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Sample records for acid gabaergic neurons

  1. Regulation of Substantia Nigra Pars Reticulata GABAergic Neuron Activity by H2O2 via Flufenamic Acid-Sensitive Channels and KATP Channels

    PubMed Central

    Lee, Christian R.; Witkovsky, Paul; Rice, Margaret E.

    2011-01-01

    Substantia nigra pars reticulata (SNr) GABAergic neurons are key output neurons of the basal ganglia. Given the role of these neurons in motor control, it is important to understand factors that regulate their firing rate and pattern. One potential regulator is hydrogen peroxide (H2O2), a reactive oxygen species that is increasingly recognized as a neuromodulator. We used whole-cell current clamp recordings of SNr GABAergic neurons in guinea-pig midbrain slices to determine how H2O2 affects the activity of these neurons and to explore the classes of ion channels underlying those effects. Elevation of H2O2 levels caused an increase in the spontaneous firing rate of SNr GABAergic neurons, whether by application of exogenous H2O2 or amplification of endogenous H2O2 through inhibition of glutathione peroxidase with mercaptosuccinate. This effect was reversed by flufenamic acid (FFA), implicating transient receptor potential (TRP) channels. Conversely, depletion of endogenous H2O2 by catalase, a peroxidase enzyme, decreased spontaneous firing rate and firing precision of SNr neurons, demonstrating tonic control of firing rate by H2O2. Elevation of H2O2 in the presence of FFA revealed an inhibition of tonic firing that was prevented by blockade of ATP-sensitive K+ (KATP) channels with glibenclamide. In contrast to guinea-pig SNr neurons, the dominant effect of H2O2 elevation in mouse SNr GABAergic neurons was hyperpolarization, indicating a species difference in H2O2-dependent regulation. Thus, H2O2 is an endogenous modulator of SNr GABAergic neurons, acting primarily through presumed TRP channels in guinea-pig SNr, with additional modulation via KATP channels to regulate SNr output. PMID:21503158

  2. Glutamatergic or GABAergic neuron-specific, long-term expression in neocortical neurons from helper virus-free HSV-1 vectors containing the phosphate-activated glutaminase, vesicular glutamate transporter-1, or glutamic acid decarboxylase promoter.

    PubMed

    Rasmussen, Morten; Kong, Lingxin; Zhang, Guo-rong; Liu, Meng; Wang, Xiaodan; Szabo, Gabor; Curthoys, Norman P; Geller, Alfred I

    2007-05-01

    Many potential uses of direct gene transfer into neurons require restricting expression to one of the two major types of forebrain neurons, glutamatergic or GABAergic neurons. Thus, it is desirable to develop virus vectors that contain either a glutamatergic or GABAergic neuron-specific promoter. The brain/kidney phosphate-activated glutaminase (PAG), the product of the GLS1 gene, produces the majority of the glutamate for release as neurotransmitter, and is a marker for glutamatergic neurons. A PAG promoter was partially characterized using a cultured kidney cell line. The three vesicular glutamate transporters (VGLUTs) are expressed in distinct populations of neurons, and VGLUT1 is the predominant VGLUT in the neocortex, hippocampus, and cerebellar cortex. Glutamic acid decarboxylase (GAD) produces GABA; the two molecular forms of the enzyme, GAD65 and GAD67, are expressed in distinct, but largely overlapping, groups of neurons, and GAD67 is the predominant form in the neocortex. In transgenic mice, an approximately 9 kb fragment of the GAD67 promoter supports expression in most classes of GABAergic neurons. Here, we constructed plasmid (amplicon) Herpes Simplex Virus (HSV-1) vectors that placed the Lac Z gene under the regulation of putative PAG, VGLUT1, or GAD67 promoters. Helper virus-free vector stocks were delivered into postrhinal cortex, and the rats were sacrificed 4 days or 2 months later. The PAG or VGLUT1 promoters supported approximately 90% glutamatergic neuron-specific expression. The GAD67 promoter supported approximately 90% GABAergic neuron-specific expression. Long-term expression was observed using each promoter. Principles for obtaining long-term expression from HSV-1 vectors, based on these and other results, are discussed. Long-term glutamatergic or GABAergic neuron-specific expression may benefit specific experiments on learning or specific gene therapy approaches. Of note, promoter analyses might identify regulatory elements that determine

  3. Control of REM sleep by ventral medulla GABAergic neurons.

    PubMed

    Weber, Franz; Chung, Shinjae; Beier, Kevin T; Xu, Min; Luo, Liqun; Dan, Yang

    2015-10-15

    Rapid eye movement (REM) sleep is a distinct brain state characterized by activated electroencephalogram and complete skeletal muscle paralysis, and is associated with vivid dreams. Transection studies by Jouvet first demonstrated that the brainstem is both necessary and sufficient for REM sleep generation, and the neural circuits in the pons have since been studied extensively. The medulla also contains neurons that are active during REM sleep, but whether they play a causal role in REM sleep generation remains unclear. Here we show that a GABAergic (γ-aminobutyric-acid-releasing) pathway originating from the ventral medulla powerfully promotes REM sleep in mice. Optogenetic activation of ventral medulla GABAergic neurons rapidly and reliably initiated REM sleep episodes and prolonged their durations, whereas inactivating these neurons had the opposite effects. Optrode recordings from channelrhodopsin-2-tagged ventral medulla GABAergic neurons showed that they were most active during REM sleep (REMmax), and during wakefulness they were preferentially active during eating and grooming. Furthermore, dual retrograde tracing showed that the rostral projections to the pons and midbrain and caudal projections to the spinal cord originate from separate ventral medulla neuron populations. Activating the rostral GABAergic projections was sufficient for both the induction and maintenance of REM sleep, which are probably mediated in part by inhibition of REM-suppressing GABAergic neurons in the ventrolateral periaqueductal grey. These results identify a key component of the pontomedullary network controlling REM sleep. The capability to induce REM sleep on command may offer a powerful tool for investigating its functions. PMID:26444238

  4. Control of REM sleep by ventral medulla GABAergic neurons.

    PubMed

    Weber, Franz; Chung, Shinjae; Beier, Kevin T; Xu, Min; Luo, Liqun; Dan, Yang

    2015-10-15

    Rapid eye movement (REM) sleep is a distinct brain state characterized by activated electroencephalogram and complete skeletal muscle paralysis, and is associated with vivid dreams. Transection studies by Jouvet first demonstrated that the brainstem is both necessary and sufficient for REM sleep generation, and the neural circuits in the pons have since been studied extensively. The medulla also contains neurons that are active during REM sleep, but whether they play a causal role in REM sleep generation remains unclear. Here we show that a GABAergic (γ-aminobutyric-acid-releasing) pathway originating from the ventral medulla powerfully promotes REM sleep in mice. Optogenetic activation of ventral medulla GABAergic neurons rapidly and reliably initiated REM sleep episodes and prolonged their durations, whereas inactivating these neurons had the opposite effects. Optrode recordings from channelrhodopsin-2-tagged ventral medulla GABAergic neurons showed that they were most active during REM sleep (REMmax), and during wakefulness they were preferentially active during eating and grooming. Furthermore, dual retrograde tracing showed that the rostral projections to the pons and midbrain and caudal projections to the spinal cord originate from separate ventral medulla neuron populations. Activating the rostral GABAergic projections was sufficient for both the induction and maintenance of REM sleep, which are probably mediated in part by inhibition of REM-suppressing GABAergic neurons in the ventrolateral periaqueductal grey. These results identify a key component of the pontomedullary network controlling REM sleep. The capability to induce REM sleep on command may offer a powerful tool for investigating its functions.

  5. Corticofugal GABAergic projection neurons in the mouse frontal cortex

    PubMed Central

    Tomioka, Ryohei; Sakimura, Kenji; Yanagawa, Yuchio

    2015-01-01

    Cortical projection neurons are classified by hodology in corticocortical, commissural and corticofugal subtypes. Although cortical projection neurons had been regarded as only glutamatergic neurons, recently corticocortical GABAergic projection neurons has been also reported in several species. Here, we demonstrate corticofugal GABAergic projection neurons in the mouse frontal cortex. We employed viral-vector-mediated anterograde tracing, classical retrograde tracing, and immunohistochemistry to characterize neocortical GABAergic projection neurons. Injections of the Cre-dependent adeno-associated virus into glutamate decarboxylase 67 (GAD67)-Cre knock-in mice revealed neocortical GABAergic projections widely to the forebrain, including the cerebral cortices, caudate putamen (CPu), ventral pallidum (VP), lateral globus pallidus (LGP), nucleus accumbens, and olfactory tubercle (Tu). Minor GABAergic projections were also found in the mediodorsal thalamic nucleus, diagonal band of Broca, medial globus pallidus, substantial nigra, and dorsal raphe nucleus. Retrograde tracing studies also demonstrated corticofugal GABAergic projection neurons in the mouse frontal cortex. Further immunohistochemical screening with neurochemical markers revealed the majority of corticostriatal GABAergic projection neurons were positive for somatostatin (SS)-immunoreactivity. In contrast, corticothalamic GABAergic projection neurons were not identified by representative neurochemical markers for GABAergic neurons. These findings suggest that corticofugal GABAergic projection neurons are heterogeneous in terms of their neurochemical properties and target nuclei, and provide axonal innervations mainly to the nuclei in the basal ganglia. PMID:26578895

  6. Distribution of GABAergic neurons and terminals in the auditory system of the barn owl.

    PubMed

    Carr, C E; Fujita, I; Konishi, M

    1989-08-01

    Antisera to GAD (glutamic acid decarboxylase) and GABA were used to determine the distribution of GABAergic cells and terminals in the brainstem and midbrain auditory nuclei of the barn owl. The owl processes time and intensity components of the auditory signal in separate pathways, and each pathway has a distinctive pattern of GAD- and GABA-like immunoreactivity. In the time pathway, all the cells of the cochlear nucleus magnocellularis and nucleus laminaris receive perisomatic GABAergic terminals, and small numbers of GABAergic neurons surround both nuclei. The ventral nucleus of the lateral lemniscus (anterior division) contains both immunoreactive terminals and some GABAergic neurons. In the intensity pathway, dense immunoreactive terminals are distributed throughout the cochlear nucleus angularis, which also contains a small number of GABAergic neurons. The superior olive contains two GABAergic cell types and immunoreactive terminals distributed throughout the neuropil. All the neurons of the nucleus of the lateral lemniscus (ventral part) appear to be GABAergic, and this nucleus also contains a moderate number of immunoreactive terminals. Immunoreactive terminals are distributed throughout the neuropil of the ventral nucleus of the lateral lemniscus (posterior division), whereas multipolar and small fusiform GABAergic neurons predominate in the dorsal regions of the nucleus. The time and intensity pathways combine in the inferior colliculus. The central nucleus of the inferior colliculus contains a larger number of fusiform and stellate GABAergic neurons and a dense plexus of immunoreactive terminals, whereas the external nucleus contains slightly fewer immunoreactive cells and terminals. The superficial nucleus contains dense, fine immunoreactive terminals and a small number of GABAergic neurons. PMID:2794115

  7. Localization of the GABAergic and non-GABAergic neurons projecting to the sublaterodorsal nucleus and potentially gating paradoxical sleep onset.

    PubMed

    Boissard, Romuald; Fort, Patrice; Gervasoni, Damien; Barbagli, Bruno; Luppi, Pierre-Hervé

    2003-09-01

    We recently determined in rats that iontophoretic application of bicuculline or gabazine [two GABAa antagonists] and kainic acid (a glutamate agonist) in the sublaterodorsal nucleus (SLD) induces with a very short latency a paradoxical sleep-like state. From these results, we proposed that GABAergic and glutamatergic inputs to the SLD paradoxical sleep (PS)-executive neurons gate the onset of PS [R. Boissard et al. (2002) Eur. J. Neurosci., 16, 1959-1973]. We therefore decided to determine the origin of the GABAergic and non-GABAergic inputs to the SLD combining ejection of a retrograde tracer [cholera-toxin B subunit (CTb)] with glutamate decarboxylase (GAD) immunohistochemistry. The presence of GAD-immunoreactive neurons in the SLD was confirmed. Then, following CTb ejections centred on the SLD, combined with GAD and CTb immunohistochemistry, double-labelled cells were observed in the mesencephalic and pontine reticular nuclei and to a lesser extent the parvicellular reticular nucleus. A large number of GAD-negative retrogradely labelled cells was also seen in these structures as well as in the primary motor area of the frontal cortex, the central nucleus of the amygdala, the ventral and lateral bed nucleus of the stria terminalis, the lateral hypothalamic area, the lateral and ventrolateral periaqueductal grey and the lateral paragigantocellular reticular nucleus. From these results, we propose that the activation of PS-executive neurons from the SLD is due to the removal of a tonic inhibition from GABAergic neurons localized in the SLD, and the mesencephalic and pontine reticular nuclei. Strong non-GABAergic inputs to the SLD could be excitatory and responsible for the tonic glutamatergic input on the PS-on neurons we have previously described. They could also terminate on SLD GABAergic interneurons and be indirectly responsible for the inhibition of the PS-on neurons during waking and slow-wave sleep.

  8. GABAergic Somatostatin-immunoreactive Neurons in the Amygdala Project to the Entorhinal Cortex

    PubMed Central

    McDonald, Alexander J.; Zaric, Violeta

    2015-01-01

    The entorhinal cortex and other hippocampal and parahippocampal cortices are interconnected by a small number of GABAergic nonpyramidal neurons in addition to glutamatergic pyramidal cells. Since the cortical and basolateral amygdalar nuclei have cortex-like cell types and have robust projections to the entorhinal cortex, we hypothesized that a small number of amygdalar GABAergic nonpyramidal neurons might participate in amygdalo-entorhinal projections. To test this hypothesis we combined Fluorogold (FG) retrograde tract tracing with immunohistochemistry for the amygdalar nonpyramidal cell markers glutamic acid decarboxylase (GAD), parvalbumin (PV), somatostatin (SOM), neuropeptide Y (NPY), vasoactive intestinal peptide (VIP), and the m2 muscarinic cholinergic receptor (M2R). Injections of FG into the rat entorhinal cortex labeled numerous neurons that were mainly located in the cortical and basolateral nuclei of the amygdala. Although most of these amygdalar FG+ neurons labeled by entorhinal injections were large pyramidal cells, 1–5% were smaller long-range nonpyramidal neurons (LRNP neurons) that expressed SOM, or both SOM and NPY. No amygdalar FG+ neurons in these cases were PV+ or VIP+. Cell counts revealed that LRNP neurons labeled by injections into the entorhinal cortex constituted about 10–20% of the total SOM+ population, and 20–40% of the total NPY population in portions of the lateral amygdalar nucleus that exhibited a high density of FG+ neurons. Sixty-two percent of amygdalar FG+/SOM+ neurons were GAD+, and 51% were M2R+. Since GABAergic projection neurons typically have low perikaryal levels of GABAergic markers, it is actually possible that most or all of the amygdalar LRNP neurons are GABAergic. Like GABAergic LRNP neurons in hippocampal/parahippocampal regions, amygdalar LRNP neurons that project to the entorhinal cortex are most likely involved in synchronizing oscillatory activity between the two regions. These oscillations could entrain

  9. GABAergic innervation organizes synaptic and extrasynaptic GABAA receptor clustering in cultured hippocampal neurons.

    PubMed

    Christie, Sean B; Miralles, Celia P; De Blas, Angel L

    2002-02-01

    We have studied the effects of GABAergic innervation on the clustering of GABA(A) receptors (GABA(A)Rs) in cultured hippocampal neurons. In the absence of GABAergic innervation, pyramidal cells form small (0.36 +/- 0.01 micrometer diameter) GABA(A)R clusters at their surface in the dendrites and soma. When receiving GABAergic innervation from glutamic acid decarboxylase-containing interneurons, pyramidal cells form large (1.62 +/- 0.08 micrometer breadth) GABA(A)R clusters at GABAergic synapses. This is accompanied by a disappearance of the small GABA(A)R clusters in the local area surrounding each GABAergic synapse. Although the large synaptic GABA(A)R clusters of any neuron contained all GABA(A)R subunits and isoforms expressed by that neuron, the small clusters not localized at GABAergic synapses showed significant heterogeneity in subunit and isoform composition. Another difference between large GABAergic and small non-GABAergic GABA(A)R clusters was that a significant proportion of the latter was juxtaposed to postsynaptic markers of glutamatergic synapses such as PSD-95 and AMPA receptor GluR1 subunit. The densities of both the glutamate receptor-associated and non-associated small GABA(A)R clusters were decreased in areas surrounding GABAergic synapses. However, no effect on the density or distribution of glutamate receptor clusters was observed. The results suggest that there are local signals generated at GABAergic synapses that induce both assembly of large synaptic GABA(A)R clusters at the synapse and disappearance of the small GABA(A)R clusters in the surrounding area. In the absence of GABAergic innervation, weaker GABA(A)R-clustering signals, generated at glutamatergic synapses, induce the formation of small postsynaptic GABA(A)R clusters that remain juxtaposed to glutamate receptors at glutamatergic synapses.

  10. CO2-inhibited neurons in the medullary raphé are GABAergic

    PubMed Central

    Iceman, Kimberly E.; Corcoran, Andrea E.; Taylor, Barbara E.; Harris, Michael B.

    2014-01-01

    Previous studies have reported subsets of medullary raphé neurons that are either stimulated or inhibited by CO2/pH in vitro, in situ, and in vivo. We tested the hypothesis that medullary raphé CO2-inhibited neurons are GABAergic. Extracellular recordings in unanesthetized juvenile in situ rat preparations showed reversible hypercapnia-induced suppression of 19% (63/323) of medullary raphé neurons, and this suppression persisted after antagonism of NMDA, AMPA/kainate, and GABAA receptors. We stained a subset of CO2-inhibited cells and found that most (11/12) had glutamic acid decarboxylase 67 immunoreactivity (GAD67-ir). These data indicate that the majority of acidosis-inhibited medullary raphé neurons are GABAergic, and that their chemosensitivity is independent of major fast synaptic inputs. Thus, CO2-sensitive GABAergic neurons may play a role in central CO2/pH chemoreception. PMID:25087734

  11. CO2-inhibited neurons in the medullary raphé are GABAergic.

    PubMed

    Iceman, Kimberly E; Corcoran, Andrea E; Taylor, Barbara E; Harris, Michael B

    2014-11-01

    Previous studies have reported subsets of medullary raphé neurons that are either stimulated or inhibited by CO2/pH in vitro, in situ, and in vivo. We tested the hypothesis that medullary raphé CO2-inhibited neurons are GABAergic. Extracellular recordings in unanesthetized juvenile in situ rat preparations showed reversible hypercapnia-induced suppression of 19% (63/323) of medullary raphé neurons, and this suppression persisted after antagonism of NMDA, AMPA/kainate, and GABAA receptors. We stained a subset of CO2-inhibited cells and found that most (11/12) had glutamic acid decarboxylase 67 immunoreactivity (GAD67-ir). These data indicate that the majority of acidosis-inhibited medullary raphé neurons are GABAergic, and that their chemosensitivity is independent of major fast synaptic inputs. Thus, CO2-sensitive GABAergic neurons may play a role in central CO2/pH chemoreception.

  12. Role of the NR2A/2B subunits of the N-methyl-D-aspartate receptor in glutamate-induced glutamic acid decarboxylase alteration in cortical GABAergic neurons in vitro.

    PubMed

    Monnerie, H; Hsu, F-C; Coulter, D A; Le Roux, P D

    2010-12-29

    The vulnerability of brain neuronal cell subpopulations to neurologic insults varies greatly. Among cells that survive a pathological insult, for example ischemia or brain trauma, some may undergo morphological and/or biochemical changes that may compromise brain function. The present study is a follow-up of our previous studies that investigated the effect of glutamate-induced excitotoxicity on the GABA synthesizing enzyme glutamic acid decarboxylase (GAD65/67)'s expression in surviving DIV 11 cortical GABAergic neurons in vitro [Monnerie and Le Roux, (2007) Exp Neurol 205:367-382, (2008) Exp Neurol 213:145-153]. An N-methyl-D-aspartate receptor (NMDAR)-mediated decrease in GAD expression was found following glutamate exposure. Here we examined which NMDAR subtype(s) mediated the glutamate-induced change in GAD protein levels. Western blotting techniques on cortical neuron cultures showed that glutamate's effect on GAD proteins was not altered by NR2B-containing diheteromeric (NR1/NR2B) receptor blockade. By contrast, blockade of triheteromeric (NR1/NR2A/NR2B) receptors fully protected against a decrease in GAD protein levels following glutamate exposure. When receptor location on the postsynaptic membrane was examined, extrasynaptic NMDAR stimulation was observed to be sufficient to decrease GAD protein levels similar to that observed after glutamate bath application. Blocking diheteromeric receptors prevented glutamate's effect on GAD proteins after extrasynaptic NMDAR stimulation. Finally, NR2B subunit examination with site-specific antibodies demonstrated a glutamate-induced, calpain-mediated alteration in NR2B expression. These results suggest that glutamate-induced excitotoxic NMDAR stimulation in cultured GABAergic cortical neurons depends upon subunit composition and receptor location (synaptic vs. extrasynaptic) on the neuronal membrane. Biochemical alterations in surviving cortical GABAergic neurons in various disease states may contribute to the altered

  13. Control of REM Sleep by Ventral Medulla GABAergic Neurons

    PubMed Central

    Weber, Franz; Chung, Shinjae; Beier, Kevin T.; Luo, Liqun; Dan, Yang

    2015-01-01

    Rapid eye movement (REM) sleep is a distinct brain state characterized by activated electroencephalogram (EEG) and complete skeletal muscle paralysis, and it is associated with vivid dreams1-3. Transection studies by Jouvet first demonstrated that the brainstem is both necessary and sufficient for REM sleep generation2, and the neural circuits in the pons have since been studied extensively4-8. The medulla also contains neurons that are active during REM sleep9-13, but whether they play a causal role in REM sleep generation remains unclear. Here we show that a GABAergic pathway originating from the ventral medulla (vM) powerfully promotes REM sleep. Optogenetic activation of vM GABAergic neurons rapidly and reliably initiated REM sleep episodes and prolonged their durations, whereas inactivating these neurons had the opposite effects. Optrode recordings from channelrhodopsin 2 (ChR2)-tagged vM GABAergic neurons showed that they were most active during REM sleep (REM-max), and during wakefulness they were preferentially active during eating and grooming. Furthermore, dual retrograde tracing showed that the rostral projections to the pons and midbrain and caudal projections to the spinal cord originate from separate vM neuron populations. Activating the rostral GABAergic projections was sufficient for both the induction and maintenance of REM sleep, which are likely mediated in part by inhibition of REM-suppressing GABAergic neurons in the ventrolateral periaqueductal gray (vlPAG). These results identify a key component of the pontomedullary network controlling REM sleep. The capability to induce REM sleep on command may offer a powerful tool for investigating its functions. PMID:26444238

  14. Lineage origins of GABAergic versus glutamatergic neurons in the neocortex

    PubMed Central

    Marín, Oscar; Müller, Ulrich

    2014-01-01

    Summary Neocortical circuits are assembled from subtypes of glutamatergic excitatory and GABAergic inhibitory neurons with divergent anatomical and molecular signatures and unique physiological properties. Excitatory neurons derive from progenitors in the pallium, whereas inhibitory neurons originate from progenitors in the subpallium. Both classes of neurons subsequently migrate along well-defined routes to their final target area, where they integrate into common neuronal circuits. Recent findings show that neuronal diversity within the lineages of excitatory and inhibitory neurons is in part already established at the level of progenitor cells prior to migration. This poses challenges for our understanding of how radial units of interconnected excitatory and inhibitory neurons are assembled from progenitors that are spatially segregated and diverse in nature. PMID:24549207

  15. A Transgenic Mouse Line Expressing the Red Fluorescent Protein tdTomato in GABAergic Neurons

    PubMed Central

    Besser, Stefanie; Sicker, Marit; Marx, Grit; Winkler, Ulrike; Eulenburg, Volker; Hülsmann, Swen; Hirrlinger, Johannes

    2015-01-01

    GABAergic inhibitory neurons are a large population of neurons in the central nervous system (CNS) of mammals and crucially contribute to the function of the circuitry of the brain. To identify specific cell types and investigate their functions labelling of cell populations by transgenic expression of fluorescent proteins is a powerful approach. While a number of mouse lines expressing the green fluorescent protein (GFP) in different subpopulations of GABAergic cells are available, GFP expressing mouse lines are not suitable for either crossbreeding to other mouse lines expressing GFP in other cell types or for Ca2+-imaging using the superior green Ca2+-indicator dyes. Therefore, we have generated a novel transgenic mouse line expressing the red fluorescent protein tdTomato in GABAergic neurons using a bacterial artificial chromosome based strategy and inserting the tdTomato open reading frame at the start codon within exon 1 of the GAD2 gene encoding glutamic acid decarboxylase 65 (GAD65). TdTomato expression was observed in all expected brain regions; however, the fluorescence intensity was highest in the olfactory bulb and the striatum. Robust expression was also observed in cortical and hippocampal neurons, Purkinje cells in the cerebellum, amacrine cells in the retina as well as in cells migrating along the rostral migratory stream. In cortex, hippocampus, olfactory bulb and brainstem, 80% to 90% of neurons expressing endogenous GAD65 also expressed the fluorescent protein. Moreover, almost all tdTomato-expressing cells coexpressed GAD65, indicating that indeed only GABAergic neurons are labelled by tdTomato expression. This mouse line with its unique spectral properties for labelling GABAergic neurons will therefore be a valuable new tool for research addressing this fascinating cell type. PMID:26076353

  16. A Transgenic Mouse Line Expressing the Red Fluorescent Protein tdTomato in GABAergic Neurons.

    PubMed

    Besser, Stefanie; Sicker, Marit; Marx, Grit; Winkler, Ulrike; Eulenburg, Volker; Hülsmann, Swen; Hirrlinger, Johannes

    2015-01-01

    GABAergic inhibitory neurons are a large population of neurons in the central nervous system (CNS) of mammals and crucially contribute to the function of the circuitry of the brain. To identify specific cell types and investigate their functions labelling of cell populations by transgenic expression of fluorescent proteins is a powerful approach. While a number of mouse lines expressing the green fluorescent protein (GFP) in different subpopulations of GABAergic cells are available, GFP expressing mouse lines are not suitable for either crossbreeding to other mouse lines expressing GFP in other cell types or for Ca2+-imaging using the superior green Ca2+-indicator dyes. Therefore, we have generated a novel transgenic mouse line expressing the red fluorescent protein tdTomato in GABAergic neurons using a bacterial artificial chromosome based strategy and inserting the tdTomato open reading frame at the start codon within exon 1 of the GAD2 gene encoding glutamic acid decarboxylase 65 (GAD65). TdTomato expression was observed in all expected brain regions; however, the fluorescence intensity was highest in the olfactory bulb and the striatum. Robust expression was also observed in cortical and hippocampal neurons, Purkinje cells in the cerebellum, amacrine cells in the retina as well as in cells migrating along the rostral migratory stream. In cortex, hippocampus, olfactory bulb and brainstem, 80% to 90% of neurons expressing endogenous GAD65 also expressed the fluorescent protein. Moreover, almost all tdTomato-expressing cells coexpressed GAD65, indicating that indeed only GABAergic neurons are labelled by tdTomato expression. This mouse line with its unique spectral properties for labelling GABAergic neurons will therefore be a valuable new tool for research addressing this fascinating cell type. PMID:26076353

  17. Local Connections of Layer 5 GABAergic Interneurons to Corticospinal Neurons

    PubMed Central

    Tanaka, Yasuyo H.; Tanaka, Yasuhiro R.; Fujiyama, Fumino; Furuta, Takahiro; Yanagawa, Yuchio; Kaneko, Takeshi

    2011-01-01

    In the local circuit of the cerebral cortex, GABAergic inhibitory interneurons are considered to work in collaboration with excitatory neurons. Although many interneuron subgroups have been described in the cortex, local inhibitory connections of each interneuron subgroup are only partially understood with respect to the functional neuron groups that receive these inhibitory connections. In the present study, we morphologically examined local inhibitory inputs to corticospinal neurons (CSNs) in motor areas using transgenic rats in which GABAergic neurons expressed fluorescent protein Venus. By analysis of biocytin-filled axons obtained with whole-cell recording/staining in cortical slices, we classified fast-spiking (FS) neurons in layer (L) 5 into two types, FS1 and FS2, by their high and low densities of axonal arborization, respectively. We then investigated the connections of FS1, FS2, somatostatin (SOM)-immunopositive, and other (non-FS/non-SOM) interneurons to CSNs that were retrogradely labeled in motor areas. When close appositions between the axon boutons of the intracellularly labeled interneurons and the somata/dendrites of the retrogradely labeled CSNs were examined electron-microscopically, 74% of these appositions made symmetric synaptic contacts. The axon boutons of single FS1 neurons were two- to fourfold more frequent in appositions to the somata/dendrites of CSNs than those of FS2, SOM, and non-FS/non-SOM neurons. Axosomatic appositions were most frequently formed with axon boutons of FS1 and FS2 neurons (approximately 30%) and least frequently formed with those of SOM neurons (7%). In contrast, SOM neurons most extensively sent axon boutons to the apical dendrites of CSNs. These results might suggest that motor outputs are controlled differentially by the subgroups of L5 GABAergic interneurons in cortical motor areas. PMID:21994491

  18. Epigenetic mechanisms expressed in basal ganglia GABAergic neurons differentiate schizophrenia from bipolar disorder.

    PubMed

    Veldic, Marin; Kadriu, Bashkim; Maloku, Ekrem; Agis-Balboa, Roberto C; Guidotti, Alessandro; Davis, John M; Costa, Erminio

    2007-03-01

    In the cerebral prefrontal cortex (PFC), DNA-methyltransferase 1 (DNMT1), the enzyme that catalyzes the methylation of cytosine at carbon atoms in position 5 in CpG dinucleotides, is expressed selectively in GABAergic neurons and is upregulated in layers I and II of schizophrenia (SZ) and bipolar disorder patients with psychosis (BDP). To replicate these earlier findings and to verify whether overexpression of DNMT1 and the consequent epigenetic decrease of reelin and glutamic acid decarboxylase (GAD) 67 mRNA expression also occur in GABAergic medium spiny neurons of the caudate nucleus (CN) and putamen (PT) of SZ and BDP, we studied the entire McLean 66 Cohort (Harvard Brain Tissue Resource Center, McLean Hospital, Belmont, MA) including SZ and BDP, which were matched with nonpsychiatric subjects. The data demonstrate that in GABAergic medium spiny neurons of CN and PT, unlike in GABAergic neurons of layer I and II PFC, the increased expression of DNMT1 and the decrease of reelin and GAD67 occur in SZ but not in BDP. This suggests that different epigenetic mechanisms must exist in the pathogenesis underlying SZ and BDP and implies that these disorders might involve two separate entities that are characterized by a well-defined neuropathology.

  19. Glucose sensing by GABAergic neurons in the mouse nucleus tractus solitarii.

    PubMed

    Boychuk, Carie R; Gyarmati, Peter; Xu, Hong; Smith, Bret N

    2015-08-01

    Changes in blood glucose concentration alter autonomic function in a manner consistent with altered neural activity in brain regions controlling digestive processes, including neurons in the brain stem nucleus tractus solitarii (NTS), which process viscerosensory information. With whole cell or on-cell patch-clamp recordings, responses to elevating glucose concentration from 2.5 to 15 mM were assessed in identified GABAergic NTS neurons in slices from transgenic mice that express EGFP in a subset of GABA neurons. Single-cell real-time RT-PCR was also performed to detect glutamic acid decarboxylase (GAD67) in recorded neurons. In most identified GABA neurons (73%), elevating glucose concentration from 2.5 to 15 mM resulted in either increased (40%) or decreased (33%) neuronal excitability, reflected by altered membrane potential and/or action potential firing. Effects on membrane potential were maintained when action potentials or fast synaptic inputs were blocked, suggesting direct glucose sensing by GABA neurons. Glucose-inhibited GABA neurons were found predominantly in the lateral NTS, whereas glucose-excited cells were mainly in the medial NTS, suggesting regional segregation of responses. Responses were prevented in the presence of glucosamine, a glucokinase (GCK) inhibitor. Depolarizing responses were prevented when KATP channel activity was blocked with tolbutamide. Whereas effects on synaptic input to identified GABAergic neurons were variable in GABA neurons, elevating glucose increased glutamate release subsequent to stimulation of tractus solitarius in unlabeled, unidentified neurons. These results indicate that GABAergic NTS neurons act as GCK-dependent glucose sensors in the vagal complex, providing a means of modulating central autonomic signals when glucose is elevated. PMID:26084907

  20. Glucose sensing by GABAergic neurons in the mouse nucleus tractus solitarii

    PubMed Central

    Boychuk, Carie R.; Gyarmati, Peter; Xu, Hong

    2015-01-01

    Changes in blood glucose concentration alter autonomic function in a manner consistent with altered neural activity in brain regions controlling digestive processes, including neurons in the brain stem nucleus tractus solitarii (NTS), which process viscerosensory information. With whole cell or on-cell patch-clamp recordings, responses to elevating glucose concentration from 2.5 to 15 mM were assessed in identified GABAergic NTS neurons in slices from transgenic mice that express EGFP in a subset of GABA neurons. Single-cell real-time RT-PCR was also performed to detect glutamic acid decarboxylase (GAD67) in recorded neurons. In most identified GABA neurons (73%), elevating glucose concentration from 2.5 to 15 mM resulted in either increased (40%) or decreased (33%) neuronal excitability, reflected by altered membrane potential and/or action potential firing. Effects on membrane potential were maintained when action potentials or fast synaptic inputs were blocked, suggesting direct glucose sensing by GABA neurons. Glucose-inhibited GABA neurons were found predominantly in the lateral NTS, whereas glucose-excited cells were mainly in the medial NTS, suggesting regional segregation of responses. Responses were prevented in the presence of glucosamine, a glucokinase (GCK) inhibitor. Depolarizing responses were prevented when KATP channel activity was blocked with tolbutamide. Whereas effects on synaptic input to identified GABAergic neurons were variable in GABA neurons, elevating glucose increased glutamate release subsequent to stimulation of tractus solitarius in unlabeled, unidentified neurons. These results indicate that GABAergic NTS neurons act as GCK-dependent glucose sensors in the vagal complex, providing a means of modulating central autonomic signals when glucose is elevated. PMID:26084907

  1. Optogenetic activation of septal GABAergic afferents entrains neuronal firing in the medial habenula

    PubMed Central

    Choi, Kyuhyun; Lee, Youngin; Lee, Changwoo; Hong, Seokheon; Lee, Soonje; Kang, Shin Jung; Shin, Ki Soon

    2016-01-01

    The medial habenula (MHb) plays an important role in nicotine-related behaviors such as nicotine aversion and withdrawal. The MHb receives GABAergic input from the medial septum/diagonal band of Broca (MS/DB), yet the synaptic mechanism that regulates MHb activity is unclear. GABA (γ -aminobutyric acid) is a major inhibitory neurotransmitter activating both GABAA receptors and GABAB receptors. Depending on intracellular chloride concentration, however, GABAA receptors also function in an excitatory manner. In the absence of various synaptic inputs, we found that MHb neurons displayed spontaneous tonic firing at a rate of about ~4.4 Hz. Optogenetic stimulation of MS/DB inputs to the MHb evoked GABAA receptor-mediated synaptic currents, which produced stimulus-locked neuronal firing. Subsequent delayed yet lasting activation of GABAB receptors attenuated the intrinsic tonic firing. Consequently, septal GABAergic input alone orchestrates both excitatory GABAA and inhibitory GABAB receptors, thereby entraining the firing of MHb neurons. PMID:27703268

  2. PKC activators enhance GABAergic neurotransmission and paired-pulse facilitation in hippocampal CA1 pyramidal neurons.

