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Sample records for acid gaba inhibitory

  1. γ-Aminobutyric Acid (GABA) Production and Angiotensin-I Converting Enzyme (ACE) Inhibitory Activity of Fermented Soybean Containing Sea Tangle by the Co-Culture of Lactobacillus brevis with Aspergillus oryzae.

    PubMed

    Jang, Eun Kyeong; Kim, Nam Yeun; Ahn, Hyung Jin; Ji, Geun Eog

    2015-08-01

    To enhance the γ-aminobutyric acid (GABA) content, the optimized fermentation of soybean with added sea tangle extract was evaluated at 30°C and pH 5.0. The medium was first inoculated with Aspergillus oryzae strain FMB S46471 and fermented for 3 days, followed by the subsequent inoculation with Lactobacillus brevis GABA 100. After fermentation for 7 days, the fermented soybean showed approximately 1.9 g/kg GABA and exhibited higher ACE inhibitory activity than the traditional soybean product. Furthermore, several peptides in the fraction containing the highest ACE inhibitory activity were identified. The novel fermented soybean enriched with GABA and ACE inhibitory components has great pharmaceutical and functional food values.

  2. 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.

  3. Maternal oxytocin triggers a transient inhibitory switch in GABA signaling in the fetal brain during delivery.

    PubMed

    Tyzio, Roman; Cossart, Rosa; Khalilov, Ilgam; Minlebaev, Marat; Hübner, Christian A; Represa, Alfonso; Ben-Ari, Yehezkel; Khazipov, Rustem

    2006-12-15

    We report a signaling mechanism in rats between mother and fetus aimed at preparing fetal neurons for delivery. In immature neurons, gamma-aminobutyric acid (GABA) is the primary excitatory neurotransmitter. We found that, shortly before delivery, there is a transient reduction in the intracellular chloride concentration and an excitatory-to-inhibitory switch of GABA actions. These events were triggered by oxytocin, an essential maternal hormone for labor. In vivo administration of an oxytocin receptor antagonist before delivery prevented the switch of GABA actions in fetal neurons and aggravated the severity of anoxic episodes. Thus, maternal oxytocin inhibits fetal neurons and increases their resistance to insults during delivery.

  4. Inhibitory effect of GABA on sympathetic neurotransmission in rabbit ear artery.

    PubMed

    Manzini, S; Maggi, C A; Meli, A

    1985-01-01

    GABA 100 microM inhibited neurogenic vasoconstrictor responses elicited in rabbit ear artery by field stimulation at various frequencies. GABA was ineffective both on resting tone and on noradrenaline (0.05-5 microM)- and high-K+ (24-54 mM)-induced tonic contraction. GABA effectiveness against field stimulation-induced vasoconstriction was inversely related to the frequency of stimulation. This action of GABA was mimicked by a selective GABAB agonist, such as baclofen (100 microM), but not by selective GABAA agonists as muscimol (100 microM) and homotaurine (100 microM). The selective GABAB antagonists 5-aminovaleric acid (1 mM) and homotaurine (100 microM) completely suppressed the inhibitory effect of GABA on field stimulation-induced vasoconstrictions. GABA action was partially reversed also by the selective GABAA antagonist picrotoxin (100 microM); however, this drug "per se" determined an increase in amplitude of field stimulation-induced contractions which in turn could have determined the minor effect of GABA. As a whole these data suggest that GABA can inhibit sympathetic neurotransmission in rabbit ear artery through the stimulation of a prejunctional receptor of the GABAB subtype.

  5. Some dipeptides reverse the inhibitory effect of GABA on /sup 35/S-TBPS binding

    SciTech Connect

    Squires, R.F.; Saederup, E.

    1987-05-01

    All known GABA-A receptor blocker reverse the inhibitory effect of GABA on /sup 35/S-t-butylphosphorothionate (TBPS) binding to rat brain membranes in vitro. This system has already been used to identify several novel GABA antagonists. The authors now report that 12 out of 52 dipeptides tested (all containing L-amino acids), at 1 mM, significantly reverse the inhibitory effect of 1 ..mu..M GABA, which inhibits specific /sup 35/S-TBPS binding about 60%. Most of the active dipeptides contain an aromatic and a basic amino acid. Tryptophan usually conferred greater activity than phe or tyr, while arg usually conferred greater activity than lys or his. Several larger peptides containing the HFRW sequence found in ACTH were also GABA antagonists; ACTH(1-24), ACTH(1-18), ACTH(1-13), ACTH(4-10) and ..gamma..-MSH while ACTH(11-24) was inactive. The excitatory effects of these later peptides may be in part due to blockade of GABA-A receptors.

  6. "Brain MR spectroscopy in autism spectrum disorder-the GABA excitatory/inhibitory imbalance theory revisited".

    PubMed

    Brix, Maiken K; Ersland, Lars; Hugdahl, Kenneth; Grüner, Renate; Posserud, Maj-Britt; Hammar, Åsa; Craven, Alexander R; Noeske, Ralph; Evans, C John; Walker, Hanne B; Midtvedt, Tore; Beyer, Mona K

    2015-01-01

    Magnetic resonance spectroscopy (MRS) from voxels placed in the left anterior cingulate cortex (ACC) was measured from 14 boys with Autism Spectrum Disorder (ASD) and 24 gender and age-matched typically developing (TD) control group. Our main aims were to compare the concentration of γ-aminobutyric acid (GABA) between the two groups, and to investigate the relationship between brain metabolites and autism symptom severity in the ASD group. We did find a significant negative correlation in the ASD group between Autism Spectrum Screening Questionnaire (ASSQ) and GABA+/Cr, which may imply that severity of symptoms in ASD is associated with differences in the level of GABA in the brain, supporting the excitatory/inhibitory (E/I) imbalance theory. However we did not find a significant difference between the two groups in GABA levels.

  7. 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

  8. GABA uptake into astrocytes is not associated with significant metabolic cost: implications for brain imaging of inhibitory transmission.

    PubMed

    Chatton, Jean-Yves; Pellerin, Luc; Magistretti, Pierre J

    2003-10-14

    Synaptically released glutamate has been identified as a signal coupling excitatory neuronal activity to increased glucose utilization. The proposed mechanism of this coupling involves glutamate uptake into astrocytes resulting in increased intracellular Na+ (Nai+) and activation of the Na+/K+-ATPase. Increased metabolic demand linked to disruption of Nai+ homeostasis activates glucose uptake and glycolysis in astrocytes. Here, we have examined whether a similar neurometabolic coupling could operate for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), also taken up by Na+-dependent transporters into astrocytes. Thus, we have compared the Nai+ response to GABA and glutamate in mouse astrocytes by microspectrofluorimetry. The Nai+ response to GABA consisted of a rapid rise of 4-6 mM followed by a plateau that did not, however, significantly activate the pump. Indeed, the GABA transporter-evoked Na+ influxes are transient in nature, almost totally shutting off within approximately 30 sec of GABA application. The metabolic consequences of the GABA-induced Nai+ response were evaluated by monitoring cellular ATP changes indirectly in single cells and measuring 2-deoxyglucose uptake in astrocyte populations. Both approaches showed that, whereas glutamate induced a robust metabolic response in astrocytes (decreased ATP levels and glucose uptake stimulation), GABA did not cause any measurable metabolic response, consistent with the Nai+ measurements. Results indicate that GABA does not couple inhibitory neuronal activity with glucose utilization, as does glutamate for excitatory neurotransmission, and suggest that GABA-mediated synaptic transmission does not contribute directly to brain imaging signals based on deoxyglucose.

  9. Flavonoid nutraceuticals and ionotropic receptors for the inhibitory neurotransmitter GABA.

    PubMed

    Johnston, Graham A R

    2015-10-01

    Flavonoids that are found in nutraceuticals have many and varied effects on the activation of ionotropic receptors for GABA, the major inhibitory neurotransmitter in our brains. They can act as positive or negative modulators enhancing or reducing the effect of GABA. They can act as allosteric agonists. They can act to modulate the action of other modulators. There is considerable evidence that these flavonoids are able to enter the brain to influence brain function. They may have a range of effects including relief of anxiety, improvement in cognition, acting as neuroprotectants and as sedatives. All of these effects are sought after in nutraceuticals. A number of studies have likened flavonoids to the widely prescribed benzodiazepines as 'a new family of benzodiazepine receptor ligands'. They are much more than that with many flavonoid actions on ionotropic GABA receptors being insensitive to the classic benzodiazepine antagonist flumazenil and thus independent of the classic benzodiazepine actions. It is time to consider flavonoids in their own right as important modulators of these vital receptors in brain function. Flavonoids are rarely consumed as a single flavonoid except as dietary supplements. The effects of mixtures of flavonoids and other modulators on GABAA receptors need to be more thoroughly investigated.

  10. GAD67-mediated GABA synthesis and signaling regulate inhibitory synaptic innervation in the visual cortex.

    PubMed

    Chattopadhyaya, Bidisha; Di Cristo, Graziella; Wu, Cai Zhi; Knott, Graham; Kuhlman, Sandra; Fu, Yu; Palmiter, Richard D; Huang, Z Josh

    2007-06-21

    The development of GABAergic inhibitory circuits is shaped by neural activity, but the underlying mechanisms are unclear. Here, we demonstrate a novel function of GABA in regulating GABAergic innervation in the adolescent brain, when GABA is mainly known as an inhibitory transmitter. Conditional knockdown of the rate-limiting synthetic enzyme GAD67 in basket interneurons in adolescent visual cortex resulted in cell autonomous deficits in axon branching, perisomatic synapse formation around pyramidal neurons, and complexity of the innervation fields; the same manipulation had little influence on the subsequent maintenance of perisomatic synapses. These effects of GABA deficiency were rescued by suppressing GABA reuptake and by GABA receptor agonists. Germline knockdown of GAD67 but not GAD65 showed similar deficits, suggesting a specific role of GAD67 in the maturation of perisomatic innervation. Since intracellular GABA levels are modulated by neuronal activity, our results implicate GAD67-mediated GABA synthesis in activity-dependent regulation of inhibitory innervation patterns.

  11. Selected Gamma Aminobutyric Acid (GABA) Esters may Provide Analgesia for Some Central Pain Conditions

    PubMed Central

    Goldberg, Joel S.

    2010-01-01

    Central pain is an enigmatic, intractable condition, related to destruction of thalamic areas, resulting in likely loss of inhibitory synaptic transmission mediated by GABA. It is proposed that treatment of central pain, a localized process, may be treated by GABA supplementation, like Parkinson’s disease and depression. At physiologic pH, GABA exists as a zwitterion that is poorly permeable to the blood brain barrier (BBB). Because the pH of the cerebral spinal fluid (CSF) is acidic relative to the plasma, ion trapping may allow a GABA ester prodrug to accumulate and be hydrolyzed within the CSF. Previous investigations with ester local anesthetics may be applicable to some GABA esters since they are weak bases, hydrolyzed by esterases and cross the BBB. Potential non-toxic GABA esters are discussed. Many GABA esters were investigated in the 1980s and it is hoped that this paper may spark renewed interest in their development. PMID:20703328

  12. GABA signaling promotes synapse elimination and axon pruning in developing cortical inhibitory interneurons.

    PubMed

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

    2012-01-04

    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.

  13. “Brain MR spectroscopy in autism spectrum disorder—the GABA excitatory/inhibitory imbalance theory revisited”

    PubMed Central

    Brix, Maiken K.; Ersland, Lars; Hugdahl, Kenneth; Grüner, Renate; Posserud, Maj-Britt; Hammar, Åsa; Craven, Alexander R.; Noeske, Ralph; Evans, C. John; Walker, Hanne B.; Midtvedt, Tore; Beyer, Mona K.

    2015-01-01

    Magnetic resonance spectroscopy (MRS) from voxels placed in the left anterior cingulate cortex (ACC) was measured from 14 boys with Autism Spectrum Disorder (ASD) and 24 gender and age-matched typically developing (TD) control group. Our main aims were to compare the concentration of γ-aminobutyric acid (GABA) between the two groups, and to investigate the relationship between brain metabolites and autism symptom severity in the ASD group. We did find a significant negative correlation in the ASD group between Autism Spectrum Screening Questionnaire (ASSQ) and GABA+/Cr, which may imply that severity of symptoms in ASD is associated with differences in the level of GABA in the brain, supporting the excitatory/inhibitory (E/I) imbalance theory. However we did not find a significant difference between the two groups in GABA levels. PMID:26157380

  14. GABA and neuroligin signaling: linking synaptic activity and adhesion in inhibitory synapse development

    PubMed Central

    Huang, Z. Josh; Scheiffele, Peter

    2013-01-01

    GABA-mediated synaptic inhibition is crucial in neural circuit operations. In mammalian brains, the development of inhibitory synapses and innervation patterns is often a prolonged postnatal process, regulated by neural activity. Emerging evidence indicates that GABA acts beyond inhibitory transmission and regulates inhibitory synapse development. Indeed, GABAA receptors not only function as chloride channels that regulate membrane voltage and conductance but also play structural roles in synapse maturation and stabilization. The link from GABAA receptors to post- and pre- synaptic adhesion is likely mediated, in part, by neuroligin-reurexin interactions, which are potent in promoting GABAergic synapse formation. Therefore, similar to glutamate signaling at excitatory synapse, GABA signaling may coordinate maturation of pre- and post- synaptic sites at inhibitory synapses. Defining the many steps from GABA signaling to receptor trafficking/stability and neuroligin function will provide further mechanistic insights into activity-dependent development and possibly plasticity of inhibitory synapses. PMID:18513949

  15. Detection of the inhibitory neurotransmitter GABA in macrophages by magnetic resonance spectroscopy.

    PubMed

    Stuckey, D J; Anthony, D C; Lowe, J P; Miller, J; Palm, W M; Styles, P; Perry, V H; Blamire, A M; Sibson, N R

    2005-08-01

    Macrophages are key components of the inflammatory response to tissue injury, but their activities can exacerbate neuropathology. High-resolution magnetic resonance spectroscopy was used to identify metabolite levels in perchloric acid extracts of cultured cells of the RAW 264.7 murine macrophage line under resting and lipopolysaccharide-activated conditions. Over 25 metabolites were identified including gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter not previously reported to be present in macrophages. The presence of GABA was also demonstrated in extracts of human peripheral blood monocyte-derived macrophages. This finding suggests that there may be communication between damaged central nervous system (CNS) tissue and recruited macrophages and resident microglia, which could help orchestrate the immune response. On activation, lactate, glutamine, glutamate, and taurine levels were elevated significantly, and GABA and alanine were reduced significantly. Strong resonances from glutathione, evident in the macrophage two-dimensional 1H spectrum, suggest that this may have potential as a noninvasive marker of macrophages recruited to the CNS, as it is only present at low levels in normal brain. Alternatively, a specific combination of spectroscopic changes, such as lactate, alanine, glutathione, and polyamines, may prove to be the most accurate means of detecting macrophage recruitment to the CNS.

  16. Inhibitory action of gamma-aminobutyric acid on the excitatory but not inhibitory innervation of the rat anococcygeus muscle.

    PubMed

    Hughes, P R; Morgan, P F; Stone, T W

    1982-12-01

    1 The effects of gamma-aminobutyric acid (GABA), ethylenediamine, 3-aminopropane sulphonic acid and (+/-)-baclofen have been examined on the responses to stimulation of the adrenergic excitatory and non-adrenergic non-cholinergic inhibitory innervation of the rat anococcygeus muscle in vitro. 2 GABA produced a dose-related depression of the contractile responses to field stimulation. Ethylenediamine and baclofen also depressed the contractile responses, though they were less potent than GABA. 3-Aminopropane sulphonic acid was almost inactive. The inhibitory action of GABA was not modified by phentolamine, propranolol or bicuculline methylbromide. 3 GABA did not affect the contractile responses of the anococcygeus muscle to noradrenaline, phenylephrine or carbachol in untreated muscles or those treated with 6-hydroxydopamine in vitro. 4 In preparations in which tone was raised by continuous perfusion with carbachol in the presence of phentolamine, field stimulation relaxed the muscle. GABA had no effect on this inhibitory response, and did not itself produce any relaxation. 5 It is concluded that GABA exerts a presynaptic inhibitory action on the excitatory adrenergic but not on the inhibitory innervation of the anococcygeus muscle, and that the GABA receptor involved exhibits properties of the previously described GABAB site.

  17. The GABA excitatory/inhibitory developmental sequence: a personal journey.

    PubMed

    Ben-Ari, Y

    2014-10-24

    The developing brain is talkative but its language is not that of the adult. Most if not all voltage and transmitter-gated ionic currents follow a developmental sequence and network-driven patterns differ in immature and adult brains. This is best illustrated in studies engaged almost three decades ago in which we observed elevated intracellular chloride (Cl(-))i levels and excitatory GABA early during development and a perinatal excitatory/inhibitory shift. This sequence is observed in a wide range of brain structures and animal species suggesting that it has been conserved throughout evolution. It is mediated primarily by a developmentally regulated expression of the NKCC1 and KCC2 chloride importer and exporter respectively. The GABAergic depolarization acts in synergy with N-methyl-d-aspartate (NMDA) receptor-mediated and voltage-gated calcium currents to enhance intracellular calcium exerting trophic effects on neuritic growth, migration and synapse formation. These sequences can be deviated in utero by genetic or environmental insults leading to a persistence of immature features in the adult brain. This "neuroarcheology" concept paves the way to novel therapeutic perspectives based on the use of drugs that block immature but not adult currents. This is illustrated notably with the return to immature high levels of chloride and excitatory actions of GABA observed in many pathological conditions. This is due to the fact that in the immature brain a down regulation of KCC2 and an up regulation of NKCC1 are seen. Here, I present a personal history of how an unexpected observation led to novel concepts in developmental neurobiology and putative treatments of autism and other developmental disorders. Being a personal account, this review is neither exhaustive nor provides an update of this topic with all the studies that have contributed to this evolution. We all rely on previous inventors to allow science to advance. Here, I present a personal summary of this

  18. GAD67-mediated GABA Synthesis and Signaling Regulate Inhibitory Synaptic Innervation in the Visual Cortex

    PubMed Central

    Chattopadhyaya, Bidisha; Di Cristo, Graziella; Wu, Cai Zhi; Knott, Graham; Kuhlman, Sandra; Fu, Yu; Palmiter, Richard D.; Huang, Z. Josh

    2007-01-01

    The development of GABAergic inhibitory circuits is shaped by neural activity, but the underlying mechanisms are unclear. we demonstrate a novel function of GABA in regulating GABAergic innervation in the adolescent brain, when GABA is mainly known as an inhibitory transmitter. Conditional knockdown of the rate-limiting synthetic enzyme GAD67 in basket interneurons in adolescent visual cortex resulted in cell autonomous deficits in axon branching, perisomatic synapse formation around pyramidal neurons, and complexity of the innervation fields; the same manipulation had little influence on the subsequent maintenance of perisomatic synapses. These effects of GABA deficiency were rescued by suppressing GABA re-uptake and by GABA receptor agonists. Germ-line knockdown of GAD67 but not GAD65 showed similar deficits, suggesting a specific role of GAD67 in the maturation of perisomatic innervation. Since intracellular GABA levels are modulated by neuronal activity, our results implicate GAD67-mediated GABA synthesis in activity-dependent regulation of inhibitory innervation patterns. PMID:17582330

  19. Homomeric RDL and heteromeric RDL/LCCH3 GABA receptors in the honeybee antennal lobes: two candidates for inhibitory transmission in olfactory processing.

    PubMed

    Dupuis, Julien Pierre; Bazelot, Michaël; Barbara, Guillaume Stéphane; Paute, Sandrine; Gauthier, Monique; Raymond-Delpech, Valérie

    2010-01-01

    gamma-Aminobutyric acid (GABA)-gated chloride channel receptors are abundant in the CNS, where their physiological role is to mediate fast inhibitory neurotransmission. In insects, this inhibitory transmission plays a crucial role in olfactory information processing. In an effort to understand the nature and properties of the ionotropic receptors involved in these processes in the honeybee Apis mellifera, we performed a pharmacological and molecular characterization of GABA-gated channels in the primary olfactory neuropile of the honeybee brain-the antennal lobe (AL)-using whole cell patch-clamp recordings coupled with single-cell RT-PCR. Application of GABA onto AL cells at -110 mV elicited fast inward currents, demonstrating the existence of ionotropic GABA-gated chloride channels. Molecular analysis of the GABA-responding cells revealed that both subunits RDL and LCCH3 were expressed out of the three orthologs of Drosophila melanogaster GABA-receptor subunits encoded within the honeybee genome (RDL, resistant to dieldrin; GRD, GABA/glycine-like receptor of Drosophila; LCCH3, ligand-gated chloride channel homologue 3), opening the door to possible homo- and/or heteromeric associations. The resulting receptors were activated by insect GABA-receptor agonists muscimol and CACA and blocked by antagonists fipronil, dieldrin, and picrotoxin, but not bicuculline, displaying a typical RDL-like pharmacology. Interestingly, increasing the intracellular calcium concentration potentiated GABA-elicited currents, suggesting a modulating effect of calcium on GABA receptors possibly through phosphorylation processes that remain to be determined. These results indicate that adult honeybee AL cells express typical RDL-like GABA receptors whose properties support a major role in synaptic inhibitory transmission during olfactory information processing.

  20. Cloning of the. gamma. -aminobutyric acid (GABA). rho. sub 1 cDNA: A GABA receptor subunit highly expressed in the retina

    SciTech Connect

    Cutting, G.R.; Lu, Luo; Kasch, L.M.; Montrose-Rafizadeh, C.; Antonarakis, S.E.; Guggino, W.B.; Kazazian, H.H. Jr. ); O'Hara, B.F.; Donovan, D.M.; Shimada, Shoichi ); Uhl, G.R. Johns Hopkins Univ. School of Medicine, Baltimore, MD )

    1991-04-01

    Type A {gamma}-aminobutyric acid (GABA{sub A}) receptors are a family of ligand-gated chloride channels that are the major inhibitory neurotransmitter receptors in the nervous system. Molecular cloning has revealed diversity in the subunits that compose this heterooligomeric receptor, but each previously elucidated subunit displays amino acid similarity in conserved structural elements. The authors have used these highly conserved regions to identify additional members of this family by using the polymerase chain reaction (PCR). One PCR product was used to isolate a full-length cDNA from a human retina cDNA library. The mature protein predicted from this cDNA sequence is 458 amino acids long and displays between 30 and 38% amino acid similarity to the previously identified GABA{sub A} subunits. This gene is expressed primarily in the retina but transcripts are also detected in the brain, lung, and thymus. Injection of Xenopus oocytes with RNA transcribed in vitro produces a GABA-responsive chloride conductance and expression of the cDNA in COS cells yields GABA-displaceable muscimol binding. These features are consistent with our identification of a GABA subunit, GABA {rho}{sub 1}, with prominent retinal expression that increases the diversity and tissue specificity of this ligand-gated ion-channel receptor family.

  1. GABA B receptor modulation of excitatory and inhibitory synaptic transmission onto rat CA3 hippocampal interneurons.

    PubMed

    Lei, Saobo; McBain, Chris J

    2003-01-15

    Hippocampal stratum radiatum inhibitory interneurons receive glutamatergic excitatory innervation via the recurrent collateral fibers of CA3 pyramidal neurons and GABAergic inhibition from other interneurons. We examined both presynaptic- and postsynaptic-GABA(B) receptor-mediated responses at both synapse types. Postsynaptic GABA(B) receptor-mediated responses were absent in recordings from young (P16-18) but present in recordings from older animals (> or =P30) suggesting developmental regulation. In young animals, the GABA(B) receptor agonist, baclofen, inhibited the amplitude of evoked EPSCs and IPSCs, an effect blocked by prior application of the selective antagonist CGP55845. Baclofen enhanced the paired-pulse ratio and coefficient of variation of evoked EPSCs and IPSCs, consistent with a presynaptic mechanism of regulation. In addition, baclofen reduced the frequency of miniature IPSCs but not mEPSCs. However, baclofen reduced the frequency of KCl-induced mEPSCs; an effect blocked by Cd(2+), implicating presynaptic voltage-gated Ca(2+) channels as a target for baclofen modulation. In contrast, although Cd(2+) prevented the KCl-induced increase in mIPSC frequency, it failed to block baclofen's reduction of mIPSC frequency. Whereas N- and P/Q-types of Ca(2+) channels contributed equally to GABA(B) receptor-mediated inhibition of EPSCs, more P/Q-type Ca(2+) channels were involved in GABA(B) receptor-mediated inhibition of IPSCs. Finally, baclofen blocked the frequency-dependent depression of EPSCs and IPSCs, but was less effective at blocking frequency-dependent facilitation of EPSCs. Our results demonstrate that presynaptic GABA(B) receptors are expressed on the terminals of both excitatory and inhibitory synapses onto CA3 interneurons and that their activation modulates essential components of the release process underlying transmission at these two synapse types.

  2. Neuronal gamma-aminobutyric acid (GABA) type A receptors undergo cognate ligand chaperoning in the endoplasmic reticulum by endogenous GABA

    PubMed Central

    Wang, Ping; Eshaq, Randa S.; Meshul, Charles K.; Moore, Cynthia; Hood, Rebecca L.; Leidenheimer, Nancy J.

    2015-01-01

    GABAA receptors mediate fast inhibitory neurotransmission in the brain. Dysfunction of these receptors is associated with various psychiatric/neurological disorders and drugs targeting this receptor are widely used therapeutic agents. Both the efficacy and plasticity of GABAA receptor-mediated neurotransmission depends on the number of surface GABAA receptors. An understudied aspect of receptor cell surface expression is the post-translational regulation of receptor biogenesis within the endoplasmic reticulum (ER). We have previously shown that exogenous GABA can act as a ligand chaperone of recombinant GABAA receptors in the early secretory pathway leading us to now investigate whether endogenous GABA facilitates the biogenesis of GABAA receptors in primary cerebral cortical cultures. In immunofluorescence labeling experiments, we have determined that neurons expressing surface GABAA receptors contain both GABA and its degradative enzyme GABA transaminase (GABA-T). Treatment of neurons with GABA-T inhibitors, a treatment known to increase intracellular GABA levels, decreases the interaction of the receptor with the ER quality control protein calnexin, concomittantly increasing receptor forward-trafficking and plasma membrane insertion. The effect of GABA-T inhibition on the receptor/calnexin interaction is not due to the activation of surface GABAA or GABAB receptors. Consistent with our hypothesis that GABA acts as a cognate ligand chaperone in the ER, immunogold-labeling of rodent brain slices reveals the presence of GABA within the rough ER. The density of this labeling is similar to that present in mitochondria, the organelle in which GABA is degraded. Lastly, the effect of GABA-T inhibition on the receptor/calnexin interaction was prevented by pretreatment with a GABA transporter inhibitor. Together, these data indicate that endogenous GABA acts in the rough ER as a cognate ligand chaperone to facilitate the biogenesis of neuronal GABAA receptors. PMID

  3. The GABA excitatory/inhibitory shift in brain maturation and neurological disorders.

    PubMed

    Ben-Ari, Yehezkel; Khalilov, Ilgam; Kahle, Kristopher T; Cherubini, Enrico

    2012-10-01

    Ionic currents and the network-driven patterns they generate differ in immature and adult neurons: The developing brain is not a "small adult brain." One of the most investigated examples is the developmentally regulated shift of actions of the transmitter GABA that inhibit adult neurons but excite immature ones because of an initially higher intracellular chloride concentration [Cl(-)](i), leading to depolarizing and often excitatory actions of GABA instead of hyperpolarizing and inhibitory actions. The levels of [Cl(-)](i) are also highly labile, being readily altered transiently or persistently by enhanced episodes of activity in relation to synaptic plasticity or a variety of pathological conditions, including seizures and brain insults. Among the plethora of channels, transporters, and other devices involved in controlling [Cl(-)](i), two have emerged as playing a particularly important role: the chloride importer NKCC1 and the chloride exporter KCC2. Here, the authors stress the importance of determining how [Cl(-)](i) is dynamically regulated and how this affects brain operation in health and disease. In a clinical perspective, agents that control [Cl(-)](i) and reinstate inhibitory actions of GABA open novel therapeutic perspectives in many neurological disorders, including infantile epilepsies, autism spectrum disorders, and other developmental disorders.

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

    PubMed Central

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

    2015-01-01

    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. PMID:25620912

  5. 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.

  6. Regulation of GABA-modulin phosphorylation and GABA receptor binding by excitatory amino acids

    SciTech Connect

    Vaccarino, F.; Guidotti, A.

    1987-05-01

    Primary cultures of cerebellar granule cells phosphorylate numerous proteins including GABA-modulin (GM), which is a putative allosteric modulator of GABA receptors. Cell depolarization and treatment with dicarboxylic excitatory amino acids, which activate PI turnover, Ca/sup 2 +/ influx and guanylate cyclase in granule cells increase the phosphorylation of specific proteins. To determine GM phosphorylation by endogenous protein kinases in living granule cell cultures, GM was isolated by immunoprecipitation and reverse-phase HPLC. High K/sup +/, veratridine, glutamate and NMDA treatment stimulated GM phosphorylation over 2-fold. This increase was abolished by the absence of extracellular Ca/sup 2 +/ and was antagonized by Mg/sup 2 +/ ions and by AVP. The excitatory amino acid action was mimicked by phorbol esters but not by forskolin or by cGMP, and thus may be mediated by an activation of protein kinase C (PKC). Moreover, excitatory amino acids increase /sup 3/H-labelled phorbol ester binding sites in granule cell membrane. The same cultures, treated with glutamate or kainate, showed a 50-fold greater efficacy of muscimol for the stimulation of benzodiazepine (BZ) binding. These data-suggest that excitatory amino acid stimulation of neurons triggers PKC translocation and the activated enzyme phosphorylates GM. The extent of GM phosphorylation may regulate the coupling between GABA and BZ binding sites.

  7. The GABAergic control of gonadotropin-releasing hormone secretion in male rats during sexual maturation involves effects on hypothalamic excitatory and inhibitory amino acid systems.

    PubMed

    Feleder, C; Jarry, H; Leonhardt, S; Wuttke, W; Moguilevsky, J A

    1996-10-01

    In order to evaluate the possible participation of the hypothalamic excitatory and inhibitory amino acid neurotransmitter systems in the GnRH release response to GABAergic drugs, hypothalami (preoptic and mediobasal area) of immature (26 days of age) and adult male rats were perifused with GABA-A and -B agonists and antagonists. GnRH and amino acid neurotransmitter concentrations (glutamate, taurine, GABA) were measured in perfusate samples collected every 15 min during 150 min. In immature rats, muscimol and baclofen (GABA-A and GABA-B agonists, respectively) increased GnRH, glutamate and GABA release and decreased taurine output, while in adults these agonists showed opposite effects on GnRH and glutamate release, and increased GABA and taurine output. On the other hand, in immature rats bicuculline and phaclofen (GABA-A and GABA-B antagonists, respectively) decreased GnRH, glutamate and GABA release, increasing taurine outflow. In adult animals, these antagonists enhanced GnRH and glutamate release, decreasing taurine and GABA outflow. These results indicate that GABA stimulates GnRH release in immature male rats and confirm the inhibitory role of this amino acid neurotransmitter in adult animals. This effect might be associated, at least partially, with the modifications observed in the excitatory and inhibitory amino acid release. On the other hand, in immature rats, stimulation of GABA-A and GABA-B receptors increased GABA release. Although ultrastructural studies have not produced any evidence of GABA-GABA neurointeractions, our results suggest the existence of a positive feedback mechanism of GABA autoregulation active during the prepubertal stage. Participation of this mechanism in the onset of puberty cannot be discarded.

  8. Activation of NPY type 5 receptors induces a long-lasting increase in spontaneous GABA release from cerebellar inhibitory interneurons

    PubMed Central

    Dubois, C. J.; Ramamoorthy, P.; Whim, M. D.

    2012-01-01

    Neuropeptide Y (NPY), a widely distributed neuropeptide in the central nervous system, can transiently suppress inhibitory synaptic transmission and alter membrane excitability via Y2 and Y1 receptors (Y2rs and Y1rs), respectively. Although many GABAergic neurons express Y5rs, the functional role of these receptors in inhibitory neurons is not known. Here, we investigated whether activation of Y5rs can modulate inhibitory transmission in cerebellar slices. Unexpectedly, application of NPY triggered a long-lasting increase in the frequency of miniature inhibitory postsynaptic currents in stellate cells. NPY also induced a sustained increase in spontaneous GABA release in cultured cerebellar neurons. When cerebellar cultures were examined for Y5r immunoreactivity, the staining colocalized with that of VGAT, a presynaptic marker for GABAergic cells, suggesting that Y5rs are located in the presynaptic terminals of inhibitory neurons. RT-PCR experiments confirmed the presence of Y5r mRNA in the cerebellum. The NPY-induced potentiation of GABA release was blocked by Y5r antagonists and mimicked by application of a selective peptide agonist for Y5r. Thus Y5r activation is necessary and sufficient to trigger an increase in GABA release. Finally, the potentiation of inhibitory transmission could not be reversed by a Y5r antagonist once it was initiated, consistent with the development of a long-term potentiation. These results indicate that activation of presynaptic Y5rs induces a sustained increase in spontaneous GABA release from inhibitory neurons in contrast to the transient suppression of inhibitory transmission that is characteristic of Y1r and Y2r activation. Our findings thus reveal a novel role of presynaptic Y5rs in inhibitory interneurons in regulating GABA release and suggest that these receptors could play a role in shaping neuronal network activity in the cerebellum. PMID:22190627

  9. Effect of centrally acting drugs on the uptake of γ-aminobutyric acid (GABA) by slices of rat cerebral cortex

    PubMed Central

    Harris, M.; Hopkin, Judy M.; Neal, M. J.

    1973-01-01

    1. The effects of centrally acting drugs on the uptake of 3H-γ-aminobutyric acid (GABA) by slices of rat cerebral cortex have been studied. 2. Many centrally acting drugs at concentrations of 0·1-1·0 mM significantly inhibited the uptake of 3H-GABA by cortical slices, but the only classes of drugs in which all members consistently produced inhibition of uptake were the phenothiazines, tricyclic antidepressants, and butyrophenones. 3. The receptor blocking drugs; phentolamine, propranolol, thymoxamine, mepyramine, and diphenhydramine at concentrations of 0·5-1 mM also significantly reduced the uptake of 3H-GABA. However, atropine, hexamethonium and (+)-tubocurarine had little effect on the uptake of 3H-GABA by cortical slices. 4. Centrally acting drugs, which did not significantly inhibit 3H-GABA uptake, included barbiturates, local anaesthetics, hallucinogens, monoamine oxidase inhibitors, anticonvulsants, and convulsants (except picrotoxin). 5. Chlorpromazine, prochlorperazine, L-2,4,diaminobutyric acid, desmethylimipramine, and iprindole inhibited the uptake of 3H-GABA by 50% (IC50) at concentrations of 30-100 μM. The most potent inhibitor of 3H-GABA uptake was p-chloromercuriphenylsulphonate (IC50 = 18 μM). 6. With the exception of L-2,4,diaminobutyric acid, an outstanding characteristic of these drugs was their complete lack of specificity. Thus at the IC50 for GABA, p-chloromercuriphenylsulphonate, chlorpromazine, prochlorperazine, iprindole, desmethylimipramine, apomorphine and diphenylhydramine also inhibited the uptake of radioactive glycine, alanine, noradrenaline, and 5-hydroxytryptamine. The uptake of the latter two compounds was often inhibited to a greater extent than GABA, glycine and alanine. 7. Kinetic analysis indicated that the inhibition of 3H-GABA by p-chloromercuriphenylsulphonate, chlorpromazine, and desmethylimipramine was noncompetitive. L-2,4,Diaminobutyric acid reduced the uptake of 3H-GABA by a `mixed' type of inhibition. 8. The

  10. Classification of inhibitory amino acid receptors in the mammalian nervous system.

    PubMed

    Simmonds, M A

    1986-01-01

    Electrophysiological and pharmacological evidence is summarized for the existence of an inhibitory receptor system operated by glycine and another two separate systems operated by gamma-aminobutyric acid (GABA) through GABA-A and GABA-B receptors, respectively. Claims for subclasses of GABA-A receptor are critically reviewed and found not-proven. A quantitative pharmacological profile of the GABA-A receptor and associated regulatory sites for picrotoxin, barbiturates and benzodiazepines on the dorsal funiculus of the rat cuneate nucleus is described. When compared with this profile and the pharmacological properties of the glycine receptor complex, the effects of taurine cannot be entirely explained by actions on these two receptor systems.

  11. Suppression of γ-aminobutyric acid (GABA) transaminases induces prominent GABA accumulation, dwarfism and infertility in the tomato (Solanum lycopersicum L.).

    PubMed

    Koike, Satoshi; Matsukura, Chiaki; Takayama, Mariko; Asamizu, Erika; Ezura, Hiroshi

    2013-05-01

    Tomatoes accumulate γ-aminobutyric acid (GABA) at high levels in the immature fruits. GABA is rapidly converted to succinate during fruit ripening through the activities of GABA transaminase (GABA-T) and succinate semialdehyde dehydrogenase (SSADH). Although three genes encoding GABA-T and both pyruvate- and α-ketoglutarate-dependent GABA-T activities have been detected in tomato fruits, the mechanism underlying the GABA-T-mediated conversion of GABA has not been fully understood. In this work, we conducted loss-of-function analyses utilizing RNA interference (RNAi) transgenic plants with suppressed pyruvate- and glyoxylate-dependent GABA-T gene expression to clarify which GABA-T isoforms are essential for its function. The RNAi plants with suppressed SlGABA-T gene expression, particularly SlGABA-T1, showed severe dwarfism and infertility. SlGABA-T1 expression was inversely associated with GABA levels in the fruit at the red ripe stage. The GABA contents in 35S::SlGABA-T1(RNAi) lines were 1.3-2.0 times and 6.8-9.2 times higher in mature green and red ripe fruits, respectively, than the contents in wild-type fruits. In addition, SlGABA-T1 expression was strongly suppressed in the GABA-accumulating lines. These results indicate that pyruvate- and glyoxylate-dependent GABA-T is the essential isoform for GABA metabolism in tomato plants and that GABA-T1 primarily contributes to GABA reduction in the ripening fruits.

  12. Bacterial endotoxin inhibits LHRH secretion following the increased release of hypothalamic GABA levels. Different effects on amino acid neurotransmitter release.

    PubMed

    Feleder, C; Refojo, D; Jarry, H; Wuttke, W; Moguilevsky, J A

    1996-01-01

    Immune system disorders are often accompanied by alterations in the reproductive axis. The bacterial endotoxin (lipopolysaccharide, LPS) has inflammatory effects and activates cytokine release in the pituitary and hypothalamus. LPS inhibition of luteinizing-hormone-releasing hormone (LHRH) release at the hypothalamic level appears to be associated with modifications in the inhibitory GABAergic neurotransmitter system. Then, knowing that gamma-aminobutyric acid (GABA) mediates other neurotransmitter effects in the central nervous system, the possibility arises that this amino acid might mediate the effect of LPS on LHRH release by modifying amino acid neurotransmitter release at the hypothalamic level. Therefore, the present study was designed to investigate a possible mediatory function of the GABAergic system in the LPS-induced inhibition of LHRH secretion. To this end, the modifications in the excitatory (glutamate, Glu) and inhibitory (taurine, Tau, and GABA) amino acid neurotransmitter release after the application of GABA-A and GABA-B antagonists, respectively, were studied and the effects of LPS on their release determined. Male rats were decapitated at 9.00 h, and the preoptic/mediobasal hypothalamic area (POA/MBH) was dissected and superfused with Earle's balanced salt solution. Superfusate fractions were collected at 15-min intervals after a 60-min stabilization superfusion period. LPS (100 ng/ml) was then added to the superfusion medium over 1 h in three different experimental designs: (1) LPS only (2) LPS simultaneously with bicuculline (GABA-A antagonist) or with phaclofen (GABA-B antagonist), and (3) LPS and subsequently bicuculline or phaclofen, performed in different experiments. This was followed by a wash-out period. The POA/MBH fragments were then subjected to a 56-mM K+ stimulus. Control POA/MBH fragments were continuously superfused with Earle's solution. As expected, LHRH release was significantly reduced (p < 0.05) during and following

  13. Unsaturated phosphinic analogues of gamma-aminobutyric acid as GABA(C) receptor antagonists.

    PubMed

    Chebib, M; Vandenberg, R J; Froestl, W; Johnston, G A

    1997-06-25

    The phosphinic and methylphosphinic analogues of gamma-aminobutyric acid (GABA) are potent GABA(C) receptor antagonists but are even more potent as GABA(B) receptor agonists. Conformationally restricted unsaturated phosphinic and methylphosphinic analogues of GABA and some potent GABA(B) receptor phosphonoamino acid antagonists were tested on GABA(C) receptors in Xenopus oocytes expressing human retinal rho1 mRNA. 3-Aminopropyl-n-butyl-phosphinic acid (CGP36742), an orally active GABA(B) receptor antagonist, was found to be a moderately potent GABA(C) receptor antagonist (IC50 = 62 microM). The unsaturated methylphosphinic and phosphinic analogues of GABA were competitive antagonists of the GABA(C) receptors, the order of potency being [(E)-3-aminopropen-1-yl]methylphosphinic acid (CGP44530, IC50 = 5.53 microM) > [(E)-3-aminopropen-1-yl]phosphinic acid (CGP38593, IC50 = 7.68 microM) > [(Z)-3-aminopropen-1-yl]methylphosphinic acid (CGP70523, IC50 = 38.94 microM) > [(Z)-3-aminopropen-1-yl]phosphinic acid (CGP70522, IC50 > 100 microM). This order of potency differs from that reported for these compounds as GABA(B) receptor agonists, where the phosphinic acids are more potent than the corresponding methylphosphinic acids.

  14. Substance P receptor expression by inhibitory interneurons of the rat hippocampus: enhanced detection using improved immunocytochemical methods for the preservation and colocalization of GABA and other neuronal markers.

    PubMed

    Sloviter, R S; Ali-Akbarian, L; Horvath, K D; Menkens, K A

    2001-02-12

    Two unresolved issues regarding the identification and characterization of hippocampal interneurons were addressed in this study. One issue was the longstanding inability to detect gamma-aminobutyric acid (GABA) in the somata of several hippocampal interneuron subpopulations, which has prevented the unequivocal identification of all hippocampal interneurons as GABA neurons. The second issue was related to the identification of the hippocampal interneurons that constitutively express substance P (neurokinin-1) receptors (SPRs). The recent development of neurotoxins that specifically target SPR-expressing cells suggests that it may be possible to destroy hippocampal inhibitory interneurons selectively for experimental purposes. Although SPRs are apparently expressed in the hippocampus only by interneurons, colocalization studies have found that most interneurons of several subtypes and hippocampal subregions appear SPR-negative. Thus, the identities and locations of the inhibitory interneurons that are potential targets of an SPR-directed neurotoxin remain in doubt. Using newly developed methods designed to copreserve and colocalize GABA and polypeptide immunoreactivities with increased sensitivity, the authors report that virtually all hippocampal interneuron somata that are immunoreactive for parvalbumin (PV), calbindin, calretinin, somatostatin (SS), neuropeptide Y, cholecystokinin, and vasoactive intestinal peptide exhibited clearly detectable, somal, GABA-like immunoreactivity (LI). Hippocampal SPR-LI was detected only on the somata and dendrites of GABA-immunopositive interneurons. All glutamate receptor subunit 2-immunoreactive principal cells, including dentate granule cells, hilar mossy cells, and hippocampal pyramidal cells, were devoid of detectable SPR-LI, even after prolonged electrical stimulation of the perforant pathway that induced the expression of other neuronal proteins in principal cells. Thus, hippocampal interneurons of all subtypes and

  15. 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…

  16. The Timing of the Excitatory-to-Inhibitory GABA Switch Is Regulated by the Oxytocin Receptor via KCC2

    PubMed Central

    Leonzino, Marianna; Busnelli, Marta; Antonucci, Flavia; Verderio, Claudia; Mazzanti, Michele; Chini, Bice

    2016-01-01

    Summary Oxytocin and its receptor (Oxtr) play a crucial role in the postnatal transition of neuronal GABA neurotransmission from excitatory to inhibitory, a developmental process known as the GABA switch. Using hippocampal neurons from Oxtr-null mice, we show that (1) Oxtr is necessary for the correct timing of the GABA switch by upregulating activity of the chloride cotransporter KCC2, (2) Oxtr, in a very early and narrow time window, directly modulates the functional activity of KCC2 by promoting its phosphorylation and insertion/stabilization at the neuronal surface, and (3) in the absence of Oxtr, electrophysiological alterations are recorded in mature neurons, a finding consistent with a reduced level of KCC2 and increased susceptibility to seizures observed in adult Oxtr-null mice. These data identify KCC2 as a key target of oxytocin in postnatal events that may be linked to pathogenesis of neurodevelopmental disorders. PMID:27052180

  17. Synthesis and evaluation of novel heteroaromatic substrates of GABA aminotransferase

    PubMed Central

    Hawker, Dustin D.; Silverman, Richard B.

    2012-01-01

    Two principal neurotransmitters are involved in the regulation of mammalian neuronal activity, namely, γ-aminobutyric acid (GABA), an inhibitory neurotransmitter, and L-glutamic acid, an excitatory neurotransmitter. Low GABA levels in the brain have been implicated in epilepsy and several other neurological diseases. Because of GABA’s poor ability to cross the blood-brain barrier (BBB), a successful strategy to raise brain GABA concentrations is the use of a compound that does cross the BBB and inhibits or inactivates GABA aminotransferase (GABA-AT), the enzyme responsible for GABA catabolism. Vigabatrin, a mechanism-based inactivator of GABA-AT, is currently a successful therapeutic for epilepsy, but has harmful side effects, leaving a need for improved GABA-AT inactivators. Here, we report the synthesis and evaluation of a series of heteroaromatic GABA analogues as substrates of GABA-AT, which will be used as the basis for the design of novel enzyme inactivators. PMID:22944334

  18. Release and effect of gamma-aminobutyric acid (GABA) on rat pineal melatonin production in vitro.

    PubMed

    Rosenstein, R E; Chuluyan, H E; Pereyra, E N; Cardinali, D P

    1989-06-01

    1. 3H-gamma-Aminobutyric acid (GABA) release elicited by a depolarizing K+ stimulus or by noradrenergic transmitter was examined in rat pineals in vitro. 2. The release of 3H-GABA was detectable at a 20 mM K+ concentration in medium and increased steadily up to 80 mM K+. 3. In a Ca2+-free medium 3H-GABA release elicited by 30 mM K+, but not that elicited by 50 mM K+, became blunted. 4. Norepinephrine (NE; 10(-6)-10(-4) M) stimulated 3H-GABA release from rat pineal explants in a dose-dependent manner. 5. The activity of 10(-5) M NE on pineal GABA release was suppressed by equimolecular amounts of prazosin or phentolamine (alpha 1- and alpha 1/alpha 2-adrenoceptor blockers, respectively) and was unaffected by propranolol (beta-adrenoceptor blocker). 6. The alpha 1-adrenoceptor agonist phenylephrine (10(-7)-10(-5) M) and the beta-adrenoceptor agonist isoproterenol (10(-5) M) mimicked the GABA releasing activity of NE, while 10(-7) M isoproterenol failed to affect it; the alpha 2-adrenoceptor agonist clonidine (10(-7)-10(-5) M) did not modify 3H-GABA release. 7. The addition of 10(-4) M GABA or of the GABA transaminase inhibitor gamma-acetylenic GABA or aminooxyacetic acid inhibited the melatonin content and/or release to the medium in rat pineal organotypic cultures. 8. GABA at concentrations of 10(-5) M or greater partially inhibited the NE-induced increase in melatonin production by pineal explants. 9. The depressant effect of GABA on melatonin production was inhibited by the GABA type A receptor antagonist bicuculline; bicuculline alone increased the pineal melatonin content. Baclofen, a GABA type B receptor agonist, did not affect the pineal melatonin content or release. 10. The decrease in serotonin (5-HT) content of rat pineal explants brought about by NE was not modified by GABA; GABA by itself increased 5-HT levels. 11. These results indicate that (a) GABA is released from rat pineals by a depolarizing stimulus of K+ through a mechanism which is partially Ca2

  19. p-Coumaric acid activates the GABA-A receptor in vitro and is orally anxiolytic in vivo.

    PubMed

    Scheepens, Arjan; Bisson, Jean-Francois; Skinner, Margot

    2014-02-01

    The increasing prevalence and social burden of subclinical anxiety in the western world represents a significant psychosocial and financial cost. Consumers are favouring a more natural and nonpharmacological approach for alleviating the effects of everyday stress and anxiety. The gamma-aminobutyric acid (GABA) receptor is the primary mediator of central inhibitory neurotransmission, and GABA-receptor agonists are well known to convey anxiolytic effects. Using an in vitro screening approach to identify naturally occurring phytochemical GABA agonists, we discovered the plant secondary metabolite p-coumaric acid to have significant GABAergic activity, an effect that could be blocked by co-administration of the specific GABA-receptor antagonist, picrotoxin. Oral administration of p-coumaric acid to rodents induced a significant anxiolytic effect in vivo as measured using the elevated plus paradigm, in line with the effects of oral diazepam. Given that p-coumaric acid is reasonably well absorbed following oral consumption in man and is relatively nontoxic, it may be suitable for the formulation of a safe and effective anxiolytic functional food.

  20. 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

  1. Relaxation and immunity enhancement effects of gamma-aminobutyric acid (GABA) administration in humans.

    PubMed

    Abdou, Adham M; Higashiguchi, S; Horie, K; Kim, Mujo; Hatta, H; Yokogoshi, H

    2006-01-01

    The effect of orally administrated gamma-aminobutyric acid (GABA) on relaxation and immunity during stress has been investigated in humans. Two studies were conducted. The first evaluated the effect of GABA intake by 13 subjects on their brain waves. Electroencephalograms (EEG) were obtained after 3 tests on each volunteer as follows: intake only water, GABA, or L-theanine. After 60 minutes of administration, GABA significantly increases alpha waves and decreases beta waves compared to water or L-theanine. These findings denote that GABA not only induces relaxation but also reduces anxiety. The second study was conducted to see the role of relaxant and anxiolytic effects of GABA intake on immunity in stressed volunteers. Eight acrophobic subjects were divided into 2 groups (placebo and GABA). All subjects were crossing a suspended bridge as a stressful stimulus. Immunoglobulin A (IgA) levels in their saliva were monitored during bridge crossing. Placebo group showed marked decrease of their IgA levels, while GABA group showed significantly higher levels. In conclusion, GABA could work effectively as a natural relaxant and its effects could be seen within 1 hour of its administration to induce relaxation and diminish anxiety. Moreover, GABA administration could enhance immunity under stress conditions.

  2. Unsaturated Analogues of the Neurotransmitter GABA: trans-4-Aminocrotonic, cis-4-Aminocrotonic and 4-Aminotetrolic Acids.

    PubMed

    Johnston, Graham A R

    2016-03-01

    Analogues of the neurotransmitter GABA containing unsaturated bonds are restricted in the conformations they can attain. This review traces three such analogues from their synthesis to their use as neurochemicals. trans-4-Aminocrotonic acid was the first conformationally restricted analogue to be extensively studied. It acts like GABA across a range of macromolecules from receptors to transporters. It acts similarly to GABA on ionotropic receptors. cis-4-Aminocrotonic acid selectively activates bicuculline-insensitive GABAC receptors. 4-Aminotetrolic acid, containing a triple bond, activates bicuculline-sensitive GABAA receptors. These findings indicate that GABA activates GABAA receptors in extended conformations and GABAC receptors in folded conformations. These and related analogues are important for the molecular modelling of ionotropic GABA receptors and to the development of new agents acting selectively on these receptors.

  3. Midbrain dopamine neurons sustain inhibitory transmission using plasma membrane uptake of GABA, not synthesis

    PubMed Central

    Tritsch, Nicolas X; Oh, Won-Jong; Gu, Chenghua; Sabatini, Bernardo L

    2014-01-01

    Synaptic transmission between midbrain dopamine neurons and target neurons in the striatum is essential for the selection and reinforcement of movements. Recent evidence indicates that nigrostriatal dopamine neurons inhibit striatal projection neurons by releasing a neurotransmitter that activates GABAA receptors. Here, we demonstrate that this phenomenon extends to mesolimbic afferents, and confirm that the released neurotransmitter is GABA. However, the GABA synthetic enzymes GAD65 and GAD67 are not detected in midbrain dopamine neurons. Instead, these cells express the membrane GABA transporters mGAT1 (Slc6a1) and mGAT4 (Slc6a11) and inhibition of these transporters prevents GABA co-release. These findings therefore indicate that GABA co-release is a general feature of midbrain dopaminergic neurons that relies on GABA uptake from the extracellular milieu as opposed to de novo synthesis. This atypical mechanism may confer dopaminergic neurons the flexibility to differentially control GABAergic transmission in a target-dependent manner across their extensive axonal arbors. DOI: http://dx.doi.org/10.7554/eLife.01936.001 PMID:24843012

  4. Basic aspects of GABA-transmission in alcoholism, with particular reference to GABA-transaminase.

    PubMed

    Sherif, F M; Tawati, A M; Ahmed, S S; Sharif, S I

    1997-02-01

    Neuronal dysfunction is the neurobiological basis for alcoholic behaviour, and ethanol craving seems related to hypofunction of the GABA-ergic activity. Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system (CNS). In several studies, GABA has been shown to be an important target of ethanol in the CNS, partly, as a consequence of damage to membrane-bound enzymes and receptors. GABA is involved in mediating pre- and post-synaptic inhibition of neuronal activity. It is speculated that the initial excitatory effects of ethanol may be due to inhibition of GABA-ergic activity whereas the sedative effects of the higher doses may be mediated by the activation of this inhibitory system. In the CNS, GABA is synthesised from glutamic acid by the enzyme glutamate decarboxylase (GAD) and catabolized into succinic semialdehyde by the enzyme GABA-transaminase (GABA-T), which are pyridoxal phosphate (PLP) dependent enzymes. Platelet GABA-T was characterized as being similar to central GABA-T. Inhibition of GABA-T with certain potent and selective compounds markedly increases the levels of brain GABA. Experimentally, acute ethanol treatment does not alter GABA-T activity whereas chronic treatment produces an increase in the activity, though, with some reservations since a bimodal effect has been found in chronically ethanol-treated rats. Thus, as it will be discussed below, it may be suggested that GABA-T inhibitors (e.g. vigabatrin) could have a potential role in the treatment of alcoholism and in some of the problems of ethanol withdrawal and of other drugs of abuse. Related studies on metabolism and concentrations of GABA are also promising and show a greater increase in our understanding of the aetiology and treatment of ethanol dependence and withdrawal. In general, this article also reviews both the animal and clinical observations in the field of alcoholism with regard to the GABA system.

  5. A functional role for both γ-aminobutyric acid (GABA) transporter-1 and GABA transporter-3 in the modulation of extracellular GABA and GABAergic tonic conductances in the rat hippocampus

    PubMed Central

    Kersanté, Flavie; Rowley, Samuel C S; Pavlov, Ivan; Gutièrrez-Mecinas, María; Semyanov, Alexey; Reul, Johannes M H M; Walker, Matthew C; Linthorst, Astrid C E

    2013-01-01

    Tonic γ-aminobutyric acid (GABA)A receptor-mediated signalling controls neuronal network excitability in the hippocampus. Although the extracellular concentration of GABA (e[GABA]) is critical in determining tonic conductances, knowledge on how e[GABA] is regulated by different GABA transporters (GATs) in vivo is limited. Therefore, we studied the role of GATs in the regulation of hippocampal e[GABA] using in vivo microdialysis in freely moving rats. Here we show that GAT-1, which is predominantly presynaptically located, is the major GABA transporter under baseline, quiescent conditions. Furthermore, a significant contribution of GAT-3 in regulating e[GABA] was revealed by administration of the GAT-3 inhibitor SNAP-5114 during simultaneous blockade of GAT-1 by NNC-711. Thus, the GABA transporting activity of GAT-3 (the expression of which is confined to astrocytes) is apparent under conditions in which GAT-1 is blocked. However, sustained neuronal activation by K+-induced depolarization caused a profound spillover of GABA into the extrasynaptic space and this increase in e[GABA] was significantly potentiated by sole blockade of GAT-3 (i.e. even when uptake of GAT-1 is intact). Furthermore, experiments using tetrodotoxin to block action potentials revealed that GAT-3 regulates extrasynaptic GABA levels from action potential-independent sources when GAT-1 is blocked. Importantly, changes in e[GABA] resulting from both GAT-1 and GAT-3 inhibition directly precipitate changes in tonic conductances in dentate granule cells as measured by whole-cell patch-clamp recording. Thus, astrocytic GAT-3 contributes to the regulation of e[GABA] in the hippocampus in vivo and may play an important role in controlling the excitability of hippocampal cells when network activity is increased. PMID:23381899

  6. Attenuation of γ-aminobutyric acid (GABA) transaminase activity contributes to GABA increase in the cerebral cortex of mice exposed to β-cypermethrin.

    PubMed

    Han, Y; Cao, D; Li, X; Zhang, R; Yu, F; Ren, Y; An, L

    2014-03-01

    The current study investigated the γ-aminobutyric acid (GABA) levels and GABA metabolic enzymes (GABA transaminase (GABA(T)) and glutamate decarboxylase (GAD)) activities at 2 and 4 h after treatment, using a high-performance liquid chromatography with ultraviolet detectors and colorimetric assay, in the cerebral cortex of mice treated with 20, 40 or 80 mg/kg β-cypermethrin by a single oral gavage, with corn oil as vehicle control. In addition, GABA protein (4 h after treatment), GABA(T) protein (2 h after treatment) and GABA receptors messenger RNA (mRNA) expression were detected by immunohistochemistry, Western blot and real-time quantitative reverse transcriptase polymerase chain reaction, respectively. β-Cypermethrin (80 mg/kg) significantly increased GABA levels in the cerebral cortex of mice, at both 2 and 4 h after treatment, compared with the control. Also, GABA immunohistochemistry results suggested that the number of positive granules was increased in the cerebral cortex of mice 4 h after exposure to 80 mg/kg β-cypermethrin when compared with the control. Furthermore, the results also showed that GABA(T) activity detected was significantly decreased in the cerebral cortex of mice 2 h after β-cypermethrin administration (40 or 80 mg/kg). No significant changes were found in GAD activity, or the expression of GABA(T) protein and GABAB receptors mRNA, in the cerebral cortex of mice, except that 80 mg/kg β-cypermethrin caused a significant decrease, compared with the vehicle control, in GABAA receptors mRNA expression 4 h after administration. These results suggested that attenuated GABA(T) activity induced by β-cypermethrin contributed to increased GABA levels in the mouse brain. The downregulated GABAA receptors mRNA expression is most likely a downstream event.

  7. In vivo blockade of thalamic GABA(B) receptors increases excitatory amino-acid levels.

    PubMed

    Nyitrai, G; Emri, Z; Crunelli, V; Kékesi, K A; Dobolyi, A; Juhász, G

    1996-12-30

    The effect of intrathalamic application of GABA(B) receptor antagonists on the basal excitatory amino-acid levels was studied using microdialysis probes implanted in the dorsal lateral geniculate nucleus and in the ventrobasal complex. In both nuclei, continuous perfusion of the GABA(B) receptor antagonist 3-aminopropyl-(diethoxymethyl)-phosphinic acid (CGP 35348) produced an increase in the extracellular concentration of aspartate and (to a lesser extent) glutamate, but no change was observed in the level of taurine, the main amino acid involved in the regulation of brain osmolarity processes. In contrast, 3-amino-2-hydroxy-2-(4-chlorophenyl)-propanesulphonic acid (2-hydroxy-saclofen), another GABA(B) receptor antagonist, failed to affect the extracellular concentration of aspartate, glutamate and taurine. Thus, the basal level of excitatory amino acids in the thalamus in vivo is under the control of CGP 35348-sensitive GABA(B) receptors.

  8. 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.

  9. Excitatory action of gamma-aminobutyric acid (GABA) on crustacean neurosecretory cells.

    PubMed

    García, U; Onetti, C; Valdiosera, R; Aréchiga, H

    1994-02-01

    1. Intracellular and voltage-clamp recordings were obtained from a selected population of neurosecretory (ns) cells in the X organ of the crayfish isolated eyestalk. Pulses of gamma-aminobutyric acid (GABA) elicited depolarizing responses and bursts of action potentials in a dose-dependent manner. These effects were blocked by picrotoxin (50 microM) but not by bicuculline. Picrotoxin also suppressed spontaneous synaptic activity. 2. The responses to GABA were abolished by severing the neurite of X organ cells, at about 150 microns from the cell body. Responses were larger when the application was made at the neuropil level. 3. Topical application of Cd2+ (2 mM), while suppressing synaptic activity, was incapable of affecting the responses to GABA. 4. Under whole-cell voltage-clamp, GABA elicited an inward current with a reversal potential dependent on the chloride equilibrium potential. The GABA effect was accompanied by an input resistance reduction up to 33% at a -50 mV holding potential. No effect of GABA was detected on potassium, calcium, and sodium currents present in X organ cells. 5. The effect of GABA on steady-state currents was dependent on the intracellular calcium concentration. At 10(-6) M [Ca2+]i, GABA (50 microM) increased the membrane conductance more than threefold and shifted the zero-current potential from -25 to -10 mV. At 10(-9) M [Ca2+]i, GABA induced only a 1.3-fold increase in membrane conductance, without shifting the zero-current potential. 6. These results support the notion that in the population of X organ cells sampled in this study, GABA acts as an excitatory neurotransmitter, opening chloride channels.

  10. Contents of Neo-flavored Tea (GABA Kintaro) Containing γ-Aminobutyric Acid

    NASA Astrophysics Data System (ADS)

    Shiraki, Yoshiya

    The contents of γ-aminobutyric acid (GABA), catechins, theaflavins, caffeine and pheophorbide-a in neo-flavored tea (GABA Kintaro tea) were analyzed. 1)The amounts of GABA were increased over 1.5mg/g by means of infrared ray irradiation with agitation treatment. 2)There was a tendency for the amount of catechins to be decreased by this treatment, whereas the amount of theaflavins tended to increase with the same treatment. The composition of these contents in this GABA Kintaro tea was almost the same as that of black tea. 3)There was a tendency for the amount of caffeine to be decreased by this treatment. 4)There was a tendency for the amount of pheophorbide-a to be increased by this treatment. 5)The result of this study showed that the amounts of GABA and theaflavins in this GABA Kintaro tea were higher than ordinary green tea but contained few catechins.It became clear that the amount of pheophorbide-a in this GABA Kintaro tea was less than the standard value established in processed chlorella.

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

    PubMed Central

    Nicholson, Russell A; Lees, George; Zheng, Jian; Verdon, Bernard

    1999-01-01

    12,14-dichlorodehydroabietic acid (12,14-Cl2DHA) reduced GABA-stimulated uptake of 36Cl− into mouse brain synaptoneurosomes suggesting inhibition of mammalian GABAA receptor function. 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. 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. 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 GABAA receptor-chloride channel complex. 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. Our investigation demonstrates that 12,14-Cl2DHA blocks GABA-dependent chloride entry in mammalian brain and operates as a non-competitive insurmountable GABAA 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. PMID:10204999

  12. (3-Aminocyclopentyl)methylphosphinic acids: novel GABA(C) receptor antagonists.

    PubMed

    Chebib, Mary; Hanrahan, Jane R; Kumar, Rohan J; Mewett, Kenneth N; Morriss, Gwendolyn; Wooller, Soraya; Johnston, Graham A R

    2007-03-01

    Our understanding of the role GABA(C) receptors play in the central nervous system is limited due to a lack of specific ligands. Here we describe the pharmacological effects of (+/-)-cis-3- and (+/-)-trans-3-(aminocyclopentyl)methylphosphinic acids ((+/-)-cis- and (+/-)-trans-3-ACPMPA) as novel ligands for the GABA(C) receptor showing little activity at GABA(A) or GABA(B) receptors. (+/-)-cis-3-ACPMPA has similar potency to (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA) at human recombinant rho1 (K(B)=1.0+/-0.2microM) and rat rho3 (K(B)=5.4+/-0.8microM) but is 15 times more potent than TPMPA on human recombinant rho2 (K(B)=1.0+/-0.3microM) GABA(C) receptors expressed in Xenopus oocytes. (+/-)-cis- and (+/-)-trans-3-ACPMPA are novel lead compounds for developing into more potent and selective GABA(C) receptor antagonists with increased lipophilicity for in vivo studies.

  13. GABA, 5-HT and amino acids in the rotifers Brachionus plicatilis and Brachionus rotundiformis.

    PubMed

    Gallardo, W G; Hagiwara, A; Hara, K; Soyano, K; Snell, T W

    2000-11-01

    gamma-Aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT) have been shown to increase the reproduction of the Brachionus plicatilis (NH3L strain). In the present study, the endogenous presence of GABA and 5-HT in the rotifers B. plicatilis (NH3L and Kamiura strains) and Brachionus rotundiformis (Langkawi strain) were confirmed by dot blot immunoassay and high-performance liquid chromatography (HPLC). HPLC showed that GABA and 5-HT concentrations in the three rotifer strains range from 71 to 188 pmol/mg and from 12 to 64 pmol/mg, respectively. A total of 33 amino acids were also detected in B. plicatilis and B. rotundiformis, with glutamic acid, serine, glycine, taurine, threonine, alanine, arginine, proline, valine and isoleucine in high concentrations relative to other amino acids.

  14. 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

  15. Metabolic pathways regulated by γ-aminobutyric acid (GABA) contributing to heat tolerance in creeping bentgrass (Agrostis stolonifera).

    PubMed

    Li, Zhou; Yu, Jingjin; Peng, Yan; Huang, Bingru

    2016-07-26

    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.

  16. Evidence for GABA-Induced Systemic GABA Accumulation in Arabidopsis upon Wounding

    PubMed Central

    Scholz, Sandra S.; Malabarba, Jaiana; Reichelt, Michael; Heyer, Monika; Ludewig, Frank; Mithöfer, Axel

    2017-01-01

    The non-proteinogenic amino acid γ-aminobutyric acid (GABA) is present in all plant species analyzed so far. Its synthesis is stimulated by either acidic conditions occurring after tissue disruption or higher cytosolic calcium level. In mammals, GABA acts as inhibitory neurotransmitter but its function in plants is still not well understood. Besides its involvement in abiotic stress resistance, GABA has a role in the jasmonate-independent defense against invertebrate pests. While the biochemical basis for GABA accumulation in wounded leaves is obvious, the underlying mechanisms for wounding-induced GABA accumulation in systemic leaves remained unclear. Here, the Arabidopsis thaliana knock-out mutant lines pop2-5, unable to degrade GABA, and tpc1-2, lacking a wounding-induced systemic cytosolic calcium elevation, were employed for a comprehensive investigation of systemic GABA accumulation. A wounding-induced systemic GABA accumulation was detected in tpc1-2 plants demonstrating that an increased calcium level was not involved. Similarly, after both mechanical wounding and Spodoptera littoralis feeding, GABA accumulation in pop2-5 plants was significantly higher in local and systemic leaves, compared to wild-type plants. Consequently, larvae feeding on these GABA-enriched mutant plants grew significantly less. Upon exogenous application of a D2-labeled GABA to wounded leaves of pop2-5 plants, its uptake but no translocation to unwounded leaves was detected. In contrast, an accumulation of endogenous GABA was observed in vascular connected systemic leaves. These results suggest that the systemic accumulation of GABA upon wounding does not depend on the translocation of GABA or on an increase in cytosolic calcium. PMID:28382046

  17. 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 .

  18. Mitochondrial reactive oxygen species regulate the strength of inhibitory GABA-mediated synaptic transmission

    NASA Astrophysics Data System (ADS)

    Accardi, Michael V.; Daniels, Bryan A.; Brown, Patricia M. G. E.; Fritschy, Jean-Marc; Tyagarajan, Shiva K.; Bowie, Derek

    2014-01-01

    Neuronal communication imposes a heavy metabolic burden in maintaining ionic gradients essential for action potential firing and synaptic signalling. Although cellular metabolism is known to regulate excitatory neurotransmission, it is still unclear whether the brain’s energy supply affects inhibitory signalling. Here we show that mitochondrial-derived reactive oxygen species (mROS) regulate the strength of postsynaptic GABAA receptors at inhibitory synapses of cerebellar stellate cells. Inhibition is strengthened through a mechanism that selectively recruits α3-containing GABAA receptors into synapses with no discernible effect on resident α1-containing receptors. Since mROS promotes the emergence of postsynaptic events with unique kinetic properties, we conclude that newly recruited α3-containing GABAA receptors are activated by neurotransmitter released onto discrete postsynaptic sites. Although traditionally associated with oxidative stress in neurodegenerative disease, our data identify mROS as a putative homeostatic signalling molecule coupling cellular metabolism to the strength of inhibitory transmission.

  19. γ-Aminobutyric acid (GABA) administration improves action selection processes: a randomised controlled trial

    PubMed Central

    Steenbergen, Laura; Sellaro, Roberta; Stock, Ann-Kathrin; Beste, Christian; Colzato, Lorenza S.

    2015-01-01

    In order to accomplish a task goal, real-life environments require us to develop different action control strategies in order to rapidly react to fast-moving visual and auditory stimuli. When engaging in complex scenarios, it is essential to prioritise and cascade different actions. Recent studies have pointed to an important role of the gamma-aminobutyric acid (GABA)-ergic system in the neuromodulation of action cascading. In this study we assessed the specific causal role of the GABA-ergic system in modulating the efficiency of action cascading by administering 800 mg of synthetic GABA or 800 mg oral of microcrystalline cellulose (placebo). In a double-blind, randomised, between-group design, 30 healthy adults performed a stop-change paradigm. Results showed that the administration of GABA, compared to placebo, increased action selection when an interruption (stop) and a change towards an alternative response were required simultaneously, and when such a change had to occur after the completion of the stop process. These findings, involving the systemic administration of synthetic GABA, provide the first evidence for a possible causal role of the GABA-ergic system in modulating performance in action cascading. PMID:26227783

  20. Caffeine and related compounds block inhibitory amino acid-gated Cl- currents in freshly dissociated rat hippocampal neurones.

    PubMed Central

    Uneyama, H.; Harata, N.; Akaike, N.

