fluorescence is localized in spots that vary in size and density and are primarily distributed near the plasma membrane. Antibodies raised against mammal VAMP-3, sintaxin-1 or SNAP-25 revealed protein immunoblot bands having molecular weights consistent with those observed in mammals. Moreover, P. primaurelia spontaneously releases GABA into the environment, and this neurotransmitter release significantly increases after membrane depolarization. The depolarization-induced GABA release was strongly reduced not only in the absence of extracellular Ca(2+) but also by pre-incubation with bafilomycin A1 or with botulinum toxin C1 serotype. It can be concluded that GABA occurs in Paramecium, where it is probably stored in vesicles capable of fusion with the cell membrane; accordingly, GABA can be released from Paramecium by stimulus-induced, neuronal-like exocytotic mechanisms.

  13. Hypothalamic neural systems controlling the female reproductive life cycle: Gonadotropin-releasing hormone, glutamate, and GABA

    PubMed Central

    Maffucci, Jacqueline A.; Gore, Andrea C.

    2009-01-01

    The hypothalamic-pituitary-gonadal (HPG) axis undergoes a number of changes throughout the reproductive life cycle that are responsible for the development, puberty, adulthood, and senescence of reproductive systems. This natural progression is dictated by the neural network controlling the hypothalamus including the cells that synthesize and release gonadotropin-releasing hormone (GnRH) and their regulatory neurotransmitters. Glutamate and GABA are the primary excitatory and inhibitory neurotransmitters in the central nervous system, and as such contribute a great deal to modulating this axis throughout the lifetime via their actions on receptors in the hypothalamus, both directly on GnRH neurons as well as indirectly though other hypothalamic neural networks. Interactions among GnRH neurons, glutamate, and GABA, including the regulation of GnRH gene and protein expression, hormone release, and modulation by estrogen, are critical to age-appropriate changes in reproductive function. Here, we present evidence for the modulation of GnRH neurosecretory cells by the balance of glutamate and GABA in the hypothalamus, and the functional consequences of these interactions on reproductive physiology across the life cycle. PMID:19349036

  14. Lack of effect of mossy fiber-released zinc on granule cell GABA(A) receptors in the pilocarpine model of epilepsy.

    PubMed

    Molnár, P; Nadler, J V

    2001-05-01

    The recurrent mossy fiber pathway of the dentate gyrus expands dramatically in the epileptic brain and serves as a mechanism for synchronization of granule cell epileptiform activity. It has been suggested that this pathway also promotes epileptiform activity by inhibiting GABA(A) receptor function through release of zinc. Hippocampal slices from pilocarpine-treated rats were used to evaluate this hypothesis. The rats had developed status epilepticus after pilocarpine administration, followed by robust recurrent mossy fiber growth. The ability of exogenously applied zinc to depress GABA(A) receptor function in dentate granule cells depended on removal of polyvalent anions from the superfusion medium. Under these conditions, 200 microM zinc reduced the amplitude of the current evoked by applying muscimol to the proximal portion of the granule cell dendrite (23%). It also reduced the mean amplitude (31%) and frequency (36%) of miniature inhibitory postsynaptic currents. Nevertheless, repetitive mossy fiber stimulation (10 Hz for 1 s, 100 Hz for 1 s, or 10 Hz for 5 min) at maximal intensity did not affect GABA(A) receptor-mediated currents evoked by photorelease of GABA onto the proximal portion of the dendrite, where recurrent mossy fiber synapses were located. These results could not be explained by stimulation-induced depletion of zinc from the recurrent mossy fiber boutons. Negative results were obtained even during exposure to conditions that promoted transmitter release and synchronized granule cell activity (6 mM [K(+)](o), nominally Mg(2+)-free medium, 33 degrees C). These results suggest that zinc released from the recurrent mossy fiber pathway did not reach a concentration at postsynaptic GABA(A) receptors sufficient to inhibit agonist-evoked activation.

  15. Imbalance between Glutamate and GABA in Fmr1 Knockout Astrocytes Influences Neuronal Development

    PubMed Central

    Wang, Lu; Wang, Yan; Zhou, Shimeng; Yang, Liukun; Shi, Qixin; Li, Yujiao; Zhang, Kun; Yang, Le; Zhao, Minggao; Yang, Qi

    2016-01-01

    Fragile X syndrome (FXS) is a form of inherited mental retardation that results from the absence of the fragile X mental retardation protein (FMRP), the product of the Fmr1 gene. Numerous studies have shown that FMRP expression in astrocytes is important in the development of FXS. Although astrocytes affect neuronal dendrite development in Fmr1 knockout (KO) mice, the factors released by astrocytes are still unclear. We cultured wild type (WT) cortical neurons in astrocyte-conditioned medium (ACM) from WT or Fmr1 KO mice. Immunocytochemistry and Western blotting were performed to detect the dendritic growth of both WT and KO neurons. We determined glutamate and γ-aminobutyric acid (GABA) levels using high-performance liquid chromatography (HPLC). The total neuronal dendritic length was reduced when cultured in the Fmr1 KO ACM. This neurotoxicity was triggered by an imbalanced release of glutamate and GABA from Fmr1 KO astrocytes. We found increased glutaminase and GABA transaminase (GABA-T) expression and decreased monoamine oxidase B expression in Fmr1 KO astrocytes. The elevated levels of glutamate contributed to oxidative stress in the cultured neurons. Vigabatrin (VGB), a GABA-T inhibitor, reversed the changes caused by glutamate and GABA release in Fmr1 KO astrocytes and the abnormal behaviors in Fmr1 KO mice. Our results indicate that the imbalance in the astrocytic glutamate and GABA release may be involved in the neuropathology and the underlying symptoms of FXS, and provides a therapeutic target for treatment. PMID:27517961

  16. Molecular Mechanisms Underlying γ-Aminobutyric Acid (GABA) Accumulation in Giant Embryo Rice Seeds.

    PubMed

    Zhao, Guo-Chao; Xie, Mi-Xue; Wang, Ying-Cun; Li, Jian-Yue

    2017-06-21

    To uncover the molecular mechanisms underlying GABA accumulation in giant embryo rice seeds, we analyzed the expression levels of GABA metabolism genes and contents of GABA and GABA metabolic intermediates in developing grains and germinated brown rice of giant embryo rice 'Shangshida No. 5' and normal embryo rice 'Chao2-10' respectively. In developing grains, the higher GABA contents in 'Shangshida No. 5' were accompanied with upregulation of gene transcripts and intermediate contents in the polyamine pathway and downregulation of GABA catabolic gene transcripts, as compared with those in 'Chao2-10'. In germinated brown rice, the higher GABA contents in 'Shangshida No. 5' were parallel with upregulation of OsGAD and polyamine pathway gene transcripts and Glu and polyamine pathway intermediate contents and downregulation of GABA catabolic gene transcripts. These results are the first to indicate that polyamine pathway and GABA catabolic genes play a crucial role in GABA accumulation in giant embryo rice seeds.

  17. Reduction of Phosphorylated Synapsin I (Ser-553) Leads to Spatial Memory Impairment by Attenuating GABA Release after Microwave Exposure in Wistar Rats

    PubMed Central

    Qiao, Simo; Peng, Ruiyun; Yan, Haitao; Gao, Yabing; Wang, Changzhen; Wang, Shuiming; Zou, Yong; Xu, Xinping; Zhao, Li; Dong, Ji; Su, Zhentao; Feng, Xinxin; Wang, Lifeng; Hu, Xiangjun

    2014-01-01

    Background Abnormal release of neurotransmitters after microwave exposure can cause learning and memory deficits. This study investigated the mechanism of this effect by exploring the potential role of phosphorylated synapsin I (p-Syn I). Methods Wistar rats, rat hippocampal synaptosomes, and differentiated (neuronal) PC12 cells were exposed to microwave radiation for 5 min at a mean power density of 30 mW/cm2. Sham group rats, synaptosomes, and cells were otherwise identically treated and acted as controls for all of the following post-exposure analyses. Spatial learning and memory in rats was assessed using the Morris Water Maze (MWM) navigation task. The protein expression and presynaptic distribution of p-Syn I and neurotransmitter transporters were examined via western blotting and immunoelectron microscopy, respectively. Levels amino acid neurotransmitter release from rat hippocampal synaptosomes and PC12 cells were measured using high performance liquid chromatograph (HPLC) at 6 hours after exposure, with or without synapsin I silencing via shRNA transfection. Results In the rat experiments, there was a decrease in spatial memory performance after microwave exposure. The expression of p-Syn I (ser-553) was decreased at 3 days post-exposure and elevated at later time points. Vesicular GABA transporter (VGAT) was significantly elevated after exposure. The GABA release from synaptosomes was attenuated and p-Syn I (ser-553) and VGAT were both enriched in small clear synaptic vesicles, which abnormally assembled in the presynaptic terminal after exposure. In the PC12 cell experiments, the expression of p-Syn I (ser-553) and GABA release were both attenuated at 6 hours after exposure. Both microwave exposure and p-Syn I silencing reduced GABA release and maximal reduction was found for the combination of the two, indicating a synergetic effect. Conclusion p-Syn I (ser-553) was found to play a key role in the impaired GABA release and cognitive dysfunction that was

  18. Reduction of phosphorylated synapsin I (ser-553) leads to spatial memory impairment by attenuating GABA release after microwave exposure in Wistar rats.

    PubMed

    Qiao, Simo; Peng, Ruiyun; Yan, Haitao; Gao, Yabing; Wang, Changzhen; Wang, Shuiming; Zou, Yong; Xu, Xinping; Zhao, Li; Dong, Ji; Su, Zhentao; Feng, Xinxin; Wang, Lifeng; Hu, Xiangjun

    2014-01-01

    Abnormal release of neurotransmitters after microwave exposure can cause learning and memory deficits. This study investigated the mechanism of this effect by exploring the potential role of phosphorylated synapsin I (p-Syn I). Wistar rats, rat hippocampal synaptosomes, and differentiated (neuronal) PC12 cells were exposed to microwave radiation for 5 min at a mean power density of 30 mW/cm2. Sham group rats, synaptosomes, and cells were otherwise identically treated and acted as controls for all of the following post-exposure analyses. Spatial learning and memory in rats was assessed using the Morris Water Maze (MWM) navigation task. The protein expression and presynaptic distribution of p-Syn I and neurotransmitter transporters were examined via western blotting and immunoelectron microscopy, respectively. Levels amino acid neurotransmitter release from rat hippocampal synaptosomes and PC12 cells were measured using high performance liquid chromatograph (HPLC) at 6 hours after exposure, with or without synapsin I silencing via shRNA transfection. In the rat experiments, there was a decrease in spatial memory performance after microwave exposure. The expression of p-Syn I (ser-553) was decreased at 3 days post-exposure and elevated at later time points. Vesicular GABA transporter (VGAT) was significantly elevated after exposure. The GABA release from synaptosomes was attenuated and p-Syn I (ser-553) and VGAT were both enriched in small clear synaptic vesicles, which abnormally assembled in the presynaptic terminal after exposure. In the PC12 cell experiments, the expression of p-Syn I (ser-553) and GABA release were both attenuated at 6 hours after exposure. Both microwave exposure and p-Syn I silencing reduced GABA release and maximal reduction was found for the combination of the two, indicating a synergetic effect. p-Syn I (ser-553) was found to play a key role in the impaired GABA release and cognitive dysfunction that was induced by microwave exposure.

  19. Sensitivity to Pigment-Dispersing Factor (PDF) Is Cell-Type Specific among PDF-Expressing Circadian Clock Neurons in the Madeira Cockroach.

    PubMed

    Gestrich, Julia; Giese, Maria; Shen, Wen; Zhang, Yi; Voss, Alexandra; Popov, Cyril; Stengl, Monika; Wei, HongYing

    2018-02-01

    Transplantation studies have pinpointed the circadian clock of the Madeira cockroach to the accessory medulla (AME) of the brain's optic lobes. The AME is innervated by approximately 240 adjacent neuropeptidergic neurons, including 12 pigment-dispersing factor (PDF)-expressing neurons anterior to the AME (aPDFMEs). Four of the aPDFMEs project contralaterally, controlling locomotor activity rhythms of the night-active cockroach. The present in vitro Ca 2+ imaging analysis focuses on contralaterally projecting AME neurons and their responses to PDF, GABA, and acetylcholine (ACh). First, rhodamine-dextran backfills from the contralateral optic stalk identified contralaterally projecting AME neurons, which were then dispersed in primary cell cultures. After characterization of PDF, GABA, and ACh responses, PDF immunocytochemistry identified ipsilaterally and contralaterally projecting PDFMEs. All PDF-sensitive clock neurons, PDF-immunoreactive clock neurons, and the majority of ipsilaterally and contralaterally projecting cells were excited by ACh. GABA inhibited all PDF-expressing clock neurons, and about half of other ipsilaterally projecting and most contralaterally projecting clock neurons. For the first time, we identified PDF autoreceptors in PDF-secreting cockroach circadian pacemakers. The medium-sized aPDFMEs and all other contralaterally projecting PDF-sensitive clock cells were inhibited by PDF. The ipsilaterally remaining small PDF-sensitive clock cells were activated by PDF. Only the largest aPDFME did not express PDF autoreceptors. We hypothesize that opposing PDF signaling generates 2 different ensembles of clock cells with antiphasic activity, regulating and maintaining a constant phase relationship between rest and activity cycles of the night-active cockroach.

  20. Effect of chronic treatment with the GABA transaminase inhibitors gamma-vinyl GABA and ethanolamine O-sulphate on the in vitro GABA release from rat hippocampus.

    PubMed

    Qume, M; Fowler, L J

    1997-10-01

    1. The effects of 2, 8 and 21 day oral treatment with the specific gamma-aminobutyric acid transaminase (GABA-T) inhibitors gamma-vinyl GABA (GVG) and ethanolamine O-sulphate (EOS) on brain GABA levels, GABA-T activity, and basal and stimulated GABA release from rat cross-chopped brain hippocampal slices was investigated. 2. Treatment with GABA-T inhibitors lead to a reduction in brain GABA-T activity by 65-80% compared with control values, with a concomitant increase in brain GABA content of 40-100%. 3. Basal hippocampal GABA release was increased to 250-450% of control levels following inhibition of GABA-T activity. No Ca2+ dependence was observed in either control or treated tissues. 4. GVG and EOS administration led to a significant elevation in the potassium stimulated release of GABA from cross-chopped hippocampal slices compared with that of controls. Although stimulated GABA release from control tissues was decreased in the presence of a low Ca2+ medium, GVG and EOS treatment abolished this Ca2+ dependency. 5. GABA compartmentalization, Na+ and Cl- coupled GABA uptake carriers and glial release may provide explanations for the loss of the Ca2+ dependency of stimulated GABA release observed following GVG and EOS treatment. 6. Administration of GABA-T inhibitors led to increases in both basal and stimulated hippocampal GABA release. However, it is not clear which is the most important factor in the anticonvulsant activity of these drugs, the increased GABA content 'leaking' out of neurones and glia leading to widespread inhibition, or the increase in stimulated GABA release which may occur following depolarization caused by an epileptic discharge.

  1. Effect of chronic treatment with the GABA transaminase inhibitors γ-vinyl GABA and ethanolamine O-sulphate on the in vitro GABA release from rat hippocampus

    PubMed Central

    Qume, M; Fowler, L J

    1997-01-01

    The effects of 2, 8 and 21 day oral treatment with the specific γ-aminobutyric acid transaminase (GABA-T) inhibitors γ-vinyl GABA (GVG) and ethanolamine O-sulphate (EOS) on brain GABA levels, GABA-T activity, and basal and stimulated GABA release from rat cross-chopped brain hippocampal slices was investigated. Treatment with GABA-T inhibitors lead to a reduction in brain GABA-T activity by 65–80% compared with control values, with a concomitant increase in brain GABA content of 40–100%. Basal hippocampal GABA release was increased to 250–450% of control levels following inhibition of GABA-T activity. No Ca2+ dependence was observed in either control or treated tissues. GVG and EOS administration led to a significant elevation in the potassium stimulated release of GABA from cross-chopped hippocampal slices compared with that of controls. Although stimulated GABA release from control tissues was decreased in the presence of a low Ca2+ medium, GVG and EOS treatment abolished this Ca2+ dependency. GABA compartmentalization, Na+ and Cl− coupled GABA uptake carriers and glial release may provide explanations for the loss of the Ca2+ dependency of stimulated GABA release observed following GVG and EOS treatment. Administration of GABA-T inhibitors led to increases in both basal and stimulated hippocampal GABA release. However, it is not clear which is the most important factor in the anticonvulsant activity of these drugs, the increased GABA content ‘leaking' out of neurones and glia leading to widespread inhibition, or the increase in stimulated GABA release which may occur following depolarization caused by an epileptic discharge. PMID:9351512

  2. The GABA Hypothesis in Essential Tremor: Lights and Shadows.

    PubMed

    Gironell, Alexandre

    2014-01-01

    The gamma-aminobutyric acid (GABA) hypothesis in essential tremor (ET) implies a disturbance of the GABAergic system, especially involving the cerebellum. This review examines the evidence of the GABA hypothesis. The review is based on published data about GABA dysfunction in ET, taking into account studies on cerebrospinal fluid, pathology, electrophysiology, genetics, neuroimaging, experimental animal models, and human drug therapies. Findings from several studies support the GABA hypothesis in ET. The hypothesis follows four steps: 1) cerebellar neurodegeneration with Purkinje cell loss; 2) a decrease in GABA system activity in deep cerebellar neurons; 3) disinhibition in output deep cerebellar neurons with pacemaker activity; and 4) an increase in rhythmic activity of the thalamus and thalamo-cortical circuit, contributing to the generation of tremor. Doubts have been cast on this hypothesis, however, by the fact that it is based on relatively few works, controversial post-mortem findings, and negative genetic studies on the GABA system. Furthermore, GABAergic drug efficacy is low and some GABAergic drugs do not have antitremoric efficacy. The GABA hypothesis continues to be the most robust pathophysiological hypothesis to explain ET. There is light in all GABA hypothesis steps, but a number of shadows cannot be overlooked. We need more studies to clarify the neurodegenerative nature of the disease, to confirm the decrease of GABA activity in the cerebellum, and to test more therapies that enhance the GABA transmission specifically in the cerebellum area.

  3. Region-specific expression of vesicular glutamate and GABA transporters under various ischaemic conditions in mouse forebrain and retina.

    PubMed

    Michalski, D; Härtig, W; Krügel, K; Edwards, R H; Böddener, M; Böhme, L; Pannicke, T; Reichenbach, A; Grosche, A

    2013-02-12

    There is accumulating evidence that glutamate and GABA release are key mechanisms of ischaemic events in the CNS. However, data on the expression of involved transporters for these mediators are inconsistent, potentially impeding further neuroprotective approaches. Here, we applied immunofluorescence labelling to characterise the expression pattern of vesicular glutamate (VGLUT) and GABA transporters (VGAT) after acute focal cerebral ischaemia and in two models of retinal ischaemia. Mice were subjected to filament-based focal cerebral ischaemia predominantly involving the middle cerebral artery territory, also leading to retinal ischaemia due to central retinal artery occlusion (CRAO). Alternatively, retinal ischaemia was induced by a transient increase of the intraocular pressure (HIOP). One day after ischaemia onset, diminished immunolabelling of neuronal nuclei and microtubule-associated protein 2-positive structures were found in the ipsilateral neocortex, subcortex and the retina, indicating neuronal degeneration. VGLUT1 expression did not change significantly in ischaemic tissues whereas VGLUT2 was down-regulated in specific areas of the brain. VGLUT3 expression was only slightly down-regulated in the ischaemia-affected neocortex, and was found to form clusters on fibrils of unknown origin in the ischaemic lateral hypothalamus. In contrast, retinae subjected to CRAO or HIOP displayed a rapid loss of VGLUT3-immunoreactivity. The expression of VGAT appears resistant to ischaemia as there was no significant alteration in all the regions analysed. In summary, these data indicate a region- and subtype-specific change of VGLUT expression in the ischaemia-affected CNS, whose consideration might help to generate specific neuroprotective strategies. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

  4. Alterations of cortical GABA neurons and network oscillations in schizophrenia.

    PubMed

    Gonzalez-Burgos, Guillermo; Hashimoto, Takanori; Lewis, David A

    2010-08-01

    The hypothesis that alterations of cortical inhibitory gamma-aminobutyric acid (GABA) neurons are a central element in the pathology of schizophrenia has emerged from a series of postmortem studies. How such abnormalities may contribute to the clinical features of schizophrenia has been substantially informed by a convergence with basic neuroscience studies revealing complex details of GABA neuron function in the healthy brain. Importantly, activity of the parvalbumin-containing class of GABA neurons has been linked to the production of cortical network oscillations. Furthermore, growing knowledge supports the concept that gamma band oscillations (30-80 Hz) are an essential mechanism for cortical information transmission and processing. Herein we review recent studies further indicating that inhibition from parvalbumin-positive GABA neurons is necessary to produce gamma oscillations in cortical circuits; provide an update on postmortem studies documenting that deficits in the expression of glutamic acid decarboxylase67, which accounts for most GABA synthesis in the cortex, are widely observed in schizophrenia; and describe studies using novel, noninvasive approaches directly assessing potential relations between alterations in GABA, oscillations, and cognitive function in schizophrenia.

  5. Gamma-vinyl GABA increases nonvesicular release of GABA and glutamate in the nucleus accumbens in rats via action on anion channels and GABA transporters

    PubMed Central

    Peng, Xiao-Qing; Gardner, Eliot L.

    2013-01-01

    Rationale γ-Amino butyric acid (GABA) is a well-characterized inhibitory neurotransmitter in the central nervous system, which may also stimulate nonvesicular release of other neurotransmitters under certain conditions. We have recently reported that γ-vinyl GABA (GVG), an irreversible GABA transaminase inhibitor, elevates extracellular GABA but fails to alter dopamine release in the nucleus accumbens (NAc). Objectives Here, we investigated the mechanism(s) by which GVG elevates extracellular GABA levels and whether GVG also alters glutamate release in the NAc. Materials and methods In vivo microdialysis was used to simultaneously measure extracellular NAc GABA and glutamate before and after GVG administration in freely moving rats. Results Systemic administration of GVG or intra-NAc local perfusion of GVG significantly increased extracellular NAc GABA and glutamate. GVG-enhanced GABA was completely blocked by intra-NAc local perfusion of 5-nitro-2, 3-(phenylpropylamino)-benzoic acid (NPPB), a selective anion channel blocker and partially blocked by SKF89976A, a type 1 GABA transporter inhibitor. GVG-enhanced glutamate was completely blocked by NPPB or SKF89976A. Tetrodotoxin, a voltage-dependent Na+-channel blocker, failed to alter GVG-enhanced GABA and glutamate. Conclusions These data suggest that GVG-enhanced extracellular GABA and glutamate are mediated predominantly by the opening of anion channels and partially by the reversal of GABA transporters. Enhanced extracellular glutamate may functionally attenuate the pharmacological action of GABA and prevent enhanced GABA-induced excess inhibition. PMID:20033132

  6. Accumulation of GABAergic neurons, causing a focal ambient GABA gradient, and downregulation of KCC2 are induced during microgyrus formation in a mouse model of polymicrogyria.

    PubMed

    Wang, Tianying; Kumada, Tatsuro; Morishima, Toshitaka; Iwata, Satomi; Kaneko, Takeshi; Yanagawa, Yuchio; Yoshida, Sachiko; Fukuda, Atsuo

    2014-04-01

    Although focal cortical malformations are considered neuronal migration disorders, their formation mechanisms remain unknown. We addressed how the γ-aminobutyric acid (GABA)ergic system affects the GABAergic and glutamatergic neuronal migration underlying such malformations. A focal freeze-lesion (FFL) of the postnatal day zero (P0) glutamic acid decarboxylase-green fluorescent protein knock-in mouse neocortex produced a 3- or 4-layered microgyrus at P7. GABAergic interneurons accumulated around the necrosis including the superficial region during microgyrus formation at P4, whereas E17.5-born, Cux1-positive pyramidal neurons outlined the GABAergic neurons and were absent from the superficial layer, forming cell-dense areas in layer 2 of the P7 microgyrus. GABA imaging showed that an extracellular GABA level temporally increased in the GABAergic neuron-positive area, including the necrotic center, at P4. The expression of the Cl(-) transporter KCC2 was downregulated in the microgyrus-forming GABAergic and E17.5-born glutamatergic neurons at P4; these cells may need a high intracellular Cl(-) concentration to induce depolarizing GABA effects. Bicuculline decreased the frequency of spontaneous Ca(2+) oscillations in these microgyrus-forming cells. Thus, neonatal FFL causes specific neuronal accumulation, preceded by an increase in ambient GABA during microgyrus formation. This GABA increase induces GABAA receptor-mediated Ca(2+) oscillation in KCC2-downregulated microgyrus-forming cells, as seen in migrating cells during early neocortical development.

  7. Astrocytic GABA transporter activity modulates excitatory neurotransmission

    PubMed Central

    Boddum, Kim; Jensen, Thomas P.; Magloire, Vincent; Kristiansen, Uffe; Rusakov, Dmitri A.; Pavlov, Ivan; Walker, Matthew C.

    2016-01-01

    Astrocytes are ideally placed to detect and respond to network activity. They express ionotropic and metabotropic receptors, and can release gliotransmitters. Astrocytes also express transporters that regulate the extracellular concentration of neurotransmitters. Here we report a previously unrecognized role for the astrocytic GABA transporter, GAT-3. GAT-3 activity results in a rise in astrocytic Na+ concentrations and a consequent increase in astrocytic Ca2+ through Na+/Ca2+ exchange. This leads to the release of ATP/adenosine by astrocytes, which then diffusely inhibits neuronal glutamate release via activation of presynaptic adenosine receptors. Through this mechanism, increases in astrocytic GAT-3 activity due to GABA released from interneurons contribute to 'diffuse' heterosynaptic depression. This provides a mechanism for homeostatic regulation of excitatory transmission in the hippocampus. PMID:27886179

  8. A study on the involvement of GABA-transaminase in MCT induced pulmonary hypertension.

    PubMed

    Lingeshwar, Poorella; Kaur, Gurpreet; Singh, Neetu; Singh, Seema; Mishra, Akanksha; Shukla, Shubha; Ramakrishna, Rachumallu; Laxman, Tulsankar Sachin; Bhatta, Rabi Sankar; Siddiqui, Hefazat H; Hanif, Kashif

    2016-02-01

    Increased sympathetic nervous system (SNS) activity is associated with cardiovascular diseases but its role has not been completely explored in pulmonary hypertension (PH). Increased SNS activity is distinguished by elevated level of norepinephrine (NE) and activity of γ-Amino butyric acid Transminase (GABA-T) which degrades GABA, an inhibitory neurotransmitter within the central and peripheral nervous system. Therefore, we hypothesized that GABA-T may contribute in pathophysiology of PH by modulating level of GABA and NE. The effect of daily oral administration of GABA-T inhibitor, Vigabatrin (GVG, 50 and 75 mg/kg/day, 35 days) was studied following a single subcutaneous administration of monocrotaline (MCT, 60 mg/kg) in male SD rats. The pressure and hypertrophy of right ventricle (RV), oxidative stress, inflammation, pulmonary vascular remodelling were assessed after 35 days in MCT treated rats. The expression of GABA-T and HIF-1α was studied in lung tissue. The levels of plasma NE (by High performance liquid chromatography coupled with electrochemical detector; HPLC-ECD) and lung GABA (by liquid chromatography-mass spectrometry) were also estimated. GVG at both doses significantly attenuated increased in pressure (35.82 ± 4.80 mm Hg, p < 0.001; 28.37 ± 3.32 mm Hg, p < 0.001 respectively) and hypertrophy of RV, pulmonary vascular remodelling, oxidative stress and inflammation in lungs of MCT exposed rats. GVG also reduced the expression of GABA-T and HIF-1α in MCT treated rats. Increased NE level and decreased GABA level was also reversed by GVG in MCT exposed rats. GABA-T plays an important role in PH by modulating SNS activity and may be considered as a therapeutic target in PH. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. GABA-CREB signalling regulates maturation and survival of newly generated neurons in the adult hippocampus

    PubMed Central

    Jagasia, Ravi; Steib, Kathrin; Englberger, Elisabeth; Herold, Sabine; Faus-Kessler, Theresa; Saxe, Michael; Gage, Fred H.; Song, Hongjun; Lie, D. Chichung

    2009-01-01

    Survival and integration of new neurons in the hippocampal circuit are rate-limiting steps in adult hippocampal neurogenesis. Neuronal network activity is a major regulator of these processes, yet little is known about the respective downstream signalling pathways. Here, we investigate the role of CREB signalling in adult hippocampal neurogenesis. CREB is activated in new granule neurons during a distinct developmental period. Loss of CREB function in a cell-autonomous fashion impairs dendritic development, decreases the expression of the neurogenic transcription factor NeuroD and of the neuronal microtubule associated protein, DCX, and compromises the survival of newborn neurons. In addition, GABA-mediated excitation regulates CREB activation at early developmental stages. Importantly, developmental defects following loss of GABA-mediated excitation can be compensated by enhanced CREB signalling. These results indicate that CREB signalling is a central pathway in adult hippocampal neurogenesis, regulating the development and survival of new hippocampal neurons downstream of GABA-mediated excitation. PMID:19553437

  10. Effects of GABA receptor antagonists on thresholds of P23H rat retinal ganglion cells to electrical stimulation of the retina

    NASA Astrophysics Data System (ADS)

    Jensen, Ralph J.; Rizzo, Joseph F., III

    2011-06-01

    An electronic retinal prosthesis may provide useful vision for patients suffering from retinitis pigmentosa (RP). In animal models of RP, the amount of current needed to activate retinal ganglion cells (RGCs) is higher than in normal, healthy retinas. In this study, we sought to reduce the stimulation thresholds of RGCs in a degenerate rat model (P23H-line 1) by blocking GABA receptor mediated inhibition in the retina. We examined the effects of TPMPA, a GABAC receptor antagonist, and SR95531, a GABAA receptor antagonist, on the electrically evoked responses of RGCs to biphasic current pulses delivered to the subretinal surface through a 400 µm diameter electrode. Both TPMPA and SR95531 reduced the stimulation thresholds of ON-center RGCs on average by 15% and 20% respectively. Co-application of the two GABA receptor antagonists had the greatest effect, on average reducing stimulation thresholds by 32%. In addition, co-application of the two GABA receptor antagonists increased the magnitude of the electrically evoked responses on average three-fold. Neither TPMPA nor SR95531, applied alone or in combination, had consistent effects on the stimulation thresholds of OFF-center RGCs. We suggest that the effects of the GABA receptor antagonists on ON-center RGCs may be attributable to blockage of GABA receptors on the axon terminals of ON bipolar cells.

  11. Contrast adaptation in cat visual cortex is not mediated by GABA.

    PubMed

    DeBruyn, E J; Bonds, A B

    1986-09-24

    The possible involvement of gamma-aminobutyric acid (GABA) in contrast adaptation in single cells in area 17 of the cat was investigated. Iontophoretic application of N-methyl bicuculline increased cell responses, but had no effect on the magnitude of adaptation. These results suggest that contrast adaptation is the result of inhibition through a parallel pathway, but that GABA does not mediate this process.

  12. Decreased surface expression of the δ subunit of the GABAA receptor contributes to reduced tonic inhibition in dentate granule cells in a mouse model of fragile X syndrome.

    PubMed

    Zhang, Nianhui; Peng, Zechun; Tong, Xiaoping; Lindemeyer, A Kerstin; Cetina, Yliana; Huang, Christine S; Olsen, Richard W; Otis, Thomas S; Houser, Carolyn R

    2017-11-01

    While numerous changes in the GABA system have been identified in models of Fragile X Syndrome (FXS), alterations in subunits of the GABA A receptors (GABA A Rs) that mediate tonic inhibition are particularly intriguing. Considering the key role of tonic inhibition in controlling neuronal excitability, reduced tonic inhibition could contribute to FXS-associated disorders such as hyperactivity, hypersensitivity, and increased seizure susceptibility. The current study has focused on the expression and function of the δ subunit of the GABA A R, a major subunit involved in tonic inhibition, in granule cells of the dentate gyrus in the Fmr1 knockout (KO) mouse model of FXS. Electrophysiological studies of dentate granule cells revealed a marked, nearly four-fold, decrease in tonic inhibition in the Fmr1 KO mice, as well as reduced effects of two δ subunit-preferring pharmacological agents, THIP and DS2, supporting the suggestion that δ subunit-containing GABA A Rs are compromised in the Fmr1 KO mice. Immunohistochemistry demonstrated a small but statistically significant decrease in δ subunit labeling in the molecular layer of the dentate gyrus in Fmr1 KO mice compared to wildtype (WT) littermates. The discrepancy between the large deficits in GABA-mediated tonic inhibition in granule cells in the Fmr1 KO mice and only modest reductions in immunolabeling of the δ subunit led to studies of surface expression of the δ subunit. Cross-linking experiments followed by Western blot analysis demonstrated a small, non-significant decrease in total δ subunit protein in the hippocampus of Fmr1 KO mice, but a four-fold decrease in surface expression of the δ subunit in these mice. No significant changes were observed in total or surface expression of the α4 subunit protein, a major partner of the δ subunit in the forebrain. Postembedding immunogold labeling for the δ subunit demonstrated a large, three-fold, decrease in the number of symmetric synapses with

  13. Seizure-induced alterations in fast-spiking basket cell GABA currents modulate frequency and coherence of gamma oscillation in network simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Proddutur, Archana; Yu, Jiandong; Elgammal, Fatima S.

    2013-12-15

    Gamma frequency oscillations have been proposed to contribute to memory formation and retrieval. Fast-spiking basket cells (FS-BCs) are known to underlie development of gamma oscillations. Fast, high amplitude GABA synapses and gap junctions have been suggested to contribute to gamma oscillations in FS-BC networks. Recently, we identified that, apart from GABAergic synapses, FS-BCs in the hippocampal dentate gyrus have GABAergic currents mediated by extrasynaptic receptors. Our experimental studies demonstrated two specific changes in FS-BC GABA currents following experimental seizures [Yu et al., J. Neurophysiol. 109, 1746 (2013)]: increase in the magnitude of extrasynaptic (tonic) GABA currents and a depolarizing shiftmore » in GABA reversal potential (E{sub GABA}). Here, we use homogeneous networks of a biophysically based model of FS-BCs to examine how the presence of extrasynaptic GABA conductance (g{sub GABA-extra}) and experimentally identified, seizure-induced changes in g{sub GABA-extra} and E{sub GABA} influence network activity. Networks of FS-BCs interconnected by fast GABAergic synapses developed synchronous firing in the dentate gamma frequency range (40–100 Hz). Systematic investigation revealed that the biologically realistic range of 30 to 40 connections between FS-BCs resulted in greater coherence in the gamma frequency range when networks were activated by Poisson-distributed dendritic synaptic inputs rather than by homogeneous somatic current injections, which were balanced for FS-BC firing frequency in unconnected networks. Distance-dependent conduction delay enhanced coherence in networks with 30–40 FS-BC interconnections while inclusion of gap junctional conductance had a modest effect on coherence. In networks activated by somatic current injections resulting in heterogeneous FS-BC firing, increasing g{sub GABA-extra} reduced the frequency and coherence of FS-BC firing when E{sub GABA} was shunting (−74 mV), but failed to alter

  14. Brain region-selective cellular redistribution of mGlu5 but not GABA(B) receptors following methamphetamine-induced associative learning.

    PubMed

    Herrold, Amy A; Voigt, Robin M; Napier, T Celeste

    2011-12-01

    Alterations in receptor expression and distribution between cell surface and cytoplasm are means by which psychostimulants regulate neurotransmission. Metabotropic glutamate receptor group I, subtype 5 (mGluR5) and GABA(B) receptors (GABA(B) R) are critically involved in the development and expression of stimulant-induced behaviors, including conditioned place preference (CPP), an index of drug-seeking. However, it is not known if psychostimulant-induced CPP alters the trafficking of these receptors. To fill this gap, this study used methamphetamine (Meth)-induced CPP in rats to ascertain if receptor changes occur in limbic brain regions that regulate drug-seeking, the medial prefrontal cortex (mPFC), nucleus accumbens (NAc), and ventral pallidum (VP). To do so, ex vivo tissue was assessed for changes in expression and surface vs. intracellular distribution of mGluR5 and GABA(B) Rs. There was a decrease in the surface to intracellular ratio of mGluR5 in the mPFC in Meth-conditioned rats, commensurate with an increase in intracellular levels. mGluR5 levels in the NAc or the VP were unaltered. There were no changes for GABA(B) R in any brain region assayed. This ex vivo snapshot of metabotropic glutamate and GABA receptor cellular distribution following induction of Meth-induced CPP is the first report to determine if these receptors are differentially altered after Meth-induced CPP. The results suggest that this Meth treatment paradigm likely induced a compensatory change in mGluR5 surface to intracellular ratio such that the surface remains unaltered while an increase in intracellular protein occurred. Copyright © 2011 Wiley-Liss, Inc.

  15. Color threshold and ratio of S100 beta, MAP5, NF68/200, GABA & GAD. I. Distribution in inner ear afferents

    NASA Technical Reports Server (NTRS)

    Fermin, C. D.; Martin, D. S.; Hara, H.

    1997-01-01

    Afferents of chick embryos (Gallus domesticus) VIIIth nerve were examined at E3, E6, E9, E13, El7, and hatching (NH) for anti-S100 beta, anti-MAP5, anti-GABA, anti-GAD and anti-NF68/200 stain. Different ages were processed together to determine if the distribution of these antibodies changed during synaptogenesis and myelination. Color thresholding showed that saturation of pixels changed for S100 beta only 5%, for NF68/200 10%, and for MAP5, 10%, between E9-NH. Color ratio of NF68/200 over MAP5 was 1.00 at E13 and 0.25 at E16 and NH. S100 beta, GABA and GAD were co-expressed on nerve endings at the edge of the maculae and center of the cristae, whereas hair cells in the center of the maculae expressed either S100 beta or GABA, but not both. S100 beta/NF68/200 shared antigenic sites on the chalices, but NF68/200 expression was higher than S100 beta in the chalices at hatching. MAP5 was expressed in more neurons than NF68/200 at E11, whereas NF68/200 was more abundant than MAP5 at hatching. The results suggest that: 1) the immunoexpression of these neuronal proteins is modulated concomitantly with the establishment of afferent synapses and myelination; 2) S100 beta may serve a neurotrophic function in the chalices where it is co-expressed with the neurotransmitter GABA and its synthesizing enzyme GAD.

  16. Functional reorganization of visual cortex maps after ischemic lesions is accompanied by changes in expression of cytoskeletal proteins and NMDA and GABA(A) receptor subunits.

    PubMed

    Zepeda, Angelica; Sengpiel, Frank; Guagnelli, Miguel Angel; Vaca, Luis; Arias, Clorinda

    2004-02-25

    Reorganization of cortical representations after focal visual cortex lesions has been documented. It has been suggested that functional reorganization may rely on cellular mechanisms involving modifications in the excitatory/inhibitory neurotransmission balance and on morphological changes of neurons peripheral to the lesion. We explored functional reorganization of cortical retinotopic maps after a focal ischemic lesion in primary visual cortex of kittens using optical imaging of intrinsic signals. After 1, 2, and 5 weeks postlesion (wPL), we addressed whether functional reorganization correlated in time with changes in the expression of MAP-2, GAP-43, GFAP, GABA(A) receptor subunit alpha1 (GABA(A)alpha1), subunit 1 of the NMDA receptor (NMDAR1), and in neurotransmitter levels at the border of the lesion. Our results show that: (1) retinotopic maps reorganize with time after an ischemic lesion; (2) MAP-2 levels increase gradually from 1wPL to 5wPL; (3) MAP-2 upregulation is associated with an increase in dendritic-like structures surrounding the lesion and a decrease in GFAP-positive cells; (4) GAP-43 levels reach the highest point at 2wPL; (5) NMDAR1 and glutamate contents increase in parallel from 1wPL to 5wPL; (6) GABA(A)alpha1 levels increase from 1wPL to 2wPL but do not change after this time point; and (7) GABA contents remain low from 1wPL to 5wPL. This is a comprehensive study showing for the first time that functional reorganization correlates in time with dendritic sprouting and with changes in the excitatory/inhibitory neurotransmission systems previously proposed to participate in cortical remodeling and suggests mechanisms by which plasticity of cortical representations may occur.

  17. GABA Signaling Promotes Synapse Elimination and Axon Pruning in Developing Cortical Inhibitory Interneurons

    PubMed Central

    Wu, Xiaoyun; Fu, Yu; Knott, Graham; Lu, Jiangteng; Di Cristo, Graziella

    2012-01-01

    Accumulating evidence indicates that GABA acts beyond inhibitory synaptic transmission and regulates the development of inhibitory synapses in the vertebrate brain, but the underlying cellular mechanism is not well understood. We have combined live imaging of cortical GABAergic axons across time scales from minutes to days with single-cell genetic manipulation of GABA release to examine its role in distinct steps of inhibitory synapse formation in the mouse neocortex. We have shown previously, by genetic knockdown of GABA synthesis in developing interneurons, that GABA signaling promotes the maturation of inhibitory synapses and axons. Here we found that a complete blockade of GABA release in basket interneurons resulted in an opposite effect, a cell-autonomous increase in axon and bouton density with apparently normal synapse structures. These results not only demonstrate that GABA is unnecessary for synapse formation per se but also uncover a novel facet of GABA in regulating synapse elimination and axon pruning. Live imaging revealed that developing GABAergic axons form a large number of transient boutons, but only a subset was stabilized. Release blockade led to significantly increased bouton stability and filopodia density, increased axon branch extension, and decreased branch retraction. Our results suggest that a major component of GABA function in synapse development is transmission-mediated elimination of subsets of nascent contacts. Therefore, GABA may regulate activity-dependent inhibitory synapse formation by coordinately eliminating certain nascent contacts while promoting the maturation of other nascent synapses. PMID:22219294

  18. Schizophrenia-like GABAergic gene expression deficits in cerebellar Golgi cells from rats chronically exposed to low-dose phencyclidine

    PubMed Central

    Bullock, W. Michael; Bolognani, Federico; Botta, Paolo; Valenzuela, C. Fernando; Perrone-Bizzozero, Nora I.

    2009-01-01

    One of the most consistent findings in schizophrenia is the decreased expression of the GABA synthesizing enzymes GAD67 and GAD65 in specific interneuron populations. This dysfunction is observed in distributed brain regions including the prefrontal cortex, hippocampus, and cerebellum. In an effort to understand the mechanisms for this GABA deficit, we investigated the effect of the N-methyl-D-aspartate receptor (NMDAR) antagonist phencyclidine (PCP), which elicits schizophrenia-like symptoms in both humans and animal models, in a chronic, low-dose exposure paradigm. Adult rats were given PCP at a dose of 2.58 mg/kg/day i.p. for a month, after which levels of various GABAergic cell mRNAs and other neuromodulators were examined in the cerebellum by RT-qPCR. Administration of PCP decreased the expression of GAD67, GAD65, and the presynaptic GABA transporter GAT-1, and increased GABAA receptor subunits similar to those seen in patients with schizophrenia. Additionally, we found that the mRNA levels of two Golgi cell selective NMDAR subunits, NR2B and NR2D, were decreased in PCP treated rats. Furthermore, we localized the deficits in GAD67 expression solely to these interneurons. Slice electrophysiological studies showed that spontaneous firing of Golgi cells was reduced by acute exposure to low dose PCP, suggesting that these neurons are particularly vulnerable to NMDA receptor antagonism. In conclusion, our results demonstrate that chronic exposure to low levels of PCP in rats mimics the GABAergic alterations reported in the cerebellum of patients with schizophrenia (Bullock et al., Am J Psychiatry 165: 1594-1603, 2008), further supporting the validity of this animal model. PMID:19651169

  19. Nonvesicular inhibitory neurotransmission via reversal of the GABA transporter GAT-1

    PubMed Central

    Wu, Yuanming; Wang, Wengang; Díez-Sampedro, Ana; Richerson, George B.

    2007-01-01

    SUMMARY GABA transporters play an important but poorly understood role in neuronal inhibition. They can reverse, but this is widely thought to occur only under pathological conditions. Here we use a heterologous expression system to show that the reversal potential of GAT-1 under physiologically relevant conditions is near the normal resting potential of neurons, and that reversal can occur rapidly enough to release GABA during simulated action potentials. We then use paired recordings from cultured hippocampal neurons, and show that GABAergic transmission is not prevented by four methods widely used to block vesicular release. This nonvesicular neurotransmission was potently blocked by GAT-1 antagonists, and was enhanced as predicted by agents that increase cytosolic [GABA] or [Na+]. The results indicate that GAT-1 regulates tonic inhibition by clamping ambient [GABA] at a level high enough to activate high affinity GABAA receptors, and that transporter-mediated GABA release can contribute to phasic inhibition. PMID:18054861

  20. Neuroprotection of ebselen against ischemia/reperfusion injury involves GABA shunt enzymes.

    PubMed

    Seo, Jeong Yeol; Lee, Choong Hyun; Cho, Jun Hwi; Choi, Jung Hoon; Yoo, Ki-Yeon; Kim, Dae Won; Park, Ok Kyu; Li, Hua; Choi, Soo Young; Hwang, In Koo; Won, Moo-Ho

    2009-10-15

    Seleno-organic compound, ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one), is a substrate with radical-scavenging activity. In this study, we observed the neuroprotective effects of ebselen against ischemic damage and on GABA shunt enzymes such as glutamic acid decarboxylase 67 (GAD67), GABA transaminse (GABA-T) and succinic semialdehyde dehydrogenase (SSADH) in the hippocampal CA1 region after 5 min of transient forebrain ischemia in gerbils. For this, vehicle (physiological saline) or ebselen was administered 30 min before or after ischemia/reperfusion and sacrificed 4 days after ischemia/reperfusion. The administration of ebselen significantly reduced the neuronal death in the CA1 region induced by ischemia/reperfusion. In addition, treatment with ebselen markedly elevated GAD67, GABA-T and SSADH immunoreactivity and their protein levels compared to that in the vehicle-treated group, respectively. These results suggest that ebselen protects neurons from ischemic damage via control of the expressions of GABA shunt enzymes to enter the TCA cycle.

  1. The PLC/IP3R/PKC Pathway is Required for Ethanol-enhanced GABA Release

    PubMed Central

    Kelm, M. Katherine; Weinberg, Richard J.; Criswell, Hugh E.; Breese, George R.

    2010-01-01

    Summary Research on the actions of ethanol at the GABAergic synapse has traditionally focused on postsynaptic mechanisms, but recent data demonstrate that ethanol also increases both evoked and spontaneous GABA release in many brain regions. Using whole-cell voltage-clamp recordings, we previously showed that ethanol increases spontaneous GABA release at the rat interneuron-Purkinje cell synapse. This presynaptic ethanol effect is dependent on calcium release from internal stores, possibly through activation of inositol 1,4,5-trisphosphate receptors (IP3Rs). After confirming that ethanol targets vesicular GABA release, in the present study we used electron microscopic immunohistochemistry to demonstrate that IP3Rs are located in presynaptic terminals of cerebellar interneurons. Activation of IP3Rs requires binding of IP3, generated through activation of phospholipase C (PLC). We find that the PLC antagonist edelfosine prevents ethanol from increasing spontaneous GABA release. Diacylglycerol generated by PLC and calcium released by activation of the IP3R activate protein kinase C (PKC). Ethanol-enhanced GABA release was blocked by two PKC antagonists, chelerythrine and calphostin C. When a membrane impermeable PKC antagonist, PKC (19-36), was delivered intracellularly to the postsynaptic neuron, ethanol continued to increase spontaneous GABA release. Overall, these results suggest that activation of the PLC/IP3R/PKC pathway is necessary for ethanol to increase spontaneous GABA release from presynaptic terminals onto Purkinje cells. PMID:20206640

  2. Stellate and pyramidal neurons in goldfish telencephalon respond differently to anoxia and GABA receptor inhibition.

    PubMed

    Hossein-Javaheri, Nariman; Wilkie, Michael P; Lado, Wudu E; Buck, Leslie T

    2017-02-15

    With oxygen deprivation, the mammalian brain undergoes hyper-activity and neuronal death while this does not occur in the anoxia-tolerant goldfish ( Carassius auratus ). Anoxic survival of the goldfish may rely on neuromodulatory mechanisms to suppress neuronal hyper-excitability. As γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain, we decided to investigate its potential role in suppressing the electrical activity of goldfish telencephalic neurons. Utilizing whole-cell patch-clamp recording, we recorded the electrical activities of both excitatory (pyramidal) and inhibitory (stellate) neurons. With anoxia, membrane potential ( V m ) depolarized in both cell types from -72.2 mV to -57.7 mV and from -64.5 mV to -46.8 mV in pyramidal and stellate neurons, respectively. While pyramidal cells remained mostly quiescent, action potential frequency (AP f ) of the stellate neurons increased 68-fold. Furthermore, the GABA A receptor reversal potential ( E - GABA ) was determined using the gramicidin perforated-patch-clamp method and found to be depolarizing in pyramidal (-53.8 mV) and stellate neurons (-42.1 mV). Although GABA was depolarizing, pyramidal neurons remained quiescent as E GABA was below the action potential threshold (-36 mV pyramidal and -38 mV stellate neurons). Inhibition of GABA A receptors with gabazine reversed the anoxia-mediated response. While GABA B receptor inhibition alone did not affect the anoxic response, co-antagonism of GABA A and GABA B receptors (gabazine and CGP-55848) led to the generation of seizure-like activities in both neuron types. We conclude that with anoxia, V m depolarizes towards E GABA which increases AP f in stellate neurons and decreases AP f in pyramidal neurons, and that GABA plays an important role in the anoxia tolerance of goldfish brain. © 2017. Published by The Company of Biologists Ltd.

  3. Non-Neuronal Release of Gamma-Aminobutyric Acid by Embryonic Pluripotent Stem Cells

    PubMed Central

    Teng, Lin; Tang, Ya-Bin; Sun, Fan; An, Shi-Min; Zhang, Chun; Yang, Xin-Jie; Lv, Hao-Yu; Lu, Qin; Cui, Yong-Yao; Hu, Jin-Jia

    2013-01-01

    γ-Aminobutyric acid (GABA), the principle inhibitory transmitter in the mature central nervous system, is also involved in activities outside the nervous system. Recent studies have shown that functional GABA receptors are expressed in embryonic stem (ES) cells and these receptors control ES cell proliferation. However, it is not clear whether ES cells have their own GABAergic transmission output machinery that can fulfill GABA release or whether the cells merely process the GABA receptors by receiving and responding to the diffused GABA released elsewhere. To get further insight into this unresolved problem, we detected the repertoire of components for GABA synthesis, storage, reaction, and termination in ES and embryonal carcinoma stem cells by biological assays, and then directly quantified released GABA in the intercellular milieu from these pluripotent stem (PS) cells by an analytical chemical assay based on high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). We found that embryonic PS cells processed a GABAergic circuit machinery and spontaneously released GABA, which suggests the potential that embryonic PS cells could autonomously establish a GABA niche via release of the transmitter. PMID:23799822

  4. GABA predicts visual intelligence.

    PubMed

    Cook, Emily; Hammett, Stephen T; Larsson, Jonas

    2016-10-06

    Early psychological researchers proposed a link between intelligence and low-level perceptual performance. It was recently suggested that this link is driven by individual variations in the ability to suppress irrelevant information, evidenced by the observation of strong correlations between perceptual surround suppression and cognitive performance. However, the neural mechanisms underlying such a link remain unclear. A candidate mechanism is neural inhibition by gamma-aminobutyric acid (GABA), but direct experimental support for GABA-mediated inhibition underlying suppression is inconsistent. Here we report evidence consistent with a global suppressive mechanism involving GABA underlying the link between sensory performance and intelligence. We measured visual cortical GABA concentration, visuo-spatial intelligence and visual surround suppression in a group of healthy adults. Levels of GABA were strongly predictive of both intelligence and surround suppression, with higher levels of intelligence associated with higher levels of GABA and stronger surround suppression. These results indicate that GABA-mediated neural inhibition may be a key factor determining cognitive performance and suggests a physiological mechanism linking surround suppression and intelligence. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  5. GABA and glutamate immunoreactivity in tentacles of the sea anemone Phymactis papillosa (LESSON 1830).

    PubMed

    Delgado, Luz M; Couve, Eduardo; Schmachtenberg, Oliver

    2010-07-01

    Sea anemones have a structurally simple nervous system that controls behaviors like feeding, locomotion, aggression, and defense. Specific chemical and tactile stimuli are transduced by ectodermal sensory cells and transmitted via a neural network to cnidocytes and epithelio-muscular cells, but the nature of the neurotransmitters operating in these processes is still under discussion. Previous studies demonstrated an important role of peptidergic transmission in cnidarians, but during the last decade the contribution of conventional neurotransmitters became increasingly evident. Here, we used immunohistochemistry on light and electron microscopical preparations to investigate the localization of glutamate and GABA in tentacle cross-sections of the sea anemone Phymactis papillosa. Our results demonstrate strong glutamate immunoreactivity in the nerve plexus, while GABA labeling was most prominent in the underlying epithelio-muscular layer. Immunoreactivity for both molecules was also found in glandular epithelial cells, and putative sensory cells were GABA positive. Under electron microscopy, both glutamate and GABA immunogold labeling was found in putative neural processes within the neural plexus. These data support a function of glutamate and GABA as signaling molecules in the nervous system of sea anemones.

  6. GABA from reactive astrocytes impairs memory in mouse models of Alzheimer's disease.

    PubMed

    Jo, Seonmi; Yarishkin, Oleg; Hwang, Yu Jin; Chun, Ye Eun; Park, Mijeong; Woo, Dong Ho; Bae, Jin Young; Kim, Taekeun; Lee, Jaekwang; Chun, Heejung; Park, Hyun Jung; Lee, Da Yong; Hong, Jinpyo; Kim, Hye Yun; Oh, Soo-Jin; Park, Seung Ju; Lee, Hyo; Yoon, Bo-Eun; Kim, YoungSoo; Jeong, Yong; Shim, Insop; Bae, Yong Chul; Cho, Jeiwon; Kowall, Neil W; Ryu, Hoon; Hwang, Eunmi; Kim, Daesoo; Lee, C Justin

    2014-08-01

    In Alzheimer's disease (AD), memory impairment is the most prominent feature that afflicts patients and their families. Although reactive astrocytes have been observed around amyloid plaques since the disease was first described, their role in memory impairment has been poorly understood. Here, we show that reactive astrocytes aberrantly and abundantly produce the inhibitory gliotransmitter GABA by monoamine oxidase-B (Maob) and abnormally release GABA through the bestrophin 1 channel. In the dentate gyrus of mouse models of AD, the released GABA reduces spike probability of granule cells by acting on presynaptic GABA receptors. Suppressing GABA production or release from reactive astrocytes fully restores the impaired spike probability, synaptic plasticity, and learning and memory in the mice. In the postmortem brain of individuals with AD, astrocytic GABA and MAOB are significantly upregulated. We propose that selective inhibition of astrocytic GABA synthesis or release may serve as an effective therapeutic strategy for treating memory impairment in AD.

  7. Arabidopsis aldehyde dehydrogenase 10 family members confer salt tolerance through putrescine-derived 4-aminobutyrate (GABA) production.

    PubMed

    Zarei, Adel; Trobacher, Christopher P; Shelp, Barry J

    2016-10-11

    Polyamines represent a potential source of 4-aminobutyrate (GABA) in plants exposed to abiotic stress. Terminal catabolism of putrescine in Arabidopsis thaliana involves amine oxidase and the production of 4-aminobutanal, which is a substrate for NAD + -dependent aminoaldehyde dehydrogenase (AMADH). Here, two AMADH homologs were chosen (AtALDH10A8 and AtALDH10A9) as candidates for encoding 4-aminobutanal dehydrogenase activity for GABA synthesis. The two genes were cloned and soluble recombinant proteins were produced in Escherichia coli. The pH optima for activity and catalytic efficiency of recombinant AtALDH10A8 with 3-aminopropanal as substrate was 10.5 and 8.5, respectively, whereas the optima for AtALDH10A9 were approximately 9.5. Maximal activity and catalytic efficiency were obtained with NAD + and 3-aminopropanal, followed by 4-aminobutanal; negligible activity was obtained with betaine aldehyde. NAD + reduction was accompanied by the production of GABA and β-alanine, respectively, with 4-aminobutanal and 3-aminopropanal as substrates. Transient co-expression systems using Arabidopsis cell suspension protoplasts or onion epidermal cells and several organelle markers revealed that AtALDH10A9 was peroxisomal, but AtALDH10A8 was cytosolic, although the N-terminal 140 amino acid sequence of AtALDH10A8 localized to the plastid. Root growth of single loss-of-function mutants was more sensitive to salinity than wild-type plants, and this was accompanied by reduced GABA accumulation.

  8. Ionotropic GABA Receptors and Distal Retinal ON and OFF Responses

    PubMed Central

    Popova, E.

    2014-01-01

    In the vertebrate retina, visual signals are segregated into parallel ON and OFF pathways, which provide information for light increments and decrements. The segregation is first evident at the level of the ON and OFF bipolar cells in distal retina. The activity of large populations of ON and OFF bipolar cells is reflected in the b- and d-waves of the diffuse electroretinogram (ERG). The role of gamma-aminobutyric acid (GABA), acting through ionotropic GABA receptors in shaping the ON and OFF responses in distal retina, is a matter of debate. This review summarized current knowledge about the types of the GABAergic neurons and ionotropic GABA receptors in the retina as well as the effects of GABA and specific GABAA and GABAC receptor antagonists on the activity of the ON and OFF bipolar cells in both nonmammalian and mammalian retina. Special emphasis is put on the effects on b- and d-waves of the ERG as a useful tool for assessment of the overall function of distal retinal ON and OFF channels. The role of GABAergic system in establishing the ON-OFF asymmetry concerning the time course and absolute and relative sensitivity of the ERG responses under different conditions of light adaptation in amphibian retina is also discussed. PMID:25143858

  9. Systematic Analysis of γ-Aminobutyric Acid (GABA) Metabolism and Function in the Social Amoeba Dictyostelium discoideum*

    PubMed Central

    Wu, Yuantai; Janetopoulos, Chris

    2013-01-01

    While GABA has been suggested to regulate spore encapsulation in the social amoeba Dictyostelium discoideum, the metabolic profile and other potential functions of GABA during development remain unclear. In this study, we investigated the homeostasis of GABA metabolism by disrupting genes related to GABA metabolism and signaling. Extracellular levels of GABA are tightly regulated during early development, and GABA is generated by the glutamate decarboxylase, GadB, during growth and in early development. However, overexpression of the prespore-specific homologue, GadA, in the presence of GadB reduces production of extracellular GABA. Perturbation of extracellular GABA levels delays the process of aggregation. Cytosolic GABA is degraded by the GABA transaminase, GabT, in the mitochondria. Disruption of a putative vesicular GABA transporter (vGAT) homologue DdvGAT reduces secreted GABA. We identified the GABAB receptor-like family member GrlB as the major GABA receptor during early development, and either disruption or overexpression of GrlB delays aggregation. This delay is likely the result of an abolished pre-starvation response and late expression of several “early” developmental genes. Distinct genes are employed for GABA generation during sporulation. During sporulation, GadA alone is required for generating GABA and DdvGAT is likely responsible for GABA secretion. GrlE but not GrlB is the GABA receptor during late development. PMID:23548898

  10. GABA regulates synaptic integration of newly generated neurons in the adult brain

    NASA Astrophysics Data System (ADS)

    Ge, Shaoyu; Goh, Eyleen L. K.; Sailor, Kurt A.; Kitabatake, Yasuji; Ming, Guo-Li; Song, Hongjun

    2006-02-01

    Adult neurogenesis, the birth and integration of new neurons from adult neural stem cells, is a striking form of structural plasticity and highlights the regenerative capacity of the adult mammalian brain. Accumulating evidence suggests that neuronal activity regulates adult neurogenesis and that new neurons contribute to specific brain functions. The mechanism that regulates the integration of newly generated neurons into the pre-existing functional circuitry in the adult brain is unknown. Here we show that newborn granule cells in the dentate gyrus of the adult hippocampus are tonically activated by ambient GABA (γ-aminobutyric acid) before being sequentially innervated by GABA- and glutamate-mediated synaptic inputs. GABA, the major inhibitory neurotransmitter in the adult brain, initially exerts an excitatory action on newborn neurons owing to their high cytoplasmic chloride ion content. Conversion of GABA-induced depolarization (excitation) into hyperpolarization (inhibition) in newborn neurons leads to marked defects in their synapse formation and dendritic development in vivo. Our study identifies an essential role for GABA in the synaptic integration of newly generated neurons in the adult brain, and suggests an unexpected mechanism for activity-dependent regulation of adult neurogenesis, in which newborn neurons may sense neuronal network activity through tonic and phasic GABA activation.

  11. Cocaine Dysregulates Opioid Gating of GABA Neurotransmission in the Ventral Pallidum

    PubMed Central

    Scofield, Michael D.; Rice, Kenner C.; Cheng, Kejun; Roques, Bernard P.

    2014-01-01

    The ventral pallidum (VP) is a target of dense nucleus accumbens projections. Many of these projections coexpress GABA and the neuropeptide enkephalin, a δ and μ opioid receptor (MOR) ligand. Of these two, the MOR in the VP is known to be involved in reward-related behaviors, such as hedonic responses to palatable food, alcohol intake, and reinstatement of cocaine seeking. Stimulating MORs in the VP decreases extracellular GABA, indicating that the effects of MORs in the VP on cocaine seeking are via modulating GABA neurotransmission. Here, we use whole-cell patch-clamp on a rat model of withdrawal from cocaine self-administration to test the hypothesis that MORs presynaptically regulate GABA transmission in the VP and that cocaine withdrawal changes the interaction between MORs and GABA. We found that in cocaine-extinguished rats pharmacological activation of MORs no longer presynaptically inhibited GABA release, whereas blocking the MORs disinhibited GABA release. Moreover, MOR-dependent long-term depression of GABA neurotransmission in the VP was lost in cocaine-extinguished rats. Last, GABA neurotransmission was found to be tonically suppressed in cocaine-extinguished rats. These substantial synaptic changes indicated that cocaine was increasing tone on MOR receptors. Accordingly, increasing endogenous tone by blocking the enzymatic degradation of enkephalin inhibited GABA neurotransmission in yoked saline rats but not in cocaine-extinguished rats. In conclusion, our results indicate that following withdrawal from cocaine self-administration enkephalin levels in the VP are elevated and the opioid modulation of GABA neurotransmission is impaired. This may contribute to the difficulties withdrawn addicts experience when trying to resist relapse. PMID:24431463

  12. 17A, a novel non-coding RNA, regulates GABA B alternative splicing and signaling in response to inflammatory stimuli and in Alzheimer disease.

    PubMed

    Massone, Sara; Vassallo, Irene; Fiorino, Gloria; Castelnuovo, Manuele; Barbieri, Federica; Borghi, Roberta; Tabaton, Massimo; Robello, Mauro; Gatta, Elena; Russo, Claudio; Florio, Tullio; Dieci, Giorgio; Cancedda, Ranieri; Pagano, Aldo

    2011-02-01

    Alternative splicing is a central component of human brain complexity; nonetheless, its regulatory mechanisms are still largely unclear. In this work, we describe a novel non-coding (nc) RNA (named 17A) RNA polymerase (pol) III-dependent embedded in the human G-protein-coupled receptor 51 gene (GPR51, GABA B2 receptor). The stable expression of 17A in SHSY5Y neuroblastoma cells induces the synthesis of an alternative splicing isoform that abolish GABA B2 intracellular signaling (i.e., inhibition of cAMP accumulation and activation of K(+) channels). Indeed, 17A is expressed in human brain, and we report that it is upregulated in cerebral tissues derived from Alzheimer disease patients. We demonstrate that 17A expression in neuroblastoma cells enhances the secretion of amyloid β peptide (Aβ) and the Aβ x-42/Αβ x-40 peptide ratio and that its synthesis is induced in response to inflammatory stimuli. These data correlate, for the first time, the activity of a novel pol III-dependent ncRNA to alternative splicing events and, possibly, to neurodegeneration induced by abnormal GABA B function. We anticipate that further analysis of pol III-dependent regulation of alternative splicing will disclose novel regulatory pathways associated to brain physiology and/or pathology. Copyright © 2010 Elsevier Inc. All rights reserved.

  13. Salmon lice (Lepeophtheirus salmonis) showing varying emamectin benzoate susceptibilities differ in neuronal acetylcholine receptor and GABA-gated chloride channel mRNA expression.

    PubMed

    Carmichael, Stephen N; Bron, James E; Taggart, John B; Ireland, Jacqueline H; Bekaert, Michaël; Burgess, Stewart Tg; Skuce, Philip J; Nisbet, Alasdair J; Gharbi, Karim; Sturm, Armin

    2013-06-18

    Caligid copepods, also called sea lice, are fish ectoparasites, some species of which cause significant problems in the mariculture of salmon, where the annual cost of infection is in excess of €300 million globally. At present, caligid control on farms is mainly achieved using medicinal treatments. However, the continued use of a restricted number of medicine actives potentially favours the development of drug resistance. Here, we report transcriptional changes in a laboratory strain of the caligid Lepeophtheirus salmonis (Krøyer, 1837) that is moderately (~7-fold) resistant to the avermectin compound emamectin benzoate (EMB), a component of the anti-salmon louse agent SLICE® (Merck Animal Health). Suppression subtractive hybridisation (SSH) was used to enrich transcripts differentially expressed between EMB-resistant (PT) and drug-susceptible (S) laboratory strains of L. salmonis. SSH libraries were subjected to 454 sequencing. Further L. salmonis transcript sequences were available as expressed sequence tags (EST) from GenBank. Contiguous sequences were generated from both SSH and EST sequences and annotated. Transcriptional responses in PT and S salmon lice were investigated using custom 15 K oligonucleotide microarrays designed using the above sequence resources. In the absence of EMB exposure, 359 targets differed in transcript abundance between the two strains, these genes being enriched for functions such as calcium ion binding, chitin metabolism and muscle structure. γ-aminobutyric acid (GABA)-gated chloride channel (GABA-Cl) and neuronal acetylcholine receptor (nAChR) subunits showed significantly lower transcript levels in PT lice compared to S lice. Using RT-qPCR, the decrease in mRNA levels was estimated at ~1.4-fold for GABA-Cl and ~2.8-fold for nAChR. Salmon lice from the PT strain showed few transcriptional responses following acute exposure (1 or 3 h) to 200 μg L-1 of EMB, a drug concentration tolerated by PT lice, but toxic for S lice

  14. Activating glutamate decarboxylase activity by removing the autoinhibitory domain leads to hyper γ-aminobutyric acid (GABA) accumulation in tomato fruit.

    PubMed

    Takayama, Mariko; Matsukura, Chiaki; Ariizumi, Tohru; Ezura, Hiroshi

    2017-01-01

    The C-terminal extension region of SlGAD3 is likely involved in autoinhibition, and removing this domain increases GABA levels in tomato fruits. γ-Aminobutyric acid (GABA) is a ubiquitous non-protein amino acid with several health-promoting benefits. In many plants including tomato, GABA is synthesized via decarboxylation of glutamate in a reaction catalyzed by glutamate decarboxylase (GAD), which generally contains a C-terminal autoinhibitory domain. We previously generated transgenic tomato plants in which tomato GAD3 (SlGAD3) was expressed using the 35S promoter/NOS terminator expression cassette (35S-SlGAD3-NOS), yielding a four- to fivefold increase in GABA levels in red-ripe fruits compared to the control. In this study, to further increase GABA accumulation in tomato fruits, we expressed SlGAD3 with (SlGAD3 OX ) or without (SlGAD3ΔC OX ) a putative autoinhibitory domain in tomato using the fruit ripening-specific E8 promoter and the Arabidopsis heat shock protein 18.2 (HSP) terminator. Although the GABA levels in SlGAD3 OX fruits were equivalent to those in 35S-SlGAD3-NOS fruits, GABA levels in SlGAD3ΔC OX fruits increased by 11- to 18-fold compared to control plants, indicating that removing the autoinhibitory domain increases GABA biosynthesis activity. Furthermore, the increased GABA levels were accompanied by a drastic reduction in glutamate and aspartate levels, indicating that enhanced GABA biosynthesis affects amino acid metabolism in ripe-fruits. Moreover, SlGAD3ΔC OX fruits exhibited an orange-ripe phenotype, which was associated with reduced levels of both carotenoid and mRNA transcripts of ethylene-responsive carotenogenic genes, suggesting that over activation of GAD influences ethylene sensitivity. Our strategy utilizing the E8 promoter and HSP terminator expression cassette, together with SlGAD3 C-terminal deletion, would facilitate the production of tomato fruits with increased GABA levels.

  15. Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics.

    PubMed

    Jin, Zhe; Bhandage, Amol K; Bazov, Igor; Kononenko, Olga; Bakalkin, Georgy; Korpi, Esa R; Birnir, Bryndis

    2014-01-01

    The central amygdala (CeA) has a role for mediating fear and anxiety responses. It is also involved in emotional imbalance caused by alcohol abuse and dependence and in regulating relapse to alcohol abuse. Growing evidences suggest that excitatory glutamatergic and inhibitory γ-aminobutyric acid-ergic (GABAergic) transmissions in the CeA are affected by chronic alcohol exposure. Human post-mortem CeA samples from male alcoholics (n = 9) and matched controls (n = 9) were assayed for the expression level of ionotropic glutamate and GABA-A receptors subunit mRNAs using quantitative real-time reverse transcription-PCR (RT-qPCR). Our data revealed that out of the 16 ionotropic glutamate receptor subunits, mRNAs encoding two AMPA [2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid] receptor subunits GluA1 and GluA4; one kainate receptor subunit GluK2; one NMDA (N-methyl-D-aspartate) receptor subunit GluN2D and one delta receptor subunit GluD2 were significantly decreased in the CeA of alcoholics. In contrast, of the 19 GABA-A receptor subunits, only the mRNA encoding the α2 subunit was significantly down-regulated in the CeA of the alcoholics as compared with control subjects. Our findings imply that the down-regulation of specific ionotropic glutamate and GABA-A receptor subunits in the CeA of alcoholics may represent one of the molecular substrates underlying the new balance between excitatory and inhibitory neurotransmission in alcohol dependence.

  16. Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics

    PubMed Central

    Jin, Zhe; Bhandage, Amol K.; Bazov, Igor; Kononenko, Olga; Bakalkin, Georgy; Korpi, Esa R.; Birnir, Bryndis

    2014-01-01

    The central amygdala (CeA) has a role for mediating fear and anxiety responses. It is also involved in emotional imbalance caused by alcohol abuse and dependence and in regulating relapse to alcohol abuse. Growing evidences suggest that excitatory glutamatergic and inhibitory γ-aminobutyric acid-ergic (GABAergic) transmissions in the CeA are affected by chronic alcohol exposure. Human post-mortem CeA samples from male alcoholics (n = 9) and matched controls (n = 9) were assayed for the expression level of ionotropic glutamate and GABA-A receptors subunit mRNAs using quantitative real-time reverse transcription-PCR (RT-qPCR). Our data revealed that out of the 16 ionotropic glutamate receptor subunits, mRNAs encoding two AMPA [2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid] receptor subunits GluA1 and GluA4; one kainate receptor subunit GluK2; one NMDA (N-methyl-D-aspartate) receptor subunit GluN2D and one delta receptor subunit GluD2 were significantly decreased in the CeA of alcoholics. In contrast, of the 19 GABA-A receptor subunits, only the mRNA encoding the α2 subunit was significantly down-regulated in the CeA of the alcoholics as compared with control subjects. Our findings imply that the down-regulation of specific ionotropic glutamate and GABA-A receptor subunits in the CeA of alcoholics may represent one of the molecular substrates underlying the new balance between excitatory and inhibitory neurotransmission in alcohol dependence. PMID:25278838

  17. GABA(C) receptors: a molecular view.

    PubMed

    Enz, R

    2001-08-01

    In the central nervous system inhibitory neurotransmission is primarily achieved through activation of receptors for gamma-aminobutyric acid (GABA). Three types of GABA receptors have been identified on the basis of their pharmacological and electrophysiological properties. The predominant type, termed GABA(A), and a recently identified GABA(C) type, form ligand-gated chloride channels, whereas GABA(B) receptors activate separate cation channels via G proteins. Based on their homology to nicotinic acetylcholine receptors, GABA(C) receptors are believed to be oligomeric protein complexes composed of five subunits in a pentameric arrangement. To date up to five different GABA(C) receptors subunits have been identified in various species. Recent studies have shed new light on the biological characteristics of GABA(C) receptors, including the chromosomal localization of its subunit genes and resulting links to deseases, the cloning of new splice variants, the identification of GABA(C) receptor-associated proteins, the identification of domains involved in subunit assembly, and finally structure/function studies examining functional consequences of introduced mutations. This review summarizes recent data in view of the molecular structure of GABA(C) receptors and presents new insights into the biological function of this protein in the retina.

  18. Acupuncture suppresses intravenous methamphetamine self-administration through GABA receptor's mediation.

    PubMed

    Choi, Yi Jeong; Kim, Nam Jun; Zhao, Rong Jie; Kim, Da Hye; Yang, Chae Ha; Kim, Hee Young; Gwak, Young S; Jang, Eun Young; Kim, Jae Su; Lee, Yun Kyu; Lee, Hyun Jong; Lee, Sang Nam; Lim, Sung Chul; Lee, Bong Hyo

    2018-01-01

    Methamphetamine is one of the widely abused drugs. In spite of a number of studies, there is still little successful therapy to suppress the methamphetamine abuse. Acupuncture has shown to attenuate the reinforcing effects of psychostimulant. Based on, the present study investigated if acupuncture could suppress intravenous methamphetamine self-administration behavior. In addition, a possible neuronal mechanism was investigated. Male Sprague-Dawley rats weighing 270-300g were trained to intake food pellet. After catheter implantation, animal was trained to self-administer methamphetamine (0.05mg/kg) intravenously using fixed ratio 1 schedule in daily 2h session during 3 weeks. After training, rats who established baseline (infusion variation less than 20% of the mean for 3 consecutive days) received acupuncture treatment on the next day. Acupuncture was performed at each acupoint manually. In the second experiment, the selective antagonists of GABA A or GABA B receptor were given before acupuncture to investigate the possible neuronal involvement of GABA receptor pathway in the acupuncture effects. C-Fos expression was examined in the nucleus accumbens to support behavioral data. Acupuncture at HT7, but not at control acupoint LI5, reduced the self-administration behavior significantly. Also, the effects of acupuncture were blocked by the GABA receptor antagonists. C-Fos expression was shown to be parallel with the behavioral data. Results of this study have shown that acupuncture at HT7 suppressed methamphetamine self-administration through GABA receptor system, suggesting that acupuncture at HT7 can be a useful therapy for the treatment of methamphetamine abuse. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Glutamate transporter EAAT4 in Purkinje cells controls intersynaptic diffusion of climbing fiber transmitter mediating inhibition of GABA release from interneurons.

    PubMed

    Satake, Shin'ichiro; Song, Si-Young; Konishi, Shiro; Imoto, Keiji

    2010-12-01

    Neurotransmitters diffuse out of the synaptic cleft and act on adjacent synapses to exert concerted control of the synaptic strength within neural pathways that converge on single target neurons. The excitatory transmitter released from climbing fibers (CFs), presumably glutamate, is shown to inhibit γ-aminobutyric acid (GABA) release at basket cell (BC)-Purkinje cell (PC) synapses in the rat cerebellar cortex through its extrasynaptic diffusion and activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors on BC axon terminals. This study aimed at examining how the CF transmitter-diffusion-mediated presynaptic inhibition is controlled by glutamate transporters. Pharmacological blockade of the PC-selective neuronal transporter EAAT4 markedly enhanced CF-induced inhibition of GABAergic transmission. Tetanic CF-stimulation elicited long-term potentiation of glutamate transporters in PCs, and thereby attenuated the CF-induced inhibition. Combined use of electrophysiology and immunohistochemistry revealed a significant inverse relationship between the level of EAAT4 expression and the inhibitory action of CF-stimulation on the GABA release at different cerebellar lobules - the CF-induced inhibition was profound in lobule III, where the EAAT4 expression level was low, whereas it was minimal in lobule X, where EAAT4 was abundant. The findings clearly demonstrate that the neuronal glutamate transporter EAAT4 in PCs plays a critical role in the extrasynaptic diffusion of CF transmitter - it appears not only to retrogradely determine the degree of CF-mediated inhibition of GABAergic inputs to the PC by controlling the glutamate concentration for intersynaptic diffusion, but also regulate synaptic information processing in the cerebellar cortex depending on its differential regional distribution as well as use-dependent plasticity of uptake efficacy. © 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience

  20. Prefrontal Cortical GABA Transmission Modulates Discrimination and Latent Inhibition of Conditioned Fear: Relevance for Schizophrenia

    PubMed Central

    Piantadosi, Patrick T; Floresco, Stan B

    2014-01-01

    Inhibitory gamma-aminobutyric acid (GABA) transmission within the prefrontal cortex (PFC) regulates numerous functions, and perturbations in GABAergic transmission within this region have been proposed to contribute to some of the cognitive and behavioral abnormalities associated with disorders such as schizophrenia. These abnormalities include deficits in emotional regulation and aberrant attributions of affective salience. Yet, how PFC GABA regulates these types of emotional processes are unclear. To address this issue, we investigated the contribution of PFC GABA transmission to different aspects of Pavlovian emotional learning in rats using translational discriminative fear conditioning and latent inhibition (LI) assays. Reducing prelimbic PFC GABAA transmission via infusions of the antagonist bicuculline before the acquisition or expression of fear conditioning eliminated the ability to discriminate between an aversive conditioned stimulus (CS+) paired with footshock vs a neutral CS–, resembling similar deficits observed in schizophrenic patients. In a separate experiment, blockade of PFC GABAA receptors before CS preexposure (PE) and conditioning did not affect subsequent expression of LI, but did enhance fear in rats that were not preexposed to the CS. In contrast, PFC GABA-blockade before a fear expression test disrupted the recall of learned irrelevance and abolished LI. These data suggest that normal PFC GABA transmission is critical for regulating and mitigating multiple aspects of aversive learning, including discrimination between fear vs safety signals and recall of information about the irrelevance of stimuli. Furthermore, they suggest that similar deficits in emotional regulation observed in schizophrenia may be driven in part by deficient PFC GABA activity. PMID:24784549

  1. Prefrontal cortical GABA transmission modulates discrimination and latent inhibition of conditioned fear: relevance for schizophrenia.