    PubMed

    Xu, C; Liu, Q-Y; Alkon, D L

    2014-05-30

    Bryostatin-1, a potent agonist of protein kinase C (PKC), has recently been found to enhance spatial learning and long-term memory in rats, mice, rabbits and the nudibranch Hermissenda, and to exert profound neuroprotective effects on Alzheimer's disease (AD) in transgenic mice. However, details of the mechanistic effects of bryostatin on learning and memory remain unclear. To address this issue, whole-cell recording, a dual-recording approach and extracellular recording techniques were performed on young (2-4months) Brown-Norway rats. We found that bath-applied bryostatin-1 significantly increased the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). The firing rate of GABAergic interneurons significantly was also increased as recorded with a loosely-attached extracellular recording configuration. Simultaneous recordings from communicating cell pairs of interneuron and pyramidal neuron revealed unique activity-dependent properties of GABAergic synapses. Furthermore, the bryostatin-induced increase of the frequency and amplitude of IPSCs was blocked by methionine enkephalin which selectively suppressed the excitability of interneurons. Pretreatment with RO-32-0432, a relatively specific PKCα antagonist, blocked the effect of bryostatin on sIPSCs. Finally, bryostatin increased paired-pulse ratio of GABAergic synapses that lasted for at least 20min while pretreatment with RO-32-0432 significantly reduced the ratio. In addition, 8-[2-(2-pentyl-cyclopropylmethl)-cyclopropyl]-octanoic acid (DCP-LA), a selective PKCε activator, also increased the frequency and amplitude of sIPSCs. Taken together, these results suggest that bryostatin enhances GABAergic neurotransmission in pyramidal neurons by activating the PKCα & ε-dependent pathway and by a presynaptic mechanism with excitation of GABAergic interneurons. These effects of bryostatin on GABAergic transmissions and modifiability may contribute to the improvement of learning and memory

  3. GABAergic neurons in the preoptic area send direct inhibitory projections to orexin neurons.

    PubMed

    Saito, Yuki C; Tsujino, Natsuko; Hasegawa, Emi; Akashi, Kaori; Abe, Manabu; Mieda, Michihiro; Sakimura, Kenji; Sakurai, Takeshi

    2013-01-01

    Populations of neurons in the hypothalamic preoptic area (POA) fire rapidly during sleep, exhibiting sleep/waking state-dependent firing patterns that are the reciprocal of those observed in the arousal system. The majority of these preoptic "sleep-active" neurons contain the inhibitory neurotransmitter GABA. On the other hand, a population of neurons in the lateral hypothalamic area (LHA) contains orexins, which play an important role in the maintenance of wakefulness, and exhibit an excitatory influence on arousal-related neurons. It is important to know the anatomical and functional interactions between the POA sleep-active neurons and orexin neurons, both of which play important, but opposite roles in regulation of sleep/wakefulness states. In this study, we confirmed that specific pharmacogenetic stimulation of GABAergic neurons in the POA leads to an increase in the amount of non-rapid eye movement (NREM) sleep. We next examined direct connectivity between POA GABAergic neurons and orexin neurons using channelrhodopsin 2 (ChR2) as an anterograde tracer as well as an optogenetic tool. We expressed ChR2-eYFP selectively in GABAergic neurons in the POA by AAV-mediated gene transfer, and examined the projection sites of ChR2-eYFP-expressing axons, and the effect of optogenetic stimulation of ChR2-eYFP on the activity of orexin neurons. We found that these neurons send widespread projections to wakefulness-related areas in the hypothalamus and brain stem, including the LHA where these fibers make close appositions to orexin neurons. Optogenetic stimulation of these fibers resulted in rapid inhibition of orexin neurons. These observations suggest direct connectivity between POA GABAergic neurons and orexin neurons.

  4. Identification and Characterization of GABAergic Projection Neurons from Ventral Hippocampus to Amygdala

    PubMed Central

    Lübkemann, Robert; Eberhardt, Judith; Röhl, Friedrich-Wilhelm; Janitzky, Kathrin; Nullmeier, Sven; Stork, Oliver; Schwegler, Herbert; Linke, Rüdiger

    2015-01-01

    GABAergic local circuit neurons are critical for the network activity and functional interaction of the amygdala and hippocampus. Previously, we obtained evidence for a GABAergic contribution to the hippocampal projection into the basolateral amygdala. Using fluorogold retrograde labeling, we now demonstrate that this projection indeed has a prominent GABAergic component comprising 17% of the GABAergic neurons in the ventral hippocampus. A majority of the identified GABAergic projection neurons are located in the stratum oriens of area CA1, but cells are also found in the stratum pyramidale and stratum radiatum. We could detect the expression of different markers of interneuron subpopulations, including parvalbumin and calbindin, somatostatin, neuropeptide Y, and cholecystokinin in such retrogradely labeled GABA neurons. Thus GABAergic projection neurons to the amygdala comprise a neurochemically heterogeneous group of cells from different interneuron populations, well situated to control network activity patterns in the amygdalo-hippocampal system. PMID:26264032

  5. Investigation of synapse formation and function in a glutamatergic-GABAergic two-neuron microcircuit.

    PubMed

    Chang, Chia-Ling; Trimbuch, Thorsten; Chao, Hsiao-Tuan; Jordan, Julia-Christine; Herman, Melissa A; Rosenmund, Christian

    2014-01-15

    Neural circuits are composed of mainly glutamatergic and GABAergic neurons, which communicate through synaptic connections. Many factors instruct the formation and function of these synapses; however, it is difficult to dissect the contribution of intrinsic cell programs from that of extrinsic environmental effects in an intact network. Here, we perform paired recordings from two-neuron microculture preparations of mouse hippocampal glutamatergic and GABAergic neurons to investigate how synaptic input and output of these two principal cells develop. In our reduced preparation, we found that glutamatergic neurons showed no change in synaptic output or input regardless of partner neuron cell type or neuronal activity level. In contrast, we found that glutamatergic input caused the GABAergic neuron to modify its output by way of an increase in synapse formation and a decrease in synaptic release efficiency. These findings are consistent with aspects of GABAergic synapse maturation observed in many brain regions. In addition, changes in GABAergic output are cell wide and not target-cell specific. We also found that glutamatergic neuronal activity determined the AMPA receptor properties of synapses on the partner GABAergic neuron. All modifications of GABAergic input and output required activity of the glutamatergic neuron. Because our system has reduced extrinsic factors, the changes we saw in the GABAergic neuron due to glutamatergic input may reflect initiation of maturation programs that underlie the formation and function of in vivo neural circuits. PMID:24431444

  6. Investigation of synapse formation and function in a glutamatergic-GABAergic two-neuron microcircuit.

    PubMed

    Chang, Chia-Ling; Trimbuch, Thorsten; Chao, Hsiao-Tuan; Jordan, Julia-Christine; Herman, Melissa A; Rosenmund, Christian

    2014-01-15

    Neural circuits are composed of mainly glutamatergic and GABAergic neurons, which communicate through synaptic connections. Many factors instruct the formation and function of these synapses; however, it is difficult to dissect the contribution of intrinsic cell programs from that of extrinsic environmental effects in an intact network. Here, we perform paired recordings from two-neuron microculture preparations of mouse hippocampal glutamatergic and GABAergic neurons to investigate how synaptic input and output of these two principal cells develop. In our reduced preparation, we found that glutamatergic neurons showed no change in synaptic output or input regardless of partner neuron cell type or neuronal activity level. In contrast, we found that glutamatergic input caused the GABAergic neuron to modify its output by way of an increase in synapse formation and a decrease in synaptic release efficiency. These findings are consistent with aspects of GABAergic synapse maturation observed in many brain regions. In addition, changes in GABAergic output are cell wide and not target-cell specific. We also found that glutamatergic neuronal activity determined the AMPA receptor properties of synapses on the partner GABAergic neuron. All modifications of GABAergic input and output required activity of the glutamatergic neuron. Because our system has reduced extrinsic factors, the changes we saw in the GABAergic neuron due to glutamatergic input may reflect initiation of maturation programs that underlie the formation and function of in vivo neural circuits.

  7. Organization and properties of GABAergic neurons in solitary tract nucleus (NTS).

    PubMed

    Bailey, Timothy W; Appleyard, Suzanne M; Jin, Young-Ho; Andresen, Michael C

    2008-04-01

    Cranial visceral afferents enter the brain at the solitary tract nucleus (NTS). GABAergic neurons are scattered throughout the NTS, but their relation to solitary tract (ST) afferent pathways is imprecisely known. We hypothesized that most GABAergic NTS neurons would be connected only indirectly to the ST. We identified GABAergic neurons in brain stem horizontal slices using transgenic mice in which enhanced green fluorescent protein (EGFP) expression was linked to glutamic acid decarboxylase expression (GAD(+)). Finely graded electrical shocks to ST recruit ST-synchronized synaptic events with all-or-none thresholds and individual waveforms did not change with greater suprathreshold intensities--evidence consistent with initiation by single afferent axons. Most (approximately 70%) GAD(+) neurons received ST-evoked excitatory postsynaptic currents (EPSCs) that had minimally variant latencies (jitter, SD of latency <200 micros) and waveforms consistent with single, direct ST connections (i.e., monosynaptic). Increasing stimulus intensity evoked additional ST-synchronized synaptic responses with jitters >200 micros including inhibitory postsynaptic currents (IPSCs), indicating indirect connections (polysynaptic). Shocks of suprathreshold intensity delivered adjacent (50-300 microm) to the ST failed to excite non-ST inputs to second-order neurons, suggesting a paucity of axons passing near to ST that connected to these neurons. Despite expectations, we found similar ST synaptic patterns in GAD(+) and unlabeled neurons. Generally, ST information that arrived indirectly had small amplitudes (EPSCs and IPSCs) and frequency-dependent failures that reached >50% for IPSCs to bursts of stimuli. This ST afferent pathway organization is strongly use-dependent--a property that may tune signal propagation within and beyond NTS.

  8. Morphological alterations in neocortical and cerebellar GABAergic neurons in a canine model of juvenile Batten disease.

    PubMed

    March, P A; Wurzelmann, S; Walkley, S U

    1995-06-01

    The pathogenesis of brain dysfunction in a canine model of juvenile Batten disease was studied with techniques designed to determine sequential changes in mitochondrial morphology and cytochrome oxidase (CO) activity, and in neurons and synapses using gamma-aminobutyric acid (GABA) as a neurotransmitter. Histochemical and immunocytochemical methods were employed. Mitochondrial alterations were found in a select population of nonpyramidal neurons in neocortex and claustrum, and in cerebellar basket cells. Proportions of affected neurons at any one time remained constant over the disease course, with morphologically-abnormal mitochondria first being recognized at age 6 months. Enlarged mitochondria were readily identifiable at the light microscope (LM) level as large CO-positive or mitochondrial antibody-positive granular structures. Colabelling with antibodies to GABA or to parvalbumin (PV) indicated that most of these cells were GABAergic. Ultrastructurally, atypical mitochondria were characterized by globular enlargement, intramitochondrial membranous inclusions, and disorganized internal structure. CO activity in all other cell somata and in neuropil was diminished compared with normal, age-matched tissue. Glutamic acid decarboxylase (GAD), PV, and GABA studies demonstrated loss of GABAergic neurons and synapses in cortex and cerebellum of affected dogs. These results indicate that abnormal mitochondria are present in neurons in Batten disease, and suggest that suboptimal mitochondrial function may play a role in the pathogenic mechanisms of brain dysfunction in this disorder.

  9. Transient epileptiform signaling during neuronal network development: regulation by external stimulation and bimodal GABAergic activity.

    PubMed

    Zemianek, Jill M; Shultz, Abraham M; Lee, Sangmook; Guaraldi, Mary; Yanco, Holly A; Shea, Thomas B

    2013-04-01

    A predominance of excitatory activity, with protracted appearance of inhibitory activity, accompanies cortical neuronal development. It is unclear whether or not inhibitory neuronal activity is solicited exclusively by excitatory neurons or whether the transient excitatory activity displayed by developing GABAergic neurons contributes to an excitatory threshold that fosters their conversion to inhibitory activity. We addressed this possibility by culturing murine embryonic neurons on multi-electrode arrays. A wave of individual 0.2-0.4 mV signals ("spikes") appeared between approx. 20-30 days in culture, then declined. A transient wave of high amplitude (>0.5 mV) epileptiform activity coincided with the developmental decline in spikes. Bursts (clusters of ≥3 low-amplitude spikes within 0.7s prior to returning to baseline) persisted following this decline. Addition of the GABAergic antagonist bicuculline initially had no effect on signaling, consistent with delayed development of GABAergic synapses. This was followed by a period in which bicuculline inhibited overall signaling, confirming that GABAergic neurons initially display excitatory activity in ex vivo networks. Following the transient developmental wave of epileptiform signaling, bicuculline induced a resurgence of epileptiform signaling, indicating that GABAergic neurons at this point displayed inhibitory activity. The appearance of transition after the developmental and decline of epileptiform activity, rather than immediately after the developmental decline in lower-amplitude spikes, suggests that the initial excitatory activity of GABAergic neurons contributes to their transition into inhibitory neurons, and that inhibitory GABAergic activity is essential for network development. Prior studies indicate that a minority (25%) of neurons in these cultures were GABAergic, suggesting that inhibitory neurons regulate multiple excitatory neurons. A similar robust increase in signaling following cessation of

  10. Accumulation of GABAergic Neurons, Causing a Focal Ambient GABA Gradient, and Downregulation of KCC2 Are Induced During Microgyrus Formation in a Mouse Model of Polymicrogyria

    PubMed Central

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

    2014-01-01

    Although focal cortical malformations are considered neuronal migration disorders, their formation mechanisms remain unknown. We addressed how the γ-aminobutyric acid (GABA)ergic system affects the GABAergic and glutamatergic neuronal migration underlying such malformations. A focal freeze-lesion (FFL) of the postnatal day zero (P0) glutamic acid decarboxylase–green fluorescent protein knock-in mouse neocortex produced a 3- or 4-layered microgyrus at P7. GABAergic interneurons accumulated around the necrosis including the superficial region during microgyrus formation at P4, whereas E17.5-born, Cux1-positive pyramidal neurons outlined the GABAergic neurons and were absent from the superficial layer, forming cell-dense areas in layer 2 of the P7 microgyrus. GABA imaging showed that an extracellular GABA level temporally increased in the GABAergic neuron-positive area, including the necrotic center, at P4. The expression of the Cl– transporter KCC2 was downregulated in the microgyrus-forming GABAergic and E17.5-born glutamatergic neurons at P4; these cells may need a high intracellular Cl– concentration to induce depolarizing GABA effects. Bicuculline decreased the frequency of spontaneous Ca2+ oscillations in these microgyrus-forming cells. Thus, neonatal FFL causes specific neuronal accumulation, preceded by an increase in ambient GABA during microgyrus formation. This GABA increase induces GABAA receptor-mediated Ca2+ oscillation in KCC2-downregulated microgyrus-forming cells, as seen in migrating cells during early neocortical development. PMID:23246779

  11. Live-Cell, Label-Free Identification of GABAergic and Non-GABAergic Neurons in Primary Cortical Cultures Using Micropatterned Surface

    PubMed Central

    Kono, Sho; Kushida, Takatoshi; Hirano-Iwata, Ayumi; Niwano, Michio; Tanii, Takashi

    2016-01-01

    Excitatory and inhibitory neurons have distinct roles in cortical dynamics. Here we present a novel method for identifying inhibitory GABAergic neurons from non-GABAergic neurons, which are mostly excitatory glutamatergic neurons, in primary cortical cultures. This was achieved using an asymmetrically designed micropattern that directs an axonal process to the longest pathway. In the current work, we first modified the micropattern geometry to improve cell viability and then studied the axon length from 2 to 7 days in vitro (DIV). The cell types of neurons were evaluated retrospectively based on immunoreactivity against GAD67, a marker for inhibitory GABAergic neurons. We found that axons of non-GABAergic neurons grow significantly longer than those of GABAergic neurons in the early stages of development. The optimal threshold for identifying GABAergic and non-GABAergic neurons was evaluated to be 110 μm at 6 DIV. The method does not require any fluorescence labelling and can be carried out on live cells. The accuracy of identification was 98.2%. We confirmed that the high accuracy was due to the use of a micropattern, which standardized the development of cultured neurons. The method promises to be beneficial both for engineering neuronal networks in vitro and for basic cellular neuroscience research. PMID:27513933

  12. In vivo clonal overexpression of neuroligin 3 and neuroligin 2 in neurons of the rat cerebral cortex: Differential effects on GABAergic synapses and neuronal migration.

    PubMed

    Fekete, Christopher D; Chiou, Tzu-Ting; Miralles, Celia P; Harris, Rachel S; Fiondella, Christopher G; Loturco, Joseph J; De Blas, Angel L

    2015-06-15

    We studied the effect of clonal overexpression of neuroligin 3 (NL3) or neuroligin 2 (NL2) in the adult rat cerebral cortex following in utero electroporation (IUEP) at embryonic stage E14. Overexpression of NL3 leads to a large increase in vesicular gamma-aminobutyric acid (GABA) transporter (vGAT) and glutamic acid decarboxylase (GAD)65 in the GABAergic contacts that the overexpressing neurons receive. Overexpression of NL2 produced a similar effect but to a lesser extent. In contrast, overexpression of NL3 or NL2 after IUEP does not affect vesicular glutamate transporter 1 (vGlut1) in the glutamatergic contacts that the NL3 or NL2-overexpressing neurons receive. The NL3 or NL2-overexpressing neurons do not show increased innervation by parvalbumin-containing GABAergic terminals or increased parvalbumin in the same terminals that show increased vGAT. These results indicate that the observed increase in vGAT and GAD65 is not due to increased GABAergic innervation but to increased expression of vGAT and GAD65 in the GABAergic contacts that NL3 or NL2-overexpressing neurons receive. The majority of bright vGAT puncta contacting the NL3-overexpressing neurons have no gephyrin juxtaposed to them, indicating that many of these contacts are nonsynaptic. This contrasts with the majority of the NL2-overexpressing neurons, which show plenty of synaptic gephyrin clusters juxtaposed to vGAT. Besides having an effect on GABAergic contacts, overexpression of NL3 interferes with the neuronal radial migration, in the cerebral cortex, of the neurons overexpressing NL3.

  13. Comparison of spike parameters from optically identified GABAergic and glutamatergic neurons in sparse cortical cultures

    PubMed Central

    Weir, Keiko; Blanquie, Oriane; Kilb, Werner; Luhmann, Heiko J.; Sinning, Anne

    2015-01-01

    Primary neuronal cultures share many typical features with the in vivo situation, including similarities in distinct electrical activity patterns and synaptic network interactions. Here, we use multi-electrode array (MEA) recordings from spontaneously active cultures of wildtype and glutamic acid decarboxylase 67 (GAD67)-green fluorescent protein (GFP) transgenic mice to evaluate which spike parameters differ between GABAergic interneurons and principal, putatively glutamatergic neurons. To analyze this question we combine MEA recordings with optical imaging in sparse cortical cultures to assign individual spikes to visually-identified single neurons. In our culture system, excitatory and inhibitory neurons are present at a similar ratio as described in vivo, and spike waveform characteristics and firing patterns are fully developed after 2 weeks in vitro. Spike amplitude, but not other spike waveform parameters, correlated with the distance between the recording electrode and the location of the assigned neuron’s soma. Cluster analysis of spike waveform properties revealed no particular cell population that may be assigned to putative inhibitory or excitatory neurons. Moreover, experiments in primary cultures from transgenic GAD67-GFP mice, which allow optical identification of GABAergic interneurons and thus unambiguous assignment of extracellular signals, did not reveal any significant difference in spike timing and spike waveform parameters between inhibitory and excitatory neurons. Despite of our detailed characterization of spike waveform and temporal spiking properties we could not identify an unequivocal electrical parameter to discriminate between individual excitatory and inhibitory neurons in vitro. Our data suggest that under in vitro conditions cellular classifications of single neurons on the basis of their extracellular firing properties should be treated with caution. PMID:25642167

  14. Physiological and morphological characterization of GABAergic neurons in the medial amygdala.

    PubMed

    Bian, Xiling

    2013-05-01

    GABAergic neurons in the medial amygdala (MeA) have been indicated in information processing in reproductive behavior and fear/anxiety. However, basic knowledge of their physiological and morphological properties is still very limited, probably due to the technical challenge to selectively record the GABAergic neurons. In this study, I characterized properties of the MeA GABAergic neurons by performing whole-cell patch clamp recordings from brain slices of adult knock-in mice selectively expressing green fluorescence protein (GFP) in GABAergic neurons. The majority (73%) of GABAergic neurons exhibiting low threshold calcium spike were classified as type I neurons, with morphological properties of being bitufted or stellate, and dendrites either aspiny or covered by various shapes of spines. Axonal collaterals of some neurons were observed near somata as well as in other amygdaloid nuclei. Neurons incapable of generate low threshold calcium spikes were divided into two types. Type II neurons (11%) exhibited hyperpolarization-activated sag and higher input resistance (>400 MΩ). Most Type II neurons exhibited asymmetric dendritic trees extending towards the superficial layer covered with long neck dendritic spines. The axons of type II neurons formed large collaterals and projected to other amygdaloid nuclei. Type III neurons (16%) lack prominent hyperpolarization-activated sag and possessed lower input resistance (<400 MΩ). These neurons were local interneurons with smooth multipolar dendritic trees. Since both MeA and nearby amygdaloid nuclei are involved in fear/anxiety processing, two types of MeA GABAergic projection neurons and a third type of interneurons that might participate in anxiety-related behavior were revealed by my present study.

  15. Activation of c-fos in GABAergic neurones in the preoptic area during sleep and in response to sleep deprivation.

    PubMed

    Gong, Hui; McGinty, Dennis; Guzman-Marin, Ruben; Chew, Keng-Tee; Stewart, Darya; Szymusiak, Ronald

    2004-05-01

    Neurones in the median preoptic nucleus (MnPN) and the ventrolateral preoptic area (vlPOA) express immunoreactivity for c-Fos protein following sustained sleep, and display elevated discharge rates during both non-REM and REM sleep compared to waking. We evaluated the hypothesis that MnPN and vlPOA sleep-active neurones are GABAergic by combining staining for c-Fos protein with staining for glutamic acid decarboxylase (GAD). In a group of six rats exhibiting spontaneous total sleep times averaging 82.2 +/- 5.1% of the 2 h immediately prior to death, >75% of MnPN neurones that were Fos-immunoreactive (IR) were also GAD-IR. Similar results were obtained in the vlPOA. In a group of 11 rats exhibiting spontaneous sleep times ranging from 20 to 92%, the number of Fos + GAD-IR neurones in MnPN and vlPOA was positively correlated with total sleep time. Compared to control animals, Fos + GAD-IR cell counts in the MnPN were significantly elevated in rats that were sleep deprived for 24 h and permitted 2 h of recovery sleep. These findings demonstrate that a majority of MnPN and vlPOA neurones that express Fos-IR during sustained spontaneous sleep are GABAergic. They also demonstrate that sleep deprivation is associated with increased activation of GABAergic neurones in the MnPN and vlPOA.

  16. Nicotine increases GABAergic input on rat dorsal raphe serotonergic neurons through alpha7 nicotinic acetylcholine receptor.

    PubMed

    Hernández-Vázquez, F; Chavarría, K; Garduño, J; Hernández-López, S; Mihailescu, S P

    2014-12-15

    The dorsal raphe nucleus (DRN) contains large populations of serotonergic (5-HT) neurons. This nucleus receives GABAergic inhibitory afferents from many brain areas and from DRN interneurons. Both GABAergic and 5-HT DRN neurons express functional nicotinic acetylcholine receptors (nAChRs). Previous studies have demonstrated that nicotine increases 5-HT release and 5-HT DRN neuron discharge rate by stimulating postsynaptic nAChRs and by increasing glutamate and norepinephrine release inside DRN. However, the influence of nicotine on the GABAergic input to 5-HT DRN neurons was poorly investigated. Therefore, the aim of this work was to determine the effect of nicotine on GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) of 5-HT DRN neurons and the subtype of nAChR(s) involved in this response. Experiments were performed in coronal slices obtained from young Wistar rats. GABAergic sIPSCs were recorded from post hoc-identified 5-HT DRN neurons with the whole cell voltage patch-clamp technique. Administration of nicotine (1 μM) increased sIPSC frequency in 72% of identified 5-HT DRN neurons. This effect was not reproduced by the α4β2 nAChR agonist RJR-2403 and was not influenced by TTX (1 μM). It was mimicked by the selective agonist for α7 nAChR, PNU-282987, and exacerbated by the positive allosteric modulator of the same receptor, PNU-120596. The nicotine-induced increase in sIPSC frequency was independent on voltage-gated calcium channels and dependent on Ca(2+)-induced Ca(2+) release (CICR). These results demonstrate that nicotine increases the GABAergic input to most 5-HT DRN neurons, by activating α7 nAChRs and producing CICR in DRN GABAergic terminals.

  17. Nicotine increases GABAergic input on rat dorsal raphe serotonergic neurons through alpha7 nicotinic acetylcholine receptor.

    PubMed

    Hernández-Vázquez, F; Chavarría, K; Garduño, J; Hernández-López, S; Mihailescu, S P

    2014-12-15

    The dorsal raphe nucleus (DRN) contains large populations of serotonergic (5-HT) neurons. This nucleus receives GABAergic inhibitory afferents from many brain areas and from DRN interneurons. Both GABAergic and 5-HT DRN neurons express functional nicotinic acetylcholine receptors (nAChRs). Previous studies have demonstrated that nicotine increases 5-HT release and 5-HT DRN neuron discharge rate by stimulating postsynaptic nAChRs and by increasing glutamate and norepinephrine release inside DRN. However, the influence of nicotine on the GABAergic input to 5-HT DRN neurons was poorly investigated. Therefore, the aim of this work was to determine the effect of nicotine on GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) of 5-HT DRN neurons and the subtype of nAChR(s) involved in this response. Experiments were performed in coronal slices obtained from young Wistar rats. GABAergic sIPSCs were recorded from post hoc-identified 5-HT DRN neurons with the whole cell voltage patch-clamp technique. Administration of nicotine (1 μM) increased sIPSC frequency in 72% of identified 5-HT DRN neurons. This effect was not reproduced by the α4β2 nAChR agonist RJR-2403 and was not influenced by TTX (1 μM). It was mimicked by the selective agonist for α7 nAChR, PNU-282987, and exacerbated by the positive allosteric modulator of the same receptor, PNU-120596. The nicotine-induced increase in sIPSC frequency was independent on voltage-gated calcium channels and dependent on Ca(2+)-induced Ca(2+) release (CICR). These results demonstrate that nicotine increases the GABAergic input to most 5-HT DRN neurons, by activating α7 nAChRs and producing CICR in DRN GABAergic terminals. PMID:25231613

  18. Endogenous acetylcholine and nicotine activation enhances GABAergic and glycinergic inputs to cardiac vagal neurons.

    PubMed

    Wang, Jijiang; Wang, Xin; Irnaten, Mustapha; Venkatesan, Priya; Evans, Cory; Baxi, Sunit; Mendelowitz, David

    2003-05-01

    The heart slows during expiration and heart rate increases during inspiration. This cardiorespiratory interaction is thought to occur by increased inhibitory synaptic events to cardiac vagal neurons during inspiration. Since cholinergic receptors have been suggested to be involved in this cardiorespiratory interaction, we tested whether endogenous cholinergic activity modulates GABAergic and glycinergic neurotransmission to cardiac vagal neurons in the nucleus ambiguus, whether nicotine can mimic this facilitation, and we examined the nicotinic receptors involved. Cardiac vagal neurons in the rat were labeled with a retrograde fluorescent tracer and studied in an in vitro slice using patch-clamp techniques. Application of neostigmine (10 microM), an acetylcholinerase inhibitor, significantly increased the frequency of both GABAergic and glycinergic inhibitory postsynaptic currents (IPSCs) in cardiac vagal neurons. Exogenous application of nicotine increased the frequency and amplitude of both GABAergic and glycinergic IPSCs. The nicotinic facilitation of both GABAergic and glycinergic IPSCs were insensitive to 100 nM alpha-bungarotoxin but were abolished by dihydro-beta-erythrodine (DHbetaE) at a concentration (3 microM) specific for alpha4beta2 nicotinic receptors. In the presence of TTX, nicotine increased the frequency of GABAergic and glycinergic miniature synaptic events, which were also abolished by DHbetaE (3 microM). This work demonstrates that there is endogenous cholinergic facilitation of GABAergic and glycinergic synaptic inputs to cardiac vagal neurons, and activation of alpha4beta2 nicotinic receptors at presynaptic terminals facilitates GABAergic and glycinergic neurotransmission to cardiac vagal neurons. Nicotinic facilitation of inhibitory neurotransmission to premotor cardiac parasympathetic neurons may be involved in generating respiratory sinus arrhythmia.

  19. A Resource of Cre Driver Lines for Genetic Targeting of GABAergic Neurons in Cerebral Cortex

    PubMed Central

    Taniguchi, Hiroki; He, Miao; Wu, Priscilla; Kim, Sangyong; Paik, Raehum; Sugino, Ken; Kvitsani, Duda; Fu, Yu; Lu, Jiangteng; Lin, Ying; Miyoshi, Goichi; Shima, Yasuyuki; Fishell, Gord; Nelson, Sacha B.

    2013-01-01

    Summary A key obstacle to understanding neural circuits in the cerebral cortex is that of unraveling the diversity of GABAergic interneurons. This diversity poses general questions for neural circuit analysis: how are these interneuron cell types generated and assembled into stereotyped local circuits and how do they differentially contribute to circuit operations that underlie cortical functions ranging from perception to cognition? Using genetic engineering in mice, we have generated and characterized ~20 Cre and inducible CreER knockin driver lines that reliably target major classes and lineages of GABAergic neurons. More select populations are captured by intersection of Cre and Flp drivers. Genetic targeting allows reliable identification, monitoring, and manipulation of cortical GABAergic neurons, thereby enabling a systematic and comprehensive analysis from cell fate specification, migration, and connectivity, to their functions in network dynamics and behavior. As such, this approach will accelerate the study of GABAergic circuits throughout the mammalian brain. PMID:21943598

  20. Distinct electrophysiological properties of glutamatergic, cholinergic and GABAergic rat septohippocampal neurons: novel implications for hippocampal rhythmicity.

    PubMed

    Sotty, F; Danik, M; Manseau, F; Laplante, F; Quirion, R; Williams, S

    2003-09-15

    The medial septum-diagonal band complex (MSDB) contains cholinergic and non-cholinergic neurons known to play key roles in learning and memory processing, and in the generation of hippocampal theta rhythm. Electrophysiologically, several classes of neurons have been described in the MSDB, but their chemical identity remains to be fully established. By combining electrophysiology with single-cell RT-PCR, we have identified four classes of neurons in the MSDB in vitro. The first class displayed slow-firing and little or no Ih, and expressed choline acetyl-transferase mRNA (ChAT). The second class was fast-firing, had a substantial Ih and expressed glutamic acid decarboxylase 67 mRNA (GAD67), sometimes co-localized with ChAT mRNAs. A third class exhibited fast- and burst-firing, had an important Ih and expressed GAD67 mRNA also occasionally co-localized with ChAT mRNAs. The ionic mechanism underlying the bursts involved a low-threshold spike and a prominent Ih current, conductances often associated with pacemaker activity. Interestingly, we identified a fourth class that expressed transcripts solely for one or two of the vesicular glutamate transporters (VGLUT1 and VGLUT2), but not ChAT or GAD. Some putative glutamatergic neurons displayed electrophysiological properties similar to ChAT-positive slow-firing neurons such as the occurrence of a very small Ih, but nearly half of glutamatergic neurons exhibited cluster firing with intrinsically generated voltage-dependent subthreshold membrane oscillations. Neurons belonging to each of the four described classes were found among septohippocampal neurons by retrograde labelling. We provide results suggesting that slow-firing cholinergic, fast-firing and burst-firing GABAergic, and cluster-firing glutamatergic neurons, may each uniquely contribute to hippocampal rhythmicity in vivo. PMID:12865506

  1. Innervation by a GABAergic neuron depresses spontaneous release in glutamatergic neurons and unveils the clamping phenotype of synaptotagmin-1.

    PubMed

    Wierda, Keimpe D B; Sørensen, Jakob B

    2014-02-01

    The role of spontaneously occurring release events in glutamatergic and GABAergic neurons and their regulation is intensely debated. To study the interdependence of glutamatergic and GABAergic spontaneous release, we compared reciprocally connected "mixed" glutamatergic/GABAergic neuronal pairs from mice cultured on astrocyte islands with "homotypic" glutamatergic or GABAergic pairs and autaptic neurons. We measured mEPSC and mIPSC frequencies simultaneously from both neurons. Neuronal pairs formed both interneuronal synaptic and autaptic connections indiscriminately. We find that whereas mEPSC and mIPSC frequencies did not deviate between autaptic and synaptic connections, the frequency of mEPSCs in mixed pairs was strongly depressed compared with either autaptic neurons or glutamatergic pairs. Simultaneous imaging of synapses, or comparison to evoked release amplitudes, showed that this decrease was not caused by fewer active synapses. The mEPSC frequency was negatively correlated with the mIPSC frequency, indicating interdependence. Moreover, the reduction in mEPSC frequency was abolished when established pairs were exposed to bicuculline for 3 d, but not by long-term incubation with tetrodotoxin, indicating that spontaneous GABA release downregulates mEPSC frequency. Further investigations showed that knockout of synaptotagmin-1 did not affect mEPSC frequencies in either glutamatergic autaptic neurons or in glutamatergic pairs. However, in mixed glutamatergic/GABAergic pairs, mEPSC frequencies were increased by a factor of four in the synaptotagmin-1-null neurons, which is in line with data obtained from mixed cultures. The effect persisted after incubation with BAPTA-AM. We conclude that spontaneous GABA release exerts control over mEPSC release, and GABAergic innervation of glutamatergic neurons unveils the unclamping phenotype of the synaptotagmin-1-null neurons.

  2. Adenosine Inhibits the Excitatory Synaptic Inputs to Basal Forebrain Cholinergic, GABAergic, and Parvalbumin Neurons in Mice

    PubMed Central

    Yang, Chun; Franciosi, Serena; Brown, Ritchie E.

    2013-01-01

    Coffee and tea contain the stimulants caffeine and theophylline. These compounds act as antagonists of adenosine receptors. Adenosine promotes sleep and its extracellular concentration rises in association with prolonged wakefulness, particularly in the basal forebrain (BF) region involved in activating the cerebral cortex. However, the effect of adenosine on identified BF neurons, especially non-cholinergic neurons, is incompletely understood. Here we used whole-cell patch-clamp recordings in mouse brain slices prepared from two validated transgenic mouse lines with fluorescent proteins expressed in GABAergic or parvalbumin (PV) neurons to determine the effect of adenosine. Whole-cell recordings were made from BF cholinergic neurons and from BF GABAergic and PV neurons with the size (>20 μm) and intrinsic membrane properties (prominent H-currents) corresponding to cortically projecting neurons. A brief (2 min) bath application of adenosine (100 μM) decreased the frequency but not the amplitude of spontaneous excitatory postsynaptic currents (EPSCs) in all groups of BF cholinergic, GABAergic, and PV neurons we recorded. In addition, adenosine decreased the frequency of miniature EPSCs in BF cholinergic neurons. Adenosine had no effect on the frequency of spontaneous inhibitory postsynaptic currents in cholinergic neurons or GABAergic neurons with large H-currents but reduced them in a group of GABAergic neurons with smaller H-currents. All effects of adenosine were blocked by a selective, adenosine A1 receptor antagonist, cyclopentyltheophylline (CPT, 1 μM). Adenosine had no postsynaptic effects. Taken together, our work suggests that adenosine promotes sleep by an A1 receptor-mediated inhibition of glutamatergic inputs to cortically projecting cholinergic and GABA/PV neurons. Conversely, caffeine and theophylline promote attentive wakefulness by inhibiting these A1 receptors in BF thereby promoting the high-frequency oscillations in the cortex required

  3. Minimal Change in the Cytoplasmic Calcium Dynamics in Striatal GABAergic Neurons of a DYT1 Dystonia Knock-In Mouse Model

    PubMed Central

    Iwabuchi, Sadahiro; Koh, Jin-Young; Wang, Kai; Ho, K. W. David; Harata, N. Charles

    2013-01-01

    DYT1 dystonia is the most common hereditary form of primary torsion dystonia. This autosomal-dominant disorder is characterized by involuntary muscle contractions that cause sustained twisting and repetitive movements. It is caused by an in-frame deletion in the TOR1A gene, leading to the deletion of a glutamic acid residue in the torsinA protein. Heterozygous knock-in mice, which reproduce the genetic mutation in human patients, have abnormalities in synaptic transmission at the principal GABAergic neurons in the striatum, a brain structure that is involved in the execution and modulation of motor activity. However, whether this mutation affects the excitability of striatal GABAergic neurons has not been investigated in this animal model. Here, we examined the excitability of cultured striatal neurons obtained from heterozygous knock-in mice, using calcium imaging as indirect readout. Immunofluorescence revealed that more than 97% of these neurons are positive for a marker of GABAergic neurons, and that more than 92% are also positive for a marker of medium spiny neurons, indicating that these are mixed cultures of mostly medium spiny neurons and a few (~5%) GABAergic interneurons. When these neurons were depolarized by field stimulation, the calcium concentration in the dendrites increased rapidly and then decayed slowly. The amplitudes of calcium transients were larger in heterozygous neurons than in wild-type neurons, resulting in ~15% increase in cumulative calcium transients during a train of stimuli. However, there was no change in other parameters of calcium dynamics. Given that calcium dynamics reflect neuronal excitability, these results suggest that the mutation only slightly increases the excitability of striatal GABAergic neurons in DYT1 dystonia. PMID:24260480

  4. Distribution and Intrinsic Membrane Properties of Basal Forebrain GABAergic and Parvalbumin Neurons in the Mouse

    PubMed Central

    McKenna, James T.; Yang, Chun; Franciosi, Serena; Winston, Stuart; Abarr, Kathleen K.; Rigby, Matthew S.; Yanagawa, Yuchio; McCarley, Robert W.; Brown, Ritchie E.