    1993-01-01

    1. The effects of caffeine and related compounds on responses mediated by inhibitory amino acids were investigated in freshly dissociated rat hippocampal pyramidal neurones by conventional and nystatin perforated patch-clamp techniques. 2. Glycine and gamma-aminobutyric acid (GABA) evoked Cl- currents in hippocampal neurones. The half-maximum effective concentrations (EC50) of glycine and GABA were 8.5 x 10(-5) and 5 x 10(-6) M, respectively. 3. Caffeine reversibly inhibited both 10(-4) M glycine- and 10(-5) M GABA-induced Cl-currents in a concentration-dependent manner. The half-maximum inhibitory concentrations (IC50) of caffeine were 4.5 x 10(-4) M for the glycine response and 3.6 x 10(-3) M for the GABA response. 4. Caffeine shifted the concentration-response curve of IGly to the right without affecting the maximum response. 5. The inhibitory action of caffeine did not show voltage-dependency. 6. The blocking action of caffeine was not affected by intracellular perfusion with 5 mM BAPTA or by pretreatment with the protein kinase A inhibitor, H-8. This excludes the participation of Ca2+ or cyclic AMP in the inhibitory action of caffeine. 7. Caffeine failed to inhibit the augmentations of aspartate- and N-methyl-D-aspartate (NMDA) -gated current by glycine, suggesting that caffeine has no effect on the allosteric glycine binding site on the NMDA receptor. 8. The inhibitory effects of some xanthine derivatives on IGly were compared. The inhibitory potency of those compounds on IGly was in the order of pentoxifylline > theophylline > or = caffeine > paraxanthine > IBMX > or = theobromine > dyphylline. Xanthine had no effect.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7689394

  1. Effect of experimental diabetes on GABA-mediated inhibition of neurally induced contractions in rat isolated trachea.

    PubMed

    Ozdem, S S; Sadan, G; Usta, C; Taşatargil, A

    2000-04-01

    1. In the present study, we investigated the effect of GABA and selective GABA agonists and antagonists on neurally induced tracheal contractions in streptozotocin (STZ) diabetic rats. 2. Contractile responses to electrical field stimulation (EFS) in rat tracheal rings were completely abolished by atropine and tetrodotoxin, but were unaffected by the ganglion blocker hexamethonium, indicating that they were mediated via neuronal release of acetylcholine (ACh). 3. Contractions induced by EFS, but not by exogenous ACh, were inhibited by GABA and the selective GABA(B) receptor agonist baclofen, but not by the selective GABA(A) receptor agonist 3-aminopropane sulphonic acid. The inhibitory effects of GABA or baclofen were not affected by the GABA(A) antagonist bicuculline, but were significantly reversed by the GABA(B) antagonist phaclofen. 4. The inhibitory effects of both GABA and baclofen were found to be significantly greater in trachea from control rats compared with tissues from diabetic rats. 5. Non-adrenergic, non-cholinergic relaxation responses elicited by EFS in precontracted tracheal rings from diabetic and control rats were similar in magnitude and were unaffected by GABA or GABA analogues. 6. These results suggest that GABA decreases the response to EFS by directly inhibiting the evoked release of ACh through GABA(B) receptors in rat trachea and that STZ-induced diabetes causes an impairment in the inhibitory effect of GABA on neurally induced contractions in this tissue.

  2. Neuronal GABA release and GABA inhibition of ACh release in guinea pig urinary bladder.

    PubMed

    Kusunoki, M; Taniyama, K; Tanaka, C

    1984-04-01

    gamma-Aminobutyric acid (GABA) and glutamate decarboxylase (GAD) are present in the urinary bladder of guinea pigs, and the possible correlation in regional distribution between GABA, GAD, and the number of vesical ganglion cells was studied. Electrical stimulation of the bladder strips produced an increase in the calcium-dependent and tetrodotoxin-sensitive [3H]GABA release and contractions in the strips preloaded with [3H]GABA. Nicotine, acetylcholine chloride (ACh), and hexamethonium did not significantly alter the release of [3H]GABA. Bicuculline significantly enhanced [3H]ACh release and cholinergic components of contractions evoked by electrical stimulation of the bladder strips preloaded with [3H]choline, thereby suggesting that this compound antagonizes the effect of endogenous GABA released during stimulation. GABA and muscimol but not baclofen reduced both the [3H]ACh release and contractions evoked by nicotine. These effects of GABA were antagonized by bicuculline and furosemide but not by alpha- and beta-adrenergic blockers. These findings suggest that GABA may be a noncholinergic nonadrenergic inhibitory neurotransmitter in the urinary bladder. The motility of the urinary bladder is thus inhibited by reducing the release of ACh from the postganglionic cholinergic neurons through bicuculline-sensitive GABA receptors probably associated with the chloride ion channel.

  3. Muscimol as an ionotropic GABA receptor agonist.

    PubMed

    Johnston, Graham A R

    2014-10-01

    Muscimol, a psychoactive isoxazole from Amanita muscaria and related mushrooms, has proved to be a remarkably selective agonist at ionotropic receptors for the inhibitory neurotransmitter GABA. This historic overview highlights the discovery and development of muscimol and related compounds as a GABA agonist by Danish and Australian neurochemists. Muscimol is widely used as a ligand to probe GABA receptors and was the lead compound in the development of a range of GABAergic agents including nipecotic acid, tiagabine, 4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol, (Gaboxadol(®)) and 4-PIOL.

  4. Conversion into GABA (gamma-aminobutyric acid) may reduce the capacity of L-glutamine as an insulin secretagogue.

    PubMed Central

    Fernández-Pascual, Sergio; Mukala-Nsengu-Tshibangu, André; Martín Del Río, Rafael; Tamarit-Rodríguez, Jorge

    2004-01-01

    We have carried out a detailed examination of L-glutamine metabolism in rat islets in order to elucidate the paradoxical failure of L-glutamine to stimulate insulin secretion. L-Glutamine was converted by isolated islets into GABA (gamma-aminobutyric acid), L-aspartate and L-glutamate. Saturation of the intracellular concentrations of all of these amino acids occurred at approx. 10 mmol/l L-glutamine, and their half-maximal values were attained at progressively increasing concentrations of L-glutamine (0.3 mmol/l for GABA; 0.5 and 1.0 mmol/l for Asp and Glu respectively). GABA accumulation accounted for most of the 14CO2 produced at various L-[U-14C]glutamine concentrations. Potentiation by L-glutamine of L-leucine-induced insulin secretion in perifused islets was suppressed by malonic acid dimethyl ester, was accompanied by a significant decrease in islet GABA accumulation, and was not modified in the presence of GABA receptor antagonists [50 micromol/l saclofen or 10 micromol/l (+)-bicuculline]. L-Leucine activated islet glutamate dehydrogenase activity, but had no effect on either glutamate decarboxylase or GABA transaminase activity, in islet homogenates. We conclude that (i) L-glutamine is metabolized preferentially to GABA and L-aspartate, which accumulate in islets, thus preventing its complete oxidation in the Krebs cycle, which accounts for its failure to stimulate insulin secretion; (ii) potentiation by L-glutamine of L-leucine-induced insulin secretion involves increased metabolism of L-glutamate and GABA via the Krebs cycle (glutamate dehydrogenase activation) and the GABA shunt (2-oxoglutarate availability for GABA transaminase) respectively, and (iii) islet release of GABA does not seem to play an important role in the modulation of the islet secretory response to the combination of L-leucine and L-glutamine. PMID:14763900

  5. Conversion into GABA (gamma-aminobutyric acid) may reduce the capacity of L-glutamine as an insulin secretagogue.

    PubMed

    Fernández-Pascual, Sergio; Mukala-Nsengu-Tshibangu, André; Martín Del Río, Rafael; Tamarit-Rodríguez, Jorge

    2004-05-01

    We have carried out a detailed examination of L-glutamine metabolism in rat islets in order to elucidate the paradoxical failure of L-glutamine to stimulate insulin secretion. L-Glutamine was converted by isolated islets into GABA (gamma-aminobutyric acid), L-aspartate and L-glutamate. Saturation of the intracellular concentrations of all of these amino acids occurred at approx. 10 mmol/l L-glutamine, and their half-maximal values were attained at progressively increasing concentrations of L-glutamine (0.3 mmol/l for GABA; 0.5 and 1.0 mmol/l for Asp and Glu respectively). GABA accumulation accounted for most of the 14CO2 produced at various L-[U-14C]glutamine concentrations. Potentiation by L-glutamine of L-leucine-induced insulin secretion in perifused islets was suppressed by malonic acid dimethyl ester, was accompanied by a significant decrease in islet GABA accumulation, and was not modified in the presence of GABA receptor antagonists [50 micromol/l saclofen or 10 micromol/l (+)-bicuculline]. L-Leucine activated islet glutamate dehydrogenase activity, but had no effect on either glutamate decarboxylase or GABA transaminase activity, in islet homogenates. We conclude that (i) L-glutamine is metabolized preferentially to GABA and L-aspartate, which accumulate in islets, thus preventing its complete oxidation in the Krebs cycle, which accounts for its failure to stimulate insulin secretion; (ii) potentiation by L-glutamine of L-leucine-induced insulin secretion involves increased metabolism of L-glutamate and GABA via the Krebs cycle (glutamate dehydrogenase activation) and the GABA shunt (2-oxoglutarate availability for GABA transaminase) respectively, and (iii) islet release of GABA does not seem to play an important role in the modulation of the islet secretory response to the combination of L-leucine and L-glutamine.

  6. 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.

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

    SciTech Connect

    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, located 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.

  8. Local GABA Concentration Predicts Perceptual Improvements After Repetitive Sensory Stimulation in Humans.

    PubMed

    Heba, Stefanie; Puts, Nicolaas A J; Kalisch, Tobias; Glaubitz, Benjamin; Haag, Lauren M; Lenz, Melanie; Dinse, Hubert R; Edden, Richard A E; Tegenthoff, Martin; Schmidt-Wilcke, Tobias

    2016-03-01

    Learning mechanisms are based on synaptic plasticity processes. Numerous studies on synaptic plasticity suggest that the regulation of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) plays a central role maintaining the delicate balance of inhibition and excitation. However, in humans, a link between learning outcome and GABA levels has not been shown so far. Using magnetic resonance spectroscopy of GABA prior to and after repetitive tactile stimulation, we show here that baseline GABA+ levels predict changes in perceptual outcome. Although no net changes in GABA+ are observed, the GABA+ concentration prior to intervention explains almost 60% of the variance in learning outcome. Our data suggest that behavioral effects can be predicted by baseline GABA+ levels, which provide new insights into the role of inhibitory mechanisms during perceptual learning.

  9. Gas release-based prescreening combined with reversed-phase HPLC quantitation for efficient selection of high-γ-aminobutyric acid (GABA)-producing lactic acid bacteria.

    PubMed

    Wu, Qinglong; Shah, Nagendra P

    2015-02-01

    High γ-aminobutyric acid (GABA)-producing lactobacilli are promising for the manufacture of GABA-rich foods and to synthesize GRAS (generally recognized as safe)-grade GABA. However, common chromatography-based screening is time-consuming and inefficient. In the present study, Korean kimchi was used as a model of lactic acid-based fermented foods, and a gas release-based prescreening of potential GABA producers was developed. The ability to produce GABA by potential GABA producers in de Man, Rogosa, and Sharpe medium supplemented with or without monosodium glutamate was further determined by HPLC. Based on the results, 9 isolates were regarded as high GABA producers, and were further genetically identified as Lactobacillus brevis based on the sequences of 16S rRNA gene. Gas release-based prescreening combined with reversed-phase HPLC confirmation was an efficient and cost-effective method to identify high-GABA-producing LAB, which could be good candidates for probiotics. The GABA that is naturally produced by these high-GABA-producing LAB could be used as a food additive.

  10. Comparison of Steroid Modulation of Spontaneous Inhibitory Postsynaptic Currents in Cultured Hippocampal Neurons and Steady-State Single-Channel Currents from Heterologously Expressed α1β2γ2L GABA(A) Receptors.

    PubMed

    Chakrabarti, Sampurna; Qian, Mingxing; Krishnan, Kathiresan; Covey, Douglas F; Mennerick, Steven; Akk, Gustav

    2016-04-01

    Neuroactive steroids are efficacious modulators of γ-aminobutyric acid type A receptor (GABA(A)) receptor function. The effects of steroids on the GABA(A) receptor are typically determined by comparing steady-state single-channel open probability or macroscopic peak responses elicited by GABA in the absence and presence of a steroid. Due to differences in activation conditions (exposure duration, concentration of agonist), it is not obvious whether modulation measured using typical experimental protocols can be used to accurately predict the effect of a modulator on native receptors under physiologic conditions. In the present study, we examined the effects of 14 neuroactive steroids and analogs on the properties of spontaneous inhibitory postsynaptic currents (sIPSCs) in cultured rat hippocampal neurons. The goal was to determine whether the magnitude of modulation of the decay time course of sIPSCs correlates with the extent of modulation and kinetic properties of potentiation as determined in previous single-channel studies. The steroids were selected to cover a wide range of efficacy on heterologously expressed rat α1β2γ2L GABA(A) receptors, ranging from essentially inert to highly efficacious (strong potentiators of single-channel and macroscopic peak responses). The data indicate a strong correlation between prolongation of the decay time course of sIPSCs and potentiation of single-channel open probability. Furthermore, changes in intracluster closed time distributions were the single best predictor of prolongation of sIPSCs. We infer that the information obtained in steady-state single-channel recordings can be used to forecast modulation of synaptic currents.

  11. Calcium dependent release of gamma-aminobutyric acid (GABA) from human cerebral cortex.

    PubMed

    Haugstad, T S; Hegstad, E; Langmoen, I A

    1992-07-06

    The release of the amino acids GABA, taurine, glycine, glutamine and leucine from human neocortex was investigated in vitro by utilizing brain tissue removed during 8 standard temporal lobectomies for epilepsy or tumor. Slices (0.5 mm thick) were cut from each biopsy and randomly placed in three different chambers. After 90 min preincubation, the three sets of slices were incubated for 60 s in wells containing, respectively, (A) regular ACSF (control), (B) ACSF with 50 mM K+ (to depolarize the cell membrane) and (C) ACSF with 50 mM K+, 0 mM Ca2+ and 4 mM Mg2+ (depolarization during blocked synaptic transmission). The content of amino acids in the wells was determined by high-performance liquid chromatography after pre-column derivatization of the amino acids with o-phthalaldehyde. Membrane depolarization (well B) increased the GABA release to 650% (620 pmol/mg) of control (well A, 95 pmol/mg). Blocking synaptic transmission (well C) reduced the evoked release by 50% (360 pmol/mg). The release of glycine, taurine, glutamine and leucine during membrane depolarization was not significantly different from the control values. The data provide evidence for a Ca(2+)-dependent release of GABA, supporting a possible role of this amino acid as a neurotransmitter in human neocortex.

  12. Guanidino acids act as rho1 GABA(C) receptor antagonists.

    PubMed

    Chebib, Mary; Gavande, Navnath; Wong, Kit Yee; Park, Anna; Premoli, Isabella; Mewett, Kenneth N; Allan, Robin D; Duke, Rujee K; Johnston, Graham A R; Hanrahan, Jane R

    2009-10-01

    GABA(C) receptors play a role in myopia, memory-related disorders and circadian rhythms signifying a need to develop potent and selective agents for this class of receptors. Guanidino analogs related to glycine, beta-alanine and taurine were evaluated at human rho(1)GABA(C) receptors expressed in Xenopus oocytes using 2-electrode voltage clamp methods. Of the 12 analogs tested, 8 analogs were active as antagonists and the remaining were inactive. (S)-2-guanidinopropionic acid (IC(50) = 2.2 microM) and guanidinoacetic acid (IC(50) = 5.4 microM; K (B) = 7.75 microM [pK (B) = 5.11 +/- 0.06]) were the most potent being competitive antagonists at this receptor. In contrast, the beta-alanine and GABA guanidino analogs showed reduced activity, indicating the distance between the carboxyl carbon and terminal nitrogen of the guanidino group is critical for activity. Substituting the C2-position of guanidinoacetic acid with various alkyl groups reduced activity indicating that steric effects may impact on activity. The results of this study contribute to the structure-activity-relationship profile required in developing novel therapeutic agents.

  13. Stimulation of [3H] GABA and beta-[3H] alanine release from rat brain slices by cis-4-aminocrotonic acid.

    PubMed

    Chebib, M; Johnston, G A

    1997-02-01

    cis-4-Aminocrotonic acid (CACA; 100 microM), an analogue of GABA in a folded conformation, stimulated the passive release of [3H] GABA from slices of rat cerebellum, cerebral cortex, retina, and spinal cord and of beta-[3H]alanine from slices of cerebellum and spinal cord without influencing potassium-evoked release. In contrast, CACA (100 microM) did not stimulate the passive release of [3H]taurine from slices of cerebellum and spinal cord or of D-[3H]aspartate from slices of cerebellum and did not influence potassium-evoked release of [3H]-taurine from the cerebellum and spinal cord and D-[3H]-aspartate from the cerebellum. These results suggest that the effects of CACA on GABA and beta-alanine release are due to CACA acting as a substrate for a beta-alanine-sensitive GABA transport system, consistent with CACA inhibiting the uptake of beta-[3H]alanine into slices of rat cerebellum and cerebral cortex. The observed Ki for CACA against beta-[3H]alanine uptake in the cerebellum was 750 +/- 60 microM. CACA appears to be 10-fold weaker as a substrate for the transporter system than as an agonist for the GABAc receptor. The effects of CACA on GABA and beta-alanine release provide indirect evidence for a GABA transporter in cerebellum, cerebral cortex, retina, and spinal cord that transports GABA, beta-alanine, CACA, and nipecotic acid that has a similar pharmacological profile to that of the GABA transporter, GAT-3, cloned from rat CNS. The structural similarities of GABA, beta-alanine, CACA, and nipecotic acid are demonstrated by computer-aided molecular modeling, providing information on the possible conformations of these substances being transported by a common carrier protein.

  14. GABA, taurine and learning: release of amino acids from slices of chick brain following filial imprinting.

    PubMed

    McCabe, B J; Horn, G; Kendrick, K M

    2001-01-01

    The intermediate and medial hyperstriatum ventrale (IMHV) is a forebrain region in the domestic chick that is a site of information storage for the learning process of imprinting. We enquired whether imprinting is associated with learning-related increases in calcium-dependent, potassium-stimulated release of neurotransmitter amino acids from the IMHV. Chicks were hatched and reared in darkness until 15-30 h after hatching. They then either remained in darkness or were trained for 2 h by exposure to an imprinting stimulus. One hour later, the chicks were given a preference test and a preference score was calculated from the results of this test, as a measure of imprinting. Chicks were killed 2 h after training. Slices from the left and right IMHV of trained and untrained chicks were superfused with Krebs' solution either with or without calcium and the superfusate assayed for arginine, aspartate, citrulline, GABA, glutamate, glycine and taurine using high-performance liquid chromatography. For calcium-containing superfusates from the left IMHV, preference score was significantly correlated with potassium-stimulated release of (i) GABA (r=0.51, 23 d.f., P=0.008) and (ii) taurine (r=0.77, 23 d.f., P<0.0001). There was no significant difference between the mean values of trained and untrained chicks for either compound. However, examination of the variance of the data indicated that release of both GABA and taurine increased as a result of learning. No significant correlation between preference score and release was found for any of the amino acids from the right IMHV, nor for control tissue from the left IMHV superfused with calcium-free solution. These results demonstrate that the learning process of imprinting is associated with increases in releasable pools of GABA and taurine and/or membrane excitability in the left IMHV.

  15. The effect of experimental ischaemia and excitatory amino acid agonists on the GABA and serotonin immunoreactivities in the rabbit retina.

    PubMed

    Osborne, N N; Herrera, A J

    1994-04-01

    The aim of the described experiments was to use immunohistochemistry to visualize the release of GABA from specific retinal amacrine cells following ischaemia and to establish the involvement of defined glutamatergic receptors. In initial experiments, rabbit retinas were exposed in vitro to excitatory amino acid agonists alone or in combination with a putative antagonist, or in physiological solution lacking oxygen and glucose, or in solution containing potassium cyanide for 45 min at 37 degrees C. The nature of the GABA immunoreactivity was then examined by immunohistochemistry. In other in vitro experiments, retinas were first allowed to accumulate exogenous serotonin before exposing the tissues to the combinations as described. These tissues were then processed immunohistochemically for the localization of serotonin. In yet other experiments, the intraocular pressure of a rabbit's eye was raised to about 110 mmHg for 60 min and a reperfusion time of 45 min allowed before dissecting the retina and processing for the localization of GABA immunoreactivity. The other eye served as a control. Of the excitatory amino acid agonists tested, only N-methyl-D-aspartate, kainate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid caused a change in the GABA immunoreactivity. The N-methyl-D-aspartate effect was specifically antagonized by dizocilpine maleate, dextromethorphan and memantine, and was characterized by a reduction in the number of GABA-immunoreactive perikarya. The GABA "staining" in the inner plexiform layer also appeared as four clear bands. The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid- and kainate-induced effects were both antagonized by 6-cyano-2,3-dihydroxy-7-nitroquinoxaline-2,3-dione and partially by kynurenic acid at the concentrations used. Here, the amount of GABA-positive perikarya was greatly reduced and three immunoreactive bands appeared in the inner plexiform layer. However, for low concentrations of alpha-amino-3-hydroxy

  16. Efficient production of gamma-aminobutyric acid using Escherichia coli by co-localization of glutamate synthase, glutamate decarboxylase, and GABA transporter.

    PubMed

    Dung Pham, Van; Somasundaram, Sivachandiran; Lee, Seung Hwan; Park, Si Jae; Hong, Soon Ho

    2016-01-01

    Gamma-aminobutyric acid (GABA) is an important bio-product, which is used in pharmaceutical formulations, nutritional supplements, and biopolymer monomer. The traditional GABA process involves the decarboxylation of glutamate. However, the direct production of GABA from glucose is a more efficient process. To construct the recombinant strains of Escherichia coli, a novel synthetic scaffold was introduced. By carrying out the co-localization of glutamate synthase, glutamate decarboxylase, and GABA transporter, we redirected the TCA cycle flux to GABA pathway. The genetically engineered E. coli strain produced 1.08 g/L of GABA from 10 g/L of initial glucose. Thus, with the introduction of a synthetic scaffold, we increased GABA production by 2.2-fold. The final GABA concentration was increased by 21.8% by inactivating competing pathways.

  17. Paralogous chemoreceptors mediate chemotaxis towards protein amino acids and the non-protein amino acid gamma-aminobutyrate (GABA).

    PubMed

    Rico-Jiménez, Miriam; Muñoz-Martínez, Francisco; García-Fontana, Cristina; Fernandez, Matilde; Morel, Bertrand; Ortega, Alvaro; Ramos, Juan Luis; Krell, Tino

    2013-06-01

    The paralogous receptors PctA, PctB and PctC of Pseudomonas aeruginosa were reported to mediate chemotaxis to amino acids, intermediates of amino acid metabolism and chlorinated hydrocarbons. We show that the recombinant ligand binding regions (LBRs) of PctA, PctB and PctC bind 17, 5 and 2 l-amino acids respectively. In addition, PctC-LBR recognized GABA but not any other structurally related compound. l-Gln, one of the three amino acids that is not recognized by PctA-LBR, was the most tightly binding ligand to PctB suggesting that PctB has evolved to mediate chemotaxis primarily towards l-Gln. Bacteria were efficiently attracted to l-Gln and GABA, but mutation of pctB and pctC, respectively, abolished chemoattraction. The physiological relevance of taxis towards GABA is proposed to reside in an interaction with plants. LBRs were predicted to adopt double PDC (PhoQ/DcuS/CitA) like structures and site-directed mutagenesis studies showed that ligands bind to the membrane-distal module. Analytical ultracentrifugation studies have shown that PctA-LBR and PctB-LBR are monomeric in the absence and presence of ligands, which is in contrast to the enterobacterial receptors that require sensor domain dimers for ligand recognition.

  18. Prejunctional GABA-B inhibition of cholinergic, neurally-mediated airway contractions in guinea-pigs.

    PubMed

    Chapman, R W; Danko, G; Rizzo, C; Egan, R W; Mauser, P J; Kreutner, W

    1991-01-01

    GABA is a known inhibitory neurotransmitter in the CNS. Recent studies have also demonstrated the presence of GABA in peripheral tissue, including lung. To delineate a role for GABA in lung, the effect of GABA and selective GABA agonists and antagonists on neuronally-induced airway contractions in guinea pigs were studied. In vitro, tracheal contractions induced by electrical field stimulation (EFS) were inhibited by tetrodotoxin and atropine indicating that the contractions were mediated by neuronal release of acetylcholine. The contractions caused by EFS, but not those by exogenous acetylcholine, were inhibited by GABA (EC50 = 4.5 microM) and the selective GABA-B agonist baclofen (EC50 = 9 microM), but not by the GABA-A agonist, muscimol. The inhibitory effect of baclofen was not affected by the GABA-A antagonist, bicuculline, but was significantly reversed with the GABA-B antagonists, 3-aminopropylphosphonic acid (3-APPA) (pA2 = 4.5) and 2-hydroxysaclofen (pA2 = 4.1). In vivo, vagal nerve stimulation (5 V, 20 Hz, 0.5 ms, 5 s) in anesthetized, mechanically ventilated guinea-pigs caused cholinergic-dependent bronchospasms that were inhibited by intravenous GABA (3 and 10 mg/kg) and baclofen (1-10 mg/kg), but not by muscimol. The inhibitory effects of GABA and baclofen against vagal bronchospasm were blocked by 3-APPA (5 mg/kg, i.v.), but not by bicuculline. Responses to the GABA-B agonists were unaltered after the treatment of animals with phentolamine or propranolol to block alpha-adrenergic and beta-adrenergic receptors, respectively. Bronchospasm due to intravenous methacholine was also unchanged by GABA and baclofen.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Zinc inhibition of γ-aminobutyric acid transporter 4 (GAT4) reveals a link between excitatory and inhibitory neurotransmission

    PubMed Central

    Cohen-Kfir, Einav; Lee, William; Eskandari, Sepehr; Nelson, Nathan

    2005-01-01

    γ-Aminobutyric acid (GABA) transporters (GATs) play an important role in inhibitory neurotransmission by clearing synaptically released GABA and by maintaining low resting levels of GABA in synaptic and extrasynaptic regions. In certain brain regions, vesicular zinc is colocalized and coreleased with glutamate and modulates the behavior of a number of channels, receptors, and transporters. We examined the effect of zinc on expressed GATs (GAT1, GAT2, GAT3, and GAT4) in Xenopus laevis oocytes by using tracer flux and electrophysiological methods. We show that zinc is a potent inhibitor of GAT4 (Ki of 3 μM). Immunolocalization of GAT4 in the hippocampus revealed dense localization in the CA1 and CA3 regions of the hippocampus, regions which are known to be heavily populated by zinc-containing glutamatergic neurons. The results suggest a physiological role of synaptically released zinc in the hippocampus, because zinc released from hyperactive glutamatergic neurons may simultaneously bring about elevated GABAergic inhibition. Therefore, this mode of zinc function signifies a link between excitatory and inhibitory neurotransmission and may play a neuroprotective role against glutamate-induced excitotoxicity. PMID:15829583

  20. Effects of inhibitory amino acids on expression of GABAA Rα and glycine Rα1 in hypoxic rat cortical neurons during development

    PubMed Central

    Qian, H; Feng, Y; He, XZ; Yang, YL; Sung, JH; Xia, Y

    2011-01-01

    Recent studies suggest that GABA and glycine are protective to mature but toxic to immature cortical neurons during prolonged hypoxia. Since the action of these inhibitory amino acids is mediated by GABA and glycine receptors, the expression of these receptors is a critical factor in determining neuronal response to GABAA and glycine in hypoxia. Therefore, we asked whether in rat cortical neurons, 1) hypoxia alters the expression of the GABA and glycine receptors; 2) inhibitory amino acids change the course of GABA and glycine receptor expression; and 3) there are any differences between the immature and mature neurons. In cultured rat cortical neurons from day 4 (4 Days in Vitro or DIV 4) to day 20 (DIV 20), we observed that 1) GABAARα and GlyRα1 underwent differential changes in expression during the development in-vitro; 2) hypoxia for 3 days decreased GABAARα and GlyRα1 density in the neurons in-between DIV 4 and DIV 20, but did not induce a major change in immature (DIV 4) and mature (DIV 20) neurons; 3) during normoxia GABA, glycine and taurine decreased GABAARα and GlyRα1 density in the immature neurons, but had a tendency to increase the density in the mature neurons, except for taurine; 4) under hypoxia, all these amino acids decreased GABAARα and GlyRα1 density in most groups of the immature neurons with a slight effect on the mature neurons; and 5) δ-opioid receptor activation with DADLE increased GABAARα and GlyRα1 density in both the immature and mature neurons under normoxia and in the mature neurons under hypoxic condition. These data suggest that inhibitory amino acids differentially regulate the expression of GABAA and glycine receptors in rat cortical neurons in normoxic and hypoxic conditions with major differences between the immature and mature neurons. PMID:22018691

  1. The role of GABA in the regulation of GnRH neurons

    PubMed Central

    Watanabe, Miho; Fukuda, Atsuo; Nabekura, Junichi

    2014-01-01

    Gonadotropin-releasing hormone (GnRH) neurons form the final common pathway for the central regulation of reproduction. Gamma-amino butyric acid (GABA) has long been implicated as one of the major players in the regulation of GnRH neurons. Although GABA is typically an inhibitory neurotransmitter in the mature adult central nervous system, most mature GnRH neurons show the unusual characteristic of being excited by GABA. While many reports have provided much insight into the contribution of GABA to the activity of GnRH neurons, the precise physiological role of the excitatory action of GABA on GnRH neurons remains elusive. This brief review presents the current knowledge of the role of GABA signaling in GnRH neuronal activity. We also discuss the modulation of GABA signaling by neurotransmitters and neuromodulators and the functional consequence of GABAergic inputs to GnRH neurons in both the physiology and pathology of reproduction. PMID:25506316

  2. Excitatory Synaptic Responses Mediated by GABA_A Receptors in the Hippocampus

    NASA Astrophysics Data System (ADS)

    Michelson, Hillary B.; Wong, Robert K. S.

    1991-09-01

    Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the cortex. Activation of postsynaptic GABA_A receptors hyperpolarizes cells and inhibits neuronal activity. Synaptic responses mediated by GABA_A receptors also strongly excited hippocampal neurons. This excitatory response was recorded in morphologically identified interneurons in the presence of 4-aminopyridine or after elevation of extracellular potassium concentrations. The synaptic excitation sustained by GABA_A receptors synchronized the activity of inhibitory interneurons. This synchronized discharge of interneurons in turn elicited large-amplitude inhibitory postsynaptic potentials in pyramidal and granule cells. Excitatory synaptic responses mediated by GABA_A receptors may thus provide a mechanism for the recruitment of GABAergic interneurons through their recurrent connections.

  3. 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

  4. Oxo-4-methylpentanoic acid directs the metabolism of GABA into the Krebs cycle in rat pancreatic islets.

    PubMed

    Hernández-Fisac, Inés; Fernández-Pascual, Sergio; Ortsäter, Henrik; Pizarro-Delgado, Javier; Martín del Río, Rafael; Bergsten, Peter; Tamarit-Rodriguez, Jorge

    2006-11-15

    OMP (oxo-4-methylpentanoic acid) stimulates by itself a biphasic secretion of insulin whereas L-leucine requires the presence of L-glutamine. L-Glutamine is predominantly converted into GABA (gamma-aminobutyric acid) in rat islets and L-leucine seems to promote its metabolism in the 'GABA shunt' [Fernández-Pascual, Mukala-Nsengu-Tshibangu, Martín del Río and Tamarit-Rodríguez (2004) Biochem. J. 379, 721-729]. In the present study, we have investigated how 10 mM OMP affects L-glutamine metabolism to uncover possible differences with L-leucine that might help to elucidate whether they share a common mechanism of stimulation of insulin secretion. In contrast with L-leucine, OMP alone stimulated a biphasic insulin secretion in rat perifused islets and decreased the islet content of GABA without modifying its extracellular release irrespective of the concentration of L-glutamine in the medium. GABA was transaminated to L-leucine whose intracellular concentration did not change because it was efficiently transported out of the islet cells. The L-[U-14C]-Glutamine (at 0.5 and 10.0 mM) conversion to 14CO2 was enhanced by 10 mM OMP within 30% and 70% respectively. Gabaculine (250 microM), a GABA transaminase inhibitor, suppressed OMP-induced oxygen consumption but not L-leucine- or glucose-stimulated respiration. It also suppressed the OMP-induced decrease in islet GABA content and the OMP-induced increase in insulin release. These results support the view that OMP promotes islet metabolism in the 'GABA shunt' generating 2-oxo-glutarate, in the branched-chain alpha-amino acid transaminase reaction, which would in turn trigger GABA deamination by GABA transaminase. OMP, but not L-leucine, suppressed islet semialdehyde succinic acid reductase activity and this might shift the metabolic flux of the 'GABA shunt' from gamma-hydroxybutyrate to succinic acid production.

  5. 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.

  6. Reproducibility and effect of tissue composition on cerebellar γ-aminobutyric acid (GABA) MRS in an elderly population.

    PubMed

    Long, Zaiyang; Dyke, Jonathan P; Ma, Ruoyun; Huang, Chaorui C; Louis, Elan D; Dydak, Ulrike

    2015-10-01

    MRS provides a valuable tool for the non-invasive detection of brain γ-aminobutyric acid (GABA) in vivo. GABAergic dysfunction has been observed in the aging cerebellum. The study of cerebellar GABA changes is of considerable interest in understanding certain age-related motor disorders. However, little is known about the reproducibility of GABA MRS in an aged population. Therefore, this study aimed to explore the feasibility and reproducibility of GABA MRS in the aged cerebellum at 3.0 T and to examine the effect of differing tissue composition on GABA measurements. MRI and (1)H MRS examinations were performed on 10 healthy elderly volunteers (mean age, 75.2 ± 6.5 years) using a 3.0-T Siemens Tim Trio scanner. Among them, five subjects were scanned twice to assess the short-term reproducibility. The MEGA-PRESS (Mescher-Garwood point-resolved spectroscopy) J-editing sequence was used for GABA detection in two volumes of interest (VOIs) in the left and right cerebellar dentate. MRS data processing and quantification were performed with LCModel 6.3-0L using two separate basis sets, generated from density matrix simulations using published values for chemical shifts and J couplings. Raw metabolite levels from LCModel outputs were corrected for cerebrospinal fluid contamination and relaxation. GABA-edited spectra yielded robust and stable GABA measurements with averaged intra-individual coefficients of variation for corrected GABA+ between 4.0 ± 2.8% and 13.4 ± 6.3%, and inter-individual coefficients of variation between 12.6% and 24.2%. In addition, there was a significant correlation between GABA+ obtained with the two LCModel basis sets. Overall, our results demonstrated the feasibility and reproducibility of cerebellar GABA-edited MRS at 3.0 T in an elderly population. This information might be helpful for studies using this technique to study GABA changes in normal or diseased aging brain, e.g. for power calculations and the interpretation of longitudinal

  7. Edited magnetic resonance spectroscopy detects an age-related decline in brain GABA levels.

    PubMed

    Gao, Fei; Edden, Richard A E; Li, Muwei; Puts, Nicolaas A J; Wang, Guangbin; Liu, Cheng; Zhao, Bin; Wang, Huiquan; Bai, Xue; Zhao, Chen; Wang, Xin; Barker, Peter B

    2013-09-01

    Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the brain. Although measurements of GABA levels in vivo in the human brain using edited proton magnetic resonance spectroscopy ((1)H-MRS) have been established for some time, it is has not been established how regional GABA levels vary with age in the normal human brain. In this study, 49 healthy men and 51 healthy women aged between 20 and 76 years were recruited and J-difference edited spectra were recorded at 3T to determine the effect of age on GABA levels, and to investigate whether there are regional and gender differences in GABA in mesial frontal and parietal regions. Because the signal detected at 3.02 ppm using these experimental parameters is also expected to contain contributions from both macromolecules (MM) and homocarnosine, in this study the signal is labeled GABA+ rather than GABA. Significant negative correlations were observed between age and GABA+ in both regions studied (GABA+/Cr: frontal region, r=-0.68, p<0.001, parietal region, r=-0.54, p<0.001; GABA+/NAA: frontal region, r=-0.58, p<0.001, parietal region, r=-0.49, p<0.001). The decrease in GABA+ with age in the frontal region was more rapid in women than men. Evidence of a measureable decline in GABA is important in considering the neurochemical basis of the cognitive decline that is associated with normal aging.

  8. Manganese accumulation in membrane fractions of primary astrocytes is associated with decreased γ-aminobutyric acid (GABA) uptake, and is exacerbated by oleic acid and palmitate.

    PubMed

    Fordahl, Steve C; Erikson, Keith M

    2014-05-01

    Manganese (Mn) exposure interferes with GABA uptake; however, the effects of Mn on GABA transport proteins (GATs) have not been identified. We sought to characterize how Mn impairs GAT function in primary rat astrocytes. Astrocytes exposed to Mn (500 μM) had significantly reduced (3)H-GABA uptake despite no change in membrane or cytosolic GAT3 protein levels. Co-treatment with 100 μM oleic or palmitic acids (both known to be elevated in Mn neurotoxicity), exacerbated the Mn-induced decline in (3)H-GABA uptake. Mn accumulation in the membrane fraction of astrocytes was enhanced with fatty acid administration, and was negatively correlated with (3)H-GABA uptake. Furthermore, control cells exposed to Mn only during the experimental uptake had significantly reduced (3)H-GABA uptake, and the addition of GABA (50 μM) blunted cytosolic Mn accumulation. These data indicate that reduced GAT function in astrocytes is influenced by Mn and fatty acids accumulating at or interacting with the plasma membrane.

  9. GABA shunt and polyamine degradation pathway on γ-aminobutyric acid accumulation in germinating fava bean (Vicia faba L.) under hypoxia.

    PubMed

    Yang, Runqiang; Guo, Qianghui; Gu, Zhenxin

    2013-01-01

    GABA shunt and polyamine degradation pathway on γ-aminobutyric acid (GABA) accumulation in germinating fava bean under hypoxia was investigated. GABA content, GAD and DAO activity were significantly increased under hypoxia treatment. Glu and polyamine contents enhanced largely and thus supplied as sufficient substrates for GABA formation. In contrast, GABA content decreased, mainly in the embryo, after removing the hypoxia stress. DAO activity, Glu and polyamines contents decreased, while an increment of GAD activity was observed. This indicated that GAD activity can be not only regulated by hypoxia, but by the rapid growth of embryo after the recovery from hypoxia stress. When treated with AG, DAO activity was almost inhibited completely, and the GABA content decreased by 32.96% and 32.07% after treated for 3 and 5 days, respectively. Hence, it can be inferred that about 30% of GABA formed in germinating fava bean under hypoxia was supplied by polyamine degradation pathway.

  10. 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

  11. Exogenous γ-aminobutyric Acid (GABA) Application Improved Early Growth, Net Photosynthesis, and Associated Physio-Biochemical Events in Maize

    PubMed Central

    Li, Wu; Liu, Jianhua; Ashraf, Umair; Li, Gaoke; Li, Yuliang; Lu, Wenjia; Gao, Lei; Han, Fuguang; Hu, Jianguang

    2016-01-01

    γ-aminobutyric acid (GABA) is an endogenous signaling molecule and involved in growth regulations and plant development, however, a little information is available on the consequences of exogenous GABA application on growth, development, and associated physio-biochemical processes in maize. The present study examined the GABA-induced regulations in early growth, net photosynthetic rate, gas exchange, osmoregulation, and enzymatic activities in three maize cultivars, i.e., Yuecainuo 6, Zhengtian 68, and Yuecainuo 2. Two levels of GABA, i.e., 0 mg L-1 and 50 mg L-1, in solution form, with total application volume of 100 ml per pot containing 15 maize seedlings were exogenously applied. Results revealed that exogenous GABA application improved seedling growth in terms of seedling length and biomass accumulation in all maize cultivars at both 3 and 7 days after treatment (DAT). It also promoted net photosynthesis and variably affected gas exchange attributes, i.e., stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as leaves SPAD value. Furthermore, lipid peroxidation [in terms of malondialdehyde (MDA)] under GABA treated maize seedlings were also remained variable; however, osmolyte accumulation (protein and proline) and activities of anti-oxidants enzymes, i.e., super-oxide dismutase and peroxidase were also affected differently at both 3 and 7 DAT in all maize cultivars. Furthermore, enzymes involved in nitrogen metabolism, e.g., nitrate reductase and glutamine synthetase were improved. These results suggest the involvement of GABA in various physio-metablical mechanisms which might lead to improvement in morphological growth of maize. In future, research is still needed at molecular and genetic levels to unravel the involvement of GABA-mediated regulations in growth and its associated physio-biochemical mechanisms. PMID:27446149

  12. Quantification of γ-aminobutyric acid (GABA) in (1) H MRS volumes composed heterogeneously of grey and white matter.

    PubMed

    Mikkelsen, Mark; Singh, Krish D; Brealy, Jennifer A; Linden, David E J; Evans, C John

    2016-11-01

    The quantification of γ-aminobutyric acid (GABA) concentration using localised MRS suffers from partial volume effects related to differences in the intrinsic concentration of GABA in grey (GM) and white (WM) matter. These differences can be represented as a ratio between intrinsic GABA in GM and WM: rM . Individual differences in GM tissue volume can therefore potentially drive apparent concentration differences. Here, a quantification method that corrects for these effects is formulated and empirically validated. Quantification using tissue water as an internal concentration reference has been described previously. Partial volume effects attributed to rM can be accounted for by incorporating into this established method an additional multiplicative correction factor based on measured or literature values of rM weighted by the proportion of GM and WM within tissue-segmented MRS volumes. Simulations were performed to test the sensitivity of this correction using different assumptions of rM taken from previous studies. The tissue correction method was then validated by applying it to an independent dataset of in vivo GABA measurements using an empirically measured value of rM . It was shown that incorrect assumptions of rM can lead to overcorrection and inflation of GABA concentration measurements quantified in volumes composed predominantly of WM. For the independent dataset, GABA concentration was linearly related to GM tissue volume when only the water signal was corrected for partial volume effects. Performing a full correction that additionally accounts for partial volume effects ascribed to rM successfully removed this dependence. With an appropriate assumption of the ratio of intrinsic GABA concentration in GM and WM, GABA measurements can be corrected for partial volume effects, potentially leading to a reduction in between-participant variance, increased power in statistical tests and better discriminability of true effects.

  13. Exogenous γ-aminobutyric Acid (GABA) Application Improved Early Growth, Net Photosynthesis, and Associated Physio-Biochemical Events in Maize.

    PubMed

    Li, Wu; Liu, Jianhua; Ashraf, Umair; Li, Gaoke; Li, Yuliang; Lu, Wenjia; Gao, Lei; Han, Fuguang; Hu, Jianguang

    2016-01-01

    γ-aminobutyric acid (GABA) is an endogenous signaling molecule and involved in growth regulations and plant development, however, a little information is available on the consequences of exogenous GABA application on growth, development, and associated physio-biochemical processes in maize. The present study examined the GABA-induced regulations in early growth, net photosynthetic rate, gas exchange, osmoregulation, and enzymatic activities in three maize cultivars, i.e., Yuecainuo 6, Zhengtian 68, and Yuecainuo 2. Two levels of GABA, i.e., 0 mg L(-1) and 50 mg L(-1), in solution form, with total application volume of 100 ml per pot containing 15 maize seedlings were exogenously applied. Results revealed that exogenous GABA application improved seedling growth in terms of seedling length and biomass accumulation in all maize cultivars at both 3 and 7 days after treatment (DAT). It also promoted net photosynthesis and variably affected gas exchange attributes, i.e., stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as leaves SPAD value. Furthermore, lipid peroxidation [in terms of malondialdehyde (MDA)] under GABA treated maize seedlings were also remained variable; however, osmolyte accumulation (protein and proline) and activities of anti-oxidants enzymes, i.e., super-oxide dismutase and peroxidase were also affected differently at both 3 and 7 DAT in all maize cultivars. Furthermore, enzymes involved in nitrogen metabolism, e.g., nitrate reductase and glutamine synthetase were improved. These results suggest the involvement of GABA in various physio-metablical mechanisms which might lead to improvement in morphological growth of maize. In future, research is still needed at molecular and genetic levels to unravel the involvement of GABA-mediated regulations in growth and its associated physio-biochemical mechanisms.

  14. 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.

  15. Focal Uncaging of GABA Reveals a Temporally Defined Role for GABAergic Inhibition during Appetitive Associative Olfactory Conditioning in Honeybees

    ERIC Educational Resources Information Center

    Raccuglia, Davide; Mueller, Uli

    2013-01-01

    Throughout the animal kingdom, the inhibitory neurotransmitter ?-aminobutyric acid (GABA) is a key modulator of physiological processes including learning. With respect to associative learning, the exact time in which GABA interferes with the molecular events of learning has not yet been clearly defined. To address this issue, we used two…

  16. Change in Excitability of Corticospinal Pathway and GABA-Mediated Inhibitory Circuits of Primary Motor Cortex Induced by Contraction of Adjacent Hand Muscle.

    PubMed

    Jono, Yasutomo; Iwata, Yasuyuki; Mizusawa, Hiroki; Hiraoka, Koichi

    2016-11-01

    The present study examined whether the excitability of the corticospinal pathway and the GABA-mediated inhibitory circuits of the primary motor cortex that project onto the corticospinal neurons in the tonically contracting hand muscle are changed by tonic contraction of the adjacent hand muscle. The motor evoked potential (MEP) and cortical silent period (CSP) in the tonically contracting hand muscle were obtained while the adjacent hand muscle was either tonically contracting or at rest. The MEP and CSP of the first dorsal interosseous (FDI) muscle elicited across the scalp sites where the MEP is predominantly elicited in the FDI muscle were decreased by tonic contraction of the abductor digiti minimi (ADM) muscle. The centers of the area of the MEP and the duration of the CSP in the FDI muscle elicited across the sites where the MEP is predominantly elicited in the FDI muscle were lateral to those in the FDI muscle elicited across the sites where the MEP is elicited in both the FDI and ADM muscles. They were also lateral to those in the ADM muscle elicited either across the sites where the MEP is predominantly elicited in the ADM muscle, or across the sites where the MEP is elicited in both the FDI and ADM muscles. The decrease in the corticospinal excitability and the excitability of the GABA-mediated inhibitory circuits of the primary motor cortex that project onto the corticospinal neurons in the FDI muscle may be due either to (1) the interaction between the activity of the lateral area of the FDI representation and the descending drive to the ADM muscle, or (2) the decreased susceptibility of the primary motor area that predominantly projects onto the corticospinal neurons in the FDI muscle, which also plays a role in independent finger movement when both the FDI and ADM muscles act together as synergists.

  17. Modulation of ischemia-evoked release of excitatory and inhibitory amino acids by adenosine A1 receptor agonist.

    PubMed

    Goda, H; Ooboshi, H; Nakane, H; Ibayashi, S; Sadoshima, S; Fujishima, M

    1998-09-18

    Adenosine has been reported to have beneficial effects against ischemic brain damage, although the mechanisms are not fully clarified. To examine the role of adenosine on the ischemia-evoked release of neurotransmitters, we applied a highly selective agonist for adenosine A1 receptor, 2-chloro-N6-cyclopentyladenosine (CCPA), into the ischemic brain using in vivo brain dialysis, which directly delivered the agonist to the local brain area. Concentrations of extracellular amino acids (glutamate, aspartate, gamma-aminobutyric acid (GABA) and taurine) and regional blood flow in the striatum of spontaneously hypertensive rats (SHRs) were monitored during cerebral ischemia elicited by bilateral carotid artery occlusion for 40 min and recirculation. Striatal blood flow and basal levels of amino acids were not affected by direct perfusion of CCPA (10 microM or 100 microM). During ischemia, concentrations of glutamate, aspartate, GABA and taurine increased up to 37-, 30-, 96- and 31-fold, respectively, when vehicle alone was administered. Administration of CCPA did not affect the changes in regional blood flow during ischemia and reperfusion. Perfusion of CCPA (100 microM), however, significantly attenuated the ischemia-evoked release of aspartate (by 70%) and glutamate (by 73%). The ischemia-induced increase of GABA tended to be decreased by CCPA, although it was not statistically significant. In contrast, both low and high concentrations of CCPA had little effect on the release of taurine during ischemia. These results suggest that stimulation of adenosine A1 receptors selectively attenuated the ischemia-evoked release of excitatory amino acids, but not of inhibitory amino acids without affecting blood flow. This modulation of the release of amino acids by adenosine A1 receptor agonists may play a protective role against ischemic neuronal damage.

  18. 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.

  19. Effect of androgens on sexual differentiation of pituitary gamma-aminobutyric acid receptor subunit GABA(B) expression.

    PubMed

    Bianchi, María S; Catalano, Paolo N; Bonaventura, María M; Silveyra, Patricia; Bettler, Bernhard; Libertun, Carlos; Lux-Lantos, Victoria A R

    2004-01-01

    Previous work demonstrated a sexually dimorphic ontogenic expression of gamma-aminobutyric acid receptors (GABA(B)R) in rat pituitary. As sex steroids determine sex-specific expression patterns, we now studied the effect of sex hormones on pituitary GABA(B)R expression. GABA(B)R subunits, measured by Western blot and by semi-quantitative RT-PCR and luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone measured by RIA were determined in two experimental designs: First experimental design: 8- and 15-day-old females (8F, 15F); 8F and 15F treated with 100 mug testosterone propionate (TP) on day 1 of life (8F100TP, 15F100TP), 8- and 15-day-old males (8M, 15M) and 8M and 15M castrated on day 1 (8MC, 15MC). Second experimental design: 8-day-old female and male animals: 8F, 8F100TP, 8F treated with 1 mug/day TP on days 1-4 (8F1TP), 8F treated with the androgen antagonist Flutamide (Flut: 2.5 mg/100 g BW of pregnant mother on days E17-E23) (8F-Flut), 8M, 8MC, 8M treated with Flut as above (8M-Flut) and 8MC-Flut. In these animals, in addition, GABA, glutamate, aspartate and taurine were measured by HPLC in hypothalami and cortex. In the first set of experiments, GABA(B1)R mRNA/protein expression was higher in 8F than in 15F, 8M or 15M. In 8F100TP, GABA(B1)R mRNA/protein decreased to male levels. TP treatment did not alter GABA(B1)R expression in 15F. There was no difference in GABA(B1)R expression between 8M and 15M and neonatal castration did not modify its expression. In the second set of experiments, TP (1 mug) or Flut did not modify GABA(B1)R in 8F, while 100 microg TP continued to decrease GABA(B1)R expression. In 8M, Flut, alone or with castration, increased GABA(B1)R mRNA/protein expression to 8F. Hypothalamic GABA content followed the same pattern as pituitary GABA(B)R expression in 8-day-old animals, suggesting a cross-regulation. With regard to hormonal levels, 100 microg, but not 1 microg TP altered gonadotropins at 8 days, although both

  20. Inhibitory effects of acetylsalicylic acid on exocrine pancreatic carcinogenesis.

    PubMed

    Yıldız, H; Oztas, H; Yıldız, D; Koc, A; Kalipci, E

    2013-05-01

    We investigated short (6 months) and long (12 months) term inhibitory effects of low (200 ppm) and high (400 ppm) dosages of acetylsalicylic acid (aspirin) on exocrine pancreatic carcinogenesis. It is known that exocrine pancreatic carcinogenesis can be detected by the presence of atypical acinar cell foci (AACF) in pancreas. We investigated possible inhibitory effects of acetylsalicylic acid in an azaserine-treated rat model. AACF were produced in rats by injection with azaserine according to previous studies. Our findings showed that the number, volume and diameter of pancreatic AACF were reduced after acetylsalicylic acid application. These observations suggest that acetylsalicylic acid may exert a protective effect against neoplastic development of pancreatic acinar cells in azaserine injected rats. Our findings corroborate reports in the literature concerning the effects of aspirin in reducing neoplastic development.

  1. Dopamine-dependent hyperactivity in the rat following manipulation of GABA mechanisms in the region of the nucleus accumbens.

    PubMed

    Pycock, C J; Horton, R W

    1979-01-01

    The effect of manipulation of GABA mechanisms in the region of the nucleus accumbens on dopamine-dependent locomotor hyperactivity in the rat has been studied. Two models of hyperactivity were used: (1) the injection of dopamine into the region of the nucleus accumbens in nialamide-pretreated animals and (2) the systemic administration of d-amphetamine. Both GABA and the GABA agonist 3-aminopropane sulphonic acid (3-APS) depressed hyperactivity in a dose-related manner. High concentrations of GABA (greater than 100 micrograms) were required to produce a significant effect and the response was short-lived possibly reflecting the efficient GABA inactivating mechanisms. 3-APS proved to be approximately 10 times more potent as compared to GABA in the dopamine-accumbens hyperactivity model. Conversely GABA receptor antagonism with low doses of either picrotoxin or bicuculline enhanced the mild locomotor response induced by a low dose of dopamine injected into the nucleus accumbens. However such results were difficult to evaluate fairly as higher doses of the GABA antagonists resulted in varying degrees of generalized seizures. Blockade of GABA uptake systems with cis-1, 3-aminocyclohexane carboxylic acid (ACHC), nipecotic acid or beta-alanine within the region of the nucleus accumbens produced dose-related depression of dopamine-dependent hyperactivity in both models. GABA uptake blockade (nipecotic acid) significantly enhanced the GABA-mediated depression of hyperactivity induced by bilateral injection of dopamine into the nucleus accumbens. The results demonstrate an inhibitory action of GABA and drugs facilitating GABA-ergic transmission on dopamine-dependent hyperactivity in the rat. Although open to criticisms of not being able to distinguish between true GABA effects and the results of non-specific neuronal depression the hyperactivity model underlines the potency of the GABA uptake blocking compounds and their possible potential for future clinical use.

  2. Urease inhibitory activities of β-boswellic acid derivatives

    PubMed Central

    2013-01-01

    Background and the purpose of the study Boswellia carterii have been used in traditional medicine for many years for management different gastrointestinal disorders. In this study, we wish to report urease inhibitory activity of four isolated compound of boswellic acid derivative. Methods 4 pentacyclic triterpenoid acids were isolated from Boswellia carterii and identified by NMR and Mass spectroscopic analysis (compounds 1, 3-O-acetyl-9,11-dehydro-β-boswellic acid; 2, 3-O-acetyl-11-hydroxy-β-boswellic acid; 3. 3-O- acetyl-11-keto-β-boswellic acid and 4, 11-keto-β-boswellic acid. Their inhibitory activity on Jack bean urease were evaluated. Docking and pharmacophore analysis using AutoDock 4.2 and Ligandscout 3.03 programs were also performed to explain possible mechanism of interaction between isolated compounds and urease enzyme. Results It was found that compound 1 has the strongest inhibitory activity against Jack bean urease (IC50 = 6.27 ± 0.03 μM), compared with thiourea as a standard inhibitor (IC50 = 21.1 ± 0.3 μM). Conclusion The inhibition potency is probably due to the formation of appropriate hydrogen bonds and hydrophobic interactions between the investigated compounds and urease enzyme active site and confirms its traditional usage. PMID:23351363

  3. Identification and functional characterization of a dual GABA/taurine transporter in the bullfrog retinal pigment epithelium

    PubMed Central

    1995-01-01

    Intracellular microelectrodes, fluorescence imaging, and radiotracer flux techniques were used to investigate the physiological response of the retinal pigment epithelium (RPE) to the major retinal inhibitory neurotransmitter, gamma-aminobutyric acid (GABA). GABA is released tonically in the dark by amphibian horizontal cells, but is not taken up by the nearby Muller cells. Addition of GABA to the apical bath produced voltage responses in the bullfrog RPE that were not blocked nor mimicked by any of the major GABA-receptor antagonists or agonists. Nipecotic acid, a substrate for GABA transport, inhibited the voltage effects of GABA. GABA and nipecotic acid also inhibited the voltage effects of taurine, suggesting that the previously characterized beta- alanine sensitive taurine carrier also takes up GABA. The voltage responses of GABA, taurine, nipecotic acid, and beta-alanine all showed first-order saturable kinetics with the following Km's: GABA (Km = 160 microM), beta-alanine (Km = 250 microM), nipecotic acid (Km = 420 microM), and taurine (Km = 850 microM). This low affinity GABA transporter is dependent on external Na, partially dependent on external Cl, and is stimulated in low [K]o, which approximates subretinal space [K]o during light onset. Apical GABA also produced a significant conductance increase at the basolateral membrane. These GABA-induced conductance changes were blocked by basal Ba2+, suggesting that GABA decreased basolateral membrane K conductance. In addition, the apical membrane Na/K ATPase was stimulated in the presence of GABA. A model for the interaction between the GABA transporter, the Na/K ATPase, and the basolateral membrane K conductance accounts for the electrical effects of GABA. Net apical-to-basal flux of [3H]-GABA was also observed in radioactive flux experiments. The present study shows that a high capacity GABA uptake mechanism with unique pharmacological properties is located at the RPE apical membrane and could play an

  4. Synthesis and characterization of N,N-dichlorinated amino acids: taurine, homotaurine, GABA and L-leucine.

    PubMed

    van Gelder, N M; Bowers, R J

    2001-06-01

    Epilepsy, trauma and other circumstances leading to hyperexcitable conditions in the CNS tend neurochemically to be associated with excessive stimulated release of glutamic acid and/or a failure of GABA modulated inhibition. Somewhat to a lesser extent, taurine and its homologue homotaurine, have also been shown to antagonize the excitatory actions of glutamic acid. Here we report the successful synthesis and isolation in pure form of N,N-dichlorinated GABA, taurine, homotaurine and leucine. These compounds are much more lipophilic than their parent compounds and may therefore more readily penetrate the blood-brain barrier systems into the neural tissue, where they can be easily dechlorinated. Very preliminary biological testing shows that this may indeed occur. The synthesis and purification methodology will likely also be applicable to a number of other amino acids as well as certain peptides or selected proteins.

  5. The activation of cannabinoid receptors in striatonigral GABAergic neurons inhibited GABA uptake.

    PubMed

    Romero, J; de Miguel, R; Ramos, J A; Fernández-Ruiz, J J

    1998-01-01

    Cannabinoid receptors (CNRs) in basal ganglia are located on striatal efferent neurons which are gamma-aminobutiric acid (GABA)-containing neurons. Recently, we have demonstrated that CN-induced motor inhibition is reversed by GABA-B, but not GABA-A, receptor antagonists, presumably indicating that the activation of CNRs in striatal outflow nuclei, mainly in the substantia nigra, should be followed by an increase of GABA concentrations into the synaptic cleft of GABA-B receptor synapses. The present study was designed to examine whether this was originated by increasing GABA synthesis and/or release or by decreasing GABA uptake. We analyzed: (i) GABA synthesis, by measuring the activity of glutamic acid decarboxylase (GAD) and GABA contents in brain regions that contain striatonigral GABAergic neurons, after in vivo administration of CNs and/or the CNR antagonist SR141716; (ii) [3H]GABA release in vitro in the presence or the absence of a synthetic CN agonist, HU-210, by using perifusion of small fragments of substantia nigra; and (iii) [3H]GABA uptake in vitro in the presence or the absence of WIN-55,212-2, by using synaptosomes obtained from either globus pallidus or substantia nigra. Results were as follows. Delta9-tetrahydrocannabinol (delta9-THC) and HU-210, did not alter neither GAD activity nor GABA contents in both the striatum and the ventral midbrain at any of the two times tested, thus suggesting that CNs apparently failed to change GABA synthesis in striatonigral GABAergic neurons. A similar lack of effect of HU-210 on in vitro [3H]GABA release, both basal and K+-evoked, was seen when this CN was added to perifused substantia nigra fragments, also suggesting no changes at the level of GABA release. However, when synaptosome preparations obtained from the substantia nigra were incubated in the presence of WIN-55,212-2, a decrease in [3H]GABA uptake could be measured. This lowering effect was specific of striatonigral GABAergic neurons since it was not

  6. α4βδ GABA(A) receptors are high-affinity targets for γ-hydroxybutyric acid (GHB).

    PubMed

    Absalom, Nathan; Eghorn, Laura F; Villumsen, Inge S; Karim, Nasiara; Bay, Tina; Olsen, Jesper V; Knudsen, Gitte M; Bräuner-Osborne, Hans; Frølund, Bente; Clausen, Rasmus P; Chebib, Mary; Wellendorph, Petrine

    2012-08-14

    γ-Hydroxybutyric acid (GHB) binding to brain-specific high-affinity sites is well-established and proposed to explain both physiological and pharmacological actions. However, the mechanistic links between these lines of data are unknown. To identify molecular targets for specific GHB high-affinity binding, we undertook photolinking studies combined with proteomic analyses and identified several GABA(A) receptor subunits as possible candidates. A subsequent functional screening of various recombinant GABA(A) receptors in Xenopus laevis oocytes using the two-electrode voltage clamp technique showed GHB to be a partial agonist at αβδ- but not αβγ-receptors, proving that the δ-subunit is essential for potency and efficacy. GHB showed preference for α4 over α(1,2,6)-subunits and preferably activated α4β1δ (EC(50) = 140 nM) over α4β(2/3)δ (EC(50) = 8.41/1.03 mM). Introduction of a mutation, α4F71L, in α4β1(δ)-receptors completely abolished GHB but not GABA function, indicating nonidentical binding sites. Radioligand binding studies using the specific GHB radioligand [(3)H](E,RS)-(6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylidene)acetic acid showed a 39% reduction (P = 0.0056) in the number of binding sites in α4 KO brain tissue compared with WT controls, corroborating the direct involvement of the α4-subunit in high-affinity GHB binding. Our data link specific GHB forebrain binding sites with α4-containing GABA(A) receptors and postulate a role for extrasynaptic α4δ-containing GABA(A) receptors in GHB pharmacology and physiology. This finding will aid in elucidating the molecular mechanisms behind the proposed function of GHB as a neurotransmitter and its unique therapeutic effects in narcolepsy and alcoholism.

  7. Inhibitory Effect of Oleic Acid on Octanoylated Ghrelin Production.

    PubMed

    Oiso, Shigeru; Nobe, Miyuki; Iwasaki, Syuhei; Nii, Wakana; Goto, Natsumi; Seki, Yukari; Nakajima, Kensuke; Nakamura, Kazuo; Kariyazono, Hiroko

    2015-01-01

    Ghrelin is a growth hormone-releasing peptide that also displays orexigenic activity. Since serine-3 acylation with octanoylate (octanoylation) is essential for the orexigenic activity of ghrelin, suppression of octanoylation could lead to amelioration or prevention of obesity. To enable the exploration of inhibitors of octanoylated ghrelin production, we developed a cell-based assay system using AGS-GHRL8 cells, in which octanoylated ghrelin concentration increases in the presence of octanoic acid. Using this assay system, we investigated whether fatty acids contained in foods or oils, such as acetic acid, stearic acid, oleic acid, linoleic acid, and α-linolenic acid, have inhibitory effects on octanoylated ghrelin production. Acetic acid did not suppress the increase in octanoylated ghrelin production in AGS-GHRL8 cells, which was induced by the addition of octanoic acid. However, stearic acid, oleic acid, linoleic acid, and α-linolenic acid significantly suppressed octanoylated ghrelin production, with the effect of oleic acid being the strongest. Additionally, oleic acid decreased the serum concentration of octanoylated ghrelin in mice. The serum concentration of des-acyl ghrelin (without acyl modification) was also decreased, but the decrease was smaller than that of octanoylated ghrelin. Decreased octanoylated ghrelin production likely resulted from post-translational ghrelin processing, as there were no significant differences in gene expression in the stomach between oleic acid-treated mice and controls. These results suggest that oleic acid is a potential inhibitor of octanoylated ghrelin production and that our assay system is a valuable tool for screening compounds with suppressive effects on octanoylated ghrelin production.

  8. Modes and nodes explain the mechanism of action of vortioxetine, a multimodal agent (MMA): modifying serotonin's downstream effects on glutamate and GABA (gamma amino butyric acid) release.

    PubMed

    Stahl, Stephen M

    2015-08-01

    Vortioxetine is an antidepressant with multiple pharmacologic modes of action at targets where serotonin neurons connect with other neurons. These actions modify the release of both glutamate and GABA (gamma amino butyric acid) within various brain circuits.

  9. Focal uncaging of GABA reveals a temporally defined role for GABAergic inhibition during appetitive associative olfactory conditioning in honeybees.

    PubMed

    Raccuglia, Davide; Mueller, Uli

    2013-07-16

    Throughout the animal kingdom, the inhibitory neurotransmitter γ-aminobutyric acid (GABA) is a key modulator of physiological processes including learning. With respect to associative learning, the exact time in which GABA interferes with the molecular events of learning has not yet been clearly defined. To address this issue, we used two different approaches to activate GABA receptors during appetitive olfactory conditioning in the honeybee. Injection of GABA-A receptor agonist muscimol 20 min before but not 20 min after associative conditioning affects memory performance. These memory deficits were attenuated by additional training sessions. Muscimol has no effect on sensory perception, odor generalization, and nonassociative learning, indicating a specific role of GABA during associative conditioning. We used photolytic uncaging of GABA to identify the GABA-sensitive time window during the short pairing of the conditioned stimulus (CS) and the unconditioned stimulus (US) that lasts only seconds. Either uncaging of GABA in the antennal lobes or the mushroom bodies during the CS presentation of the CS-US pairing impairs memory formation, while uncaging GABA during the US phase has no effect on memory. Uncaging GABA during the CS presentation in memory retrieval also has no effect. Thus, in honeybee appetitive olfactory learning GABA specifically interferes with the integration of CS and US during associative conditioning and exerts a modulatory role in memory formation depending on the training strength.

  10. Expression of the γ-Aminobutyric Acid (GABA) Plasma Membrane Transporter-1 in Monkey and Human Retina

    PubMed Central

    Casini, Giovanni; Rickman, Dennis W.; Brecha, Nicholas C.

    2010-01-01

    Purpose To determine the expression pattern of the predominant γ-aminobutyric acid (GABA) plasma membrane transporter GAT-1 in Old World monkey (Macaca mulatta) and human retina. Methods GAT-1 was localized in retinal sections by using immunohistochemical techniques with fluorescence and confocal microscopy. Double-labeling studies were performed with the GAT-1 antibody using antibodies to GABA, vasoactive intestinal polypeptide (VIP), tyrosine hydroxylase (TH), and the bipolar cell marker Mab115A10. Results The pattern of GAT-1 immunostaining was similar in human and monkey retinas. Numerous small immunoreactive somata were in the inner nuclear layer (INL) and were present rarely in the inner plexiform layer (IPL) of all retinal regions. Medium GAT-1 somata were in the ganglion cell layer in the parafoveal and peripheral retinal regions. GAT-1 fibers were densely distributed throughout the IPL. Varicose processes, originating from both the IPL and somata in the INL, arborized in the outer plexiform layer (OPL), forming a sparse network in all retinal regions, except the fovea. Sparsely occurring GAT-1 processes were in the nerve fiber layer in parafoveal regions and near the optic nerve head but not in the optic nerve. In the INL, 99% of the GAT-1 somata contained GABA, and 66% of the GABA immunoreactive somata expressed GAT-1. GAT-1 immunoreactivity was in all VIP-containing cells, but it was absent in TH-immunoreactive amacrine cells and in Mab115A10 immunoreactive bipolar cells. Conclusions GAT-1 in primate retinas is expressed by amacrine and displaced amacrine cells. The predominant expression of GAT-1 in the inner retina is consistent with the idea that GABA transporters influence neurotransmission and thus participate in visual information processing in the retina. PMID:16565409

  11. 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. GABAB1, GABAB2, GABAA1, and GABAA3 were ubiquitously expressed both on gene and protein level. GABAA2 and GAD65 were undetectable in resting cells, but induced by inflammation. GABAB1 exhibited the highest basal gene expression (6.97 % ± 0.16). IL-1ß markedly increased GABAB2 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.

  12. A Gut Feeling about GABA: Focus on GABAB Receptors

    PubMed Central

    Hyland, Niall P.; Cryan, John F.

    2010-01-01

    γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the body and hence GABA-mediated neurotransmission regulates many physiological functions, including those in the gastrointestinal (GI) tract. GABA is located throughout the GI tract and is found in enteric nerves as well as in endocrine-like cells, implicating GABA as both a neurotransmitter and an endocrine mediator influencing GI function. GABA mediates its effects via GABA receptors which are either ionotropic GABAA or metabotropic GABAB. The latter which respond to the agonist baclofen have been least characterized, however accumulating data suggest that they play a key role in GI function in health and disease. Like GABA, GABAB receptors have been detected throughout the gut of several species in the enteric nervous system, muscle, epithelial layers as well as on endocrine-like cells. Such widespread distribution of this metabotropic GABA receptor is consistent with its significant modulatory role over intestinal motility, gastric emptying, gastric acid secretion, transient lower esophageal sphincter relaxation and visceral sensation of painful colonic stimuli. More intriguing findings, the mechanisms underlying which have yet to be determined, suggest GABAB receptors inhibit GI carcinogenesis and tumor growth. Therefore, the diversity of GI functions regulated by GABAB receptors makes it a potentially useful target in the treatment of several GI disorders. In light of the development of novel compounds such as peripherally acting GABAB receptor agonists, positive allosteric modulators of the GABAB receptor and GABA producing enteric bacteria, we review and summarize current knowledge on the function of GABAB receptors within the GI tract. PMID:21833169

  13. Regulation of (/sup 3/H)GABA release from strips of guinea pig urinary bladder

    SciTech Connect

    Shirakawa, J.; Taniyama, K.; Iwai, S.; Tanaka, C.

    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 by 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.

  14. Effect of antioxidant treatment on spinal GABA neurons in a neuropathic pain model in the mouse.

    PubMed

    Yowtak, June; Wang, Jigong; Kim, Hee Young; Lu, Ying; Chung, Kyungsoon; Chung, Jin Mo

    2013-11-01

    One feature of neuropathic pain is a reduced spinal gamma-aminobutyric acid (GABA)-ergic inhibitory function. However, the mechanisms behind this attenuation remain to be elucidated. This study investigated the involvement of reactive oxygen species in the spinal GABA neuron loss and reduced GABA neuron excitability in spinal nerve ligation (SNL) model of neuropathic pain in mice. The importance of spinal GABAergic inhibition in neuropathic pain was tested by examining the effects of intrathecally administered GABA receptor agonists and antagonists in SNL and naïve mice, respectively. The effects of SNL and antioxidant treatment on GABA neuron loss and functional changes were examined in transgenic GAD67-enhanced green fluorescent protein positive (EGFP+) mice. GABA receptor agonists transiently reversed mechanical hypersensitivity of the hind paw in SNL mice. On the other hand, GABA receptor antagonists made naïve mice mechanically hypersensitive. Stereological analysis showed that the numbers of enhanced green fluorescent protein positive (EGFP+) GABA neurons were significantly decreased in the lateral superficial laminae (I-II) on the ipsilateral L5 spinal cord after SNL. Repeated antioxidant treatments significantly reduced the pain behaviors and prevented the reduction in EGFP+ GABA neurons. The response rate of the tonic firing GABA neurons recorded from SNL mice increased with antioxidant treatment, whereas no change was seen in those recorded from naïve mice, which suggested that oxidative stress impaired some spinal GABA neuron activity in the neuropathic pain condition. Together the data suggest that neuropathic pain, at least partially, is attributed to oxidative stress, which induces both a GABA neuron loss and dysfunction of surviving GABA neurons.

  15. Dual effects of slightly acidic electrolyzed water (SAEW) treatment on the accumulation of γ-aminobutyric acid (GABA) and rutin in germinated buckwheat.