    PubMed

    Piantadosi, Patrick T; Floresco, Stan B

    2014-09-01

    Inhibitory gamma-aminobutyric acid (GABA) transmission within the prefrontal cortex (PFC) regulates numerous functions, and perturbations in GABAergic transmission within this region have been proposed to contribute to some of the cognitive and behavioral abnormalities associated with disorders such as schizophrenia. These abnormalities include deficits in emotional regulation and aberrant attributions of affective salience. Yet, how PFC GABA regulates these types of emotional processes are unclear. To address this issue, we investigated the contribution of PFC GABA transmission to different aspects of Pavlovian emotional learning in rats using translational discriminative fear conditioning and latent inhibition (LI) assays. Reducing prelimbic PFC GABAA transmission via infusions of the antagonist bicuculline before the acquisition or expression of fear conditioning eliminated the ability to discriminate between an aversive conditioned stimulus (CS+) paired with footshock vs a neutral CS-, resembling similar deficits observed in schizophrenic patients. In a separate experiment, blockade of PFC GABAA receptors before CS preexposure (PE) and conditioning did not affect subsequent expression of LI, but did enhance fear in rats that were not preexposed to the CS. In contrast, PFC GABA-blockade before a fear expression test disrupted the recall of learned irrelevance and abolished LI. These data suggest that normal PFC GABA transmission is critical for regulating and mitigating multiple aspects of aversive learning, including discrimination between fear vs safety signals and recall of information about the irrelevance of stimuli. Furthermore, they suggest that similar deficits in emotional regulation observed in schizophrenia may be driven in part by deficient PFC GABA activity.

  2. Control of cortical neuronal migration by glutamate and GABA

    PubMed Central

    Luhmann, Heiko J.; Fukuda, A.; Kilb, W.

    2015-01-01

    Neuronal migration in the cortex is controlled by the paracrine action of the classical neurotransmitters glutamate and GABA. Glutamate controls radial migration of pyramidal neurons by acting primarily on NMDA receptors and regulates tangential migration of inhibitory interneurons by activating non-NMDA and NMDA receptors. GABA, acting on ionotropic GABAA-rho and GABAA receptors, has a dichotomic action on radially migrating neurons by acting as a GO signal in lower layers and as a STOP signal in upper cortical plate (CP), respectively. Metabotropic GABAB receptors promote radial migration into the CP and tangential migration of interneurons. Besides GABA, the endogenous GABAergic agonist taurine is a relevant agonist controlling radial migration. To a smaller extent glycine receptor activation can also influence radial and tangential migration. Activation of glutamate and GABA receptors causes increases in intracellular Ca2+ transients, which promote neuronal migration by acting on the cytoskeleton. Pharmacological or genetic manipulation of glutamate or GABA receptors during early corticogenesis induce heterotopic cell clusters in upper layers and loss of cortical lamination, i.e., neuronal migration disorders which can be associated with neurological or neuropsychiatric diseases. The pivotal role of NMDA and ionotropic GABA receptors in cortical neuronal migration is of major clinical relevance, since a number of drugs acting on these receptors (e.g., anti-epileptics, anesthetics, alcohol) may disturb the normal migration pattern when present during early corticogenesis. PMID:25688185

  3. Technological and safety properties of newly isolated GABA-producing Lactobacillus futsaii strains.

    PubMed

    Sanchart, C; Rattanaporn, O; Haltrich, D; Phukpattaranont, P; Maneerat, S

    2016-09-01

    To evaluate the technological and safety properties of Lactobacillus futsaii CS3 and CS5 isolated from Thai fermented shrimp products (Kung-Som) in order to develop a valuable gamma-aminobutyric acid (GABA)-producing starter culture. Both strains showed a high GABA-producing ability (>8 mg ml(-1) ) in MRS broth containing 20 mg ml(-1) monosodium glutamate (MSG) for 120 h. They also exhibited inhibitory activity against foodborne pathogens and spoilage bacteria. Cell surface hydrophobicity and proteolytic activity were observed in both strains. Strain CS3 survived better under simulated gastrointestinal tract conditions with only 1·5 log-units cell decrease over 8 h. Both strains showed the ability to deconjugate taurocholate and taurodeoxycholate acid. Neither virulence genes nor biogenic amine production was detected. Strain CS3 exhibited susceptibility to all tested antibiotics with the exception of vancomycin, while strain CS5 showed resistance to vancomycin, ampicillin and chloramphenicol. Based on the results obtained, Lact. futsaii CS3 is very promising as a GABA-producing and potentially probiotic starter culture strain for applications in functional fermented foods. This study focuses on the technological and safety characteristics of Lact. futsaii CS3 and CS5 including their high GABA-producing capacity for the first time. This provides a way of replacing chemical GABA by natural GABA using a GABA-producing starter culture candidate, at the same time offering the consumer new attractive food products. © 2016 The Society for Applied Microbiology.

  4. Metabotropic GABAB receptors mediate GABA inhibition of acetylcholine release in the rat neuromuscular junction.

    PubMed

    Malomouzh, Artem I; Petrov, Konstantin A; Nurullin, Leniz F; Nikolsky, Evgeny E

    2015-12-01

    Gamma-aminobutyric acid (GABA) is an amino acid which acts as a neurotransmitter in the central nervous system. Here, we studied the effects of GABA on non-quantal, spontaneous, and evoked quantal acetylcholine (ACh) release from motor nerve endings. We found that while the application of 10 μM of GABA had no effect on spontaneous quantal ACh release, as detected by the frequency of miniature endplate potentials, GABA reduced the non-quantal ACh release by 57%, as determined by the H-effect value. Finally, the evoked quantal ACh release, estimated by calculating the quantal content of full-sized endplate potentials (EPPs), was reduced by 34%. GABA's inhibitory effect remained unchanged after pre-incubation with picrotoxin, an ionotropic GABAA receptor blocker, but was attenuated following application of the GABAB receptor blocker CGP 55845, which itself had no effect on ACh release. An inhibitor of phospholipase C, U73122, completely prevented the GABA-induced decrease in ACh release. Immunofluorescence demonstrated the presence of both subunits of the GABAB receptor (GABAB R1 and GABAB R2) in the neuromuscular junction. These findings suggest that metabotropic GABAB receptors are expressed in the mammalian neuromuscular synapse and their activation results in a phospholipase C-mediated reduction in the intensity of non-quantal and evoked quantal ACh release. We investigated the effect of gamma-aminobutyric acid (GABA) on neuromuscular transmission. GABA reduced the non-quantal and evoked quantal release of acetylcholine. These effects are mediated by GABAB receptors and are implemented via phospholipase C (PLC) activation. Our findings suggest that in the mammalian neuromuscular synapse, metabotropic GABAB receptors are expressed and their activation results in a reduction in the intensity of acetylcholine release. © 2015 International Society for Neurochemistry.

  5. Context-dependent modulation of alphabetagamma and alphabetadelta GABA A receptors by penicillin: implications for phasic and tonic inhibition.

    PubMed

    Feng, Hua-Jun; Botzolakis, Emmanuel J; Macdonald, Robert L

    2009-01-01

    Penicillin, an open-channel blocker of GABA(A) receptors, was recently reported to inhibit phasic, but not tonic, currents in hippocampal neurons. To distinguish between isoform-specific and context-dependent modulation as possible explanations for this selectivity, the effects of penicillin were evaluated on recombinant GABA(A) receptors expressed in HEK293T cells. When co-applied with saturating GABA, penicillin decreased peak amplitude, induced rebound, and prolonged deactivation of currents evoked from both synaptic and extrasynaptic receptor isoforms. However, penicillin had isoform-specific effects on the extent of desensitization, reflecting its ability to differentially modulate peak (non-equilibrium) and residual (near-equilibrium) currents. This suggested that the context of activation could determine the apparent sensitivity of a given receptor isoform to penicillin. To test this hypothesis, we explored the ability of penicillin to modulate synaptic and extrasynaptic isoform currents that were activated under more physiologically relevant conditions. Interestingly, while currents evoked from synaptic isoforms under phasic conditions (transient activation by a saturating concentration of GABA) were substantially inhibited by penicillin, currents evoked from extrasynaptic isoforms under tonic conditions (prolonged application by a sub-saturating concentration of GABA) were minimally affected. We therefore concluded that the reported inability of penicillin to modulate tonic currents could not simply be attributed to insensitivity of extrasynaptic receptors, but rather, reflected an inability to modulate these receptors in their native context of activation.

  6. Seizure-induced alterations in fast-spiking basket cell GABA currents modulate frequency and coherence of gamma oscillation in network simulations

    NASA Astrophysics Data System (ADS)

    Proddutur, Archana; Yu, Jiandong; Elgammal, Fatima S.; Santhakumar, Vijayalakshmi

    2013-12-01

    Gamma frequency oscillations have been proposed to contribute to memory formation and retrieval. Fast-spiking basket cells (FS-BCs) are known to underlie development of gamma oscillations. Fast, high amplitude GABA synapses and gap junctions have been suggested to contribute to gamma oscillations in FS-BC networks. Recently, we identified that, apart from GABAergic synapses, FS-BCs in the hippocampal dentate gyrus have GABAergic currents mediated by extrasynaptic receptors. Our experimental studies demonstrated two specific changes in FS-BC GABA currents following experimental seizures [Yu et al., J. Neurophysiol. 109, 1746 (2013)]: increase in the magnitude of extrasynaptic (tonic) GABA currents and a depolarizing shift in GABA reversal potential (EGABA). Here, we use homogeneous networks of a biophysically based model of FS-BCs to examine how the presence of extrasynaptic GABA conductance (gGABA-extra) and experimentally identified, seizure-induced changes in gGABA-extra and EGABA influence network activity. Networks of FS-BCs interconnected by fast GABAergic synapses developed synchronous firing in the dentate gamma frequency range (40-100 Hz). Systematic investigation revealed that the biologically realistic range of 30 to 40 connections between FS-BCs resulted in greater coherence in the gamma frequency range when networks were activated by Poisson-distributed dendritic synaptic inputs rather than by homogeneous somatic current injections, which were balanced for FS-BC firing frequency in unconnected networks. Distance-dependent conduction delay enhanced coherence in networks with 30-40 FS-BC interconnections while inclusion of gap junctional conductance had a modest effect on coherence. In networks activated by somatic current injections resulting in heterogeneous FS-BC firing, increasing gGABA-extra reduced the frequency and coherence of FS-BC firing when EGABA was shunting (-74 mV), but failed to alter average FS-BC frequency when EGABA was depolarizing

  7. The Relevance of AgRP Neuron-Derived GABA Inputs to POMC Neurons Differs for Spontaneous and Evoked Release

    PubMed Central

    2017-01-01

    Hypothalamic agouti-related peptide (AgRP) neurons potently stimulate food intake, whereas proopiomelanocortin (POMC) neurons inhibit feeding. Whether AgRP neurons exert their orexigenic actions, at least in part, by inhibiting anorexigenic POMC neurons remains unclear. Here, the connectivity between GABA-releasing AgRP neurons and POMC neurons was examined in brain slices from male and female mice. GABA-mediated spontaneous IPSCs (sIPSCs) in POMC neurons were unaffected by disturbing GABA release from AgRP neurons either by cell type-specific deletion of the vesicular GABA transporter or by expression of botulinum toxin in AgRP neurons to prevent vesicle-associated membrane protein 2-dependent vesicle fusion. Additionally, there was no difference in the ability of μ-opioid receptor (MOR) agonists to inhibit sIPSCs in POMC neurons when MORs were deleted from AgRP neurons, and activation of the inhibitory designer receptor hM4Di on AgRP neurons did not affect sIPSCs recorded from POMC neurons. These approaches collectively indicate that AgRP neurons do not significantly contribute to the strong spontaneous GABA input to POMC neurons. Despite these observations, optogenetic stimulation of AgRP neurons reliably produced evoked IPSCs in POMC neurons, leading to the inhibition of POMC neuron firing. Thus, AgRP neurons can potently affect POMC neuron function without contributing a significant source of spontaneous GABA input to POMC neurons. Together, these results indicate that the relevance of GABAergic inputs from AgRP to POMC neurons is state dependent and highlight the need to consider different types of transmitter release in circuit mapping and physiologic regulation. SIGNIFICANCE STATEMENT Agouti-related peptide (AgRP) neurons play an important role in driving food intake, while proopiomelanocortin (POMC) neurons inhibit feeding. Despite the importance of these two well characterized neuron types in maintaining metabolic homeostasis, communication between these

  8. The Relevance of AgRP Neuron-Derived GABA Inputs to POMC Neurons Differs for Spontaneous and Evoked Release.

    PubMed

    Rau, Andrew R; Hentges, Shane T

    2017-08-02

    Hypothalamic agouti-related peptide (AgRP) neurons potently stimulate food intake, whereas proopiomelanocortin (POMC) neurons inhibit feeding. Whether AgRP neurons exert their orexigenic actions, at least in part, by inhibiting anorexigenic POMC neurons remains unclear. Here, the connectivity between GABA-releasing AgRP neurons and POMC neurons was examined in brain slices from male and female mice. GABA-mediated spontaneous IPSCs (sIPSCs) in POMC neurons were unaffected by disturbing GABA release from AgRP neurons either by cell type-specific deletion of the vesicular GABA transporter or by expression of botulinum toxin in AgRP neurons to prevent vesicle-associated membrane protein 2-dependent vesicle fusion. Additionally, there was no difference in the ability of μ-opioid receptor (MOR) agonists to inhibit sIPSCs in POMC neurons when MORs were deleted from AgRP neurons, and activation of the inhibitory designer receptor hM4Di on AgRP neurons did not affect sIPSCs recorded from POMC neurons. These approaches collectively indicate that AgRP neurons do not significantly contribute to the strong spontaneous GABA input to POMC neurons. Despite these observations, optogenetic stimulation of AgRP neurons reliably produced evoked IPSCs in POMC neurons, leading to the inhibition of POMC neuron firing. Thus, AgRP neurons can potently affect POMC neuron function without contributing a significant source of spontaneous GABA input to POMC neurons. Together, these results indicate that the relevance of GABAergic inputs from AgRP to POMC neurons is state dependent and highlight the need to consider different types of transmitter release in circuit mapping and physiologic regulation. SIGNIFICANCE STATEMENT Agouti-related peptide (AgRP) neurons play an important role in driving food intake, while proopiomelanocortin (POMC) neurons inhibit feeding. Despite the importance of these two well characterized neuron types in maintaining metabolic homeostasis, communication between these

  9. γ-Aminobutyric acid transaminase deficiency impairs central carbon metabolism and leads to cell wall defects during salt stress in Arabidopsis roots.

    PubMed

    Renault, Hugues; El Amrani, Abdelhak; Berger, Adeline; Mouille, Grégory; Soubigou-Taconnat, Ludivine; Bouchereau, Alain; Deleu, Carole

    2013-05-01

    Environmental constraints challenge cell homeostasis and thus require a tight regulation of metabolic activity. We have previously reported that the γ-aminobutyric acid (GABA) metabolism is crucial for Arabidopsis salt tolerance as revealed by the NaCl hypersensitivity of the GABA transaminase (GABA-T, At3g22200) gaba-t/pop2-1 mutant. In this study, we demonstrate that GABA-T deficiency during salt stress causes root and hypocotyl developmental defects and alterations of cell wall composition. A comparative genome-wide transcriptional analysis revealed that expression levels of genes involved in carbon metabolism, particularly sucrose and starch catabolism, were found to increase upon the loss of GABA-T function under salt stress conditions. Consistent with the altered mutant cell wall composition, a number of cell wall-related genes were also found differentially expressed. A targeted quantitative analysis of primary metabolites revealed that glutamate (GABA precursor) accumulated while succinate (the final product of GABA metabolism) significantly decreased in mutant roots after 1 d of NaCl treatment. Furthermore, sugar concentration was twofold reduced in gaba-t/pop2-1 mutant roots compared with wild type. Together, our results provide strong evidence that GABA metabolism is a major route for succinate production in roots and identify GABA as a major player of central carbon adjustment during salt stress. © 2012 Blackwell Publishing Ltd.

  10. The effects of elevated endogenous GABA levels on movement-related network oscillations.

    PubMed

    Muthukumaraswamy, S D; Myers, J F M; Wilson, S J; Nutt, D J; Lingford-Hughes, A; Singh, K D; Hamandi, K

    2013-02-01

    The EEG/MEG signal is generated primarily by the summation of the post-synaptic potentials of cortical principal cells. At a microcircuit level, these glutamatergic principal cells are reciprocally connected to GABAergic interneurons and cortical oscillations are thought to be dependent on the balance of excitation and inhibition between these cell types. To investigate the dependence of movement-related cortical oscillations on excitation-inhibition balance, we pharmacologically manipulated the GABA system using tiagabine, which blocks GABA Transporter 1(GAT-1), the GABA uptake transporter and increases endogenous GABA activity. In a blinded, placebo-controlled, crossover design, in 15 healthy participants we administered either 15mg of tiagabine or a placebo. We recorded whole-head magnetoencephalograms, while the participants performed a movement task, prior to, one hour post, three hour post and five hour post tiagabine ingestion. Using time-frequency analysis of beamformer source reconstructions, we quantified the baseline level of beta activity (15-30Hz), the post-movement beta rebound (PMBR), beta event-related desynchronisation (beta-ERD) and movement-related gamma synchronisation (MRGS) (60-90Hz). Our results demonstrated that tiagabine, and hence elevated endogenous GABA levels causes, an elevation of baseline beta power, enhanced beta-ERD and reduced PMBR, but no modulation of MRGS. Comparing our results to recent literature (Hall et al., 2011) we suggest that beta-ERD may be a GABAA receptor mediated process while PMBR may be GABAB receptor mediated. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Expression of gamma-aminobutyric acid rho 1 and rho 1 Delta 450 as gene fusions with the green fluorescent protein.

    PubMed

    Martinez-Torres, A; Miledi, R

    2001-02-13

    The functional characteristics and cellular localization of the gamma aminobutyric acid (GABA) rho 1 receptor and its nonfunctional isoform rho 1 Delta 450 were investigated by expressing them as gene fusions with the enhanced version of the green fluorescent protein (GFP). Oocytes injected with rho 1-GFP had receptors that gated chloride channels when activated by GABA. The functional characteristics of these receptors were the same as for those of wild-type rho 1 receptors. Fluorescence, because of the chimeric receptors expressed, was over the whole oocyte but was more intense near the cell surface and more abundant in the animal hemisphere. Similar to the wild type, rho 1 Delta 450-GFP did not lead to the expression of functional GABA receptors, and injected oocytes failed to generate currents even after exposure to high concentrations of GABA. Nonetheless, the fluorescence displayed by oocytes expressing rho 1 Delta 450-GFP was distributed similarly to that of rho 1-GFP. Mammalian cells transfected with the rho 1-GFP or rho 1 Delta 450-GFP constructs showed mostly intracellularly distributed fluorescence in confocal microscope images. A sparse localization of fluorescence was observed in the plasma membrane regardless of the cell line used. We conclude that rho 1 Delta 450 is expressed and transported close to, and perhaps incorporated into, the plasma membrane. Thus, rho 1- and rho 1 Delta 450-GFP fusions provide a powerful tool to visualize the traffic of GABA type C receptors.

  12. Expression of γ-aminobutyric acid ρ1 and ρ1Δ450 as gene fusions with the green fluorescent protein

    PubMed Central

    Martínez-Torres, Ataúlfo; Miledi, Ricardo

    2001-01-01

    The functional characteristics and cellular localization of the γaminobutyric acid (GABA) ρ1 receptor and its nonfunctional isoform ρ1Δ450 were investigated by expressing them as gene fusions with the enhanced version of the green fluorescent protein (GFP). Oocytes injected with ρ1-GFP had receptors that gated chloride channels when activated by GABA. The functional characteristics of these receptors were the same as for those of wild-type ρ1 receptors. Fluorescence, because of the chimeric receptors expressed, was over the whole oocyte but was more intense near the cell surface and more abundant in the animal hemisphere. Similar to the wild type, ρ1Δ450-GFP did not lead to the expression of functional GABA receptors, and injected oocytes failed to generate currents even after exposure to high concentrations of GABA. Nonetheless, the fluorescence displayed by oocytes expressing ρ1Δ450-GFP was distributed similarly to that of ρ1-GFP. Mammalian cells transfected with the ρ1-GFP or ρ1Δ450-GFP constructs showed mostly intracellularly distributed fluorescence in confocal microscope images. A sparse localization of fluorescence was observed in the plasma membrane regardless of the cell line used. We conclude that ρ1Δ450 is expressed and transported close to, and perhaps incorporated into, the plasma membrane. Thus, ρ1- and ρ1Δ450-GFP fusions provide a powerful tool to visualize the traffic of GABA type C receptors. PMID:11172056

  13. mRNA and Protein Levels for GABA[subscript A][alpha]4, [alpha]5, [beta]1 and GABA[subscript B]R1 Receptors are Altered in Brains from Subjects with Autism

    ERIC Educational Resources Information Center

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Rooney, Robert J.; Patel, Diven H.; Thuras, Paul D.

    2010-01-01

    We have shown altered expression of gamma-aminobutyric acid A (GABA[subscript A]) and gamma-aminobutyric acid B (GABA[subscript B]) receptors in the brains of subjects with autism. In the current study, we sought to verify our western blotting data for GABBR1 via qRT-PCR and to expand our previous work to measure mRNA and protein levels of 3…

  14. [Local GABA-ergic modulation of serotonergic neuron activity in the nucleus raphe magnus].

    PubMed

    Iniushkin, A N; Merkulova, N A; Orlova, A O; Iniushkina, E M

    2009-07-01

    In voltage-clamp experimental on slices of the rat brainstem the effects of 5-HT and GABA on serotonergic neurons of nucleus raphe magnus were investigated. Local applications of 5-HT induced an increase in IPCSs frequency and amplitude in 45% of serotonergic cells. The effect suppressed by the blocker of fast sodium channels tetradotoxin. Antagonist of GABA receptor gabazine blocked IPSCs in neurons both sensitive and non-sensitive to 5-HT action. Applications of GABA induced a membrane current (I(GABA)), which was completely blocked by gabazine. The data suggest self-control of the activity of serotonergic neurons in nucleus raphe magnus by negative feedback loop via local GABAergic interneurons.

  15. Population patch-clamp electrophysiology analysis of recombinant GABAA alpha1beta3gamma2 channels expressed in HEK-293 cells.

    PubMed

    Hollands, Emma C; Dale, Tim J; Baxter, Andrew W; Meadows, Helen J; Powell, Andrew J; Clare, Jeff J; Trezise, Derek J

    2009-08-01

    Gamma-amino butyric acid (GABA)-activated Cl- channels are critical mediators of inhibitory postsynaptic potentials in the CNS. To date, rational design efforts to identify potent and selective GABA(A) subtype ligands have been hampered by the absence of suitable high-throughput screening approaches. The authors describe 384-well population patch-clamp (PPC) planar array electrophysiology methods for the study of GABA(A) receptor pharmacology. In HEK293 cells stably expressing human alpha1beta3gamma2 GABA(A) channels, GABA evoked outward currents at 0 mV of 1.05 +/- 0.08 nA, measured 8 s post GABA addition. The I(GABA) was linear and reversed close to the theoretical E(Cl) (-56 mV). Concentration-response curve analysis yielded a mean pEC(50) value of 5.4 and Hill slope of 1.5, and for a series of agonists, the rank order of potency was muscimol > GABA > isoguvacine. A range of known positive modulators, including diazepam and pentobarbital, produced concentration-dependent augmentation of the GABA EC( 20) response (1 microM). The competitive antagonists bicuculline and gabazine produced concentration-dependent, parallel, rightward displacement of GABA curves with pA(2) and slope values of 5.7 and 1.0 and 6.7 and 1.0, respectively. In contrast, picrotoxin (0.2-150 microM) depressed the maximal GABA response, implying a non-competitive antagonism. Overall, the pharmacology of human alpha1beta3gamma2 GABA(A) determined by PPC was highly similar to that obtained by conventional patch-clamp methods. In small-scale single-shot screens, Z' values of >0.5 were obtained in agonist, modulator, and antagonist formats with hit rates of 0% to 3%. The authors conclude that despite the inability of the method to resolve the peak agonist responses, PPC can rapidly and usefully quantify pharmacology for the alpha1beta3gamma2 GABA(A) isoform. These data suggest that PPC may be a valuable approach for a focused set and secondary screening of GABA(A) receptors and other slow ligand

  16. Glucose, Lactate, β-Hydroxybutyrate, Acetate, GABA, and Succinate as Substrates for Synthesis of Glutamate and GABA in the Glutamine-Glutamate/GABA Cycle.

    PubMed

    Hertz, Leif; Rothman, Douglas L

    2016-01-01

    The glutamine-glutamate/GABA cycle is an astrocytic-neuronal pathway transferring precursors for transmitter glutamate and GABA from astrocytes to neurons. In addition, the cycle carries released transmitter back to astrocytes, where a minor fraction (~25 %) is degraded (requiring a similar amount of resynthesis) and the remainder returned to the neurons for reuse. The flux in the cycle is intense, amounting to the same value as neuronal glucose utilization rate or 75-80 % of total cortical glucose consumption. This glucose:glutamate ratio is reduced when high amounts of β-hydroxybutyrate are present, but β-hydroxybutyrate can at most replace 60 % of glucose during awake brain function. The cycle is initiated by α-ketoglutarate production in astrocytes and its conversion via glutamate to glutamine which is released. A crucial reaction in the cycle is metabolism of glutamine after its accumulation in neurons. In glutamatergic neurons all generated glutamate enters the mitochondria and its exit to the cytosol occurs in a process resembling the malate-aspartate shuttle and therefore requiring concomitant pyruvate metabolism. In GABAergic neurons one half enters the mitochondria, whereas the other one half is released directly from the cytosol. A revised concept is proposed for the synthesis and metabolism of vesicular and nonvesicular GABA. It includes the well-established neuronal GABA reuptake, its metabolism, and use for resynthesis of vesicular GABA. In contrast, mitochondrial glutamate is by transamination to α-ketoglutarate and subsequent retransamination to releasable glutamate essential for the transaminations occurring during metabolism of accumulated GABA and subsequent resynthesis of vesicular GABA.

  17. Impact of exogenous GABA treatments on endogenous GABA metabolism in anthurium cut flowers in response to postharvest chilling temperature.

    PubMed

    Aghdam, Morteza Soleimani; Naderi, Roohangiz; Jannatizadeh, Abbasali; Babalar, Mesbah; Sarcheshmeh, Mohammad Ali Askari; Faradonbe, Mojtaba Zamani

    2016-09-01

    Anthurium flowers are susceptible to chilling injury, and the optimum storage temperature is 12.5-20 °C. The γ-aminobutyric acid (GABA) shunt pathway may alleviate chilling stress in horticultural commodities by providing energy (ATP), reducing molecules (NADH), and minimizing accumulation of reactive oxygen species (ROS). In this experiment, the impact of a preharvest spray treatment with 1 mM GABA and postharvest treatment of 5 mM GABA stem-end dipping on GABA shunt pathway activity of anthurium cut flowers (cv. Sirion) in response to cold storage (4 °C for 21 days) was investigated. GABA treatments resulted in lower glutamate decarboxylase (GAD) and higher GABA transaminase (GABA-T) activities in flowers during cold storage, which was associated with lower GABA content and coincided with higher ATP content. GABA treatments also enhanced accumulation of endogenous glycine betaine (GB) in flowers during cold storage, as well as higher spathe relative water content (RWC). These findings suggest that GABA treatments may alleviate chilling injury of anthurium cut flowers by enhancing GABA shunt pathway activity leading to provide sufficient ATP and promoting endogenous GB accumulation. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  18. Alteration of Transcripts of Stress-Protective Genes and Transcriptional Factors by γ-Aminobutyric Acid (GABA) Associated with Improved Heat and Drought Tolerance in Creeping Bentgrass (Agrostis stolonifera).

    PubMed

    Li, Zhou; Peng, Yan; Huang, Bingru

    2018-05-31

    Gamma-aminobutyric acid (GABA) may play a positive role in regulating plant tolerance to drought or heat stress. The objectives of this study were to investigate the physiological effects of GABA on tolerance of creeping bentgrass ( Agrostis stolonifera ) to heat and drought stress and to determine whether enhanced heat and drought tolerance due to GABA treatment was associated with the up-regulation of selected genes and transcriptional factors involved in stress protection. Creeping bentgrass (cultivar "Penncross") plants were treated with 0.5 mM GABA or water (untreated control) as a foliar spray and were subsequently exposed to heat stress (35/30 °C, day/night), drought stress by withholding irrigation, or non-stress conditions in controlled-environment growth chambers. Exogenous application of GABA significantly improved plant tolerance to heat and drought stress, as reflected by increased leaf water content, cell membrane stability, and chlorophyll content. The analysis of gene transcript level revealed that exogenous GABA up-regulated the expression of ABF3 , POD , APX , HSP90 , DHN3 , and MT1 during heat stress and the expression of CDPK26 , MAPK1 , ABF3 , WRKY75 , MYB13 , HSP70 , MT1 , 14-3-3 , and genes ( SOD , CAT , POD , APX , MDHAR , DHAR , and GR ) encoding antioxidant enzymes during drought stress. The up-regulation of the aforementioned stress-protective genes and transcriptional factors could contribute to improved heat and drought tolerance in creeping bentgrass.

  19. CB1-Dependent Long-Term Depression in Ventral Tegmental Area GABA Neurons: A Novel Target for Marijuana

    PubMed Central

    Friend, Lindsey; Sandoval, Philip; Nufer, Teresa; Ostlund, Isaac

    2017-01-01

    The VTA is necessary for reward behavior with dopamine cells critically involved in reward signaling. Dopamine cells in turn are innervated and regulated by neighboring inhibitory GABA cells. Using whole-cell electrophysiology in juvenile-adolescent GAD67-GFP male mice, we examined excitatory plasticity in fluorescent VTA GABA cells. A novel CB1-dependent LTD was induced in GABA cells that was dependent on metabotropic glutamate receptor 5, and cannabinoid receptor 1 (CB1). LTD was absent in CB1 knock-out mice but preserved in heterozygous littermates. Bath applied Δ9-tetrahydrocannabinol depressed GABA cell activity, therefore downstream dopamine cells will be disinhibited; and thus, this could potentially result in increased reward. Chronic injections of Δ9-tetrahydrocannabinol occluded LTD compared with vehicle injections; however, a single exposure was insufficient to do so. As synaptic modifications by drugs of abuse are often tied to addiction, these data suggest a possible mechanism for the addictive effects of Δ9-tetrahydrocannabinol in juvenile-adolescents, by potentially altering reward behavioral outcomes. SIGNIFICANCE STATEMENT The present study identifies a novel form of glutamatergic synaptic plasticity in VTA GABA neurons, a currently understudied cell type that is critical for the brain's reward circuit, and how Δ9-tetrahydrocannabinol occludes this plasticity. This study specifically addresses a potential unifying mechanism whereby marijuana could exert rewarding and addictive/withdrawal effects. Marijuana use and legalization are a pressing issue for many states in the United States. Although marijuana is the most commonly abused illicit drug, the implications of legalized, widespread, or continued usage are speculative. This study in juvenile-adolescent aged mice identifies a novel form of synaptic plasticity in VTA GABA cells, and the synaptic remodeling that can occur after Δ9-tetrahydrocannabinol use. PMID:29038246

  20. CB1-Dependent Long-Term Depression in Ventral Tegmental Area GABA Neurons: A Novel Target for Marijuana.

    PubMed

    Friend, Lindsey; Weed, Jared; Sandoval, Philip; Nufer, Teresa; Ostlund, Isaac; Edwards, Jeffrey G

    2017-11-08

    The VTA is necessary for reward behavior with dopamine cells critically involved in reward signaling. Dopamine cells in turn are innervated and regulated by neighboring inhibitory GABA cells. Using whole-cell electrophysiology in juvenile-adolescent GAD67-GFP male mice, we examined excitatory plasticity in fluorescent VTA GABA cells. A novel CB1-dependent LTD was induced in GABA cells that was dependent on metabotropic glutamate receptor 5, and cannabinoid receptor 1 (CB1). LTD was absent in CB1 knock-out mice but preserved in heterozygous littermates. Bath applied Δ 9 -tetrahydrocannabinol depressed GABA cell activity, therefore downstream dopamine cells will be disinhibited; and thus, this could potentially result in increased reward. Chronic injections of Δ 9 -tetrahydrocannabinol occluded LTD compared with vehicle injections; however, a single exposure was insufficient to do so. As synaptic modifications by drugs of abuse are often tied to addiction, these data suggest a possible mechanism for the addictive effects of Δ 9 -tetrahydrocannabinol in juvenile-adolescents, by potentially altering reward behavioral outcomes. SIGNIFICANCE STATEMENT The present study identifies a novel form of glutamatergic synaptic plasticity in VTA GABA neurons, a currently understudied cell type that is critical for the brain's reward circuit, and how Δ 9 -tetrahydrocannabinol occludes this plasticity. This study specifically addresses a potential unifying mechanism whereby marijuana could exert rewarding and addictive/withdrawal effects. Marijuana use and legalization are a pressing issue for many states in the United States. Although marijuana is the most commonly abused illicit drug, the implications of legalized, widespread, or continued usage are speculative. This study in juvenile-adolescent aged mice identifies a novel form of synaptic plasticity in VTA GABA cells, and the synaptic remodeling that can occur after Δ 9 -tetrahydrocannabinol use. Copyright © 2017 the

  1. Salmon lice (Lepeophtheirus salmonis) showing varying emamectin benzoate susceptibilities differ in neuronal acetylcholine receptor and GABA-gated chloride channel mRNA expression

    PubMed Central

    2013-01-01

    Background Caligid copepods, also called sea lice, are fish ectoparasites, some species of which cause significant problems in the mariculture of salmon, where the annual cost of infection is in excess of €300 million globally. At present, caligid control on farms is mainly achieved using medicinal treatments. However, the continued use of a restricted number of medicine actives potentially favours the development of drug resistance. Here, we report transcriptional changes in a laboratory strain of the caligid Lepeophtheirus salmonis (Krøyer, 1837) that is moderately (~7-fold) resistant to the avermectin compound emamectin benzoate (EMB), a component of the anti-salmon louse agent SLICE® (Merck Animal Health). Results Suppression subtractive hybridisation (SSH) was used to enrich transcripts differentially expressed between EMB-resistant (PT) and drug-susceptible (S) laboratory strains of L. salmonis. SSH libraries were subjected to 454 sequencing. Further L. salmonis transcript sequences were available as expressed sequence tags (EST) from GenBank. Contiguous sequences were generated from both SSH and EST sequences and annotated. Transcriptional responses in PT and S salmon lice were investigated using custom 15 K oligonucleotide microarrays designed using the above sequence resources. In the absence of EMB exposure, 359 targets differed in transcript abundance between the two strains, these genes being enriched for functions such as calcium ion binding, chitin metabolism and muscle structure. γ-aminobutyric acid (GABA)-gated chloride channel (GABA-Cl) and neuronal acetylcholine receptor (nAChR) subunits showed significantly lower transcript levels in PT lice compared to S lice. Using RT-qPCR, the decrease in mRNA levels was estimated at ~1.4-fold for GABA-Cl and ~2.8-fold for nAChR. Salmon lice from the PT strain showed few transcriptional responses following acute exposure (1 or 3 h) to 200 μg L-1 of EMB, a drug concentration tolerated by PT lice, but

  2. The effects of agonists of ionotropic GABA(A) and metabotropic GABA(B) receptors on learning.

    PubMed

    Zyablitseva, Evgeniya A; Kositsyn, Nikolay S; Shul'gina, Galina I

    2009-05-01

    The research described here investigates the role played by inhibitory processes in the discriminations made by the nervous system of humans and animals between familiar and unfamiliar and significant and nonsignificant events. This research compared the effects of two inhibitory mediators of gamma-aminobutyric acid (GABA): 1) phenibut, a nonselective agonist of ionotropic GABA(A) and metabotropic GABA(B) receptors and 2) gaboxadol a selective agonist of ionotropic GABA(A) receptors on the process of developing active defensive and inhibitory conditioned reflexes in alert non-immobilized rabbits. It was found that phenibut, but not gaboxadol, accelerates the development of defensive reflexes at an early stage of conditioning. Both phenibut and gaboxadol facilitate the development of conditioned inhibition, but the effect of gaboxadol occurs at later stages of conditioning and is less stable than that of phenibut. The earlier and more stable effects of phenibut, as compared to gaboxadol, on storage in memory of the inhibitory significance of a stimulus may occur because GABA(B) receptors play the dominant role in the development of internal inhibition during an early stage of conditioning. On the other hand this may occur because the participation of both GABA(A) and GABA(B) receptors are essential to the process. We discuss the polyfunctionality of GABA receptors as a function of their structure and the positions of the relevant neurons in the brain as this factor can affect regulation of various types of psychological processes.

  3. Prenatal Ontogeny as a Susceptibility Period for Cortical GABA Neuron Disturbances in Schizophrenia

    PubMed Central

    Volk, David W.; Lewis, David A.

    2013-01-01

    Cognitive deficits in schizophrenia have been linked to disturbances in GABA neurons in the prefrontal cortex. Furthermore, cognitive deficits in schizophrenia appear well before the onset of psychosis and have been reported to be present during early childhood and even during the first year of life. Taken together, these data raise the following question: Does the disease process that produces abnormalities in prefrontal GABA neurons in schizophrenia begin prenatally and disrupt the ontogeny of cortical GABA neurons? Here, we address this question through a consideration of evidence that genetic and/or environmental insults that occur during gestation initiate a pathogenetic process that alters cortical GABA neuron ontogeny and produces the pattern of GABA neuron abnormalities, and consequently cognitive difficulties, seen in schizophrenia. First, we review available evidence from postmortem human brain tissue studies characterizing alterations in certain subpopulations of prefrontal GABA neuron that provide clues to a prenatal origin in schizophrenia. Second, we review recent discoveries of transcription factors, cytokine receptors, and other developmental regulators that govern the birth, migration, specification, maturation, and survival of different subpopulations of prefrontal GABA neurons. Third, we discuss recent studies demonstrating altered expression of these ontogenetic factors in the prefrontal cortex in schizophrenia. Fourth, we discuss the potential role of disturbances in the maternal-fetal environment such as maternal immune activation in the development of GABA neuron dysfunction. Finally, we propose critical questions that need to be answered in future research to further investigate the role of altered GABA neuron ontogeny in the pathogenesis of schizophrenia. PMID:23769891

  4. Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve

    PubMed Central

    Bravo, Javier A.; Forsythe, Paul; Chew, Marianne V.; Escaravage, Emily; Savignac, Hélène M.; Dinan, Timothy G.; Bienenstock, John; Cryan, John F.

    2011-01-01

    There is increasing, but largely indirect, evidence pointing to an effect of commensal gut microbiota on the central nervous system (CNS). However, it is unknown whether lactic acid bacteria such as Lactobacillus rhamnosus could have a direct effect on neurotransmitter receptors in the CNS in normal, healthy animals. GABA is the main CNS inhibitory neurotransmitter and is significantly involved in regulating many physiological and psychological processes. Alterations in central GABA receptor expression are implicated in the pathogenesis of anxiety and depression, which are highly comorbid with functional bowel disorders. In this work, we show that chronic treatment with L. rhamnosus (JB-1) induced region-dependent alterations in GABAB1b mRNA in the brain with increases in cortical regions (cingulate and prelimbic) and concomitant reductions in expression in the hippocampus, amygdala, and locus coeruleus, in comparison with control-fed mice. In addition, L. rhamnosus (JB-1) reduced GABAAα2 mRNA expression in the prefrontal cortex and amygdala, but increased GABAAα2 in the hippocampus. Importantly, L. rhamnosus (JB-1) reduced stress-induced corticosterone and anxiety- and depression-related behavior. Moreover, the neurochemical and behavioral effects were not found in vagotomized mice, identifying the vagus as a major modulatory constitutive communication pathway between the bacteria exposed to the gut and the brain. Together, these findings highlight the important role of bacteria in the bidirectional communication of the gut–brain axis and suggest that certain organisms may prove to be useful therapeutic adjuncts in stress-related disorders such as anxiety and depression. PMID:21876150

  5. Nicotine induces self-renewal of pancreatic cancer stem cells via neurotransmitter-driven activation of sonic hedgehog signalling.

    PubMed

    Al-Wadei, Mohammed H; Banerjee, Jheelam; Al-Wadei, Hussein A N; Schuller, Hildegard M

    2016-01-01

    A small subpopulation of pancreatic cancer cells with characteristics of stem cells drive tumour initiation, progression and metastasis. A better understanding of the regulation of cancer stem cells may lead to more effective cancer prevention and therapy. We have shown that the proliferation and migration of pancreatic cancer cell lines is activated by the nicotinic receptor-mediated release of stress neurotransmitters, responses reversed by γ-aminobutyric acid (GABA). However, the observed cancer inhibiting effects of GABA will only succeed clinically if GABA inhibits pancreatic cancer stem cells (PCSCs) in addition to the more differentiated cancer cells that comprise the majority of cancer tissues and cell lines. Using PCSCs isolated from two pancreatic cancer patients by cell sorting and by spheroid formation assay from pancreatic cancer cell line Panc-1, we tested the hypothesis that nicotine induces the self-renewal of PCSCs. Nicotinic acetylcholine receptors (nAChRs) α3, α4, α5 and α7 were expressed and chronic exposure to nicotine increased the protein expression of these receptors. Immunoassays showed that PCSCs produced the stress neurotransmitters epinephrine and norepinephrine and the inhibitory neurotransmitter GABA. Chronic nicotine significantly increased the production of stress neurotransmitters and sonic hedgehog (SHH) while inducing Gli1 protein and decreasing GABA. GABA treatment inhibited the induction of SHH and Gli1. Spheroid formation and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide assays showed significant nicotine-induced increases in self renewal and cell proliferation, responses blocked by GABA. Our data suggest that nicotine increases the SHH-mediated malignant potential of PCSCs and that GABA prevents these effects. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. GABA Immunoreactivity in Auditory and Song Control Brain Areas of Zebra Finches

    PubMed Central

    Pinaud, Raphael; Mello, Claudio V.

    2009-01-01

    Inhibitory transmission is critical to sensory and motor processing and is believed to play a role in experience-dependent plasticity. The main inhibitory neurotransmitter in vertebrates, GABA, has been implicated in both sensory and motor aspects of vocalization in songbirds. To understand the role of GABAergic mechanisms in vocal communication, GABAergic elements must be characterized fully. Hence, we investigated GABA immunohistochemistry in the zebra finch brain, emphasizing auditory areas and song control nuclei. Several nuclei of the ascending auditory pathway showed a moderate to high density of GABAergic neurons including the cochlear nuclei, nucleus laminaris, superior olivary nucleus, mesencephalic nucleus lateralis pars dorsalis, and nucleus ovoidalis. Telencephalic auditory areas, including field L subfields L1, L2a and L3, as well as the caudomedial nidopallium (NCM) and mesopallium (CMM), contained GABAergic cells at particularly high densities. Considerable GABA labeling was also seen in the shelf area of caudodorsal nidopallium, and the cup area in the arcopallium, as well as in area X, the lateral magnocellular nucleus of the anterior nidopallium, the robust nucleus of the arcopallium and nidopallial nucleus HVC. GABAergic cells were typically small, most likely local inhibitory interneurons, although large GABA-positive cells that were sparsely distributed were also identified. GABA-positive neurites and puncta were identified in most nuclei of the ascending auditory pathway and in song control nuclei. Our data are in accordance with a prominent role of GABAergic mechanisms in regulating the neural circuits involved in song perceptual processing, motor production, and vocal learning in songbirds. PMID:17466487

  7. GABA-A Receptors Mediate Tonic Inhibition and Neurosteroid Sensitivity in the Brain.

    PubMed

    Reddy, Doodipala Samba

    2018-01-01

    Neurosteroids like allopregnanolone (AP) are positive allosteric modulators of synaptic and extrasynaptic GABA-A receptors. AP and related neurosteroids exhibit a greater potency for δ-containing extrasynaptic receptors. The δGABA-A receptors, which are expressed extrasynaptically in the dentate gyrus and other regions, contribute to tonic inhibition, promoting network shunting as well as reducing seizure susceptibility. Levels of endogenous neurosteroids fluctuate with ovarian cycle. Natural and synthetic neurosteroids maximally potentiate tonic inhibition in the hippocampus and provide robust protection against a variety of limbic seizures and status epilepticus. Recently, a consensus neurosteroid pharmacophore model has been proposed at extrasynaptic δGABA-A receptors based on structure-activity relationship for functional activation of tonic currents and seizure protection. Aside from anticonvulsant actions, neurosteroids have been found to be powerful anxiolytic and anesthetic agents. Neurosteroids and Zn 2+ have preferential affinity for δ-containing receptors. Thus, Zn 2+ can prevent neurosteroid activation of extrasynaptic δGABA-A receptor-mediated tonic inhibition. Recently, we demonstrated that Zn 2+ selectively inhibits extrasynaptic δGABA-A receptors and thereby fully prevents AP activation of tonic inhibition and seizure protection. We confirmed that neurosteroids exhibit greater sensitivity at extrasynaptic δGABA-A receptors. Overall, extrasynaptic GABA-A receptors are primary mediators of tonic inhibition in the brain and play a key role in the pathophysiology of epilepsy and other neurological disorders. © 2018 Elsevier Inc. All rights reserved.

  8. Stimulation of GABA-Induced Ca2+ Influx Enhances Maturation of Human Induced Pluripotent Stem Cell-Derived Neurons

    PubMed Central

    Rushton, David J.; Mattis, Virginia B.; Svendsen, Clive N.; Allen, Nicholas D.; Kemp, Paul J.

    2013-01-01

    Optimal use of patient-derived, induced pluripotent stem cells for modeling neuronal diseases is crucially dependent upon the proper physiological maturation of derived neurons. As a strategy to develop defined differentiation protocols that optimize electrophysiological function, we investigated the role of Ca2+ channel regulation by astrocyte conditioned medium in neuronal maturation, using whole-cell patch clamp and Ca2+ imaging. Standard control medium supported basic differentiation of induced pluripotent stem cell-derived neurons, as assayed by the ability to fire simple, single, induced action potentials. In contrast, treatment with astrocyte conditioned medium elicited complex and spontaneous neuronal activity, often with rhythmic and biphasic characteristics. Such augmented spontaneous activity correlated with astrocyte conditioned medium-evoked hyperpolarization and was dependent upon regulated function of L-, N- and R-type Ca2+ channels. The requirement for astrocyte conditioned medium could be substituted by simply supplementing control differentiation medium with high Ca2+ or γ-amino butyric acid (GABA). Importantly, even in the absence of GABA signalling, opening Ca2+ channels directly using Bay K8644 was able to hyperpolarise neurons and enhance excitability, producing fully functional neurons. These data provide mechanistic insight into how secreted astrocyte factors control differentiation and, importantly, suggest that pharmacological modulation of Ca2+ channel function leads to the development of a defined protocol for improved maturation of induced pluripotent stem cell-derived neurons. PMID:24278369

  9. Laser photolysis of DPNI-GABA, a tool for investigating the properties and distribution of GABA receptors and for silencing neurons in situ.

    PubMed

    Trigo, Federico F; Papageorgiou, George; Corrie, John E T; Ogden, David

    2009-07-30

    Laser photolysis to release GABA at precisely defined times and locations permits investigation of the distribution of functional GABA(A) receptors in neuronal compartments, the activation kinetics and pharmacology of GABA(A) receptors in situ, and the role of individual neurons in neural circuits by selective silencing with low GABA concentrations. We describe the experimental evaluation and applications of a new nitroindoline-caged GABA, DPNI-GABA, modified to minimize the pharmacological interference commonly found with caged GABA reagents, but retaining the advantages of nitroindoline cages. Unlike the 5-methoxycarbonylmethyl-7-nitroindolinyl-GABA tested previously, DPNI-GABA inhibited GABA(A) receptors with much lower affinity, reducing peak GABA-evoked responses with an IC(50) of approximately 0.5 mM. Most importantly, the kinetics of receptor activation, determined as 10-90% rise-times, were comparable to synaptic events and were little affected by DPNI-GABA present at 1mM concentration, permitting photolysis of DPNI-GABA to mimic synaptic activation of GABA(A) receptors. With a laser spot of 1 microm applied to cerebellar molecular layer interneurons, the spatial resolution of uncaging DPNI-GABA in dendrites was estimated as 2 microm laterally and 7.5 microm focally. Finally, at low DPNI-GABA concentration, photorelease restricted to the area of the soma suppressed spiking in single Purkinje neurons or molecular layer interneurons for periods controlled by the flash intensity and duration. DPNI-GABA has properties better adapted for fast kinetic studies with laser photolysis at GABA(A) receptors than previously reported caged GABA reagents, and can be used in experiments where spatial resolution is determined by the dimensions of the laser light spot.

  10. A human anti-neuronal autoantibody against GABA B receptor induces experimental autoimmune agrypnia.

    PubMed

    Frisullo, Giovanni; Della Marca, Giacomo; Mirabella, Massimiliano; Caggiula, Marcella; Broccolini, Aldobrando; Rubino, Marco; Mennuni, Gioacchino; Tonali, Pietro Attilio; Batocchi, Anna Paola

    2007-04-01

    In the serum and cerebrospinal fluid of a patient with recurrent acute episodes of respiratory crises, autonomic symptoms and total insomnia (agrypnia), we identified a novel anti-neural complement fixing antibody directed against GABA(B) receptor (GABA(B)R). Patient purified IgG recognized a band of approximately 110 kDa on protein extracts of mouse cerebellum, cortex and brainstem and immunolabelled cultured Chinese hamster ovary (CHO) cells, transfected with human GABA(B)R1 and rat GABA(B)R2 receptors. Western blot analysis of transfected CHO homogenates showed the same band using both patient purified IgG and anti-GABA(B)R1 antibody. In order to verify the pathogenic role of these purified antibodies, we injected patient IgG intrathecally into cisterna magna of C57BL/6 mice pre-implanted with EEG electrodes and we observed severe ataxia followed by breathing depression and total suppression of slow wave sleep, as evidenced by EEG recording, in a dose-dependent manner. Immunohistochemistry on brain sections of mice injected with patient IgG showed the simultaneous presence of bound human IgG and C5b-9 deposits on Purkinje cells and cerebellar granular layer. After incubation with anti-GABA(B)R antibody, a marked reduction of receptor immunostaining was found with relative sparing of neuronal architecture. In conclusion we recognized an anti-neuronal autoantibody directed against GABA(B)R that is associated with autoimmune agrypnia and we showed that our patient purified IgG was able to induce in mice experimental autoimmune agrypnia characterized by a complex neurological syndrome affecting several CNS functions.

  11. The main source of ambient GABA responsible for tonic inhibition in the mouse hippocampus.

    PubMed

    Glykys, Joseph; Mody, Istvan

    2007-08-01

    The extracellular space of the brain contains gamma-aminobutyric acid (GABA) that activates extrasynaptic GABA(A) receptors mediating tonic inhibition. The source of this GABA is uncertain: it could be overspill of vesicular release, non-vesicular leakage, reverse transport, dying cells or glia. Using a novel approach, we simultaneously measured phasic and tonic inhibitory currents and assessed their correlation. Enhancing or diminishing vesicular GABA release in hippocampal neurons caused highly correlated changes in the two inhibitions. During high-frequency phasic inhibitory bursts, tonic current was also enhanced as shown by simulating the summation of IPSCs and by recordings in knockout mice devoid of tonic inhibitory current. When vesicular release was reduced by blocking action potentials or the vesicular GABA transporter, phasic and tonic currents decreased in a correlated fashion. Our results are consistent with most of hippocampal tonic inhibitory current being mediated by GABA released from the very vesicles responsible for activating phasic inhibition.

  12. Homeostatic scaling of vesicular glutamate and GABA transporter expression in rat neocortical circuits.

    PubMed

    De Gois, Stéphanie; Schäfer, Martin K-H; Defamie, Norah; Chen, Chu; Ricci, Anthony; Weihe, Eberhard; Varoqui, Hélène; Erickson, Jeffrey D

    2005-08-03

    Homeostatic control of pyramidal neuron firing rate involves a functional balance of feedforward excitation and feedback inhibition in neocortical circuits. Here, we reveal a dynamic scaling in vesicular excitatory (vesicular glutamate transporters VGLUT1 and VGLUT2) and inhibitory (vesicular inhibitory amino acid transporter VIAAT) transporter mRNA and synaptic protein expression in rat neocortical neuronal cultures, using a well established in vitro protocol to induce homeostatic plasticity. During the second and third week of synaptic differentiation, the predominant vesicular transporters expressed in neocortical neurons, VGLUT1 and VIAAT, are both dramatically upregulated. In mature cultures, VGLUT1 and VIAAT exhibit bidirectional and opposite regulation by prolonged activity changes. Endogenous coregulation during development and homeostatic scaling of the expression of the transporters in functionally differentiated cultures may serve to control vesicular glutamate and GABA filling and adjust functional presynaptic excitatory/inhibitory balance. Unexpectedly, hyperexcitation in differentiated cultures triggers a striking increase in VGLUT2 mRNA and synaptic protein, whereas decreased excitation reduces levels. VGLUT2 mRNA and protein are expressed in subsets of VGLUT1-encoded neocortical neurons that we identify in primary cultures and in neocortex in situ and in vivo. After prolonged hyperexcitation, downregulation of VGLUT1/synaptophysin intensity ratios at most synapses is observed, whereas a subset of VGLUT1-containing boutons selectively increase the expression of VGLUT2. Bidirectional and opposite regulation of VGLUT1 and VGLUT2 by activity may serve as positive or negative feedback regulators for cortical synaptic transmission. Intracortical VGLUT1/VGLUT2 coexpressing neurons have the capacity to independently modulate the level of expression of either transporter at discrete synapses and therefore may serve as a plastic interface between subcortical

  13. Is GABA neurotransmission enhanced in auditory thalamus relative to inferior colliculus?

    PubMed Central

    Cai, Rui; Kalappa, Bopanna I.; Brozoski, Thomas J.; Ling, Lynne L.

    2013-01-01

    Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central auditory system. Sensory thalamic structures show high levels of non-desensitizing extrasynaptic GABAA receptors (GABAARs) and a reduction in the redundancy of coded information. The present study compared the inhibitory potency of GABA acting at GABAARs between the inferior colliculus (IC) and the medial geniculate body (MGB) using quantitative in vivo, in vitro, and ex vivo experimental approaches. In vivo single unit studies compared the ability of half maximal inhibitory concentrations of GABA to inhibit sound-evoked temporal responses, and found that GABA was two to three times (P < 0.01) more potent at suppressing MGB single unit responses than IC unit responses. In vitro whole cell patch-clamp slice recordings were used to demonstrate that gaboxadol, a δ-subunit selective GABAAR agonist, was significantly more potent at evoking tonic inhibitory currents from MGB neurons than IC neurons (P < 0.01). These electrophysiological findings were supported by an in vitro receptor binding assay which used the picrotoxin analog [3H]TBOB to assess binding in the GABAAR chloride channel. MGB GABAARs had significantly greater total open chloride channel capacity relative to GABAARs in IC (P < 0.05) as shown by increased total [3H]TBOB binding. Finally, a comparative ex vivo measurement compared endogenous GABA levels and suggested a trend towards higher GABA concentrations in MGB than in IC. Collectively, these studies suggest that, per unit GABA, high affinity extrasynaptic and synaptic GABAARs confer a significant inhibitory GABAAR advantage to MGB neurons relative to IC neurons. This increased GABA sensitivity likely underpins the vital filtering role of auditory thalamus. PMID:24155003

  14. Endogenous GABA and Glutamate Finely Tune the Bursting of Olfactory Bulb External Tufted Cells

    PubMed Central

    Hayar, Abdallah; Ennis, Matthew

    2008-01-01

    In rat olfactory bulb slices, external tufted (ET) cells spontaneously generate spike bursts. Although ET cell bursting is intrinsically generated, its strength and precise timing may be regulated by synaptic input. We tested this hypothesis by analyzing whether the burst properties are modulated by activation of ionotropic γ-aminobutyric acid (GABA) and glutamate receptors. Blocking GABAA receptors increased—whereas blocking ionotropic glutamate receptors decreased—the number of spikes/burst without changing the interburst frequency. The GABAA agonist (isoguvacine, 10 μM) completely inhibited bursting or reduced the number of spikes/burst, suggesting a shunting effect. These findings indicate that the properties of ET cell spontaneous bursting are differentially controlled by GABAergic and glutamatergic fast synaptic transmission. We suggest that ET cell excitatory and inhibitory inputs may be encoded as a change in the pattern of spike bursting in ET cells, which together with mitral/tufted cells constitute the output circuit of the olfactory bulb. PMID:17567771

  15. Increased glutamate/GABA+ ratio in a shared autistic and schizotypal trait phenotype termed Social Disorganisation.

    PubMed

    Ford, Talitha C; Nibbs, Richard; Crewther, David P

    2017-01-01

    Autism and schizophrenia are multi-dimensional spectrum disorders that have substantial phenotypic overlap. This overlap is readily identified in the non-clinical population, and has been conceptualised as Social Disorganisation (SD). This study investigates the balance of excitatory glutamate and inhibitory γ -aminobutyric acid (GABA) concentrations in a non-clinical sample with high and low trait SD, as glutamate and GABA abnormalities are reported across the autism and schizophrenia spectrum disorders. Participants were 18 low (10 females) and 19 high (9 females) SD scorers aged 18 to 40 years who underwent 1 H-MRS for glutamate and GABA+macromolecule (GABA+) concentrations in right and left hemisphere superior temporal (ST) voxels. Reduced GABA+ concentration ( p  = 0.03) and increased glutamate/GABA+ ratio ( p  = 0.003) in the right ST voxel for the high SD group was found, and there was increased GABA+ concentration in the left compared to right ST voxel ( p  = 0.047). Bilateral glutamate concentration was increased for the high SD group ( p  = 0.006); there was no hemisphere by group interaction ( p  = 0.772). Results suggest that a higher expression of the SD phenotype may be associated with increased glutamate/GABA+ ratio in the right ST region, which may affect speech prosody processing, and lead behavioural characteristics that are shared within the autistic and schizotypal spectra.

  16. GABA action in immature neocortical neurons directly depends on the availability of ketone bodies.

    PubMed

    Rheims, Sylvain; Holmgren, Carl D; Chazal, Genevieve; Mulder, Jan; Harkany, Tibor; Zilberter, Tanya; Zilberter, Yuri

    2009-08-01

    In the early postnatal period, energy metabolism in the suckling rodent brain relies to a large extent on metabolic pathways alternate to glucose such as the utilization of ketone bodies (KBs). However, how KBs affect neuronal excitability is not known. Using recordings of single NMDA and GABA-activated channels in neocortical pyramidal cells we studied the effects of KBs on the resting membrane potential (E(m)) and reversal potential of GABA-induced anionic currents (E(GABA)), respectively. We show that during postnatal development (P3-P19) if neocortical brain slices are adequately supplied with KBs, E(m) and E(GABA) are both maintained at negative levels of about -83 and -80 mV, respectively. Conversely, a KB deficiency causes a significant depolarization of both E(m) (>5 mV) and E(GABA) (>15 mV). The KB-mediated shift in E(GABA) is largely determined by the interaction of the NKCC1 cotransporter and Cl(-)/HCO3 transporter(s). Therefore, by inducing a hyperpolarizing shift in E(m) and modulating GABA signaling mode, KBs can efficiently control the excitability of neonatal cortical neurons.

  17. Acute spinal cord injury (SCI) transforms how GABA affects nociceptive sensitization.

    PubMed

    Huang, Yung-Jen; Lee, Kuan H; Murphy, Lauren; Garraway, Sandra M; Grau, James W

    2016-11-01

    Noxious input can sensitize pain (nociceptive) circuits within the spinal cord, inducing a lasting increase in spinal cord neural excitability (central sensitization) that is thought to contribute to chronic pain. The development of spinally-mediated central sensitization is regulated by descending fibers and GABAergic interneurons. The current study provides evidence that spinal cord injury (SCI) transforms how GABA affects nociceptive transmission within the spinal cord, recapitulating an earlier developmental state wherein GABA has an excitatory effect. In spinally transected rats, noxious electrical stimulation and inflammation induce enhanced mechanical reactivity (EMR), a behavioral index of nociceptive sensitization. Pretreatment with the GABA A receptor antagonist bicuculline blocked these effects. Peripheral application of an irritant (capsaicin) also induced EMR. Both the induction and maintenance of this effect were blocked by bicuculline. Cellular indices of central sensitization [c-fos expression and ERK phosphorylation (pERK)] were also attenuated. In intact (sham operated) rats, bicuculline had the opposite effect. Pretreatment with a GABA agonist (muscimol) attenuated nociceptive sensitization in intact, but not spinally injured, rats. The effect of SCI on GABA function was linked to a reduction in the Cl - transporter, KCC2, leading to a reduction in intracellular Cl - that would attenuate GABA-mediated inhibition. Pharmacologically blocking the KCC2 channel (with i.t. DIOA) in intact rats mimicked the effect of SCI. Conversely, a pharmacological treatment (bumetanide) that should increase intracellular Cl - levels blocked the effect of SCI. The results suggest that GABAergic neurons drive, rather than inhibit, the development of nociceptive sensitization after spinal injury. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Hap1 and GABA: thinking about food intake.

    PubMed

    Woods, Stephen C; Seeley, Randy J

    2006-06-01

    GABA stimulation of hypothalamic GABAA receptors increases food intake and body weight. Huntingtin-associated protein-1 (Hap1), is highly expressed in the hypothalamus and increases activity at GABAA receptors; mice lacking Hap1 are hypophagic. A recent paper (Sheng et al.,2006) further explores the role of Hap1 in the control of food intake.

  19. Drug-induced GABA transporter currents enhance GABA release to induce opioid withdrawal behaviors.

    PubMed

    Bagley, Elena E; Hacker, Jennifer; Chefer, Vladimir I; Mallet, Christophe; McNally, Gavan P; Chieng, Billy C H; Perroud, Julie; Shippenberg, Toni S; Christie, MacDonald J

    2011-10-30

    Neurotransmitter transporters can affect neuronal excitability indirectly via modulation of neurotransmitter concentrations or directly via transporter currents. A physiological or pathophysiological role for transporter currents has not been described. We found that GABA transporter 1 (GAT-1) cation currents directly increased GABAergic neuronal excitability and synaptic GABA release in the periaqueductal gray (PAG) during opioid withdrawal in rodents. In contrast, GAT-1 did not indirectly alter GABA receptor responses via modulation of extracellular GABA concentrations. Notably, we found that GAT-1-induced increases in GABAergic activity contributed to many PAG-mediated signs of opioid withdrawal. Together, these data support the hypothesis that GAT-1 activity directly produces opioid withdrawal signs through direct hyperexcitation of GABAergic PAG neurons and nerve terminals, which presumably enhances GABAergic inhibition of PAG output neurons. These data provide, to the best of our knowledge, the first evidence that dysregulation of a neurotransmitter transporter current is important for the maladaptive plasticity that underlies opiate withdrawal.

  20. Inhibition of GABA synthesis in the prefrontal cortex increases locomotor activity but does not affect attention in the 5-choice serial reaction time task.

    PubMed

    Asinof, Samuel K; Paine, Tracie A

    2013-02-01

    Attention deficits are a core cognitive symptom of schizophrenia; the neuropathology underlying these deficits is not known. Attention is regulated, at least in part, by the prefrontal cortex (PFC), a brain area in which pathology of γ-aminobutyric acid (GABA) neurons has been consistently observed in post-mortem analysis of the brains of people with schizophrenia. Specifically, expression of the 67-kD isoform of the GABA synthesis enzyme glutamic acid decarboxylase (GAD67) is reduced in parvalbumin-containing fast-spiking GABA interneurons. Thus it is hypothesized that reduced cortical GABA synthesis and release may contribute to the attention deficits in schizophrenia. Here the effect of reducing cortical GABA synthesis with l-allylglycine (LAG) on attention was tested using three different versions of the 5-choice serial reaction time task (5CSRTT). Because 5CSRTT performance can be affected by locomotor activity, we also measured this behavior in an open field. Finally, the expression of Fos protein was used as an indirect measure of reduced GABA synthesis. Intra-cortical LAG (10 μg/0.5 μl/side) infusions increased Fos expression and resulted in hyperactivity in the open field. Intra-cortical LAG infusions did not affect attention in any version of the 5CSRTT. These results suggest that a general decrease in GABA synthesis is not sufficient to cause attention deficits. It remains to be tested whether a selective decrease in GABA synthesis in parvalbumin-containing GABA neurons could cause attention deficits. Decreased cortical GABA synthesis did increase locomotor activity; this may reflect the positive symptoms of schizophrenia. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Exogenous Application of GABA Improves PEG-Induced Drought Tolerance Positively Associated with GABA-Shunt, Polyamines, and Proline Metabolism in White Clover.

    PubMed

    Yong, Bin; Xie, Huan; Li, Zhou; Li, Ya-Ping; Zhang, Yan; Nie, Gang; Zhang, Xin-Quan; Ma, Xiao; Huang, Lin-Kai; Yan, Yan-Hong; Peng, Yan

    2017-01-01

    In order to investigate the physiological effects of exogenous γ-aminobutyric acid (GABA) on drought tolerance in white clover (Trifolium repens), GABA shunt, polyamines (PAs), and proline (Pro) metabolism were examined after plants pretreated with or without GABA (8 mM) and then exposed to water or 15% PEG-induced drought stress in growth chamber. In this study, exogenous application of GABA effectively alleviated drought-induced damage in leaves, as reflected by significantly higher relative water content, lower electrolyte leakage, lipid peroxidation, and leaf wilt. Exogenous GABA further promoted drought-induced increases in GABA transaminase and alpha ketone glutarate dehydrogenase activities, but inhibited glutamate decarboxylase activity under both control and drought conditions, resulting in an increase in endogenous glutamate (Glu) and GABA content. Besides, exogenous GABA could well accelerated PAs synthesis and suppressed PAs catabolism, which lead to the extremely enhanced different types of PAs content (free Put and Spd, insoluble bound Spd and Spm, soluble conjugated Spd and Spm, and total Put, Spd and Spm) under drought stress. In addition, exogenous GABA application further activated drought-induced Δ 1 -pyrroline-5-carboxylate synthetase and proline dehydrogenase activities, but suppressed drought-facilitated ornithine -δ-amino transferase activities, leading to a higher Pro accumulation and metabolism in GABA-pretreated plants in the middle and last period of drought. The results suggested that increased endogenous GABA by exogenous GABA treatment could improve drought tolerance of white clover associated with a positive regulation in the GABA-shunt, PAs and Pro metabolism.

  2. Exogenous Application of GABA Improves PEG-Induced Drought Tolerance Positively Associated with GABA-Shunt, Polyamines, and Proline Metabolism in White Clover

    PubMed Central

    Yong, Bin; Xie, Huan; Li, Zhou; Li, Ya-Ping; Zhang, Yan; Nie, Gang; Zhang, Xin-Quan; Ma, Xiao; Huang, Lin-Kai; Yan, Yan-Hong; Peng, Yan

    2017-01-01

    In order to investigate the physiological effects of exogenous γ-aminobutyric acid (GABA) on drought tolerance in white clover (Trifolium repens), GABA shunt, polyamines (PAs), and proline (Pro) metabolism were examined after plants pretreated with or without GABA (8 mM) and then exposed to water or 15% PEG-induced drought stress in growth chamber. In this study, exogenous application of GABA effectively alleviated drought-induced damage in leaves, as reflected by significantly higher relative water content, lower electrolyte leakage, lipid peroxidation, and leaf wilt. Exogenous GABA further promoted drought-induced increases in GABA transaminase and alpha ketone glutarate dehydrogenase activities, but inhibited glutamate decarboxylase activity under both control and drought conditions, resulting in an increase in endogenous glutamate (Glu) and GABA content. Besides, exogenous GABA could well accelerated PAs synthesis and suppressed PAs catabolism, which lead to the extremely enhanced different types of PAs content (free Put and Spd, insoluble bound Spd and Spm, soluble conjugated Spd and Spm, and total Put, Spd and Spm) under drought stress. In addition, exogenous GABA application further activated drought-induced Δ1-pyrroline-5-carboxylate synthetase and proline dehydrogenase activities, but suppressed drought-facilitated ornithine -δ-amino transferase activities, leading to a higher Pro accumulation and metabolism in GABA-pretreated plants in the middle and last period of drought. The results suggested that increased endogenous GABA by exogenous GABA treatment could improve drought tolerance of white clover associated with a positive regulation in the GABA-shunt, PAs and Pro metabolism. PMID:29312009

  3. Evidence of two populations of GABA(A) receptors in cerebellar granule cells in culture: different desensitization kinetics, pharmacology, serine/threonine kinase sensitivity, and localization.

    PubMed

    Robello, M; Amico, C; Cupello, A

    1999-12-20

    GABA(A) receptors of rat cerebellar granule cells in culture have been studied by the whole cell patch clamp technique. The biphasic desensitization kinetic observed could be due either to different desensitization mechanisms of a single receptor population or to different receptor populations. The overall data indicate that the latter hypothesis is most probably the correct one. In fact, the fast desensitizing component was selectively potentiated by a benzodiazepine agonist and preferentially down-regulated by activation of the protein serine/threonine kinases A and G, as a consequence of the latter characteristic that receptor population was preferentially down-regulated by previous activation of N-methyl-d-aspartate glutamate receptors, via production of nitric oxide and PKG activation, most probably in dendrites. The other population is benzodiazepine insensitive and not influenced by activation of PKA or PKG. This slowly desensitizing population may correspond to the extrasynaptic delta subunit containing GABA(A) receptors described by other authors. Instead, the rapidly desensitizing population appears to represent dendritic synaptic GABA(A) receptors. Copyright 1999 Academic Press.

  4. Alteration of glutamate/GABA balance during acute alcohol intoxication in rats: effect of Xingnaojing injection.

    PubMed

    Wei, Jingjing; Yao, Limei; Yang, Lei; Zhao, Wei; Shi, Si; Cai, Qingyan; Chen, Dingsheng; Li, Weirong; Wang, Qi

    2015-05-26

    Xingnaojing Injection (XNJI) is a modern Chinese formula came from famous Chinese medicine An Gong Niu Huang Pill. XNJI has been used for treatment of cerebral diseases and stroke in China, and is approved by the State Food and Drug Administration of China for the treatment of acute alcohol intoxication (AAI). XNJI belongs to the ethnopharmacological family of medicines. In this study, we investigated the mechanisms of the XNJI effect on AAI. To investigate the effects of XNJI on glutamate, gamma-aminobutyric acid (GABA) and related receptor in lateral hypothalamic area (LHA) of AAI rat. Adult male Sprague-Dawley rats were implanted with microdialysis probes in LHA. Rats were randomly divided into control, model, 1.36mg/kg XNJI, 0.68mg/kg XNJI and 0.34mg/kg XNJI groups. During microdialysis, baseline samples were collected from 1h to 2.5h; thereafter, the rats were given an intraperitoneal injection of 52% ethanol, 5.2g/kg, or saline for control group. Twenty minutes later, three doses of XNJI was given by unilateral injection respectively, while saline for control and model groups, and samples were collected for the next 4h. The extracellular glutamate and GABA levels were measured in the LHA by a high performance liquid chromatography coupled with fluorescence detector (HPLC-FLU). The expression levels of related receptors N-methyl-d-aspartate receptor (NR) subunit NR2A, NR2B and GABAA were analyzed by reverse transcription polymerase chain reaction (RT-PCR). Ethanol (5.2g/kg) significantly decreased the extracellular levels of glutamate and increased extracellular GABA in LHA. On the other hand ethanol significantly decreased NR2A and NR2B mRNAs expression, and increase GABAA mRNA expression. XNJI could increase the extracellular level of glutamate and decrease that of GABA; moreover, induced an increase in NR2A and NR2B mRNA expression, and a decrease in GABAA mRNA expression in LHA. The current changes in glutamate, GABA and mRNA expressions of related

  5. Altered expression of genes involved in GABAergic transmission and neuromodulation of granule cell activity in the cerebellum of schizophrenia patients.

    PubMed

    Bullock, W Michael; Cardon, Karen; Bustillo, Juan; Roberts, Rosalinda C; Perrone-Bizzozero, Nora I

    2008-12-01

    Deficits in gamma-aminobutyric acid (GABA) signaling have been described in the prefrontal cortex, limbic system, and cerebellum in individuals with schizophrenia. The purpose of the present study was to further investigate cerebellar gene expression alterations as they relate to decreases in GABAergic transmission by examining the expression of GABAergic markers, N-methyl-d-aspartic-acid (NMDA) receptor subunits, and cerebellum neuromodulators in individuals with schizophrenia. Subjects were postmortem men with a diagnosis of schizophrenia (N=13) and a postmortem interval-matched non-psychiatric male comparison group (N=13). The authors utilized real-time-quantitative polymerase chain reaction (PCR) to measure mRNA levels of the following GABAergic markers: glutamic acid decarboxylase (GAD) 65 and 67; GABA plasma membrane transporter-1 (GAT-1); GABA type A (GABA(A)) receptor subunits alpha(6), beta(3), and delta; and parvalbumin. In addition, real-time-quantitative PCR was utilized to assess mRNA levels of the NMDA receptor (NR) subunits NR1, NR2-A, NR2-B, NR2-C, and NR2-D as well as the cerebellar neuromodulators glutamate receptor (GluR)-6, kainate-preferring glutamate receptor subunit-2 (KA2), metabotropic glutamate receptor (mGluR)-2 and mGluR3, and neuronal nitric oxide synthase. Measurements for mRNA levels were determined using lateral cerebellar hemisphere tissue from both schizophrenia and comparison subjects. Schizophrenia subjects showed significant decreases in mRNA levels of GAD(67), GAD(65), GAT-1, mGluR2, and neuronal nitric oxide synthase. Increases in GABA(A)-alpha(6 )and GABA(A)-delta as well as GluR6 and KA2 were also observed. Medication effects on the expression of the same genes were examined in rats treated with either haloperidol (Sprague-Dawley rats [N=16]) or clozapine (Long-Evans rats [N=20]). Both haloperidol and clozapine increased the levels of GAD(67) in the cerebellum and altered the expression of other cerebellar mRNAs. These

  6. The membrane effects, and sensitivity to strychnine, of neural inhibition of the Mauthner cell, and its inhibition by glycine and GABA

    PubMed Central

    Diamond, J.; Roper, S.; Yasargil, G. M.

    1973-01-01

    1. Anionic conductance changes in Mauthner neurones of goldfish were measured during synaptically evoked inhibition and inhibition caused by iontophoretic application of the putative inhibitory transmitters glycine and γ-aminobutyric acid (GABA). 2. The effects of either amino acid were indistinguishable from those of the neural inhibitory transmitter(s). The membrane permeability during the neural or drug response was increased to Br-, Cl-, I-, SCN-, NO3-, ClO3-, and formate (HCOO-), but not to HCO3-, BrO3-, IO3-, SO4-, HPO4-, H2PO4-, acetate and citrate. 3. Strychnine was injected intramuscularly, iontophoretically, or applied topically to the exposed brain in order to compare quantitatively its ability to prevent inhibition evoked by synaptic activation and by pharmacological means. Inhibitions were measured by the increase in membrane conductance. 4. Strychnine, at concentrations just adequate to block completely the late collateral inhibition (LCI) and crossed VIII nerve inhibition, had little effect on the pharmacological inhibition caused by glycine, and sometimes there was no detectable effect at all. In one experiment even a local iontophoretic application of strychnine in a sufficient dose to diffuse over the cell and block the LCI almost completely, merely halved the effect of a small dose of glycine applied to the same localized region of the membrane. 5. Higher concentrations of strychnine than those necessary to block synaptically evoked inhibition would reduce the effect of glycine but not that of GABA. The evidence indicated that any apparent effect of strychnine upon GABA could be explained by displacement of the GABA-containing iontophoretic pipette. 6. The glycine-blocking action of iontophoretic pulses of strychnine was of relatively very slow onset and long duration compared to the effects of pulses of glycine and GABA. 7. These findings can be interpreted as either (1) strychnine has a presynaptic action, preventing the release of inhibitory

  7. Responses to GABA(A) receptor activation are altered in NTS neurons isolated from renal-wrap hypertensive rats.

    PubMed

    Tolstykh, Gleb; Belugin, Sergei; Tolstykh, Olga; Mifflin, Steve

    2003-10-01

    The inhibitory amino acid GABA is a potent modulator of the spontaneous discharge and the responses to afferent inputs of neurons in the nucleus of the solitary tract (NTS). To determine if responses to activation of GABA(A) receptors are altered in hypertension, GABA(A) receptor-evoked whole cell currents were measured in enzymatically dispersed NTS neurons from 33 normotensive (NT, 109+/-4 mm Hg, n=7) and 24 hypertensive (HT, 167+/-5 mm Hg, n=24) rats. GABA(A) receptor-evoked currents reversed at the calculated equilibrium potential for chloride and were blocked by bicuculline (n=6). Membrane capacitance was the same in neurons from NT (7.5+/-0.6 pF, n=62) and HT (6.8+/-0.6 pF, n=51) rats. The EC50 for peak GABA-evoked currents cells was significantly greater in neurons from HT (21.0+/-2.6 micromol/L, n=16) compared with NT rats (13.0+/-1.8 micromol/L, n=14, P=0.01). The EC50 of neurons exhibiting DiA labeling of presumptive aortic nerve terminals was no different than that observed in the nonlabeled cells (19.0+/-4.9 micromol/L, n=4). The time constant for desensitization of GABA(A)-evoked currents was the same in neurons from HT (4.5+/-0.3 seconds, n=17) and NT rats (3.8+/-0.3 seconds, n=17, P>0.05). Repetitive pulse application of GABA revealed a more rapid decline in the evoked current in neurons from HT compared with NT rats. The amplitude of the 5th pulse of GABA (5-second duration, 2-second interval) was 21+/-2% the amplitude of the 1st pulse in NT rats (n=10) and 14+/-2% in HT rats (n=11, P<0.05). These alterations in GABAA-receptor evoked currents could render the neurons less sensitive to GABA(A) receptor inhibition and influence afferent integration by NTS neurons in HT.