    2013-01-01

    The basal forebrain (BF) strongly regulates cortical activation, sleep homeostasis, and attention. Many BF neurons involved in these processes are GABAergic, including a subpopulation of projection neurons containing the calcium-binding protein, parvalbumin (PV). However, technical difficulties in identification have prevented a precise mapping of the distribution of GABAergic and GABA/PV+ neurons in the mouse or a determination of their intrinsic membrane properties. Here we used mice expressing fluorescent proteins in GABAergic (GAD67-GFP knock-in mice) or PV+ neurons (PV-Tomato mice) to study these neurons. Immunohistochemical staining for GABA in GAD67-GFP mice confirmed that GFP selectively labeled BF GABAergic neurons. GFP+ neurons and fibers were distributed throughout the BF, with the highest density in the magnocellular preoptic area (MCPO). Immunohistochemistry for PV indicated that the majority of PV+ neurons in the BF were large (>20 μm) or medium-sized (15–20 μm) GFP+ neurons. Most medium and large-sized BF GFP+ neurons, including those retrogradely labeled from the neocortex, were fast-firing and spontaneously active in vitro. They exhibited prominent hyperpolarization-activated inward currents and subthreshold “spikelets,” suggestive of electrical coupling. PV+ neurons recorded in PV-Tomato mice had similar properties but had significantly narrower action potentials and a higher maximal firing frequency. Another population of smaller GFP+ neurons had properties similar to striatal projection neurons. The fast firing and electrical coupling of BF GABA/PV+ neurons, together with their projections to cortical interneurons and the thalamic reticular nucleus, suggest a strong and synchronous control of the neocortical fast rhythms typical of wakefulness and REM sleep. PMID:23254904

  5. Reciprocal cholinergic and GABAergic modulation of the small ventrolateral pacemaker neurons of Drosophila's circadian clock neuron network.

    PubMed

    Lelito, Katherine R; Shafer, Orie T

    2012-04-01

    The relatively simple clock neuron network of Drosophila is a valuable model system for the neuronal basis of circadian timekeeping. Unfortunately, many key neuronal classes of this network are inaccessible to electrophysiological analysis. We have therefore adopted the use of genetically encoded sensors to address the physiology of the fly's circadian clock network. Using genetically encoded Ca(2+) and cAMP sensors, we have investigated the physiological responses of two specific classes of clock neuron, the large and small ventrolateral neurons (l- and s-LN(v)s), to two neurotransmitters implicated in their modulation: acetylcholine (ACh) and γ-aminobutyric acid (GABA). Live imaging of l-LN(v) cAMP and Ca(2+) dynamics in response to cholinergic agonist and GABA application were well aligned with published electrophysiological data, indicating that our sensors were capable of faithfully reporting acute physiological responses to these transmitters within single adult clock neuron soma. We extended these live imaging methods to s-LN(v)s, critical neuronal pacemakers whose physiological properties in the adult brain are largely unknown. Our s-LN(v) experiments revealed the predicted excitatory responses to bath-applied cholinergic agonists and the predicted inhibitory effects of GABA and established that the antagonism of ACh and GABA extends to their effects on cAMP signaling. These data support recently published but physiologically untested models of s-LN(v) modulation and lead to the prediction that cholinergic and GABAergic inputs to s-LN(v)s will have opposing effects on the phase and/or period of the molecular clock within these critical pacemaker neurons.

  6. Strategies and Tools for Combinatorial Targeting of GABAergic Neurons in Mouse Cerebral Cortex.

    PubMed

    He, Miao; Tucciarone, Jason; Lee, SooHyun; Nigro, Maximiliano José; Kim, Yongsoo; Levine, Jesse Maurica; Kelly, Sean Michael; Krugikov, Illya; Wu, Priscilla; Chen, Yang; Gong, Lin; Hou, Yongjie; Osten, Pavel; Rudy, Bernardo; Huang, Z Josh

    2016-09-21

    Systematic genetic access to GABAergic cell types will facilitate studying the function and development of inhibitory circuitry. However, single gene-driven recombinase lines mark relatively broad and heterogeneous cell populations. Although intersectional approaches improve precision, it remains unclear whether they can capture cell types defined by multiple features. Here we demonstrate that combinatorial genetic and viral approaches target restricted GABAergic subpopulations and cell types characterized by distinct laminar location, morphology, axonal projection, and electrophysiological properties. Intersectional embryonic transcription factor drivers allow finer fate mapping of progenitor pools that give rise to distinct GABAergic populations, including laminar cohorts. Conversion of progenitor fate restriction signals to constitutive recombinase expression enables viral targeting of cell types based on their lineage and birth time. Properly designed intersection, subtraction, conversion, and multi-color reporters enhance the precision and versatility of drivers and viral vectors. These strategies and tools will facilitate studying GABAergic neurons throughout the mouse brain. PMID:27618674

  7. In vivo administration of epidermal growth factor and its homologue attenuates developmental maturation of functional excitatory synapses in cortical GABAergic neurons.

    PubMed

    Nagano, Tadasato; Namba, Hisaaki; Abe, Yuichi; Aoki, Hiroyuki; Takei, Nobuyuki; Nawa, Hiroyuki

    2007-01-01

    The ErbB1 ligand family includes epidermal growth factor (EGF), transforming growth factor-alpha (TGFalpha), heparin-binding EGF-like growth factor, amphiregulin and betacellulin. Previously, we demonstrated that TGFalpha decreases alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors in cultured neocortical gamma-aminobutyric acid (GABA) neurons. In the present study, we examined in vivo effects of EGF and TGFalpha in the mouse neocortex using electrophysiological and biochemical techniques. In mouse neonates, subcutaneously administered EGF penetrated the blood-brain barrier and activated ErbB1 in the neocortex. Daily administration of EGF or TGFalpha attenuates developmental increases in expression of the AMPA receptor subunits (GluR1 and GluR2/3) in the neocortex of postnatal mice. Immunohistochemistry revealed that the reduction in AMPA receptor expression was significant in the GABAergic neurons, especially those positive for parvalbumin. Using cortical slices prepared from EGF-treated mice, we recorded miniature excitatory postsynaptic currents (mEPSCs) in both GABAergic and pyramidal neurons. Subchronic treatment with EGF decreased the amplitude and frequency of mEPSCs in GABAergic neurons, but its effects were negligible on pyramidal neurons. We conclude that EGF or other ErbB1 ligand(s) attenuates a developmental increase in AMPA receptor expression and function in cortical GABAergic neurons.

  8. Selective α4β2 nicotinic acetylcholine receptor agonists target epigenetic mechanisms in cortical GABAergic neurons.

    PubMed

    Maloku, Ekrem; Kadriu, Bashkim; Zhubi, Adrian; Dong, Erbo; Pibiri, Fabio; Satta, Rosalba; Guidotti, Alessandro

    2011-06-01

    Nicotine improves cognitive performance and attention in both experimental animals and in human subjects, including patients affected by neuropsychiatric disorders. However, the specific molecular mechanisms underlying nicotine-induced behavioral changes remain unclear. We have recently shown in mice that repeated injections of nicotine, which achieve plasma concentrations comparable to those reported in high cigarette smokers, result in an epigenetically induced increase of glutamic acid decarboxylase 67 (GAD(67)) expression. Here we explored the impact of synthetic α(4)β(2) and α(7) nAChR agonists on GABAergic epigenetic parameters. Varenicline (VAR), a high-affinity partial agonist at α(4)β(2) and a lower affinity full agonist at α(7) neuronal nAChR, injected in doses of 1-5 mg/kg/s.c. twice daily for 5 days, elicited a 30-40% decrease of cortical DNA methyltransferase (DNMT)1 mRNA and an increased expression of GAD(67) mRNA and protein. This upregulation of GAD(67) was abolished by the nAChR antagonist mecamylamine. Furthermore, the level of MeCP(2) binding to GAD(67) promoters was significantly reduced following VAR administration. This effect was abolished when VAR was administered with mecamylamine. Similar effects on cortical DNMT1 and GAD(67) expression were obtained after administration of A-85380, an agonist that binds to α(4)β(2) but has negligible affinity for α(3)β(4) or α(7) subtypes containing nAChR. In contrast, PNU-282987, an agonist of the homomeric α(7) nAChR, failed to decrease cortical DNMT1 mRNA or to induce GAD(67) expression. The present study suggests that the α(4)β(2) nAChR agonists may be better suited to control the epigenetic alterations of GABAergic neurons in schizophrenia than the α(7) nAChR agonists.

  9. Quantitative study of NPY-expressing GABAergic neurons and axons in rat spinal dorsal horn.

    PubMed

    Polgár, Erika; Sardella, Thomas C P; Watanabe, Masahiko; Todd, Andrew J

    2011-04-15

    Between 25-40% of neurons in laminae I-III are GABAergic, and some of these express neuropeptide Y (NPY). We previously reported that NPY-immunoreactive axons form numerous synapses on lamina III projection neurons that possess the neurokinin 1 receptor (NK1r). The aims of this study were to determine the proportion of neurons and GABAergic boutons in this region that contain NPY, and to look for evidence that they selectively innervate different neuronal populations. We found that 4-6% of neurons in laminae I-III were NPY-immunoreactive and based on the proportions of neurons that are GABAergic, we estimate that NPY is expressed by 18% of inhibitory interneurons in laminae I-II and 9% of those in lamina III. GABAergic boutons were identified by the presence of the vesicular GABA transporter (VGAT) and NPY was found in 13-15% of VGAT-immunoreactive boutons in laminae I-II, and 5% of those in lamina III. For both the lamina III NK1r-immunoreactive projection neurons and protein kinase Cγ (PKCγ)-immunoreactive interneurons in lamina II, we found that around one-third of the VGAT boutons that contacted them were NPY-immunoreactive. However, based on differences in the sizes of these boutons and the strength of their NPY-immunoreactivity, we conclude that these originate from different populations of interneurons. Only 6% of VGAT boutons presynaptic to large lamina I projection neurons that lacked NK1rs contained NPY. These results show that NPY-containing neurons make up a considerable proportion of the inhibitory interneurons in laminae I-III, and that their axons preferentially target certain classes of dorsal horn neuron.

  10. Characteristics of GABAergic and cholinergic neurons in perinuclear zone of mouse supraoptic nucleus

    PubMed Central

    Ennis, Matthew; Szabó, Gábor; Armstrong, William E.

    2014-01-01

    The perinuclear zone (PNZ) of the supraoptic nucleus (SON) contains some GABAergic and cholinergic neurons thought to innervate the SON proper. In mice expressing enhanced green fluorescent protein (eGFP) in association with glutamate decarboxylase (GAD)65 we found an abundance of GAD65-eGFP neurons in the PNZ, whereas in mice expressing GAD67-eGFP, there were few labeled PNZ neurons. In mice expressing choline acetyltransferase (ChAT)-eGFP, large, brightly fluorescent and small, dimly fluorescent ChAT-eGFP neurons were present in the PNZ. The small ChAT-eGFP and GAD65-eGFP neurons exhibited a low-threshold depolarizing potential consistent with a low-threshold spike, with little transient outward rectification. Large ChAT-eGFP neurons exhibited strong transient outward rectification and a large hyperpolarizing spike afterpotential, very similar to that of magnocellular vasopressin and oxytocin neurons. Thus the large soma and transient outward rectification of large ChAT-eGFP neurons suggest that these neurons would be difficult to distinguish from magnocellular SON neurons in dissociated preparations by these criteria. Large, but not small, ChAT-eGFP neurons were immunostained with ChAT antibody (AB144p). Reconstructed neurons revealed a few processes encroaching near and passing through the SON from all types but no clear evidence of a terminal axon arbor. Large ChAT-eGFP neurons were usually oriented vertically and had four or five dendrites with multiple branches and an axon with many collaterals and local arborizations. Small ChAT-eGFP neurons had a more restricted dendritic tree compared with parvocellular GAD65 neurons, the latter of which had long thin processes oriented mediolaterally. Thus many of the characteristics found previously in unidentified, small PNZ neurons are also found in identified GABAergic neurons and in a population of smaller ChAT-eGFP neurons. PMID:25376783

  11. Direct Induction and Functional Maturation of Forebrain GABAergic Neurons from Human Pluripotent Stem Cells.

    PubMed

    Sun, Alfred Xuyang; Yuan, Qiang; Tan, Shawn; Xiao, Yixin; Wang, Danlei; Khoo, Audrey Tze Ting; Sani, Levena; Tran, Hoang-Dai; Kim, Paul; Chiew, Yong Seng; Lee, Kea Joo; Yen, Yi-Chun; Ng, Huck Hui; Lim, Bing; Je, Hyunsoo Shawn

    2016-08-16

    Gamma-aminobutyric acid (GABA)-releasing interneurons play an important modulatory role in the cortex and have been implicated in multiple neurological disorders. Patient-derived interneurons could provide a foundation for studying the pathogenesis of these diseases as well as for identifying potential therapeutic targets. Here, we identified a set of genetic factors that could robustly induce human pluripotent stem cells (hPSCs) into GABAergic neurons (iGNs) with high efficiency. We demonstrated that the human iGNs express neurochemical markers and exhibit mature electrophysiological properties within 6-8 weeks. Furthermore, in vitro, iGNs could form functional synapses with other iGNs or with human-induced glutamatergic neurons (iENs). Upon transplantation into immunodeficient mice, human iGNs underwent synaptic maturation and integration into host neural circuits. Taken together, our rapid and highly efficient single-step protocol to generate iGNs may be useful to both mechanistic and translational studies of human interneurons. PMID:27498872

  12. Interplay of environmental signals and progenitor diversity on fate specification of cortical GABAergic neurons

    PubMed Central

    Romcy-Pereira, Rodrigo N.

    2015-01-01

    Cortical GABAergic interneurons constitute an extremely diverse population of cells organized in a well-defined topology of precisely interconnected cells. They play a crucial role regulating inhibitory-excitatory balance in brain circuits, gating sensory perception, and regulating spike timing to brain oscillations during distinct behaviors. Dysfunctions in the establishment of proper inhibitory circuits have been associated to several brain disorders such as autism, epilepsy, and schizophrenia. In the rodent adult cortex, inhibitory neurons are generated during the second gestational week from distinct progenitor lineages located in restricted domains of the ventral telencephalon. However, only recently, studies have revealed some of the mechanisms generating the heterogeneity of neuronal subtypes and their modes of integration in brain networks. Here we will discuss some the events involved in the production of cortical GABAergic neuron diversity with focus on the interaction between intrinsically driven genetic programs and environmental signals during development. PMID:25972784

  13. Selective degeneration of septal and hippocampal GABAergic neurons in a mouse model of amyloidosis and tauopathy.

    PubMed

    Loreth, Desirée; Ozmen, Laurence; Revel, Florent G; Knoflach, Frédéric; Wetzel, Philine; Frotscher, Michael; Metzger, Friedrich; Kretz, Oliver

    2012-07-01

    Alzheimer's disease (AD) is a neurodegenerative disorder characterized by brain accumulation of amyloid-β peptide and neurofibrillary tangles, which are believed to initiate a pathological cascade that results in progressive impairment of cognitive functions and eventual neuronal death. To obtain a mouse model displaying the typical AD histopathology of amyloidosis and tauopathy, we generated a triple-transgenic mouse line (TauPS2APP) by overexpressing human mutations of the amyloid precursor protein, presenilin2 and tau genes. Stereological analysis of TauPS2APP mice revealed significant neurodegeneration of GABAergic septo-hippocampal projection neurons as well as their target cells, the GABAergic hippocampal interneurons. In contrast, the cholinergic medial septum neurons remained unaffected. Moreover, the degeneration of hippocampal GABAergic interneurons was dependent on the hippocampal subfield and interneuronal subtype investigated, whereby the dentate gyrus and the NPY-positive interneurons, respectively, were most strongly affected. Neurodegeneration was also accompanied by a change in the mRNA expression of markers for inhibitory interneurons. In line with the loss of inhibitory neurons, we observed functional changes in TauPS2APP mice relative to WT mice, with strongly enhanced long-term potentiation in the medial-perforant pathway input to the dentate gyrus, and stereotypic hyperactivity. Our data indicate that inhibitory neurons are the targets of neurodegeneration in a mouse model of amyloidosis and tauopathy, thus pointing to a possible role of the inhibitory network in the pathophysiological and functional cascade of Alzheimer's disease.

  14. Discharge profiles of identified GABAergic in comparison to cholinergic and putative glutamatergic basal forebrain neurons across the sleep-wake cycle.

    PubMed

    Hassani, Oum Kaltoum; Lee, Maan Gee; Henny, Pablo; Jones, Barbara E

    2009-09-23

    Whereas basal forebrain (BF) cholinergic neurons are known to participate in processes of cortical activation during wake (W) and paradoxical sleep (PS or P, also called REM sleep), codistributed GABAergic neurons have been thought to participate in processes of cortical deactivation and slow-wave sleep (SWS or S). To learn the roles the GABAergic neurons might play, in relation to cholinergic and glutamatergic neurons, we juxtacellularly recorded and labeled neurons during natural sleep-wake states in head-fixed rats. Neurobiotin (Nb)-labeled cells were identified immunohistochemically as choline acetyltransferase (ChAT)+, glutamic acid decarboxylase (GAD)+, or ChAT-/GAD-. Of the latter, some were identified as glutamatergic by immunostaining of their terminals with the vesicular glutamate transporter (VGluT2). In contrast to ChAT+ neurons, which all discharged maximally during W and PS, GAD+ neurons comprised multiple sleep-wake subgroups. Some GABAergic neurons discharged maximally during W and PS, as WP-max active cells (36%), and in positive correlation with gamma electroencephalographic (EEG) activity. Some discharged maximally during SWS, as S-max active cells (28%), and in positive correlation with delta EEG activity. Others increased their discharge progressively during sleep to discharge maximally during PS, as P-max active cells (36%), and in negative association with electromyographic (EMG) activity. ChAT-/GAD- cells comprised WP-max (46%), S-max (17%), P-max (17%), and W-max active cells (14%), whose discharge was positively correlated with EMG activity. GABAergic neurons would thus play similar or reciprocal roles to other cholinergic and glutamatergic BF neurons in regulating cortical activity and muscle tone along with behavior across sleep-wake states.

  15. GABAergic Projection Neurons Route Selective Olfactory Inputs to Specific Higher Order Neurons

    PubMed Central

    Liang, Liang; Li, Yulong; Potter, Christopher J.; Yizhar, Ofer; Deisseroth, Karl; Tsien, Richard W.; Luo, Liqun

    2013-01-01

    Summary We characterize an inhibitory circuit motif in the Drosophila olfactory system, parallel inhibition, which differs from feed-forward or feedback inhibition. Excitatory and GABAergic inhibitory projection neurons (ePNs and iPNs) each receive input from antennal lobe glomeruli and send parallel output to the lateral horn, a higher center implicated in regulating innate olfactory behavior. Ca2+ imaging of specific lateral horn neurons as an olfactory readout revealed that iPNs selectively suppress food-related odorant responses, but spared signal transmission from pheromone channels. Co-applying food odorant did not affect pheromone signal transmission, suggesting that the differential effects likely result from connection specificity of iPNs, rather than a generalized inhibitory tone. Ca2+ responses in the ePN axon terminals show no detectable suppression by iPNs, arguing against presynaptic inhibition as a primary mechanism. The parallel inhibition motif may provide specificity in inhibition to funnel specific olfactory information, such as food and pheromone, into distinct downstream circuits. PMID:24012005

  16. GABAergic neurons immunoreactive for calcium binding proteins are reduced in the prefrontal cortex in major depression.

    PubMed

    Rajkowska, Grazyna; O'Dwyer, Gillian; Teleki, Zsofia; Stockmeier, Craig A; Miguel-Hidalgo, Jose Javier

    2007-02-01

    Post-mortem morphometric studies report reductions in the average density and size of cortical neurons in the dorsolateral prefrontal cortex (dlPFC) and orbitofrontal cortex (ORB) in major depressive disorder (MDD). The contribution of specific neuronal phenotypes to this general pathology in depression is still unclear. Post-mortem sections from the dlPFC and ORB regions of 14 subjects with MDD and 11 controls were immunostained to visualize calbindin-immunoreactive (CB-IR) and parvalbumin-immunoreactive (PV-IR) presumptive GABAergic neurons. A three-dimensional cell counting probe was used to assess the cell packing density and size of CB-IR neurons in layers II+IIIa and PV-IR neurons in layers III-VI. The density of CB-IR neurons was significantly reduced by 50% in depression in the dlPFC and there was a trend toward reduction in the ORB. The size of CB-IR somata was significantly decreased (18%) in depression in the dlPFC with a trend toward reduction in the ORB. In contrast, there was no difference in the density of PV-IR neurons between the depressed and control groups in the dlPFC. The size of PV-IR neuronal soma was unchanged in depressed compared to control subjects in either dlPFC or ORB. In depression, subpopulations of GABAergic neurons may be affected differently in dlPFC and ORB. A significant reduction in the density and size of GABAergic interneurons immunoreactive for calcium binding proteins was found predominantly in the dlPFC region. These cellular changes are consistent with recent neuroimaging studies revealing a reduction in the cortical levels of GABA in depression. PMID:17063153

  17. Nicotine enhances inhibition of mouse vagal motor neurons by modulating excitability of premotor GABAergic neurons in the nucleus tractus solitarii

    PubMed Central

    Xu, Hong; Boychuk, Jeffery A.; Boychuk, Carie R.; Uteshev, Victor V.

    2014-01-01

    The caudal nucleus of the solitary tract (NTS) serves as the site of the first synapse for visceral sensory inputs to the central nervous system. The NTS sends functional projections to multiple brain nuclei, with gastric-related projections primarily targeting the dorsal motor nucleus of the vagus (DMV). Previous studies have demonstrated that the majority of caudal NTS neurons that project to the DMV respond robustly to nicotine and express nicotinic acetylcholine receptors (nAChRs). However, the cytochemical identity and relationship with specific viscera of DMV-projecting, nicotine-responsive caudal NTS neurons have not been determined. The present study used transgenic mice that express enhanced green fluorescent protein (EGFP) under a GAD67 promoter in a subset of GABAergic neurons, in vivo retrograde pseudorabies viral labeling to identify gastric-related vagal complex neurons, and patch-clamp electrophysiology in acute brain stem slices to test the hypothesis that gastric-related and GABAergic inhibitory synaptic input to the DMV from the caudal NTS is under a robust modulatory control by nAChRs. Our results suggest that activation of nAChRs in the caudal NTS, but not DMV, potentiates GABAergic, but not glutamatergic, input to the DMV. Gastric-related caudal NTS and DMV neurons are directly involved in this nicotine-sensitive circuitry. Understanding the central patterns of nicotinic modulation of visceral sensory-motor circuitry may help develop therapeutic interventions to restore autonomic homeostasis in patients with autonomic impairments. PMID:25429117

  18. Raphe GABAergic neurons mediate the acquisition of avoidance after social defeat.

    PubMed

    Challis, Collin; Boulden, Janette; Veerakumar, Avin; Espallergues, Julie; Vassoler, Fair M; Pierce, R Christopher; Beck, Sheryl G; Berton, Olivier

    2013-08-28

    Serotonin (5-HT) modulates neural responses to socioaffective cues and can bias approach or avoidance behavioral decisions, yet the cellular mechanisms underlying its contribution to the regulation of social experiences remain poorly understood. We hypothesized that GABAergic neurons in the dorsal raphe nucleus (DRN) may participate in socioaffective regulation by controlling serotonergic tone during social interaction. We tested this hypothesis using whole-cell recording techniques in genetically identified DRN GABA and 5-HT neurons in mice exposed to social defeat, a model that induces long-lasting avoidance behaviors in a subset of mice responsive to serotonergic antidepressants. Our results revealed that social defeat engaged DRN GABA neurons and drove GABAergic sensitization that strengthened inhibition of 5-HT neurons in mice that were susceptible, but not resilient to social defeat. Furthermore, optogenetic silencing of DRN GABA neurons disinhibited neighboring 5-HT neurons and prevented the acquisition of social avoidance in mice exposed to a social threat, but did not affect a previously acquired avoidance phenotype. We provide the first characterization of GABA neurons in the DRN that monosynaptically inhibit 5-HT neurons and reveal their key role in neuroplastic processes underlying the development of social avoidance.

  19. Raphe GABAergic Neurons Mediate the Acquisition of Avoidance after Social Defeat

    PubMed Central

    Challis, Collin; Boulden, Janette; Veerakumar, Avin; Espallergues, Julie; Vassoler, Fair M.; Pierce, R. Christopher

    2013-01-01

    Serotonin (5-HT) modulates neural responses to socioaffective cues and can bias approach or avoidance behavioral decisions, yet the cellular mechanisms underlying its contribution to the regulation of social experiences remain poorly understood. We hypothesized that GABAergic neurons in the dorsal raphe nucleus (DRN) may participate in socioaffective regulation by controlling serotonergic tone during social interaction. We tested this hypothesis using whole-cell recording techniques in genetically identified DRN GABA and 5-HT neurons in mice exposed to social defeat, a model that induces long-lasting avoidance behaviors in a subset of mice responsive to serotonergic antidepressants. Our results revealed that social defeat engaged DRN GABA neurons and drove GABAergic sensitization that strengthened inhibition of 5-HT neurons in mice that were susceptible, but not resilient to social defeat. Furthermore, optogenetic silencing of DRN GABA neurons disinhibited neighboring 5-HT neurons and prevented the acquisition of social avoidance in mice exposed to a social threat, but did not affect a previously acquired avoidance phenotype. We provide the first characterization of GABA neurons in the DRN that monosynaptically inhibit 5-HT neurons and reveal their key role in neuroplastic processes underlying the development of social avoidance. PMID:23986235

  20. The glutaminergic, GABAergic, dopaminergic but not cholinergic neurons are susceptible to anaesthesia-induced cell death in the rat developing brain.

    PubMed

    Zhou, Z-W; Shu, Y; Li, M; Guo, X; Pac-Soo, C; Maze, M; Ma, D

    2011-02-01

    Neuronal cell death induced by anaesthetics in the developing brain was evident in previous pre-clinical studies. However, the neuronal cell types involved in anaesthesia-induced neuronal cell death remains elusive. The aim of this study was to investigate glutamatergic, GABAergic, cholinergic and dopaminergic neuronal cell apoptosis induced by anaesthetic exposure in specific brain regions in rats. Separate cohorts of 7-day-old Sprague Dawley (SD) rat pups were randomly assigned to two groups: Naive and anaesthetics alone (70% nitrous oxide and 0.75% isoflurane exposure for 6 h). The brains were sectioned and the slices that contained the basal forebrain, substantia nigra, cornu ammonis area 1 (CA1) subarea of hippocampus or cingulate cortex were selected and subsequently subjected to double-labelled fluorescent immunohistochemistry for choline acetyltransferase, dopamine, vesicular glutamate transporter 1 (vGLUT1) or glutamic acid decarboxylase 67 (GAD67) together with caspase 3, respectively. Compared to the naive control, anaesthetic exposure significantly increased the number of caspase-3 positive cells in the CA1 subarea of hippocampus, cingulate cortex, and substantia nigra, but not in the basal forebrain. 54% and 14% of apoptotic cells in the CA1 subarea of hippocampus were GABAergic and glutamatergic neurons respectively. In the cingulate cortex, 30% and 37% of apoptotic cells were GABAergic and glutamatergic neurons respectively. In the substantia nigra, 22% of apoptotic cells were dopaminergic neurons. Our data suggests, anaesthetic exposure significantly increases neuroapoptosis of glutamatergic, GABAergic and dopaminergic neurons in the developing brain but not that of the cholinergic neurons in the basal forebrain. PMID:21056635

  1. Co-release of glutamate and GABA from single vesicles in GABAergic neurons exogenously expressing VGLUT3

    PubMed Central

    Zimmermann, Johannes; Herman, Melissa A.; Rosenmund, Christian

    2015-01-01

    The identity of the vesicle neurotransmitter transporter expressed by a neuron largely corresponds with the primary neurotransmitter that cell releases. However, the vesicular glutamate transporter subtype 3 (VGLUT3) is mainly expressed in non-glutamatergic neurons, including cholinergic, serotonergic, or GABAergic neurons. Though a functional role for glutamate release from these non-glutamatergic neurons has been demonstrated, the interplay between VGLUT3 and the neuron’s characteristic neurotransmitter transporter, particularly in the case of GABAergic neurons, at the synaptic and vesicular level is less clear. In this study, we explore how exogenous expression of VGLUT3 in striatal GABAergic neurons affects the packaging and release of glutamate and GABA in synaptic vesicles (SVs). We found that VGLUT3 expression in isolated, autaptic GABAergic neurons leads to action potential evoked release of glutamate. Under these conditions, glutamate and GABA could be packaged together in single vesicles release either spontaneously or asynchronously. However, the presence of glutamate in GABAergic vesicles did not affect uptake of GABA itself, suggesting a lack of synergy in vesicle filling for these transmitters. Finally, we found postsynaptic detection of glutamate released from GABAergic terminals difficult when bona fide glutamatergic synapses were present, suggesting that co-released glutamate cannot induce postsynaptic glutamate receptor clustering. PMID:26441632

  2. DEVELOPMENTAL HYPOTHYROIDISM REDUCES PARVALBUMIN EXPRESSION IN GABAERGIC NEURONS OF CORTEX AND HIPPOCAMPUS: IMMUNOHISTOCHEMICAL FINDINGS AND FUNCTIONAL CORRELATES.

    EPA Science Inventory

    GABAergic interneurons comprise the bulk of local inhibitory neuronal circuitry in cortex and hippocampus and a subpopulation of these interneurons contain the calcium binding protein, parvalbumin (PV). A previous report indicated that severe hypothyroidism reduced PV immunoreact...

  3. Distribution of type 1 cannabinoid receptor-expressing neurons in the septal-hypothalamic region of the mouse: colocalization with GABAergic and glutamatergic markers.

    PubMed

    Hrabovszky, Erik; Wittmann, Gábor; Kalló, Imre; Füzesi, Tamás; Fekete, Csaba; Liposits, Zsolt

    2012-04-01

    Type 1 cannabinoid receptor (CB1) is the principal mediator of retrograde endocannabinoid signaling in the brain. In this study, we addressed the topographic distribution and amino acid neurotransmitter phenotype of endocannabinoid-sensitive hypothalamic neurons in mice. The in situ hybridization detection of CB1 mRNA revealed high levels of expression in the medial septum (MS) and the diagonal band of Broca (DBB), moderate levels in the preoptic area and the hypothalamic lateroanterior (LA), paraventricular (Pa), ventromedial (VMH), lateral mammillary (LM), and ventral premammillary (PMV) nuclei, and low levels in many other hypothalamic regions including the suprachiasmatic (SCh) and arcuate (Arc) nuclei. This regional distribution pattern was compared with location of γ-aminobutyric acid (GABA)ergic and glutamatergic cell groups, as identified by the expression of glutamic acid decarboxylase 65 (GAD65) and type 2 vesicular glutamate transporter (VGLUT2) mRNAs, respectively. The MS, DBB, and preoptic area showed overlaps between GABAergic and CB1-expressing neurons, whereas hypothalamic sites with moderate CB1 signals, including the LA, Pa, VMH, LM, and PMV, were dominated by glutamatergic neurons. Low CB1 mRNA levels were also present in other glutamatergic and GABAergic regions. Dual-label in situ hybridization experiments confirmed the cellular co-expression of CB1 with both glutamatergic and GABAergic markers. In this report we provide a detailed anatomical map of hypothalamic glutamatergic and GABAergic systems whose neurotransmitter release is controlled by retrograde endocannabinoid signaling from hypothalamic and extrahypothalamic target neurons. This neuroanatomical information contributes to an understanding of the role that the endocannabinoid system plays in the regulation of endocrine and metabolic functions.