    PubMed

    Hao, Jianxiong; Wu, Tongjiao; Li, Huiying; Wang, Wei; Liu, Haijie

    2016-06-15

    In the present study, the dual effects of slightly acidic electrolyzed water (SAEW) treatment on γ-aminobutyric acid (GABA) and rutin accumulation of germinated buckwheat were evaluated during germination. The results showed that SAEW treatment (pH 5.83, ACC of 20.3 mg/L) could promote the accumulation of GABA and rutin in germinated buckwheat. The GABA and rutin contents of SAEW-germinated buckwheat reached 143.20 and 739.9 mg/100 g respectively, which is significantly higher than those of control (P<0.05). Moreover, SAEW treatment could increase the activity of glutamic acid decarboxylase (GAD) and phenylalanine ammonialyase (PAL) and thus result in the GABA and rutin accumulation of germinated buckwheat. The results suggested that SAEW treatment could promote the rutin accumulation of germinated buckwheat by influencing phenylpropanoid secondary metabolic pathway instead of the inhibition of rutin degrading enzyme (RDE) activity. In addition, SAEW treatment had no adverse impact on the sprouts growth and could reduce the microbial populations of germinated buckwheat during germination.

  16. Inhibition of GABA uptake potentiates the conductance increase produced by GABA-mimetic compounds on single neurones in isolated olfactory cortex slices of the guinea-pig.

    PubMed

    Brown, D A; Scholfield, C N

    1984-09-01

    Membrane potential and input conductance were recorded in single neurones in slices of guinea-pig olfactory cortex in vitro. gamma-Aminobutyric acid (GABA) and GABA-mimetic compounds were applied by bath-perfusion. Potency was measured as the concentration required to double the input conductance. The potency of GABA was increased (i.e. the equi-effective concentrations were reduced) by 15.5 +/- 2.3 times (mean +/- s.e. mean) on reducing external [Na+] from 144 to 20 mmol l-1, by replacement with Mg2+. Corresponding potency changes for other agonists were + 10.8 +/- 2.5 for 3-aminopropanesulphonic acid (3-APS); 3.25 +/- 1.06 for isoguvacine and 2.43 +/- 0.69 for muscimol. Nipecotic acid (0.5 mM) produced the following increases in potency: GABA 2.68 +/- 0.02; 3-aminopropanesulphonic acid, 3.11 +/- 0.07; isoguvacine, 1.92 +/- 0.34; muscimol, 2.24 +/- 0.17. The concentration of GABA in the bathing fluid necessary to double input conductance increased with increasing depth of the recording site from the cut surface. The apparent potency fell 10 times for each 60 micron depth increment up to 150 micron. The recording depth also affected the apparent potency of muscimol and 3-APS but to a lesser extent. Reduction of external [Na+] reduced the depth-dependence of both GABA and 3-APS potency. No clear change in the duration of the recurrent inhibitory postsynaptic conductance could be detected in the presence of 0.5 mmol l-1 nipecotic acid. 6 It is suggested that agonist uptake by a Na+-dependent, nipecotic acid-sensitive mechanism severely attenuates the responses of olfactory neurones to exogenous GABA and to its analogues 3-APS, muscimol and isoguvacine, but has little immediate influence on the duration of the GABA-mediated inhibitory postsynaptic conductance.

  17. Systematic analysis of γ-aminobutyric acid (GABA) metabolism and function in the social amoeba Dictyostelium discoideum.

    PubMed

    Wu, Yuantai; Janetopoulos, Chris

    2013-05-24

    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.

  18. Edited Magnetic Resonance Spectroscopy Detects an Age-Related Decline in Nonhuman Primate Brain GABA Levels

    PubMed Central

    Killiany, Ronald J.

    2016-01-01

    Recent research had shown a correlation between aging and decreasing Gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain. However, how GABA level varies with age in the medial portion of the brain has not yet been studied. The purpose of this study was to investigate the GABA level variation with age focusing on the posterior cingulate cortex, which is the “core hub” of the default mode network. In this study, 14 monkeys between 4 and 21 years were recruited, and MEGA-PRESS MRS was performed to measure GABA levels, in order to explore a potential link between aging and GABA. Our results showed that a correlation between age and GABA+/Creatine ratio was at the edge of significance (r = −0.523, p = 0.081). There was also a near-significant trend between gray matter/white matter ratio and the GABA+/Creatine ratio (r = −0.518, p = 0.0848). Meanwhile, the correlation between age and grey matter showed no significance (r = −0.028, p = 0.93). Therefore, age and gray matter/white matter ratio account for different part of R-squared (adjusted R-squared = 0.5187) as independent variables for predicting GABA levels. Adjusted R-squared is about 0.5 for two independent variables. These findings suggest that there is internal neurochemical variation of GABA levels in the nonhuman primates associated with normal aging and structural brain decline. PMID:27660760

  19. 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.

  20. 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

  1. Design, synthesis and SAR studies of GABA uptake inhibitors derived from 2-substituted pyrrolidine-2-yl-acetic acids.

    PubMed

    Steffan, Tobias; Renukappa-Gutke, Thejavathi; Höfner, Georg; Wanner, Klaus T

    2015-03-15

    In this paper, we disclose the design and synthesis of a series of 2-substituted pyrrolidine-2-yl-acetic acid as core structures and the N-arylalkyl derivatives thereof as potential GABA transport inhibitors. The 2-position in the side chain of pyrrolidine-2-yl-acetic acid derivatives was substituted with alkyl, hydroxy and amino groups to modulate the activity and selectivity to mGAT1 and mGAT4 proteins. SAR studies of the compounds performed for the four mouse GABA transporter proteins (mGAT1-mGAT4) implied significant potencies and subtype selectivities for 2-hydroxy-2-pyrrolidine-2-yl-acetic acid derivatives. The racemate rac-(u)-13c exhibited the highest potency (pIC50 5.67) at and selectivity for mGAT1 in GABA uptake assays. In fact, the potency of rac-(u)-13c at hGAT-1 (pIC50 6.14) was even higher than its potency at mGAT1. These uptake results for rac-(u)-13c are in line with the binding affinities to the aforesaid proteins mGAT1 (pKi 6.99) and hGAT-1 (pKi 7.18) determined by MS Binding Assay based on NO711 as marker quantified by LC-ESI-MS-MS analysis. Interestingly, the 2-hydroxy-2-pyrrolidine-2-yl-acetic acid rac-(u)-13d containing 2-{[tris(4-methoxyphenyl)]methoxy} ethyl group at the nitrogen atom of the pyrrolidine ring showed high potency at mGAT4 and a comparatively better selectivity for this protein (>15 against mGAT3) than the well known mGAT4 uptake inhibitor (S)-SNAP-5114.

  2. Inhibition of GABA release by presynaptic ionotropic GABA receptors in hippocampal CA3.

    PubMed

    Axmacher, Nikolai; Draguhn, Andreas

    2004-02-09

    Vesicular transmitter release can be regulated by transmitter-gated ion channels at presynaptic axon terminals. The central inhibitory transmitter GABA acts on such presynaptic ionotropic receptors in various cells, including inhibitory interneurons. Here we report that GABA-mediated postsynaptic inhibitory currents in CA3 pyramidal cells of rat hippocampal slices are suppressed by agonists of GABAA receptors. The effect is present for both stimulus-induced and miniature IPSCs, indicating a reduction in the probability of vesicular release by presynaptic, action-potential-independent mechanisms. We conclude that the release of GABA from hippocampal CA3 interneurons is regulated by a negative feedback via presynaptic ionotropic GABA autoreceptors.

  3. Disorders of GABA metabolism: SSADH and GABA-transaminase deficiencies.

    PubMed

    Parviz, Mahsa; Vogel, Kara; Gibson, K Michael; Pearl, Phillip L

    2014-11-25

    Clinical disorders known to affect inherited gamma-amino butyric acid (GABA) metabolism are autosomal recessively inherited succinic semialdehyde dehydrogenase and GABA-transaminase deficiency. The clinical presentation of succinic semialdehyde dehydrogenase deficiency includes intellectual disability, ataxia, obsessive-compulsive disorder and epilepsy with a nonprogressive course in typical cases, although a progressive form in early childhood as well as deterioration in adulthood with worsening epilepsy are reported. GABA-transaminase deficiency is associated with a severe neonatal-infantile epileptic encephalopathy.

  4. Determination of theanine, GABA, and other amino acids in green, oolong, black, and Pu-erh teas with dabsylation and high-performance liquid chromatography.

    PubMed

    Syu, Kai-Yang; Lin, Chih-Li; Huang, Hsiu-Chen; Lin, Jen-Kun

    2008-09-10

    Dabsyl chloride (dimethylaminoazobenzene sulfonyl chloride), a useful chromophoric labeling reagent for amino acids and amines, was developed in this laboratory in 1975. Although several methods have been developed to determine various types of amino acids, a quick and easy method of determining theanine, GABA, and other amino acids has not been developed in one HPLC system. In this paper are analyzed the free amino acid contents of theanine and GABA in different teas (green tea, black tea, oolong tea, Pu-erh tea, and GABA tea) with a dabsylation and reverse phase high-performance liquid chromatography (HPLC) system coupled with a detector at 425 nm absorbance. Two reverse phase columns, Hypersil GOLD and Zorbax ODS, were used and gave different resolutions of dabsyl amino acids in the gradient elution program. The data suggest that the tea source or the steps of tea-making may contribute to the theanine contents variations. High theanine contents of high-mountain tea were observed in both green tea and oolong tea. Furthermore, the raw (natural fermented) Pu-erh tea contained more theanine than ripe (wet fermented) Pu-erh tea, and the GABA contents in normal teas were generally lower than that in GABA tea.

  5. Methamphetamine-evoked depression of GABA(B) receptor signaling in GABA neurons of the VTA.

    PubMed

    Padgett, Claire L; Lalive, Arnaud L; Tan, Kelly R; Terunuma, Miho; Munoz, Michaelanne B; Pangalos, Menelas N; Martínez-Hernández, José; Watanabe, Masahiko; Moss, Stephen J; Luján, Rafael; Lüscher, Christian; Slesinger, Paul A

    2012-03-08

    Psychostimulants induce neuroadaptations in excitatory and fast inhibitory transmission in the ventral tegmental area (VTA). Mechanisms underlying drug-evoked synaptic plasticity of slow inhibitory transmission mediated by GABA(B) receptors and G protein-gated inwardly rectifying potassium (GIRK/Kir(3)) channels, however, are poorly understood. Here, we show that 1 day after methamphetamine (METH) or cocaine exposure both synaptically evoked and baclofen-activated GABA(B)R-GIRK currents were significantly depressed in VTA GABA neurons and remained depressed for 7 days. Presynaptic inhibition mediated by GABA(B)Rs on GABA terminals was also weakened. Quantitative immunoelectron microscopy revealed internalization of GABA(B1) and GIRK2, which occurred coincident with dephosphorylation of serine 783 (S783) in GABA(B2), a site implicated in regulating GABA(B)R surface expression. Inhibition of protein phosphatases recovered GABA(B)R-GIRK currents in VTA GABA neurons of METH-injected mice. This psychostimulant-evoked impairment in GABA(B)R signaling removes an intrinsic brake on GABA neuron spiking, which may augment GABA transmission in the mesocorticolimbic system.

  6. Novel functions of GABA signaling in adult neurogenesis

    PubMed Central

    PONTES, Adalto; ZHANG, Yonggang; HU, Wenhui

    2013-01-01

    Neurotransmitter gamma-aminobutiric acid (GABA) through ionotropic GABAA and metabotropic GABAB receptors plays key roles in modulating the development, plasticity and function of neuronal networks. GABA is inhibitory in mature neurons but excitatory in immature neurons, neuroblasts and neural stem/progenitor cells (NSCs/NPCs). The switch from excitatory to inhibitory occurs following the development of glutamatergic synaptic input and results from the dynamic changes in the expression of Na+/K+/2Cl− co-transporter NKCC1 driving Cl− influx and neuron-specific K+/Cl− co-transporter KCC2 driving Cl− efflux. The developmental transition of KCC2 expression is regulated by Disrupted-in-Schizophrenia 1 (DISC1) and brain-derived neurotrophic factor (BDNF) signaling. The excitatory GABA signaling during early neurogenesis is important to the activity/experience-induced regulation of NSC quiescence, NPC proliferation, neuroblast migration and newborn neuronal maturation/functional integration. The inhibitory GABA signaling allows for the sparse and static functional networking essential for learning/memory development and maintenance. PMID:24285940

  7. GABA and glycine are protective to mature but toxic to immature rat cortical neurons under hypoxia.

    PubMed

    Zhao, Peng; Qian, Hong; Xia, Ying

    2005-07-01

    Although recent studies suggest that gamma-aminobutyric acid (GABA) and glycine may be 'inhibitory' to mature neurons, but 'excitatory' to immature neurons under normoxia, it is unknown whether inhibitory neurotransmitters are differentially involved in neuronal response to hypoxia in immature and mature neurons. In the present study, we exposed rat cortical neurons to hypoxia (1% O2) and examined the effects of three major inhibitory neurotransmitters (GABA, glycine and taurine) on the hypoxic neurons at different neuronal ages [days in vitro (DIV)4-20]. Our data showed that the cortical neurons expressed both GABA(A) and glycine receptors with differential developmental profiles. GABA (10-2000 microm) was neuroprotective to hypoxic neurons of DIV20, but enhanced hypoxic injury in neurons of GABA. However, higher concentrations of glycine (1000-2000 microm) for long-term exposure (48-72 h) displayed neuroprotection at all ages (DIV4-20). Taurine (10-2000 microm), unlike GABA and glycine, displayed protection only in DIV4 neurons, and was slightly toxic to neurons>DIV4. In comparison with delta-opioid receptor (DOR)-induced protection in DIV20 neurons exposed to 72 h of hypoxia, glycine-induced protection was weaker than that of DOR but stronger than that of GABA and taurine. These data suggest that the effects of the inhibitory neurotransmitters on hypoxic cortical neurons are age-dependent, with GABA and glycine being neurotoxic to immature neurons and neuroprotective to mature neurons.

  8. Stable isotope dilution HILIC-MS/MS method for accurate quantification of glutamic acid, glutamine, pyroglutamic acid, GABA and theanine in mouse brain tissues.

    PubMed

    Inoue, Koichi; Miyazaki, Yasuto; Unno, Keiko; Min, Jun Zhe; Todoroki, Kenichiro; Toyo'oka, Toshimasa

    2016-01-01

    In this study, we developed the stable isotope dilution hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS) technique for the accurate, reasonable and simultaneous quantification of glutamic acid (Glu), glutamine (Gln), pyroglutamic acid (pGlu), γ-aminobutyric acid (GABA) and theanine in mouse brain tissues. The quantification of these analytes was accomplished using stable isotope internal standards and the HILIC separating mode to fully correct the intramolecular cyclization during the electrospray ionization. It was shown that linear calibrations were available with high coefficients of correlation (r(2)  > 0.999, range from 10 pmol/mL to 50 mol/mL). For application of the theanine intake, the determination of Glu, Gln, pGlu, GABA and theanine in the hippocampus and central cortex tissues was performed based on our developed method. In the region of the hippocampus, the concentration levels of Glu and pGlu were significantly reduced during reality-based theanine intake. Conversely, the concentration level of GABA increased. This result showed that transited theanine has an effect on the metabolic balance of Glu analogs in the hippocampus.

  9. Gestational changes of GABA levels and GABA binding in the human uterus

    SciTech Connect

    Erdoe, S.L.; Villanyi, P.; Laszlo, A.

    1989-01-01

    The concentrations of gamma-aminobutyric acid (GABA), the activities of L-glutamate decarboxylase and GABA-transaminase, and the nature of the sodium-independent binding of GABA were examined in uterine tissue pieces obtained surgically from pregnant and non-pregnant women. GABA concentrations were reduced, while the activity of GABA-transaminase and the specific binding of (/sup 3/H)GABA significantly increased in specimens from pregnant subjects. These findings suggest some gestation-related functional role for the GABA system in the human uterus.

  10. Role of a gamma-aminobutryic acid (GABA) receptor mutation in the evolution and spread of Diabrotica virgifera virgifera resistance to cyclodiene insecticides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An alanine to serine amino acid substitution within the Rdl subunit of the gamma-aminobutyric acid (GABA) receptor confers resistance to cyclodiene insecticides in many species. The corn rootworm, Diabrotica virgifera virgifera, is a damaging pest of cultivated corn that was partially controlled by ...

  11. Parkinson's Disease and Neurodegeneration: GABA-Collapse Hypothesis

    PubMed Central

    Błaszczyk, Janusz W.

    2016-01-01

    Neurodegenerative diseases constitute a heterogeneous group of age-related disorders that are characterized by a slow but irreversible deterioration of brain functions. Evidence accumulated over more than two decades has implicated calcium-related homeostatic mechanisms, giving rise to the Ca2+ hypothesis of brain aging and, ultimately, cell death. Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter within the central (CNS), peripheral and enteric nervous systems. It appears to be involved in a wide variety of physiological functions within and outside the nervous system, that are maintained through a complex interaction between GABA and calcium-dependent neurotransmission and cellular metabolic functions. Within CNS the Ca2+/GABA mechanism stabilizes neuronal activity both at cellular and systemic levels. Decline in the Ca2+/GABA control initiates several cascading processes leading to both weakened protective barriers (in particular the blood-brain barrier) and accumulations of intracellular deposits of calcium and Lewy bodies. Linking such a vital mechanism of synaptic transmission with metabolism (both at cellular and tissue level) by means of a common reciprocal Ca2+/GABA inhibition results in a fragile balance, which is prone to destabilization and auto-destruction. The GABA decline etiology proposed here appears to apply to all human neurodegenerative processes initiated by abnormal intracellular calcium levels. Therefore, the original description of Parkinson's disease (PD) as due to the selective damage of dopaminergic neurons in the mesencephalon should be updated into the concept of a severe multisystemic neurodegenerative disorder of the nervous system, whose clinical symptoms reflect the localization and progression of the most advanced GABA pathology. A future and more complete therapeutic approach to PD should be aimed first at slowing (or stopping) the progression of Ca2+/GABA functional decline. PMID:27375426

  12. Psychological stress-reducing effect of chocolate enriched with gamma-aminobutyric acid (GABA) in humans: assessment of stress using heart rate variability and salivary chromogranin A.

    PubMed

    Nakamura, H; Takishima, T; Kometani, T; Yokogoshi, H

    2009-01-01

    We studied the psychological stress-reducing effect of chocolate enriched with gamma-aminobutyric acid (GABA), on stress induced by an arithmetic task using changes of heart rate variability (HRV) and salivary chromogranin A (CgA). Subjects ingested 10 g chocolate enriched with 28 mg GABA (GABA chocolate); 15 min after the ingestion, subjects were assigned an arithmetic task for 15 min. After the task, an electrocardiogram was recorded and saliva samples were collected. HRV was determined from the electrocardiogram, and the activity of the autonomic nervous system was estimated through HRV. The CgA concentration of all saliva samples, an index for acute psychological stress, was measured. From HRV, those taking GABA chocolate made a quick recovery to the normal state from the stressful state. The CgA value after the task in those taking GABA chocolate did not increased in comparison with that before ingestion. From these results, GABA chocolate was considered to have a psychological stress-reducing effect.

  13. Enhancing Contents of γ-Aminobutyric Acid (GABA) and Other Micronutrients in Dehulled Rice during Germination under Normoxic and Hypoxic Conditions.

    PubMed

    Ding, Junzhou; Yang, Tewu; Feng, Hao; Dong, Mengyi; Slavin, Margaret; Xiong, Shanbai; Zhao, Siming

    2016-02-10

    Biofortification of staple grains with high contents of essential micronutrients is an important strategy to overcome micronutrient malnutrition. However, few attempts have targeted at γ-aminobutyric acid (GABA), a functional nutrient for aging populations. In this study, two rice cultivars, Heinuo and Xianhui 207, were used to investigate changes in GABA and other nutritional compounds of dehulled rice after germination under normoxic and hypoxic conditions. Forty-one metabolites were identified in both cultivars treated by normoxic germination, whereas the germinated dehulled rice of Heinuo and Xianhui 207 under hypoxic treatment had 43 and 41 metabolites identified, respectively. GABA increased in dehulled rice after germination, especially under hypoxia. Meanwhile, a number of other health-beneficial and/or flavor-related compounds such as lysine and d-mannose increased after the hypoxic treatment. The accumulation of GABA exhibited genotype-specific modes in both normoxic and hypoxic treatments. With regard to GABA production, Xianhui 207 was more responsive to the germination process than Heinuo, whereas Heinuo was more responsive to hypoxia than Xianhui 207. This study provides a promising approach to biofortify dehulled rice with increased GABA and other nutrients through metabolomic-based regulation.

  14. Positive feedback regulation between gamma-aminobutyric acid type A (GABA(A)) receptor signaling and brain-derived neurotrophic factor (BDNF) release in developing neurons.

    PubMed

    Porcher, Christophe; Hatchett, Caroline; Longbottom, Rebecca E; McAinch, Kristina; Sihra, Talvinder S; Moss, Stephen J; Thomson, Alex M; Jovanovic, Jasmina N

    2011-06-17

    During the early development of the nervous system, γ-aminobutyric acid (GABA) type A receptor (GABA(A)R)-mediated signaling parallels the neurotrophin/tropomyosin-related kinase (Trk)-dependent signaling in controlling a number of processes from cell proliferation and migration, via dendritic and axonal outgrowth, to synapse formation and plasticity. Here we present the first evidence that these two signaling systems regulate each other through a complex positive feedback mechanism. We first demonstrate that GABA(A)R activation leads to an increase in the cell surface expression of these receptors in cultured embryonic cerebrocortical neurons, specifically at the stage when this activity causes depolarization of the plasma membrane and Ca(2+) influx through L-type voltage-gated Ca(2+) channels. We further demonstrate that GABA(A)R activity triggers release of the brain-derived neurotrophic factor (BDNF), which, in turn by activating TrkB receptors, mediates the observed increase in cell surface expression of GABA(A)Rs. This BDNF/TrkB-dependent increase in surface levels of GABA(A)Rs requires the activity of phosphoinositide 3-kinase (PI3K) and protein kinase C (PKC) and does not involve the extracellular signal-regulated kinase (ERK) 1/2 activity. The increase in GABA(A)R surface levels occurs due to an inhibition of the receptor endocytosis by BDNF, whereas the receptor reinsertion into the plasma membrane remains unaltered. Thus, GABA(A)R activity is a potent regulator of the BDNF release during neuronal development, and at the same time, it is strongly enhanced by the activity of the BDNF/TrkB/PI3K/PKC signaling pathway.

  15. GABA-ergic neurons in the leach central nervous system

    SciTech Connect

    Cline, H.T.

    1985-01-01

    GABA is a candidate for an inhibitory neurotransmitter in the leech central nervous system because of the well-documented inhibitory action of GABA in other invertebrates. To demonstrate that GABA meets the criteria used to identify a substance as a neurotransmitter, the author examined GABA metabolism and synaptic interactions of inhibitory motor neurons in two leech species, Hirudo medicinalis and Haementeria ghilianii. Segmental ganglia of the leech ventral nerve cord and identified inhibitors have the capacity to synthesize GABA when incubated in the presence of the precursor glutamate. Application of GABA to cell bodies of excitatory motor neurons or muscle fibers innervated by the inhibitors hyperpolarizes the membrane potential of the target cell and activates a chloride ion conductance channel, similar to the inhibitory membrane response following intracellular stimulation of the inhibitor. Bicuculline methiodide (5 x 10/sup -5/M), GABA receptor antagonist, blocks reversibly the response to applied GABA and the inhibitory synaptic inputs onto the postsynaptic neurons or muscle fibers without interfering with their excitatory inputs. Furthermore, the inhibitors are included among approximately 25 neurons per segmental ganglion that take up GABA by a high affinity uptake system, as revealed by /sup 3/H-GABA-autoradiography. The development of the capacities to synthesize and to take up GABA were examined in leech embryos. The embryos are able to synthesize GABA at early stages of the development of the nervous system, before any neurons have extended neutrites.

  16. Natural and Synthetic Variants of the Tricarboxylic Acid Cycle in Cyanobacteria: Introduction of the GABA Shunt into Synechococcus sp. PCC 7002

    PubMed Central

    Zhang, Shuyi; Qian, Xiao; Chang, Shannon; Dismukes, G. C.; Bryant, Donald A.

    2016-01-01

    For nearly half a century, it was believed that cyanobacteria had an incomplete tricarboxylic acid (TCA) cycle, because 2-oxoglutarate dehydrogenase (2-OGDH) was missing. Recently, a bypass route via succinic semialdehyde (SSA), which utilizes 2-oxoglutarate decarboxylase (OgdA) and succinic semialdehyde dehydrogenase (SsaD) to convert 2-oxoglutarate (2-OG) into succinate, was identified, thus completing the TCA cycle in most cyanobacteria. In addition to the recently characterized glyoxylate shunt that occurs in a few of cyanobacteria, the existence of a third variant of the TCA cycle connecting these metabolites, the γ-aminobutyric acid (GABA) shunt, was considered to be ambiguous because the GABA aminotransferase is missing in many cyanobacteria. In this study we isolated and biochemically characterized the enzymes of the GABA shunt. We show that N-acetylornithine aminotransferase (ArgD) can function as a GABA aminotransferase and that, together with glutamate decarboxylase (GadA), it can complete a functional GABA shunt. To prove the connectivity between the OgdA/SsaD bypass and the GABA shunt, the gadA gene from Synechocystis sp. PCC 6803 was heterologously expressed in Synechococcus sp. PCC 7002, which naturally lacks this enzyme. Metabolite profiling of seven Synechococcus sp. PCC 7002 mutant strains related to these two routes to succinate were investigated and proved the functional connectivity. Metabolite profiling also indicated that, compared to the OgdA/SsaD shunt, the GABA shunt was less efficient in converting 2-OG to SSA in Synechococcus sp. PCC 7002. The metabolic profiling study of these two TCA cycle variants provides new insights into carbon metabolism as well as evolution of the TCA cycle in cyanobacteria. PMID:28018308

  17. Drug interactions at GABA(A) receptors.

    PubMed

    Korpi, Esa R; Gründer, Gerhard; Lüddens, Hartmut

    2002-06-01

    Neurotransmitter receptor systems have been the focus of intensive pharmacological research for more than 20 years for basic and applied scientific reasons, but only recently has there been a better understanding of their key features. One of these systems includes the type A receptor for the gamma-aminobutyric acid (GABA), which forms an integral anion channel from a pentameric subunit assembly and mediates most of the fast inhibitory neurotransmission in the adult vertebrate central nervous system. Up to now, depending on the definition, 16-19 mammalian subunits have been cloned and localized on different genes. Their assembly into proteins in a poorly defined stoichiometry forms the basis of functional and pharmacological GABA(A) receptor diversity, i.e. the receptor subtypes. The latter has been well documented in autoradiographic studies using ligands that label some of the receptors' various binding sites, corroborated by recombinant expression studies using the same tools. Significantly less heterogeneity has been found at the physiological level in native receptors, where the subunit combinations have been difficult to dissect. This review focuses on the characteristics, use and usefulness of various ligands and their binding sites to probe GABA(A) receptor properties and to gain insight into the biological function from fish to man and into evolutionary conserved GABA(A) receptor heterogeneity. We also summarize the properties of the novel mouse models created for the study of various brain functions and review the state-of-the-art imaging of brain GABA(A) receptors in various human neuropsychiatric conditions. The data indicate that the present ligands are only partly satisfactory tools and further ligands with subtype-selective properties are needed for imaging purposes and for confirming the behavioral and functional results of the studies presently carried out in gene-targeted mice with other species, including man.

  18. Inhibitory effects of tannic acid on fatty acid synthase and 3T3-L1 preadipocyte.

    PubMed

    Fan, Huijin; Wu, Dan; Tian, Weixi; Ma, Xiaofeng

    2013-07-01

    Tannic acid is a hydrolyzable tannin that exists in many widespread edible plants with a variety of biological activities. In this study, we found that tannic acid potently inhibited the activity of fatty acid synthase (FAS) in a concentration-dependent manner with a half-inhibitory concentration value (IC50) of 0.14 microM. The inhibition kinetic results showed that the inhibition of FAS by tannic acid was mixed competitive and noncompetitive manner with respect to acetyl-CoA and malonyl-CoA, but uncompetitive to NADPH. Tannic acid prevented the differentiation of 3T3-L1 pre-adipocytes, and thus repressed intracellular lipid accumulation. In the meantime, tannic acid decreased the expression of FAS and down-regulated the mRNA level of FAS and PPARgamma during adipocyte differentiation. Further studies showed that the inhibitory effect of tannic acid did not relate to FAS non-specific sedimentation. Since FAS was believed to be a therapeutic target of obesity, these findings suggested that tannic acid was considered having potential in the prevention of obesity.

  19. Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors functional regulation during enhanced liver cell proliferation by GABA and 5-HT chitosan nanoparticles treatment.

    PubMed

    Shilpa, Joy; Pretty, Mary Abraham; Anitha, Malat; Paulose, Cheramadathikudyil Skaria

    2013-09-05

    Liver is one of the major organs in vertebrates and hepatocytes are damaged by many factors. The liver cell maintenance and multiplication after injury and treatment gained immense interest. The present study investigated the role of Gamma aminobutyric acid (GABA) and serotonin or 5-hydroxytryptamine (5-HT) coupled with chitosan nanoparticles in the functional regulation of Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors mediated cell signaling mechanisms, extend of DNA methylation and superoxide dismutase activity during enhanced liver cell proliferation. Liver injury was achieved by partial hepatectomy of male Wistar rats and the GABA and 5-HT chitosan nanoparticles treatments were given intraperitoneally. The experimental groups were sham operated control (C), partially hepatectomised rats with no treatment (PHNT), partially hepatectomised rats with GABA chitosan nanoparticle (GCNP), 5-HT chitosan nanoparticle (SCNP) and a combination of GABA and 5-HT chitosan nanoparticle (GSCNP) treatments. In GABA and 5-HT chitosan nanoparticle treated group there was a significant decrease (P<0.001) in the receptor expression of Gamma aminobutyric acid B and a significant increase (P<0.001) in the receptor expression of 5-hydroxy tryptamine 2A when compared to PHNT. The cyclic adenosine monophosphate content and its regulatory protein, presence of methylated DNA and superoxide dismutase activity were decreased in GCNP, SCNP and GSCNP when compared to PHNT. The Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors coupled signaling elements played an important role in GABA and 5-HT chitosan nanoparticles induced liver cell proliferation which has therapeutic significance in liver disease management.

  20. Excitatory actions of gaba during development: the nature of the nurture.

    PubMed

    Ben-Ari, Yehezkel

    2002-09-01

    In the immature brain, GABA (gamma-aminobutyric acid) is excitatory, and GABA-releasing synapses are formed before glutamatergic contacts in a wide range of species and structures. GABA becomes inhibitory by the delayed expression of a chloride exporter, leading to a negative shift in the reversal potential for choride ions. I propose that this mechanism provides a solution to the problem of how to excite developing neurons to promote growth and synapse formation while avoiding the potentially toxic effects of a mismatch between GABA-mediated inhibition and glutamatergic excitation. As key elements of this cascade are activity dependent, the formation of inhibition adds an element of nurture to the construction of cortical networks.

  1. Novel dose-dependent alterations in excitatory GABA during embryonic development associated with lead (Pb) neurotoxicity.

    PubMed

    Wirbisky, Sara E; Weber, Gregory J; Lee, Jang-Won; Cannon, Jason R; Freeman, Jennifer L

    2014-08-17

    Lead (Pb) is a heavy metal that is toxic to numerous physiological processes. Its use in industrial applications is widespread and results in an increased risk of human environmental exposure. The central nervous system (CNS) is most sensitive to Pb exposure during early development due to rapid cell proliferation and migration, axonal growth, and synaptogenesis. One of the key components of CNS development is the Gamma-aminobutyric acid (GABA)-ergic system. GABA is the primary inhibitory neurotransmitter in the adult brain. However, during development GABA acts as an excitatory neurotrophic factor which contributes to these cellular processes. Multiple studies report effects of Pb on GABA in the mature brain; however, little is known regarding the adverse effects of Pb exposure on the GABAergic system during embryonic development. To characterize the effects of Pb on the GABAergic system during development, zebrafish embryos were exposed to 10, 50, or 100 ppb Pb or a control treatment. Tissue up-take, gross morphological alterations, gene expression, and neurotransmitter levels were analyzed. Analysis revealed that alterations in gene expression throughout the GABAergic system and GABA levels were dose and developmental time point specific. These data provide a framework for further analysis of the effects of Pb on the GABAergic system during the excitatory phase and as GABA transitions to an inhibitory neurotransmitter during development.

  2. Alternate cadmium exposure differentially affects the content of gamma-aminobutyric acid (GABA) and taurine within the hypothalamus, median eminence, striatum and prefrontal cortex of male rats.

    PubMed

    Esquifino, A I; Seara, R; Fernández-Rey, E; Lafuente, A

    2001-05-01

    This work examines changes of gamma aminobutyric acid (GABA) and taurine contents in the hypothalamus, striatum and prefrontal cortex of the rat after an alternate schedule of cadmium administration. Age-associated changes were also evaluated, of those before puberty and after adult age. In control rats GABA content decreased with age in the median eminence and in anterior, mediobasal and posterior hypothalamus, prefrontal cortex and the striatum. Taurine content showed similar results with the exception of mediobasal hypothalamus and striatum, where no changes were detected. In pubertal rats treated with cadmium from 30 to 60 days of life, GABA content significantly decreased in all brain regions except in the striatum. When cadmium was administered from day 60 to 90 of life, GABA content was significantly changed in prefrontal cortex only compared with the age matched controls. Taurine content showed similar results in pubertal rats, with the exception of the median eminence and the mediobasal hypothalamus, neither of which showed a change. However, when cadmium was administered to rats from day 60 to 90 of life, taurine content only changed in prefrontal cortex compared with the age matched controls. These results suggest that cadmium differentially affects GABA and taurine contents within the hypothalamus, median eminence, striatum and prefrontal cortex as a function of age.

  3. Effects of poly-γ-glutamic acid on serum and brain concentrations of glutamate and GABA in diet-induced obese rats

    PubMed Central

    Lee, Hyesung; Chang, Moon-Jeong

    2010-01-01

    Poly-gamma-glutamic acid (γ-PGA) is a mucilaginous and biodegradable compound produced by Bacillus subtilis from fermented soybeans, and is found in the traditional Korean soy product, cheongkukjang. This study was carried out to evaluate the effects of γ-PGA from a food source on the concentration of the neurotransmitter GABA and its metabolic precursor glutamate in diet-induced obese rats. Eight-week old male Sprague-Dawley rats (n=60) were used. The rats were divided into two groups and obesity was induced by providing either a 10% control fat or 45% high fat diet for 5 weeks. The rats were then blocked into 6 groups and supplemented with a 0.1% γ-PGA diet for 4 weeks. After sacrifice, brain and serum GABA and glutamate concentrations were analyzed by high performance liquid chromatography with fluorometric detection. The rats fed the high fat diet had significantly increased body weights. γ-PGA supplementation significantly increased serum concentrations of glutamate and GABA in the control fat diet groups while this effect was not found in the high fat groups. In the brain, glutamate concentrations were significantly higher in the γ-PGA supplemented groups both in rats fed the normal and high fat diets than in the no γ-PGA controls. GABA concentrations showed the same tendency. The results indicated that γ-PGA intake increased GABA concentrations in the serum and brain. However, the effects were not shown in obese rats. PMID:20198205

  4. Treating enhanced GABAergic inhibition in Down syndrome: use of GABA α5-selective inverse agonists.

    PubMed

    Martínez-Cué, Carmen; Delatour, Benoît; Potier, Marie-Claude

    2014-10-01

    Excess inhibition in the brain of individuals carrying an extra copy of chromosome 21 could be responsible for cognitive deficits observed throughout their lives. A change in the excitatory/inhibitory balance in adulthood would alter synaptic plasticity, potentially triggering learning and memory deficits. γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mature central nervous system and binds to GABAA receptors, opens a chloride channel, and reduces neuronal excitability. In this review we discuss methods to alleviate neuronal inhibition in a mouse model of Down syndrome, the Ts65Dn mouse, using either an antagonist (pentylenetetrazol) or two different inverse agonists selective for the α5-subunit containing receptor. Both inverse agonists, which reduce inhibitory GABAergic transmission, could rescue learning and memory deficits in Ts65Dn mice. We also discuss safety issues since modulation of the excitatory-inhibitory balance to improve cognition without inducing seizures remains particularly difficult when using GABA antagonists.

  5. Potentiation of the ionotropic GABA receptor response by whiskey fragrance.

    PubMed

    Hossain, Sheikh Julfikar; Aoshima, Hitoshi; Koda, Hirofumi; Kiso, Yoshinobu

    2002-11-06

    It is well-known that the target of most mood-defining compounds is an ionotropic gamma-aminobutyric acid receptor (GABA(A) receptor). The potentiation of the response of these inhibitory neurotransmitter receptors induces anxiolytic, sedative, and anesthetic activity in the human brain. To study the effects of whiskey fragrance on the GABA(A) receptor-mediated response, GABA(A) receptors were expressed in Xenopus oocyte by injecting rat whole brain mRNA or cRNA prepared from the cloned cDNA for the alpha(1) and beta(1) subunits of the bovine receptors. Most whiskey components such as phenol, ethoxy, and lactone derivatives potentiated the electrical responses of GABA(A) receptors, especially ethyl phenylpropanoate (EPP), which strongly potentiated the response. When this compound was applied to mice through respiration, the convulsions induced by pentetrazole were delayed, suggesting that EPP was absorbed by the brain, where it could potentiate the GABA(A) receptor responses. The extract of other alcoholic drinks such as wine, sake, brandy, and shochu also potentiated the responses to varying degrees. Although these fragrant components are present in alcoholic drinks at low concentrations (extremely small quantities compared with ethanol), they may also modulate the mood or consciousness of the human through the potentiation of the GABA(A) receptor response after absorption into the brain, because these hydrophobic fragrant compounds are easily absorbed into the brain through the blood-brain barrier and are several thousands times as potent as ethanol in the potentiation of the GABA(A) receptor-mediated response.

  6. 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.

  7. GABA System in Schizophrenia and Mood Disorders: A Mini Review on Third-Generation Imaging Studies

    PubMed Central

    Chiapponi, Chiara; Piras, Federica; Piras, Fabrizio; Caltagirone, Carlo; Spalletta, Gianfranco

    2016-01-01

    Third-generation neuroimaging research has been enriched by advances in magnetic resonance spectroscopy (MRS) measuring the concentration of important neurotrasmitters, such as the inhibitory amino acid GABA. Here, we performed a systematic mini-review on brain MRS studies measuring GABA concentration in patients affected by schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD). We wondered whether multimodal investigations could overcome intrinsic technical limits of MRS giving a broader view of mental disorders pathogenesis. In SZ, unimodal studies gave mixed results, as increased, decreased, or unaltered GABA levels were reported depending on region, disease phase, and treatment. Conversely, multimodal results showed reduced level of glutamate, but not of GABA, in patients mirrored by in vitro biochemical findings revealing hippocampal reduction in glutamate signaling in SZ, and no deficits in GABA synthesis. Moreover, a mouse model confirmed the unique pathological characteristic of glutamate function in SZ. Unimodal studies in BD revealed again, inconsistent results, while no multimodal investigations including MRS on GABA exist. In MDD, unimodal studies could not differentiate patients from controls nor characterize high-risk subjects and remitted patients. However, a multimodal study combining functional magnetic resonance imaging and MRS revealed that cingulate cortex activity is related to glutamate, N-acetylaspartate levels and anhedonia in patients, and to GABA concentration in healthy subjects, improving the distinction between MDD and physiology. Overall, our results show that unimodal studies do not indicate GABA as a biomarker for the psychiatric disorders considered. Conversely, multimodal studies can widen the understanding of the link between psychopathology, genetics, neuroanatomy, and functional–biochemical brain activity in mental disorders. Although scarce, multimodal approaches seem promising for moving from GABA

  8. Relative vulnerability of dopamine and GABA neurons in mesencephalic culture to inhibition of succinate dehydrogenase by malonate and 3-nitropropionic acid and protection by NMDA receptor blockade.

    PubMed

    Zeevalk, G D; Derr-Yellin, E; Nicklas, W J

    1995-12-01

    The effects of different severities of metabolic stress on dopamine (DA) and gamma-aminobutyric acid (GABA) cell loss were examined in rat mesencephalic culture. Partial metabolic inhibition was induced in 12-day-old cultures by a 24-hr treatment with various concentrations of 3-nitropropionic acid(3-NPA, 0.1-0.5 mM) or malonate (10-50 mM), irreversible and reversible inhibitors of the Krebs cycle enzyme, succinate dehydrogenase. Cell damage to the DA and GABA populations was assessed after a 48-hr recovery period by simultaneous measurement of high affinity uptake for 3H-DA and 14C-GABA. 3-NPA or malonate caused a dose-dependent loss of DA uptake (EC50 0.21 or 42 mM, respectively). 3-NPA treatment was equally detrimental to the GABA population, whereas malonate exposure did not cause any significant loss of GABA uptake. The presence of the NMDA antagonist, MK-801 (1 microM), during 24 hr of 3-NPA or malonate treatment fully protected against DA and GABA loss with 50 mM malonate or 0.25 mM 3-NPA and partially protected versus 0.5 mM 3-NPA. To determine the degree of metabolic stress imposed by 3-NPA and malonate, 12-day-old cultures were treated with 0.5 mM 3-NPA or 50 mM malonate for 3 hr and the rate of lactate formation was measured. lactate was increased nearly 2-fold at 3 hr of treatment with 3-NPA, but was not significantly elevated above basal with malonate treatment. SDH activity was decreased by 48 or 58% after 3 hr of treatment with 0.25 and 0.5 mM 3-NPA, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and gamma-vinyl-gamma-aminobutyric acid (gamma-vinyl GABA) alter neurotransmitter concentrations in the nervous tissue of the goldfish (Carassius auratus) but not the cockroach (Periplaneta americana).

    PubMed

    Sloley, B D; McKenna, K F

    1993-02-01

    1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-methyl-4-phenylpyridinium iodide (MPP+) and gamma-vinyl-gamma-aminobutyric acid (gamma-vinyl GABA) are drugs demonstrated to alter catecholamine or gamma-aminobutyric acid (GABA) concentrations in vertebrate nervous tissue. MPTP and MPP+, which are potent and selective vertebrate neurotoxins, are effective in depleting noradrenaline and dopamine concentrations in goldfish. However, only MPP+ depletes dopamine in the central nervous tissues of the cockroach, and only when injected directly into the nervous tissue. Systemic injection of gamma-vinyl GABA, a selective GABA transaminase inhibitor in vertebrates, increases GABA concentrations in goldfish but not cockroach nervous tissue. Incubations of both goldfish hypothalamus and cockroach nervous tissue demonstrated the presence of GABA transaminase activity in vitro. However, the GABA transaminase activity obtained from goldfish tissues was much more sensitive to inhibition by gamma-vinyl GABA than that obtained from cockroach nervous tissue. These results demonstrate that MPTP, MPP+ and gamma-vinyl GABA are useful pharmacological tools which can alter neurotransmitter concentrations in a lower vertebrate. Unfortunately, they possess limited effectiveness in the cockroach.

  10. Neurons accumulating [3H]gamma-aminobutyric acid (GABA) in supragranular layers of cat primary auditory cortex (AI)

    PubMed

    Winer, J A

    1986-11-01

    The classes of neurons accumulating exogenously injected, tritiated gamma-aminobutyric acid [( 3H]GABA) were studied in the supragranular layers in the primary auditory field of the adult cat. The size, laminar locus, and somatodendritic profiles of labeled neurons were studied light microscopically in frozen- or Vibratome-sectioned, 30 micron thick material, and in semithin, 1-2 micron thick, plastic-embedded high-resolution autoradiographic preparations. The chief goals of the study were to determine which types of cells could be identified as accumulating [3H]GABA in layers I, II and III, and to establish possible relationships between these cells and neurons described in Golgi studies of these layers, and the neurons found, in parallel investigations of the connections of the primary auditory field, to participate as ipsilateral corticocortical and commissural cells of origin. The principal findings are: that neurons in every layer in the primary auditory field take up tritiated gamma-aminobutyric acid; that their Nissl-counterstained somata have a smaller average area, and a smaller range of areas, than do the unlabeled cells; that more than one type of labeled neuron-as defined by somatic size and shape, height:width ratios, and nuclear membrane morphology-could be identified in each layer; that none of the labeled neurons had a soma with a pyramidal configuration; that the labeled cells are comparable in size, shape, and laminar distribution to some populations of non-pyramidal ipsilateral corticocortical cells of origin in layers II and III, and perhaps to certain classes of commissurally projecting, layer III non-pyramidal neurons; and finally, that only a rather small proportion-perhaps 10% or less, except in layer I-of the supragranular cells appear to accumulate labeled material. With regard to the identity of particular classes of neurons accumulating silver grains above background in the individual layers, in layer I, 2 of the 4 types of neurons

  11. Functional Maturation of GABA Synapses During Postnatal Development of the Monkey Dorsolateral Prefrontal Cortex.

    PubMed

    Gonzalez-Burgos, Guillermo; Miyamae, Takeaki; Pafundo, Diego E; Yoshino, Hiroki; Rotaru, Diana C; Hoftman, Gil; Datta, Dibyadeep; Zhang, Yun; Hammond, Mahjub; Sampson, Allan R; Fish, Kenneth N; Ermentrout, G Bard; Lewis, David A

    2015-11-01

    Development of inhibition onto pyramidal cells may be crucial for the emergence of cortical network activity, including gamma oscillations. In primate dorsolateral prefrontal cortex (DLPFC), inhibitory synaptogenesis starts in utero and inhibitory synapse density reaches adult levels before birth. However, in DLPFC, the expression levels of γ-aminobutyric acid (GABA) synapse-related gene products changes markedly during development until young adult age, suggesting a highly protracted maturation of GABA synapse function. Therefore, we examined the development of GABA synapses by recording GABAAR-mediated inhibitory postsynaptic currents (GABAAR-IPSCs) from pyramidal cells in the DLPFC of neonatal, prepubertal, peripubertal, and adult macaque monkeys. We found that the decay of GABAAR-IPSCs, possibly including those from parvalbumin-positive GABA neurons, shortened by prepubertal age, while their amplitude increased until the peripubertal period. Interestingly, both GABAAR-mediated quantal response size, estimated by miniature GABAAR-IPSCs, and the density of GABAAR synaptic appositions, measured with immunofluorescence microscopy, were stable with age. Simulations in a computational model network with constant GABA synapse density showed that the developmental changes in GABAAR-IPSC properties had a significant impact on oscillatory activity and predicted that, whereas DLPFC circuits can generate gamma frequency oscillations by prepubertal age, mature levels of gamma band power are attained at late stages of development.

  12. Neurotoxins from Snake Venoms and α-Conotoxin ImI Inhibit Functionally Active Ionotropic γ-Aminobutyric Acid (GABA) Receptors*

    PubMed Central

    Kudryavtsev, Denis S.; Shelukhina, Irina V.; Son, Lina V.; Ojomoko, Lucy O.; Kryukova, Elena V.; Lyukmanova, Ekaterina N.; Zhmak, Maxim N.; Dolgikh, Dmitry A.; Ivanov, Igor A.; Kasheverov, Igor E.; Starkov, Vladislav G.; Ramerstorfer, Joachim; Sieghart, Werner; Tsetlin, Victor I.; Utkin, Yuri N.

    2015-01-01

    Ionotropic receptors of γ-aminobutyric acid (GABAAR) regulate neuronal inhibition and are targeted by benzodiazepines and general anesthetics. We show that a fluorescent derivative of α-cobratoxin (α-Ctx), belonging to the family of three-finger toxins from snake venoms, specifically stained the α1β3γ2 receptor; and at 10 μm α-Ctx completely blocked GABA-induced currents in this receptor expressed in Xenopus oocytes (IC50 = 236 nm) and less potently inhibited α1β2γ2 ≈ α2β2γ2 > α5β2γ2 > α2β3γ2 and α1β3δ GABAARs. The α1β3γ2 receptor was also inhibited by some other three-finger toxins, long α-neurotoxin Ls III and nonconventional toxin WTX. α-Conotoxin ImI displayed inhibitory activity as well. Electrophysiology experiments showed mixed competitive and noncompetitive α-Ctx action. Fluorescent α-Ctx, however, could be displaced by muscimol indicating that most of the α-Ctx-binding sites overlap with the orthosteric sites at the β/α subunit interface. Modeling and molecular dynamic studies indicated that α-Ctx or α-bungarotoxin seem to interact with GABAAR in a way similar to their interaction with the acetylcholine-binding protein or the ligand-binding domain of nicotinic receptors. This was supported by mutagenesis studies and experiments with α-conotoxin ImI and a chimeric Naja oxiana α-neurotoxin indicating that the major role in α-Ctx binding to GABAAR is played by the tip of its central loop II accommodating under loop C of the receptors. PMID:26221036

  13. Enhanced astroglial GABA uptake attenuates tonic GABAA inhibition of the presympathetic hypothalamic paraventricular nucleus neurons in heart failure.

    PubMed

    Pandit, Sudip; Jo, Ji Yoon; Lee, Sang Ung; Lee, Young Jae; Lee, So Yeong; Ryu, Pan Dong; Lee, Jung Un; Kim, Hyun-Woo; Jeon, Byeong Hwa; Park, Jin Bong

    2015-08-01

    γ-Aminobutyric acid (GABA) generates persistent tonic inhibitory currents (Itonic) and conventional inhibitory postsynaptic currents in the hypothalamic paraventricular nucleus (PVN) via activation of GABAA receptors (GABAARs). We investigated the pathophysiological significance of astroglial GABA uptake in the regulation of Itonic in the PVN neurons projecting to the rostral ventrolateral medulla (PVN-RVLM). The Itonic of PVN-RVLM neurons were significantly reduced in heart failure (HF) compared with sham-operated (SHAM) rats. Reduced Itonic sensitivity to THIP argued for the decreased function of GABAAR δ subunits in HF, whereas similar Itonic sensitivity to benzodiazepines argued against the difference of γ2 subunit-containing GABAARs in SHAM and HF rats. HF Itonic attenuation was reversed by a nonselective GABA transporter (GAT) blocker (nipecotic acid, NPA) and a GAT-3 selective blocker, but not by a GAT-1 blocker, suggesting that astroglial GABA clearance increased in HF. Similar and minimal Itonic responses to bestrophin-1 blockade in SHAM and HF neurons further argued against a role for astroglial GABA release in HF Itonic attenuation. Finally, the NPA-induced inhibition of spontaneous firing was greater in HF than in SHAM PVN-RVLM neurons, whereas diazepam induced less inhibition of spontaneous firing in HF than in SHAM neurons. Overall, our results showed that combined with reduced GABAARs function, the enhanced astroglial GABA uptake-induced attenuation of Itonic in HF PVN-RVLM neurons explains the deficit in tonic GABAergic inhibition and increased sympathetic outflow from the PVN during heart failure.

  14. trans-4-Amino-2-methylbut-2-enoic acid (2-MeTACA) and (+/-)-trans-2-aminomethylcyclopropanecarboxylic acid ((+/-)-TAMP) can differentiate rat rho3 from human rho1 and rho2 recombinant GABA(C) receptors.

    PubMed

    Vien, Jimmy; Duke, Rujee K; Mewett, Kenneth N; Johnston, Graham A R; Shingai, Ryuzo; Chebib, Mary

    2002-02-01

    1. This study investigated the effects of a number of GABA analogues on rat rho3 GABA(C) receptors expressed in Xenopus oocytes using 2-electrode voltage clamp methods. 2. The potency order of agonists was muscimol (EC(50)=1.9 +/- 0.1 microM) (+)-trans-3-aminocyclopentanecarboxylic acids ((+)-TACP; EC(50)=2.7 +/- 0.9 microM) trans-4-aminocrotonic acid (TACA; EC(50)=3.8 +/-0.3 microM) GABA (EC(50)=4.0 +/- 0.3 microM) > thiomuscimol (EC(50)=24.8 +/- 2.6 microM) > (+/-)-cis-2-aminomethylcyclopropane-carboxylic acid ((+/-)-CAMP; EC(50)=52.6 +/-8.7 microM) > cis-4-aminocrotonic acid (CACA; EC(50)=139.4 +/- 5.2 microM). 3. The potency order of antagonists was (+/-)-trans-2-aminomethylcyclopropanecarboxylic acid ((+/-)-TAMP; K(B)=4.8+/-1.8 microM) (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA; K(B)=4.8 +/-0.8 microM) > (piperidin-4-yl)methylphosphinic acid (P4MPA; K(B)=10.2+/-2.3 microM) 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP; K(B)=10.2+/-0.3 microM) imidazole-4-acetic acid (I4AA; K(B)=12.6+/-2.7 microM) > 3-aminopropylphosphonic acid (3-APA; K(B)=35.8+/-13.5 microM). 4. trans-4-Amino-2-methylbut-2-enoic acid (2-MeTACA; 300 microM) had no effect as an agonist or an antagonist indicating that the C2 methyl substituent is sterically interacting with the ligand-binding site of rat rho3 GABA(C) receptors. 5. 2-MeTACA affects rho1 and rho2 but not rho3 GABA(C) receptors. In contrast, (plus minus)-TAMP is a partial agonist at rho1 and rho2 GABA(C) receptors, while at rat rho3 GABA(C) receptors it is an antagonist. Thus, 2-MeTACA and (+/-)-TAMP could be important pharmacological tools because they may functionally differentiate between rho1, rho2 and rho3 GABA(C) receptors in vitro.

  15. Taurine activates GABA(A) but not GABA(B) receptors in rat hippocampal CA1 area.

    PubMed

    del Olmo, N; Bustamante, J; del Río, R M; Solís, J M

    2000-05-12

    We investigated if taurine, an endogenous GABA analog, could mimic both hyperpolarizing and depolarizing GABA(A)-mediated responses as well as pre- and postsynaptic GABA(B)-mediated actions in the CA1 region of rat hippocampal slices. Taurine (10 mM) perfusion induced changes in membrane potential and input resistance that are compatible with GABA(A) receptor activation. Local pressure application of taurine and GABA from a double barrel pipette positioned along the dendritic shaft of pyramidal cells revealed that taurine evoked a very small change of membrane potential and resistance compared with the large changes induced by GABA in these parameters. Moreover, in the presence of GABA(A) antagonists, local application of GABA on the dendrites evoked a GABA(B)-mediated hyperpolarization while taurine did not induce any change. Taurine neither mimicked baclofen inhibitory actions on presynaptic release of glutamate and GABA as judging by the lack of taurine effect on paired-pulse facilitation ratio and slow inhibitory postsynaptic potentials, respectively. These results show that taurine mainly activates GABA(A) receptors located on the cell body, indicating therefore that if taurine has any action on the dendrites it will not be mediated by either GABA(A) or GABA(B) receptors activation.

  16. Effects of intraventricular taurine, homotaurine and GABA on serum prolactin and thyrotropin levels in female and in male rats.

    PubMed

    Mäkinen, M; Ahtee, L; Rosenqvist, K; Tuominen, R K; Männistö, P

    1993-01-01

    Serum prolactin and thyrotropin levels of conscious, unrestrained male and female rats were compared after intracerebroventricular (i.c.v.) administration of taurine, gamma-aminobutyric acid (GABA) and homotaurine. The amino acids studied had no clear effect on serum basal thyrotropin levels in male or female rats. All amino acids elevated serum prolactin levels in female rats at the dose of 5 mumol/rat; homotaurine by about 18-fold, taurine and GABA by 3-fold. Only homotaurine elevated serum prolactin of male rats at this dose, but its effect was less pronounced (p < 0.01) in male than in female rats. Although homotaurine was clearly more potent than the two other amino acids, at the dose of 10 mumol/rat taurine and GABA also elevated serum prolactin in male rats. These findings show that there are gender-related differences in the responses of serum prolactin levels to homotaurine, taurine and GABA in rats. The tuberoinfundibular dopaminergic pathway, which exerts tonic inhibitory influence on prolactin secretion, is sexually differentiated. Hence the gender-related differences in the effects of the amino acids on prolactin secretion suggest that they might inhibit dopamine release from the median eminence. In case of homotaurine, the gender effect was most pronounced. The less clear dependence of GABA's effect on the gender is in accordance with the suggestions that GABA influences the secretion of serum prolactin by more than one mechanism.

  17. G protein activation kinetics and spillover of gamma-aminobutyric acid may account for differences between inhibitory responses in the hippocampus and thalamus.

    PubMed Central

    Destexhe, A; Sejnowski, T J

    1995-01-01

    We have developed a model of gamma-aminobutyric acid (GABA)ergic synaptic transmission mediated by GABAA and GABAB receptors, including cooperativity in the guanine nucleotide binding protein (G protein) cascade mediating the activation of K+ channels by GABAB receptors. If the binding of several G proteins is needed to activate the K+ channels, then only a prolonged activation of GABAB receptors evoked detectable currents. This could occur if strong stimuli evoked release in adjacent terminals and the spillover resulted in prolonged activation of the receptors, leading to inhibitory responses similar to those observed in hippocampal slices. The same model also reproduced thalamic GABAB responses to high-frequency bursts of stimuli. In this case, prolonged activation of the receptors was due to high-frequency release conditions. This model provides insights into the function of GABAB receptors in normal and epileptic discharges. Images Fig. 2 Fig. 4 PMID:7568165

  18. GABA and GAD expression in the X-organ sinus gland system of the Procambarus clarkii crayfish: inhibition mediated by GABA between X-organ neurons.

    PubMed

    Pérez-Polanco, Paola; Garduño, Julieta; Cebada, Jorge; Zarco, Natanael; Segovia, José; Lamas, Mónica; García, Ubaldo

    2011-09-01

    In crustaceans, the X-organ-sinus gland (XO-SG) neurosecretory system is formed of distinct populations of neurons that produce two families of neuropeptides: crustacean hyperglycemic hormone and adipokinetic hormone/red pigment-concentrating hormone. On the basis of electrophysiological evidence, it has been proposed that γ-aminobutyric acid (GABA) regulates both electrical and secretory activity of the XO-SG system. In this work we observed that depolarizing current pulses to neurons located in the external rim of the X-organ induced repetitive firing that suppressed the spontaneous firing of previously active X-organ neurons. Picrotoxin reversibly blocked this inhibitory effect suggesting that the GABA released from the stimulated neuron inhibited neighboring cells. Immunoperoxidase in X-organ serial sections showed co-localization of GABA and glutamic acid decarboxylase (GAD) including the aforementioned neurons. Immunofluorescence in whole mount preparations showed that two subpopulations of crustacean hyperglycemic hormone-containing neurons colocalized with GABA. The expression of GAD mRNA was determined in crayfish tissue and X-organ single cells by RT-PCR. Bioinformatics analysis shows, within the amplified region, 90.4% consensus and 41.9% identity at the amino acid level compared with Drosophila melanogaster and Caenorhabditis elegans. We suggest that crustacean hyperglycemic hormone-GABA-containing neurons can regulate the excitability of other X-organ neurons that produce different neurohormones.

  19. Aging of whiskey increases the potentiation of GABA(A) receptor response.

    PubMed

    Koda, Hirofumi; Hossain, Sheikh Julfikar; Kiso, Yoshinobu; Aoshima, Hitoshi

    2003-08-27

    It is known that the target of most mood-defining compounds such as ethanol is an ionotropic gamma-aminobutyric acid receptor (GABA(A) receptor). The potentiation of the response of these inhibitory neurotransmitter receptors induces anxiolytic, sedative, and anesthetic activities in the human brain. Because both extracts of whiskey by pentane and fragrant components in whiskey potentiate the GABA(A) receptor-mediated response, GABA(A) receptors were expressed in Xenopus oocyte by injecting cRNAs prepared from the cloned cDNA for the alpha(1) and beta(1) subunits of the bovine receptors in order to study the effects of whiskey itself on the GABA(A) receptor-mediated response. Whiskey itself also potentiated the electrical responses of GABA(A) receptors generally more than ethanol at the same concentration as that of the whiskey. The potentiation of the GABA(A) receptor-mediated response increased with the aging period of the whiskey. Inhalation of whiskey to mice increased the sleeping time induced by pentobarbital more than that of the same concentration of ethanol as the whiskey. These results suggest that not only ethanol but also minor components in whiskey play an important role in the potentiation of GABA(A) receptor-mediated response and possibly the sedative effect of whiskey. Although the minor components are present in extremely small quantities compared with ethanol in alcoholic beverages, they may modulate the mood or consciousness of humans through the potentiation of the GABA(A) receptor response after absorption into the brain, because these hydrophobic compounds are easily absorbed into the brain across the blood-brain barrier and are several thousands times as potent as ethanol in the potentiation of the GABA(A) receptor-mediated response.

  20. Microtransplantation of cellular membranes from squid stellate ganglion reveals ionotropic GABA receptors.

    PubMed

    Conti, Luca; Limon, Agenor; Palma, Eleonora; Miledi, Ricardo

    2013-02-01

    The squid has been the most studied cephalopod, and it has served as a very useful model for investigating the events associated with nerve impulse generation and synaptic transmission. While the physiology of squid giant axons has been extensively studied, very little is known about the distribution and function of the neurotransmitters and receptors that mediate inhibitory transmission at the synapses. In this study we investigated whether γ-aminobutyric acid (GABA) activates neurotransmitter receptors in stellate ganglia membranes. To overcome the low abundance of GABA-like mRNAs in invertebrates and the low expression of GABA in cephalopods, we used a two-electrode voltage clamp technique to determine if Xenopus laevis oocytes injected with cell membranes from squid stellate ganglia responded to GABA. Using this method, membrane patches containing proteins and ion channels from the squid's stellate ganglion were incorporated into the surface of oocytes. We demonstrated that GABA activates membrane receptors in cellular membranes isolated from squid stellate ganglia. Using the same approach, we were able to record native glutamate-evoked currents. The squid's GABA receptors showed an EC(50) of 98 μmol l(-1) to GABA and were inhibited by zinc (IC(50) = 356 μmol l(-1)). Interestingly, GABA receptors from the squid were only partially blocked by bicuculline. These results indicate that the microtransplantation of native cell membranes is useful to identify and characterize scarce membrane proteins. Moreover, our data also support the role of GABA as an ionotropic neurotransmitter in cephalopods, acting through chloride-permeable membrane receptors.

  1. GABA-B receptor activation inhibits the in vitro migration of malignant hepatocytes.

    PubMed

    Lodewyks, Carly; Rodriguez, Jose; Yan, Jing; Lerner, Betty; Lipschitz, Jeremy; Nfon, Charles; Rempel, Julia Darlene; Uhanova, Julia; Minuk, Gerald Yosel

    2011-06-01

    There are conflicting data regarding whether activation of γ-aminobutyric acid-B (GABA-B) receptors results in inhibition of tumor growth and invasion. The objectives of this study were to document the effects of the GABA-B receptor agonist baclofen on malignant hepatocyte proliferation and migration. We also sought to determine whether any effects on cell migration were mediated by changes in cyclic adenosine monophosphate (cAMP) signaling or matrix metalloproteinase (MMP) expression. Finally, GABA-B(1) and -B(2) receptor expression was documented in 2 malignant hepatocyte cell lines (PLC/PRF/5 and Huh-7) and 12 sets of human hepatocellular carcinoma and adjacent nontumor tissues. Cell proliferative activity was documented by WST-1 absorbance, migration by wound healing assays, cAMP levels by enzyme-linked immunoassay (ELISA), MMP by immunohistochemistry and ELISA, and GABA-B receptor expression by flow cytometry and reverse transcriptase - polymerase chain reaction. Although baclofen had no effect on cell proliferation, wound healing was delayed, an effect that was reversed by the GABA-B receptor antagonist CGP. cAMP levels were decreased in Huh-7 but not PLC cells exposed to baclofen. MMP expression remained unaltered in both cell lines. Finally, GABA-B(1) receptor expression was present and consistently expressed, but GABA-B(2) expression was limited and varied with the number of cell passages and (or) duration of culture. In conclusion, activation of GABA-B receptors has no effect on malignant hepatocyte proliferation but does decrease cell migration. This inhibitory effect may involve cAMP signaling but not MMP expression. GABA-B(2) receptor expression is limited and variable, which may help to explain discrepancies with previously published results.

  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. GABA localization in the nematode Ascaris

    SciTech Connect

    Guastella, J.

    1988-01-01

    A histochemical approach was used to examine the distribution of GABA-associated neurons in the nematode Ascaris, an organism whose small number of morphologically simple neurons make it an excellent preparation for analyzing neuronal phenotypes. Two GABAergic markers were examined: GABA-like immunoreactivity (GLIR), a marker for endogenous stores of GABA; and ({sup 3}H)-GABA uptake, a marker for GABA uptake sites. Strong GLIR was present in the cell bodies, neurites and commissures of dorsal and ventral inhibitory motorneurons present in this region. Strong GLIR was also present in the cell bodies and processes of the four RME neurons in the nerve ring and in several other ganglionic neurons. Staining was absent in excitatory motorneurons, in ventral cord interneurons and in muscle cells and hypodermis. GABA uptake sites were found in single neural processes in both the ventral and dorsal nerve cords. ({sup 3}H)-GABA labeling was also observed in the other two RME cells and several other cephalic neurons. Four putative cholinergic excitatory motorneurons in the retrovesicular ganglion (RVG) were heavily labeled. Ventral and dorsal nerve cord inhibitory motorneurons did not take up ({sup 3}H)-GABA. Labeling of the ventral cord excitatory motorneuron somata and cell bodies was at or slightly above background. Heavy labeling of muscle cells was also observed.

  4. GABA deficiency in NF1

    PubMed Central

    Patricio, Miguel; Bernardino, Inês; Rebola, José; Abrunhosa, Antero J.; Ferreira, Nuno; Castelo-Branco, Miguel

    2016-01-01

    Objective: To provide a comprehensive investigation of the γ-aminobutyric acid (GABA) system in patients with neurofibromatosis type 1 (NF1) that allows understanding the nature of the GABA imbalance in humans at pre- and postsynaptic levels. Methods: In this cross-sectional study, we employed multimodal imaging and spectroscopy measures to investigate GABA type A (GABAA) receptor binding, using [11C]-flumazenil PET, and GABA concentration, using magnetic resonance spectroscopy (MRS). Fourteen adult patients with NF1 and 13 matched controls were included in the study. MRS was performed in the occipital cortex and in a frontal region centered in the functionally localized frontal eye fields. PET and MRS acquisitions were performed in the same day. Results: Patients with NF1 have reduced concentration of GABA+ in the occipital cortex (p = 0.004) and frontal eye fields (p = 0.026). PET results showed decreased binding of GABAA receptors in patients in the parieto-occipital cortex, midbrain, and thalamus, which are not explained by decreased gray matter levels. Conclusions: Abnormalities in the GABA system in NF1 involve both GABA concentration and GABAA receptor density suggestive of neurodevelopmental synaptopathy with both pre- and postsynaptic involvement. PMID:27473134

  5. Acetylcholinesterase inhibitory properties of some benzoic acid derivatives

    NASA Astrophysics Data System (ADS)

    Yildiz, Melike; Kiliç, Deryanur; Ünver, Yaǧmur; Şentürk, Murat; Askin, Hakan; Küfrevioǧlu, Ömer Irfan

    2016-04-01

    Acetylcholinesterase (AChE) hydrolyses the neurotransmitter acetylcholine to acetic acid and choline. AChE inhibitors are used in treatment of several neurodegeneartive disorder and Alzheimer's disease. In the present study, inhibition of AChE with some benzoic acid derivatives were investigated. 3-Chloro-benzoic acid (1), 2-hydroxy-5-sulfobenzoic acid (2), 2-(sulfooxy) benzoic acid (3), 2-hydroxybenzoic acid (4), 2,3-dimethoxybenzoic (5), and 3,4,5-trimethoxybenzoic (6) were calculated IC50 values AChE enzyme. Kinetic investigations showed that similarly to AChE inhibitors. Benzoic acid derivatives (1-6) investigated are encouraging agents which may be used as lead molecules in order to derivative novel AChE inhibitors that might be useful in medical applications.

  6. Advantages of an antagonist: bicuculline and other GABA antagonists

    PubMed Central

    Johnston, Graham AR

    2013-01-01

    The convulsant alkaloid bicuculline continues to be investigated more than 40 years after the first publication of its action as an antagonist of receptors for the inhibitory neurotransmitter GABA. This historical perspective highlights key aspects of the discovery of bicuculline as a GABA antagonist and the sustained interest in this and other GABA antagonists. The exciting advances in the molecular biology, pharmacology and physiology of GABA receptors provide a continuing stimulus for the discovery of new antagonists with increasing selectivity for the myriad of GABA receptor subclasses. Interesting GABA antagonists not structurally related to bicuculline include gabazine, salicylidene salicylhydrazide, RU5135 and 4-(3-biphenyl-5-(4-piperidyl)-3-isoxazole. Bicuculline became the benchmark antagonist for what became known as GABAA receptors, but not all ionotropic GABA receptors are susceptible to bicuculline. In addition, not all GABAA receptor antagonists are convulsants. Thus there are still surprises in store as the study of GABA receptors evolves. PMID:23425285

  7. Inhibitory Activity of (+)-Usnic Acid against Non-Small Cell Lung Cancer Cell Motility.

    PubMed

    Yang, Yi; Nguyen, Thanh Thi; Jeong, Min-Hye; Crişan, Florin; Yu, Young Hyun; Ha, Hyung-Ho; Choi, Kyung Hee; Jeong, Hye Gwang; Jeong, Tae Cheon; Lee, Kwang Youl; Kim, Kyung Keun; Hur, Jae-Seoun; Kim, Hangun

    2016-01-01

    Lichens are symbiotic organisms that produce various unique chemicals that can be used for pharmaceutical purposes. With the aim of screening new anti-cancer agents that inhibit cancer cell motility, we tested the inhibitory activity of seven lichen species collected from the Romanian Carpathian Mountains against migration and invasion of human lung cancer cells and further investigated the molecular mechanisms underlying their anti-metastatic activity. Among them, Alectoria samentosa, Flavocetraria nivalis, Alectoria ochroleuca, and Usnea florida showed significant inhibitory activity against motility of human lung cancer cells. HPLC results showed that usnic acid is the main compound in these lichens, and (+)-usnic acid showed similar inhibitory activity that crude extract have. Mechanistically, β-catenin-mediated TOPFLASH activity and KITENIN-mediated AP-1 activity were decreased by (+)-usnic acid treatment in a dose-dependent manner. The quantitative real-time PCR data showed that (+)-usnic acid decreased the mRNA level of CD44, Cyclin D1 and c-myc, which are the downstream target genes of both β-catenin/LEF and c-jun/AP-1. Also, Rac1 and RhoA activities were decreased by treatment with (+)-usnic acid. Interestingly, higher inhibitory activity for cell invasion was observed when cells were treated with (+)-usnic acid and cetuximab. These results implied that (+)-usnic acid might have potential activity in inhibition of cancer cell metastasis, and (+)-usnic acid could be used for anti-cancer therapy with a distinct mechanisms of action.