  8. Ghrelin Causes a Decline in GABA Release by Reducing Fatty Acid Oxidation in Cortex.

    PubMed

    Mir, Joan Francesc; Zagmutt, Sebastián; Lichtenstein, Mathieu P; García-Villoria, Judit; Weber, Minéia; Gracia, Ana; Fabriàs, Gemma; Casas, Josefina; López, Miguel; Casals, Núria; Ribes, Antònia; Suñol, Cristina; Herrero, Laura; Serra, Dolors

    2018-02-02

    Lipid metabolism, specifically fatty acid oxidation (FAO) mediated by carnitine palmitoyltransferase (CPT) 1A, has been described to be an important actor of ghrelin action in hypothalamus. However, it is not known whether CPT1A and FAO mediate the effect of ghrelin on the cortex. Here, we show that ghrelin produces a differential effect on CPT1 activity and γ-aminobutyric acid (GABA) metabolism in the hypothalamus and cortex of mice. In the hypothalamus, ghrelin enhances CPT1A activity while GABA transaminase (GABAT) activity, a key enzyme in GABA shunt metabolism, is unaltered. However, in cortex CPT1A activity and GABAT activity are reduced after ghrelin treatment. Furthermore, in primary cortical neurons, ghrelin reduces GABA release through a CPT1A reduction. By using CPT1A floxed mice, we have observed that genetic ablation of CPT1A recapitulates the effect of ghrelin on GABA release in cortical neurons, inducing reductions in mitochondrial oxygen consumption, cell content of citrate and α-ketoglutarate, and GABA shunt enzyme activity. Taken together, these observations indicate that ghrelin-induced changes in CPT1A activity modulate mitochondrial function, yielding changes in GABA metabolism. This evidence suggests that the action of ghrelin on GABA release is region specific within the brain, providing a basis for differential effects of ghrelin in the central nervous system.

  9. Genes in the GABA pathway increase in the lateral thalamus of Sprague Dawley rats during the proestrus/estrus phase

    PubMed Central

    Umorin, Mikhail; Stinson, Crystal; Bellinger, Larry L.; Kramer, Phillip

    2015-01-01

    Pain can vary over the estrous cycle as a result of changes in estradiol concentration but the mechanism causing this variation is unclear. Because the thalamus is important in pain control, gene expression in the lateral thalamus (ventral posteromedial, ventral posterolateral, reticular thalamic nuclei) was screened at different phases of the estrous cycle. Gene expression changes in Sprague-Dawley rats were further analyzed by real-time PCR and ELISA and plasma estradiol levels were measured by RIAs at different phases of the estrous cycle. Our results indicated that both the RNA and protein expression of glutamate decarboxylase 1 and 2 (GAD1, GAD2), GABA(A) receptor-associated protein like 1 (GABARAPL1) and vesicular GABA transporter (VGAT) significantly increased in the lateral thalamus when plasma estradiol levels were elevated. Estradiol levels were elevated during the proestrus and estrus phases of the estrous cycle. Estrogen receptor α (ERα) was observed to be co-localized in thalamic cells and thalamic infusion of an ERα antagonist significantly reduced GAD1 and VGAT transcript. GAD1, GAD2 GABARAPL1 and VGAT have been shown to effect neuronal responses suggesting that modulation of pain during the estrous cycle can be dependent, in part, through estradiol induced changes in thalamic gene expression. PMID:26388520

  10. Depolarizing actions of GABA in immature neurons depend neither on ketone bodies nor on pyruvate.

    PubMed

    Tyzio, Roman; Allene, Camille; Nardou, Romain; Picardo, Michel A; Yamamoto, Sumii; Sivakumaran, Sudhir; Caiati, Maddalena D; Rheims, Sylvain; Minlebaev, Marat; Milh, Mathieu; Ferré, Pascal; Khazipov, Rustem; Romette, Jean-Louis; Lorquin, Jean; Cossart, Rosa; Khalilov, Ilgam; Nehlig, Astrid; Cherubini, Enrico; Ben-Ari, Yehezkel

    2011-01-05

    GABA depolarizes immature neurons because of a high [Cl(-)](i) and orchestrates giant depolarizing potential (GDP) generation. Zilberter and coworkers (Rheims et al., 2009; Holmgren et al., 2010) showed recently that the ketone body metabolite DL-3-hydroxybutyrate (DL-BHB) (4 mM), lactate (4 mM), or pyruvate (5 mM) shifted GABA actions to hyperpolarizing, suggesting that the depolarizing effects of GABA are attributable to inadequate energy supply when glucose is the sole energy source. We now report that, in rat pups (postnatal days 4-7), plasma D-BHB, lactate, and pyruvate levels are 0.9, 1.5, and 0.12 mM, respectively. Then, we show that DL-BHB (4 mM) and pyruvate (200 μM) do not affect (i) the driving force for GABA(A) receptor-mediated currents (DF(GABA)) in cell-attached single-channel recordings, (2) the resting membrane potential and reversal potential of synaptic GABA(A) receptor-mediated responses in perforated patch recordings, (3) the action potentials triggered by focal GABA applications, or (4) the GDPs determined with electrophysiological recordings and dynamic two-photon calcium imaging. Only very high nonphysiological concentrations of pyruvate (5 mM) reduced DF(GABA) and blocked GDPs. Therefore, DL-BHB does not alter GABA signals even at the high concentrations used by Zilberter and colleagues, whereas pyruvate requires exceedingly high nonphysiological concentrations to exert an effect. There is no need to alter conventional glucose enriched artificial CSF to investigate GABA signals in the developing brain.

  11. A tonoplast Glu/Asp/GABA exchanger that affects tomato fruit amino acid composition.

    PubMed

    Snowden, Christopher J; Thomas, Benjamin; Baxter, Charles J; Smith, J Andrew C; Sweetlove, Lee J

    2015-03-01

    Vacuolar accumulation of acidic metabolites is an important aspect of tomato fruit flavour and nutritional quality. The amino acids Asp and Glu accumulate to high concentrations during ripening, while γ-aminobutyrate (GABA) shows an approximately stoichiometric decline. Given that GABA can be catabolised to form Glu and subsequently Asp, and the requirement for the fruit to maintain osmotic homeostasis during ripening, we hypothesised the existence of a tonoplast transporter that exports GABA from the vacuole in exchange for import of either Asp or Glu. We show here that the tomato vacuolar membrane possesses such a transport property: transport of Glu across isolated tonoplast vesicle membranes was trans-stimulated in counterexchange mode by GABA, Glu and Asp. We identified SlCAT9 as a candidate protein for this exchanger using quantitative proteomics of a tonoplast-enriched membrane fraction. Transient expression of a SlCAT9-YFP fusion in tobacco confirmed a tonoplast localisation. The function of the protein was examined by overexpression of SlCAT9 in transgenic tomato plants. Tonoplast vesicles isolated from transgenic plants showed higher rates of Glu and GABA transport than wild-type (WT) only when assayed in counterexchange mode with Glu, Asp, or GABA. Moreover, there were substantial increases in the content of all three cognate amino acids in ripe fruit from the transgenic plants. We conclude that SlCAT9 is a tonoplast Glu/Asp/GABA exchanger that strongly influences the accumulation of these amino acids during fruit development. © 2015 The Authors The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.

  12. Norepinephrine-gamma-aminobutyric acid (GABA) interaction in limbic stress circuits: effects of reboxetine on GABAergic neurons.

    PubMed

    Herman, James P; Renda, Andrew; Bodie, Bryan

    2003-01-15

    Reboxetine is a selective norepinephrine (NE) reuptake inhibitor that exerts significant antidepressant action. The current study assessed norepinephrine-gamma-aminobutyric acid (GABA)-ergic mechanisms in reboxetine action, examining glutamic acid decarboxylase (GAD) mRNA expression in limbic neurocircuits following reboxetine within the context of chronic stress. Male rats received 25 mg/kg reboxetine/day, p.o. Reboxetine and vehicle animals were exposed to 1 week of variable stress exposure or handling. Behavioral responses to stress (open field) were tested on day 7, and animals were killed on day 8 to assess neuroendocrine stress responses and limbic GAD65/67 mRNA regulation (in situ hybridization). Reboxetine significantly decreased behavioral reactivity in the open field. Reboxetine administration did not affect expression of GAD65/67 mRNA in handled rats; however, administration to stressed animals reduced GAD67 (but not GAD65) mRNA in the medial amygdaloid nucleus, posteromedial bed nucleus of the stria terminalis, and dentate gyrus. In contrast, GAD65 mRNA expression was increased by reboxetine in the lateral septum of stressed animals. Norepinephrine pathways appear to modulate synthesis of GABA in central limbic stress circuits. Decreases in GABA synthetic capacity suggest reduced activation of stress-excitatory pathways and enhanced activation of stress-inhibitory circuits, and is consistent with a role for GABA in the antidepressant efficacy of NE reuptake inhibitors.

  13. Prevention of GABA reduction during dough fermentation using a baker's yeast dal81 mutant.

    PubMed

    Ando, Akira; Nakamura, Toshihide

    2016-10-01

    γ-Aminobutyric acid (GABA) is consumed by yeasts during fermentation. To prevent GABA reduction in bread dough, a baker's yeast mutant AY77 deficient in GABA assimilation was characterized and utilized for wheat dough fermentation. An amber mutation in the DAL81 gene, which codes for a positive regulator of multiple nitrogen degradation pathways, was found in the AY77 strain. The qPCR analyses of genes involved in nitrogen utilization showed that transcriptional levels of the UGA1 and DUR3 genes encoding GABA transaminase and urea transporter, respectively, are severely decreased in the AY77 cells. The AY77 strain cultivated by fed-batch culture using cane molasses exhibited inferior gas production during dough fermentation compared to that of wild-type strain AY13. However, when fed with molasses containing 0.5% ammonium sulfate, the mutant strain exhibited gas production comparable to that of the AY13 strain. In contrast to the AY13 strain, which completely consumed GABA in dough within 5 h, the AY77 strain consumed no GABA under either culture condition. Dough fermentation with the dal81 mutant strain should be useful for suppression of GABA reduction in breads. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  14. The main source of ambient GABA responsible for tonic inhibition in the mouse hippocampus

    PubMed Central

    Glykys, Joseph; Mody, Istvan

    2007-01-01

    The extracellular space of the brain contains γ-aminobutyric acid (GABA) that activates extrasynaptic GABAA receptors mediating tonic inhibition. The source of this GABA is uncertain: it could be overspill of vesicular release, non-vesicular leakage, reverse transport, dying cells or glia. Using a novel approach, we simultaneously measured phasic and tonic inhibitory currents and assessed their correlation. Enhancing or diminishing vesicular GABA release in hippocampal neurons caused highly correlated changes in the two inhibitions. During high-frequency phasic inhibitory bursts, tonic current was also enhanced as shown by simulating the summation of IPSCs and by recordings in knockout mice devoid of tonic inhibitory current. When vesicular release was reduced by blocking action potentials or the vesicular GABA transporter, phasic and tonic currents decreased in a correlated fashion. Our results are consistent with most of hippocampal tonic inhibitory current being mediated by GABA released from the very vesicles responsible for activating phasic inhibition. PMID:17525114

  15. Expression of S100 beta in sensory and secretory cells of the vertebrate inner ear

    NASA Technical Reports Server (NTRS)

    Fermin, C. D.; Martin, D. S.

    1995-01-01

    We evaluated anti-S100 beta expression in the chick (Gallus domesticus) inner ear and determined that: 1) the monomer anti-S100 beta is expressed differentially in the vestibular and auditory perikarya; 2) expression of S100 beta in the afferent nerve terminals is time-related to synapse and myelin formation; 3) the expression of the dimer anti-S100 alpha alpha beta beta and monomer anti-S100 beta overlaps in most inner ear cell types. Most S100 alpha alpha beta beta positive cells express S100 beta, but S100 beta positive cells do not always express S100 alpha alpha beta beta. 4) the expression of S100 beta is diffused over the perikaryal cytoplasm and nuclei of the acoustic ganglia but is concentrated over the nuclei of the vestibular perikarya. 6) S100 beta is expressed in secretory cells, and it is co-localized with GABA in sensory cells. 7) Color thresholding objective quantitation indicates that the amount of S100 beta was higher (mean 22, SD +/- 4) at E19 than at E9 (mean 34, SD +/- 3) in afferent axons. 8) Moreover, S100 beta was unchanged between E11-E19 in the perikaryal cytoplasm, but did change over the nuclei. At E9, 74%, and at E21, 5% of vestibular perikarya were positive. The data suggest that S100 beta may be physically associated with neuronal and ionic controlling cells of the vertebrate inner ear, where it could provide a dual ionic and neurotrophic modulatory function.

  16. Regulation of α3-containing GABAA receptors in guinea-pig adrenal medullary cells by adrenal steroids.

    PubMed

    Inoue, M; Harada, K; Nakamura, J; Matsuoka, H

    2013-12-03

    GABA is thought to function as a paracrine factor in adrenal medullary (AM) cells. Thus, we electrophysiologically and immunologically examined the properties of GABAA receptors (GABAARs) in guinea-pig AM cells. Bath application of GABA produced an inward current at -60 mV in a dose-dependent manner with an EC50 of 32.3 μM. This GABA-induced current was enhanced by allopregnanolone at concentrations of 0.01 μM and more. A prior exposure to allopregnanolone resulted in a decrease in an EC50 for GABA in activating GABAARs. The GABA-induced current was suppressed by Zn(2+) in a dose-dependent manner with an IC50 of 18 μM, whereas it was enhanced by 100 μM La(3+). The benzodiazepine analog diazepam was three times more potent than zolpidem in enhancing the GABA current, and it was also augmented by L-838,417, which has no action on α1-containing GABAARs. The GABAAR α3, but not α1, and γ2 subunits were immunologically detected at the cell periphery. The expression of α3 subunits in PC12 cells was enhanced by glucocorticoid activity. The results indicated that GABAARs in guinea-pig AM cells mainly comprise α3, β, and γ2 subunits and are enhanced by allopreganalone and glucocorticoids may play a major role in the expression of α3 subunits. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  17. Sleep and Movement Differentiates Actions of Two Types of Somatostatin-Expressing GABAergic Interneuron in Rat Hippocampus

    PubMed Central

    Katona, Linda; Lapray, Damien; Viney, Tim J.; Oulhaj, Abderrahim; Borhegyi, Zsolt; Micklem, Benjamin R.; Klausberger, Thomas; Somogyi, Peter

    2014-01-01

    Summary Neuropeptides acting on pre- and postsynaptic receptors are coreleased with GABA by interneurons including bistratified and O-LM cells, both expressing somatostatin but innervating segregated dendritic domains of pyramidal cells. Neuropeptide release requires high-frequency action potentials, but the firing patterns of most peptide/GABA-releasing interneurons during behavior are unknown. We show that behavioral and network states differentiate the activities of bistratified and O-LM cells in freely moving rats. Bistratified cells fire at higher rates during sleep than O-LM cells and, unlike O-LM cells, strongly increase spiking during sharp wave-associated ripples (SWRs). In contrast, O-LM interneurons decrease firing during sleep relative to awake states and are mostly inhibited during SWRs. During movement, both cell types fire cooperatively at the troughs of theta oscillations but with different frequencies. Somatostatin and GABA are differentially released to distinct dendritic zones of CA1 pyramidal cells during sleep and wakefulness to coordinate segregated glutamatergic inputs from entorhinal cortex and CA3. PMID:24794095

  18. Impaired striatal GABA transmission in experimental autoimmune encephalomyelitis.

    PubMed

    Rossi, Silvia; Muzio, Luca; De Chiara, Valentina; Grasselli, Giorgio; Musella, Alessandra; Musumeci, Gabriele; Mandolesi, Georgia; De Ceglia, Roberta; Maida, Simona; Biffi, Emilia; Pedrocchi, Alessandra; Menegon, Andrea; Bernardi, Giorgio; Furlan, Roberto; Martino, Gianvito; Centonze, Diego

    2011-07-01

    Synaptic dysfunction triggers neuronal damage in experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS). While excessive glutamate signaling has been reported in the striatum of EAE, it is still uncertain whether GABA synapses are altered. Electrophysiological recordings showed a reduction of spontaneous GABAergic synaptic currents (sIPSCs) recorded from striatal projection neurons of mice with MOG((35-55))-induced EAE. GABAergic sIPSC deficits started in the acute phase of the disease (20-25days post immunization, dpi), and were exacerbated at later time-points (35, 50, 70 and 90dpi). Of note, in slices they were independent of microglial activation and of release of TNF-α. Indeed, sIPSC inhibition likely involved synaptic inputs arising from GABAergic interneurons, because EAE preferentially reduced sIPSCs of high amplitude, and was associated with a selective loss of striatal parvalbumin (PV)-positive GABAergic interneurons, which contact striatal projection neurons in their somatic region, giving rise to more efficient synaptic inhibition. Furthermore, we found also that the chronic persistence of pro-inflammatory cytokines were able, per se, to produce profound alterations of electrophysiological network properties, that were reverted by GABA administration. The results of the present investigation indicate defective GABA transmission in MS models depending from alteration of PV cells number and, in part, deriving from the effects of a chronic inflammation, and suggest that pharmacological agents potentiating GABA signaling might be considered to limit neuronal damage in MS patients. Copyright © 2010 Elsevier Inc. All rights reserved.

  19. Acutely increasing δGABA(A) receptor activity impairs memory and inhibits synaptic plasticity in the hippocampus.

    PubMed

    Whissell, Paul D; Eng, Dave; Lecker, Irene; Martin, Loren J; Wang, Dian-Shi; Orser, Beverley A

    2013-01-01

    Extrasynaptic γ-aminobutyric acid type A (GABA(A)) receptors that contain the δ subunit (δGABA(A) receptors) are expressed in several brain regions including the dentate gyrus (DG) and CA1 subfields of the hippocampus. Drugs that increase δGABA(A) receptor activity have been proposed as treatments for a variety of disorders including insomnia, epilepsy and chronic pain. Also, long-term pretreatment with the δGABA(A) receptor-preferring agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) enhances discrimination memory and increases neurogenesis in the DG. Despite the potential therapeutic benefits of such treatments, the effects of acutely increasing δGABA(A) receptor activity on memory behaviors remain unknown. Here, we studied the effects of THIP (4 mg/kg, i.p.) on memory performance in wild-type (WT) and δGABA(A) receptor null mutant (Gabrd(-/-)) mice. Additionally, the effects of THIP on long-term potentiation (LTP), a molecular correlate of memory, were studied within the DG and CA1 subfields of the hippocampus using electrophysiological recordings of field potentials in hippocampal slices. The results showed that THIP impaired performance in the Morris water maze, contextual fear conditioning and object recognition tasks in WT mice but not Gabrd(-/-) mice. Furthermore, THIP inhibited LTP in hippocampal slices from WT but not Gabrd(-/-) mice, an effect that was blocked by GABA(A) receptor antagonist bicuculline. Thus, acutely increasing δGABA(A) receptor activity impairs memory behaviors and inhibits synaptic plasticity. These results have important implications for the development of therapies aimed at increasing δGABA(A) receptor activity.

  20. Brain gamma-aminobutyric acid (GABA) abnormalities in bipolar disorder

    PubMed Central

    Brady, Roscoe O; McCarthy, Julie M; Prescot, Andrew P; Jensen, J Eric; Cooper, Alissa J; Cohen, Bruce M; Renshaw, Perry F; Ongür, Dost

    2017-01-01

    Objectives Gamma-aminobutyric acid (GABA) abnormalities have been implicated in bipolar disorder. However, due to discrepant studies measuring postmortem, cerebrospinal fluid, plasma, and in vivo brain levels of GABA, the nature of these abnormalities is unclear. Using proton magnetic resonance spectroscopy, we investigated tissue levels of GABA in the anterior cingulate cortex and parieto-occipital cortex of participants with bipolar disorder and healthy controls. Methods Fourteen stably medicated euthymic outpatients with bipolar disorder type I (mean age 32.6 years, eight male) and 14 healthy control participants (mean age 36.9 years, 10 male) completed a proton magnetic resonance spectroscopy scan at 4-Tesla after providing informed consent. We collected data from two 16.7-mL voxels using MEGAPRESS, and they were analyzed using LCModel. Results GABA/creatine ratios were elevated in bipolar disorder participants compared to healthy controls [F(1,21) = 4.4, p = 0.048] in the anterior cingulate cortex (25.1% elevation) and the parieto-occipital cortex (14.6% elevation). Bipolar disorder participants not taking GABA-modulating medications demonstrated greater GABA/creatine elevations than patients taking GABA-modulating medications. Conclusions We found higher GABA/creatine levels in euthymic bipolar disorder outpatients compared to healthy controls, and the extent of this elevation may be affected by the use of GABA-modulating medications. Our findings suggest that elevated brain GABA levels in bipolar disorder may be associated with GABAergic dysfunction and that GABA-modulating medications reduce GABA levels in this condition. PMID:23634979

  1. Meta-diamide insecticides acting on distinct sites of RDL GABA receptor from those for conventional noncompetitive antagonists.

    PubMed

    Nakao, Toshifumi; Banba, Shinich; Nomura, Michikazu; Hirase, Kangetsu

    2013-04-01

    The RDL GABA receptor is an attractive target of insecticides. Here we demonstrate that meta-diamides [3-benzamido-N-(4-(perfluoropropan-2-yl)phenyl)benzamides] are a distinct class of RDL GABA receptor antagonists showing high insecticidal activity against Spodoptera litura. We also suggest that the mode of action of the meta-diamides is distinct from that of conventional noncompetitive antagonists (NCAs), such as fipronil, picrotoxin, lindane, dieldrin, and α-endosulfan. Using a membrane potential assay, we examined the effects of the meta-diamide 3-benzamido-N-(2-bromo-4-(perfluoropropan-2-yl)-6-(trifluoromethyl)phenyl)-2-fluorobenzamide (meta-diamide 7) and NCAs on mutant Drosophila RDL GABA receptors expressed in Drosophila Mel-2 cells. NCAs had little or no inhibitory activity against at least one of the three mutant receptors (A2'S, A2'G, and A2'N), which were reported to confer resistance to NCAs. In contrast, meta-diamide 7 inhibited all three A2' mutant receptors, at levels comparable to its activity with the wild-type receptor. Furthermore, the A2'S·T6'V mutation almost abolished the inhibitory effects of all NCAs. However, meta-diamide 7 inhibited the A2'S・T6'S mutant receptor at the same level as its activity with the wild-type receptor. In contrast, a G336M mutation in the third transmembrane domain of the RDL GABA receptor abolished the inhibitory activities of meta-diamide 7, although the G336M mutation had little effect on the inhibitory activities of conventional NCAs. Molecular modeling studies also suggested that the binding site of meta-diamides was different from those of NCAs. Meta-diamide insecticides are expected to be prominent insecticides effective against A2' mutant RDL GABA receptors with a different mode of action. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Activation of VTA GABA neurons disrupts reward consumption

    PubMed Central

    van Zessen, Ruud; Phillips, Jana L.; Budygin, Evgeny A.; Stuber, Garret D.

    2012-01-01

    The activity of Ventral Tegmental Area (VTA) dopamine (DA) neurons promotes behavioral responses to rewards and environmental stimuli that predict them. VTA GABA inputs synapse directly onto DA neurons and may regulate DA neuronal activity to alter reward-related behaviors, however, the functional consequences of selective activation of VTA GABA neurons remains unknown. Here, we show that in vivo optogenetic activation of VTA GABA neurons disrupts reward consummatory behavior, but not conditioned anticipatory behavior in response to reward-predictive cues. In addition, direct activation of VTA GABA projections to the nucleus accumbens (NAc) resulted in detectable GABA release, but did not alter reward consumption. Furthermore, optogenetic stimulation of VTA GABA neurons directly suppressed the activity and excitability of neighboring DA neurons, as well as the release of DA in the NAc, suggesting that the dynamic interplay between VTA DA and GABA neurons can control the initiation and termination of reward-related behaviors. PMID:22445345

  3. Decreased GABA receptor in the striatum and spatial recognition memory deficit in epileptic rats: effect of Bacopa monnieri and bacoside-A.

    PubMed

    Mathew, Jobin; Soman, Smijin; Sadanandan, Jayanarayanan; Paulose, Cheramadathikudyil Skaria

    2010-07-20

    Gamma-aminobutyric acid A receptors are the principal mediators of synaptic inhibition in striatal neurons and play an important role in preventing the spreading of seizures through the striatum. In the present study, effect of Bacopa monnieri (L.) Pennel and its active component bacoside-A on spatial recognition memory deficit and alterations of GABA receptor in the striatum of epileptic rats were investigated. Total GABA and GABA(A) receptor numbers in the control and epileptic rats were evaluated using [(3)H]GABA and [(3)H]bicuculline binding. GABA(Aalpha1,) GABA(Aalpha5,) GABA(Agamma3) and GABA(Adelta) gene expressions were studied. Behavioral performance was assed using Y-maze. Scatchard analysis of [(3)H]GABA and [(3)H]bicuculline in the striatum of epileptic rats showed significant decrease in B(max) compared to control. Real-Time PCR amplification of GABA(A) receptor subunits such as GABA(Aalpha1,) GABA(Aalpha5) and GABA(Adelta), were down regulated (p<0.001) in the striatum of epileptic rats compared to control. Epileptic rats have deficit in Y-maze performance. Bacopa monnieri and bacoside-A treatment reversed these changes to near control. Our results suggest that decreased GABA receptors in the striatum have an important role in epilepsy associated motor learning deficits and Bacopa monnieri and bacoside-A has a beneficial effect in the management of epilepsy. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  4. Production of gaba (γ - Aminobutyric acid) by microorganisms: a review.

    PubMed

    Dhakal, Radhika; Bajpai, Vivek K; Baek, Kwang-Hyun

    2012-10-01

    GABA (γ-aminobutyric acid) is a four carbon non-protein amino acid that is widely distributed in plants, animals and microorganisms. As a metabolic product of plants and microorganisms produced by the decarboxylation of glutamic acid, GABA functions as an inhibitory neurotransmitter in the brain that directly affects the personality and the stress management. A wide range of traditional foods produced by microbial fermentation contain GABA, in which GABA is safe and eco-friendly, and also has the possibility of providing new health-benefited products enriched with GABA. Synthesis of GABA is catalyzed by glutamate decarboxylase, therefore, the optimal fermentation condition is mainly based on the biochemical properties of the enzyme. Major GABA producing microorganisms are lactic acid bacteria (LAB), which make food spoilage pathogens unable to grow and act as probiotics in the gastrointestinal tract. The major factors affecting the production of GABA by microbial fermentation are temperature, pH, fermentation time and different media additives, therefore, these factors are summarized to provide the most up-dated information for effective GABA synthesis. There has been a huge accumulation of knowledge on GABA application for human health accompanying with a demand on natural GABA supply. Only the GABA production by microorganisms can fulfill the demand with GABA-enriched health beneficial foods.

  5. GABA is not elevated during neuroprotective neuronal depression in the hypoxic epaulette shark (Hemiscyllium ocellatum).

    PubMed

    Mulvey, Jamin M; Renshaw, Gillian M C

    2009-02-01

    Prolonged hypoxic exposure results in cell failure, glutamate excitotoxicity and apoptosis in the brain. The epaulette shark can withstand prolonged hypoxic exposure without brain injury, while maintaining normal function and activity at tropical temperatures. We examined whether the inhibitory neurotransmitter GABA was involved in hypoxia tolerance and neuroprotection during hypoxic preconditioning. Sharks were exposed to either cyclic hypoxic preconditioning or normoxic conditions. Whole brain GABA concentration was determined using high performance liquid chromatography; GABA distribution in neuronal structures was localised with immunohistochemistry and quantified. While the overall brain level of GABA was not significantly different, there was a significant heterogeneous change in GABA distribution. GABA immunoreactivity was elevated in key motor and sensory nuclei from preconditioned animals, including the nucleus motorius nervi vagi and the cerebellar crest (p<0.001), corresponding to areas of previously reported neuronal hypometabolism. Since the neuroprotection in all other hypoxia and anoxia tolerant species examined so far relies in part on significant elevations in GABA and the phylogenetically older epaulette shark does not, it is reasonable to assume that further research in this unique animal model may yield clues to new key modulators of neuroprotection. Understanding such mechanisms may facilitate the development of therapeutic interventions in the treatment of transient ischaemic attacks, strokes and traumatic brain injury.

  6. Design and Mechanism of Tetrahydrothiophene-based GABA Aminotransferase Inactivators

    PubMed Central

    Le, Hoang V.; Hawker, Dustin D.; Wu, Rui; Doud, Emma; Widom, Julia; Sanishvili, Ruslan; Liu, Dali; Kelleher, Neil L.; Silverman, Richard B.

    2015-01-01

    Low levels of γ-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the blood-brain barrier and inhibit the activity of γ-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally-restricted, tetrahydrothiophene-based GABA analogs with a properly-positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is eight times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bond interactions with Arg-192, a π-π interaction with Phe-189, and a weak nonbonded S···O=C interaction with Glu-270, thereby inactivating the enzyme. PMID:25781189

  7. Big GABA: Edited MR spectroscopy at 24 research sites.

    PubMed

    Mikkelsen, Mark; Barker, Peter B; Bhattacharyya, Pallab K; Brix, Maiken K; Buur, Pieter F; Cecil, Kim M; Chan, Kimberly L; Chen, David Y-T; Craven, Alexander R; Cuypers, Koen; Dacko, Michael; Duncan, Niall W; Dydak, Ulrike; Edmondson, David A; Ende, Gabriele; Ersland, Lars; Gao, Fei; Greenhouse, Ian; Harris, Ashley D; He, Naying; Heba, Stefanie; Hoggard, Nigel; Hsu, Tun-Wei; Jansen, Jacobus F A; Kangarlu, Alayar; Lange, Thomas; Lebel, R Marc; Li, Yan; Lin, Chien-Yuan E; Liou, Jy-Kang; Lirng, Jiing-Feng; Liu, Feng; Ma, Ruoyun; Maes, Celine; Moreno-Ortega, Marta; Murray, Scott O; Noah, Sean; Noeske, Ralph; Noseworthy, Michael D; Oeltzschner, Georg; Prisciandaro, James J; Puts, Nicolaas A J; Roberts, Timothy P L; Sack, Markus; Sailasuta, Napapon; Saleh, Muhammad G; Schallmo, Michael-Paul; Simard, Nicholas; Swinnen, Stephan P; Tegenthoff, Martin; Truong, Peter; Wang, Guangbin; Wilkinson, Iain D; Wittsack, Hans-Jörg; Xu, Hongmin; Yan, Fuhua; Zhang, Chencheng; Zipunnikov, Vadim; Zöllner, Helge J; Edden, Richard A E

    2017-10-01

    Magnetic resonance spectroscopy (MRS) is the only biomedical imaging method that can noninvasively detect endogenous signals from the neurotransmitter γ-aminobutyric acid (GABA) in the human brain. Its increasing popularity has been aided by improvements in scanner hardware and acquisition methodology, as well as by broader access to pulse sequences that can selectively detect GABA, in particular J-difference spectral editing sequences. Nevertheless, implementations of GABA-edited MRS remain diverse across research sites, making comparisons between studies challenging. This large-scale multi-vendor, multi-site study seeks to better understand the factors that impact measurement outcomes of GABA-edited MRS. An international consortium of 24 research sites was formed. Data from 272 healthy adults were acquired on scanners from the three major MRI vendors and analyzed using the Gannet processing pipeline. MRS data were acquired in the medial parietal lobe with standard GABA+ and macromolecule- (MM-) suppressed GABA editing. The coefficient of variation across the entire cohort was 12% for GABA+ measurements and 28% for MM-suppressed GABA measurements. A multilevel analysis revealed that most of the variance (72%) in the GABA+ data was accounted for by differences between participants within-site, while site-level differences accounted for comparatively more variance (20%) than vendor-level differences (8%). For MM-suppressed GABA data, the variance was distributed equally between site- (50%) and participant-level (50%) differences. The findings show that GABA+ measurements exhibit strong agreement when implemented with a standard protocol. There is, however, increased variability for MM-suppressed GABA measurements that is attributed in part to differences in site-to-site data acquisition. This study's protocol establishes a framework for future methodological standardization of GABA-edited MRS, while the results provide valuable benchmarks for the MRS community

  8. Genetics Home Reference: GABA-transaminase deficiency

    MedlinePlus

    ... Chiriboga CA, Ichikawa K, Osaka H, Tsuji M, Gibson KM, Bonnen PE, Pearl PL. Phenotype of GABA- ... Meirleir L, Jaeken J, Jakobs C, Nyhan WL, Gibson KM. 4-Aminobutyrate aminotransferase (GABA-transaminase) deficiency. J ...

  9. Distribution of metabotropic receptors of serotonin, dopamine, GABA, glutamate, and short neuropeptide F in the central complex of Drosophila.

    PubMed

    Kahsai, L; Carlsson, M A; Winther, A M E; Nässel, D R

    2012-04-19

    The central complex is a prominent set of midline neuropils in the insect brain, known to be a higher locomotor control center that integrates visual inputs and modulates motor outputs. It is composed of four major neuropil structures, the ellipsoid body (EB), fan-shaped body (FB), noduli (NO), and protocerebral bridge (PB). In Drosophila different types of central complex neurons have been shown to express multiple neuropeptides and neurotransmitters; however, the distribution of corresponding receptors is not known. Here, we have mapped metabotropic, G-protein-coupled receptors (GPCRs) of several neurotransmitters to neurons of the central complex. By combining immunocytochemistry with GAL4 driven green fluorescent protein, we examined the distribution patterns of six different GPCRs: two serotonin receptor subtypes (5-HT(1B) and 5-HT(7)), a dopamine receptor (DopR), the metabotropic GABA(B) receptor (GABA(B)R), the metabotropic glutamate receptor (DmGluR(A)) and a short neuropeptide F receptor (sNPFR1). Five of the six GPCRs were mapped to different neurons in the EB (sNPFR1 was not seen). Different layers of the FB express DopR, GABA(B)R, DmGluR(A,) and sNPFR1, whereas only GABA(B)R and DmGluR(A) were localized to the PB. Finally, strong expression of DopR and DmGluR(A) was detected in the NO. In most cases the distribution patterns of the GPCRs matched the expression of markers for their respective ligands. In some nonmatching regions it is likely that other types of dopamine and serotonin receptors or ionotropic GABA and glutamate receptors are expressed. Our data suggest that chemical signaling and signal modulation are diverse and highly complex in the different compartments and circuits of the Drosophila central complex. The information provided here, on receptor distribution, will be very useful for future analysis of functional circuits in the central complex, based on targeted interference with receptor expression. Copyright © 2012 IBRO. Published by

  10. Optogenetic and pharmacological evidence that somatostatin‐GABA neurons are important regulators of parasympathetic outflow to the stomach

    PubMed Central

    Lewin, Amanda E.; Vicini, Stefano; Richardson, Janell; Dretchen, Kenneth L.; Gillis, Richard A.

    2016-01-01

    Key points The dorsal motor nucleus of the vagus (DMV) in the brainstem consists primarily of vagal preganglionic neurons that innervate postganglionic neurons of the upper gastrointestinal tract.The activity of the vagal preganglionic neurons is predominantly regulated by GABAergic transmission in the DMV.The present findings indicate that the overwhelming GABAergic drive present at the DMV is primarily from somatostatin positive GABA (Sst‐GABA) DMV neurons.Activation of both melanocortin and μ‐opioid receptors at the DMV inhibits Sst‐GABA DMV neurons.Sst‐GABA DMV neurons may serve as integrative targets for modulating vagal output activity to the stomach. Abstract We have previously shown that local GABA signalling in the brainstem is an important determinant of vagally‐mediated gastric activity. However, the neural identity of this GABA source is currently unknown. To determine this, we focused on the somatostatin positive GABA (Sst‐GABA) interneuron in the dorsal motor nucleus of the vagus (DMV), a nucleus that is intimately involved in regulating gastric activity. Also of particular interest was the effect of melanocortin and μ‐opioid agonists on neural activity of Sst‐GABA DMV neurons because their in vivo administration in the DMV mimics GABA blockade in the nucleus. Experiments were conducted in brain slice preparation of transgenic adult Sst‐IRES‐Cre mice expressing tdTomato fluorescence, channelrhodopsin‐2, archaerhodopsin or GCaMP3. Electrophysiological recordings were obtained from Sst‐GABA DMV neurons or DiI labelled gastric‐antrum projecting DMV neurons. Our results show that optogenetic stimulation of Sst‐GABA neurons results in a robust inhibition of action potentials of labelled premotor DMV neurons to the gastric‐antrum through an increase in inhibitory post‐synaptic currents. The activity of the Sst‐GABA neurons in the DMV is inhibited by both melanocortin and μ‐opioid agonists. These agonists counteract the

  11. Optogenetic and pharmacological evidence that somatostatin-GABA neurons are important regulators of parasympathetic outflow to the stomach.

    PubMed

    Lewin, Amanda E; Vicini, Stefano; Richardson, Janell; Dretchen, Kenneth L; Gillis, Richard A; Sahibzada, Niaz

    2016-05-15

    The dorsal motor nucleus of the vagus (DMV) in the brainstem consists primarily of vagal preganglionic neurons that innervate postganglionic neurons of the upper gastrointestinal tract. The activity of the vagal preganglionic neurons is predominantly regulated by GABAergic transmission in the DMV. The present findings indicate that the overwhelming GABAergic drive present at the DMV is primarily from somatostatin positive GABA (Sst-GABA) DMV neurons. Activation of both melanocortin and μ-opioid receptors at the DMV inhibits Sst-GABA DMV neurons. Sst-GABA DMV neurons may serve as integrative targets for modulating vagal output activity to the stomach. We have previously shown that local GABA signalling in the brainstem is an important determinant of vagally-mediated gastric activity. However, the neural identity of this GABA source is currently unknown. To determine this, we focused on the somatostatin positive GABA (Sst-GABA) interneuron in the dorsal motor nucleus of the vagus (DMV), a nucleus that is intimately involved in regulating gastric activity. Also of particular interest was the effect of melanocortin and μ-opioid agonists on neural activity of Sst-GABA DMV neurons because their in vivo administration in the DMV mimics GABA blockade in the nucleus. Experiments were conducted in brain slice preparation of transgenic adult Sst-IRES-Cre mice expressing tdTomato fluorescence, channelrhodopsin-2, archaerhodopsin or GCaMP3. Electrophysiological recordings were obtained from Sst-GABA DMV neurons or DiI labelled gastric-antrum projecting DMV neurons. Our results show that optogenetic stimulation of Sst-GABA neurons results in a robust inhibition of action potentials of labelled premotor DMV neurons to the gastric-antrum through an increase in inhibitory post-synaptic currents. The activity of the Sst-GABA neurons in the DMV is inhibited by both melanocortin and μ-opioid agonists. These agonists counteract the pronounced inhibitory effect of Sst-GABA neurons on

  12. Enhanced excitatory input to MCH neurons during developmental period of high food intake is mediated by GABA

    PubMed Central

    Li, Ying; van den Pol, Anthony N.

    2010-01-01

    In contrast to the local axons of GABA neurons of the cortex and hippocampus, lateral hypothalamic neurons containing melanin concentrating hormone (MCH) and GABA send long axons throughout the brain and play key roles in energy homeostasis and mental status. In adults, MCH neurons maintain a hyperpolarized membrane potential and most of the synaptic input is inhibitory. In contrast, we found that developing MCH neurons received substantially more excitatory synaptic input. Based on gramicidicin-perforated patch recordings in hypothalamic slices from MCH-GFP transgenic mice, we found that GABA was the primary excitatory synaptic transmitter in embryonic and neonatal ages up to postnatal day 10. Surprisingly, glutamate assumed only a minor excitatory role, if any. GABA plays a complex role in developing MCH neurons, with its actions conditionally dependent on a number of factors. GABA depolarization could lead to an increase in spikes either independently or in summation with other depolarizing stimuli, or alternately, depending on the relative timing of other depolarizing events, could lead to shunting inhibition. The developmental shift from depolarizing to hyperpolarizing occurred later in the dendrites than in the cell body. Early GABA depolarization was based on a Cl− dependent inward current. An interesting secondary depolarization in mature neurons that followed an initial hyperpolarization was based on a bicarbonate mechanism. Thus during the early developmental period when food consumption is high, MCH neurons are more depolarized than in the adult, and an increased level of excitatory synaptic input to these orexigenic cells is mediated by GABA. PMID:19955372

  13. Decreased agonist sensitivity of human GABA(A) receptors by an amino acid variant, isoleucine to valine, in the alpha1 subunit.

    PubMed

    Westh-Hansen, S E; Rasmussen, P B; Hastrup, S; Nabekura, J; Noguchi, K; Akaike, N; Witt, M R; Nielsen, M

    1997-06-25

    Recombinant human GABA(A) receptors were investigated in vitro by coexpression of cDNAs coding for alpha1, beta2, and gamma2 subunits in the baculovirus/Sf-9 insect cell system. We report that a single amino acid exchange (isoleucine 121 to valine 121) in the N-terminal, extracellular part of the alpha1 subunit induces a marked decrease in agonist GABA(A) receptor ligand sensitivity. The potency of muscimol and GABA to inhibit the binding of the GABA(A) receptor antagonist [3H]SR 95531 (2-(3-carboxypropyl)-3-amino-6-(4-methoxyphenyl)pyridazinium bromide) was higher in receptor complexes of alpha1(ile 121) beta2gamma2 than in those of alpha1(val 121) beta2gamma2 (IC50 values were 32-fold and 26-fold lower for muscimol and GABA, respectively). The apparent affinity of the GABA(A) receptor antagonist bicuculline methiodide to inhibit the binding of [3H]SR 95531 did not differ between the two receptor complex variants. Electrophysiological measurements of GABA induced whole-cell Cl- currents showed a ten-fold decrease in the GABA(A) receptor sensitivity of alpha1 (val 121) beta2gamma2 as compared to alpha1(ile 121) beta2gamma2 receptor complexes. Thus, a relatively small change in the primary structure of the alpha1 subunit leads to a decrease selective for GABA(A) receptor sensitivity to agonist ligands, since no changes were observed in a GABA(A) receptor antagonist affinity and benzodiazepine receptor binding.

  14. An Electrostatic Funnel in the GABA-Binding Pathway

    PubMed Central

    Lightstone, Felice C.

    2016-01-01

    The γ-aminobutyric acid type A receptor (GABAA-R) is a major inhibitory neuroreceptor that is activated by the binding of GABA. The structure of the GABAA-R is well characterized, and many of the binding site residues have been identified. However, most of these residues are obscured behind the C-loop that acts as a cover to the binding site. Thus, the mechanism by which the GABA molecule recognizes the binding site, and the pathway it takes to enter the binding site are both unclear. Through the completion and detailed analysis of 100 short, unbiased, independent molecular dynamics simulations, we have investigated this phenomenon of GABA entering the binding site. In each system, GABA was placed quasi-randomly near the binding site of a GABAA-R homology model, and atomistic simulations were carried out to observe the behavior of the GABA molecules. GABA fully entered the binding site in 19 of the 100 simulations. The pathway taken by these molecules was consistent and non-random; the GABA molecules approach the binding site from below, before passing up behind the C-loop and into the binding site. This binding pathway is driven by long-range electrostatic interactions, whereby the electrostatic field acts as a ‘funnel’ that sweeps the GABA molecules towards the binding site, at which point more specific atomic interactions take over. These findings define a nuanced mechanism whereby the GABAA-R uses the general zwitterionic features of the GABA molecule to identify a potential ligand some 2 nm away from the binding site. PMID:27119953

  15. Development of tolerance to the effects of vigabatrin (gamma-vinyl-GABA) on GABA release from rat cerebral cortex, spinal cord and retina.

    PubMed Central

    Neal, M. J.; Shah, M. A.

    1990-01-01

    1. The effects of acute and chronic vigabatrin (gamma-vinyl-GABA) (GVG) administration on gamma-aminobutyric acid (GABA) levels and release in rat cortical slices, spinal cord slices and retinas were studied. 2. GVG (250 mgkg-1 i.p.) administered to rats 18 h before death (acute administration) produced an almost 3 fold increase in GABA levels of the cortex and spinal cord and a 6 fold increase in retinal GABA. The levels of glutamate, aspartate, glycine and taurine were unaffected. 3. When GVG (250 mgkg-1 i.p.) was administered daily for 17 days (chronic administration) a similar (almost 3 fold) increase in cortical GABA occurred but the increases in spinal and retinal GABA were reduced by approximately 40%. 4. Acute administration of GVG strikingly increased the potassium-evoked release (KCl 50 mM) of GABA from all three tissues. This enhanced evoked release was reduced by about 50% in tissues taken from rats that had been chronically treated with GVG. 5. Acute administration of GVG reduced GABA-transaminase (GABA-T) activity by approximately 80% in cortex and cord and by 98% in the retina. Following the chronic administration of GVG, there was a trend for GABA-T activities to recover (significant only in cortex). Acute administration of GVG had no effect on glutamic acid decarboxylase (GAD) activity in cortex or spinal cord. However, chronic treatment resulted in significant decreases in GAD activity in both the cortex and cord (35% and 50% reduction respectively).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2379037

  16. GABA and glutamate in schizophrenia: a 7 T ¹H-MRS study.

    PubMed

    Marsman, Anouk; Mandl, René C W; Klomp, Dennis W J; Bohlken, Marc M; Boer, Vincent O; Andreychenko, Anna; Cahn, Wiepke; Kahn, René S; Luijten, Peter R; Hulshoff Pol, Hilleke E

    2014-01-01

    Schizophrenia is characterized by loss of brain volume, which may represent an ongoing pathophysiological process. This loss of brain volume may be explained by reduced neuropil rather than neuronal loss, suggesting abnormal synaptic plasticity and cortical microcircuitry. A possible mechanism is hypofunction of the NMDA-type of glutamate receptor, which reduces the excitation of inhibitory GABAergic interneurons, resulting in a disinhibition of glutamatergic pyramidal neurons. Disinhibition of pyramidal cells may result in excessive stimulation by glutamate, which in turn could cause neuronal damage or death through excitotoxicity. In this study, GABA/creatine ratios, and glutamate, NAA, creatine and choline concentrations in the prefrontal and parieto-occipital cortices were measured in 17 patients with schizophrenia and 23 healthy controls using proton magnetic resonance spectroscopy at an ultra-high magnetic field strength of 7 T. Significantly lower GABA/Cr ratios were found in patients with schizophrenia in the prefrontal cortex as compared to healthy controls, with GABA/Cr ratios inversely correlated with cognitive functioning in the patients. No significant change in the GABA/Cr ratio was found between patients and controls in the parieto-occipital cortex, nor were levels of glutamate, NAA, creatine, and choline differed in patients and controls in the prefrontal and parieto-occipital cortices. Our findings support a mechanism involving altered GABA levels distinguished from glutamate levels in the medial prefrontal cortex in schizophrenia, particularly in high functioning patients. A (compensatory) role for GABA through altered inhibitory neurotransmission in the prefrontal cortex may be ongoing in (higher functioning) patients with schizophrenia.

  17. Superficial NK1 expressing spinal dorsal horn neurones modulate inhibitory neurotransmission mediated by spinal GABA(A) receptors.

    PubMed

    Rahman, Wahida; Sikandar, Shafaq; Sikander, Shafaq; Suzuki, Rie; Hunt, Stephen P; Dickenson, Anthony H

    2007-06-04

    Lamina 1 projection neurones which express the NK1 receptor (NK1R+) drive a descending serotonergic pathway from the brainstem that enhances spinal dorsal horn neuronal activity via the facilitatory spinal 5-HT3 receptor. Selective destruction of these cells via lumbar injection of substance P-saporin (SP-SAP) attenuates pain behaviours, including mechanical and thermal hypersensitivity, which are mirrored by deficits in the evoked responses of lamina V-VI wide dynamic range (WDR) neurones to noxious stimuli. To assess whether removing the origin of this facilitatory spino-bulbo-spinal loop results in alterations in GABAergic spinal inhibitory systems, the effects of spinal bicuculline, a selective GABA(A) receptor antagonist, on the evoked neuronal responses to electrical (Abeta-, Adelta-, C-fibre, post-discharge and Input) and mechanical (brush, prod and von Frey (vF) 8 and 26 g) stimuli were measured in SAP and SP-SAP groups. In the SAP control group, bicuculline produced a significant dose related facilitation of the electrically evoked Adelta-, C-fibre, post-discharge and input neuronal responses. The evoked mechanical (prod, vF8 g and 26 g) responses were also significantly increased. Brush evoked neuronal responses in these animals were enhanced but did not reach significance. This facilitatory effect of bicuculline, however, was lost in the SP-SAP treated group. The generation of intrinsic GABAergic transmission in the spinal cord appears dependent on NK1 bearing neurons, yet despite the loss of GABAergic inhibitory controls after SP-SAP treatment, the net effect is a decrease in spinal cord excitability. Thus activation of these cells predominantly drives facilitation.

  18. Spontaneous Seizures and Altered Gene Expression in GABA Signaling Pathways in a mind bomb Mutant Zebrafish

    PubMed Central

    Hortopan, Gabriela A.; Dinday, Matthew T.; Baraban, Scott C.

    2010-01-01

    Disruption of E3 ubiquitin ligase activity in immature zebrafish mind bomb mutants, leads to a failure in Notch signaling, excessive numbers of neurons, and depletion of neural progenitor cells. This neurogenic phenotype is associated with defects in neural patterning and brain development. Because developmental brain abnormalities are recognized as an important feature of childhood neurological disorders such as epilepsy and autism, we determined whether zebrafish mutants with grossly abnormal brain structure exhibit spontaneous electrical activity that resembles the long-duration, high-amplitude multi-spike discharges reported in immature zebrafish exposed to convulsant drugs. Electrophysiological recordings from agar immobilized mind bomb mutants at three days postfertilization (dpf) confirmed the occurrence of electrographic seizure activity; seizure-like behaviors were also noted during locomotion video tracking of freely behaving mutants. To identify genes differentially expressed in the mind bomb mutant and provide insight into molecular pathways that may mediate these epileptic phenotypes, a transcriptome analysis was performed using microarray. Interesting candidate genes were further analyzed using conventional reverse transcriptasepolymerase chain reaction (RT-PCR) and real-time quantitative PCR (qPCR), as well as whole-mount in situ hybridization. Approximately 150 genes, some implicated in development, transcription, cell metabolism and signal transduction, are differentially regulated including down-regulation of several genes necessary for GABA-mediated signaling. These findings identify a collection of gene transcripts that may be responsible for the abnormal electrical discharge and epileptic activities observed in a mind bomb zebrafish mutant. This work may have important implications for neurological and neurodevelopmental disorders associated with mutations in ubiquitin ligase activity. Notch is an essential component of an evolutionarily

  19. Responses to GABA(A) receptor activation are altered in NTS neurons isolated from chronic hypoxic rats.

    PubMed

    Tolstykh, Gleb; Belugin, Sergei; Mifflin, Steve

    2004-04-23

    The inhibitory amino acid GABA is released within the nucleus of the solitary tract (NTS) during hypoxia and modulates the respiratory response to hypoxia. To determine if responses of NTS neurons to activation of GABA(A) receptors are altered following exposure to chronic hypoxia, GABA(A) receptor-evoked whole cell currents were measured in enzymatically dispersed NTS neurons from normoxic and chronic hypoxic rats. Chronic hypoxic rats were exposed to 10% O(2) for 9-12 days. Membrane capacitance was the same in neurons from normoxic (6.9+/-0.5 pF, n=16) and hypoxic (6.3+/-0.5 pF, n=15) rats. The EC(50) for peak GABA-evoked current density was significantly greater in neurons from hypoxic (21.7+/-2.2 microM) compared to normoxic rats (12.2+/-0.9 microM) (p<0.001). Peak and 5-s adapted GABA currents evoked by 1, 3 and 10 microM were greater in neurons from normoxic compared to hypoxic rats (p<0.05) whereas peak and 5-s adapted responses to 30 and 100 microM GABA were not different comparing normoxic to hypoxic rats. Desensitization of GABA(A)-evoked currents was observed at concentrations greater than 3 microM and, measured as the ratio of the current 5 s after the onset of 100 microM GABA application to the peak GABA current, was the same in neurons from normoxic (0.37+/-0.03) and hypoxic rats (0.33+/-0.04). Reduced sensitivity to GABA(A) receptor-evoked inhibition in chronic hypoxia could influence chemoreceptor afferent integration by NTS neurons.

  20. Determination of GABA and vigabatrin in human plasma by a rapid and simple HPLC method: correlation between clinical response to vigabatrin and increase in plasma GABA.

    PubMed

    Löscher, W; Fassbender, C P; Gram, L; Gramer, M; Hörstermann, D; Zahner, B; Stefan, H

    1993-03-01

    The novel antiepileptic drug vigabatrin (Sabril) acts by inhibiting degradation of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), increasing the GABA concentrations in the brain. Because the GABA degrading enzyme GABA aminotransferase (GABA-T) is also present in peripheral tissues, including blood platelets, measurement of plasma GABA levels might be a useful indication of the pharmacological response to vigabatrin during therapeutic monitoring. However, because of the very low concentrations of GABA in plasma, the few methods available for plasma GABA analysis are time-consuming, difficult to perform and/or not selective enough because of potential interference with other plasma constituents. In the present study, a rapid, selective and sensitive amino acid analysis HPLC method has been developed for plasma GABA determination with fluorescence detection, using o-phthaldialdehyde as a precolumn derivatizing agent. By employing a 3 microns particle size reversed-phase column and a multi-step gradient system of two solvents, the very low endogenous concentration of GABA in human plasma could be reproducibly quantitated without interference of other endogenous compounds. Incubation of human plasma samples with GABA degrading enzyme(s) resulted in an almost total loss of the GABA peak, thus demonstrating the specificity of the method for GABA analysis. In addition to GABA and other endogenous amino acids, the HPLC method could be used to quantitate plasma levels of vigabatrin. Thus, this improved HPLC amino acid assay might be used to examine whether concomitant monitoring of plasma GABA and vigabatrin is useful for clinical purposes. This was examined in 20 epileptic patients undergoing chronic treatment with vigabatrin. The average plasma GABA level of these 20 patients did not differ significantly from non-epileptic controls. However, when epileptic patients were subdivided according to their clinical response to vigabatrin, vigabatrin responders

  1. A molecular characterization of the agonist binding site of a nematode cys-loop GABA receptor

    PubMed Central

    Kaji, Mark D; Kwaka, Ariel; Callanan, Micah K; Nusrat, Humza; Desaulniers, Jean-Paul; Forrester, Sean G

    2015-01-01

    Background and Purpose Cys-loop GABA receptors represent important targets for human chemotherapeutics and insecticides and are potential targets for novel anthelmintics (nematicides). However, compared with insect and mammalian receptors, little is known regarding the pharmacological characteristics of nematode Cys-loop GABA receptors. Here we have investigated the agonist binding site of the Cys-loop GABA receptor UNC-49 (Hco-UNC-49) from the parasitic nematode Haemonchus contortus. Experimental Approach We used two-electrode voltage-clamp electrophysiology to measure channel activation by classical GABA receptor agonists on Hco-UNC-49 expressed in Xenopus laevis oocytes, along with site-directed mutagenesis and in silico homology modelling. Key Results The sulphonated molecules P4S and taurine had no effect on Hco-UNC-49. Other classical Cys-loop GABAA receptor agonists tested on the Hco-UNC-49B/C heteromeric channel had a rank order efficacy of GABA > trans-4-aminocrotonic acid > isoguvacine > imidazole-4-acetic acid (IMA) > (R)-(−)-4-amino-3-hydroxybutyric acid [R(−)-GABOB] > (S)-(+)-4-amino-3-hydroxybutyric acid [S(+)-GABOB] > guanidinoacetic acid > isonipecotic acid > 5-aminovaleric acid (DAVA) (partial agonist) > β-alanine (partial agonist). In silico ligand docking revealed some variation in binding between agonists. Mutagenesis of a key serine residue in binding loop C to threonine had minimal effects on GABA and IMA but significantly increased the maximal response to DAVA and decreased twofold the EC50 for R(−)- and S(+)-GABOB. Conclusions and Implications The pharmacological profile of Hco-UNC-49 differed from that of vertebrate Cys-loop GABA receptors and insect resistance to dieldrin receptors, suggesting differences in the agonist binding pocket. These findings could be exploited to develop new drugs that specifically target GABA receptors of parasitic nematodes. PMID:25850584

  2. Production of gaba (γ – Aminobutyric acid) by microorganisms: a review

    PubMed Central

    Dhakal, Radhika; Bajpai, Vivek K.; Baek, Kwang-Hyun

    2012-01-01

    GABA (γ-aminobutyric acid) is a four carbon non-protein amino acid that is widely distributed in plants, animals and microorganisms. As a metabolic product of plants and microorganisms produced by the decarboxylation of glutamic acid, GABA functions as an inhibitory neurotransmitter in the brain that directly affects the personality and the stress management. A wide range of traditional foods produced by microbial fermentation contain GABA, in which GABA is safe and eco-friendly, and also has the possibility of providing new health-benefited products enriched with GABA. Synthesis of GABA is catalyzed by glutamate decarboxylase, therefore, the optimal fermentation condition is mainly based on the biochemical properties of the enzyme. Major GABA producing microorganisms are lactic acid bacteria (LAB), which make food spoilage pathogens unable to grow and act as probiotics in the gastrointestinal tract. The major factors affecting the production of GABA by microbial fermentation are temperature, pH, fermentation time and different media additives, therefore, these factors are summarized to provide the most up-dated information for effective GABA synthesis. There has been a huge accumulation of knowledge on GABA application for human health accompanying with a demand on natural GABA supply. Only the GABA production by microorganisms can fulfill the demand with GABA-enriched health beneficial foods. PMID:24031948

  3. The anti-spasticity drug baclofen alleviates collagen-induced arthritis and regulates dendritic cells.

    PubMed

    Huang, Shichao; Mao, Jianxin; Wei, Bin; Pei, Gang

    2015-07-01

    Baclofen is used clinically as a drug that treats spasticity, which is a syndrome characterized by excessive contraction of the muscles and hyperflexia in the central nervous system (CNS), by activating GABA(B) receptors (GABA(B)Rs). Baclofen was recently reported to desensitize chemokine receptors and to suppress inflammation through the activation of GABA(B)Rs. GABA(B)Rs are expressed in various immune cells, but the functions of these receptors in autoimmune diseases remain largely unknown. In this study, we investigated the effects of baclofen in murine collagen-induced arthritis (CIA). Oral administration of baclofen alleviated the clinical development of CIA, with a reduced number of IL-17-producing T helper 17 (T(H)17) cells. In addition, baclofen treatment suppressed dendritic cell (DC)-primed T(H)17 cell differentiation by reducing the production of IL-6 by DCs in vitro. Furthermore, the pharmacological and genetic blockade of GABA(B)Rs in DCs weakened the effects of baclofen, indicating that GABA(B)Rs are the molecular targets of baclofen on DCs. Thus, our findings revealed a potential role for baclofen in the treatment of CIA, as well as a previously unknown signaling pathway that regulates DC function. © 2014 Wiley Periodicals, Inc.

  4. [Influence of exogenous gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid contents in roots of melon seedling under hypoxia stress].

    PubMed

    Wang, Chun-Yan; Li, Jing-Rui; Xia, Qing-Ping; Wu, Xiao-Lei; Gao, Hong-Bo

    2014-07-01

    This paper investigated the influence of gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid content under hypoxia stress by accurately controlling the level of dissolved oxygen in hydroponics, using the roots of melon 'Xiyu 1' seedlings as the test material. The results showed that compared with the control, the growth of roots was inhibited seriously under hypoxia stress. Meanwhile, the hypoxia-treated roots had significantly higher activities of glutamate decarboxylase (GAD), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS), alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the contents of GABA, pyruvic acid, alanine (Ala) and aspartic acid (Asp). But the contents of glutamic acid (Glu) and alpha-keto glutaric acid in roots under hypoxia stress was obviously lower than those of the control. Exogenous treatment with GABA alleviated the inhibition effect of hypoxia stress on root growth, which was accompanied by an increase in the contents of endogenous GABA, Glu, alpha-keto glutaric acid and Asp. Furthermore, under hypoxia stress, the activities of GAD, GDH, GOGAT, GS, ALT, AST as well as the contents of pyruvic acid and Ala significantly decreased in roots treated with GABA. However, adding GABA and viny-gamma-aminobutyric acid (VGB) reduced the alleviation effect of GABA on melon seedlings under hypoxia stress. The results suggested that absorption of GABA by roots could alleviate the injury of hypoxia stress to melon seedlings. This meant that GABA treatment allows the normal physiological metabolism under hypoxia by inhibiting the GAD activity through feedback and maintaining higher Glu content as well as the bal- ance of carbon and nitrogen.

  5. Occipital GABA correlates with cognitive failures in daily life.

    PubMed

    Sandberg, Kristian; Blicher, Jakob Udby; Dong, Mia Yuan; Rees, Geraint; Near, Jamie; Kanai, Ryota

    2014-02-15

    The brain has limited capacity, and so selective attention enhances relevant incoming information while suppressing irrelevant information. This process is not always successful, and the frequency of such cognitive failures varies to a large extent between individuals. Here we hypothesised that individual differences in cognitive failures might be reflected in inhibitory processing in the sensory cortex. To test this hypothesis, we measured GABA in human visual cortex using MR spectroscopy and found a negative correlation between occipital GABA (GABA+/Cr ratio) and cognitive failures as measured by an established cognitive failures questionnaire (CFQ). For a second site in parietal cortex, no correlation between CFQ score and GABA+/Cr ratio was found, thus establishing the regional specificity of the link between occipital GABA and cognitive failures. We further found that grey matter volume in the left superior parietal lobule (SPL) correlated with cognitive failures independently from the impact of occipital GABA and together, occipital GABA and SPL grey matter volume statistically explained around 50% of the individual variability in daily cognitive failures. We speculate that the amount of GABA in sensory areas may reflect the potential capacity to selectively suppress irrelevant information already at the sensory level, or alternatively that GABA influences the specificity of neural representations in visual cortex thus improving the effectiveness of successful attentional modulation. © 2013. Published by Elsevier Inc. All rights reserved.

  6. Perisylvian GABA levels in schizophrenia and bipolar disorder.

    PubMed

    Atagün, Murat İlhan; Şıkoğlu, Elif Muazzez; Soykan, Çağlar; Serdar Süleyman, Can; Ulusoy-Kaymak, Semra; Çayköylü, Ali; Algın, Oktay; Phillips, Mary Louise; Öngür, Dost; Moore, Constance Mary

    2017-01-10

    The aim of this study is to measure GABA levels of perisylvian cortices in schizophrenia and bipolar disorder patients, using proton magnetic resonance spectroscopy ( 1 H-MRS). Patients with schizophrenia (n=25), bipolar I disorder (BD-I; n=28) and bipolar II disorder (BD-II; n=20) were compared with healthy controls (n=30). 1 H-MRS data was acquired using a Siemens 3T whole body scanner to quantify right and left perisylvian structures' (including superior temporal lobes) GABA levels. Right perisylvian GABA values differed significantly between groups [χ 2 =9.62, df: 3, p=0.022]. GABA levels were significantly higher in the schizophrenia group compared with the healthy control group (p=0.002). Furthermore, Chlorpromazine equivalent doses of antipsychotics correlated with right hemisphere GABA levels (r 2 =0.68, p=0.006, n=33). GABA levels are elevated in the right hemisphere in patients with schizophrenia in comparison to bipolar disorder and healthy controls. The balance between excitatory and inhibitory controls over the cortical circuits may have direct relationship with GABAergic functions in auditory cortices. In addition, GABA levels may be altered by brain regions of interest, psychotropic medications, and clinical stage in schizophrenia and bipolar disorder. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Perisylvian GABA levels in schizophrenia and bipolar disorder

    PubMed Central

    ATAGÜN, Murat İlhan; ŞIKOĞLU, Elif Muazzez; SOYKAN, Çağlar; CAN, Serdar Süleyman; ULUSOY-KAYMAK, Semra; ÇAYKÖYLÜ, Ali; ALGIN, Oktay; PHILLIPS, Mary Louise; ÖNGÜR, Dost; MOORE, Constance Mary

    2016-01-01

    The aim of this study is to measure GABA levels of perisylvian cortices in schizophrenia and bipolar disorder patients, using proton magnetic resonance spectroscopy (1H-MRS). Patients with schizophrenia (n=25), bipolar I disorder (BD-I; n=28) and bipolar II disorder (BD-II; n=20) were compared with healthy controls (n=30). 1H-MRS data was acquired using a Siemens 3 Tesla whole body scanner to quantify right and left perisylvian structures’ (including superior temporal lobes) GABA levels. Right perisylvian GABA values differed significantly between groups [χ2=9.62, df: 3, p = 0.022]. GABA levels were significantly higher in the schizophrenia group compared with the healthy control group (p=0.002). Furthermore, Chlorpromazine equivalent doses of antipsychotics correlated with right hemisphere GABA levels (r2=0.68, p=0.006, n=33). GABA levels are elevated in the right hemisphere in patients with schizophrenia in comparison to bipolar disorder and healthy controls. The balance between excitatory and inhibitory controls over the cortical circuits may have direct relationship with GABAergic functions in auditory cortices. In addition, GABA levels may be altered by brain regions of interest, psychotropic medications, and clinical stage in schizophrenia and bipolar disorder. PMID:27890741

  8. Isolation and chemical characterization of agelaiatoxin8 (AvTx8) from Agelaia vicina wasp venom and its biological effects on GABA neurotransmission.

    PubMed

    Pizzo, Andrea B; Beleboni, Renê O; Gomes Carolino, Ruither O; de Oliveira, Luciana; Miranda, Antonio; Coutinho-Netto, Joaquim; Fontana, Andréia C K; Dos Santos, Wagner Ferreira

    2017-10-01

    Arthropod venoms are sources of molecules that may be useful tools to investigate molecular mechanisms of putative new medicines and laboratory drugs. Here we show the effects of the compound agelaiatoxin-8 (AVTx8), isolated from Agelaia vicina venom, on γ-aminobutyric acid (GABA) neurotransmission in rat brain synaptosomes. Analysis reveals that AvTx8 is composed by 14 amino acid residues with a molecular weight (MW) of 1567 Da. AvTx8 increased GABA release and inhibited GABA uptake in synaptosomes from rat cerebral cortex. AvTx8 inhibited GABA uptake and increased GABA release in the presence of Ca + , Na + , and K + channel blockers, suggesting that it acts directly on GABA transporters. In addition, AvTx8 significantly decreases GABA binding in synaptic membranes from rat brain cortex, suggesting that it also modulates the activity of GABA receptors. Moreover, AvTx8 decreased GAT-1- and GAT-3-mediated GABA uptake in transfected COS-7 cells. Accordingly, we suggest that AvTx8 modulates GABA neurotransmission and might provide a novel entry point for identifying a new class of GABA-modulating neuroprotective drugs. © 2017 Wiley Periodicals, Inc.

  9. Neuron-specific feeding RNAi in C. elegans and its use in a screen for essential genes required for GABA neuron function.

    PubMed

    Firnhaber, Christopher; Hammarlund, Marc

    2013-11-01

    Forward genetic screens are important tools for exploring the genetic requirements for neuronal function. However, conventional forward screens often have difficulty identifying genes whose relevant functions are masked by pleiotropy. In particular, if loss of gene function results in sterility, lethality, or other severe pleiotropy, neuronal-specific functions cannot be readily analyzed. Here we describe a method in C. elegans for generating cell-specific knockdown in neurons using feeding RNAi and its application in a screen for the role of essential genes in GABAergic neurons. We combine manipulations that increase the sensitivity of select neurons to RNAi with manipulations that block RNAi in other cells. We produce animal strains in which feeding RNAi results in restricted gene knockdown in either GABA-, acetylcholine-, dopamine-, or glutamate-releasing neurons. In these strains, we observe neuron cell-type specific behavioral changes when we knock down genes required for these neurons to function, including genes encoding the basal neurotransmission machinery. These reagents enable high-throughput, cell-specific knockdown in the nervous system, facilitating rapid dissection of the site of gene action and screening for neuronal functions of essential genes. Using the GABA-specific RNAi strain, we screened 1,320 RNAi clones targeting essential genes on chromosomes I, II, and III for their effect on GABA neuron function. We identified 48 genes whose GABA cell-specific knockdown resulted in reduced GABA motor output. This screen extends our understanding of the genetic requirements for continued neuronal function in a mature organism.

  10. Glial GABA, synthesized by monoamine oxidase B, mediates tonic inhibition

    PubMed Central

    Yoon, Bo-Eun; Woo, Junsung; Chun, Ye-Eun; Chun, Heejung; Jo, Seonmi; Bae, Jin Young; An, Heeyoung; Min, Joo Ok; Oh, Soo-Jin; Han, Kyung-Seok; Kim, Hye Yun; Kim, Taekeun; Kim, Young Soo; Bae, Yong Chul; Lee, C Justin

    2014-01-01

    GABA is the major inhibitory transmitter in the brain and is released not only from a subset of neurons but also from glia. Although neuronal GABA is well known to be synthesized by glutamic acid decarboxylase (GAD), the source of glial GABA is unknown. After estimating the concentration of GABA in Bergmann glia to be around 5–10 mm by immunogold electron microscopy, we demonstrate that GABA production in glia requires MAOB, a key enzyme in the putrescine degradation pathway. In cultured cerebellar glia, both Ca2+-induced and tonic GABA release are significantly reduced by both gene silencing of MAOB and the MAOB inhibitor selegiline. In the cerebellum and striatum of adult mice, general gene silencing, knock out of MAOB or selegiline treatment resulted in elimination of tonic GABA currents recorded from granule neurons and medium spiny neurons. Glial-specific rescue of MAOB resulted in complete rescue of tonic GABA currents. Our results identify MAOB as a key synthesizing enzyme of glial GABA, which is released via bestrophin 1 (Best1) channel to mediate tonic inhibition in the brain. PMID:25239459

  11. Elevating Endogenous GABA Levels with GAT-1 Blockade Modulates Evoked but Not Induced Responses in Human Visual Cortex

    PubMed Central

    Muthukumaraswamy, Suresh D; Myers, Jim F M; Wilson, Sue J; Nutt, David J; Hamandi, Khalid; Lingford-Hughes, Anne; Singh, Krish D

    2013-01-01

    The electroencephalographic/magnetoencephalographic (EEG/MEG) signal is generated primarily by the summation of the postsynaptic currents of cortical principal cells. At a microcircuit level, these glutamatergic principal cells are reciprocally connected to GABAergic interneurons. Here we investigated the relative sensitivity of visual evoked and induced responses to altered levels of endogenous GABAergic inhibition. To do this, we pharmacologically manipulated the GABA system using tiagabine, which blocks the synaptic GABA transporter 1, and so increases endogenous GABA levels. In a single-blinded and placebo-controlled crossover study of 15 healthy participants, we administered either 15 mg of tiagabine or a placebo. We recorded whole-head MEG, while participants viewed a visual grating stimulus, before, 1, 3 and 5 h post tiagabine ingestion. Using beamformer source localization, we reconstructed responses from early visual cortices. Our results showed no change in either stimulus-induced gamma-band amplitude increases or stimulus-induced alpha amplitude decreases. However, the same data showed a 45% reduction in the evoked response component at ∼80 ms. These data demonstrate that, in early visual cortex the evoked response shows a greater sensitivity compared with induced oscillations to pharmacologically increased endogenous GABA levels. We suggest that previous studies correlating GABA concentrations as measured by magnetic resonance spectroscopy to gamma oscillation frequency may reflect underlying variations such as interneuron/inhibitory synapse density rather than functional synaptic GABA concentrations. PMID:23361120

  12. The insecticide fipronil and its metabolite fipronil sulphone inhibit the rat alpha1beta2gamma2L GABA(A) receptor.

    PubMed

    Li, P; Akk, G

    2008-11-01

    Fipronil is the active ingredient in a number of widely used insecticides. Human exposure to fipronil leads to symptoms (headache, nausea and seizures) typically associated with the antagonism of GABA(A) receptors in the brain. In this study, we have examined the modulation of the common brain GABA(A) receptor subtype by fipronil and its major metabolite, fipronil sulphone. Whole-cell and single-channel recordings were made from HEK 293 cells transiently expressing rat alpha1beta2gamma2L GABA(A) receptors. The major effect of fipronil was to increase the rate of current decay in macroscopic recordings. In single-channel recordings, the presence of fipronil resulted in shorter cluster durations without affecting the intracluster open and closed time distributions or the single-channel conductance. The alpha1V256S mutation, previously shown alleviate channel inhibition by inhibitory steroids and several insecticides, had a relatively small effect on channel block by fipronil. The mode of action of fipronil sulphone was similar to that of its parent compound but the metabolite was less potent at inhibiting the alpha1beta2gamma2L receptor. We conclude that exposure to fipronil induces accumulation of receptors in a novel, long-lived blocked state. This process proceeds in parallel with and independently of, channel desensitization. The lower potency of fipronil sulphone indicates that the conversion serves as a detoxifying process in mammalian brain.

  13. GABA production and structure of gadB/gadC genes in Lactobacillus and Bifidobacterium strains from human microbiota.

    PubMed

    Yunes, R A; Poluektova, E U; Dyachkova, M S; Klimina, K M; Kovtun, A S; Averina, O V; Orlova, V S; Danilenko, V N

    2016-12-01

    Gamma-amino butyric acid (GABA) is an active biogenic substance synthesized in plants, fungi, vertebrate animals and bacteria. Lactic acid bacteria are considered the main producers of GABA among bacteria. GABA-producing lactobacilli are isolated from food products such as cheese, yogurt, sourdough, etc. and are the source of bioactive properties assigned to those foods. The ability of human-derived lactobacilli and bifidobacteria to synthesize GABA remains poorly characterized. In this paper, we screened our collection of 135 human-derived Lactobacillus and Bifidobacterium strains for their ability to produce GABA from its precursor monosodium glutamate. Fifty eight strains were able to produce GABA. The most efficient GABA-producers were Bifidobacterium strains (up to 6 g/L). Time profiles of cell growth and GABA production as well as the influence of pyridoxal phosphate on GABA production were studied for L. plantarum 90sk, L. brevis 15f, B. adolescentis 150 and B. angulatum GT102. DNA of these strains was sequenced; the gadB and gadC genes were identified. The presence of these genes was analyzed in 14 metagenomes of healthy individuals. The genes were found in the following genera of bacteria: Bacteroidetes (Bacteroides, Parabacteroides, Alistipes, Odoribacter, Prevotella), Proteobacterium (Esherichia), Firmicutes (Enterococcus), Actinobacteria (Bifidobacterium). These data indicate that gad genes as well as the ability to produce GABA are widely distributed among lactobacilli and bifidobacteria (mainly in L. plantarum, L. brevis, B. adolescentis, B. angulatum, B. dentium) and other gut-derived bacterial species. Perhaps, GABA is involved in the interaction of gut microbiota with the macroorganism and the ability to synthesize GABA may be an important feature in the selection of bacterial strains - psychobiotics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Enhanced excitatory input to melanin concentrating hormone neurons during developmental period of high food intake is mediated by GABA.

    PubMed

    Li, Ying; van den Pol, Anthony N

    2009-12-02

    In contrast to the local axons of GABA neurons of the cortex and hippocampus, lateral hypothalamic neurons containing melanin concentrating hormone (MCH) and GABA send long axons throughout the brain and play key roles in energy homeostasis and mental status. In adults, MCH neurons maintain a hyperpolarized membrane potential and most of the synaptic input is inhibitory. In contrast, we found that developing MCH neurons received substantially more excitatory synaptic input. Based on gramicidin-perforated patch recordings in hypothalamic slices from MCH-green fluorescent protein transgenic mice, we found that GABA was the primary excitatory synaptic transmitter in embryonic and neonatal ages up to postnatal day 10. Surprisingly, glutamate assumed only a minor excitatory role, if any. GABA plays a complex role in developing MCH neurons, with its actions conditionally dependent on a number of factors. GABA depolarization could lead to an increase in spikes either independently or in summation with other depolarizing stimuli, or alternately, depending on the relative timing of other depolarizing events, could lead to shunting inhibition. The developmental shift from depolarizing to hyperpolarizing occurred later in the dendrites than in the cell body. Early GABA depolarization was based on a Cl(-)-dependent inward current. An interesting secondary depolarization in mature neurons that followed an initial hyperpolarization was based on a bicarbonate mechanism. Thus during the early developmental period when food consumption is high, MCH neurons are more depolarized than in the adult, and an increased level of excitatory synaptic input to these orexigenic cells is mediated by GABA.

  15. Effect of GABA agonists and GABA-A receptor modulators on cocaine- and food-maintained responding and cocaine discrimination in rats.