  4. The presence of pacemaker HCN channels identifies theta rhythmic GABAergic neurons in the medial septum

    PubMed Central

    Varga, Viktor; Hangya, Balázs; Kránitz, Kinga; Ludányi, Anikó; Zemankovics, Rita; Katona, István; Shigemoto, Ryuichi; Freund, Tamás F; Borhegyi, Zsolt

    2008-01-01

    The medial septum (MS) is an indispensable component of the subcortical network which synchronizes the hippocampus at theta frequency during specific stages of information processing. GABAergic neurons exhibiting highly regular firing coupled to the hippocampal theta rhythm are thought to form the core of the MS rhythm-generating network. In recent studies the hyperpolarization-activated, cyclic nucleotide-gated non-selective cation (HCN) channel was shown to participate in theta synchronization of the medial septum. Here, we tested the hypothesis that HCN channel expression correlates with theta modulated firing behaviour of MS neurons by a combined anatomical and electrophysiological approach. HCN-expressing neurons represented a subpopulation of GABAergic cells in the MS partly overlapping with parvalbumin (PV)-containing neurons. Rhythmic firing in the theta frequency range was characteristic of all HCN-expressing neurons. In contrast, only a minority of HCN-negative cells displayed theta related activity. All HCN cells had tight phase coupling to hippocampal theta waves. As a group, PV-expressing HCN neurons had a marked bimodal phase distribution, whereas PV-immunonegative HCN neurons did not show group-level phase preference despite significant individual phase coupling. Microiontophoretic blockade of HCN channels resulted in the reduction of discharge frequency, but theta rhythmic firing was perturbed only in a few cases. Our data imply that HCN-expressing GABAergic neurons provide rhythmic drive in all phases of the hippocampal theta activity. In most MS theta cells rhythm genesis is apparently determined by interactions at the level of the network rather than by the pacemaking property of HCN channels alone. PMID:18565991

  5. Loss of GABAergic cortical neurons underlies the neuropathology of Lafora disease

    PubMed Central

    2014-01-01

    Background Lafora disease is an autosomal recessive form of progressive myoclonic epilepsy caused by defects in the EPM2A and EPM2B genes. Primary symptoms of the pathology include seizures, ataxia, myoclonus, and progressive development of severe dementia. Lafora disease can be caused by defects in the EPM2A gene, which encodes the laforin protein phosphatase, or in the NHLRC1 gene (also called EPM2B) codifying the malin E3 ubiquitin ligase. Studies on cellular models showed that laforin and malin interact and operate as a functional complex apparently regulating cellular functions such as glycogen metabolism, cellular stress response, and the proteolytic processes. However, the pathogenesis and the molecular mechanism of the disease, which imply either laforin or malin are poorly understood. Thus, the aim of our study is to elucidate the molecular mechanism of the pathology by characterizing cerebral cortex neurodegeneration in the well accepted murine model of Lafora disease EPM2A-/- mouse. Results In this article, we want to asses the primary cause of the neurodegeneration in Lafora disease by studying GABAergic neurons in the cerebral cortex. We showed that the majority of Lafora bodies are specifically located in GABAergic neurons of the cerebral cortex of 3 months-old EPM2A-/- mice. Moreover, GABAergic neurons in the cerebral cortex of younger mice (1 month-old) are decreased in number and present altered neurotrophins and p75NTR signalling. Conclusions Here, we concluded that there is impairment in GABAergic neurons neurodevelopment in the cerebral cortex, which occurs prior to the formation of Lafora bodies in the cytoplasm. The dysregulation of cerebral cortex development may contribute to Lafora disease pathogenesis. PMID:24472629

  6. Nitric Oxide Modulation of GABAergic Synaptic Transmission in Mechanically Isolated Rat Auditory Cortical Neurons

    PubMed Central

    2009-01-01

    The auditory cortex (A1) encodes the acquired significance of sound for the perception and interpretation of sound. Nitric oxide (NO) is a gas molecule with free radical properties that functions as a transmitter molecule and can alter neural activity without direct synaptic connections. We used whole-cell recordings under voltage clamp to investigate the effect of NO on spontaneous GABAergic synaptic transmission in mechanically isolated rat auditory cortical neurons preserving functional presynaptic nerve terminals. GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) in the A1 were completely blocked by bicuculline. The NO donor, S-nitroso-N-acetylpenicillamine (SNAP), reduced the GABAergic sIPSC frequency without affecting the mean current amplitude. The SNAP-induced inhibition of sIPSC frequency was mimicked by 8-bromoguanosine cyclic 3',5'-monophosphate, a membrane permeable cyclic-GMP analogue, and blocked by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a specific NO scavenger. Blockade of presynaptic K+ channels by 4-aminopyridine, a K+ channel blocker, increased the frequencies of GABAergic sIPSCs, but did not affect the inhibitory effects of SNAP. However, blocking of presynaptic Ca2+ channels by Cd2+, a general voltage-dependent Ca2+ channel blocker, decreased the frequencies of GABAergic sIPSCs, and blocked SNAP-induced reduction of sIPSC frequency. These findings suggest that NO inhibits spontaneous GABA release by activation of cGMP-dependent signaling and inhibition of presynaptic Ca2+ channels in the presynaptic nerve terminals of A1 neurons. PMID:20054493

  7. Perineuronal nets affect parvalbumin expression in GABAergic neurons of the mouse hippocampus.

    PubMed

    Yamada, J; Ohgomori, T; Jinno, S

    2015-02-01

    Recent studies have suggested that the perineuronal net (PNN), a specialised extracellular matrix structure, and parvalbumin (PV), an EF-hand calcium-binding protein, are involved in the regulation of plasticity of neural circuits. Here, we aimed to quantitatively estimate the relationship between the two plasticity regulators, PV and PNNs, in the hippocampus of young adult mice. Dual fluorescence staining for PV and Wisteria floribunda agglutinin (a broad PNN marker) showed that a substantial population of PV-expressing (PV(+) ) GABAergic neurons lacked PNNs. Optical disector analysis demonstrated that there were fewer PNN(+) neurons than PV(+) neurons. The ratio of PNN expression in PV(+) neurons was generally lower in the dendritic layers than in the principal cell layers, whereas the ratio of PV expression in PNN(+) neurons was effectively 100%. The mean PV fluorescence was significantly higher in PNN(+) /PV(+) neurons than in PNN(-) /PV(+) neurons. Cumulative frequencies for single-cell PV fluorescence indicated that intensely stained PV(+) neurons tend to be enwrapped by PNNs, whereas weakly stained PV(+) neurons are likely to lack PNNs. We digested the PNNs by a unilateral injection of chondroitinase ABC (chABC) into the dorsal CA1 region. Although the densities of PV(+) neurons remained unchanged, the PV fluorescence declined 7 days after chABC injection. Quantitative real-time polymerase chain reaction analysis demonstrated a reduction in PV mRNA expression following chABC injection. These findings indicate that the presence or absence of PNNs affects the relative PV expression in GABAergic neurons in the hippocampus.

  8. Differential presynaptic actions of pyrethroid insecticides on glutamatergic and GABAergic neurons in the hippocampus.

    PubMed

    Hossain, Muhammad Mubarak; Suzuki, Tadahiko; Unno, Toshihiro; Komori, Seiichi; Kobayashi, Haruo

    2008-01-14

    This study was designed to investigate the effects of several pyrethroids on the extracellular level of glutamate and gamma-aminobutyric acid (GABA) in the hippocampus of rats measured using microdialysis following systemic (i.p.) administration. Pyrethroids, allethrin (type I), cyhalothrin (type II) and deltamethrin (type II), were found to have differential effects on glutamatergic and GABAergic neurons in the hippocampus. Allethrin had an interesting dual effect, increasing glutamate release with low doses (10 and 20mg/kg) to about 175-150% and decreasing glutamate release with high dose (60 mg/kg) to about 50% of baseline. Cyhalothrin (10, 20 and 60 mg/kg) inhibited the release of glutamate dose-dependently to about 60-30% of baseline. The extracellular level of GABA was decreased to about 50% of baseline by 10 and 20mg/kg allethrin. The high dose of allethrin (60 mg/kg) and all doses of cyhalothrin (10, 20 and 60 mg/kg) increased the extracellular level of GABA while decreasing the level of glutamate. Deltamethrin dose-dependently increased extracellular glutamate levels to about 190-275% of baseline while decreasing the level of GABA. Local infusion of TTX (1 microM), a Na(+) channel blocker, completely prevented the effect of allethrin (10, 20 and 60 mg/kg), cyhalothrin (20 and 60 mg/kg) and deltamethrin (20mg/kg) on glutamate and GABA release, but only partially blocked the effects of 60 mg/kg deltamethrin. The effect of deltamethrin (60 mg/kg) on glutamate release was completely prevented by local infusion of nimodipine (10 microM), an L-type Ca(2+) channel blocker. Collectively, results from this study suggest that the excitatory glutamatergic neurons in the hippocampus are modulated by inhibitory GABA-releasing interneurons and that other mechanisms, beside sodium channels, may be involved with the neurotoxic action of pyrethroids.

  9. [REM sleep modulation by non-GABAergic neurons of the hypothalamus and basal forebrain].

    PubMed

    Reinoso Suárez, Fernando

    2010-01-01

    The ventral part of the oral pontine reticular nucleus (vRPO) is a demonstrated site of brainstem REM-sleep generation and maintenance. The vRPO has reciprocal connections with structures that control other states of the sleep-wakefulness cycle, many situated in the basal forebrain and the diencephalon. The aim of the present revision is to map, using the results described in previous publications of our group, the local origin of the basal forebrain and hypothalamus non-GABAergic projections to the vRPO, and specially the contribution of the hypothalamic neurons positive to hypocretin/orexin (H/O) peptides. I summarize non-GABAergic projections to the vRPO from the: ipsilateral central amygdaline nucleus and the stria terminalis bed nuclei, bilateral projections, but most abundant in the ipsilateral side, from the median preoptic nucleus, medial and lateral preoptic areas, abundant from the zona incerta and dorsal, lateral, posterior and perifornical hypothalamic areas. Very abundant bilateral projections of H/O neurons to the vRPO are described, expressive of the important modulation exerted by these neurons on the vRPO nucleus. I discuss the functional significance of the above results and the corresponding mechanisms, supported by physiological and ultrastructural results of our group. Based on the connections and action mechanisms of H/O neurons on the vRPO, which produce the decreased activity of neurons in this nucleus and, therefore, inhibition of REM sleep, I reflect briefly on narcolepsy pathophysiology.

  10. Pyramidal cells make specific connections onto smooth (GABAergic) neurons in mouse visual cortex.

    PubMed

    Bopp, Rita; Maçarico da Costa, Nuno; Kampa, Björn M; Martin, Kevan A C; Roth, Morgane M

    2014-08-01

    One of the hallmarks of neocortical circuits is the predominance of recurrent excitation between pyramidal neurons, which is balanced by recurrent inhibition from smooth GABAergic neurons. It has been previously described that in layer 2/3 of primary visual cortex (V1) of cat and monkey, pyramidal cells filled with horseradish peroxidase connect approximately in proportion to the spiny (excitatory, 95% and 81%, respectively) and smooth (GABAergic, 5% and 19%, respectively) dendrites found in the neuropil. By contrast, a recent ultrastructural study of V1 in a single mouse found that smooth neurons formed 51% of the targets of the superficial layer pyramidal cells. This suggests that either the neuropil of this particular mouse V1 had a dramatically different composition to that of V1 in cat and monkey, or that smooth neurons were specifically targeted by the pyramidal cells in that mouse. We tested these hypotheses by examining similar cells filled with biocytin in a sample of five mice. We found that the average composition of the neuropil in V1 of these mice was similar to that described for cat and monkey V1, but that the superficial layer pyramidal cells do form proportionately more synapses with smooth dendrites than the equivalent neurons in cat or monkey. These distributions may underlie the distinct differences in functional architecture of V1 between rodent and higher mammals.

  11. Diminished Perisomatic GABAergic Terminals on Cortical Neurons Adjacent to Amyloid Plaques

    PubMed Central

    Garcia-Marin, Virginia; Blazquez-Llorca, Lidia; Rodriguez, José-Rodrigo; Boluda, Susana; Muntane, Gerard; Ferrer, Isidro; DeFelipe, Javier

    2009-01-01

    One of the main pathological hallmarks of Alzheimer's disease (AD) is the accumulation of plaques in the cerebral cortex, which may appear either in the neuropil or in direct association with neuronal somata. Since different axonal systems innervate the dendritic (mostly glutamatergic) and perisomatic (mostly GABAergic) regions of neurons, the accumulation of plaques in the neuropil or associated with the soma might produce different alterations to synaptic circuits. We have used a variety of conventional light, confocal and electron microscopy techniques to study their relationship with neuronal somata in the cerebral cortex from AD patients and APP/PS1 transgenic mice. The main finding was that the membrane surfaces of neurons (mainly pyramidal cells) in contact with plaques lack GABAergic perisomatic synapses. Since these perisomatic synapses are thought to exert a strong influence on the output of pyramidal cells, their loss may lead to the hyperactivity of the neurons in contact with plaques. These results suggest that plaques modify circuits in a more selective manner than previously thought. PMID:19949482

  12. Medial septal GABAergic projection neurons promote object exploration behavior and type 2 theta rhythm.

    PubMed

    Gangadharan, Gireesh; Shin, Jonghan; Kim, Seong-Wook; Kim, Angela; Paydar, Afshin; Kim, Duk-Soo; Miyazaki, Taisuke; Watanabe, Masahiko; Yanagawa, Yuchio; Kim, Jinhyun; Kim, Yeon-Soo; Kim, Daesoo; Shin, Hee-Sup

    2016-06-01

    Exploratory drive is one of the most fundamental emotions, of all organisms, that are evoked by novelty stimulation. Exploratory behavior plays a fundamental role in motivation, learning, and well-being of organisms. Diverse exploratory behaviors have been described, although their heterogeneity is not certain because of the lack of solid experimental evidence for their distinction. Here we present results demonstrating that different neural mechanisms underlie different exploratory behaviors. Localized Cav3.1 knockdown in the medial septum (MS) selectively enhanced object exploration, whereas the null mutant (KO) mice showed enhanced-object exploration as well as open-field exploration. In MS knockdown mice, only type 2 hippocampal theta rhythm was enhanced, whereas both type 1 and type 2 theta rhythm were enhanced in KO mice. This selective effect was accompanied by markedly increased excitability of septo-hippocampal GABAergic projection neurons in the MS lacking T-type Ca(2+) channels. Furthermore, optogenetic activation of the septo-hippocampal GABAergic pathway in WT mice also selectively enhanced object exploration behavior and type 2 theta rhythm, whereas inhibition of the same pathway decreased the behavior and the rhythm. These findings define object exploration distinguished from open-field exploration and reveal a critical role of T-type Ca(2+) channels in the medial septal GABAergic projection neurons in this behavior. PMID:27208094

  13. Medial septal GABAergic projection neurons promote object exploration behavior and type 2 theta rhythm

    PubMed Central

    Gangadharan, Gireesh; Shin, Jonghan; Kim, Seong-Wook; Kim, Angela; Paydar, Afshin; Kim, Duk-Soo; Miyazaki, Taisuke; Watanabe, Masahiko; Yanagawa, Yuchio; Kim, Jinhyun; Kim, Yeon-Soo; Kim, Daesoo; Shin, Hee-Sup

    2016-01-01

    Exploratory drive is one of the most fundamental emotions, of all organisms, that are evoked by novelty stimulation. Exploratory behavior plays a fundamental role in motivation, learning, and well-being of organisms. Diverse exploratory behaviors have been described, although their heterogeneity is not certain because of the lack of solid experimental evidence for their distinction. Here we present results demonstrating that different neural mechanisms underlie different exploratory behaviors. Localized Cav3.1 knockdown in the medial septum (MS) selectively enhanced object exploration, whereas the null mutant (KO) mice showed enhanced-object exploration as well as open-field exploration. In MS knockdown mice, only type 2 hippocampal theta rhythm was enhanced, whereas both type 1 and type 2 theta rhythm were enhanced in KO mice. This selective effect was accompanied by markedly increased excitability of septo-hippocampal GABAergic projection neurons in the MS lacking T-type Ca2+ channels. Furthermore, optogenetic activation of the septo-hippocampal GABAergic pathway in WT mice also selectively enhanced object exploration behavior and type 2 theta rhythm, whereas inhibition of the same pathway decreased the behavior and the rhythm. These findings define object exploration distinguished from open-field exploration and reveal a critical role of T-type Ca2+ channels in the medial septal GABAergic projection neurons in this behavior. PMID:27208094

  14. hVGAT-mCherry: a novel molecular tool for analysis of GABAergic neurons derived from human pluripotent stem cells

    PubMed Central

    DeRosa, Brooke A.; Belle, Kinsley C.; Thomas, Blake J.; Cukier, Holly N.; Pericak-Vance, Margaret A.; Vance, Jeffery M.; Dykxhoorn, Derek M.

    2015-01-01

    Background GABAergic synaptic transmission is known to play a critical role in the assembly of neuronal circuits during development and is responsible for maintaining the balance between excitatory and inhibitory signaling in the brain during maturation into adulthood. Importantly, defects in GABAergic neuronal function and signaling have been linked to a number of neurological diseases, including autism spectrum disorders, schizophrenia, and epilepsy. With patient-specific induced pluripotent stem cell (iPSC)-based models of neurological disease, it is now possible to investigate the disease mechanisms that underlie deficits in GABAergic function in affected human neurons. To that end, tools that enable the labeling and purification of viable GABAergic neurons from human pluripotent stem cells would be of great value. Results To address the need for tools that facilitate the identification and isolation of viable GABAergic neurons from the in vitro differentiation of iPSC lines, a cell type-specific promoter-driven fluorescent reporter construct was developed that utilizes the human vesicular GABA transporter (hVGAT) promoter to drive the expression of mCherry specifically in VGAT-expressing neurons. The transduction of iPSC-derived forebrain neuronal cultures with the hVGAT promoter-mCherry lentiviral reporter construct specifically labeled GABAergic neurons. Immunocytochemical analysis of hVGAT-mCherry expression cells showed significant co-labelling with the GABAergic neuronal markers for endogenous VGAT, GABA, and GAD67. Expression of mCherry from the VGAT promoter showed expression in several cortical interneuron subtypes to similar levels. In addition, an effective and reproducible protocol was developed to facilitate the fluorescent activated cell sorting (FACS)-mediated purification of high yields of viable VGAT-positive cells. Conclusions These studies demonstrate the utility of the hVGAT-mCherry reporter construct as an effective tool for studying

  15. Forebrain GABAergic neuron precursors integrate into adult spinal cord and reduce injury-induced neuropathic pain

    PubMed Central

    Bráz, JM; Sharif-Naeini, R; Vogt, D; Kriegstein, A; Alvarez-Buylla, A; Rubenstein, JL; Basbaum, AI

    2012-01-01

    Neuropathic pain is a chronic debilitating disease characterized by mechanical allodynia and spontaneous pain. Because symptoms are often unresponsive to conventional methods of pain treatment, new therapeutic approaches are essential. Here, we describe a strategy that not only ameliorates symptoms of neuropathic pain, but is also potentially disease modifying. We show that transplantation of immature telencephalic GABAergic interneurons from the mouse medial ganglionic eminence (MGE) into the adult mouse spinal cord completely reverses the mechanical hypersensitivity produced by peripheral nerve injury. Underlying this improvement is a remarkable integration of the MGE transplants into the host spinal cord circuitry, in which the transplanted cells make functional connections with both primary afferent and spinal cord neurons. By contrast, MGE transplants were not effective against inflammatory pain. Our findings suggest that MGE-derived GABAergic interneurons overcome the spinal cord hyperexcitability that is a hallmark of nerve-injury induced neuropathic pain. PMID:22632725

  16. The Memory-Impairing Effects of Septal GABA Receptor Activation Involve GABAergic Septo-Hippocampal Projection Neurons

    ERIC Educational Resources Information Center

    Krebs-Kraft, Desiree L.; Wheeler, Marina G.; Parent, Marise B.

    2007-01-01

    Septal infusions of the [gamma]-aminobutyric acid (GABA)[subscript A] agonist muscimol impair memory, and the effect likely involves the hippocampus. GABA[subscript A] receptors are present on the perikarya of cholinergic and GABAergic septo-hippocampal (SH) projections. The current experiments determined whether GABAergic SH projections are…

  17. GABAergic neurons in the medial septal-diagonal band (MSDB) are important for acquisition of the classically conditioned eyeblink response

    PubMed Central

    Roland, J.J.; Janke, K.L.; Servatius, R.J; Pang, K.C.H.

    2013-01-01

    The medial septum and diagonal band of Broca (MSDB) influence hippocampal function through cholinergic, GABAergic and glutamatergic septohippocampal neurons. Nonselective damage of the MSDB or intraseptal scopolamine impairs classical conditioning of the eyeblink response (CCER). Scopolamine preferentially inhibits GABAergic MSDB neurons suggesting that these neurons may be an important modulator of delay CCER, a form of CCER not dependent on the hippocampus. The current study directly examined the importance of GABAergic MSDB neurons in acquisition of delay CCER. Adult male Sprague-Dawley rats received either a sham (PBS) or GABAergic MSDB lesion using GAT1-saporin (SAP). Rats were given two consecutive days of delay eyeblink conditioning with 100 conditioned stimulus (CS)-unconditioned stimulus (US) paired trials. Intraseptal GAT1-SAP impaired acquisition of CCER. The impairment was observed on the first day with sham and lesion groups reaching similar performance by the end of the second day. Our results provide evidence that GABAergic MSDB neurons are an important modulator of delay CCER. The pathways by which MSDB neurons influence the neural circuits necessary for delay CCER are discussed. PMID:24965560

  18. Leptin-Responsive GABAergic Neurons Regulate Fertility through Pathways That Result in Reduced Kisspeptinergic Tone

    PubMed Central

    Martin, Cecilia; Navarro, Víctor M.; Simavli, Serap; Vong, Linh; Carroll, Rona S.; Lowell, Bradford B.

    2014-01-01

    The adipocyte-derived hormone leptin plays a critical role in the central transmission of energy balance to modulate reproductive function. However, the neurocircuitry underlying this interaction remains elusive, in part due to incomplete knowledge of first-order leptin-responsive neurons. To address this gap, we explored the contribution of predominantly inhibitory (GABAergic) neurons versus excitatory (glutamatergic) neurons in the female mouse by selective ablation of the leptin receptor in each neuronal population: Vgat-Cre;Leprlox/lox and Vglut2-Cre;Leprlox/lox mice, respectively. Female Vgat-Cre;Leprlox/lox but not Vglut2-Cre;Leprlox/lox mice were obese. Vgat-Cre;Leprlox/lox mice had delayed or absent vaginal opening, persistent diestrus, and atrophic reproductive tracts with absent corpora lutea. In contrast, Vglut2-Cre;Leprlox/lox females exhibited reproductive maturation and function comparable to Leprlox/lox control mice. Intracerebroventricular administration of kisspeptin-10 to Vgat-Cre;Leprlox/lox female mice elicited robust gonadotropin responses, suggesting normal gonadotropin-releasing hormone neuronal and gonadotrope function. However, adult ovariectomized Vgat-Cre;Leprlox/lox mice displayed significantly reduced levels of Kiss1 (but not Tac2) mRNA in the arcuate nucleus, and a reduced compensatory luteinizing hormone increase compared with control animals. Estradiol replacement after ovariectomy inhibited gonadotropin release to a similar extent in both groups. These animals also exhibited a compromised positive feedback response to sex steroids, as shown by significantly lower Kiss1 mRNA levels in the AVPV, compared with Leprlox/lox mice. We conclude that leptin-responsive GABAergic neurons, but not glutamatergic neurons, act as metabolic sensors to regulate fertility, at least in part through modulatory effects on kisspeptin neurons. PMID:24760864

  19. Novel Nuclear Protein Complexes of Dystrophin 71 Isoforms in Rat Cultured Hippocampal GABAergic and Glutamatergic Neurons

    PubMed Central

    Alemán, Víctor; Osorio, Beatriz; Chávez-González, Oscar; Rendon, Alvaro; Martínez-Rojas, Dalila; Meraz-Ríos, Marco Antonio

    2015-01-01

    The precise functional role of the dystrophin 71 in neurons is still elusive. Previously, we reported that dystrophin 71d and dystrophin 71f are present in nuclei from cultured neurons. In the present work, we performed a detailed analysis of the intranuclear distribution of dystrophin 71 isoforms (Dp71d and Dp71f), during the temporal course of 7-day postnatal rats hippocampal neurons culture for 1h, 2, 4, 10, 15 and 21 days in vitro (DIV). By immunofluorescence assays, we detected the highest level of nuclear expression of both dystrophin Dp71 isoforms at 10 DIV, during the temporal course of primary culture. Dp71d and Dp71f were detected mainly in bipolar GABAergic (≥60%) and multipolar Glutamatergic (≤40%) neurons, respectively. We also characterized the existence of two nuclear dystrophin-associated protein complexes (DAPC): dystrophin 71d or dystrophin 71f bound to β-dystroglycan, α1-, β-, α2-dystrobrevins, α-syntrophin, and syntrophin-associated protein nNOS (Dp71d-DAPC or Dp71f-DAPC, respectively), in the hippocampal neurons. Furthermore, both complexes were localized in interchromatin granule cluster structures (nuclear speckles) of neuronal nucleoskeleton preparations. The present study evinces that each Dp71’s complexes differ slightly in dystrobrevins composition. The results demonstrated that Dp71d-DAPC was mainly localized in bipolar GABAergic and Dp71f-DAPC in multipolar Glutamatergic hippocampal neurons. Taken together, our results show that dystrophin 71d, dystrophin 71f and DAP integrate protein complexes, and both complexes were associated to nuclear speckles structures. PMID:26378780

  20. Novel Nuclear Protein Complexes of Dystrophin 71 Isoforms in Rat Cultured Hippocampal GABAergic and Glutamatergic Neurons.

    PubMed

    Rodríguez-Muñoz, Rafael; Cárdenas-Aguayo, María Del Carmen; Alemán, Víctor; Osorio, Beatriz; Chávez-González, Oscar; Rendon, Alvaro; Martínez-Rojas, Dalila; Meraz-Ríos, Marco Antonio

    2015-01-01

    The precise functional role of the dystrophin 71 in neurons is still elusive. Previously, we reported that dystrophin 71d and dystrophin 71f are present in nuclei from cultured neurons. In the present work, we performed a detailed analysis of the intranuclear distribution of dystrophin 71 isoforms (Dp71d and Dp71f), during the temporal course of 7-day postnatal rats hippocampal neurons culture for 1h, 2, 4, 10, 15 and 21 days in vitro (DIV). By immunofluorescence assays, we detected the highest level of nuclear expression of both dystrophin Dp71 isoforms at 10 DIV, during the temporal course of primary culture. Dp71d and Dp71f were detected mainly in bipolar GABAergic (≥60%) and multipolar Glutamatergic (≤40%) neurons, respectively. We also characterized the existence of two nuclear dystrophin-associated protein complexes (DAPC): dystrophin 71d or dystrophin 71f bound to β-dystroglycan, α1-, β-, α2-dystrobrevins, α-syntrophin, and syntrophin-associated protein nNOS (Dp71d-DAPC or Dp71f-DAPC, respectively), in the hippocampal neurons. Furthermore, both complexes were localized in interchromatin granule cluster structures (nuclear speckles) of neuronal nucleoskeleton preparations. The present study evinces that each Dp71's complexes differ slightly in dystrobrevins composition. The results demonstrated that Dp71d-DAPC was mainly localized in bipolar GABAergic and Dp71f-DAPC in multipolar Glutamatergic hippocampal neurons. Taken together, our results show that dystrophin 71d, dystrophin 71f and DAP integrate protein complexes, and both complexes were associated to nuclear speckles structures.

  1. Functional Upregulation of α4* Nicotinic Acetylcholine Receptors in VTA GABAergic Neurons Increases Sensitivity to Nicotine Reward.

    PubMed

    Ngolab, Jennifer; Liu, Liwang; Zhao-Shea, Rubing; Gao, Guangping; Gardner, Paul D; Tapper, Andrew R

    2015-06-01

    Chronic nicotine exposure increases sensitivity to nicotine reward during a withdrawal period, which may facilitate relapse in abstinent smokers, yet the molecular neuroadaptation(s) that contribute to this phenomenon are unknown. Interestingly, chronic nicotine use induces functional upregulation of nicotinic acetylcholine receptors (nAChRs) in the mesocorticolimbic reward pathway potentially linking upregulation to increased drug sensitivity. In the ventral tegmental area (VTA), functional upregulation of nAChRs containing the α4 subunit (α4* nAChRs) is restricted to GABAergic neurons. To test the hypothesis that increased functional expression of α4* nAChRs in these neurons modulates nicotine reward behaviors, we engineered a Cre recombinase-dependent gene expression system to selectively express α4 nAChR subunits harboring a "gain-of-function" mutation [a leucine mutated to a serine residue at the 9' position (Leu9'Ser)] in VTA GABAergic neurons of adult mice. In mice expressing Leu9'Ser α4 nAChR subunits in VTA GABAergic neurons (Gad2(VTA):Leu9'Ser mice), subreward threshold doses of nicotine were sufficient to selectively activate VTA GABAergic neurons and elicit acute hypolocomotion, with subsequent nicotine exposures eliciting tolerance to this effect, compared to control animals. In the conditioned place preference procedure, nicotine was sufficient to condition a significant place preference in Gad2(VTA):Leu9'Ser mice at low nicotine doses that failed to condition control animals. Together, these data indicate that functional upregulation of α4* nAChRs in VTA GABAergic neurons confers increased sensitivity to nicotine reward and points to nAChR subtypes specifically expressed in GABAergic VTA neurons as molecular targets for smoking cessation therapeutics.

  2. Adenosine A2A receptors regulate the activity of sleep regulatory GABAergic neurons in the preoptic hypothalamus

    PubMed Central

    Kumar, Sunil; Rai, Seema; Hsieh, Kung-Chiao; McGinty, Dennis; Alam, Md. Noor

    2013-01-01

    The median preoptic nucleus (MnPN) and the ventrolateral preoptic area (VLPO) are two hypothalamic regions that have been implicated in sleep regulation, and both nuclei contain sleep-active GABAergic neurons. Adenosine is an endogenous sleep regulatory substance, which promotes sleep via A1 and A2A receptors (A2AR). Infusion of A2AR agonist into the lateral ventricle or into the subarachnoid space underlying the rostral basal forebrain (SS-rBF), has been previously shown to increase sleep. We examined the effects of an A2AR agonist, CGS-21680, administered into the lateral ventricle and the SS-rBF on sleep and c-Fos protein immunoreactivity (Fos-IR) in GABAergic neurons in the MnPN and VLPO. Intracerebroventricular administration of CGS-21680 during the second half of lights-on phase increased sleep and increased the number of MnPN and VLPO GABAergic neurons expressing Fos-IR. Similar effects were found with CGS-21680 microinjection into the SS-rBF. The induction of Fos-IR in preoptic GABAergic neurons was not secondary to drug-induced sleep, since CGS-21680 delivered to the SS-rBF significantly increased Fos-IR in MnPN and VLPO neurons in animals that were not permitted to sleep. Intracerebroventricular infusion of ZM-241385, an A2AR antagonist, during the last 2 h of a 3-h period of sleep deprivation caused suppression of subsequent recovery sleep and reduced Fos-IR in MnPN and VLPO GABAergic neurons. Our findings support a hypothesis that A2AR-mediated activation of MnPN and VLPO GABAergic neurons contributes to adenosinergic regulation of sleep. PMID:23637137

  3. Convergence of Lemniscal and Local Excitatory Inputs on Large GABAergic Tectothalamic Neurons.

    PubMed

    Ito, Tetsufumi; Hioki, Hiroyuki; Sohn, Jaerin; Okamoto, Shinichiro; Kaneko, Takeshi; Iino, Satoshi; Oliver, Douglas L

    2015-10-15

    Large GABAergic (LG) neurons form a distinct cell type in the inferior colliculus (IC), identified by the presence of dense VGLUT2-containing axosomatic terminals. Although some of the axosomatic terminals originate from local and commissural IC neurons, it has been unclear whether LG neurons also receive axosomatic inputs from the lower auditory brainstem nuclei, i.e., cochlear nuclei (CN), superior olivary complex (SOC), and nuclei of the lateral lemniscus (NLL). In this study we injected recombinant viral tracers that force infected cells to express GFP in a Golgi-like manner into the lower auditory brainstem nuclei to determine whether these nuclei directly innervate LG cell somata. Labeled axons from CN, SOC, and NLL terminated as excitatory axosomatic endings, identified by colabeling of GFP and VGLUT2, on single LG neurons in the IC. Each excitatory axon made only a few axosomatic contacts on each LG neuron. Inputs to a single LG cell are unlikely to be from a single brainstem nucleus, since lesions of individual nuclei failed to eliminate most VGLUT2-positive terminals on the LG neurons. The estimated number of inputs on a single LG cell body was almost proportional to the surface area of the cell body. Double injections of different viruses into IC and a brainstem nucleus showed that LG neurons received inputs from both. These results demonstrated that both ascending and intrinsic sources converge on the LG somata to control inhibitory tectothalamic projections.

  4. GABAergic Neuron-Specific Loss of Ube3a Causes Angelman Syndrome-Like EEG Abnormalities and Enhances Seizure Susceptibility.

    PubMed

    Judson, Matthew C; Wallace, Michael L; Sidorov, Michael S; Burette, Alain C; Gu, Bin; van Woerden, Geeske M; King, Ian F; Han, Ji Eun; Zylka, Mark J; Elgersma, Ype; Weinberg, Richard J; Philpot, Benjamin D

    2016-04-01

    Loss of maternal UBE3A causes Angelman syndrome (AS), a neurodevelopmental disorder associated with severe epilepsy. We previously implicated GABAergic deficits onto layer (L) 2/3 pyramidal neurons in the pathogenesis of neocortical hyperexcitability, and perhaps epilepsy, in AS model mice. Here we investigate consequences of selective Ube3a loss from either GABAergic or glutamatergic neurons, focusing on the development of hyperexcitability within L2/3 neocortex and in broader circuit and behavioral contexts. We find that GABAergic Ube3a loss causes AS-like increases in neocortical EEG delta power, enhances seizure susceptibility, and leads to presynaptic accumulation of clathrin-coated vesicles (CCVs)-all without decreasing GABAergic inhibition onto L2/3 pyramidal neurons. Conversely, glutamatergic Ube3a loss fails to yield EEG abnormalities, seizures, or associated CCV phenotypes, despite impairing tonic inhibition onto L2/3 pyramidal neurons. These results substantiate GABAergic Ube3a loss as the principal cause of circuit hyperexcitability in AS mice, lending insight into ictogenic mechanisms in AS.

  5. GABAergic Neuron-Specific Loss of Ube3a Causes Angelman Syndrome-Like EEG Abnormalities and Enhances Seizure Susceptibility.

    PubMed

    Judson, Matthew C; Wallace, Michael L; Sidorov, Michael S; Burette, Alain C; Gu, Bin; van Woerden, Geeske M; King, Ian F; Han, Ji Eun; Zylka, Mark J; Elgersma, Ype; Weinberg, Richard J; Philpot, Benjamin D

    2016-04-01

    Loss of maternal UBE3A causes Angelman syndrome (AS), a neurodevelopmental disorder associated with severe epilepsy. We previously implicated GABAergic deficits onto layer (L) 2/3 pyramidal neurons in the pathogenesis of neocortical hyperexcitability, and perhaps epilepsy, in AS model mice. Here we investigate consequences of selective Ube3a loss from either GABAergic or glutamatergic neurons, focusing on the development of hyperexcitability within L2/3 neocortex and in broader circuit and behavioral contexts. We find that GABAergic Ube3a loss causes AS-like increases in neocortical EEG delta power, enhances seizure susceptibility, and leads to presynaptic accumulation of clathrin-coated vesicles (CCVs)-all without decreasing GABAergic inhibition onto L2/3 pyramidal neurons. Conversely, glutamatergic Ube3a loss fails to yield EEG abnormalities, seizures, or associated CCV phenotypes, despite impairing tonic inhibition onto L2/3 pyramidal neurons. These results substantiate GABAergic Ube3a loss as the principal cause of circuit hyperexcitability in AS mice, lending insight into ictogenic mechanisms in AS. PMID:27021170

  6. Interactions between hypocretinergic and GABAergic systems in the control of activity of neurons in the cat pontine reticular formation.

    PubMed

    Xi, M; Fung, S J; Yamuy, J; Chase, M H

    2015-07-01

    Anatomical studies have demonstrated that hypocretinergic and GABAergic neurons innervate cells in the nucleus pontis oralis (NPO), a nucleus responsible for the generation of active (rapid eye movement (REM)) sleep (AS) and wakefulness (W). Behavioral and electrophysiological studies have shown that hypocretinergic and GABAergic processes in the NPO are involved in the generation of AS as well as W. An increase in hypocretin in the NPO is associated with both AS and W, whereas GABA levels in the NPO are elevated during W. We therefore examined the manner in which GABA modulates NPO neuronal responses to hypocretin. We hypothesized that interactions between the hypocretinergic and GABAergic systems in the NPO play an important role in determining the occurrence of AS or W. To determine the veracity of this hypothesis, we examined the effects of the juxtacellular application of hypocretin-1 and GABA on the activity of NPO neurons, which were recorded intracellularly, in chloralose-anesthetized cats. The juxtacellular application of hypocretin-1 significantly increased the mean amplitude of spontaneous EPSPs and the frequency of discharge of NPO neurons; in contrast, the juxtacellular microinjection of GABA produced the opposite effects, i.e., there was a significant reduction in the mean amplitude of spontaneous EPSPs and a decrease in the discharge of these cells. When hypocretin-1 and GABA were applied simultaneously, the inhibitory effect of GABA on the activity of NPO neurons was reduced or completely blocked. In addition, hypocretin-1 also blocked GABAergic inhibition of EPSPs evoked by stimulation of the laterodorsal tegmental nucleus. These data indicate that hypocretin and GABA function within the context of a neuronal gate that controls the activity of AS-on neurons. Therefore, we suggest that the occurrence of either AS or W depends upon interactions between hypocretinergic and GABAergic processes as well as inputs from other sites that project to AS

  7. Opposing Dopaminergic and GABAergic Neurons Control the Duration and Persistence of Copulation in Drosophila

    PubMed Central

    Crickmore, Michael A.; Vosshall, Leslie B.