  8. Inhibitory Activity of (+)-Usnic Acid against Non-Small Cell Lung Cancer Cell Motility

    PubMed Central

    Yang, Yi; Nguyen, Thanh Thi; Jeong, Min-Hye; Crişan, Florin; Yu, Young Hyun; Ha, Hyung-Ho; Choi, Kyung Hee; Jeong, Hye Gwang; Jeong, Tae Cheon; Lee, Kwang Youl; Kim, Kyung Keun; Hur, Jae-Seoun; Kim, Hangun

    2016-01-01

    Lichens are symbiotic organisms that produce various unique chemicals that can be used for pharmaceutical purposes. With the aim of screening new anti-cancer agents that inhibit cancer cell motility, we tested the inhibitory activity of seven lichen species collected from the Romanian Carpathian Mountains against migration and invasion of human lung cancer cells and further investigated the molecular mechanisms underlying their anti-metastatic activity. Among them, Alectoria samentosa, Flavocetraria nivalis, Alectoria ochroleuca, and Usnea florida showed significant inhibitory activity against motility of human lung cancer cells. HPLC results showed that usnic acid is the main compound in these lichens, and (+)-usnic acid showed similar inhibitory activity that crude extract have. Mechanistically, β-catenin-mediated TOPFLASH activity and KITENIN-mediated AP-1 activity were decreased by (+)-usnic acid treatment in a dose-dependent manner. The quantitative real-time PCR data showed that (+)-usnic acid decreased the mRNA level of CD44, Cyclin D1 and c-myc, which are the downstream target genes of both β-catenin/LEF and c-jun/AP-1. Also, Rac1 and RhoA activities were decreased by treatment with (+)-usnic acid. Interestingly, higher inhibitory activity for cell invasion was observed when cells were treated with (+)-usnic acid and cetuximab. These results implied that (+)-usnic acid might have potential activity in inhibition of cancer cell metastasis, and (+)-usnic acid could be used for anti-cancer therapy with a distinct mechanisms of action. PMID:26751081

  9. Decreased GABA receptor in the cerebral cortex of epileptic rats: effect of Bacopa monnieri and Bacoside-A

    PubMed Central

    2012-01-01

    Abstact Background Gamma amino butyric acid (GABA), the principal inhibitory neurotransmitter in the cerebral cortex, maintains the inhibitory tones that counter balances neuronal excitation. When this balance is perturbed, seizures may ensue. Methods In the present study, alterations of the general GABA, GABAA and GABAB receptors in the cerebral cortex of the epileptic rat and the therapeutic application of Bacopa monnieri were investigated. Results Scatchard analysis of [3H]GABA, [3H]bicuculline and [3H]baclofen in the cerebral cortex of the epileptic rat showed significant decrease in Bmax (P < 0.001) compared to control. Real Time PCR amplification of GABA receptor subunits such as GABAAά1, GABAAγ, GABAAδ, GABAB and GAD where down regulated (P < 0.001) in epileptic rats. GABAAά5 subunit and Cyclic AMP responsible element binding protein were up regulated. Confocal imaging study confirmed the decreased GABA receptors in epileptic rats. Epileptic rats have deficit in radial arm and Y maze performance. Conclusions Bacopa monnieri and Bacoside-A treatment reverses epilepsy associated changes to near control suggesting that decreased GABA receptors in the cerebral cortex have an important role in epileptic occurrence; Bacopa monnieri and Bacoside-A have therapeutic application in epilepsy management. PMID:22364254

  10. GABA-ergic Cell Therapy for Epilepsy: Advances, Limitations and Challenges

    PubMed Central

    Shetty, Ashok K.; Upadhya, Dinesh

    2016-01-01

    Diminution in the number of gamma-amino butyric acid positive (GABA-ergic) interneurons and their axon terminals, and/or alterations in functional inhibition are conspicuous brain alterations believed to contribute to the persistence of seizures in acquired epilepsies such as temporal lobe epilepsy. This has steered a perception that replacement of lost GABA-ergic interneurons would improve inhibitory synaptic neurotransmission in the epileptic brain region and thereby reduce the occurrence of seizures. Indeed, studies using animal prototypes have reported that grafting of GABA-ergic progenitors derived from multiple sources into epileptic regions can reduce seizures. This review deliberates recent advances, limitations and challenges concerning the development of GABA-ergic cell therapy for epilepsy. The efficacy and limitations of grafts of primary GABA-ergic progenitors from the embryonic lateral ganglionic eminence and medial ganglionic eminence (MGE), neural stem/progenitor cells expanded from MGE, and MGE-like progenitors generated from human pluripotent stem cells for alleviating seizures and co-morbidities of epilepsy are conferred. Additional studies required for possible clinical application of GABA-ergic cell therapy for epilepsy are also summarized. PMID:26748379

  11. 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

  12. 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.

  13. Downregulation of Parvalbumin at Cortical GABA Synapses Reduces Network Gamma Oscillatory Activity

    PubMed Central

    Volman, Vladislav; Behrens, M. Margarita; Sejnowski, Terrence J.

    2012-01-01

    Postmortem and functional imaging studies of patients with psychiatric disorders, including schizophrenia, are consistent with a dysfunction of interneurons leading to compromised inhibitory control of network activity. Parvalbumin (PV)-expressing, fast-spiking interneurons interacting with pyramidal neurons generate cortical gamma oscillations (30 – 80 Hz) that synchronize cortical activity during cognitive processing. In postmortem studies of schizophrenia patients, these interneurons show reduced PV and glutamic acid decarboxylase 67 (GAD67), an enzyme that synthesizes GABA, but the consequences of this downregulation are unclear. We developed a biophysically realistic and detailed computational model of a cortical circuit including asynchronous release from GABAergic interneurons to investigate how reductions in PV and GABA affect gamma oscillations induced by sensory stimuli. Networks with reduced GABA were disinhibited and had altered gamma oscillations in response to stimulation; PV-deficient GABA synapses had increased asynchronous release of GABA, which decreased the level of excitation and reduced gamma-band activity. Combined reductions of PV and GABA resulted in a diminished gamma-band oscillatory activity in response to stimuli, similar to that observed in schizophrenia patients. Our results suggest a mechanism by which reduced GAD67 and PV in fast-spiking interneurons may contribute to cortical dysfunction in schizophrenia and related psychiatric disorders. PMID:22159125

  14. Closing the loop on the GABA shunt in plants: are GABA metabolism and signaling entwined?

    PubMed Central

    Michaeli, Simon; Fromm, Hillel

    2015-01-01

    γ-Aminobutyric acid (GABA) is a non-proteinogenic amino acid that is found in uni- and multi-cellular organisms and is involved in many aspects of plant life cycle. GABA metabolism occurs by the action of evolutionary conserved enzymes that constitute the GABA shunt, bypassing two steps of the TCA cycle. The central position of GABA in the interface between plant carbon and nitrogen metabolism is well established. In parallel, there is evidence to support a role for GABA as a signaling molecule in plants. Here we cover some of the recent findings on GABA metabolism and signaling in plants and further suggest that the metabolic and signaling aspects of GABA may actually be inseparable. PMID:26106401

  15. Insula and anterior cingulate GABA levels in post-traumatic stress disorder: Preliminary findings using magnetic resonance spectroscopy

    PubMed Central

    Rosso, Isabelle M.; Weiner, Melissa R.; Crowley, Davidan J; Silveri, Marisa M.; Rauch, Scott L.; Jensen, J. Eric

    2013-01-01

    Background Increased reactivity of the insular cortex and decreased activity of the dorsal anterior cingulate (ACC) are seen in functional imaging studies of post-traumatic stress disorder (PTSD), and may partly explain the persistent fear- and anxiety-proneness that characterize the disorder. A possible neurochemical correlate is altered function of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). We report results from what we believe is the first study applying proton magnetic resonance spectroscopy (1H-MRS) to measure brain GABA in PTSD. Methods Thirteen adults with DSM-IV PTSD and 13 matched healthy control subjects underwent single voxel 1H-MRS at 4 Tesla. GABA was measured in the right anterior insula and dorsal anterior cingulate, using MEGAPRESS spectral editing. Subjects were interviewed with the Structured Clinical Interview for DSM-IV and the Clinician Administered PTSD Scale, and also completed the State and Trait Anxiety Inventory. Results Insula GABA was significantly lower in PTSD subjects than in controls, and dorsal ACC GABA did not differ significantly between the groups. Insula GABA was not significantly associated with severity of PTSD symptoms. However, lower insula GABA was associated with significantly higher state and trait anxiety in the subject sample as a whole. Conclusions PTSD is associated with reduced GABA in the right anterior insula. This preliminary evidence of the 1H-MRS GABA metabolite as a possible biomarker of PTSD encourages replication in larger samples and examination of relations with symptom dimensions. Future studies also should examine whether insula GABA is a marker of anxiety proneness, cutting across clinical diagnostic categories. PMID:23861191

  16. Specific targeting of the GABA-A receptor α5 subtype by a selective inverse agonist restores cognitive deficits in Down syndrome mice

    PubMed Central

    Braudeau, J; Delatour, B; Duchon, A; Pereira, P Lopes; Dauphinot, L; de Chaumont, F; Olivo-Marin, J-C; Dodd, RH; Hérault, Y; Potier, M-C

    2011-01-01

    An imbalance between inhibitory and excitatory neurotransmission has been proposed to contribute to altered brain function in individuals with Down syndrome (DS). Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system and accordingly treatment with GABA-A antagonists can efficiently restore cognitive functions of Ts65Dn mice, a genetic model for DS. However, GABA-A antagonists are also convulsant which preclude their use for therapeutic intervention in DS individuals. Here, we have evaluated safer strategies to release GABAergic inhibition using a GABA-A-benzodiazepine receptor inverse agonist selective for the α5-subtype (α5IA). We demonstrate that α5IA restores learning and memory functions of Ts65Dn mice in the novel-object recognition and in the Morris water maze tasks. Furthermore, we show that following behavioural stimulation, α5IA enhances learning-evoked immediate early gene products in specific brain regions involved in cognition. Importantly, acute and chronic treatments with α5IA do not induce any convulsant or anxiogenic effects that are associated with GABA-A antagonists or non-selective inverse agonists of the GABA-A-benzodiazepine receptors. Finally, chronic treatment with α5IA did not induce histological alterations in the brain, liver and kidney of mice. Our results suggest that non-convulsant α5-selective GABA-A inverse agonists could improve learning and memory deficits in DS individuals. PMID:21693554

  17. Inhibitory and excitatory amino acid neurotransmitters are utilized by the projection from the dorsal deep mesencephalic nucleus to the sublaterodorsal nucleus REM sleep induction zone

    PubMed Central

    Liang, Chang-Lin; Nguyen, Tin Quang; Marks, Gerald A.

    2014-01-01

    The sublaterodorsal nucleus (SLD) in the pons of the rat is a locus supporting short-latency induction of a REM sleep-like state following local application of a GABAA receptor antagonist or kainate, glutamate receptor agonist. One putatively relevant source of these neurotransmitters is from the region of the deep mesencephalic nucleus (DpMe) just ventrolateral to the periaquiductal gray, termed the dorsal DpMe (dDpMe). Here, the amino acid neurotransmitter innervation of SLD from dDpMe was studied utilizing anterograde tract-tracing with biotinylated dextranamine (BDA) and fluorescence immunohistochemistry visualized with laser scanning confocal microscopy. Both markers for inhibitory and excitatory amino acid neurotransmitters were found in varicose axon fibers in SLD originating from dDpMe. Vesicular glutamate transporter2 (VGLUT2) represented the largest number of anterogradely labeled varicosities followed by vesicular GABA transporter (VGAT). Numerous VGAT and VGLUT2 labeled varicosities were observed apposed to dDpMe-labeled axon fibers indicating both excitatory and inhibitory presynaptic, local modulation within the SLD. Some double-labeled BDA/VGAT varicosities were seen apposed to small somata labeled for glutamate consistent with being presynaptic to the phenotype of REM sleep-active SLD neurons. Results found support the current theoretical framework of the interaction of dDpMe and SLD in control of REM sleep, while also indicating operation of mechanisms with a greater level of complexity. PMID:24751569

  18. Thiocolchicoside inhibits the activity of various subtypes of recombinant GABA(A) receptors expressed in Xenopus laevis oocytes.

    PubMed

    Mascia, Maria Paola; Bachis, Elisabetta; Obili, Nicola; Maciocco, Elisabetta; Cocco, Giovanni Antonio; Sechi, Gian Pietro; Biggio, Giovanni

    2007-03-08

    Thiocolchicoside is a myorelaxant drug with anti-inflammatory and analgesic properties as well as pronounced convulsant activity. To characterize the mechanisms of action of this drug at the molecular level, we examined its effects on the function of various recombinant neurotransmitter receptors expressed in Xenopus oocytes. Electrophysiological recordings from recombinant human gamma-aminobutyric acid type A (GABA(A)) receptors consisting of alpha1beta1gamma2L, alpha1beta2gamma2L, or alpha2beta2gamma2L subunit combinations revealed that thiocolchicoside inhibited GABA-evoked Cl(-) currents with similar potencies (median inhibitory concentrations of 0.13 to 0.2 microM) and in a competitive manner. Consistent with previous observations, thiocolchicoside also inhibited the binding of GABA to rat cerebral cortical membranes. Thiocolchicoside inhibited the function of recombinant human strychnine-sensitive glycine receptors composed of the alpha1 subunit with a potency (median inhibitory concentration of 47 microM) lower than that apparent with recombinant GABA(A) receptors. It also inhibited the function of human nicotinic acetylcholine receptors composed of the alpha4 and beta2 subunits, but this effect was only partial and apparent at high concentrations. In contrast, thiocolchicoside had no effect on the function of 5-HT(3A) serotonin receptors. Our results thus provide molecular evidence that the epileptogenic activity of thiocolchicoside might be due to inhibition of the function of inhibitory receptors in the central nervous system, especially that of GABA(A) receptors.

  19. Use of sourdough fermentation and pseudo-cereals and leguminous flours for the making of a functional bread enriched of gamma-aminobutyric acid (GABA).

    PubMed

    Coda, Rossana; Rizzello, Carlo Giuseppe; Gobbetti, Marco

    2010-02-28

    Lactobacillus plantarum C48 and Lactococcus lactis subsp. lactis PU1, previously selected for the biosynthesis of gamma-aminobutyric acid (GABA), were used for sourdough fermentation of cereal, pseudo-cereal and leguminous flours. Chickpea, amaranth, quinoa and buckwheat were the flours most suitable to be enriched of GABA. The parameters of sourdough fermentation were optimized. Addition of 0.1mM pyridoxal phosphate, dough yield of 160, inoculum of 5 x 10(7)CFU/g of starter bacteria and fermentation for 24h at 30 degrees C were found to be the optimal conditions. A blend of buckwheat, amaranth, chickpea and quinoa flours (ratio 1:1:5.3:1) was selected and fermented with baker's yeast (non-conventional flour bread, NCB) or with Lb. plantarum C48 sourdough (non-conventional flour sourdough bread, NCSB) and compared to baker's yeast started wheat flour bread (WFB). NCSB had the highest concentration of free amino acids and GABA (ca. 4467 and 504 mg/kg, respectively). The concentration of phenolic compounds and antioxidant activity of NCSB bread was the highest, as well as the rate of in vitro starch hydrolysis was the lowest. Texture analysis showed that sourdough fermentation enhances several characteristics of NCSB with respect to NCB, thus approaching the features of WFB. Sensory analysis showed that sourdough fermentation allowed to get good palatability and overall taste appreciation.

  20. Zeolites relieves inhibitory stress from high concentrations of long chain fatty acids.

    PubMed

    Nordell, Erik; Hansson, Anna B; Karlsson, Martin

    2013-12-01

    Protein and fat rich slaughterhouse waste is a very attractive waste stream for the production of biogas because of the high biochemical methane potential of the substrate. The material has however some drawbacks as the sole material for biogas production due to the production of several process disturbing metabolites such as ammonia, sulfides and long chain fatty acids. We can in this work present results that show that zeolites have the potential to relieve inhibitory stress from the presence of long chain fatty acids. Moreover, the results strongly indicate that it is mainly acetic acid consumers that are most negatively affected by long chain fatty acids and that the mechanism of stress relief is an adsorption of long chain fatty acids to the zeolites. In addition to this, it is shown that the effect is immediate and that only a small amount of zeolites is necessary to cancel the inhibitory effect of long chain fatty acids.

  1. Glutamate and GABA-metabolizing enzymes in post-mortem cerebellum in Alzheimer's disease: phosphate-activated glutaminase and glutamic acid decarboxylase.

    PubMed

    Burbaeva, G Sh; Boksha, I S; Tereshkina, E B; Savushkina, O K; Prokhorova, T A; Vorobyeva, E A

    2014-10-01

    Enzymes of glutamate and GABA metabolism in postmortem cerebellum from patients with Alzheimer's disease (AD) have not been comprehensively studied. The present work reports results of original comparative study on levels of phosphate-activated glutaminase (PAG) and glutamic acid decarboxylase isoenzymes (GAD65/67) in autopsied cerebellum samples from AD patients and matched controls (13 cases in each group) as well as summarizes published evidence for altered levels of PAG and GAD65/67 in AD brain. Altered (decreased) levels of these enzymes and changes in links between amounts of these enzymes and other glutamate-metabolizing enzymes (such as glutamate dehydrogenase and glutamine synthetase-like protein) in AD cerebella suggest significantly impaired glutamate and GABA metabolism in this brain region, which was previously regarded as not substantially involved in AD pathogenesis.

  2. GABA interaction with lipids in organic medium

    SciTech Connect

    Beltramo, D.; Kivatinitz, S.; Lassaga, E.; Arce, A.

    1987-08-10

    The interaction of TH-GABA and UC-glutamate with lipids in an aqueous organic partition system was studied. With this partition system TH-GABA and UC-glutamate were able to interact with sphingomyelin, sulfatide, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and phosphatidic acid but not with cholesterol or ceramide. In an homogeneous aqueous medium the authors could not demonstrate any interaction between TH-GABA-lipids. The apparent dissociation constants (K/sub d/) for TH-GABA-lipids or UC-glutamate-lipids interactions inorganic medium were in the millimolar range and maximal charge between 3 and 7 moles of GABA or glutamate by mole of lipid. Amino acids such as glutamic acid, US -alanine and glycine displaced TH-GABA with the same potency as GABA itself; thus these results show that the interaction lacks pharmacological specificity. To detect this interaction lipid concentrations higher than 2 M were required and in the partition system TH-GABA and lipid phosphorus were both concentrated at the interface. Therefore, lipids tested with a biphasic partition system do not fulfill the classical criteria for a neurotransmitter receptor at least not for GABA and glutamate. 15 references, 1 figure, 3 tables.

  3. Taurine is a potent activator of extrasynaptic GABA(A) receptors in the thalamus.

    PubMed

    Jia, Fan; Yue, Minerva; Chandra, Dev; Keramidas, Angelo; Goldstein, Peter A; Homanics, Gregg E; Harrison, Neil L

    2008-01-02

    Taurine is one of the most abundant free amino acids in the brain. In a number of studies, taurine has been reported to activate glycine receptors (Gly-Rs) at moderate concentrations (> or = 100 microM), and to be a weak agonist at GABA(A) receptors (GABA(A)-Rs), which are usually activated at high concentrations (> or = 1 mM). In this study, we show that taurine reduced the excitability of thalamocortical relay neurons and activated both extrasynaptic GABA(A)-Rs and Gly-Rs in neurons in the mouse ventrobasal (VB) thalamus. Low concentrations of taurine (10-100 microM) decreased neuronal input resistance and firing frequency, and elicited a steady outward current under voltage clamp, but had no effects on fast inhibitory synaptic currents. Currents elicited by 50 microM taurine were abolished by gabazine, insensitive to midazolam, and partially blocked by 20 microM Zn2+, consistent with the pharmacological properties of extrasynaptic GABA(A)-Rs (alpha4beta2delta subtype) involved in tonic inhibition in the thalamus. Tonic inhibition was enhanced by an inhibitor of taurine transport, suggesting that taurine can act as an endogenous activator of these receptors. Taurine-evoked currents were absent in relay neurons from GABA(A)-R alpha4 subunit knock-out mice. The amplitude of the taurine current was larger in neurons from adult mice than juvenile mice. Taurine was a more potent agonist at recombinant alpha4beta2delta GABA(A)-Rs than at alpha1beta2gamma2 GABA(A)-Rs. We conclude that physiological concentrations of taurine can inhibit VB neurons via activation of extrasynaptic GABA(A)-Rs and that taurine may function as an endogenous regulator of excitability and network activity in the thalamus.

  4. Thalamic GABA Predicts Fine Motor Performance in Manganese-Exposed Smelter Workers

    PubMed Central

    Long, Zaiyang; Li, Xiang-Rong; Xu, Jun; Edden, Richard A. E.; Qin, Wei-Ping; Long, Li-Ling; Murdoch, James B.; Zheng, Wei; Jiang, Yue-Ming; Dydak, Ulrike

    2014-01-01

    Overexposure to manganese (Mn) may lead to parkinsonian symptoms including motor deficits. The main inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is known to play a pivotal role in the regulation and performance of movement. Therefore this study was aimed at testing the hypothesis that an alteration of GABA following Mn exposure may be associated with fine motor performance in occupationally exposed workers and may underlie the mechanism of Mn-induced motor deficits. A cohort of nine Mn-exposed male smelter workers from an Mn-iron alloy factory and 23 gender- and age-matched controls were recruited and underwent neurological exams, magnetic resonance spectroscopy (MRS) measurements, and Purdue pegboard motor testing. Short-echo-time MRS was used to measure N-Acetyl-aspartate (NAA) and myo-inositol (mI). GABA was detected with a MEGA-PRESS J-editing MRS sequence. The mean thalamic GABA level was significantly increased in smelter workers compared to controls (p = 0.009). Multiple linear regression analysis reveals (1) a significant association between the increase in GABA level and the duration of exposure (R2 = 0.660, p = 0.039), and (2) significant inverse associations between GABA levels and all Purdue pegboard test scores (for summation of all scores R2 = 0.902, p = 0.001) in the smelter workers. In addition, levels of mI were reduced significantly in the thalamus and PCC of smelter workers compared to controls (p = 0.030 and p = 0.009, respectively). In conclusion, our results show clear associations between thalamic GABA levels and fine motor performance. Thus in Mn-exposed subjects, increased thalamic GABA levels may serve as a biomarker for subtle deficits in motor control and may become valuable for early diagnosis of Mn poisoning. PMID:24505436

  5. Gamma-aminobutyric acid (GABA) and neuropeptides in neural areas mediating motion-induced emesis

    NASA Technical Reports Server (NTRS)

    Damelio, F.; Daunton, Nancy G.; Fox, Robert A.

    1991-01-01

    Immunocytochemical methods were employed to localize the neurotransmitter amino acid gamma-aminobutyric acid and the neuropeptides substance P and Met-enkephalin in the area postrema (AP), area subpostrema (ASP), nucleus of the tractus solitarius (NTS), dorsal motor nucleus of the vagus nerve (DMNV), and lateral vestibular nucleus (LVN). Glutamic acid decarboxylase immunoreactive (GAD-IR) terminals and fibers were observed in the AP and particularly in the ASP. A gradual decrease in the density of terminals was seen towards the solitary complex. The DMNV revealed irregularly scattered GAD-IR terminals within the neuropil or closely surrounding neuronal cell bodies. The LVN, particularly the dorsal division, showed numerous axon terminals which were mostly localize around large neurons and their proximal dendrites. Substance P immunoreactive (SP-IR) terminals and fibers showed high density in the solitary complex, in particular within the lateral division. The ASP showed medium to low density of SP-IR fibers and terminals. The AP exhibited a small number of fibers and terminals irregularly distributed. The DMNV revealed a high density of SP-IR terminals and fibers that were mainly concentrated in the periphery. Very few terminals were detected in the LVN. Met-enkephalin immunoreactive (Met-Enk-IR) fibers and terminals showed high density and uniform distribution in the DMNV. Scattered terminals and fibers were observed in the AP, ASP, and NTS (particularly the lateral division). The very few fibers were observed in the LVN surrounded the neuronal cell bodies. The present report is part of a study designed to investigate the interaction between neuropeptides and conventional neurotransmitters under conditions producing motion sickness and in the process of sensory-motor adaptation.

  6. Columnar architecture sculpted by GABA circuits in developing cat visual cortex.

    PubMed

    Hensch, Takao K; Stryker, Michael P

    2004-03-12

    The mammalian visual cortex is organized into columns. Here, we examine cortical influences upon developing visual afferents in the cat by altering intrinsic gamma-aminobutyric acid (GABA)-mediated inhibition with benzodiazepines. Local enhancement by agonist (diazepam) infusion did not perturb visual responsiveness, but did widen column spacing. An inverse agonist (DMCM) produced the opposite effect. Thus, intracortical inhibitory circuits shape the geometry of incoming thalamic arbors, suggesting that cortical columnar architecture depends on neuronal activity.

  7. Modulation of the release of norepinephrine by gamma-aminobutyric acid and morphine in the frontal cerebral cortex of the rat

    SciTech Connect

    Peoples, R.W.

    1989-01-01

    Agents that enhance gamma-aminobutyric acid, or GABA, neurotransmission modulate certain effects of opioids, such as analgesia. Opioid analgesia is mediated in part by norepinephrine in the forebrain. In this study, the interactions between morphine and GABAergic agents on release of ({sup 3}H) norepinephrine from rat frontal cerebral cortical slices were examined. GABA, 5 {times} 10{sup {minus}5}-10{sup {minus}3} M, enhanced potassium stimulated ({sup 3}H) norepinephrine release and reversed the inhibitory effect of morphine in a noncompetitive manner. GABA did not enhance release of ({sup 3}H) norepinephrine stimulated by the calcium ionophore A23187. The effect of GABA was reduced by the GABA{sub A} receptor antagonists bicuculline methiodide or picrotoxin, and by the selective inhibitor of GABA uptake SKF 89976A, but was blocked completely only when bicuculline methiodide and SKF 89976A were used in combination. The GABA{sub A} agonist muscimol, 10{sup {minus}4} M, mimicked the effect of GABA, but the GABA{sub B} agonist ({plus minus})baclofen, 10{sup {minus}4} M, did not affect the release of ({sup 3}H) norepinephrine in the absence or the presence of morphine. Thus GABA appears to produce this effect by stimulating GABA uptake and GABA{sub A}, but not GABA{sub B}, receptors. In contrast to the results that would be predicted for an event involving GABA{sub A} receptors, however, the effect of GABA did not desensitize, and benzodiazepine agonists did not enhance the effect of GABA at any concentration tested between 10{sup {minus}8} and 10{sup {minus}4} M. Thus these receptors may constitute a subclass of GABA{sub A} receptors. These results support a role of GABA uptake and GABA{sub A} receptors in enhancing the release of norepinephrine and modulating its inhibition by opioids in the frontal cortex of the rat.

  8. Effect of domoic acid on brain amino acid levels.

    PubMed

    Durán, R; Arufe, M C; Arias, B; Alfonso, M

    1995-03-01

    The administration of Domoic Acid (Dom) in a 0.2 mg/kg i.p. dose induces changes in the levels of amino acids of neurochemical interest (Asp, Glu, Gly, Tau, Ala, GABA) in different rat brain regions (hypothalamus, hippocampus, amygdala, striatum, cortex and midbrain). The most affected amino acid is the GABA, the main inhibitory amino acid neurotransmitter, whereas glutamate, the main excitatory amino acid, is not affected. The rat brain regions that seem to be the main target of the Dom action belong to the limbic system (hippocampus, amygdala). The possible implication of the amino acids in the actions of Dom is also discussed.

  9. Low nanomolar GABA effects at extrasynaptic α4β1/β3δ GABA(A) receptor subtypes indicate a different binding mode for GABA at these receptors.

    PubMed

    Karim, Nasiara; Wellendorph, Petrine; Absalom, Nathan; Bang, Line Haunstrup; Jensen, Marianne Lerbech; Hansen, Maja Michelle; Lee, Ho Joon; Johnston, Graham A R; Hanrahan, Jane R; Chebib, Mary

    2012-08-15

    Ionotropic GABA(A) receptors are a highly heterogenous population of receptors assembled from a combination of multiple subunits. The aims of this study were to characterize the potency of GABA at human recombinant δ-containing extrasynaptic GABA(A) receptors expressed in Xenopus oocytes using the two-electrode voltage clamp technique, and to investigate, using site-directed mutagenesis, the molecular determinants for GABA potency at α4β3δ GABA(A) receptors. α4/δ-Containing GABA(A) receptors displayed high sensitivity to GABA, with mid-nanomolar concentrations activating α4β1δ (EC₅₀=24 nM) and α4β3δ (EC₅₀=12 nM) receptors. In the majority of oocytes expressing α4β3δ subtypes, GABA produced a biphasic concentration-response curve, and activated the receptor with low and high concentrations (EC₅₀(1)=16 nM; EC₅₀(2)=1.2 μM). At α4β2δ, GABA had low micromolar activity (EC₅₀=1 μM). An analysis of 10 N-terminal singly mutated α4β3δ receptors shows that GABA interacts with amino acids different to those reported for α1β2γ2 GABA(A) receptors. Residues Y205 and R207 of the β3-subunit significantly affected GABA potency, while the residue F71 of the α4- and the residue Y97 of the β3-subunit did not significantly affect GABA potency. Mutating the residue R218 of the δ-subunit, equivalent to the GABA binding residue R207 of the β2-subunit, reduced the potency of GABA by 670-fold, suggesting a novel GABA binding site at the δ-subunit interface. Taken together, GABA may have different binding modes for extrasynaptic δ-containing GABA(A) receptors compared to their synaptic counterparts.

  10. L-DOPA Reverses the Increased Free Amino Acids Tissue Levels Induced by Dopamine Depletion and Rises GABA and Tyrosine in the Striatum.

    PubMed

    Solís, Oscar; García-Sanz, Patricia; Herranz, Antonio S; Asensio, María-José; Moratalla, Rosario

    2016-07-01

    Perturbations in the cerebral levels of various amino acids are associated with neurological disorders, and previous studies have suggested that such alterations have a role in the motor and non-motor symptoms of Parkinson's disease. However, the direct effects of chronic L-DOPA treatment, that produces dyskinesia, on neural tissue amino acid concentrations have not been explored in detail. To evaluate whether striatal amino acid concentrations are altered in peak dose dyskinesia, 6-hydroxydopamine (6-OHDA)-lesioned hemiparkinsonian mice were treated chronically with L-DOPA and tissue amino acid concentrations were assessed by HPLC analysis. These experiments revealed that neither 6-OHDA nor L-DOPA treatment are able to alter glutamate in the striatum. However, glutamine increases after 6-OHDA and returns back to normal levels with L-DOPA treatment, suggesting increased striatal glutamatergic transmission with lack of dopamine. In addition, glycine and taurine levels are increased following dopamine denervation and restored to normal levels by L-DOPA. Interestingly, dyskinetic animals showed increased levels of GABA and tyrosine, while aspartate striatal tissue levels are not altered. Overall, our results indicate that chronic L-DOPA treatment, besides normalizing the altered levels of some amino acids after 6-OHDA, robustly increases striatal GABA and tyrosine levels which may in turn contribute to the development of L-DOPA-induced dyskinesia.

  11. Interactions between dopamine and GABA in the control of ambulatory activity.

    PubMed

    Agmo, A; Belzung, C; Giordano, M

    1996-01-01

    Ambulatory activity of male rats was quantified in an open field. The subjects were treated with DL-amphetamine and amfonelic acid alone or combined with the GABA transaminase inhibitors gamma-acetylen GABA (GAG) and sodium valproate as well as with the GABAA agonist THIP and the GABAB agonist baclofen. Subeffective doses of the GABAergic drugs did not modify the effects of moderate doses of the dopaminergic stimulants whereas effective doses continued to reduce ambulatory activity just as in the absence of dopaminergic activation. When DL-amphetamine or amfonelic acid were administered in doses that strongly enhanced ambulatory activity, doses of the GABAergic drugs that were inhibitory in the absence of dopaminergic stimulation were no longer effective. The mixed D1/D2 dopamine antagonist pimozide, the D1 antagonist SCH 23390 and the D2 antagonist sulpiride were then combined with subeffective doses of the GABA agonists. GAG, sodium valproate and baclofen were potentiated by pimozide and SCH 23390 but not by sulpiride. THIP was ineffective. These data show that GABAergic drugs had a reduced effect after stimulation of dopaminergic neurotransmission. On the other hand, when dopamine D1 receptors were blocked, nonselective GABA agonists and the GABAB agonist baclofen were potentiated. This was not the case for the GABAA agonist THIP, suggesting that the GABAA receptor is of slight importance for the interactions between GABA and dopamine in the control of ambulatory activity. No potentiation of GABAergic agonists was obtained after treatment with a dopamine D2 antagonist.

  12. GABA(B2) is essential for g-protein coupling of the GABA(B) receptor heterodimer.

    PubMed

    Robbins, M J; Calver, A R; Filippov, A K; Hirst, W D; Russell, R B; Wood, M D; Nasir, S; Couve, A; Brown, D A; Moss, S J; Pangalos, M N

    2001-10-15

    GABA(B) receptors are unique among G-protein-coupled receptors (GPCRs) in their requirement for heterodimerization between two homologous subunits, GABA(B1) and GABA(B2), for functional expression. Whereas GABA(B1) is capable of binding receptor agonists and antagonists, the role of each GABA(B) subunit in receptor signaling is unknown. Here we identified amino acid residues within the second intracellular domain of GABA(B2) that are critical for the coupling of GABA(B) receptor heterodimers to their downstream effector systems. Our results provide strong evidence for a functional role of the GABA(B2) subunit in G-protein coupling of the GABA(B) receptor heterodimer. In addition, they provide evidence for a novel "sequential" GPCR signaling mechanism in which ligand binding to one heterodimer subunit can induce signal transduction through the second partner of a heteromeric complex.

  13. Inhibitory effect of chlorogenic acid on digestion of potato starch.

    PubMed

    Karim, Zida; Holmes, Melvin; Orfila, Caroline

    2017-02-15

    The effect of the chlorogenic acid isomer 5-O-caffeoylquinic acid (5-CQA) on digestion of potato starch by porcine pancreatic alpha amylase (PPAA) was investigated using isolated starch and cooked potato tuber as substrates. In vitro digestion was performed on five varieties of potato with varying phenolic content. Co- and pre-incubation of PPAA with 5-CQA significantly reduced PPAA activity in a dose dependent manner with an IC50 value of about 2mgmL(-1). Lineweaver-Burk plots indicated that 5-CQA exerts a mixed type inhibition as km increased and Vmax decreased. The total polyphenol content (TPC) of peeled tuber tissue ranged from 320.59 to 528.94mg 100g(-1)dry weight (DW) in raw tubers and 282.03-543.96mg 100g(-1)DW in cooked tubers. With the exception of Désirée, TPC and 5-CQA levels decreased after cooking. Principle component analysis indicated that digestibility is affected by multiple factors including phenolic, dry matter and starch content.

  14. Superior In Vivo Inhibitory Efficacy of Methylseleninic Acid Against Human Prostate Cancer over Selenomethionine or Selenite

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Methylselenol has been implicated as an active anti-cancer selenium metabolite. Its in vivo efficacy for prostate cancer has yet to be established. Methods: We evaluated the in vivo growth inhibitory effects of two presumed methylselenol precursors methylseleninic acid (MSeA) and ...

  15. A possible role of the non-GAT1 GABA transporters in transfer of GABA from GABAergic to glutamatergic neurons in mouse cerebellar neuronal cultures.

    PubMed

    Suñol, C; Babot, Z; Cristòfol, R; Sonnewald, U; Waagepetersen, H S; Schousboe, A

    2010-09-01

    Cultures of dissociated cerebellum from 7-day-old mice were used to investigate the mechanism involved in synthesis and cellular redistribution of GABA in these cultures consisting primarily of glutamatergic granule neurons and a smaller population of GABAergic Golgi and stellate neurons. The distribution of GAD, GABA and the vesicular glutamate transporter VGlut-1 was assessed using specific antibodies combined with immunofluorescence microscopy. Additionally, tiagabine, SKF 89976-A, betaine, beta-alanine, nipecotic acid and guvacine were used to inhibit the GAT1, betaine/GABA (BGT1), GAT2 and GAT3 transporters. Only a small population of cells were immuno-stained for GAD while many cells exhibited VGlut-1 like immuno-reactivity which, however, never co-localized with GAD positive neurons. This likely reflects the small number of GABAergic neurons compared to the glutamatergic granule neurons constituting the majority of the cells. GABA uptake exhibited the kinetics of high affinity transport and could be partly (20%) inhibited by betaine (IC(50) 142 microM), beta-alanine (30%) and almost fully (90%) inhibited by SKF 89976-A (IC(50) 0.8 microM) or nipecotic acid and guvacine at 1 mM concentrations (95%). Essentially all neurons showed GABA like immunostaining albeit with differences in intensity. The results indicate that GABA which is synthesized in a small population of GAD-positive neurons is redistributed to essentially all neurons including the glutamatergic granule cells. GAT1 is not likely involved in this redistribution since addition of 15 microM tiagabine (GAT1 inhibitor) to the culture medium had no effect on the overall GABA content of the cells. Likewise the BGT1 transporter cannot alone account for the redistribution since inclusion of 3 mM betaine in the culture medium had no effect on the overall GABA content. The inhibitory action of beta-alanine and high concentrations of nipecotic acid and guvacine on GABA transport strongly suggests that also

  16. gamma-Aminobutyric acid (GABA): a fast excitatory transmitter which may regulate the development of hippocampal neurones in early postnatal life.

    PubMed

    Ben-Ari, Y; Tseeb, V; Raggozzino, D; Khazipov, R; Gaiarsa, J L

    1994-01-01

    consequent rise in intracellular calcium, for stimulating neurite outgrowth; the GABAergic network, which develops prior to the glutamatergic one, appears to provide this depolarisation. Starting from the end of the first postnatal week of life, at a time when excitatory pathways are developing, GABA (acting on both GABAA and GABAB receptors) would reverse its action, and start to play its well-known role as an inhibitory neurotransmitter.

  17. Kinetic studies on the inhibition of GABA-T by gamma-vinyl GABA and taurine.

    PubMed

    Sulaiman, Saba A J; Suliman, Fakhr Eldin O; Barghouthi, Samira

    2003-08-01

    Gamma-aminobutyric acid transaminase (GABA-T, EC 2.6.1.19) is a pyridoxal phosphate (PLP) dependent enzyme that catalyzes the degradation of gamma-aminobutyric acid. The kinetics of this reaction are studied in vitro, both in the absence, and in the presence of two inhibitors: gamma-vinyl GABA (4-aminohex-5-enoic acid), and a natural product, taurine (ethylamine-2-sulfonic acid). A kinetic model that describes the transamination process is proposed. GABA-T from Pseudomonas fluorescens is inhibited by gamma-vinyl GABA and taurine at concentrations of 51.0 and 78.5 mM. Both inhibitors show competitive inhibition behavior when GABA is the substrate and the inhibition constant (Ki) values for gamma-vinyl GABA and taurine were found to be 26 +/- 3 mM and 68 +/- 7 mM respectively. The transamination process of alpha-ketoglutarate was not affected by the presence of gamma-vinyl GABA, whereas, taurine was a noncompetitive inhibitor of GABA-T when alpha-ketoglutarate was the substrate. The inhibition dissociation constant (Kii) for this system was found to be 96 +/- 10 mM. The Michaelis-Menten constant (Km) in the absence of inhibition, was found to be 0.79 +/- 0.11 mM, and 0.47 +/- 0.10 mM for GABA and alpha-ketoglutarate respectively.

  18. [GABA-ergic system in defense against excitatory kynurenines].

    PubMed

    Lapin, I P

    1997-01-01

    Protection against the excitatory action of L-kynurenine and quinolinic acid in mice is related to the activation of GABA-B and dopamine receptors of the brain and to much lesser degree to the activation of GABA-A receptors. It is hardly believable that the anticonvulsant effect of phenibut (beta-phenyl-GABA), baclofen (CL-phenibut), sodium hydroxybutyrate and taurine against seizures induced by these two kynurenines is determined by alterations in metabolism of GABA.

  19. 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

  20. Reduced Chrna7 expression in mice is associated with decreases in hippocampal markers of inhibitory function: implications for neuropsychiatric diseases

    PubMed Central

    Adams, Catherine E.; Yonchek, Joan C.; Schulz, Kalynn M.; Graw, Sharon L.; Stitzel, Jerry; Teschke, Patricia U.; Stevens, Karen E.

    2012-01-01

    The α7* nicotinic acetylcholine receptor encoded by CHRNA7 (human)/Chrna7 (mice) regulates the release of both the inhibitory neurotransmitter γ-aminobutyric acid (GABA) and the excitatory neurotransmitter glutamate in the hippocampal formation. A heterozygous deletion at 15q13.3 containing CHRNA7 is associated with increased risk for schizophrenia, autism and epilepsy. Each of these diseases is 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 heterozygous 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, GABAA receptors, the GABA synthetic enzyme glutamate decarboxylase-65 (GAD-65) and the vesicular GABA transporter GAT-1 in wild type (Chrna7 +/+) and heterozygous (Chrna7 +/−) C3H α7 mice of both genders. GAD-65 levels were significantly decreased in male and female heterozygous C3H α7 mice while GABAA receptors were significantly reduced only in male heterozygous 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. PMID:22314319

  1. The inhibitory effects on sexual behavior and ambulatory activity of the mixed GABAA/GABAB agonist progabide are differentially blocked by GABA receptor antagonists.

    PubMed

    Agmo, A; Paredes, R G; Sierra, L; Garcés, I

    1997-01-01

    Progabide inhibited male rat sexual behavior at a dose of 200 mg/kg. This dose had only modest effects on ambulatory activity and no effect at all on motor coordination as evaluated by a rotarod test. The GABAA antagonist bicuculline, at a dose of 1 mg/kg, blocked the effects of progabide on sex behavior. In contrast, the GABAB antagonist CGP 35348, at doses of 50 and 100 mg/kg, was ineffective. These doses have previously been shown to block the actions of baclofen on sexual behavior. It was concluded that the GABAA but not the GABAB receptor is important for the inhibitory effects of progabide on that behavior. The actions of progabide on ambulatory activity were not blocked by bicuculline or CGP 35348 at any of the doses used (up to 2 and 200 mg/kg, respectively). Even the combination of both antagonists was ineffective. This suggests that the motor effects of progabide are mediated by either a non-GABAergic receptor or by a subtype of the GABAA or the GABAB receptor that is not sensitive to the antagonists. Present results show that the effects of progabide on motor functions depend on mechanisms different from those involved in its effects on sexual behavior. They further suggest that the GABAA receptor may be important for drug actions on male sexual behavior.

  2. Excitatory action of GABA on immature neurons is not due to absence of ketone bodies metabolites or other energy substrates.

    PubMed

    Ben-Ari, Yehezkel; Tyzio, Roman; Nehlig, Astrid

    2011-09-01

    Brain slices incubated with glucose have provided most of our knowledge on cellular, synaptic, and network driven mechanisms. It has been recently suggested that γ-aminobutyric acid (GABA) excites neonatal neurons in conventional glucose-perfused slices but not when ketone bodies metabolites, pyruvate, and/or lactate are added, suggesting that the excitatory actions of GABA are due to energy deprivation when glucose is the sole energy source. In this article, we review the vast number of studies that show that slices are not energy deprived in glucose-containing medium, and that addition of other energy substrates at physiologic concentrations does not alter the excitatory actions of GABA on neonatal neurons. In contrast, lactate, like other weak acids, can produce an intracellular acidification that will cause a reduction of intracellular chloride and a shift of GABA actions. The effects of high concentrations of lactate, and particularly of pyruvate (4-5 mm), as used are relevant primarily to pathologic conditions; these concentrations not being found in the brain in normal "control" conditions. Slices in glucose-containing medium may not be ideal, but additional energy substrates neither correspond to physiologic conditions nor alter GABA actions. In keeping with extensive observations in a wide range of animal species and brain structures, GABA depolarizes immature neurons and the reduction of the intracellular concentration of chloride ([Cl(-)](i)) is a basic property of brain maturation that has been preserved throughout evolution. In addition, this developmental sequence has important clinical implications, notably concerning the higher incidence of seizures early in life and their long-lasting deleterious sequels. Immature neurons have difficulties exporting chloride that accumulates during seizures, leading to permanent increase of [Cl(-)](i) that converts the inhibitory actions of GABA to excitatory and hampers the efficacy of GABA-acting antiepileptic

  3. Effect of pressure on (/sup 3/H)GABA release by synaptosomes isolated from cerebral cortex

    SciTech Connect

    Gilman, S.C.; Colton, J.S.; Hallenbeck, J.M.

    1986-12-01

    High hydrostatic pressure has been shown to produce neurological changes in humans which manifest, in part, as tremor, myoclonic jerks, electroencephalographic changes, and convulsions. This clinical pattern has been termed high-pressure nervous syndrome (HPNS). These symptoms may represent an alteration in synaptic transmission in the central nervous system with the inhibitory neural pathways being affected in particular. Since gamma-aminobutyric acid (GABA) transmission has been implicated in other seizure disorders, it was of interest to study GABAergic function at high pressure. Isolated synaptosomes were used to follow GABA release at 67.7 ATA of pressure. The major observation was a 33% depression in total (/sup 3/H)GABA efflux from depolarized cerebrocortical synaptosomes at 67.7 ATA. The Ca2+-dependent component of release was found to be completely blocked during the 1st min of (/sup 3/H)GABA efflux with a slow rise over the subsequent 3 min. These findings lead us to conclude that high pressure interferes with the intraterminal cascade for Ca2+-dependent release of GABA.

  4. Inhibitory effect and mechanism of acarbose combined with gymnemic acid on maltose absorption in rat intestine

    PubMed Central

    Luo, Hong; Wang, Le Feng; Imoto, Toshiaki; Hiji, Yasutake

    2001-01-01

    AIM: To compare the combinative and individual effect of acarbose and gymnemic acid (GA) on maltose absorption and hydrolysis in small intestine to determine whether nutrient control in diabetic care can be improved by combination of them. METHODS: The absorption and hydrolysis of maltose were studied by cyclic perfusion of intestinal loops in situ and motility of the intestine was recorded with the intestinal ring in vitro using Wistar rats. RESULTS: The total inhibitory rate of maltose absorption was improved by the combination of GA (0.1 g/L-1.0 g/L) and acarbose (0.1 mmol/L-2.0 mmol/L) throughout their effective duration (P < 0.05, U test of Mann-Whitney), although the improvement only could be seen at a low dosage during the first hour. With the combination, inhibitory duration of acarbose on maltose absorption was prolonged to 3 h and the inhibitory effect onset of GA was fastened to 15 min. GA suppressed the intestinal mobility with a good correlation (r = 0.98) to the inhibitory effect of GA on maltose absorption and the inhibitory effect of 2 mmol/L (high dose) acarbose on maltose hydrolysis was dual modulated by 1 g/L GA in vivo indicating that the combined effects involved the functional alteration of intestinal barriers. CONCLUSION: There are augmented effects of acarbose and GA, which involve pre-cellular and paracellular barriers. Diabetic care can be improved by employing the combination. PMID:11819725

  5. Potent Inhibitory Effect of Chinese Dietary Spices on Fatty Acid Synthase.

    PubMed

    Jiang, Bing; Liang, Yan; Sun, Xuebing; Liu, Xiaoxin; Tian, Weixi; Ma, Xiaofeng

    2015-09-01

    Dietary spices have been adopted in cooking since ancient times to enhance flavor and also as food preservatives and disease remedies. In China, the use of spices and other aromatic plants as food flavoring is an integral part of dietary behavior, but relatively little is known about their functions. Fatty acid synthase (FAS) has been recognized as a remedy target, and its inhibitors might be applied in disease treatment. The present work was designed to assess the inhibitory activities on FAS of spices extracts in Chinese menu. The in vitro inhibitory activities on FAS of 22 extracts of spices were assessed by spectrophotometrically monitoring oxidation of NADPH at 340 nm. Results showed that 20 spices extracts (90.9 %) exhibited inhibitory activities on FAS, with half inhibition concentration (IC(50)) values ranging from 1.72 to 810.7 μg/ml. Among them, seven spices showed strong inhibitory effect with IC(50) values lower than 10 μg/ml. These findings suggest that a large proportion of the dietary spices studied possess promising inhibitory activities on FAS, and subsequently might be applied in the treatment of obesity and obesity-related human diseases.

  6. 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

  7. Role of a γ-aminobutryic acid (GABA) receptor mutation in the evolution and spread of Diabrotica virgifera virgifera resistance to cyclodiene insecticides.

    PubMed

    Wang, H; Coates, B S; Chen, H; Sappington, T W; Guillemaud, T; Siegfried, B D

    2013-10-01

    The western corn rootworm, Diabrotica virgifera virgifera, is a damaging pest of cultivated corn that was controlled by applications of cyclodiene insecticides from the late 1940s until resistance evolved ∼10 years later. Range expansion from the western plains into eastern USA coincides with resistance development. An alanine to serine amino acid substitution within the Rdl subunit of the gamma-aminobutyric acid (GABA) receptor confers resistance to cyclodiene insecticides in many species. We found that the non-synonymous single nucleotide polymorphism (SNP) G/T at the GABA receptor cDNA position 838 (G/T(838)) of D. v. virgifera resulted in the alanine to serine change, and the codominant SNP allele T(838) was genetically linked to survival of beetles in aldrin bioassays. A phenotypic gradient of decreasing susceptibility from west to east was correlated with higher frequencies of the resistance-conferring T(838) allele in the eastern-most populations. This pattern exists in opposition to perceived selective pressures since the more eastern and most resistant populations probably experienced reduced exposure. The reasons for the observed distribution are uncertain, but historical records of the range expansion combined with the distribution of susceptible and resistant phenotypes and genotypes provide an opportunity to better understand factors affecting the species' range expansion.

  8. The GABA transaminase, ABAT, is essential for mitochondrial nucleoside metabolism

    PubMed Central

    Besse, Arnaud; Wu, Ping; Bruni, Francesco; Donti, Taraka; Graham, Brett H.; Craigen, William J.; McFarland, Robert; Moretti, Paolo; Lalani, Seema; Scott, Kenneth L.; Taylor, Robert W.; Bonnen, Penelope E.

    2015-01-01

    Summary ABAT is a key enzyme responsible for catabolism of principal inhibitory neurotransmitter gamma-aminobutyric acid (GABA). We report an essential role for ABAT in a seemingly unrelated pathway, mitochondrial nucleoside salvage, and demonstrate that mutations in this enzyme cause an autosomal recessive neurometabolic disorder and mtDNA depletion syndrome (MDS). We describe a family with encephalomyopathic MDS caused by a homozygous missense mutation in ABAT that results in elevated GABA in subjects’ brains as well as decreased mtDNA levels in subjects’ fibroblasts. Nucleoside rescue and co-IP experiments pinpoint that ABAT functions in the mitochondrial nucleoside salvage pathway to facilitate conversion of dNDPs to dNTPs. Pharmacological inhibition of ABAT through the irreversible inhibitor Vigabatrin caused depletion of mtDNA in photoreceptor cells that was prevented through addition of dNTPs in cell culture media. This work reveals ABAT as a connection between GABA metabolism and nucleoside metabolism and defines a neurometabolic disorder that includes MDS. PMID:25738457

  9. A new phenolic fatty acid ester with lipoxygenase inhibitory activity from Jacaranda filicifolia.

    PubMed

    Ali, R M; Houghton, P J

    1999-06-01

    The dichloromethane extract of the stem of jacaranda filicifolia Don. showed inhibitory activity in vitro against soybean 5-lipoxygenase. Systematic fractionation to isolate the compounds responsible resulted in the isolation of three active compounds, 2 alpha, 3 alpha-dihydroxyurs-12-en-28-oic acid, beta-sitosterol, and one of which was new which was characterised as 2-(4-hydroxyphenyl)ethyl 1-dodecyloctadecanoate. This type of compound has not previously been reported to inhibit lipoxygenase.

  10. Postnatal changes in somatic gamma-aminobutyric acid signalling in the rat hippocampus.

    PubMed

    Tyzio, Roman; Minlebaev, Marat; Rheims, Sylvain; Ivanov, Anton; Jorquera, Isabelle; Holmes, Gregory L; Zilberter, Yuri; Ben-Ari, Yehezkiel; Khazipov, Rustem

    2008-05-01

    During postnatal development of the rat hippocampus, gamma-aminobutyric acid (GABA) switches its action on CA3 pyramidal cells from excitatory to inhibitory. To characterize the underlying changes in the GABA reversal potential, we used somatic cell-attached recordings of GABA(A) and N-methyl-D-aspartate channels to monitor the GABA driving force and resting membrane potential, respectively. We found that the GABA driving force is strongly depolarizing during the first postnatal week. The strength of this depolarization rapidly declines with age, although GABA remains slightly depolarizing, by a few millivolts, even in adult neurons. Reduction in the depolarizing GABA driving force was due to a progressive negative shift of the reversal potential of GABA currents. Similar postnatal changes in GABA signalling were also observed using the superfused hippocampus preparation in vivo, and in the hippocampal interneurons in vitro. We also found that in adult pyramidal cells, somatic GABA reversal potential is maintained at a slightly depolarizing level by bicarbonate conductance, chloride-extrusion and chloride-loading systems. Thus, the postnatal excitatory-to-inhibitory switch in somatic GABA signalling is associated with a negative shift of the GABA reversal potential but without a hyperpolarizing switch in the polarity of GABA responses. These results also suggest that in adult CA3 pyramidal cells, somatic GABAergic inhibition takes place essentially through shunting rather than hyperpolarization. Apparent hyperpolarizing GABA responses previously reported in the soma of CA3 pyramidal cells are probably due to cell depolarization during intracellular or whole-cell recordings.

  11. Inhibitory effects of docosahexaenoic acid on colon carcinoma 26 metastasis to the lung.

    PubMed Central

    Iigo, M.; Nakagawa, T.; Ishikawa, C.; Iwahori, Y.; Asamoto, M.; Yazawa, K.; Araki, E.; Tsuda, H.

    1997-01-01

    Unsaturated fatty acids, including n-3 polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (C22:6, DHA) and eicosapentaenoic acid (C20:5, EPA), and a series of n-6 PUFAs were investigated for their anti-tumour and antimetastatic effects in a subcutaneous (s.c.) implanted highly metastatic colon carcinoma 26 (Co 26Lu) model. EPA and DHA exerted significant inhibitory effects on tumour growth at the implantation site and significantly decreased the numbers of lung metastatic nodules. Oleic acid also significantly inhibited lung metastatic nodules. Treatment with arachidonic acid showed a tendency for reduction in colonization. However, treatment with high doses of fatty acids, especially linoleic acid, increased the numbers of lung metastatic nodules. DHA and EPA only inhibited lung colonizations when administered together with the tumour cells, suggesting that their incorporation is necessary for an influence to be exerted. Chromatography confirmed that contents of fatty acids in both tumour tissues and plasma were indeed affected by the treatments. Tumour cells pretreated with fatty acids in vivo, in particular DHA, also showed a low potential for lung colony formation when transferred to new hosts. Thus, DHA treatment exerted marked antimetastatic activity associated with pronounced change in the fatty acid component of tumour cells. The results indicate that uptake of DHA into tumour cells results in altered tumour cell membrane characteristics and a decreased ability to metastasize. PMID:9043019

  12. Presynaptic Na+-dependent transport and exocytose of GABA and glutamate in brain in hypergravity.

    NASA Astrophysics Data System (ADS)

    Borisova, T.; Pozdnyakova, N.; Krisanova, N.; Himmelreich, N.

    γ-Aminobutyric acid (GABA) and L-glutamate are the most widespread neurotransmitter amino acids in the mammalian central nervous system. GABA is now widely recognized as the major inhibitory neurotransmitter. L-glutamate mediates the most of excitatory synaptic neurotransmission in the brain. They involved in the main aspects of normal brain function. The nerve terminals (synaptosomes) offer several advantages as a model system for the study of general mechanisms of neurosecretion. Our data allowed to conclude that exposure of animals to hypergravity (centrifugation of rats at 10G for 1 hour) had a profound effect on synaptic processes in brain. Comparative analysis of uptake and release of GABA and glutamate have demonstrated that hypergravity loading evokes oppositely directed alterations in inhibitory and excitatory signal transmission. We studied the maximal velocities of [^3H]GABA reuptake and revealed more than twofold enhancement of GABA transporter activity (Vmax rises from 1.4 |pm 0.3 nmol/min/mg of protein in the control group to 3.3 ± 0.59 nmol/min/mg of protein for animals exposed to hypergravity (P ≤ 0.05)). Recently we have also demonstrated the significant lowering of glutamate transporter activity (Vmax of glutamate reuptake decreased from 12.5 ± 3.2 nmol/min/mg of protein in the control group to 5.6 ± 0.9 nmol/min/mg of protein in the group of animals, exposed to the hypergravity stress (P ≤ 0.05)). Significant changes occurred in release of neurotransmitters induced by stimulating exocytosis with the agents, which depolarized nerve terminal plasma membrane. Depolarization-evoked Ca2+-stimulated release was more abundant for GABA (7.2 ± 0.54% and 11,74 ±1,2 % of total accumulated label for control and hypergravity, respectively (P≤0.05)) and was essentially less for glutamate (14.4 ± 0.7% and 6.2 ± 1.9%) after exposure of animals to centrifuge induced artificial gravity. Changes observed in depolarization-evoked exocytotic release

  13. Differential effects of phosphonic analogues of GABA on GABA(B) autoreceptors in rat neocortical slices.

    PubMed

    Ong, J; Marino, V; Parker, D A; Kerr, D I

    1998-04-01

    The effects of five phosphonic derivatives of GABA on the release of [3H]-GABA from rat neocortical slices, preloaded with [3H]-GABA, were investigated. Phaclofen and 4-aminobutylphosphonic acid (4-ABPA) increased the overflow of [3H] evoked by electrical stimulation (2 Hz) in a concentration-dependent manner, with similar potencies (phaclofen EC50=0.3 mmol/l, 4-ABPA EC50=0.4 mmol/l). At 3 mmol/l, phaclofen increased the release of [3H]-GABA by 82.6+/-8.6%, and 4-ABPA increased the release by 81.3+/-9.0%. 2-Amino-ethylphosphonic acid (2-AEPA) increased the overflow of [3H] by 46.8+/-10.9% at the highest concentration tested (3 mmol/l). In contrast, the lower phosphonic homologue 3-aminopropylphosphonic acid (3-APPA), and 2-amino-2-(p-chlorophenyl)-ethylphosphonic acid (2-CPEPA), a baclofen analogue, did not modify the stimulated overflow. These results suggest that phaclofen, 4-ABPA and 2-AEPA are antagonists at GABA(B) autoreceptors, the latter being the weakest antagonist, whilst neither 3-APPA nor 2-CPEPA are active at these receptors. Since phaclofen, 4-ABPA and 2-CPEPA are antagonists and 3-APPA a partial agonist/antagonist on GABA(B) heteroreceptors, the lack of effect of 3-APPA and 2-CPEPA on [3H]-GABA release in this study suggests that GABA(B) autoreceptors may be pharmacologically distinct from the heteroreceptors.

  14. Excitatory actions of GABA in developing rat hypothalamic neurones.

    PubMed Central

    Chen, G; Trombley, P Q; van den Pol, A N

    1996-01-01

    in young cultures that the GABA-evoked depolarization could directly trigger action potentials, facilitate some depolarizing input to fire action potentials, and shunt other depolarizing input. Whether the GABA-induced depolarization is excitatory or inhibitory would be determined by the reversal potential of the GABA-evoked current, and the temporal relationship between GABA-evoked depolarizations and other excitatory events. 6. We conclude that the reversal potential of the GABA-evoked current shifts negatively from depolarizing to hyperpolarizing in developing hypothalamus. Consequently, GABA neurotransmission may serve both excitatory and inhibitory roles during early development. PMID:8842004

  15. Dopamine receptor antagonist blocks the release of glycine, GABA, and taurine produced by amphetamine.

    PubMed

    Porras, A; Mora, F

    1993-01-01

    The effects of systemic injections of amphetamine sulfate on the extracellular levels of glycine, GABA, and taurine in the neostriatum of awake rats were studied using a push-pull perfusion system. Amphetamine produced a dose-related increase in glycine levels. Amphetamine also produced an enhancement on GABA and taurine levels, although these increases did not follow a dose-related curve. The percentage increase of amino acids produced by the highest dose of amphetamine (5 mg/kg) at the peak effect was: GLY 235.9%; GABA 218%, and TAU 177%. All these effects were blocked by the D1-D2 dopamine receptor antagonist, haloperidol. It is suggested that dopamine, released by amphetamine, induces the release of inhibitory amino acid neurotransmitters in the neostriatum. These results are consistent with the hypothesis of dopamine playing a role of an amplifier of the activity of different neurochemical circuits. The results are also in accord with the idea that dopamine could mediate the neurotoxic effects produced by amphetamines through an interplay between excitatory and inhibitory amino acids.

  16. Lack of functional GABA(B) receptors alters GnRH physiology and sexual dimorphic expression of GnRH and GAD-67 in the brain.

    PubMed

    Catalano, Paolo N; Di Giorgio, Noelia; Bonaventura, María M; Bettler, Bernhard; Libertun, Carlos; Lux-Lantos, Victoria A

    2010-03-01

    GABA, the main inhibitory neurotransmitter, acts through GABA(A/C) and GABA(B) receptors (GABA(B)Rs); it is critical for gonadotropin regulation. We studied whether the lack of functional GABA(B)Rs in GABA(B1) knockout (GABA(B1)KO) mice affected the gonadotropin axis physiology. Adult male and female GABA(B1)KO and wild-type (WT) mice were killed to collect blood and tissue samples. Gonadotropin-releasing hormone (GnRH) content in whole hypothalami (HT), olfactory bulbs (OB), and frontoparietal cortexes (CT) were determined (RIA). GnRH expression by quantitative real-time PCR (qRT-PCR) was evaluated in preoptic area-anterior hypothalamus (POA-AH), medial basal-posterior hypothalamus (MBH-PH), OB, and CT. Pulsatile GnRH secretion from hypothalamic explants was measured by RIA. GABA, glutamate, and taurine contents in HT and CT were determined by HPLC. Glutamic acid decarboxylase-67 (GAD-67) mRNA was measured by qRT-PCR in POA-AH, MBH-PH, and CT. Gonadotropin content, serum levels, and secretion from adenohypophyseal cell cultures (ACC) were measured by RIA. GnRH mRNA expression was increased in POA-AH of WT males compared with females; this pattern of expression was inversed in GABA(B1)KO mice. MBH-PH, OB, and CT did not follow this pattern. In GABA(B1)KO females, GnRH pulse frequency was increased and GABA and glutamate contents were augmented. POA-AH GAD-67 mRNA showed the same expression pattern as GnRH mRNA in this area. Gonadotropin pituitary contents and serum levels showed no differences between genotypes. Increased basal LH secretion and decreased GnRH-stimulated gonadotropin response were observed in GABA(B1)KO female ACCs. These results support the hypothesis that the absence of functional GABA(B)Rs alters GnRH physiology and critically affects sexual dimorphic expression of GnRH and GAD-67 in POA-AH.

  17. Cardiovascular and behavioral effects produced by administration of liposome-entrapped GABA into the rat central nervous system.

    PubMed

    Vaz, G C; Bahia, A P C O; de Figueiredo Müller-Ribeiro, F C; Xavier, C H; Patel, K P; Santos, R A S; Moreira, F A; Frézard, F; Fontes, M A P

    2015-01-29

    Liposomes are nanosystems that allow a sustained release of entrapped substances. Gamma-aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter of the central nervous system (CNS). We developed a liposomal formulation of GABA for application in long-term CNS functional studies. Two days after liposome-entrapped GABA was injected intracerebroventricularly (ICV), Wistar rats were submitted to the following evaluations: (1) changes in mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) to ICV injection of bicuculline methiodide (BMI) in anesthetized rats; (2) changes in cardiovascular reactivity to air jet stress in conscious rats; and (3) anxiety-like behavior in conscious rats. GABA and saline-containing pegylated liposomes were prepared with a mean diameter of 200 nm. Rats with implanted cannulas targeted to lateral cerebral ventricle (n = 5-8/group) received either GABA solution (GS), empty liposomes (EL) or GABA-containing liposomes (GL). Following (48 h) central microinjection (2 μL, 0.09 M and 99 g/L) of liposomes, animals were submitted to the different protocols. Animals that received GL demonstrated attenuated response of RSNA to BMI microinjection (GS 48 ± 9, EL 43 ± 9, GL 11 ± 8%; P < 0.05), blunted tachycardia in the stress trial (ΔHR: GS 115 ± 14, EL 117 ± 10, GL 74 ± 9 bpm; P<0.05) and spent more time in the open arms of elevated plus maze (EL 6 ± 2 vs. GL 18 ± 5%; P = 0.028) compared with GS and EL groups. These results indicate that liposome-entrapped GABA can be a potential tool for exploring the chronic effects of GABA in specific regions and pathways of the central nervous system.

  18. Comparative inhibitory effects of niflumic acid and novel synthetic derivatives on the rat isolated stomach fundus.

    PubMed

    Criddle, David N; Meireles, AnaVanescaP; Macêdo, Liana B; Leal-Cardoso, José H; Scarparo, Henrique C; Jaffar, Mohammed

    2002-02-01

    Novel derivatives of 2-[3-(trifluoromethyl)-analino]nicotinic acid (niflumic acid) were synthesized. The compounds were compared for their inhibitory effects on 5-hydroxytryptamine (5-HT)- and KCI-induced contraction of the rat fundus. The aim was to assess structure-activity relationships regarding the selectivity and potency of these compounds. Niflumic acid (1-100 microM) concentration-dependently inhibited 5-HT-induced tonic contractions with an IC50 value (concentration reducing the control contractile response by 50%, calculated from semi-log graphs) of 0.24 x 10(4) M (n = 9). In contrast, it was significantly less potent at inhibiting KCl-induced responses (IC50 = 1.49 x 10(4) M, n = 9). The methyl ester (NFAme) and amido (NFAm) analogues showed no selectivity between 5-HT- and KCl-induced contractions with IC50 values of 1.64 x 10(-4) M (n = 8) and 1.87 x 10(-4) M (n = 9) for 5-HT responses, and 2.61 x 10(-4) M (n = 8) and 2.55 x 10(-4) M (n = 7) for KCl-induced responses, respectively. Our results suggest that alteration of the carboxylic acid moiety of niflumic acid reduces the selectivity and potency of its inhibitory action on 5-HT-induced contractile responses of the rat fundus, possibly via a reduced interaction with calcium-activated chloride channels.

  19. Substance P selectively modulates GABA(A) receptor-mediated synaptic transmission in striatal cholinergic interneurons.

    PubMed

    Govindaiah, G; Wang, Yanyan; Cox, Charles L

    2010-02-01

    Substance P (SP) is co-localized and co-released with gamma-amino butyric acid (GABA) from approximately 50% of GABAergic medium spiny neurons (MSNs) in the striatum. MSNs innervate several cellular targets including neighboring MSNs and cholinergic interneurons via collaterals. However, the functional role of SP release onto striatal interneurons is unknown. Here we examined SP-mediated actions on inhibitory synaptic transmission in cholinergic interneurons using whole-cell recordings in mouse corticostriatal slices. We found that SP selectively suppressed GABA(A) receptor-mediated inhibitory post-synaptic currents (IPSCs), but not excitatory post-synaptic currents (EPSCs) in cholinergic interneurons. In contrast, SP did not alter IPSCs in fast-spiking interneurons and MSNs. SP suppressed IPSC amplitude in a concentration-dependent and reversible manner, and the NK1 receptor antagonist RP67580 attenuated the SP-mediated suppression. In addition, RP67580 alone enhanced the evoked IPSC amplitude in cholinergic interneurons, suggesting an endogenous action of SP on regulation of inhibitory synaptic transmission. SP did not alter the paired-pulse ratio, but reduced the amplitudes of GABA(A) agonist muscimol-induced outward currents and miniature IPSCs in cholinergic interneurons, suggesting SP exerts its effects primarily at the post-synaptic site. Our results indicate that the physiological effects of SP are to enhance the activity of striatal cholinergic interneurons and provide a rationale for designing potential new antiparkinsonian agents.

  20. Pharmacology of the inhibitory glycine receptor: agonist and antagonist actions of amino acids and piperidine carboxylic acid compounds.

    PubMed

    Schmieden, V; Betz, H

    1995-11-01

    To define structure-activity relations for ligands binding to the inhibitory glycine receptor (GlyR), the agonistic and antagonistic properties of alpha- and beta-amino acids were analyzed at the recombinant human alpha 1 GlyR expressed in Xenopus oocytes. The agonistic activity of alpha-amino acids exhibited a marked stereoselectivity and was highly susceptible to substitutions at the C alpha-atom. In contrast, alpha-amino acid antagonism was not enantiomer dependent and was influenced little by C alpha-atom substitutions. The beta-amino acids taurine, beta-aminobutyric acid (beta-ABA), and beta-aminoisobutyric acid (beta-AIBA) are partial agonists at the GlyR. Low concentrations of these compounds competitively inhibited glycine responses, whereas higher concentrations elicited a significant membrane current. Nipecotic acid, which contains a trans-beta-amino acid configuration, behaved as purely competitive GlyR antagonist. Our data are consistent with the existence of a common binding site for all amino acid agonists and antagonists, at which the functional consequences of binding depend on the particular conformation a given ligand adopts within the binding pocket. In the case of beta-amino acids, the trans conformation appears to mediate antagonistic receptor binding, and the cis conformation appears to mediate agonistic receptor binding. This led us to propose that the partial agonist activity of a given beta-amino acid is determined by the relative mole fractions of the respective cis/trans conformers.

  1. Role of gamma-aminobutyric acid (GABA) and metabotropic glutamate receptors in nicotine reinforcement: potential pharmacotherapies for smoking cessation.

    PubMed

    Markou, Athina; Paterson, Neil E; Semenova, Svetlana

    2004-10-01

    Previous work indicated a role for GABA and glutamate in the reinforcing effects of drugs of abuse. The present studies assessed the effects of GABAergic and glutamatergic manipulations on the reinforcing effects of nicotine as assessed by intravenous nicotine self-administration. Male Wistar rats were allowed to self-administer either of two nicotine doses under a fixed ratio or a progressive ratio schedule of reinforcement. The effects of a glutamatergic compound on nicotine self-administration in male DBA/2J mice were also explored. Finally, to assess for nonspecific effects of the drug manipulations, the effects of all test compounds on responding maintained by a food reinforcer were investigated. The pharmacological manipulations used were: gamma-vinyl-GABA (vigabatrin or GVG), an irreversible inhibitor of GABA transaminase, the GABAB receptor agonists (-)baclofen and CGP44532, and the metabotropic glutamate receptor 5 (mGluR5) antagonist MPEP. GVG, CGP44532, and (-)baclofen dose-dependently decreased nicotine self-administration on the fixed-ratio schedule, but also decreased food-maintained responding. Furthermore, CGP44532 decreased breakpoints for nicotine and food at identical doses under the progressive-ratio schedule. MPEP dose-dependently decreased nicotine self-administration with no effect on food-maintained responding in rats. MPEP also decreased nicotine self-administration in the mice. These results demonstrate that activation of GABAB receptors or blockade of mGluR5 decreased nicotine self-administration. Although there was some selectivity for the effects of the GABAergic manipulations, there was clear selectivity of the effects of MPEP on nicotine- versus food-maintained responding. Thus, compounds that increase GABAergic neurotransmission and antagonists at mGluR5 have potential as anti-smoking medications for humans.