    PubMed

    Barrett, Andrew C; Negus, S Stevens; Mello, Nancy K; Caine, S Barak

    2005-11-01

    Recent studies indicate that GABAergic ligands modulate abuse-related effects of cocaine. The goal of this study was to evaluate the effects of a mechanistically diverse group of GABAergic ligands on the discriminative stimulus and reinforcing effects of cocaine in rats. One group of rats was trained to discriminate 5.6 mg/kg cocaine from saline in a two-lever, food-reinforced, drug discrimination procedure. In two other groups, responding was maintained by cocaine (0-3.2 mg/kg/injection) or liquid food (0-100%) under a fixed ratio 5 schedule. Six GABA agonists were tested: the GABA-A receptor agonist muscimol, the GABA-B receptor agonist baclofen, the GABA transaminase inhibitor gamma-vinyl-GABA (GVG), and three GABA-A receptor modulators (the barbiturate pentobarbital, the high-efficacy benzodiazepine midazolam, and the low-efficacy benzodiazepine enazenil). When tested alone, none of the compounds substituted fully for the discriminative stimulus effects of cocaine. As acute pretreatments, select doses of midazolam and pentobarbital produced 2.2- to 3.6-fold rightward shifts in the cocaine dose-effect function. In contrast, muscimol, baclofen, GVG, and enazenil failed to alter the discriminative stimulus effects of cocaine. In assays of cocaine- and food-maintained responding, midazolam and pentobarbital decreased cocaine self-administration at doses 9.6- and 3.3-fold lower, respectively, than those that decreased food-maintained responding. In contrast, muscimol, baclofen, and GVG decreased cocaine self-administration at doses that also decreased food-maintained responding. Enazenil failed to alter cocaine self-administration. Together with previous studies, these data suggest that among mechanistically diverse GABA agonists, high-efficacy GABA-A modulators may be the most effective for modifying the abuse-related effects of cocaine.

  16. Influence of GABA and GABA-producing Lactobacillus brevis DPC 6108 on the development of diabetes in a streptozotocin rat model.

    PubMed

    Marques, T M; Patterson, E; Wall, R; O'Sullivan, O; Fitzgerald, G F; Cotter, P D; Dinan, T G; Cryan, J F; Ross, R P; Stanton, C

    2016-06-01

    The aim of this study was to investigate if dietary administration of γ-aminobutyric acid (GABA)-producing Lactobacillus brevis DPC 6108 and pure GABA exert protective effects against the development of diabetes in streptozotocin (STZ)-induced diabetic Sprague Dawley rats. In a first experiment, healthy rats were divided in 3 groups (n=10/group) receiving placebo, 2.6 mg/kg body weight (bw) pure GABA or L. brevis DPC 6108 (~10(9)microorganisms). In a second experiment, rats (n=15/group) were randomised to five groups and four of these received an injection of STZ to induce type 1 diabetes. Diabetic and non-diabetic controls received placebo [4% (w/v) yeast extract in dH2O], while the other three diabetic groups received one of the following dietary supplements: 2.6 mg/kg bw GABA (low GABA), 200 mg/kg bw GABA (high GABA) or ~10(9) L. brevis DPC 6108. L. brevis DPC 6108 supplementation was associated with increased serum insulin levels (P<0.05), but did not alter other metabolic markers in healthy rats. Diabetes induced by STZ injection decreased body weight (P<0.05), increased intestinal length (P<0.05) and stimulated water and food intake. Insulin was decreased (P<0.05), whereas glucose was increased (P<0.001) in all diabetic groups, compared with non-diabetic controls. A decrease (P<0.01) in glucose levels was observed in diabetic rats receiving L. brevis DPC 6108, compared with diabetic-controls. Both the composition and diversity of the intestinal microbiota were affected by diabetes. Microbial diversity in diabetic rats supplemented with low GABA was not reduced (P>0.05), compared with non-diabetic controls while all other diabetic groups displayed reduced diversity (P<0.05). L. brevis DPC 6108 attenuated hyperglycaemia induced by diabetes but additional studies are needed to understand the mechanisms involved in this reduction.

  17. Delta Subunit-Containing Gamma-Aminobutyric Acid A Receptor Disinhibits Lateral Amygdala and Facilitates Fear Expression in Mice.

    PubMed

    Liu, Zhi-Peng; He, Qing-Hai; Pan, Han-Qing; Xu, Xiao-Bin; Chen, Wen-Bing; He, Ye; Zhou, Jin; Zhang, Wen-Hua; Zhang, Jun-Yu; Ying, Xiao-Ping; Han, Ren-Wen; Li, Bao-Ming; Gao, Tian-Ming; Pan, Bing-Xing

    2017-06-15

    Maintaining gamma-aminobutyric acidergic (GABAergic) inhibition in the amygdala within a physiological range is critical for the appropriate expression of emotions such as fear and anxiety. The synaptic GABA type A receptor (GABA A R) is generally known to mediate the primary component of amygdala inhibition and prevent inappropriate expression of fear. However, little is known about the contribution of the extrasynaptic GABA A R to amygdala inhibition and fear. By using mice expressing green fluorescent protein in interneurons (INs) and lacking the δ subunit-containing GABA A R (GABA A (δ)R), which is exclusively situated in the extrasynaptic membrane, we systematically investigated the role of GABA A (δ)R in regulating inhibition in the lateral amygdala (LA) and fear learning using the combined approaches of immunohistochemistry, electrophysiology, and behavior. In sharp contrast to the established role of synaptic GABA A R in mediating LA inhibition, we found that either pharmacological or physiological recruitment of GABA A (δ)R resulted in the weakening of GABAergic transmission onto projection neurons in LA while leaving the glutamatergic transmission unaltered, suggesting disinhibition by GABA A (δ)R. The disinhibition arose from IN-specific expression of GABA A (δ)R with its activation decreasing the input resistance of local INs and suppressing their activation. Genetic deletion of GABA A (δ)R attenuated its role in suppressing LA INs and disinhibiting LA. Importantly, the GABA A (δ)R facilitated long-term potentiation in sensory afferents to LA and permitted the expression of learned fear. Our findings suggest that GABA A (δ)R serves as a brake rather than a mediator of GABAergic inhibition in LA. The disinhibition by GABA A (δ)R may help to prevent excessive suppression of amygdala activity and thus ensure the expression of emotion. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  18. Under stressful conditions activation of the ionotropic P2X7 receptor differentially regulates GABA and glutamate release from nerve terminals of the rat cerebral cortex.

    PubMed

    Barros-Barbosa, Aurora R; Oliveira, Ângela; Lobo, M Graça; Cordeiro, J Miguel; Correia-de-Sá, Paulo

    2018-01-01

    γ-Aminobutyric acid (GABA) and glutamate (Glu) are the main inhibitory and excitatory neurotransmitters in the central nervous system (CNS), respectively. Fine tuning regulation of extracellular levels of these amino acids is essential for normal brain activity. Recently, we showed that neocortical nerve terminals from patients with epilepsy express higher amounts of the non-desensitizing ionotropic P2X7 receptor. Once activated by ATP released from neuronal cells, the P2X7 receptor unbalances GABAergic vs. glutamatergic neurotransmission by differentially interfering with GABA and Glu uptake. Here, we investigated if activation of the P2X7 receptor also affects [ 3 H]GABA and [ 14 C]Glu release measured synchronously from isolated nerve terminals (synaptosomes) of the rat cerebral cortex. Data show that activation of the P2X7 receptor consistently increases [ 14 C]Glu over [ 3 H]GABA release from cortical nerve terminals, but the GABA/Glu ratio depends on extracellular Ca 2+ concentrations. While the P2X7-induced [ 3 H]GABA release is operated by a Ca 2+ -dependent pathway when external Ca 2+ is available, this mechanism shifts towards the reversal of the GAT1 transporter in low Ca 2+ conditions. A different scenario is verified regarding [ 14 C]Glu outflow triggered by the P2X7 receptor, since the amino acid seems to be consistently released through the recruitment of connexin-containing hemichannels upon P2X7 activation, both in the absence and in the presence of external Ca 2+ . Data from this study add valuable information suggesting that ATP, via P2X7 activation, not only interferes with the high-affinity uptake of GABA and Glu but actually favors the release of these amino acids through distinct molecular mechanisms amenable to differential therapeutic control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Effects of new fluorinated analogues of GABA, pregabalin bioisosters, on the ambient level and exocytotic release of [3H]GABA from rat brain nerve terminals.

    PubMed

    Borisova, T; Pozdnyakova, N; Shaitanova, E; Gerus, I; Dudarenko, M; Haufe, G; Kukhar, V

    2017-01-15

    Recently, we have shown that new fluorinated analogues of γ-aminobutyric acid (GABA), bioisosters of pregabalin (β-i-Bu-GABA), i.e. β-polyfluoroalkyl-GABAs (FGABAs), with substituents: β-CF 3 -β-OH (1), β-CF 3 (2); β-CF 2 CF 2 H (3), are able to increase the initial rate of [ 3 H]GABA uptake by isolated rat brain nerve terminals (synaptosomes), and this effect is higher than that of pregabalin. So, synthesized FGABAs are structural but not functional analogues of GABA. Herein, we assessed the effects of synthesized FGABAs (100μM) on the ambient level and exocytotic release of [ 3 H]GABA in nerve terminals and compared with those of pregabalin (100μM). It was shown that FGABAs 1-3 did not influence the ambient level of [ 3 H]GABA in the synaptosomal preparations, and this parameter was also not altered by pregabalin. During blockage of GABA transporters GAT1 by specific inhibitor NO-711, FGABAs and pregabalin also did not change ambient [ 3 H]GABA in synaptosomal preparations. Exocytotic release of [ 3 H]GABA from synaptosomes decreased in the presence of FGABAs 1-3 and pregabalin, and the effects of FGABAs 1 &3 were more significant than those of FGABAs 2 and pregabalin. FGABAs 1-3/pregabalin-induced decrease in exocytotic release of [ 3 H]GABA from synaptosomes was not a result of changes in the potential of the plasma membrane. Therefore, new synthesized FGABAs 1 &3 were able to decrease exocytotic release of [ 3 H]GABA from nerve terminals more effectively in comparison to pregabalin. Absence of unspecific side effects of FGABAs 1 &3 on the membrane potential makes these compounds perspective for medical application. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Inhibition of GABA-gated chloride channels by 12,14-dichlorodehydroabietic acid in mammalian brain.

    PubMed

    Nicholson, R A; Lees, G; Zheng, J; Verdon, B

    1999-03-01

    1. 12,14-dichlorodehydroabietic acid (12,14-Cl2DHA) reduced GABA-stimulated uptake of 36Cl- into mouse brain synaptoneurosomes suggesting inhibition of mammalian GABA(A) receptor function. 2. 12,14-Cl2DHA did not affect the binding of [3H]-muscimol to brain membranes but displaced specifically bound [3H]-EBOB. The inhibitory effect on [3H]-EBOB binding was not reversible. 12,14-Cl2DHA reduced the availability of [3H]-EBOB binding sites (Bmax) without changing the KD of the radioligand for remaining sites. 12,14-Cl2DHA did not affect the rate of association of [3H]-EBOB with its chloride channel receptor, but increased the initial rate of [3H]-EBOB dissociation. 3. 12,14-Cl2DHA enhanced the incidence of EPSCs when rapidly applied to cultured rat cortical neurones. Longer exposures produced block of IPSCs with marked increases in the frequency of EPSCs and min EPSCs. 12,14-Cl2DHA also irreversibly suppressed chloride currents evoked by pulses of exogenous GABA in these cells. 4. Ultimately, 12,14-Cl2DHA inhibited all synaptic traffic and action currents in current clamped cells indicating that, in contrast to picrotoxinin (which causes paroxysmal bursting), it is not fully selective for the GABA(A) receptor-chloride channel complex. 5. The depolarizing block seen with 12,14-Cl2DHA in amphotericin-perforated preparations implicates loss of Ca2+ buffering in the polarity change and this may account for inhibition of spontaneous action potentials. 6. Our investigation demonstrates that 12,14-Cl2DHA blocks GABA-dependent chloride entry in mammalian brain and operates as a non-competitive insurmountable GABA(A) antagonist. The mechanism likely involves either irreversible binding of 12,14-Cl2DHA to the trioxabicyclooctane recognition site or a site that is allosterically coupled to it. We cannot exclude, however, the possibility that 12,14-Cl2DHA causes localized proteolysis or more extensive conformational change within a critical subunit of the chloride channel.

  1. Chloride ions in the pore of glycine and GABA channels shape the time course and voltage dependence of agonist currents

    PubMed Central

    Moroni, Mirko; Biro, Istvan; Giugliano, Michele; Vijayan, Ranjit; Biggin, Philip C.; Beato, Marco; Sivilotti, Lucia G.

    2011-01-01

    In the vertebrate CNS, fast synaptic inhibition is mediated by GABA and glycine receptors. We recently reported that the time course of these synaptic currents is slower when intracellular chloride is high. Here we extend these findings to measure the effects of both extracellular and intracellular chloride on the deactivation of glycine and GABA currents at both negative and positive holding potentials. Currents were elicited by fast agonist application to outside-out patches from HEK293 cells expressing rat glycine or GABA receptors. The slowing effect of high extracellular chloride on current decay was detectable only in low intracellular chloride (4 mM). Our main finding is that glycine and GABA receptors “sense” chloride concentrations because of interactions between the M2 pore-lining domain and the permeating ions. This hypothesis is supported by the observation that the sensitivity of channel gating to intracellular chloride is abolished if the channel is engineered to become cation-selective, or if positive charges in the external pore vestibule are eliminated by mutagenesis. The appropriate interaction between permeating ions and channel pore is also necessary to maintain the channel voltage sensitivity of gating, which prolongs current decay at depolarized potentials. Voltage-dependence is abolished by the same mutations that suppress the effect of intracellular chloride and also by replacing chloride with another permeant ion, thiocyanate. These observations suggest that permeant chloride affects gating by a foot-in-the-door effect, binding to a channel site with asymmetrical access from the intracellular and extracellular sides of the membrane. PMID:21976494

  2. Leptin signaling in GABA neurons, but not glutamate neurons, is required for reproductive function.

    PubMed

    Zuure, Wieteke A; Roberts, Amy L; Quennell, Janette H; Anderson, Greg M

    2013-11-06

    The adipocyte-derived hormone leptin acts in the brain to modulate the central driver of fertility: the gonadotropin releasing hormone (GnRH) neuronal system. This effect is indirect, as GnRH neurons do not express leptin receptors (LEPRs). Here we test whether GABAergic or glutamatergic neurons provide the intermediate pathway between the site of leptin action and the GnRH neurons. Leptin receptors were deleted from GABA and glutamate neurons using Cre-Lox transgenics, and the downstream effects on puberty onset and reproduction were examined. Both mouse lines displayed the expected increase in body weight and region-specific loss of leptin signaling in the hypothalamus. The GABA neuron-specific LEPR knock-out females and males showed significantly delayed puberty onset. Adult fertility observations revealed that these knock-out animals have decreased fecundity. In contrast, glutamate neuron-specific LEPR knock-out mice displayed normal fertility. Assessment of the estrogenic hypothalamic-pituitary-gonadal axis regulation in females showed that leptin action on GABA neurons is not necessary for estradiol-mediated suppression of tonic luteinizing hormone secretion (an indirect measure of GnRH neuron activity) but is required for regulation of a full preovulatory-like luteinizing hormone surge. In conclusion, leptin signaling in GABAergic (but not glutamatergic neurons) plays a critical role in the timing of puberty onset and is involved in fertility regulation throughout adulthood in both sexes. These results form an important step in explaining the role of central leptin signaling in the reproductive system. Limiting the leptin-to-GnRH mediators to GABAergic cells will enable future research to focus on a few specific types of neurons.

  3. Lineage tracing of dlx1a/2a and dlx5a/6a expressing cells in the developing zebrafish brain.

    PubMed

    Solek, Cynthia M; Feng, Shengrui; Perin, Sofia; Weinschutz Mendes, Hellen; Ekker, Marc

    2017-07-01

    Lineage tracing of specific populations of progenitor cells provides crucial information about developmental programs. Four members of the Dlx homeobox gene family, Dlx1,2, 5 and 6, are involved in the specification of γ-aminobutyric acid (GABA)ergic neurons in the vertebrate forebrain. Orthologous genes in mammals and teleost show similarities in expression patterns and transcriptional regulation mechanisms. We have used lineage tracing to permanently label dlx-expressing cells in the zebrafish and have characterized the progeny of these cells in the larva and in the juvenile and adult brain. We have found that dlx1a/2a and dlx5a/6a expressing progenitors give rise, for the most part, to small populations of cells which constitute only a small proportion of GABAergic cells in the adult brain tissue. Moreover, some of the cells do not acquire a neuronal phenotype suggesting that, regardless of the time a cell expresses dlx genes in the brain, it can potentially give rise to cells other than neurons. In some instances, labeling larval dlx5a/6a-expressing cells, but not dlx1a/2a-expressing cells, results in massively expanding, widespread clonal expansion throughout the adult brain. Our data provide a detailed lineage analysis of the dlx1a/2a and dlx5a/6a expressing progenitors in the zebrafish brain and lays the foundation for further characterization of the role of these transcription factors beyond the specification of GABAergic neurons. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Neurochemical correlates of. gamma. -aminobutyrate (GABA) inhibition in cat visual cortex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Balcar, V.J.; Dreher, B.

    1990-01-01

    High affinity binding of ({sup 3}H){gamma}-aminobutyric acid (GABA) to neuronal membranes from different parts of cat visual cortex was tested for sensitivity to GABA{sub A} agonists isoguvacine and THIP, GABA{sub A} antagonist SR95531 and GABA{sub B} agonist baclofen. Some of the GABA{sub A}-binding sites were found to have a very low affinity for THIP, suggesting the presence and, possibly, uneven distribution of non-synaptic GABA{sub A} receptors in cat visual cortex. There were no differences in K{sub m} and V{sub max} values of high affinity uptake of GABA and in the potency of K{sup +}-stimulated release of GABA, between primary andmore » association cortices. Consequently, the present results indicate that despite the anatomical and physiological differences between the primary and association feline visual cortices the neurochemical characteristics of GABAergic inhibition are very similar in the two regions.« less

  5. Acute sleep deprivation preconditions the heart against ischemia/ reperfusion injury: the role of central GABA-A receptors

    PubMed Central

    Parsa, Hoda; Imani, Alireza; Faghihi, Mahdieh; Riahi, Esmail; Badavi, Mohammad; Shakoori, Abbas; Rastegar, Tayebeh; Aghajani, Marjan; Rajani, Sulail Fatima

    2017-01-01

    Objective(s): Central γ-aminobutyric acid (GABA) neurotransmission modulates cardiovascular functions and sleep. Acute sleep deprivation (ASD) affects functions of various body organs via different mechanisms. Here, we evaluated the effect of ASD on cardiac ischemia/reperfusion injury (IRI), and studied the role of GABA-A receptor inhibition in central nucleus of amygdala (CeA) by assessing nitric oxide (NO) and oxidative stress. Materials and Methods: The CeA in sixty male Wistar rats was cannulated for saline or bicuculline (GABA-A receptor antagonist) administration. All animals underwent 30 min of coronary occlusion (ischemia), followed by 2 hr reperfusion (IR). The five experimental groups (n=12) included are as follows: IR: received saline; BIC+IR: received Bicuculline; MLP+IR: received saline, followed by the placement of animals in an aquarium with multiple large platforms; ASD+IR: underwent ASD in an aquarium with multiple small platforms; and BIC+ASD+IR: received bicuculline prior to ASD. Results: Bicuculline administration increased the malondialdehyde levels and infarct size, and decreased the NO metabolites levels and endothelial nitric oxide synthase (eNOS) gene expression in infarcted and non-infarcted areas in comparison to IR group. ASD reduced malondialdehyde levels and infarct size and increased NO metabolites, corticosterone levels and eNOS expression in infarcted and non-infarcted areas as compared to the IR group. Levels of malondialdehyde were increased while levels of NO metabolites, corticosterone and eNOS expression in infarcted and non-infarcted areas were reduced in the BIC+ASD+IR as compared to the ASD+IR group. Conclusion: Blockade of GABA-A receptors in the CeA abolishes ASD-induced cardioprotection by suppressing oxidative stress and NO production. PMID:29299201

  6. Acute sleep deprivation preconditions the heart against ischemia/ reperfusion injury: the role of central GABA-A receptors.

    PubMed

    Parsa, Hoda; Imani, Alireza; Faghihi, Mahdieh; Riahi, Esmail; Badavi, Mohammad; Shakoori, Abbas; Rastegar, Tayebeh; Aghajani, Marjan; Rajani, Sulail Fatima

    2017-11-01

    Central γ-aminobutyric acid (GABA) neurotransmission modulates cardiovascular functions and sleep. Acute sleep deprivation (ASD) affects functions of various body organs via different mechanisms. Here, we evaluated the effect of ASD on cardiac ischemia/reperfusion injury (IRI), and studied the role of GABA-A receptor inhibition in central nucleus of amygdala (CeA) by assessing nitric oxide (NO) and oxidative stress. The CeA in sixty male Wistar rats was cannulated for saline or bicuculline (GABA-A receptor antagonist) administration. All animals underwent 30 min of coronary occlusion (ischemia), followed by 2 hr reperfusion (IR). The five experimental groups (n=12) included are as follows: IR: received saline; BIC+IR: received Bicuculline; MLP+IR: received saline, followed by the placement of animals in an aquarium with multiple large platforms; ASD+IR: underwent ASD in an aquarium with multiple small platforms; and BIC+ASD+IR: received bicuculline prior to ASD. Bicuculline administration increased the malondialdehyde levels and infarct size, and decreased the NO metabolites levels and endothelial nitric oxide synthase (eNOS) gene expression in infarcted and non-infarcted areas in comparison to IR group. ASD reduced malondialdehyde levels and infarct size and increased NO metabolites, corticosterone levels and eNOS expression in infarcted and non-infarcted areas as compared to the IR group. Levels of malondialdehyde were increased while levels of NO metabolites, corticosterone and eNOS expression in infarcted and non-infarcted areas were reduced in the BIC+ASD+IR as compared to the ASD+IR group. Blockade of GABA-A receptors in the CeA abolishes ASD-induced cardioprotection by suppressing oxidative stress and NO production.

  7. GABA and Glutamate Pathways Are Spatially and Developmentally Affected in the Brain of Mecp2-Deficient Mice

    PubMed Central

    Matagne, Valérie; Ghata, Adeline; Villard, Laurent; Roux, Jean-Christophe

    2014-01-01

    Proper brain functioning requires a fine-tuning between excitatory and inhibitory neurotransmission, a balance maintained through the regulation and release of glutamate and GABA. Rett syndrome (RTT) is a rare genetic disorder caused by mutations in the methyl-CpG binding protein 2 (MECP2) gene affecting the postnatal brain development. Dysfunctions in the GABAergic and glutamatergic systems have been implicated in the neuropathology of RTT and a disruption of the balance between excitation and inhibition, together with a perturbation of the electrophysiological properties of GABA and glutamate neurons, were reported in the brain of the Mecp2-deficient mouse. However, to date, the extent and the nature of the GABA/glutamate deficit affecting the Mecp2-deficient mouse brain are unclear. In order to better characterize these deficits, we simultaneously analyzed the GABA and glutamate levels in Mecp2-deficient mice at 2 different ages (P35 and P55) and in several brain areas. We used a multilevel approach including the quantification of GABA and glutamate levels, as well as the quantification of the mRNA and protein expression levels of key genes involved in the GABAergic and glutamatergic pathways. Our results show that Mecp2-deficient mice displayed regional- and age-dependent variations in the GABA pathway and, to a lesser extent, in the glutamate pathway. The implication of the GABA pathway in the RTT neuropathology was further confirmed using an in vivo treatment with a GABA reuptake inhibitor that significantly improved the lifespan of Mecp2-deficient mice. Our results confirm that RTT mouse present a deficit in the GABAergic pathway and suggest that GABAergic modulators could be interesting therapeutic agents for this severe neurological disorder. PMID:24667344

  8. The effect of sodium thiopental as a GABA mimetic drug in neonatal period on expression of GAD65 and GAD67 genes in hippocampus of newborn and adult male rats.

    PubMed

    Naseri, Masoud; Parham, Abbas; Moghimi, Ali

    2017-09-01

    Development of the nervous system in human and most animals is continued after the birth. Critical role of this period in generation and specialization of the neuronal circuits is confirmed in numerous studies. Any pharmacological intervention in this period may result in structural, functional or behavioral abnormalities. In this study, sodium thiopental a GABA mimetic drug was administrated to newborn rats and their GAD65 and GAD67 expression in hippocampus was evaluated before and after puberty. Newborn male Wistar rats were received sodium thiopental (35 mg/kg) daily for 11 days (from 4 to 14 days after birth). Expression of GAD65 and GAD67 in their hippocampus was compared with control groups in 15 and 45 days after birth with RT-qPCR method. Significant down regulation of GAD65 and GAD67 gene expression was observed in treated rats compared with control group in 45 days after birth animals. But no significant difference was shown between experimental and control groups 15 days after birth animals. The effect of sodium thiopental on GAD65 and GAD67 expression only at adult rats showed a latent period of influence which can be attributed to dosage or intension of sodium thiopental neurotoxicity. Significant down regulation of GAD65 and GAD67 showed unwanted effect of sodium thiopental as GABA mimetic drug in critical period of development.

  9. Immunocytochemical Mapping of an RDL-Like GABA Receptor Subunit and of GABA in Brain Structures Related to Learning and Memory in the Cricket Acheta domesticus

    PubMed Central

    Strambi, Colette; Cayre, Myriam; Sattelle, David B.; Augier, Roger; Charpin, Pierre; Strambi, Alain

    1998-01-01

    The distribution of putative RDL-like GABA receptors and of γ-aminobutyric acid (GABA) in the brain of the adult house cricket Acheta domesticus was studied using specific antisera. Special attention was given to brain structures known to be related to learning and memory. The main immunostaining for the RDL-like GABA receptor was observed in mushroom bodies, in particular the upper part of mushroom body peduncle and the two arms of the posterior calyx. Weaker immunostaining was detected in the distal part of the peduncle and in the α and β lobes. The dorso- and ventrolateral protocerebrum neuropils appeared rich in RDL-like GABA receptors. Staining was also detected in the glomeruli of the antennal lobe, as well as in the ellipsoid body of the central complex. Many neurons clustered in groups exhibit GABA-like immunoreactivity. Tracts that were strongly immunostained innervated both the calyces and the lobes of mushroom bodies. The glomeruli of the antennal lobe, the ellipsoid body, as well as neuropils of the dorso- and ventrolateral protocerebrum were also rich in GABA-like immuno- reactivity. The data demonstrated a good correlation between the distribution of the GABA-like and of the RDL-like GABA receptor immunoreactivity. The prominent distribution of RDL-like GABA receptor subunits, in particular areas of mushroom bodies and antennal lobes, underlines the importance of inhibitory signals in information processing in these major integrative centers of the insect brain. PMID:10454373

  10. The developmental switch in GABA polarity is delayed in fragile X mice.

    PubMed

    He, Qionger; Nomura, Toshihiro; Xu, Jian; Contractor, Anis

    2014-01-08

    Delays in synaptic and neuronal development in the cortex are key hallmarks of fragile X syndrome, a prevalent neurodevelopmental disorder that causes intellectual disability and sensory deficits and is the most common known cause of autism. Previous studies have demonstrated that the normal progression of plasticity and synaptic refinement during the critical period is altered in the cortex of fragile X mice. Although the disruptions in excitatory synapses are well documented in fragile X, there is less known about inhibitory neurotransmission during the critical period. GABAergic transmission plays a crucial trophic role in cortical development through its early depolarizing action. At the end of cortical critical period, response properties of GABA transform into their mature hyperpolarizing type due to developmental changes in intracellular chloride homeostasis. We found that the timing of the switch from depolarizing to hyperpolarizing GABA is delayed in the cortex of fragile X mice and there is a concurrent alteration in the expression of the neuronal chloride cotransporter NKCC1 that promotes the accumulation of intracellular chloride. Disruption of the trophic effects of GABA during cortical development could contribute to the altered trajectory of synaptic maturation in fragile X syndrome.

  11. Dependence-induced ethanol drinking and GABA neurotransmission are altered in Alk deficient mice

    PubMed Central

    Schweitzer, Paul; Cates-Gatto, Chelsea; Varodayan, Florence P.; Nadav, Tali; Roberto, Marisa; Lasek, Amy W.; Roberts, Amanda J.

    2016-01-01

    Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase that is expressed in the brain and implicated in alcohol abuse in humans and behavioral responses to ethanol in mice. Previous studies have shown an association of human ALK with acute responses to alcohol and alcohol dependence. In addition, Alk knockout (Alk −/−) mice consume more ethanol in a binge-drinking test and show increased sensitivity to ethanol sedation. However, the function of ALK in excessive drinking following the establishment of ethanol dependence has not been examined. In this study, we tested Alk −/− mice for dependence-induced drinking using the chronic intermittent ethanol-two bottle choice drinking (CIE-2BC) protocol. We found that Alk −/− mice initially consume more ethanol prior to CIE exposure, but do not escalate ethanol consumption after exposure, suggesting that ALK may promote the escalation of drinking after ethanol dependence. To determine the mechanism(s) responsible for this behavioral phenotype we used an electrophysiological approach to examine GABA neurotransmission in the central nucleus of the amygdala (CeA), a brain region that regulates alcohol consumption and shows increased GABA signaling after chronic ethanol exposure. GABA transmission in ethanol-naïve Alk −/− mice was enhanced at baseline and potentiated in response to acute ethanol application when compared to wild-type (Alk +/+) mice. Moreover, basal GABA transmission was not elevated by CIE exposure in Alk −/− mice as it was in Alk +/+ mice. These data suggest that ALK plays a role in dependence-induced drinking and the regulation of presynaptic GABA release in the CeA. PMID:26946429

  12. Proline antagonizes GABA-induced quenching of quorum-sensing in Agrobacterium tumefaciens

    PubMed Central

    Haudecoeur, E.; Planamente, S.; Cirou, A.; Tannières, M.; Shelp, B. J.; Moréra, S.; Faure, D.

    2009-01-01

    Plants accumulate free L-proline (Pro) in response to abiotic stresses (drought and salinity) and presence of bacterial pathogens, including the tumor-inducing bacterium Agrobacterium tumefaciens. However, the function of Pro accumulation in host-pathogen interaction is still unclear. Here, we demonstrated that Pro antagonizes plant GABA-defense in the A. tumefaciens C58-induced tumor by interfering with the import of GABA and consequently the GABA-induced degradation of the bacterial quorum-sensing signal, 3-oxo-octanoylhomoserine lactone. We identified a bacterial receptor Atu2422, which is implicated in the uptake of GABA and Pro, suggesting that Pro acts as a natural antagonist of GABA-signaling. The Atu2422 amino acid sequence contains a Venus flytrap domain that is required for trapping GABA in human GABAB receptors. A constructed atu2422 mutant was more virulent than the wild type bacterium; moreover, transgenic plants with a low level of Pro exhibited less severe tumor symptoms than did their wild-type parents, revealing a crucial role for Venus flytrap GABA-receptor and relative abundance of GABA and Pro in host-pathogen interaction. PMID:19706545

  13. Molecular and functional differences in voltage-activated sodium currents between GABA projection neurons and dopamine neurons in the substantia nigra

    PubMed Central

    Ding, Shengyuan; Wei, Wei

    2011-01-01

    GABA projection neurons (GABA neurons) in the substantia nigra pars reticulata (SNr) and dopamine projection neurons (DA neurons) in substantia nigra pars compacta (SNc) have strikingly different firing properties. SNc DA neurons fire low-frequency, long-duration spikes, whereas SNr GABA neurons fire high-frequency, short-duration spikes. Since voltage-activated sodium (NaV) channels are critical to spike generation, the different firing properties raise the possibility that, compared with DA neurons, NaV channels in SNr GABA neurons have higher density, faster kinetics, and less cumulative inactivation. Our quantitative RT-PCR analysis on immunohistochemically identified nigral neurons indicated that mRNAs for pore-forming NaV1.1 and NaV1.6 subunits and regulatory NaVβ1 and Navβ4 subunits are more abundant in SNr GABA neurons than SNc DA neurons. These α-subunits and β-subunits are key subunits for forming NaV channels conducting the transient NaV current (INaT), persistent Na current (INaP), and resurgent Na current (INaR). Nucleated patch-clamp recordings showed that INaT had a higher density, a steeper voltage-dependent activation, and a faster deactivation in SNr GABA neurons than in SNc DA neurons. INaT also recovered more quickly from inactivation and had less cumulative inactivation in SNr GABA neurons than in SNc DA neurons. Furthermore, compared with nigral DA neurons, SNr GABA neurons had a larger INaR and INaP. Blockade of INaP induced a larger hyperpolarization in SNr GABA neurons than in SNc DA neurons. Taken together, these results indicate that NaV channels expressed in fast-spiking SNr GABA neurons and slow-spiking SNc DA neurons are tailored to support their different spiking capabilities. PMID:21880943

  14. l-Proline, GABA Synthesis and Gamma Oscillations in Schizophrenia.

    PubMed

    Volk, David W; Gonzalez-Burgos, Guillermo; Lewis, David A

    2016-12-01

    Altered inhibition from parvalbumin-containing GABA neurons is thought to contribute to impaired gamma frequency oscillations and cognitive deficits in schizophrenia. Crabtree and colleagues report that proline dehydrogenase deficits produce excessive cytosolic levels of the GABA-mimetic l-proline which impairs GABA synthesis and gamma oscillations in a manner that mimics schizophrenia. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Alterations in food intake elicited by GABA and opioid agonists and antagonists administered into the ventral tegmental area region of rats.

    PubMed

    Echo, Joyce A; Lamonte, Nicole; Ackerman, Tsippa F; Bodnar, Richard J

    2002-05-01

    Food intake is significantly increased following administration of mu-selective opioid agonists into the ventral tegmental area (VTA) region acting through multiple local opioid receptor subtypes. Since GABA receptor agonists in the VTA region are capable of eliciting feeding, the present study investigated whether feeding elicited by the mu-selective opioid agonist [D-Ala(2), NMe(4), Gly-ol(5)]-enkephalin (DAMGO) in the VTA region was altered by pretreatment into the same site with equimolar doses of either GABA(A) (bicuculline) or GABA(B) (saclofen) antagonists, and further, whether pretreatment with either general opioid or selective GABA receptor antagonists decreased feeding elicited by GABA(A) (muscimol) or GABA(B) (baclofen) agonists in the VTA region. DAMGO-induced feeding in the VTA region was dose-dependently decreased following pretreatment with either GABA(A) or GABA(B) antagonists in the absence of significant alterations in food intake by the antagonists per se. However, the presence of short-lived seizures following bicuculline in the VTA region suggests that this ingestive effect was caused by nonspecific actions. In contrast, GABA(B) receptors are involved in the full expression of mu-opioid agonist-induced feeding in this region since saclofen failed to elicit either seizure activity or a conditioned taste aversion. Pretreatment with naltrexone in the VTA region reduced intake elicited by baclofen, but not muscimol. Finally, baclofen-induced feeding was significantly reduced by saclofen, but not bicuculline, pretreatment in the VTA region. Therefore, possible coregulation between GABA(B) and opioid receptors in the VTA region, as suggested by immunocytochemical evidence, is supported by these behavioral effects upon ingestion.

  16. Presynaptic Protein Synthesis Is Required for Long-Term Plasticity of GABA Release.

    PubMed

    Younts, Thomas J; Monday, Hannah R; Dudok, Barna; Klein, Matthew E; Jordan, Bryen A; Katona, István; Castillo, Pablo E

    2016-10-19

    Long-term changes of neurotransmitter release are critical for proper brain function. However, the molecular mechanisms underlying these changes are poorly understood. While protein synthesis is crucial for the consolidation of postsynaptic plasticity, whether and how protein synthesis regulates presynaptic plasticity in the mature mammalian brain remain unclear. Here, using paired whole-cell recordings in rodent hippocampal slices, we report that presynaptic protein synthesis is required for long-term, but not short-term, plasticity of GABA release from type 1 cannabinoid receptor (CB 1 )-expressing axons. This long-term depression of inhibitory transmission (iLTD) involves cap-dependent protein synthesis in presynaptic interneuron axons, but not somata. Translation is required during the induction, but not maintenance, of iLTD. Mechanistically, CB 1 activation enhances protein synthesis via the mTOR pathway. Furthermore, using super-resolution STORM microscopy, we revealed eukaryotic ribosomes in CB 1 -expressing axon terminals. These findings suggest that presynaptic local protein synthesis controls neurotransmitter release during long-term plasticity in the mature mammalian brain. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Creatine Enhances Transdifferentiation of Bone Marrow Stromal Cell-Derived Neural Stem Cell Into GABAergic Neuron-Like Cells Characterized With Differential Gene Expression.

    PubMed

    Darabi, Shahram; Tiraihi, Taki; Delshad, AliReza; Sadeghizadeh, Majid; Taheri, Taher; Hassoun, Hayder K

    2017-04-01

    Creatine was reported to induce bone marrow stromal cells (BMSC) into GABAergic neuron-like cells (GNLC). In a previous study, creatine was used as a single inducer for BMSC into GNLC with low yield. In this study, BMSC-derived neurospheres (NS) have been used in generating GABAergic phenotype. The BMSC were isolated from adult rats and used in generating neurospheres and used for producing neural stem cells (NSC). A combination of all-trans-retinoic acid (RA), the ciliary neurotrophic factor (CNTF), and creatine was used in order to improve the yield of GNLC. We also used other protocols for the transdifferentiation including RA alone; RA and creatine; RA and CNTF; and RA, CNTF, and creatine. The BMSC, NSC, and GNLC were characterized by specific markers. The activity of the GNLC was evaluated using FM1-43. The isolated BMSC expressed Oct4, fibronectin, and CD44. The NS were immunoreactive to nestin and SOX2, the NSC were immunoreactive to nestin, NF68 and NF160, while the GNLC were immunoreactive to GAD1/2, VGAT, GABA, and synaptophysin. Oct4 and c-MYC, pluripotency genes, were expressed in the BMSC, while SOX2 and c-MYC were expressed in the NSC. The activity of GNLC indicates that the synaptic vesicles were released upon stimulation. The conclusion is that the combination of RA, CNTF, and creatine induced differentiation of neurosphere-derived NSC into GNLC within 1 week. This protocol gives higher yield than the other protocols used in this study. The mechanism of induction was clearly associated with several differential pluripotent genes.

  18. GABA neuron alterations, cortical circuit dysfunction and cognitive deficits in schizophrenia.

    PubMed

    Gonzalez-Burgos, Guillermo; Fish, Kenneth N; Lewis, David A

    2011-01-01

    Schizophrenia is a brain disorder associated with cognitive deficits that severely affect the patients' capacity for daily functioning. Whereas our understanding of its pathophysiology is limited, postmortem studies suggest that schizophrenia is associated with deficits of GABA-mediated synaptic transmission. A major role of GABA-mediated transmission may be producing synchronized network oscillations which are currently hypothesized to be essential for normal cognitive function. Therefore, cognitive deficits in schizophrenia may result from a GABA synapse dysfunction that disturbs neural synchrony. Here, we highlight recent studies further suggesting alterations of GABA transmission and network oscillations in schizophrenia. We also review current models for the mechanisms of GABA-mediated synchronization of neural activity, focusing on parvalbumin-positive GABA neurons, which are altered in schizophrenia and whose function has been strongly linked to the production of neural synchrony. Alterations of GABA signaling that impair gamma oscillations and, as a result, cognitive function suggest paths for novel therapeutic interventions.

  19. GABA Neuron Alterations, Cortical Circuit Dysfunction and Cognitive Deficits in Schizophrenia

    PubMed Central

    Gonzalez-Burgos, Guillermo; Fish, Kenneth N.; Lewis, David A.

    2011-01-01

    Schizophrenia is a brain disorder associated with cognitive deficits that severely affect the patients' capacity for daily functioning. Whereas our understanding of its pathophysiology is limited, postmortem studies suggest that schizophrenia is associated with deficits of GABA-mediated synaptic transmission. A major role of GABA-mediated transmission may be producing synchronized network oscillations which are currently hypothesized to be essential for normal cognitive function. Therefore, cognitive deficits in schizophrenia may result from a GABA synapse dysfunction that disturbs neural synchrony. Here, we highlight recent studies further suggesting alterations of GABA transmission and network oscillations in schizophrenia. We also review current models for the mechanisms of GABA-mediated synchronization of neural activity, focusing on parvalbumin-positive GABA neurons, which are altered in schizophrenia and whose function has been strongly linked to the production of neural synchrony. Alterations of GABA signaling that impair gamma oscillations and, as a result, cognitive function suggest paths for novel therapeutic interventions. PMID:21904685

  20. The GABA(A) receptor RDL acts in peptidergic PDF neurons to promote sleep in Drosophila.

    PubMed

    Chung, Brian Y; Kilman, Valerie L; Keath, J Russel; Pitman, Jena L; Allada, Ravi

    2009-03-10

    Sleep is regulated by a circadian clock that times sleep and wake to specific times of day and a homeostat that drives sleep as a function of prior wakefulness. To analyze the role of the circadian clock, we have used the fruit fly Drosophila. Flies display the core behavioral features of sleep, including relative immobility, elevated arousal thresholds, and homeostatic regulation. We assessed sleep-wake modulation by a core set of circadian pacemaker neurons that express the neuropeptide PDF. We find that disruption of PDF function increases sleep during the late night in light:dark and the first subjective day of constant darkness. Flies deploy genetic and neurotransmitter pathways to regulate sleep that are similar to those of their mammalian counterparts, including GABA. We find that RNA interference-mediated knockdown of the GABA(A) receptor gene, Resistant to dieldrin (Rdl), in PDF neurons reduces sleep, consistent with a role for GABA in inhibiting PDF neuron function. Patch-clamp electrophysiology reveals GABA-activated picrotoxin-sensitive chloride currents on PDF+ neurons. In addition, RDL is detectable most strongly on the large subset of PDF+ pacemaker neurons. These results suggest that GABAergic inhibition of arousal-promoting PDF neurons is an important mode of sleep-wake regulation in vivo.

  1. Increased GABA-A receptor binding and reduced connectivity at the motor cortex in children with hemiplegic cerebral palsy: a multimodal investigation using 18F-fluoroflumazenil PET, immunohistochemistry, and MR imaging.

    PubMed

    Park, Hae-Jeong; Kim, Chul Hoon; Park, Eun Sook; Park, Bumhee; Oh, So Ra; Oh, Maeng-Keun; Park, Chang Il; Lee, Jong Doo

    2013-08-01

    γ-aminobutyric acid (GABA)-A receptor-mediated neural transmission is important to promote practice-dependent plasticity after brain injury. This study investigated alterations in GABA-A receptor binding and functional and anatomic connectivity within the motor cortex in children with cerebral palsy (CP). We conducted (18)F-fluoroflumazenil PET on children with hemiplegic CP to investigate whether in vivo GABA-A receptor binding is altered in the ipsilateral or contralateral hemisphere of the lesion site. To evaluate changes in the GABA-A receptor subunit after prenatal brain injury, we performed GABA-A receptor immunohistochemistry using rat pups with a diffuse hypoxic ischemic insult. We also performed diffusion tensor MR imaging and resting-state functional MR imaging on the same children with hemiplegic CP to investigate alterations in anatomic and functional connectivity at the motor cortex with increased GABA-A receptor binding. In children with hemiplegic CP, the (18)F-fluoroflumazenil binding potential was increased within the ipsilateral motor cortex. GABA-A receptors with the α1 subunit were highly expressed exclusively within cortical layers III, IV, and VI of the motor cortex in rat pups. The motor cortex with increased GABA-A receptor binding in children with hemiplegic CP had reduced thalamocortical and corticocortical connectivity, which might be linked to increased GABA-A receptor distribution in cortical layers in rats. Increased expression of the GABA-A receptor α1 subunit within the ipsilateral motor cortex may be an important adaptive mechanism after prenatal brain injury in children with CP but may be associated with improper functional connectivity after birth and have adverse effects on the development of motor plasticity.

  2. Lhx6-positive GABA-releasing neurons of the zona incerta promote sleep

    PubMed Central

    Liu, Kai; Kim, Juhyun; Kim, Dong Won; Zhang, Yi Stephanie; Bao, Hechen; Denaxa, Myrto; Lim, Szu-Aun; Kim, Eileen; Liu, Chang; Wickersham, Ian R.; Pachnis, Vassilis; Hattar, Samer; Song, Juan; Brown, Solange P.; Blackshaw, Seth

    2017-01-01

    Multiple populations of wake-promoting neurons have been characterized in mammals, but few sleep-promoting neurons have been identified1. Wake-promoting cell types include hypocretin and GABA (γ-aminobutyric-acid)-releasing neurons of the lateral hypothalamus, which promote the transition to wakefulness from non-rapid eye movement (NREM) and rapid eye movement (REM) sleep2,3. Here we show that a subset of GABAergic neurons in the mouse ventral zona incerta, which express the LIM homeodomain factor Lhx6 and are activated by sleep pressure, both directly inhibit wake-active hypocretin and GABAergic cells in the lateral hypothalamus and receive inputs from multiple sleep–wake-regulating neurons. Conditional deletion of Lhx6 from the developing diencephalon leads to decreases in both NREM and REM sleep. Furthermore, selective activation and inhibition of Lhx6-positive neurons in the ventral zona incerta bidirectionally regulate sleep time in adult mice, in part through hypocretin-dependent mechanisms. These studies identify a GABAergic subpopulation of neurons in the ventral zona incerta that promote sleep. PMID:28847002

  3. Rapid binge-like eating and body weight gain driven by zona incerta GABA neuron activation.

    PubMed

    Zhang, Xiaobing; van den Pol, Anthony N

    2017-05-26

    The neuronal substrate for binge eating, which can at times lead to obesity, is not clear. We find that optogenetic stimulation of mouse zona incerta (ZI) γ-aminobutyric acid (GABA) neurons or their axonal projections to paraventricular thalamus (PVT) excitatory neurons immediately (in 2 to 3 seconds) evoked binge-like eating. Minimal intermittent stimulation led to body weight gain; ZI GABA neuron ablation reduced weight. ZI stimulation generated 35% of normal 24-hour food intake in just 10 minutes. The ZI cells were excited by food deprivation and the gut hunger signal ghrelin. In contrast, stimulation of excitatory axons from the parasubthalamic nucleus to PVT or direct stimulation of PVT glutamate neurons reduced food intake. These data suggest an unexpected robust orexigenic potential for the ZI GABA neurons. Copyright © 2017, American Association for the Advancement of Science.

  4. Effects of disrupting medial prefrontal cortex GABA transmission on decision-making in a rodent gambling task.

    PubMed

    Paine, T A; O'Hara, A; Plaut, B; Lowes, D C

    2015-05-01

    Decision-making is a complex cognitive process that is mediated, in part, by subregions of the medial prefrontal cortex (PFC). Decision-making is impaired in a number of psychiatric conditions including schizophrenia. Notably, people with schizophrenia exhibit reductions in GABA function in the same PFC areas that are implicated in decision-making. For example, expression of the GABA-synthesizing enzyme GAD67 is reduced in the dorsolateral PFC of people with schizophrenia. The goal of this experiment was to determine whether disrupting cortical GABA transmission impairs decision-making using a rodent gambling task (rGT). Rats were trained on the rGT until they reached stable performance and then were implanted with guide cannulae aimed at the medial PFC. Following recovery, the effects of intra-PFC infusions of the GABAA receptor antagonist bicuculline methiodide (BMI) or the GABA synthesis inhibitor L-allylglycine (LAG) on performance on the rGT were assessed. Intracortical infusions of BMI (25 ng/μl/side), but not LAG (10 μg/μl/side), altered decision-making. Following BMI infusions, rats made fewer advantageous choices. Follow-up experiments suggested that the change in decision-making was due to a change in the sensitivity to the punishments, rather than a change in the sensitivity to reward magnitudes, associated with each outcome. LAG infusions increased premature responding, a measure of response inhibition, but did not affect decision-making. Blocking GABAA receptors, but not inhibiting cortical GABA synthesis, within the medial PFC affects decision-making in the rGT. These data provide proof-of-concept evidence that disruptions in GABA transmission can contribute to the decision-making deficits in schizophrenia.

  5. Gamma-aminobutyric acid (GABA)-B receptor 1 in cerebellar cortex of essential tremor.

    PubMed

    Luo, C; Rajput, A H; Robinson, C A; Rajput, A

    2012-06-01

    Some reports suggest cerebellar dysfunction as the basis of essential tremor (ET). Several drugs with the action of gamma-aminobutyric acid (GABA) are known to improve ET. Autopsy studies were performed on brains from nine former patients followed at the Movement Disorders Clinic Saskatchewan, Canada, and compared with five normal control brains. We aimed to measure the concentration of GABA B receptor 1 (GBR1) in the brains of patients who had had ET and to compare them to the GABA concentration in brains of controls. Western blot was used to determine the expression of GBR1 in cerebellar cortex tissue. We found that compared to the controls, the ET brains had three different patterns of GBR1 protein concentration--two with high, four comparable, and three with marginally low levels. There was no association between the age of onset, severity or duration of tremor, the response to alcohol or other drugs and GBR1 level. Thus, we conclude that our study does not support that GBR1 is involved in ET. Further studies are needed to verify these results. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Age-related differences in GABA levels are driven by bulk tissue changes.

    PubMed

    Maes, Celine; Hermans, Lize; Pauwels, Lisa; Chalavi, Sima; Leunissen, Inge; Levin, Oron; Cuypers, Koen; Peeters, Ronald; Sunaert, Stefan; Mantini, Dante; Puts, Nicolaas A J; Edden, Richard A E; Swinnen, Stephan P

    2018-05-02

    Levels of GABA, the main inhibitory neurotransmitter in the brain, can be regionally quantified using magnetic resonance spectroscopy (MRS). Although GABA is crucial for efficient neuronal functioning, little is known about age-related differences in GABA levels and their relationship with age-related changes in brain structure. Here, we investigated the effect of age on GABA levels within the left sensorimotor cortex and the occipital cortex in a sample of 85 young and 85 older adults using the MEGA-PRESS sequence. Because the distribution of GABA varies across different brain tissues, various correction methods are available to account for this variation. Considering that these correction methods are highly dependent on the tissue composition of the voxel of interest, we examined differences in voxel composition between age groups and the impact of these various correction methods on the identification of age-related differences in GABA levels. Results indicated that, within both voxels of interest, older (as compared to young adults) exhibited smaller gray matter fraction accompanied by larger fraction of cerebrospinal fluid. Whereas uncorrected GABA levels were significantly lower in older as compared to young adults, this age effect was absent when GABA levels were corrected for voxel composition. These results suggest that age-related differences in GABA levels are at least partly driven by the age-related gray matter loss. However, as alterations in GABA levels might be region-specific, further research should clarify to what extent gray matter changes may account for age-related differences in GABA levels within other brain regions. © 2018 Wiley Periodicals, Inc.

  7. Actions of Agonists, Fipronil and Ivermectin on the Predominant In Vivo Splice and Edit Variant (RDLbd, I/V) of the Drosophila GABA Receptor Expressed in Xenopus laevis Oocytes

    PubMed Central

    Suwanmanee, Siros; Buckingham, Steven David; Biggin, Philip; Sattelle, David

    2014-01-01

    Ionotropic GABA receptors are the targets for several classes of insecticides. One of the most widely-studied insect GABA receptors is RDL (resistance to dieldrin), originally isolated from Drosophila melanogaster. RDL undergoes alternative splicing and RNA editing, which influence the potency of GABA. Most work has focussed on minority isoforms. Here, we report the first characterisation of the predominant native splice variant and RNA edit, combining functional characterisation with molecular modelling of the agonist-binding region. The relative order of agonist potency is GABA> muscimol> TACA> β-alanine. The I/V edit does not alter the potency of GABA compared to RDLbd. Docking calculations suggest that these agonists bind and activate RDLbdI/V through a similar binding mode. TACA and β-alanine are predicted to bind with lower affinity than GABA, potentially explaining their lower potency, whereas the lower potency of muscimol and isoguvacine cannot be explained structurally from the docking calculations. The A301S (resistance to dieldrin) mutation reduced the potency of antagonists picrotoxin, fipronil and pyrafluprole but the I/V edit had no measurable effect. Ivermectin suppressed responses to GABA of RDLbdI/V, RDLbd and RDLbdI/VA301S. The dieldrin resistant variant also showed reduced sensitivity to Ivermectin. This study of a highly abundant insect GABA receptor isoform will help the design of new insecticides. PMID:24823815

  8. Human Occipital and Parietal GABA Selectively Influence Visual Perception of Orientation and Size.

    PubMed

    Song, Chen; Sandberg, Kristian; Andersen, Lau Møller; Blicher, Jakob Udby; Rees, Geraint

    2017-09-13

    GABA is the primary inhibitory neurotransmitter in human brain. The level of GABA varies substantially across individuals, and this variability is associated with interindividual differences in visual perception. However, it remains unclear whether the association between GABA level and visual perception reflects a general influence of visual inhibition or whether the GABA levels of different cortical regions selectively influence perception of different visual features. To address this, we studied how the GABA levels of parietal and occipital cortices related to interindividual differences in size, orientation, and brightness perception. We used visual contextual illusion as a perceptual assay since the illusion dissociates perceptual content from stimulus content and the magnitude of the illusion reflects the effect of visual inhibition. Across individuals, we observed selective correlations between the level of GABA and the magnitude of contextual illusion. Specifically, parietal GABA level correlated with size illusion magnitude but not with orientation or brightness illusion magnitude; in contrast, occipital GABA level correlated with orientation illusion magnitude but not with size or brightness illusion magnitude. Our findings reveal a region- and feature-dependent influence of GABA level on human visual perception. Parietal and occipital cortices contain, respectively, topographic maps of size and orientation preference in which neural responses to stimulus sizes and stimulus orientations are modulated by intraregional lateral connections. We propose that these lateral connections may underlie the selective influence of GABA on visual perception. SIGNIFICANCE STATEMENT GABA, the primary inhibitory neurotransmitter in human visual system, varies substantially across individuals. This interindividual variability in GABA level is linked to interindividual differences in many aspects of visual perception. However, the widespread influence of GABA raises the

  9. GABA level, gamma oscillation, and working memory performance in schizophrenia

    PubMed Central

    Chen, Chi-Ming A.; Stanford, Arielle D.; Mao, Xiangling; Abi-Dargham, Anissa; Shungu, Dikoma C.; Lisanby, Sarah H.; Schroeder, Charles E.; Kegeles, Lawrence S.

    2014-01-01

    A relationship between working memory impairment, disordered neuronal oscillations, and abnormal prefrontal GABA function has been hypothesized in schizophrenia; however, in vivo GABA measurements and gamma band neural synchrony have not yet been compared in schizophrenia. This case–control pilot study (N = 24) compared baseline and working memory task-induced neuronal oscillations acquired with high-density electroencephalograms (EEGs) to GABA levels measured in vivo with magnetic resonance spectroscopy. Working memory performance, baseline GABA level in the left dorsolateral prefrontal cortex (DLPFC), and measures of gamma oscillations from EEGs at baseline and during a working memory task were obtained. A major limitation of this study is a relatively small sample size for several analyses due to the integration of diverse methodologies and participant compliance. Working memory performance was significantly lower for patients than for controls. During the working memory task, patients (n = 7) had significantly lower amplitudes in gamma oscillations than controls (n = 9). However, both at rest and across working memory stages, there were significant correlations between gamma oscillation amplitude and left DLPFC GABA level. Peak gamma frequency during the encoding stage of the working memory task (n = 16) significantly correlated with GABA level and working memory performance. Despite gamma band amplitude deficits in patients across working memory stages, both baseline and working memory-induced gamma oscillations showed strong dependence on baseline GABA levels in patients and controls. These findings suggest a critical role for GABA function in gamma band oscillations, even under conditions of system and cognitive impairments as seen in schizophrenia. PMID:24749063

  10. GABA level, gamma oscillation, and working memory performance in schizophrenia.

    PubMed

    Chen, Chi-Ming A; Stanford, Arielle D; Mao, Xiangling; Abi-Dargham, Anissa; Shungu, Dikoma C; Lisanby, Sarah H; Schroeder, Charles E; Kegeles, Lawrence S

    2014-01-01

    A relationship between working memory impairment, disordered neuronal oscillations, and abnormal prefrontal GABA function has been hypothesized in schizophrenia; however, in vivo GABA measurements and gamma band neural synchrony have not yet been compared in schizophrenia. This case-control pilot study (N = 24) compared baseline and working memory task-induced neuronal oscillations acquired with high-density electroencephalograms (EEGs) to GABA levels measured in vivo with magnetic resonance spectroscopy. Working memory performance, baseline GABA level in the left dorsolateral prefrontal cortex (DLPFC), and measures of gamma oscillations from EEGs at baseline and during a working memory task were obtained. A major limitation of this study is a relatively small sample size for several analyses due to the integration of diverse methodologies and participant compliance. Working memory performance was significantly lower for patients than for controls. During the working memory task, patients (n = 7) had significantly lower amplitudes in gamma oscillations than controls (n = 9). However, both at rest and across working memory stages, there were significant correlations between gamma oscillation amplitude and left DLPFC GABA level. Peak gamma frequency during the encoding stage of the working memory task (n = 16) significantly correlated with GABA level and working memory performance. Despite gamma band amplitude deficits in patients across working memory stages, both baseline and working memory-induced gamma oscillations showed strong dependence on baseline GABA levels in patients and controls. These findings suggest a critical role for GABA function in gamma band oscillations, even under conditions of system and cognitive impairments as seen in schizophrenia.

  11. The GABA uptake inhibitor beta-alanine reduces pilocarpine-induced tremor and increases extracellular GABA in substantia nigra pars reticulata as measured by microdialysis.

    PubMed

    Ishiwari, Keita; Mingote, Susana; Correa, Merce; Trevitt, Jennifer T; Carlson, Brian B; Salamone, John D

    2004-12-30

    Substantia nigra pars reticulata (SNr) is a major output nucleus of the basal ganglia that receives GABAergic projections from neostriatum and globus pallidus. Previous research has shown that local pharmacological manipulations of GABA in SNr can influence tremulous jaw movements in rats. Tremulous jaw movements are defined as rapid vertical deflections of the lower jaw that resemble chewing but are not directed at a particular stimulus, and evidence indicates that these movements share many characteristics with parkinsonian tremor in humans. In order to investigate the role of GABA in motor functions related to tremor, the present study tested the GABA uptake blocker beta-alanine for its ability to reduce pilocarpine-induced tremulous jaw movements. In a parallel experiment, the effect of an active dose of beta-alanine on dialysate levels of GABA in SNr was assessed using microdialysis methods. GABA levels in dialysis samples were measured using high performance liquid chromatography with electrochemical detection. beta-Alanine (250-500 mg/kg) significantly reduced tremulous jaw movements induced by pilocarpine (4.0 mg/kg). Moreover, systemic administration of beta-alanine at a dose that reduced tremulous jaw movements (500 mg/kg) resulted in a substantial increase in extracellular levels of GABA in SNr compared to the pre-injection baseline. Thus, the present results are consistent with the hypothesis that GABAergic tone in SNr plays a role in the regulation of tremulous jaw movements. This research may lead to a better understanding of how parkinsonian symptoms are modulated by SNr GABA mechanisms.

  12. Ketone bodies and brain glutamate and GABA metabolism.

    PubMed

    Daikhin, Y; Yudkoff, M

    1998-01-01

    The effects of ketone bodies on brain metabolism of glutamate and GABA were studied in three different systems: synaptosomes, cultured astrocytes and the whole animal. In synaptosomes the addition of either acetoacetate or 3-OH-butyrate was associated with diminished consumption of glutamate via transamination to aspartate and increased formation of labelled GABA from either L-[2H5-2,3,3,4, 4]glutamine or L-[15N]glutamine. There was no effect of ketone bodies on synaptosomal GABA transamination. An increase of total forebrain GABA and a diminution of aspartate was noted when mice were injected intraperitoneally with 3-OH-butyrate. In cultured astrocytes the addition of acetoacetate to the medium was associated with a significantly enhanced rate of citrate production and with a diminution in the rate of conversion of [15N]glutamate to [15N]aspartate. These data are consistent with the hypothesis that the metabolism of ketone bodies to acetyl-CoA results in a diminution of the pool of brain oxaloacetate, which is consumed in the citrate synthetase reaction (oxaloacetate + acetyl-CoA --> citrate). As less oxaloacetate is available to the aspartate aminotransferase reaction, thereby lowering the rate of glutamate transamination, more glutamate becomes accessible to the glutamate decarboxylase pathway, thereby favoring the synthesis of GABA.

  13. Neurotransmitters as food supplements: the effects of GABA on brain and behavior

    PubMed Central

    Boonstra, Evert; de Kleijn, Roy; Colzato, Lorenza S.; Alkemade, Anneke; Forstmann, Birte U.; Nieuwenhuis, Sander

    2015-01-01

    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex. The food supplement version of GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer benefits beyond a placebo effect. Currently, the mechanism of action behind these products is unknown. It has long been thought that GABA is unable to cross the blood–brain barrier (BBB), but the studies that have assessed this issue are often contradictory and range widely in their employed methods. Accordingly, future research needs to establish the effects of oral GABA administration on GABA levels in the human brain, for example using magnetic resonance spectroscopy. There is some evidence in favor of a calming effect of GABA food supplements, but most of this evidence was reported by researchers with a potential conflict of interest. We suggest that any veridical effects of GABA food supplements on brain and cognition might be exerted through BBB passage or, more indirectly, via an effect on the enteric nervous system. We conclude that the mechanism of action of GABA food supplements is far from clear, and that further work is needed to establish the behavioral effects of GABA. PMID:26500584

  14. Neurotransmitters as food supplements: the effects of GABA on brain and behavior.

    PubMed

    Boonstra, Evert; de Kleijn, Roy; Colzato, Lorenza S; Alkemade, Anneke; Forstmann, Birte U; Nieuwenhuis, Sander

    2015-01-01

    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex. The food supplement version of GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer benefits beyond a placebo effect. Currently, the mechanism of action behind these products is unknown. It has long been thought that GABA is unable to cross the blood-brain barrier (BBB), but the studies that have assessed this issue are often contradictory and range widely in their employed methods. Accordingly, future research needs to establish the effects of oral GABA administration on GABA levels in the human brain, for example using magnetic resonance spectroscopy. There is some evidence in favor of a calming effect of GABA food supplements, but most of this evidence was reported by researchers with a potential conflict of interest. We suggest that any veridical effects of GABA food supplements on brain and cognition might be exerted through BBB passage or, more indirectly, via an effect on the enteric nervous system. We conclude that the mechanism of action of GABA food supplements is far from clear, and that further work is needed to establish the behavioral effects of GABA.

  15. Neural Stem Cell or Human Induced Pluripotent Stem Cell-derived GABA-ergic Progenitor Cell Grafting in an Animal Model of Chronic Temporal Lobe Epilepsy

    PubMed Central

    Upadhya, Dinesh; Hattiangady, Bharathi; Shetty, Geetha A.; Zanirati, Gabriele; Kodali, Maheedhar; Shetty, Ashok K.

    2016-01-01

    Grafting of neural stem cells (NSCs) or GABA-ergic progenitor cells (GPCs) into the hippocampus could offer an alternative therapy to hippocampal resection in patients with drug-resistant chronic epilepsy, which afflicts >30% of temporal lobe epilepsy (TLE) cases. Multipotent, self-renewing NSCs could be expanded from multiple regions of the developing and adult brain, human embryonic stem cells (hESCs), and human induced pluripotent stem cells (hiPSCs). On the other hand, GPCs could be generated from the medial and lateral ganglionic eminences of the embryonic brain and from hESCs and hiPSCs. To provide comprehensive methodologies involved in testing the efficacy of transplantation of NSCs and GPCs in a rat model of chronic TLE, NSCs derived from the rat medial ganglionic eminence (MGE) and MGE-like GPCs derived from hiPSCs are taken as examples in this unit. The topics comprise description of the required materials, reagents and equipment, methods for obtaining rat MGE-NSCs and hiPSC-derived MGE-like GPCs in culture, generation of chronically epileptic rats, intrahippocampal grafting procedure, post-grafting evaluation of the effects of grafts on spontaneous recurrent seizures and cognitive and mood impairments, analyses of the yield and the fate of graft-derived cells, and the effects of grafts on the host hippocampus. PMID:27532817

  16. Gamma-hydroxybutyric acid (GHB) and the mesoaccumbens reward circuit: evidence for GABA(B) receptor-mediated effects.

    PubMed

    Pistis, M; Muntoni, A L; Pillolla, G; Perra, S; Cignarella, G; Melis, M; Gessa, G L

    2005-01-01

    Gamma-hydroxybutyric acid (GHB) is a short-chain fatty acid naturally occurring in the mammalian brain, which recently emerged as a major recreational drug of abuse. GHB has multiple neuronal mechanisms including activation of both the GABA(B) receptor, and a distinct GHB-specific receptor. This complex GHB-GABA(B) receptor interaction is probably responsible for the multifaceted pharmacological, behavioral and toxicological profile of GHB. Drugs of abuse exert remarkably similar effects upon reward-related circuits, in particular the mesolimbic dopaminergic system and the nucleus accumbens (NAc). We used single unit recordings in vivo from urethane-anesthetized rats to characterize the effects of GHB on evoked firing in NAc "shell" neurons and on spontaneous activity of antidromically identified dopamine (DA) cells located in the ventral tegmental area. GHB was studied in comparison with the GABA(B) receptor agonist baclofen and antagonist (2S)(+)-5,5-dimethyl-2-morpholineacetic acid (SCH50911). Additionally, we utilized a GHB analog, gamma-(p-methoxybenzil)-gamma-hydroxybutyric acid (NCS-435), devoid of GABA(B) binding properties, but with high affinity for specific GHB binding sites. In common with other drugs of abuse, GHB depressed firing in NAc neurons evoked by the stimulation of the basolateral amygdala. On DA neurons, GHB exerted heterogeneous effects, which were correlated to the baseline firing rate of the cells but led to a moderate stimulation of the DA system. All GHB actions were mediated by GABA(B) receptors, since they were blocked by SCH50911 and were not mimicked by NCS-435. Our study indicates that the electrophysiological profile of GHB is close to typical drugs of abuse: both inhibition of NAc neurons and moderate to strong stimulation of DA transmission are distinctive features of diverse classes of abused drugs. Moreover, it is concluded that addictive and rewarding properties of GHB do not necessarily involve a putative high affinity GHB

  17. The depolarizing action of GABA in cultured hippocampal neurons is not due to the absence of ketone bodies.

    PubMed

    Waddell, Jaylyn; Kim, Jimok; Alger, Bradley E; McCarthy, Margaret M

    2011-01-01

    Two recent reports propose that the depolarizing action of GABA in the immature brain is an artifact of in vitro preparations in which glucose is the only energy source. The authors argue that this does not mimic the physiological environment because the suckling rats use ketone bodies and pyruvate as major sources of metabolic energy. Here, we show that availability of physiologically relevant levels of ketone bodies has no impact on the excitatory action of GABA in immature cultured hippocampal neurons. Addition of β-hydroxybutyrate (BHB), the primary ketone body in the neonate rat, affected neither intracellular calcium elevation nor membrane depolarizations induced by the GABA-A receptor agonist muscimol, when assessed with calcium imaging or perforated patch-clamp recording, respectively. These results confirm that the addition of ketone bodies to the extracellular environment to mimic conditions in the neonatal brain does not reverse the chloride gradient and therefore render GABA hyperpolarizing. Our data are consistent with the existence of a genuine "developmental switch" mechanism in which GABA goes from having a predominantly excitatory role in immature cells to a predominantly inhibitory one in adults.

  18. Robust Induction of DARPP32-Expressing GABAergic Striatal Neurons from Human Pluripotent Stem Cells.

    PubMed

    Fjodorova, Marija; Li, Meng

    2018-01-01

    Efficient generation of disease relevant neuronal subtypes from human pluripotent stem cells (PSCs) is fundamental for realizing their promise in disease modeling, pharmaceutical drug screening and cell therapy. Here we describe a step-by-step protocol for directing the differentiation of human embryonic and induced PSCs (hESCs and hiPSCs, respectively) toward medium spiny neurons, the type of cells that are preferentially lost in Huntington's disease patients. This method is based on a novel concept of Activin A-dependent induction of the lateral ganglionic/striatal fate using a simple monolayer culture paradigm under chemically defined conditions. Transplantable medium spiny neuron progenitors amenable for cryopreservation are produced in less than 20 days, which differentiate and mature into a high yield of dopamine- and cAMP-regulated phosphoprotein, Mr 32 kDa (DARPP32) expressing gamma-aminobutyric acid (GABA)-ergic neurons in vitro and in the adult rat brain after transplantation. This method has been validated in multiple hESC and hiPSC lines, and is independent of the regime for PSC maintenance.

  19. Periaqueductal Gray Afferents Synapse onto Dopamine and GABA Neurons In the Rat Ventral Tegmental Area

    PubMed Central

    Omelchenko, Natalia; Sesack, Susan R.

    2009-01-01

    The midbrain central gray (periaqueductal gray; PAG) mediates defensive behaviors and is implicated in the rewarding effects of opiate drugs. Projections from the PAG to the ventral tegmental area (VTA) suggest that this region might also regulate behaviors involving motivation and cognition. However, studies have not yet examined the morphological features of PAG axons in the VTA or whether they synapse onto dopamine (DA) or GABA neurons. In this study, we injected anterograde tracers into the rat PAG and used immunoperoxidase to visualize the projections to the VTA. Immunogold-silver labeling for tyrosine hydroxylase (TH) or GABA was then used to identify the phenotype of innervated cells. Electron microscopic examination of the VTA revealed axons labeled anterogradely from the PAG, including myelinated and unmyelinated fibers and axon varicosities, some of which formed identifiable synapses. Approximately 55% of these synaptic contacts were of the symmetric (presumably inhibitory) type; the rest were asymmetric (presumably excitatory). These findings are consistent with the presence of both GABA and glutamate projection neurons in the PAG. Some PAG axons contained dense-cored vesicles indicating the presence of neuropeptides in addition to classical neurotransmitters. PAG projections synapsed onto both DA and GABA cells with no obvious selectivity, providing the first anatomical evidence for these direct connections. The results suggest a diverse nature of PAG physiological actions on midbrain neurons. Moreover, as both the VTA and PAG are implicated in the reinforcing actions of opiates, our findings provide a potential substrate for some of the rewarding effects of these drugs. PMID:19885830

  20. Demonstration of neuron-glia transfer of precursors for GABA biosynthesis in a co-culture system of dissociated mouse cerebral cortex.

    PubMed

    Leke, Renata; Bak, Lasse K; Schousboe, Arne; Waagepetersen, Helle S

    2008-12-01

    Co-cultures of neurons and astrocytes were prepared from dissociated embryonic mouse cerebral cortex and cultured for 7 days. To investigate if these cultures may serve as a functional model system to study neuron-glia interaction with regard to GABA biosynthesis, the cells were incubated either in media containing [U-(13)C]glutamine (0.1, 0.3 and 0.5 mM) or 1 mM acetate plus 2.5 mM glucose plus 1 mM lactate. In the latter case one of the 3 substrates was uniformly (13)C labeled. Cellular contents and (13)C labeling of glutamate, GABA, aspartate and glutamine were determined in the cells after an incubation period of 2.5 h. The GABA biosynthetic machinery exhibited the expected complexity with regard to metabolic compartmentation and involvement of TCA cycle activity as seen in other culture systems containing GABAergic neurons. Metabolism of acetate clearly demonstrated glial synthesis of glutamine and its transfer to the neuronal compartment. It is concluded that this co-culture system serves as a reliable model in which functional and pharmacological aspects of GABA biosynthesis can be investigated.

  1. Comparative analysis of Met-enkephalin, galanin and GABA immunoreactivity in the developing trout preoptic-hypophyseal system.

    PubMed

    Rodríguez Díaz, M A; Candal, E; Santos-Durán, G N; Adrio, F; Rodríguez-Moldes, I

    2011-08-01

    We studied the organization of Met-enkephalin-containing cells and fibers in the developing preoptic-hypophyseal system of the brown trout (Salmo trutta fario) by immunohistochemistry and determined the relationship of these cells and fibers to the galaninergic and GABAergic systems. Met-enkephalin immunoreactivity was observed in cells in the preoptic area, the hypothalamus and the pituitary of late larvae. In the hypophysis, a few Met-enkephalin-containing cells were present in all divisions of the adenohypophysis, and some immunoreactive fibers were present in the interdigitations of the neural lobe with the proximal pars distalis. Concurrently, GABAergic fibers innervated the anterior and posterior neural lobe. Galanin cells coexisted with Met-enkephalin cells in neuronal groups of the preoptic-hypophyseal system. Galaninergic and GABAergic fibers innervated the preoptic and hypothalamic areas, but GABAergic fibers containing galanin were not observed. These results indicate that Met-enkephalin, galanin and GABA may modulate neuroendocrine activities in the preoptic area, hypothalamus and pituitary during the transition from larval to juvenile period. To better know how the development of the trout preoptic-hypophyseal system takes place, we studied the patterns of cell proliferation and expression of Pax6, a conserved transcription factor involved in the hypophysis development. Pax6 expressing cells and proliferating cells were present in the Rathke's pouch, the hypothalamus and the hypophysis of early larvae. In late larvae, Pax6 expression was no longer observed in these areas, and the density of proliferating cells largely decreased throughout development, although they remained in the hypophysis of late larvae and juveniles, suggesting that Pax6 might play an important role in the early regionalization of the pituitary in the trout. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. GABA and homovanillic acid in the plasma of Schizophrenic and bipolar I patients.

    PubMed

    Arrúe, Aurora; Dávila, Ricardo; Zumárraga, Mercedes; Basterreche, Nieves; González-Torres, Miguel A; Goienetxea, Biotza; Zamalloa, Maria I; Anguiano, Juan B; Guimón, José

    2010-02-01

    We have determined the plasma (p) concentration of gamma-aminobutyric acid (GABA) and the dopamine metabolite homovanillic acid (HVA), and the pHVA/pGABA ratio in schizophrenic and bipolar patients. The research was undertaken in a geographic area with an ethnically homogeneous population. The HVA plasma concentrations were significantly elevated in the schizophrenic patients compared to the bipolar patients. The levels of pGABA was significantly lower in the two groups of patients compared to the control group, while the pHVA/pGABA ratio was significantly greater in the both groups of patients compared to the controls. As the levels of pHVA and pGABA are partially under genetic control it is better to compare their concentrations within an homogeneous population. The values of the ratio pHVA/pGABA are compatible with the idea of an abnormal dopamine-GABA interaction in schizophrenic and bipolar patients. The pHVA/pGABA ratio may be a good peripheral marker in psychiatric research.

  3. Exogenous γ-aminobutyric acid (GABA) affects pollen tube growth via modulating putative Ca2+-permeable membrane channels and is coupled to negative regulation on glutamate decarboxylase

    PubMed Central

    Yu, Guang-Hui; Zou, Jie; Feng, Jing; Peng, Xiong-Bo; Wu, Ju-You; Wu, Ying-Liang; Palanivelu, Ravishankar; Sun, Meng-Xiang

    2014-01-01

    γ-Aminobutyric acid (GABA) is implicated in pollen tube growth, but the molecular and cellular mechanisms that it mediates are largely unknown. Here, it is shown that exogenous GABA modulates putative Ca2+-permeable channels on the plasma membranes of tobacco pollen grains and pollen tubes. Whole-cell voltage-clamp experiments and non-invasive micromeasurement technology (NMT) revealed that the influx of Ca2+ increases in pollen tubes in response to exogenous GABA. It is also demonstrated that glutamate decarboxylase (GAD), the rate-limiting enzyme of GABA biosynthesis, is involved in feedback controls of Ca2+-permeable channels to fluctuate intracellular GABA levels and thus modulate pollen tube growth. The findings suggest that GAD activity linked with Ca2+-permeable channels relays an extracellular GABA signal and integrates multiple signal pathways to modulate tobacco pollen tube growth. Thus, the data explain how GABA mediates the communication between the style and the growing pollen tubes. PMID:24799560

  4. Oxytocin Depolarizes Fast-Spiking Hilar Interneurons and Induces GABA Release onto Mossy Cells of the Rat Dentate Gyrus

    PubMed Central

    Harden, Scott W.; Frazier, Charles J.

    2016-01-01

    Delivery of exogenous oxytocin (OXT) to central oxytocin receptors (OXT-Rs) is currently being investigated as a potential treatment for conditions such as post-traumatic stress disorder (PTSD), depression, social anxiety, and autism spectrum disorder (ASD). Despite significant research implicating central OXT signaling in modulation of mood, affect, social behavior, and stress response, relatively little is known about the cellular and synaptic mechanisms underlying these complex actions, particularly in brain regions which express the OXT-R but lie outside of the hypothalamus (where OXT-synthesizing neurons reside). We report that bath application of low concentrations of the selective OXT-R agonist Thr4,Gly7-OXT (TGOT) reliably and robustly drives GABA release in the dentate gyrus in an action potential dependent manner. Additional experiments led to identification of a small subset of small hilar interneurons that are directly depolarized by acute application of TGOT. From a physiological perspective, TGOT-responsive hilar interneurons have high input resistance, rapid repolarization velocity during an action potential, and a robust afterhyperpolarization. Further, they fire irregularly (or stutter) in response to moderate depolarization, and fire quickly with minimal spike frequency accommodation in response to large current injections. From an anatomical perspective, TGOT responsive hilar interneurons have dense axonal arborizations in the hilus that were found close proximity with mossy cell somata and/or proximal dendrites, and also invade the granule cell layer. Further, they have primary dendrites that always extend into the granule cell layer, and sometimes have clear arborizations in the molecular layer. Overall, these data reveal a novel site of action for OXT in an important limbic circuit, and represent a significant step towards better understanding how endogenous OXT may modulate flow of information in hippocampal networks. PMID:27068005

  5. Oxytocin depolarizes fast-spiking hilar interneurons and induces GABA release onto mossy cells of the rat dentate gyrus.