    2014-01-01

    SUMMARY Behavioral persistence is a major factor in determiningwhen and under which circumstances animals will terminate their current activity and transition into more profitable, appropriate, or urgent behavior. We show that, for the first 5 min of copulation in Drosophila, stressful stimuli do not interrupt mating, whereas 10 min later, even minor perturbations are sufficient to terminate copulation. This decline in persistence occurs as the probability of successful mating increases and is promoted by approximately eight sexually dimorphic, GABAergic interneurons of the male abdominal ganglion. When these interneurons were silenced, persistence increased and males copulated far longer than required for successful mating. When these interneurons were stimulated, persistence decreased and copulations were shortened. In contrast, dopaminergic neurons of the ventral nerve cord promote copulation persistence and extend copulation duration. Thus, copulation duration in Drosophila is a product of gradually declining persistence controlled by opposing neuronal populations using conserved neurotransmission systems. PMID:24209625

  8. Glutamate Decarboxylase 67 Deficiency in a Subset of GABAergic Neurons Induces Schizophrenia-Related Phenotypes

    PubMed Central

    Fujihara, Kazuyuki; Miwa, Hideki; Kakizaki, Toshikazu; Kaneko, Ryosuke; Mikuni, Masahiko; Tanahira, Chiyoko; Tamamaki, Nobuaki; Yanagawa, Yuchio

    2015-01-01

    Decreased expression of the GABA synthetic enzyme glutamate decarboxylase 67 (GAD67) in a subset of GABAergic neurons, including parvalbumin (PV)-expressing neurons, has been observed in postmortem brain studies of schizophrenics and in animal models of schizophrenia. However, it is unclear whether and how the perturbations of GAD67-mediated GABA synthesis and signaling contribute to the pathogenesis of schizophrenia. To address this issue, we generated the mice lacking GAD67 primarily in PV neurons and characterized them with focus on schizophrenia-related parameters. We found that heterozygous mutant mice exhibited schizophrenia-related behavioral abnormalities such as deficits in prepulse inhibition, MK-801 sensitivity, and social memory. Furthermore, we observed reduced inhibitory synaptic transmission, altered properties of NMDA receptor-mediated synaptic responses in pyramidal neurons, and increased spine density in hippocampal CA1 apical dendrites, suggesting a possible link between GAD67 deficiency and disturbed glutamatergic excitatory synaptic functions in schizophrenia. Thus, our results indicate that the mice heterozygous for GAD67 deficiency primarily in PV neurons share several neurochemical and behavioral abnormalities with schizophrenia, offering a novel tool for addressing the underlying pathophysiology of schizophrenia. PMID:25904362

  9. Glutamate Decarboxylase 67 Deficiency in a Subset of GABAergic Neurons Induces Schizophrenia-Related Phenotypes.

    PubMed

    Fujihara, Kazuyuki; Miwa, Hideki; Kakizaki, Toshikazu; Kaneko, Ryosuke; Mikuni, Masahiko; Tanahira, Chiyoko; Tamamaki, Nobuaki; Yanagawa, Yuchio

    2015-09-01

    Decreased expression of the GABA synthetic enzyme glutamate decarboxylase 67 (GAD67) in a subset of GABAergic neurons, including parvalbumin (PV)-expressing neurons, has been observed in postmortem brain studies of schizophrenics and in animal models of schizophrenia. However, it is unclear whether and how the perturbations of GAD67-mediated GABA synthesis and signaling contribute to the pathogenesis of schizophrenia. To address this issue, we generated the mice lacking GAD67 primarily in PV neurons and characterized them with focus on schizophrenia-related parameters. We found that heterozygous mutant mice exhibited schizophrenia-related behavioral abnormalities such as deficits in prepulse inhibition, MK-801 sensitivity, and social memory. Furthermore, we observed reduced inhibitory synaptic transmission, altered properties of NMDA receptor-mediated synaptic responses in pyramidal neurons, and increased spine density in hippocampal CA1 apical dendrites, suggesting a possible link between GAD67 deficiency and disturbed glutamatergic excitatory synaptic functions in schizophrenia. Thus, our results indicate that the mice heterozygous for GAD67 deficiency primarily in PV neurons share several neurochemical and behavioral abnormalities with schizophrenia, offering a novel tool for addressing the underlying pathophysiology of schizophrenia. PMID:25904362

  10. Chronic LPS exposure produces changes in intrinsic membrane properties and a sustained IL-beta-dependent increase in GABAergic inhibition in hippocampal CA1 pyramidal neurons.

    PubMed

    Hellstrom, Ian C; Danik, Marc; Luheshi, Giamal N; Williams, Sylvain

    2005-01-01

    Chronic inflammation has been reported to be a significant factor in the induction and progression of a number of chronic neurological disorders including Alzheimer's disease and Down syndrome. It is believed that inflammation may promote synaptic dysfunction, an effect that is mediated in part by pro-inflammatory cytokines such as interleukin-1beta (IL-1beta). However, the role of IL-1beta and other cytokines in synaptic transmission is still poorly understood. In this study, we have investigated how synaptic transmission and neuronal excitability in hippocampal pyramidal neurons are affected by chronic inflammation induced by exposing organotypic slices to the bacterial cell-wall product lipopolysaccharide (LPS). We report that CA1 pyramidal neurons recorded in whole cell from slices previously exposed to LPS for 7 days had resting membrane potential and action potential properties similar to those of the controls. However, they had significantly lower membrane resistance and a more elevated action potential threshold, and displayed a slower frequency of action potential discharge. Moreover, the amplitude of pharmacologically isolated postsynaptic gamma-aminobutyric acid (GABA)ergic potentials, but not excitatory glutamatergic postsynaptic potentials, was significantly larger following chronic LPS exposure. Interestingly, co-incubation of the IL-1 receptor antagonist (IL-1Ra) concurrently with LPS prevented the increase in GABAergic transmission, but not the reduction in intrinsic neuronal excitability. Finally, we confirmed that LPS dramatically increased IL-1beta, and IL-1beta-dependent IL-6 levels in the culture medium for 2 days before returning to baseline. We conclude that CA1 pyramidal neurons in slices chronically exposed to LPS show a persistent decrease in excitability due to a combined decrease in intrinsic membrane excitability and an enhancement in synaptic GABAergic input, the latter being dependent on IL-1beta. Therefore, chronic inflammation in

  11. Area-specific analysis of the distribution of hypothalamic neurons projecting to the rat ventral tegmental area, with special reference to the GABAergic and glutamatergic efferents

    PubMed Central

    Kalló, Imre; Molnár, Csilla S.; Szöke, Sarolta; Fekete, Csaba; Hrabovszky, Erik; Liposits, Zsolt

    2015-01-01

    The ventral tegmental area (VTA) is a main regulator of reward and integrates a wide scale of hormonal and neuronal information. Feeding-, energy expenditure-, stress, adaptation- and reproduction-related hypothalamic signals are processed in the VTA and influence the reward processes. However, the neuroanatomical origin and chemical phenotype of neurons mediating these signals to the VTA have not been fully characterized. In this study we have systematically mapped hypothalamic neurons that project to the VTA using the retrograde tracer Choleratoxin B subunit (CTB) and analyzed their putative gamma-aminobutyric acid (GABA) and/or glutamate character with in situ hybridization in male rats. 23.93 ± 3.91% of hypothalamic neurons projecting to the VTA was found in preoptic and 76.27 ± 4.88% in anterior, tuberal and mammillary hypothalamic regions. Nearly half of the retrogradely-labeled neurons in the preoptic, and more than one third in the anterior, tuberal and mammillary hypothalamus appeared in medially located regions. The analyses of vesicular glutamate transporter 2 (VGLUT2) and glutamate decarboxylase 65 (GAD65) mRNA expression revealed both amino acid markers in different subsets of retrogradely-labeled hypothalamic neurons, typically with the predominance of the glutamatergic marker VGLUT2. About one tenth of CTB-IR neurons were GAD65-positive even in hypothalamic nuclei expressing primarily VGLUT2. Some regions were populated mostly by GAD65 mRNA-containing retrogradely-labeled neurons. These included the perifornical part of the lateral hypothalamus where 58.63 ± 19.04% of CTB-IR neurons were GABAergic. These results indicate that both the medial and lateral nuclear compartments of the hypothalamus provide substantial input to the VTA. Furthermore, colocalization studies revealed that these projections not only use glutamate but also GABA for neurotransmission. These GABAergic afferents may underlie important inhibitory mechanism to fine-tune the

  12. Specification of spatial identities of cerebellar neuron progenitors by ptf1a and atoh1 for proper production of GABAergic and glutamatergic neurons.

    PubMed

    Yamada, Mayumi; Seto, Yusuke; Taya, Shinichiro; Owa, Tomoo; Inoue, Yukiko U; Inoue, Takayoshi; Kawaguchi, Yoshiya; Nabeshima, Yo-Ichi; Hoshino, Mikio

    2014-04-01

    In the cerebellum, the bHLH transcription factors Ptf1a and Atoh1 are expressed in distinct neuroepithelial regions, the ventricular zone (VZ) and the rhombic lip (RL), and are required for producing GABAergic and glutamatergic neurons, respectively. However, it is unclear whether Ptf1a or Atoh1 is sufficient for specifying GABAergic or glutamatergic neuronal fates. To test this, we generated two novel knock-in mouse lines, Ptf1a(Atoh1) and Atoh1(Ptf1a), that are designed to express Atoh1 and Ptf1a ectopically in the VZ and RL, respectively. In Ptf1a(Atoh1) embryos, ectopically Atoh1-expressing VZ cells produced glutamatergic neurons, including granule cells and deep cerebellar nuclei neurons. Correspondingly, in Atoh1(Ptf1a) animals, ectopically Ptf1a-expressing RL cells produced GABAergic populations, such as Purkinje cells and GABAergic interneurons. Consistent results were also obtained from in utero electroporation of Ptf1a or Atoh1 into embryonic cerebella, suggesting that Ptf1a and Atoh1 are essential and sufficient for GABAergic versus glutamatergic specification in the neuroepithelium. Furthermore, birthdating analyses with BrdU in the knock-in mice or with electroporation studies showed that ectopically produced fate-changed neuronal types were generated at temporal schedules closely simulating those of the wild-type RL and VZ, suggesting that the VZ and RL share common temporal information. Observations of knock-in brains as well as electroporated brains revealed that Ptf1a and Atoh1 mutually negatively regulate their expression, probably contributing to formation of non-overlapping neuroepithelial domains. These findings suggest that Ptf1a and Atoh1 specify spatial identities of cerebellar neuron progenitors in the neuroepithelium, leading to appropriate production of GABAergic and glutamatergic neurons, respectively.

  13. The lateral hypothalamic area controls paradoxical (REM) sleep by means of descending projections to brainstem GABAergic neurons.

    PubMed

    Clément, Olivier; Sapin, Emilie; Libourel, Paul-Antoine; Arthaud, Sébastien; Brischoux, Frédéric; Fort, Patrice; Luppi, Pierre-Hervé

    2012-11-21

    It has recently been shown that the ventrolateral part of the periaqueductal gray (VLPAG) and the adjacent dorsal deep mesencephalic nucleus (dDpMe) contain GABAergic neurons gating paradoxical sleep (PS) onset by means of their projection to the glutamatergic PS-on neurons of the sublaterodorsal tegmental nucleus (SLD). To determine the mechanisms responsible for the cessation of activity of these GABAergic PS-off neurons at the onset and during PS, we combined the immunostaining of c-FOS, a marker of neuronal activation, with cholera toxin b subunit (CTb) retrograde tracing from the VLPAG/dDpMe in three groups of rats (control, PS deprived, and PS hypersomniac). We found that the lateral hypothalamic area (LH) is the only brain structure containing a very large number of neurons activated during PS hypersomnia and projecting to the VLPAG/dDpMe. We further demonstrated that 44% of these neurons express the neuropeptide melanin concentrating hormone (MCH). We then showed that bilateral injections in the LH of two inhibitory compounds, clonidine (an α-2 adrenergic agonist) and muscimol (a GABAa agonist) induce an inhibition of PS. Furthermore, after muscimol injections in the LH, the VLPAG/dDpMe contained a large number of activated neurons, mostly GABAergic, and projecting to the SLD. Altogether, our results indicate for the first time that the activation of a population of LH neurons, in part MCH containing, is necessary for PS to occur. Furthermore, our results strongly suggest that these neurons trigger PS by means of their inhibitory projection to the PS-off GABAergic neurons located in the VLPAG/dDpMe.

  14. Block and allosteric modulation of GABAergic currents by oenanthotoxin in rat cultured hippocampal neurons

    PubMed Central

    Wyrembek, Paulina; Lebida, Katarzyna; Mercik, Katarzyna; Szczuraszek, Katarzyna; Szczot, Marcin; Pollastro, Federica; Appendino, Giovanni; Mozrzymas, Jerzy W

    2010-01-01

    Background and purpose: Oenanthotoxin (OETX), a polyacetylenic alcohol from plants of the genus Oenanthe, has recently been identified as potent inhibitor of GABA-evoked currents. However, the effects of OETX on the inhibitory postsynaptic currents (IPSCs), as well as the pharmacological mechanism(s) underlying its effects on GABAA receptors, remain unknown. The purpose of this study was to elucidate the mechanism underlying the inhibition of GABAergic currents by OETX. Experimental approach: Effects of OETX on GABAergic currents were studied using the patch clamp technique on rat cultured hippocampal neurons. Miniature IPSCs (mIPSCs) were recorded in the whole-cell configuration, while the current responses were elicited by ultrafast GABA applications onto the excised patches. Key results: OETX potently inhibited both mIPSCs and current responses, but its effect was much stronger on synaptic currents. Analysis of the effects of OETX on mIPSCs and evoked currents disclosed a complex mechanism: allosteric modulation of both GABAA receptor binding and gating properties and a non-competitive, probably open channel block mechanism. In particular, OETX reduced the binding rate and nearly abolished receptor desensitization. A combination of rapid clearance of synaptic GABA and OETX-induced slowing of binding kinetics is proposed to underlie the potent action of OETX on mIPSCs. Conclusions and implications: OETX shows a complex blocking mechanism of GABAA receptors, and the impact of this toxin is more potent on mIPSCs than on currents evoked by exogenous GABA. Such effects on GABAergic currents are compatible with the convulsions and epileptic-like activity reported for OETX. PMID:20590622

  15. GABAergic neurons of the medial septum play a nodal role in facilitation of nociception-induced affect.

    PubMed

    Ang, Seok Ting; Lee, Andy Thiam Huat; Foo, Fang Chee; Ng, Lynn; Low, Chian-Ming; Khanna, Sanjay

    2015-01-01

    The present study explored the functional details of the influence of medial septal region (MSDB) on spectrum of nociceptive behaviours by manipulating intraseptal GABAergic mechanisms. Results showed that formalin-induced acute nociception was not affected by intraseptal microinjection of bicuculline, a GABAA receptor antagonist, or on selective lesion of septal GABAergic neurons. Indeed, the acute nociceptive responses were dissociated from the regulation of sensorimotor behaviour and generation of theta-rhythm by the GABAergic mechanisms in MSDB. The GABAergic lesion attenuated formalin-induced unconditioned cellular response in the anterior cingulate cortex (ACC) and blocked formalin-induced conditioned place avoidance (F-CPA), and as well as the contextual fear induced on conditioning with brief footshock. The effects of lesion on nociceptive-conditioned cellular responses were, however, variable. Interestingly, the lesion attenuated the conditioned representation of experimental context in dorsal hippocampus field CA1 in the F-CPA task. Collectively, the preceding suggests that the MSDB is a nodal centre wherein the GABAergic neurons mediate nociceptive affect-motivation by regulating cellular mechanisms in ACC that confer an aversive value to the noxious stimulus. Further, in conjunction with a modulatory influence on hippocampal contextual processing, MSDB may integrate affect with context as part of associative learning in the F-CPA task. PMID:26487082

  16. GABAergic neurons of the medial septum play a nodal role in facilitation of nociception-induced affect

    PubMed Central

    Ang, Seok Ting; Lee, Andy Thiam Huat; Foo, Fang Chee; Ng, Lynn; Low, Chian-Ming; Khanna, Sanjay

    2015-01-01

    The present study explored the functional details of the influence of medial septal region (MSDB) on spectrum of nociceptive behaviours by manipulating intraseptal GABAergic mechanisms. Results showed that formalin-induced acute nociception was not affected by intraseptal microinjection of bicuculline, a GABAA receptor antagonist, or on selective lesion of septal GABAergic neurons. Indeed, the acute nociceptive responses were dissociated from the regulation of sensorimotor behaviour and generation of theta-rhythm by the GABAergic mechanisms in MSDB. The GABAergic lesion attenuated formalin-induced unconditioned cellular response in the anterior cingulate cortex (ACC) and blocked formalin-induced conditioned place avoidance (F-CPA), and as well as the contextual fear induced on conditioning with brief footshock. The effects of lesion on nociceptive-conditioned cellular responses were, however, variable. Interestingly, the lesion attenuated the conditioned representation of experimental context in dorsal hippocampus field CA1 in the F-CPA task. Collectively, the preceding suggests that the MSDB is a nodal centre wherein the GABAergic neurons mediate nociceptive affect-motivation by regulating cellular mechanisms in ACC that confer an aversive value to the noxious stimulus. Further, in conjunction with a modulatory influence on hippocampal contextual processing, MSDB may integrate affect with context as part of associative learning in the F-CPA task. PMID:26487082

  17. In vivo clonal overexpression of neuroligin 3 and neuroligin 2 in neurons of the rat cerebral cortex. Differential effects on GABAergic synapses and neuronal migration

    PubMed Central

    Fekete, Christopher D.; Chiou, Tzu-Ting; Miralles, Celia P.; Harris, Rachel S.; Fiondella, Christopher G.; LoTurco, Joseph J.; De Blas, Angel L.

    2015-01-01

    We have studied the effect of clonal overexpression of neuroligin 3 (NL3) or neuroligin 2 (NL2) in the adult rat cerebral cortex following in utero electroporation (IUEP) at embryonic stage E14. Overexpression of NL3 leads to a large increase in vGAT and GAD65 in the GABAergic contacts that the overexpressing neurons receive. Overexpression of NL2 produced a similar effect but to a lesser extent. In contrast, overexpression of NL3 or NL2 after IUEP, does not affect vGlut1 in the glutamatergic contacts that the NL3 or NL2 overexpressing neurons receive. The NL3 or NL2 overexpressing neurons do not show increased innervation by parvalbumin-containing GABAergic terminals or increased parvalbumin in the same terminals that show increased vGAT. These results indicate that the observed increase in vGAT and GAD65 is not due to increased GABAergic innervation but to increased expression of vGAT and GAD65 in the GABAergic contacts that NL3 or NL2 overexpressing neurons receive. The majority of bright vGAT puncta contacting the NL3 overexpressing neurons have no gephyrin juxtaposed to them indicating that many of these contacts are non-synaptic. This contrasts with the majority of the NL2 overexpressing neurons, which show plenty of synaptic gephyrin clusters juxtaposed to vGAT. Besides having an effect on GABAergic contacts, overexpression of NL3 interferes with the neuronal radial migration, in the cerebral cortex, of the neurons overexpressing NL3. PMID:25565602

  18. GABAergic neurons of the cat dorsal raphe nucleus express c-fos during carbachol-induced active sleep.

    PubMed

    Torterolo, P; Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    2000-11-24

    Serotonergic neurons of the dorsal raphe nucleus (DRN) cease firing during active sleep (AS, also called rapid-eye-movement sleep). This cessation of electrical activity is believed to play a 'permissive' role in the generation of AS. In the present study we explored the possibility that GABAergic cells in the DRN are involved in the suppression of serotonergic activity during AS. Accordingly, we examined whether immunocytochemically identified GABAergic neurons in the DRN were activated, as indicated by their expression of c-fos, during carbachol-induced AS (AS-carbachol). Three chronically-prepared cats were euthanized after prolonged episodes of AS that was induced by microinjections of carbachol into the nucleus pontis oralis. Another four cats (controls) were maintained 2 h in quiet wakefulness before being euthanized. Thereafter, immunocytochemical studies were performed on brainstem sections utilizing antibodies against Fos, GABA and serotonin. When compared with identically prepared tissue from awake cats, the number of Fos+ neurons was larger in the DRN during AS-carbachol (35.9+/-5.6 vs. 13.9+/-4.4, P<0.05). Furthermore, a larger number of GABA+ Fos+ neurons were observed during AS-carbachol than during wakefulness (24.8+/-3.3 vs. 4.0+/-1.0, P<0.001). These GABA+ Fos+ neurons were distributed asymmetrically with a larger number located ipsilaterally to the site of injection. There was no significant difference between control and experimental animals in the number of non-GABAergic neurons that expressed c-fos in the DRN. We therefore suggest that activated GABAergic neurons of the DRN are responsible for the inhibition of serotonergic neurons that occurs during natural AS. PMID:11082488

  19. Interactions between ethanol and the endocannabinoid system at GABAergic synapses on basolateral amygdala principal neurons.

    PubMed

    Talani, Giuseppe; Lovinger, David M

    2015-12-01

    The basolateral amygdala (BLA) plays crucial roles in stimulus value coding, as well as drug and alcohol dependence. Ethanol alters synaptic transmission in the BLA, while endocannabinoids (eCBs) produce presynaptic depression at BLA synapses. Recent studies suggest interactions between ethanol and eCBs that have important consequences for alcohol drinking behavior. To determine how ethanol and eCBs interact in the BLA, we examined the physiology and pharmacology of GABAergic synapses onto BLA pyramidal neurons in neurons from young rats. Application of ethanol at concentrations relevant to intoxication increased, in both young and adult animals, the frequency of spontaneous and miniature GABAergic inhibitory postsynaptic currents, indicating a presynaptic site of ethanol action. Ethanol did not potentiate sIPSCs during inhibition of adenylyl cyclase while still exerting its effect during inhibition of protein kinase A. Activation of type 1 cannabinoid receptors (CB1) in the BLA inhibited GABAergic transmission via an apparent presynaptic mechanism, and prevented ethanol potentiation. Surprisingly, ethanol potentiation was also prevented by CB1 antagonists/inverse agonists. Brief depolarization of BLA pyramidal neurons suppressed GABAergic transmission (depolarization-induced suppression of inhibition [DSI]), an effect previously shown to be mediated by postsynaptic eCB release and presynaptic CB1 activation. A CB1-mediated suppression of GABAergic transmission was also produced by combined afferent stimulation at 0.1 Hz (LFS), and postsynaptic loading with the eCB arachidonoyl ethanolamide (AEA). Both DSI and LFS-induced synaptic depression were prevented by ethanol. Our findings indicate antagonistic interactions between ethanol and eCB/CB1 modulation at GABAergic BLA synapses that may contribute to eCB roles in ethanol seeking and drinking.

  20. Distribution of glutamatergic, GABAergic, and glycinergic neurons in the auditory pathways of macaque monkeys.

    PubMed

    Ito, T; Inoue, K; Takada, M

    2015-12-01

    Macaque monkeys use complex communication calls and are regarded as a model for studying the coding and decoding of complex sound in the auditory system. However, little is known about the distribution of excitatory and inhibitory neurons in the auditory system of macaque monkeys. In this study, we examined the overall distribution of cell bodies that expressed mRNAs for VGLUT1, and VGLUT2 (markers for glutamatergic neurons), GAD67 (a marker for GABAergic neurons), and GLYT2 (a marker for glycinergic neurons) in the auditory system of the Japanese macaque. In addition, we performed immunohistochemistry for VGLUT1, VGLUT2, and GAD67 in order to compare the distribution of proteins and mRNAs. We found that most of the excitatory neurons in the auditory brainstem expressed VGLUT2. In contrast, the expression of VGLUT1 mRNA was restricted to the auditory cortex (AC), periolivary nuclei, and cochlear nuclei (CN). The co-expression of GAD67 and GLYT2 mRNAs was common in the ventral nucleus of the lateral lemniscus (VNLL), CN, and superior olivary complex except for the medial nucleus of the trapezoid body, which expressed GLYT2 alone. In contrast, the dorsal nucleus of the lateral lemniscus, inferior colliculus, thalamus, and AC expressed GAD67 alone. The absence of co-expression of VGLUT1 and VGLUT2 in the medial geniculate, medial superior olive, and VNLL suggests that synaptic responses in the target neurons of these nuclei may be different between rodents and macaque monkeys.

  1. Diversity among principal and GABAergic neurons of the anterior olfactory nucleus

    PubMed Central

    Kay, Rachel B.; Brunjes, Peter C.

    2014-01-01

    Understanding the cellular components of neural circuits is an essential step in discerning regional function. The anterior olfactory nucleus (AON) is reciprocally connected to both the ipsi- and contralateral olfactory bulb (OB) and piriform cortex (PC), and, as a result, can broadly influence the central processing of odor information. While both the AON and PC are simple cortical structures, the regions differ in many ways including their general organization, internal wiring and synaptic connections with other brain areas. The present work used targeted whole-cell patch clamping to investigate the morphological and electrophysiological properties of the AON's two main neuronal populations: excitatory projection neurons and inhibitory interneurons. Retrograde fluorescent tracers placed into either the OB or PC identified projection neurons. Two classes were observed with different physiological signatures and locations (superficial and deep pyramidal neurons), suggesting the AON contains independent efferent channels. Transgenic mice in which GABA-containing cells expressed green fluorescent protein were used to assess inhibitory neurons. These cells were further identified as containing one or more of seven molecular markers including three calcium-binding proteins (calbindin, calretinin, parvalbumin) or four neuropeptides (somatostatin, vasoactive intestinal peptide, neuropeptide Y, cholecystokinin). The proportion of GABAergic cells containing these markers varied across subregions reinforcing notions that the AON has local functional subunits. At least five classes of inhibitory cells were observed: fast-spiking multipolar, regular-spiking multipolar, superficial neurogliaform, deep neurogliaform, and horizontal neurons. While some of these cell types are similar to those reported in the PC and other cortical regions, the AON also has unique populations. These studies provide the first examination of the cellular components of this simple cortical system

  2. During postnatal development endogenous neurosteroids influence GABA-ergic neurotransmission of mouse cortical neurons

    PubMed Central

    Brown, Adam R.; Mitchell, Scott J.; Peden, Dianne R.; Herd, Murray B.; Seifi, Mohsen; Swinny, Jerome D.; Belelli, Delia; Lambert, Jeremy J.

    2016-01-01

    As neuronal development progresses, GABAergic synaptic transmission undergoes a defined program of reconfiguration. For example, GABAA receptor (GABAAR)-mediated synaptic currents, (miniature inhibitory postsynaptic currents; mIPSCs), which initially exhibit a relatively slow decay phase, become progressively reduced in duration, thereby supporting the temporal resolution required for mature network activity. Here we report that during postnatal development of cortical layer 2/3 pyramidal neurons, GABAAR-mediated phasic inhibition is influenced by a resident neurosteroid tone, which wanes in the second postnatal week, resulting in the brief phasic events characteristic of mature neuronal signalling. Treatment of cortical slices with the immediate precursor of 5α-pregnan-3α-ol-20-one (5α3α), the GABAAR-inactive 5α-dihydroprogesterone, (5α-DHP), greatly prolonged the mIPSCs of P20 pyramidal neurons, demonstrating these more mature neurons retain the capacity to synthesize GABAAR-active neurosteroids, but now lack the endogenous steroid substrate. Previously, such developmental plasticity of phasic inhibition was ascribed to the expression of synaptic GABAARs incorporating the α1 subunit. However, the duration of mIPSCs recorded from L2/3 cortical neurons derived from α1 subunit deleted mice, were similarly under the developmental influence of a neurosteroid tone. In addition to principal cells, synaptic GABAARs of L2/3 interneurons were modulated by native neurosteroids in a development-dependent manner. In summary, local neurosteroids influence synaptic transmission during a crucial period of cortical neurodevelopment, findings which may be of importance for establishing normal network connectivity. PMID:26626485

  3. Diversity among principal and GABAergic neurons of the anterior olfactory nucleus.

    PubMed

    Kay, Rachel B; Brunjes, Peter C

    2014-01-01

    Understanding the cellular components of neural circuits is an essential step in discerning regional function. The anterior olfactory nucleus (AON) is reciprocally connected to both the ipsi- and contralateral olfactory bulb (OB) and piriform cortex (PC), and, as a result, can broadly influence the central processing of odor information. While both the AON and PC are simple cortical structures, the regions differ in many ways including their general organization, internal wiring and synaptic connections with other brain areas. The present work used targeted whole-cell patch clamping to investigate the morphological and electrophysiological properties of the AON's two main neuronal populations: excitatory projection neurons and inhibitory interneurons. Retrograde fluorescent tracers placed into either the OB or PC identified projection neurons. Two classes were observed with different physiological signatures and locations (superficial and deep pyramidal neurons), suggesting the AON contains independent efferent channels. Transgenic mice in which GABA-containing cells expressed green fluorescent protein were used to assess inhibitory neurons. These cells were further identified as containing one or more of seven molecular markers including three calcium-binding proteins (calbindin, calretinin, parvalbumin) or four neuropeptides (somatostatin, vasoactive intestinal peptide, neuropeptide Y, cholecystokinin). The proportion of GABAergic cells containing these markers varied across subregions reinforcing notions that the AON has local functional subunits. At least five classes of inhibitory cells were observed: fast-spiking multipolar, regular-spiking multipolar, superficial neurogliaform, deep neurogliaform, and horizontal neurons. While some of these cell types are similar to those reported in the PC and other cortical regions, the AON also has unique populations. These studies provide the first examination of the cellular components of this simple cortical system.

  4. An epilepsy-related ARX polyalanine expansion modifies glutamatergic neurons excitability and morphology without affecting GABAergic neurons development.

    PubMed

    Beguin, Shirley; Crépel, Valérie; Aniksztejn, Laurent; Becq, Hélène; Pelosi, Barbara; Pallesi-Pocachard, Emilie; Bouamrane, Lamine; Pasqualetti, Massimo; Kitamura, Kunio; Cardoso, Carlos; Represa, Alfonso

    2013-06-01

    Epileptic encephalopathies comprise a heterogeneous group of severe infantile disorders for which the pathophysiological basis of epilepsy is inaccurately clarified by genotype-phenotype analysis. Because a deficit of GABA neurons has been found in some of these syndromes, notably in patients with X-linked lissencephaly with abnormal genitalia, epilepsy was suggested to result from an imbalance in GABAergic inhibition, and the notion of "interneuronopathy" was proposed. Here, we studied the impact of a polyalanine expansion of aristaless-related homeobox (ARX) gene, a mutation notably found in West and Ohtahara syndromes. Analysis of Arx((GCG)7/Y) knock-in mice revealed that GABA neuron development is not affected. Moreover, pyramidal cell migration and cortical layering are unaltered in these mice. Interestingly, electrophysiological recordings show that hippocampal pyramidal neurons displayed a frequency of inhibitory postsynaptic currents similar to wild-type (WT) mice. However, these neurons show a dramatic increase in the frequency of excitatory inputs associated with a remodeling of their axonal arborization, suggesting that epilepsy in Arx((GCG)7/Y)mice would result from a glutamate network remodeling. We therefore propose that secondary alterations are instrumental for the development of disease-specific phenotypes and should be considered to explain the phenotypic diversity associated with epileptogenic mutations. PMID:22628459

  5. The Cholinergic Agonist Carbachol Increases the Frequency of Spontaneous GABAergic Synaptic Currents in Dorsal Raphe Serotonergic Neurons in the Mouse

    PubMed Central

    Yang, Chun; Brown, Ritchie E.

    2013-01-01

    Dorsal raphe nucleus (DRN) serotonin (5-HT) neurons play an important role in feeding, mood control and stress responses. One important feature of their activity across the sleep-wake cycle is their reduced firing during rapid-eye-movement (REM) sleep which stands in stark contrast to the wake/REM-on discharge pattern of brainstem cholinergic neurons. A prominent model of REM sleep control posits a reciprocal interaction between these cell groups. 5-HT inhibits cholinergic neurons, and activation of nicotinic receptors can excite DRN 5-HT neurons but the cholinergic effect on inhibitory inputs is incompletely understood. Here, in vitro, in DRN brain slices prepared from GAD67-GFP knock-in mice, a brief (3 min) bath application of carbachol (50 μM) increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in GFP-negative, putative serotonin neurons but did not affect miniature (tetrodotoxin-insensitive) IPSCs. Carbachol had no direct postsynaptic effect. Thus, carbachol likely increases the activity of local GABAergic neurons which synapse on 5-HT neurons. Removal of dorsal regions of the slice including the ventrolateral periaqueductal gray (vlPAG) region where GABAergic neurons projecting to the DRN have been identified, abolished the effect of carbachol on sIPSCs whereas removal of ventral regions containing the oral region of the pontine reticular nucleus (PnO) did not. In addition, carbachol directly excited GFP-positive, GABAergic vlPAG neurons. Antagonism of both muscarinic and nicotinic receptors completely abolished the effects of carbachol. We suggest cholinergic neurons inhibit DRN 5-HT neurons when acetylcholine levels are lower i.e. during quiet wakefulness and the beginning of REM sleep periods, in part via excitation of muscarinic and nicotinic receptors located on local vlPAG and DRN GABAergic neurons. Higher firing rates or burst firing of cholinergic neurons associated with attentive wakefulness or phasic REM sleep periods

  6. The cholinergic agonist carbachol increases the frequency of spontaneous GABAergic synaptic currents in dorsal raphe serotonergic neurons in the mouse.

    PubMed

    Yang, C; Brown, R E

    2014-01-31

    Dorsal raphe nucleus (DRN) serotonin (5-HT) neurons play an important role in feeding, mood control and stress responses. One important feature of their activity across the sleep-wake cycle is their reduced firing during rapid-eye-movement (REM) sleep which stands in stark contrast to the wake/REM-on discharge pattern of brainstem cholinergic neurons. A prominent model of REM sleep control posits a reciprocal interaction between these cell groups. 5-HT inhibits cholinergic neurons, and activation of nicotinic receptors can excite DRN 5-HT neurons but the cholinergic effect on inhibitory inputs is incompletely understood. Here, in vitro, in DRN brain slices prepared from GAD67-GFP knock-in mice, a brief (3 min) bath application of carbachol (50 μM) increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in GFP-negative, putative 5-HT neurons but did not affect miniature (tetrodotoxin-insensitive) IPSCs. Carbachol had no direct postsynaptic effect. Thus, carbachol likely increases the activity of local GABAergic neurons which synapse on 5-HT neurons. Removal of dorsal regions of the slice including the ventrolateral periaqueductal gray (vlPAG) region where GABAergic neurons projecting to the DRN have been identified, abolished the effect of carbachol on sIPSCs whereas the removal of ventral regions containing the oral region of the pontine reticular nucleus (PnO) did not. In addition, carbachol directly excited GFP-positive, GABAergic vlPAG neurons. Antagonism of both muscarinic and nicotinic receptors completely abolished the effects of carbachol. We suggest cholinergic neurons inhibit DRN 5-HT neurons when acetylcholine levels are lower i.e. during quiet wakefulness and the beginning of REM sleep periods, in part via excitation of muscarinic and nicotinic receptors located on local vlPAG and DRN GABAergic neurons. Higher firing rates or burst firing of cholinergic neurons associated with attentive wakefulness or phasic REM sleep periods

  7. A very large number of GABAergic neurons are activated in the tuberal hypothalamus during paradoxical (REM) sleep hypersomnia.

    PubMed

    Sapin, Emilie; Bérod, Anne; Léger, Lucienne; Herman, Paul A; Luppi, Pierre-Hervé; Peyron, Christelle

    2010-07-26

    We recently discovered, using Fos immunostaining, that the tuberal and mammillary hypothalamus contain a massive population of neurons specifically activated during paradoxical sleep (PS) hypersomnia. We further showed that some of the activated neurons of the tuberal hypothalamus express the melanin concentrating hormone (MCH) neuropeptide and that icv injection of MCH induces a strong increase in PS quantity. However, the chemical nature of the majority of the neurons activated during PS had not been characterized. To determine whether these neurons are GABAergic, we combined in situ hybridization of GAD(67) mRNA with immunohistochemical detection of Fos in control, PS deprived and PS hypersomniac rats. We found that 74% of the very large population of Fos-labeled neurons located in the tuberal hypothalamus after PS hypersomnia were GAD-positive. We further demonstrated combining MCH immunohistochemistry and GAD(67)in situ hybridization that 85% of the MCH neurons were also GAD-positive. Finally, based on the number of Fos-ir/GAD(+), Fos-ir/MCH(+), and GAD(+)/MCH(+) double-labeled neurons counted from three sets of double-staining, we uncovered that around 80% of the large number of the Fos-ir/GAD(+) neurons located in the tuberal hypothalamus after PS hypersomnia do not contain MCH. Based on these and previous results, we propose that the non-MCH Fos/GABAergic neuronal population could be involved in PS induction and maintenance while the Fos/MCH/GABAergic neurons could be involved in the homeostatic regulation of PS. Further investigations will be needed to corroborate this original hypothesis.