  2. An in vitro study of the relationship between GABA receptor function and propulsive motility in the distal colon of the rabbit.

    PubMed

    Tonini, M; Crema, A; Frigo, G M; Rizzi, C A; Manzo, L; Candura, S M; Onori, L

    1989-12-01

    1. The effects of gamma-aminobutyric acid (GABA), 3-aminopropane sulphonic acid (3-APS) and baclofen on spontaneous, electrically-induced and propulsive motility were investigated in rabbit distal colon. 2. In unstimulated longitudinal (LMPs) and circular muscle strip preparations (CMPs) 3-APS (10-200 microM) and GABA caused a clear-cut relaxation susceptible to desensitization. Baclofen (10-200 microM) caused relaxation in a minority (30%) of preparations. The 3-APS response was sensitive to tetrodotoxin (TTX; 1 microM), SR 95531 (a novel competitive GABAA-receptor antagonist) (10 microM), picrotoxinin (30 microM), and insensitive to hyoscine (1 microM) and to a combination of prazosin (1 microM) and propranolol (1 microM). The baclofen response was antagonized by 5-aminovaleric acid (DAVA, 500 microM), TTX and hyoscine and resistant to GABAA-receptor and adrenoceptor blockade. GABAA-receptors were therefore associated with non-adrenergic non-cholinergic (NANC) inhibitory nerve activation while GABAB-receptors were involved in depression of cholinergic tone of smooth muscle. GABA (10-200 microM) elicited both above mentioned effects. 3. In LMPs, baclofen (10-200 microM) dose-dependently inhibited submaximal responses to both cholinergic and NANC inhibitory nerve stimulation. This effect was resistant to SR 95531 and picrotoxinin and prevented by DAVA and baclofen desensitization. GABA (10-200 microM) mimicked the action of baclofen. GABA inhibitory effects persisted in the presence of GABAA-receptor blockade. 4. In segments of distal colon, GABA and baclofen (1-200 microM), but not 3-APS (1-200 microM), dose-dependently decreased the velocity of propulsion of an intraluminally-distended balloon. This effect was antagonized by DAVA and GABA or baclofen desensitization and resistant to SR 95531 and picrotoxinin. These antagonists per se had no effect on propulsion. In preparations in which propulsion was slowed by hyoscine (1 microM), baclofen caused no consistent

  3. Valproic acid mediates the synaptic excitatory/inhibitory balance through astrocytes--a preliminary study.

    PubMed

    Wang, Chao-Chuan; Chen, Po See; Hsu, Chien-Wen; Wu, Shou-Jung; Lin, Chieh-Ting; Gean, Po Wu

    2012-04-27

    Valproic acid (VPA) is one of the most widely used anticonvulsant and mood-stabilizing agents for the treatment of epilepsy and bipolar disorder. However, the underlying therapeutic mechanisms of the treatment of each disease remain unclear. Recently, the anti-epileptic effect of VPA has been found to lead to modulation of the synaptic excitatory/inhibitory balance. In addition, the therapeutic action of VPA has been linked to its effect on astrocytes by regulating gene expression at the molecular level, perhaps through an epigenetic mechanism as a histone deacetylase (HDAC) inhibitor. To provide insight into the mechanisms underlying the actions of VPA, this study investigated whether the synaptic excitatory/inhibitory (E/I) balance could be mediated by VPA through astrocytes. First, using the primary rat neuronal, astroglial, and neuro-glial mixed culture systems, we demonstrated that VPA treatment could regulate the mRNA levels of two post-synaptic cell adhesion molecules(neuroligin-1 and neuregulin-1) and two extracellular matrices (neuronal pentraxin-1and thrombospondin-3) in primary rat astrocyte cultures in a time- and concentration-dependent manner. Moreover, the up-regulation effect of VPA was noted in astrocytes, but not in neurons. In addition, these regulatory effects could be mimicked by sodium butyrate, a HDAC inhibitor, but not by lithium or two other glycogen synthase kinase-3 beta inhibitors. With the known role of these four proteins in regulating the synaptic E/I balance, we further demonstrated that VPA increased excitatory post-synaptic protein (postsynaptic density 95) and inhibitory post-synaptic protein (Gephyrin) in cortical neuro-glial mixed cultures. Our results suggested that VPA might affect the synaptic excitatory/inhibitory balance through its effect on astrocytes. This work provides the basis for future evaluation of the role of astroglial cell adhesion molecules and the extracellular matrix on the control of excitatory and

  4. Coenzyme Q releases the inhibitory effect of free fatty acids on mitochondrial glycerophosphate dehydrogenase.

    PubMed

    Rauchová, Hana; Drahota, Zdenek; Rauch, Pavel; Fato, Romana; Lenaz, Giorgio

    2003-01-01

    Data presented in this paper show that the size of the endogenous coenzyme Q (CoQ) pool is not a limiting factor in the activation of mitochondrial glycerophosphate-dependent respiration by exogenous CoQ(3), since successive additions of succinate and NADH to brown adipose tissue mitochondria further increase the rate of oxygen uptake. Because the inhibition of glycerophosphate-dependent respiration by oleate was eliminated by added CoQ(3), our data indicate that the activating effect of CoQ(3) is related to the release of the inhibitory effect of endogenous free fatty acids (FFA). Both the inhibitory effect of FFA and the activating effect of CoQ(3) could be demonstrated only for glycerophosphate-dependent respiration, while succinate- or NADH-dependent respiration was not affected. The presented data suggest differences between mitochondrial glycerophosphate dehydrogenase and succinate or NADH dehydrogenases in the transfer of reducing equivalents to the CoQ pool.

  5. Antioxidant Activity and α-Glucosidase Inhibitory Activities of the Polycondensate of Catechin with Glyoxylic Acid

    PubMed Central

    Ma, Hanjun; Liu, Benguo

    2016-01-01

    In order to investigate polymeric flavonoids, the polycondensate of catechin with glyoxylic acid (PCG) was prepared and its chemically antioxidant, cellular antioxidant (CAA) and α-glucosidase inhibitory activities were evaluated. The DPPH and ABTS radical scavenging activities and antiproliferative effect of PCG were lower than those of catechin, while PCG had higher CAA activity than catechin. In addition, PCG had very high α-glucosidase inhibitory activities (IC50 value, 2.59 μg/mL) in comparison to catechin (IC50 value, 239.27 μg/mL). Inhibition kinetics suggested that both PCG and catechin demonstrated a mixture of noncompetitive and anticompetitive inhibition. The enhanced CAA and α-glucosidase inhibitor activities of PCG could be due to catechin polymerization enhancing the binding capacity to the cellular membrane and enzymes. PMID:26960205

  6. Antioxidant Activity and α-Glucosidase Inhibitory Activities of the Polycondensate of Catechin with Glyoxylic Acid.

    PubMed

    Geng, Sheng; Shan, Sharui; Ma, Hanjun; Liu, Benguo

    2016-01-01

    In order to investigate polymeric flavonoids, the polycondensate of catechin with glyoxylic acid (PCG) was prepared and its chemically antioxidant, cellular antioxidant (CAA) and α-glucosidase inhibitory activities were evaluated. The DPPH and ABTS radical scavenging activities and antiproliferative effect of PCG were lower than those of catechin, while PCG had higher CAA activity than catechin. In addition, PCG had very high α-glucosidase inhibitory activities (IC50 value, 2.59 μg/mL) in comparison to catechin (IC50 value, 239.27 μg/mL). Inhibition kinetics suggested that both PCG and catechin demonstrated a mixture of noncompetitive and anticompetitive inhibition. The enhanced CAA and α-glucosidase inhibitor activities of PCG could be due to catechin polymerization enhancing the binding capacity to the cellular membrane and enzymes.

  7. Taurine and beta-alanine act on both GABA and glycine receptors in Xenopus oocyte injected with mouse brain messenger RNA.

    PubMed

    Horikoshi, T; Asanuma, A; Yanagisawa, K; Anzai, K; Goto, S

    1988-09-01

    The responding pathway (process from agonist binding to channel opening) of taurine and beta-alanine was investigated in Xenopus oocytes injected with mouse brain poly(A)+ RNA. Responses to gamma-aminobutyric acid (GABA), glycine, taurine and beta-alanine were induced in oocytes injected with poly(A)+ RNA extracted from 3 regions, cerebrum, cerebellum and brainstem of the mouse brain. From comparison, responses to these 4 inhibitory amino acids in each regional poly(A)+ RNA-injected oocytes were categorized into at least 3 groups: (1) GABA, (2) glycine, and (3) taurine and beta-alanine. No cross-desensitization was observed between GABA response and glycine response, but taurine and beta-alanine responses cross-desensitized both the GABA and glycine responses. Taurine and beta-alanine responses were partially inhibited by the GABA antagonist, bicuculline, and also by the glycine antagonist, strychnine. The results suggest that the taurine or the beta-alanine response in the brain is caused through both the GABA receptor and the glycine receptor.

  8. The influence of fig proteases on the inhibition of angiotensin I-converting and GABA formation in meat.

    PubMed

    Li, Jinyue; Izumimoto, Masatoshi; Yonehara, Makiko; Hirotsu, Seiya; Kuriki, Takayoshi; Naito, Ichiro; Yamada, Hidenori

    2009-12-01

    The purposes of this research were to use fig protease for texture tenderizing, and to inhibit angiotensin I-converting enzyme (ACE) action and gamma-aminobutyric acid (GABA) formation of meat. Liberated peptides by the enzymatic action of fig protease in processing meat and free amino acids were determined and ACE inhibitory activity was assayed. Meat treated with fig protease became tender as indicated by shear force value (SFV) which was half of those of non-fig treated meat during storage even at 5 degrees C. Liberated peptides, free amino acids and GABA increased while extremely low levels of Glu were detected after storage. The optimal temperature of fig protease against meat was 80 degrees C. However, the activity of fig protease decreased after pre-heating more than 40 degrees C. High ACE inhibitory activity of a mixture of fig and meat was found around 80 degrees C, and the value corresponded to the amount of liberated peptide. A lot of liberated peptides were found at 60-80 degrees C and pasterization of meat product becomes convenient to produce peptides. Production of ACE inhibitory peptides and GABA can be expected as the healthy functional meat product such as antihypertensive activity and improve brain function.

  9. Inhibitory mechanism of l-glutamic acid on spawning of the starfish Patiria (Asterina) pectinifera.

    PubMed

    Mita, Masatoshi

    2016-12-22

    l-Glutamic acid was previously identified as an inhibitor of spawning in the starfish Patiria (Asterina) pectinifera; this study examined how l-glutamic acid works. Oocyte release from ovaries of P. pectinifera occurred after germinal vesicle breakdown (GVBD) and follicular envelope breakdown (FEBD) when gonads were incubated ex vivo with either relaxin-like gonad-stimulating peptide (RGP) or 1-methyladenine (1-MeAde). l-Glutamic acid blocked this spawning phenotype, causing the mature oocytes to remain within the ovaries. Neither RGP-induced 1-MeAde production in ovarian follicle cells nor 1-MeAde-induced GVBD and FEBD was affected by l-glutamic acid. l-Glutamic acid may act through metabotropic receptors in the ovaries to inhibit spawning, as l-(+)-2-amino-4-phosphonobutyric acid, an agonist for metabotropic glutamate receptors, also inhibited spawning induced by 1-MeAde. Application of acetylcholine (ACH) to ovaries under inhibitory conditions with l-glutamic acid, however, brought about spawning, possibly by inducing contraction of the ovarian wall to discharge mature oocytes from the ovaries concurrently with GVBD and FEBD. Thus, l-glutamic acid may inhibit ACH secretion from gonadal nerve cells in the ovary. Mol. Reprod. Dev. 2016. © 2016 Wiley Periodicals, Inc.

  10. Separation of gamma-aminobutyric acid from fermented broth.

    PubMed

    Li, Haixing; Qiu, Ting; Chen, Yan; Cao, Yusheng

    2011-12-01

    Gamma-aminobutyric acid (GABA) is a non-proteinaceous amino acid that is widely distributed in nature and acts as the major inhibitory neurotransmitter in the mammalian brain. This study aimed to find a separation method for getting high-purity GABA from a fermented broth. Firstly, a fermented broth with a high content of GABA (reaching 997 ± 51 mM) was prepared by fermentation with Lactobacillus brevis NCL912. GABA purification was conducted by successive centrifugation, filtration, decoloration, desalination, ion-exchange chromatography (IEC), and crystallization. Inorganic salt (Na₂SO₄) was removed from the both by desalination with 70% ethanol solution. A ninhydrin test strip was designed for the real-time detection of GABA during IEC. The recovery rate for the whole purification process was about 50%. The purified product was characterized by thin-layer chromatography and HPLC, and its purity reached 98.66 ± 2.36%.

  11. GnRH neuron firing and response to GABA in vitro depend on acute brain slice thickness and orientation.

    PubMed

    Constantin, Stephanie; Piet, Richard; Iremonger, Karl; Hwa Yeo, Shel; Clarkson, Jenny; Porteous, Robert; Herbison, Allan E

    2012-08-01

    The GnRH neurons exhibit long dendrites and project to the median eminence. The aim of the present study was to generate an acute brain slice preparation that enabled recordings to be undertaken from GnRH neurons maintaining the full extent of their dendrites or axons. A thick, horizontal brain slice was developed, in which it was possible to record from the horizontally oriented GnRH neurons located in the anterior hypothalamic area (AHA). In vivo studies showed that the majority of AHA GnRH neurons projected outside the blood-brain barrier and expressed c-Fos at the time of the GnRH surge. On-cell recordings compared AHA GnRH neurons in the horizontal slice (AHAh) with AHA and preoptic area (POA) GnRH neurons in coronal slices [POA coronal (POAc) and AHA coronal (AHAc), respectively]. AHAh GnRH neurons exhibited tighter burst firing compared with other slice orientations. Although α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) excited GnRH neurons in all preparations, γ-aminobutyric acid (GABA) was excitatory in AHAc and POAc but inhibitory in AHAh slices. GABA(A) receptor postsynaptic currents were the same in AHAh and AHAc slices. Intriguingly, direct activation of GABA(A) or GABA(B) receptors respectively stimulated and inhibited GnRH neurons regardless of slice orientation. Subsequent experiments indicated that net GABA effects were determined by differences in the ratio of GABA(A) and GABA(B) receptor-mediated effects in "long" and "short" dendrites of GnRH neurons in the different slice orientations. These studies document a new brain slice preparation for recording from GnRH neurons with their extensive dendrites/axons and highlight the importance of GnRH neuron orientation relative to the angle of brain slicing in studying these neurons in vitro.

  12. The inhibitory effect of metals and other ions on acid phosphatase activity from Vigna aconitifolia seeds.

    PubMed

    Srivastava, Pramod Kumar; Anand, Asha

    2015-01-01

    Sensitivity of acid phosphatase from Vigna aconitifolia seeds to metal ions, fluoride, and phosphate was examined. All the effectors had different degree of inhibitory effect on the enzyme. Among metal ions, molybdate and ferric ion were observed to be most potent inhibitors and both exhibited mixed type of inhibition. Acid phosphatase activity was inhibited by Cu2+ in a noncompetitive manner. Zn and Mn showed mild inhibition on the enzyme activity. Inhibition kinetics analysis explored molybdate as a potent inhibitor for acid phosphatase in comparison with other effectors used in this study. Fluoride was the next most strong inhibitor for the enzyme activity, and caused a mixed type of inhibition. Phosphate inhibited the enzyme competitively, which demonstrates that inhibition due to phosphate is one of the regulatory factors for enzyme activity.

  13. Library screening by means of mass spectrometry (MS) binding assays-exemplarily demonstrated for a pseudostatic library addressing γ-aminobutyric acid (GABA) transporter 1 (GAT1).

    PubMed

    Sindelar, Miriam; Wanner, Klaus T

    2012-09-01

    In the present study, the application of mass spectrometry (MS) binding assays as a tool for library screening is reported. For library generation, dynamic combinatorial chemistry (DCC) was used. These libraries can be screened by means of MS binding assays when appropriate measures are taken to render the libraries pseudostatic. That way, the efficiency of MS binding assays to determine ligand binding in compound screening with the ease of library generation by DCC is combined. The feasibility of this approach is shown for γ-aminobutyric acid (GABA) transporter 1 (GAT1) as a target, representing the most important subtype of the GABA transporters. For the screening, hydrazone libraries were employed that were generated in the presence of the target by reacting various sets of aldehydes with a hydrazine derivative that is delineated from piperidine-3-carboxylic acid (nipecotic acid), a common fragment of known GAT1 inhibitors. To ensure that the library generated is pseudostatic, a large excess of the nipecotic acid derivative is employed. As the library is generated in a buffer system suitable for binding and the target is already present, the mixtures can be directly analyzed by MS binding assays-the process of library generation and screening thus becoming simple to perform. The binding affinities of the hits identified by deconvolution were confirmed in conventional competitive MS binding assays performed with single compounds obtained by separate synthesis. In this way, two nipecotic acid derivatives exhibiting a biaryl moiety, 1-{2-[2'-(1,1'-biphenyl-2-ylmethylidene)hydrazine]ethyl}piperidine-3-carboxylic acid and 1-(2-{2'-[1-(2-thiophenylphenyl)methylidene]hydrazine}ethyl)piperidine-3-carboxylic acid, were found to be potent GAT1 ligands exhibiting pK(i) values of 6.186 ± 0.028 and 6.229 ± 0.039, respectively. This method enables screening of libraries, whether generated by conventional chemistry or DCC, and is applicable to all kinds of targets including

  14. How and why does tomato accumulate a large amount of GABA in the fruit?

    PubMed Central

    Takayama, Mariko; Ezura, Hiroshi

    2015-01-01

    Gamma-aminobutyric acid (GABA) has received much attention as a health-promoting functional compound, and several GABA-enriched foods have been commercialized. In higher plants, GABA is primarily metabolized via a short pathway called the GABA shunt. The GABA shunt bypasses two steps (the oxidation of α-ketoglutarate to succinate) of the tricarboxylic acid (TCA) cycle via reactions catalyzed by three enzymes: glutamate decarboxylase, GABA transaminase, and succinic semialdehyde dehydrogenase. The GABA shunt plays a major role in primary carbon and nitrogen metabolism and is an integral part of the TCA cycle under stress and non-stress conditions. Tomato is one of the major crops that accumulate a relatively high level of GABA in its fruits. The GABA levels in tomato fruits dramatically change during fruit development; the GABA levels increase from flowering to the mature green stage and then rapidly decrease during the ripening stage. Although GABA constitutes up to 50% of the free amino acids at the mature green stage, the molecular mechanism of GABA accumulation and the physiological function of GABA during tomato fruit development remain unclear. In this review, we summarize recent studies of GABA accumulation in tomato fruits and discuss the potential biological roles of GABA in tomato fruit development. PMID:26322056

  15. Effect of various GABA-receptor agonists and antagonists on anaphylactic histamine release in the guinea-pig ileum.

    PubMed

    Luzzi, S; Franchi-Micheli, S; Ciuffi, M; Rosi, E; Zilletti, L

    1987-04-01

    In this paper we confirm the previously reported inhibition by GABA of anaphylactic histamine release from isolated guinea-pig ileum longitudinal muscle. Moreover we report that: GABA-inhibition of anaphylactic histamine release is mimicked both by GABA-A and GABA-B agonists; both GABA-A and GABA-B antagonists are effective in reversing GABA's inhibitory effect; the effect is exerted specifically by GABA-ergic drugs: taurine and beta-alanine are ineffective; the GABA-ergic effect seems not to involve cholinergic and adrenergic transmission. It is concluded that it might be interesting to assess the clinical value of GABA-ergic drugs in allergic gut disorders.

  16. Electrochemical evaluation of the inhibitory effects of weak acids on Zygosaccharomyces bailii.

    PubMed

    Zhao, Jinsheng; Yang, Zhenyu; Wang, Min; Lu, Yao; Yang, Zhengyu

    2004-12-01

    The changes in intracellular redox activity or in mitochondrial electron transport could be taken as indications of the changes in the physiological state of living cells, based on which a mediated electrochemical method was purposed to evaluate the inhibitory effects of weak acids on Zygosaccharomyces bailii, a known food spoilage yeast. The dual mediator systems menadione/ferricyanide and 2,6-dichlorophenolindophenol/ferricyanide were employed as probes to detect the variance in intracellular redox activity and in mitochondrial electron flux, respectively. Measurements were made with a microelectrode voltammetric method to assay the ferrocyanide accumulations arising from menadione- or 2,6-dichlorophenolindophenol-mediated reduction of ferricyanide by Z. bailii suspensions by the presence or absence of increasing concentrations of weak acids. The results obtained from 2 h of incubation showed that the variance in electrochemical response revealed some physiological information underlying the inhibitory effects of weak acid on the yeast. For the first time, it was shown that the mediated electrochemical method provides an adjunct to the conventional method based on respiration inhibition for establishing levels for the utilization of preservatives in the food industry.

  17. The aging human cochlear nucleus: Changes in the glial fibrillary acidic protein, intracellular calcium regulatory proteins, GABA neurotransmitter and cholinergic receptor.

    PubMed

    Sharma, Saroj; Nag, Tapas C; Thakar, Alok; Bhardwaj, Daya N; Roy, Tara Sankar

    2014-03-01

    The human auditory system is highly susceptible to environmental and metabolic insults which further affect the biochemical and physiological milieu of the cells that may contribute to progressive, hearing loss with aging. The cochlear nucleus (CN) is populated by morphologically diverse types of neurons with discrete physiological and neurochemical properties. Between the dorsal and the ventral cochlear nucleus (DCN and VCN), the VCN is further sub-divided into the rostral (rVCN) and caudal (cVCN) sub-divisions. Although, information is available on the age related neurochemical changes in the mammalian CN similar reports on human CN is still sparse. The morphometry and semiquantitative analysis of intensity of expression of glial fibrillary acidic protein (GFAP), calcium binding proteins (calbindin, calretinin and parvalbumin), gamma amino butyric acid (GABA) and nicotinic acetyl choline receptor (nAchR) beta 2 immunostaining were carried out in all three sub-divisions of the human CN from birth to 90 years. There was increased GFAP immunoreactivity in decades 2 and 3 in comparison to decade 1 in the CN. But no change was observed in rVCN from decade 4 onwards, whereas intense staining was also observed in decades 5 and 6 in cVCN and DCN. All three calcium binding proteins were highly expressed in early to middle ages, whereas a significant reduction was found in later decades in the VCN. GABA and nAchR beta 2 expressions were unchanged throughout in all the decades. The middle age may represent a critical period of onset and progression of aging changes in the CN and these alterations may add to the deterioration of hearing responses in the old age.

  18. Active transport of. gamma. -aminobutyric acid and glycine into synaptic vesicles

    SciTech Connect

    Kish, P.E.; Fischer-Bovenkerk, C.; Ueda, T. )

    1989-05-01

    Although {gamma}-aminobutyric acid (GABA) and glycine are recognized as major amino acid inhibitory neurotransmitters in the central nervous system, their storage is poorly understood. In this study the authors have characterized vesicular GABA and glycine uptakes in the cerebrum and spinal cord, respectively. They present evidence that GABA and glycine are each taken up into isolated synaptic vesicles in an ATP-dependent manner and that the uptake is driven by an electrochemical proton gradient. Uptake for both amino acids exhibited kinetics with low affinity similar to a vesicular glutamate uptake. The ATP-dependent GABA uptake was not inhibited by the putative amino acid neurotransmitters glycine, taurine, glutamate, or aspartate or by GABA analogs, agonists, and antagonists. Similarly, ATP-dependent glycine uptake was hardly affected by GABA, taurine, glutamate, or aspartate or by glycine analogs or antagonists. The GABA uptake was not affected by chloride, which is in contrast to the uptake of the excitatory neurotransmitter glutamate, whereas the glycine uptake was slightly stimulated by low concentrations of chloride. Tissue distribution studies indicate that the vesicular uptake systems for GABA, glycine, and glutamate are distributed in different proportions in the cerebrum and spinal cord. These results suggest that the vesicular uptake systems for GABA, glycine, and glutamate are distinct from each other.

  19. 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

  20. Decreased auditory GABA+ concentrations in presbycusis demonstrated by edited magnetic resonance spectroscopy.

    PubMed

    Gao, Fei; Wang, Guangbin; Ma, Wen; Ren, Fuxin; Li, Muwei; Dong, Yuling; Liu, Cheng; Liu, Bo; Bai, Xue; Zhao, Bin; Edden, Richard A E

    2015-02-01

    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 cm(3) 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.

  1. Effect of taurine on the concentrations of glutamate, GABA, glutamine and alanine in the rat striatum and hippocampus.

    PubMed

    Molchanova, Svetlana M; Oja, Simos S; Saransaari, Pirjo

    2007-01-01

    Taurine, a non-protein amino acid, acts as an osmoregulator and inhibitory neuromodulator in the brain. Here we studied the effects of intraperitoneal injections of taurine on the concentrations of glutamate and GABA, and their precursors, glutamine and alanine, in the rat striatum and hippocampus. Injections of 0.25, 0.5 and 1 g/kg taurine led to a gradual increase in taurine tissue concentrations in both hippocampus and striatum. Glutamate and GABA also increased in the hippocampus, but not in the striatum. Glutamine increased and alanine decreased markedly in both brain structures. The results corroborate the neuromodulatory role of taurine in the brain. Taurine administration results in an imbalance in inhibitory and excitatory neurotransmission in the glutamatergic (hippocampus) and GABAergic (striatum) brain structures, affecting more markedly the neurotransmitter precursors.

  2. GABA and glycine actions on spinal motoneurons.

    PubMed

    Krnjević, K; Puil, E; Werman, R

    1977-06-01

    Applied microiontophoretically in the spinal cord of cats, glycine is consistently more powerful than gamma-aminobutyric acid (GABA) in raising the membrane conductance of lumbosacral motoneurons (mean ratio of equipotent iontophoretic currents tested on same cells is 5.6:1). This is the reverse of the situation in cerebral cortex. The effect of glycine is well maintained during applications lasting about 1 min, but that of GABA, after an early peak, drops to a much lower plateau (mean plateau-over-peak ratio is 0.23). The reversal potentials for the action of GABA and glycine are initially similar but they behave differently during a prolonged application; that for glycine usually remains constant or becomes more negative whereas that for GABA tends to shift in the positive direction. Various explanations of these phenomena are considered. It is suggested that a single process, electrogenic uptake of GABA, may account for both desensitization (by removing GABA from its site of action) and the positive shift in GABA reversal potential (became uptake is probably associated with an influx of Na+).

  3. An mRNA encoding a putative GABA-gated chloride channel is expressed in the human cardiac conduction system.

    PubMed

    Garret, M; Bascles, L; Boue-Grabot, E; Sartor, P; Charron, G; Bloch, B; Margolskee, R F

    1997-04-01

    GABA-gated chloride channels are the main inhibitory neurotransmitter receptors in the CNS. Conserved domains among members of previously described GABAA receptor subunits were used to design degenerate sense and antisense oligonucleotides. A PCR product from this amplification was used to isolate a full-length cDNA. The predicted protein has many of the features shared by other members of the ligand-gated ion channel family. This channel subunit has significant amino acid identity (25-40%) with members of GABAA and GABAC receptor subunits and thus may represent a new subfamily of the GABA receptor channel. Although we cannot rule out that this clone encodes a receptor for an unidentified ligand, it was termed GABA chi. This gene is mainly expressed in placenta and in heart; however, placenta appears to express only an unspliced mRNA. In situ hybridization reveals that the GABA chi subunit mRNA is present in the electrical conduction system of the human heart. Our results suggest that novel GABA receptors expressed outside of the CNS may regulate cardiac function.

  4. GABA depolarizes immature neurons and inhibits network activity in the neonatal neocortex in vivo.

    PubMed

    Kirmse, Knut; Kummer, Michael; Kovalchuk, Yury; Witte, Otto W; Garaschuk, Olga; Holthoff, Knut

    2015-07-16

    A large body of evidence from in vitro studies suggests that GABA is depolarizing during early postnatal development. However, the mode of GABA action in the intact developing brain is unknown. Here we examine the in vivo effects of GABA in cells of the upper cortical plate using a combination of electrophysiological and Ca(2+)-imaging techniques. We report that at postnatal days (P) 3-4, GABA depolarizes the majority of immature neurons in the occipital cortex of anaesthetized mice. At the same time, GABA does not efficiently activate voltage-gated Ca(2+) channels and fails to induce action potential firing. Blocking GABA(A) receptors disinhibits spontaneous network activity, whereas allosteric activation of GABA(A) receptors has the opposite effect. In summary, our data provide evidence that in vivo GABA acts as a depolarizing neurotransmitter imposing an inhibitory control on network activity in the neonatal (P3-4) neocortex.

  5. NSAIDs modulate GABA-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons

    PubMed Central

    ZHAO, LEI; LI, LI; MA, KE-TAO; WANG, YANG; LI, JING; SHI, WEN-YAN; ZHU, HE; ZHANG, ZHONG-SHUANG; SI, JUN-QIANG

    2016-01-01

    The ability of non-steroidal anti-inflammatory drugs (NSAIDs) to modulate γ-aminobutyrate (GABA)-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons (DRG), was examined in the present study. During the preparation of DRG neurons harvested from Sprague-Dawley rats, the whole-cell recording technique was used to record the effect of NSAIDs on GABA-activated inward currents, and the expression levels of the TMEM16A and TMEM16B subunits were revealed. In the event that DRG neurons were pre-incubated for 20 sec with niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) prior to the administration of GABA, the GABA-induced inward currents were diminished markedly in the majority of neurons examined (96.3%). The inward currents induced by 100 µmol/l GABA were attenuated by (0±0.09%; neurons = 4), (5.32±3.51%; neurons = 6), (21.3±4.00%; neurons = 5), (33.8±5.20%; neurons = 17), (52.2±5.10%; neurons = 4) and (61.1±4.12%; neurons = 12) by 0.1, 1, 3, 10, 30 and 100 µmol/l NFA, respectively. The inward currents induced by 100 µmol/l GABA were attenuated by (13.8±6%; neurons = 6), (23.2±14.7%; neurons = 6) and (29.7±9.1%; neurons = 9) by 3, 10 and 30 µmol/l NPPB, respectively. NFA and NPPB dose-dependently inhibited GABA-activated currents with half maximal inhibitory concentration (IC50) values of 6.7 and 11 µmol/l, respectively. The inhibitory effect of 100 µmol/l NFA on the GABA-evoked inward current were also strongly inhibited by nitrendipine (NTDP; an L-type calcium channel blocker), 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetrakis (a highly selective calcium chelating reagent), caffeine (a widely available Ca2+ consuming drug) and calcium-free extracellular fluid, in a concentration-dependent manner. Immunofluorescent staining indicated that TMEM16A and TMEM16B expression was widely distributed in DRG neurons. The results suggest that NSAIDs may be able to regulate Ca2

  6. An excitatory GABA loop operating in vivo

    PubMed Central

    Astorga, Guadalupe; Bao, Jin; Marty, Alain; Augustine, George J.; Franconville, Romain; Jalil, Abdelali; Bradley, Jonathan; Llano, Isabel

    2015-01-01

    While it has been proposed that the conventional inhibitory neurotransmitter GABA can be excitatory in the mammalian brain, much remains to be learned concerning the circumstances and the cellular mechanisms governing potential excitatory GABA action. Using a combination of optogenetics and two-photon calcium imaging in vivo, we find that activation of chloride-permeable GABAA receptors in parallel fibers (PFs) of the cerebellar molecular layer of adult mice causes parallel fiber excitation. Stimulation of PFs at submaximal stimulus intensities leads to GABA release from molecular layer interneurons (MLIs), thus creating a positive feedback loop that enhances excitation near the center of an activated PF bundle. Our results imply that elevated chloride concentration can occur in specific intracellular compartments of mature mammalian neurons and suggest an excitatory role for GABAA receptors in the cerebellar cortex of adult mice. PMID:26236197

  7. Docking of fatty acids into the WIF domain of the human Wnt inhibitory factor-1.

    PubMed

    Malinauskas, Tomas

    2008-03-01

    Palmitoylated Wnt proteins comprise a conserved family of secreted signaling molecules associated with variety of human cancers. WIF domain of the human WIF (Wnt inhibitory factor)-1 is sufficient for Wnt binding and signaling inhibition. Detailed interactions between Wnt and WIF-1 are not known. Computational docking was employed to identify a possible fatty acid binding site in the WIF domain. A putative binding site was identified inside the domain. WIF domain exhibited the highest affinity for C16:0-C18:0 (-22 kJ/mol free energy of binding) fatty acids. The results suggest a role of the WIF domain as a palmitoyl binding domain required for WIF-1 binding to palmitoylated Wnt and signaling inhibition.

  8. Oxytocin regulates changes of extracellular glutamate and GABA levels induced by methamphetamine in the mouse brain.

    PubMed

    Qi, Jia; Han, Wen-Yan; Yang, Jing-Yu; Wang, Li-Hui; Dong, Ying-Xu; Wang, Fang; Song, Ming; Wu, Chun-Fu

    2012-07-01

    Oxytocin (OT), a neurohypophyseal neuropeptide, affects adaptive processes of the central nervous system. In the present study, we investigated the effects of OT on extracellular levels of glutamate (Glu) and γ-aminobutyric acid (GABA) induced by methamphetamine (MAP) in the medial prefrontal cortex (mPFC) and dorsal hippocampus (DHC) of freely moving mice, using in vivo microdialysis coupled to high-performance liquid chromatography and fluorescence detection. The results showed that OT had no effect on basal Glu levels, but attenuated MAP-induced Glu increase in the mPFC and decrease in the DHC. OT increased the basal levels of extracellular GABA in mPFC and DHC of mice, and inhibited the MAP-induced GABA decrease in DHC. Western blot results indicated that OT significantly inhibited the increased glutamatergic receptor (NR1 subunit) levels in the PFC after acute MAP administration, whereas OT further enhanced the elevated levels of glutamatergic transporter (GLT1) induced by MAP in the hippocampus of mice. Atosiban, a selective inhibitor of OT receptor, antagonized the effects of OT. The results provided the first neurochemical evidence that OT, which exerted its action via its receptor, decreased Glu release induced by MAP, and attenuated the changes in glutamatergic neurotransmission partially via regulation of NR1 and GLT1 expression. OT-induced extracellular GABA increase also suggests that OT acts potentially as an inhibitory neuromodulator in mPFC and DHC of mice.

  9. Increased GABA concentrations in type 2 diabetes mellitus are related to lower cognitive functioning

    PubMed Central

    van Bussel, Frank C.G.; Backes, Walter H.; Hofman, Paul A.M.; Puts, Nicolaas A.J.; Edden, Richard A.E.; van Boxtel, Martin P.J.; Schram, Miranda T.; Stehouwer, Coen D.A.; Wildberger, Joachim E.; Jansen, Jacobus F.A.

    2016-01-01

    Abstract Type 2 diabetes mellitus is associated with accelerated cognitive decline. The underlying pathophysiological mechanisms still remain to be elucidated although it is known that insulin signaling modulates neurotransmitter activity, including inhibitory γ-aminobutyric acid (GABA) and excitatory glutamate (Glu) receptors. Therefore, we examined whether levels of GABA and Glu are related to diabetes status and cognitive performance. Forty-one participants with type 2 diabetes and 39 participants without type 2 diabetes underwent detailed cognitive assessments and 3-Tesla proton MR spectroscopy. The associations of neurotransmitters with type 2 diabetes and cognitive performance were examined using multivariate regression analyses controlling for age, sex, education, BMI, and percentage gray/white matter ratio in spectroscopic voxel. Analysis revealed higher GABA+ levels in participants with type 2 diabetes, in participants with higher fasting blood glucose levels and in participants with higher HbA1c levels, and higher GABA+ levels in participants with both high HbA1c levels and less cognitive performance. To conclude, participants with type 2 diabetes have alterations in the GABAergic neurotransmitter system, which are related to lower cognitive functioning, and hint at the involvement of an underlying metabolic mechanism. PMID:27603392

  10. 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.

  11. Structural determinants of activity at the GABAB receptor. A comparison of phosphoethanolamine and related GABA analogs.

    PubMed

    Klunk, W E; McClure, R J; Xu, C J; Pettegrew, J W

    1995-09-01

    Phosphoethanolamine is a phosphomonoester that is reduced in Alzheimer disease brain. Despite its close structural similarity to GABA and the GABAB partial agonist 3-aminopropylphosphonic acid, phosphoethanolamine binds very poorly to GABAB receptors (IC50 = 7.5 +/- 0.8 mM). In this study, we examined whether the marked decrease in binding affinity associated with the presence of an ester oxygen in place of the alpha-CH2 group of GABAergic compounds also occurred in sulfonates and used high resolution solution NMR and molecular mechanics calculations to determine the structural basis of this decrease in activity. The sulfonate analog of GABA, 3-amino-propylsulfonic acid, became > 2500-fold less potent when the alpha-CH2 was replaced by an ester oxygen. Structural studies showed that the active alpha-CH2 compounds (GABA, 3-aminopropylphosphonic acid, and 3-aminopropylsulfonic acid) prefer a fully extended conformation. The inactive compounds, phosphoethanolamine and ethanolamine-O-sulfate, exist in a gauche conformation around the C beta-C gamma bond. This study, which suggests conformational differences, may explain how PE can be so efficiently excluded from GABAB receptors, despite being present in millimolar concentrations in brain. Exclusion of phosphoethanolamine from GABAB receptors may be an important physiologic control mechanism in the regulation of inhibitory neurotransmission.

  12. Inhibitory effect of vanillic acid on methylglyoxal-mediated glycation in apoptotic Neuro-2A cells.

    PubMed

    Huang, Shang-Ming; Hsu, Chin-Lin; Chuang, Hong-Chih; Shih, Ping-Hsiao; Wu, Chi-Hao; Yen, Gow-Chin

    2008-11-01

    Methylglyoxal is a reactive dicarbonyl compound generated as an intermediate of glycolysis during the physical glycation in the diabetic condition. It is considered to be a potent precursor of advanced glycation end products (AGEs) formation. Methylglyoxal itself and methylglyoxal-derived AGEs have been commonly implicated in the development of diabetic neuropathy. Our previous study indicated that vanillic acid showed an inhibitory effect against methylglyoxal-mediated Neuro-2A cell apoptosis, suggesting that vanillic acid might possess cytoprotective properties in the prevention of diabetic neuropathy complication. In this study, the effects of vanillic acid on the methylglyoxal-mediated glycation system involved in the progression of Neuro-2A cell apoptosis were further investigated. Our findings indicated that methylglyoxal-induced Neuro-2A cell apoptosis was mediated through the possible glycation mechanism of oxidative stress, activation of the MAPK signaling pathway (p38 and JNK) and oxidation-sensitive protein expression (PKC and p47(phox)) and methylglyoxal-derived N-epsilon-(carboxymethyl)lysine (CML) formation. Vanillic acid, however, suppressed methylglyoxal-induced Neuro-2A cell apoptosis via inhibition of glycation mechanisms including ROS, p38 and JNK, PKC and p47(phox), and methylglyoxal-derived CML formation. In the present study, we established the first evidence that vanillic acid might contribute to the prevention of the development of diabetic neuropathy by blocking the methylglyoxal-mediated intracellular glycation system.

  13. Guinea Pig Horizontal Cells Express GABA, the GABA-Synthesizing Enzyme GAD65, and the GABA Vesicular Transporter

    PubMed Central

    Guo, Chenying; Hirano, Arlene A.; Stella, Salvatore L.; Bitzer, Michaela; Brecha, Nicholas C.

    2013-01-01

    γ-Aminobutyric acid (GABA) is likely expressed in horizontal cells of all species, although conflicting physiological findings have led to considerable controversy regarding its role as a transmitter in the outer retina. This study has evaluated key components of the GABA system in the outer retina of guinea pig, an emerging retinal model system. The presence of GABA, its rate-limiting synthetic enzyme glutamic acid decarboxylase (GAD65 and GAD67 isoforms), the plasma membrane GABA transporters (GAT-1 and GAT-3), and the vesicular GABA transporter (VGAT) was evaluated by using immunohistochemistry with well-characterized antibodies. The presence of GAD65 mRNA was also evaluated by using laser capture microdissection and reverse transcriptase-polymerase chain reaction. Specific GABA, GAD65, and VGAT immunostaining was localized to horizontal cell bodies, as well as to their processes and tips in the outer plexiform layer. Furthermore, immunostaining of retinal whole mounts and acutely dissociated retinas showed GAD65 and VGAT immunoreactivity in both A-type and B-type horizontal cells. However, these cells did not contain GAD67, GAT-1, or GAT-3 immunoreactivity. GAD65 mRNA was detected in horizontal cells, and sequencing of the amplified GAD65 fragment showed approximately 85% identity with other mammalian GAD65 mRNAs. These studies demonstrate the presence of GABA, GAD65, and VGAT in horizontal cells of the guinea pig retina, and support the idea that GABA is synthesized from GAD65, taken up into synaptic vesicles by VGAT, and likely released by a vesicular mechanism from horizontal cells. PMID:20235161

  14. Inhibitory Effect of Long-Chain Fatty Acids on Biogas Production and the Protective Effect of Membrane Bioreactor

    PubMed Central

    Dasa, Kris Triwulan; Westman, Supansa Y.; Cahyanto, Muhammad Nur; Niklasson, Claes

    2016-01-01

    Anaerobic digestion of lipid-containing wastes for biogas production is often hampered by the inhibitory effect of long-chain fatty acids (LCFAs). In this study, the inhibitory effects of LCFAs (palmitic, stearic, and oleic acid) on biogas production as well as the protective effect of a membrane bioreactor (MBR) against LCFAs were examined in thermophilic batch digesters. The results showed that palmitic and oleic acid with concentrations of 3.0 and 4.5 g/L resulted in >50% inhibition on the biogas production, while stearic acid had an even stronger inhibitory effect. The encased cells in the MBR system were able to perform better in the presence of LCFAs. This system exhibited a significantly lower percentage of inhibition than the free cell system, not reaching over 50% at any LCFA concentration tested. PMID:27699172

  15. The role of inhibitory amino acidergic neurotransmission in hepatic encephalopathy: a critical overview.

    PubMed

    Albrecht, Jan; Zielińska, Magdalena

    2002-12-01

    Gamma-Aminobutyric acid (GABA) is the main inhibitory amino acid in the central nervous system (CNS). Experiments with animal models of HE, and with brain slices or cultured CNS cells treated with ammonia, have documented changes in GABA distribution and transport, and modulation of the responses of both the GABA(A)-benzodiazepine receptor complex and GABA(B) receptors. Although many of the data point to an enhancement of GABAergic transmission probably contributing to HE, the evidence is not unequivocal. The major weaknesses of the GABA theory are (1) in a vast majority of HE models, there were no alterations of GABA content in the brain tissue and/or extracellular space, indicating that exposure of neurons to GABA may not have been altered, (2) changes in the affinity and capacity of GABA receptor binding were either absent or qualitatively different in HE models of comparable severity and duration, and (3) no sound changes in the GABAergic system parameters were noted in clinical cases of HE. Taurine (Tau) is an amino acid that is thought to mimic GABA function because of its agonistic properties towards GABA(A) receptors, and to contribute to neuroprotection and osmoregulation. These effects require Tau redistribution between the different cell compartments and the extracellular space. Acute treatment with ammonia evokes massive release of radiolabeled or endogenous Tau from CNS tissues in vivo and in vitro, and the underlying mechanism of Tau release differs from the release evoked by depolarizing conditions or hypoosmotic treatment. Subacute or chronic HE, and also long-term treatment of cultured CNS cells in vitro with ammonia, increase spontaneous Tau "leakage" from the tissue. This is accompanied by a decreased potassium- or hypoosmolarity-induced release of Tau and often by cell swelling, indicating impaired osmoregulation. In in vivo models of HE, Tau leakage is manifested by its increased accumulation in the extrasynaptic space, which may promote

  16. Effects of prenatal exposure to 2,4-D/2,4,5-T mixture on postnatal changes in rat brain glutamate, GABA protein, and nucleic acid levels

    SciTech Connect

    Mohammad, F.K.; Omer, V.E.V.

    1988-02-01

    The opportunity of maternal exposure to various chemicals in the work place and the general environments have increased, and the fetus and neonate may be at greater risk than the adult. However, the embryotoxic and teratogenic effects of the chlorinated phenoxy herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), the main chemicals in Agent Orange, are well documented only in laboratory animals. The brain of the developing fetus is vulnerable to the toxic effects of the phenoxy herbicides which readily cross the placental barrier and distribute into fetal tissues, including brain. Although the neurochemical basis for the behavioral teratogenicity of the phenoxy herbicides is not know, it was recently reported that non-teratogenic doses of a 1:1 mixture of 2,4-D and 2,4,5-T delayed the ontogeny of dopamine and serotonin in the brain of the developing rate. This communication provides further descriptive information about the ontogeny of rat brain nucleic acid, protein, glutamate and ..gamma..-aminobutyrate (GABA) following in utero exposure to non-teratogenic levels of a 1:1 mixture of 2,4-D/2,4,5-T.

  17. Novel sirtuin inhibitory warheads derived from the N(ε)-acetyl-lysine analog L-2-amino-7-carboxamidoheptanoic acid.

    PubMed

    He, Yanhua; Yan, Lingling; Zang, Wenwen; Zheng, Weiping

    2015-11-14

    Built upon the catalytic mechanism-based pan-SIRT1/2/3 inhibitory warhead L-2-amino-7-carboxamidoheptanoic acid (L-ACAH, a close structural analog of N(ε)-acetyl-lysine) that our laboratory discovered recently, in the current study, its carboxamide NH2-ethylated analog was found to be a ∼2.4-6.6-fold stronger SIRT1/2/3 inhibitory warhead than L-ACAH. Carboxamide NH2-dodecylated and carboxymethylated analogs of L-ACAH were also identified as potent SIRT6 and SIRT5 inhibitory warheads, respectively.

  18. Oxytocin-mediated GABA inhibition during delivery attenuates autism pathogenesis in rodent offspring.

    PubMed

    Tyzio, Roman; Nardou, Romain; Ferrari, Diana C; Tsintsadze, Timur; Shahrokhi, Amene; Eftekhari, Sanaz; Khalilov, Ilgam; Tsintsadze, Vera; Brouchoud, Corinne; Chazal, Genevieve; Lemonnier, Eric; Lozovaya, Natalia; Burnashev, Nail; Ben-Ari, Yehezkel

    2014-02-07

    We report that the oxytocin-mediated neuroprotective γ-aminobutyric acid (GABA) excitatory-inhibitory shift during delivery is abolished in the valproate and fragile X rodent models of autism. During delivery and subsequently, hippocampal neurons in these models have elevated intracellular chloride levels, increased excitatory GABA, enhanced glutamatergic activity, and elevated gamma oscillations. Maternal pretreatment with bumetanide restored in offspring control electrophysiological and behavioral phenotypes. Conversely, blocking oxytocin signaling in naïve mothers produced offspring having electrophysiological and behavioral autistic-like features. Our results suggest a chronic deficient chloride regulation in these rodent models of autism and stress the importance of oxytocin-mediated GABAergic inhibition during the delivery process. Our data validate the amelioration observed with bumetanide and oxytocin and point to common pathways in a drug-induced and a genetic rodent model of autism.

  19. Assignment of the human GABA transporter gene (GABATHG) locus to chromosome 3p24-p25

    SciTech Connect

    Huang, Fang; Fei, Jian; Guo, Li-He

    1995-09-01

    An essential regulatory process of synaptic transmission is the inactivation of released neurotransmitters by the transmitter-specific uptake mechanism, {gamma}-Aminobutyric acid (GABA) is an inhibitory transmitter in the vertebrate central nervous system; its activity is terminated by a high-affinity Na{sup +} and Cl{sup -} -dependent specific GABA transporter (GAT), which carries the neurotransmitter to the presynaptic neuron and/or glial elements surrounding the synaptic cleft. Deficiency of the transporter may cause epilepsy and some other nervous diseases. The human GAT gene (GABATHG), approximately 25 kb in length, has been cloned and sequenced by our colleagues (7). Here the results of the in situ hybridization mapping with the gene are presented. 10 refs., 1 fig.

  20. GABA Metabolism and Transport: Effects on Synaptic Efficacy

    PubMed Central

    Roth, Fabian C.; Draguhn, Andreas

    2012-01-01

    GABAergic inhibition is an important regulator of excitability in neuronal networks. In addition, inhibitory synaptic signals contribute crucially to the organization of spatiotemporal patterns of network activity, especially during coherent oscillations. In order to maintain stable network states, the release of GABA by interneurons must be plastic in timing and amount. This homeostatic regulation is achieved by several pre- and postsynaptic mechanisms and is triggered by various activity-dependent local signals such as excitatory input or ambient levels of neurotransmitters. Here, we review findings on the availability of GABA for release at presynaptic terminals of interneurons. Presynaptic GABA content seems to be an important determinant of inhibitory efficacy and can be differentially regulated by changing synthesis, transport, and degradation of GABA or related molecules. We will discuss the functional impact of such regulations on neuronal network patterns and, finally, point towards pharmacological approaches targeting these processes. PMID:22530158

  1. [GABA-Receptors in Modulation of Fear Memory Extinction].

    PubMed

    Dubrovina, N I

    2016-01-01

    GABA is the major inhibitory neurotransmitter in the central nervous system determining the efficacy of neuronal interaction. GABA-receptors play a key role in different aspects of fear memory--acquisition and consolidation, retention, reconsolidation and extinction. Extinction is an important behavioural phenomenon which allows organism to adapt its behavior to a changing environment. Extinction of fear memory is a form of new inhibitory learning which interferes with expression of the initial acquired fear conditioning. Resistance to extinction is symptom of depression and posttraumatic stress disorder. The aim of the present review was to summarize own and literary data about GABAergic modulation of fear extinction and pharmacological correction of extinction impairment at influences on GABA(A)- and GABA(B)- receptors.

  2. Marlin-1, a novel RNA-binding protein associates with GABA receptors.

    PubMed

    Couve, Andrés; Restituito, Sophie; Brandon, Julia M; Charles, Kelly J; Bawagan, Hinayana; Freeman, Katie B; Pangalos, Menelas N; Calver, Andrew R; Moss, Stephen J

    2004-04-02

    GABA(B) receptors are heterodimeric G protein-coupled receptors that mediate slow synaptic inhibition in the central nervous system. Whereas heterodimerization between GABA(B) receptor GABA(B)R1 and GABA(B)R2 subunits is essential for functional expression, how neurons coordinate the assembly of these critical receptors remains to be established. Here we have identified Marlin-1, a novel GABA(B) receptor-binding protein that associates specifically with the GABA(B)R1 subunit in yeast, tissue culture cells, and neurons. Marlin-1 is expressed in the brain and exhibits a granular distribution in cultured hippocampal neurons. Marlin-1 binds different RNA species including the 3'-untranslated regions of both the GABA(B)R1 and GABA(B)R2 mRNAs in vitro and also associates with RNA in cultured neurons. Inhibition of Marlin-1 expression via small RNA interference technology results in enhanced intracellular levels of the GABA(B)R2 receptor subunit without affecting the level of GABA(B)R1. Together our results suggest that Marlin-1 functions to regulate the cellular levels of GABA(B) R2 subunits, which may have significant effects on the production of functional GABA(B) receptor heterodimers. Therefore, our observations provide an added level of regulation for the control of GABA(B) receptor expression and for the efficacy of inhibitory synaptic transmission.

  3. gamma-Aminobutyric acid agonists and antagonists alter chloride flux across brain membranes.

    PubMed

    Allan, A M; Harris, R A

    1986-05-01

    gamma-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the mammalian brain, increases membrane chloride conductance. Previously, we reported that GABA increases 36Cl- uptake by membrane vesicles (microsacs) prepared from mouse brain. Employing this technique, we found that the GABAA agonists, muscimol, isoguvacine, 4,5,6,7-tetrahydroisoxazolo(5,4-C)pyridine-3-ol, and 3-amino-1-propane sulfonate, all produced a concentration-dependent increase in 36Cl- influx, but baclofen, a GABAB agonist, failed to alter 36Cl- flux. Inhibition of GABA-dependent 36Cl- influx was produced by the convulsant drugs, bicuculline, picrotoxin, and pentylenetetrazole. Ion specificity was demonstrated by a failure of GABA agonists to stimulate influx of 45Ca2+, 86Rb+, 22Na+, or 35SO4(2). GABA-stimulated uptake of 36Cl- was largest in cortex and cerebellum and smaller in hippocampus and striatum. There was little difference in sensitivity to GABA among the areas. Analysis of subcellular fractions prepared from mouse brain demonstrated that the GABA-dependent 36Cl- influx was enriched in the synaptosomal fraction. The nonspecific (GABA-independent) uptake of 36Cl- was enriched in the myelin fraction. These experiments provide evidence for a functional coupling among GABA receptors and the chloride ionophore and suggest that the GABA-activated chloride channel is a site of action for several convulsant compounds.

  4. An extract of Gymnema sylvestre leaves and purified gymnemic acid inhibits glucose-stimulated gastric inhibitory peptide secretion in rats.

    PubMed

    Fushiki, T; Kojima, A; Imoto, T; Inoue, K; Sugimoto, E

    1992-12-01

    Gastric inhibitory peptide release into the portal vein in response to duodenal infusion of D-glucose was studied in the presence of a leaf extract of Gymnema sylvestre, purified gymnemic acid and inhibitors of some putative glucose sensors and carriers in the intestinal lumen. Intraduodenal infusion of D-glucose significantly increased the portal immunoreactive gastric inhibitory peptide concentration in a dose-dependent manner. The increase in the portal immunoreactive gastric inhibitory peptide induced by glucose was significantly depressed by concomitantly infused leaf extract of Gymnema sylvestre, purified gymnemic acid and phlorizin but not by cytochalasin B. Mannoheptulose, which inhibits glycolysis, and procaine and lidocaine, which inhibit the vagal glucoreceptor in the lumen, did not affect portal immunoreactive gastric inhibitory peptide concentrations. These results suggest that a glucose receptor, which interacts with the leaf extract of Gymnema sylvestre, purified gymnemic acid and phlorizin, exists for the release of immunoreactive gastric inhibitory peptide and that the glucose receptor for gastric inhibitory peptide release is not likely to be identical with a glucose transporter or a vagal glucoreceptor in the lumen.

  5. Cannabidiolic acid as a selective cyclooxygenase-2 inhibitory component in cannabis.

    PubMed

    Takeda, Shuso; Misawa, Koichiro; Yamamoto, Ikuo; Watanabe, Kazuhito

    2008-09-01

    In the present study it was revealed that cannabidiolic acid (CBDA) selectively inhibited cyclooxygenase (COX)-2 activity with an IC(50) value (50% inhibition concentration) around 2 microM, having 9-fold higher selectivity than COX-1 inhibition. In contrast, Delta(9)-tetrahydrocannabinolic acid (Delta(9)-THCA) was a much less potent inhibitor of COX-2 (IC(50) > 100 microM). Nonsteroidal anti-inflammatory drugs containing a carboxyl group in their chemical structures such as salicylic acid are known to inhibit nonselectively both COX-1 and COX-2. CBDA and Delta(9)-THCA have a salicylic acid moiety in their structures. Thus, the structural requirements for the CBDA-mediated COX-2 inhibition were next studied. There is a structural difference between CBDA and Delta(9)-THCA; phenolic hydroxyl groups of CBDA are freed from the ring formation with the terpene moiety, although Delta(9)-THCA has dibenzopyran ring structure. It was assumed that the whole structure of CBDA is important for COX-2 selective inhibition because beta-resorcylic acid itself did not inhibit COX-2 activity. Methylation of the carboxylic acid moiety of CBDA led to disappearance of COX-2 selectivity. Thus, it was suggested that the carboxylic acid moiety in CBDA is a key determinant for the inhibition. Furthermore, the crude extract of cannabis containing mainly CBDA was shown to have a selective inhibitory effect on COX-2. Taken together, these lines of evidence in this study suggest that naturally occurring CBDA in cannabis is a selective inhibitor for COX-2.

  6. Targeting BACE with small inhibitory nucleic acids - a future for Alzheimer's disease therapy?

    PubMed

    Nawrot, Barbara

    2004-01-01

    beta-Secretase, a beta-site amyloid precursor protein (APP) cleaving enzyme (BACE), participates in the secretion of beta-amyloid peptides (Abeta), the major components of the toxic amyloid plaques found in the brains of patients with Alzheimer's disease (AD). According to the amyloid hypothesis, accumulation of Abeta is the primary influence driving AD pathogenesis. Lowering of Abeta secretion can be achieved by decreasing BACE activity rather than by down-regulation of the APP substrate protein. Therefore, beta-secretase is a primary target for anti-amyloid therapeutic drug design. Several approaches have been undertaken to find an effective inhibitor of human beta-secretase activity, mostly in the field of peptidomimetic, non-cleavable substrate analogues. This review describes strategies targeting BACE mRNA recognition and its down-regulation based on the antisense action of small inhibitory nucleic acids (siNAs). These include antisense oligonucleotides, catalytic nucleic acids - ribozymes and deoxyribozymes - as well as small interfering RNAs (siRNAs). While antisense oligonucleotides were first used to identify an aspartyl protease with beta-secretase activity, all the strategies now demonstrate that siNAs are able to inhibit BACE gene expression in a sequence-specific manner, measured both at the level of its mRNA and at the level of protein. Moreover, knock-down of BACE reduces the intra- and extracellular population of Abeta40 and Abeta42 peptides. An anti-amyloid effect of siNAs is observed in a wide spectrum of cell lines as well as in primary cortical neurons. Thus targeting BACE with small inhibitory nucleic acids may be beneficial for the treatment of Alzheimer's disease and for future drug design.

  7. Putative TRP channel antagonists, SKF 96365, flufenamic acid and 2-APB, are non-competitive antagonists at recombinant human α1β2γ2 GABA(A) receptors.

    PubMed

    Rae, M G; Hilton, J; Sharkey, J

    2012-05-01

    Although transient receptor potential (TRP) channel biology research has expanded rapidly in recent years, the field is hampered by the widely held, but relatively poorly investigated, belief that most of the pharmacological tools used to investigate TRP channel function may not be particularly selective for their intended targets. The objective of this study was therefore to determine if this was indeed the case by systematically evaluating the effects of three routinely used putative TRP channel antagonists, SKF 96365, flufenamic acid (FF) and 2-aminoethoxydiphenyl borate (2-APB) against one of the most widely expressed CNS receptor subtypes CNS, the human α1β2γ2 GABA(A) receptor. Using whole cell patch-clamp recording to record responses to rapidly applied GABA in the absence and presence of the three putative antagonists in turn we found that SKF 96365 (1-100 μM) and FF (1-100 μM) significantly inhibited GABA responses of recombinant human α1β2γ2 GABA(A) receptor stably expressed in HEK293 cells with IC(50) values of 13.4 ± 5.1 and 1.9 ± 1.4 μM, respectively, suppressing the maximal response to GABA at all concentrations used in a manner consistent with a non-competitive mode of action. SKF 96365 and FF also both significantly reduced desensitisation and prolonged the deactivation kinetics of the receptors to GABA (1mM; P<0.05). 2-APB (10-1000 μM) also inhibited responses to GABA at all concentrations used with an IC(50) value of 16.7 ± 5.4 μM (n=3-5) but had no significant effect on the activation, desensitisation or deactivation kinetics of the GABA responses. Taken together this investigation revealed that these widely utilised TRP channel antagonists display significant 'off-target' effects at concentrations that are routinely used for the study of TRP channel function in numerous biological systems and as such, data which is obtained utilising these compounds should be interpreted with caution.

  8. Physiological inhibitory effect of ocs in arachidonic acid-rich Parietochloris incisa (trebouxiophyceae, chlorophyta)

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Guo; Zhang, Cheng-Wu; Cohen, Zvi; Richmond, Amos

    2002-09-01

    Parietochloris incisa is an arachidonic acid-rich snow green alga. The main physiological profiles, such as ash free dry weight (AFDW), chlorophyll, carotenoid, protein and total fatty acids (TFA), in this alga exposed to old culture supernatant (OCS) at the decline phase or its crude ethyl acetate extracts (CEAE) were investigated by using tubular photobioreactors of different diameters. Results showed that both OCS and CEAE had strong inhibitory effect on the above physiological parameters. The longer the culture was exposed to OCS and the more CEAE were added into the algal culture, the more the above physiological properties were inhibited. Arachidonic acid (AA), the dominant component of fatty acids in this alga, was also seriously inhibited with respect to total TFA, AFDW of cell mass, or culture volume, due to a probable reduction of enzymes activities catalyzing chain elongation from C18; 1ω9 to AA. These results incontestably evidenced that some CEAE dissolving substances existing in OCS. like auto-inhibitors, inhibited P. incisa growth through feedback. Hence, any efficient removal of auto-inhibitors from algal culture to decrease their bioactivity could be good for maximal production of desired products like AA.

  9. Green Synthesis and Urease Inhibitory Activity of Spiro-Pyrimidinethiones/Spiro-Pyrimidinones-Barbituric Acid Derivatives

    PubMed Central

    Mohammadi Ziarani, Ghodsi; Asadi, Shima; Faramarzi, Sakineh; Amanlou, Massoud

    2015-01-01

    Sulfonic acid functionalized SBA-15 (SBA-Pr-SO3H) with pore size 6 nm as an efficient heterogeneous nanoporous solid acid catalyst exhibited good catalytic activity in the Biginelli-like reaction in the synthesis of spiroheterobicyclic rings with good yield and good recyclability. Spiro-pyrimidinethiones/spiro-pyrimidinones-barbituric acid derivatives were synthesized in a simple and efficient method using the one-pot three-component reaction of a cyclic 1,3- dicarbonyl compounds (barbituric acid), an aromatic aldehyde and urea or thiourea in the presence of nanoporous silica SBA-Pr-SO3H under solvent free conditions. Urease inhibitory activity of spiro compounds were tested against Jack bean urease using Berthelot alkaline phenol–hypochlorite method. Five of 13 compounds were inhibitor and two of them were enzyme activators. Analysis of the docking results showed that, in most of the spiro molecules, one of the carbonyl groups is coordinated with both nickel atoms, while the other one is involved in the formation of hydrogen bonds with important active-site residues. The effect of inserting two methyl groups on N atoms of barbiturate ring, S substituted, ortho, meta and para substituted compounds were investigated too. PMID:26664377

  10. Inhibitory effects of sea buckthorn procyanidins on fatty acid synthase and MDA-MB-231 cells.

    PubMed

    Wang, Yi; Nie, Fangyuan; Ouyang, Jian; Wang, Xiaoyan; Ma, Xiaofeng

    2014-10-01

    Fatty acid synthase (FAS) is overexpressed in many human cancers including breast cancer and is considered to be a promising target for therapy. Sea buckthorn has long been used to treat a variety of maladies. Here, we investigated the inhibitory effect of sea buckthorn procyanidins (SBPs) isolated from the seeds of sea buckthorn on FAS and FAS overexpressed human breast cancer MDA-MB-231 cells. The FAS activity and FAS inhibition were measured by a spectrophotometer at 340 nm of nicotinamide adenine dinucleotide phosphate (NADPH) absorption. We found that SBP potently inhibited the activity of FAS with a half-inhibitory concentration (IC50) value of 0.087 μg/ml. 3-4,5-Dimethylthiazol-2-yl-2,3-diphenyl tetrazolium bromide (MTT) assay was used to test the cell viability. SBP reduced MDA-MB-231 cell viability with an IC50 value of 37.5 μg/ml. Hoechst 33258/propidium iodide dual staining and flow cytometric analysis showed that SBP induced MDA-MB-231 cell apoptosis. SBP inhibited intracellular FAS activity with a dose-dependent manner. In addition, sodium palmitate could rescue the cell apoptosis induced by SBP. These results showed that SBP was a promising FAS inhibitor which could induce the apoptosis of MDA-MB-231 cells via inhibiting FAS. These findings suggested that SBP might be useful for preventing or treating breast cancer.

  11. Involvement of glutamate and gamma-aminobutyric acid (GABA)-ergic systems in thyrotropin-releasing hormone-induced rat cerebellar cGMP formation.

    PubMed

    Nakayama, T; Hashimoto, T; Nagai, Y

    1996-12-05

    The increase in cyclic guanosine 3',5'-monophosphate (cGMP) caused by subcutaneous injection of thyrotropin-releasing hormone (TRH) tartrate was observed in a region-specific manner in the rat cerebellum. TRH tartrate (TRH-T) (2.8, 7.0 and 17 mg/kg as free TRH, s.c.) produced dose-dependent increases in cGMP levels markedly in the cerebellar superior and inferior vermis, and a smaller but still significant increase in the cerebellar hemispheres and brainstem but no significant increases in other brain regions. The TRH-induced increase in the cGMP level in the cerebellum was suppressed by pretreatment with muscimol, THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3(2H)-one) or MK-801 (dizocilpine maleate) and partially suppressed by atropine but was not suppressed by chlordiazepoxide, oxazepam, phentolamine, propranolol, cyproheptadine, haloperidol, baclofen or DNQX (6,7-dinitroquinoxaline-2,3-dione), suggesting the possible involvement of GABA (gamma-aminobutyric acid)(A)-ergic, N-methyl-D-aspartate (NMDA)-type glutamatergic and cholinergic systems. These results suggest that excitatory amino acids may be involved in the cGMP formation caused by TRH in the cerebellar areas, and that cGMP formation is inhibited by enhancement of GABAA receptor function.

  12. A role for sodium and chloride in kainic acid-induced beading of inhibitory interneuron dendrites.

    PubMed

    Al-Noori, S; Swann, J W

    2000-01-01

    Excitotoxic injury of the dendrites of inhibitory interneurons could lead to decreases in their synaptic activation and explain subsequent local circuit hyperexcitability and epilepsy. A hallmark of dendrotoxicity, at least in principal neurons of the hippocampus and cortex, is focal or varicose swellings of dendritic arbors. In experiments reported here, transient (1h) exposure of hippocampal explant cultures to kainic acid produced marked focal swellings of the dendrites of parvalbumin-immunoreactive pyramidal basket cells in a highly reproducible and dose-dependent manner. At 5mM kainic acid, more than half of the immunopositive apical dendrites in area CA(1) had a beaded appearance. However, the somal volumes of these cells were unaltered by the same treatment. The presence of focal swellings was reversible with kainate washout and was not accompanied by interneuronal cell death. In contrast, exposure to much higher concentrations (300mM) of kainic acid resulted in the total loss of parvalbumin-positive interneurons from explants. Surprisingly, kainic acid-induced dendritic beading does not appear to be mediated by extracellular calcium. Beading was unaltered in the presence of N-methyl-D-aspartate receptor antagonists, the L-type calcium channel antagonist, nimodipine, cadmium, or by removing extracellular calcium. However, blockade of voltage-gated sodium channels by either tetrodotoxin or lidocaine abolished dendritic beading, while the activation of existing voltage-gated sodium channels by veratridine mimicked the kainic acid-induced dendritic beading. Finally, the removal of extracellular chloride prevented the kainic acid-induced dendritic beading.Thus, we suggest that the movement of Na(+) and Cl(-), rather than Ca(2+), into cells underlies the focal swellings of interneuron dendrites in hippocampus.

  13. Fatty acids from the cyanobacterium Microcystis aeruginosa with potent inhibitory effects on fish gill Na+/K+-ATPase activity.

    PubMed

    Bury, N R; Codd, G A; Wendelaaar Bonga, S E; Flik, G

    1998-01-01

    Fatty acids from two strains of the cyanobacterium Microcystis aeruginosa, PCC 7820 (a strain that produces the hepatotoxin microcystin-LR, MC-LR) and CYA 43 (a strain that produces only small quantities of MC-LR), were extracted, partially characterised and tested for their inhibitory effect on the K+-dependent p-nitrophenol phosphatase (pNPPase) activity of tilapia (Oreochromis mossambicus) gill basolateral membrane. Thin-layer chromatography of the lipids from dichloromethane:methanol extracts of M. aeruginosa PCC 7820 and CYA 43, using diethylether:isopropanol:formic acid (100:4.5:2.5) as solvent, yielded five inhibitory products from M. aeruginosa 7820 and six from M. aeruginosa CYA 43. None of these products could be related to MC-LR. The inhibitory behaviour of the products mimics that of a slow, tight-binding inhibitor. The inhibitory activity is removed by incubation of extracts with fatty-acid-free bovine serum albumin (FAF-BSA). However, FAF-BSA only partially reversed the inhibition of K+-dependent pNPPase on fish gills pre-exposed to the extracted products. We conclude that M. aeruginosa strains PCC 7820 and CYA 43 produce fatty acids with potent inhibitory effects on K+-dependent pNPPase. The release of these products following lysis of cyanobacterial blooms may help to explain fish kills through a disturbance of gill functioning.

  14. Pharmacologically novel GABA receptor in human dorsal root ganglion neurons.

    PubMed

    Valeyev, A Y; Hackman, J C; Wood, P M; Davidoff, R A

    1996-11-01

    1. Whole cell voltage-clamp studies of gamma-aminobutyric acid (GABA) receptors were performed on large (> 80 microns) cultured human dorsal root ganglion (DRG) neurons. 2. GABA and pentobarbital sodium when applied in micromolar concentrations evoked inward Cl- currents in DRG neurons voltage clamped at negative membrane potentials. 3. Diazepam (10 microM) and pentobarbital (10 microM) upmodulated the GABA current by approximately 149 and 168%, respectively. 4. The GABA currents in human DRG cells were unaffected by the classical GABA antagonists picrotoxin and bicuclline (100 microM). In contrast, the GABA responses evoked in adult rat DRG cells cultured in an identical manner were inhibited by both antagonists. The glycine receptor antagonist strychnine (100 microM) did not alter GABA currents in human DRG cells. 5. Human DRG cells did not respond to glycine (10-100 microM) or taurine (10-100 microM). The GABAB agonist baclofen had no effect on the holding current when patch pipettes were filled with 130 mM KCl. The GABAB antagonists saclofen applied either alone or with GABA was without effect. 6. The differences between the GABA receptors described here and GABA receptors in other species may reflect the presence of receptor subunits unique to human DRG cells.

  15. Dysfunction in GABA signalling mediates autism-like stereotypies and Rett syndrome phenotypes.

    PubMed

    Chao, Hsiao-Tuan; Chen, Hongmei; Samaco, Rodney C; Xue, Mingshan; Chahrour, Maria; Yoo, Jong; Neul, Jeffrey L; Gong, Shiaoching; Lu, Hui-Chen; Heintz, Nathaniel; Ekker, Marc; Rubenstein, John L R; Noebels, Jeffrey L; Rosenmund, Christian; Zoghbi, Huda Y

    2010-11-11

    Mutations in the X-linked MECP2 gene, which encodes the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2), cause Rett syndrome and several neurodevelopmental disorders including cognitive disorders, autism, juvenile-onset schizophrenia and encephalopathy with early lethality. Rett syndrome is characterized by apparently normal early development followed by regression, motor abnormalities, seizures and features of autism, especially stereotyped behaviours. The mechanisms mediating these features are poorly understood. Here we show that mice lacking Mecp2 from GABA (γ-aminobutyric acid)-releasing neurons recapitulate numerous Rett syndrome and autistic features, including repetitive behaviours. Loss of MeCP2 from a subset of forebrain GABAergic neurons also recapitulates many features of Rett syndrome. MeCP2-deficient GABAergic neurons show reduced inhibitory quantal size, consistent with a presynaptic reduction in glutamic acid decarboxylase 1 (Gad1) and glutamic acid decarboxylase 2 (Gad2) levels, and GABA immunoreactivity. These data demonstrate that MeCP2 is critical for normal function of GABA-releasing neurons and that subtle dysfunction of GABAergic neurons contributes to numerous neuropsychiatric phenotypes.