    PubMed

    Harden, Scott W; Frazier, Charles J

    2016-09-01

    Delivery of exogenous oxytocin (OXT) to central oxytocin receptors (OXT-Rs) is currently being investigated as a potential treatment for conditions such as post-traumatic stress disorder (PTSD), depression, social anxiety, and autism spectrum disorder (ASD). Despite significant research implicating central OXT signaling in modulation of mood, affect, social behavior, and stress response, relatively little is known about the cellular and synaptic mechanisms underlying these complex actions, particularly in brain regions which express the OXT-R but lie outside of the hypothalamus (where OXT-synthesizing neurons reside). We report that bath application of low concentrations of the selective OXT-R agonist Thr4,Gly7-OXT (TGOT) reliably and robustly drives GABA release in the dentate gyrus in an action potential dependent manner. Additional experiments led to identification of a small subset of small hilar interneurons that are directly depolarized by acute application of TGOT. From a physiological perspective, TGOT-responsive hilar interneurons have high input resistance, rapid repolarization velocity during an action potential, and a robust afterhyperpolarization. Further, they fire irregularly (or stutter) in response to moderate depolarization, and fire quickly with minimal spike frequency accommodation in response to large current injections. From an anatomical perspective, TGOT responsive hilar interneurons have dense axonal arborizations in the hilus that were found in close proximity with mossy cell somata and/or proximal dendrites, and also invade the granule cell layer. Further, they have primary dendrites that always extend into the granule cell layer, and sometimes have clear arborizations in the molecular layer. Overall, these data reveal a novel site of action for OXT in an important limbic circuit, and represent a significant step towards better understanding how endogenous OXT may modulate flow of information in hippocampal networks. © 2016 Wiley

  6. Molecular dynamics investigation of Cl(-) transport through the closed and open states of the 2α12β2γ2 GABA(A) receptor.

    PubMed

    Xie, Hong-Bo; Wang, Jian; Sha, Yu; Cheng, Mao-Sheng

    2013-01-01

    The α1β2γ2 gamma-aminobutyric type A receptor (GABA(A)R) is one of the most widely expressed GABA(A)R subtypes in the mammalian brain. GABA(A)Rsbelonging to the Cys-loop superfamily of ligand-gated ion channels have been identified as key targets for many clinical drugs, and the motions that govern the gating mechanism are still not well understood. In this study, an open-state GABA(A)R was constructed using the structure of the glutamate-gated chloride channel (GluCl), which has a high sequence identity to GABA(A)R. A closed-state model was constructed using the structure of the nicotinic acetylcholine receptor (nAChR). Molecular dynamics simulations of the open-state and closed-state GABA(A)R were performed. We calculated the electrostatic potential of the two conformations, the pore radius of the two ion channels and the root-mean-square fluctuation. We observed the presence of two positively charged girdles around the ion channel and found flexible regions in the GABA(A)R. Then, the free-energy of chloride ion permeations through the closed-state and open-state G GABA(A)R has been estimated using adaptive biasing force (ABF) simulation. For the closed-state G GABA(A)R, we observed two major energy barriers for chloride ion translocation in the transmembrane domain (TMD). For the open-state GABA(A)R, there was only one energy barrier formed by two Thr261 (α1), two Thr255 (β2) and one Thr271 (γ2). By using ABF simulation, the overall free-energy profile is obtained for Cl(-) transporting through GABA(A)R, which gives a complete map of the ion channel of Cl(-) permeation. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Dietary Restriction Affects Neuronal Response Property and GABA Synthesis in the Primary Visual Cortex.

    PubMed

    Yang, Jinfang; Wang, Qian; He, Fenfen; Ding, Yanxia; Sun, Qingyan; Hua, Tianmiao; Xi, Minmin

    2016-01-01

    Previous studies have reported inconsistent effects of dietary restriction (DR) on cortical inhibition. To clarify this issue, we examined the response properties of neurons in the primary visual cortex (V1) of DR and control groups of cats using in vivo extracellular single-unit recording techniques, and assessed the synthesis of inhibitory neurotransmitter GABA in the V1 of cats from both groups using immunohistochemical and Western blot techniques. Our results showed that the response of V1 neurons to visual stimuli was significantly modified by DR, as indicated by an enhanced selectivity for stimulus orientations and motion directions, decreased visually-evoked response, lowered spontaneous activity and increased signal-to-noise ratio in DR cats relative to control cats. Further, it was shown that, accompanied with these changes of neuronal responsiveness, GABA immunoreactivity and the expression of a key GABA-synthesizing enzyme GAD67 in the V1 were significantly increased by DR. These results demonstrate that DR may retard brain aging by increasing the intracortical inhibition effect and improve the function of visual cortical neurons in visual information processing. This DR-induced elevation of cortical inhibition may favor the brain in modulating energy expenditure based on food availability.

  8. Cytosolic Accumulation of L-Proline Disrupts GABA-Ergic Transmission through GAD Blockade.

    PubMed

    Crabtree, Gregg W; Park, Alan J; Gordon, Joshua A; Gogos, Joseph A

    2016-10-04

    Proline dehydrogenase (PRODH), which degrades L-proline, resides within the schizophrenia-linked 22q11.2 deletion suggesting a role in disease. Supporting this, elevated L-proline levels have been shown to increase risk for psychotic disorders. Despite the strength of data linking PRODH and L-proline to neuropsychiatric diseases, targets of disease-relevant concentrations of L-proline have not been convincingly described. Here, we show that Prodh-deficient mice with elevated CNS L-proline display specific deficits in high-frequency GABA-ergic transmission and gamma-band oscillations. We find that L-proline is a GABA-mimetic and can act at multiple GABA-ergic targets. However, at disease-relevant concentrations, GABA-mimesis is limited to competitive blockade of glutamate decarboxylase leading to reduced GABA production. Significantly, deficits in GABA-ergic transmission are reversed by enhancing net GABA production with the clinically relevant compound vigabatrin. These findings indicate that accumulation of a neuroactive metabolite can lead to molecular and synaptic dysfunction and help to understand mechanisms underlying neuropsychiatric disease. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  9. Opiate alkaloids antagonize postsynaptic glycine and GABA responses: correlation with convulsant action.

    PubMed

    Werz, M A; Macdonald, R L

    1982-03-18

    Opiate alkaloid and opioid peptide actions on spontaneous neuronal activity and postsynaptic amino acid responsiveness were assessed using intracellular recording techniques applied to murine spinal cord neurons in primary dissociated cell culture. Application of opiates was by superfusion and amino acids by iontophoresis. Glycine and GABA but not glutamate responses were antagonized by the opiate alkaloids. Since opiate effects on glycine and GABA responses were not naloxone-reversible, only weakly stereospecific, and not produced by the opioid peptide [D-Ala2]-Met-enkephalinamide, it is unlikely that these effects were mediated by opiate receptors. Opiate depression of glycine inhibition was correlated with the induction of paroxysmal depolarizations in cultured spinal cord neurons, suggesting that antagonism of inhibitory amino acid transmission may underlie the convulsant actions of high concentrations of the opiate alkaloids.

  10. Determination of γ-Aminobutyric Acid (GABA) in Rambutan Fruit cv. Rongrian by HPLC-ELSD and Separation of GABA from Rambutan Fruit Using Dowex 50W-X8 Column.

    PubMed

    Meeploy, Maneerat; Deewatthanawong, Rujira

    2016-03-01

    A high-performance liquid chromatography method coupled with an evaporative light scattering detector (ELSD) was validated for the determination of γ-aminobutyric acid (GABA) in rambutan fruit without any sample pretreatment or derivatization. In the concentration range of 0.05-1.0 mg/mL GABA, the ELSD response was linear with a correlation coefficient (r) >0.999. Limit of detection and limit of quantitation were found to be 0.7 and 2.0 µg/mL, respectively. The method enabled the complete separation of GABA in the aqueous extract of rambutan flesh from the impurity peaks at 45.7 min. The recoveries of sample added GABA were obtained in the range of 92.0-99.3%. Intraday and interday relative standard deviations were <5.3%. Repeatability of the extraction process showed the acceptable precision. From the analysis of GABA content in rambutan flesh, 0.71 ± 0.23 mg of GABA was found in 1 g fresh weight. The recovery of GABA after passing through the Dowex 50W-X8 column was 96.65%. The analytical methodology could be potentially applied to the detection and quantification of GABA in other fruits and complex matrices when a sufficient quantity is available. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. GABA neurons and the mechanisms of network oscillations: implications for understanding cortical dysfunction in schizophrenia.

    PubMed

    Gonzalez-Burgos, Guillermo; Lewis, David A

    2008-09-01

    Synchronization of neuronal activity in the neocortex may underlie the coordination of neural representations and thus is critical for optimal cognitive function. Because cognitive deficits are the major determinant of functional outcome in schizophrenia, identifying their neural basis is important for the development of new therapeutic interventions. Here we review the data suggesting that phasic synaptic inhibition mediated by specific subtypes of cortical gamma-aminobutyric acid (GABA) neurons is essential for the production of synchronized network oscillations. We also discuss evidence indicating that GABA neurotransmission is altered in schizophrenia and propose mechanisms by which such alterations can decrease the strength of inhibitory connections in a cell-type-specific manner. We suggest that some alterations observed in the neocortex of schizophrenia subjects may be compensatory responses that partially restore inhibitory synaptic efficacy. The findings of altered neural synchrony and impaired cognitive function in schizophrenia suggest that such compensatory responses are insufficient and that interventions aimed at augmenting the efficacy of GABA neurotransmission might be of therapeutic value.

  12. GABA-B receptor activation and conflict behavior

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ketelaars, C.E.J.; Bollen, E.L.; Rigter, H.

    1988-01-01

    Baclofen and oxazepam enhance extinction of conflict behavior in the Geller-Seifter test while baclofen and diazepam release punished behavior in Vogel's conflict test. In order to investigate the possibility that the effect of the selective GABA-B receptor agonist baclofen is mediated indirectly via the GABA-A/benzodiazepine receptor complex, the effect of pretreatment of rats with baclofen on (/sup 3/H)-diazepam binding to washed and unwashed cortical and cerebellar membranes of rats has been studied. Baclofen pretreatment increase Bmax in washed cerebellar membranes when bicuculline was present in the incubation mixture. No effect was seen in cortical membranes. The present results render itmore » unlikely that the effect of baclofen on extinction of conflict behavior and punished drinking is mediated via the GABA-A/benzodiazepine receptor complex. 50 references, 1 figure, 4 tables.« less

  13. Distribution of CaMKIIα expression in the brain in vivo, studied by CaMKIIα-GFP mice

    PubMed Central

    Wang, Xinjun; Zhang, Chunzhao; Szábo, Gábor; Sun, Qian-Quan

    2013-01-01

    To facilitate the study of the CaMKIIα function in vivo, a CaMKIIα-GFP transgenic mouse line was generated. Here, our goal is to provide the first neuroanatomical characterization of GFP expression in the CNS of this line of mouse. Overall, CaMKIIα -GFP expression is strong and highly heterogeneous, with the dentate gyrus of the hippocampus as the most abundantly expressed region. In the hippocampus, around 70% of granule and pyramidal neurons expressed strong GFP. In the neocortex, presumed pyramidal neurons were GFP positive: around 32% of layer II/III and 35% of layer VI neurons expressed GFP, and a lower expression rate was found in other layers. In the thalamus and hypothalamus, strong GFP signals were detected in the neuropil. GFP-positive cells were also found in many other regions such as the spinal trigeminal nucleus, cerebellum and basal ganglia. We further compared the GFP expression with specific antibody staining for CaMKIIα and GABA. We found that GFP+ neurons were mostly positive for CaMKIIα-IR throughout the brain, with some exceptions throughout the brain, especially in the deeper layers of neocortex. GFP and GABA-IR marked distinct neuronal populations in most brain regions with the exception of granule cells in the olfactory bulb, purkinje cells in the cerebellar, and some layer I cells in neocortex. In conclusion, GFP expression in the CaMKIIα-GFP mice is similar to the endogenous expression of CaMKIIα protein, thus these mice can be used in in vivo and in vitro physiological studies in which visualization of CaMKIIα- neuronal populations is required. PMID:23632380

  14. Alleviation in the rat of a GABA-induced reduction in food intake and growth.

    PubMed

    Tews, J K; Repa, J J; Harper, A E

    1984-07-01

    Cold exposure and diet dilution which stimulate food intake of normal rats lessened depressions of food intake and growth induced by dietary GABA. During a 3-day adaptation to the cold, rats fed a diet containing 4.5% GABA lost weight; thereafter, food intake and growth rate differed little from those of cold control rats and were usually greater than those of normal rats fed GABA. Hepatic GABA-aminotransferase activity of cold-exposed rats fed the GABA diet increased to about twice that of normal control rats. Rats fed a control diet diluted by half with cellulose ate 50% more of this diet than of the undiluted diet but gained only 20% less weight. Rats ate twice as much of a diluted, 9% GABA diet as of an undiluted, 4.5% GABA diet (thus doubling their GABA intake) and gained three times as much weight. A novel food (condensed milk) barely lessened the adverse responses to GABA. These results show that conditions requiring rats to increase their food intake in order to maintain body weight can also increase their acceptance of a diet high in GABA.

  15. Epigenetic regulation of dorsal raphe GABA(B1a) associated with isolation-induced abnormal responses to social stimulation in mice.

    PubMed

    Araki, Ryota; Hiraki, Yosuke; Nishida, Shoji; Kuramoto, Nobuyuki; Matsumoto, Kinzo; Yabe, Takeshi

    2016-02-01

    In isolation-reared mice, social encounter stimulation induces locomotor hyperactivity and activation of the dorsal raphe nucleus (DRN), suggesting that dysregulation of dorsal raphe function may be involved in abnormal behaviors. In this study, we examined the involvement of dorsal raphe GABAergic dysregulation in the abnormal behaviors of isolation-reared mice. We also studied an epigenetic mechanism underlying abnormalities of the dorsal raphe GABAergic system. Both mRNA and protein levels of GABA(B1a), a GABA(B) receptor subunit, were increased in the DRN of isolation-reared mice, compared with these levels in group-reared mice. In contrast, mRNA levels for other GABAergic system-related genes (GABA(A) receptor α1, β2 and γ2 subunits, GABA(B) receptor 1b and 2 subunits, and glutamate decarboxylase 67 and 65) were unchanged. Intra-DRN microinjection of 0.06 nmol baclofen (a GABA(B) receptor agonist) exacerbated encounter-induced hyperactivity and aggressive behavior, while microinjection of 0.3 nmol phaclofen (a GABA(B) receptor antagonist) attenuated encounter-induced hyperactivity and aggressive behavior in isolation-reared mice. Furthermore, microinjection of 0.06 nmol baclofen elicited encounter-induced hyperactivity in group-reared mice. Neither baclofen nor phaclofen affected immobility time in the forced swim test and hyperactivity in a novel environment of isolation reared mice. Bisulfite sequence analyses revealed that the DNA methylation level of the CpG island around the transcription start site (TSS) of GABA(B1a) was decreased in the DRN of isolation-reared mice. Chromatin immunoprecipitation analysis showed that histone H3 was hyperacetylated around the TSS of GABA(B1a) in the DRN of isolation-reared mice. These findings indicate that an increase in dorsal raphe GABA(B1a) expression via epigenetic regulation is associated with abnormal responses to social stimulation such as encounter-induced hyperactivity and aggressive behavior in isolation

  16. Ribosomal binding site sequences and promoters for expressing glutamate decarboxylase and producing γ-aminobutyrate in Corynebacterium glutamicum.

    PubMed

    Shi, Feng; Luan, Mingyue; Li, Yongfu

    2018-04-18

    Glutamate decarboxylase (GAD) converts L-glutamate (Glu) into γ-aminobutyric acid (GABA). Corynebacterium glutamicum that expresses exogenous GAD gene, gadB2 or gadB1, can synthesize GABA from its own produced Glu. To enhance GABA production in C. glutamicum, ribosomal binding site (RBS) sequence and promoter were searched and optimized for increasing the expression efficiency of gadB2. R4 exhibited the highest strength among RBS sequences tested, with 6 nt the optimal aligned spacing (AS) between RBS and start codon. This combination of RBS sequence and AS contributed to gadB2 expression, increased GAD activity by 156% and GABA production by 82% compared to normal strong RBS and AS combination. Then, a series of native promoters were selected for transcribing gadB2 under optimal RBS and AS combination. P dnaK , P dtsR , P odhI and P clgR expressed gadB2 and produced GABA as effectively as widely applied P tuf and P cspB promoters and more effectively than P sod promoter. However, each native promoter did not work as well as the synthetic strong promoter P tacM , which produced 20.2 ± 0.3 g/L GABA. Even with prolonged length and bicistronic architecture, the strength of P dnaK did not enhance. Finally, gadB2 and mutant gadB1 were co-expressed under the optimal promoter and RBS combination, thus converted Glu into GABA completely and improved GABA production to more than 25 g/L. This study provides useful promoters and RBS sequences for gene expression in C. glutamicum.

  17. Subcellular fractionation on Percoll gradient of mossy fiber synaptosomes: evoked release of glutamate, GABA, aspartate and glutamate decarboxylase activity in control and degranulated rat hippocampus.

    PubMed

    Taupin, P; Ben-Ari, Y; Roisin, M P

    1994-05-02

    Using discontinuous density gradient centrifugation in isotonic Percoll sucrose, we have characterized two subcellular fractions (PII and PIII) enriched in mossy fiber synaptosomes and two others (SII and SIII) enriched in small synaptosomes. These synaptosomal fractions were compared with those obtained from adult hippocampus irradiated at neonatal stage to destroy granule cells and their mossy fibers. Synaptosomes were viable as judged by their ability to release aspartate, glutamate and GABA upon K+ depolarization. After irradiation, compared to the control values, the release of glutamate and GABA was decreased by 57 and 74% in the PIII fraction, but not in the other fractions and the content of glutamate, aspartate and GABA was also decreased in PIII fraction by 62, 44 and 52% respectively. These results suggest that mossy fiber (MF) synaptosomes contain and release glutamate and GABA. Measurement of the GABA synthesizing enzyme, glutamate decarboxylase, exhibited no significant difference after irradiation, suggesting that GABA is not synthesized by this enzyme in mossy fibers.

  18. GABA predicts inhibition of frequency-specific oscillations in schizophrenia.

    PubMed

    Rowland, Laura M; Edden, Richard A E; Kontson, Kimberly; Zhu, He; Barker, Peter B; Hong, L Elliot

    2013-01-01

    This study is the first to show a relationship between in-vivo brain gamma-amino butyric acid (GABA) levels and auditory inhibitory electrophysiological measures in schizophrenia. Results revealed a strong association between GABA levels and gating of the theta-alpha and beta activities in schizophrenia.

  19. GABA(B) receptors, schizophrenia and sleep dysfunction: a review of the relationship and its potential clinical and therapeutic implications.

    PubMed

    Kantrowitz, Joshua; Citrome, Leslie; Javitt, Daniel

    2009-08-01

    Evidence for an intrinsic relationship between sleep, cognition and the symptomatic manifestations of schizophrenia is accumulating. This review presents evidence for the possible utility of GABA(B) receptor agonists for the treatment of subjective and objective sleep abnormalities related to schizophrenia. At the phenotypic level, sleep disturbance occurs in 16-30% of patients with schizophrenia and is related to reduced quality of life and poor coping skills. On the neurophysiological level, studies suggest that sleep deficits reflect a core component of schizophrenia. Specifically, slow-wave sleep deficits, which are inversely correlated with cognition scores, are seen. Moreover, sleep plays an increasingly well documented role in memory consolidation in schizophrenia. Correlations of slow-wave sleep deficits with impaired reaction time and declarative memory have also been reported. Thus, both behavioural insomnia and sleep architecture are critical therapeutic targets in patients with schizophrenia. However, long-term treatment with antipsychotics often results in residual sleep dysfunction and does not improve slow-wave sleep, and adjunctive GABA(A) receptor modulators, such as benzodiazepines and zolpidem, can impair sleep architecture and cognition in schizophrenia. GABA(B) receptor agonists have therapeutic potential in schizophrenia. These agents have minimal effect on rapid eye movement sleep while increasing slow-wave sleep. Preclinical associations with increased expression of genes related to slow-wave sleep production and circadian rhythm function have also been reported. GABA(B) receptor deficits result in a sustained hyperdopaminergic state and can be reversed by a GABA(B) receptor agonist. Genetic, postmortem and electrophysiological studies also associate GABA(B) receptors with schizophrenia. While studies thus far have not shown significant effects, prior focus on the use of GABA(B) receptor agonists has been on the positive symptoms of

  20. Actions of insecticides on the insect GABA receptor complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bermudez, I.; Hawkins, C.A.; Taylor, A.M.

    1991-01-01

    The actions of insecticides on the insect gamma-aminobutyric acid (GABA) receptor were investigated using (35S)t-butylbicyclophosphorothionate (( 35S)TBPS) binding and voltage-clamp techniques. Specific binding of (35S)TBPS to a membrane homogenate derived from the brain of Locusta migratoria locusts is characterised by a Kd value of 79.3 {plus minus} 2.9 nM and a Bmax value of 1770 {plus minus} 40 fmol/mg protein. (35S)TBPS binding is inhibited by mM concentrations of barbiturates and benzodiazepines. In contrast dieldrin, ivermectin, lindane, picrotoxin and TBPS are inhibitors of (35S)TBPS binding at the nanomolar range. Bicuculline, baclofen and pyrethroid insecticides have no effect on (35S)TBPS binding. Thesemore » results are similar to those obtained in electrophysiological studies of the current elicited by GABA in both Locusta and Periplaneta americana central neurones. Noise analysis of the effects of lindane, TBPS, dieldrin and picrotoxin on the cockroach GABA responses reveals that these compounds decrease the variance of the GABA-induced current but have no effect on its mean open time. All these compounds, with the exception of dieldrin, significantly decrease the conductance of GABA-evoked single current.« less

  1. Regulation of the Hippocampal Network by VGLUT3-Positive CCK- GABAergic Basket Cells

    PubMed Central

    Fasano, Caroline; Rocchetti, Jill; Pietrajtis, Katarzyna; Zander, Johannes-Friedrich; Manseau, Frédéric; Sakae, Diana Y.; Marcus-Sells, Maya; Ramet, Lauriane; Morel, Lydie J.; Carrel, Damien; Dumas, Sylvie; Bolte, Susanne; Bernard, Véronique; Vigneault, Erika; Goutagny, Romain; Ahnert-Hilger, Gudrun; Giros, Bruno; Daumas, Stéphanie; Williams, Sylvain; El Mestikawy, Salah

    2017-01-01

    Hippocampal interneurons release the inhibitory transmitter GABA to regulate excitation, rhythm generation and synaptic plasticity. A subpopulation of GABAergic basket cells co-expresses the GABA/glycine vesicular transporters (VIAAT) and the atypical type III vesicular glutamate transporter (VGLUT3); therefore, these cells have the ability to signal with both GABA and glutamate. GABAergic transmission by basket cells has been extensively characterized but nothing is known about the functional implications of VGLUT3-dependent glutamate released by these cells. Here, using VGLUT3-null mice we observed that the loss of VGLUT3 results in a metaplastic shift in synaptic plasticity at Shaeffer’s collaterals – CA1 synapses and an altered theta oscillation. These changes were paralleled by the loss of a VGLUT3-dependent inhibition of GABAergic current in CA1 pyramidal layer. Therefore presynaptic type III metabotropic could be activated by glutamate released from VGLUT3-positive interneurons. This putative presynaptic heterologous feedback mechanism inhibits local GABAergic tone and regulates the hippocampal neuronal network. PMID:28559797

  2. In Vivo Measurements of Glutamate, GABA, and NAAG in Schizophrenia

    PubMed Central

    Rowland, Laura M.

    2013-01-01

    The major excitatory and inhibitory neurotransmitters, glutamate (Glu) and gamma-aminobutyric acid (GABA), respectively, are implicated in the pathophysiology of schizophrenia. N-acetyl-aspartyl-glutamate (NAAG), a neuropeptide that modulates the Glu system, may also be altered in schizophrenia. This study investigated GABA, Glu + glutamine (Glx), and NAAG levels in younger and older subjects with schizophrenia. Forty-one subjects, 21 with chronic schizophrenia and 20 healthy controls, participated in this study. Proton magnetic resonance spectroscopy (1H-MRS) was used to measure GABA, Glx, and NAAG levels in the anterior cingulate (AC) and centrum semiovale (CSO) regions. NAAG in the CSO was higher in younger schizophrenia subjects compared with younger control subjects. The opposite pattern was observed in the older groups. Glx was reduced in the schizophrenia group irrespective of age group and brain region. There was a trend for reduced AC GABA in older schizophrenia subjects compared with older control subjects. Poor attention performance was correlated to lower AC GABA levels in both groups. Higher levels of CSO NAAG were associated with greater negative symptom severity in schizophrenia. These results provide support for altered glutamatergic and GABAergic function associated with illness course and cognitive and negative symptoms in schizophrenia. The study also highlights the importance of studies that combine MRS measurements of NAAG, GABA, and Glu for a more comprehensive neurochemical characterization of schizophrenia. PMID:23081992

  3. In vivo measurements of glutamate, GABA, and NAAG in schizophrenia.

    PubMed

    Rowland, Laura M; Kontson, Kimberly; West, Jeffrey; Edden, Richard A; Zhu, He; Wijtenburg, S Andrea; Holcomb, Henry H; Barker, Peter B

    2013-09-01

    The major excitatory and inhibitory neurotransmitters, glutamate (Glu) and gamma-aminobutyric acid (GABA), respectively, are implicated in the pathophysiology of schizophrenia. N-acetyl-aspartyl-glutamate (NAAG), a neuropeptide that modulates the Glu system, may also be altered in schizophrenia. This study investigated GABA, Glu + glutamine (Glx), and NAAG levels in younger and older subjects with schizophrenia. Forty-one subjects, 21 with chronic schizophrenia and 20 healthy controls, participated in this study. Proton magnetic resonance spectroscopy ((1)H-MRS) was used to measure GABA, Glx, and NAAG levels in the anterior cingulate (AC) and centrum semiovale (CSO) regions. NAAG in the CSO was higher in younger schizophrenia subjects compared with younger control subjects. The opposite pattern was observed in the older groups. Glx was reduced in the schizophrenia group irrespective of age group and brain region. There was a trend for reduced AC GABA in older schizophrenia subjects compared with older control subjects. Poor attention performance was correlated to lower AC GABA levels in both groups. Higher levels of CSO NAAG were associated with greater negative symptom severity in schizophrenia. These results provide support for altered glutamatergic and GABAergic function associated with illness course and cognitive and negative symptoms in schizophrenia. The study also highlights the importance of studies that combine MRS measurements of NAAG, GABA, and Glu for a more comprehensive neurochemical characterization of schizophrenia.

  4. Neuroimaging studies of GABA in schizophrenia: a systematic review with meta-analysis.

    PubMed

    Egerton, A; Modinos, G; Ferrera, D; McGuire, P

    2017-06-06

    Data from animal models and from postmortem studies suggest that schizophrenia is associated with brain GABAergic dysfunction. The extent to which this is reflected in data from in vivo studies of GABA function in schizophrenia is unclear. The Medline database was searched to identify articles published until 21 October 2016. The search terms included GABA, proton magnetic resonance spectroscopy ( 1 H-MRS), positron emission tomography (PET), single photon emission computed tomography (SPECT), schizophrenia and psychosis. Sixteen GABA 1 H-MRS studies (538 controls, 526 patients) and seven PET/SPECT studies of GABA A /benzodiazepine receptor (GABA A /BZR) availability (118 controls, 113 patients) were identified. Meta-analyses of 1 H-MRS GABA in the medial prefrontal cortex (mPFC), parietal/occipital cortex (POC) and striatum did not show significant group differences (mFC: g=-0.3, 409 patients, 495 controls, 95% confidence interval (CI): -0.6 to 0.1; POC: g=-0.3, 139 patients, 111 controls, 95% CI: -0.9 to 0.3; striatum: g=-0.004, 123 patients, 95 controls, 95% CI: -0.7 to 0.7). Heterogeneity across studies was high (I 2 >50%), and this was not explained by subsequent moderator or meta-regression analyses. There were insufficient PET/SPECT receptor availability studies for meta-analyses, but a systematic review did not suggest replicable group differences in regional GABA A /BZR availability. The current literature does not reveal consistent alterations in in vivo GABA neuroimaging measures in schizophrenia, as might be hypothesized from animal models and postmortem data. The analysis highlights the need for further GABA neuroimaging studies with improved methodology and addressing potential sources of heterogeneity.

  5. A novel GABA(A) alpha 5 receptor inhibitor with therapeutic potential.

    PubMed

    Ling, István; Mihalik, Balázs; Etherington, Lori-An; Kapus, Gábor; Pálvölgyi, Adrienn; Gigler, Gábor; Kertész, Szabolcs; Gaál, Attila; Pallagi, Katalin; Kiricsi, Péter; Szabó, Éva; Szénási, Gábor; Papp, Lilla; Hársing, László G; Lévay, György; Spedding, Michael; Lambert, Jeremy J; Belelli, Delia; Barkóczy, József; Volk, Balázs; Simig, Gyula; Gacsályi, István; Antoni, Ferenc A

    2015-10-05

    Novel 2,3-benzodiazepine and related isoquinoline derivatives, substituted at position 1 with a 2-benzothiophenyl moiety, were synthesized to produce compounds that potently inhibited the action of GABA on heterologously expressed GABAA receptors containing the alpha 5 subunit (GABAA α5), with no apparent affinity for the benzodiazepine site. Substitutions of the benzothiophene moiety at position 4 led to compounds with drug-like properties that were putative inhibitors of extra-synaptic GABAA α5 receptors and had substantial blood-brain barrier permeability. Initial characterization in vivo showed that 8-methyl-5-[4-(trifluoromethyl)-1-benzothiophen-2-yl]-1,9-dihydro-2H-[1,3]oxazolo[4,5-h][2,3]benzodiazepin-2-one was devoid of sedative, pro-convulsive or motor side-effects, and enhanced the performance of rats in the object recognition test. In summary, we have discovered a first-in-class GABA-site inhibitor of extra-synaptic GABAA α5 receptors that has promising drug-like properties and warrants further development. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Enhancement of γ-aminobutyric acid production in recombinant Corynebacterium glutamicum by co-expressing two glutamate decarboxylase genes from Lactobacillus brevis.

    PubMed

    Shi, Feng; Jiang, Junjun; Li, Yongfu; Li, Youxin; Xie, Yilong

    2013-11-01

    γ-Aminobutyric acid (GABA), a non-protein amino acid, is a bioactive component in the food, feed and pharmaceutical fields. To establish an effective single-step production system for GABA, a recombinant Corynebacterium glutamicum strain co-expressing two glutamate decarboxylase (GAD) genes (gadB1 and gadB2) derived from Lactobacillus brevis Lb85 was constructed. Compared with the GABA production of the gadB1 or gadB2 single-expressing strains, GABA production by the gadB1-gadB2 co-expressing strain increased more than twofold. By optimising urea supplementation, the total production of L-glutamate and GABA increased from 22.57 ± 1.24 to 30.18 ± 1.33 g L⁻¹, and GABA production increased from 4.02 ± 0.95 to 18.66 ± 2.11 g L⁻¹ after 84-h cultivation. Under optimal urea supplementation, L-glutamate continued to be consumed, GABA continued to accumulate after 36 h of fermentation, and the pH level fluctuated. GABA production increased to a maximum level of 27.13 ± 0.54 g L⁻¹ after 120-h flask cultivation and 26.32 g L⁻¹ after 60-h fed-batch fermentation. The conversion ratio of L-glutamate to GABA reached 0.60-0.74 mol mol⁻¹. By co-expressing gadB1 and gadB2 and optimising the urea addition method, C. glutamicum was genetically improved for de novo biosynthesis of GABA from its own accumulated L-glutamate.

  7. Altered cortical GABA neurotransmission in schizophrenia: insights into novel therapeutic strategies.

    PubMed

    Stan, Ana D; Lewis, David A

    2012-06-01

    Altered markers of cortical GABA neurotransmission are among the most consistently observed abnormalities in postmortem studies of schizophrenia. The altered markers are particularly evident between the chandelier class of GABA neurons and their synaptic targets, the axon initial segment (AIS) of pyramidal neurons. For example, in the dorsolateral prefrontal cortex of subjects with schizophrenia immunoreactivity for the GABA membrane transporter is decreased in presynaptic chandelier neuron axon terminals, whereas immunoreactivity for the GABAA receptor α2 subunit is increased in postsynaptic AIS. Both of these molecular changes appear to be compensatory responses to a presynaptic deficit in GABA synthesis, and thus could represent targets for novel therapeutic strategies intended to augment the brain's own compensatory mechanisms. Recent findings that GABA inputs from neocortical chandelier neurons can be powerfully excitatory provide new ideas about the role of these neurons in the pathophysiology of cortical dysfunction in schizophrenia, and consequently in the design of pharmacological interventions.

  8. Neurophysiology of space travel: energetic solar particles cause cell type-specific plasticity of neurotransmission.

    PubMed

    Lee, Sang-Hun; Dudok, Barna; Parihar, Vipan K; Jung, Kwang-Mook; Zöldi, Miklós; Kang, Young-Jin; Maroso, Mattia; Alexander, Allyson L; Nelson, Gregory A; Piomelli, Daniele; Katona, István; Limoli, Charles L; Soltesz, Ivan

    2017-07-01

    In the not too distant future, humankind will embark on one of its greatest adventures, the travel to distant planets. However, deep space travel is associated with an inevitable exposure to radiation fields. Space-relevant doses of protons elicit persistent disruptions in cognition and neuronal structure. However, whether space-relevant irradiation alters neurotransmission is unknown. Within the hippocampus, a brain region crucial for cognition, perisomatic inhibitory control of pyramidal cells (PCs) is supplied by two distinct cell types, the cannabinoid type 1 receptor (CB 1 )-expressing basket cells (CB 1 BCs) and parvalbumin (PV)-expressing interneurons (PVINs). Mice subjected to low-dose proton irradiation were analyzed using electrophysiological, biochemical and imaging techniques months after exposure. In irradiated mice, GABA release from CB 1 BCs onto PCs was dramatically increased. This effect was abolished by CB 1 blockade, indicating that irradiation decreased CB 1 -dependent tonic inhibition of GABA release. These alterations in GABA release were accompanied by decreased levels of the major CB 1 ligand 2-arachidonoylglycerol. In contrast, GABA release from PVINs was unchanged, and the excitatory connectivity from PCs to the interneurons also underwent cell type-specific alterations. These results demonstrate that energetic charged particles at space-relevant low doses elicit surprisingly selective long-term plasticity of synaptic microcircuits in the hippocampus. The magnitude and persistent nature of these alterations in synaptic function are consistent with the observed perturbations in cognitive performance after irradiation, while the high specificity of these changes indicates that it may be possible to develop targeted therapeutic interventions to decrease the risk of adverse events during interplanetary travel.

  9. Dietary Restriction Affects Neuronal Response Property and GABA Synthesis in the Primary Visual Cortex

    PubMed Central

    Sun, Qingyan; Hua, Tianmiao; Xi, Minmin

    2016-01-01

    Previous studies have reported inconsistent effects of dietary restriction (DR) on cortical inhibition. To clarify this issue, we examined the response properties of neurons in the primary visual cortex (V1) of DR and control groups of cats using in vivo extracellular single-unit recording techniques, and assessed the synthesis of inhibitory neurotransmitter GABA in the V1 of cats from both groups using immunohistochemical and Western blot techniques. Our results showed that the response of V1 neurons to visual stimuli was significantly modified by DR, as indicated by an enhanced selectivity for stimulus orientations and motion directions, decreased visually-evoked response, lowered spontaneous activity and increased signal-to-noise ratio in DR cats relative to control cats. Further, it was shown that, accompanied with these changes of neuronal responsiveness, GABA immunoreactivity and the expression of a key GABA-synthesizing enzyme GAD67 in the V1 were significantly increased by DR. These results demonstrate that DR may retard brain aging by increasing the intracortical inhibition effect and improve the function of visual cortical neurons in visual information processing. This DR-induced elevation of cortical inhibition may favor the brain in modulating energy expenditure based on food availability. PMID:26863207

  10. GABA+ levels in postmenopausal women with mild-to-moderate depression

    PubMed Central

    Wang, Zhensong; Zhang, Aiying; Zhao, Bin; Gan, Jie; Wang, Guangbin; Gao, Fei; Liu, Bo; Gong, Tao; Liu, Wen; Edden, Richard A.E.

    2016-01-01

    Abstract Background: It is increasingly being recognized that alterations of the GABAergic system are implicated in the pathophysiology of depression. This study aimed to explore in vivo gamma-aminobutyric acid (GABA) levels in the anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC) and posterior-cingulate cortex (PCC) of postmenopausal women with depression using magnetic resonance spectroscopy (1H-MRS). Methods: Nineteen postmenopausal women with depression and thirteen healthy controls were enrolled in the study. All subjects underwent 1H-MRS of the ACC/mPFC and PCC using the “MEGA Point Resolved Spectroscopy Sequence” (MEGA-PRESS) technique. The severity of depression was assessed by 17-item Hamilton Depression Scale (HAMD). Quantification of MRS data was performed using Gannet program. Differences of GABA+ levels from patients and controls were tested using one-way analysis of variance. Spearman correlation coefficients were used to evaluate the linear associations between GABA+ levels and HAMD scores, as well as estrogen levels. Results: Significantly lower GABA+ levels were detected in the ACC/mPFC of postmenopausal women with depression compared to healthy controls (P = 0.002). No significant correlations were found between 17-HAMD/14-HAMA and GABA+ levels, either in ACC/mPFC (P = 0.486; r = 0.170/P = 0.814; r = −0.058) or PCC (P = 0.887; r = 0.035/ P = 0.987; r = −0.004) in the patients; there is also no significant correlation between GABA+ levels and estrogen levels in patients group (ACC/mPFC: P = 0.629, r = −0.018; PCC: P = 0.861, r = 0.043). Conclusion: Significantly lower GABA+ levels were found in the ACC/mPFC of postmenopausal women with depression, suggesting that the dysfunction of the GABAergic system may also be involved in the pathogenesis of depression in postmenopausal women. PMID:27684829

  11. Increased GABA Levels in Medial Prefrontal Cortex of Young Adults with Narcolepsy

    PubMed Central

    Kim, Seog Ju; Lyoo, In Kyoon; Lee, Yujin S.; Sung, Young Hoon; Kim, Hengjun J.; Kim, Jihyun H.; Kim, Kye Hyun; Jeong, Do-Un

    2008-01-01

    Study Objectives: To explore absolute concentrations of brain metabolites including gamma amino-butyric acid (GABA) in the medial prefrontal cortex and basal ganglia of young adults with narcolepsy. Design: Proton magnetic resonance (MR) spectroscopy centered on the medial prefrontal cortex and the basal ganglia was acquired. The absolute concentrations of brain metabolites including GABA and glutamate were assessed and compared between narcoleptic patients and healthy comparison subjects. Setting: Sleep and Chronobiology Center at Seoul National University Hospital; A high strength 3.0 Tesla MR scanner in the Department of Radiology at Seoul National University Hospital. Patients or Participants: Seventeen young adults with a sole diagnosis of HLA DQB1 0602 positive narcolepsy with cataplexy (25.1 ± 4.6 years old) and 17 healthy comparison subjects (26.8 ± 4.8 years old). Interventions: N/A. Measurements and Results: Relative to comparison subjects, narcoleptic patients had higher GABA concentration in the medial prefrontal cortex (t = 4.10, P <0.001). Narcoleptic patients with nocturnal sleep disturbance had higher GABA concentration in the medial prefrontal cortex than those without nocturnal sleep disturbance (t = 2.45, P= 0.03), but had lower GABA concentration than comparison subjects (t = 2.30, P = 0.03). Conclusions: The current study reports that young adults with narcolepsy had a higher GABA concentration in the medial prefrontal cortex, which was more prominent in patients without nocturnal sleep disturbance. Our findings suggest that the medial prefrontal GABA level may be increased in narcolepsy, and the increased medial prefrontal GABA might be a compensatory mechanism to reduce nocturnal sleep disturbances in narcolepsy. Citation: Kim SJ; Lyoo IK; Lee YS; Sung YH; Kim HJ; Kim JH; Kim KH; Jeong DU. Increased GABA levels in medial prefrontal cortex of young adults with narcolepsy. SLEEP 2008;31(3):342-347. PMID:18363310

  12. Stiff person syndrome associated anti-amphiphysin antibodies reduce GABA associated [Ca(2+)]i rise in embryonic motoneurons.

    PubMed

    Geis, C; Beck, M; Jablonka, S; Weishaupt, A; Toyka, K V; Sendtner, M; Sommer, C

    2009-10-01

    Autoantibodies to the synaptic protein amphiphysin play a crucial pathogenic role in paraneoplastic stiff-person syndrome. Impairment of GABAergic inhibition is the presumed pathophysiological mechanism by which these autoantibodies become pathogenic. Here we used calcium imaging on rat embryonic motor neurons to investigate whether antibodies to amphiphysin directly hinder GABAergic signaling. We found that the immunoglobulin G fraction from a patient with stiff-person syndrome, containing high titer antibodies to amphiphysin and inducing stiffness in rats upon passive transfer, reduced GABA-induced calcium influx in embryonic motor neurons. Depletion of the anti-amphiphysin fraction from the patient's IgG by selective affinity chromatography abolished this effect, showing its specificity for amphiphysin. Quantification of the surface expression of the Na(+)/K(+)/2Cl(2-) cotransporter revealed a reduction after incubation with anti-amphiphysin IgG, which is concordant with a lower intracellular chloride concentration and thus impairment of GABA mediated calcium influx. Thus, anti-amphiphysin antibodies exert a direct effect on GABA signaling, which is likely to contribute to the pathogenesis of SPS.

  13. Local GABA receptor blockade reveals hindlimb responses in the SI forelimb-stump representation of neonatally amputated rats.

    PubMed

    Pluto, Charles P; Lane, Richard D; Rhoades, Robert W

    2004-07-01

    In adult rats that sustained forelimb amputation on the day of birth, there are numerous multi-unit recording sites in the forelimb-stump representation of primary somatosensory cortex (SI) that also respond to cutaneous stimulation of the hindlimb when cortical receptors for GABA are blocked. These normally suppressed hindlimb inputs originate in the SI hindlimb representation and synapse in the dysgranular cortex before exciting SI forelimb-stump neurons. In our previous studies, GABA (A + B) receptor blockade was achieved by topically applying a bicuculline methiodide/saclofen solution (BMI/SAC) to the cortical surface. This treatment blocks receptors throughout SI and does not allow determination of where along the above circuit the GABA-mediated suppression of hindlimb information occurs. In this study, focal injections of BMI/SAC were delivered to three distinct cortical regions that are involved in the hindlimb-to-forelimb-stump pathway. Blocking GABA receptors in the SI hindlimb representation and in the dysgranular cortex was largely ineffective in revealing hindlimb inputs ( approximately 10% of hindlimb inputs were revealed in both cases). In contrast, when the blockade was targeted at forelimb-stump recording sites, >80% of hindlimb inputs were revealed. Thus GABAergic interneurons within the forelimb-stump representation suppress the expression of reorganized hindlimb inputs to the region. A circuit model incorporating these and previous observations is presented and discussed.

  14. GABA Neurons and the Mechanisms of Network Oscillations: Implications for Understanding Cortical Dysfunction in Schizophrenia

    PubMed Central

    Gonzalez-Burgos, Guillermo; Lewis, David A.

    2008-01-01

    Synchronization of neuronal activity in the neocortex may underlie the coordination of neural representations and thus is critical for optimal cognitive function. Because cognitive deficits are the major determinant of functional outcome in schizophrenia, identifying their neural basis is important for the development of new therapeutic interventions. Here we review the data suggesting that phasic synaptic inhibition mediated by specific subtypes of cortical γ-aminobutyric acid (GABA) neurons is essential for the production of synchronized network oscillations. We also discuss evidence indicating that GABA neurotransmission is altered in schizophrenia and propose mechanisms by which such alterations can decrease the strength of inhibitory connections in a cell-type–specific manner. We suggest that some alterations observed in the neocortex of schizophrenia subjects may be compensatory responses that partially restore inhibitory synaptic efficacy. The findings of altered neural synchrony and impaired cognitive function in schizophrenia suggest that such compensatory responses are insufficient and that interventions aimed at augmenting the efficacy of GABA neurotransmission might be of therapeutic value. PMID:18586694

  15. Cortical deficits of glutamic acid decarboxylase 67 expression in schizophrenia: clinical, protein, and cell type-specific features.

    PubMed

    Curley, Allison A; Arion, Dominique; Volk, David W; Asafu-Adjei, Josephine K; Sampson, Allan R; Fish, Kenneth N; Lewis, David A

    2011-09-01

    Cognitive deficits in schizophrenia are associated with altered activity of the dorsolateral prefrontal cortex, which has been attributed to lower expression of the 67 kDa isoform of glutamic acid decarboxylase (GAD67), the major γ-aminobutyric acid (GABA)-synthesizing enzyme. However, little is known about the relationship of prefrontal GAD67 mRNA levels and illness severity, translation of the transcript into protein, and protein levels in axon terminals, the key site of GABA production and function. Quantitative polymerase chain reaction was used to measure GAD67 mRNA levels in postmortem specimens of dorsolateral prefrontal cortex from subjects with schizophrenia and matched comparison subjects with no known history of psychiatric or neurological disorders (N=42 pairs). In a subset of this cohort in which potential confounds of protein measures were controlled (N=19 pairs), Western blotting was used to quantify tissue levels of GAD67 protein in tissue. In five of these pairs, multilabel confocal immunofluorescence was used to quantify GAD67 protein levels in the axon terminals of parvalbumin-containing GABA neurons, which are known to have low levels of GAD67 mRNA in schizophrenia. GAD67 mRNA levels were significantly lower in schizophrenia subjects (by 15%), but transcript levels were not associated with predictors or measures of illness severity or chronicity. In schizophrenia subjects, GAD67 protein levels were significantly lower in total gray matter (by 10%) and in parvalbumin axon terminals (by 49%). The findings that lower GAD67 mRNA expression is common in schizophrenia, that it is not a consequence of having the illness, and that it leads to less translation of the protein, especially in the axon terminals of parvalbumin-containing neurons, support the hypothesis that lower GABA synthesis in parvalbumin neurons contributes to dorsolateral prefrontal cortex dysfunction and impaired cognition in schizophrenia.

  16. Cortical Gene Expression After a Conditional Knockout of 67 kDa Glutamic Acid Decarboxylase in Parvalbumin Neurons.

    PubMed

    Georgiev, Danko; Yoshihara, Toru; Kawabata, Rika; Matsubara, Takurou; Tsubomoto, Makoto; Minabe, Yoshio; Lewis, David A; Hashimoto, Takanori

    2016-07-01

    In the cortex of subjects with schizophrenia, expression of glutamic acid decarboxylase 67 (GAD67), the enzyme primarily responsible for cortical GABA synthesis, is reduced in the subset of GABA neurons that express parvalbumin (PV). This GAD67 deficit is accompanied by lower cortical levels of other GABA-associated transcripts, including GABA transporter-1, PV, brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B, somatostatin, GABAA receptor α1 subunit, and KCNS3 potassium channel subunit mRNAs. In contrast, messenger RNA (mRNA) levels for glutamic acid decarboxylase 65 (GAD65), another enzyme for GABA synthesis, are not altered. We tested the hypothesis that this pattern of GABA-associated transcript levels is secondary to the GAD67 deficit in PV neurons by analyzing cortical levels of these GABA-associated mRNAs in mice with a PV neuron-specific GAD67 knockout. Using in situ hybridization, we found that none of the examined GABA-associated transcripts had lower cortical expression in the knockout mice. In contrast, PV, BDNF, KCNS3, and GAD65 mRNA levels were higher in the homozygous mice. In addition, our behavioral test battery failed to detect a change in sensorimotor gating or working memory, although the homozygous mice exhibited increased spontaneous activities. These findings suggest that reduced GAD67 expression in PV neurons is not an upstream cause of the lower levels of GABA-associated transcripts, or of the characteristic behaviors, in schizophrenia. In PV neuron-specific GAD67 knockout mice, increased levels of PV, BDNF, and KCNS3 mRNAs might be the consequence of increased neuronal activity secondary to lower GABA synthesis, whereas increased GAD65 mRNA might represent a compensatory response to increase GABA synthesis. © The Author 2016. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  17. Expression of membrane progesterone receptors (mPRs) in rat peripheral glial cell membranes and their potential role in the modulation of cell migration and protein expression.

    PubMed

    Castelnovo, Luca F; Magnaghi, Valerio; Thomas, Peter

    2017-09-28

    The role played by progestogens in modulating Schwann cell pathophysiology is well established. Progestogens exert their effects in these cells through both classical genomic and non-genomic mechanisms, the latter mediated by the GABA-A receptor. However, there is evidence that other receptors may be involved. Membrane progesterone receptors (mPRs) are novel 7-transmembrane receptors coupled to G proteins that have been characterized in different tissues and cells, including the central nervous system (CNS). The mPRs were shown to mediate some of progestogens' neuroprotective effects in the CNS, and to be upregulated in glial cells after traumatic brain injury. Based on this evidence, this paper investigated the possible involvement of mPRs in mediating progestogen actions in S42 Schwann cells. All five mPR isoforms and progesterone receptor membrane component 1 (PGRMC1) were detected in Schwann cells, and were present on the cell membrane. Progesterone and the mPR-specific agonist, Org-OD-02-0 (02) bound to these membranes, indicating the presence of functional mPRs. The mPR agonist 02 rapidly increased cell migration in an in vitro assay, suggesting a putative role of mPRs in the nerve regeneration process. Treatment with pertussis toxin and 8-Br-cAMP blocked 02-induced cell migration, suggesting this progestogen action is mediated by activation of an inhibitory G protein, leading to a decrease in intracellular cAMP levels. In contrast, long-term mPR activation led to increased expression levels of myelin associated glycoprotein (MAG). Taken together, these findings show that mPRs are present and active in Schwann cells and have a role in modulating their physiological processes. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Mitochondrial carbonic anhydrase in the nervous system: expression in neuronal and glial cells.

    PubMed

    Ghandour, M S; Parkkila, A K; Parkkila, S; Waheed, A; Sly, W S

    2000-11-01

    Carbonic anhydrase (CA) V is a mitochondrial enzyme that has been reported in several tissues of the gastrointestinal tract. In liver, it participates in ureagenesis and gluconeogenesis by providing bicarbonate ions for two other mitochondrial enzymes: carbamyl phosphate synthetase I and pyruvate carboxylase. This study presents evidence of immunohistochemical localization of CA V in the rodent nervous tissue. Polyclonal rabbit antisera against a polypeptide of 17 C-terminal amino acids of rat CA V and against purified recombinant mouse isozyme were used in western blotting and immunoperoxidase stainings. Immunohistochemistry showed that CA V is expressed in astrocytes and neurons but not in oligodendrocytes, which are rich in CA II, or capillary endothelial cells, which express CA IV on their plasma face. The specificity of the immunohistochemical results was confirmed by western blotting, which identified a major 30-kDa polypeptide band of CA V in mouse cerebral cortex, hippocampus, cerebellum, spinal cord, and sciatic nerve. The expression of CA V in astrocytes and neurons suggests that this isozyme has a cell-specific, physiological role in the nervous system. In astrocytes, CA V may play an important role in gluconeogenesis by providing bicarbonate ions for the pyruvate carboxylase. The neuronal CA V could be involved in the regulation of the intramitochondrial calcium level, thus contributing to the stability of the intracellular calcium concentration. CA V may also participate in bicarbonate ion-induced GABA responses by regulating the bicarbonate homeostasis in neurons, and its inhibition could be the basis of some neurotropic effects of carbonic anhydrase inhibitors.

  19. The role of GABA in NMDA-dependent long term depression (LTD) of rat medial vestibular nuclei.

    PubMed

    Grassi, S; Della Torre, G; Capocchi, G; Zampolini, M; Pettorossi, V E

    1995-11-20

    The role of GABA in NMDA-dependent long term depression (LTD) in the medial vestibular nuclei (MVN) was studied on rat brainstem slices. High frequency stimulation (HFS) of the primary vestibular afferents induces a long lasting reduction of the polysynaptic (N2) component of the field potentials recorded in the dorsal portion of the MVN. The induction but not the maintenance of this depression was abolished by AP5, a specific blocking agent for glutamate NMDA receptors. The involvement of GABA in mediating the depression was checked by applying the GABAA and GABAB receptor antagonists, bicuculline and saclofen, before and after HFS. Under bicuculline and saclofen perfusion, HFS provoked a slight potentiation of the N2 wave, while the N2 depression clearly emerged after drug wash-out. This indicates that GABA is not involved in inducing the long term effect, but it is necessary for its expression. Similarly, the LTD reversed and a slight potentiation appeared when both drugs were administered after its induction. Most of these effects were due to the bicuculline, suggesting that GABAA receptors contribute to LTD more than GABAB do. According to our results, it is unlikely that the long lasting vestibular depression is the result of a homosynaptic LTD. On the contrary, our findings suggest that the depression is due to an enhancement of the GABA inhibitory effect, caused by an HFS dependent increase in gabaergic interneuron activity, which resets vestibular neuron excitability at a lower level.

  20. Temperature dependence and GABA modulation of (TH)triazolam binding in the rat brain

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Earle, M.E.; Concas, A.; Wamsley, J.K.

    1987-07-27

    The hypnotic triazolam (TZ), a triazolobenzodiazepine displays a short physiological half life and has been used for the treatment of insomnia related to anxiety states. The authors major objectives were the direct measurement of the temperature dependence and the gamma-aminobutyric acid (GABA) effect of (TH)TZ binding in the rat brain. Saturation studies showed a shift to lower affinity with increasing temperatures (K/sub d/ = 0.27 +/- 08 nM at 0C; K/sub d/ = 1.96 +/- 0.85 nM at 37C) while the B/sub max/ values remained unchanged (1220 +/- 176 fmoles/mg protein at 0C and 1160 +/- 383 fmoles/mg protein atmore » 37C). Saturation studies of (TH)TZ binding in the presence or absence of GABA (100 M) showed a GABA-shift. At 0C the K/sub d/ values were (K/sub d/ = 0.24 +/- 0.03 nM/-GABA; K/sub d/ = 0.16 +/- 0.04/+GABA) and at 37C the K/sub d/ values were (K/sub d/ = 1.84 +/- 0.44 nM/-GABA; K/sub d/ = 0.95 +/- 0.29 nM/+GABA). In contrast to reported literature, the authors findings show that TZ interacts with benzodiazepine receptors with a temperature dependence and GABA-shift consistent with predicted behavior for benzodiazepine agonists. 20 references, 3 tables.« less

  1. Is plasma GABA level a biomarker of Post-Traumatic Stress Disorder (PTSD) severity? A preliminary study.

    PubMed

    Trousselard, Marion; Lefebvre, Bertrand; Caillet, Lionel; Andruetan, Yann; de Montleau, Franck; Denis, Josiane; Canini, Frédéric

    2016-07-30

    An increased reactivity to the environment is observed in Post-Traumatic Stress Disorder (PTSD). It would be related to impairment of the Gamma Amino Butyric Acid (GABA) neurotransmission. The study aimed to evaluate plasma GABA concentration as a candidate for PTSD severity biomarker. This hypothesis was studied in 17 PTSD patients and 17 healthy Controls using classic and emotional Stroop paradigms. Plasma GABA concentrations were assessed before and after both Stroop tests to evaluate GABA basal tone and GABA reactivity (change in GABAp), respectively. During baseline, PTSD had lower plasma GABA concentrations than the Controls. After the Stroop conflicts GABA reactivity was also lower in PTSD than in the Controls. The GABA baseline tone was negatively correlated with the severity of the PTSD symptoms. This relation was only marginally observed for GABA reactivity. The results produced a trend due to the small size of the sample compared to the number of statistical results given. Altogether, the reduced GABA concentration observed in PTSD could be considered as a possible biomarker for PTSD severity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  2. GABA/benzodiazepine receptor complex in long-sleep and short-sleep mice

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marley, R.J.

    LS mice are more sensitive to benzodiazepine-induced anesthesia; however, the two lines do not differ in their hypothermic response to flurazepam. SS mice are more resistant to 3-mercaptopropionic acid-induced seizures and more sensitive to the anticonvulsant effects of benzodiazepines. The various correlates of GABA and benzodiazepine actions probably are the results of different mechanisms of action and/or differential regional control. Bicuculline competition for /sup 3/H-GABA binding sites is greater in SS cerebellar tissue and /sup 3/H-flunitrazepam binding is greater in the mid-brain region of LS mice. GABA enhancement of /sup 3/H-flunitrazepma binding is greater in SS mice. Ethanol also enhancesmore » /sup 3/H-flunitrazepam binding and increases the levels of /sup 3/H-flunitrazepam binding above those observed for GABA. Using correlational techniques on data from LS and SS mice and several inbred mouse strains, it was demonstrated that a positive relationship exists between the degree of receptor coupling within the GABA receptor complex and the degree of resistance to seizures.« less

  3. Disruption of the GABA shunt affects mitochondrial respiration and virulence in the cereal pathogen Fusarium graminearum.

    PubMed

    Bönnighausen, Jakob; Gebhard, Daniel; Kröger, Cathrin; Hadeler, Birgit; Tumforde, Thomas; Lieberei, Reinhard; Bergemann, Jörg; Schäfer, Wilhelm; Bormann, Jörg

    2015-12-01

    The cereal pathogen Fusarium graminearum threatens food and feed production worldwide. It reduces the yield and poisons the remaining kernels with mycotoxins, notably deoxynivalenol (DON). We analyzed the importance of gamma-aminobutanoic acid (GABA) metabolism for the life cycle of this fungal pathogen. GABA metabolism in F. graminearum is partially regulated by the global nitrogen regulator AreA. Genetic disruption of the GABA shunt by deletion of two GABA transaminases renders the pathogen unable to utilize the plant stress metabolites GABA and putrescine. The mutants showed increased sensitivity against oxidative stress, GABA accumulation in the mycelium, downregulation of two key enzymes of the TCA cycle, disturbed potential gradient in the mitochondrial membrane and lower mitochondrial oxygen consumption. In contrast, addition of GABA to the wild type resulted in its rapid turnover and increased mitochondrial steady state oxygen consumption. GABA concentrations are highly upregulated in infected wheat tissues. We conclude that GABA is metabolized by the pathogen during infection increasing its energy production, whereas the mutants accumulate GABA intracellularly resulting in decreased energy production. Consequently, the GABA mutants are strongly reduced in virulence but, because of their DON production, are able to cross the rachis node. © 2015 John Wiley & Sons Ltd.

  4. Subchronic toxicity evaluation of γ-aminobutyric acid (GABA) in rats.

    PubMed

    Takeshima, Kazuhito; Yamatsu, Atsushi; Yamashita, Yusuke; Watabe, Kazuya; Horie, Noriko; Masuda, Kazuyuki; Kim, Mujo

    2014-06-01

    γ-Aminobutyric acid (GABA) is an amino acid compound contained in vegetables such as tomatoes and also widely distributed in mammals. GABA acts as an inhibitory neurotransmitter and promotes parasympathetic activity to provide several beneficial effects, for instance, relaxation, anti-stress, and insomnia. GABA, produced via a fermentation process, has been available as a functional food ingredient. As part of a program to assess its safety, GABA was administered by oral gavage at doses of 500, 1250, and 2500mg/kg body weight to groups of 10 male and 10 female Sprague-Dawley rats for 13weeks. Treatment was not associated with the test substance-related mortality and appeared to be well tolerated. There were no toxicologically and statistically significant changes in urinalysis, hematology, clinical chemistry parameters, and in necropsy findings. A few statistically significant changes in food consumption and body weights were noted in the male groups while any significant changes were not noted in female groups. There was no effect of treatment on organ weights or on the results of the histopathological examinations. The results of toxicity evaluation support the safety use of GABA and the potential use as a functional food ingredient. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Engineering the intracellular metabolism of Escherichia coli to produce gamma-aminobutyric acid by co-localization of GABA shunt enzymes.

    PubMed

    Pham, Van Dung; Somasundaram, Sivachandiran; Lee, Seung Hwan; Park, Si Jae; Hong, Soon Ho

    2016-02-01

    To direct the carbon flux from Krebs cycle into the gamma-aminobutyric acid (GABA) shunt pathway for the production of GABA by protein scaffold introduction in Escherichia coli. Escherichia coli was engineered to produce GABA from glucose by the co-localization of enzymes succinate semialdehyde dehydrogenase (GadD), GABA aminotransferase (PuuE) and GABA transporter (GadC) by protein scaffold. 0.7 g GABA l(-1) was produced from 10 g glucose l(-1) while no GABA was produced in wild type E. coli. pH 6 and 30 °C were optimum for GABA production, and GABA concentration increased to 1.12 g GABA l(-1) when 20 g glucose l(-1) was used. When competing metabolic networks were inactivated, GABA increased by 24 % (0.87 g GABA l(-1)). The novel GABA production system was constructed by co-localization of GABA shunt enzymes.

  6. GABA receptor subunit distribution and FMRP-mGluR5 signaling abnormalities in the cerebellum of subjects with schizophrenia, mood disorders, and autism

    PubMed Central

    Fatemi, S. Hossein; Folsom, Timothy D.

    2016-01-01

    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain. GABAergic receptor abnormalities have been documented in several major psychiatric disorders including schizophrenia, mood disorders, and autism. Abnormal expression of mRNA and protein for multiple GABA receptors has also been observed in multiple brain regions leading to alterations in the balance between excitatory/inhibitory signaling in the brain with potential profound consequences for normal cognition and maintenance of mood and perception. Altered expression of GABAA receptor subunits has been documented in Fragile X mental retardation 1 (FMR1) knockout mice, suggesting that loss of its protein product, fragile X mental retardation protein (FMRP), impacts GABAA subunit expression. Recent postmortem studies from our laboratory have shown reduced expression of FMRP in brains of subjects with schizophrenia, bipolar disorder, major depression, and autism. FMRP acts as a translational repressor and, under normal conditions, inhibits metabotropic glutamate receptor 5 (mGluR5)-mediated signaling. In fragile X syndrome (FXS), absence of FMRP is hypothesized to lead to unregulated mGluR5 signaling, ultimately resulting in the behavioral and intellectual impairments associated with this disorder. Our laboratory has identified changes in mGluR5 expression in autism, schizophrenia, and mood disorders. In the current review article, we discuss our postmortem data on GABA receptors, FMRP, and mGluR5 levels and compare our results with other laboratories. Finally, we discuss the interactions between these molecules and the potential for new therapeutic interventions that target these interconnected signaling systems. PMID:25432637

  7. GABA receptor subunit distribution and FMRP-mGluR5 signaling abnormalities in the cerebellum of subjects with schizophrenia, mood disorders, and autism.

    PubMed

    Fatemi, S Hossein; Folsom, Timothy D

    2015-09-01

    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain. GABAergic receptor abnormalities have been documented in several major psychiatric disorders including schizophrenia, mood disorders, and autism. Abnormal expression of mRNA and protein for multiple GABA receptors has also been observed in multiple brain regions leading to alterations in the balance between excitatory/inhibitory signaling in the brain with potential profound consequences for normal cognition and maintenance of mood and perception. Altered expression of GABAA receptor subunits has been documented in fragile X mental retardation 1 (FMR1) knockout mice, suggesting that loss of its protein product, fragile X mental retardation protein (FMRP), impacts GABAA subunit expression. Recent postmortem studies from our laboratory have shown reduced expression of FMRP in the brains of subjects with schizophrenia, bipolar disorder, major depression, and autism. FMRP acts as a translational repressor and, under normal conditions, inhibits metabotropic glutamate receptor 5 (mGluR5)-mediated signaling. In fragile X syndrome (FXS), the absence of FMRP is hypothesized to lead to unregulated mGluR5 signaling, ultimately resulting in the behavioral and intellectual impairments associated with this disorder. Our laboratory has identified changes in mGluR5 expression in autism, schizophrenia, and mood disorders. In the current review article, we discuss our postmortem data on GABA receptors, FMRP, and mGluR5 levels and compare our results with other laboratories. Finally, we discuss the interactions between these molecules and the potential for new therapeutic interventions that target these interconnected signaling systems. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Dose-dependent EEG effects of zolpidem provide evidence for GABA(A) receptor subtype selectivity in vivo.

    PubMed

    Visser, S A G; Wolters, F L C; van der Graaf, P H; Peletier, L A; Danhof, M

    2003-03-01

    Zolpidem is a nonbenzodiazepine GABA(A) receptor modulator that binds in vitro with high affinity to GABA(A) receptors expressing alpha(1) subunits but with relatively low affinity to receptors expressing alpha(2), alpha(3), and alpha(5) subunits. In the present study, it was investigated whether this subtype selectivity could be detected and quantified in vivo. Three doses (1.25, 5, and 25 mg) of zolpidem were administered to rats in an intravenous infusion over 5 min. The time course of the plasma concentrations was determined in conjunction with the change in the beta-frequency range of the EEG as pharmacodynamic endpoint. The concentration-effect relationship of the three doses showed a dose-dependent maximum effect and a dose-dependent potency. The data were analyzed for one- or two-site binding using two pharmacodynamic models based on 1) the descriptive model and 2) a novel mechanism-based pharmacokinetic/pharmacodynamic (PK/PD) model for GABA(A) receptor modulators that aims to separates drug- and system-specific properties, thereby allowing the estimation of in vivo affinity and efficacy. The application of two-site models significantly improved the fits compared with one-site models. Furthermore, in contrast to the descriptive model, the mechanism-based PK/PD model yielded dose-independent estimates for affinity (97 +/- 40 and 33,100 +/- 14,800 ng x ml(-1)). In conclusion, the mechanism-based PK/PD model is able to describe and explain the observed dose-dependent EEG effects of zolpidem and suggests the subtype selectivity of zolpidem in vivo.

  9. Dorsolateral Prefrontal Cortex GABA Concentration in Humans Predicts Working Memory Load Processing Capacity.

    PubMed

    Yoon, Jong H; Grandelis, Anthony; Maddock, Richard J

    2016-11-16

    The discovery of neural mechanisms of working memory (WM) would significantly enhance our understanding of complex human behaviors and guide treatment development for WM-related impairments found in neuropsychiatric conditions and aging. Although the dorsolateral prefrontal cortex (DLPFC) has long been considered critical for WM, we still know little about the neural elements and pathways within the DLPFC that support WM in humans. In this study, we tested whether an individual's DLPFC gamma-aminobutryic acid (GABA) content predicts individual differences in WM task performance using a novel behavioral approach. Twenty-three healthy adults completed a task that measured the unique contribution of major WM components (memory load, maintenance, and distraction resistance) to performance. This was done to address the possibility that components have differing GABA dependencies and the failure to parse WM into components would lead to missing true associations with GABA. The subjects then had their DLPFC GABA content measured by single-voxel proton magnetic spectroscopy. We found that individuals with lower DLPFC GABA showed greater performance degradation with higher load, accounting for 31% of variance, p (corrected) = 0.015. This relationship was component, neurochemical, and brain region specific. DLPFC GABA content did not predict performance sensitivity to other components tested; DLPFC glutamate + glutamine and visual cortical GABA content did not predict load sensitivity. These results confirm the involvement of DLPFC GABA in WM load processing in humans and implicate factors controlling DLPFC GABA content in the neural mechanisms of WM and its impairments. This study demonstrated for the first time that the amount of gamma-aminobutryic acid (GABA), the major inhibitory neurotransmitter of the brain, in an individual's prefrontal cortex predicts working memory (WM) task performance. Given that WM is required for many of the most characteristic cognitive and

  10. The Association Between Clinical Characteristics of Migraine and Brain GABA Levels: An Exploratory Study.

    PubMed

    Aguila, Maria-Eliza R; Rebbeck, Trudy; Leaver, Andrew M; Lagopoulos, Jim; Brennan, Patrick C; Hübscher, Markus; Refshauge, Kathryn M

    2016-10-01

    Migraine is prevalent and disabling yet is poorly understood. One way to better understand migraine is to examine its clinical characteristics and potential biomarkers such as gamma-aminobutyric acid (GABA). The primary objective of this study was to explore whether relevant disease characteristics of migraine are associated with brain GABA levels. Twenty adults fulfilling the established diagnostic criteria for migraine and 20 age- and gender-matched controls completed this cross-sectional study. Pain, central sensitization, negative emotional state, and perceived disability were measured using Short-form McGill Pain Questionnaire-2, Central Sensitization Inventory, Depression Anxiety Stress Scales-21, and Headache Impact Test-6, respectively. Secondary analysis of brain GABA levels of the same cohort measured using proton magnetic resonance spectroscopy was conducted. The migraine group had significantly higher scores than the control group on pain, central sensitization, and disability. Correlation analyses showed fair positive association between GABA levels and pain and central sensitization scores. No association was found between GABA levels and emotional state and disability. These findings are preliminary evidence supporting the use of questionnaires and GABA levels in characterizing migraine better and broadening the diagnostic process. These findings also strengthen the rationale for the role of GABA in migraine pathophysiology and corroborate the potential of GABA as a migraine biomarker. Higher pain and central sensitization scores were associated with increased brain GABA levels in individuals with migraine. These findings offer preliminary evidence for the usefulness of measuring pain and central sensitization in migraine and provide some support for the possible role of GABA in migraine pathophysiology and its potential as a diagnostic marker. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

  11. Enhanced phasic GABA inhibition during the repair phase of stroke: a novel therapeutic target

    PubMed Central

    Paz, Jeanne T.; Wang, Eric Hou Jen; Badgely, Corrine; Olson, Andrew; Micheva, Kristina D.; Wang, Gordon; Lemmens, Robin; Tran, Kevin V.; Nishiyama, Yasuhiro; Liang, Xibin; Hamilton, Scott A.; O’Rourke, Nancy; Smith, Stephen J.; Huguenard, John R.; Bliss, Tonya M.

    2016-01-01

    Abstract Ischaemic stroke is the leading cause of severe long-term disability yet lacks drug therapies that promote the repair phase of recovery. This repair phase of stroke occurs days to months after stroke onset and involves brain remapping and plasticity within the peri-infarct zone. Elucidating mechanisms that promote this plasticity is critical for the development of new therapeutics with a broad treatment window. Inhibiting tonic (extrasynaptic) GABA signalling during the repair phase was reported to enhance functional recovery in mice suggesting that GABA plays an important function in modulating brain repair. While tonic GABA appears to suppress brain repair after stroke, less is known about the role of phasic (synaptic) GABA during the repair phase. We observed an increase in postsynaptic phasic GABA signalling in mice within the peri-infarct cortex specific to layer 5; we found increased numbers of α1 receptor subunit-containing GABAergic synapses detected using array tomography, and an associated increased efficacy of spontaneous and miniature inhibitory postsynaptic currents in pyramidal neurons. Furthermore, we demonstrate that enhancing phasic GABA signalling using zolpidem, a Food and Drug Administration (FDA)-approved GABA-positive allosteric modulator, during the repair phase improved behavioural recovery. These data identify potentiation of phasic GABA signalling as a novel therapeutic strategy, indicate zolpidem’s potential to improve recovery, and underscore the necessity to distinguish the role of tonic and phasic GABA signalling in stroke recovery. PMID:26685158

  12. Enhanced phasic GABA inhibition during the repair phase of stroke: a novel therapeutic target.

    PubMed

    Hiu, Takeshi; Farzampour, Zoya; Paz, Jeanne T; Wang, Eric Hou Jen; Badgely, Corrine; Olson, Andrew; Micheva, Kristina D; Wang, Gordon; Lemmens, Robin; Tran, Kevin V; Nishiyama, Yasuhiro; Liang, Xibin; Hamilton, Scott A; O'Rourke, Nancy; Smith, Stephen J; Huguenard, John R; Bliss, Tonya M; Steinberg, Gary K

    2016-02-01

    Ischaemic stroke is the leading cause of severe long-term disability yet lacks drug therapies that promote the repair phase of recovery. This repair phase of stroke occurs days to months after stroke onset and involves brain remapping and plasticity within the peri-infarct zone. Elucidating mechanisms that promote this plasticity is critical for the development of new therapeutics with a broad treatment window. Inhibiting tonic (extrasynaptic) GABA signalling during the repair phase was reported to enhance functional recovery in mice suggesting that GABA plays an important function in modulating brain repair. While tonic GABA appears to suppress brain repair after stroke, less is known about the role of phasic (synaptic) GABA during the repair phase. We observed an increase in postsynaptic phasic GABA signalling in mice within the peri-infarct cortex specific to layer 5; we found increased numbers of α1 receptor subunit-containing GABAergic synapses detected using array tomography, and an associated increased efficacy of spontaneous and miniature inhibitory postsynaptic currents in pyramidal neurons. Furthermore, we demonstrate that enhancing phasic GABA signalling using zolpidem, a Food and Drug Administration (FDA)-approved GABA-positive allosteric modulator, during the repair phase improved behavioural recovery. These data identify potentiation of phasic GABA signalling as a novel therapeutic strategy, indicate zolpidem's potential to improve recovery, and underscore the necessity to distinguish the role of tonic and phasic GABA signalling in stroke recovery. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.

  13. Activation induced changes in GABA: Functional MRS at 7T with MEGA-sLASER.

    PubMed

    Chen, Chen; Sigurdsson, Hilmar P; Pépés, Sophia E; Auer, Dorothee P; Morris, Peter G; Morgan, Paul S; Gowland, Penny A; Jackson, Stephen R

    2017-08-01

    Functional magnetic resonance spectroscopy (fMRS) has been used to assess the dynamic metabolic responses of the brain to a physiological stimulus non-invasively. However, only limited information on the dynamic functional response of γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain, is available. We aimed to measure the activation-induced changes in GABA unambiguously using a spectral editing method, instead of the conventional direct detection techniques used in previous fMRS studies. The Mescher-Garwood-semi-localised by adiabatic selective refocusing (MEGA-sLASER) sequence was developed at 7T to obtain the time course of GABA concentration without macromolecular contamination. A significant decrease (-12±5%) in the GABA to total creatine ratio (GABA/tCr) was observed in the motor cortex during a period of 10min of hand-clenching, compared to an initial baseline level (GABA/tCr =0.11±0.02) at rest. An increase in the Glx (glutamate and glutamine) to tCr ratio was also found, which is in agreement with previous findings. In contrast, no significant changes in NAA/tCr and tCr were detected. With consistent and highly efficient editing performance for GABA detection and the advantage of visually identifying GABA resonances in the spectra, MEGA-sLASER is demonstrated to be an effective method for studying of dynamic changes in GABA at 7T. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. The Improvement of Sleep by Oral Intake of GABA and Apocynum venetum Leaf Extract.

    PubMed

    Yamatsu, Atsushi; Yamashita, Yusuke; Maru, Isafumi; Yang, Jinwei; Tatsuzaki, Jin; Kim, Mujo

    2015-01-01

    The effects of two food materials, γ-aminobutyric acid (GABA) produced by natural fermentation and Apocynum venetum leaf extract (AVLE), on the improvement of sleep were investigated in humans. The electroencephalogram (EEG) test revealed that oral administration of GABA (100 mg) and AVLE (50 mg) had beneficial effects on sleep. GABA shortened sleep latency by 5.3 min and AVLE increased non-rapid eye movement (REM) sleep time by 7.6%. Simultaneous intake of GABA and AVLE shortened sleep latency by 4.3 min and increased non-REM sleep time by 5.1%. The result of questionnaires showed that GABA and AVLE enabled subjects to realize the effects on sleep. These results mean that GABA can help people to fall asleep quickly, AVLE induces deep sleep, and they function complementarily with simultaneous intake. Since both GABA and AVLE are materials of foods and have been ingested for a long time, they can be regarded as safe and appropriate for daily intake in order to improve the quality of sleep.

  15. Changes in plasma GABA concentration during vigabatrin treatment of epilepsy: a prospective study.

    PubMed

    Erdal, J; Gram, L; Alving, J; Löscher, W

    1999-04-01

    The aim of the present prospective study was to evaluate changes in plasma GABA concentration in relation to clinical response during vigabatrin treatment of epilepsy. We studied 29 patients with uncontrolled partial-onset seizures during open add-on vigabatrin treatment and measured plasma GABA and vigabatrin concentrations by a sensitive HPLC method. Following short-term treatment 17 out of 28 patients had a seizure reduction of > 50% (responders). After long-term treatment 16 out of 22 patients were responders. There was no difference between responders and nonresponders regarding pretreatment seizure frequency, treatment duration, vigabatrin dose, or plasma vigabatrin concentration. Responders had a significant (p < 0.001) increase in mean plasma GABA both after short-term (from 0.380 to 0.530 nmol/ml; mean increase: 48%) and after long-term (from 0.392 to 0.618 nmol/ml; mean increase: 71%) vigabatrin treatment, whilst nonresponders had no significant changes in GABA levels. However, since plasma GABA increased in a subgroup of nonresponders, mean plasma GABA levels did not differ between responders and nonresponders. Although plasma GABA increased significantly in the responder but not in the nonresponder group during vigabatrin treatment of patients with epilepsy, it does not seem to be a reliable marker of individual clinical response to vigabatrin treatment.

  16. Differentiated human midbrain-derived neural progenitor cells express excitatory strychnine-sensitive glycine receptors containing α2β subunits.