  8. Hypothalamic Non-AgRP, Non-POMC GABAergic Neurons Are Required for Postweaning Feeding and NPY Hyperphagia.

    PubMed

    Kim, Eun Ran; Wu, Zhaofei; Sun, Hao; Xu, Yuanzhong; Mangieri, Leandra R; Xu, Yong; Tong, Qingchun

    2015-07-22

    The hypothalamus is critical for feeding and body weight regulation. Prevailing studies focus on hypothalamic neurons that are defined by selectively expressing transcription factors or neuropeptides including those expressing proopiomelanocortin (POMC) and agouti-related peptides (AgRP). The Cre expression driven by the pancreas-duodenum homeobox 1 promoter is abundant in several hypothalamic nuclei but not in AgRP or POMC neurons. Using this line, we generated mice with disruption of GABA release from a major subset of non-POMC, non-AgRP GABAergic neurons in the hypothalamus. These mice exhibited a reduction in postweaning feeding and growth, and disrupted hyperphagic responses to NPY. Disruption of GABA release severely diminished GABAergic input to the paraventricular hypothalamic nucleus (PVH). Furthermore, disruption of GABA-A receptor function in the PVH also reduced postweaning feeding and blunted NPY-induced hyperphagia. Given the limited knowledge on postweaning feeding, our results are significant in identifying GABA release from a major subset of less appreciated hypothalamic neurons as a key mediator for postweaning feeding and NPY hyperphagia, and the PVH as one major downstream site that contributes significantly to the GABA action. Significance statement: Prevalent studies on feeding in the hypothalamus focus on well characterized, selective groups neurons [e.g., proopiomelanocortin (POMC) and agouti-related peptide (AgRP) neurons], and as a result, the role of the majority of other hypothalamic neurons is largely neglected. Here, we demonstrated an important role for GABAergic projections from non-POMC non-AgRP neurons to the paraventricular hypothalamic nucleus in promoting postweaning (mainly nocturnal) feeding and mediating NPY-induced hyperphagia. Thus, these results signify an importance to study those yet to be defined hypothalamic neurons in the regulation of energy balance and reveal a neural basis for postweaning (nocturnal) feeding and

  9. Enhancement of a robust arcuate GABAergic input to gonadotropin-releasing hormone neurons in a model of polycystic ovarian syndrome.

    PubMed

    Moore, Aleisha M; Prescott, Mel; Marshall, Christopher J; Yip, Siew Hoong; Campbell, Rebecca E

    2015-01-13

    Polycystic ovarian syndrome (PCOS), the leading cause of female infertility, is associated with an increase in luteinizing hormone (LH) pulse frequency, implicating abnormal steroid hormone feedback to gonadotropin-releasing hormone (GnRH) neurons. This study investigated whether modifications in the synaptically connected neuronal network of GnRH neurons could account for this pathology. The PCOS phenotype was induced in mice following prenatal androgen (PNA) exposure. Serial blood sampling confirmed that PNA elicits increased LH pulse frequency and impaired progesterone negative feedback in adult females, mimicking the neuroendocrine abnormalities of the clinical syndrome. Imaging of GnRH neurons revealed greater dendritic spine density that correlated with increased putative GABAergic but not glutamatergic inputs in PNA mice. Mapping of steroid hormone receptor expression revealed that PNA mice had 59% fewer progesterone receptor-expressing cells in the arcuate nucleus of the hypothalamus (ARN). To address whether increased GABA innervation to GnRH neurons originates in the ARN, a viral-mediated Cre-lox approach was taken to trace the projections of ARN GABA neurons in vivo. Remarkably, projections from ARN GABAergic neurons heavily contacted and even bundled with GnRH neuron dendrites, and the density of fibers apposing GnRH neurons was even greater in PNA mice (56%). Additionally, this ARN GABA population showed significantly less colocalization with progesterone receptor in PNA animals compared with controls. Together, these data describe a robust GABAergic circuit originating in the ARN that is enhanced in a model of PCOS and may underpin the neuroendocrine pathophysiology of the syndrome.

  10. Turning a Negative into a Positive: Ascending GABAergic Control of Cortical Activation and Arousal

    PubMed Central

    Brown, Ritchie E.; McKenna, James T.

    2015-01-01

    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain. Recent technological advances have illuminated the role of GABAergic neurons in control of cortical arousal and sleep. Sleep-promoting GABAergic neurons in the preoptic hypothalamus are well-known. Less well-appreciated are GABAergic projection neurons in the brainstem, midbrain, hypothalamus, and basal forebrain, which paradoxically promote arousal and fast electroencephalographic (EEG) rhythms. Thus, GABA is not purely a sleep-promoting neurotransmitter. GABAergic projection neurons in the brainstem nucleus incertus and ventral tegmental nucleus of Gudden promote theta (4–8 Hz) rhythms. Ventral tegmental area GABAergic neurons, neighboring midbrain dopamine neurons, project to the frontal cortex and nucleus accumbens. They discharge faster during cortical arousal and regulate reward. Thalamic reticular nucleus GABAergic neurons initiate sleep spindles in non-REM sleep. In addition, however, during wakefulness, they tonically regulate the activity of thalamocortical neurons. Other GABAergic inputs to the thalamus arising in the globus pallidus pars interna, substantia nigra pars reticulata, zona incerta, and basal forebrain regulate motor activity, arousal, attention, and sensory transmission. Several subpopulations of cortically projecting GABAergic neurons in the basal forebrain project to the thalamus and neocortex and preferentially promote cortical gamma-band (30–80 Hz) activity and wakefulness. Unlike sleep-active GABAergic neurons, these ascending GABAergic neurons are fast-firing neurons which disinhibit and synchronize the activity of their forebrain targets, promoting the fast EEG rhythms typical of conscious states. They are prominent targets of GABAergic hypnotic agents. Understanding the properties of ascending GABAergic neurons may lead to novel treatments for diseases involving disorders of cortical activation and wakefulness. PMID:26124745

  11. Restoration of Mecp2 expression in GABAergic neurons is sufficient to rescue multiple disease features in a mouse model of Rett syndrome.

    PubMed

    Ure, Kerstin; Lu, Hui; Wang, Wei; Ito-Ishida, Aya; Wu, Zhenyu; He, Ling-Jie; Sztainberg, Yehezkel; Chen, Wu; Tang, Jianrong; Zoghbi, Huda Y

    2016-01-01

    The postnatal neurodevelopmental disorder Rett syndrome, caused by mutations in MECP2, produces a diverse array of symptoms, including loss of language, motor, and social skills and the development of hand stereotypies, anxiety, tremor, ataxia, respiratory dysrhythmias, and seizures. Surprisingly, despite the diversity of these features, we have found that deleting Mecp2 only from GABAergic inhibitory neurons in mice replicates most of this phenotype. Here we show that genetically restoring Mecp2 expression only in GABAergic neurons of male Mecp2 null mice enhanced inhibitory signaling, extended lifespan, and rescued ataxia, apraxia, and social abnormalities but did not rescue tremor or anxiety. Female Mecp2(+/-) mice showed a less dramatic but still substantial rescue. These findings highlight the critical regulatory role of GABAergic neurons in certain behaviors and suggest that modulating the excitatory/inhibitory balance through GABAergic neurons could prove a viable therapeutic option in Rett syndrome. PMID:27328321

  12. Restoration of Mecp2 expression in GABAergic neurons is sufficient to rescue multiple disease features in a mouse model of Rett syndrome.

    PubMed

    Ure, Kerstin; Lu, Hui; Wang, Wei; Ito-Ishida, Aya; Wu, Zhenyu; He, Ling-Jie; Sztainberg, Yehezkel; Chen, Wu; Tang, Jianrong; Zoghbi, Huda Y

    2016-06-21

    The postnatal neurodevelopmental disorder Rett syndrome, caused by mutations in MECP2, produces a diverse array of symptoms, including loss of language, motor, and social skills and the development of hand stereotypies, anxiety, tremor, ataxia, respiratory dysrhythmias, and seizures. Surprisingly, despite the diversity of these features, we have found that deleting Mecp2 only from GABAergic inhibitory neurons in mice replicates most of this phenotype. Here we show that genetically restoring Mecp2 expression only in GABAergic neurons of male Mecp2 null mice enhanced inhibitory signaling, extended lifespan, and rescued ataxia, apraxia, and social abnormalities but did not rescue tremor or anxiety. Female Mecp2(+/-) mice showed a less dramatic but still substantial rescue. These findings highlight the critical regulatory role of GABAergic neurons in certain behaviors and suggest that modulating the excitatory/inhibitory balance through GABAergic neurons could prove a viable therapeutic option in Rett syndrome.

  13. Parvalbumin-Expressing GABAergic Neurons in Mouse Barrel Cortex Contribute to Gating a Goal-Directed Sensorimotor Transformation

    PubMed Central

    Sachidhanandam, Shankar; Sermet, B. Semihcan; Petersen, Carl C.H.

    2016-01-01

    Summary Sensory processing in neocortex is primarily driven by glutamatergic excitation, which is counterbalanced by GABAergic inhibition, mediated by a diversity of largely local inhibitory interneurons. Here, we trained mice to lick a reward spout in response to whisker deflection, and we recorded from genetically defined GABAergic inhibitory neurons in layer 2/3 of the primary somatosensory barrel cortex. Parvalbumin-expressing (PV), vasoactive intestinal peptide-expressing (VIP), and somatostatin-expressing (SST) neurons displayed distinct action potential firing dynamics during task performance. Whereas SST neurons fired at low rates, both PV and VIP neurons fired at high rates both spontaneously and in response to whisker stimulation. After an initial outcome-invariant early sensory response, PV neurons had lower firing rates in hit trials compared to miss trials. Optogenetic inhibition of PV neurons during this time period enhanced behavioral performance. Hence, PV neuron activity might contribute causally to gating the sensorimotor transformation of a whisker sensory stimulus into licking motor output. PMID:27149853

  14. Neuronal nitric oxide synthase-dependent S-nitrosylation of gephyrin regulates gephyrin clustering at GABAergic synapses.

    PubMed

    Dejanovic, Borislav; Schwarz, Guenter

    2014-06-01

    Gephyrin, the principal scaffolding protein at inhibitory synapses, is essential for postsynaptic clustering of glycine and GABA type A receptors (GABA(A)Rs). Gephyrin cluster formation, which determines the strength of GABAergic transmission, is modulated by interaction with signaling proteins and post-translational modifications. Here, we show that gephyrin was found to be associated with neuronal nitric oxide synthase (nNOS), the major source of the ubiquitous and important signaling molecule NO in brain. Furthermore, we identified that gephyrin is S-nitrosylated in vivo. Overexpression of nNOS decreased the size of postsynaptic gephyrin clusters in primary hippocampal neurons. Conversely, inhibition of nNOS resulted in a loss of S-nitrosylation of gephyrin and the formation of larger gephyrin clusters at synaptic sites, ultimately increasing the number of cell surface expressed synaptic GABA(A)Rs. In conclusion, S-nitrosylation of gephyrin is important for homeostatic assembly and plasticity of GABAergic synapses.

  15. Somatostatin enhances tooth-pulp-evoked cervical dorsal horn neuronal activity in the rat via inhibition of GABAergic interneurons.

    PubMed

    Takahashi, Masayuki; Takeda, Mamoru; Matsumoto, Shigeji

    2014-01-01

    A recent in vitro electrophysiological analysis combined with anatomical approach suggests that a potential disinhibitory mechanism involving somatostatin (SST), which is released by interneurons in the superficial dorsal horn, contributes to nociceptive transmission (Yasaka et al., 2010); however, whether this mechanism occurs in vivo remains to be determined. The aim of the present study was to investigate whether iontophoretic application of SST facilitates the excitability of nociceptive upper cervical spinal dorsal horn (C1) neurons through GABAergic disinhibiton, using extracellular electrophysiological recording with multibarrel electrodes and immunohistochemical techniques. Immunoreactivity of SST2A receptors was found in layer II of the C1 dorsal horn in the rat and most of these neurons co-expressed the GABA synthesizing enzyme glutamate decarboxylase 67. Single-unit recordings were made from C1 neurons responding to tooth-pulp (TP) electrical stimulation in pentobarbital anesthestized rats. Iontophoretic application of SST significantly increased TP-evoked C1 neuronal discharges in layers I and II of the spinal dorsal horn and this effect occurred in a current-dependent manner. The facilitation of this discharge by SST application was abolished with co-application of the SST2 receptor antagonist, Cyanamid 154806. Iontophoretic application of GABAA receptor antagonist, bicuculline, induced facilitation of TP-evoked C1 neuronal discharges. There was no significant difference in the relative number of spikes between SST and bicuculline applications. These results suggest that a local release of SST facilitates the excitability of trigeminal nocicepitve C1 neuronal activity via inhibition of GABAergic neurons. Therefore, SST2A receptors expressed in layer II GABAergic inhibitory interneurons play an important role in trigeminal nociceptive transmission and are a potential therapeutic target in the treatment of trigeminal pain, including hyperalgesia. PMID

  16. Inhibitory Synapse Formation in a Co-culture Model Incorporating GABAergic Medium Spiny Neurons and HEK293 Cells Stably Expressing GABAA Receptors

    PubMed Central

    Brown, Laura E.; Fuchs, Celine; Nicholson, Martin W.; Stephenson, F. Anne; Thomson, Alex M.; Jovanovic, Jasmina N.

    2014-01-01

    Inhibitory neurons act in the central nervous system to regulate the dynamics and spatio-temporal co-ordination of neuronal networks. GABA (γ-aminobutyric acid) is the predominant inhibitory neurotransmitter in the brain. It is released from the presynaptic terminals of inhibitory neurons within highly specialized intercellular junctions known as synapses, where it binds to GABAA receptors (GABAARs) present at the plasma membrane of the synapse-receiving, postsynaptic neurons. Activation of these GABA-gated ion channels leads to influx of chloride resulting in postsynaptic potential changes that decrease the probability that these neurons will generate action potentials. During development, diverse types of inhibitory neurons with distinct morphological, electrophysiological and neurochemical characteristics have the ability to recognize their target neurons and form synapses which incorporate specific GABAARs subtypes. This principle of selective innervation of neuronal targets raises the question as to how the appropriate synaptic partners identify each other. To elucidate the underlying molecular mechanisms, a novel in vitro co-culture model system was established, in which medium spiny GABAergic neurons, a highly homogenous population of neurons isolated from the embryonic striatum, were cultured with stably transfected HEK293 cell lines that express different GABAAR subtypes. Synapses form rapidly, efficiently and selectively in this system, and are easily accessible for quantification. Our results indicate that various GABAAR subtypes differ in their ability to promote synapse formation, suggesting that this reduced in vitro model system can be used to reproduce, at least in part, the in vivo conditions required for the recognition of the appropriate synaptic partners and formation of specific synapses. Here the protocols for culturing the medium spiny neurons and generating HEK293 cells lines expressing GABAARs are first described, followed by detailed

  17. Neuroimmune Regulation of GABAergic Neurons Within the Ventral Tegmental Area During Withdrawal from Chronic Morphine

    PubMed Central

    Taylor, Anna M W; Castonguay, Annie; Ghogha, Atefeh; Vayssiere, Pia; Pradhan, Amynah A A; Xue, Lihua; Mehrabani, Sadaf; Wu, Juli; Levitt, Pat; Olmstead, Mary C; De Koninck, Yves; Evans, Christopher J; Cahill, Catherine M

    2016-01-01

    Opioid dependence is accompanied by neuroplastic changes in reward circuitry leading to a negative affective state contributing to addictive behaviors and risk of relapse. The current study presents a neuroimmune mechanism through which chronic opioids disrupt the ventral tegmental area (VTA) dopaminergic circuitry that contributes to impaired reward behavior. Opioid dependence was induced in rodents by treatment with escalating doses of morphine. Microglial activation was observed in the VTA following spontaneous withdrawal from chronic morphine treatment. Opioid-induced microglial activation resulted in an increase in brain-derived neurotrophic factor (BDNF) expression and a reduction in the expression and function of the K+Cl− co-transporter KCC2 within VTA GABAergic neurons. Inhibition of microglial activation or interfering with BDNF signaling prevented the loss of Cl− extrusion capacity and restored the rewarding effects of cocaine in opioid-dependent animals. Consistent with a microglial-derived BDNF-induced disruption of reward, intra-VTA injection of BDNF or a KCC2 inhibitor resulted in a loss of cocaine-induced place preference in opioid-naïve animals. The loss of the extracellular Cl− gradient undermines GABAA-mediated inhibition, and represents a mechanism by which chronic opioid treatments can result in blunted reward circuitry. This study directly implicates microglial-derived BDNF as a negative regulator of reward in opioid-dependent states, identifying new therapeutic targets for opiate addictive behaviors. PMID:26202104

  18. Neuroimmune Regulation of GABAergic Neurons Within the Ventral Tegmental Area During Withdrawal from Chronic Morphine.

    PubMed

    Taylor, Anna M W; Castonguay, Annie; Ghogha, Atefeh; Vayssiere, Pia; Pradhan, Amynah A A; Xue, Lihua; Mehrabani, Sadaf; Wu, Juli; Levitt, Pat; Olmstead, Mary C; De Koninck, Yves; Evans, Christopher J; Cahill, Catherine M

    2016-03-01

    Opioid dependence is accompanied by neuroplastic changes in reward circuitry leading to a negative affective state contributing to addictive behaviors and risk of relapse. The current study presents a neuroimmune mechanism through which chronic opioids disrupt the ventral tegmental area (VTA) dopaminergic circuitry that contributes to impaired reward behavior. Opioid dependence was induced in rodents by treatment with escalating doses of morphine. Microglial activation was observed in the VTA following spontaneous withdrawal from chronic morphine treatment. Opioid-induced microglial activation resulted in an increase in brain-derived neurotrophic factor (BDNF) expression and a reduction in the expression and function of the K(+)Cl(-) co-transporter KCC2 within VTA GABAergic neurons. Inhibition of microglial activation or interfering with BDNF signaling prevented the loss of Cl(-) extrusion capacity and restored the rewarding effects of cocaine in opioid-dependent animals. Consistent with a microglial-derived BDNF-induced disruption of reward, intra-VTA injection of BDNF or a KCC2 inhibitor resulted in a loss of cocaine-induced place preference in opioid-naïve animals. The loss of the extracellular Cl(-) gradient undermines GABAA-mediated inhibition, and represents a mechanism by which chronic opioid treatments can result in blunted reward circuitry. This study directly implicates microglial-derived BDNF as a negative regulator of reward in opioid-dependent states, identifying new therapeutic targets for opiate addictive behaviors. PMID:26202104

  19. Glutamic acid decarboxylase 65: a link between GABAergic synaptic plasticity in the lateral amygdala and conditioned fear generalization.

    PubMed

    Lange, Maren D; Jüngling, Kay; Paulukat, Linda; Vieler, Marc; Gaburro, Stefano; Sosulina, Ludmila; Blaesse, Peter; Sreepathi, Hari K; Ferraguti, Francesco; Pape, Hans-Christian

    2014-08-01

    An imbalance of the gamma-aminobutyric acid (GABA) system is considered a major neurobiological pathomechanism of anxiety, and the amygdala is a key brain region involved. Reduced GABA levels have been found in anxiety patients, and genetic variations of glutamic acid decarboxylase (GAD), the rate-limiting enzyme of GABA synthesis, have been associated with anxiety phenotypes in both humans and mice. These findings prompted us to hypothesize that a deficiency of GAD65, the GAD isoform controlling the availability of GABA as a transmitter, affects synaptic transmission and plasticity in the lateral amygdala (LA), and thereby interferes with fear responsiveness. Results indicate that genetically determined GAD65 deficiency in mice is associated with (1) increased synaptic length and release at GABAergic connections, (2) impaired efficacy of GABAergic synaptic transmission and plasticity, and (3) reduced spillover of GABA to presynaptic GABAB receptors, resulting in a loss of the associative nature of long-term synaptic plasticity at cortical inputs to LA principal neurons. (4) In addition, training with high shock intensities in wild-type mice mimicked the phenotype of GAD65 deficiency at both the behavioral and synaptic level, indicated by generalization of conditioned fear and a loss of the associative nature of synaptic plasticity in the LA. In conclusion, GAD65 is required for efficient GABAergic synaptic transmission and plasticity, and for maintaining extracellular GABA at a level needed for associative plasticity at cortical inputs in the LA, which, if disturbed, results in an impairment of the cue specificity of conditioned fear responses typifying anxiety disorders.

  20. Characterization of GABAergic neurons in rapid-eye-movement sleep controlling regions of the brainstem reticular formation in GAD67-green fluorescent protein knock-in mice.

    PubMed

    Brown, Ritchie E; McKenna, James T; Winston, Stuart; Basheer, Radhika; Yanagawa, Yuchio; Thakkar, Mahesh M; McCarley, Robert W

    2008-01-01

    Recent experiments suggest that brainstem GABAergic neurons may control rapid-eye-movement (REM) sleep. However, understanding their pharmacology/physiology has been hindered by difficulty in identification. Here we report that mice expressing green fluorescent protein (GFP) under the control of the GAD67 promoter (GAD67-GFP knock-in mice) exhibit numerous GFP-positive neurons in the central gray and reticular formation, allowing on-line identification in vitro. Small (10-15 microm) or medium-sized (15-25 microm) GFP-positive perikarya surrounded larger serotonergic, noradrenergic, cholinergic and reticular neurons, and > 96% of neurons were double-labeled for GFP and GABA, confirming that GFP-positive neurons are GABAergic. Whole-cell recordings in brainstem regions important for promoting REM sleep [subcoeruleus (SubC) or pontine nucleus oralis (PnO) regions] revealed that GFP-positive neurons were spontaneously active at 3-12 Hz, fired tonically, and possessed a medium-sized depolarizing sag during hyperpolarizing steps. Many neurons also exhibited a small, low-threshold calcium spike. GFP-positive neurons were tested with pharmacological agents known to promote (carbachol) or inhibit (orexin A) REM sleep. SubC GFP-positive neurons were excited by the cholinergic agonist carbachol, whereas those in the PnO were either inhibited or excited. GFP-positive neurons in both areas were excited by orexins/hypocretins. These data are congruent with the hypothesis that carbachol-inhibited GABAergic PnO neurons project to, and inhibit, REM-on SubC reticular neurons during waking, whereas carbachol-excited SubC and PnO GABAergic neurons are involved in silencing locus coeruleus and dorsal raphe aminergic neurons during REM sleep. Orexinergic suppression of REM during waking is probably mediated in part via excitation of acetylcholine-inhibited GABAergic neurons.

  1. Medial Habenula Output Circuit Mediated by α5 Nicotinic Receptor-Expressing GABAergic Neurons in the Interpeduncular Nucleus

    PubMed Central

    Hsu, Yun-Wei A.; Tempest, Lynne; Quina, Lely A.; Wei, Aguan D.; Zeng, Hongkui

    2013-01-01

    The Chrna5 gene encodes the α5 nicotinic acetylcholine receptor subunit, an “accessory” subunit of pentameric nicotinic receptors, that has been shown to play a role in nicotine-related behaviors in rodents and is genetically linked to smoking behavior in humans. Here we have used a BAC transgenic mouse line, α5GFP, to examine the cellular phenotype, connectivity, and function of α5-expressing neurons. Although the medial habenula (MHb) has been proposed as a site of α5 function, α5GFP is not detectable in the MHb, and α5 mRNA is expressed there only at very low levels. However, α5GFP is strongly expressed in a subset of neurons in the interpeduncular nucleus (IP), median raphe/paramedian raphe (MnR/PMnR), and dorsal tegmental area (DTg). Double-label fluorescence in situ hybridization reveals that these neurons are exclusively GABAergic. Transgenic and conventional tract tracing show that α5GFP neurons in the IP project principally to the MnR/PMnR and DTg/interfascicular dorsal raphe, both areas rich in serotonergic neurons. The α5GFP neurons in the IP are located in a region that receives cholinergic fiber inputs from the ventral MHb, and optogenetically assisted circuit mapping demonstrates a monosynaptic connection between these cholinergic neurons and α5GFP IP neurons. Selective inhibitors of both α4β2- and α3β4-containing nicotinic receptors were able to reduce nicotine-evoked inward currents in α5GFP neurons in the IP, suggesting a mixed nicotinic receptor profile in these cells. Together, these findings show that the α5-GABAergic interneurons form a link from the MHb to serotonergic brain centers, which is likely to mediate some of the behavioral effects of nicotine. PMID:24227714

  2. Medial habenula output circuit mediated by α5 nicotinic receptor-expressing GABAergic neurons in the interpeduncular nucleus.

    PubMed

    Hsu, Yun-Wei A; Tempest, Lynne; Quina, Lely A; Wei, Aguan D; Zeng, Hongkui; Turner, Eric E

    2013-11-13

    The Chrna5 gene encodes the α5 nicotinic acetylcholine receptor subunit, an "accessory" subunit of pentameric nicotinic receptors, that has been shown to play a role in nicotine-related behaviors in rodents and is genetically linked to smoking behavior in humans. Here we have used a BAC transgenic mouse line, α5(GFP), to examine the cellular phenotype, connectivity, and function of α5-expressing neurons. Although the medial habenula (MHb) has been proposed as a site of α5 function, α5(GFP) is not detectable in the MHb, and α5 mRNA is expressed there only at very low levels. However, α5(GFP) is strongly expressed in a subset of neurons in the interpeduncular nucleus (IP), median raphe/paramedian raphe (MnR/PMnR), and dorsal tegmental area (DTg). Double-label fluorescence in situ hybridization reveals that these neurons are exclusively GABAergic. Transgenic and conventional tract tracing show that α5(GFP) neurons in the IP project principally to the MnR/PMnR and DTg/interfascicular dorsal raphe, both areas rich in serotonergic neurons. The α5(GFP) neurons in the IP are located in a region that receives cholinergic fiber inputs from the ventral MHb, and optogenetically assisted circuit mapping demonstrates a monosynaptic connection between these cholinergic neurons and α5(GFP) IP neurons. Selective inhibitors of both α4β2- and α3β4-containing nicotinic receptors were able to reduce nicotine-evoked inward currents in α5(GFP) neurons in the IP, suggesting a mixed nicotinic receptor profile in these cells. Together, these findings show that the α5-GABAergic interneurons form a link from the MHb to serotonergic brain centers, which is likely to mediate some of the behavioral effects of nicotine. PMID:24227714

  3. α-MSH exerts direct postsynaptic excitatory effects on NTS neurons and enhances GABAergic signaling in the NTS.

    PubMed

    Mimee, A; Kuksis, M; Ferguson, A V

    2014-03-14

    The central melanocortin system plays an essential role in the regulation of energy balance. While anorexigenic effects of α-melanocyte-stimulating hormone (α-MSH) acting in the nucleus of the solitary tract (NTS), a critical medullary autonomic control center, have been established, the cellular events underlying these effects are less well characterized. In this study, we used whole-cell patch-clamp electrophysiology to examine firstly whether α-MSH exerts direct postsynaptic effects on the membrane potential of rat NTS neurons in slice preparation, and secondly whether α-MSH influences GABAergic signaling in the NTS. In normal artificial cerebrospinal fluid, perfusion of α-MSH (500 nM) resulted in a depolarization in 39% of cells (n=16, mean 6.14±0.54 mV), and a hyperpolarization in 22% of cells (n=9, -6.79±1.02 mV). Studies using tetrodotoxin to block neuronal communication revealed α-MSH exerts direct depolarizing effects on some NTS neurons, and indirect inhibitory effects on others. A third subset of neurons is simultaneously directly depolarized and indirectly hyperpolarized by α-MSH, resulting in a net lack of effect on membrane potential. The inhibitory inputs influenced by α-MSH were identified as GABAergic, as α-MSH increased the frequency, but not amplitude, of inhibitory postsynaptic currents (IPSCs) in 50% of NTS neurons. α-MSH had no effect on the frequency or amplitude of miniature IPSCs. Furthermore, pharmacological blockade of GABAA and GABAB receptors, and physical removal of all synaptic inputs via cellular dissociation, abolished hyperpolarizations induced by α-MSH. We conclude α-MSH exerts direct, postsynaptic excitatory effects on a subset of NTS neurons. By exciting GABAergic NTS neurons and presynaptically enhancing GABAergic signaling, α-MSH also indirectly inhibits other NTS cells. These findings provide critical insight into the cellular events underlying medullary melanocortin anorexigenic effects, and expand the

  4. Immunohistochemical study on the distribution and origin of GABAergic nerve terminals in the superior salivatory nucleus.

    PubMed

    Matsushima, Ayumi; Ichikawa, Hiroyuki; Fujita, Masako; Mitoh, Yoshihiro; Kobashi, Motoi; Yamashiro, Takashi; Matsuo, Ryuji

    2009-01-01

    The superior salivatory nucleus (SSN) is the primary parasympathetic center controlling submandibular salivatory secretion. Our previous electrophysiological study revealed that many SSN neurons receive GABAergic and glycinergic synaptic inputs. In the present study, we examined the distribution of GABAergic and glycinergic nerve terminals, GABA(A) receptors in the SSN, and the origin of GABAergic nerve terminals innervating the SSN. Glutamic acid decarboxylase (GAD) and glycine transporter 2 (GLYT2) were used as markers of GABAergic and glycinergic nerve terminals, respectively. GAD- and GLYT2-positive nerve terminals and GABA(A) receptors were examined immunohistochemically in SSN neurons labeled by the retrograde axonal transport of FastBlue (FB) injected into the chorda-lingual nerve. The SSN neurons abundantly contained GAD-positive nerve terminals and GABA(A) receptors, suggesting that SSN neurons undergo strong GABAergic inhibition. The origin of GABAergic terminals was examined in neurons labeled by the retrograde transport of FluoroGold (FG) injected into the SSN. GAD was used as a marker of GABAergic neurons. Numerous FG-labeled neurons were found in the forebrain and brainstem. However, in FG-labeled neurons, GAD-positive neurons were occasionally observed in the reticular formation of the brainstem. These findings suggest that SSN neurons mainly receive GABAergic projections from the reticular formation.

  5. Cell type-specific, presynaptic LTP of inhibitory synapses on fast-spiking GABAergic neurons in the mouse visual cortex.

    PubMed

    Sarihi, Abdolrahman; Mirnajafi-Zadeh, Javad; Jiang, Bin; Sohya, Kazuhiro; Safari, Mir-Shahram; Arami, Masoumeh Kourosh; Yanagawa, Yuchio; Tsumoto, Tadaharu

    2012-09-19

    Properties and plasticity of inhibitory synapses on fast-spiking (FS) GABAergic (FS-GABA) interneurons in layer II/III of the mouse visual cortex were examined in cortical slices by whole-cell recordings of IPSCs or IPSPs evoked by activation of presynaptic FS or non-FS GABAergic interneurons. Unitary IPSCs (uIPSCs) evoked by action potentials of FS-GABA neurons have shorter onset latency, faster rising slope, higher peak amplitude, and faster decay time than those evoked by action potentials of non-FS-GABA neurons. Tetanic activation of presynaptic FS-GABA neurons induced long-term potentiation (LTP) of uIPSCs, whereas that of presynaptic non-FS-GABA neurons did not induce LTP, indicating that long-term plasticity of inhibitory synapses on FS-GABA neurons is pathway specific. For further analysis of inhibitory synaptic plasticity, IPSPs evoked by electrical stimulation of an adjacent site in the cortex were recorded from FS-GABA neurons. Theta burst stimulation induced LTP of IPSPs in 12 of 14 FS-GABA neurons. The paired-pulse stimulation protocol and coefficient of variation analysis indicated that this form of LTP may be presynaptic in origin. Filling postsynaptic cells with a Ca(2+) chelator did not block the induction of LTP, suggesting no involvement of postsynaptic Ca(2+) rise. Also, this form of LTP was dependent neither on metabotropic glutamate receptors nor voltage-gated Ca(2+) channels of the L and T types. Further pharmacological analysis indicated that voltage-gated Ca(2+) channels other than the P/Q type, such as N and R types, were not involved in LTP, suggesting that P/Q-type channels are a candidate for factors inducing LTP of inhibitory synapses between FS-GABA neurons. PMID:22993435

  6. Fluorescent labeling of both GABAergic and glycinergic neurons in vesicular GABA transporter (VGAT)-venus transgenic mouse.

    PubMed

    Wang, Y; Kakizaki, T; Sakagami, H; Saito, K; Ebihara, S; Kato, M; Hirabayashi, M; Saito, Y; Furuya, N; Yanagawa, Y

    2009-12-15

    Inhibitory neurons play important roles in a number of brain functions. They are composed of GABAergic neurons and glycinergic neurons, and vesicular GABA transporter (VGAT) is specifically expressed in these neurons. Since the inhibitory neurons are scattered around in the CNS, it is difficult to identify these cells in living brain preparations. The glutamate decarboxylase (GAD) 67-GFP knock-in mouse has been widely used for the identification of GABAergic neurons, but their GAD67 expression was decreased compared to the wild-type mice. To overcome such a problem and to highlight the function and morphology of inhibitory neurons, we generated four lines of VGAT-Venus transgenic mice (lines #04, #29, #39 and #49) expressing Venus fluorescent protein under the control of mouse VGAT promoter. We found higher expression level of Venus transcripts and proteins as well as brighter fluorescent signal in line #39 mouse brains, compared to brains of other lines examined. By Western blots and spectrofluorometric measurements of forebrain, the line #39 mouse showed stronger GFP immunoreactivity and brighter fluorescent intensity than the GAD67-GFP knock-in mouse. In addition, Venus was present not only in somata, but also in neurites in the line #39 mouse by histological studies. In situ hybridization analysis showed that the expression pattern of Venus in the line #39 mouse was similar to that of endogenous VGAT. Double immunostaining analysis in line #39 mouse showed that Venus-expressing cells are primarily immunoreactive for GABA in cerebral cortex, hippocampus and cerebellar cortex and for GABA or glycine in dorsal cochlear nucleus. These results demonstrate that the VGAT-Venus line #39 mouse should be useful for studies on function and morphology of inhibitory neurons in the CNS.

  7. Increased gabaergic input to ventral tegmental area dopaminergic neurons associated with decreased cocaine reinforcement in mu-opioid receptor knockout mice.