  16. GABA{sub A} receptor open-state conformation determines non-competitive antagonist binding

    SciTech Connect

    Chen Ligong; Xue Ling; Giacomini, Kathleen M.; Casida, John E.

    2011-02-01

    The {gamma}-aminobutyric acid (GABA) type A receptor (GABA{sub A}R) is one of the most important targets for insecticide action. The human recombinant {beta}3 homomer is the best available model for this binding site and 4-n-[{sup 3}H]propyl-4'-ethynylbicycloorthobenzoate ([{sup 3}H]EBOB) is the preferred non-competitive antagonist (NCA) radioligand. The uniquely high sensitivity of the {beta}3 homomer relative to the much-less-active but structurally very-similar {beta}1 homomer provides an ideal comparison to elucidate structural and functional features important for NCA binding. The {beta}1 and {beta}3 subunits were compared using chimeragenesis and mutagenesis and various combinations with the {alpha}1 subunit and modulators. Chimera {beta}3/{beta}1 with the {beta}3 subunit extracellular domain and the {beta}1 subunit transmembrane helices retained the high [{sup 3}H]EBOB binding level of the {beta}3 homomer while chimera {beta}1/{beta}3 with the {beta}1 subunit extracellular domain and the {beta}3 subunit transmembrane helices had low binding activity similar to the {beta}1 homomer. GABA at 3 {mu}M stimulated heteromers {alpha}1{beta}1 and {alpha}1{beta}3 binding levels more than 2-fold by increasing the open probability of the channel. Addition of the {alpha}1 subunit rescued the inactive {beta}1/{beta}3 chimera close to wildtype {alpha}1{beta}1 activity. EBOB binding was significantly altered by mutations {beta}1S15'N and {beta}3N15'S compared with wildtype {beta}1 and {beta}3, respectively. However, the binding activity of {alpha}1{beta}1S15'N was insensitive to GABA and {alpha}1{beta}3N15'S was stimulated much less than wildtype {alpha}1{beta}3 by GABA. The inhibitory effect of etomidate on NCA binding was reduced more than 5-fold by the mutation {beta}3N15'S. Therefore, the NCA binding site is tightly regulated by the open-state conformation that largely determines GABA{sub A} receptor sensitivity. - Graphical Abstract: Display Omitted Research Highlights

  17. Cross-talk and co-trafficking between rho1/GABA receptors and ATP-gated channels.

    PubMed

    Boué-Grabot, Eric; Emerit, Michel B; Toulmé, Estelle; Séguéla, Philippe; Garret, Maurice

    2004-02-20

    Gamma-aminobutyric-acid (GABA) and ATP ionotropic receptors represent two structurally and functionally different classes of neurotransmitter-gated channels involved in fast synaptic transmission. We demonstrate here that, when the inhibitory rho1/GABA and the excitatory P2X2 receptor channels are co-expressed in Xenopus oocytes, activation of one channel reduces the currents mediated by the other one. This reciprocal inhibitory cross-talk is a receptor-mediated phenomenon independent of agonist cross-modulation, membrane potential, direction of ionic flux, or channel densities. Functional interaction is disrupted when the cytoplasmic C-terminal domain of P2X2 is deleted or in competition experiments with minigenes coding for the C-terminal domain of P2X2 or the main intracellular loop of rho1 subunits. We also show a physical interaction between P2X2 and rho1 receptors expressed in oocytes and the co-clustering of these receptors in transfected hippocampal neurons. Co-expression with P2X2 induces retargeting and recruitment of mainly intracellular rho1/GABA receptors to surface clusters. Therefore, molecular and functional cross-talk between inhibitory and excitatory ligand-gated channels may regulate synaptic strength both by activity-dependent current occlusion and synaptic receptors co-trafficking.

  18. The inhibitory effect of glycolic acid and lactic acid on melanin synthesis in melanoma cells.

    PubMed

    Usuki, Akiko; Ohashi, Akiko; Sato, Hirofumi; Ochiai, Yasunobu; Ichihashi, Masamitsu; Funasaka, Yoko

    2003-01-01

    Alpha-hydroxy acids (AHAs) such as glycolic acid (GA) and lactic acid (LA) have been reported to be effective in treating pigmentary lesions such as melasma, solar lentigines, and postinflammatory hyperpigmentation. The mechanism of this effect might be due to epidermal remodeling and accelerated desquamation, which would result in quick pigment dispersion. However, the direct effect of AHAs on melanin synthesis has not yet been well studied. To elucidate such a direct effect of AHAs on melanogenesis, we performed melanin assays, growth curve determinations, Northern and Western blotting for melanogenic proteins [tyrosinase, tyrosinase related protein (TRP)-1 and TRP-2], and tyrosinase and, 4-dihydroxyphenylalaninechrome tautomerase enzyme activity assays using mouse B16 and human melanoma cells. GA or LA (at doses of 300 or 500 microg/ml) inhibited melanin formation in similar dose-dependent manner, without affecting cell growth. Although the mRNA and protein expression or molecular size of tyrosinase, TRP-1 and TRP-2 were not affected, tyrosinase activity was inhibited. To see whether GA and/or LA directly inhibit tyrosinase catalytic function, the effect of GA and LA on human tyrosinase purified from the melanosome-rich large granule fraction of human melanoma cells was performed. GA or LA were shown to inhibit tyrosinase enzyme activity directly, but this effect was not due to the acidity of GA or LA, because adjusting the pH to 5.6 (the pH of GA and LA at concentrations of 2500 microg/ml), did not affect tyrosinase activity. Taken together, these results show that GA and LA suppress melanin formation by directly inhibiting tyrosinase activity, an effect independent of their acidic nature. GA and LA might work on pigmentary lesions not only by accelerating the turnover of the epidermis but also by directly inhibiting melanin formation in melanocytes.

  19. Developmental expression of glycine immunoreactivity and its colocalization with GABA in the embryonic chick lumbosacral spinal cord.

    PubMed

    Berki, A C; O'Donovan, M J; Antal, M

    1995-11-27

    The development of immunoreactivity for the putative inhibitory amino acid neurotransmitter glycine was investigated in the embryonic and posthatched chick lumbosacral spinal cord by using postembedding immunocytochemical methods. Glycine immunoreactive perikarya were first observed at embryonic day 8 (E8) both in the dorsal and ventral gray matters. The number of immunostained neurons sharply increased by E10 and was gradually augmented further at later developmental stages. The general pattern of glycine immunoreactivity characteristic of mature animals had been achieved by E12 and was only slightly altered afterward. Most of the immunostained neurons were located in the presumptive deep dorsal horn (laminae IV-VI) and lamina VII, although glycine-immunoreactive neurons were scattered throughout the entire extent of the spinal gray matter. By using some of our previously obtained and published data concerning the development of gamma-aminobutyric acid (GABA)-ergic neurons in the embryonic chick lumbosacral spinal cord, we have compared the numbers, sizes, and distribution of glycine- and GABA-immunoreactive spinal neurons at various developmental stages and found the following marked differences in the developmental characteristics of these two populations of putative inhibitory interneurons. (i) GABA immunoreactivity was expressed very early (E4), whereas immunoreactivity for glycine appeared relatively late (E8) in embryonic development. (ii) In the ventral horn, GABA immunoreactivity declined, whereas immunoreactivity for glycine gradually increased from E8 onward in such a manner that the sum of glycinergic and GABAergic perikarya remained constant during the second half of embryonic development. (iii) Glycinergic and GABAergic neurons showed different distribution patterns in the spinal gray matter throughout the entire course of embryogenesis as well as in the posthatched animal. When investigating the colocalization of glycine and GABA immunoreactivities

  20. GABA(B) and NMDA receptors contribute to spindle-like oscillations in rat thalamus in vitro.

    PubMed

    Jacobsen, R B; Ulrich, D; Huguenard, J R

    2001-09-01

    Thalamic slice preparations, in which intrathalamic connectivity between the reticular nucleus and relay nuclei is maintained, are capable of sustaining rhythmic burst firing activity in rodents and ferret. These in vitro oscillations occur spontaneously in the ferret and have frequencies (6-10 Hz) within the range of sleep spindles observed in vivo. In the rat, mainly lower frequency (2-4 Hz) oscillations, evoked under conditions of low bath [Mg(2+)] and/or GABA(A) receptor blockade, have been described. Here we show that faster rhythms in the range of 4-9 Hz can be evoked in rat thalamic slices by electrical stimulation of the internal capsule and also occur spontaneously. When bath [Mg(2+)] was 2 mM, these spindle-like oscillations were most common in a brief developmental time window, peaking at postnatal day 12 (P12). The oscillations were almost completely blocked by the GABA(A) receptor antagonist picrotoxin, and, in some cases, the frequency of oscillations was increased by the GABA(B) receptor antagonist CGP-35348. The selective blockade of N-methyl-D-aspartate (NMDA) or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors by the antagonists 2-amino-5-phosphonovaleric acid or 1,2,3,4-Tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide (NBQX), respectively, significantly shortened oscillations but did not completely block them. A combination of the two drugs was necessary to abolish oscillatory activity. The barbituate pentobarbital, which enhances GABA(A)R responses, initially slowed and synchronized oscillations before completely blocking them. When bath [Mg(2+)] was reduced from 2 to 0.65 mM, evoked oscillations became more robust and were often accompanied by spontaneously arising oscillations. Under these conditions, GABA(A) receptor blockade no longer inhibited oscillations, but instead converted them into the slow, synchronous rhythms that have been observed in other studies. The effects of GABA(B) or NMDA receptor

  1. GABA and GABA receptors alterations in the primary visual cortex of concave lens-induced myopic model.

    PubMed

    Zhao, Wen; Bi, Ai-Ling; Xu, Chao-Li; Ye, Xiang; Chen, Mei-Qing; Wang, Xin-Ting; Zhang, Xiao-Yan; Guo, Jun-Guo; Jiang, Wen-Jun; Zhang, Jin; Bi, Hong-Sheng

    2017-02-02

    Until recently most researches on myopia mechanisms have mainly been focused on the eye ball and few investigations were explored on the upper visual pathway, such as the visual cortex. The roles of gamma-aminobutyric acid (GABA) in the retinal and in the upper visual pathway are inter-correlated. As the retinal glutamate decarboxylase (GAD), GABA, and the mRNA levels of GABA receptors increased during the concave lens induced myopia formation, however, whether GABA alterations also occurred in the visual cortex during the concave lens induction is still unknown. In the present study, using HPLC, Enzyme-Linked Immunosorbent Assay (ELISA) and Real-Time Quantitative-PCR (RT-PCR) methods, we observed the changing trends of GABA, glutamate decarboxylase (GAD), and GABA receptors in the visual cortex of concave lens-induced myopic guinea pigs. Similar to the changing patterns of retinal GABA, the concentrations of GAD, GABA and the mRNA levels of GABA receptors in the visual cortex also increased. These results indicate that the exploration on myopia mechanisms should possibly be investigated on the whole visual pathway and the detailed significance of cortical GABA alterations needs further investigation.

  2. Treatment of Huntington disease with gamma-acetylenic GABA an irreversible inhibitor of GABA-transaminase: increased CSF GABA and homocarnosine without clinical amelioration.

    PubMed

    Tell, G; Böhlen, P; Schechter, P J; Koch-Weser, J; Agid, Y; Bonnet, A M; Coquillat, G; Chazot, G; Fischer, C

    1981-02-01

    gamma-Acetylenic GABA (GAG, RMI 71.645), a potent irreversible inhibitor of gamma-aminobutyric acid transaminase, was given orally in various dosage schedules to 14 patients with Huntington disease. The biochemical effects of the drug on cerebrospinal fluid (CSF) concentrations of gamma-aminobutyric acid (GABA) and the GABA-containing dipeptide, homocarnosine, were measured in 10 of 14 patients. Treatment with GAG increased CSF concentrations of GABA and homocarnosine as compared to pretreatment values, suggesting that the drug increased brain GABA concentration. Despite this neurochemical effect, the clinical state was not improved. Except for single seizure episodes in five patients, GAG therapy was well tolerated. These results do not exclude the possibility that agents that augment CNS GABAergic function may prove useful in therapy of Huntington disease.

  3. Isolation of lactic acid bacteria with inhibitory activity against pathogens and spoilage organisms associated with fresh meat.

    PubMed

    Jones, Rhys J; Hussein, Hassan M; Zagorec, Monique; Brightwell, Gale; Tagg, John R

    2008-04-01

    The use of lactic acid bacteria (LAB) as protective cultures in vacuum-packed chill-stored meat has potential application for assuring and improving food quality, safety and market access. In a study to identify candidate strains suitable for evaluation in a meat model, agar-based methods were employed to screen 181 chilled meat and meat process-related LAB for strains inhibitory to pathogens and spoilage organisms of importance to the meat industry. Six meat-derived strains, including Lactobacillus sakei and Lactococcus lactis, were found to be inhibitory to one or more of the target strains Listeria monocytogenes, Brochothrix thermosphacta, Campylobacter jejuni and Clostridium estertheticum. The inhibitory agents appeared to be either cell-associated or molecules released extracellularly with bacteriocin-like properties. Variations detected in the antimicrobial activity of LAB associated with changes to test parameters such as substrate composition underlined the importance of further in situ evaluation of the inhibitory strains in stored meat trials.

  4. Attenuation of malonate toxicity in primary mesencephalic cultures using the GABA transport blocker, NO-711.

    PubMed

    Stokes, A H; Bernard, L P; Nicklas, W J; Zeevalk, G D

    2001-04-01

    Cultured rat mesencephalic neurons were used to assess the effects of gamma-aminobutyric acid (GABA) transport blockers on toxicity caused by malonate, a reversible, competitive inhibitor of succinate dehydrogenase. Previous studies utilizing an ex vivo chick retinal preparation have shown that GABA release and cell swelling are early consequences of acute energy impairment and that GABA transport blockers attenuate this toxicity. The present results demonstrate that the nonsubstrate GABA transport blocker, NO-711 (1 nM-1 microM), dose-dependently protected cultured mesencephalic dopamine (DA) and GABA neurons from malonate-induced toxicity. Similar protection was demonstrated with nipecotic acid (1 mM) and SKF89976A (100 nM), substrate and nonsubstrate GABA transport blockers, respectively. These compounds by themselves produced no signs of toxicity, although nipecotic acid caused a long-term decrease in GABA uptake not associated with toxicity. Compounds which decrease intracellular reactive oxygen species (ROS) are protective in this model, but NO-711 did not prevent the rise in intracellular ROS induced by malonate, indicating its protective effects were downstream of ROS production. Supplementation of malonate treated cultures with the GABA(A) agonist, muscimol (10 microM), increased the toxicity toward the DA and GABA neuron populations. Antagonists at the GABA(A) and glycine receptors provided partial protection to both the GABA and DA neurons. These findings suggest that the GABA transporter, GABA(A), and/or glycine channels contribute to cell damage associated with energy impairment in this model.

  5. The dynamics of GABA signaling: Revelations from the circadian pacemaker in the suprachiasmatic nucleus.

    PubMed

    Albers, H Elliott; Walton, James C; Gamble, Karen L; McNeill, John K; Hummer, Daniel L

    2017-01-01

    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.

  6. Altered γ-aminobutyric acid neurotransmission in major depressive disorder: a critical review of the supporting evidence and the influence of serotonergic antidepressants.

    PubMed

    Pehrson, Alan L; Sanchez, Connie

    2015-01-01

    Evidence suggesting that central nervous system γ-aminobutyric acid (GABA) concentrations are reduced in patients with major depressive disorder (MDD) has been present since at least 1980, and this idea has recently gained support from more recent magnetic resonance spectroscopy data. These observations have led to the assumption that MDD's underlying etiology is tied to an overall reduction in GABA-mediated inhibitory neurotransmission. In this paper, we review the mechanisms that govern GABA and glutamate concentrations in the brain, and provide a comprehensive and critical evaluation of the clinical data supporting reduced GABA neurotransmission in MDD. This review includes an evaluation of magnetic resonance spectroscopy data, as well as data on the expression and function of the GABA-synthesizing enzyme glutamic acid decarboxylase, GABA neuron-specific cell markers, such as parvalbumin, calretinin and calbindin, and the GABAA and GABAB receptors in clinical MDD populations. We explore a potential role for glial pathology in MDD-related reductions in GABA concentrations, and evidence of a connection between neurosteroids, GABA neurotransmission, and hormone-related mood disorders. Additionally, we investigate the effects of GABAergic pharmacological agents on mood, and demonstrate that these compounds have complex effects that do not universally support the idea that reduced GABA neurotransmission is at the root of MDD. Finally, we discuss the connections between serotonergic and GABAergic neurotransmission, and show that two serotonin-focused antidepressants - the selective serotonin-reuptake inhibitor fluoxetine and the multimodal antidepressant vortioxetine - modulate GABA neurotransmission in opposing ways, despite both being effective MDD treatments. Altogether, this review demonstrates that there are large gaps in our understanding of the relationship between GABA physiology and MDD, which must be remedied with more data from well-controlled empirical

  7. Activation of GABA-A Receptor Ameliorates Homocysteine-Induced MMP-9 Activation by ERK Pathway

    PubMed Central

    TYAGI, NEETU; GILLESPIE, WILLIAM; VACEK, JONATHAN C.; SEN, UTPAL; TYAGI, SURESH C.; LOMINADZE, DAVID

    2010-01-01

    Hyperhomocysteinemia (HHcy) is a risk factor for neuroinflammatory and neurodegenerative diseases. Homocysteine (Hcy) induces redox stress, in part, by activating matrix metalloproteinase-9 (MMP-9), which degrades the matrix and leads to blood–brain barrier dysfunction. Hcy competitively binds to γ-aminbutyric acid (GABA) receptors, which are excitatory neurotransmitter receptors. However, the role of GABA-A receptor in Hcy-induced cerebrovascular remodeling is not clear. We hypothesized that Hcy causes cerebrovascular remodeling by increasing redox stress and MMP-9 activity via the extracellular signal-regulated kinase (ERK) signaling pathway and by inhibition of GABA-A receptors, thus behaving as an inhibitory neurotransmitter. Hcy-induced reactive oxygen species production was detected using the fluorescent probe, 2′–7′-dichlorodihydrofluorescein diacetate. Hcy increased nicotinamide adenine dinucleotide phosphate-oxidase-4 concomitantly suppressing thioredoxin. Hcy caused activation of MMP-9, measured by gelatin zymography. The GABA-A receptor agonist, muscimol ameliorated the Hcy-mediated MMP-9 activation. In parallel, Hcy caused phosphorylation of ERK and selectively decreased levels of tissue inhibitors of metalloproteinase-4 (TIMP-4). Treatment of the endothelial cell with muscimol restored the levels of TIMP-4 to the levels in control group. Hcy induced expression of iNOS and decreased eNOS expression, which lead to a decreased NO bioavailability. Furthermore muscimol attenuated Hcy-induced MMP-9 via ERK signaling pathway. These results suggest that Hcy competes with GABA-A receptors, inducing the oxidative stress transduction pathway and leading to ERK activation. PMID:19308943

  8. GABA A/Bz receptor subtypes as targets for selective drugs.

    PubMed

    Da Settimo, F; Taliani, S; Trincavelli, M L; Montali, M; Martini, C

    2007-01-01

    The gamma-aminobutyric acid type A (GABA(A)) receptors are the major inhibitory neuronal receptors in the mammalian brain. Their activation by GABA opens the intrinsic ion channel, enabling chloride flux into the cell with subsequent hyperpolarization. Several GABA(A) receptor subunit isoforms have been cloned, the major isoform containing alpha, beta, and gamma subunits, and a regional heterogeneity associated with distinct physiological effects has been suggested. As a variety of allosteric ligands can modulate GABA-gated conductance changes through binding to distinct sites, the development of subtype-selective ligands may lead to the selective treatment of GABA system-associated pathology. In particular, the best characterized binding site is the benzodiazepine site (BzR), localized at the alpha/gamma subunit interface, in which the alpha subunit is the main determinant of BzR ligand action selectivity. The alpha1-containing BzR have been proposed to be responsible for the sedative action; the alpha2 and/or the alpha3 subtypes have been suggested to mediate the anxiolytic activity and the myorelaxation effects, and the alpha5 subtype has been associated with cognition processes. The discovery of alpha-selective subtype ligands may help in the specific treatment of anxiety, sleep disorders, convulsions and memory deficits with fewer side effects. Selectivity may be achieved by two approaches: selective affinity or selective efficacy. Selective affinity needs a compound to bind with a higher affinity to one receptor subtype compared with another, whereas subtype-selective efficacy relies on a compound binding to all subtypes, but having different efficacies at various subtypes. The status of BzR ligands, subdivided on the basis of their main chemical structural features, is reviewed in relation to structure-activity relationships which determine their affinity or efficacy selectivity for a certain BzR subtype.

  9. 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.

  10. An Evolutionarily Conserved Switch in Response to GABA Affects Development and Behavior of the Locomotor Circuit of Caenorhabditis elegans

    PubMed Central

    Han, Bingjie; Bellemer, Andrew; Koelle, Michael R.

    2015-01-01

    The neurotransmitter gamma-aminobutyric acid (GABA) is depolarizing in the developing vertebrate brain, but in older animals switches to hyperpolarizing and becomes the major inhibitory neurotransmitter in adults. We discovered a similar developmental switch in GABA response in Caenorhabditis elegans and have genetically analyzed its mechanism and function in a well-defined circuit. Worm GABA neurons innervate body wall muscles to control locomotion. Activation of GABAA receptors with their agonist muscimol in newly hatched first larval (L1) stage animals excites muscle contraction and thus is depolarizing. At the mid-L1 stage, as the GABAergic neurons rewire onto their mature muscle targets, muscimol shifts to relaxing muscles and thus has switched to hyperpolarizing. This muscimol response switch depends on chloride transporters in the muscles analogous to those that control GABA response in mammalian neurons: the chloride accumulator sodium-potassium-chloride-cotransporter-1 (NKCC-1) is required for the early depolarizing muscimol response, while the two chloride extruders potassium-chloride-cotransporter-2 (KCC-2) and anion-bicarbonate-transporter-1 (ABTS-1) are required for the later hyperpolarizing response. Using mutations that disrupt GABA signaling, we found that neural circuit development still proceeds to completion but with an ∼6-hr delay. Using optogenetic activation of GABAergic neurons, we found that endogenous GABAA signaling in early L1 animals, although presumably depolarizing, does not cause an excitatory response. Thus a developmental depolarizing-to-hyperpolarizing shift is an ancient conserved feature of GABA signaling, but existing theories for why this shift occurs appear inadequate to explain its function upon rigorous genetic analysis of a well-defined neural circuit. PMID:25644702

  11. Cloning and expression of a rat brain GABA transporter

    SciTech Connect

    Guastella, J.; Czyzyk, L.; Davidson, N.; Lester, H.A. ); Nelson, N.; Nelson, H.; Miedel, M.C. ); Keynan, S.; Kanner, B.I. )

    1990-09-14

    A complementary DNA clone (designated GAT-1) encoding a transporter for the neurotransmitter {gamma}-aminobutyric acid (GABA) has been isolated from rat brain, and its functional properties have been examined in Xenopus oocytes. Oocytes injected with GAT-1 synthetic messenger RNA accumulated ({sup 3}H)GABA to levels above control values. The transporter encoded by GAT-1 has a high affinity for GABA, is sodium- and chloride-dependent, and is pharmacologically similar to neuronal GABA transporters. The GAT-1 protein shares antigenic determinants with a native rat brain GABA transporter. The nucleotide sequence of GAT-1 predicts a protein of 599 amino acids with a molecular weight of 67 kilodaltons. Hydropathy analysis of the deduced protein suggests multiple transmembrane regions, a feature shared by several cloned transporters; however, database searches indicate that GAT-1 is not homologous to any previously identified proteins. Therefore, GAT-1 appears to be a member of a previously uncharacterized family of transport molecules.

  12. Frontal GABA levels change during working memory.

    PubMed

    Michels, Lars; Martin, Ernst; Klaver, Peter; Edden, Richard; Zelaya, Fernando; Lythgoe, David J; Lüchinger, Rafael; Brandeis, Daniel; O'Gorman, Ruth L

    2012-01-01

    Functional neuroimaging metrics are thought to reflect changes in neurotransmitter flux, but changes in neurotransmitter levels have not been demonstrated in humans during a cognitive task, and the relationship between neurotransmitter dynamics and hemodynamic activity during cognition has not yet been established. We evaluate the concentration of the major inhibitory (GABA) and excitatory (glutamate + glutamine: Glx) neurotransmitters and the cerebral perfusion at rest and during a prolonged delayed match-to-sample working memory task. Resting GABA levels in the dorsolateral prefrontal cortex correlated positively with the resting perfusion and inversely with the change in perfusion during the task. Further, only GABA increased significantly during the first working memory run and then decreased continuously across subsequent task runs. The decrease of GABA over time was paralleled by a trend towards decreased reaction times and higher task accuracy. These results demonstrate a link between neurotransmitter dynamics and hemodynamic activity during working memory, indicating that functional neuroimaging metrics depend on the balance of excitation and inhibition required for cognitive processing.

  13. Biphasic effects of baclofen on phrenic motoneurons: possible involvement of two types of gamma-aminobutyric acid (GABA) receptors.

    PubMed

    Lalley, P M

    1983-08-01

    Intravenous injections of baclofen have two general dose-dependent effects on phrenic motoneurons in anesthetized cats. Small doses (0.5-1.5 mg/kg) increase the frequency of action potentials recorded from single motoneurons and from the phrenic nerve, whereas large doses (2-10 mg/kg) reduce or abolish action potentials. The increase in frequency produced by small doses is accompanied by membrane depolarization and, in most experiments, by increased input resistance. Large doses hyperpolarize phrenic motoneurons and produce greater increases in input resistance. Extracellular recording during microelectrophoretic application of baclofen reveals only one effect, depression of cell firing, at all effective current strengths. The low dose stimulatory effect of i.v. baclofen is attributed to disinhibition, whereas the depression by large doses is attributed to disfacilitation. During incomplete inhibition by baclofen, CO2 administration further depresses phrenic nerve activity. Bicuculline (100-600 micrograms/kg i.v.) and picrotoxin (900 micrograms/kg i.v.) restore firing depressed by baclofen, whereas strychnine (80-1280 micrograms/kg) does not. 3-Aminopropanesulfonic acid (5-75 mg/kg i.v.) an agonist at gamma-aminobutyric acid-A receptor sites, depresses phrenic nerve activity. It is suggested that the low dose stimulatory effects are related to actions at gamma-aminobutyric acid-B receptors, whereas the high dose depressant effects are related, at least in part, to activation of gamma-aminobutyric acid-A receptors.

  14. Evaluation of the tannic acid inhibitory effect against the NorA efflux pump of Staphylococcus aureus.

    PubMed

    Tintino, Saulo R; Oliveira-Tintino, Cícera D M; Campina, Fábia F; Silva, Raimundo L P; Costa, Maria do S; Menezes, Irwin R A; Calixto-Júnior, João T; Siqueira-Junior, José P; Coutinho, Henrique D M; Leal-Balbino, Tereza C; Balbino, Valdir Q

    2016-08-01

    During the early periods of antibiotic usage, bacterial infections were considered tamed. However, widespread antibiotic use has promoted the emergence of antibiotic-resistant pathogens, including multidrug resistant strains. Active efflux is a mechanism for bacterial resistance to inhibitory substances, known simply as drug efflux pumps. The bacterium Staphylococcus aureus is an important pathogenic bacterium responsible for an array of infections. The NorA efflux pump has been shown to be responsible for moderate fluoroquinolone resistance of S. aureus. The inhibition of the efflux pump was assayed using a sub-inhibitory concentration of standard efflux pump inhibitors and tannic acid (MIC/8), where its capacity to decrease the MIC of Ethidium bromide (EtBr) and antibiotics due to the possible inhibitory effect of these substances was observed. The MICs of EtBr and antibiotics were significantly reduced in the presence of tannic acid, indicating the inhibitory effect of this agent against the efflux pumps of both strains causing a three-fold reduction of the MIC when compared with the control. These results indicate the possible usage of tannic acid as an adjuvant in antibiotic therapy against multidrug resistant bacteria (MDR).

  15. Inhibitory effect of boric acid on intergranular attack and stress corrosion cracking of Alloy 600 in high temperature water

    SciTech Connect

    Kawamura, H.; Hirano, H.; Koike, M.; Suda, M.

    1995-09-01

    The inhibitory effect of boric acid on the Intergranular Attack and Stress Corrosion Cracking (IGA/SCC) propagation behavior of steam generator (SG) tubing was studied under accelerated test conditions. Based on the analysis results of stress intensity factors at IGA/SCC crack tips, the notched C-ring tests were carried out to evaluate the effect of stress intensity and boric acid on the IGA/SCC crack propagation. The A.C. impedance measurement and Auger electron spectroscopy (AES) were also conducted to clarify the inhibitory effect of boric acid. Notched C-ring test results indicated that IGA/SCC crack velocity of alloy 600 increased gradually with increasing stress intensity factor in the range 4 to about 26 MPa{center_dot}m{sup 1/2}, which might be loaded on the IGA/SCC crack tips of actual SG tubes under PWR secondary conditions. Adding boric acid slightly retarded the crack velocity in both all volatile treatment (AVT) water and caustic solutions. IGA/SCC crack velocities were lower in nearly neutral solutions than in alkali or acidic solutions. Furthermore, A.C. impedance studies showed that the polarization resistances of oxide films formed in boric acid solutions were higher than those of films formed in acidic and alkali solutions. AES analysis revealed that boron content in the oxide films formed in acidic solution containing boric acid was lowest. Good agreement was obtained between the IGA/SCC inhibitory effect of boric acid and the formation of the stable oxide films containing boron.

  16. Glycolic acid chemical peeling improves inflammatory acne eruptions through its inhibitory and bactericidal effects on Propionibacterium acnes.

    PubMed

    Takenaka, Yuko; Hayashi, Nobukazu; Takeda, Mikiko; Ashikaga, Sayaka; Kawashima, Makoto

    2012-04-01

    Glycolic acid chemical peeling is effective for treating comedones, and some clinical data show that it also improves inflammatory eruptions. The purpose of this study was to identify the mechanism of glycolic acid chemical peeling to improve inflammatory acne. To assess growth inhibitory and bactericidal effects of glycolic acid on Propionibacterium acnes in vitro, we used an agar diffusion method and a time-kill method. To reveal bactericidal effects in vivo, we established an agar-attached method which correlated well with the ordinary swab-wash method, and we used the agar-attached method to compare the numbers of propionibacteria on the cheek treated with glycolic acid chemical peeling. Our results show that 30% glycolic acid (at pH 1.5, 3.5 and 5.5) formed growth inhibitory circles in the agar diffusion method, but the diameters of those circles were smaller than with 1% nadifloxacin lotion or 1% clindamycin gel. In the time-kill method, 30% glycolic acid (at pH 1.5 and 3.5) or 1% nadifloxacin lotion reduced the number of P. acnes to less than 100 CFU/mL within 5 min. In contrast, in 30% glycolic acid (at pH 5.5) or in 1% clindamycin gel, P. acnes survived for more than 4 h. Chemical peeling with 35% glycolic acid (at pH 1.2) decreased the number of propionibacteria on the cheeks of patients compared with untreated controls (P < 0.01). Our results demonstrate that glycolic acid has moderate growth inhibitory and bactericidal effects on P. acnes, and that chemical peeling with glycolic acid works on inflammatory acne via those effects.

  17. Modelling inhibitory effects of long chain fatty acids in the anaerobic digestion process.

    PubMed

    Zonta, Z; Alves, M M; Flotats, X; Palatsi, J

    2013-03-01

    Mathematical modelling of anaerobic digestion process has been used to give new insights regarding dynamics of the long chain fatty acids (LCFA) inhibition. Previously published experimental data, including batch tests with clay mineral bentonite additions, were used for parameter identification. New kinetics were considered to describe the bio-physics of the inhibitory process, including: i) adsorption of LCFA over granular biomass and ii) specific LCFA substrate (saturated/unsaturated) and LCFA-degrading populations. Furthermore, iii) a new variable was introduced to describe the state of damage of the acetoclastic methanogens in order to account for the loss of cell-functionality (inhibition) induced by the adsorbed LCFAs. The proposed model modifications are state compatible and easy to be integrated into the International Water Association's Anaerobic Digestion Model N°1 (ADM1) framework. Practical identifiability of model parameters was assessed with a global sensitivity analysis, while calibration and model structure validation were performed on independent data sets. A reliable simulation of the LCFA-inhibition process can be achieved, if the model includes the description of the adsorptive nature of the LCFAs and the LCFA-damage over specific biomass. The importance of microbial population structure (saturated/unsaturated LCFA-degraders) and the high sensitivity of acetoclastic population to LCFA are evidenced, providing a plausible explanation of experimental based hypothesis.

  18. Inhibitory Effects of Glycyrrhetinic Acid on DNA Polymerase and Inflammatory Activities

    PubMed Central

    Ishida, Tsukasa; Mizushina, Yoshiyuki; Yagi, Saori; Irino, Yasuhiro; Nishiumi, Shin; Miki, Ikuya; Kondo, Yasuyuki; Mizuno, Shigeto; Yoshida, Hiromi; Azuma, Takeshi; Yoshida, Masaru

    2012-01-01

    We investigated the inhibitory effect of three glycyrrhizin derivatives, such as Glycyrrhizin (compound 1), dipotassium glycyrrhizate (compound 2) and glycyrrhetinic acid (compound 3), on the activity of mammalian pols. Among these derivatives, compound 3 was the strongest inhibitor of mammalian pols α, β, κ, and λ, which belong to the B, A, Y, and X families of pols, respectively, whereas compounds 1 and 2 showed moderate inhibition. Among the these derivatives tested, compound 3 displayed strongest suppression of the production of tumor necrosis factor-α (TNF-α) induced by lipopolysaccharide (LPS) in a cell-culture system using mouse macrophages RAW264.7 and peritoneal macrophages derived from mice. Moreover, compound 3 was found to inhibit the action of nuclear factor-κB (NF-κB) in engineered human embryonic kidney (HEK) 293 cells. In addition, compound 3 caused greater reduction of 12-O-tetradecanoylphorbol-13-acetate-(TPA-) induced acute inflammation in mouse ear than compounds 1 and 2. In conclusion, this study has identified compound 3, which is the aglycone of compounds 1 and 2, as a promising anti-inflammatory candidate based on mammalian pol inhibition. PMID:21785649

  19. Blocking Early GABA Depolarization with Bumetanide Results in Permanent Alterations in Cortical Circuits and Sensorimotor Gating Deficits

    PubMed Central

    Kriegstein, Arnold R.

    2011-01-01

    A high incidence of seizures occurs during the neonatal period when immature networks are hyperexcitable and susceptible to hypersyncrhonous activity. During development, γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in adults, typically excites neurons due to high expression of the Na+-K+-2Cl− cotransporter (NKCC1). NKCC1 facilitates seizures because it renders GABA activity excitatory through intracellular Cl− accumulation, while blocking NKCC1 with bumetanide suppresses seizures. Bumetanide is currently being tested in clinical trials for treatment of neonatal seizures. By blocking NKCC1 with bumetanide during cortical development, we found a critical period for the development of α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate synapses. Disruption of GABA signaling during this window resulted in permanent decreases in excitatory synaptic transmission and sensorimotor gating deficits, a common feature in schizophrenia. Our study identifies an essential role for GABA-mediated depolarization in regulating the balance between cortical excitation and inhibition during a critical period and suggests a cautionary approach for using bumetanide in treating neonatal seizures. PMID:20624842

  20. Cloning of the mouse GABA-benzodiazepine receptor. alpha. 1 subunit in a study of alcohol neurosensitivity

    SciTech Connect

    Keir, W.J.; Deitrich, R.A.; Sikela, J.M. )

    1989-02-09

    The inhibitory action of gamma amino butyric acid (GABA) is mediated by its binding to the benzodiazepine (BDZ) receptor and opening of a chloride channel. This receptor contains a variety of binding sites for several behavorially active drugs. Recent studies with SS and LS mice which were selected for differential neurosensitivity to ethanol, suggest that the GABAergic system plays a role in this differential sensitivity. Thus genes controlling the GABAergic system may also influence the acute hypnotic actions of ethanol. As a fist step towards verifying this hypothesis we have cloned and partially sequenced the mouse GABA-BDZ {alpha}1 subunit cDNA using a 40 bp oligonucleotide derived from the N terminus of a published bovine {alpha} subunit cDNA. A positive clone from a mouse brain cDNA library was identified and contains an insert of approximately 2.5 Kb. Partial sequence analysis indicates that this clone corresponds to the mouse homolog of the {alpha}1 subunit of the GABA-BDZ receptor. This clone is being used as a probe to identify restriction fragment length polymorphisms in several mouse genotypes which differ in their neurosensitivity to ethanol in an attempt to identify molecular genetic changes in the GABA-BDZ receptor that are related to differential ethanol neurosensitivity.

  1. Dual role of GABA in the neonatal rat hippocampus.

    PubMed

    Khalilov, I; Dzhala, V; Ben-Ari, Y; Khazipov, R

    1999-11-01

    The effects of modulators of GABA-A receptors on neuronal network activity were studied in the neonatal (postnatal days 0-5) rat hippocampus in vitro. Under control conditions, the physiological pattern of activity of the neonatal hippocampal network was characterized by spontaneous network-driven giant depolarizing potentials (GDPs). The GABA-A receptor agonist isoguvacine (1-2 microM) and the allosteric modulator diazepam (2 microM) induced biphasic responses: initially the frequency of GDPs increased 3 to 4 fold followed by blockade of GDPs and desynchronization of the network activity. The GABA-A receptor antagonists bicuculline (10 microM) and picrotoxin (100 microM) blocked GDPs and induced glutamate (AMPA and NMDA)-receptor-mediated interictal- and ictal-like activities in the hippocampal slices and the intact hippocampus. These data suggest that at early postnatal ages GABA can exert a dual - both excitatory and inhibitory - action on the network activity.

  2. Benzodiazepine-dependent stabilization of GABA(A) receptors at synapses.

    PubMed

    Gouzer, Géraldine; Specht, Christian G; Allain, Laure; Shinoe, Toru; Triller, Antoine

    2014-11-01

    GABA(A) receptors constitutively enter and exit synapses by lateral diffusion in the plane of the neuronal membrane. They are trapped at synapses through their interactions with gephyrin, the main scaffolding protein at inhibitory post-synaptic densities. Previous work has shown that the synaptic accumulation and diffusion dynamics of GABA(A)Rs are controlled via excitatory synaptic activity. However, it remains unknown whether GABA(A)R activity can itself impact the surface trafficking of the receptors. Here we report the effects of GABA(A)R agonists, antagonists and allosteric modulators on the receptor's surface dynamics. Using immunocytochemistry and single particle tracking experiments on mouse hippocampal neurons, we show that the agonist muscimol decreases GABA(A)R and gephyrin levels at synapses and accelerates the receptor's lateral diffusion within 30–120 min of treatment. In contrast, the GABA(A)R antagonist gabazine increased GABA(A)R amounts and slowed down GABA(A)R diffusion at synapses. The response to GABA(A)R activation or inhibition appears to be an adaptative regulation of GABAergic synapses. Surprisingly, the positive allosteric modulator diazepam abolished the regulation induced by muscimol, and this effect was observed on α1, α2, α5 and γ2 GABA(A)R subunits. Altogether these results indicate that diazepam stabilizes synaptic GABA(A)Rs and thus prevents the agonist-induced regulation of GABA(A)R levels at synapses. This occurred independently of neuronal activity and intracellular calcium and involved GABA(A)R–gephyrin interactions, suggesting that the changes in GABA(A)R diffusion depend on conformational changes of the receptor. Our study provides a new molecular mechanism involved in the adaptative response to changes in GABA(A)R activity and benzodiazepine treatments.

  3. Catabolism of GABA, succinic semialdehyde or gamma-hydroxybutyrate through the GABA shunt impair mitochondrial substrate-level phosphorylation.

    PubMed

    Ravasz, Dora; Kacso, Gergely; Fodor, Viktoria; Horvath, Kata; Adam-Vizi, Vera; Chinopoulos, Christos

    2017-03-11

    GABA is catabolized in the mitochondrial matrix through the GABA shunt, encompassing transamination to succinic semialdehyde followed by oxidation to succinate by the concerted actions of GABA transaminase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH), respectively. Gamma-hydroxybutyrate (GHB) is a neurotransmitter and a psychoactive drug that could enter the citric acid cycle through transhydrogenation with α-ketoglutarate to succinic semialdehyde and d-hydroxyglutarate, a reaction catalyzed by hydroxyacid-oxoacid transhydrogenase (HOT). Here, we tested the hypothesis that the elevation in matrix succinate concentration caused by exogenous addition of GABA, succinic semialdehyde or GHB shifts the equilibrium of the reversible reaction catalyzed by succinate-CoA ligase towards ATP (or GTP) hydrolysis, effectively negating substrate-level phosphorylation (SLP). Mitochondrial SLP was addressed by interrogating the directionality of the adenine nucleotide translocase during anoxia in isolated mouse brain and liver mitochondria. GABA eliminated SLP, and this was rescued by the GABA-T inhibitors vigabatrin and aminooxyacetic acid. Succinic semialdehyde was an extremely efficient substrate energizing mitochondria during normoxia but mimicked GABA in abolishing SLP in anoxia, in a manner refractory to vigabatrin and aminooxyacetic acid. GHB could moderately energize liver but not brain mitochondria consistent with the scarcity of HOT expression in the latter. In line with these results, GHB abolished SLP in liver but not brain mitochondria during anoxia and this was unaffected by either vigabatrin or aminooxyacetic acid. It is concluded that when mitochondria catabolize GABA or succinic semialdehyde or GHB through the GABA shunt, their ability to perform SLP is impaired.

  4. Investigating GABA and its function in platelets as compared to neurons.

    PubMed

    Kaneez, Fatima Shad; Saeed, Sheikh Arshad

    2009-08-01

    We have recently suggested that platelets could be used as a model for neuronal receptors. In this paper we have investigated gamma-aminobutyric acid (GABA) metabolism and GABA receptors in platelets and in cultured neurons to see whether platelets' GABA mimics neuronal GABA receptor activities. We used the ELISA technique for detecting the GABA concentration in platelet rich plasma and cultured neurons. The functional effects of GABA and its receptor ligands on platelets were determined using an aggregometer. We found that the GABA concentration is 30% lower in platelets than in neurons and in both preparations GABA was metabolized by GABA transaminase (GABA-T). GABA potentiated calcium dependent platelet aggregation with a higher value in washed platelets suspension (WPS) then in platelet rich plasma (PRP). This effect was inhibited by benzodiazepines, calcium channel blockers and the selective phosphoinositide 3-kinase antagonist Wortmannin. GABA neurotransmission is involved in most aspects of normal brain function and can be perturbed in many neuropathologic conditions. We concluded that platelets could be further developed to be used as a peripheral model to study neuronal GABAergic function and its abnormality in diseases such as epilepsy and schizophrenia. Furthermore our results indicated that PI3-kinase is involved in calcium dependent GABA induced platelet aggregation as this synergistic effect is inhibited by Wortmannin in dose dependent manner.

  5. Agonist pharmacology of two Drosophila GABA receptor splice variants.

    PubMed Central

    Hosie, A. M.; Sattelle, D. B.

    1996-01-01

    1. The Drosophila melanogaster gamma-aminobutyric acid (GABA) receptor subunits, RDLac and DRC 17-1-2, form functional homo-oligomeric receptors when heterologously expressed in Xenopus laevis oocytes. The subunits differ in only 17 amino acids, principally in regions of the N-terminal domain which determine agonist pharmacology in vertebrate ionotropic neurotransmitter receptors. A range of conformationally restricted GABA analogues were tested on the two homo-oligomers and their agonists pharmacology compared with that of insect and vertebrate iontropic GABA receptors. 2. The actions of GABA, isoguvacine and isonipecotic acid on RDLac and DRC 17-1-2 homo-oligomers were compared, by use of two-electrode voltage-clamp. All three compounds were full agonists of both receptors, but were 4-6 fold less potent agonists of DRC 17-1-2 homo-oligomers than of RDLac. However, the relative potencies of these agonists on each receptor were very similar. 3. A more complete agonist profile was established for RDLac homo-oligomers. The most potent agonists of these receptors were GABA, muscimol and trans-aminocrotonic acid (TACA), which were approximately equipotent. RDLac homo-oligomers were fully activated by a range of GABA analogues, with the order of potency: GABA > ZAPA ((Z)-3-[(aminoiminomethyl)thio]prop-2-enoic acid) > isoguvacine > imidazole-4-acetic acid > or = isonipecotic acid > or = cis-aminocrotonic acid (CACA) > beta-alanine. 3-Aminopropane sulphonic acid (3-APS), a partial agonist of RDLac homo-oligomers, was the weakest agonist tested and 100 fold less potent than GABA. 4. SR95531, an antagonist of vertebrate GABAA receptors, competitively inhibited the GABA responses of RDLac homo-oligomers, which have previously been found to insensitive to bicuculline. However, its potency (IC50 500 microM) was much reduced when compared to GABAA receptors. 5. The agonist pharmacology of Drosophila RDLac homo-oligomers exhibits aspects of the characteristic pharmacology of

  6. Excitatory GABA: How a Correct Observation May Turn Out to be an Experimental Artifact

    PubMed Central

    Bregestovski, Piotr; Bernard, Christophe

    2012-01-01

    The concept of the excitatory action of GABA during early development is based on data obtained mainly in brain slice recordings. However, in vivo measurements as well as observations made in intact hippocampal preparations indicate that GABA is in fact inhibitory in rodents at early neonatal stages. The apparent excitatory action of GABA seems to stem from cellular injury due to the slicing procedure, which leads to accumulation of intracellular Cl− in injured neurons. This procedural artifact was shown to be attenuated through various manipulations such as addition of energy substrates more relevant to the in vivo situation. These observations question the very concept of excitatory GABA in immature neuronal networks. PMID:22529813

  7. Optimization of γ-amino butyric acid production in a newly isolated Lactobacillus brevis.

    PubMed

    Binh, Tran Thi Thanh; Ju, Wan-Taek; Jung, Woo-Jin; Park, Ro-Dong

    2014-01-01

    An isolate from kimchi, identified as Lactobacillus brevis, accumulated γ-aminobutyric acid (GABA), a major inhibitory neurotransmitter, in the culture medium. Optimal culture conditions for growth of L. brevis and production of GABA were 6 % (w/v) l-glutamic acid, 4 % (w/v) maltose, 2 % (w/v) yeast extract, 1 % (w/v) NaCl, 1 % (w/v) CaCl2, 2 g Tween 80/l, and 0.02 mM pyridoxal 5′-phosphate at initial pH 5.25 and 37 °C. GABA reached 44.4 g/l after 72 h cultivation with a conversion rate 99.7 %, based on the amount (6 %) of l-glutamic acid added. GABA was purified using ion exchange column chromatography with 70 % recovery and 97 % purity.

  8. Glutamate and GABA in Appetite Regulation

    PubMed Central

    Delgado, Teresa C.

    2013-01-01

    Appetite is regulated by a coordinated interplay between gut, adipose tissue, and brain. A primary site for the regulation of appetite is the hypothalamus where interaction between orexigenic neurons, expressing Neuropeptide Y/Agouti-related protein, and anorexigenic neurons, expressing Pro-opiomelanocortin cocaine/Amphetamine-related transcript, controls energy homeostasis. Within the hypothalamus, several peripheral signals have been shown to modulate the activity of these neurons, including the orexigenic peptide ghrelin and the anorexigenic hormones insulin and leptin. In addition to the accumulated knowledge on neuropeptide signaling, presence and function of amino acid neurotransmitters in key hypothalamic neurons brought a new light into appetite regulation. Therefore, the principal aim of this review will be to describe the current knowledge of the role of amino acid neurotransmitters in the mechanism of neuronal activation during appetite regulation and the associated neuronal-astrocytic metabolic coupling mechanisms. Glutamate and GABA dominate synaptic transmission in the hypothalamus and administration of their receptors agonists into hypothalamic nuclei stimulates feeding. By using 13C High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance spectroscopy based analysis, the Cerdán group has shown that increased neuronal firing in mice hypothalamus, as triggered by appetite during the feeding-fasting paradigm, may stimulate the use of lactate as neuronal fuel leading to increased astrocytic glucose consumption and glycolysis. Moreover, fasted mice showed increased hypothalamic [2-13C]GABA content, which may be explained by the existence of GABAergic neurons in key appetite regulation hypothalamic nuclei. Interestingly, increased [2-13C]GABA concentration in the hypothalamus of fasted animals appears to result mainly from reduction in GABA metabolizing pathways, rather than increased GABA synthesis by augmented activity of the glutamate-glutamine-GABA

  9. Glutamate and GABA in Appetite Regulation.

    PubMed

    Delgado, Teresa C

    2013-01-01

    Appetite is regulated by a coordinated interplay between gut, adipose tissue, and brain. A primary site for the regulation of appetite is the hypothalamus where interaction between orexigenic neurons, expressing Neuropeptide Y/Agouti-related protein, and anorexigenic neurons, expressing Pro-opiomelanocortin cocaine/Amphetamine-related transcript, controls energy homeostasis. Within the hypothalamus, several peripheral signals have been shown to modulate the activity of these neurons, including the orexigenic peptide ghrelin and the anorexigenic hormones insulin and leptin. In addition to the accumulated knowledge on neuropeptide signaling, presence and function of amino acid neurotransmitters in key hypothalamic neurons brought a new light into appetite regulation. Therefore, the principal aim of this review will be to describe the current knowledge of the role of amino acid neurotransmitters in the mechanism of neuronal activation during appetite regulation and the associated neuronal-astrocytic metabolic coupling mechanisms. Glutamate and GABA dominate synaptic transmission in the hypothalamus and administration of their receptors agonists into hypothalamic nuclei stimulates feeding. By using (13)C High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance spectroscopy based analysis, the Cerdán group has shown that increased neuronal firing in mice hypothalamus, as triggered by appetite during the feeding-fasting paradigm, may stimulate the use of lactate as neuronal fuel leading to increased astrocytic glucose consumption and glycolysis. Moreover, fasted mice showed increased hypothalamic [2-(13)C]GABA content, which may be explained by the existence of GABAergic neurons in key appetite regulation hypothalamic nuclei. Interestingly, increased [2-(13)C]GABA concentration in the hypothalamus of fasted animals appears to result mainly from reduction in GABA metabolizing pathways, rather than increased GABA synthesis by augmented activity of the glutamate-glutamine-GABA

  10. Linking GABA and glutamate levels to cognitive skill acquisition during development

    PubMed Central

    Krause, Beatrix; King, Andrew J.; Near, Jamie

    2015-01-01

    Abstract Developmental adjustments in the balance of excitation and inhibition are thought to constrain the plasticity of sensory areas of the cortex. It is unknown however, how changes in excitatory or inhibitory neurochemical expression (glutamate, γ‐aminobutyric acid (GABA)) contribute to skill acquisition during development. Here we used single‐voxel proton magnetic resonance spectroscopy (1H‐MRS) to reveal how differences in cortical glutamate vs. GABA ratios relate to face proficiency and working memory abilities in children and adults. We show that higher glutamate levels in the inferior frontal gyrus correlated positively with face processing proficiency in the children, but not the adults, an effect which was independent of age‐dependent differences in underlying cortical gray matter. Moreover, we found that glutamate/GABA levels and gray matter volume are dissociated at the different maturational stages. These findings suggest that increased excitation during development is linked to neuroplasticity and the acquisition of new cognitive skills. They also offer a new, neurochemical approach to investigating the relationship between cognitive performance and brain development across the lifespan. Hum Brain Mapp 36:4334–4345, 2015. © 2015 The Authors. Human Brain Mapping Published byWiley Periodicals, Inc. PMID:26350618

  11. Inhibitory effects of several saturated fatty acids and their related fatty alcohols on the growth of Candida albicans.

    PubMed

    Hayama, Kazumi; Takahashi, Miki; Yui, Satoru; Abe, Shigeru

    2015-12-01

    We examined the effect of 5 saturated fatty acids and their related alcohols on the growth of Candida albicans. The inhibitory effects of these compounds against the yeast and hyphal growth forms of C. albicans were examined using the modified NCCLS method and crystal violet staining, respectively. Among these compounds, capric acid inhibited both types of growth at the lowest concentration. The IC(80), i.e., the concentration at which the compounds reduced the growth of C. albicans by 80% in comparison with the growth of control cells, of capric acid for the hyphal growth of this fungus, which is indispensable for its mucosal invasion, was 16.7 μM. These fatty acids, including capric acid, have an unpleasant smell, which may limit their therapeutic use. To test them at reduced concentrations, the combined effect of these fatty acids and oligonol, a depolymerized polyphenol, was evaluated in vitro. These combinations showed potent synergistic inhibition of hyphal growth [fractional inhibitory concentration (FIC) index = 0.319]. Our results demonstrated that capric acid combined with oligonol could be used as an effective anti-Candida compound. It may be a candidate prophylactic or therapeutic tool against mucosal Candida infection.

  12. Inhibitory neurosteroids and the GABAA receptor.

    PubMed

    Seljeset, Sandra; Laverty, Duncan; Smart, Trevor G

    2015-01-01

    γ-Aminobutyric acid type A receptors (GABAARs) are vital proteins that are engaged in regulating neural circuit activity in the central nervous system. Their effectiveness in this task is dependent on the extent of receptor modulation by naturally occurring ligands that are released in the brain. One of the foremost examples of such ligands is the neurosteroids that can either potentiate GABAAR function or cause direct inhibition. To fully understand the underlying mechanisms by which neurosteroids modulate GABAARs, it is necessary to identify their binding sites on the receptors. For potentiating neurosteroids, recent work has made substantive progress in identifying a binding site located in the transmembrane domains of GABAAR α subunits. However, for the inhibitory neurosteroids, several possibilities exist including an ion channel site as well as potential sites in the transmembrane domain. This review systematically analyzes the evidence behind possible binding sites for the inhibitory neurosteroids. We consider the chemical structure-function properties of such inhibitory neurosteroids, their physiological effects on synaptic inhibition, and whether a binding site exists in the GABA ion channel or in other areas of the transmembrane domain. Finally, we discuss how structural homology modeling and Cys-loop receptor homologues may help to locate the inhibitory neurosteroid-binding site on GABAARs.

  13. Inhibitory effect of p-coumaric acid by Rhodiola sachalinensis on melanin synthesis in B16F10 cells.

    PubMed

    Park, So-Hee; Kim, Dong-Seok; Park, Seo-Hyoung; Shin, Jung-Won; Youn, Sang-Woong; Park, Kyoung-Chan

    2008-04-01

    Rhodiola has been widely used in traditional Asian medicine. In this study, we tested the hypopigmentation effects of R. sachalinensis and its active compounds including catechin, chlorogenic acid, p-coumaric acid, and p-tyrosol. Results have shown that only p-coumaric acid inhibits melanin synthesis in B16F10 cells. However, p-coumaric acid did not inhibit tyrosinase activity when L-DOPA was used as a substrate. Instead, p-coumaric acid inhibited tyrosinase activity when L-tyrosine was used as a substrate. We further analyzed the changes of cAMP responsive element binding protein (CREB) phosphorylation and tyrosinase gene expression. The results indicate that p-coumaric acid does not affect CREB phosphorylation or tyrosinase protein production. In turn, these findings demonstrate that p-coumaric acid has no effect on the upstream regulation of tyrosinase gene expression, although p-coumaric acid showed a significant inhibitory effect on melanogenesis. Because p-coumaric acid showed different effects on tyrosinase activity according to different substrates, we tested whether tyrosinase can utilize p-coumaric acid as a substrate. Our findings revealed that competitive inhibition occurs between p-coumaric acid and tyrosine. Consequently, this finding could be a primary mechanism for the hypopigmenting action of p-coumaric acid.

  14. A mitochondrial GABA permease connects the GABA shunt and the TCA cycle, and is essential for normal carbon metabolism.

    PubMed

    Michaeli, Simon; Fait, Aaron; Lagor, Kelly; Nunes-Nesi, Adriano; Grillich, Nicole; Yellin, Ayelet; Bar, Dana; Khan, Munziba; Fernie, Alisdair R; Turano, Frank J; Fromm, Hillel

    2011-08-01

    In plants, γ-aminobutyric acid (GABA) accumulates in the cytosol in response to a variety of stresses. GABA is transported into mitochondria, where it is catabolized into TCA cycle or other intermediates. Although there is circumstantial evidence for mitochondrial GABA transporters in eukaryotes, none have yet been identified. Described here is an Arabidopsis protein similar in sequence and topology to unicellular GABA transporters. The expression of this protein complements a GABA-transport-deficient yeast mutant. Thus the protein was termed AtGABP to indicate GABA-permease activity. In vivo localization of GABP fused to GFP and immunobloting of subcellular fractions demonstrate its mitochondrial localization. Direct [(3) H]GABA uptake measurements into isolated mitochondria revealed impaired uptake into mitochondria of a gabp mutant compared with wild-type (WT) mitochondria, implicating AtGABP as a major mitochondrial GABA carrier. Measurements of CO(2) release, derived from radiolabeled substrates in whole seedlings and in isolated mitochondria, demonstrate impaired GABA-derived input into the TCA cycle, and a compensatory increase in TCA cycle activity in gabp mutants. Finally, growth abnormalities of gabp mutants under limited carbon availability on artificial media, and in soil under low light intensity, combined with their metabolite profiles, suggest an important role for AtGABP in primary carbon metabolism and plant growth. Thus, AtGABP-mediated transport of GABA from the cytosol into mitochondria is important to ensure proper GABA-mediated respiration and carbon metabolism. This function is particularly essential for plant growth under conditions of limited carbon.

  15. Localization and expression of GABA transporters in the suprachiasmatic nucleus

    PubMed Central

    Moldavan, Michael; Cravetchi, Olga; Williams, Melissa; Irwin, Robert P.; Aicher, Sue A.; Allen, Charles N.

    2015-01-01

    GABA is a principal neurotransmitter in the suprachiasmatic hypothalamic nucleus (SCN), the master circadian clock. Despite the importance of GABA and GABA uptake for functioning of the circadian pacemaker, the localization and expression of GABA transporters (GATs) in the SCN has not been investigated. The present studies used Western blot analysis, immunohistochemistry, and electron microscopy to demonstrate the presence of GABA transporter 1 (GAT1) and GABA transporter 3 (GAT3) in the SCN. By light microscopy, GAT1 and GAT3 were co-localized throughout the SCN, but were not expressed in the perikarya of arginine vasopressin- or vasoactive intestinal peptide-immunoreactive (−ir) neurons of adult rats, nor in the neuronal processes labeled with the Neurofilament Heavy Chain. By electron microscopy, GAT1- and GAT3-ir was found in glial processes surrounding unlabeled neuronal perikarya, axons, dendrites, and enveloped symmetric and asymmetric axo-dendritic synapses. Glial Fibrillary Acidic Protein-ir astrocytes grown in cell culture were immunopositive for GAT1 and GAT3 – and both GATs could be observed in the same glial cell. These data demonstrate that synapses in the SCN function as “tripartite” synapses consisting of presynaptic axon terminals, postsynaptic membranes, and astrocytes that contain GABA transporters. This model suggests that astrocytes expressing both GATs may regulate the extracellular GABA, and thereby modulate the activity of neuronal networks in the SCN. PMID:26390912

  16. Glycyrrhetinic acid exhibits strong inhibitory effects towards UDP-glucuronosyltransferase (UGT) 1A3 and 2B7.

    PubMed

    Huang, Yin-Peng; Cao, Yun-Feng; Fang, Zhong-Ze; Zhang, Yan-Yan; Hu, Cui-Min; Sun, Xiao-Yu; Yu, Zhen-Wen; Zhu, Xu; Hong, Mo; Yang, Lu; Sun, Hong-Zhi

    2013-09-01

    The aim of the present study is to evaluate the inhibitory effects of liver UDP-glucuronosyltransferases (UGTs) by glycyrrhizic acid and glycyrrhetinic acid, which are the bioactive ingredients isolated from licorice. The results showed that glycyrrhetinic acid exhibited stronger inhibition towards all the tested UGT isoforms, indicating that the deglycosylation process played an important role in the inhibitory potential towards UGT isoforms. Furthermore, the inhibition kinetic type and parameters were determined for the inhibition of glycyrrhetinic acid towards UGT1A3 and UGT2B7. Data fitting using Dixon and Lineweaver-Burk plots demonstrated that the inhibition of UGT1A3 and UGT2B7 by glycyrrhetinic acid was best fit to competitive and noncompetitive type, respectively. The second plot using the slopes from Lineweaver-Burk plots versus glycyrrhetinic acid concentrations was employed to calculate the inhibition kinetic parameters (K(i)), and the values were calculated to be 0.2 and 1.7 μM for UGT1A3 and UGT2B7, respectively. All these results remind us the possibility of UGT inhibition-based herb-drug interaction. However, the explanation of these in vitro parameters should be paid more caution due to complicated factors, including the probe substrate-dependent UGT inhibition behaviour, environmental factors affecting the abundance of herbs' ingredients, and individual difference of pharmacokinetic factors.

  17. Characterization of bicuculline/baclofen-insensitive (rho-like) gamma-aminobutyric acid receptors expressed in Xenopus oocytes. II. Pharmacology of gamma-aminobutyric acidA and gamma-aminobutyric acidB receptor agonists and antagonists.

    PubMed

    Woodward, R M; Polenzani, L; Miledi, R

    1993-04-01

    Poly(A)+ RNA from mammalian retina expresses bicuculline/baclofen-insensitive gamma-aminobutyric acid (GABA) receptors in Xenopus oocytes with properties similar to those of homooligomeric GABA rho 1 receptors. The pharmacological profile of these rho-like receptors was extended by measuring sensitivities to various GABAA and GABAB receptor ligands. For direct comparison the same compounds were also assayed with GABAA receptors expressed by rat brain RNA. The potency sequence for heterocyclic GABA analogues at the GABA rho-like receptors was GABA (1.3) > muscimol (2.3) > isoguvacine (100) (approximate EC50 in parentheses; all EC50 and Kb values given in microM). Both muscimol and isoguvacine were partial agonists at the rho-like receptors. 4,5,6,7-Tetrahydroisoxazolo[5,4-c]pyridin-3-ol (Kb congruent to 32), piperidine-4-sulfonic acid (Kb congruent to 85), and isonipecotic acid (Kb congruent to 1000) acted primarily as competitive antagonists, showing little or no activity as agonists. The sulfonic acid GABA analogue 3-aminopropanesulfonic acid was also a competitive antagonist (Kb congruent to 20). Conformationally restricted GABA analogues trans- and cis-4-aminocrotonic acid (TACA and CACA) were agonists at the rho-like receptors. TACA (EC50 congruent to 0.6) had twice the potency of GABA and was 125 times more potent than CACA (EC50 congruent to 75). Z-3-(Amidinothio)propenoic acid, an isothiouronium analogue of GABA, had little activity as an agonist but instead acted as a competitive antagonist (Kb congruent to 20). At concentrations of > 100 microM, bicuculline did have some weak competitive inhibitory effects on the GABA rho-like receptors (Kb congruent to 6000), but it was at least 5000 times more potent at GABAA receptors. Strychnine (Kb congruent to 70) and SR-95531 (Kb congruent to 35) also were competitive inhibitors of the rho-like receptors but were, respectively, 20 and 240 times more potent at GABAA receptors. The GABAB receptor ligands baclofen

  18. Function of taurine transporter (Slc6a6/TauT) as a GABA transporting protein and its relevance to GABA transport in rat retinal capillary endothelial cells.

    PubMed

    Tomi, Masatoshi; Tajima, Ayumi; Tachikawa, Masanori; Hosoya, Ken-ichi

    2008-10-01

    The purpose of this study was to identify the uptake mechanism of gamma-aminobutyric acid (GABA) via taurine transporter (Slc6a6/TauT) and its relationship with GABA transport at the inner BRB. Rat Slc6a6/TauT-transfected HeLa cells exhibited Na(+)-, Cl(-)-, and concentration-dependent [3H]GABA uptake with a Km of 1.5 mM. Taurine, beta-alanine, and GABA markedly inhibited Slc6a6/TauT-mediated uptake of [3H]GABA. The uptake of [3H]GABA by a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB2) was Na(+)-, Cl(-)-, and concentration-dependent with a Km of 2.0 mM. This process was more potently inhibited by substrates of Slc6a6/TauT, taurine and beta-alanine, than those of GABA transporters, GABA and betaine. In the presence of taurine, there was competitive inhibition with a Ki of 74 microM. [3H]Taurine also exhibited competitive inhibition with a Ki of 1.8 mM in the presence of GABA. In conclusion, rat Slc6a6/TauT has the ability to use GABA as a substrate and Slc6a6/TauT-mediated GABA transport appears to be present at the inner BRB.

  19. Endogenous synthesis of taurine and GABA in rat ocular tissues.

    PubMed

    Heinämäki, A A

    1988-01-01

    The endogenous production of taurine and gamma-aminobutyric acid (GABA) in rat ocular tissues was investigated. The activities of taurine-producing enzyme, cysteine sulfinic acid decarboxylase (CSAD), and GABA-synthesizing enzyme, glutamic acid decarboxylase (GAD), were observed in the retina, lens, iris-ciliary body and cornea. The highest specific activity of CSAD was in the cornea and that of GAD in the retina. The discrepancy between CSAD activity and taurine content within the ocular tissues indicates that intra- or extraocular transport processes may regulate the concentration of taurine in the rat eye. The GAD activity and the content of GABA were distributed in parallel within the rat ocular tissues. The quantitative results suggest that the GAD/GABA system has functional significance only in the retina of the rat eye.

  20. GABA-A and GABA-B receptors in the cuneate nucleus of the rat in vivo.

    PubMed

    Orviz, P; Cecchini, B G; Andrés-Trelles, F

    1986-09-01

    Electric stimulation of the rat forepaw evokes a negative potential (N-wave) at the ipsilateral cuneate nucleus. The responses of the N-wave to microiontophoretically applied GABA agonists and antagonists have been studied. Applications of GABA-A agonists (3-amino-propanesulfonic acid and muscimol) reduce the amplitude of the N-wave. This effect decreases during prolonged application, suggesting a desensitization of GABA-A receptors. In addition the effect of muscimol is reduced by (-)-bicuculline methiodide. Baclofen (a GABA-B agonist) also depresses the N-wave but its action lasts longer, is less reversible, shows no desensitization and is not blocked by (-)-bicuculline methiodide. The different responses of the N-wave to GABA-A and GABA-B agonists are compatible with the existence of different types of functional receptors for them in the cuneate nucleus of the rat. The receptors activated by muscimol (GABA-A) are clearly not the same as the ones activated by baclofen (conceivably GABA-B).

  1. Comparative Mapping of GABA-Immunoreactive Neurons in the Buccal Ganglia of Nudipleura Molluscs.

    PubMed

    Gunaratne, Charuni A; Katz, Paul S

    2016-04-15

    Phylogenetic comparisons of neurotransmitter distribution are important for understanding the ground plan organization of nervous systems. This study describes the γ-aminobutyric acid (GABA)-immunoreactive (GABA-ir) neurons in the buccal ganglia of six sea slug species (Mollusca, Gastropoda, Euthyneura, Nudipleura). In the nudibranch species, Hermissenda crassicornis, Tritonia diomedea, Tochuina tetraquetra, and Dendronotus iris, the number of GABA-ir neurons was highly consistent. Another nudibranch, Melibe leonina, however, contained approximately half the number of GABA-ir neurons. This may relate to its loss of a radula and its unique feeding behavior. The GABA immunoreactivity in a sister group to the nudibranchs, Pleurobranchaea californica, differed drastically from that of the nudibranchs. Not only did it have significantly more GABA-ir neurons but it also had a unique GABA distribution pattern. Furthermore, unlike the nudibranchs, the Pleurobranchaea GABA distribution was also different from that of other, more distantly related, euopisthobranch and panpulmonate snails and slugs. This suggests that the Pleurobranchaea GABA distribution may be a derived feature, unique to this lineage. The majority of GABA-ir axons and neuropil in the Nudipleura were restricted to the buccal ganglia, commissures, and connectives. However, in Tritonia and Pleurobranchaea, we detected a few GABA-ir fibers in buccal nerves that innervate feeding muscles. Although the specific functions of the GABA-ir neurons in the species in this study are not known, the innervation pattern suggests these neurons may play an integrative or regulatory role in bilaterally coordinated behaviors in the Nudipleura.

  2. Development of GABA-mediated, chloride-dependent inhibition in CA1 pyramidal neurones of immature rat hippocampal slices.

    PubMed Central

    Zhang, L; Spigelman, I; Carlen, P L

    1991-01-01

    1. gamma-Aminobutyric acid (GABA)-mediated, Cl(-)-dependent inhibitory postsynaptic potentials (IPSPs) and GABA currents in immature rat hippocampal CA1 neurones were studied using the whole-cell recording technique in brain slices. 2. IPSPs evoked by electrical stimulation were observed in postnatal 2- to 5- (PN2-5), 8- to 13-(PN8-13) and 15- to 20-(PN15-20)day-old CA1 neurones. In the presence of glutamate receptor blockers 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and D-2-amino-5-phosphonovaleric acid (APV), the reversal potential for the IPSP (EIPSP) was near the resting membrane potential (RMP) in the PN2-5 neurones, but 13 and 25 mV more negative than the RMP in PN8-13 and PN15-20 neurones respectively. IPSPs and GABA currents were blocked by the GABAA-receptor antagonists bicuculline or picrotoxin. 3. The reversal potential for somatic GABA currents (EGABA) was examined in the presence of tetrodotoxin (TTX). There was a strong dependence of the EGABA upon the patch pipette [Cl-] ([Cl-]p). indicating that the GABA currents were mediated by a Cl- conductance. In PN2-5 neurones, EGABA agreed with the value predicted by the Goldman-Hodgkin-Katz equation at given concentrations of internal and external anions permeable through GABA-activated Cl- channels, whereas EGABA in older neurones was 8-18 mV more negative. 4. Examination of the relations between EGABA, holding potential, [Cl-]p and resting conductance indicated that the membrane of the PN2-5 neurones was readily permeable to Cl- which followed a passive Donnan equilibrium. Passive distribution of Cl- played a decreasing role in PN8-13 neurones and in PN15-20 neurones. 5. To assess the contribution of outward Cl- co-transport, bath applications of high K+ or furosemide were performed. High K+ and furosemide caused a reversible positive shift of EGABA in PN15-20 neurones. Raising the temperature moved EGABA to a more negative potential, with a Q10 of 5 mV. A similar change of EGABA in response to high K

  3. Effect of gamma-aminobutyric acid on neurally mediated contraction of guinea pig trachealis smooth muscle.

    PubMed

    Tamaoki, J; Graf, P D; Nadel, J A

    1987-10-01

    To determine whether gamma-aminobutyric acid (GABA) affects the contractile properties of airway smooth muscle and, if so, what the mechanism of action is, the authors studied guinea pig tracheal rings under isometric conditions in vitro. GABA and related substances, baclofen and muscimol, had no effect on the resting tension but reversibly depressed contractions induced by electrical field stimulation in a dose-dependent fashion, IC50 values (mean +/- S.E.) being 5.6 +/- 1.4 X 10(-6) M, 6.8 +/- 0.9 X 10(-6) M and 8.5 +/- 1.5 X 10(-5) M, respectively. In contrast, GABA did not alter the response to exogenous acetylcholine or the nonadrenergic noncholinergic inhibitory component. Pretreatment of tissues with bicuculline antagonized the inhibitory effect of GABA as well as that of baclofen. This inhibitory effect was not modified by propranolol, phentolamine, hemicholinium-3 or naloxone, but it was blocked by the Cl channel blocker furosemide and by the substitution of external Cl. These results suggest that GABA decreases the contractile response of airway smooth muscle to cholinergic nerve stimulation by inhibiting the evoked release of acetylcholine and that this effect is exerted by activating Cl-dependent, bicuculline-sensitive GABA receptors.