    PubMed

    Wegner, Florian; Kraft, Robert; Busse, Kathy; Härtig, Wolfgang; Ahrens, Jörg; Leffler, Andreas; Dengler, Reinhard; Schwarz, Johannes

    2012-01-01

    Human fetal midbrain-derived neural progenitor cells (NPCs) may deliver a tissue source for drug screening and regenerative cell therapy to treat Parkinson's disease. While glutamate and GABA(A) receptors play an important role in neurogenesis, the involvement of glycine receptors during human neurogenesis and dopaminergic differentiation as well as their molecular and functional characteristics in NPCs are largely unknown. Here we investigated NPCs in respect to their glycine receptor function and subunit expression using electrophysiology, calcium imaging, immunocytochemistry, and quantitative real-time PCR. Whole-cell recordings demonstrate the ability of NPCs to express functional strychnine-sensitive glycine receptors after differentiation for 3 weeks in vitro. Pharmacological and molecular analyses indicate a predominance of glycine receptor heteromers containing α2β subunits. Intracellular calcium measurements of differentiated NPCs suggest that glycine evokes depolarisations mediated by strychnine-sensitive glycine receptors and not by D-serine-sensitive excitatory glycine receptors. Culturing NPCs with additional glycine, the glycine-receptor antagonist strychnine, or the Na(+)-K(+)-Cl(-) co-transporter 1 (NKCC1)-inhibitor bumetanide did not significantly influence cell proliferation and differentiation in vitro. These data indicate that NPCs derived from human fetal midbrain tissue acquire essential glycine receptor properties during neuronal maturation. However, glycine receptors seem to have a limited functional impact on neurogenesis and dopaminergic differentiation of NPCs in vitro.

  17. Regulation of metabolic products and gene expression in Fusarium asiaticum by agmatine addition.

    PubMed

    Suzuki, Tadahiro; Kim, Young-Kyung; Yoshioka, Hifumi; Iwahashi, Yumiko

    2013-05-01

    The metabolic products resulting from the cultivation of F. asiaticum in agmatine were identified using capillary electrophoresis-time of flight mass spectrometry. Glyoxylic acid was detected from fungal cultures grown in agmatine, while it was absent in control cells. The abundance of other metabolic products of the glycolytic pathway also increased because of agmatine; however, there was no increase in the amounts of pyruvic acid or metabolites from the tricarboxylic acid cycle. Moreover, gene expression levels within Fusarium asiaticum exposed to agmatine were analyzed by DNA microarray. Changes in gene expression levels directed the changes in metabolic products. Our results suggest that acetyl coenzyme A, which is a starting substrate for the biosynthesis of deoxynivalenol (DON), was simultaneously produced by activated β-oxidation. Furthermore, the content of 4-aminobutyrate (GABA) was increased in the agmatine addition culture medium. GABA can be synthesized from agmatine through putrescine and might influence the regulation of DON-related genes.

  18. Vigabatrin, a GABA Transaminase Inhibitor, Reversibly Eliminates Tinnitus in an Animal Model

    PubMed Central

    Spires, T. JosephD.; Bauer, Carol A.

    2007-01-01

    Animal models have facilitated basic neuroscience research investigating the pathophysiology of tinnitus. It has been hypothesized that partial deafferentation produces a loss of tonic inhibition in the auditory system that may lead to inappropriate neuroplastic changes eventually expressed as tinnitus. The pathological down-regulation of γ-amino butyric acid (GABA) provides a potential mechanism for this loss of inhibition. Using an animal model previously demonstrated to be sensitive to treatments that either induce or attenuate tinnitus, the present study examined the effect of the specific GABA agonist vigabatrin on chronic tinnitus. It was hypothesized that vigabatrin would decrease the evidence of tinnitus by restoring central inhibitory function through increased GABA availability. Vigabatrin has been demonstrated to elevate central GABA levels (Mattson et al. 1995). Tinnitus was induced in rats using a single 1-h unilateral exposure to band-limited noise, which preserved normal hearing in one ear. Psychophysical evidence of tinnitus was obtained using a free-operant conditioned-suppression method: Rats lever-pressed for food pellets and were trained to discriminate between the presence and absence of sound by punishing lever pressing with a mild foot shock (0.5 mA; 1 s) at the conclusion of randomly introduced silent periods (60 s) inserted into background low-level noise. Additional random insertion of pure tone and noise periods of variable intensity enabled the derivation of psychophysical functions that reflected the presence of tinnitus with features similar to 20-kHz tones. Vigabatrin was chronically administered via drinking water at 30 and 81 mg kg−1 day−1, with each dose level tested over 2 weeks, followed by a 0-mg washout test. Vigabatrin completely and reversibly eliminated the psychophysical evidence of tinnitus at both doses. Although vigabatrin has serious negative side effects that have prevented its clinical use in the USA, it is

  19. Rapid compensatory changes in GABA receptor efficacy in rat vestibular neurones after unilateral labyrinthectomy

    PubMed Central

    Yamanaka, Toshiaki; Him, Aydin; Cameron, Susan A; Dutia, Mayank B

    2000-01-01

    The inhibitory effects of the GABAA agonist muscimol and the GABAB agonist baclofen on tonically active medial vestibular nucleus (MVN) neurones were recorded in slices of the rat dorsal brainstem in vitro, to determine whether any changes occurred in the functional efficacy of GABAergic inhibition in these cells during the initial rapid stage of ‘vestibular compensation’, the behavioural recovery that takes place after unilateral labyrinthectomy (UL). These experiments were carried out in preparations where the midline was cut, severing all commissural connections between the two vestibular nuclei. Slices of the MVN were prepared from normal animals and animals that had been unilaterally labyrinthectomised 4 h earlier. The mean in vitro discharge rate of MVN neurones in the rostral region of the ipsi-lesional nucleus after UL was significantly higher than that in control slices, confirming our earlier reports of an increase in intrinsic excitability of these cells in the early stage of vestibular compensation. The in vitro discharge rates of caudal ipsi-lesional MVN cells, and rostral and caudal contra-lesional MVN cells, were not different from controls. Muscimol and baclofen caused reversible, dose-related inhibition of the tonic discharge rate of MVN cells in control slices. In slices prepared from UL animals, MVN cells in the rostral region of the ipsi-lesional nucleus showed a marked downregulation of their response to both muscimol and baclofen, seen as a rightward shift and a decrease in slope of the dose-response relationships for the two agonists. In the contra-lesional nucleus, there was a small but significant upregulation of the responsiveness of both rostral and caudal MVN cells to baclofen, and a marked upregulation of the responsiveness of caudal MVN cells to muscimol. In slices from animals that had undergone bilateral labyrinthectomy 4 h earlier, the downregulation of the functional efficacy of GABA receptors in the rostral MVN cells did not

  20. Action of tremorgenic mycotoxins on GABA/sub A/ receptor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gant, D.B.; Cole, R.J.; Valdes, J.J.

    1987-11-09

    The effects of four tremorgenic and one nontremorgenic mycotoxins were studied on ..gamma..-aminobutyric acid (GABA/sub A/) receptor binding and function in rat brain and on binding of a voltage-operated Cl/sup -/ channel in Torpedo electric organ. None of the mycotoxins had significant effect on (/sup 3/H)muscimol or (/sup 3/H)flunitrazepam binding to the GAMA/sup A/ receptor. However, only the four tremorgenic mycotoxins inhibited GABA-induced /sup 36/Cl/sup -/ influx and (/sup 35/S)t-butylbicyclophosphorothionate ((/sup 35/S)TBPS) binding in rate brain membranes, while the nontremorgenic verruculotoxin had no effect. Inhibition of (/sup 35/S)TBPS binding by paspalinine was non-competitive. This suggests that tremorgenic mycotoxins inhibit GABA/submore » A/ receptor function by binding close to the receptor's Cl/sup -/ channel. On the voltage-operated Cl/sup -/ channel, only high concentrations of verruculogen and verruculotoxin caused significant inhibition of the channel's binding of (/sup 35/S)TBPS. The data suggest that the tremorgenic action of these mycotoxins may be due in part to their inhibition of GABA/sub A/ receptor function. 21 references, 4 figures, 2 tables.« less

  1. GABA abnormalities in schizophrenia: a methodological review of in vivo studies.

    PubMed

    Taylor, Stephan F; Tso, Ivy F

    2015-09-01

    Abnormalities of GABAergic interneurons are some of the most consistent findings from post-mortem studies of schizophrenia. However, linking these molecular deficits with in vivo observations in patients - a critical goal in order to evaluate interventions that would target GABAergic deficits - presents a challenge. Explanatory models have been developed based on animal work and the emerging experimental literature in schizophrenia patients. This literature includes: neuroimaging ligands to GABA receptors, magnetic resonance spectroscopy (MRS) of GABA concentration, transcranial magnetic stimulation of cortical inhibitory circuits and pharmacologic probes of GABA receptors to dynamically challenge the GABA system, usually in combination with neuroimaging studies. Pharmacologic challenges have elicited behavioral changes, and preliminary studies of therapeutic GABAergic interventions have been conducted. This article critically reviews the evidence for GABAergic dysfunction from each of these areas. These methods remain indirect measures of GABAergic function, and a broad array of dysfunction is linked with the putative GABAergic measures, including positive symptoms, cognition, emotion, motor processing and sensory processing, covering diverse brain areas. Measures of receptor binding have not shown replicable group differences in binding, and MRS assays of GABA concentration have yielded equivocal evidence of large-scale alteration in GABA concentration. Overall, the experimental base remains sparse, and much remains to be learned about the role of GABAergic interneurons in healthy brains. Challenges with pharmacologic and functional probes show promise, and may yet enable a better characterization of GABAergic deficits in schizophrenia. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Honokiol promotes non-rapid eye movement sleep via the benzodiazepine site of the GABA(A) receptor in mice.

    PubMed

    Qu, Wei-Min; Yue, Xiao-Fang; Sun, Yu; Fan, Kun; Chen, Chang-Rui; Hou, Yi-Ping; Urade, Yoshihiro; Huang, Zhi-Li

    2012-10-01

    Decoctions of the Chinese herb houpu contain honokiol and are used to treat a variety of mental disorders, including depression. Depression commonly presents alongside sleep disorders and sleep disturbances, which appear to be a major risk factor for depression. Here, we have evaluated the somnogenic effect of honokiol and the mechanisms involved. Honokiol was administered i.p. at 20:00 h in mice. Flumazenil, an antagonist at the benzodiazepine site of the GABA(A) receptor, was administered i.p. 15 min before honokiol. The effects of honokiol were measured by EEG and electromyogram (EMG), c-Fos expression and in vitro electrophysiology. Honokiol (10 and 20 mg·kg⁻¹) significantly shortened the sleep latency to non-rapid eye movement (non-REM, NREM) sleep and increased the amount of NREM sleep. Honokiol increased the number of state transitions from wakefulness to NREM sleep and, subsequently, from NREM sleep to wakefulness. However, honokiol had no effect on either the amount of REM sleep or EEG power density of both NREM and REM sleep. Honokiol increased c-Fos expression in ventrolateral preoptic area (VLPO) neurons, as examined by immunostaining, and excited sleep-promoting neurons in the VLPO by whole-cell patch clamping in the brain slice. Pretreatment with flumazenil abolished the somnogenic effects and activation of the VLPO neurons by honokiol. Honokiol promoted NREM sleep by modulating the benzodiazepine site of the GABA(A) receptor, suggesting potential applications in the treatment of insomnia, especially for patients who experience difficulty in falling and staying asleep. © 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.

  3. Antagonism of GABA-B but not GABA-A receptors in the VTA prevents stress- and intra-VTA CRF-induced reinstatement of extinguished cocaine seeking in rats

    PubMed Central

    Blacktop, Jordan M.; Vranjkovic, Oliver; Mayer, Matthieu; Van Hoof, Matthew; Baker, David A.; Mantsch, John R.

    2015-01-01

    Stress-induced reinstatement of cocaine seeking requires corticotropin releasing factor (CRF) actions in the ventral tegmental area (VTA). However the mechanisms through which CRF regulates VTA function to promote cocaine use are not fully understood. Here we examined the role of GABAergic neurotransmission in the VTA mediated by GABA-A or GABA-B receptors in the reinstatement of extinguished cocaine seeking by a stressor, uncontrollable intermittent footshock, or bilateral intra-VTA administration of CRF. Rats underwent repeated daily cocaine self-administration (1.0 mg/kg/ing; 14 × 6 hrs/day) and extinction and were tested for reinstatement in response to footshock (0.5 mA, 0.5” duration, average every 40 sec; range 10–70 sec) or intra-VTA CRF delivery (500 ng/side) following intra-VTA pretreatment with the GABA-A antagonist, bicuculline, the GABA-B antagonist, 2-hydroxysaclofen or vehicle. Intra-VTA bicuculline (1, 10 or 20 ng/side) failed to block footshock- or CRF-induced cocaine seeking at either dose tested. By contrast, 2-hydroxysaclofen (0.2 or 2 µg/side) prevented reinstatement by both footshock and intra-VTA CRF at a concentration that failed to attenuate food-reinforced lever pressing (45 mg sucrose-sweetened pellets; FR4 schedule) in a separate group of rats. These data suggest that GABA-B receptor-dependent CRF actions in the VTA mediate stress-induced cocaine seeking and that GABA-B receptor antagonists may have utility for the management of stress-induced relapse in cocaine addicts. PMID:26596556

  4. Modulation of GABA-stimulated chloride influx into membrane vesicles from rat cerebral cortex by triazolobenzodiazepines

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Obata, T.; Yamamura, H.I.

    1988-01-01

    The effects of triazolobenzodiazepines of GABA-stimulated /sup 36/Cl/sup -/ uptake by membrane vesicles from rat cerebral cortex were examined. Triazolam and alprazolam showed a significant enhancement of GABA-stimulated /sup 36/Cl/sup -/ uptake at 0.01-10 uM. On the other hand, adinazolam showed a small enhancement at 0.1-1 uM followed by a significant inhibition of GABA-stimulated /sup 36/Cl/sup -/ uptake at 100 uM. The enhancement of GABA-stimulated /sup 36/Cl/sup -/ uptake by 1 uM alprazolam was antagonized by Ro15-1788, a benzodiazepine antagonist, but the inhibition of this response by 30 uM adinazolam was not antagonized by Ro15-1788. These results indicate that triazolobenzodiazepinesmore » enhanced GABA-stimulated /sup 36/Cl/sup -/ uptake through benzodiazepine receptors. High concentrations of adinazolam inhibit GABA-stimulated /sup 36/Cl/sup -/ uptake which may be due to the direct blockade of GABA-gated chloride channel. 23 references, 4 figures.« less

  5. GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters.

    PubMed

    Ramesh, Sunita A; Tyerman, Stephen D; Xu, Bo; Bose, Jayakumar; Kaur, Satwinder; Conn, Vanessa; Domingos, Patricia; Ullah, Sana; Wege, Stefanie; Shabala, Sergey; Feijó, José A; Ryan, Peter R; Gilliham, Matthew; Gillham, Matthew

    2015-07-29

    The non-protein amino acid, gamma-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to biotic and abiotic stress, and regulates plant growth. Until now it was not known whether GABA exerts its effects in plants through the regulation of carbon metabolism or via an unidentified signalling pathway. Here, we demonstrate that anion flux through plant aluminium-activated malate transporter (ALMT) proteins is activated by anions and negatively regulated by GABA. Site-directed mutagenesis of selected amino acids within ALMT proteins abolishes GABA efficacy but does not alter other transport properties. GABA modulation of ALMT activity results in altered root growth and altered root tolerance to alkaline pH, acid pH and aluminium ions. We propose that GABA exerts its multiple physiological effects in plants via ALMT, including the regulation of pollen tube and root growth, and that GABA can finally be considered a legitimate signalling molecule in both the plant and animal kingdoms.

  6. GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters

    PubMed Central

    Ramesh, Sunita A.; Tyerman, Stephen D.; Xu, Bo; Bose, Jayakumar; Kaur, Satwinder; Conn, Vanessa; Domingos, Patricia; Ullah, Sana; Wege, Stefanie; Shabala, Sergey; Feijó, José A.; Ryan, Peter R.; Gillham, Matthew

    2015-01-01

    The non-protein amino acid, gamma-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to biotic and abiotic stress, and regulates plant growth. Until now it was not known whether GABA exerts its effects in plants through the regulation of carbon metabolism or via an unidentified signalling pathway. Here, we demonstrate that anion flux through plant aluminium-activated malate transporter (ALMT) proteins is activated by anions and negatively regulated by GABA. Site-directed mutagenesis of selected amino acids within ALMT proteins abolishes GABA efficacy but does not alter other transport properties. GABA modulation of ALMT activity results in altered root growth and altered root tolerance to alkaline pH, acid pH and aluminium ions. We propose that GABA exerts its multiple physiological effects in plants via ALMT, including the regulation of pollen tube and root growth, and that GABA can finally be considered a legitimate signalling molecule in both the plant and animal kingdoms. PMID:26219411

  7. The effects of neuroleptics on the GABA-induced Cl- current in rat dorsal root ganglion neurons: differences between some neuroleptics.

    PubMed

    Yokota, Kenjiro; Tatebayashi, Hideharu; Matsuo, Tadashi; Shoge, Takashi; Motomura, Haruhiko; Matsuno, Toshiyuki; Fukuda, Akira; Tashiro, Nobutada

    2002-03-01

    1. Several neuroleptics inhibited the 3 microM gamma-aminobutyric acid induced-chloride current (GABA-current) on dissociated rat dorsal root ganglion neurons in whole-cell patch-clamp investigations. 2. The IC(50) for clozapine, zotepine, olanzapine, risperidone and chlorpromazine were 6.95, 18.26, 20.30, 106.01 and 114.56 microM, respectively. The values for the inhibitory effects of neuroleptics on the GABA (3 microM)-current, which were calculated by the fitting Hill's equations where the concentrations represent the mean therapeutic blood concentrations, were ranked clozapine>zotepine>chlorpromazine>olanzapine>risperidone. These inhibitory effects, weighted with the therapeutic concentrations of neuroleptics, were correlated with the clinical incidences of seizure during treatment with neuroleptics. 3. Clozapine reduced the picrotoxin-inhibiton, and may compete with a ligand of the t-butylbicyclophosphorothionate (TBPS) binding site. 4. Haloperidol and quetiapine did not affect the peak amplitude of the GABA (3 microM)-current. However, haloperidol reduced the clozapine-inhibition, and may antagonize ligand binding to TBPS binding site. 5. Neuroleptics including haloperidol and quetiapine enhanced the desensitization of the GABA (3 microM)-current. However, haloperidol and quetiapine at 100 microM inhibited the desensitization at the beginning of application. 6. Blonanserin (AD-5423) at 30 and 50 microM potentiated the GABA (3 microM)-current to 170.1+/-6.9 and 192.0+/-10.6% of the control current, respectively. Blonanserin shifted GABA concentration-response curve leftward. Blonanserin only partly negatively interacted with diazepam. The blonanserin-potentiation was not reversed by flumazenil. Blonanserin is not a benzodiazepine receptor agonist. 7. The various effects of neuroleptics on the GABA-current may be related to the clinical effects including modifying the seizure threshold.

  8. The effects of neuroleptics on the GABA-induced Cl− current in rat dorsal root ganglion neurons: differences between some neuroleptics

    PubMed Central

    Yokota, Kenjiro; Tatebayashi, Hideharu; Matsuo, Tadashi; Shoge, Takashi; Motomura, Haruhiko; Matsuno, Toshiyuki; Fukuda, Akira; Tashiro, Nobutada

    2002-01-01

    Several neuroleptics inhibited the 3 μM γ-aminobutyric acid induced-chloride current (GABA-current) on dissociated rat dorsal root ganglion neurons in whole-cell patch-clamp investigations. The IC50 for clozapine, zotepine, olanzapine, risperidone and chlorpromazine were 6.95, 18.26, 20.30, 106.01 and 114.56 μM, respectively. The values for the inhibitory effects of neuroleptics on the GABA (3 μM)-current, which were calculated by the fitting Hill's equations where the concentrations represent the mean therapeutic blood concentrations, were ranked clozapine>zotepine>chlorpromazine>olanzapine>risperidone. These inhibitory effects, weighted with the therapeutic concentrations of neuroleptics, were correlated with the clinical incidences of seizure during treatment with neuroleptics. Clozapine reduced the picrotoxin-inhibiton, and may compete with a ligand of the t-butylbicyclophosphorothionate (TBPS) binding site. Haloperidol and quetiapine did not affect the peak amplitude of the GABA (3 μM)-current. However, haloperidol reduced the clozapine-inhibition, and may antagonize ligand binding to TBPS binding site. Neuroleptics including haloperidol and quetiapine enhanced the desensitization of the GABA (3 μM)-current. However, haloperidol and quetiapine at 100 μM inhibited the desensitization at the beginning of application. Blonanserin (AD-5423) at 30 and 50 μM potentiated the GABA (3 μM)-current to 170.1±6.9 and 192.0±10.6% of the control current, respectively. Blonanserin shifted GABA concentration-response curve leftward. Blonanserin only partly negatively interacted with diazepam. The blonanserin-potentiation was not reversed by flumazenil. Blonanserin is not a benzodiazepine receptor agonist. The various effects of neuroleptics on the GABA-current may be related to the clinical effects including modifying the seizure threshold. PMID:11906969

  9. Developmental excitatory-to-inhibitory GABA polarity switch is delayed in Ts65Dn mice, a genetic model of Down syndrome.

    PubMed

    Lysenko, Larisa V; Kim, Jeesun; Madamba, Francisco; Tyrtyshnaia, Anna A; Ruparelia, Aarti; Kleschevnikov, Alexander M

    2018-07-01

    Down syndrome (DS) is the most frequent genetic cause of developmental abnormalities leading to intellectual disability. One notable phenomenon affecting the formation of nascent neural circuits during late developmental periods is developmental switch of GABA action from depolarizing to hyperpolarizing mode. We examined properties of this switch in DS using primary cultures and acute hippocampal slices from Ts65Dn mice, a genetic model of DS. Cultures of DIV3-DIV13 Ts65Dn and control normosomic (2 N) neurons were loaded with FURA-2 AM, and GABA action was assessed using local applications. In 2 N cultures, the number of GABA-activated cells dropped from ~100% to 20% between postnatal days 3-13 (P3-P13) reflecting the switch in GABA action polarity. In Ts65Dn cultures, the timing of this switch was delayed by 2-3 days. Next, microelectrode recordings of multi-unit activity (MUA) were performed in CA3 slices during bath application of the GABA A agonist isoguvacine. MUA frequency was increased in P8-P12 and reduced in P14-P22 slices reflecting the switch of GABA action from excitatory to inhibitory mode. The timing of this switch was delayed in Ts65Dn by approximately 2 days. Finally, frequency of giant depolarizing potentials (GDPs), a form of primordial neural activity, was significantly increased in slices from Ts65Dn pups at P12 and P14. These experimental evidences show that GABA action polarity switch is delayed in Ts65Dn model of DS, and that these changes lead to a delay in maturation of nascent neural circuits. These alterations may affect properties of neural circuits in adult animals and, therefore, represent a prospective target for pharmacotherapy of cognitive impairment in DS. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Effect of acute psychological stress on prefrontal GABA concentration determined by proton magnetic resonance spectroscopy.

    PubMed

    Hasler, Gregor; van der Veen, Jan Willem; Grillon, Christian; Drevets, Wayne C; Shen, Jun

    2010-10-01

    Impaired function of the central gamma-aminobutyric acid (GABA) system, which provides the brain's major inhibitory pathways, is thought to play an important role in the pathophysiology of anxiety disorders. The effect of acute psychological stress on the human GABA-ergic system is still unknown, however. The purpose of this study was to determine the effect of acute stress on prefrontal GABA levels. A recently developed noninvasive magnetic resonance spectroscopy method was used to measure changes in the GABA concentration of the prefrontal cortex in 10 healthy human subjects during a threat-of-shock condition and during a safe condition (two sessions on different days). The main outcome measure was the mean GABA concentration within a 3×3×2-cm(3) voxel selected from the medial prefrontal cortex. Prefrontal GABA decreased by approximately 18% in the threat-of-shock condition relative to the safe condition. This reduction was specific to GABA, since the concentrations of N-acetyl-aspartate, choline-containing compounds, and glutamate/glutamine levels obtained in the same spectra did not change significantly. This result appeared compatible with evidence from preclinical studies in rodents, which showed rapid presynaptic down-regulation of GABA-ergic neurotransmission in response to acute psychological stress. The molecular mechanism and functional significance of this reduced inhibitory effect of acute psychological stress in relation to impaired GABA-ergic function in anxiety disorders merit further investigation.

  11. Regulation of (/sup 3/H)GABA release from strips of guinea pig urinary bladder

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shirakawa, J.; Taniyama, K.; Iwai, S.

    1988-12-01

    The presence of receptors that regulate the release of gamma-aminobutyric acid (GABA) was studied in strips of the guinea pig urinary bladder. GABA (10(-8)-10(-5) M) and muscimol (10(-8)-10(-5) M), but not baclofen (10(-5) M), reduced the Ca2+-dependent, tetrodotoxin-resistant release of (/sup 3/H)GABA evoked by high K+ from the urinary bladder strips preloaded with (/sup 3/H)GABA. The inhibitory effect of muscimol was antagonized by bicuculline and potentiated by diazepam, clonazepam, and pentobarbital sodium. The potentiating effect of clonazepam was antagonized by Ro 15-1788. Acetylcholine (ACh) inhibited the high K+-evoked release of (/sup 3/H)GABA. The inhibitory effect of ACh was antagonized bymore » atropine sulfate and pirenzepine but not by hexamethonium. Norepinephrine (NE) inhibited the evoked release of (/sup 3/H)GABA. The inhibitory effect of NE was mimicked by clonidine, but not by phenylephrine, and was antagonized by yohimbine but not by prazosin. These results provide evidence that the release of GABA from strips of guinea pig urinary bladder is regulated via the bicuculline-sensitive GABAA receptor, M1-muscarinic, and alpha 2-adrenergic receptors.« less

  12. New Pharmacotherapy Targeting Cognitive Dysfunction of Schizophrenia via Modulation of GABA Neuronal Function

    PubMed Central

    Jeon, Won Je; Sumiyoshi, Tomiki; Kurachi, Masayoshi

    2015-01-01

    Schizophrenia is considered a neurodevelopmental and neurodegenerative disorder. Cognitive impairment is a core symptom in patients with the illness, and has been suggested a major predictor of functional outcomes. Reduction of parvalbumin (PV)-positive γ-aminobutyric acid (GABA) interneurons has been associated with the pathophysiology of schizophrenia, in view of the link between the abnormality of GABA neurons and cognitive impairments of the disease. It is assumed that an imbalance of excitatory and inhibitory (E-I) activity induced by low activity of glutamatergic projections and PV-positive GABA interneurons in the prefrontal cortex resulted in sustained neural firing and gamma oscillation, leading to impaired cognitive function. Therefore, it is important to develop novel pharmacotherapy targeting GABA neurons and their activities. Clinical evidence suggests serotonin (5-HT) 1A receptor agonist improves cognitive disturbances of schizophrenia, consistent with results from preclinical studies, through mechanism that corrects E-I imbalance via the suppression of GABA neural function. On the other hand, T-817MA, a novel neurotrophic agent, ameliorated loss of PV-positive GABA neurons in the medial prefrontal cortex and reduction of gamma-band activity, as well as cognitive dysfunction in animal model of schizophrenia. In conclusion, a pharmacotherapy to alleviate abnormalities in GABA neurons through 5-HT1A agonists and T-817MA is expected to prevent the onset and/or progression of schizophrenia. PMID:26630957

  13. New Pharmacotherapy Targeting Cognitive Dysfunction of Schizophrenia via Modulation of GABA Neuronal Function.

    PubMed

    Uehara, Takashi; Sumiyoshi, Tomiki; Kurachi, Masayoshi

    2015-01-01

    Schizophrenia is considered a neurodevelopmental and neurodegenerative disorder. Cognitive impairment is a core symptom in patients with the illness, and has been suggested a major predictor of functional outcomes. Reduction of parvalbumin (PV)-positive γ-aminobutyric acid (GABA) interneurons has been associated with the pathophysiology of schizophrenia, in view of the link between the abnormality of GABA neurons and cognitive impairments of the disease. It is assumed that an imbalance of excitatory and inhibitory (E-I) activity induced by low activity of glutamatergic projections and PV-positive GABA interneurons in the prefrontal cortex resulted in sustained neural firing and gamma oscillation, leading to impaired cognitive function. Therefore, it is important to develop novel pharmacotherapy targeting GABA neurons and their activities. Clinical evidence suggests serotonin (5-HT) 1A receptor agonist improves cognitive disturbances of schizophrenia, consistent with results from preclinical studies, through mechanism that corrects E-I imbalance via the suppression of GABA neural function. On the other hand, T-817MA, a novel neurotrophic agent, ameliorated loss of PV-positive GABA neurons in the medial prefrontal cortex and reduction of gamma-band activity, as well as cognitive dysfunction in animal model of schizophrenia. In conclusion, a pharmacotherapy to alleviate abnormalities in GABA neurons through 5-HT1A agonists and T-817MA is expected to prevent the onset and/or progression of schizophrenia.

  14. Dopamine/Tyrosine Hydroxylase Neurons of the Hypothalamic Arcuate Nucleus Release GABA, Communicate with Dopaminergic and Other Arcuate Neurons, and Respond to Dynorphin, Met-Enkephalin, and Oxytocin

    PubMed Central

    Zhang, Xiaobing

    2015-01-01

    We employ transgenic mice with selective expression of tdTomato or cre recombinase together with optogenetics to investigate whether hypothalamic arcuate (ARC) dopamine/tyrosine hydroxylase (TH) neurons interact with other ARC neurons, how they respond to hypothalamic neuropeptides, and to test whether these cells constitute a single homogeneous population. Immunostaining with dopamine and TH antisera was used to corroborate targeted transgene expression. Using whole-cell recording on a large number of neurons (n = 483), two types of neurons with different electrophysiological properties were identified in the dorsomedial ARC where 94% of TH neurons contained immunoreactive dopamine: bursting and nonbursting neurons. In contrast to rat, the regular oscillations of mouse bursting neurons depend on a mechanism involving both T-type calcium and A-type potassium channel activation, but are independent of gap junction coupling. Optogenetic stimulation using cre recombinase-dependent ChIEF-AAV-DJ expressed in ARC TH neurons evoked postsynaptic GABA currents in the majority of neighboring dopamine and nondopamine neurons, suggesting for the first time substantial synaptic projections from ARC TH cells to other ARC neurons. Numerous met-enkephalin (mENK) and dynorphin-immunoreactive boutons appeared to contact ARC TH neurons. mENK inhibited both types of TH neuron through G-protein coupled inwardly rectifying potassium currents mediated by δ and μ opioid receptors. Dynorphin-A inhibited both bursting and nonbursting TH neurons by activating κ receptors. Oxytocin excited both bursting and nonbursting neurons. These results reveal a complexity of TH neurons that communicate extensively with neurons within the ARC. SIGNIFICANCE STATEMENT Here, we show that the great majority of mouse hypothalamic arcuate nucleus (ARC) neurons that synthesize TH in the dorsomedial ARC also contain immunoreactive dopamine, and show either bursting or nonbursting electrical activity. Unlike

  15. Medial frontal GABA is lower in older schizophrenia: a MEGA-PRESS with macromolecule suppression study.

    PubMed

    Rowland, L M; Krause, B W; Wijtenburg, S A; McMahon, R P; Chiappelli, J; Nugent, K L; Nisonger, S J; Korenic, S A; Kochunov, P; Hong, L E

    2016-02-01

    Gamma-butyric acid (GABA) dysfunction has been implicated in the pathophysiology of schizophrenia and its cognitive deficits. Proton magnetic resonance spectroscopy (MRS) was used to test the hypothesis that older participants with schizophrenia have lower anterior cingulate GABA levels compared with older control participants. One-hundred forty-five participants completed this study. For detection of GABA, spectra were acquired from the medial frontal/anterior cingulate cortex using a macromolecule-suppressed MEGA-PRESS sequence. Patients were evaluated for psychopathology and all participants completed neuropsychological tests of working memory, processing speed and functional capacity. GABA levels were significantly lower in the older participants with schizophrenia (n=31) compared with the older control (n=37) group (P=0.003) but not between the younger control (n=40) and schizophrenia (n=29) groups (P=0.994). Age strongly predicted GABA levels in the schizophrenia group accounting for 42% of the variance, but the effect of age was less in the control group accounting for 5.7% of the variance. GABA levels were specifically related to working memory but not processing speed performance, functional capacity, or positive or negative symptom severity. This is the largest MRS study of GABA in schizophrenia and the first to examine GABA without macromolecule contamination, a potentially significant issue in previous studies. GABA levels more rapidly declined with advancing age in the schizophrenia compared with the control group. Interventions targeted at halting the decline or increasing GABA levels may improve functional outcomes and quality of life as patients with schizophrenia age.

  16. Medial Frontal GABA is Lower in Older Schizophrenia: A MEGA-PRESS with Macromolecule Suppression Study

    PubMed Central

    Rowland, Laura M; Krause, Benjamin W.; Wijtenburg, S. Andrea; McMahon, Robert P.; Chiappelli, Joshua; Nugent, Katie L.; Nisonger, Sarah J.; Korenic, Stephanie A.; Kochunov, Peter; Hong, L. Elliot

    2015-01-01

    Gamma-butyric acid (GABA) dysfunction has been implicated in the pathophysiology of schizophrenia and its cognitive deficits. Proton magnetic resonance spectroscopy (MRS) was used to test the hypothesis that older participants with schizophrenia have lower anterior cingulate GABA levels compared to older control participants. One-hundred and forty-five participants completed this study. For detection of GABA, spectra were acquired from the medial frontal/anterior cingulate cortex using a macromolecule-suppressed MEGA-PRESS sequence. Patients were evaluated for psychopathology and all participants completed neuropsychological tests of working memory, processing speed, and functional capacity. GABA levels were significantly lower in the older participants with schizophrenia(n=31) compared to the older control(n=37) group (p=0.003) but not between the younger control(n=40) and schizophrenia (n=29) groups (p=0.994). Age strongly predicted GABA levels in the schizophrenia group accounting for 42% of the variance, but the effect of age was less in the control group accounting for 5.7% of the variance. GABA levels were specifically related to working memory but not processing speed performance, functional capacity, or positive or negative symptom severity. This is the largest MRS study of GABA in schizophrenia and the first to examine GABA without macromolecule contamination, a potentially significant issue in previous studies. GABA levels more rapidly declined with advancing age in the schizophrenia compared to the control group. Interventions targeted at halting the decline or increasing GABA levels may improve functional outcomes and quality of life as patients with schizophrenia age. PMID:25824298

  17. Aldehyde dehydrogenase 1a1 mediates a GABA synthesis pathway in midbrain dopaminergic neurons.

    PubMed

    Kim, Jae-Ick; Ganesan, Subhashree; Luo, Sarah X; Wu, Yu-Wei; Park, Esther; Huang, Eric J; Chen, Lu; Ding, Jun B

    2015-10-02

    Midbrain dopamine neurons are an essential component of the basal ganglia circuitry, playing key roles in the control of fine movement and reward. Recently, it has been demonstrated that γ-aminobutyric acid (GABA), the chief inhibitory neurotransmitter, is co-released by dopamine neurons. Here, we show that GABA co-release in dopamine neurons does not use the conventional GABA-synthesizing enzymes, glutamate decarboxylases GAD65 and GAD67. Our experiments reveal an evolutionarily conserved GABA synthesis pathway mediated by aldehyde dehydrogenase 1a1 (ALDH1a1). Moreover, GABA co-release is modulated by ethanol (EtOH) at concentrations seen in blood alcohol after binge drinking, and diminished ALDH1a1 leads to enhanced alcohol consumption and preference. These findings provide insights into the functional role of GABA co-release in midbrain dopamine neurons, which may be essential for reward-based behavior and addiction. Copyright © 2015, American Association for the Advancement of Science.

  18. Utilization of barley or wheat bran to bioconvert glutamate to γ-aminobutyric acid (GABA).

    PubMed

    Jin, Wen-Jie; Kim, Min-Ju; Kim, Keun-Sung

    2013-09-01

    This study deals with the utilization of agro-industrial wastes created by barley and wheat bran in the production of a value-added product, γ-aminobutyric acid (GABA). The simple and eco-friendly reaction requires no pretreatment or microbial fermentation steps but uses barley or wheat bran as an enzyme source, glutamate as a substrate, and pyridoxal 5'-phosphate (PLP) as a cofactor. The optimal reaction conditions were determined on the basis of the temperatures and times used for the decarboxylation reactions and the initial concentrations of barley or wheat bran, glutamate, and PLP. The optimal reactions produced 9.2 mM of GABA from 10 mM glutamate, yielding a 92% GABA conversion rate, when barley bran was used and 6.0 mM of GABA from 10 mM glutamate, yielding a 60% GABA conversion rate, when wheat bran was used. The results imply that barley bran is more efficient than wheat bran in the production of GABA. © 2013 Institute of Food Technologists®

  19. The dynamics of GABA signaling: Revelations from the circadian pacemaker in the suprachiasmatic nucleus

    PubMed Central

    Albers, H. Elliott; Walton, James C.; Gamble, Karen L.; McNeill, John K.; Hummer, Daniel L.

    2016-01-01

    Virtually every neuron within the suprachiasmatic nucleus (SCN) communicates via GABAergic signaling. The extracellular levels of GABA within the SCN are determined by a complex interaction of synthesis and transport, as well as synaptic and non-synaptic release. The response to GABA is mediated by GABAA receptors that respond to both phasic and tonic GABA release and that can produce excitatory as well as inhibitory cellular responses. GABA also influences circadian control through the exclusively inhibitory effects of GABAB receptors. Both GABA and neuropeptide signaling occur within the SCN, although the functional consequences of the interactions of these signals are not well understood. This review considers the role of GABA in the circadian pacemaker, in the mechanisms responsible for the generation of circadian rhythms, in the ability of non-photic stimuli to reset the phase of the pacemaker, and in the ability of the day-night cycle to entrain the pacemaker. PMID:27894927

  20. Improving and accelerating the differentiation and functional maturation of human stem cell-derived neurons: role of extracellular calcium and GABA.

    PubMed

    Kemp, Paul J; Rushton, David J; Yarova, Polina L; Schnell, Christian; Geater, Charlene; Hancock, Jane M; Wieland, Annalena; Hughes, Alis; Badder, Luned; Cope, Emma; Riccardi, Daniela; Randall, Andrew D; Brown, Jonathan T; Allen, Nicholas D; Telezhkin, Vsevolod

    2016-11-15

    Neurons differentiated from pluripotent stem cells using established neural culture conditions often exhibit functional deficits. Recently, we have developed enhanced media which both synchronize the neurogenesis of pluripotent stem cell-derived neural progenitors and accelerate their functional maturation; together these media are termed SynaptoJuice. This pair of media are pro-synaptogenic and generate authentic, mature synaptic networks of connected forebrain neurons from a variety of induced pluripotent and embryonic stem cell lines. Such enhanced rate and extent of synchronized maturation of pluripotent stem cell-derived neural progenitor cells generates neurons which are characterized by a relatively hyperpolarized resting membrane potential, higher spontaneous and induced action potential activity, enhanced synaptic activity, more complete development of a mature inhibitory GABA A receptor phenotype and faster production of electrical network activity when compared to standard differentiation media. This entire process - from pre-patterned neural progenitor to active neuron - takes 3 weeks or less, making it an ideal platform for drug discovery and disease modelling in the fields of human neurodegenerative and neuropsychiatric disorders, such as Huntington's disease, Parkinson's disease, Alzheimer's disease and Schizophrenia. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

  1. The influences of metabotropic receptor activation on cellular signaling and synaptic function in amacrine cells.

    PubMed

    Gleason, Evanna

    2012-01-01

    Amacrine cells receive glutamatergic input from bipolar cells and GABAergic, glycinergic, cholinergic, and dopaminergic input from other amacrine cells. Glutamate, GABA, glycine, and acetylcholine (ACh) interact with ionotropic receptors and it is these interactions that form much of the functional circuitry in the inner retina. However, glutamate, GABA, ACh, and dopamine also activate metabotropic receptors linked to second messenger pathways that have the potential to modify the function of individual cells as well as retinal circuitry. Here, the physiological effects of activating dopamine receptors, metabotropic glutamate receptors, GABAB receptors, and muscarinic ACh receptors on amacrine cells will be discussed. The retina also expresses metabotropic receptors and the biochemical machinery associated with the synthesis and degradation of endocannabinoids and sphingosine-1-phosphate (S1P). The effects of activating cannabinoid receptors and S1P receptors on amacrine cell function will also be addressed. Copyright © Cambridge University Press, 2012

  2. Homocysteine alters cerebral microvascular integrity and causes remodeling by antagonizing GABA-A receptor*

    PubMed Central

    Lominadze, David; Tyagi, Neetu; Sen, Utpal; Ovechkin, Alexander; Tyagi, Suresh C.

    2012-01-01

    High levels of homocysteine (Hcy), known as hyperhomocysteinemia (HHcy), are associated with cerebrovascular diseases, such as vascualr dementia, stroke, and Alzheimer's disease. The -amino butyric acid (GABA) is a inhibitory neurotransmitter and a ligand of GABA-A receptor. By inhibiting excitatory response it may decrease complications associated with vascular dementia and stroke. Hcy specifically competes with the GABA-A receptors and acts as an excitotoxic neurotransmitter. Previously we have shown that Hcy increases levels of NADPH oxidase and reactive oxygen species (ROS), and decreases levels of thioredoxin and peroxiredoxin by antagonizing the GABA-A receptor. Hcy treatment leads to activation of matrix metalloproteinases (MMPs) in cerebral circualtion by inducing redox stress and ROS. The hypothesis is that Hcy induces MMPs and suppresses tissue inhibitors of metalloproteinase (TIMPs), in part, by inhibiting the GABA-A receptor. This leads to degradation of the matrix and disruption of the blood brain barrier. The brain cortex of transgenic mouse model of HHcy (cystathionine -synthase, CBS −/+) and GABA-A receptor null mice treated with and without muscimol (GABA-A receptor agonist) was analysed. The mRNA levels were measured by Q-RT-PCR. Levels of MMP-2, -9, -13, and TIMP-1, -2, -3, and -4 were evaluated by in situ labeling and PCR-gene arrays. Pial venular permeability to fluorescence-labeled albumin was assessed with intravital fluorescence microscopy. We found that Hcy increases metalloproteinase activity and decreases TIMP-4 by antagonizing the GABA-A receptor. The results demonstrate a novel mechanism in which brain microvascular permeability changes during HHcy and vascular dementias, and have therapeutic ramifications for microvascular disease in Alzheimer's patients. PMID:22886392

  3. Alcohol interactions with channel activation and desensitization at 5-HT[sub 3] and GABA[sub A] receptors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lovinger, D.M.; Zhou, O.

    1992-01-01

    Ethanol (EtOH) and trichloroethanol (TCEt) potentiate 5-HT[sub 3] receptor-mediated ion current in NCB-20 neuroblastoma cells and nodose ganglion neurons. TCEt potentiates GABA[sub A] receptor-mediated current in dorsal root ganglion neurons. Whole-cell patch-clamp recording was used to examine the interactions of alcohols with current activation and receptor desensitization. Alcohols increased the potency of 5-HT, consistent with an increase in channel activation rate. Current decay rate increased in the presence of alcohols such that potentiation decreased with time following in onset of agonist + alcohol treatment. Potentiation of 5-HT-activated current by EtOH was 61 [plus minus] 17% above control at the startmore » of application but was absent 10 sec after current onset. Agonist pretreatment decreased potentiation by subsequent agonist + alcohol application. Potentiation by TCEt of 5-HT-activated current decreased from 96% above control with simultaneous application of 5-HT + TCEt to 44% after a 30 sec 5-HT treatment. This agonist- and time-dependent loss of potentiation was observed prior to the onset of current decay when low agonist concentrations were used. Agonist pretreatment appears to drive the channel into an alcohol-insensitive. Current activated by GABA + TCEt recovers from desensitization produced by GABA alone more slowly than recovery tested in the absence of TCEt.« less

  4. GABA editing with macromolecule suppression using an improved MEGA-SPECIAL sequence.

    PubMed

    Gu, Meng; Hurd, Ralph; Noeske, Ralph; Baltusis, Laima; Hancock, Roeland; Sacchet, Matthew D; Gotlib, Ian H; Chin, Frederick T; Spielman, Daniel M

    2018-01-01

    The most common γ-aminobutyric-acid (GABA) editing approach, MEGA-PRESS, uses J-editing to measure GABA distinct from larger overlapping metabolites, but suffers contamination from coedited macromolecules (MMs) comprising 40 to 60% of the observed signal. MEGA-SPECIAL is an alternative method with better MM suppression, but is not widely used primarily because of its relatively poor spatial localization. Our goal was to develop an improved MM-suppressed GABA editing sequence at 3 Tesla. We modified a single-voxel MEGA-SPECIAL sequence with an oscillating readout gradient for improved spatial localization, and used very selective 30-ms editing pulses for improved suppression of coedited MMs. Simulation and in vivo experiments confirmed excellent MM suppression, insensitive to the range of B 0 frequency drifts typically encountered in vivo. Both intersubject and intrasubject studies showed that MMs, when suppressed by the improved MEGA-SPECIAL method, contributed approximately 40% to the corresponding MEGA-PRESS measurements. From the intersubject study, the coefficient of variation for GABA+/Cre (MEGA-PRESS) was 11.2% versus 7% for GABA/Cre (improved MEGA-SPECIAL), demonstrating significantly reduced variance (P = 0.005), likely coming from coedited MMs. This improved MEGA-SPECIAL sequence provides unbiased GABA measurements with reduced variance as compared with conventional MEGA-PRESS. This approach is also relatively insensitive to the range of B 0 drifts typically observed in in vivo human studies. Magn Reson Med 79:41-47, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  5. Ventral tegmental area GABA neurons and opiate motivation

    PubMed Central

    Vargas-Perez, Hector; Mabey, Jennifer K.; Shin, Samuel I.; Steffensen, Scott C.; van der Kooy, Derek

    2013-01-01

    Rational Past research has demonstrated that when an animal changes from a previously drug-naive to an opiate-dependent and withdrawn state, morphine’s motivational effects are switched from a tegmental pedunculopontine nucleus (TPP)-dependent to a dopamine-dependent pathway. Interestingly, a corresponding change is observed in ventral tegmental area (VTA) GABAA receptors, which change from mediating hyperpolarization of VTA GABA neurons to mediating depolarization. Objectives The present study investigated whether pharmacological manipulation of VTA GABAA receptor activity could directly influence the mechanisms underlying opiate motivation. Results Using an unbiased place conditioning procedure, we demonstrated that in Wistar rats, intra-VTA administration of furosemide, a Cl− cotransporter inhibitor, was able to promote a switch in the mechanisms underlying morphine’s motivational properties, one which is normally observed only after chronic opiate exposure. This behavioral switch was prevented by intra-VTA administration of acetazolamide, an inhibitor of the bicarbonate ion-producing carbonic anhydrase enzyme. Electrophysiological recordings of mouse VTA showed that furosemide reduced the sensitivity of VTA GABA neurons to inhibition by the GABAA receptor agonist muscimol, instead increasing the firing rate of a significant subset of these GABA neurons. Conclusion Our results suggest that the carbonic anhydrase enzyme may constitute part of a common VTA GABA neuron-based biological pathway responsible for controlling the mechanisms underlying opiate motivation, supporting the hypothesis that VTA GABAA receptor hyperpolarization or depolarization is responsible for selecting TPP- or dopamine-dependent motivational outputs, respectively. PMID:23392354

  6. Brain GABA Detection in vivo with the J-editing 1H MRS Technique: A Comprehensive Methodological Evaluation of Sensitivity Enhancement, Macromolecule Contamination and Test-Retest Reliability

    PubMed Central

    Shungu, Dikoma C.; Mao, Xiangling; Gonzales, Robyn; Soones, Tacara N.; Dyke, Jonathan P.; van der Veen, Jan Willem; Kegeles, Lawrence S.

    2016-01-01

    Abnormalities in brain γ-aminobutyric acid (GABA) have been implicated in various neuropsychiatric and neurological disorders. However, in vivo GABA detection by proton magnetic resonance spectroscopy (1H MRS) presents significant challenges arising from low brain concentration, overlap by much stronger resonances, and contamination by mobile macromolecule (MM) signals. This study addresses these impediments to reliable brain GABA detection with the J-editing difference technique on a 3T MR system in healthy human subjects by (a) assessing the sensitivity gains attainable with an 8-channel phased-array head coil, (b) determining the magnitude and anatomic variation of the contamination of GABA by MM, and (c) estimating the test-retest reliability of measuring GABA with this method. Sensitivity gains and test-retest reliability were examined in the dorsolateral prefrontal cortex (DLPFC), while MM levels were compared across three cortical regions: the DLPFC, the medial prefrontal cortex (MPFC) and the occipital cortex (OCC). A 3-fold higher GABA detection sensitivity was attained with the 8-channel head coil compared to the standard single-channel head coil in DLPFC. Despite significant anatomic variation in GABA+MM and MM across the three brain regions (p < 0.05), the contribution of MM to GABA+MM was relatively stable across the three voxels, ranging from 41% to 49%, a non-significant regional variation (p = 0.58). The test-retest reliability of GABA measurement, expressed either as ratios to voxel tissue water (W) or total creatine, was found to be very high for both the single-channel coil and the 8-channel phased-array coil. For the 8-channel coil, for example, Pearson’s correlation coefficient of test vs. retest for GABA/W was 0.98 (R2 = 0.96, p = 0.0007), the percent coefficient of variation (CV) was 1.25%, and the intraclass correlation coefficient (ICC) was 0.98. Similar reliability was also found for the co-edited resonance of combined glutamate and

  7. Antagonism of GABA-B but not GABA-A receptors in the VTA prevents stress- and intra-VTA CRF-induced reinstatement of extinguished cocaine seeking in rats.

    PubMed

    Blacktop, Jordan M; Vranjkovic, Oliver; Mayer, Matthieu; Van Hoof, Matthew; Baker, David A; Mantsch, John R

    2016-03-01

    Stress-induced reinstatement of cocaine seeking requires corticotropin releasing factor (CRF) actions in the ventral tegmental area (VTA). However the mechanisms through which CRF regulates VTA function to promote cocaine use are not fully understood. Here we examined the role of GABAergic neurotransmission in the VTA mediated by GABA-A or GABA-B receptors in the reinstatement of extinguished cocaine seeking by a stressor, uncontrollable intermittent footshock, or bilateral intra-VTA administration of CRF. Rats underwent repeated daily cocaine self-administration (1.0 mg/kg/ing; 14 × 6 h/day) and extinction and were tested for reinstatement in response to footshock (0.5 mA, 0.5" duration, average every 40 s; range 10-70 s) or intra-VTA CRF delivery (500 ng/side) following intra-VTA pretreatment with the GABA-A antagonist, bicuculline, the GABA-B antagonist, 2-hydroxysaclofen or vehicle. Intra-VTA bicuculline (1, 10 or 20 ng/side) failed to block footshock- or CRF-induced cocaine seeking at either dose tested. By contrast, 2-hydroxysaclofen (0.2 or 2 μg/side) prevented reinstatement by both footshock and intra-VTA CRF at a concentration that failed to attenuate food-reinforced lever pressing (45 mg sucrose-sweetened pellets; FR4 schedule) in a separate group of rats. These data suggest that GABA-B receptor-dependent CRF actions in the VTA mediate stress-induced cocaine seeking and that GABA-B receptor antagonists may have utility for the management of stress-induced relapse in cocaine addicts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. In vivo measurement of GABA transmission in healthy subjects and schizophrenia patients.

    PubMed

    Frankle, W Gordon; Cho, Raymond Y; Prasad, Konasale M; Mason, N Scott; Paris, Jennifer; Himes, Michael L; Walker, Christopher; Lewis, David A; Narendran, Rajesh

    2015-11-01

    Postmortem studies in schizophrenia reveal alterations in gene products that regulate the release and extracellular persistence of GABA. However, results of in vivo studies of schizophrenia measuring total tissue GABA with magnetic resonance spectroscopy (MRS) have been inconsistent. Neither the postmortem nor the MRS studies directly address the physiological properties of GABA neurotransmission. The present study addresses this question through an innovative positron emission tomography (PET) paradigm. The binding of [(11)C]flumazenil, a benzodiazepine-specific PET radiotracer, was measured before and after administration of tiagabine (0.2 mg/kg of body weight), a GABA membrane transporter (GAT1) blocker, in 17 off-medication patients with schizophrenia and 22 healthy comparison subjects. Increased extracellular GABA, through GAT1 blockade, enhances the affinity of GABAA receptors for benzodiazepine ligands, detected as an increase in [(11)C]flumazenil tissue distribution volume (VT). [(11)C]Flumazenil VT was significantly increased across all cortical brain regions in the healthy comparison group but not in the schizophrenia group. This lack of effect was most prominent in the antipsychotic-naive schizophrenia group. In this subgroup, [(11)C]flumazenil ΔVT in the medial temporal lobe was correlated with positive symptoms, and baseline [(11)C]flumazenil VT in the medial temporal lobe was negatively correlated with visual learning. In the healthy comparison group but not the schizophrenia group, [(11)C]flumazenil ΔVT was positively associated with gamma-band oscillation power. This study demonstrates, for the first time, an in vivo impairment in GABA transmission in schizophrenia, most prominent in antipsychotic-naive individuals. The impairment in GABA transmission appears to be linked to clinical symptoms, disturbances in cortical oscillations, and cognition.

  9. Effect of Acute Psychological Stress on Prefrontal GABA Concentration Determined by Proton Magnetic Resonance Spectroscopy

    PubMed Central

    Hasler, Gregor; van der Veen, Jan Willem; Grillon, Christian; Drevets, Wayne C.; Shen, Jun

    2011-01-01

    Objective Impaired function of the central gamma-aminobutyric acid (GABA) system, which provides the brain’s major inhibitory pathways, is thought to play an important role in the pathophysiology of anxiety disorders. The effect of acute psychological stress on the human GABA-ergic system is still unknown, however. The purpose of this study was to determine the effect of acute stress on prefrontal GABA levels. Method A recently developed noninvasive magnetic resonance spectroscopy method was used to measure changes in the GABA concentration of the prefrontal cortex in 10 healthy human subjects during a threat-of-shock condition and during a safe condition (two sessions on different days). The main outcome measure was the mean GABA concentration within a 3×3×2-cm3 voxel selected from the medial prefrontal cortex. Results Prefrontal GABA decreased by approximately 18% in the threat-of-shock condition relative to the safe condition. This reduction was specific to GABA, since the concentrations of N-acetyl-aspartate, choline-containing compounds, and glutamate/glutamine levels obtained in the same spectra did not change significantly. Conclusions This result appeared compatible with evidence from preclinical studies in rodents, which showed rapid presynaptic down-regulation of GABA-ergic neurotransmission in response to acute psychological stress. The molecular mechanism and functional significance of this reduced inhibitory effect of acute psychological stress in relation to impaired GABA-ergic function in anxiety disorders merit further investigation. PMID:20634372

  10. Hypoxia and GABA shunt activation in the pathogenesis of Alzheimer's disease.

    PubMed

    Salminen, Antero; Jouhten, Paula; Sarajärvi, Timo; Haapasalo, Annakaisa; Hiltunen, Mikko

    2016-01-01

    We have previously observed that the conversion of mild cognitive impairment to definitive Alzheimer's disease (AD) is associated with a significant increase in the serum level of 2,4-dihydroxybutyrate (2,4-DHBA). The metabolic generation of 2,4-DHBA is linked to the activation of the γ-aminobutyric acid (GABA) shunt, an alternative energy production pathway activated during cellular stress, when the function of Krebs cycle is compromised. The GABA shunt can be triggered by local hypoperfusion and subsequent hypoxia in AD brains caused by cerebral amyloid angiopathy. Succinic semialdehyde dehydrogenase (SSADH) is a key enzyme in the GABA shunt, converting succinic semialdehyde (SSA) into succinate, a Krebs cycle intermediate. A deficiency of SSADH activity stimulates the conversion of SSA into γ-hydroxybutyrate (GHB), an alternative route from the GABA shunt. GHB can exert not only acute neuroprotective activities but unfortunately also chronic detrimental effects which may lead to cognitive impairment. Subsequently, GHB can be metabolized to 2,4-DHBA and secreted from the brain. Thus, the activation of the GABA shunt and the generation of GHB and 2,4-DHBA can have an important role in the early phase of AD pathogenesis. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Allosteric modulation by benzodiazepines of GABA-gated chloride channels of an identified insect motor neurone.

    PubMed

    Buckingham, Steven D; Higashino, Yoshiaki; Sattelle, David B

    2009-11-01

    The actions of benzodiazepines were studied on the responses to GABA of the fast coxal depressor (D(f)) motor neurone of the cockroach, Periplaneta americana. Ro5-4864, diazepam and clonazepam were investigated. Responses to GABA receptors were enhanced by both Ro5-4864 and diazepam, whereas clonazepam, a potent-positive allosteric modulator of human GABA(A) receptors, was ineffective on the native insect GABA receptors of the D(f) motor neurone. Thus, clear pharmacological differences exist between insect and mammalian native GABA-gated chloride channels with respect to the actions of benzodiazepines. The results enhance our understanding of invertebrate GABA-gated chloride channels which have recently proved important in (a) comparative studies aimed at identifying human allosteric drug-binding sites and (b) understanding the actions of compounds used to control ectoparasites and insect crop pests.

  12. GABA transporter currents activated by protein kinase A excite midbrain neurons during opioid withdrawal.

    PubMed

    Bagley, Elena E; Gerke, Michelle B; Vaughan, Christopher W; Hack, Stephen P; Christie, MacDonald J

    2005-02-03

    Adaptations in neurons of the midbrain periaqueductal gray (PAG) induced by chronic morphine treatment mediate expression of many signs of opioid withdrawal. The abnormally elevated action potential rate of opioid-sensitive PAG neurons is a likely cellular mechanism for withdrawal expression. We report here that opioid withdrawal in vitro induced an opioid-sensitive cation current that was mediated by the GABA transporter-1 (GAT-1) and required activation of protein kinase A (PKA) for its expression. Inhibition of GAT-1 or PKA also prevented withdrawal-induced hyperexcitation of PAG neurons. Our findings indicate that GAT-1 currents can directly increase the action potential rates of neurons and that GAT-1 may be a target for therapy to alleviate opioid-withdrawal symptoms.

  13. Cortical Deficits of Glutamic Acid Decarboxylase 67 Expression in Schizophrenia: Clinical, Protein, and Cell Type-Specific Features

    PubMed Central

    Curley, Allison A.; Arion, Dominique; Volk, David W.; Asafu-Adjei, Josephine K.; Sampson, Allan R.; Fish, Kenneth N.; Lewis, David A.

    2012-01-01

    Objective Cognitive deficits in schizophrenia are associated with altered activity of the dorsolateral prefrontal cortex, which has been attributed to lower expression of the 67 kDa isoform of glutamic acid decarboxylase (GAD67), the major γ-aminobutyric acid (GABA)-synthesizing enzyme. However, little is know n about the relationship of prefrontal GAD67 m RNA levels and illness severity, translation of the transcript into protein, and protein levels in axon terminals, the key site of GABA production and function. Method Quantitative polymerase chain reaction was used to measure GAD67 m RNA levels in postmortem specimens of dorsolateral prefrontal cortex from subjects with schizophrenia and matched comparison subjects with no know n history of psychiatric or neurological disorders (N=42 pairs). In a subset of this cohort in which potential confounds of protein measures were controlled (N=19 pairs), Western blotting was used to quantify tissue levels of GAD67 protein in tissue. In five of these pairs, multilabel confocalimm unofluorescence was used to quantify GAD67 protein levels in the axon terminals of parvalbumin-containing GABA neurons, which are know n to have low levels of GAD67 m RNA in schizophrenia. Results GAD67 m RNA levels were significantly lower in schizophrenia subjects (by 15%), but transcript levels were not associated with predictors or measures of illness severity or chronicity. In schizophrenia subjects, GAD67 protein levels were significantly lower in total gray matter (by 10%) and in parvalbumin axon terminals (by 49%). Conclusions The findings that lower GAD67 m RNA expression is com m on in schizophrenia, that it is not a consequence of having the illness, and that it leads to less translation of the protein, especially in the axon terminals of parvalbumin-containing neurons, support the hypothesis that lower GABA synthesis in parvalbumin neurons contributes to dorsolateral prefrontal cortex dysfunction and impaired cognition in

  14. GABA release in the zona incerta of the sheep in response to the sight and ingestion of food and salt.

    PubMed

    Kendrick, K M; Hinton, M R; Baldwin, B A

    1991-05-31

    In order to establish which neurotransmitters may influence the activity of zona incerta neurones in the sheep which respond selectively to the sight or ingestion of food, we have measured the release of amino acid and monoamine neurotransmitters from this region using microdialysis sampling. Co-ordinates for the placement of microdialysis probes in regions of the zona incerta where cells respond to the sight or ingestion of food were first established by making single-unit extracellular recordings. When animals were food-deprived results showed that release of gamma-aminobutyric acid (GABA) was increased in response to the sight and ingestion of food but not of aspartate, glutamate, taurine, noradrenaline, dopamine or serotonin. This release of GABA was absent when the animals were shown non-food objects or saw or ingested salt solutions. When the same animals were physiologically sodium-depleted GABA release was evoked by the sight and ingestion of salt solutions and release following the sight and ingestion of food was significantly reduced. These results provide further evidence that GABA is an important neurotransmitter in neural circuits controlling the regulation of food intake.

  15. In vivo evaluation of the hippocampal glutamate, GABA and the BDNF levels associated with spatial memory performance in a rodent model of neuropathic pain.

    PubMed

    Saffarpour, S; Shaabani, M; Naghdi, N; Farahmandfar, M; Janzadeh, A; Nasirinezhad, F

    2017-06-01

    Patients with chronic pain usually suffer from learning and memory impairment which may significantly decrease their quality of life. Despite laboratory and clinical studies, the mechanism underlying this memory impairment remains elusive. We evaluated the effect of chronic pain on the glutamate and GABA levels and BDNF expression in the CA1 region of hippocampus as a possible explanation for memory impairment related to neuropathic pain. In this respect, 30 male rats were randomly allocated to 3 groups as control, sham and neuropathic. Neuropathic pain was induced by a chronic constriction injury of the sciatic nerve (CCI) and mechanical allodynia and the spatial memory was assessed using the Von Frey filaments and Morris water maze respectively. To determine the potential mechanisms, the in vivo extracellular levels of glutamate and γ-aminobutyric acid (GABA) were measured by microdialysis and the brain-derived neurotrophic factor (BDNF) expression was determined by using western blots technique in the hippocampus on days 14 and 21 post-CCI. We showed that CCI impaired spatial learning and memory in Morris water maze (MWM) task. BDNF expression level and glutamate concentration significantly decreased in rats with chronic constriction injury of the sciatic nerve (P<0.001, F=7.3, F=23.23). In addition, GABA increased in hippocampal CA1 region (P<0.001, F=39.2) when the pain threshold was minimum. Nevertheless, these changes reversed while pain was relieved spontaneously. Chronic pain induced by constriction of the sciatic nerve impairs the spatial learning and memory function in rats. This effect exerts through the increase in GABA concentration and decrease in the glutamate and BDNF levels in the CA1 region of the hippocampus. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. CSF GABA is reduced in first-episode psychosis and associates to symptom severity

    PubMed Central

    Orhan, F; Fatouros-Bergman, H; Goiny, M; Malmqvist, A; Piehl, F; Engberg, Göran; Erhardt, Sophie; Schwieler, Lilly; Orhan, Funda; Malmqvist, Anna; Hedberg, Mikael; Farde, Lars; Cervenka, Simon; Flyckt, Lena; Collste, Karin; Ikonen, Pauliina; Piehl, Fredrik; Agartz, Ingrid; Cervenka, S; Collste, K; Victorsson, P; Sellgren, C M; Flyckt, L; Erhardt, S; Engberg, G

    2018-01-01

    Schizophrenia is characterized by a multiplicity of symptoms arising from almost all domains of mental function. γ-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the brain and is increasingly recognized to have a significant role in the pathophysiology of the disorder. In the present study, cerebrospinal fluid (CSF) concentrations of GABA were analyzed in 41 first-episode psychosis (FEP) patients and 21 age- and sex-matched healthy volunteers by high-performance liquid chromatography. We found lower CSF GABA concentration in FEP patients compared with that in the healthy volunteers, a condition that was unrelated to antipsychotic and/or anxiolytic medication. Moreover, lower CSF GABA levels were associated with total and general score of Positive and Negative Syndrome Scale, illness severity and probably with a poor performance in a test of attention. This study offers clinical in vivo evidence for a potential role of GABA in early-stage schizophrenia. PMID:28289277

  17. Treatment of GABA from Fermented Rice Germ Ameliorates Caffeine-Induced Sleep Disturbance in Mice

    PubMed Central

    Mabunga, Darine Froy N.; Gonzales, Edson Luck T.; Kim, Hee Jin; Choung, Se Young

    2015-01-01

    γ-Aminobutyric acid (GABA), a major inhibitory neurotransmitter in the mammalian central nervous system, is involved in sleep physiology. Caffeine is widely used psychoactive substance known to induce wakefulness and insomnia to its consumers. This study was performed to examine whether GABA extracts from fermented rice germ ameliorates caffeine-induced sleep disturbance in mice, without affecting spontaneous locomotor activity and motor coordination. Indeed, caffeine (10 mg/kg, i.p.) delayed sleep onset and reduced sleep duration of mice. Conversely, rice germ ferment extracts-GABA treatment (10, 30, or 100 mg/kg, p.o.), especially at 100 mg/kg, normalized the sleep disturbance induced by caffeine. In locomotor tests, rice germ ferment extracts-GABA slightly but not significantly reduced the caffeine-induced increase in locomotor activity without affecting motor coordination. Additionally, rice germ ferment extracts-GABA per se did not affect the spontaneous locomotor activity and motor coordination of mice. In conclusion, rice germ ferment extracts-GABA supplementation can counter the sleep disturbance induced by caffeine, without affecting the general locomotor activities of mice. PMID:25995826

  18. Dynorphin is expressed primarily by GABAergic neurons that contain galanin in the rat dorsal horn

    PubMed Central

    2011-01-01

    Background The opioid peptide dynorphin is expressed by certain neurons in the superficial dorsal horn of the spinal cord, but little is known about the types of cell that contain dynorphin. In this study, we have used an antibody against the dynorphin precursor preprodynorphin (PPD), to reveal the cell bodies and axons of dynorphin-expressing neurons in the rat spinal cord. The main aims were to estimate the proportion of neurons in each of laminae I-III that express dynorphin and to determine whether they are excitatory or inhibitory neurons. Results PPD-immunoreactive cells were concentrated in lamina I and the outer part of lamina II (IIo), where they constituted 17% and 8%, respectively, of all neurons. Around half of those in lamina I and 80% of those in lamina II were GABA-immunoreactive. We have previously identified four non-overlapping neurochemical populations of inhibitory interneurons in this region, defined by the presence of neuropeptide Y, galanin, parvalbumin and neuronal nitric oxide synthase. PPD co-localised extensively with galanin in both cell bodies and axons, but rarely or not at all with the other three markers. PPD was present in around 4% of GABAergic boutons (identified by the presence of the vesicular GABA transporter) in laminae I-II. Conclusions These results show that most dynorphin-expressing cells in the superficial dorsal horn are inhibitory interneurons, and that they largely correspond to the population that is defined by the presence of galanin. We estimate that dynorphin is present in ~32% of inhibitory interneurons in lamina I and 11% of those in lamina II. Since the proportion of GABAergic boutons that contain PPD in these laminae was considerably lower than this, our findings suggest that these neurons may generate relatively small axonal arborisations. PMID:21958458

  19. Astrocyte deletion of Bmal1 alters daily locomotor activity and cognitive functions via GABA signalling

    PubMed Central

    Barca-Mayo, Olga; Pons-Espinal, Meritxell; Follert, Philipp; Armirotti, Andrea; Berdondini, Luca; De Pietri Tonelli, Davide

    2017-01-01

    Circadian rhythms are controlled by a network of clock neurons in the central pacemaker, the suprachiasmatic nucleus (SCN). Core clock genes, such as Bmal1, are expressed in SCN neurons and in other brain cells, such as astrocytes. However, the role of astrocytic clock genes in controlling rhythmic behaviour is unknown. Here we show that ablation of Bmal1 in GLAST-positive astrocytes alters circadian locomotor behaviour and cognition in mice. Specifically, deletion of astrocytic Bmal1 has an impact on the neuronal clock through GABA signalling. Importantly, pharmacological modulation of GABAA-receptor signalling completely rescues the behavioural phenotypes. Our results reveal a crucial role of astrocytic Bmal1 for the coordination of neuronal clocks and propose a new cellular target, astrocytes, for neuropharmacology of transient or chronic perturbation of circadian rhythms, where alteration of astrocytic clock genes might contribute to the impairment of the neurobehavioural outputs such as cognition. PMID:28186121

  20. d Subunit-Containing GABA[subscript A] Receptor Prevents Overgeneralization of Fear in Adult Mice

    ERIC Educational Resources Information Center

    Zhang, Wen-Hua; Zhou, Jin; Pan, Han-Qing; Wang, Xiao-Yang; Liu, Wei-Zhu; Zhang, Jun-Yu; Yin, Xiao-Ping; Pan, Bing-Xing

    2017-01-01

    The role of d subunit-containing GABA[subscript A] receptor (GABA[subscript A](d)R) in fear generalization is uncertain. Here, by using mice with or without genetic deletion of GABA[subscript A](d)R and using protocols in which the conditioned tone stimuli were cross presented with different nonconditioned stimuli, we observed that when the two…

  1. Localization and function of GABA transporters in the globus pallidus of parkinsonian monkeys

    PubMed Central

    Galvan, Adriana; Hu, Xing; Smith, Yoland; Wichmann, Thomas

    2010-01-01

    The GABA transporters GAT-1 and GAT-3 are abundant in the external and internal segments of the globus pallidus (GPe and GPi, respectively). We have shown that pharmacological blockade of either of these transporters results in decreased neuronal firing, and in elevated levels of extracellular GABA in normal monkeys. We now studied whether the electrophysiologic and biochemical effects of local intra-pallidal injections of GAT-1 and GAT-3 blockers, or the subcellular localization of these transporters, are altered in monkeys rendered parkinsonian by the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The subcellular localization of the transporters in GPe and GPi, studied with electron microscopy immunoperoxidase, was similar to that found in normal animals: i.e., GAT-3 immunoreactivity was mostly confined to glial processes, while GAT-1 labeling was expressed in unmyelinated axons and glial processes. A combined injection/recording device was used to record extracellular activity of single neurons in GPe and GPi, before, during and after administration of small volumes (1 μl) of either the GAT-1 inhibitor, SKF-89976A hydrochloride (720 ng), or the GAT-3 inhibitor, (S)-SNAP-5114 (500 ng). In GPe, the effects of GAT-1 or GAT-3 blockade were similar to those seen in normal monkeys. However, unlike the findings in the normal state, the firing of most neurons was not affected by blockade of either transporter in GPi. These results suggest that, after dopaminergic depletion, the functions of GABA transporters are altered in GPi; without major changes in their subcellular localization. PMID:20138865

  2. Glutamate and GABA contributions to medial prefrontal cortical activity to emotion: implications for mood disorders.

    PubMed

    Stan, Ana D; Schirda, Claudiu V; Bertocci, Michele A; Bebko, Genna M; Kronhaus, Dina M; Aslam, Haris A; LaBarbara, Eduard J; Tanase, Costin; Lockovich, Jeanette C; Pollock, Myrna H; Stiffler, Richelle S; Phillips, Mary L

    2014-09-30

    The dorsomedial prefrontal cortex (MdPFC) and anterior cingulate cortices (ACC) play a critical role in implicit emotion regulation; however the understanding of the specific neurotransmitters that mediate such role is lacking. In this study, we examined relationships between MdPFC concentrations of two neurotransmitters, glutamate and γ-amino butyric acid (GABA), and BOLD activity in ACC during performance of an implicit facial emotion-processing task. Twenty healthy volunteers, aged 20-35 years, were scanned while performing an implicit facial emotion-processing task, whereby presented facial expressions changed from neutral to one of the four emotions: happy, anger, fear, or sad. Glutamate concentrations were measured before and after the emotion-processing task in right MdPFC using magnetic resonance spectroscopy (MRS). GABA concentrations were measured in bilateral MdPFC after the emotion-processing task. Multiple regression models were run to determine the relative contribution of glutamate and GABA concentration, age, and gender to BOLD signal in ACC to each of the four emotions. Multiple regression analyses revealed a significant negative correlation between MdPFC GABA concentration and BOLD signal in subgenual ACC (p<0.05, corrected) to sad versus shape contrast. For the anger versus shape contrast, there was a significant negative correlation between age and BOLD signal in pregenual ACC (p<0.05, corrected) and a positive correlation between MdPFC glutamate concentration (pre-task) and BOLD signal in pregenual ACC (p<0.05, corrected). Our findings are the first to provide insight into relationships between MdPFC neurotransmitter concentrations and ACC BOLD signal, and could further understanding of molecular mechanisms underlying emotion processing in healthy and mood-disordered individuals. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  3. GABA and glutamate levels in occlusal splint-wearing males with possible bruxism.

    PubMed

    Dharmadhikari, Shalmali; Romito, Laura M; Dzemidzic, Mario; Dydak, Ulrike; Xu, Jun; Bodkin, Cynthia L; Manchanda, Shalini; Byrd, Kenneth E

    2015-07-01

    The inhibitory neurotransmitter γ-aminobutyric acid (GABA) plays an important role in the pathophysiology of anxiety behavioural disorders such as panic disorder and post-traumatic stress disorder and is also implicated in the manifestation of tooth-grinding and clenching behaviours generally known as bruxism. In order to test whether the stress-related behaviours of tooth-grinding and clenching share similar underlying mechanisms involving GABA and other metabolites as do anxiety-related behavioural disorders, we performed a Magnetic Resonance Spectroscopy (MRS) study for accurate, in vivo metabolite quantification in anxiety-related brain regions. MRS was performed in the right hippocampus and right thalamus involved in the hypothalamic-pituitary-adrenal axis system, together with a motor planning region (dorsal anterior cingulate cortex/pre-supplementary motor area) and right dorsolateral prefrontal cortex (DLPFC). Eight occlusal splint-wearing men (OCS) with possible tooth-grinding and clenching behaviours and nine male controls (CON) with no such behaviour were studied. Repeated-measures ANOVA showed significant Group×Region interaction for GABA+ (p = 0.001) and glutamate (Glu) (p = 0.031). Between-group post hoc ANOVA showed significantly lower levels of GABA+ (p = 0.003) and higher levels of Glu (p = 0.002) in DLPFC of OCS subjects. These GABA+ and Glu group differences remained significant (GABA+, p = 0.049; Glu, p = 0.039) after the inclusion of anxiety as a covariate. Additionally, GABA and Glu levels in the DLPFC of all subjects were negatively related (Pearson's r = -0.75, p = 0.003). These findings indicate that the oral behaviours of tooth-grinding and clenching, generally known as bruxism, may be associated with disturbances in brain GABAergic and glutamatergic systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. In Vivo Measurement of GABA Transmission in Healthy Subjects and Schizophrenia Patients

    PubMed Central

    Frankle, W. Gordon; Cho, Raymond Y.; Prasad, Konasale M.; Mason, N. Scott; Paris, Jennifer; Himes, Michael L.; Walker, Christopher; Lewis, David A.; Narendran, Rajesh

    2016-01-01

    Objective Postmortem studies in schizophrenia reveal alterations in gene products that regulate the release and extracellular persistence of GABA. However, results of in vivo studies of schizophrenia measuring total tissue GABA with magnetic resonance spectroscopy (MRS) have been inconsistent. Neither the postmortem nor the MRS studies directly address the physiological properties of GABA neurotransmission. The present study addresses this question through an innovative positron emission tomography (PET) paradigm. Method The binding of [11C]flumazenil, a benzodiazepine-specific PET radiotracer, was measured before and after administration of tiagabine (0.2 mg/kg of body weight), a GABA membrane transporter (GAT1) blocker, in 17 off-medication patients with schizophrenia and 22 healthy comparison subjects. Increased extracellular GABA, through GAT1 blockade, enhances the affinity of GABAA receptors for benzodiazepine ligands, detected as an increase in [11C]flumazenil tissue distribution volume (VT). Results [11C]Flumazenil VT was significantly increased across all cortical brain regions in the healthy comparison group but not in the schizophrenia group. This lack of effect was most prominent in the antipsychotic-naive schizophrenia group. In this subgroup, [11C]flumazenil ΔVT in the medial temporal lobe was correlated with positive symptoms, and baseline [11C] flumazenil VT in the medial temporal lobe was negatively correlated with visual learning. In the healthy comparison group but not the schizophrenia group, [11C]flumazenil ΔVT was positively associated with gamma-band oscillation power. Conclusions This study demonstrates, for the first time, an in vivo impairment in GABA transmission in schizophrenia, most prominent in antipsychotic-naive individuals. The impairment in GABA transmission appears to be linked to clinical symptoms, disturbances in cortical oscillations, and cognition. PMID:26133962

  5. Beta Peak Frequencies at Rest Correlate with Endogenous GABA+/Cr Concentrations in Sensorimotor Cortex Areas

    PubMed Central

    Baumgarten, Thomas J.; Oeltzschner, Georg; Hoogenboom, Nienke; Wittsack, Hans-Jörg; Schnitzler, Alfons; Lange, Joachim

    2016-01-01

    Neuronal oscillatory activity in the beta band (15–30 Hz) is a prominent signal within the human sensorimotor cortex. Computational modeling and pharmacological modulation studies suggest an influence of GABAergic interneurons on the generation of beta band oscillations. Accordingly, studies in humans have demonstrated a correlation between GABA concentrations and power of beta band oscillations. It remains unclear, however, if GABA concentrations also influence beta peak frequencies and whether this influence is present in the sensorimotor cortex at rest and without pharmacological modulation. In the present study, we investigated the relation between endogenous GABA concentration (measured by magnetic resonance spectroscopy) and beta oscillations (measured by magnetoencephalography) at rest in humans. GABA concentrations and beta band oscillations were measured for left and right sensorimotor and occipital cortex areas. A significant positive linear correlation between GABA concentration and beta peak frequency was found for the left sensorimotor cortex, whereas no significant correlations were found for the right sensorimotor and the occipital cortex. The results show a novel connection between endogenous GABA concentration and beta peak frequency at rest. This finding supports previous results that demonstrated a connection between oscillatory beta activity and pharmacologically modulated GABA concentration in the sensorimotor cortex. Furthermore, the results demonstrate that for a predominantly right-handed sample, the correlation between beta band oscillations and endogenous GABA concentrations is evident only in the left sensorimotor cortex. PMID:27258089

  6. K+ channel TASK-1 knockout mice show enhanced sensitivities to ataxic and hypnotic effects of GABA(A) receptor ligands.