    PubMed

    Mathon, D S; Lesscher, H M B; Gerrits, M A F M; Kamal, A; Pintar, J E; Schuller, A G P; Spruijt, B M; Burbach, J P H; Smidt, M P; van Ree, J M; Ramakers, G M J

    2005-01-01

    There is general agreement that dopaminergic neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens and prefrontal cortex play a key role in drug reinforcement. The activity of these neurons is strongly modulated by the inhibitory and excitatory input they receive. Activation of mu-opioid receptors, located on GABAergic neurons in the VTA, causes hyperpolarization of these GABAergic neurons, thereby causing a disinhibition of VTA dopaminergic neurons. This effect of mu-opioid receptors upon GABA neurotransmission is a likely mechanism for mu-opioid receptor modulation of drug reinforcement. We studied mu-opioid receptor signaling in relation to cocaine reinforcement in wild-type and mu-opioid receptor knockout mice using a cocaine self-administration paradigm and in vitro electrophysiology. Cocaine self-administration was reduced in mu-opioid receptor knockout mice, suggesting a critical role of mu-opioid receptors in cocaine reinforcement. The frequency of spontaneous inhibitory post-synaptic currents onto dopaminergic neurons in the ventral tegmental area was increased in mu-opioid receptor knockout mice compared with wild-type controls, while the frequency of spontaneous excitatory post-synaptic currents was unaltered. The reduced cocaine self-administration and increased GABAergic input to VTA dopaminergic neurons in mu-opioid receptor knockout mice supports the notion that suppression of GABAergic input onto dopaminergic neurons in the VTA contributes to mu-opioid receptor modulation of cocaine reinforcement. PMID:15664692

  8. Ethanol inhibits histaminergic neurons in mouse tuberomammillary nucleus slices via potentiating GABAergic transmission onto the neurons at both pre- and postsynaptic sites

    PubMed Central

    Sun, Yu; Jiang, Shi-yu; Ni, Jian; Luo, Yan-jia; Chen, Chang-rui; Hong, Zong-yuan; Yanagawa, Yuchio; Qu, Wei-min; Wang, Lu; Huang, Zhi-li

    2016-01-01

    Aim: Ethanol, one of the most frequently used and abused substances in our society, has a profound impact on sedation. However, the neuronal mechanisms underlying its sedative effect remain unclear. In this study, we investigated the effects of ethanol on histaminergic neurons in the tuberomammillary nucleus (TMN), a brain region thought to be critical for wakefulness. Methods: Coronal brain slices (250 μm thick) containing the TMN were prepared from GAD67-GFP knock-in mice. GAD67-GFP was used to identify histaminergic neurons in the TMN. The spontaneous firing and membrane potential of histaminergic neurons, and GABAergic transmission onto these neurons were recorded using whole-cell patch-clamp recordings. Drugs were applied through superfusion. Results: Histaminergic and GAD67-expressing neurons in the TMN of GAD67-GFP mice were highly co-localized. TMN GFP-positive neurons exhibited a regular spontaneous discharge at a rate of 2–4 Hz without burst firing. Brief superfusion of ethanol (64, 190, and 560 mmol/L) dose-dependently and reversibly suppressed the spontaneous firing of the neurons in the TMN; when synaptic transmission was blocked by tetrodotoxin (1 μmol/L), ethanol caused hyperpolarization of the membrane potential. Furthermore, superfusion of ethanol markedly increased the frequency and amplitude of spontaneous and miniature inhibitory postsynaptic currents (sIPSCs and mIPSCs), which were abolished in the presence of the GABAA receptor antagonist bicuculline (20 μmol/L). Finally, ethanol-mediated enhancement of sIPSCs and mIPSCs was significantly attenuated when the slices were pretreated with the GABAB agonist baclofen (30 μmol/L). Conclusion: Ethanol inhibits the excitability of histaminergic neurons in mouse TMN slices, possibly via potentiating GABAergic transmission onto the neurons at both pre- and postsynaptic sites. PMID:27498778

  9. Discharge Profiles across the Sleep–Waking Cycle of Identified Cholinergic, GABAergic, and Glutamatergic Neurons in the Pontomesencephalic Tegmentum of the Rat

    PubMed Central

    Boucetta, Soufiane; Cissé, Youssouf; Mainville, Lynda; Morales, Marisela

    2014-01-01

    Distributed within the laterodorsal tegmental and pedunculopontine tegmental nuclei (LDT and PPT), cholinergic neurons in the pontomesencephalic tegmentum have long been thought to play a critical role in stimulating cortical activation during waking (W) and paradoxical sleep (PS, also called REM sleep), yet also in promoting PS with muscle atonia. However, the discharge profile and thus precise roles of the cholinergic neurons have remained uncertain because they lie intermingled with GABAergic and glutamatergic neurons, which might also assume these roles. By applying juxtacellular recording and labeling in naturally sleeping–waking, head-fixed rats, we investigated the discharge profiles of histochemically identified cholinergic, GABAergic, and glutamatergic neurons in the LDT, SubLDT, and adjoining medial part of the PPT (MPPT) in relation to sleep–wake states, cortical activity, and muscle tone. We found that all cholinergic neurons were maximally active during W and PS in positive correlation with fast (γ) cortical activity, as “W/PS-max active neurons.” Like cholinergic neurons, many GABAergic and glutamatergic neurons were also “W/PS-max active.” Other GABAergic and glutamatergic neurons were “PS-max active,” being minimally active during W and maximally active during PS in negative correlation with muscle tone. Conversely, some glutamatergic neurons were “W-max active,” being maximally active during W and minimally active during PS in positive correlation with muscle tone. Through different discharge profiles, the cholinergic, GABAergic, and glutamatergic neurons of the LDT, SubLDT, and MPPT thus appear to play distinct roles in promoting W and PS with cortical activation, PS with muscle atonia, or W with muscle tone. PMID:24672016

  10. Discharge profiles across the sleep-waking cycle of identified cholinergic, GABAergic, and glutamatergic neurons in the pontomesencephalic tegmentum of the rat.

    PubMed

    Boucetta, Soufiane; Cissé, Youssouf; Mainville, Lynda; Morales, Marisela; Jones, Barbara E

    2014-03-26

    Distributed within the laterodorsal tegmental and pedunculopontine tegmental nuclei (LDT and PPT), cholinergic neurons in the pontomesencephalic tegmentum have long been thought to play a critical role in stimulating cortical activation during waking (W) and paradoxical sleep (PS, also called REM sleep), yet also in promoting PS with muscle atonia. However, the discharge profile and thus precise roles of the cholinergic neurons have remained uncertain because they lie intermingled with GABAergic and glutamatergic neurons, which might also assume these roles. By applying juxtacellular recording and labeling in naturally sleeping-waking, head-fixed rats, we investigated the discharge profiles of histochemically identified cholinergic, GABAergic, and glutamatergic neurons in the LDT, SubLDT, and adjoining medial part of the PPT (MPPT) in relation to sleep-wake states, cortical activity, and muscle tone. We found that all cholinergic neurons were maximally active during W and PS in positive correlation with fast (γ) cortical activity, as "W/PS-max active neurons." Like cholinergic neurons, many GABAergic and glutamatergic neurons were also "W/PS-max active." Other GABAergic and glutamatergic neurons were "PS-max active," being minimally active during W and maximally active during PS in negative correlation with muscle tone. Conversely, some glutamatergic neurons were "W-max active," being maximally active during W and minimally active during PS in positive correlation with muscle tone. Through different discharge profiles, the cholinergic, GABAergic, and glutamatergic neurons of the LDT, SubLDT, and MPPT thus appear to play distinct roles in promoting W and PS with cortical activation, PS with muscle atonia, or W with muscle tone. PMID:24672016

  11. Discharge profiles across the sleep-waking cycle of identified cholinergic, GABAergic, and glutamatergic neurons in the pontomesencephalic tegmentum of the rat.

    PubMed

    Boucetta, Soufiane; Cissé, Youssouf; Mainville, Lynda; Morales, Marisela; Jones, Barbara E

    2014-03-26

    Distributed within the laterodorsal tegmental and pedunculopontine tegmental nuclei (LDT and PPT), cholinergic neurons in the pontomesencephalic tegmentum have long been thought to play a critical role in stimulating cortical activation during waking (W) and paradoxical sleep (PS, also called REM sleep), yet also in promoting PS with muscle atonia. However, the discharge profile and thus precise roles of the cholinergic neurons have remained uncertain because they lie intermingled with GABAergic and glutamatergic neurons, which might also assume these roles. By applying juxtacellular recording and labeling in naturally sleeping-waking, head-fixed rats, we investigated the discharge profiles of histochemically identified cholinergic, GABAergic, and glutamatergic neurons in the LDT, SubLDT, and adjoining medial part of the PPT (MPPT) in relation to sleep-wake states, cortical activity, and muscle tone. We found that all cholinergic neurons were maximally active during W and PS in positive correlation with fast (γ) cortical activity, as "W/PS-max active neurons." Like cholinergic neurons, many GABAergic and glutamatergic neurons were also "W/PS-max active." Other GABAergic and glutamatergic neurons were "PS-max active," being minimally active during W and maximally active during PS in negative correlation with muscle tone. Conversely, some glutamatergic neurons were "W-max active," being maximally active during W and minimally active during PS in positive correlation with muscle tone. Through different discharge profiles, the cholinergic, GABAergic, and glutamatergic neurons of the LDT, SubLDT, and MPPT thus appear to play distinct roles in promoting W and PS with cortical activation, PS with muscle atonia, or W with muscle tone.

  12. Laminar segregation of GABAergic neurons in the avian nucleus isthmi pars magnocellularis: a retrograde tracer and comparative study.

    PubMed

    Faunes, Macarena; Fernández, Sara; Gutiérrez-Ibáñez, Cristián; Iwaniuk, Andrew N; Wylie, Douglas R; Mpodozis, Jorge; Karten, Harvey J; Marín, Gonzalo

    2013-06-01

    The isthmic complex is part of a visual midbrain circuit thought to be involved in stimulus selection and spatial attention. In birds, this circuit is composed of the nuclei isthmi pars magnocellularis (Imc), pars parvocellularis (Ipc), and pars semilunaris (SLu), all of them reciprocally connected to the ipsilateral optic tectum (TeO). The Imc conveys heterotopic inhibition to the TeO, Ipc, and SLu via widespread γ-aminobutyric acid (GABA)ergic axons that allow global competitive interactions among simultaneous sensory inputs. Anatomical studies in the chick have described a cytoarchitectonically uniform Imc nucleus containing two intermingled cell types: one projecting to the Ipc and SLu and the other to the TeO. Here we report that in passerine species, the Imc is segregated into an internal division displaying larger, sparsely distributed cells, and an external division displaying smaller, more densely packed cells. In vivo and in vitro injections of neural tracers in the TeO and the Ipc of the zebra finch demonstrated that neurons from the external and internal subdivisions project to the Ipc and the TeO, respectively, indicating that each Imc subdivision contains one of the two cell types hodologically defined in the chick. In an extensive survey across avian orders, we found that, in addition to passerines, only species of Piciformes and Rallidae exhibited a segregated Imc, whereas all other groups exhibited a uniform Imc. These results offer a comparative basis to investigate the functional role played by each Imc neural type in the competitive interactions mediated by this nucleus.

  13. NPY+-, but not PV+-GABAergic neurons mediated long-range inhibition from infra- to prelimbic cortex

    PubMed Central

    Saffari, R; Teng, Z; Zhang, M; Kravchenko, M; Hohoff, C; Ambrée, O; Zhang, W

    2016-01-01

    Anxiety disorders are thought to reflect deficits in the regulation of fear memories. While the amygdala has long been considered a site of storage of fear memories, newer findings suggest that the prefrontal cortex (PFC) is essential in the regulation of amygdala-dependent memories and fear expression. Here, activation of the prelimbic cortex (PrL) enhances the expression of fear, while an elevated activity in the infralimbic cortex (IL) enhances fear extinction. Despite the presence of these facts, we still know very little about the synaptic interconnectivity within the PFC. The aim of the present study was to investigate the inhibitory circuits between prelimbic and IL using morphological and electrophysiological methods. Our immunohistochemical analysis revealed that the distribution of PV+- and NPY+-GABAergic neurons was strikingly different within the PFC. In addition, we provided the first experimental evidence that the pyramidal neurons in the PrL received a direct inhibitory input mediated by bipolar NPY+-GABAergic projection neurons in the IL. Deletion of the anxiety-related neuroligin 2 gene caused a decrease of this direct synaptic inhibition that originated from the IL. Thus, our data suggested that activation of the IL might not only directly activate the corresponding downstream anxiolytic pathway, but also suppress the PrL-related anxiogenic pathway and thus could differentially bias the regulation of fear expression and extinction. PMID:26882036

  14. A single GABAergic neuron mediates feedback of odor-evoked signals in the mushroom body of larval Drosophila

    PubMed Central

    Masuda-Nakagawa, Liria M.; Ito, Kei; Awasaki, Takeshi; O'Kane, Cahir J.

    2014-01-01

    Inhibition has a central role in defining the selectivity of the responses of higher order neurons to sensory stimuli. However, the circuit mechanisms of regulation of these responses by inhibitory neurons are still unclear. In Drosophila, the mushroom bodies (MBs) are necessary for olfactory memory, and by implication for the selectivity of learned responses to specific odors. To understand the circuitry of inhibition in the calyx (the input dendritic region) of the MBs, and its relationship with MB excitatory activity, we used the simple anatomy of the Drosophila larval olfactory system to identify any inhibitory inputs that could contribute to the selectivity of MB odor responses. We found that a single neuron accounts for all detectable GABA innervation in the calyx of the MBs, and that this neuron has pre-synaptic terminals in the calyx and post-synaptic branches in the MB lobes (output axonal area). We call this neuron the larval anterior paired lateral (APL) neuron, because of its similarity to the previously described adult APL neuron. Reconstitution of GFP partners (GRASP) suggests that the larval APL makes extensive contacts with the MB intrinsic neurons, Kenyon Cells (KCs), but few contacts with incoming projection neurons (PNs). Using calcium imaging of neuronal activity in live larvae, we show that the larval APL responds to odors, in a mannner that requires output from KCs. Our data suggest that the larval APL is the sole GABAergic neuron that innervates the MB input region and carries inhibitory feedback from the MB output region, consistent with a role in modulating the olfactory selectivity of MB neurons. PMID:24782716

  15. Expression of COUP-TFII Nuclear Receptor in Restricted GABAergic Neuronal Populations in the Adult Rat Hippocampus

    PubMed Central

    Fuentealba, Pablo; Klausberger, Thomas; Karayannis, Theofanis; Suen, Wai Yee; Huck, Jojanneke; Tomioka, Ryohei; Rockland, Kathleen; Capogna, Marco; Studer, Michèle; Morales, Marisela; Somogyi, Peter

    2015-01-01

    The COUP-TFII nuclear receptor, also known as NR2F2, is expressed in the developing ventral telencephalon and modulates the tangential migration of a set of subpallial neuronal progenitors during forebrain development. Little information is available about its expression patterns in the adult brain. We have identified the cell populations expressing COUP-TFII and the contribution of some of them to network activity in vivo. Expression of COUP-TFII by hippocampal pyramidal and dentate granule cells, as well as neurons in the neocortex, formed a gradient increasing from undetectable in the dorsal to very strong in the ventral sectors. In the dorsal hippocampal CA1 area, COUP-TFII was restricted to GABAergic interneurons and expressed in several, largely nonoverlapping neuronal populations. Immunoreactivity was present in calretinin-, neuronal nitric oxide synthase-, and reelin-expressing cells, as well as in subsets of cholecystokinin- or calbindin-expressing or radiatum-retrohippocampally projecting GABAergic cells, but not in parvalbumin-and/or somatostatin-expressing interneurons. In vivo recording and juxtacellular labeling of COUP-TFII-expressing cells revealed neurogliaform cells, basket cells in stratum radiatum and tachykinin-expressing radiatum dentate innervating interneurons, identified by their axodendritic distributions. They showed cell type-selective phase-locked firing to the theta rhythm but no activation during sharp wave/ripple oscillations. These basket cells in stratum radiatum and neurogliaform cells fired at the peak of theta oscillations detected extracellularly in stratum pyramidale, unlike previously reported ivy cells, which fired at the trough. The characterization of COUP-TFII-expressing neurons suggests that this developmentally important transcription factor plays cell type-specific role(s)in the adult hippocampus. PMID:20130170

  16. Enhanced GABAergic synaptic transmission at VLPAG neurons and potent modulation by oxycodone in a bone cancer pain model

    PubMed Central

    Takasu, Keiko; Ogawa, Koichi; Nakamura, Atsushi; Kanbara, Tomoe; Ono, Hiroko; Tomii, Takako; Morioka, Yasuhide; Hasegawa, Minoru; Shibasaki, Masahiro; Mori, Tomohisa; Suzuki, Tsutomu; Sakaguchi, Gaku

    2015-01-01

    Background and Purpose We demonstrated previously that oxycodone has potent antinociceptive effects at supraspinal sites. In this study, we investigated changes in neuronal function and antinociceptive mechanisms of oxycodone at ventrolateral periaqueductal gray (VLPAG) neurons, which are a major site of opioid action, in a femur bone cancer (FBC) model with bone cancer-related pain. Experimental Approach We characterized the supraspinal antinociceptive profiles of oxycodone and morphine on mechanical hypersensitivity in the FBC model. Based on the disinhibition mechanism underlying supraspinal opioid antinociception, the effects of oxycodone and morphine on GABAA receptor-mediated inhibitory postsynaptic currents (IPSCs) in VLPAG neurons were evaluated in slices from the FBC model. Key Results The supraspinal antinociceptive effects of oxycodone, but not morphine, were abolished by blocking G protein-gated inwardly rectifying potassium1 (Kir3.1) channels. In slices from the FBC model, GABAergic synaptic transmission at VLPAG neurons was enhanced, as indicated by a leftward shift of the input–output relationship curve of evoked IPSCs, the increased paired-pulse facilitation and the enhancement of miniature IPSC frequency. Following treatment with oxycodone and morphine, IPSCs were reduced in the FBC model, and the inhibition of presynaptic GABA release by oxycodone, but not morphine was enhanced and dependent on Kir3.1 channels. Conclusion and Implications Our results demonstrate that Kir3.1 channels are important for supraspinal antinociception and presynaptic GABA release inhibition by oxycodone in the FBC model. Enhanced GABAergic synaptic transmission at VLPAG neurons in the FBC model is an important site of supraspinal antinociception by oxycodone via Kir3.1 channel activation. PMID:25521524

  17. Optogenetic activation of GABAergic neurons in the nucleus accumbens decreases the activity of the ventral pallidum and the expression of cocaine-context-associated memory.

    PubMed

    Wang, Li; Shen, Minjie; Yu, Yongchun; Tao, Yezheng; Zheng, Ping; Wang, Feifei; Ma, Lan

    2014-05-01

    GABAergic medium-sized spiny neurons (MSNs) in the nucleus accumbens (NAc) differentially express D1 and D2 dopamine receptors. Both D2- and D1-MSNs in the NAc form projections into the ventral pallidum, whereas only D1-MSNs directly project into midbrain neurons. They are critical in rewarding and aversive learning, and understanding the function of these NAc efferents and the alteration of their targeted brain regions in responding to a reward-associated context is important. In this study, we activated the GABAergic neurons in the NAc of mice expressing channelrhodopsin-2 under the control of the vesicular GABA transporter promoter by an optogenetic approach, and examined its effects on the expression of cocaine-context-associated memory. In vivo optogenetic activation of the NAc GABAergic neurons inhibited the expression of cocaine-conditioned place preference (CPP). When tested 24 h later, these mice exhibited normal cocaine-induced CPP, indicating that the inhibitory effect on the expression of CPP was transient and reversible. Activation of the NAc GABAergic neurons also attenuated the learning of cocaine-induced reinforcement, as indicated by the results of behavioural sensitization. To explore how the cocaine-context-associated information was processed and integrated, we assessed the activity of NAc MSN-targeted brain nuclei and found that the activation of NAc GABAergic neurons during CPP expression resulted in a decrease of c-Fos+ cells in the ventral palladium. Our data suggested that the NAc GABAergic efferents inhibit the ventral palladium activity and negatively regulate the expression of motivational effects induced by cocaine-context-associated cues.

  18. Accelerated intoxication of GABAergic synapses by botulinum neurotoxin A disinhibits stem cell-derived neuron networks prior to network silencing

    PubMed Central

    Beske, Phillip H.; Scheeler, Stephen M.; Adler, Michael; McNutt, Patrick M.

    2015-01-01

    Botulinum neurotoxins (BoNTs) are extremely potent toxins that specifically cleave SNARE proteins in peripheral synapses, preventing neurotransmitter release. Neuronal responses to BoNT intoxication are traditionally studied by quantifying SNARE protein cleavage in vitro or monitoring physiological paralysis in vivo. Consequently, the dynamic effects of intoxication on synaptic behaviors are not well-understood. We have reported that mouse embryonic stem cell-derived neurons (ESNs) are highly sensitive to BoNT based on molecular readouts of intoxication. Here we study the time-dependent changes in synapse- and network-level behaviors following addition of BoNT/A to spontaneously active networks of glutamatergic and GABAergic ESNs. Whole-cell patch-clamp recordings indicated that BoNT/A rapidly blocked synaptic neurotransmission, confirming that ESNs replicate the functional pathophysiology responsible for clinical botulism. Quantitation of spontaneous neurotransmission in pharmacologically isolated synapses revealed accelerated silencing of GABAergic synapses compared to glutamatergic synapses, which was consistent with the selective accumulation of cleaved SNAP-25 at GAD1+ pre-synaptic terminals at early timepoints. Different latencies of intoxication resulted in complex network responses to BoNT/A addition, involving rapid disinhibition of stochastic firing followed by network silencing. Synaptic activity was found to be highly sensitive to SNAP-25 cleavage, reflecting the functional consequences of the localized cleavage of the small subpopulation of SNAP-25 that is engaged in neurotransmitter release in the nerve terminal. Collectively these findings illustrate that use of synaptic function assays in networked neurons cultures offers a novel and highly sensitive approach for mechanistic studies of toxin:neuron interactions and synaptic responses to BoNT. PMID:25954159

  19. GABAergic inhibition of histaminergic neurons regulates active waking but not the sleep-wake switch or propofol-induced loss of consciousness.

    PubMed

    Zecharia, Anna Y; Yu, Xiao; Götz, Thomas; Ye, Zhiwen; Carr, David R; Wulff, Peer; Bettler, Bernhard; Vyssotski, Alexei L; Brickley, Stephen G; Franks, Nicholas P; Wisden, William

    2012-09-19

    The activity of histaminergic neurons in the tuberomammillary nucleus (TMN) of the hypothalamus correlates with an animal's behavioral state and maintains arousal. We examined how GABAergic inputs onto histaminergic neurons regulate this behavior. A prominent hypothesis, the "flip-flop" model, predicts that increased and sustained GABAergic drive onto these cells promotes sleep. Similarly, because of the histaminergic neurons' key hub-like place in the arousal circuitry, it has also been suggested that anesthetics such as propofol induce loss of consciousness by acting primarily at histaminergic neurons. We tested both these hypotheses in mice by genetically removing ionotropic GABA(A) or metabotropic GABA(B) receptors from histidine decarboxylase-expressing neurons. At the cellular level, histaminergic neurons deficient in synaptic GABA(A) receptors were significantly more excitable and were insensitive to the anesthetic propofol. At the behavioral level, EEG profiles were recorded in nontethered mice over 24 h. Surprisingly, GABAergic transmission onto histaminergic neurons had no effect in regulating the natural sleep-wake cycle and, in the case of GABA(A) receptors, for propofol-induced loss of righting reflex. The latter finding makes it unlikely that the histaminergic TMN has a central role in anesthesia. GABA(B) receptors on histaminergic neurons were dispensable for all behaviors examined. Synaptic inhibition of histaminergic cells by GABA(A) receptors, however, was essential for habituation to a novel environment.

  20. Postnatal maternal separation enhances tonic GABA current of cortical layer 5 pyramidal neurons in juvenile rats and promotes genesis of GABAergic neurons in neocortical molecular layer and subventricular zone in adult rats.

    PubMed

    Feng, Mei; Sheng, Guoxia; Li, Zhongxia; Wang, Jiangping; Ren, Keming; Jin, Xiaoming; Jiang, Kewen

    2014-03-01

    Postnatal maternal separation (PMS) has been shown to be associated with an increased vulnerability to psychiatric illnesses in adulthood. However, the underlying neurological mechanisms are not well understood. Here we evaluated its effects on neurogenesis and tonic GABA currents of cortical layer 5 (L5) pyramidal neurons. PMS not only increased cell proliferation in the subventricular zone, cortical layer 1 and hippocampal dentate gyrus in the adult brain, but also promoted the newly generated cells to differentiate into GABAergic neurons, and PMS adult brain maintained higher ratios of GABAergic neurons in the survival of newly generated cells within 5 days immediately post PMS. Additionally, PMS increased the tonic currents at P7-10 and P30-35 in cortical L5 pyramidal cells. Our results suggest that the newly generated GABAergic neurons and the low GABA concentration-activated tonic currents may be involved in the development of psychiatric disorders after PMS.

  1. Activation of synaptic group II metabotropic glutamate receptors induces long-term depression at GABAergic synapses in CNS neurons.

    PubMed

    Tang, Zheng-Quan; Liu, Yu-Wei; Shi, Wei; Dinh, Emilie Hoang; Hamlet, William R; Curry, Rebecca J; Lu, Yong

    2013-10-01

    Metabotropic glutamate receptor (mGluR)-dependent homosynaptic long-term depression (LTD) has been studied extensively at glutamatergic synapses in the CNS. However, much less is known about heterosynaptic long-term plasticity induced by mGluRs at inhibitory synapses. Here we report that pharmacological or synaptic activation of group II mGluRs (mGluR II) induces LTD at GABAergic synapses without affecting the excitatory glutamatergic transmission in neurons of the chicken cochlear nucleus. Coefficient of variation and failure rate analysis suggested that the LTD was expressed presynaptically. The LTD requires presynaptic spike activity, but does not require the activation of NMDA receptors. The classic cAMP-dependent protein kinase A signaling is involved in the transduction pathway. Remarkably, blocking mGluR II increased spontaneous GABA release, indicating the presence of tonic activation of mGluR II by ambient glutamate. Furthermore, synaptically released glutamate induced by electrical stimulations that concurrently activated both the glutamatergic and GABAergic pathways resulted in significant and constant suppression of GABA release at various stimulus frequencies (3.3, 100, and 300 Hz). Strikingly, low-frequency stimulation (1 Hz, 15 min) of the glutamatergic synapses induced heterosynaptic LTD of GABAergic transmission, and the LTD was blocked by mGluR II antagonist, indicating that synaptic activation of mGluR II induced the LTD. This novel form of long-term plasticity in the avian auditory brainstem may play a role in the development as well as in temporal processing in the sound localization circuit.

  2. Restoration of Mecp2 expression in GABAergic neurons is sufficient to rescue multiple disease features in a mouse model of Rett syndrome

    PubMed Central

    Ure, Kerstin; Lu, Hui; Wang, Wei; Ito-Ishida, Aya; Wu, Zhenyu; He, Ling-jie; Sztainberg, Yehezkel; Chen, Wu; Tang, Jianrong; Zoghbi, Huda Y

    2016-01-01

    The postnatal neurodevelopmental disorder Rett syndrome, caused by mutations in MECP2, produces a diverse array of symptoms, including loss of language, motor, and social skills and the development of hand stereotypies, anxiety, tremor, ataxia, respiratory dysrhythmias, and seizures. Surprisingly, despite the diversity of these features, we have found that deleting Mecp2 only from GABAergic inhibitory neurons in mice replicates most of this phenotype. Here we show that genetically restoring Mecp2 expression only in GABAergic neurons of male Mecp2 null mice enhanced inhibitory signaling, extended lifespan, and rescued ataxia, apraxia, and social abnormalities but did not rescue tremor or anxiety. Female Mecp2+/- mice showed a less dramatic but still substantial rescue. These findings highlight the critical regulatory role of GABAergic neurons in certain behaviors and suggest that modulating the excitatory/inhibitory balance through GABAergic neurons could prove a viable therapeutic option in Rett syndrome. DOI: http://dx.doi.org/10.7554/eLife.14198.001 PMID:27328321

  3. The DEG/ENaC cation channel protein UNC-8 drives activity-dependent synapse removal in remodeling GABAergic neurons

    PubMed Central

    Miller-Fleming, Tyne W; Petersen, Sarah C; Manning, Laura; Matthewman, Cristina; Gornet, Megan; Beers, Allison; Hori, Sayaka; Mitani, Shohei; Bianchi, Laura; Richmond, Janet; Miller, David M

    2016-01-01

    Genetic programming and neural activity drive synaptic remodeling in developing neural circuits, but the molecular components that link these pathways are poorly understood. Here we show that the C. elegans Degenerin/Epithelial Sodium Channel (DEG/ENaC) protein, UNC-8, is transcriptionally controlled to function as a trigger in an activity-dependent mechanism that removes synapses in remodeling GABAergic neurons. UNC-8 cation channel activity promotes disassembly of presynaptic domains in DD type GABA neurons, but not in VD class GABA neurons where unc-8 expression is blocked by the COUP/TF transcription factor, UNC-55. We propose that the depolarizing effect of UNC-8-dependent sodium import elevates intracellular calcium in a positive feedback loop involving the voltage-gated calcium channel UNC-2 and the calcium-activated phosphatase TAX-6/calcineurin to initiate a caspase-dependent mechanism that disassembles the presynaptic apparatus. Thus, UNC-8 serves as a link between genetic and activity-dependent pathways that function together to promote the elimination of GABA synapses in remodeling neurons. DOI: http://dx.doi.org/10.7554/eLife.14599.001 PMID:27403890

  4. Ethanol exposure during development reduces GABAergic/glycinergic neuron numbers and lobule volumes in the mouse cerebellar vermis.

    PubMed

    Nirgudkar, Pranita; Taylor, Devin H; Yanagawa, Yuchio; Valenzuela, C Fernando

    2016-10-01

    Cerebellar alterations are a hallmark of Fetal Alcohol Spectrum Disorders and are thought to be responsible for deficits in fine motor control, motor learning, balance, and higher cognitive functions. These deficits are, in part, a consequence of dysfunction of cerebellar circuits. Although the effect of developmental ethanol exposure on Purkinje and granule cells has been previously characterized, its actions on other cerebellar neuronal populations are not fully understood. Here, we assessed the impact of repeated ethanol exposure on the number of inhibitory neurons in the cerebellar vermis. We exposed pregnant mice to ethanol in vapor inhalation chambers during gestational days 12-19 and offspring during postnatal days 2-9. We used transgenic mice expressing the fluorescent protein, Venus, in GABAergic/glycinergic neurons. Using unbiased stereology techniques, we detected a reduction in Venus positive neurons in the molecular and granule cell layers of lobule II in the ethanol exposed group at postnatal day 16. In contrast, ethanol produced a more widespread reduction in Purkinje cell numbers that involved lobules II, IV-V and IX. We also found a reduction in the volume of lobules II, IV-V, VI-VII, IX and X in ethanol-exposed pups. These findings indicate that second and third trimester-equivalent ethanol exposure has a greater impact on Purkinje cells than interneurons in the developing cerebellar vermis. The decrease in the volume of most lobules could be a consequence of a reduction in cell numbers, dendritic arborizations, or axonal projections.

  5. Ethanol exposure during development reduces GABAergic/glycinergic neuron numbers and lobule volumes in the mouse cerebellar vermis.

    PubMed

    Nirgudkar, Pranita; Taylor, Devin H; Yanagawa, Yuchio; Valenzuela, C Fernando

    2016-10-01

    Cerebellar alterations are a hallmark of Fetal Alcohol Spectrum Disorders and are thought to be responsible for deficits in fine motor control, motor learning, balance, and higher cognitive functions. These deficits are, in part, a consequence of dysfunction of cerebellar circuits. Although the effect of developmental ethanol exposure on Purkinje and granule cells has been previously characterized, its actions on other cerebellar neuronal populations are not fully understood. Here, we assessed the impact of repeated ethanol exposure on the number of inhibitory neurons in the cerebellar vermis. We exposed pregnant mice to ethanol in vapor inhalation chambers during gestational days 12-19 and offspring during postnatal days 2-9. We used transgenic mice expressing the fluorescent protein, Venus, in GABAergic/glycinergic neurons. Using unbiased stereology techniques, we detected a reduction in Venus positive neurons in the molecular and granule cell layers of lobule II in the ethanol exposed group at postnatal day 16. In contrast, ethanol produced a more widespread reduction in Purkinje cell numbers that involved lobules II, IV-V and IX. We also found a reduction in the volume of lobules II, IV-V, VI-VII, IX and X in ethanol-exposed pups. These findings indicate that second and third trimester-equivalent ethanol exposure has a greater impact on Purkinje cells than interneurons in the developing cerebellar vermis. The decrease in the volume of most lobules could be a consequence of a reduction in cell numbers, dendritic arborizations, or axonal projections. PMID:27565053

  6. The DEG/ENaC cation channel protein UNC-8 drives activity-dependent synapse removal in remodeling GABAergic neurons.

    PubMed

    Miller-Fleming, Tyne W; Petersen, Sarah C; Manning, Laura; Matthewman, Cristina; Gornet, Megan; Beers, Allison; Hori, Sayaka; Mitani, Shohei; Bianchi, Laura; Richmond, Janet; Miller, David M

    2016-01-01

    Genetic programming and neural activity drive synaptic remodeling in developing neural circuits, but the molecular components that link these pathways are poorly understood. Here we show that the C. elegans Degenerin/Epithelial Sodium Channel (DEG/ENaC) protein, UNC-8, is transcriptionally controlled to function as a trigger in an activity-dependent mechanism that removes synapses in remodeling GABAergic neurons. UNC-8 cation channel activity promotes disassembly of presynaptic domains in DD type GABA neurons, but not in VD class GABA neurons where unc-8 expression is blocked by the COUP/TF transcription factor, UNC-55. We propose that the depolarizing effect of UNC-8-dependent sodium import elevates intracellular calcium in a positive feedback loop involving the voltage-gated calcium channel UNC-2 and the calcium-activated phosphatase TAX-6/calcineurin to initiate a caspase-dependent mechanism that disassembles the presynaptic apparatus. Thus, UNC-8 serves as a link between genetic and activity-dependent pathways that function together to promote the elimination of GABA synapses in remodeling neurons. PMID:27403890

  7. GABAergic neuron deficit as an idiopathic generalized epilepsy mechanism: the role of BRD2 haploinsufficiency in juvenile myoclonic epilepsy.

    PubMed

    Velíšek, Libor; Shang, Enyuan; Velíšková, Jana; Chachua, Tamar; Macchiarulo, Stephania; Maglakelidze, Giorgi; Wolgemuth, Debra J; Greenberg, David A

    2011-01-01

    Idiopathic generalized epilepsy (IGE) syndromes represent about 30% of all epilepsies. They have strong, but elusive, genetic components and sex-specific seizure expression. Multiple linkage and population association studies have connected the bromodomain-containing gene BRD2 to forms of IGE. In mice, a null mutation at the homologous Brd2 locus results in embryonic lethality while heterozygous Brd2+/- mice are viable and overtly normal. However, using the flurothyl model, we now show, that compared to the Brd2+/+ littermates, Brd2+/- males have a decreased clonic, and females a decreased tonic-clonic, seizure threshold. Additionally, long-term EEG/video recordings captured spontaneous seizures in three out of five recorded Brd2+/- female mice. Anatomical analysis of specific regions of the brain further revealed significant differences in Brd2+/- vs +/+ mice. Specifically, there were decreases in the numbers of GABAergic (parvalbumin- or GAD67-immunopositive) neurons along the basal ganglia pathway, i.e., in the neocortex and striatum of Brd2+/- mice, compared to Brd2+/+ mice. There were also fewer GABAergic neurons in the substantia nigra reticulata (SNR), yet there was a minor, possibly compensatory increase in the GABA producing enzyme GAD67 in these SNR cells. Further, GAD67 expression in the superior colliculus and ventral medial thalamic nucleus, the main SNR outputs, was significantly decreased in Brd2+/- mice, further supporting GABA downregulation. Our data show that the non-channel-encoding, developmentally critical Brd2 gene is associated with i) sex-specific increases in seizure susceptibility, ii) the development of spontaneous seizures, and iii) seizure-related anatomical changes in the GABA system, supporting BRD2's involvement in human IGE. PMID:21887291

  8. Non-avoidance behaviour in enchytraeids to boric acid is related to the GABAergic mechanism.

    PubMed

    Bicho, Rita C; Gomes, Susana I L; Soares, Amadeu M V M; Amorim, Mónica J B

    2015-05-01

    Soil invertebrates, e.g. enchytraeids, are known to be able to avoid unfavourable conditions, which gives them an important ecological advantage. These organisms possess chemoreceptors that can detect stressors, which in turn activate responses such as avoidance behaviour. We studied the avoidance behaviour in response to boric acid (BA) using enchytraeids. Results showed not only no avoidance, but that increasing concentrations seemed to have an "attraction" effect. To study the underlying mechanism, a selection of genes targeting for neurotransmission pathways (acetylcholinesterase (AChE) and gamma-aminobutyric acid receptor (GABAr)) were quantified via quantitative real-time polymerase chain reaction (qPCR). Evidences were that BA is neurotoxic via the GABAergic system mechanism where it acts as a GABA-associated protein receptor (GABAAR) antagonist possibly causing anaesthetic effects. This is the first time that (non)avoidance behaviour in invertebrates was studied in relation with the GABAergic system. We strongly recommend the combination of such gene and/or functional assay studies with the avoidance behaviour test as it can bring many advantages and important interpretation lines for ecotoxicity with minor effort.

  9. The hippocamposeptal pathway generates rhythmic firing of GABAergic neurons in the medial septum and diagonal bands: an investigation using a complete septohippocampal preparation in vitro.