  4. 5-HT and GABA modulate intrinsic excitability of type I interneurons in Hermissenda.

    PubMed

    Jin, Nan Ge; Tian, Lian-Ming; Crow, Terry

    2009-11-01

    The sensory neurons (photoreceptors) in the visual system of Hermissenda are one site of plasticity produced by Pavlovian conditioning. A second site of plasticity produced by conditioning is the type I interneurons in the cerebropleural ganglia. Both photoreceptors and statocyst hair cells of the graviceptive system form monosynaptic connections with identified type I interneurons. Two proposed neurotransmitters in the graviceptive system, serotonin (5-HT) and gamma-aminobutyric acid (GABA), have been shown to modify synaptic strength and intrinsic neuronal excitability in identified photoreceptors. However, the potential role of 5-HT and GABA in plasticity of type I interneurons has not been investigated. Here we show that 5-HT increased the peak amplitude of light-evoked complex excitatory postsynaptic potentials (EPSPs), enhanced intrinsic excitability, and increased spike activity of identified type I(e(A)) interneurons. In contrast, 5-HT decreased spike activity and intrinsic excitability of type I(e(B)) interneurons. The classification of two categories of type I(e) interneurons was also supported by the observation that 5-HT produced opposite effects on whole cell steady-state outward currents in type I(e) interneurons. Serotonin produced a reduction in the amplitude of light-evoked complex inhibitory PSPs (IPSPs), increased spontaneous spike activity, decreased intrinsic excitability, and depolarized the resting membrane potential of identified type I(i) interneurons. In contrast to the effects of 5-HT, GABA produced inhibition in both types of I(e) interneurons and type I(i) interneurons. These results show that 5-HT and GABA can modulate the intrinsic excitability of type I interneurons independent of the presynaptic effects of the same transmitters on excitability and synaptic efficacy of photoreceptors.

  5. 5-HT and GABA Modulate Intrinsic Excitability of Type I Interneurons in Hermissenda

    PubMed Central

    Jin, Nan Ge; Tian, Lian-Ming

    2009-01-01

    The sensory neurons (photoreceptors) in the visual system of Hermissenda are one site of plasticity produced by Pavlovian conditioning. A second site of plasticity produced by conditioning is the type I interneurons in the cerebropleural ganglia. Both photoreceptors and statocyst hair cells of the graviceptive system form monosynaptic connections with identified type I interneurons. Two proposed neurotransmitters in the graviceptive system, serotonin (5-HT) and γ-aminobutyric acid (GABA), have been shown to modify synaptic strength and intrinsic neuronal excitability in identified photoreceptors. However, the potential role of 5-HT and GABA in plasticity of type I interneurons has not been investigated. Here we show that 5-HT increased the peak amplitude of light-evoked complex excitatory postsynaptic potentials (EPSPs), enhanced intrinsic excitability, and increased spike activity of identified type Ie(A) interneurons. In contrast, 5-HT decreased spike activity and intrinsic excitability of type Ie(B) interneurons. The classification of two categories of type Ie interneurons was also supported by the observation that 5-HT produced opposite effects on whole cell steady-state outward currents in type Ie interneurons. Serotonin produced a reduction in the amplitude of light-evoked complex inhibitory PSPs (IPSPs), increased spontaneous spike activity, decreased intrinsic excitability, and depolarized the resting membrane potential of identified type Ii interneurons. In contrast to the effects of 5-HT, GABA produced inhibition in both types of Ie interneurons and type Ii interneurons. These results show that 5-HT and GABA can modulate the intrinsic excitability of type I interneurons independent of the presynaptic effects of the same transmitters on excitability and synaptic efficacy of photoreceptors. PMID:19710377

  6. Inhibitory effect of the ether extract of human feces on activities of mutagens: inhibition by oleic and linoleic acids.

    PubMed

    Hayatsu, H; Arimoto, S; Togawa, K; Makita, M

    1981-05-01

    An ether extract of normal human feces showed inhibitory effects on the activities of several mutagens in the Ames tests. By addition of the ether extract at an amount equivalent to 0.5 g of a sample of feces, the mutagenicity of 1.5 nmole of 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) on Salmonella typhimurium TA98 was completely inhibited. No killing of the bacteria was detected during this treatment. Other mutagens also subject to the inhibition were 2-amino-6-methyl-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1), 2-amino-9H-pyrido[2,3-b]indole (Glob-P-2), 2-amino-3-methylimidazo[4,5-d]quinoline (IQ), benzo[a]pyrene and aflatoxin B1. Apart from these mutagens, which require S9 for their activation, the direct mutagen prepared from Trp-P-1 by treatment with S9 was also inhibited by the fecal extract. The inhibitory principles in the fecal extract were fractionated by thin-layer chromatography on silica gel and were identified as oleic and linoleic acids. Whereas these unsaturated fatty acids showed strong inhibitory activities, saturated fatty acids, i.e, stearic and palmitic acids, did not exhibit any inhibition. Although the physiological significance of these effects of oleate and linoleate is yet to be elucidated, this finding has indicated that care must be taken in screening mutagens by the Ames tests to avoid false negatives resulting from the presence of unsaturated fatty acids in the system.

  7. Control of cortical neuronal migration by glutamate and GABA.

    PubMed

    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 Ca(2+) 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.

  8. 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

  9. Effects of oxytocin on GABA signalling in the foetal brain during delivery.

    PubMed

    Khazipov, Rustem; Tyzio, Roman; Ben-Ari, Yehezkel

    2008-01-01

    Oxytocin (OXT) exerts multiple effects in the adult central nervous system. However, little is known about the effects of OXT on foetal neurons during delivery, at the time when a surge of OXT occurs. In a recent study, the effects of OXT on gamma-aminobutyric acid (GABA) signalling have been reported in foetal and newborn rats. In the immature rat hippocampal and neocortical neurons at birth, endogenous OXT induced a switch in the action of GABA from excitatory to inhibitory. This excitatory-to-inhibitory switch was caused by a switch in the polarity of the GABAergic responses from depolarizing to hyperpolarizing, reflecting a decrease in the intracellular chloride concentration. The effects of OXT were mimicked and occluded by bumetanide, a selective blocker of the chloride co-transporter NKCC1, suggesting that the effects of OXT involve inhibition of NKCC1. Neuronal death caused by anoxic-aglycaemic episodes was substantially delayed in the foetal hippocampus by endogenous OXT. These findings suggest that OXT plays important role in the preparation of the foetal brain to delivery.

  10. The action of GABA receptor agonists and antagonists on muscle membrane conductance in Schistocerca gregaria.

    PubMed Central

    Murphy, V. F.; Wann, K. T.

    1988-01-01

    1. The properties of postsynaptic gamma-aminobutyric acid (GABA) receptors in the extensor tibiae muscle of Schistocerca gregaria were studied by conventional electrophysiological recording techniques. 2. GABA and other active GABA receptor agonists produced rapid, dose-dependent, reversible increases in membrane conductance. 3. In two microelectrode experiments the ED50 for GABA was approximately 1 mM. In three microelectrode experiments (assuming short cable theory conditions) the ED50 for GABA was 2.3 mM. The Hill coefficient for GABA estimated from the latter experiments was 1.4. 4. The relative potency of muscimol/GABA at the ED50 for GABA was 1.36. 3-Aminopropane sulphonic acid (3-APS) and isonipecotic acid were weakly active, baclofen and piperidine-4-sulphonic acid (P4S) were inactive. Isoguvacine produced depolarizations and increases in conductance in preparations which hyperpolarized in response to GABA. These depolarizations were enhanced by both picrotoxin and pitrazepin although the increases in input conductance were depressed. 5. Picrotoxin (20 microM), (+)-bicuculline (20-100 microM) and pitrazepin (1-10 microM) all reversibly antagonized GABA-induced responses. Such antagonism was not competitive in the case of picrotoxin and (+)-bicuculline but was competitive for pitrazepin. Schild plot analysis gave an average pA2 value of 5.5 for pitrazepin. 6. The significance of these results is briefly discussed. PMID:2850061

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

    PubMed

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

    2011-09-20

    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 GABA(B1b) 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 GABA(Aα2) mRNA expression in the prefrontal cortex and amygdala, but increased GABA(Aα2) 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.

  12. Effects of white rice containing enriched gamma-aminobutyric acid on blood pressure

    PubMed Central

    Nishimura, Mie; Yoshida, Shin-ichi; Haramoto, Masafumi; Mizuno, Hidenori; Fukuda, Tomohiko; Kagami-Katsuyama, Hiroyo; Tanaka, Aiko; Ohkawara, Tatsuya; Sato, Yuji; Nishihira, Jun

    2015-01-01

    Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter with beneficial effects including antihypertension and antistress properties. In this study, we examined the effects of GABA-enriched white rice (GABA rice) on blood pressure (BP) in 39 mildly hypertensive adults in a randomized, double-blind, placebo-controlled study. The participants were divided into a test group (n = 22) who consumed rice with 11.2 mg GABA/100 g of rice and a placebo group (n = 17) who consumed rice with 2.7 mg GABA/100 g of rice. For 8 weeks, the participants took 150 g of either the GABA rice or the placebo rice. Hematological examinations were performed on both groups at 0, 4, and 8 weeks after the start of rice consumption. Home BP was self-measured two times daily, morning and evening, from 1 weeks before to 2 weeks after the intervention. Although the hospital BP and evening BP measurements of the participants showed no significant change, consumption of the GABA rice improved the morning BP compared with the placebo rice after the 1st week and during the 6th and 8th weeks. These results showed the possibility that the GABA rice improves morning hypertension. PMID:26870683

  13. [GABA, a key transmitter for fetal brain maturation].

    PubMed

    Ben-Ari, Yehezkel

    2007-01-01

    GABA, the principal inhibitory transmitter excites immature neurons in all animal species studied. This is due to the higher intracellular concentration of chloride at early developmental stages. Excitatory actions of GABA play an important action in brain maturation. Recent observations also suggest an abrupt shift during delivery that exerts a neuro-protective action contributing to reduce the sequels of trauma and anoxic episodes. These observations have important clinical implications in relation to delivery associated insults but also preterm delivery and more generally consumption of agents during gestation.

  14. The action of oxygen and oxygen at high pressure on inhibitory transmission.

    PubMed

    Colton, C A; Colton, J S

    1986-01-29

    The effect of 100% oxygen at ambient pressure, 100% oxygen at 1.7 Atmospheres Absolute (ATA), 100% oxygen at 5.1 ATA, helium at 1.7 ATA and helium at 5.1 ATA on inhibitory synaptic transmission was studied using the lobster walking leg neuromuscular preparation. Exposure to 100% oxygen at ambient pressure, at 1.7 ATA or at 5.1 ATA produced a decrease in inhibitory transmission manifest as a fall in inhibitory synaptic conductance (Ginh). The largest decrease in Ginh was seen in 100% oxygen at ambient pressure, while a progressively smaller decrease was seen in 100% oxygen at 1.7 ATA and 5.1 ATA, respectively. Also associated with 100% oxygen at ambient pressure was the disappearance of inhibitory junction potentials. Pressurization with helium produced a fall in Ginh at 5.1 ATA but no change or a slight increase at 1.7 ATA. The action of either 100% oxygen at ambient and at 1.7 or 5.1 ATA or helium at 1.7 or 5.1 ATA was shown to be on presynaptic parameters since the percent decrease in Ro induced by exogenous application of gamma-aminobutyric acid (GABA), the inhibitory transmitter, was the same in either 100% oxygen at ambient pressure, 100% oxygen or helium at 1.7 ATA and 5.1 ATA. The similarity in action of oxygen to the action of isoniazid, a known glutamic acid decarboxylase (the enzyme that catalyzes the production of GABA) inhibitor in the same preparation suggests that one possible site of oxygen action is on GABA production.

  15. Photorelease of GABA with Visible Light Using an Inorganic Caging Group

    PubMed Central

    Rial Verde, Emiliano M.; Zayat, Leonardo; Etchenique, Roberto; Yuste, Rafael

    2008-01-01

    We describe the selective photorelease of γ-amino butyric acid (GABA) with a novel caged-GABA compound that uses a ruthenium complex as photosensor. This compound (“RuBi-GABA”) can be excited with visible wavelengths, providing greater tissue penetration, less photo-toxicity, and faster photorelease kinetics than currently used UV light-sensitive caged compounds. Using pyramidal neurons from neocortical brain slices, we show that RuBi-GABA uncaging induces GABA-A receptor-mediated responses, has no detectable side effects on endogenous GABAergic and glutamatergic receptors and generates responses with kinetics and spatial resolution comparable to the best caged GABA compounds presently available. Finally, we illustrate two potential applications of RuBi-GABA uncaging: GABA receptor mapping, and optical silencing of neuronal firing. PMID:18946542

  16. 3H-GABA uptake selectively labels identifiable neurons in the leech central nervous system

    SciTech Connect

    Cline, H.T.

    1983-04-10

    Segmental ganglia of the leech ventral nerve cord synthesize the neurotransmitter gamma-aminobutyric acid (GABA) when incubated in the presence of the precursor glutamate, suggesting that there may be GABA-ergic neurons in the leech nerve cord. GABA-accumulating neurons of the two taxonomically distant leech species, Haementeria ghilianii and Hirudo medicinalis, have been labeled by taking advantage of their high-affinity uptake system for the neurotransmitter. Autoradiography of sectioned segmental ganglia previously exposed to 3H-GABA reveals a reproducible pattern of about thirty 3H-GABA-labeled neuronal cell bodies per ganglion. The majority of 3H-GABA-labeled neuronal cell bodies are bilaterally paired, although some apparently unpaired cell bodies also accumulate label. Neuronal processes were reproducibly labeled by GABA uptake and could be traced in the neuropil through commissures and fiber tracts into the segmental nerve roots and interganglionic connectives, respectively.

  17. Presynaptic modulation by L-glutamate and GABA of sympathetic co-transmission in rat isolated vas deferens.

    PubMed

    Kwan, Y W; Ngan, M P; Tsang, K Y; Lee, H M; Chu, L A

    1996-06-01

    , whilst kainate (Kain, 1 microM-1 mM) caused an inhibition of the EFS-induced contractions. Effects of Kain could be abolished by the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dioxine (CNQX, 10 microM). NMDA, Quis and Kain had no effect on the exogenous ATP- or noradrenaline-induced contractions. 7. It is concluded that the excitatory amino acid L-glutamate modulates the electrically evoked vas deferens contraction through conversion to the inhibitory amino acid GABA by a specific GABA transaminase. The GABA formed may then act on GABAB receptors and cause inhibition of the contraction through a presynaptic mechanism.

  18. Receptor subtype-dependent positive and negative modulation of GABA(A) receptor function by niflumic acid, a nonsteroidal anti-inflammatory drug.

    PubMed

    Sinkkonen, Saku T; Mansikkamäki, Salla; Möykkynen, Tommi; Lüddens, Hartmut; Uusi-Oukari, Mikko; Korpi, Esa R

    2003-09-01

    In addition to blocking cyclooxygenases, members of the fenamate group of nonsteroidal anti-inflammatory drugs have been proposed to affect brain GABAA receptors. Using quantitative autoradiography with GABAA receptor-associated ionophore ligand [35S]t-butylbicyclophosphorothionate (TBPS) on rat brain sections, one of the fenamates, niflumate, at micromolar concentration was found to potentiate GABA actions in most brain areas, whereas being in the cerebellar granule cell layer an efficient antagonist similar to furosemide. With recombinant GABAA receptors expressed in Xenopus laevis oocytes, we found that niflumate potentiated 3 microM GABA responses up to 160% and shifted the GABA concentration-response curve to the left in alpha1beta2gamma2 receptors, the predominant GABAA receptor subtype in the brain. This effect needed the gamma2 subunit, because on alpha1beta2 receptors, niflumate exhibited solely an antagonistic effect at high concentrations. The potentiation was not abolished by the specific benzodiazepine site antagonist flumazenil. Niflumate acted as a potent antagonist of alpha6beta2 receptors (with or without gamma2 subunit) and of alphaXbeta2gamma2 receptors containing a chimeric alpha1 to alpha6 subunit, which suggests that niflumate antagonism is dependent on the same transmembrane domain 1- and 2-including fragment of the alpha6 subunit as furosemide antagonism. This antagonism was noncompetitive because the maximal GABA response, but not the potency, was reduced by niflumate. These data show receptor subtype-dependent positive and negative modulatory actions of niflumate on GABAA receptors at clinically relevant concentrations, and they suggest the existence of a novel positive modulatory site on alpha1beta2gamma2 receptors that is dependent on the gamma2 subunit but not associated with the benzodiazepine binding site.

  19. Frontal Gamma-Aminobutyric Acid Concentrations Are Associated With Cognitive Performance in Older Adults

    PubMed Central

    Porges, Eric C.; Woods, Adam J.; Edden, Richard A.E.; Puts, Nicolaas A.J.; Harris, Ashley D.; Chen, Huaihou; Garcia, Amanda M.; Seider, Talia R.; Lamb, Damon G.; Williamson, John B.; Cohen, Ronald A.

    2017-01-01

    BACKGROUND Gamma-aminobutyric acid (GABA), the brain’s principal inhibitory neurotransmitter, has been associated with perceptual and attentional functioning. Recent application of magnetic resonance spectroscopy (MRS) provides in vivo evidence for decreasing GABA concentrations during adulthood. It is unclear, however, how age-related decrements in cerebral GABA concentrations contribute to cognitive decline, or whether previously reported declines in cerebral GABA concentrations persist during healthy aging. We hypothesized that participants with higher GABA concentrations in the frontal cortex would exhibit superior cognitive function and that previously reported age-related decreases in cortical GABA concentrations continue into old age. METHODS We measured GABA concentrations in frontal and posterior midline cerebral regions using a Mescher-Garwood point-resolved spectroscopy (MEGA-PRESS) 1H-MRS approach in 94 older adults without history or clinical evidence of mild cognitive impairment or dementia (mean age, 73 years). We administered the Montreal Cognitive Assessment to assess cognitive functioning. RESULTS Greater frontal GABA concentrations were associated with superior cognitive performance. This relation remained significant after controlling for age, years of education, and brain atrophy. GABA concentrations in both frontal and posterior regions decreased as a function of age. CONCLUSIONS These novel findings from a large, healthy, older population indicate that cognitive function is sensitive to cerebral GABA concentrations in the frontal cortex, and GABA concentration in frontal and posterior regions continue to decline in later age. These effects suggest that proton MRS may provide a clinically useful method for the assessment of normal and abnormal age-related cognitive changes and the associated physiological contributors. PMID:28217759

  20. Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus

    PubMed Central

    Whissell, Paul D.; Cajanding, Janine D.; Fogel, Nicole; Kim, Jun Chul

    2015-01-01

    Cholecystokinin (CCK)- and parvalbumin (PV)-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behavior. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV) than they were in corresponding primary areas (V1, S1, M1, and Aud1). The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favor the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism. PMID:26441554

  1. Minimal inhibitory concentrations of undissociated lactic, acetic, citric and propionic acid for Listeria monocytogenes under conditions relevant to cheese.

    PubMed

    Wemmenhove, Ellen; van Valenberg, Hein J F; Zwietering, Marcel H; van Hooijdonk, Toon C M; Wells-Bennik, Marjon H J

    2016-09-01

    Minimal inhibitory concentrations (MICs) of undissociated lactic acid were determined for six different Listeria monocytogenes strains at 30 °C and in a pH range of 4.2-5.8. Small increments in pH and acid concentrations were used to accurately establish the growth/no growth limits of L. monocytogenes for these acids. The MICs of undissociated lactic acid in the pH range of 5.2-5.8 were generally higher than at pH 4.6 for the different L. monocytogenes strains. The average MIC of undissociated lactic acid was 5.0 (SD 1.5) mM in the pH range 5.2-5.6, which is relevant to Gouda cheese. Significant differences in MICs of undissociated lactic acid were found between strains of L. monocytogenes at a given pH, with a maximum observed level of 9.0 mM. Variations in MICs were mostly due to strain variation. In the pH range 5.2-5.6, the MICs of undissociated lactic acid were not significantly different at 12 °C and 30 °C. The average MICs of undissociated acetic acid, citric acid, and propionic acid were 19.0 (SD 6.5) mM, 3.8 (SD 0.9) mM, and 11.0 (SD 6.3) mM, respectively, for the six L. monocytogenes strains tested in the pH range 5.2-5.6. Variations in MICs of these organic acids for L. monocytogenes were also mostly due to strain variation. The generated data contribute to improved predictions of growth/no growth of L. monocytogenes in cheese and other foods containing these organic acids.

  2. Benzodiazepines do not potentiate GABA responses in neonatal hippocampal neurons.

    PubMed

    Rovira, C; Ben-Ari, Y

    1991-09-16

    Benzodiazepines (midazolam; flunitrazepam) and pentobarbital increase the response to exogenous gamma-aminobutyric acid (GABA) in adult hippocampal cells. We report in this paper that in contrast pentobarbital but not benzodiazepine potentiate the effects of exogenous (GABA) in neurons recorded from slices of less than two weeks old. This finding suggests that the functional association of benzodiazepine and GABAA receptors is changed during early postnatal life.

  3. ACC GABA levels are associated with functional activation and connectivity in the fronto-striatal network during interference inhibition in patients with borderline personality disorder.

    PubMed

    Wang, Guo-Ying; van Eijk, Julia; Demirakca, Traute; Sack, Markus; Krause-Utz, Annegret; Cackowski, Sylvia; Schmahl, Christian; Ende, Gabriele

    2017-02-15

    Impulsivity often develops from disturbed inhibitory control, a function mainly regulated by γ-Aminobutyric acid (GABA) levels in the anterior cingulate cortex (ACC) and the fronto-striatal system. In this study, we combined MRS GABA measurements and fMRI to investigate neurochemical and neurofunctional correlates of interference inhibition, further emphasizing the direct relationship between those two systems, as well as their relations to impulsivity in patients with BPD. In addition to BOLD activation, task-dependent functional connectivity was assessed by a generalized psychophysiological interactions approach. Full factorial analyses were performed via SPM to examine the main effect (within-group associations) as well as the interaction term (group differences in the association slope). The UPPS scales were used to evaluate impulsivity traits. Compared to healthy controls (HCs), BPD patients exhibited significantly less ACC-caudate functional connectivity during interference inhibition. ACC GABA levels in BPD patients but not in HCs were positively related to the magnitude of activation in several fronto-striatal regions (e.g. ACC, frontal regions, putamen, caudate,) and the strength of ACC-caudate functional connectivity during interference inhibition. The strength of the correlations of GABA with connectivity significantly differs between the two groups. Moreover, among all the UPPS impulsivity subscales, UPPS sensation seeking in the BPD group was related to GABA and was also negatively related to the task-dependent BOLD activation and functional connectivity in the fronto-striatal network. Finally, mediation analyses revealed that the magnitude of activation in the caudate and the strength of ACC-caudate functional connectivity mediated the relationship between ACC GABA levels and UPPS sensation seeking in patients with BPD. Our findings suggest a disconnectivity of the fronto-striatal network in BPD patients during interference inhibition, particularly

  4. Inhibitory effect of acetylsalicylic acid on matrix metalloproteinase - 2 activity in human endothelial cells exposed to high glucose.

    PubMed

    Nicolae, Manuela; Tircol, Magdalena; Alexandru, Dorin

    2005-01-01

    Matrix metalloproteinases play a major role in the process of angiogenesis, an important feature of diabetes complications, cancer or rheumatoid arthritis. High glucose concentrations were reported to augment metalloproteinase-2 secretion in some cell types. In the present study we investigated the influence of acetylsalicylic acid on metalloproteinase- 2 secretion and expression in endothelial cells cultured for one week in high glucose conditions (25 mM and 33 mM). Metalloproteinase-2 activity was evidenced by gel zymography, the protein was identified by Western blotting, and the gene expression was quantitated by RT-PCR. The results indicated a marked inhibitory effect of acetylsalicylic acid at gene expression level (approximately 43%) and also at secretion level in samples of conditioned media (approximately 30%) and cellular homogenates (approximately 70%). This may suggest that acetylsalicylic acid could have a beneficial effect in preventing the angiogenic process that appears in diabetes complications.

  5. Mechanism of Inactivation of γ-Aminobutyric Acid Aminotransferase by (1S ,3S)-3-Amino-4-difluoromethylene-1-cyclopentanoic Acid (CPP-115)

    DOE PAGES

    Lee, Hyunbeom; Doud, Emma H.; Wu, Rui; ...

    2015-01-23

    γ-Aminobutyric acid aminotransferase (GABA-AT) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that degrades GABA, the principal inhibitory neurotransmitter in mammalian cells. When the concentration of GABA falls below a threshold level, convulsions can occur. Inhibition of GABA-AT raises GABA levels in the brain, which can terminate seizures as well as have potential therapeutic applications in treating other neurological disorders, including drug addiction. Among the analogues that we previously developed, (1S,3S)-3-amino-4-difluoromethylene-1-cyclopentanoic acid (CPP-115) showed 187 times greater potency than that of vigabatrin, a known inactivator of GABA-AT and approved drug (Sabril) for the treatment of infantile spasms and refractory adult epilepsy. Recently,more » CPP-115 was shown to have no adverse effects in a Phase I clinical trial. Here we report a novel inactivation mechanism for CPP-115, a mechanism-based inactivator that undergoes GABA-AT-catalyzed hydrolysis of the difluoromethylene group to a carboxylic acid with concomitant loss of two fluoride ions and coenzyme conversion to pyridoxamine 5'-phosphate (PMP). The partition ratio for CPP-115 with GABA-AT is about 2000, releasing cyclopentanone-2,4-dicarboxylate (22) and two other precursors of this compound (20 and 21). Time-dependent inactivation occurs by a conformational change induced by the formation of the aldimine of 4-aminocyclopentane-1,3-dicarboxylic acid and PMP (20), which disrupts an electrostatic interaction between Glu270 and Arg445 to form an electrostatic interaction between Arg445 and the newly formed carboxylate produced by hydrolysis of the difluoromethylene group in CPP-115, resulting in a noncovalent, tightly bound complex. Ultimately, this represents a novel mechanism for inactivation of GABA-AT and a new approach for the design of mechanism-based inactivators in general.« less

  6. Seizures beget seizures: the quest for GABA as a key player.

    PubMed

    Ben-Ari, Yehezkel

    2006-01-01

    Synapses mediated by gamma-aminobutyric acid (GABA) A receptors are notoriously altered during periods of enhanced activity. Since a loss of inhibitory tone is a basic cause of seizures and epilepsies, it is important to determine the underlying mechanisms and the way this could be alleviated or at least reduced. Alterations of the intracellular content of chloride are thought to be a major player in the sequence of events that follow episodes of hyperactivity. In this review, I discuss these mechanisms both in the adult and developing brain, relying on studies in which chloride and GABAergic currents were measured by electrophysiological and imaging techniques. The main conclusion is that in adult systems, status epilepticus induces a complete re-organization of the networks, with cell death, axonal growth, and glutamatergic neosynapse formation leading to an increased glutamatergic drive. This, in turn, will decrease the threshold of seizure generation and thus contribute to seizure generation. In contrast, GABAergic synapses are not readily "plastic" as the lost interneurones and synapses are not replaced. Somatostatin-positive 0-LM Interneurons that innervate the dendrites of the principal cells in the hippocampus degenerate selectively, leading to a loss of the inhibitory drive in the dendrites, whereas somatic projecting basket cells and somatic inhibitory drives are relatively spared. This imbalance leads to a reduction of the inhibitory strength that is necessary but not sufficient to generate ongoing seizures. An additional important factor is the persistent increase of the intracellular chloride concentration that leads to a long-lasting shift in the depolarizing direction of the actions of GABA that will also contribute to seizure generation. In the developing brain, a major source of seizure generation is the depolarizing and often excitatory actions of GABA due to a higher intracellular chloride concentration ([Cl-]I) in immature neurons, a property

  7. Potent inhibitory effects of D-tagatose on the acid production and water-insoluble glucan synthesis of Streptococcus mutans GS5 in the presence of sucrose.

    PubMed

    Sawada, Daijo; Ogawa, Takaaki; Miyake, Minoru; Hasui, Yoshinori; Yamaguchi, Fuminori; Izumori, Ken; Tokuda, Masaaki

    2015-01-01

    We examined and compared the inhibitory effects of D-tagatose on the growth, acid production, and water-insoluble glucan synthesis of GS5, a bacterial strain of Streptococcus mutans, with those of xylitol, D-psicose, L-psicose and L-tagatose. GS5 was cultured for 12h in a medium containing 10% (w/v) of xylitol, D-psicose, L-psicose, D-tagatose or L-tagatose, and the inhibitory effect of GS5 growth was assessed. Each sugar showed different inhibitory effects on GS5. Both D-tagatose and xylitol significantly inhibited the acid production and water-insoluble glucan synthesis of GS5 in the presence of 1% (w/v) sucrose. However, the inhibitory effect of acid production by D-tagatose was significantly stronger than that of xylitol in presence of sucrose.

  8. 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

    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

  9. Brain GABA levels across psychiatric disorders: A systematic literature review and meta-analysis of (1) H-MRS studies.

    PubMed

    Schür, Remmelt R; Draisma, Luc W R; Wijnen, Jannie P; Boks, Marco P; Koevoets, Martijn G J C; Joëls, Marian; Klomp, Dennis W; Kahn, René S; Vinkers, Christiaan H

    2016-09-01

    The inhibitory gamma-aminobutyric acid (GABA) system is involved in the etiology of most psychiatric disorders, including schizophrenia, autism spectrum disorder (ASD) and major depressive disorder (MDD). It is therefore not surprising that proton magnetic resonance spectroscopy ((1) H-MRS) is increasingly used to investigate in vivo brain GABA levels. However, integration of the evidence for altered in vivo GABA levels across psychiatric disorders is lacking. We therefore systematically searched the clinical (1) H-MRS literature and performed a meta-analysis. A total of 40 studies (N = 1,591) in seven different psychiatric disorders were included in the meta-analysis: MDD (N = 437), schizophrenia (N = 517), ASD (N = 150), bipolar disorder (N = 129), panic disorder (N = 81), posttraumatic stress disorder (PTSD) (N = 104), and attention deficit/hyperactivity disorder (ADHD) (N = 173). Brain GABA levels were lower in ASD (standardized mean difference [SMD] = -0.74, P = 0.001) and in depressed MDD patients (SMD = -0.52, P = 0.005), but not in remitted MDD patients (SMD = -0.24, P = 0.310) compared with controls. In schizophrenia this finding did not reach statistical significance (SMD = -0.23, P = 0.089). No significant differences in GABA levels were found in bipolar disorder, panic disorder, PTSD, and ADHD compared with controls. In conclusion, this meta-analysis provided evidence for lower brain GABA levels in ASD and in depressed (but not remitted) MDD patients compared with healthy controls. Findings in schizophrenia were more equivocal. Even though future (1) H-MRS studies could greatly benefit from a longitudinal design and consensus on the preferred analytical approach, it is apparent that (1) H-MRS studies have great potential in advancing our understanding of the role of the GABA system in the pathogenesis of psychiatric disorders. Hum Brain Mapp 37:3337-3352, 2016. © 2016 Wiley Periodicals

  10. Influence of cold stress on contents of soluble sugars, vitamin C and free amino acids including gamma-aminobutyric acid (GABA) in spinach (Spinacia oleracea).

    PubMed

    Yoon, Young-Eun; Kuppusamy, Saranya; Cho, Kye Man; Kim, Pil Joo; Kwack, Yong-Bum; Lee, Yong Bok

    2017-01-15

    The contents of soluble sugars (sucrose, fructose, glucose, maltose and raffinose), vitamin C and free amino acids (34 compounds, essential and non-essential) were quantified in open-field and greenhouse-grown spinaches in response to cold stress using liquid chromatography. In general, greenhouse cultivation produced nutritionally high value spinach in a shorter growing period, where the soluble sugars, vitamin C and total amino acids concentrations, including essential were in larger amounts compared to those grown in open-field scenarios. Further, low temperature exposure of spinach during a shorter growth period resulted in the production of spinach with high sucrose, ascorbate, proline, gamma-aminobutyric acid, valine and leucine content, and these constitute the most important energy/nutrient sources. In conclusion, cultivation of spinach in greenhouse at a low temperature (4-7°C) and exposure for a shorter period (7-21days) before harvest is recommended. This strategy will produce a high quality product that people can eat.

  11. Activation of Presynaptic GABAB(1a,2) Receptors Inhibits Synaptic Transmission at Mammalian Inhibitory Cholinergic Olivocochlear–Hair Cell Synapses

    PubMed Central

    Wedemeyer, Carolina; Zorrilla de San Martín, Javier; Ballestero, Jimena; Gómez-Casati, María Eugenia; Torbidoni, Ana Vanesa; Fuchs, Paul A.; Bettler, Bernhard; Elgoyhen, Ana Belén

    2013-01-01

    The synapse between olivocochlear (OC) neurons and cochlear mechanosensory hair cells is cholinergic, fast, and inhibitory. The inhibitory sign of this cholinergic synapse is accounted for by the activation of Ca2+-permeable postsynaptic α9α10 nicotinic receptors coupled to the opening of hyperpolarizing Ca2+-activated small-conductance type 2 (SK2)K+ channels. Acetylcholine (ACh) release at this synapse is supported by both P/Q- and N-type voltage-gated calcium channels (VGCCs). Although the OC synapse is cholinergic, an abundant OC GABA innervation is present along the mammalian cochlea. The role of this neurotransmitter at the OC efferent innervation, however, is for the most part unknown. We show that GABA fails to evoke fast postsynaptic inhibitory currents in apical developing inner and outer hair cells. However, electrical stimulation of OC efferent fibers activates presynaptic GABAB(1a,2) receptors [GABAB(1a,2)Rs] that downregulate the amount of ACh released at the OC–hair cell synapse, by inhibiting P/Q-type VGCCs. We confirmed the expression of GABABRs at OC terminals contacting the hair cells by coimmunostaining for GFP and synaptophysin in transgenic mice expressing GABAB1–GFP fusion proteins. Moreover, coimmunostaining with antibodies against the GABA synthetic enzyme glutamic acid decarboxylase and synaptophysin support the idea that GABA is directly synthesized at OC terminals contacting the hair cells during development. Thus, we demonstrate for the first time a physiological role for GABA in cochlear synaptic function. In addition, our data suggest that the GABAB1a isoform selectively inhibits release at efferent cholinergic synapses. PMID:24068816

  12. In vitro inhibitory effect on pancreatic lipase activity of subfractions from ethanol extracts of fermented Oats (Avena sativa L.) and synergistic effect of three phenolic acids.

    PubMed

    Cai, Shengbao; Wang, Ou; Wang, Mengqian; He, Jianfeng; Wang, Yong; Zhang, Di; Zhou, Feng; Ji, Baoping

    2012-07-25

    The purpose of the present work is to study the pancreatic lipase inhibitory effects of different subfractions (n-hexane, ethyl acetate (EA), n-butanol, and water) from ethanol extracts of nonfermented and fungi-fermented oats and to delineate the interactions of three primary phenolic acids in the EA subfractions. The EA subfraction showed the highest inhibitory effect on pancreatic lipase activity at 1.5 mg/mL compared to the other subfractions, regardless of whether the oats were fermented. Meanwhile, both of the EA subfractions of two fungi-fermented oats demonstrated more effective inhibitory activity than that of nonfermented oats. A positive correlation between the total phenolics content and inhibitory activity was found. The inhibitory ability of the EA subfraction from nonfermented or fermented oats also displayed a dose-dependent effect. The standards of caffeic, ferulic, and p-coumaric acids, mainly included in EA subfractions of fermented oats, also displayed a dose-dependent inhibitory effect. A synergistic effect of each binary combination of p-coumaric, ferulic, and caffeic acids was observed, especially at 150.0 μg/mL. Those results indicate that fungi-fermented oats have a more effective inhibitory ability on pancreatic lipase and polyphenols may be the most effective component and could be potentially used for dietary therapy of obesity.

  13. In Vivo Effect of a 5-HT7 Receptor Agonist on 5-HT Neurons and GABA Interneurons in the Dorsal Raphe Nuclei of Sham and PD Rats.

    PubMed

    Wang, Shuang; Zhao, Yan; Gao, Jie; Guo, Yufang; Wang, Xiang; Huo, Jian; Wei, Ping; Cao, Jian

    2017-03-01

    The 5-hydroxytryptamine (5-HT; serotonin) neurotransmission is severely affected by the degeneration of nigrostriatal dopaminergic neurons. Here, we report the effects of the systemic administration of the 5-HT7 receptor agonist AS-19. In sham rats, the mean response of the 5-HT neurons in the dorsal raphe nucleus (DRN) to systemic AS-19 was excitatory and the mean response of the γ-aminobutyric acid (GABA) interneurons was inhibitory. In Parkinson disease (PD) rats, the same dose did not affect the 5-HT neurons and only high doses (640 μg/kg intravenous) were able to the increase GABA interneuron activity. These results indicate that DRN 5-HT neurons and GABA interneurons are regulated by the activation of 5-HT7 receptors and that the degeneration of the nigrostriatal pathway leads to decreased responses of these neurons to AS-19, which in turn suggests that the 5-HT7 receptors on 5-HT neurons and GABA interneurons in PD rats are dysfunctional and downregulated.

  14. Paradoxical effects of GABA-A modulators may explain sex steroid induced negative mood symptoms in some persons.

    PubMed

    Bäckström, T; Haage, D; Löfgren, M; Johansson, I M; Strömberg, J; Nyberg, S; Andréen, L; Ossewaarde, L; van Wingen, G A; Turkmen, S; Bengtsson, S K

    2011-09-15

    Some women have negative mood symptoms, caused by progestagens in hormonal contraceptives or sequential hormone therapy or by progesterone in the luteal phase of the menstrual cycle, which may be attributed to metabolites acting on the GABA-A receptor. The GABA system is the major inhibitory system in the adult CNS and most positive modulators of the GABA-A receptor (benzodiazepines, barbiturates, alcohol, GABA steroids), induce inhibitory (e.g. anesthetic, sedative, anticonvulsant, anxiolytic) effects. However, some individuals have adverse effects (seizures, increased pain, anxiety, irritability, aggression) upon exposure. Positive GABA-A receptor modulators induce strong paradoxical effects including negative mood in 3%-8% of those exposed, while up to 25% have moderate symptoms. The effect is biphasic: low concentrations induce an adverse anxiogenic effect while higher concentrations decrease this effect and show inhibitory, calming properties. The prevalence of premenstrual dysphoric disorder (PMDD) is also 3%-8% among women in fertile ages, and up to 25% have more moderate symptoms of premenstrual syndrome (PMS). Patients with PMDD have severe luteal phase-related symptoms and show changes in GABA-A receptor sensitivity and GABA concentrations. Findings suggest that negative mood symptoms in women with PMDD are caused by the paradoxical effect of allopregnanolone mediated via the GABA-A receptor, which may be explained by one or more of three hypotheses regarding the paradoxical effect of GABA steroids on behavior: (1) under certain conditions, such as puberty, the relative fraction of certain GABA-A receptor subtypes may be altered, and at those subtypes the GABA steroids may act as negative modulators in contrast to their usual role as positive modulators; (2) in certain brain areas of vulnerable women the transmembrane Cl(-) gradient may be altered by factors such as estrogens that favor excitability; (3) inhibition of inhibitory neurons may promote

  15. Hypertonicity enhances GABA uptake by cultured rat retinal capillary endothelial cells.

    PubMed

    Yahara, Tohru; Tachikawa, Masanori; Akanuma, Shin-ichi; Hosoya, Ken-ichi

    2010-01-01

    We have reported previously that taurine transporter (TauT) mediates γ-aminobutyric acid (GABA) as a substrate in a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB2 cells). This study investigates how TauT-mediated GABA transport is regulated in TR-iBRB2 cells under hypertonic conditions. [³H]GABA uptake by TR-iBRB2 cells exposed to 12 h- to 24 h-hypertonic culture medium was significantly greater than that of isotonic culture medium. [³H]GABA uptake by TR-iBRB2 cells was Na(+)-, Cl(-)-, and concentration-dependent with a Michaelis-Menten (K(m)) constant of 3.5 mM under isotonic conditions and K(m) of 0.324 and 5.48 mM under hypertonic conditions. Under hypertonic conditions, [³H]GABA uptake by TR-iBRB2 cells was more potently inhibited by substrates of TauT, such as taurine and β-alanine, than those of GABA transporters such as GABA, nipecotic acid, and betaine. These results suggest that an unknown high-affinity GABA transport process and TauT-mediated GABA transport are enhanced under hypertonic conditions. In conclusion, hypertonicity enhances GABA uptake by cultured rat retinal capillary endothelial cells.

  16. 2-Aminoethyl Methylphosphonate, a Potent and Rapidly Acting Antagonist of GABAA-ρ1 Receptors

    SciTech Connect

    Xie, A.; Yan, J.; Yue, L.; Feng, F.; Mir, F.; Abdel-Halim, H.; Chebib, M.; Le Breton, G. C.; Standaert, R. F.; Qian, H.; Pepperberg, D. R.

    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 Brown 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 differed

  17. In vivo electroretinographic studies of the role of GABAC receptors in retinal signal processing

    SciTech Connect

    Wang, Jing; Mojumder, Deb Kumar; Yan, Jun; Xie, An; Standaert, Robert F.; Qian, Haohua; Pepperberg, David R.; Frishman, Laura J.

    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. 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(C)R antagonists

  18. High saturated fatty acid intake induces insulin secretion by elevating gastric inhibitory polypeptide levels in healthy individuals.

    PubMed

    Itoh, Kazue; Moriguchi, Ririko; Yamada, Yuichiro; Fujita, Misuzu; Yamato, Takako; Oumi, Masayo; Holst, Jens Juul; Seino, Yutaka

    2014-08-01

    Insulin resistance is central to the etiology of the metabolic syndrome cluster of diseases. Evidence suggests that a high-fat diet is associated with insulin resistance, which may be modulated by dietary fatty acid composition. We hypothesized that high saturated fatty acid intake increases insulin and gastric inhibitory polypeptide (GIP) secretion. To clarify the effect of ingested fatty acid composition on glucose levels, we conducted an intervention study to investigate the insulin and plasma GIP responses in 11 healthy women, including a dietary control. Subjects were provided daily control meals (F-20; saturated fatty acids/monounsaturated fatty acids/polyunsaturated fatty acids [S/M/P] ratio, 3:4:3) with 20 energy (E) % fat, followed by 2 isoenergetic experimental meals for 7 days each. These meals comprised 60 E% carbohydrate, 15 E% protein, and 30 E% fat (FB-30; high saturated fatty acid meal; S/M/P, 5:4:1; F-30: reduced saturated fatty acid meal; S/M/P, 3:4:3). On the second day of the F-20 and the last day of F-30 and FB-30, blood samples were taken before and 30, 60, and 120 minutes after a meal tolerance test. The plasma glucose responses did not differ between F-20 and FB-30 or F-30. However, insulin levels were higher after the FB-30 than after the F-20 (P < .01). The GIP response after the FB-30 was higher than that after the F-30 (P < .05). In addition, the difference in the incremental GIP between FB-30 and F-30 correlated significantly and positively with that of the insulin. These results suggest that a high saturated fatty acid content stimulates postprandial insulin release via increased GIP secretion.

  19. The GABA-synthetic enzyme GAD65 controls circadian activation of conditioned fear pathways.

    PubMed

    Bergado-Acosta, Jorge R; Müller, Iris; Richter-Levin, Gal; Stork, Oliver

    2014-03-01

    Circadian fluctuations of fear and anxiety symptoms are observable in persons with post-traumatic stress disorder, generalized anxiety, and panic disorder; however, the underlying neurobiological mechanisms are not sufficiently understood. In the present study, we investigated the putative role of inhibitory neurotransmission in the circadian fluctuation of fear symptoms, using mice with genetic ablation of the γ-amino butyric acid (GABA) synthesizing isoenzyme, glutamic acid decarboxylase GAD65. We observed in these mutant mice an altered expression of conditioned fear with a profound reduction of freezing, and an increase of hyperactivity bouts occurring only when both fear conditioning training and retrieval testing were done at the beginning of their active phase. Mutants further showed an increased arousal response at this time of the day, although, circadian rhythm of home cage activity was unaltered. Hyperactivity and reduced freezing during fear memory retrieval were accompanied by an increased induction of the immediate early gene cFos suggesting hyperactivation of the hippocampus, amygdala, and medial hypothalamus. Our data suggest a role of GAD65-mediated GABA synthesis in the encoding of circadian information to fear memory. GAD65 deficits in a state-dependent manner result in increased neural activation in fear circuits and elicit panic-like flight responses during fear memory retrieval.

  20. Inhibitory pathways and the inhibition of luteinizing hormone-releasing hormone release by alcohol

    PubMed Central

    Lomniczi, Alejandro; Mastronardi, Claudio A.; Faletti, Alicia G.; Seilicovich, Adriana; De Laurentiis, Andrea; McCann, Samuel M.; Rettori, Valeria

    2000-01-01

    In this research we examined the mechanisms by which ethanol (EtOH) inhibits luteinizing hormone-releasing hormone (LHRH) release from incubated medial basal hypothalamic explants. EtOH (100 mM) stimulated the release of two inhibitory neurotransmitters: γ-aminobutyric acid (GABA) and β-endorphin. EtOH also inhibited NO production, indicative of a suppression of nitric oxide synthase (NOS) activity. This inhibition was reversed by naltroxone (10−8 M), a μ-opioid receptor blocker, indicating that the inhibition of NOS by EtOH is mediated by β-endorphin. EtOH also blocked N-methyl-d-aspartic acid-induced LHRH release, but the blockade could not be reversed by either the GABA receptor blocker, bicuculline (10−5 M), naltroxone (10−8 M), or both inhibitors added together. However, increasing the concentration of naltrexone (10−6 M) but not bicuculline (10−4 M) reversed the inhibition. When we lowered the concentration of EtOH (50 mM), the EtOH-induced blockade of LHRH release could be reversed by either bicuculline (10−5 M), naltroxone (10−8 M), or the combination of the two blockers. Therefore, GABA is partially responsible for the blockade of N-methyl-d-aspartic acid-induced LHRH release. The block by GABA was exerted by inhibiting the activation of cyclooxygenase by NO, because it was reversed by prostaglandin E2, the product of activation of cyclooxygenase. Because the inhibition caused by the higher concentration of EtOH could not be reduced by bicuculline (10−4 M) but was blocked by naltroxone (10−6 M), the action of alcohol can be accounted for by stimulation of β-endorphin neurons that inhibit LHRH release by inhibition of activation of NOS and stimulation of GABA release. PMID:10688896

  1. Evidence for a Revised Ion/Substrate Coupling Stoichiometry of GABA Transporters.

    PubMed

    Willford, Samantha L; Anderson, Cynthia M; Spencer, Shelly R; Eskandari, Sepehr

    2015-08-01

    Plasma membrane γ-aminobutyric acid (GABA) transporters (GATs) are electrogenic transport proteins that couple the cotranslocation of Na(+), Cl(-), and GABA across the plasma membrane of neurons and glia. A fundamental property of the transporter that determines its ability to concentrate GABA in cells and, hence, regulate synaptic and extra-synaptic GABA concentrations, is the ion/substrate coupling stoichiometry. Here, we scrutinized the currently accepted 2 Na(+):1 Cl(-):1 GABA stoichiometry because it is inconsistent with the measured net charge translocated per co-substrate (Na(+), Cl(-), and GABA). We expressed GAT1 and GAT3 in Xenopus laevis oocytes and utilized thermodynamic and uptake under voltage-clamp measurements to determine the stoichiometry of the GABA transporters. Voltage-clamped GAT1-expressing oocytes were internally loaded with GABA, and the reversal potential (V rev) of the transporter-mediated current was recorded at different external concentrations of Na(+), Cl(-), or GABA. The shifts in V rev for a tenfold change in the external Na(+), Cl(-), and GABA concentration were 84 ± 4, 30 ± 1, and 29 ± 1 mV, respectively. To determine the net charge translocated per Na(+), Cl(-), and GABA, we measured substrate fluxes under voltage clamp in cells expressing GAT1 or GAT3. Charge flux to substrate flux ratios were 0.7 ± 0.1 charge/Na(+), 2.0 ± 0.2 charges/Cl(-), and 2.1 ± 0.1 charges/GABA. Altogether, our results strongly suggest a 3 Na(+):1 Cl(-):1 GABA coupling stoichiometry for the GABA transporters. The revised stoichiometry has important implications for understanding the contribution of GATs to GABAergic signaling in health and disease.

  2. Synthesis and carbonic anhydrase inhibitory properties of amino acid - coumarin/quinolinone conjugates incorporating glycine, alanine and phenylalanine moieties.

    PubMed

    Küçükbay, F Zehra; Küçükbay, Hasan; Tanc, Muhammet; Supuran, Claudiu T

    2016-12-01

    N-Protected amino acids (Gly, Ala and Phe) were reacted with amino substituted coumarin and quinolinone derivatives, leading to the corresponding N-protected amino acid-coumarin/quinolinone conjugates. The carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity of the new compounds was assessed against various human (h) isoforms, such as hCA I, hCA II, hCA IV and hCA XII. The quinolinone conjugates were inactive as enzyme inhibitors, whereas the coumarins were ineffective hCA I/II inhibitors (KIs > 50 μM) but were submicromolar hCA IV and XII inhibitors, with inhibition constants ranging between 92 nM and 1.19 μM for hCA IV, and between 0.11 and 0.79 μM for hCA XII. These coumarin derivatives, as many others reported earlier, thus show an interesting selective inhibitory profile for the membrane-bound over the cytosolic CA isoforms.

  3. Inhibitory effect of ciprofloxacin on β-glucuronidase-mediated deconjugation of mycophenolic acid glucuronide.

    PubMed

    Kodawara, Takaaki; Masuda, Satohiro; Yano, Yoshitaka; Matsubara, Kazuo; Nakamura, Toshiaki; Masada, Mikio

    2014-07-01

    The interaction between mycophenolate (MPA) and quinolone antibiotics such as ciprofloxacin is considered to reduce the enterohepatic recycling of MPA, which is biotransformed in the intestine from MPA glucuronide (MPAG) conjugate excreted via the biliary system; however, the molecular mechanism underlying this biotransformation of MPA is still unclear. In this study, an in vitro system was established to evaluate β-glucuronidase-mediated deconjugation and to examine the influence of ciprofloxacin on the enzymatic deconjugation of MPAG and MPA resynthesis. Resynthesis of MPA via deconjugation of MPAG increased in a time-dependent manner from 5 to 60 min in the presence of β-glucuronidase. Ciprofloxacin and phenolphthalein-β-d-glucuronide (PhePG), a typical β-glucuronidase substrate, significantly decreased the production of MPA from MPAG in the β-glucuronidase-mediated deconjugation system. In addition, enoxacin significantly inhibited the production of MPA from MPAG, while levofloxacin and ofloxacin had no inhibitory effect on MPA synthesis. Pharmacokinetic analysis revealed that ciprofloxacin showed a dose-dependent inhibitory effect on MPA production from MPAG via β-glucuronidase with a half-maximal inhibitory concentration (IC50 ) value of 30.4 µm. While PhePG inhibited the β-glucuronidase-mediated production of MPA from MPAG in a competitive manner, ciprofloxacin inhibited MPA synthesis via noncompetitive inhibition. These findings suggest that the reduction in the serum MPA concentration during the co-administration of ciprofloxacin is at least in part due to the decreased enterohepatic circulation of MPA because of noncompetitive inhibition of deconjugation of MPAG by intestinal β-glucuronidase.

  4. Activation of metabotropic GABA receptors increases the energy barrier for vesicle fusion.

    PubMed

    Rost, Benjamin R; Nicholson, Patrick; Ahnert-Hilger, Gudrun; Rummel, Andreas; Rosenmund, Christian; Breustedt, Joerg; Schmitz, Dietmar

    2011-09-15

    Neurotransmitter release from presynaptic terminals is under the tight control of various metabotropic receptors. We report here that in addition to the regulation of Ca(2+) channel activity, metabotropic GABA(B) receptors (GABA(B)Rs) at murine hippocampal glutamatergic synapses utilize an inhibitory pathway that directly targets the synaptic vesicle release machinery. Acute application of the GABA(B)R agonist baclofen rapidly and reversibly inhibits vesicle fusion, which occurs independently of the SNAP-25 C-terminus. Using applications of hypertonic sucrose solutions, we find that the size of the readily releasable pool remains unchanged by GABA(B)R activation, but the sensitivity of primed vesicles to hypertonic stimuli appears lowered as the response amplitudes at intermediate sucrose concentrations are smaller and release kinetics are slowed. These data show that presynaptic GABA(B)Rs can inhibit neurotransmitter release directly by increasing the energy barrier for vesicle fusion.

  5. Comparing GABA-dependent physiological measures of inhibition with proton magnetic resonance spectroscopy measurement of GABA using ultra-high-field MRI.

    PubMed

    Dyke, Katherine; Pépés, Sophia E; Chen, Chen; Kim, Soyoung; Sigurdsson, Hilmar P; Draper, Amelia; Husain, Masud; Nachev, Parashkev; Gowland, Penelope A; Morris, Peter G; Jackson, Stephen R

    2017-03-09

    Imbalances in glutamatergic (excitatory) and GABA (inhibitory) signalling within key brain networks are thought to underlie many brain and mental health disorders, and for this reason there is considerable interest in investigating how individual variability in localised concentrations of these molecules relate to brain disorders. Magnetic resonance spectroscopy (MRS) provides a reliable means of measuring, in vivo, concentrations of neurometabolites such as GABA, glutamate and glutamine that can be correlated with brain function and dysfunction. However, an issue of much debate is whether the GABA observed and measured using MRS represents the entire pool of GABA available for measurement (i.e., metabolic, intracellular, and extracellular) or is instead limited to only some portion of it. GABA function can also be investigated indirectly in humans through the use of non-invasive transcranial magnetic stimulation (TMS) techniques that can be used to measure cortical excitability and GABA-mediated physiological inhibition. To investigate this issue further we collected in a single session both types of measurement, i.e., TMS measures of cortical excitability and physiological inhibition and ultra-high-field (7 T) MRS measures of GABA, glutamate and glutamine, from the left sensorimotor cortex of the same group of right-handed individuals. We found that TMS and MRS measures were largely uncorrelated with one another, save for the plateau of the TMS IO curve that was negatively correlated with MRS-Glutamate (Glu) and intra-cortical facilitation (10ms ISI) that was positively associated with MRS-Glutamate concentration. These findings are consistent with the view that the GABA concentrations measured using the MRS largely represent pools of GABA that are linked to tonic rather than phasic inhibition and thus contribute to the inhibitory tone of a brain area rather than GABAergic synaptic transmission.

  6. Pressure-Dependent Changes in the Release of GABA by Cerebrocortical Synaptosomes

    DTIC Science & Technology

    1989-01-01

    DTICL9? Undersea Biomedical Research, Vol. 16, No. 3. 1989 N V918f, NOV09198 B U Pressure-dependent changes in the release of GABA 1 by...Center, Bothesda. Maryland 20814-5055 Gilman SC, Colton JS, Dutka AJ. Pressure-dependent changes in the release of GABA by cerebrocortical synaptosomes...evoked [3H]--aminobutyric acid ( GABA ) release from isolated presynaptic terminals (synaptosomes) (15, 16). The current study was designed to evaluate

  7. GABA Signaling and Neuroactive Steroids in Adrenal Medullary Chromaffin Cells

    PubMed Central

    Harada, Keita; Matsuoka, Hidetada; Fujihara, Hiroaki; Ueta, Yoichi; Yanagawa, Yuchio; Inoue, Masumi

    2016-01-01

    Gamma-aminobutyric acid (GABA) is produced not only in the brain, but also in endocrine cells by the two isoforms of glutamic acid decarboxylase (GAD), GAD65 and GAD67. In rat adrenal medullary chromaffin cells only GAD67 is expressed, and GABA is stored in large dense core vesicles (LDCVs), but not synaptic-like microvesicles (SLMVs). The α3β2/3γ2 complex represents the majority of GABAA receptors expressed in rat and guinea pig chromaffin cells, whereas PC12 cells, an immortalized rat chromaffin cell line, express the α1 subunit as well as the α3. The expression of α3, but not α1, in PC12 cells is enhanced by glucocorticoid activity, which may be mediated by both the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). GABA has two actions mediated by GABAA receptors in chromaffin cells: it induces catecholamine secretion by itself and produces an inhibition of synaptically evoked secretion by a shunt effect. Allopregnanolone, a neuroactive steroid which is secreted from the adrenal cortex, produces a marked facilitation of GABAA receptor channel activity. Since there are no GABAergic nerve fibers in the adrenal medulla, GABA may function as a para/autocrine factor in the chromaffin cells. This function of GABA may be facilitated by expression of the immature isoforms of GAD and GABAA receptors and the lack of expression of plasma membrane GABA transporters (GATs). In this review, we will consider how the para/autocrine function of GABA is achieved, focusing on the structural and molecular mechanisms for GABA signaling. PMID:27147972

  8. Dynamic changes in gamma-aminobutyric acid and glutamate decarboxylase activity in oats (Avena nuda L.) during steeping and germination.

    PubMed

    Xu, Jian Guo; Hu, Qing Ping; Duan, Jiang Lian; Tian, Cheng Rui

    2010-09-08

    Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the central nervous system and provides beneficial effects for human and other animals health. To accumulate GABA, samples from two different naked oat cultivars, Baiyan II and Bayou I, were steeped and germinated in an incubator. The content of GABA and glutamic acid as well as the activity of the glutamate decarboxylase (GAD) in oats during steeping and germination were investigated with an amino acid automatic analyzer. Compared with raw groats, an increase in GABA content of oat groats during steeping and germination was continuously observed for two oat cultivars. The activity of GAD increased greatly at the end of steeping and the second stage of germination for Baiyan II and Bayou I, respectively. Glutamic acid content of treated oat groats was significantly lower than that in raw groats until the later period of germination. GABA was correlated (p<0.01) significantly and positively with the glutamic acid rather than GAD activity in the current study. The results indicates that steeping and germination process under highly controlled conditions can effectively accumulate the GABA in oat groats for Baiyan II and Bayou I, which would greatly facilitate production of nutraceuticals or food ingredients that enable consumers to gain greater access to the health benefits of oats. However, more assays need to be further performed with more oat cultivars.

  9. 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.

  10. Presynaptic kainate receptors that enhance the release of GABA on CA1 hippocampal interneurons.

    PubMed

    Cossart, R; Tyzio, R; Dinocourt, C; Esclapez, M; Hirsch, J C; Ben-Ari, Y; Bernard, C

    2001-02-01

    We report that kainate receptors are present on presynaptic GABAergic terminals contacting interneurons and that their activation increases GABA release. Application of kainate increased the frequency of miniature inhibitory postsynaptic currents recorded in CA1 interneurons. Local applications of glutamate but not of AMPA or NMDA also increased GABA quantal release. Application of kainate as well as synaptically released glutamate reduced the number of failures of GABAergic neurotransmission between interneurons. Thus, activation of presynaptic kainate receptors increases the probability of GABA release at interneuron-interneuron synapses. Glutamate may selectively control the communication between interneurons by increasing their mutual inhibition.

  11. Regulation of GABA and benzodiazepine receptors following neurotoxin-induced striatal and medial forebrain bundle lesions

    SciTech Connect

    Pan, H.S.I.

    1985-01-01

    GABA, a major inhibitory transmitter, is used by many projection neurons of the striatum. To investigate the role of GABA in striatal function, the GABA receptor complex was studied after lesions of the striatum or the nigrostriatal neurons. Quantitative receptor autoradiography using thaw-mounted tissue slices was developed for the study of GABA and benzodiazepine (BDZ) receptors. With the technique established, binding to GABA and BDZ receptors after unilateral striatal kainate lesions was examined. Subsequently, changes in GABA and BDZ receptors were studied following the destruction of dopaminergic nigrostriatal cells by unilateral 6-hydroxydopamine lesion of the medial forebrain bundle. In summary, quantitative receptor autoradiography allowed the detection of GABA and BDZ receptor changes in multiple small areas in each lesioned brain. This technique made it feasible to carry out kinetic saturation, and competition studies using less than 1 mg of tissue. The data suggest that dopamine is functionally inhibitory on striatopallidal neurons but is functionally excitatory on striatoentopeduncular and striatonigral cells which in turn inhibit the thalamus. This quantitative autoradiographic technique can be generalized to study other transmitter receptors and can be combined with 2-deoxyglucose uptake studies.

  12. Contribution of metabotropic GABA(B) receptors to neuronal network construction.

    PubMed

    Gaiarsa, Jean-Luc; Kuczewski, Nicola; Porcher, Christophe

    2011-11-01

    In the 1980s, Bowery and colleagues discovered the presence of a novel, bicuculline-resistant and baclofen-sensitive type of GABA receptor on peripheral nerve terminals, the GABA(B) receptor. Since this pioneering work, GABA(B) receptors have been identified in the Central Nervous System (CNS), where they provide an important inhibitory control of postsynaptic excitability and presynaptic transmitter release. GABA(B) receptors have been implicated in a number of important processes in the adult brain such as the regulation of synaptic plasticity and modulation of rhythmic activity. As a result of these studies, several potential therapeutic applications of GABA(B) receptor ligands have been identified. Recent advances have further shown that GABA(B) receptors play more than a classical inhibitory role in adult neurotransmission, and can in fact function as an important developmental signal early in life. Here we summarize current knowledge on the contribution of GABA(B) receptors to the construction and function of developing neuronal networks.

  13. Abnormal relationship between GABA, neurophysiology and impulsive behavior in neurofibromatosis type 1.

    PubMed

    Ribeiro, Maria J; Violante, Inês R; Bernardino, Inês; Edden, Richard A E; Castelo-Branco, Miguel

    2015-03-01

    Neurofibromatosis type 1 (NF1) is a neurodevelopmental disorder characterized by a broad spectrum of cognitive deficits. In particular, executive dysfunction is recognized as a core deficit of NF1, including impairments in executive attention and inhibitory control. Yet, the neural mechanisms behind these important deficits are still unknown. Here, we studied inhibitory control in a visual go/no-go task in children and adolescents with NF1 and age- and gender-matched controls (n = 16 per group). We applied a multimodal approach using high-density electroencephalography (EEG), to study the evoked brain responses, and magnetic resonance spectroscopy (MRS) to measure the levels of GABA and glutamate + glutamine in the medial frontal cortex, a brain region that plays a pivotal role in inhibitory control, and also in a control region, the occipital cortex. Finally, we run correlation analyses to identify the relationship between inhibitory control, levels of neurotransmitters, and EEG markers of neural function. Individuals with NF1 showed impaired impulse control and reduced EEG correlates of early visual processing (parieto-occipital P1) and inhibitory control (frontal P3). MRS data revealed a reduction in medial frontal GABA+/tCr (total Creatine) levels in the NF1 group, in parallel with the already reported reduced occipital GABA levels. In contrast, glutamate + glutamine/tCr levels were normal, suggesting the existence of abnormal inhibition/excitation balance in this disorder. Notably, medial frontal but not occipital GABA levels correlated with general intellectual abilities (IQ) in NF1, and inhibitory control in both groups. Surprisingly, the relationship between inhibitory control and medial frontal GABA was reversed in NF1: higher GABA was associated with a faster response style whereas in controls it was related to a cautious strategy. Abnormal GABAergic physiology appears, thus, as an important factor underlying impaired cognition in NF1, in a level and

  14. GAD67 deficiency in parvalbumin interneurons produces deficits in inhibitory transmission and network disinhibition in mouse prefrontal cortex.

    PubMed

    Lazarus, Matthew S; Krishnan, Keerthi; Huang, Z Josh

    2015-05-01

    In mammalian neocortex, the delicate balance of neural circuits is regulated by a rich repertoire of inhibitory control mechanisms mediated by diverse classes of GABAergic interneurons. A key step common to all GABAergic neurons is the synthesis of GABA, catalyzed by 2 isoforms of glutamic acid decarboxylases (GAD). Among these, GAD67 is the rate-limiting enzyme. GAD67 level is regulated by neural activity and is altered in multiple neuropsychiatric disorders. The significance of altered GAD67 levels on inhibitory transmission, however, remains unclear. The presence of GAD65, postsynaptic GABA receptor regulation, and the diversity of cortical interneurons make the link from GAD67 levels to GABA transmission less than straightforward. Here, we selectively removed one allele of the GAD67 gene, Gad1, in PV interneurons in juvenile mice. We found substantial deficits in transmission from PV to pyramidal neurons in prefrontal cortex, along with increases of pyramidal cell excitability and excitation/inhibition balance in PV cells. Synaptic deficits recovered in adult mice, suggesting engagement of homeostatic and compensatory mechanisms. These results demonstrate that GAD67 levels directly influence synaptic inhibition. Thus, GAD67 deficiency in PV cells likely contributes to cortical dysfunction in disease states; the reversibility of synaptic deficits suggests nonpermanent damage to inhibitory circuitry.

  15. Mechanism of Inactivation of γ-Aminobutyric Acid Aminotransferase by (1S ,3S)-3-Amino-4-difluoromethylene-1-cyclopentanoic Acid (CPP-115)

    SciTech Connect

    Lee, Hyunbeom; Doud, Emma H.; Wu, Rui; Sanishvili, Ruslan; Juncosa, Jose I.; Liu, Dali; Kelleher, Neil L.; Silverman, Richard B.

    2015-01-23

    γ-Aminobutyric acid aminotransferase (GABA-AT) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that degrades GABA, the principal inhibitory neurotransmitter in mammalian cells. When the concentration of GABA falls below a threshold level, convulsions can occur. Inhibition of GABA-AT raises GABA levels in the brain, which can terminate seizures as well as have potential therapeutic applications in treating other neurological disorders, including drug addiction. Among the analogues that we previously developed, (1S,3S)-3-amino-4-difluoromethylene-1-cyclopentanoic acid (CPP-115) showed 187 times greater potency than that of vigabatrin, a known inactivator of GABA-AT and approved drug (Sabril) for the treatment of infantile spasms and refractory adult epilepsy. Recently, CPP-115 was shown to have no adverse effects in a Phase I clinical trial. Here we report a novel inactivation mechanism for CPP-115, a mechanism-based inactivator that undergoes GABA-AT-catalyzed hydrolysis of the difluoromethylene group to a carboxylic acid with concomitant loss of two fluoride ions and coenzyme conversion to pyridoxamine 5'-phosphate (PMP). The partition ratio for CPP-115 with GABA-AT is about 2000, releasing cyclopentanone-2,4-dicarboxylate (22) and two other precursors of this compound (20 and 21). Time-dependent inactivation occurs by a conformational change induced by the formation of the aldimine of 4-aminocyclopentane-1,3-dicarboxylic acid and PMP (20), which disrupts an electrostatic interaction between Glu270 and Arg445 to form an electrostatic interaction between Arg445 and the newly formed carboxylate produced by hydrolysis of the difluoromethylene group in CPP-115, resulting in a noncovalent, tightly bound complex. Ultimately, this represents a novel mechanism for inactivation of GABA-AT and a new approach for the design of mechanism-based inactivators in general.

  16. Intestinal transport of zinc and folic acid: a mutual inhibitory effect

    SciTech Connect

    Ghishan, F.K.; Said, H.M.; Wilson, P.C.; Murrell, J.E.; Greene, H.L.

    1986-02-01

    Recent observations suggest an inverse relationship between folic acid intake and zinc nutriture and indicate an interaction between folic acid and zinc at the intestinal level. To define that interaction, we designed in vivo and in vitro transport studies in which folic acid transport in the presence of zinc, as well as zinc transport in the presence of folic acid was examined. These studies show that zinc transport is significantly decreased when folate is present in the intestinal lumen. Similarly folic acid transport is significantly decreased with the presence of zinc. To determine whether this intestinal inhibition is secondary to zinc and folate-forming complexes, charcoal-binding studies were performed. These studies indicate that zinc and folate from complexes at pH 2.0, but that at pH 6.0, these complexes dissolve. Therefore, our studies suggest that under normal physiological conditions a mutual inhibition between folate and zinc exists at the site of intestinal transport.

  17. Selective inhibitory effects of niflumic acid on 5-HT-induced contraction of the rat isolated stomach fundus.

    PubMed

    Scarparo, H C; Santos, G C; Leal-Cardoso, J H; Criddle, D N

    2000-06-01

    The effects of niflumic acid (NFA), an inhibitor of calcium-activated chloride currents I(Cl(Ca)), were compared with the actions of the voltage-dependent calcium channel (VDCC) blocker nifedipine on 5-hydroxtryptamine (5-HT)- and acetylcholine (ACh)-induced contractions of the rat isolated fundus. NFA (1 - 30 microM) elicited a concentration-dependent inhibition of contractions induced by 5-HT (10 microM) with a reduction to 15. 5+/-6.0% of the control value at 30 microM. 1 microM nifedipine reduced 5-HT-induced contraction to 15.2+/-4.9% of the control, an effect not greater in the additional presence of 30 microM NFA. In contrast, the contractile response to ACh (10 microM) was not inhibited by NFA in concentrations acid and 4, 4'-diisothiocyanatostilbene-2,2'-disulphonic acid were less selective in their inhibitory effects, inducing reductions of 60 mM KCl-induced contraction at concentrations >/=10 microM. Our results show that NFA can exert selective inhibitory effects on the chloride-dependent 5-HT-induced contractions of the rat fundus. The data support the hypothesis that activation of Cl((Ca)) channels leading to calcium entry via VDCCs is a mechanism utilized by 5-HT, but not by ACh, to elicit contraction of the rat fundus.