    PubMed

    Linden, Anni-Maija; Aller, M Isabel; Leppä, Elli; Rosenberg, Per H; Wisden, William; Korpi, Esa R

    2008-10-01

    TASK two-pore-domain leak K(+) channels occur throughout the brain. However, TASK-1 and TASK-3 knockout (KO) mice have few neurological impairments and only mildly reduced sensitivities to inhalational anesthetics, contrasting with the anticipated functions and importance of these channels. TASK-1/-3 channel expression can compensate for the absence of GABA(A) receptors in GABA(A) alpha6 KO mice. To investigate the converse, we analyzed the behavior of TASK-1 and -3 KO mice after administering drugs with preferential efficacies at GABA(A) receptor subtypes: benzodiazepines (diazepam and flurazepam, active at alpha1betagamma2, alpha2betagamma2, alpha3betagamma2, and alpha5betagamma2 subtypes), zolpidem (alpha1betagamma2 subtype), propofol (beta2-3-containing receptors), gaboxadol (alpha4betadelta and alpha6betadelta subtypes), pregnanolone, and pentobarbital (many subtypes). TASK-1 KO mice showed increased motor impairment in rotarod and beam-walking tests after diazepam and flurazepam administration but not after zolpidem. They also showed prolonged loss of righting reflex induced by propofol and pentobarbital. Autoradiography indicated no change in GABA(A) receptor ligand binding levels. These altered behavioral responses to GABAergic drugs suggest functional up-regulation of alpha2beta2/3gamma2 and alpha3beta2/3gamma2 receptor subtypes in TASK-1 KO mice. In addition, female, but not male, TASK-1 KO mice were more sensitive to gaboxadol, suggesting an increased influence of alpha4betadelta or alpha6betadelta subtypes. The benzodiazepine sensitivity of TASK-3 KO mice was marginally increased. Our results underline that TASK-1 channels perform such key functions in the brain that compensation is needed for their absence. Furthermore, because inhalation anesthetics act partially through GABA(A) receptors, the up-regulation of GABA(A) receptor function in TASK-1 KO mice might mask TASK-1 channel's significance as a target for inhalation anesthetics.

  7. Contribution of ventral tegmental GABA receptors to cocaine self-administration in rats.

    PubMed

    Backes, E N; Hemby, S E

    2008-03-01

    Recent evidence has suggested that compounds affecting GABAergic transmission may provide useful pharmacological tools for the treatment of cocaine addiction. Using a rat model of self-administration, the present study examined the effects of GABA agonists and antagonists injected directly into the ventral tegmental area (VTA) on cocaine intake in rats trained to self-administer cocaine (0, 125, 250 and 500 microg/infusion) under an FR5 schedule of reinforcement. Separate groups of rats received bilateral intra-VTA injections of the GABA-A antagonist picrotoxin (34 ng/side, n = 7; 68 ng/side, n = 8), GABA-A agonist muscimol (14 ng/side, n = 8), GABA-B agonist baclofen (56 ng/side, n = 7; 100 ng/side, n = 6), picrotoxin (68 ng/side) co-injected with the GABA-B antagonist 2-hydroxysaclofen (100 ng/side, n = 7; 2 microg/side, n = 8) or artificial cerebrospinal fluid (aCSF, n = 6) to assess the effects of the various compounds on the cocaine self-administration dose-response curve. Both picrotoxin and baclofen reduced responding maintained by cocaine, whereas muscimol had no effect on responding. In contrast, neither picrotoxin (n = 6) nor baclofen (n = 8) affected responding maintained by food. Interestingly, 2-hydroxysaclofen effectively blocked the suppression of responding produced by picrotoxin, suggesting that both picrotoxin and baclofen exert their effects via activation of GABA-B receptors. Additionally, these effects appear to be specific to cocaine reinforcement, supporting current investigation of baclofen as a treatment for cocaine addiction.

  8. Contribution of ventral tegmental GABA receptors to cocaine self-administration in rats

    PubMed Central

    Backes, E.N.; Hemby, S.E.

    2008-01-01

    Recent evidence has suggested that compounds affecting GABAergic transmission may provide useful pharmacological tools for the treatment of cocaine addiction. Using a rat model of self-administration, the present study examined the effects of GABA agonists and antagonists injected directly into the ventral tegmental area (VTA) on cocaine intake in rats trained to self-administer cocaine (0, 125, 250 and 500 µg/infusion) under an FR5 schedule of reinforcement. Separate groups of rats received bilateral intra-VTA injections of the GABA-A antagonist picrotoxin (34 ng/side, n=7; 68 ng/side, n=8), GABA-A agonist muscimol (14 ng/side, n=8), GABA-B agonist baclofen (56 ng/side, n=7; 100 ng/side, n=6), picrotoxin (68 ng/side) co-injected with the GABA-B antagonist 2-hydroxysaclofen (100 ng/side, n=7; 2 µg/side, n=8) or artificial cerebrospinal fluid (aCSF, n=6) to assess the effects of the various compounds on the cocaine self-administration dose-response curve. Both picrotoxin and baclofen reduced responding maintained by cocaine, whereas muscimol had no effect on responding. In contrast, neither picrotoxin (n=6) nor baclofen (n=8) affected responding maintained by food. Interestingly, 2-hydroxysaclofen effectively blocked the suppression of responding produced by picrotoxin, suggesting that both picrotoxin and baclofen exert their effects via activation of GABA-B receptors. Additionally, these effects appear to be specific to cocaine reinforcement, supporting current investigation of baclofen as a treatment for cocaine addiction. PMID:17943439

  9. Role of proline and GABA in sexual reproduction of angiosperms

    PubMed Central

    Biancucci, Marco; Mattioli, Roberto; Forlani, Giuseppe; Funck, Dietmar; Costantino, Paolo; Trovato, Maurizio

    2015-01-01

    Two glutamate derivatives, proline and γ-aminobutyric acid (GABA), appear to play pivotal roles in different aspects of sexual reproduction in angiosperms, although their precise function in plant reproduction and the molecular basis of their action are not yet fully understood. Proline and GABA have long been regarded as pivotal amino acids in pollen vitality and fertility. Proline may constitute up to 70% of the free amino acid pool in pollen grains and it has been recently shown that Arabidopsis mutants affected in the first and rate-limiting step in proline synthesis produce aberrant and infertile pollen grains, indicating that proline synthesis is required for pollen development and fertility. Concerning GABA, a large body of evidence points to this glutamate derivative as a key determinant of post-pollination fertilization. Intriguingly, proline has also been associated with pollination, another aspect of sexual reproduction, since honeybees were reported to show a strong preference for proline-enriched nectars. In this review, we survey current knowledge on the roles of proline and GABA in plant fertility, and discuss future perspectives potentially capable to improve our understanding on the functions of these amino acids in pollen development, pollination, and pollen tube guidance. PMID:26388884

  10. Regional GABA Concentrations Modulate Inter-network Resting-state Functional Connectivity.

    PubMed

    Chen, Xi; Fan, Xiaoying; Hu, Yuzheng; Zuo, Chun; Whitfield-Gabrieli, Susan; Holt, Daphne; Gong, Qiyong; Yang, Yihong; Pizzagalli, Diego A; Du, Fei; Ongur, Dost

    2018-03-28

    Coordinated activity within and differential activity between large-scale neuronal networks such as the default mode network (DMN) and the control network (CN) is a critical feature of brain organization. The CN usually exhibits activations in response to cognitive tasks while the DMN shows deactivations; in addition, activity between the two networks is anti-correlated at rest. To address this issue, we used functional MRI to measure whole-brain BOLD signal during resting-state and task-evoked conditions, and MR spectroscopy (MRS) to quantify GABA and glutamate concentrations, in nodes within the DMN and CN (MPFC and DLPFC, respectively) in 19 healthy individuals at 3 Tesla. We found that GABA concentrations in the MPFC were significantly associated with DMN deactivation during a working memory task and with anti-correlation between DMN and CN at rest and during task performance, while GABA concentrations in the DLPFC weakly modulated DMN-CN anti-correlation in the opposite direction. Highlighting specificity, glutamate played a less significant role related to brain activity. These findings indicate that GABA in the MPFC is potentially involved in orchestrating between-network brain activity at rest and during task performance.

  11. Endogenous GABA levels in the pontine reticular formation are greater during wakefulness than during REM sleep

    PubMed Central

    Vanini, Giancarlo; Wathen, Bradley L.; Lydic, Ralph; Baghdoyan, Helen A.

    2011-01-01

    Studies using drugs that increase or decrease GABAergic transmission suggest that GABA in the pontine reticular formation (PRF) promotes wakefulness and inhibits rapid eye movement (REM) sleep. Cholinergic transmission in the PRF promotes REM sleep, and levels of endogenous acetylcholine (ACh) in the PRF are significantly greater during REM sleep than during wakefulness or non-REM (NREM) sleep. No previous studies have determined whether levels of endogenous GABA in the PRF vary as a function of sleep and wakefulness. This study tested the hypothesis that GABA levels in cat PRF are greatest during wakefulness and lowest during REM sleep. Extracellular GABA levels were measured during wakefulness, NREM sleep, REM sleep, and the REM sleep-like state (REMNeo) caused by microinjecting neostigmine into the PRF. GABA levels varied significantly as a function of sleep and wakefulness, and decreased significantly below waking levels during REM sleep (−42%) and REMNeo (−63%). The decrease in GABA levels during NREM sleep (22% below waking levels) was not statistically significant. Compared to NREM sleep, GABA levels decreased significantly during REM sleep (−27%) and REMNeo (−52%). Comparisons of REM sleep and REMNeo revealed no differences in GABA levels or cortical EEG power. GABA levels did not vary significantly as a function of dialysis site within the PRF. The inverse relationship between changes in PRF levels of GABA and ACh during REM sleep indicates that low GABAergic tone combined with high cholinergic tone in the PRF contributes to the generation of REM sleep. PMID:21325533

  12. Topographic specializations of catecholaminergic cells and ganglion cells and distribution of calcium binding proteins in the crepuscular rock cavy (Kerodon rupestris) retina.

    PubMed

    Oliveira, Francisco Gilberto; Nascimento-Júnior, Expedito Silva do; Cavalcante, Judney Cley; Guzen, Fausto Pierdoná; Cavalcante, Jeferson de Souza; Soares, Joacil Germano; Cavalcanti, José Rodolfo Lopes de Paiva; Freitas, Leandro Moura de; Costa, Miriam Stela Maris de Oliveira; Andrade-da-Costa, Belmira Lara da Silveira

    2018-07-01

    The rock cavy (Kerodon rupestris) is a crepuscular Hystricomorpha rodent that has been used in comparative analysis of retinal targets, but its retinal organization remains to be investigated. In order to better characterize its visual system, the present study analyzed neurochemical features related to the topographic organization of catecholaminergic cells and ganglion cells, as well the distribution of calcium-binding proteins in the outer and inner retina. Retinal sections and/or wholemounts were processed using tyrosine hydroxylase (TH), GABA, calbindin, parvalbumin and calretinin immunohistochemistry or Nissl staining. Two types of TH-immunoreactive (TH-IR) cells were found which differ in soma size, dendritic arborization, intensity of TH immunoreactivity and stratification pattern in the inner plexiform layer. The topographic distribution of all TH-IR cells defines a visual streak along the horizontal meridian in the superior retina. The ganglion cells are also distributed in a visual streak and the visual acuity estimated considering their peak density is 4.13 cycles/degree. A subset of TH-IR cells express GABA or calbindin. Calretinin is abundant in most of retinal layers and coexists with calbindin in horizontal cells. Parvalbumin is less abundant and expressed by presumed amacrine cells in the INL and some ganglion cells in the GCL. The topographic distribution of TH-IR cells and ganglion cells in the rock cavy retina indicate a suitable adaptation for using a broad extension of its inferior visual field in aspects that involve resolution, adjustment to ambient light intensity and movement detection without specialized eye movements. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Impact of Precooling and Controlled-Atmosphere Storage on γ-Aminobutyric Acid (GABA) Accumulation in Longan (Dimocarpus longan Lour.) Fruit.

    PubMed

    Zhou, Molin; Ndeurumio, Kessy H; Zhao, Lei; Hu, Zhuoyan

    2016-08-24

    Longan (Dimocarpus longan Lour.) fruit cultivars 'Chuliang' and 'Shixia' were analyzed for γ-aminobutyric acid (GABA) accumulation after precooling and in controlled-atmosphere storage. Fruit were exposed to 5% O2 plus 3%, 5%, or 10% CO2 at 4 °C, and GABA and associated enzymes, aril firmness, and pericarp color were measured. Aril softening and pericarp browning were delayed by 5% CO2 + 5% O2. GABA concentrations and glutamate decarboxylase (GAD; EC 4.1.1.15) activities declined during storage at the higher-CO2 treatments. However, GABA aminotransferase (GABA-T; EC 2.6.1.19) activities in elevated CO2-treated fruit fluctuated during storage. GABA concentrations increased after precooling treatments. GAD activity and GABA-T activity were different between cultivars after precooling. GABA concentrations in fruit increased after 3 days of 10% CO2 + 5% O2 treatment and then declined as storage time increased. GABA accumulation was associated with stimulation of GAD activity rather than inhibition of GABA-T activity.

  14. Different populations of parvalbumin- and calbindin-D28k-immunoreactive neurons contain GABA and accumulate 3H-D-aspartate in the dorsal horn of the rat spinal cord.

    PubMed

    Antal, M; Polgár, E; Chalmers, J; Minson, J B; Llewellyn-Smith, I; Heizmann, C W; Somogyi, P

    1991-12-01

    The colocalization of parvalbumin (PV), calbindin-D28k (CaBP), GABA immunoreactivities, and the ability to accumulate 3H-D-aspartate selectively were investigated in neurons of laminae I-IV of the dorsal horn of the rat spinal cord. Following injection of 3H-D-aspartate into the basal dorsal horn (laminae IV-VI), perikarya selectively accumulating 3H-D-aspartate were detected in araldite embedded semithin sections by autoradiography, and consecutive semithin sections were treated to reveal PV, CaBP and GABA by postembedding immunocytochemistry. Perikarya accumulating 3H-D-aspartate were found exclusively in laminae I-III, and no labelled somata were found in deeper layers or in the intermediolateral column although the labelled amino acid clearly spread to these regions. More than half of the labelled cells were localized in lamina II. In this layer, 16.4% of 3H-D-aspartate-labelled perikarya were also stained for CaBP. In contrast to CaBP, PV or GABA was never detected in neurons accumulating 3H-D-aspartate. A high proportion of PV-immunoreactive perikarya were also stained for GABA in laminae II and III (70.0% and 61.2% respectively). However, the majority of CaBP-immunoreactive perikarya were GABA-negative. GABA-immunoreactivity was found in less than 2% of the total population of cells stained for CaBP in laminae I-IV. A significant proportion of the GABA-negative but PV-immunoreactive neurons also showed CaBP-immunoreactivity in laminae II and IV. These results show that out of the two calcium-binding proteins, CaBP is a characteristic protein of a small subpopulation of neurons using excitatory amino acids and PV is a characteristic protein of a subpopulation of neurons utilizing GABA as a transmitter. However, both proteins are present in additional subgroups of neurons, and neuronal populations using inhibitory or excitatory amino acid transmitters are heterogeneous with regard to their content of calcium-binding proteins in the dorsal horn of the rat

  15. Enhanced productivity of gamma-amino butyric acid by cascade modifications of a whole-cell biocatalyst.

    PubMed

    Yang, Xinwei; Ke, Chongrong; Zhu, Jiangming; Wang, Yan; Zeng, Wenchao; Huang, Jianzhong

    2018-04-01

    We previously developed a gamma-amino butyric acid (GABA)-producing strain of Escherichia coli, leading to production of 614.15 g/L GABA at 45 °C from L-glutamic acid (L-Glu) with a productivity of 40.94 g/L/h by three successive whole-cell conversion cycles. However, the increase in pH caused by the accumulation of GABA resulted in inactivation of the biocatalyst and consequently led to relatively lower productivity. In this study, by overcoming the major problem associated with the increase in pH during the production process, a more efficient biocatalyst was obtained through cascade modifications of the previously reported E. coli strain. First, we introduced four amino acid mutations to the codon-optimized GadB protein from Lactococcus lactis to shift its decarboxylation activity toward a neutral pH, resulting in 306.65 g/L of GABA with 99.14 mol% conversion yield and 69.8% increase in GABA productivity. Second, we promoted transportation of L-Glu and GABA by removing the genomic region encoding the C-plug of GadC (a glutamate/GABA antiporter) to allow its transport path to remain open at a neutral pH, which improved the GABA productivity by 16.8% with 99.3 mol% conversion of 3 M L-Glu. Third, we enhanced the expression of soluble GadB by introducing the GroESL molecular chaperones, leading to 20.2% improvement in GABA productivity, with 307.40 g/L of GABA and a 61.48 g/L/h productivity obtained in one cycle. Finally, we inhibited the degradation of GABA by inactivation of gadA and gadB from the E. coli genome, which resulted in almost no GABA degradation after 40 h. After the cascade system modifications, the engineered recombinant E. coli strain achieved a 44.04 g/L/h productivity with a 99.6 mol% conversion of 3 M L-Glu in a 5-L bioreactor, about twofold increase in productivity compared to the starting strain. This increase represents the highest GABA productivity by whole-cell bioconversion using L-Glu as a substrate in one cycle observed

  16. Individual differences in GABA content are reliable but are not uniform across the human cortex

    PubMed Central

    Greenhouse, Ian; Noah, Sean; Maddock, Richard J; Ivry, Richard B

    2016-01-01

    1H magnetic resonance spectroscopy (MRS) provides a powerful tool to measure gamma-aminobutyric acid (GABA), the principle inhibitory neurotransmitter in the human brain. We asked whether individual differences in MRS estimates of GABA are uniform across the cortex or vary between regions. In two sessions, resting GABA concentrations in the lateral prefrontal, sensorimotor, dorsal premotor, and occipital cortices were measured in twenty-eight healthy individuals. GABA estimates within each region were stable across weeks, with low coefficients of variation. Despite this stability, the GABA estimates were not correlated between regions. In contrast, the percentage of brain tissue per volume, a control measure, was correlated between the three anterior regions. These results provide an interesting dissociation between an anatomical measure of individual differences and a neurochemical measure. The different patterns of anatomy and GABA concentrations have implications for understanding regional variation in the molecular topography of the brain in health and disease. PMID:27288552

  17. Vortioxetine Treatment Reverses Subchronic PCP Treatment-Induced Cognitive Impairments: A Potential Role for Serotonin Receptor-Mediated Regulation of GABA Neurotransmission

    PubMed Central

    Pehrson, Alan L.; Pedersen, Christian S.; Tølbøl, Kirstine Sloth; Sanchez, Connie

    2018-01-01

    Major depressive disorder (MDD) is associated with cognitive impairments that may contribute to poor functional outcomes. Clinical data suggests that the multimodal antidepressant vortioxetine attenuates some cognitive impairments in MDD patients, but the mechanistic basis for these improvements is unclear. One theory suggests that vortioxetine improves cognition by suppressing γ-amino butyric acid (GABA)ergic neurotransmission, thereby increasing glutamatergic activation. Vortioxetine’s effects on cognition, GABA and glutamate neurotransmission have been supported in separate experiments, but no empirical work has directly connected vortioxetine’s cognitive effects to those on GABA and glutamate neurotransmission. In this paper, we attempt to bridge this gap by evaluating vortioxetine’s effects in the subchronic PCP (subPCP) model, which induces impaired cognitive function and altered GABA and glutamate neurotransmission. We demonstrate that acute or subchronic vortioxetine treatment attenuated subPCP-induced deficits in attentional set shifting (AST) performance, and that the selective 5-HT3 receptor antagonist ondansetron or the 5-HT reuptake inhibitor escitalopram could mimic this effect. Furthermore, acute vortioxetine treatment reversed subPCP-induced object recognition (OR) deficits in rats, while subchronic vortioxetine reversed subPCP-induced Object Recognition and object placement impairments in mice. Finally, subPCP treatment reduced GABAB receptor expression in a manner that was insensitive to vortioxetine treatment, and subchronic vortioxetine treatment alone, but not in combination with subPCP, significantly increased GABA’s affinity for the GABAA receptor. These data suggest that vortioxetine reverses cognitive impairments in a model associated with altered GABA and glutamate neurotransmission, further supporting the hypothesis that vortioxetine’s GABAergic and glutamatergic effects are relevant for cognitive function. PMID:29559911

  18. Correlation between the enhancement of flunitrazepam binding by GABA and seizure susceptibility in mice

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marley, R.J.; Wehner, J.M.

    Various populations of mice exhibit differential sensitivity to seizure-inducing agents. The relationship of seizure susceptibility to alterations in the GABA receptor complex was investigated in six different populations of mice consisting of four inbred strains (C57BL, DBA, C3H, and BALB) and two selected lines (long sleep and short sleep). Seizure activity was induced by intraperitoneal administration of the GAD inhibitor, 3-mercaptopropionic acid, and latencies to seizure onset and tonus were measured. In naive mice of the same populations, GABA enhancement of TH-flunitrazepam binding was measured in extensively washed whole brain membranes at several GABA concentrations. Both differential seizure sensitivity tomore » 3-mercaptopropionic acid and differential enhancement of TH-flunitrazepam binding by GABA were observed in these six populations of mice. Correlational analyses indicated a positive correlation between the degree of GABA enhancement of TH-flunitrazepam binding and resistance to the seizure-inducing properties of 3-mercaptopropionic acid. These data suggest that genetic differences in sensitivity to seizure-inducing agents that disrupt the GABAergic system may be related to differences in coupling between the various receptors associated with the GABA receptor complex.« less

  19. Global gene expression analyses of hematopoietic stem cell-like cell lines with inducible Lhx2 expression

    PubMed Central

    Richter, Karin; Wirta, Valtteri; Dahl, Lina; Bruce, Sara; Lundeberg, Joakim; Carlsson, Leif; Williams, Cecilia

    2006-01-01

    Background Expression of the LIM-homeobox gene Lhx2 in murine hematopoietic cells allows for the generation of hematopoietic stem cell (HSC)-like cell lines. To address the molecular basis of Lhx2 function, we generated HSC-like cell lines where Lhx2 expression is regulated by a tet-on system and hence dependent on the presence of doxycyclin (dox). These cell lines efficiently down-regulate Lhx2 expression upon dox withdrawal leading to a rapid differentiation into various myeloid cell types. Results Global gene expression of these cell lines cultured in dox was compared to different time points after dox withdrawal using microarray technology. We identified 267 differentially expressed genes. The majority of the genes overlapping with HSC-specific databases were those down-regulated after turning off Lhx2 expression and a majority of the genes overlapping with those defined as late progenitor-specific genes were the up-regulated genes, suggesting that these cell lines represent a relevant model system for normal HSCs also at the level of global gene expression. Moreover, in situ hybridisations of several genes down-regulated after dox withdrawal showed overlapping expression patterns with Lhx2 in various tissues during embryonic development. Conclusion Global gene expression analysis of HSC-like cell lines with inducible Lhx2 expression has identified genes putatively linked to self-renewal / differentiation of HSCs, and function of Lhx2 in organ development and stem / progenitor cells of non-hematopoietic origin. PMID:16600034

  20. Anterior Insula GABA Levels Correlate with Emotional Aspects of Empathy: A Proton Magnetic Resonance Spectroscopy Study

    PubMed Central

    Dong, Fang; Chen, Luguang; Zheng, Li; Guo, Xiuyan; Li, Jianqi

    2014-01-01

    Background: Empathy is a multidimensional construct referring to the capacity to understand and share the emotional and affective states of another person. Cerebral γ-aminobutyric acid (GABA)-ergic levels are associated with a variety of neurological and psychiatric disorders. However, the role of the GABA system in different dimensions of empathy has not been investigated. Materials and Methods: Thirty-two right-handed healthy volunteers took part in this study. We used proton magnetic resonance spectroscopy to determine GABA concentrations in the anterior insula (AI) and the anterior cingulate cortex (ACC) and to examine the relationship between the GABA concentrations and the subcomponents of empathy evaluated by the Interpersonal Reactivity Index (IRI). Result: Pearson correlation analyses (two-tailed) showed that AI GABA was significantly associated with the empathy concern score (r = 0.584, p<0.05) and the personal distress score (r = 0.538, p<0.05) but not significantly associated with other empathy subscales. No significant correlation was found between ACC GABA and empathy subscores. Conclusion: Left AI GABA was positively correlated with the emotional aspects of empathy. These preliminary findings call into question whether AI GABA alterations might predict empathy dysfunction in major psychiatric disorders such as autism and schizophrenia, which have been described as deficits in emotional empathic abilities. PMID:25419976

  1. GABA concentration is reduced in visual cortex in schizophrenia and correlates with orientation-specific surround suppression.

    PubMed

    Yoon, Jong H; Maddock, Richard J; Rokem, Ariel; Silver, Michael A; Minzenberg, Michael J; Ragland, J Daniel; Carter, Cameron S

    2010-03-10

    The neural mechanisms underlying cognitive deficits in schizophrenia remain essentially unknown. The GABA hypothesis proposes that reduced neuronal GABA concentration and neurotransmission results in cognitive impairments in schizophrenia. However, few in vivo studies have directly examined this hypothesis. We used magnetic resonance spectroscopy (MRS) at high field to measure visual cortical GABA levels in 13 subjects with schizophrenia and 13 demographically matched healthy control subjects. We found that the schizophrenia group had an approximately 10% reduction in GABA concentration. We further tested the GABA hypothesis by examining the relationship between visual cortical GABA levels and orientation-specific surround suppression (OSSS), a behavioral measure of visual inhibition thought to be dependent on GABAergic synaptic transmission. Previous work has shown that subjects with schizophrenia exhibit reduced OSSS of contrast discrimination (Yoon et al., 2009). For subjects with both MRS and OSSS data (n = 16), we found a highly significant positive correlation (r = 0.76) between these variables. GABA concentration was not correlated with overall contrast discrimination performance for stimuli without a surround (r = -0.10). These results suggest that a neocortical GABA deficit in subjects with schizophrenia leads to impaired cortical inhibition and that GABAergic synaptic transmission in visual cortex plays a critical role in OSSS.

  2. Optimization of culture condition for ACEI and GABA production by lactic acid bacteria.

    PubMed

    Tung, Yi-Ting; Lee, Bao-Hong; Liu, Chin-Feng; Pan, Tzu-Ming

    2011-01-01

    Gamma-aminobutyric acid (GABA) and angiotensin-converting enzyme inhibitor (ACEI) are compounds which can influence hypertension. The goal of this study is to optimize the culture condition for GABA and ACEI production by Lactobacillus plantarum NTU 102 fermented skim milk. In this study, we used 3-factor-3-level Box-Behnken design combining with response surface methodology, where the 3 factors represent the concentration of skim milk, the concentration of monosodium glutamate, and culture temperature. Best conditions for GABA and ACEI production differed. The results indicated that L. plantarum NTU 102 produced the highest combined levels of GABA and ACEI at 37 °C, in milk having 8% to 12% nonfat solids supplemented with 0.6% to 1% MSG. Agitation of the medium during fermentation had no effect on GABA or ACEI production but extended incubation (up to 6 d) increases levels of the bioactive compounds. L. plantarum NTU 102 fermented products may be a potential functional food source for regulating hypertension. © 2011 Institute of Food Technologists®

  3. Prefrontal Cortical GABA Levels in Panic Disorder Determined by Proton Magnetic Resonance Spectroscopy

    PubMed Central

    Hasler, Gregor; van der Veen, Jan Willem; Geraci, Marilla; Shen, Jun; Pine, Daniel; Drevets, Wayne C.

    2009-01-01

    Background Panic disorder (PD) is hypothesized to be associated with altered function of the major inhibitory neurotransmitter, gamma-amino butyric acid (GABA). Previous proton magnetic resonance spectroscopy (MRS) studies found lower GABA concentrations in the occipital cortex of subjects with PD relative to healthy controls. The current study is the first MRS study to compare GABA concentrations between unmedicated PD subjects and controls in the prefrontal cortex (PFC). Methods Unmedicated subjects with PD (n=17) and age- and sex-matched healthy controls (n=17) were scanned on a 3 Tesla scanner using a transmit-receive head coil that provided a sufficiently homogenous radiofrequency field to obtain spectroscopic measurements in the dorsomedial/dorsal anterolateral and ventromedial areas of the PFC. Results The prefrontal cortical GABA concentrations did not differ significantly between PD subjects and controls. There also was no statistically significant difference in Glx, choline or N-acetyl-aspartate concentrations. Conclusions The previously reported finding of reduced GABA concentrations in the occipital cortex of PD subjects does not appear to extend to the PFC. PMID:18692172

  4. Behavioral effects of gamma-hydroxybutyrate, its precursor gamma-butyrolactone, and GABA(B) receptor agonists: time course and differential antagonism by the GABA(B) receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348).

    PubMed

    Koek, Wouter; Mercer, Susan L; Coop, Andrew; France, Charles P

    2009-09-01

    Gamma-hydroxybutyrate (GHB) is used therapeutically and recreationally. The mechanism by which GHB produces its therapeutic and recreational effects is not entirely clear, although GABA(B) receptors seem to play an important role. This role could be complex, because there are indications that different GABA(B) receptor mechanisms mediate the effects of GHB and the prototypical GABA(B) receptor agonist baclofen. To further explore possible differences in underlying GABA(B) receptor mechanisms, the present study examined the effects of GHB and baclofen on operant responding and their antagonism by the GABA(B) receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348). Pigeons were trained to peck a key for access to food during response periods that started at different times after the beginning of the session. In these pigeons, GHB, its precursor gamma-butyrolactone (GBL), and the GABA(B) receptor agonists baclofen and 3-aminopropyl(methyl)phosphinic acid hydrochloride (SKF97541) decreased the rate of responding in a dose- and time-dependent manner. CGP35348 shifted the dose-response curve of each agonist to the right, but the magnitude of the shift differed among the agonists. Schild analysis yielded a pA(2) value of CGP35348 to antagonize GHB and GBL [i.e., 3.9 (3.7-4.2)] that was different (P = 0.0011) from the pA(2) value to antagonize baclofen and SKF97541 [i.e., 4.5 (4.4-4.7)]. This finding is further evidence that the GABA(B) receptor mechanisms mediating the effects of GHB and prototypical GABA(B) receptor agonists are not identical. A better understanding of the similarities and differences between these mechanisms, and their involvement in the therapeutic effects of GHB and baclofen, could lead to more effective medications with fewer adverse effects.

  5. Reduced Chrna7 expression in mice is associated with decreases in hippocampal markers of inhibitory function: implications for neuropsychiatric diseases.

    PubMed

    Adams, C E; Yonchek, J C; Schulz, K M; Graw, S L; Stitzel, J; Teschke, P U; Stevens, K E

    2012-04-05

    The α7* nicotinic acetylcholine receptor encoded by CHRNA7 (human)/Chrna7 (mice) regulates the release of both the inhibitory neurotransmitter GABA and the excitatory neurotransmitter glutamate in the hippocampal formation. A heterozygous (Het) deletion at 15q13.3 containing CHRNA7 is associated with increased risk for schizophrenia, autism, and epilepsy. Each of these diseases are characterized by abnormalities in excitatory and inhibitory hippocampal circuit function. Reduced Chrna7 expression results in decreased hippocampal α7* receptor density, abnormal hippocampal auditory sensory processing, and increased hippocampal CA3 pyramidal neuron activity in C3H mice Het for a null mutation in Chrna7. These abnormalities demonstrate that decreased Chrna7 expression alters hippocampal inhibitory circuit function. The current study examined the specific impact of reduced Chrna7 expression on hippocampal inhibitory circuits by measuring the levels of GABA, GABA(A) receptors, the GABA synthetic enzyme l-glutamic acid decarboxylase-65 (GAD-65), and the vesicular GABA transporter 1 (GAT-1) in wild-type (Chrna7 +/+) and Het (Chrna7 +/-) C3H α7 mice of both genders. GAD-65 levels were significantly decreased in male and female Het C3H α7 mice, whereas GABA(A) receptors were significantly reduced only in male Het C3H α7 mice. No changes in GABA and GAT-1 levels were detected. These data suggest that reduced CHRNA7 expression may contribute to the abnormalities in hippocampal inhibitory circuits observed in schizophrenia, autism, and/or epilepsy. Published by Elsevier Ltd.

  6. Self-enhancement of GABA in rice bran using various stress treatments.

    PubMed

    Kim, Hyun Soo; Lee, Eun Jung; Lim, Seung-Taik; Han, Jung-Ah

    2015-04-01

    Gamma-aminobutyric acid (GABA) may be synthesized in plant tissues when the organism is under stressful conditions. Rice bran byproduct obtained from the milling of brown rice was treated under anaerobic storage with nitrogen at different temperatures (20-60 °C) and moisture contents (10-50%) up to 12h. For the GABA synthesis, the storage at 30% moisture content and 40 °C appeared optimal. Utilisation of an electrolyzed oxidizing water (EOW, pH 3.3) for moisture adjustment and addition of glutamic acid increased the GABA content in rice bran. The maximum GABA content in rice bran (523 mg/100g) could be achieved by the anaerobic storage at 30% EOW for 5h at 40 °C after an addition of glutamic acid (5mM). This amount was approximately 17 times higher than that in the control (30 mg/100g). The use of EOW also prevented bacterial growth by decreasing the colony counts almost by half. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Elevated prefrontal cortex GABA in patients with major depressive disorder after TMS treatment measured with proton magnetic resonance spectroscopy

    PubMed Central

    Dubin, Marc J.; Mao, Xiangling; Banerjee, Samprit; Goodman, Zachary; Lapidus, Kyle A.B.; Kang, Guoxin; Liston, Conor; Shungu, Dikoma C.

    2016-01-01

    Background GABAergic and glutamatergic neurotransmitter systems are central to the pathophysiology of depression and are potential targets of repetitive transcranial magnetic stimulation (rTMS). We assessed the effect of 10-Hz rTMS over the left dorsolateral prefrontal cortex (DLPFC) of patients with major depressive disorder on the levels of medial prefrontal cortex (MPFC) γ-aminobutyric acid (GABA) and the combined resonance of glutamate and glutamine (Glx) as assessed in vivo with proton magnetic resonance spectroscopy (1H MRS). Methods Currently depressed individuals between the ages of 23 and 68 years participated in a 5-week naturalistic, open-label treatment study of rTMS, with 1H MRS measurements of MPFC GABA and Glx levels at baseline and following 5 weeks of the rTMS intervention. We applied rTMS pulses over the left DLPFC at 10 Hz and 80%–120% of motor threshold for 25 daily sessions, with each session consisting of 3000 pulses. We assessed therapeutic response using the 24-item Hamilton Rating Scale for Depression (HAMD24). The GABA and Glx levels are expressed as ratios of peak areas relative to the area of the synchronously acquired and similarly fitted unsuppressed voxel water signal (W). Results Twenty-three currently depressed individuals (7 men) participated in the study. GABA/W in the MPFC increased 13.8% (p = 0.013) in all depressed individuals. There were no significant effects of rTMS on Glx/W. GABA/W and Glx/W were highly correlated in severely depressed patients at baseline but not after TMS. Limitations The primary study limitations are the open-label design and the inclusion of participants currently taking stable regimens of antidepressant medications. Conclusion These results implicate GABAergic and glutamatergic systems in the mechanism of action of rTMS for major depression, warranting further investigation in larger samples. PMID:26900793

  8. Antidepressants and seizure-interactions at the GABA-receptor chloride-ionophore complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Malatynska, E.; Knapp, R.J.; Ikeda, M.

    1988-01-01

    Convulsive seizures are a potential side effect of antidepressant drug treatment and can be produced by all classes of antidepressants. It is also know that some convulsant and anticonvulsant drug actions are mediated by the GABA-receptor chloride-ionophore complex. Drugs acting at this complex appear to induce convulsions by inhibiting chloride conductance through the associated chloride channel. Using the method of GABA-stimulated /sup 36/Cl-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs can inhibit the GABA-receptor chloride uptake, and that the degree of chloride channel inhibition by these drugs correlates with the frequency of convulsive seizures induced bymore » them.« less

  9. Decreased GABA-A binding on FMZ-PET in succinic semialdehyde dehydrogenase deficiency.

    PubMed

    Pearl, P L; Gibson, K M; Quezado, Z; Dustin, I; Taylor, J; Trzcinski, S; Schreiber, J; Forester, K; Reeves-Tyer, P; Liew, C; Shamim, S; Herscovitch, P; Carson, R; Butman, J; Jakobs, C; Theodore, W

    2009-08-11

    Succinic semialdehyde dehydrogenase (SSADH) deficiency is an autosomal recessive disorder of GABA metabolism characterized by elevated levels of GABA and gamma-hydroxybutyric acid. Clinical findings include intellectual impairment, hypotonia, hyporeflexia, hallucinations, autistic behaviors, and seizures. Autoradiographic labeling and slice electrophysiology studies in the murine model demonstrate use-dependent downregulation of GABA(A) receptors. We studied GABA(A) receptor activity in human SSADH deficiency utilizing [(11)C]-flumazenil (FMZ)-PET. FMZ binding was measured in 7 patients, 10 unaffected parents, and 8 healthy controls. Data analysis was performed using a reference region compartmental model, with time-activity curve from pons as the input function. Relative parametric binding potential (BP(ND)) was derived, with MRI-based pixel by pixel partial volume correction, in regions of interest drawn on coregistered MRI. In amygdala, hippocampus, cerebellar vermis, frontal, parietal, and occipital cortex, patients with SSADH deficiency had significant reductions in FMZ BP(ND) compared to parents and controls. Mean cortical values were 6.96 +/- 0.79 (controls), 6.89 +/- 0.71 (parents), and 4.88 +/- 0.77 (patients) (F ratio 16.1; p < 0.001). There were no differences between controls and parents in any cortical region. Succinic semialdehyde dehydrogenase (SSADH) deficient patients show widespread reduction in BZPR binding on [(11)C]-flumazenil-PET. Our results suggest that high endogenous brain GABA levels in SSADH deficiency downregulate GABA(A)-BZPR binding site availability. This finding suggests a potential mechanism for neurologic dysfunction in a serious neurodevelopmental disorder, and suggests that PET may be useful to translate studies in animal models to human disease.

  10. GABA content within the ventromedial prefrontal cortex is related to trait anxiety.

    PubMed

    Delli Pizzi, Stefano; Padulo, Caterina; Brancucci, Alfredo; Bubbico, Giovanna; Edden, Richard A; Ferretti, Antonio; Franciotti, Raffaella; Manippa, Valerio; Marzoli, Daniele; Onofrj, Marco; Sepede, Gianna; Tartaro, Armando; Tommasi, Luca; Puglisi-Allegra, Stefano; Bonanni, Laura

    2016-05-01

    The ventromedial prefrontal cortex (vmPFC) plays a key role in emotion processing and regulation. vmPFC dysfunction may lead to disinhibition of amygdala causing high anxiety levels. γ-Aminobutyric acid (GABA) inter-neurons within vmPFC shape the information flow to amygdala. Thus, we hypothesize that GABA content within vmPFC could be relevant to trait anxiety. Forty-three healthy volunteers aged between 20 and 88 years were assessed for trait anxiety with the Subscale-2 of the State-Trait-Anxiety Inventory (STAI-Y2) and were studied with proton magnetic resonance spectroscopy to investigate GABA and Glx (glutamate+glutamine) contents within vmPFC. Total creatine (tCr) was used as internal reference. Partial correlations assessed the association between metabolite levels and STAI-Y2 scores, removing the effect of possible nuisance factors including age, educational level, volumes of gray matter and white matter within magnetic resonance spectroscopy voxel. We observed a positive relationship between GABA/tCr and STAI-Y2 scores. No significant relationships were found between Glx/tCr and STAI-Y2 and between tCr/water and STAI-Y2. No differences were found between males and females as regards to age, STAI-Y2, GABA/tCr, Glx/tCr, tCr/water, gray matter and white matter volumes. We suggest a close relationship between GABA content within vmPFC and trait anxiety providing new insights in the physiology of emotional brain. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  11. Non-neuronal, slow GABA signalling in the ventrobasal thalamus targets δ-subunit-containing GABAA receptors

    PubMed Central

    Jiménez-González, Cristina; Pirttimaki, Tiina; Cope, David W; Parri, H R

    2011-01-01

    The rodent ventrobasal (VB) thalamus contains a relatively uniform population of thalamocortical (TC) neurons that receive glutamatergic input from the vibrissae and the somatosensory cortex, and inhibitory input from the nucleus reticularis thalami (nRT). In this study we describe γ-aminobutyric acid (GABA)A receptor-dependent slow outward currents (SOCs) in TC neurons that are distinct from fast inhibitory postsynaptic currents (IPSCs) and tonic currents. SOCs occurred spontaneously or could be evoked by hypo-osmotic stimulus, and were not blocked by tetrodotoxin, removal of extracellular Ca2+ or bafilomycin A1, indicating a non-synaptic, non-vesicular GABA origin. SOCs were more common in TC neurons of the VB compared with the dorsal lateral geniculate nucleus, and were rarely observed in nRT neurons, whilst SOC frequency in the VB increased with age. Application of THIP, a selective agonist at δ-subunit-containing GABAA receptors, occluded SOCs, whereas the benzodiazepine site inverse agonist β-CCB had no effect, but did inhibit spontaneous and evoked IPSCs. In addition, the occurrence of SOCs was reduced in mice lacking the δ-subunit, and their kinetics were also altered. The anti-epileptic drug vigabatrin increased SOC frequency in a time-dependent manner, but this effect was not due to reversal of GABA transporters. Together, these data indicate that SOCs in TC neurons arise from astrocytic GABA release, and are mediated by δ-subunit-containing GABAA receptors. Furthermore, these findings suggest that the therapeutic action of vigabatrin may occur through the augmentation of this astrocyte–neuron interaction, and highlight the importance of glial cells in CNS (patho) physiology. PMID:21395866

  12. Dietary GABA and food selection by rats.

    PubMed

    Tews, J K; Repa, J J; Harper, A E

    1986-01-01

    To obtain further information pertaining to amino acid-induced alterations in feeding behavior, studies were performed to examine the food choices made by rats fed low protein diets made more or less aversive by the addition of various amino acids. When rats were allowed to choose between two diets, they preferred a low protein control, threonine-imbalanced or nonprotein diet to one containing 2.5% gamma-aminobutyric acid (GABA). Acceptance increased when GABA content was lowered to 1.5%; rats preferred this diet when the alternative diet was made sufficiently aversive. There were large individual differences among rats selecting from pairs of unacceptable diets. Avoidance of, or preference for, a given diet is clearly affected by the relative aversive qualities of the offered pair of diets.

  13. New inducible genetic method reveals critical roles of GABA in the control of feeding and metabolism.

    PubMed

    Meng, Fantao; Han, Yong; Srisai, Dollada; Belakhov, Valery; Farias, Monica; Xu, Yong; Palmiter, Richard D; Baasov, Timor; Wu, Qi

    2016-03-29

    Currently available inducible Cre/loxP systems, despite their considerable utility in gene manipulation, have pitfalls in certain scenarios, such as unsatisfactory recombination rates and deleterious effects on physiology and behavior. To overcome these limitations, we designed a new, inducible gene-targeting system by introducing an in-frame nonsense mutation into the coding sequence of Cre recombinase (nsCre). Mutant mRNAs transcribed from nsCre transgene can be efficiently translated into full-length, functional Cre recombinase in the presence of nonsense suppressors such as aminoglycosides. In a proof-of-concept model, GABA signaling from hypothalamic neurons expressing agouti-related peptide (AgRP) was genetically inactivated within 4 d after treatment with a synthetic aminoglycoside. Disruption of GABA synthesis in AgRP neurons in young adult mice led to a dramatic loss of body weight due to reduced food intake and elevated energy expenditure; they also manifested glucose intolerance. In contrast, older mice with genetic inactivation of GABA signaling by AgRP neurons had only transient reduction of feeding and body weight; their energy expenditure and glucose tolerance were unaffected. These results indicate that GABAergic signaling from AgRP neurons plays a key role in the control of feeding and metabolism through an age-dependent mechanism. This new genetic technique will augment current tools used to elucidate mechanisms underlying many physiological and neurological processes.

  14. New inducible genetic method reveals critical roles of GABA in the control of feeding and metabolism

    PubMed Central

    Meng, Fantao; Han, Yong; Srisai, Dollada; Belakhov, Valery; Farias, Monica; Xu, Yong; Palmiter, Richard D.; Baasov, Timor; Wu, Qi

    2016-01-01

    Currently available inducible Cre/loxP systems, despite their considerable utility in gene manipulation, have pitfalls in certain scenarios, such as unsatisfactory recombination rates and deleterious effects on physiology and behavior. To overcome these limitations, we designed a new, inducible gene-targeting system by introducing an in-frame nonsense mutation into the coding sequence of Cre recombinase (nsCre). Mutant mRNAs transcribed from nsCre transgene can be efficiently translated into full-length, functional Cre recombinase in the presence of nonsense suppressors such as aminoglycosides. In a proof-of-concept model, GABA signaling from hypothalamic neurons expressing agouti-related peptide (AgRP) was genetically inactivated within 4 d after treatment with a synthetic aminoglycoside. Disruption of GABA synthesis in AgRP neurons in young adult mice led to a dramatic loss of body weight due to reduced food intake and elevated energy expenditure; they also manifested glucose intolerance. In contrast, older mice with genetic inactivation of GABA signaling by AgRP neurons had only transient reduction of feeding and body weight; their energy expenditure and glucose tolerance were unaffected. These results indicate that GABAergic signaling from AgRP neurons plays a key role in the control of feeding and metabolism through an age-dependent mechanism. This new genetic technique will augment current tools used to elucidate mechanisms underlying many physiological and neurological processes. PMID:26976589

  15. Increased GABA(A) inhibition of the RVLM after hindlimb unloading in rats

    NASA Technical Reports Server (NTRS)

    Moffitt, Julia A.; Heesch, Cheryl M.; Hasser, Eileen M.

    2002-01-01

    Attenuated baroreflex-mediated increases in renal sympathetic nerve activity (RSNA) in hindlimb unloaded (HU) rats apparently are due to changes within the central nervous system. We hypothesized that GABA(A) receptor-mediated inhibition of the rostral ventrolateral medulla (RVLM) is increased after hindlimb unloading. Responses to bilateral microinjection of the GABA(A) antagonist (-)-bicuculline methiodide (BIC) into the RVLM were examined before and during caudal ventrolateral medulla (CVLM) inhibition in Inactin-anesthetized control and HU rats. Increases in mean arterial pressure (MAP), heart rate (HR), and RSNA in response to BIC in the RVLM were significantly enhanced in HU rats. Responses to bilateral CVLM blockade were not different. When remaining GABA(A) inhibition in the RVLM was blocked by BIC during CVLM inhibition, the additional increases in MAP and RSNA were significantly greater in HU rats. These data indicate that GABA(A) receptor-mediated inhibition of RVLM neurons is augmented after hindlimb unloading. Effects of input from the CVLM were unaltered. Thus, after cardiovascular deconditioning in rodents, the attenuated increase in sympathetic nerve activity in response to hypotension is associated with greater GABA(A) receptor-mediated inhibition of RVLM neurons originating at least in part from sources other than the CVLM.

  16. Prefrontal Cortical GABA Modulation of Spatial Reference and Working Memory

    PubMed Central

    Auger, Meagan L.

    2015-01-01

    Background: Dysfunction in prefrontal cortex (PFC) GABA transmission has been proposed to contribute to cognitive dysfunction in schizophrenia, yet how this system regulates different cognitive and mnemonic functions remains unclear. Methods: We assessed the effects of pharmacological reduction of GABAA signaling in the medial PFC of rats on spatial reference/working memory using different versions of the radial-arm maze task. We used a massed-trials procedure to probe how PFC GABA regulates susceptibility to proactive interference. Male rats were well-trained to retrieve food from the same 4 arms of an 8-arm maze, receiving 5 trials/day (1–2min intervals). Results: Infusions of the GABAA receptor antagonist bicuculline (12.5–50ng) markedly increased working and reference memory errors and response latencies. Similar treatments also impaired short-term memory on an 8-baited arm task. These effects did not appear to be due to increased susceptibility to proactive interference. In contrast, PFC inactivation via infusion of GABA agonists baclofen/muscimol did not affect reference/working memory. In comparison to the pronounced effects on the 8-arm maze tasks, PFC GABAA antagonism only causes a slight and transient decrease in accuracy on a 2-arm spatial discrimination. Conclusions: These findings demonstrate that prefrontal GABA hypofunction severely disrupts spatial reference and short-term memory and that disinhibition of the PFC can, in some instances, perturb memory processes not normally dependent on the frontal lobes. Moreover, these impairments closely resemble those observed in schizophrenic patients, suggesting that perturbation in PFC GABA signaling may contribute to these types of cognitive deficits associated with the disorder. PMID:25552433

  17. Prefrontal cortical GABA modulation of spatial reference and working memory.

    PubMed

    Auger, Meagan L; Floresco, Stan B

    2014-10-31

    Dysfunction in prefrontal cortex (PFC) GABA transmission has been proposed to contribute to cognitive dysfunction in schizophrenia, yet how this system regulates different cognitive and mnemonic functions remains unclear. We assessed the effects of pharmacological reduction of GABAA signaling in the medial PFC of rats on spatial reference/working memory using different versions of the radial-arm maze task. We used a massed-trials procedure to probe how PFC GABA regulates susceptibility to proactive interference. Male rats were well-trained to retrieve food from the same 4 arms of an 8-arm maze, receiving 5 trials/day (1-2 min intervals). Infusions of the GABAA receptor antagonist bicuculline (12.5-50 ng) markedly increased working and reference memory errors and response latencies. Similar treatments also impaired short-term memory on an 8-baited arm task. These effects did not appear to be due to increased susceptibility to proactive interference. In contrast, PFC inactivation via infusion of GABA agonists baclofen/muscimol did not affect reference/working memory. In comparison to the pronounced effects on the 8-arm maze tasks, PFC GABAA antagonism only causes a slight and transient decrease in accuracy on a 2-arm spatial discrimination. These findings demonstrate that prefrontal GABA hypofunction severely disrupts spatial reference and short-term memory and that disinhibition of the PFC can, in some instances, perturb memory processes not normally dependent on the frontal lobes. Moreover, these impairments closely resemble those observed in schizophrenic patients, suggesting that perturbation in PFC GABA signaling may contribute to these types of cognitive deficits associated with the disorder. © The Author 2014. Published by Oxford University Press on behalf of CINP.

  18. Characterization of GABA/sub A/ receptor-mediated /sup 36/chloride uptake in rat brain synaptoneurosomes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Luu, M.D.; Morrow, A.L.; Paul, S.M.

    1987-09-07

    ..gamma..-Aminobutyric acid (GABA) receptor-mediated /sup 36/chloride (/sup 36/Cl/sup -/) uptake was measured in synaptoneurosomes from rat brain. GABA and GABA agonists stimulated /sup 36/Cl/sup -/ uptake in a concentration-dependent manner with the following order of potency: Muscimol>GABA>piperidine-4-sulfonic acid (P4S)>4,5,6,7-tetrahydroisoxazolo-(5,4-c)pyridin-3-ol (THIP)=3-aminopropanesulfonic acid (3APS)>>taurine. Both P4S and 3APS behaved as partial agonists, while the GABA/sub B/ agonist, baclofen, was ineffective. The response to muscimol was inhibited by bicuculline and picrotoxin in a mixed competitive/non-competitive manner. Other inhibitors of GABA receptor-opened channels or non-neuronal anion channels such as penicillin, picrate, furosemide and disulfonic acid stilbenes also inhibited the response to muscimol. A regionalmore » variation in muscimol-stimulated /sup 36/Cl/sup -/ uptake was observed; the largest responses were observed in the cerebral cortex, cerebellum and hippocampus, moderate responses were obtained in the striatum and hypothalamus and the smallest response was observed in the pons-medulla. GABA receptor-mediated /sup 36/Cl/sup -/ uptake was also dependent on the anion present in the media. The muscinol response varied in media containing the following anions: Br/sup -/>Cl/sup -/greater than or equal toNO/sub 3//sup -/>I/sup -/greater than or equal toSCN/sup -/>>C/sub 3/H/sub 5/OO/sup -/greater than or equal toClO/sub 4//sup -/>F/sup -/, consistent with the relative anion permeability through GABA receptor-gated anion channels and the enhancement of convulsant binding to the GABA receptor-gated Cl/sup -/ channel. 43 references, 4 figures, 3 tables.« less

  19. Heterogeneous transgene expression in the retinas of the TH-RFP, TH-Cre, TH-BAC-Cre and DAT-Cre mouse lines

    PubMed Central

    Vuong, Helen E.; de Sevilla Müller, Luis Pérez; Hardi, Claudia N.; McMahon, Douglas G.; Brecha, Nicholas C.

    2015-01-01

    Transgenic mouse lines are essential tools for understanding the connectivity, physiology and function of neuronal circuits, including those in the retina. This report compares transgene expression in the retina of a tyrosine hydroxylase (TH)-red fluorescent protein (RFP) line with three catecholamine-related Cre recombinase lines [TH-bacterial artificial chromosome (BAC)-, TH-, and dopamine transporter (DAT)-Cre] that were crossed with a ROSA26-tdTomato reporter line. Retinas were evaluated and immunostained with commonly used antibodies including those directed to TH, GABA and glycine to characterize the RFP or tdTomato fluorescent-labeled amacrine cells, and an antibody directed to RNA-binding protein with multiple splicing to identify ganglion cells. In TH-RFP retinas, types 1 and 2 dopamine (DA) amacrine cells were identified by their characteristic cellular morphology and type 1 DA cells by their expression of TH immunoreactivity. In the TH-BAC-, TH-, and DAT-tdTomato retinas, less than 1%, ~6%, and 0%, respectively, of the fluorescent cells were the expected type 1 DA amacrine cells. Instead, in the TH-BAC-tdTomato retinas, fluorescently labeled AII amacrine cells were predominant, with some medium somal diameter ganglion cells. In TH-tdTomato retinas, fluorescence was in multiple neurochemical amacrine cell types, including four types of polyaxonal amacrine cells. In DAT-tdTomato retinas, fluorescence was in GABA immunoreactive amacrine cells, including two types of bistratified and two types of monostratified amacrine cells. Although each of the Cre lines were generated with the intent to specifically label DA cells, our findings show a cellular diversity in Cre expression in the adult retina and indicate the importance of careful characterization of transgene labeling patterns. These mouse lines with their distinctive cellular labeling patterns will be useful tools for future studies of retinal function and visual processing. PMID:26335381

  20. Heterogeneous transgene expression in the retinas of the TH-RFP, TH-Cre, TH-BAC-Cre and DAT-Cre mouse lines.

    PubMed

    Vuong, H E; Pérez de Sevilla Müller, L; Hardi, C N; McMahon, D G; Brecha, N C

    2015-10-29

    Transgenic mouse lines are essential tools for understanding the connectivity, physiology and function of neuronal circuits, including those in the retina. This report compares transgene expression in the retina of a tyrosine hydroxylase (TH)-red fluorescent protein (RFP) mouse line with three catecholamine-related Cre recombinase mouse lines [TH-bacterial artificial chromosome (BAC)-, TH-, and dopamine transporter (DAT)-Cre] that were crossed with a ROSA26-tdTomato reporter line. Retinas were evaluated and immunostained with commonly used antibodies including those directed to TH, GABA and glycine to characterize the RFP or tdTomato fluorescent-labeled amacrine cells, and an antibody directed to RNA-binding protein with multiple splicing to identify ganglion cells. In TH-RFP retinas, types 1 and 2 dopamine (DA) amacrine cells were identified by their characteristic cellular morphology and type 1 DA cells by their expression of TH immunoreactivity. In the TH-BAC-, TH-, and DAT-tdTomato retinas, less than 1%, ∼ 6%, and 0%, respectively, of the fluorescent cells were the expected type 1 DA amacrine cells. Instead, in the TH-BAC-tdTomato retinas, fluorescently labeled AII amacrine cells were predominant, with some medium diameter ganglion cells. In TH-tdTomato retinas, fluorescence was in multiple neurochemical amacrine cell types, including four types of polyaxonal amacrine cells. In DAT-tdTomato retinas, fluorescence was in GABA immunoreactive amacrine cells, including two types of bistratified and two types of monostratified amacrine cells. Although each of the Cre lines was generated with the intent to specifically label DA cells, our findings show a cellular diversity in Cre expression in the adult retina and indicate the importance of careful characterization of transgene labeling patterns. These mouse lines with their distinctive cellular labeling patterns will be useful tools for future studies of retinal function and visual processing. Published by Elsevier

  1. Glutamate and GABA in lateral hypothalamic mechanisms controlling food intake.

    PubMed

    Stanley, B G; Urstadt, K R; Charles, J R; Kee, T

    2011-07-25

    By the 1990s a convergence of evidence had accumulated to suggest that neurons within the lateral hypothalamus (LH) play important roles in the stimulation of feeding behavior. However, there was little direct evidence demonstrating that neurotransmitters in the LH could, like electrical stimulation, elicit feeding in satiated animals. The present paper is a brief review in honor of Bartley Hoebel's scientific contributions, emphasizing the evidence from my lab that the excitatory neurotransmitter glutamate and the inhibitory neurotransmitter gamma aminobutyric acid (GABA) in the LH mediate feeding stimulation and feeding inhibition respectively. Specifically, we summarize evidence that LH injection of glutamate, or agonists of its N-methyl-D-aspartate (NMDA) and non-NMDA receptors, elicits feeding in satiated rats, that NMDA receptor antagonists block the eating elicited by NMDA and, more importantly, that NMDA blockade suppresses natural feeding and can reduce body weight. Conversely, GABA(A) agonists injected into the LH suppress feeding and can also reduce body weight, while GABA(A) receptor antagonists actually elicit eating when injected into the LH of satiated rats. It is suggested that natural feeding may reflect the moment-to-moment balance in the activity of glutamate and GABA within the LH. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Early life stress is a risk factor for excessive alcohol drinking and impulsivity in adults and is mediated via a CRF/GABA(A) mechanism.

    PubMed

    Gondré-Lewis, Marjorie C; Warnock, Kaitlin T; Wang, Hong; June, Harry L; Bell, Kimberly A; Rabe, Holger; Tiruveedhula, Veera Venkata Naga Phani Babu; Cook, James; Lüddens, Hartmut; Aurelian, Laure; June, Harry L

    2016-01-01

    Childhood stress and trauma are associated with substance use disorders in adulthood, but the neurological changes that confer increased vulnerability are largely unknown. In this study, maternal separation (MS) stress, restricted to the pre-weaning period, was used as a model to study mechanisms of protracted effects of childhood stress/traumatic experiences on binge drinking and impulsivity. Using an operant self-administration model of binge drinking and a delay discounting assay to measure impulsive-like behavior, we report that early life stress due to MS facilitated acquisition of binge drinking and impulsivity during adulthood in rats. Previous studies have shown heightened levels of corticotropin releasing factor (CRF) after MS, and here, we add that MS increased expression levels of GABA(A) α2 subunit in central stress circuits. To investigate the precise role of these circuits in regulating impulsivity and binge drinking, the CRF1 receptor antagonist antalarmin and the novel GABA(A) α2 subunit ligand 3-PBC were infused into the central amygdala (CeA) and medial prefrontal cortex (mPFC). Antalarmin and 3-PBC at each site markedly reduced impulsivity and produced profound reductions on binge-motivated alcohol drinking, without altering responding for sucrose. Furthermore, whole-cell patch-clamp studies showed that low concentrations of 3-PBC directly reversed the effect of relatively high concentrations of ethanol on α2β3γ2 GABA(A) receptors, by a benzodiazepine site-independent mechanism. Together, our data provide strong evidence that maternal separation, i.e. early life stress, is a risk factor for binge drinking, and is linked to impulsivity, another key risk factor for excessive alcohol drinking. We further show that pharmacological manipulation of CRF and GABA receptor signaling is effective to reverse binge drinking and impulsive-like behavior in MS rats. These results provide novel insights into the role of the brain stress systems in the

  3. Determination and comparison of γ-aminobutyric acid (GABA) content in pu-erh and other types of Chinese tea.

    PubMed

    Zhao, Ming; Ma, Yan; Wei, Zhen-zhen; Yuan, Wen-xia; Li, Ya-li; Zhang, Chun-hua; Xue, Xiao-ting; Zhou, Hong-jie

    2011-04-27

    Two previous studies have reported that pu-erh tea contains a high level of γ-aminobutyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system and has several physiological functions. However, two other researchers have demonstrated that the GABA content of several pu-erh teas was low. Due to the high value and health benefits of GABA, analysis of mass-produced pu-erh tea is necessary to determine whether it is actually enriched with GABA. A high-performance liquid chromatography (HPLC) method was developed for the determination of GABA in tea, the results of which were verified by amino acid analysis using an Amino Acid Analyzer (AAA). A total of 114 samples of various types of Chinese tea, including 62 pu-erh teas, 13 green teas, 8 oolong teas, 8 black teas, 3 white teas, 4 GABA teas, and 16 process samples from two industrial fermentations of pu-erh tea (including the raw material and the first to seventh turnings), were analyzed using HPLC. Statistical analysis demonstrated that the GABA content in pu-erh tea was significantly lower than that in other types of tea (p < 0.05) and that the GABA content decreased during industrial fermentation of pu-erh tea (p < 0.05). This mass analysis and comparison suggested GABA was not a major bioactive constituent and resolved the disagreement GABA content in pu-erh tea. In addition, the GABA content in white tea was found to be significantly higher than that in the other types of tea (p < 0.05), leading to the possibility of producing GABA-enriched white tea.

  4. Altered Cortical GABA in Female Veterans with Suicidal Behavior: Sex Differences and Clinical Correlates.

    PubMed

    Prescot, Andrew; Sheth, Chandni; Legarreta, Margaret; Renshaw, Perry F; McGlade, Erin; Yurgelun-Todd, Deborah

    2018-01-01

    Suicide is a public health concern in the civilian and veteran populations. Stressful life events are precipitating factors for suicide. The neurochemical underpinnings of the association between stress/trauma and suicide risk are unclear, especially in regards to sex differences. We hypothesized that gamma-amino butyric acid (GABA), the major inhibitory neurotransmitter may be a neurochemical candidate that is critical in the association between stress and suicide risk in veterans. Proton magnetic resonance spectroscopy ( 1 H MRS) at 3.0 Tesla was used to measure in vivo neurochemistry in the anterior cingulate cortex (ACC; predominantly the dorsal ACC) of 81 veterans (16 females), including 57 (11 females) who endorsed past suicidal ideation (SI) and/or suicide attempt (SA) and 24 (5 females) with no history of SI and/or SA. Suicidal behavior (SB) was defined as the presence of SI and/or SA. We observed no significant differences in GABA/ Creatine+phosphocreatine (Cr+PCr) between veterans with SB (SB+) and without SB (SB-). However, the female SB+ group showed significantly reduced GABA/Cr+PCr vs. the female SB- group. We observed a trend-level significant negative correlation between GABA/Cr+PCr and the defensive avoidance (DA) subscale on the Trauma Symptom Inventory (TSI) in the SB+ group. In contrast, the SB- group exhibited a positive relationship between the two variables. Furthermore, we found significant negative correlations between GABA/Cr+PCr and Hamilton Rating Scale for Depression (HAM-D) scores as well as between GABA/Cr+PCr and several subscales of the TSI in female veterans. This study suggests that reduced GABA/Cr+ PCr ratio in the ACC, which may be related to altered inhibitory capacity, may underlie suicide risk in female veterans. Further, the negative association between GABA/Cr+PCr and stress symptomatology and depression scores suggests that MRS studies may shed light on intermediate phenotypes of SB.

  5. Field trial of GABA-fortified rice plants and oral administration of milled rice in spontaneously hypertensive rats.

    PubMed

    Kowaka, Emi; Shimajiri, Yasuka; Kawakami, Kouhei; Tongu, Miki; Akama, Kazuhito

    2015-06-01

    Hypertension is one of the most critical risk factors accompanying cardiovascular diseases. γ-Aminobutyric acid (GABA) is a non-protein amino acid that functions as a major neurotransmitter in mammals and also as a blood-pressure lowering agent. We previously produced GABA-fortified rice lines of a popular Japonica rice cultivar 'Koshihikari' by genetic manipulation of GABA shunt-related genes. In the study reported here, we grew these same novel rice lines in a field trial and administered the milled rice orally to rats. The yield parameters of the transgenic rice plants were almost unchanged compared to those of untransformed cv. 'Koshihikari' plants, while the rice grains of the transgenic plants contained a high GABA content (3.5 g GABA/kg brown rice; 0.75-0.85 GABA g/kg milled rice) in a greenhouse trial. Oral administration of a diet containing 2.5% GABA-fortified rice, with a daily intake for 8 weeks, had an approximately 20 mmHg anti-hypertensive effect in spontaneous hypertensive rats but not in normotensive Wistar-Kyoto rats. These results suggest that GABA-fortified rice may be applicable as a staple food to control or prevent hypertension.

  6. The effects of volatile anesthetics on the extracellular accumulation of [(3)H]GABA in rat brain cortical slices.

    PubMed

    Diniz, Paulo H C; Guatimosim, Cristina; Binda, Nancy S; Costa, Flávia L P; Gomez, Marcus V; Gomez, Renato S

    2014-01-01

    GABA is an inhibitory neurotransmitter that appears to be associated with the action of volatile anesthetics. These anesthetics potentiate GABA-induced postsynaptic currents by synaptic GABAA receptors, although recent evidence suggests that these agents also significantly affect extrasynaptic GABA receptors. However, the effect of volatile anesthetics on the extracellular concentration of GABA in the central nervous system has not been fully established. In the present study, rat brain cortical slices loaded with [(3)H]GABA were used to investigate the effect of halothane and sevoflurane on the extracellular accumulation of this neurotransmitter. The accumulation of [(3)H]GABA was significantly increased by sevoflurane (0.058, 0.11, 0.23, 0.46, and 0.93 mM) and halothane (0.006, 0.012, 0.024, 0.048, 0072, and 0.096 mM) with an EC50 of 0.26 mM and 35 μM, respectively. TTX (blocker of voltage-dependent Na(+) channels), EGTA (an extracellular Ca(2+) chelator) and BAPTA-AM (an intracellular Ca(2+) chelator) did not interfere with the accumulation of [(3)H]GABA induced by 0.23 mM sevoflurane and 0.048 mM halothane. SKF 89976A, a GABA transporter type 1 (GAT-1) inhibitor, reduced the sevoflurane- and halothane-induced increase in the accumulation of GABA by 57 and 63 %, respectively. Incubation of brain cortical slices at low temperature (17 °C), a condition that inhibits GAT function and reduces GABA release through reverse transport, reduced the sevoflurane- and halothane-induced increase in the accumulation of [(3)H]GABA by 82 and 75 %, respectively, relative to that at normal temperature (37 °C). Ouabain, a Na(+)/K(+) ATPase pump inhibitor, which is known to induce GABA release through reverse transport, abolished the sevoflurane and halothane effects on the accumulation of [(3)H]GABA. The effect of sevoflurane and halothane did not involve glial transporters because β-alanine, a blocker of GAT-2 and GAT-3, did not inhibit the effect of the anesthetics

  7. Functional neuroanatomy of the ventral striopallidal GABA pathway. New sites of intervention in the treatment of schizophrenia.

    PubMed

    O'Connor, W T

    2001-08-15

    Microdialysis was employed to investigate the dopamine, cholecystokinin (CCK) and neurotensin receptor regulation of ventral striopallidal GABA transmission by intra-accumbens perfusion with selective receptor ligands and monitoring local or ipsilateral ventral pallidal GABA release. In the dual probe studies intra-accumbens perfusion with the dopamine D1 and D2 receptor agonists SKF28293 and pergolide had no effect on ventral pallidal GABA, while both the D1 and D2 receptor antagonists SCH23390 and raclopride increased ventral pallidal GABA release. In contrast, intra-accumbens CCK decreased ventral pallidal GABA release and this was reversed by local perfusion with the CCK2 receptor antagonist PD134308 but not the CCK1 receptor antagonist L-364,718. In a single probe study intra-accumbens neurotensin increased local GABA release, which was strongly potentiated when the peptidase inhibitor phosphodiepryl 08 was perfused together with neurotensin. In addition, the neurotensin receptor antagonist SR48692 counteracted this phosphodiepryl 08 induced potentiated increased in GABA release. Taken together, these findings indicate that mesolimbic dopamine and CCK exert a respective tonic and phasic inhibition of ventral pallidal GABA release while the antipsychotic activity associated with D1 and D2 receptor antagonists may be explained by their ability to increase ventral striopallidal GABA transmission. Furthermore, the findings suggest that CCK2 receptor antagonists and neurotensin endopeptidase inhibitors may be useful antipsychotics.

  8. Different in vitro and in vivo profiles of substituted 3-aminopropylphosphinate and 3-aminopropyl(methyl)phosphinate GABA(B) receptor agonists as inhibitors of transient lower oesophageal sphincter relaxation.

    PubMed

    Lehmann, A; Antonsson, M; Aurell-Holmberg, A; Blackshaw, L A; Brändén, L; Elebring, T; Jensen, J; Kärrberg, L; Mattsson, J P; Nilsson, K; Oja, S S; Saransaari, P; von Unge, S

    2012-03-01

    Gastro-oesophageal reflux is predominantly caused by transient lower oesophageal sphincter relaxation (TLOSR) and GABA(B) receptor stimulation inhibits TLOSR. Lesogaberan produces fewer CNS side effects than baclofen, which has been attributed to its affinity for the GABA transporter (GAT), the action of which limits stimulation of central GABA(B) receptors. To understand the structure-activity relationship for analogues of lesogaberan (3-aminopropylphosphinic acids), and corresponding 3-aminopropyl(methyl)phosphinic acids, we have compared representatives of these classes in different in vitro and in vivo models. The compounds were characterized in terms of GABA(B) agonism in vitro. Binding to GATs and cellular uptake was done using rat brain membranes and slices respectively. TLOSR was measured in dogs, and CNS side effects were evaluated as hypothermia in mice and rats. 3-Aminopropylphosphinic acids inhibited TLOSR with a superior therapeutic index compared to 3-aminopropyl(methyl)phosphinic acids. This difference was most likely due to differential GAT-mediated uptake into brain cells of the former but not latter. In agreement, 3-aminopropyl(methyl)phosphinic acids were much more potent in producing hypothermia in rats even when administered i.c.v. An enhanced therapeutic window for 3-aminopropylphosphinic acids compared with 3-aminopropyl(methyl)phosphinic acids with respect to inhibition of TLOSR was observed and is probably mechanistically linked to neural cell uptake of the former but not latter group of compounds. These findings offer a platform for discovery of new GABA(B) receptor agonists for the treatment of reflux disease and other conditions where selective peripheral GABA(B) receptor agonism may afford therapeutic effects. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

  9. GABA concentration in schizophrenia patients and the effects of antipsychotic medication: a proton magnetic resonance spectroscopy study.

    PubMed

    Tayoshi, Shin'Ya; Nakataki, Masahito; Sumitani, Satsuki; Taniguchi, Kyoko; Shibuya-Tayoshi, Sumiko; Numata, Shusuke; Iga, Jun-ichi; Ueno, Shu-ichi; Harada, Masafumi; Ohmori, Tetsuro

    2010-03-01

    Gamma-amino butyric acid (GABA) is thought to play a role in the pathophysiology of schizophrenia. High magnetic field proton magnetic resonance spectroscopy ((1)H-MRS) provides a reliable measurement of GABA in specific regions of the brain. This study measured GABA concentration in the anterior cingulate cortex (ACC) and in the left basal ganglia (ltBG) in 38 patients with chronic schizophrenia and 29 healthy control subjects. There was no significant difference in GABA concentration between the schizophrenia patients and the healthy controls in either the ACC (1.36+/-0.45 mmol/l in schizophrenia patients and 1.52+/-0.54 mmol/l in control subjects) or the ltBG (1.13+/-0.26 mmol/l in schizophrenia patients and 1.18+/-0.20 mmol/l in control subjects). Among the right handed schizophrenia patients, the GABA concentration in the ltBG was significantly higher in patients taking typical antipsychotics (1.25+/-0.24 mmol/l) than in those taking atypical antipsychotics (1.03+/-0.24 mmol/l, p=0.026). In the ACC, the GABA concentration was negatively correlated with the dose of the antipsychotics (rs=-0.347, p=0.035). In the ltBG, the GABA concentration was positively correlated with the dose of the anticholinergics (rs=0.403, p=0.015). To the best of our knowledge, this is the first study to have directly measured GABA concentrations in schizophrenia patients using (1)H-MRS. Our results suggest that there are no differences in GABA concentrations in the ACC or the ltBG of schizophrenia patients compared to healthy controls. Antipsychotic medication may cause changes in GABA concentration, and atypical and typical antipsychotics may have differing effects. It is possible that medication effects conceal inherent differences in GABA concentrations between schizophrenia patients and healthy controls. (c) 2009 Elsevier B.V. All rights reserved.

  10. Enhancement of gamma-aminobutyric acid (GABA) levels using an autochthonous Lactobacillus futsaii CS3 as starter culture in Thai fermented shrimp (Kung-Som).

    PubMed

    Sanchart, Chatthaphisuth; Rattanaporn, Onnicha; Haltrich, Dietmar; Phukpattaranont, Pimpimol; Maneerat, Suppasil

    2017-08-01

    Gamma-aminobutyric acid (GABA) is a non-proteinogenic amino acid, which has a variety of well-characterized beneficial physiological functions. In order to improve GABA levels and the fermentation process of Thai fermented shrimp (Kung-Som), autochthonous Lactobacillus futsaii CS3 was inoculated as a starter culture into Kung-Som, and its effects on the quality of Kung-Som were studied. The optimal conditions for GABA production in Kung-Som as obtained by response surface methodology (RSM) using a central composite design (CCD) were an inoculum size of roughly 10 7 CFU/g (X 1 ) of L. futsaii cells together with the addition of 0.5% (w/w) monosodium glutamate (MSG) (X 2 ), resulting in maximum GABA levels of 10,500 mg per kg fresh product. Under these optimized conditions, the experimental GABA content of Kung-Som with an added starter culture was up to four times higher than that of the control (without starter culture) or commercial Kung-Som products (10,120 mg/kg product). Kung-Som produced by inoculation with L. futsaii CS3 but without addition of MSG showed a considerably increased GABA content of 7790 mg/kg compared to the control. Fermentation time was reduced to less than 1 week for these samples compared to the control batches, which took up to 19 days. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) revealed that L. futsaii CS3 remained prominently throughout the Kung-Som fermentation, and that lactic acid bacteria (LAB) rapidly dominated the total microflora because of this inoculation with L. futsaii CS3. Kung-Som samples with starter culture were accepted as well as commercial ones by 30 panelists (p > 0.05). In conclusion, L. futsaii CS3 is a good starter culture for GABA production, resulting in, improved microbiological safety as well as reduced fermentation time.

  11. A high-fat diet decreases GABA concentration in the frontal cortex and hippocampus of rats.

    PubMed

    Sandoval-Salazar, Cuauhtemoc; Ramírez-Emiliano, Joel; Trejo-Bahena, Aurora; Oviedo-Solís, Cecilia I; Solís-Ortiz, Martha Silvia

    2016-02-29

    It has been proposed that the γ-aminobutyric acid (GABA) plays a key role in the regulation of food intake and body weight by controlling the excitability, plasticity and the synchronization of neuronal activity in the frontal cortex (FC). It has been also proposed that the high-fat diet (HFD) could disturb the metabolism of glutamate and consequently the GABA levels, but the mechanism is not yet clearly understood. Therefore, the aim of this study was to investigate the effect of a HFD on the GABA levels in the FC and hippocampus of rats. The HFD significantly increased weight gain and blood glucose levels, whereas decreased the GABA levels in the FC and hippocampus compared with standard diet-fed rats. HFD decreases GABA levels in the FC and hippocampus of rat, which likely disrupts the GABAergic inhibitory processes, underlying feeding behavior.

  12. Gamma-amino butyric acid (GABA) synthesis of Lactobacillus in fermentation of defatted rice bran extract

    NASA Astrophysics Data System (ADS)

    Dat, Lai Quoc; Ngan, Tran Thi Kim; Nu, Nguyen Thi Xuan

    2017-09-01

    This research focused on the synthesis of GABA by Lactobacillus bacteria in fermentation of defatted rice bran extract without adding glutamate. Two strains of Lactobacillus were investigated into capacity of GABA synthesis. Result indicates that, Lactobacillus brevis VTCC - B - 454 exhibited the higher capacity of GABA synthesis in fermentation of defatted rice bran extract than that of Lactobacillus plantarum VTCC - B - 890. Total dissolved solid (TDS), free amino acids (AA) and reducing sugar (RS) contents in fermentation of defatted rice bran extract with two strains also significantly decreased. At pH 5 and 9 %w/w of TDS content in defatted rice bran extract, Lactobacillus brevis VTCC - B - 454 accumulated 2,952 ppm of GABA in 24 hours of fermentation. The result implies that fermentation with Lactobacillus brevis VTCC - B - 454 can be applied for GABA production from defatted rice bran extract.

  13. Meroterpenoid Chrodrimanins Are Selective and Potent Blockers of Insect GABA-Gated Chloride Channels

    PubMed Central

    Ihara, Makoto; Ling, Yun; Yang, Xinling; Kai, Kenji; Hayashi, Hideo; Matsuda, Kazuhiko

    2015-01-01

    Meroterpenoid chrodrimanins, produced from Talaromyces sp. YO-2, are known to paralyze silkworm (Bombyx mori) larvae, but their target is unknown. We have investigated the actions of chrodrimanin B on ligand-gated ion channels of silkworm larval neurons using patch-clamp electrophysiology. Chrodrimanin B had no effect on membrane currents when tested alone at 1 μM. However, it completely blocked the γ-aminobutyric acid (GABA)-induced current and showed less pronounced actions on acetylcholine- and L-glutamate-induced currents, when delivered at 1 μM for 1 min prior to co-application with transmitter GABA. Thus, chrodrimanins were also tested on a wild-type isoform of the B. mori GABA receptor (GABAR) RDL using two-electrode voltage-clamp electrophysiology. Chrodrimanin B attenuated the peak current amplitude of the GABA response of RDL with an IC50 of 1.66 nM. The order of the GABAR-blocking potency of chrodrimanins B > D > A was in accordance with their reported insecticidal potency. Chrodrimanin B had no open channel blocking action when tested at 3 nM on the GABA response of RDL. Co-application with 3 nM chrodrimanin B shifted the GABA concentration response curve to a higher concentration and further increase of chrodrimanin B concentration to10 nM; it reduced maximum current amplitude of the GABA response, pointing to a high-affinity competitive action and a lower affinity non-competitive action. The A282S;T286V double mutation of RDL, which impairs the actions of fipronil, hardly affected the blocking action of chrodrimanin B, indicating a binding site of chrodrimanin B distinct from that of fipronil. Chrodrimanin B showed approximately 1,000-fold lower blocking action on human α1β2γ2 GABAR compared to RDL and thus is a selective blocker of insect GABARs. PMID:25902139

  14. Neuroimaging studies of GABA in schizophrenia: a systematic review with meta-analysis

    PubMed Central

    Egerton, A; Modinos, G; Ferrera, D; McGuire, P

    2017-01-01

    Data from animal models and from postmortem studies suggest that schizophrenia is associated with brain GABAergic dysfunction. The extent to which this is reflected in data from in vivo studies of GABA function in schizophrenia is unclear. The Medline database was searched to identify articles published until 21 October 2016. The search terms included GABA, proton magnetic resonance spectroscopy (1H-MRS), positron emission tomography (PET), single photon emission computed tomography (SPECT), schizophrenia and psychosis. Sixteen GABA 1H-MRS studies (538 controls, 526 patients) and seven PET/SPECT studies of GABAA/benzodiazepine receptor (GABAA/BZR) availability (118 controls, 113 patients) were identified. Meta-analyses of 1H-MRS GABA in the medial prefrontal cortex (mPFC), parietal/occipital cortex (POC) and striatum did not show significant group differences (mFC: g=−0.3, 409 patients, 495 controls, 95% confidence interval (CI): −0.6 to 0.1; POC: g=−0.3, 139 patients, 111 controls, 95% CI: −0.9 to 0.3; striatum: g=−0.004, 123 patients, 95 controls, 95% CI: −0.7 to 0.7). Heterogeneity across studies was high (I2>50%), and this was not explained by subsequent moderator or meta-regression analyses. There were insufficient PET/SPECT receptor availability studies for meta-analyses, but a systematic review did not suggest replicable group differences in regional GABAA/BZR availability. The current literature does not reveal consistent alterations in in vivo GABA neuroimaging measures in schizophrenia, as might be hypothesized from animal models and postmortem data. The analysis highlights the need for further GABA neuroimaging studies with improved methodology and addressing potential sources of heterogeneity. PMID:28585933

  15. Glial Control of Endocannabinoid Heterosynaptic Modulation in Hypothalamic Magnocellular Neuroendocrine Cells

    PubMed Central

    Popescu, Ion R.

    2013-01-01

    Cannabinoid receptors are functionally operant at both glutamate and GABA synapses on hypothalamic magnocellular neuroendocrine cells; however, retrograde endocannabinoid actions are evoked at only glutamate synapses. We tested whether the functional targeting of evoked retrograde endocannabinoid actions to glutamate, and not GABA, synapses on magnocellular neurons is the result of the spatial restriction of extracellular endocannabinoids by astrocytes. Whole-cell GABA synaptic currents were recorded in magnocellular neurons in rat hypothalamic slices following manipulations to reduce glial buffering of extracellular signals. Depolarization- and glucocorticoid-evoked retrograde endocannabinoid suppression of synaptic GABA release was not detected under normal conditions, but occurred in both oxytocin and vasopressin neurons under conditions of attenuated glial coverage and depressed glial metabolic function, suggesting an emergent endocannabinoid modulation of GABA synapses with the loss of astrocyte function. Tonic endocannabinoid suppression of GABA release was insensitive to glial manipulation. Blocking cannabinoid transport mimicked, and increasing the extracellular viscosity reversed, the effect of suppressed glial buffering on the endocannabinoid modulation of GABA release. Evoked, but not tonic, endocannabinoid modulation of GABA synapses was mediated by 2-arachidonoylglycerol. Therefore, depolarization- and glucocorticoid-evoked 2-arachidonoylglycerol release from magnocellular neurons is spatially restricted to glutamate synapses by astrocytes, but spills over onto GABA synapses under conditions of reduced astrocyte buffering; tonic endocannabinoid modulation of GABA release, in contrast, is likely mediated by anandamide and is insensitive to astrocytic buffering. Astrocytes, therefore, provide dynamic control of stimulus-evoked 2-arachidonoylglycerol, but not tonic anandamide, regulation of GABA synaptic inputs to magnocellular neuroendocrine cells under

  16. Relative Neurotoxicity of Ivermectin and Moxidectin in Mdr1ab (−/−) Mice and Effects on Mammalian GABA(A) Channel Activity

    PubMed Central

    Ménez, Cécile; Sutra, Jean-François; Prichard, Roger; Lespine, Anne

    2012-01-01

    The anthelmintics ivermectin (IVM) and moxidectin (MOX) display differences in toxicity in several host species. Entrance into the brain is restricted by the P-glycoprotein (P-gp) efflux transporter, while toxicity is mediated through the brain GABA(A) receptors. This study compared the toxicity of IVM and MOX in vivo and their interaction with GABA(A) receptors in vitro. Drug toxicity was assessed in Mdr1ab(−/−) mice P-gp-deficient after subcutaneous administration of increasing doses (0.11–2.0 and 0.23–12.9 µmol/kg for IVM and MOX in P-gp-deficient mice and half lethal doses (LD50) in wild-type mice). Survival was evaluated over 14-days. In Mdr1ab(−/−) mice, LD50 was 0.46 and 2.3 µmol/kg for IVM and MOX, respectively, demonstrating that MOX was less toxic than IVM. In P-gp-deficient mice, MOX had a lower brain-to-plasma concentration ratio and entered into the brain more slowly than IVM. The brain sublethal drug concentrations determined after administration of doses close to LD50 were, in Mdr1ab(−/−) and wild-type mice, respectively, 270 and 210 pmol/g for IVM and 830 and 740–1380 pmol/g for MOX, indicating that higher brain concentrations are required for MOX toxicity than IVM. In rat α1β2γ2 GABA channels expressed in Xenopus oocytes, IVM and MOX were both allosteric activators of the GABA-induced response. The Hill coefficient was 1.52±0.45 for IVM and 0.34±0.56 for MOX (p<0.001), while the maximum potentiation caused by IVM and MOX relative to GABA alone was 413.7±66.1 and 257.4±40.6%, respectively (p<0.05), showing that IVM causes a greater potentiation of GABA action on this receptor. Differences in the accumulation of IVM and MOX in the brain and in the interaction of IVM and MOX with GABA(A) receptors account for differences in neurotoxicity seen in intact and Mdr1-deficient animals. These differences in neurotoxicity of IVM and MOX are important in considering their use in humans. PMID:23133688

  17. Glutamate-glutamine and GABA in brain of normal aged and patients with cognitive impairment.

    PubMed

    Huang, Dandan; Liu, Dan; Yin, Jianzhong; Qian, Tianyi; Shrestha, Susan; Ni, Hongyan

    2017-07-01

    To explore the changes of glutamate-glutamine (Glx) and gamma-aminobutyric acid (GABA) in the brain in normal old age and cognitive impairment using magnetic resonance spectroscopy (MRS). Seventeen normal young controls (NYC), 15 normal elderly controls (NEC), 21 patients with mild cognitive impairment (MCI) and 17 with Alzheimer disease (AD) patients were included in this study. Glx and GABA+ levels in the anterior cingulate cortex (ACC) and right hippocampus (rHP) were measured by using a MEGA-PRESS sequence. Glx/Cr and GABA+/Cr ratios were compared between NYC and NEC and between the three elderly groups using analysis of covariance (ANCOVA); the tissue fractions of voxels were used as covariates. The relationships between metabolite ratios and cognitive performance were analysed using Spearman correlation coefficients. For NEC and NYC groups, Glx/Cr and GABA+/Cr ratios were lower in NEC in ACC and rHP. For the three elderly groups, Glx/Cr ratio was lower in AD in ACC compared to NEC and MCI; Glx/Cr ratio was lower in AD in rHP compared to NEC. There was no significant decrease for GABA+/Cr ratio. Glx and GABA levels may decrease simultaneously in normal aged, and Glx level decreased predominantly in AD, and it is helpful in the early diagnosis of AD. • Glx and GABA levels may decrease simultaneously in normal aged. • Glx level may decrease predominantly in Alzheimer disease. • The balance in excitatory-inhibitory systems may be broken in AD. • Decreased Glx level may be helpful in early diagnosis of AD.

  18. Comparative mapping of GABA-immunoreactive neurons in the central nervous systems of nudibranch molluscs.

    PubMed

    Gunaratne, Charuni A; Sakurai, Akira; Katz, Paul S

    2014-03-01

    The relative simplicity of certain invertebrate nervous systems, such as those of gastropod molluscs, allows behaviors to be dissected at the level of small neural circuits composed of individually identifiable neurons. Elucidating the neurotransmitter phenotype of neurons in neural circuits is important for understanding how those neural circuits function. In this study, we examined the distribution of γ-aminobutyric-acid;-immunoreactive (GABA-ir) neurons in four species of sea slugs (Mollusca, Gastropoda, Opisthobranchia, Nudibranchia): Tritonia diomedea, Melibe leonina, Dendronotus iris, and Hermissenda crassicornis. We found consistent patterns of GABA immunoreactivity in the pedal and cerebral-pleural ganglia across species. In particular, there were bilateral clusters in the lateral and medial regions of the dorsal surface of the cerebral ganglia as well as a cluster on the ventral surface of the pedal ganglia. There were also individual GABA-ir neurons that were recognizable across species. The invariant presence of these individual neurons and clusters suggests that they are homologous, although there were interspecies differences in the numbers of neurons in the clusters. The GABAergic system was largely restricted to the central nervous system, with the majority of axons confined to ganglionic connectives and commissures, suggesting a central, integrative role for GABA. GABA was a candidate inhibitory neurotransmitter for neurons in central pattern generator (CPG) circuits underlying swimming behaviors in these species, however none of the known swim CPG neurons were GABA-ir. Although the functions of these GABA-ir neurons are not known, it is clear that their presence has been strongly conserved across nudibranchs. Copyright © 2013 Wiley Periodicals, Inc.

  19. GABAergic excitation after febrile seizures induces ectopic granule cells and adult epilepsy.

    PubMed

    Koyama, Ryuta; Tao, Kentaro; Sasaki, Takuya; Ichikawa, Junya; Miyamoto, Daisuke; Muramatsu, Rieko; Matsuki, Norio; Ikegaya, Yuji

    2012-08-01

    Temporal lobe epilepsy (TLE) is accompanied by an abnormal location of granule cells in the dentate gyrus. Using a rat model of complex febrile seizures, which are thought to be a precipitating insult of TLE later in life, we report that aberrant migration of neonatal-generated granule cells results in granule cell ectopia that persists into adulthood. Febrile seizures induced an upregulation of GABA(A) receptors (GABA(A)-Rs) in neonatally generated granule cells, and hyperactivation of excitatory GABA(A)-Rs caused a reversal in the direction of granule cell migration. This abnormal migration was prevented by RNAi-mediated knockdown of the Na(+)K(+)2Cl(-) co-transporter (NKCC1), which regulates the excitatory action of GABA. NKCC1 inhibition with bumetanide after febrile seizures rescued the granule cell ectopia, susceptibility to limbic seizures and development of epilepsy. Thus, this work identifies a previously unknown pathogenic role of excitatory GABA(A)-R signaling and highlights NKCC1 as a potential therapeutic target for preventing granule cell ectopia and the development of epilepsy after febrile seizures.

  20. Intranigral transplants of a GABAergic cell line produce long-term alleviation of established motor seizures.

    PubMed

    Castillo, Claudia G; Mendoza-Trejo, Soledad; Aguilar, Manuel B; Freed, William J; Giordano, Magda

    2008-11-03

    We have previously shown that intranigral transplants of immortalized GABAergic cells decrease the number of kainic acid-induced seizures [Castillo CG, Mendoza S, Freed WJ, Giordano M. Intranigral transplants of immortalized GABAergic cells decrease the expression of kainic acid-induced seizures in the rat. Behav Brain Res 2006;171:109-15] in an animal model. In the present study, recurrent spontaneous behavioral seizures were established by repeated systemic injections of this excitotoxin into male Sprague-Dawley rats. After the seizures had been established, cells were transplanted into the substantia nigra. Animals with transplants of control cells (without hGAD67 expression) or with sham transplants showed a death rate of more than 40% over the 12 weeks of observation, whereas in animals with M213-2O CL-4 transplants, the death rate was reduced to less than 20%. The M213-2O CL-4 transplants significantly reduced the percentage of animals showing behavioral seizures; animals with these transplants also showed a lower occurrence of stage V seizures than animals in the other groups. In vivo and in vitro analyses provided evidence that the GABAergic cells show sustained expression of both GAD67 and hGAD67 cDNA, as well as increased gamma-aminobutyric acid (GABA) levels in the ventral mesencephalon of transplanted animals. Therefore, transplantation of GABA-producing cells can produce long-term alleviation of behavioral seizures in an animal model.

  1. Characterization of GABAergic marker expression in the chronic unpredictable stress model of depression

    PubMed Central

    Banasr, Mounira; Lepack, Ashley; Fee, Corey; Duric, Vanja; Maldonado-Aviles, Jaime; DiLeone, Ralph; Sibille, Etienne; Duman, Ronald S.; Sanacora, Gerard

    2017-01-01

    Evidence continues to build suggesting that the GABAergic neurotransmitter system is altered in brains of patients with major depressive disorder. However, there is little information available related to the extent of these changes or the potential mechanisms associated with these alterations. As stress is a well-established precipitant to depressive episodes, we sought to explore the impact of chronic stress on GABAergic interneurons. Using western blot analyses and quantitative real-time PCR (qPCR) we assessed the effects of five-weeks of chronic unpredictable stress (CUS) exposure on the expression of GABA-synthesizing enzymes (GAD65 and GAD67), calcium-binding proteins (calbindin (CB), parvalbumin (PV) and calretinin (CR)), and neuropeptides co-expressed in GABAergic neurons (somatostatin (SST), neuropeptide Y (NPY), vasoactive intestinal peptide (VIP) and cholecystokinin (CCK)) in the prefrontal cortex (PFC) and hippocampus (HPC) of rats. We also investigated the effects of corticosterone (CORT) and dexamethasone (DEX) exposure on these markers in vitro in primary cortical and hippocampal cultures. We found that CUS induced significant reductions of GAD67 protein levels in both the PFC and HPC of CUS-exposed rats, but did not detect changes in GAD65 protein expression. Similar protein expression changes were found in vitro in cortical neurons. In addition, our results provide clear evidence of reduced markers of interneuron population(s), namely SST and NPY, in the PFC, suggesting these cell types may be selectively vulnerable to chronic stress. Together, this work highlights that chronic stress induces regional and cell type-selective effects on GABAergic interneurons in rats. These findings provide additional supporting evidence that stress-induced GABA neuron dysfunction and cell vulnerability play critical roles in the pathophysiology of stress-related illnesses, including major depressive disorder. PMID:28835932

  2. Analgesia and hyperalgesia from GABA-mediated modulation of the cerebral cortex.

    PubMed

    Jasmin, Luc; Rabkin, Samuel D; Granato, Alberto; Boudah, Abdennacer; Ohara, Peter T

    2003-07-17

    It is known that pain perception can be altered by mood, attention and cognition, or by direct stimulation of the cerebral cortex, but we know little of the neural mechanisms underlying the cortical modulation of pain. One of the few cortical areas consistently activated by painful stimuli is the rostral agranular insular cortex (RAIC) where, as in other parts of the cortex, the neurotransmitter gamma-aminobutyric acid (GABA) robustly inhibits neuronal activity. Here we show that changes in GABA neurotransmission in the RAIC can raise or lower the pain threshold--producing analgesia or hyperalgesia, respectively--in freely moving rats. Locally increasing GABA, by using an enzyme inhibitor or gene transfer mediated by a viral vector, produces lasting analgesia by enhancing the descending inhibition of spinal nociceptive neurons. Selectively activating GABA(B)-receptor-bearing RAIC neurons produces hyperalgesia through projections to the amygdala, an area involved in pain and fear. Whereas most studies focus on the role of the cerebral cortex as the end point of nociceptive processing, we suggest that cerebral cortex activity can change the set-point of pain threshold in a top-down manner.

  3. Behavioral deficit and decreased GABA receptor functional regulation in the hippocampus of epileptic rats: effect of Bacopa monnieri.

    PubMed

    Mathew, Jobin; Gangadharan, Gireesh; Kuruvilla, Korah P; Paulose, C S

    2011-01-01

    In the present study, alterations of the General GABA and GABA(A) receptors in the hippocampus of pilocarpine-induced temporal lobe epileptic rats and the therapeutic application of Bacopa monnieri and its active component Bacoside-A were investigated. Bacopa monnieri (Linn.) is a herbaceous plant belonging to the family Scrophulariaceae. Hippocampus is the major region of the brain belonging to the limbic system and plays an important role in epileptogenesis, memory and learning. Scatchard analysis of [³H]GABA and [³H]bicuculline in the hippocampus of the epileptic rat showed significant decrease in B(max) (P < 0.001) compared to control. Real Time PCR amplification of GABA(A) receptor sub-units such as GABA(Aά₁), GABA(Aά₅) GABA(Aδ), and GAD were down regulated (P < 0.001) in the hippocampus of the epileptic rats compared to control. GABA(Aγ) subunit was up regulated. Epileptic rats have deficit in the radial arm and Y maze performance. Bacopa monnieri and Bacoside-A treatment reverses all these changes near to control. Our results suggest that decreased GABA receptors in the hippocampus have an important role in epilepsy associated behavioral deficit, Bacopa monnieri and Bacoside-A have clinical significance in the management of epilepsy.

  4. Src family kinases mediate the inhibition of substance P release in the rat spinal cord by μ-opioid receptors and GABA(B) receptors, but not α2 adrenergic receptors.

    PubMed

    Zhang, Guohua; Chen, Wenling; Marvizón, Juan Carlos G

    2010-09-01

    GABA(B) , μ-opioid and adrenergic α(2) receptors inhibit substance P release from primary afferent terminals in the dorsal horn. Studies in cell expression systems suggest that μ-opioid and GABA(B) receptors inhibit transmitter release from primary afferents by activating Src family kinases (SFKs), which then phosphorylate and inhibit voltage-gated calcium channels. This study investigated whether SFKs mediate the inhibition of substance P release by these three receptors. Substance P release was measured as neurokinin 1 receptor (NK1R) internalization in spinal cord slices and in vivo. In slices, NK1R internalization induced by high-frequency dorsal root stimulation was inhibited by the μ-opioid agonist DAMGO and the GABA(B) agonist baclofen. This inhibition was reversed by the SFK inhibitor PP1. NK1R internalization induced by low-frequency stimulation was also inhibited by DAMGO, but PP1 did not reverse this effect. In vivo, NK1R internalization induced by noxious mechanical stimulation of the hind paw was inhibited by intrathecal DAMGO and baclofen. This inhibition was reversed by intrathecal PP1, but not by the inactive PP1 analog PP3. PP1 produced no effect by itself. The α(2) adrenergic agonists medetomidine and guanfacine produced a small but statistically significant inhibition of NK1R internalization induced by low-frequency dorsal root stimulation. PP1 did not reverse the inhibition by guanfacine. These results show that SFKs mediate the inhibition of substance P release by μ-opioid and GABA(B) receptors, but not by α(2) receptors, which is probably mediated by the binding of G protein βγ subunits to calcium channels. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd. No claim to original US government works.

  5. Elevated prefrontal cortex GABA in patients with major depressive disorder after TMS treatment measured with proton magnetic resonance spectroscopy.

    PubMed

    Dubin, Marc J; Mao, Xiangling; Banerjee, Samprit; Goodman, Zachary; Lapidus, Kyle A B; Kang, Guoxin; Liston, Conor; Shungu, Dikoma C

    2016-04-01

    GABAergic and glutamatergic neurotransmitter systems are central to the pathophysiology of depression and are potential targets of repetitive transcranial magnetic stimulation (rTMS). We assessed the effect of 10-Hz rTMS over the left dorsolateral prefrontal cortex (DLPFC) of patients with major depressive disorder on the levels of medial prefrontal cortex (MPFC) γ-aminobutyric acid (GABA) and the combined resonance of glutamate and glutamine (Glx) as assessed in vivo with proton magnetic resonance spectroscopy ((1)H MRS). Currently depressed individuals between the ages of 23 and 68 years participated in a 5-week naturalistic, open-label treatment study of rTMS, with (1)H MRS measurements of MPFC GABA and Glx levels at baseline and following 5 weeks of the rTMS intervention. We applied rTMS pulses over the left DLPFC at 10 Hz and 80%-120% of motor threshold for 25 daily sessions, with each session consisting of 3000 pulses. We assessed therapeutic response using the 24-item Hamilton Rating Scale for Depression (HAMD24). The GABA and Glx levels are expressed as ratios of peak areas relative to the area of the synchronously acquired and similarly fitted unsuppressed voxel water signal (W). Twenty-three currently depressed individuals (7 men) participated in the study. GABA/W in the MPFC increased 13.8% (p = 0.013) in all depressed individuals. There were no significant effects of rTMS on Glx/W. GABA/W and Glx/W were highly correlated in severely depressed patients at baseline but not after TMS. The primary study limitations are the open-label design and the inclusion of participants currently taking stable regimens of antidepressant medications. These results implicate GABAergic and glutamatergic systems in the mechanism of action of rTMS for major depression, warranting further investigation in larger samples.

  6. Investigation of brain GABA+ in primary hypothyroidism using edited proton MR spectroscopy

    PubMed Central

    Liu, Bo; Yang, Huan; Gao, Fei; Wang, Qing; Zhao, Bin; Gong, Tao; Wang, Zhensong; Chen, Weibo; Wang, Guangbin; Edden, Richard A.E.

    2017-01-01

    Summary Objective Evidence indicates that thyroid hormones have effects on the inhibitory GABAergic system. The aim of this study was to investigate whether brain GABA levels are altered in patients with hypothyroidism compared with healthy controls. Design/Methods Fifteen patients with primary hypothyroidism and 15 matched healthy controls underwent single-voxel MEGA-PRESS magnetic resonance spectroscopy at 3T, to quantify GABA levels in the median prefrontal cortex (mPFC) and posterior cingulate cortex (PCC). All participants underwent thyroid function test. Neuropsychological performances were evaluated by administration of the Montreal Cognitive Assessment (MoCA) and the 21-item Beck Depression Inventory-II (BDI-II). Results The patients with hypothyroidism had significantly lower GABA+ levels in the mPFC compared with healthy controls (P = 0·016), whereas no significant difference (P = 0·214) was observed in the PCC. Exploratory analyses revealed that mPFC GABA+ levels were negatively correlated with the BDI-II scores in patient group (r = −0·60, P = 0·018). No correlations were found between GABA+ levels and TSH or fT3 or fT4 levels in either region (all P > 0·05). Conclusion This study suggests that alteration of GABAergic neurotransmission may play an important role in the pathophysiology of primary hypothyroidism, providing intriguing neurochemical clues to understand thyroid–brain interactions. PMID:27581339

  7. Unique pH dynamics in GABAergic synaptic vesicles illuminates the mechanism and kinetics of GABA loading.

    PubMed

    Egashira, Yoshihiro; Takase, Miki; Watanabe, Shoji; Ishida, Junji; Fukamizu, Akiyoshi; Kaneko, Ryosuke; Yanagawa, Yuchio; Takamori, Shigeo

    2016-09-20

    GABA acts as the major inhibitory neurotransmitter in the mammalian brain, shaping neuronal and circuit activity. For sustained synaptic transmission, synaptic vesicles (SVs) are required to be recycled and refilled with neurotransmitters using an H(+) electrochemical gradient. However, neither the mechanism underlying vesicular GABA uptake nor the kinetics of GABA loading in living neurons have been fully elucidated. To characterize the process of GABA uptake into SVs in functional synapses, we monitored luminal pH of GABAergic SVs separately from that of excitatory glutamatergic SVs in cultured hippocampal neurons. By using a pH sensor optimal for the SV lumen, we found that GABAergic SVs exhibited an unexpectedly higher resting pH (∼6.4) than glutamatergic SVs (pH ∼5.8). Moreover, unlike glutamatergic SVs, GABAergic SVs displayed unique pH dynamics after endocytosis that involved initial overacidification and subsequent alkalization that restored their resting pH. GABAergic SVs that lacked the vesicular GABA transporter (VGAT) did not show the pH overshoot and acidified further to ∼6.0. Comparison of luminal pH dynamics in the presence or absence of VGAT showed that VGAT operates as a GABA/H(+) exchanger, which is continuously required to offset GABA leakage. Furthermore, the kinetics of GABA transport was slower (τ > 20 s at physiological temperature) than that of glutamate uptake and may exceed the time required for reuse of exocytosed SVs, allowing reuse of incompletely filled vesicles in the presence of high demand for inhibitory transmission.

  8. Opioid modulation of GABA release in the rat inferior colliculus

    PubMed Central

    Tongjaroenbungam, Walaiporn; Jongkamonwiwat, Nopporn; Cunningham, Joanna; Phansuwan-Pujito, Pansiri; Dodson, Hilary C; Forge, Andrew; Govitrapong, Piyarat; Casalotti, Stefano O

    2004-01-01

    Background The inferior colliculus, which receives almost all ascending and descending auditory signals, plays a crucial role in the processing of auditory information. While the majority of the recorded activities in the inferior colliculus are attributed to GABAergic and glutamatergic signalling, other neurotransmitter systems are expressed in this brain area including opiate peptides and their receptors which may play a modulatory role in neuronal communication. Results Using a perfusion protocol we demonstrate that morphine can inhibit KCl-induced release of [3H]GABA from rat inferior colliculus slices. DAMGO ([D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin) but not DADLE ([D-Ala2, D-Leu5]-enkephalin or U69593 has the same effect as morphine indicating that μ rather than δ or κ opioid receptors mediate this action. [3H]GABA release was diminished by 16%, and this was not altered by the protein kinase C inhibitor bisindolylmaleimide I. Immunostaining of inferior colliculus cryosections shows extensive staining for glutamic acid decarboxylase, more limited staining for μ opiate receptors and relatively few neurons co-stained for both proteins. Conclusion The results suggest that μ-opioid receptor ligands can modify neurotransmitter release in a sub population of GABAergic neurons of the inferior colliculus. This could have important physiological implications in the processing of hearing information and/or other functions attributed to the inferior colliculus such as audiogenic seizures and aversive behaviour. PMID:15353008

  9. Kindling alters entorhinal cortex-hippocampal interaction by increased efficacy of presynaptic GABA(B) autoreceptors in layer III of the entorhinal cortex.

    PubMed

    Gloveli, Tengis; Behr, Joachim; Dugladze, Tamar; Kokaia, Zaal; Kokaia, Merab; Heinemann, Uwe

    2003-08-01

    We studied the effect of kindling, a model of temporal lobe epilepsy, on the frequency-dependent information transfer from the entorhinal cortex to the hippocampus in vitro. In control rats repetitive synaptic activation of layer III projection cells resulted in a frequency dependent depression of the synaptic transfer of action potentials to the hippocampus. One-to-two-days after kindling this effect was strongly reduced. Although no substantial change in synaptic inhibition upon single electrical stimulation was detected in kindled rats, there was a significant depression in the prolonged inhibition following high frequency stimulation. In kindled animals, paired-pulse depression (PPD) of stimulus-evoked IPSCs in layer III neurons was significantly stronger than in control rats. The increase of PPD is most likely caused by an increased presynaptic GABA(B) receptor-mediated autoinhibition. In kindled animals activation of presynaptic GABA(B) receptors by baclofen (10 microM) suppressed monosynaptic IPSCs significantly more than in control rats. In contrast, activation of postsynaptic GABA(B) receptors by baclofen was accompanied by comparable changes of the membrane conductance in both animal groups. Thus, in kindled animals activation of the layer III-CA1 pathway is facilitated by an increased GABA(B) receptor-mediated autoinhibition leading to an enhanced activation of the monosynaptic EC-CA1 pathway.

  10. Artificial Autopolyploidization Modifies the Tricarboxylic Acid Cycle and GABA Shunt in Arabidopsis thaliana Col-0

    NASA Astrophysics Data System (ADS)

    Vergara, Fredd; Kikuchi, Jun; Breuer, Christian

    2016-05-01

    Autopolyploidy is a process whereby the chromosome set is multiplied and it is a common phenomenon in angiosperms. Autopolyploidy is thought to be an important evolutionary force that has led to the formation of new plant species. Despite its relevance, the consequences of autopolyploidy in plant metabolism are poorly understood. This study compares the metabolic profiles of natural diploids and artificial autotetraploids of Arabidopsis thaliana Col-0. Different physiological parameters are compared between diploids and autotetraploids using nuclear magnetic resonance (NMR), elemental analysis (carbon:nitrogen balance) and quantitative real-time PCR (qRT-PCR). The main difference between diploid and autotetraploid A. thaliana Col-0 is observed in the concentration of metabolites related to the tricarboxylic acid cycle (TCA) and γ-amino butyric acid (GABA) shunt, as shown by multivariate statistical analysis of NMR spectra. qRT-PCR shows that genes related to the TCA and GABA shunt are also differentially expressed between diploids and autotetraploids following similar trends as their corresponding metabolites. Solid evidence is presented to demonstrate that autopolyploidy influences core plant metabolic processes.

  11. Profiling neurotransmitter receptor expression in the Ambystoma mexicanum brain.

    PubMed

    Reyes-Ruiz, Jorge Mauricio; Limon, Agenor; Korn, Matthew J; Nakamura, Paul A; Shirkey, Nicole J; Wong, Jamie K; Miledi, Ricardo

    2013-03-22

    Ability to regenerate limbs and central nervous system (CNS) is unique to few vertebrates, most notably the axolotl (Ambystoma sp.). However, despite the fact the neurotransmitter receptors are involved in axonal regeneration, little is known regarding its expression profile. In this project, RT-PCR and qPCR were performed to gain insight into the neurotransmitter receptors present in Ambystoma. Its functional ability was studied by expressing axolotl receptors in Xenopus laevis oocytes by either injection of mRNA or by direct microtransplantation of brain membranes. Oocytes injected with axolotl mRNA expressed ionotropic receptors activated by GABA, aspartate+glycine and kainate, as well as metabotropic receptors activated by acetylcholine and glutamate. Interestingly, we did not see responses following the application of serotonin. Membranes from the axolotl brain were efficiently microtransplanted into Xenopus oocytes and two types of native GABA receptors that differed in the temporal course of their responses and affinities to GABA were observed. Results of this study are necessary for further characterization of axolotl neurotransmitter receptors and may be useful for guiding experiments aimed at understanding activity-dependant limb and CNS regeneration. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  12. Decreased auditory GABA+ concentrations in presbycusis demonstrated by edited magnetic resonance spectroscopy

    PubMed Central

    Gao, Fei; Wang, Guangbin; Ma, Wen; Ren, Fuxin; Li, Muwei; Dong, Yuling; Liu, Cheng; Liu, Bo; Bai, Xue; Zhao, Bin; Edden, Richard A.E.

    2014-01-01

    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central auditory system. Altered GABAergic neurotransmission has been found in both the inferior colliculus and the auditory cortex in animal models of presbycusis. Edited magnetic resonance spectroscopy (MRS), using the MEGA-PRESS sequence, is the most widely used technique for detecting GABA in the human brain. However, to date there has been a paucity of studies exploring changes to the GABA concentrations in the auditory region of patients with presbycusis. In this study, sixteen patients with presbycusis (5 males/11 females, mean age 63.1 ± 2.6 years) and twenty healthy controls (6 males/14 females, mean age 62.5 ± 2.3 years) underwent audiological and MRS examinations. Pure tone audiometry from 0.125 to 8 KHz and tympanometry were used to assess the hearing abilities of all subjects. The pure tone average (PTA; the average of hearing thresholds at 0.5, 1, 2, and 4 kHz) was calculated. The MEGA-PRESS sequence was used to measure GABA+ concentrations in 4 × 3 × 3 cm3 volumes centered on the left and right Heschl’s gyri. GABA+ concentrations were significantly lower in the presbycusis group compared to the control group (left auditory regions: p = 0.002, right auditory regions: p = 0.008). Significant negative correlations were observed between PTA and GABA+ concentrations in the presbycusis group (r = −0.57, p = 0.02), while a similar trend was found in the control group (r = −0.40, p = 0.08). These results are consistent with a hypothesis of dysfunctional GABAergic neurotransmission in the central auditory system in presbycusis, and suggest a potential treatment target for presbycusis. PMID:25463460

  13. Glutamate/GABA+ ratio is associated with the psychosocial domain of autistic and schizotypal traits.

    PubMed

    Ford, Talitha C; Nibbs, Richard; Crewther, David P

    2017-01-01

    The autism and schizophrenia spectra overlap to a large degree in the social and interpersonal domains. Similarly, abnormal excitatory glutamate and inhibitory γ-aminobutyric acid (GABA) neurotransmitter concentrations have been reported for both spectra, with the interplay of these neurotransmitters important for cortical excitation to inhibition regulation. This study investigates whether these neurotransmitter abnormalities are specific to the shared symptomatology, and whether the degree of abnormality increases with increasing symptom severity. Hence, the relationship between the glutamate/GABA ratio and autism and schizophrenia spectrum traits in an unmedicated, subclinical population was investigated. A total of 37 adults (19 female, 18 male) aged 18-38 years completed the Autism Spectrum Quotient (AQ) and Schizotypal Personality Questionnaire (SPQ), and participated in the resting state proton magnetic resonance spectroscopy study in which sequences specific for quantification of glutamate and GABA+ concentration were applied to a right and left superior temporal voxel. There were significant, moderate, positive relationships between right superior temporal glutamate/GABA+ ratio and AQ, SPQ and AQ+SPQ total scores (p<0.05), SPQ subscales Social Anxiety, No Close Friend, Constricted Affect, Odd Behaviour, Odd Speech, Ideas of Reference and Suspiciousness, and AQ subscales Social Skills, Communication and Attention Switching (p<0.05); increased glutamate/GABA+ coinciding with higher scores on these subscales. Only the relationships between glutamate/GABA+ ratio and Social Anxiety, Constricted Affect, Social Skills and Communication survived multiple comparison correction (p< 0.004). Left superior temporal glutamate/GABA+ ratio reduced with increasing restricted imagination (p<0.05). These findings demonstrate evidence for an association between excitatory/inhibitory neurotransmitter concentrations and symptoms that are shared between the autism and

  14. Decreasing GABA function within the medial prefrontal cortex or basolateral amygdala decreases sociability.

    PubMed

    Paine, Tracie A; Swedlow, Nathan; Swetschinski, Lucien

    2017-01-15

    Decreased sociability is a symptom of psychiatric conditions including autism-spectrum disorder and schizophrenia. Both of these conditions are associated with decreases in GABA function, particularly in the medial prefrontal cortex (PFC) and the basolateral amygdala (BLA); structures that are components of the social brain. Here, we determined if decreasing GABA transmission within either the PFC or the BLA decreases social behavior. Rats were implanted with cannulae aimed at either the medial PFC or the BLA and then were tested on up to 4 behavioral tests following bilateral infusions of 0.5μl bicuculline methiodide (BMI, a GABA A receptor antagonist) at doses of 0, 25, or 50ng/μl. Rats were tested in the social interaction test, the social preference test, the sucrose preference test and for locomotor activity (BLA infusions only). Intra-BLA or PFC BMI infusions decreased the amount of time and the number of social interactions in the social interaction test. Further, in the social preference test, rats infused with 50ng BMI no longer exhibited a preference to explore a social over a non-social stimulus. The change in sociability was not due to a change in reward processing or locomotor behavior. Decreasing GABA transmission in either the medial PFC or BLA decreased sociability. Thus, changes in GABA signaling observed in conditions such as autism or schizophrenia may mediate the social withdrawal characteristic of these conditions. Moreover, they suggest that social withdrawal may be treated by drugs that potentiate GABA transmission. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Organization of GABAergic synaptic circuits in the rat ventral tegmental area.

    PubMed

    Ciccarelli, Alessandro; Calza, Arianna; Panzanelli, Patrizia; Concas, Alessandra; Giustetto, Maurizio; Sassoè-Pognetto, Marco

    2012-01-01

    The ventral tegmental area (VTA) is widely implicated in drug addiction and other psychiatric disorders. This brain region is densely populated by dopaminergic (DA) neurons and also contains a sparse population of γ-aminobutyric acid (GABA)ergic cells that regulate the activity of the principal neurons. Therefore, an in-depth knowledge of the organization of VTA GABAergic circuits and of the plasticity induced by drug consumption is essential for understanding the mechanisms by which drugs induce stable changes in brain reward circuits. Using immunohistochemistry, we provide a detailed description of the localization of major GABA(A) and GABA(B) receptor subunits in the rat VTA. We show that DA and GABAergic cells express both GABA(A) and GABA(B) receptors. However VTA neurons differ considerably in the expression of GABA(A) receptor subunits, as the α1 subunit is associated predominantly with non-DA cells, whereas the α3 subunit is present at low levels in both types of VTA neurons. Using an unbiased stereological method, we then demonstrate that α1-positive elements represent only a fraction of non-DA neurons and that the ratio of DA and non-DA cells is quite variable throughout the rostro-caudal extent of the VTA. Interestingly, DA and non-DA cells receive a similar density of perisomatic synapses, whereas axo-dendritic synapses are significantly more abundant in non-DA cells, indicating that local interneurons receive prominent GABAergic inhibition. These findings reveal a differential expression of GABA receptor subtypes in the two major categories of VTA neurons and provide an anatomical basis for interpreting the plasticity of inhibitory circuits induced by drug exposure.

  16. Effects of NaCl Replacement with Gamma-Aminobutyric acid (GABA) on the Quality Characteristics and Sensorial Properties of Model Meat Products

    PubMed Central

    Chun, Ji-Yeon; Cho, Hyung-Yong; Min, Sang-Gi

    2014-01-01

    This study investigated the effects of γ-aminobutylic acid (GABA) on the quality and sensorial properties of both the GABA/NaCl complex and model meat products. GABA/NaCl complex was prepared by spray-drying, and the surface dimensions, morphology, rheology, and saltiness were characterized. For model meat products, pork patties were prepared by replacing NaCl with GABA. For characteristics of the complex, increasing GABA concentration increased the surface dimensions of the complex. However, GABA did not affect the rheological properties of solutions containing the complex. The addition of 2% GABA exhibited significantly higher saltiness than the control (no GABA treatment). In the case of pork patties, sensory testing indicated that the addition of GABA decreased the saltiness intensity. Both the intensity of juiciness and tenderness of patties containing GABA also scored lower than the control, based on the NaCl reduction. These results were consistent with the quality characteristics (cooking loss and texture profile analysis). Nevertheless, overall acceptability of the pork patties showed that up to 1.5%, patties containing GABA did not significantly differ from the control. Consequently, the results indicated that GABA has a potential application in meat products, but also manifested a deterioration of quality by the NaCl reduction, which warrants further exploration. PMID:26761294

  17. Endogenous GABA levels in the pontine reticular formation are greater during wakefulness than during rapid eye movement sleep.

    PubMed

    Vanini, Giancarlo; Wathen, Bradley L; Lydic, Ralph; Baghdoyan, Helen A

    2011-02-16

    Studies using drugs that increase or decrease GABAergic transmission suggest that GABA in the pontine reticular formation (PRF) promotes wakefulness and inhibits rapid eye movement (REM) sleep. Cholinergic transmission in the PRF promotes REM sleep, and levels of endogenous acetylcholine (ACh) in the PRF are significantly greater during REM sleep than during wakefulness or non-REM (NREM) sleep. No previous studies have determined whether levels of endogenous GABA in the PRF vary as a function of sleep and wakefulness. This study tested the hypothesis that GABA levels in cat PRF are greatest during wakefulness and lowest during REM sleep. Extracellular GABA levels were measured during wakefulness, NREM sleep, REM sleep, and the REM sleep-like state (REM(Neo)) caused by microinjecting neostigmine into the PRF. GABA levels varied significantly as a function of sleep and wakefulness, and decreased significantly below waking levels during REM sleep (-42%) and REM(Neo) (-63%). The decrease in GABA levels during NREM sleep (22% below waking levels) was not statistically significant. Compared with NREM sleep, GABA levels decreased significantly during REM sleep (-27%) and REM(Neo) (-52%). Comparisons of REM sleep and REM(Neo) revealed no differences in GABA levels or cortical EEG power. GABA levels did not vary significantly as a function of dialysis site within the PRF. The inverse relationship between changes in PRF levels of GABA and ACh during REM sleep indicates that low GABAergic tone combined with high cholinergic tone in the PRF contributes to the generation of REM sleep.

  18. Metabolic pathways regulated by γ-aminobutyric acid (GABA) contributing to heat tolerance in creeping bentgrass (Agrostis stolonifera)

    PubMed Central

    Li, Zhou; Yu, Jingjin; Peng, Yan; Huang, Bingru

    2016-01-01

    γ-Aminobutyric acid is a non-protein amino acid involved in various metabolic processes. The objectives of this study were to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass through physiological analysis, and to determine major metabolic pathways regulated by GABA through metabolic profiling. Plants were pretreated with 0.5 mM GABA or water before exposed to non-stressed condition (21/19 °C) or heat stress (35/30 °C) in controlled growth chambers for 35 d. The growth and physiological analysis demonstrated that exogenous GABA application significantly improved heat tolerance of creeping bentgrass. Metabolic profiling found that exogenous application of GABA led to increases in accumulations of amino acids (glutamic acid, aspartic acid, alanine, threonine, serine, and valine), organic acids (aconitic acid, malic acid, succinic acid, oxalic acid, and threonic acid), sugars (sucrose, fructose, glucose, galactose, and maltose), and sugar alcohols (mannitol and myo-inositol). These findings suggest that GABA-induced heat tolerance in creeping bentgrass could involve the enhancement of photosynthesis and ascorbate-glutathione cycle, the maintenance of osmotic adjustment, and the increase in GABA shunt. The increased GABA shunt could be the supply of intermediates to feed the tricarboxylic acid cycle of respiration metabolism during a long-term heat stress, thereby maintaining metabolic homeostasis. PMID:27455877

  19. 4,5-Substituted 3-Isoxazolols with Insecticidal Activity Act as Competitive Antagonists of Housefly GABA Receptors.

    PubMed

    Liu, Genyan; Ozoe, Fumiyo; Furuta, Kenjiro; Ozoe, Yoshihisa

    2015-07-22

    The insect GABA receptor (GABAR), which is composed of five RDL subunits, represents an important target for insecticides. A series of 4,5-disubstituted 3-isoxazolols, including muscimol analogues, were synthesized and examined for their activities against four splice variants (ac, ad, bc, and bd) of housefly GABARs expressed in Xenopus oocytes. Muscimol was a more potent agonist than GABA in all four splice variants, whereas synthesized analogues did not exhibit agonism but rather antagonism in housefly GABARs. The introduction of bicyclic aromatic groups at the 4-position of muscimol and the simultaneous replacement of the aminomethyl group with a carbamoyl group at the 5-position to afford six 4-aryl-5-carbamoyl-3-isoxazolols resulted in compounds that exhibited significantly enhanced antagonism with IC50 values in the low micromolar range in the ac variant. The inhibition of GABA-induced currents by 100 μM analogues was approximately 1.5-4-fold greater in the ac and bc variants than in the ad and bd variants. 4-(3-Biphenylyl)-5-carbamoyl-3-isoxazolol displayed competitive antagonism, with IC50 values of 30, 34, 107, and 96 μM in the ac, bc, ad, and bd variants, respectively, and exhibited moderate insecticidal activity against houseflies, with an LD50 value of 5.6 nmol/fly. These findings suggest that these 3-isoxazolol analogues are novel lead compounds for the design and development of insecticides that target the orthosteric site of housefly GABARs.

  20. Endogenous concentrations, pharmacokinetics, and selected pharmacodynamic effects of a single dose of exogenous GABA in horses.

    PubMed

    Knych, H K; Steinmetz, S J; McKemie, D S

    2015-04-01

    The anti-anxiety and calming effects following activation of the GABA receptor have been exploited in performance horses by administering products containing GABA. The primary goal of the study reported here was to describe endogenous concentrations of GABA in horses and the pharmacokinetics, selected pharmacodynamic effects, and CSF concentrations following administration of a GABA-containing product. The mean (±SD) endogenous GABA level was 36.4 ± 12.5 ng/mL (n = 147). Sixteen of these horses received a single intravenous and oral dose of GABA (1650 mg). Blood, urine, and cerebrospinal fluid (n = 2) samples were collected at time 0 and at various times for up to 48 h and analyzed using LC-MS. Plasma clearance and volume of distribution was 155.6 and 147.6 L/h and 0.154 and 7.39 L for the central and peripheral compartments, respectively. Terminal elimination half-life was 22.1 (intravenous) and 25.1 (oral) min. Oral bioavailability was 9.81%. Urine GABA concentrations peaked rapidly returning to baseline levels by 3 h. Horses appeared behaviorally unaffected following oral administration, while sedative-like changes following intravenous administration were transient. Heart rate was increased for 1 h postintravenous administration, and gastrointestinal sounds decreased for approximately 30 min following both intravenous and oral administration. Based on a limited number of horses and time points, exogenously administered GABA does not appear to enter the CSF to an appreciable extent. © 2014 John Wiley & Sons Ltd.

  1. Hypergravity exposure decreases gamma-aminobutyric acid immunoreactivity in axon terminals contacting pyramidal cells in the rat somatosensory cortex: a quantitative immunocytochemical image analysis

    NASA Technical Reports Server (NTRS)

    D'Amelio, F.; Wu, L. C.; Fox, R. A.; Daunton, N. G.; Corcoran, M. L.; Polyakov, I.

    1998-01-01

    Quantitative evaluation of gamma-aminobutyric acid immunoreactivity (GABA-IR) in the hindlimb representation of the rat somatosensory cortex after 14 days of exposure to hypergravity (hyper-G) was conducted by using computer-assisted image processing. The area of GABA-IR axosomatic terminals apposed to pyramidal cells of cortical layer V was reduced in rats exposed to hyper-G compared with control rats, which were exposed either to rotation alone or to vivarium conditions. Based on previous immunocytochemical and behavioral studies, we suggest that this reduction is due to changes in sensory feedback information from muscle receptors. Consequently, priorities for muscle recruitment are altered at the cortical level, and a new pattern of muscle activity is thus generated. It is proposed that the reduction observed in GABA-IR of the terminal area around pyramidal neurons is the immunocytochemical expression of changes in the activity of GABAergic cells that participate in reprogramming motor outputs to achieve effective movement control in response to alterations in the afferent information.

  2. Loss of ethanol conditioned taste aversion and motor stimulation in knockin mice with ethanol-insensitive α2-containing GABA(A) receptors.

    PubMed

    Blednov, Y A; Borghese, C M; McCracken, M L; Benavidez, J M; Geil, C R; Osterndorff-Kahanek, E; Werner, D F; Iyer, S; Swihart, A; Harrison, N L; Homanics, G E; Harris, R A

    2011-01-01

    GABA type A receptors (GABA(A)-Rs) are potential targets of ethanol. However, there are multiple subtypes of this receptor, and, thus far, individual subunits have not been definitively linked with specific ethanol behavioral actions. Interestingly, though, a chromosomal cluster of four GABA(A)-R subunit genes, including α2 (Gabra2), was associated with human alcoholism (Am J Hum Genet 74:705-714, 2004; Pharmacol Biochem Behav 90:95-104, 2008; J Psychiatr Res 42:184-191, 2008). The goal of our study was to determine the role of receptors containing this subunit in alcohol action. We designed an α2 subunit with serine 270 to histidine and leucine 277 to alanine mutations that was insensitive to potentiation by ethanol yet retained normal GABA sensitivity in a recombinant expression system. Knockin mice containing this mutant subunit were tested in a range of ethanol behavioral tests. These mutant mice did not develop the typical conditioned taste aversion in response to ethanol and showed complete loss of the motor stimulant effects of ethanol. Conversely, they also demonstrated changes in ethanol intake and preference in multiple tests. The knockin mice showed increased ethanol-induced hypnosis but no difference in anxiolytic effects or recovery from acute ethanol-induced motor incoordination. Overall, these studies demonstrate that the effects of ethanol at GABAergic synapses containing the α2 subunit are important for specific behavioral effects of ethanol that may be relevant to the genetic linkage of this subunit with human alcoholism.

  3. Effect of GABA on oxidative stress in the skeletal muscles and plasma free amino acids in mice fed high-fat diet.

    PubMed

    Xie, Z X; Xia, S F; Qiao, Y; Shi, Y H; Le, G W

    2015-06-01

    Increased levels of plasma free amino acids (pFAAs) can disturb the blood glucose levels in patients with obesity, diabetes mellitus and metabolic syndrome (MS) and are associated with enhanced protein oxidation. Oxidation of proteins, especially in the muscles, can promote protein degradation and elevate the levels of pFAAs. Gamma-aminobutyric acid (GABA), a food additive, can reduce high-fat diet (HFD)-induced hyperglycaemia; however, the mechanisms remain unclear. The aim of this study was to evaluate the effects of GABA on protein oxidation and pFAAs changes. One hundred male C57BL/6 mice were randomly divided into five groups that were fed with control diet, HFD and HFD supplied with 0.2%, 0.12% and 0.06% GABA in drinking water for 20 weeks respectively. HFD feeding led to muscular oxidative stress, protein oxidation, pFAA disorders, hyperglycaemia and augmented plasma GABA levels. Treatment with GABA restored normally fasting blood glucose level and dose-dependently inhibited body weight gains, muscular oxidation and protein degradation. While medium and low doses of GABA mitigated HFD-induced pFAA disorders, the high dose of GABA deteriorated the pFAA disorders. Medium dose of GABA increased the levels of GABA, but high dose of GABA reduced the levels of plasma GABA and increased the activity of succinic semialdehyde dehydrogenase in the liver. Therefore, treatment with GABA mitigated HFD-induced hyperglycaemia probably by repairing HFD-induced muscular oxidative stress and pFAA disorders in mice. Our data also suggest that an optimal dose of GABA is crucial for the prevention of excess GABA-related decrease in the levels of pFAA and GABA as well as obesity. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

  4. Taurine-induced attenuation of MPP+ neurotoxicity in vitro: a possible role for the GABA(A) subclass of GABA receptors.

    PubMed

    O'Byrne, M B; Tipton, K F

    2000-05-01

    Taurine is a sulphur-containing beta-amino acid found in high (millimolar) concentrations in excitable tissues such as brain and heart. Its suggested roles include osmoregulator, thermoregulator, neuromodulator, and potential neurotransmitter. This amino acid has also been shown to be released in large concentrations during ischaemia and excitotoxin-induced neuronal damage. Here we report a protective effect of taurine against MPP(+)-induced neurotoxicity in coronal slices from rat brain. Significant protective effects were observed at taurine concentrations of 20 and 1 mM, suggesting a potential role for taurine in cases of neuronal insult. Studies with the synthetic taurine analogues taurine phosphonate, guanidinoethane sulphonate, and trimethyltaurine suggested the observed effect to be mediated via an extracellular mechanism. The use of GABA receptor ligands muscimol and bicuculline indicated the effect to be mediated through activation of GABA(A) receptors.

  5. Neuropeptide Y Opposes Alcohol Effects on GABA Release in Amygdala and Blocks the Transition to Alcohol Dependence

    PubMed Central

    Gilpin, Nicholas W.; Misra, Kaushik; Herman, Melissa A.; Cruz, Maureen T.; Koob, George F.; Roberto, Marisa

    2011-01-01

    Background During the transition to alcohol and drug addiction, neuromodulator systems in the extended amygdala are recruited to mediate aspects of withdrawal and relapse via convergence on inhibitory GABA neurons in central amygdala (CeA). Methods This study investigated the role of neuropeptide Y (NPY) in excessive alcohol drinking by making rats dependent on alcohol via alcohol vapor inhalation. This study also utilized intracellular and whole-cell recording techniques to determine the effects of NPY on GABAergic inhibitory transmission in CeA, synaptic mechanisms involved in these NPY effects, and NPY interactions with alcohol in the CeA of alcohol-naïve and alcohol-dependent rats. Results Chronic NPY treatment blocked excessive operant alcohol-reinforced responding associated with alcohol dependence, as well as gradual increases in alcohol responding by intermittently tested non-dependent controls. NPY decreased baseline GABAergic transmission and reversed alcohol-induced enhancement of inhibitory transmission in CeA by suppressing GABA release via actions at presynaptic Y2 receptors. Conclusions These results highlight NPY modulation of GABAergic signaling in central amygdala as a promising pharmacotheraputic target for the treatment of alcoholism. GABA neurons in the CeA likely constitute a major point of convergence for neuromodulator systems recruited during the transition to alcohol dependence. PMID:21459365

  6. Differential maturation of vesicular glutamate and GABA transporter expression in the mouse auditory forebrain during the first weeks of hearing.

    PubMed

    Hackett, Troy A; Clause, Amanda R; Takahata, Toru; Hackett, Nicholas J; Polley, Daniel B

    2016-06-01

    Vesicular transporter proteins are an essential component of the presynaptic machinery that regulates neurotransmitter storage and release. They also provide a key point of control for homeostatic signaling pathways that maintain balanced excitation and inhibition following changes in activity levels, including the onset of sensory experience. To advance understanding of their roles in the developing auditory forebrain, we tracked the expression of the vesicular transporters of glutamate (VGluT1, VGluT2) and GABA (VGAT) in primary auditory cortex (A1) and medial geniculate body (MGB) of developing mice (P7, P11, P14, P21, adult) before and after ear canal opening (~P11-P13). RNA sequencing, in situ hybridization, and immunohistochemistry were combined to track changes in transporter expression and document regional patterns of transcript and protein localization. Overall, vesicular transporter expression changed the most between P7 and P21. The expression patterns and maturational trajectories of each marker varied by brain region, cortical layer, and MGB subdivision. VGluT1 expression was highest in A1, moderate in MGB, and increased with age in both regions. VGluT2 mRNA levels were low in A1 at all ages, but high in MGB, where adult levels were reached by P14. VGluT2 immunoreactivity was prominent in both regions. VGluT1 (+) and VGluT2 (+) transcripts were co-expressed in MGB and A1 somata, but co-localization of immunoreactive puncta was not detected. In A1, VGAT mRNA levels were relatively stable from P7 to adult, while immunoreactivity increased steadily. VGAT (+) transcripts were rare in MGB neurons, whereas VGAT immunoreactivity was robust at all ages. Morphological changes in immunoreactive puncta were found in two regions after ear canal opening. In the ventral MGB, a decrease in VGluT2 puncta density was accompanied by an increase in puncta size. In A1, perisomatic VGAT and VGluT1 terminals became prominent around the neuronal somata. Overall, the

  7. Differential maturation of vesicular glutamate and GABA transporter expression in the mouse auditory forebrain during the first weeks of hearing

    PubMed Central

    Hackett, Troy A.; Clause, Amanda R.; Takahata, Toru; Hackett, Nicholas J.; Polley, Daniel B.

    2015-01-01

    Vesicular transporter proteins are an essential component of the presynaptic machinery that regulates neurotransmitter storage and release. They also provide a key point of control for homeostatic signaling pathways that maintain balanced excitation and inhibition following changes in activity levels, including the onset of sensory experience. To advance understanding of their roles in the developing auditory forebrain, we tracked the expression of the vesicular transporters of glutamate (VGluT1, VGluT2) and GABA (VGAT) in primary auditory cortex (A1) and medial geniculate body (MGB) of developing mice (P7, P11, P14, P21, adult) before and after ear canal opening (~P11–P13). RNA sequencing, in situ hybridization, and immunohistochemistry were combined to track changes in transporter expression and document regional patterns of transcript and protein localization. Overall, vesicular transporter expression changed the most between P7 and P21. The expression patterns and maturational trajectories of each marker varied by brain region, cortical layer, and MGB subdivision. VGluT1 expression was highest in A1, moderate in MGB, and increased with age in both regions. VGluT2 mRNA levels were low in A1 at all ages, but high in MGB, where adult levels were reached by P14. VGluT2 immunoreactivity was prominent in both regions. VGluT1+ and VGluT2+ transcripts were co-expressed in MGB and A1 somata, but co-localization of immunoreactive puncta was not detected. In A1, VGAT mRNA levels were relatively stable from P7 to adult, while immunoreactivity increased steadily. VGAT+ transcripts were rare in MGB neurons, whereas VGAT immunoreactivity was robust at all ages. Morphological changes in immunoreactive puncta were found in two regions after ear canal opening. In the ventral MGB, a decrease in VGluT2 puncta density was accompanied by an increase in puncta size. In A1, peri-somatic VGAT and VGluT1 terminals became prominent around the neuronal somata. Overall, the observed

  8. Excitatory synaptic inputs to mouse on-off direction-selective retinal ganglion cells lack direction tuning.

    PubMed

    Park, Silvia J H; Kim, In-Jung; Looger, Loren L; Demb, Jonathan B; Borghuis, Bart G

    2014-03-12

    Direction selectivity represents a fundamental visual computation. In mammalian retina, On-Off direction-selective ganglion cells (DSGCs) respond strongly to motion in a preferred direction and weakly to motion in the opposite, null direction. Electrical recordings suggested three direction-selective (DS) synaptic mechanisms: DS GABA release during null-direction motion from starburst amacrine cells (SACs) and DS acetylcholine and glutamate release during preferred direction motion from SACs and bipolar cells. However, evidence for DS acetylcholine and glutamate release has been inconsistent and at least one bipolar cell type that contacts another DSGC (On-type) lacks DS release. Here, whole-cell recordings in mouse retina showed that cholinergic input to On-Off DSGCs lacked DS, whereas the remaining (glutamatergic) input showed apparent DS. Fluorescence measurements with the glutamate biosensor intensity-based glutamate-sensing fluorescent reporter (iGluSnFR) conditionally expressed in On-Off DSGCs showed that glutamate release in both On- and Off-layer dendrites lacked DS, whereas simultaneously recorded excitatory currents showed apparent DS. With GABA-A receptors blocked, both iGluSnFR signals and excitatory currents lacked DS. Our measurements rule out DS release from bipolar cells onto On-Off DSGCs and support a theoretical model suggesting that apparent DS excitation in voltage-clamp recordings results from inadequate voltage control of DSGC dendrites during null-direction inhibition. SAC GABA release is the apparent sole source of DS input onto On-Off DSGCs.

  9. Electrophysiological and morphological properties of neurons in the prepositus hypoglossi nucleus that express both ChAT and VGAT in a double-transgenic rat model.

    PubMed

    Saito, Yasuhiko; Zhang, Yue; Yanagawa, Yuchio

    2015-04-01

    Although it has been proposed that neurons that contain both acetylcholine (ACh) and γ-aminobutyric acid (GABA) are present in the prepositus hypoglossi nucleus (PHN), these neurons have not been characterized because of the difficulty in identifying them. In the present study, PHN neurons that express both choline acetyltransferase and the vesicular GABA transporter (VGAT) were identified using double-transgenic rats, in which the cholinergic and inhibitory neurons express the fluorescent proteins tdTomato and Venus, respectively. To characterize the neurons that express both tdTomato and Venus (D+ neurons), the afterhyperpolarization (AHP) profiles and firing patterns of these neurons were investigated via whole-cell recordings of brainstem slice preparations. Regarding the three AHP profiles and four firing patterns that the D+ neurons exhibited, an AHP with an afterdepolarization and a firing pattern that exhibited a delay in the generation of the first spike were the preferential properties of these neurons. In the three morphological types classified, the multipolar type that exhibited radiating dendrites was predominant among the D+ neurons. Immunocytochemical analysis revealed that the VGAT-immunopositive axonal boutons that expressed tdTomato were primarily located in the dorsal cap of inferior olive (IO) and the PHN. Although the PHN receives cholinergic inputs from the pedunculopontine tegmental nucleus and laterodorsal tegmental nucleus, D+ neurons were absent from these brain areas. Together, these results suggest that PHN neurons that co-express ACh and GABA exhibit specific electrophysiological and morphological properties, and innervate the dorsal cap of the IO and the PHN. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  10. The Enantiomers of 4-Amino-3-fluorobutanoic Acid as Substrates for γ-Aminobutyric Acid Aminotransferase. Conformational Probes for GABA Binding†

    PubMed Central

    Clift, Michael; Ji, Haitao; Deniau, Gildas P.; O’Hagan, David; Silverman, Richard B.

    2008-01-01

    γ-Aminobutyric acid aminotransferase (GABA-AT), a pyridoxal 5’-phosphate dependent enzyme, catalyzes the degradation of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) to succinic semialdehyde with concomitant conversion of pyridoxal 5’-phosphate (PLP) to pyridoxamine 5’-phosphate (PMP). The enzyme then catalyzes the conversion of α-ketoglutarate to the excitatory neurotransmitter L-glutamate. Racemic 4-amino-3-fluorobutanoic acid (3-F-GABA) was shown previously to act as a substrate for GABA-AT, not for transamination, but for HF elimination. Here we report studies of the reaction catalyzed by GABA-AT on (R)- and (S)-3-F-GABA. Neither enantiomer is a substrate for transamination. Very little elimination from the (S)-enantiomer was detected using a coupled enzyme assay; The rate of elimination of HF from the (R)-enantiomer is at least 10 times greater than that for the (S)-enantiomer. The (R)-enantiomer is about 20 times more efficient as a substrate for GABA-AT catalyzed HF elimination than GABA is a substrate for transamination. The (R)-enantiomer also inhibits the transamination of GABA 10 times more effectively than the (S)-enantiomer. Using a combination of computer modeling and the knowledge that vicinal C-F and C-NH3+ bonds have a strong preference to align gauche rather than anti to each other, it is concluded that on binding of free 3-F-GABA to GABA-AT the optimal conformation places the C-NH3+ and C-F bonds gauche in the (R)-enantiomer but anti in the (S)-enantiomer. Furthermore, the dynamic binding process and the bioactive conformation of GABA bound to GABA-AT have been inferred based on the different biological behavior of the two enantiomers of 3-F-GABA when they bind to the enzyme. The present study suggests that the C-F bond can be utilized as a conformational probe to explore the dynamic binding process and provide insight into the bioactive conformation of substrates, which cannot be easily determined by other biophysical

  11. GABA(A) receptors in visual and auditory cortex and neural activity changes during basic visual stimulation.

    PubMed

    Qin, Pengmin; Duncan, Niall W; Wiebking, Christine; Gravel, Paul; Lyttelton, Oliver; Hayes, Dave J; Verhaeghe, Jeroen; Kostikov, Alexey; Schirrmacher, Ralf; Reader, Andrew J; Northoff, Georg

    2012-01-01

    Recent imaging studies have demonstrated that levels of resting γ-aminobutyric acid (GABA) in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABA(A) receptors, in the changes in brain activity between the eyes closed (EC) and eyes open (EO) state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: an EO and EC block design, allowing the modeling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [(18)F]Flumazenil PET to measure GABA(A) receptor binding potentials. It was demonstrated that the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex also predicted the change in functional connectivity between the visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABA(A) receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.

  12. Comparison of taurine, GABA, Glu, and Asp as scavengers of malondialdehyde in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Deng, Yan; Wang, Wei; Yu, Pingfeng; Xi, Zhijiang; Xu, Lijian; Li, Xiaolong; He, Nongyue

    2013-04-01

    The purpose of this study is to determine if amino acid neurotransmitters such as gamma-aminobutyric acid (GABA), taurine, glutamate (Glu), and aspartate (Asp) can scavenge activated carbonyl toxicants. In vitro, direct reaction between malondialdehyde (MDA) and amino acids was researched using different analytical methods. The results indicated that scavenging activated carbonyl function of taurine and GABA is very strong and that of Glu and Asp is very weak in pathophysiological situations. The results provided perspective into the reaction mechanism of taurine and GABA as targets of activated carbonyl such as MDA in protecting nerve terminals. In vivo, we studied the effect of taurine and GABA as antioxidants by detecting MDA concentration and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. It was shown that MDA concentration was decreased significantly, and the activities of SOD and GSH-Px were increased significantly in the cerebral cortex and hippocampus of acute epileptic state rats, after the administration of taurine and GABA. The results indicated that the peripherally administered taurine and GABA can scavenge free radicals and protect the tissue against activated carbonyl in vivo and in vitro.

  13. Mechanism of Inactivation of GABA Aminotransferase by (E)- and (Z)-(1S,3S)-3-Amino-4-fluoromethylenyl-1-cyclopentanoic Acid

    PubMed Central

    Lee, Hyunbeom; Le, Hoang V.; Wu, Rui; Doud, Emma; Sanishvili, Ruslan; Kellie, John F.; Compton, Phillip D.; Pachaiyappan, Boobalan; Liu, Dali; Kelleher, Neil L.

    2015-01-01

    When γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the mammalian central nervous system, falls below a threshold level, seizures occur. One approach to raise GABA concentrations is to inhibit GABA aminotransferase (GABA-AT), a pyridoxal 5’-phosphate-dependent enzyme that degrades GABA. We have previously developed (1S,3S)-3-amino-4-difluoromethylene-1-cyclopentanoic acid (CPP-115), which is 186 times more efficient in inactivating GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. We also developed (E)- and (Z)-(1S,3S)-3-amino-4-fluoromethylenyl-1-cyclopentanoic acid (1 and 2, respectively), monofluorinated analogs of CPP-115, which are comparable to vigabatrin in inactivating GABA-AT. Here we report the mechanism of inactivation of GABA-AT by 1 and 2. Both produce a metabolite that induces disruption of the Glu270-Arg445 salt bridge to accommodate interaction between the metabolite formyl group and Arg445. This is the second time that Arg445 has interacted with a ligand and is involved in GABA-AT inactivation, thereby confirming the importance of Arg445 in future inactivator design. PMID:26110556

  14. Mechanism of Inactivation of GABA Aminotransferase by (E)- and (Z)-(1S,3S)-3-Amino-4-fluoromethylenyl-1-cyclopentanoic Acid.

    PubMed

    Lee, Hyunbeom; Le, Hoang V; Wu, Rui; Doud, Emma; Sanishvili, Ruslan; Kellie, John F; Compton, Phillip D; Pachaiyappan, Boobalan; Liu, Dali; Kelleher, Neil L; Silverman, Richard B

    2015-09-18

    When γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the mammalian central nervous system, falls below a threshold level, seizures occur. One approach to raise GABA concentrations is to inhibit GABA aminotransferase (GABA-AT), a pyridoxal 5'-phosphate-dependent enzyme that degrades GABA. We have previously developed (1S,3S)-3-amino-4-difluoromethylene-1-cyclopentanoic acid (CPP-115), which is 186 times more efficient in inactivating GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. We also developed (E)- and (Z)-(1S,3S)-3-amino-4-fluoromethylenyl-1-cyclopentanoic acid (1 and 2, respectively), monofluorinated analogs of CPP-115, which are comparable to vigabatrin in inactivating GABA-AT. Here, we report the mechanism of inactivation of GABA-AT by 1 and 2. Both produce a metabolite that induces disruption of the Glu270-Arg445 salt bridge to accommodate interaction between the metabolite formyl group and Arg445. This is the second time that Arg445 has interacted with a ligand and is involved in GABA-AT inactivation, thereby confirming the importance of Arg445 in future inactivator design.

  15. Baclofen blocks the acquisition and expression of mitragynine-induced conditioned place preference in rats.

    PubMed

    Yusoff, Nurul H M; Mansor, Sharif M; Müller, Christian P; Hassan, Zurina

    2018-06-01

    Mitragynine is the major alkaloid found in the leaves of M. speciosa Korth (Rubiaceae), a plant that is native to Southeast Asia. This compound has been used, either traditionally or recreationally, due to its psychostimulant and opioid-like effects. Recently, mitragynine has been shown to exert conditioned place preference (CPP), indicating the rewarding and motivational properties of M. speciosa. Here, the involvement of GABA B receptors in mediating mitragynine reward is studied using a CPP paradigm in rats. First, we examined the effects of GABA B receptor agonist baclofen (1.25, 2.5 and 5 mg/kg) on the acquisition of mitragynine (10 mg/kg)-induced CPP. Second, the involvement of GABA B receptors in the expression of mitragynine-induced CPP was tested. We found that the acquisition of mitragynine-induced CPP could be blocked by higher doses (2.5 and 5 mg/kg) of baclofen. Baclofen at a high dose inhibited locomotor activity and caused a CPP. Furthermore, we found that baclofen (2.5 and 5 mg/kg) also blocked the expression of mitragynine-induced CPP. These findings suggest that both, the acquisition and expression of mitragynine's reinforcing properties is controlled by the GABA B receptor. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Single Cell Gene Expression Profiling of Skeletal Muscle-Derived Cells.

    PubMed

    Gatto, Sole; Puri, Pier Lorenzo; Malecova, Barbora

    2017-01-01

    Single cell gene expression profiling is a fundamental tool for studying the heterogeneity of a cell population by addressing the phenotypic and functional characteristics of each cell. Technological advances that have coupled microfluidic technologies with high-throughput quantitative RT-PCR analyses have enabled detailed analyses of single cells in various biological contexts. In this chapter, we describe the procedure for isolating the skeletal muscle interstitial cells termed Fibro-Adipogenic Progenitors (FAPs ) and their gene expression profiling at the single cell level. Moreover, we accompany our bench protocol with bioinformatics analysis designed to process raw data as well as to visualize single cell gene expression data. Single cell gene expression profiling is therefore a useful tool in the investigation of FAPs heterogeneity and their contribution to muscle homeostasis.

  17. Expression of heparanase in basal cell carcinoma and squamous cell carcinoma.

    PubMed

    Pinhal, Maria Aparecida Silva; Almeida, Maria Carolina Leal; Costa, Alessandra Scorse; Theodoro, Thérèse Rachell; Serrano, Rodrigo Lorenzetti; Machado, Carlos D'Apparecida Santos

    2016-01-01

    Heparanase is an enzyme that cleaves heparan sulfate chains. Oligosaccharides generated by heparanase induce tumor progression. Basal cell carcinoma and squamous cell carcinoma comprise types of nonmelanoma skin cancer. Evaluate the glycosaminoglycans profile and expression of heparanase in two human cell lines established in culture, immortalized skin keratinocyte (HaCaT) and squamous cell carcinoma (A431) and also investigate the expression of heparanase in basal cell carcinoma, squamous cell carcinoma and eyelid skin of individuals not affected by the disease (control). Glycosaminoglycans were quantified by electrophoresis and indirect ELISA method. The heparanase expression was analyzed by quantitative RT-PCR (qRTPCR). The A431 strain showed significant increase in the sulfated glycosaminoglycans, increased heparanase expression and decreased hyaluronic acid, comparing to the HaCaT lineage. The mRNA expression of heparanase was significantly higher in Basal cell carcinoma and squamous cell carcinoma compared with control skin samples. It was also observed increased heparanase expression in squamous cell carcinoma compared to the Basal cell carcinoma. The glycosaminoglycans profile, as well as heparanase expression are different between HaCaT and A431 cell lines. The increased expression of heparanase in Basal cell carcinoma and squamous cell carcinoma suggests that this enzyme could be a marker for the diagnosis of such types of non-melanoma cancers, and may be useful as a target molecule for future alternative treatment.

  18. Effects of yoga versus walking on mood, anxiety, and brain GABA levels: a randomized controlled MRS study.

    PubMed

    Streeter, Chris C; Whitfield, Theodore H; Owen, Liz; Rein, Tasha; Karri, Surya K; Yakhkind, Aleksandra; Perlmutter, Ruth; Prescot, Andrew; Renshaw, Perry F; Ciraulo, Domenic A; Jensen, J Eric

    2010-11-01

    Yoga and exercise have beneficial effects on mood and anxiety. γ-Aminobutyric acid (GABA)-ergic activity is reduced in mood and anxiety disorders. The practice of yoga postures is associated with increased brain GABA levels. This study addresses the question of whether changes in mood, anxiety, and GABA levels are specific to yoga or related to physical activity. Healthy subjects with no significant medical/psychiatric disorders were randomized to yoga or a metabolically matched walking intervention for 60 minutes 3 times a week for 12 weeks. Mood and anxiety scales were taken at weeks 0, 4, 8, 12, and before each magnetic resonance spectroscopy scan. Scan 1 was at baseline. Scan 2, obtained after the 12-week intervention, was followed by a 60-minute yoga or walking intervention, which was immediately followed by Scan 3. The yoga subjects (n = 19) reported greater improvement in mood and greater decreases in anxiety than the walking group (n = 15). There were positive correlations between improved mood and decreased anxiety and thalamic GABA levels. The yoga group had positive correlations between changes in mood scales and changes in GABA levels. The 12-week yoga intervention was associated with greater improvements in mood and anxiety than a metabolically matched walking exercise. This is the first study to demonstrate that increased thalamic GABA levels are associated with improved mood and decreased anxiety. It is also the first time that a behavioral intervention (i.e., yoga postures) has been associated with a positive correlation between acute increases in thalamic GABA levels and improvements in mood and anxiety scales. Given that pharmacologic agents that increase the activity of the GABA system are prescribed to improve mood and decrease anxiety, the reported correlations are in the expected direction. The possible role of GABA in mediating the beneficial effects of yoga on mood and anxiety warrants further study.

  19. Effects of traditionally used anxiolytic botanicals on enzymes of the gamma-aminobutyric acid (GABA) system.

    PubMed

    Awad, R; Levac, D; Cybulska, P; Merali, Z; Trudeau, V L; Arnason, J T

    2007-09-01

    In Canada, the use of botanical natural health products (NHPs) for anxiety disorders is on the rise, and a critical evaluation of their safety and efficacy is required. The purpose of this study was to determine whether commercially available botanicals directly affect the primary brain enzymes responsible for gamma-aminobutyric acid (GABA) metabolism. Anxiolytic plants may interact with either glutamic acid decarboxylase (GAD) or GABA transaminase (GABA-T) and ultimately influence brain GABA levels and neurotransmission. Two in vitro rat brain homogenate assays were developed to determine the inhibitory concentrations (IC50) of aqueous and ethanolic plant extracts. Approximately 70% of all extracts that were tested showed little or no inhibitory effect (IC50 values greater than 1 mg/mL) and are therefore unlikely to affect GABA metabolism as tested. The aqueous extract of Melissa officinalis (lemon balm) exhibited the greatest inhibition of GABA-T activity (IC50 = 0.35 mg/mL). Extracts from Centella asiatica (gotu kola) and Valeriana officinalis (valerian) stimulated GAD activity by over 40% at a dose of 1 mg/mL. On the other hand, both Matricaria recutita (German chamomile) and Humulus lupulus (hops) showed significant inhibition of GAD activity (0.11-0.65 mg/mL). Several of these species may therefore warrant further pharmacological investigation. The relation between enzyme activity and possible in vivo mode of action is discussed.

  20. Role of GABA Deficit in Sensitivity to the Psychotomimetic Effects of Amphetamine.

    PubMed

    Ahn, Kyung-Heup; Sewell, Andrew; Elander, Jacqueline; Pittman, Brian; Ranganathan, Mohini; Gunduz-Bruce, Handan; Krystal, John; D'Souza, Deepak Cyril

    2015-11-01

    Some schizophrenia patients are more sensitive to amphetamine (AMPH)-induced exacerbations in psychosis-an effect that correlates with higher striatal dopamine release. This enhanced vulnerability may be related to gamma-aminobutyric acid (GABA) deficits observed in schizophrenia. We hypothesized that a pharmacologically induced GABA deficit would create vulnerability to the psychotomimetic effects to the 'subthreshold' dose of AMPH in healthy subjects, which by itself would not induce clinically significant increase in positive symptoms. To test this hypothesis, a GABA deficit was induced by intravenous infusion of iomazenil (IOM; 3.7 μg/kg), an antagonist and partial inverse agonist of benzodiazepine receptor. A subthreshold dose of AMPH (0.1 mg/kg) was administered by intravenous infusion. Healthy subjects received placebo IOM followed by placebo AMPH, active IOM followed by placebo AMPH, placebo IOM followed by active AMPH, and active IOM followed by active AMPH in a randomized, double-blind crossover design over 4 test days. Twelve healthy subjects who had a subclinical response to active AMPH alone were included in the analysis. Psychotomimetic effects (Positive and Negative Syndrome Scale (PANSS)), perceptual alterations (Clinician Administered Dissociative Symptoms Scale (CADSS)), and subjective effects (visual analog scale) were captured before and after the administration of drugs. IOM significantly augmented AMPH-induced peak changes in PANSS positive symptom subscale and both subjective and objective CADSS scores. There were no pharmacokinetic interactions. In conclusion, GABA deficits increased vulnerability to amphetamine-induced psychosis-relevant effects in healthy subjects, suggesting that pre-existing GABA deficits may explain why a subgroup of schizophrenia patients are vulnerable to AMPH.