  18. 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

  19. Inhibition of recombinant N-type and native high voltage-gated neuronal Ca{sup 2+} channels by AdGABA: Mechanism of action studies

    SciTech Connect

    Martinez-Hernandez, Elizabeth; Sandoval, Alejandro; Gonzalez-Ramirez, Ricardo; Zoidis, Grigoris; Felix, Ricardo

    2011-02-01

    High-voltage activated Ca{sup 2+} (Ca{sub V}) channels play a key role in the regulation of numerous physiological events by causing transient changes in the intracellular Ca{sup 2+} concentration. These channels consist of a pore-forming Ca{sub V}{alpha}{sub 1} protein and three auxiliary subunits (Ca{sub V}{beta}, Ca{sub V}{alpha}{sub 2}{delta} and Ca{sub V}{gamma}). Ca{sub V}{alpha}{sub 2}{delta} is an important component of Ca{sub V} channels in many tissues and of great interest as a drug target. It is well known that anticonvulsant agent gabapentin (GBP) binds to Ca{sub V}{alpha}{sub 2}{delta} and reduces Ca{sup 2+} currents by modulating the expression and/or function of the Ca{sub V}{alpha}{sub 1} subunit. Recently, we showed that an adamantane derivative of GABA, AdGABA, has also inhibitory effects on Ca{sub V} channels. However, the importance of the interaction of AdGABA with the Ca{sub V}{alpha}{sub 2}{delta} subunit has not been conclusively demonstrated and the mechanism of action of the drug has yet to be elucidated. Here, we describe studies on the mechanism of action of AdGABA. Using a combined approach of patch-clamp recordings and molecular biology we show that AdGABA inhibits Ca{sup 2+} currents acting on Ca{sub V}{alpha}{sub 2}{delta} only when applied chronically, both in a heterologous expression system and in dorsal root-ganglion neurons. AdGABA seems to require uptake and be acting intracellularly given that its effects are prevented by an inhibitor of the L-amino acid transport system. Interestingly, a mutation in the Ca{sub V}{alpha}{sub 2}{delta} that abolishes GBP binding did not affect AdGABA actions, revealing that its mechanism of action is similar but not identical to that of GBP. These results indicate that AdGABA is an important Ca{sub V}{alpha}{sub 2}{delta} ligand that regulates Ca{sub V} channels.

  20. Novel chemical synthesis of ginkgolic acid (13:0) and evaluation of its tyrosinase inhibitory activity.

    PubMed

    Fu, Yuanqing; Hong, Shan; Li, Duo; Liu, Songbai

    2013-06-05

    A novel efficient synthesis of ginkgolic acid (13:0) from abundant 2,6-dihydroxybenzoic acid was successfully developed through a state-of-the-art palladium-catalyzed cross-coupling reaction and catalytic hydrogenation with an overall yield of 34% in five steps. The identity of the synthesized ginkgolic acid (13:0) was confirmed by nuclear magnetic resonance, mass spectrometry, infrared, and high-performance liquid chromatography. The reaction sequence of this method can be readily extended to the synthesis of other ginkgolic acids. The synthesized ginkgolic acid (13:0) exhibited promising anti-tyrosinase activity (IC₅₀ = 2.8 mg/mL) that was not correlated to antioxidant activity as probed by 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ferric reducing ability of plasma, and oxygen radical absorbance capacity assays. The synthetic strategy developed in this work will significantly facilitate biological studies of ginkgolic acids that have great potential applications in food and pharmaceuticals.

  1. Ketosis and brain handling of glutamate, glutamine, and GABA.

    PubMed

    Yudkoff, Marc; Daikhin, Yevgeny; Horyn, Oksana; Nissim, Ilana; Nissim, Itzhak

    2008-11-01

    We hypothesize that one mechanism of the anti-epileptic effect of the ketogenic diet is to alter brain handling of glutamate. According to this formulation, in ketotic brain astrocyte metabolism is more active, resulting in enhanced conversion of glutamate to glutamine. This allows for: (a) more efficient removal of glutamate, the most important excitatory neurotransmitter; and (b) more efficient conversion of glutamine to GABA, the major inhibitory neurotransmitter.

  2. α-Glucosidase inhibitory activities of fatty acids purified from the internal organ of sea cucumber Stichopus japonicas.

    PubMed

    Nguyen, T H; Kim, S M

    2015-04-01

    α-Glucosidase inhibitory activities of the various solvent fractions (n-hexane, CHCl3 , EtOAc, BuOH, and water) of sea cucumber internal organ were investigated. 1,3-Dipalmitolein (1) and cis-9-octadecenoic acid (2) with potent α-glucosidase inhibitory activity were purified from the n-hexane fraction of sea cucumber internal organ. IC50 values of compounds 1 and 2 were 4.45 and 14.87 μM against Saccharomyces cerevisiae α-glucosidase. These compounds mildly inhibited rat-intestinal α-glucosidase. In addition, both compounds showed a mixed competitive inhibition against S. cerevisiae α-glucosidase and were very stable at pH 2 up to 60 min. The KI values of compounds 1 and 2 were 0.48 and 1.24 μM, respectively. Therefore, the internal organ of sea cucumber might be a potential new source of α-glucosidase inhibitors suitably used for prevention of obesity and diabetes mellitus.

  3. 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.

  4. Characterization of gamma-aminobutyric acid receptors in the neurointermediate lobe of the amphibian Xenopus laevis.

    PubMed

    Verburg-van Kemenade, B M; Jenks, B G; Lenssen, F J; Vaudry, H

    1987-02-01

    The neurotransmitter gamma-aminobutyric acid (GABA) is involved in the regulation of secretion of MSH from the intermediate lobe of Xenopus laevis. The purpose of this study was to identify the GABA receptor(s) involved by determination of the effect of specific receptor agonists and antagonists on the release of immunoreactive MSH from superfused neurointermediate lobes of Xenopus. Exogenous GABA induces a rapid inhibition of MSH secretion. There was no evidence for a transitory stimulatory effect of GABA as reported for the rat melanotropes. Both the GABA agonists (GABAa) homotaurine and isoguvacine and the GABA agonist (GABAb) baclofen inhibited MSH release in a dose-dependent manner. In vivo, homotaurine and baclofen caused aggregation of pigment in dermal melanophores. The MSH release-inhibiting effect of homotaurine and isoguvacine could be antagonized by the specific GABAa receptor antagonist bicuculline. However, bicuculline and picrotoxin failed to block the effect of exogenous GABA. We conclude that in the neurointermediate lobe of Xenopus laevis both GABAa and GABAb receptors are present, suggesting a dual inhibitory regulation.

  5. Waking action of ursodeoxycholic acid (UDCA) involves histamine and GABAA receptor block.

    PubMed

    Yanovsky, Yevgenij; Schubring, Stephan R; Yao, Quiaoling; Zhao, Yan; Li, Sha; May, Andrea; Haas, Helmut L; Lin, Jian-Sheng; Sergeeva, Olga A

    2012-01-01

    Since ancient times ursodeoxycholic acid (UDCA), a constituent of bile, is used against gallstone formation and cholestasis. A neuroprotective action of UDCA was demonstrated recently in models of Alzheimer's disease and retinal degeneration. The mechanisms of UDCA action in the nervous system are poorly understood. We show now that UDCA promotes wakefulness during the active period of the day, lacking this activity in histamine-deficient mice. In cultured hypothalamic neurons UDCA did not affect firing rate but synchronized the firing, an effect abolished by the GABA(A)R antagonist gabazine. In histaminergic neurons recorded in slices UDCA reduced amplitude and duration of spontaneous and evoked IPSCs. In acutely isolated histaminergic neurons UDCA inhibited GABA-evoked currents and sIPSCs starting at 10 µM (IC(50) = 70 µM) and did not affect NMDA- and AMPA-receptor mediated currents at 100 µM. Recombinant GABA(A) receptors composed of α1, β1-3 and γ2L subunits expressed in HEK293 cells displayed a sensitivity to UDCA similar to that of native GABA(A) receptors. The mutation α1V256S, known to reduce the inhibitory action of pregnenolone sulphate, reduced the potency of UDCA. The mutation α1Q241L, which abolishes GABA(A)R potentiation by several neurosteroids, had no effect on GABA(A)R inhibition by UDCA. In conclusion, UDCA enhances alertness through disinhibition, at least partially of the histaminergic system via GABA(A) receptors.

  6. Antistaphylococcal and biofilm inhibitory activities of gallic, caffeic, and chlorogenic acids.

    PubMed

    Luís, Ângelo; Silva, Filomena; Sousa, Sónia; Duarte, Ana Paula; Domingues, Fernanda

    2014-01-01

    Staphylococcus aureus is a Gram-positive pathogen which is able to form biofilms, exhibiting a more pronounced resistance to antibiotics and disinfectants. The hurdles posed in eradicating biofilms have driven the search for new compounds able to fight these structures. Phenolic compounds constitute one of the most numerous and ubiquitous group of plant secondary metabolites with many biological activities. The aim of the present work was to study the potential antimicrobial and antibiofilm properties of gallic, caffeic, and chlorogenic acids against S. aureus as well to elucidate its mechanism of action. It was concluded that the phenolic acids studied in this work have antistaphylococcal properties. For instance, gallic acid is able to influence the adhesion properties of S. aureus. The phenolic acids tested were also able to inhibit the production of α-hemolysin by this microorganism, with the exception of chlorogenic acid. Regarding its mechanism of action, caffeic acid interferes with the stability of the cell membrane and with the metabolic activity of the cells of S. aureus.

  7. Conformationally sensitive proximity of extracellular loops 2 and 4 of the γ-aminobutyric acid (GABA) transporter GAT-1 inferred from paired cysteine mutagenesis.

    PubMed

    Hilwi, Maram; Dayan, Oshrat; Kanner, Baruch I

    2014-12-05

    The sodium- and chloride-coupled GABA transporter GAT-1 is a member of the neurotransmitter:sodium:symporters, which are crucial for synaptic transmission. Structural work on the bacterial homologue LeuT suggests that extracellular loop 4 closes the extracellular solvent pathway when the transporter becomes inward-facing. To test whether this model can be extrapolated to GAT-1, cysteine residues were introduced at positions 359 and 448 of extracellular loop 4 and transmembrane helix 10, respectively. Treatment of HeLa cells, expressing the double cysteine mutant S359C/K448C with the oxidizing reagent copper(II)(1,10-phenantroline)3, resulted in a significant inhibition of [(3)H]GABA transport. However, transport by the single cysteine mutant S359C was also inhibited by the oxidant, whereas its activity was almost 4-fold stimulated by dithiothreitol. Both effects were attenuated when the conserved cysteine residues, Cys-164 and/or Cys-173, were replaced by serine. These cysteines are located in extracellular loop 2, the role of which in the structure and function of the eukaryotic neurotransmitter:sodium:symporters remains unknown. The inhibition of transport of S359C by the oxidant was markedly reduced under conditions expected to increase the proportion of inward-facing transporters, whereas the reactivity of the mutants to a membrane-impermeant sulfhydryl reagent was not conformationally sensitive. Our data suggest that extracellular loops 2 and 4 come into close proximity to each other in the outward-facing conformation of GAT-1.

  8. [Effect of the GABA derivative phenibut on learning].

    PubMed

    Shul'gina, G I; Ziablitseva, E A

    2005-01-01

    The learning effect of phenibut, a beta-phenyl derivative of the inhibitory neuromediator GABA, used in a subcutaneous dose of 40 mg/kg 2 hours before each experiment, was studied in rabbits. The injection of phenibut was shown to enhance not only the inhibitory, but also excitatory components of cerebral cortical neuronal responses to all applied stimuli. The findings support the concept that the GABAergic neuromediator system is involved in the elaboration of internal inhibition and explain the sense of intracerebral processes that ensure both the sedative properties of phenibut and its ability to improve patients' systemic tone and health status when brain dysfunctions are treated.

  9. Modulatory action of taurine on the release of GABA in cerebellar slices of the guinea pig.

    PubMed

    Namima, M; Okamoto, K; Sakai, Y

    1983-01-01

    For the purpose of demonstrating the action of taurine as a neuromodulator in addition to its suggested neurotransmitter function, the effects of taurine and muscimol on the depolarization-induced Ca-dependent release of [3H] gamma-aminobutyric acid ([3H]GABA) and L-[3H]glutamate in cerebellar slices from guinea pigs were investigated. The release of [3H]GABA was found to be greatly decreased by a GABA agonist, muscimol, and by taurine, but not by glycine. The release of L-[3H]glutamate was little affected by taurine. The release of [3H]GABA, was enhanced by bicuculline and strychnine, but not by picrotoxin, and the suppressive action of muscimol on the GABA release was antagonized by bicuculline, picrotoxin, and strychnine, suggesting the possible existence of presynaptic autoreceptors for GABA in the cerebellum. The suppressive action of taurine on the release of [3H]GABA, on the other hand, was blocked only by bicuculline. These results suggest that taurine reduced the release of [3H]GABA from cerebellar slices by acting on the GABA autoreceptors or, more likely, on other types of receptors that are sensitive to bicuculline. As a possible mechanism for this modulatory action of taurine, the blockade by this amino acid of the influx of Ca2+ into cerebellar tissues was tentatively suggested.

  10. A study on quality components and sleep-promoting effects of GABA black tea.

    PubMed

    Zhao, Wenfang; Li, Yun; Ma, William; Ge, Yazhong; Huang, Yahui

    2015-10-01

    The aims of this study were to analyze the changes in quality components of gamma (γ)-aminobutyric acid (GABA) black tea during processing, and to investigate the effect of three dosages of GABA black tea on sleep improvement. The results showed that the GABA content was increased significantly up to 2.70 mg g(-1) after vacuum anaerobic and aerobic treatment. In addition, the content of GABA after drying reached 2.34 mg g(-1), which achieved the standard of GABA tea. During the entire processing of GABA black tea, the contents of tea polyphenols, caffeine and total catechins displayed a gradually descending trend, while the contents of free amino acids and GABA were firstly increased, and then reduced. The GABA black tea had significant effects on prolonging the sleeping time with sodium pentobarbital (P < 0.05) and significantly enhancing the sleeping rate induced by sodium pentobarbital at a sub-threshold dose (P < 0.05). But its effect on shortening the sleeping latency period induced by sodium barbital was not significant (P > 0.05). It had no effect on directly inducing sleep and the mouse body weight. The extract of GABA black tea improved the sleeping quality of mice to extend with an optimal effect being found in the high dose-treated mice.

  11. Inhibitory effect of oxalic acid on bacterial spoilage of raw chilled chicken.

    PubMed

    Anang, D M; Rusul, G; Radu, Son; Bakar, Jamilah; Beuchat, L R

    2006-08-01

    Oxalic acid was evaluated as a treatment for reducing populations of naturally occurring microorganisms on raw chicken. Raw chicken breasts were dipped in solutions of oxalic acid (0, 0.5, 1.0, 1.5, and 2.0%, wt/vol) for 10, 20, and 30 min, individually packed in oxygen-permeable polyethylene bags, and stored at 4 degrees C. Total plate counts of aerobic bacteria and populations of Pseudomonas spp. and Enterobacteriaceae on breasts were determined before treatment and after storage for 1, 3, 7, 10, and 14 days. The pH and Hunter L, a, and b values of the breast surface were measured. Total plate counts were ca. 1.5 and 4.0 log CFU/g higher on untreated chicken breasts after storage for 7 and 14 days, respectively, than on breasts treated with 0.5% oxalic acid, regardless of dip time. Differences in counts on chicken breasts treated with water and 1.0 to 2.0% of oxalic acid were greater. Populations of Pseudomonas spp. on chicken breasts treated with 0.5 to 2.0% oxalic acid and stored at 4 degrees C for 1 day were less than 2 log CFU/g (detection limit), compared with 5.14 log CFU/g on untreated breasts. Pseudomonas grew on chicken breasts treated with 0.5% oxalic acid to reach counts not exceeding 3.88 log CFU/g after storage for 14 days. Counts on untreated chicken exceeded 8.83 log CFU/g at 14 days. Treatment with oxalic acid caused similar reductions in Enterobacteriaceae counts. Kocuria rhizophila was the predominant bacterium isolated from treated chicken. Other common bacteria included Escherichia coli and Empedobacter brevis. Treatment with oxalic acid caused a slight darkening in color (decreased Hunter L value), retention of redness (increased Hunter a value), and increase in yellowness (increased Hunter b value). Oxalic acid has potential for use as a sanitizer to reduce populations of spoilage microorganisms naturally occurring on raw chicken, thereby extending chicken shelf life.

  12. Inhibitory effect of caffeic acid on human organic anion transporters hOAT1 and hOAT3: a novel candidate for food-drug interaction.

    PubMed

    Uwai, Yuichi; Ozeki, Yukihiro; Isaka, Tomonori; Honjo, Hiroaki; Iwamoto, Kikuo

    2011-01-01

    Several kinds of food have been shown to influence the absorption and metabolism of drugs, although there is little information about their effect on the renal excretion of drugs. In this study, we performed uptake experiments using Xenopus laevis oocytes to assess the inhibitory effects of chlorogenic acid, caffeic acid and quinic acid, which are contained in coffee, fruits and vegetables, on human organic anion transporters hOAT1 and hOAT3; these transporters mediate renal tubular uptake of anionic drugs from blood. Injection of hOAT1 and hOAT3 cRNA into oocytes stimulated uptake of typical substrates of hOAT1 and hOAT3 (p-aminohippurate and estrone sulfate, respectively); among the three compounds tested, caffeic acid most strongly inhibited these transporters. The apparent 50% inhibitory concentrations of caffeic acid were estimated to be 16.6 µM for hOAT1 and 5.4 µM for hOAT3. Eadie-Hofstee plot analysis showed that caffeic acid inhibited both transporters in a competitive manner. In addition to the transport of p-aminohippurate and estrone sulfate, that of antifolates and antivirals was inhibited by caffeic acid. These findings show that caffeic acid has inhibitory potential against hOAT1 and hOAT3, suggesting that renal excretion of their substrates could be affected in patients consuming a diet including caffeic acid.

  13. Neuronal activity and brain-derived neurotrophic factor regulate the density of inhibitory synapses in organotypic slice cultures of postnatal hippocampus.

    PubMed

    Marty, S; Wehrlé, R; Sotelo, C

    2000-11-01

    Hippocampal interneurons inhibit pyramidal neurons through the release of the neurotransmitter GABA. Given the importance of this inhibition for the proper functioning of the hippocampus, the development of inhibitory synapses must be tightly regulated. In this study, the possibility that neuronal activity and neurotrophins regulate the density of GABAergic inhibitory synapses was investigated in organotypic slice cultures taken from postnatal day 7 rats. In hippocampal slices cultured for 13 d in the presence of the GABA(A) receptor antagonist bicuculline, the density of glutamic acid decarboxylase (GAD) 65-immunoreactive terminals was increased in the CA1 area when compared with control slices. Treatment with the glutamate receptor antagonist 6,7-dinitroquinoxaline-2,3-dione decreased the density of GAD65-immunoreactive terminals in the stratum oriens of CA1. These treatments had parallel effects on the density of GABA-immunoreactive processes. Electron microscopic analysis after postembedding immunogold labeling with antibodies against GABA indicated that bicuculline treatment increased the density of inhibitory but not excitatory synapses. Application of exogenous BDNF partly mimicked the stimulatory effect of bicuculline on GAD65-immunoreactive terminals. Finally, antibodies against BDNF, but not antibodies against nerve growth factor, decrease the density of GAD65-immunoreactive terminals in bicuculline-treated slices. Thus, neuronal activity regulates the density of inhibitory synapses made by postnatal hippocampal interneurons, and BDNF could mediate part of this regulation. This regulation of the density of inhibitory synapses could represent a feedback mechanism aimed at maintaining an appropriate level of activity in the developing hippocampal networks.

  14. Magnetic resonance spectroscopy reveals oral Lactobacillus promotion of increases in brain GABA, N-acetyl aspartate and glutamate.

    PubMed

    Janik, Rafal; Thomason, Lynsie A M; Stanisz, Andrew M; Forsythe, Paul; Bienenstock, John; Stanisz, Greg J

    2016-01-15

    The gut microbiome has been shown to regulate the development and functions of the enteric and central nervous systems. Its involvement in the regulation of behavior has attracted particular attention because of its potential translational importance in clinical disorders, however little is known about the pathways involved. We previously have demonstrated that administration of Lactobacillus rhamnosus (JB-1) to healthy male BALB/c mice, promotes consistent changes in GABA-A and -B receptor sub-types in specific brain regions, accompanied by reductions in anxiety and depression-related behaviors. In the present study, using magnetic resonance spectroscopy (MRS), we quantitatively assessed two clinically validated biomarkers of brain activity and function, glutamate+glutamine (Glx) and total N-acetyl aspartate+N-acetyl aspartyl glutamic acid (tNAA), as well as GABA, the chief brain inhibitory neurotransmitter. Mice received 1×10(9) cfu of JB-1 per day for 4weeks and were subjected to MRS weekly and again 4weeks after cessation of treatment to ascertain temporal changes in these neurometabolites. Baseline concentrations for Glx, tNAA and GABA were equal to 10.4±0.3mM, 8.7±0.1mM, and 1.2±0.1mM, respectively. Delayed increases were first seen for Glx (~10%) and NAA (~37%) at 2weeks which persisted only to the end of treatment. However, Glx was still elevated 4weeks after treatment had ceased. Significantly elevated GABA (~25%) was only seen at 4weeks. These results suggest specific metabolic pathways in our pursuit of mechanisms of action of psychoactive bacteria. They also offer through application of standard clinical neurodiagnostic techniques, translational opportunities to assess biomarkers accompanying behavioral changes induced by alterations in the gut microbiome.

  15. Adhesive Properties and Acid-Forming Activity of Lactobacilli and Streptococci Under Inhibitory Substances, Such as Nitrates.

    PubMed

    Hakobyan, L; Harutyunyan, K; Harutyunyan, N; Melik-Andreasyan, G; Trchounian, A

    2016-06-01

    One of the main requirements for probiotics is their ability to survive during passage through gastrointestinal tract and to maintain their activity at different adverse conditions. The aim of the study was to look for the strains of lactobacilli and streptococci with high adhesive properties even affected by inhibitory substances, such as nitrates (NO3 (-)). To study the adhesion properties hemagglutination reaction of bacterial cells with red blood cells of different animals and humans was used. The acid formation ability of bacteria was determined by the method of titration after 7 days of incubation in the sterile milk. These properties were investigated at different concentrations of NO3 (-). The high concentration (mostly ≥2.0 %) NO3 (-) inhibited the growth of both lactobacilli and streptococci, but compared with streptococcal cultures lactobacilli, especially Lactobacillus acidophilus Ep 317/402, have shown more stability and higher adhesive properties. In addition, the concentrations of NO3 (-) of 0.5-2.0 % decreased the acid-forming activity of the strains, but even under these conditions they coagulated milk and, in comparison to control, formed low acidity in milk. Thus, the L. acidophilus Ep 317/402 with high adhesive properties has demonstrated a higher activity of NO3 (-) transformation.

  16. Pharmacological characterisation of a cell line expressing GABA B1b and GABA B2 receptor subunits.

    PubMed

    Hirst, Warren D; Babbs, Adam J; Green, Andrew; Minton, Jayne A L; Shaw, Tracy E; Wise, Alan; Rice, Simon Q; Pangalos, Menelas N; Price, Gary W

    2003-04-01

    The gamma-aminobutyric acid (GABA(B)) receptor has been shown to be a heterodimer consisting of two receptor subunits, GABA(B1) and GABA(B2). We have stably co-expressed these two subunits in a CHO cell line, characterised its pharmacology and compared it to the native receptor in rat brain membranes. Radioligand binding using [3H]CGP54626A demonstrated a similar rank order of potency between recombinant and native receptors: CGP62349>CGP54626A>SCH 50911>3-aminopropylphosphinicacid(3-APPA)>GABA>baclofen>saclofen>phaclofen. However, differences were observed in the affinity of agonists, which were higher at the native receptor, suggesting that in the recombinant system a large number of the receptors were in the low agonist affinity state. In contrast, [35S]GTPgammaS binding studies did not show any differences between recombinant and native receptors with the full agonists GABA and 3-APPA. Measurement of cAMP accumulation in the cells revealed a degree of endogenous coupling of the receptors to G-proteins. This is most likely to be due to the high expression levels of receptors (B(max)=22.5+/-2.5pmol/mg protein) in this experimental system. There was no evidence of GABA(B2) receptors, when expressed alone, binding [3H]CGP54626A, [3H]GABA, [3H]3-APPA nor of GABA having any effect on basal [35S]GTPgammaS binding or cAMP levels.

  17. [Inhibitory effect of essential oils, food additives, peracetic acid and detergents on bacterial histidine decarboxylase].

    PubMed

    Kamii, Eri; Terada, Gaku; Akiyama, Jyunki; Isshiki, Kenji

    2011-01-01

    The aim of this study is to examine whether various essential oils, food additives, peracetic acid and detergents inhibit bacterial histidine decarboxylase. Crude extract of Morganella morganii NBRC3848 was prepared and incubated with various agents. Histidine decarboxylase activity was significantly inhibited (p<0.05) by 26 of 45 compounds tested. Among the 26 agents, sodium hypochlorite completely decomposed both histidine and histamine, while peracetic acid caused slight decomposition. Histidine and histamine were stable in the presence of the other 24 agents. These results indicated that 25 of the agents examined were inhibitors of histidine decarboxylase.

  18. GABA A receptor π subunit promotes apoptosis of HTR-8/SVneo trophoblastic cells: Implications in preeclampsia.

    PubMed

    Lu, Junjie; Zhang, Qian; Tan, Dongmei; Luo, Wenping; Zhao, Hai; Ma, Jing; Liang, Hao; Tan, Yi

    2016-07-01

    Gamma-aminobutyric acid (GABA) functions primarily as an inhibitory neurotransmitter through its receptors in the mature central nervous system. The GABA type A receptor π subunit (GABRP) has been identified in the tissues of the reproductive system, particularly in the uterus. In addition, we have previously detected GABRP expression in both human and mouse placentas. To examine the role of GABRP in trophoblastic cell invasion, we constructed a pIRES2-GABRP-EGFP plasmid which was used for the transfection of a human placental cell line derived from first trimester extravillous trophoblasts (HTR-8/SVneo). The number of invaded cells was decreased by GABRP overexpression. Notably, the decrease in the invasive cell number may be due to the increased apoptosis of the HTR-8/SVneo cells following GABRP transfection, which was further confirmed by flow cytometry, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. Based on the increased apoptosis of trophoblastic cells in pregnancies complicated by preeclampsia (PE) and the fact that GABRP promotes the apoptosis of trophoblastic cells, we hypothesized that GABRP expression is increased in the placental tissues from patients with PE compared with that in the normal groups and this hypothesis was confirmed by RT-qPCR and immunohistochemical analysis. Taken together, these findings imply that GABRP plays an important role in placentation and this pathway may be a promising molecular target for the development of novel therapeutic strategies for PE.

  19. Possible expression of a particular gamma-aminobutyric acid transporter isoform responsive to upregulation by hyperosmolarity in rat calvarial osteoblasts.

    PubMed

    Fujimori, Sayumi; Hinoi, Eiichi; Takarada, Takeshi; Iemata, Mika; Takahata, Yoshifumi; Yoneda, Yukio

    2006-11-21

    Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter in the brain, but widely distributed in different peripheral organs. We have previously shown the functional expression of GABA(B) receptors required for GABAergic signal input by cultured rat calvarial osteoblasts. This study focused on the possible functional expression of the machinery required for GABAergic signal termination such as GABA transporters. In rat calvarial osteoblasts cultured for 7 days, [(3)H]GABA accumulation was observed in a temperature-, sodium- and chloride-dependent manner, consisting of a single component with a K(m) value of 789.6+/-9.0 microM and a V(max) value of 4.4+/-0.1 nmol/min/mg protein, respectively. Both nipecotic and L-2,4-diaminobutyric acids significantly inhibited [(3)H]GABA accumulation in a concentration-dependent manner. Constitutive expression was seen with mRNA for the betaine/GABA transporter-1 (BGT-1) and taurine transporter (TauT), while hyperosmotic cultivation led to significant increases in both [(3)H]GABA accumulation and BGT-1 mRNA expression without affecting TauT mRNA expression. Highly immunoreactive cells were detected for the BGT-1 isoform at the surface of trabecular bone of neonatal rat tibias. Sustained exposure to GABA significantly inhibited alkaline phosphatase (ALP) activity, but not cellular viability, at concentrations above 0.1 mM in osteoblasts cultured for 3 to 28 days. Nipecotic acid not only decreased ALP activity alone, but also further decreased ALP activity in osteoblasts cultured in the presence of GABA. These results suggest that the BGT-1 isoform may be functionally expressed by rat calvarial osteoblasts to play a hitherto unidentified role in mechanisms underlying hyperosmotic regulation of osteoblastogenesis.

  20. The Role of Genetic Sex in Affect Regulation and Expression of GABA-Related Genes Across Species

    PubMed Central

    Seney, Marianne L.; Chang, Lun-Ching; Oh, Hyunjung; Wang, Xingbin; Tseng, George C.; Lewis, David A.; Sibille, Etienne

    2013-01-01

    Although circulating hormones and inhibitory gamma-aminobutyric acid (GABA)-related factors are known to affect mood, considerable knowledge gaps persist for biological mechanisms underlying the female bias in mood disorders. Here, we combine human and mouse studies to investigate sexual dimorphism in the GABA system in the context of major depressive disorder (MDD) and then use a genetic model to dissect the role of sex-related factors in GABA-related gene expression and anxiety-/depressive-like behaviors in mice. First, using meta-analysis of gene array data in human postmortem brain (N = 51 MDD subjects, 50 controls), we show that the previously reported down-regulation in MDD of somatostatin (SST), a marker of a GABA neuron subtype, is significantly greater in women with MDD. Second, using gene co-expression network analysis in control human subjects (N = 214; two frontal cortex regions) and expression quantitative trait loci mapping (N = 170 subjects), we show that expression of SST and the GABA-synthesizing enzymes glutamate decarboxylase 67 (GAD67) and GAD65 are tightly co-regulated and influenced by X-chromosome genetic polymorphisms. Third, using a rodent genetic model [Four Core Genotypes (FCG) mice], in which genetic and gonadal sex are artificially dissociated (N ≥ 12/group), we show that genetic sex (i.e., X/Y-chromosome) influences both gene expression (lower Sst, Gad67, Gad65 in XY mice) and anxiety-like behaviors (higher in XY mice). This suggests that in an intact male animal, the observed behavior represents the outcomes of male genetic sex increasing and male-like testosterone decreasing anxiety-like behaviors. Gonadal sex was the only factor influencing depressive-like behavior (gonadal males < gonadal females). Collectively, these combined human and mouse studies provide mechanistic insight into sexual dimorphism in mood disorders, and specifically demonstrate an unexpected role of male-like factors (XY genetic sex) on

  1. Investigation of platelet aggregation inhibitory activity by phenyl amides and esters of piperidinecarboxylic acids.

    PubMed

    de Candia, Modesto; Summo, Luciana; Carrieri, Antonio; Altomare, Cosimo; Nardecchia, Adele; Cellamare, Saverio; Carotti, Angelo

    2003-04-03

    A series of anilides and phenyl esters of piperidine-3-carboxylic acid (nipecotic acid) were synthesized and tested for the ability to inhibit aggregation of human platelet rich-plasma triggered by adenosine 5'-diphosphate (ADP) and adrenaline. As a rule, amides were about two times more active than the corresponding esters, and derivatives bearing substituents at the para position of the phenyl ring were significantly more active than the meta-substituted ones. Among the tested compounds, 4-hexyloxyanilide of nipecotic acid (18a) was found to be the most active one, its IC(50) value being close to that of the most active bis-3-carbamoylpiperidines reported in literature (ca. 40 micro M) and aspirin (ca. 60 microM) in ADP- and adrenaline-induced aggregation, respectively. Compared with the isomeric 4-hexyloxyanilides of piperidine-2-carboxylic (pipecolinic) and piperidine-4-carboxylic (isonipecotic) acids, compound 18a showed higher activity, and a Hansch-type quantitative structure-activity relationship (QSAR) study highlighted lipophilicity and increase in electron density of the phenyl ring as the properties which mainly increase the antiplatelet activity (r(2)=0.74, q(2)=0.64). The interaction of nipecotoyl anilides with phosphatidylinositol, a major component of the inner layer of the platelet membranes, was investigated by means of flexible docking calculation methods to give an account of a key event underlying their biological action.

  2. The inhibitory efficacy of methylseleninic acid against colon cancer xenografts in C57BL/6 mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Data indicate that methylselenol is a critical selenium (Se) metabolite for anticancer activity in vivo. We tested the hypoththesis that oral dosing methylseleninic acid (MSeA), a methylselenol precursor, inhibits the growth of colon cancer xenografts in C57BL/6 mice fed a Se adequate diet. In this...

  3. Inhibitory activities of omega-3 Fatty acids and traditional african remedies on keloid fibroblasts.

    PubMed

    Olaitan, Peter B; Chen, I-Ping; Norris, James E C; Feinn, Richard; Oluwatosin, Odunayo M; Reichenberger, Ernst J

    2011-04-01

    Keloids develop when scar tissue responds to skin trauma with proliferative fibrous growths that extend beyond the boundaries of the original wound and progress for several months or years. Keloids most frequently occur in individuals of indigenous sub-Saharan African origin. The etiology for keloids is still unknown and treatment can be problematic as patients respond differently to various treatment modalities. Keloids have a high rate of recurrence following surgical excision. Some West African patients claim to have had successful outcomes with traditional African remedies-boa constrictor oil (BCO) and shea butter-leading the authors to investigate their effects on cultured fibroblasts. The effects of emulsions of BCO, fish oil, isolated omega-3 fatty acids, and shea butter were tested in comparison to triamcinolone regarding inhibition of cell growth in keloid and control fibroblast cultures. In a series of controlled studies, it was observed that fish oil and BCO were more effective than triamcinolone, and that cis-5, 8, 11, 14, 17-eicosapentaenoic acid was more effective than -linolenic acid. While cell counts in control cultures continuously decreased over a period of 5 days, cell counts in keloid cultures consistently declined between day 1 and day 3, and then increased between day 3 and day 5 for all tested reagents except for fish oil. These results suggest that oils rich in omega-3 fatty acids may be effective in reducing actively proliferating keloid fibroblasts. Additional studies are warranted to investigate whether oils rich in omega-3 fatty acids offer effective and affordable treatment for some keloid patients, especially in the developing world.

  4. GABA actions in hippocampal area CA3 during postnatal development: differential shift from depolarizing to hyperpolarizing in somatic and dendritic compartments.

    PubMed

    Romo-Parra, Héctor; Treviño, Mario; Heinemann, Uwe; Gutiérrez, Rafael

    2008-03-01

    Gamma-aminobutyric acid type A receptor (GABA(A)-R) activation leads to depolarization of pyramidal cells during the first postnatal week and produces hyperpolarization from the second week. However, immunohistochemical evidence has suggested that during the second and third postnatal weeks the NKCC1 cotransporter relocates from the soma to the dendrites of CA3 pyramidal cells. We hypothesized that this leads to depolarizing responses in apical dendrites. Here we show that the activation of GABA(A)-R in the distal dendrites of CA3 pyramidal cells at P15 by restricted application of muscimol or synaptic activation by stimulation of interneurons in stratum radiatum (SR) causes depolarizing postsynaptic potentials (PSPs), which are blocked by NKCC1 cotransporter antagonists. By contrast, activation of proximal GABA(A)-R by muscimol application or by stimulation of interneurons in s. oriens (SO) leads to hyperpolarizing PSPs. Activation of the dentate gyrus (DG) in the presence of glutamatergic blockers evokes hyperpolarizing responses during the second postnatal week; however, the reversal potential of the DG-evoked inhibitory (I)PSPs is more depolarized than that of IPSPs evoked by activation of SO interneurons. Despite the shift of GABA action from depolarizing to hyperpolarizing, DG-evoked field potentials (f-PSPs) recorded in s. lucidum/radiatum (SL/R) do not change in polarity until the third week. Current source density analysis yielded results consistent with depolarizing actions of GABA in the dendritic compartment. Our data suggest that GABAergic input to apical dendrites of pyramidal cells of CA3 evokes depolarizing PSPs long after synaptic inhibition has become hyperpolarizing in the somata, in the axon initial segments and in basal dendrites.

  5. The TM2 6' position of GABA(A) receptors mediates alcohol inhibition.

    PubMed

    Johnson, W David; Howard, Rebecca J; Trudell, James R; Harris, R Adron

    2012-02-01

    Ionotropic GABA(A) receptors (GABA(A)Rs), which mediate inhibitory neurotransmission in the central nervous system, are implicated in the behavioral effects of alcohol and alcoholism. Site-directed mutagenesis studies support the presence of discrete molecular sites involved in alcohol enhancement and, more recently, inhibition of GABA(A)Rs. We used Xenopus laevis oocytes to investigate the 6' position in the second transmembrane region of GABA(A)Rs as a site influencing alcohol inhibition. We asked whether modification of the 6' position by substitution with larger residues or methanethiol labeling [using methyl methanethiosulfonate (MMTS)] of a substituted cysteine, reduced GABA action and/or blocked further inhibition by alcohols. Labeling of the 6' position in either α2 or β2 subunits reduced responses to GABA. In addition, methanol and ethanol potentiation increased after MMTS labeling or substitution with tryptophan or methionine, consistent with elimination of an inhibitory site for these alcohols. Specific alcohols, but not the anesthetic etomidate, competed with MMTS labeling at the 6' position. We verified a role for the 6' position in previously tested α2β2 as well as more physiologically relevant α2β2γ2s GABA(A)Rs. Finally, we built a novel molecular model based on the invertebrate glutamate-gated chloride channel receptor, a GABA(A)R homolog, revealing that the 6' position residue faces the channel pore, and modification of this residue alters volume and polarity of the pore-facing cavity in this region. These results indicate that the 6' positions in both α2 and β2 GABA(A)R subunits mediate inhibition by short-chain alcohols, which is consistent with the presence of multiple counteracting sites of action for alcohols on ligand-gated ion channels.

  6. Kinase inhibitory, haemolytic and cytotoxic activity of three deep-water sponges from North Western Australia and their fatty acid composition.

    PubMed

    Zivanovic, Ana; Pastro, Natalie J; Fromont, Jane; Thomson, Murray; Skropeta, Danielle

    2011-12-01

    The c-AMP dependent protein kinase (PKA) inhibition, haemolytic activity, and cytoxicity of 21 extracts obtained from North Western Australian sponges collected from depths of 84-135 m were investigated. Hexane extracts from Ircinia/Sarcotragus sp. and Geodia sp. displayed PKA inhibitory activities of 100 and 97% respectively (at 100 microg/mL), while aq. methanol extracts from Haliclona sp. exhibited potent haemolytic activity (75%) and hexane extracts from Geodia sp. were highly toxic (88%) to the brine shrimp Artemia franciscana. As the non-polar extracts gave the greatest PKA inhibition, these were further analysed by GC-MS and 29 fatty acids were identified in the highest proportions in Ircinia/Sarcotragus sp. > Haliclona sp. > Geodia sp. In contrast to shallow-water sponges that are dominated by polyunsaturated fatty acids with a high percentage of long chain fatty acids, LCFAs (C24-C30), the deep-sea sponges investigated herein were all found to be rich in saturated fatty acids, in particular C14-C20 fatty acids, including odd and branched chain fatty acids, with only low levels (0-10%) of LCFAs. Screening of the PKA inhibitory activity of a series of commercially available fatty acids identified C14-C18 fatty acids as possessing significant PKA inhibitory activity that may contribute to the activity observed in the sponges studied.

  7. Novel GABA receptor pesticide targets.

    PubMed

    Casida, John E; Durkin, Kathleen A

    2015-06-01

    The γ-aminobutyric acid (GABA) receptor has four distinct but overlapping and coupled targets of pesticide action importantly associated with little or no cross-resistance. The target sites are differentiated by binding assays with specific radioligands, resistant strains, site-directed mutagenesis and molecular modeling. Three of the targets are for non-competitive antagonists (NCAs) or channel blockers of widely varied chemotypes. The target of the first generation (20th century) NCAs differs between the larger or elongated compounds (NCA-IA) including many important insecticides of the past (cyclodienes and polychlorocycloalkanes) or present (fiproles) and the smaller or compact compounds (NCA-IB) highly toxic to mammals and known as cage convulsants, rodenticides or chemical threat agents. The target of greatest current interest is designated NCA-II for the second generation (21st century) of NCAs consisting for now of isoxazolines and meta-diamides. This new and uniquely different NCA-II site apparently differs enough between insects and mammals to confer selective toxicity. The fourth target is the avermectin site (AVE) for allosteric modulators of the chloride channel. NCA pesticides vary in molecular surface area and solvent accessible volume relative to avermectin with NCA-IBs at 20-22%, NCA-IAs at 40-45% and NCA-IIs at 57-60%. The same type of relationship relative to ligand-docked length is 27-43% for NCA-IBs, 63-71% for NCA-IAs and 85-105% for NCA-IIs. The four targets are compared by molecular modeling for the Drosophila melanogaster GABA-R. The principal sites of interaction are proposed to be: pore V1' and A2' for NCA-IB compounds; pore A2', L6' and T9' for NCA-IA compounds; pore T9' to S15' in proximity to M1/M3 subunit interface (or alternatively an interstitial site) for NCA-II compounds; and M1/M3, M2 interfaces for AVE. Understanding the relationships of these four binding sites is important in resistance management and in the discovery and use

  8. Possible role of glutamate, aspartate, glutamine, GABA or taurine on cadmium toxicity on the hypothalamic pituitary axis activity in adult male rats.

    PubMed

    Lafuente, A; Esquifino, A I

    2002-06-01

    This work was designed to evaluate the possible changes in glutamate, aspartate, glutamine, GABA and taurine within various hypothalamic areas the striatum and prefrontal cortex after oral cadmium exposure in adult male rats, and if these changes are related to pituitary hormone secretion. The contents of glutamine, glutamate, aspartate, GABA and taurine in the median eminence, anterior, mediobasal and posterior hypothalamus, and in prefrontal cortex in adult male rats exposed to 272.7 micromol l(-1) of cadmium chloride (CdCl2) in the drinking water for one month. Cadmium diminished the content of glutamine, glutamate and aspartate in anterior hypothalamus as compared to the values found in the untreated group. Besides, there is a decrease in the content of glutamate, aspartate and taurine in the prefrontal cortex. The amino acids studied did not change in median eminence, mediobasal and posterior hypothalamus or the striatum by cadmium treatment. Plasma prolactin and LH levels decreased in rats exposed to the metal. These results suggest that (1) cadmium differentially affects amino acid content within the brain region studied and (2) the inhibitory effect of cadmium on prolactin and LH secretion may be partially explained by a decrease in the content of both glutamate and aspartate in anterior hypothalamus, but not through changes in GABA and taurine.

  9. Downregulation of GABA[Subscript A] Receptor Protein Subunits a6, ß2, d, e, ?2, ?, and ?2 in Superior Frontal Cortex of Subjects with Autism

    ERIC Educational Resources Information Center

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Rustan, Oyvind G.; Rooney, Robert J.; Thuras, Paul D.

    2014-01-01

    We measured protein and mRNA levels for nine gamma-aminobutyric acid A (GABA[subscript A]) receptor subunits in three brain regions (cerebellum, superior frontal cortex, and parietal cortex) in subjects with autism versus matched controls. We observed changes in mRNA for a number of GABA[subscript A] and GABA[subscript B] subunits and overall…

  10. Analysis of GABA(A)- and GABA(B)-receptor mediated effects on intracellular Ca(2+) in DRG hybrid neurones.

    PubMed

    Yokogawa, T; Kim, S U; Krieger, C; Puil, E

    2001-09-01

    1. Using pharmacological analysis and fura-2 spectrofluorimetry, we examined the effects of gamma-aminobutyric acid (GABA) and related substances on intracellular Ca(2+) concentration ([Ca(2+)]i) of hybrid neurones, called MD3 cells. The cell line was produced by fusion between a mouse neuroblastoma cell and a mouse dorsal root ganglion (DRG) neurone. 2. MD3 cells exhibited DRG neurone-like properties, such as immunoreactivity to microtubule-associated protein-2 and neurofilament proteins. Bath applications of capsaicin and alpha, beta-methylene adenosine triphosphate reversibly increased [Ca(2+)]i. However, repeated applications of capsaicin were much less effective. 3. Pressure applications of GABA (100 microM), (Z)-3-[(aminoiminomethyl) thio] prop-2-enoic acid sulphate (ZAPA; 100 microM), an agonist at low affinity GABA(A)-receptors, or KCl (25 mM), transiently increased [Ca(2+)]i. 4. Bath application of bicuculline (100 nM - 100 microM), but not picrotoxinin (10 - 25 microM), antagonized GABA-induced increases in [Ca(2+)]i in a concentration-dependent manner (IC(50)=9.3 microM). 5. Ca(2+)-free perfusion reversibly abolished GABA-evoked increases in [Ca(2+)]i. Nifedipine and nimodipine eliminated GABA-evoked increases in [Ca(2+)]i. These results imply GABA response dependence on extracellular Ca(2+). 6. Baclofen (500 nM - 100 microM) activation of GABA(B)-receptors reversibly attenuated KCl-induced increases in [Ca(2+)]i in a concentration-dependent manner (EC(50)=1.8 microM). 2-hydroxy-saclofen (1 - 20 microM) antagonized the baclofen-depression of the KCl-induced increase in [Ca(2+)]i. 7. In conclusion, GABA(A)-receptor activation had effects similar to depolarization by high external K(+), initiating Ca(2+) influx through high voltage-activated channels, thereby transiently elevating [Ca(2+)]i. GABA(B)-receptor activation reduced Ca(2+) influx evoked by depolarization, possibly at Ca(2+)-channel sites in MD3 cells.

  11. Evidence against GABA release from glutamatergic mossy fiber terminals in the developing hippocampus.

    PubMed

    Uchigashima, Motokazu; Fukaya, Masahiro; Watanabe, Masahiko; Kamiya, Haruyuki

    2007-07-25

    Hippocampal mossy fibers of young rodents have been reported to corelease inhibitory neurotransmitter GABA in addition to excitatory transmitter glutamate. In this study, we aimed at re-evaluating this corelease hypothesis of both inhibitory and excitatory transmitters in the hippocampus. Electrophysiological examination revealed that, in juvenile mice and rats of the two to 3 weeks old, stimulation at the granule cell layer of the dentate gyrus elicited monosynaptic GABAergic IPSCs in CA3 neurons in the presence of ionotropic glutamate receptor (iGluR) blockers, only when rather strong stimuli were given. The group II mGluR agonist (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclo-propyl)glycine (DCG-IV), which selectively suppresses transmission at the mossy fiber-CA3 synapse, abolished almost all postsynaptic responses elicited by the weak stimuli, whereas those by strong stimuli were inhibited only slightly. In addition, the minimal stimulation elicited GABAergic IPSCs in neonatal mice of the first postnatal week, whereas these responses are not sensitive to DCG-IV. Immunohistochemical examination revealed that mossy fiber terminals expressed GABA and the GABA-synthesizing enzyme GAD67, although the expression levels were much weaker than those in the inhibitory interneurons. Notably, the expression levels of the vesicular GABA transporter were much lower than those of GABA and GAD67, and almost below detection threshold. These results suggest that mossy fiber synapses are purely glutamatergic and apparent monosynaptic IPSCs so far reported are evoked by costimulation of inhibitory interneurons, at least in young mice and rats. Hippocampal mossy fiber terminals synthesize and store GABA, but have limited ability in vesicular release for GABA in the developing rodents.

  12. Properties of GABA-mediated synaptic potentials induced by zinc in adult rat hippocampal pyramidal neurones.

    PubMed Central

    Xie, X; Smart, T G

    1993-01-01

    1. Intracellular recording techniques were used to study the actions of the transition ion, zinc, on CA1 and CA3 pyramidal neurones in adult rat hippocampal slices. 2. Zinc (300 microM) hyperpolarized pyramidal neurones, increased the membrane excitability and also induced periodic, spontaneous giant depolarizing potentials associated with a conductance increase mechanism. 3. The occurrence of spontaneous giant depolarizations was dependent on the zinc concentration (10 microM-1 mM) with an apparent dissociation constant of 98 microM. The frequency of zinc-induced depolarizations was unaffected by the membrane potential from -50 to -100 mV. 4. Stimulation of the Schaffer collaterals or mossy fibre pathways evoked an excitatory and inhibitory synaptic potential complex. In the presence of zinc, nerve fibre stimulation evoked, in an all-or-none fashion, a giant depolarizing potential with an increased membrane conductance. Both spontaneous and evoked depolarizations were inhibited by 1 microM tetrodotoxin. 5. Evoked giant depolarizations were labile with too frequent stimulation resulting in a failure of generation. A minimum time of 140 s was required between stimuli to ensure successive giant depolarizations. 6. Spontaneous and evoked zinc-induced depolarizing potentials were inhibited by bicuculline (10 microM) or picrotoxin (40 microM) and enhanced by pentobarbitone (100 microM) or flurazepam (10 microM), suggesting that these potentials are mediated by activation of gamma-aminobutyric acidA (GABAA) receptors. 7. Ionophoretic application of GABA produced biphasic responses at -60 mV membrane potential. The reversal potentials for the depolarizing and hyperpolarizing GABA responses were -56 +/- 5 and -66 +/- 8 mV respectively. The giant depolarizations induced by zinc reversed at -57 +/- 4 mV. This suggests a dendritic location for the generation of these potentials. 8. Excitatory amino acid antagonists, 2-amino-5-phosphonovalerate (APV, 40 microM) or 6-cyano-7

  13. Changes in mediobasal hypothalamic dopamine and GABA release: a possible mechanism underlying taurine-induced prolactin secretion.

    PubMed

    Arias, P; Jarry, H; Convertini, V; Ginzburg, M; Wuttke, W; Moguilevsky, J

    1998-01-01

    Taurine (Tau), a putative inhibitory amino acid neurotransmitter, has been shown to stimulate prolactin (PRL) release. Using ovariectomized, estrogen-replaced adult rats we investigated initially the effect of this amino acid, injected by different routes, on PRL secretion in vivo. Tau (100-500 mg/kg) had no effect on PRL release when given i.p.; 15 min after i.c.v. injection of Tau (3 mumoles), a significant increase in serum PRL levels was observed (78 +/- 9 ng/ml over basal levels, p < 0.01 vs. controls). In vitro (cultured anterior pituitary cells) PRL release was not affected by a 5 h incubation with Tau (10(-3)-10(-8) M). Basal dopamine (DA) or gamma-aminobutyric acid (GABA) output from superfused mediobasal hypothalamic fragments (MBH) was not affected by Tau (10(-3) M or 10(-5) M). However, during stimulation with KCl (50 mM), Tau (10(-3) M) significantly lowered DA release, and increased GABA output. It is concluded that Tau acts at a central level to increase PRL secretion, most probably by modulating the hypothalamic release of neurotransmitters controlling lactotroph function.

  14. A single amino acid substitution in CFTR converts ATP to an inhibitory ligand

    PubMed Central

    Lin, Wen-Ying; Jih, Kang-Yang

    2014-01-01

    Cystic fibrosis (CF), one of the most common lethal genetic diseases, is caused by loss-of-function mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a chloride channel that, when phosphorylated, is gated by ATP. The third most common pathogenic mutation, a glycine-to-aspartate mutation at position 551 or G551D, shows a significantly decreased open probability (Po) caused by failure of the mutant channel to respond to ATP. Recently, a CFTR-targeted drug, VX-770 (Ivacaftor), which potentiates G551D-CFTR function in vitro by boosting its Po, has been approved by the FDA to treat CF patients carrying this mutation. Here, we show that, in the presence of VX-770, G551D-CFTR becomes responsive to ATP, albeit with an unusual time course. In marked contrast to wild-type channels, which are stimulated by ATP, sudden removal of ATP in excised inside-out patches elicits an initial increase in macroscopic G551D-CFTR current followed by a slow decrease. Furthermore, decreasing [ATP] from 2 mM to 20 µM resulted in a paradoxical increase in G551D-CFTR current. These results suggest that the two ATP-binding sites in the G551D mutant mediate opposite effects on channel gating. We introduced mutations that specifically alter ATP-binding affinity in either nucleotide-binding domain (NBD1 or NBD2) into the G551D background and determined that this disease-associated mutation converts site 2, formed by the head subdomain of NBD2 and the tail subdomain of NBD1, into an inhibitory site, whereas site 1 remains stimulatory. G551E, but not G551K or G551S, exhibits a similar phenotype, indicating that electrostatic repulsion between the negatively charged side chain of aspartate and the γ-phosphate of ATP accounts for the observed mutational effects. Understanding the molecular mechanism of this gating defect lays a foundation for rational drug design for the treatment of CF. PMID:25225552

  15. Antimicrobial and Efflux Pump Inhibitory Activity of Caffeoylquinic Acids from Artemisia absinthium against Gram-Positive Pathogenic Bacteria

    PubMed Central

    Fiamegos, Yiannis C.; Kastritis, Panagiotis L.; Exarchou, Vassiliki; Han, Haley; Bonvin, Alexandre M. J. J.; Vervoort, Jacques; Lewis, Kim; Hamblin, Michael R.; Tegos, George P.

    2011-01-01

    Background Traditional antibiotics are increasingly suffering from the emergence of multidrug resistance amongst pathogenic bacteria leading to a range of novel approaches to control microbial infections being investigated as potential alternative treatments. One plausible antimicrobial alternative could be the combination of conventional antimicrobial agents/antibiotics with small molecules which block multidrug efflux systems known as efflux pump inhibitors. Bioassay-driven purification and structural determination of compounds from plant sources have yielded a number of pump inhibitors which acted against gram positive bacteria. Methodology/Principal Findings In this study we report the identification and characterization of 4′,5′-O-dicaffeoylquinic acid (4′,5′-ODCQA) from Artemisia absinthium as a pump inhibitor with a potential of targeting efflux systems in a wide panel of Gram-positive human pathogenic bacteria. Separation and identification of phenolic compounds (chlorogenic acid, 3′,5′-ODCQA, 4′,5′-ODCQA) was based on hyphenated chromatographic techniques such as liquid chromatography with post column solid-phase extraction coupled with nuclear magnetic resonance spectroscopy and mass spectroscopy. Microbial susceptibility testing and potentiation of well know pump substrates revealed at least two active compounds; chlorogenic acid with weak antimicrobial activity and 4′,5′-ODCQA with pump inhibitory activity whereas 3′,5′-ODCQA was ineffective. These intitial findings were further validated with checkerboard, berberine accumulation efflux assays using efflux-related phenotypes and clinical isolates as well as molecular modeling methodology. Conclusions/Significance These techniques facilitated the direct analysis of the active components from plant extracts, as well as dramatically reduced the time needed to analyze the compounds, without the need for prior isolation. The calculated energetics of the docking poses supported the

  16. Selective inhibitory effects of niflumic acid on 5-HT-induced contraction of the rat isolated stomach fundus

    PubMed Central

    Scarparo, H C; Santos, G C M; Leal-Cardoso, J H; Criddle, D N

    2000-01-01

    The effects of niflumic acid (NFA), an inhibitor of calcium-activated chloride currents ICl(Ca), were compared with the actions of the voltage-dependent calcium channel (VDCC) blocker nifedipine on 5-hydroxtryptamine (5-HT)- and acetylcholine (ACh)-induced contractions of the rat isolated fundus.NFA (1–30 μM) elicited a concentration-dependent inhibition of contractions induced by 5-HT (10 μM) with a reduction to 15.5±6.0% of the control value at 30 μM. 1 μM nifedipine reduced 5-HT-induced contraction to 15.2±4.9% of the control, an effect not greater in the additional presence of 30 μM NFA.In contrast, the contractile response to ACh (10 μM) was not inhibited by NFA in concentrations ⩽100 μM, although this response was partly inhibited by nifedipine (1 μM) to 67.6±11.8% of the control value.NFA (1–30 μM) did not affect contraction induced by either 20 mM or 60 mM KCl, suggesting that this drug was not acting via blockade of VDCCs or activation of potassium channels. In contrast, 3,5-dichlorophenylamine-2-carboxylic acid and 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid were less selective in their inhibitory effects, inducing reductions of 60 mM KCl-induced contraction at concentrations ⩾10 μM.Our results show that NFA can exert selective inhibitory effects on the chloride-dependent 5-HT-induced contractions of the rat fundus. The data support the hypothesis that activation of Cl(Ca) channels leading to calcium entry via VDCCs is a mechanism utilized by 5-HT, but not by ACh, to elicit contraction of the rat fundus. PMID:10821798

  17. Inhibitory effects of onion (Allium cepa L.) extract on proliferation of cancer cells and adipocytes via inhibiting fatty acid synthase.

    PubMed

    Wang, Yi; Tian, Wei-Xi; Ma, Xiao-Feng

    2012-01-01

    Onions (Allium cepa L.) are widely used in the food industry for its nutritional and aromatic properties. Our studies showed that ethyl acetate extract of onion (EEO) had potent inhibitory effects on animal fatty acid synthase (FAS), and could induce apoptosis in FAS over-expressing human breast cancer MDA-MB-231 cells. Furthermore, this apoptosis was accompanied by reduction of intracellular FAS activity and could be rescued by 25 mM or 50 mM exogenous palmitic acids, the final product of FAS catalyzed synthesis. These results suggest that the apoptosis induced by EEO occurs via inhibition of FAS. We also found that EEO could suppress lipid accumulation during the differentiation of 3T3-L1 adipocytes, which was also related to its inhibition of intracellular FAS activity. Since obesity is closely related to breast cancer and obese patients are at elevated risk of developing various cancers, these findings suggested that onion might be useful for preventing obesity-related malignancy.

  18. Identifying inhibitory effects of lignocellulosic by-products on growth of lactic acid producing micro-organisms using a rapid small-scale screening method.

    PubMed

    van der Pol, Edwin C; Vaessen, Evelien; Weusthuis, Ruud A; Eggink, Gerrit

    2016-06-01

    Sugars obtained from pretreated lignocellulose are interesting as substrate for the production of lactic acid in fermentation processes. However, by-products formed during pretreatment of lignocellulose can inhibit microbial growth. In this study, a small-scale rapid screening method was used to identify inhibitory effects of single and combined by-products on growth of lactic acid producing micro-organisms. The small-scale screening was performed in 48-well plates using 5 bacterial species and 12 by-products. Large differences were observed in inhibitory effects of by-products between different species. Predictions can be made for growth behaviour of different micro-organisms on acid pretreated or alkaline pretreated bagasse substrates using data from the small-scale screening. Both individual and combined inhibition effects were shown to be important parameters to predict growth. Synergy between coumaric acid, formic acid and acetic acid is a key inhibitory parameter in alkaline pretreated lignocellulose, while furfural is a key inhibitor in acid pretreated lignocellulose.

  19. Pretreatment with anti-oxidants sensitizes oxidatively stressed human cancer cells to growth inhibitory effect of suberoylanilide hydroxamic acid (SAHA)

    PubMed Central

    Mahlum, Amy; Mehraein-Ghomi, Farideh; Kegel, Stacy J.; Guo, Song; Peters, Noel R.; Wilding, George

    2013-01-01

    Purpose Most prostate, colon and breast cancer cells are resistant to growth inhibitory effects of suberoylanilide hydroxamic acid (SAHA). We have examined whether the high oxidative stress in these cells causes a loss of SAHA activity and if so, whether pretreatment with an anti-oxidant can sensitize these cells to SAHA. Methods A DNA-Hoechst dye fluorescence measured cell growth and dichlorfluorescein-diacetate (DCF-DA) dye fluorescence measured reactive oxygen species (ROS). Growth inhibitory and ROS-generating activities of SAHA in androgen-treated or untreated LNCaP cells and PC-3 prostate cancer cells, HT-29 and HCT-115 colon cancer cells, MDA-MB231 breast cancer cells and A549 and NCI-H460 lung cancer cells with or without pretreatment with an anti-oxidant Vitamin E was determined. SAHA activity against LNCaP cells treated with another anti-oxidant N-acetyl cysteine (NAC) was also determined. Liquid chromatography–mass spectrometry (LC–MS) was used to determine intracellular SAHA level. Results SAHA treatment markedly inhibits LNCaP cell growth, when the cells are at a low ROS level. SAHA is, however, inactive against the same cell line, when the cells are at a high ROS level. A significant decrease in SAHA level was observed in LNCaP cells with high ROS after 24-and 72-h treatment when compared to cells with low ROS. Vitamin E pretreatment that reduces cellular ROS, synergistically sensitizes oxidatively stressed LNCaP, PC-3, HT-29, HCT-115 and MDA-MB231 cells, but not the A-549 and NCI-H460 cells with low ROS to SAHA. NAC treatment also sensitized androgen-treated LNCaP cells to the growth inhibitory effects of SAHA. Conclusion Response to SAHA could be improved by combining anti-oxidants such as Vitamin E with SAHA for the treatment of oxidatively stressed human malignancies that are otherwise resistant to SAHA. PMID:20512578

  20. Excitatory actions of GABA in the intact neonatal rodent hippocampus in vitro

    PubMed Central

    Valeeva, Guzel; Valiullina, Fliza; Khazipov, Roustem

    2013-01-01

    The excitatory action of gamma-aminobutyric acid (GABA) is considered to be a hallmark of the developing nervous system. However, in immature brain slices, excitatory GABA actions may be secondary to neuronal injury during slice preparation. Here, we explored GABA actions in the rodent intact hippocampal preparations and at different depths of hippocampal slices during the early post-natal period [post-natal days (P) 1–7]. We found that in the intact hippocampus at P1–3: (i) GABA exerts depolarizing action as seen in cell-attached single GABA(A) channel recordings; (ii) GABA(A) receptor (GABA(A)-R) agonist isoguvacine and synaptic activation of the GABA(A)-Rs increase the frequency of multiple unit activity and the frequency of the network-driven giant depolarizing potentials (GDPs); and that (iii) Na+–K+–2Cl- cotransporter (NKCC1) antagonist bumetanide suppresses GDPs and the excitatory actions of isoguvacine. In the hippocampal slices at P2–5, isoguvacine and synaptic activation of GABA(A)-Rs-evoked excitatory responses at all slice depths, including surface and core. Thus, GABA exerts excitatory actions in the intact hippocampus (P1–3) and at all depths of hippocampal slices (P2–5). Therefore, the excitatory actions of GABA in hippocampal slices during the first post-natal days are not due to neuronal injury during slice preparation, and the trauma-related excitatory GABA actions at the slice surface are a fundamentally different phenomenon observed during the second post-natal week. PMID:23467988

  1. Inhibitory mechanism of dimercaptopropanesulfonic acid (DMPS) in the cellular biomethylation of arsenic.

    PubMed

    Wang, Shuping; Shi, Nan; Geng, Zhirong; Li, Xiangli; Hu, Xin; Wang, Zhilin

    2014-11-01

    Dimercaptopropanesulfonic acid (DMPS) has been approved for the treatment of arsenic poisoning through promoting arsenic excretion and modulating arsenic species. To clarify how DMPS regulates the excretion of arsenic species, we investigated the effects of DMPS on the biomethylation of arsenite (As(3+)) in HepG2 cells. In the experiments, we found that DMPS at low concentrations dramatically decreased the content of arsenic in HepG2 cells and inhibited the cellular methylation of As(3+). Three aspects, the expression of human arsenic (III) methyltransferase (hAS3MT), the accumulation of cellular reactive oxygen species (ROS) and the in vitro enzymatic methylation of arsenic, were considered to explain the reasons for the inhibition of DMPS in arsenic metabolism. The results suggested that DMPS competitively coordinated with As(3+) and monomethylarsonous acid (MMA(3+)) to inhibit the up-regulation of arsenic on the expression of hAS3MT and block arsenic involving in the enzymatic methylation. Moreover, DMPS eliminated arsenic-induced accumulation of ROS, which might contribute to the antidotal effects of DMPS on arsenic posing.

  2. Inhibitory effect of glutamic acid on the scale formation process using electrochemical methods.

    PubMed

    Karar, A; Naamoune, F; Kahoul, A; Belattar, N

    2016-08-01

    The formation of calcium carbonate CaCO3 in water has some important implications in geoscience researches, ocean chemistry studies, CO2 emission issues and biology. In industry, the scaling phenomenon may cause technical problems, such as reduction in heat transfer efficiency in cooling systems and obstruction of pipes. This paper focuses on the study of the glutamic acid (GA) for reducing CaCO3 scale formation on metallic surfaces in the water of Bir Aissa region. The anti-scaling properties of glutamic acid (GA), used as a complexing agent of Ca(2+) ions, have been evaluated by the chronoamperometry and electrochemical impedance spectroscopy methods in conjunction with a microscopic examination. Chemical and electrochemical study of this water shows a high calcium concentration. The characterization using X-ray diffraction reveals that while the CaCO3 scale formed chemically is a mixture of calcite, aragonite and vaterite, the one deposited electrochemically is a pure calcite. The effect of temperature on the efficiency of the inhibitor was investigated. At 30 and 40°C, a complete scaling inhibition was obtained at a GA concentration of 18 mg/L with 90.2% efficiency rate. However, the efficiency of GA decreased at 50 and 60°C.

  3. Hyperpolarization-independent maturation and refinement of GABA/glycinergic connections in the auditory brain stem

    PubMed Central

    Lee, Hanmi; Bach, Eva; Noh, Jihyun; Delpire, Eric

    2015-01-01

    During development GABA and glycine synapses are initially excitatory before they gradually become inhibitory. This transition is due to a developmental increase in the activity of neuronal potassium-chloride cotransporter 2 (KCC2), which shifts the chloride equilibrium potential (ECl) to values more negative than the resting membrane potential. While the role of early GABA and glycine depolarizations in neuronal development has become increasingly clear, the role of the transition to hyperpolarization in synapse maturation and circuit refinement has remained an open question. Here we investigated this question by examining the maturation and developmental refinement of GABA/glycinergic and glutamatergic synapses in the lateral superior olive (LSO), a binaural auditory brain stem nucleus, in KCC2-knockdown mice, in which GABA and glycine remain depolarizing. We found that many key events in the development of synaptic inputs to the LSO, such as changes in neurotransmitter phenotype, strengthening and elimination of GABA/glycinergic connection, and maturation of glutamatergic synapses, occur undisturbed in KCC2-knockdown mice compared with wild-type mice. These results indicate that maturation of inhibitory and excitatory synapses in the LSO is independent of the GABA and glycine depolarization-to-hyperpolarization transition. PMID:26655825

  4. Amiloride and GMQ Allosteric Modulation of the GABA-A ρ1 Receptor: Influences of the Intersubunit Site

    PubMed Central

    Snell, Heather D.

    2015-01-01

    Amiloride, a diuretic used in the treatment of hypertension and congestive heart failure, and 2-guanidine-4-methylquinazoline (GMQ) are guanidine compounds that modulate acid-sensing ion channels. Both compounds have demonstrated affinity for a variety of membrane proteins, including members of the Cys-loop family of ligand-gated ion channels, such as the heteromeric GABA-A αβγ receptors. The actions of these guanidine compounds on the homomeric GABA-A ρ1 receptor remains unclear, especially in light of how many GABA-A αβγ receptor modulators have different effects in the GABA-A ρ1 receptors. We sought to characterize the influence of amiloride and GMQ on the human GABA-A ρ1 receptors using whole-cell patch-clamp electrophysiology. The diuretic amiloride potentiated the human GABA-A ρ1 GABA-mediated current, whereas GMQ antagonized the receptor. Furthermore, a GABA-A second transmembrane domain site, the intersubunit site, responsible for allosteric modulation in the heteromeric GABA-A receptors mediated amiloride’s positive allosteric actions. In contrast, the mutation did not remove GMQ antagonism but only changed the guanidine compound’s potency within the human GABA-A ρ1 receptor. Through modeling and introduction of point mutations, we propose that the GABA-A ρ1 intersubunit site plays a role in mediating the allosteric effects of amiloride and GMQ. PMID:25829529

  5. Amiloride and GMQ Allosteric Modulation of the GABA-A ρ1 Receptor: Influences of the Intersubunit Site.

    PubMed

    Snell, Heather D; Gonzales, Eric B

    2015-06-01

    Amiloride, a diuretic used in the treatment of hypertension and congestive heart failure, and 2-guanidine-4-methylquinazoline (GMQ) are guanidine compounds that modulate acid-sensing ion channels. Both compounds have demonstrated affinity for a variety of membrane proteins, including members of the Cys-loop family of ligand-gated ion channels, such as the heteromeric GABA-A αβγ receptors. The actions of these guanidine compounds on the homomeric GABA-A ρ1 receptor remains unclear, especially in light of how many GABA-A αβγ receptor modulators have different effects in the GABA-A ρ1 receptors. We sought to characterize the influence of amiloride and GMQ on the human GABA-A ρ1 receptors using whole-cell patch-clamp electrophysiology. The diuretic amiloride potentiated the human GABA-A ρ1 GABA-mediated current, whereas GMQ antagonized the receptor. Furthermore, a GABA-A second transmembrane domain site, the intersubunit site, responsible for allosteric modulation in the heteromeric GABA-A receptors mediated amiloride's positive allosteric actions. In contrast, the mutation did not remove GMQ antagonism but only changed the guanidine compound's potency within the human GABA-A ρ1 receptor. Through modeling and introduction of point mutations, we propose that the GABA-A ρ1 intersubunit site plays a role in mediating the allosteric effects of amiloride and GMQ.

  6. In vitro and in vivo studies on adlay-derived seed extracts: phenolic profiles, antioxidant activities, serum uric acid suppression, and xanthine oxidase inhibitory effects.

    PubMed

    Zhao, Mouming; Zhu, Dashuai; Sun-Waterhouse, Dongxiao; Su, Guowan; Lin, Lianzhu; Wang, Xiao; Dong, Yi

    2014-08-06

    This study aimed to explore the potential of polished adlay, brown adlay, adlay bran, and adlay hull to prevent and treat hyperuricemia. Brown adlay extract effectively decreased the serum uric acid levels of oxonate-induced hyperuricemic rats. Free and bound phenolic extracts from these materials contained significant amounts of phenolics, with free phenolics dominated by chlorogenic acid and p-coumaric acid while bound phenolics dominated by p-coumaric acid and ferulic acid. Free and bound phenolics of adlay bran exhibited significant xanthine oxidase inhibition activities, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, oxygen radical absorbance capacities, and superoxide radical scavenging activities. Adlay bran phenolics could be effective xanthine oxidase inhibitors and radical scavengers. p-Coumaric acid is a xanthine oxidase inhibitor with strong superoxide radical scavenging activity. However, ferulic acid is a xanthine oxidase inhibitor with weak superoxide radical scavenging activity. Chlorogenic acid is a superoxide radical scavenger with weak xanthine oxidase inhibitory activity.

  7. A Comparison of the In Vitro Inhibitory Effects of Thelephoric Acid and SKF-525A on Human Cytochrome P450 Activity.

    PubMed

    Song, Min; Do, Hyunhee; Kwon, Oh Kwang; Yang, Eun-Ju; Bae, Jong-Sup; Jeong, Tae Cheon; Song, Kyung-Sik; Lee, Sangkyu

    2014-02-01

    Thelephoric acid is an antioxidant produced by the hydrolysis of polyozellin, which is isolated from Polyozellus multiplex. In the present study, the inhibitory effects of polyozellin and thelephoric acid on 9 cytochrome P450 (CYP) family members (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4) were examined in pooled human liver microsomes (HLMs) using a cocktail probe assay. Polyozellin exhibited weak inhibitory effects on the activities of all 9 CYPs examined, whereas thelephoric