    PubMed

    Manseau, Frédéric; Goutagny, Romain; Danik, Marc; Williams, Sylvain

    2008-04-01

    The medial septum diagonal band area (MS/DB) projects to the hippocampus through the fornix/fimbria pathway and is implicated in generating hippocampal theta oscillations. The hippocampus also projects back to the MS/DB, but very little is known functionally about this input. Here, we investigated the physiological role of hippocamposeptal feedback to the MS/DB in a complete in vitro septohippocampal preparation containing the intact interconnecting fornix/fimbria pathway. We demonstrated that carbachol-induced rhythmic theta-like hippocampal oscillations recorded extracellularly were synchronized with powerful rhythmic IPSPs in whole-cell recorded MS/DB neurons. Interestingly, we found that these IPSPs evoked rebound spiking in GABAergic MS/DB neurons. In contrast, putative cholinergic and glutamatergic MS/DB neurons responded only weakly with rebound spiking and, as a result, were mostly silent during theta-like oscillations. We next determined the mechanism underlying the rebound spiking that followed the IPSPs in MS/DB GABAergic neurons using phasic electrical stimulation of the fornix/fimbria pathway. We demonstrate that the increased rebound spiking was attributable to the activation of I(h) current, because it was significantly reduced by low concentrations of the I(h) antagonist ZD7288 [4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyridinium chloride]. Together, these results suggest that rhythmical activity in hippocampus is transferred to the MS/DB and can preferentially phase the spiking of GABAergic MS/DB neurons because of their significant expression of I(h) currents. Our data demonstrate that hippocamposeptal inhibition facilitates theta rhythmic discharges in MS/DB GABAergic neurons while favoring the inhibition of most ACh and glutamate neurons. PMID:18400909

  10. GABA concentration and GABAergic neuron populations in limbic areas are differentially altered by brain serotonin deficiency in Tph2 knockout mice.

    PubMed

    Waider, Jonas; Proft, Florian; Langlhofer, Georg; Asan, Esther; Lesch, Klaus-Peter; Gutknecht, Lise

    2013-02-01

    While tryptophan hydroxylase-2 (Tph2) null mutant (Tph2(-/-)) mice are completely deficient in brain serotonin (5-HT) synthesis, the formation of serotonergic neurons and pathfinding of their projections are not impaired. However, 5-HT deficiency, during development and in the adult, might affect morphological and functional parameters of other neural systems. To assess the influence of 5-HT deficiency on γ-amino butyric acid (GABA) systems, we carried out measurements of GABA concentrations in limbic brain regions of adult male wildtype (wt), heterozygous (Tph2(+/-)) and Tph2(-/-) mice. In addition, unbiased stereological estimation of GABAergic interneuron numbers and density was performed in subregions of amygdala and hippocampus. Amygdala and prefrontal cortex displayed significantly increased and decreased GABA concentrations, respectively, exclusively in Tph2(+/-) mice while no changes were detected between Tph2(-/-) and wt mice. In contrast, in the hippocampus, increased GABA concentrations were found in Tph2(-/-) mice. While total cell density in the anterior basolateral amygdala did not differ between genotypes, the number and density of the GABAergic interneurons were significantly decreased in Tph2(-/-) mice, with the group of parvalbumin (PV)-immunoreactive (ir) interneurons contributing somewhat less to the decrease than that of non-PV-ir GABAergic interneurons. Major morphological changes were also absent in the dorsal hippocampus, and only a trend toward reduced density of PV-ir cells was observed in the CA3 region of Tph2(-/-) mice. Our findings are the first to document that life-long reduction or complete lack of brain 5-HT transmission causes differential changes of GABA systems in limbic regions which are key players in emotional learning and memory processes. The changes likely reflect a combination of developmental alterations and functional adaptations of emotion circuits to balance the lack of 5-HT, and may underlie altered emotional

  11. GABAergic neurons of the laterodorsal and pedunculopontine tegmental nuclei of the cat express c-fos during carbachol-induced active sleep.

    PubMed

    Torterolo, P; Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    2001-02-23

    The laterodorsal and pedunculopontine tegmental nuclei (LDT-PPT) are involved in the generation of active sleep (AS; also called REM or rapid eye movement sleep). Although the LDT-PPT are composed principally of cholinergic neurons that participate in the control of sleep and waking states, the function of the large number of GABAergic neurons that are also located in the LDT-PPT is unknown. Consequently, we sought to determine if these neurons are activated (as indicated by their c-fos expression) during active sleep induced by the microinjection of carbachol into the rostro-dorsal pons (AS-carbachol). Accordingly, immunocytochemical double-labeling techniques were used to identify GABA and Fos protein, as well as choline acetyltransferase (ChAT), in histological sections of the LDT-PPT. Compared to control awake cats, there was a larger number of GABAergic neurons that expressed c-fos during AS-carbachol (31.5+/-6.1 vs. 112+/-15.2, P<0.005). This increase in the number of GABA+Fos+ neurons occurred on the ipsilateral side relative to the injection site; there was a small decrease in GABA+Fos+ cells in the contralateral LDT-PPT. However, the LDT-PPT neurons that exhibited the largest increase in c-fos expression during AS-carbachol were neither GABA+ nor ChAT+ (47+/-22.5 vs. 228.7+/-14.0, P<0.0005). The number of cholinergic neurons that expressed c-fos during AS-carbachol was not significantly different compared to wakefulness. These data demonstrate that, during AS-carbachol, GABAergic as well as an unidentified population of neurons are activated in the LDT-PPT. We propose that these non-cholinergic LDT-PPT neurons may participate in the regulation of active sleep. PMID:11172778

  12. GABAergic neurons of the laterodorsal and pedunculopontine tegmental nuclei of the cat express c-fos during carbachol-induced active sleep.

    PubMed

    Torterolo, P; Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    2001-02-23

    The laterodorsal and pedunculopontine tegmental nuclei (LDT-PPT) are involved in the generation of active sleep (AS; also called REM or rapid eye movement sleep). Although the LDT-PPT are composed principally of cholinergic neurons that participate in the control of sleep and waking states, the function of the large number of GABAergic neurons that are also located in the LDT-PPT is unknown. Consequently, we sought to determine if these neurons are activated (as indicated by their c-fos expression) during active sleep induced by the microinjection of carbachol into the rostro-dorsal pons (AS-carbachol). Accordingly, immunocytochemical double-labeling techniques were used to identify GABA and Fos protein, as well as choline acetyltransferase (ChAT), in histological sections of the LDT-PPT. Compared to control awake cats, there was a larger number of GABAergic neurons that expressed c-fos during AS-carbachol (31.5+/-6.1 vs. 112+/-15.2, P<0.005). This increase in the number of GABA+Fos+ neurons occurred on the ipsilateral side relative to the injection site; there was a small decrease in GABA+Fos+ cells in the contralateral LDT-PPT. However, the LDT-PPT neurons that exhibited the largest increase in c-fos expression during AS-carbachol were neither GABA+ nor ChAT+ (47+/-22.5 vs. 228.7+/-14.0, P<0.0005). The number of cholinergic neurons that expressed c-fos during AS-carbachol was not significantly different compared to wakefulness. These data demonstrate that, during AS-carbachol, GABAergic as well as an unidentified population of neurons are activated in the LDT-PPT. We propose that these non-cholinergic LDT-PPT neurons may participate in the regulation of active sleep.

  13. Chaoborus and gasterosteus anti-predator responses in Daphnia pulex are mediated by independent cholinergic and gabaergic neuronal signals.

    PubMed

    Weiss, Linda C; Kruppert, Sebastian; Laforsch, Christian; Tollrian, Ralph

    2012-01-01

    Many prey species evolved inducible defense strategies that protect effectively against predation threats. Especially the crustacean Daphnia emerged as a model system for studying the ecology and evolution of inducible defenses. Daphnia pulex e.g. shows different phenotypic adaptations against vertebrate and invertebrate predators. In response to the invertebrate phantom midge larvae Chaoborus (Diptera) D. pulex develops defensive morphological defenses (neckteeth). Cues originating from predatory fish result in life history changes in which resources are allocated from somatic growth to reproduction. While there are hints that responses against Chaoborus cues are transmitted involving cholinergic neuronal pathways, nothing is known about the neurophysiology underlying the transmission of fish related cues. We investigated the neurophysiological basis underlying the activation of inducible defenses in D. pulex using induction assays with the invertebrate predator Chaoborus and the three-spined stickleback Gasterosteus aculeatus. Predator-specific cues were combined with neuro-effective substances that stimulated or inhibited the cholinergic and gabaergic nervous system. We show that cholinergic-dependent pathways are involved in the perception and transmission of Chaoborus cues, while GABA was not involved. Thus, the cholinergic nervous system independently mediates the development of morphological defenses in response to Chaoborus cues. In contrast, only the inhibitory effect of GABA significantly influence fish-induced life history changes, while the application of cholinergic stimulants had no effect in combination with fish related cues. Our results show that cholinergic stimulation mediates signal transmission of Chaoborus cues leading to morphological defenses. Fish cues, which are responsible for predator-specific life history adaptations involve gabaergic control. Our study shows that both pathways are independent and thus potentially allow for adjustment

  14. Chaoborus and Gasterosteus Anti-Predator Responses in Daphnia pulex Are Mediated by Independent Cholinergic and Gabaergic Neuronal Signals

    PubMed Central

    Weiss, Linda C.; Kruppert, Sebastian; Laforsch, Christian; Tollrian, Ralph

    2012-01-01

    Many prey species evolved inducible defense strategies that protect effectively against predation threats. Especially the crustacean Daphnia emerged as a model system for studying the ecology and evolution of inducible defenses. Daphnia pulex e.g. shows different phenotypic adaptations against vertebrate and invertebrate predators. In response to the invertebrate phantom midge larvae Chaoborus (Diptera) D. pulex develops defensive morphological defenses (neckteeth). Cues originating from predatory fish result in life history changes in which resources are allocated from somatic growth to reproduction. While there are hints that responses against Chaoborus cues are transmitted involving cholinergic neuronal pathways, nothing is known about the neurophysiology underlying the transmission of fish related cues. We investigated the neurophysiological basis underlying the activation of inducible defenses in D. pulex using induction assays with the invertebrate predator Chaoborus and the three-spined stickleback Gasterosteus aculeatus. Predator-specific cues were combined with neuro-effective substances that stimulated or inhibited the cholinergic and gabaergic nervous system. We show that cholinergic-dependent pathways are involved in the perception and transmission of Chaoborus cues, while GABA was not involved. Thus, the cholinergic nervous system independently mediates the development of morphological defenses in response to Chaoborus cues. In contrast, only the inhibitory effect of GABA significantly influence fish-induced life history changes, while the application of cholinergic stimulants had no effect in combination with fish related cues. Our results show that cholinergic stimulation mediates signal transmission of Chaoborus cues leading to morphological defenses. Fish cues, which are responsible for predator-specific life history adaptations involve gabaergic control. Our study shows that both pathways are independent and thus potentially allow for adjustment

  15. GABAergic Projections to the Oculomotor Nucleus in the Goldfish (carassius Auratus)

    PubMed Central

    Luque, M. Angeles; Torres-Torrelo, Julio; Carrascal, Livia; Torres, Blas; Herrero, Luis

    2010-01-01

    The mammalian oculomotor nucleus receives a strong γ-aminobutyric acid (GABA)ergic synaptic input, whereas such projections have rarely been reported in fish. In order to determine whether this synaptic organization is preserved across vertebrates, we investigated the GABAergic projections to the oculomotor nucleus in the goldfish by combining retrograde transport of biotin dextran amine, injected into the antidromically identified oculomotor nucleus, and GABA immunohistochemistry. The main source of GABAergic afferents to the oculomotor nucleus was the ipsilateral anterior octaval nucleus, with only a few, if any, GABAergic neurons being located in the contralateral tangential and descending nuclei of the octaval column. In mammals there is a nearly GABAergic inhibitory inputs; thus, the vestibulooculomotor GABAergic circuitry follows a plan that appears to be shared throughout the vertebrate phylogeny. The second major source of GABAergic projections was the rhombencephalic reticular formation, primarily from the medial area but, to a lesser extent, from the inferior area. A few GABAergic oculomotor projecting neurons were also observed in the ipsilateral nucleus of the medial longitudinal fasciculus. The GABAergic projections from neurons located in both the reticular formation surrounding the abducens nucleus and the nucleus of the medial reticular formation have primarily been related to the control of saccadic eye movements. Finally, all retrogradely labeled internuclear neurons of the abducens nucleus, and neurons in the cerebellum (close to the caudal lobe), were negative for GABA. These data suggest that the vestibuloocular and saccadic inhibitory GABAergic systems appear early in vertebrate phylogeny to modulate the firing properties of the oculomotor nucleus motoneurons. PMID:21331170

  16. Brain region specific modulation of ethanol-induced depression of GABAergic neurons in the brain reward system by the nicotine receptor antagonist mecamylamine.

    PubMed

    Adermark, Louise; Söderpalm, Bo; Burkhardt, John M

    2014-08-01

    The mechanisms underlying ethanol-induced activation of the mesolimbic dopamine system are not fully understood, but increased extracellular dopamine in the nucleus accumbens (nAc) has been shown to involve nicotinic acetylcholine receptors (nAChRs). Basal activity of dopaminergic neurons in the ventral tegmental area (VTA) is under the influence of GABAergic neurotransmission, and the aim of this study was to characterize the involvement of nAChRs in mediating acute ethanol effects on GABAergic activity in subregions of the brain reward system. Multi-electrode in vivo recordings were made in the VTA and nAc of awake and behaving C57BL6/J mice receiving intraperitoneal injections of saline or ethanol (2.0 g/kg), combined with, or without, pre-injection of the non-competitive nAChR antagonist mecamylamine (1.0 mg/kg). Ethanol significantly decreased the activity of quinpirole-insensitive slow-spiking and fast-spiking units in both the VTA and the nAc as compared to saline injection. Pre-treatment with mecamylamine inhibited the rate-inhibiting properties of ethanol in the VTA, but not in the nAc. The data presented here show that ethanol depresses the activity of quinpirole-insensitive, putative GABAergic neurons, in the mesolimbic dopamine system of mice, and that nAChRs contribute to this modulation. This finding, taken together with previous microdialysis studies, supports an involvement of GABAergic neurons and nAChRs in ethanol's interaction with the mesolimbic dopamine system.

  17. GABAergic circuit dysfunction in the Drosophila Fragile X syndrome model.

    PubMed

    Gatto, Cheryl L; Pereira, Daniel; Broadie, Kendal

    2014-05-01

    Fragile X syndrome (FXS), caused by loss of FMR1 gene function, is the most common heritable cause of intellectual disability and autism spectrum disorders. The FMR1 protein (FMRP) translational regulator mediates activity-dependent control of synapses. In addition to the metabotropic glutamate receptor (mGluR) hyperexcitation FXS theory, the GABA theory postulates that hypoinhibition is causative for disease state symptoms. Here, we use the Drosophila FXS model to assay central brain GABAergic circuitry, especially within the Mushroom Body (MB) learning center. All 3 GABAA receptor (GABAAR) subunits are reportedly downregulated in dfmr1 null brains. We demonstrate parallel downregulation of glutamic acid decarboxylase (GAD), the rate-limiting GABA synthesis enzyme, although GABAergic cell numbers appear unaffected. Mosaic analysis with a repressible cell marker (MARCM) single-cell clonal studies show that dfmr1 null GABAergic neurons innervating the MB calyx display altered architectural development, with early underdevelopment followed by later overelaboration. In addition, a new class of extra-calyx terminating GABAergic neurons is shown to include MB intrinsic α/β Kenyon Cells (KCs), revealing a novel level of MB inhibitory regulation. Functionally, dfmr1 null GABAergic neurons exhibit elevated calcium signaling and altered kinetics in response to acute depolarization. To test the role of these GABAergic changes, we attempted to pharmacologically restore GABAergic signaling and assay effects on the compromised MB-dependent olfactory learning in dfmr1 mutants, but found no improvement. Our results show that GABAergic circuit structure and function are impaired in the FXS disease state, but that correction of hypoinhibition alone is not sufficient to rescue a behavioral learning impairment.

  18. Striatal GABAergic and cortical glutamatergic neurons mediate contrasting effects of cannabinoids on cortical network synchrony.

    PubMed

    Sales-Carbonell, Carola; Rueda-Orozco, Pavel E; Soria-Gómez, Edgar; Buzsáki, György; Marsicano, Giovanni; Robbe, David

    2013-01-01

    Activation of type 1 cannabinoid receptors (CB1R) decreases GABA and glutamate release in cortical and subcortical regions, with complex outcomes on cortical network activity. To date there have been few attempts to disentangle the region- and cell-specific mechanisms underlying the effects of cannabinoids on cortical network activity in vivo. Here we addressed this issue by combining in vivo electrophysiological recordings with local and systemic pharmacological manipulations in conditional mutant mice lacking CB1R expression in different neuronal populations. First we report that cannabinoids induce hypersynchronous thalamocortical oscillations while decreasing the amplitude of faster cortical oscillations. Then we demonstrate that CB1R at striatonigral synapses (basal ganglia direct pathway) mediate the thalamocortical hypersynchrony, whereas activation of CB1R expressed in cortical glutamatergic neurons decreases cortical synchrony. Finally we show that activation of CB1 expressed in cortical glutamatergic neurons limits the cannabinoid-induced thalamocortical hypersynchrony. By reporting that CB1R activations in cortical and subcortical regions have contrasting effects on cortical synchrony, our study bridges the gap between cellular and in vivo network effects of cannabinoids. Incidentally, the thalamocortical hypersynchrony we report suggests a potential mechanism to explain the sensory "high" experienced during recreational consumption of marijuana.

  19. Striatal GABAergic and cortical glutamatergic neurons mediate contrasting effects of cannabinoids on cortical network synchrony

    PubMed Central

    Sales-Carbonell, Carola; Rueda-Orozco, Pavel E.; Soria-Gómez, Edgar; Buzsáki, György; Marsicano, Giovanni; Robbe, David

    2013-01-01

    Activation of type 1 cannabinoid receptors (CB1R) decreases GABA and glutamate release in cortical and subcortical regions, with complex outcomes on cortical network activity. To date there have been few attempts to disentangle the region- and cell-specific mechanisms underlying the effects of cannabinoids on cortical network activity in vivo. Here we addressed this issue by combining in vivo electrophysiological recordings with local and systemic pharmacological manipulations in conditional mutant mice lacking CB1R expression in different neuronal populations. First we report that cannabinoids induce hypersynchronous thalamocortical oscillations while decreasing the amplitude of faster cortical oscillations. Then we demonstrate that CB1R at striatonigral synapses (basal ganglia direct pathway) mediate the thalamocortical hypersynchrony, whereas activation of CB1R expressed in cortical glutamatergic neurons decreases cortical synchrony. Finally we show that activation of CB1 expressed in cortical glutamatergic neurons limits the cannabinoid-induced thalamocortical hypersynchrony. By reporting that CB1R activations in cortical and subcortical regions have contrasting effects on cortical synchrony, our study bridges the gap between cellular and in vivo network effects of cannabinoids. Incidentally, the thalamocortical hypersynchrony we report suggests a potential mechanism to explain the sensory “high” experienced during recreational consumption of marijuana. PMID:23269835

  20. Extracellular Molecular Markers and Soma Size of Inhibitory Neurons: Evidence for Four Subtypes of GABAergic Cells in the Inferior Colliculus

    PubMed Central

    Beebe, Nichole L.; Young, Jesse W.; Mellott, Jeffrey G.

    2016-01-01

    Inhibition plays an important role in shaping responses to stimuli throughout the CNS, including in the inferior colliculus (IC), a major hub in both ascending and descending auditory pathways. Subdividing GABAergic cells has furthered the understanding of inhibition in many brain areas, most notably in the cerebral cortex. Here, we seek the same understanding of subcortical inhibitory cell types by combining staining for two types of extracellular markers—perineuronal nets (PNs) and perisomatic rings of terminals expressing vesicular glutamate transporter 2 (VGLUT2) —to subdivide IC GABAergic cells in adult guinea pigs. We found four distinct groups of GABAergic cells in the IC: (1) those with both a PN and a VGLUT2 ring; (2) those with only a PN; (3) those with only a VGLUT2 ring; and (4) those with neither marker. In addition, these four GABAergic subtypes differ in their soma size and distribution among IC subdivisions. Functionally, the presence or absence of VGLUT2 rings indicates differences in inputs, whereas the presence or absence of PNs indicates different potential for plasticity and temporal processing. We conclude that these markers distinguish four GABAergic subtypes that almost certainly serve different roles in the processing of auditory stimuli within the IC. SIGNIFICANCE STATEMENT GABAergic inhibition plays a critical role throughout the brain. Identification of subclasses of GABAergic cells (up to 15 in the cerebral cortex) has furthered the understanding of GABAergic roles in circuit modulation. Inhibition is also prominent in the inferior colliculus, a subcortical hub in auditory pathways. Here, we use two extracellular markers to identify four distinct groups of GABAergic cells. Perineuronal nets and perisomatic rings of glutamatergic boutons are present in many subcortical areas and often are associated with inhibitory cells, but they have rarely been used to identify inhibitory subtypes. Our results further the understanding of

  1. Effect of GABAergic inhibition on odorant concentration coding in mushroom body intrinsic neurons of the honeybee.

    PubMed

    Froese, Anja; Szyszka, Paul; Menzel, Randolf

    2014-03-01

    Kenyon cells, the intrinsic neurons of the insect mushroom body, have the intriguing property of responding in a sparse way to odorants. Sparse neuronal codes are often invariant to changes in stimulus intensity and duration, and sparse coding often depends on global inhibition. We tested if this is the case for honeybees' Kenyon cells, too, and used in vivo Ca²⁺ imaging to record their responses to different odorant concentrations. Kenyon cells responded not only to the onset of odorant stimuli (ON responses), but also to their termination (OFF responses). Both, ON and OFF responses increased with increasing odorant concentration. ON responses were phasic and invariant to the duration of odorant stimuli, while OFF responses increased with increasing odorant duration. Pharmacological blocking of GABA receptors in the brain revealed that ionotropic GABA(A) and metabotropic GABA(B) receptors attenuate Kenyon cells' ON responses without changing their OFF responses. Ionotropic GABA(A) receptors attenuated Kenyon cell ON responses more strongly than metabotropic GABA(B) receptors. However, the response dynamic, temporal resolution and paired-pulse depression did not depend on GABA(A) transmission. These data are discussed in the context of mechanisms leading to sparse coding in Kenyon cells.

  2. Transcriptional Networks Controlled by NKX2-1 in the Development of Forebrain GABAergic Neurons.

    PubMed

    Sandberg, Magnus; Flandin, Pierre; Silberberg, Shanni; Su-Feher, Linda; Price, James D; Hu, Jia Sheng; Kim, Carol; Visel, Axel; Nord, Alex S; Rubenstein, John L R

    2016-09-21

    The embryonic basal ganglia generates multiple projection neurons and interneuron subtypes from distinct progenitor domains. Combinatorial interactions of transcription factors and chromatin are thought to regulate gene expression. In the medial ganglionic eminence, the NKX2-1 transcription factor controls regional identity and, with LHX6, is necessary to specify pallidal projection neurons and forebrain interneurons. Here, we dissected the molecular functions of NKX2-1 by defining its chromosomal binding, regulation of gene expression, and epigenetic state. NKX2-1 binding at distal regulatory elements led to a repressed epigenetic state and transcriptional repression in the ventricular zone. Conversely, NKX2-1 is required to establish a permissive chromatin state and transcriptional activation in the sub-ventricular and mantle zones. Moreover, combinatorial binding of NKX2-1 and LHX6 promotes transcriptionally permissive chromatin and activates genes expressed in cortical migrating interneurons. Our integrated approach provides a foundation for elucidating transcriptional networks guiding the development of the MGE and its descendants. PMID:27657450

  3. β-Hydroxybutyrate is the preferred substrate for GABA and glutamate synthesis while glucose is indispensable during depolarization in cultured GABAergic neurons.

    PubMed

    Lund, Trine M; Obel, Linea F; Risa, Øystein; Sonnewald, Ursula

    2011-08-01

    The ketogenic diet has multiple beneficial effects not only in treatment of epilepsy, but also in that of glucose transporter 1 deficiency, cancer, Parkinson's disease, obesity and pain. Thus, there is an increasing interest in understanding the mechanism behind this metabolic therapy. Patients on a ketogenic diet reach high plasma levels of ketone bodies, which are used by the brain as energy substrates. The interaction between glucose and ketone bodies is complex and there is still controversy as to what extent it affects the homeostasis of the neurotransmitters glutamate, aspartate and GABA. The present study was conducted to study this metabolic interaction in cultured GABAergic neurons exposed to different combinations of (13)C-labeled and unlabeled glucose and β-hydroxybutyrate. Depolarization was induced and the incorporation of (13)C into glutamate, GABA and aspartate was analyzed. The presence of β-hydroxybutyrate together with glucose did not affect the total GABA content but did, however, decrease the aspartate content to a lower value than when either glucose or β-hydroxybutyrate was employed alone. When combinations of the two substrates were used (13)C-atoms from β-hydroxybutyrate were found in all three amino acids to a greater extent than (13)C-atoms from glucose, but only the (13)C contribution from [1,6-(13)C]glucose increased upon depolarization. In conclusion, β-hydroxybutyrate was preferred over glucose as substrate for amino acid synthesis but the total content of aspartate decreased when both substrates were present. Furthermore only the use of glucose increased upon depolarization. PMID:21684314

  4. Differential inhibitory control of semicircular canal nerve afferent-evoked inputs in second-order vestibular neurons by glycinergic and GABAergic circuits.

    PubMed

    Biesdorf, Stefan; Malinvaud, David; Reichenberger, Ingrid; Pfanzelt, Sandra; Straka, Hans

    2008-04-01

    Labyrinthine nerve-evoked monosynaptic excitatory postsynaptic potentials (EPSPs) in second-order vestibular neurons (2 degrees VN) sum with disynaptic inhibitory postsynaptic potentials (IPSPs) that originate from the thickest afferent fibers of the same nerve branch and are mediated by neurons in the ipsilateral vestibular nucleus. Pharmacological properties of the inhibition and the interaction with the afferent excitation were studied by recording monosynaptic responses of phasic and tonic 2 degrees VN in an isolated frog brain after electrical stimulation of individual semicircular canal nerves. Specific transmitter antagonists revealed glycine and GABA(A) receptor-mediated IPSPs with a disynaptic onset only in phasic but not in tonic 2 degrees VN. Compared with GABAergic IPSPs, glycinergic responses in phasic 2 degrees VN have larger amplitudes and a longer duration and reduce early and late components of the afferent nerve-evoked subthreshold activation and spike discharge. The difference in profile of the disynaptic glycinergic and GABAergic inhibition is compatible with the larger number of glycinergic as opposed to GABAergic terminal-like structures on 2 degrees VN. The increase in monosynaptic excitation after a block of the disynaptic inhibition in phasic 2 degrees VN is in part mediated by a N-methyl-d-aspartate receptor-activated component. Although inhibitory inputs were superimposed on monosynaptic EPSPs in tonic 2 degrees VN as well, the much longer latency of these IPSPs excludes a control by short-latency inhibitory feed-forward side-loops as observed in phasic 2 degrees VN. The differential synaptic organization of the inhibitory control of labyrinthine afferent signals in phasic and tonic 2 degrees VN is consistent with the different intrinsic signal processing modes of the two neuronal types and suggests a co-adaptation of intrinsic membrane properties and emerging network properties. PMID:18256163

  5. Development and specification of GABAergic cortical interneurons

    PubMed Central

    2013-01-01

    GABAergic interneurons are inhibitory neurons of the nervous system that play a vital role in neural circuitry and activity. They are so named due to their release of the neurotransmitter gamma-aminobutyric acid (GABA), and occupy different areas of the brain. This review will focus primarily on GABAergic interneurons of the mammalian cerebral cortex from a developmental standpoint. There is a diverse amount of cortical interneuronal subtypes that may be categorized by a number of characteristics; this review will classify them largely by the protein markers they express. The developmental origins of GABAergic interneurons will be discussed, as well as factors that influence the complex migration routes that these interneurons must take in order to ultimately localize in the cerebral cortex where they will integrate with the neural circuitry set in place. This review will also place an emphasis on the transcriptional network of genes that play a role in the specification and maintenance of GABAergic interneuron fate. Gaining an understanding of the different aspects of cortical interneuron development and specification, especially in humans, has many useful clinical applications that may serve to treat various neurological disorders linked to alterations in interneuron populations. PMID:23618463

  6. Isolation Rearing Reduces Neuronal Excitability in Dentate Gyrus Granule Cells of Adolescent C57BL/6J Mice: Role of GABAergic Tonic Currents and Neurosteroids.

    PubMed

    Talani, Giuseppe; Biggio, Francesca; Licheri, Valentina; Locci, Valentina; Biggio, Giovanni; Sanna, Enrico

    2016-01-01

    Early-life exposure to stress, by impacting on a brain still under development, is considered a critical factor for the increased vulnerability to psychiatric disorders and abuse of psychotropic substances during adulthood. As previously reported, rearing C57BL/6J weanling mice in social isolation (SI) from their peers for several weeks, a model of prolonged stress, is associated with a decreased plasma and brain levels of neuroactive steroids such as 3α,5α-THP, with a parallel up-regulation of extrasynaptic GABAA receptors (GABAAR) in dentate gyrus (DG) granule cells compared to group-housed (GH) mice. In the present study, together with the SI-induced decrease in plasma concentration of both progesterone and 3α,5α-THP, and an increase in THIP-stimulated GABAergic tonic currents, patch-clamp analysis of DG granule cells revealed a significant decrease in membrane input resistance and action potential (AP) firing rate, in SI compared to GH mice, suggesting that SI exerts an inhibitory action on neuronal excitability of these neurons. Voltage-clamp recordings of glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs) revealed a SI-associated decrease in frequency as well as a shift from paired-pulse (PP) depression to PP facilitation (PPF) of evoked EPSCs, indicative of a reduced probability of glutamate release. Daily administration of progesterone during isolation reverted the changes in plasma 3α,5α-THP as well as in GABAergic tonic currents and neuronal excitability caused by SI, but it had only a limited effect on the changes in the probability of presynaptic glutamate release. Overall, the results obtained in this work, together with those previously published, indicate that exposure of mice to SI during adolescence reduces neuronal excitability of DG granule cells, an effect that may be linked to the increased GABAergic tonic currents as a consequence of the sustained decrease in plasma and hippocampal levels of neurosteroids. All these

  7. Isolation Rearing Reduces Neuronal Excitability in Dentate Gyrus Granule Cells of Adolescent C57BL/6J Mice: Role of GABAergic Tonic Currents and Neurosteroids

    PubMed Central

    Talani, Giuseppe; Biggio, Francesca; Licheri, Valentina; Locci, Valentina; Biggio, Giovanni; Sanna, Enrico

    2016-01-01

    Early-life exposure to stress, by impacting on a brain still under development, is considered a critical factor for the increased vulnerability to psychiatric disorders and abuse of psychotropic substances during adulthood. As previously reported, rearing C57BL/6J weanling mice in social isolation (SI) from their peers for several weeks, a model of prolonged stress, is associated with a decreased plasma and brain levels of neuroactive steroids such as 3α,5α-THP, with a parallel up-regulation of extrasynaptic GABAA receptors (GABAAR) in dentate gyrus (DG) granule cells compared to group-housed (GH) mice. In the present study, together with the SI-induced decrease in plasma concentration of both progesterone and 3α,5α-THP, and an increase in THIP-stimulated GABAergic tonic currents, patch-clamp analysis of DG granule cells revealed a significant decrease in membrane input resistance and action potential (AP) firing rate, in SI compared to GH mice, suggesting that SI exerts an inhibitory action on neuronal excitability of these neurons. Voltage-clamp recordings of glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs) revealed a SI-associated decrease in frequency as well as a shift from paired-pulse (PP) depression to PP facilitation (PPF) of evoked EPSCs, indicative of a reduced probability of glutamate release. Daily administration of progesterone during isolation reverted the changes in plasma 3α,5α-THP as well as in GABAergic tonic currents and neuronal excitability caused by SI, but it had only a limited effect on the changes in the probability of presynaptic glutamate release. Overall, the results obtained in this work, together with those previously published, indicate that exposure of mice to SI during adolescence reduces neuronal excitability of DG granule cells, an effect that may be linked to the increased GABAergic tonic currents as a consequence of the sustained decrease in plasma and hippocampal levels of neurosteroids. All these

  8. Isolation Rearing Reduces Neuronal Excitability in Dentate Gyrus Granule Cells of Adolescent C57BL/6J Mice: Role of GABAergic Tonic Currents and Neurosteroids.

    PubMed

    Talani, Giuseppe; Biggio, Francesca; Licheri, Valentina; Locci, Valentina; Biggio, Giovanni; Sanna, Enrico

    2016-01-01

    Early-life exposure to stress, by impacting on a brain still under development, is considered a critical factor for the increased vulnerability to psychiatric disorders and abuse of psychotropic substances during adulthood. As previously reported, rearing C57BL/6J weanling mice in social isolation (SI) from their peers for several weeks, a model of prolonged stress, is associated with a decreased plasma and brain levels of neuroactive steroids such as 3α,5α-THP, with a parallel up-regulation of extrasynaptic GABAA receptors (GABAAR) in dentate gyrus (DG) granule cells compared to group-housed (GH) mice. In the present study, together with the SI-induced decrease in plasma concentration of both progesterone and 3α,5α-THP, and an increase in THIP-stimulated GABAergic tonic currents, patch-clamp analysis of DG granule cells revealed a significant decrease in membrane input resistance and action potential (AP) firing rate, in SI compared to GH mice, suggesting that SI exerts an inhibitory action on neuronal excitability of these neurons. Voltage-clamp recordings of glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs) revealed a SI-associated decrease in frequency as well as a shift from paired-pulse (PP) depression to PP facilitation (PPF) of evoked EPSCs, indicative of a reduced probability of glutamate release. Daily administration of progesterone during isolation reverted the changes in plasma 3α,5α-THP as well as in GABAergic tonic currents and neuronal excitability caused by SI, but it had only a limited effect on the changes in the probability of presynaptic glutamate release. Overall, the results obtained in this work, together with those previously published, indicate that exposure of mice to SI during adolescence reduces neuronal excitability of DG granule cells, an effect that may be linked to the increased GABAergic tonic currents as a consequence of the sustained decrease in plasma and hippocampal levels of neurosteroids. All these

  9. Fatty acids increase neuronal hypertrophy of Pten knockdown neurons

    PubMed Central

    Fricano, Catherine J.; DeSpenza, Tyrone; Frazel, Paul W.; Li, Meijie; O'Malley, A. James; Westbrook, Gary L.; Luikart, Bryan W.

    2014-01-01

    Phosphatase and tensin homolog (Pten) catalyzes the reverse reaction of PI3K by dephosphorylating PIP3 to PIP2. This negatively regulates downstream Akt/mTOR/S6 signaling resulting in decreased cellular growth and proliferation. Co-injection of a lentivirus knocking Pten down with a control lentivirus allows us to compare the effects of Pten knockdown between individual neurons within the same animal. We find that knockdown of Pten results in neuronal hypertrophy by 21 days post-injection. This neuronal hypertrophy is correlated with increased p-S6 and p-mTOR in individual neurons. We used this system to test whether an environmental factor that has been implicated in cellular hypertrophy could influence the severity of the Pten knockdown-induced hypertrophy. Implantation of mini-osmotic pumps delivering fatty acids results in increased neuronal hypertrophy and p-S6/p-mTOR staining. These hypertrophic effects were reversed in response to rapamycin treatment. However, we did not observe a similar increase in hypertrophy in response to dietary manipulations of fatty acids. Thus, we conclude that by driving growth signaling with fatty acids and knocking down a critical regulator of growth, Pten, we are able to observe an additive morphological phenotype of increased soma size mediated by the mTOR pathway. PMID:24795563

  10. GABAergic synapses: their plasticity and role in sensory cortex

    PubMed Central

    Griffen, Trevor C.; Maffei, Arianna

    2014-01-01

    The mammalian neocortex is composed of a variety of cell types organized in a highly interconnected circuit. GABAergic neurons account for only about 20% of cortical neurons. However, they show widespread connectivity and a high degree of diversity in morphology, location, electrophysiological properties and gene expression. In addition, distinct populations of inhibitory neurons have different sensory response properties, capacities for plasticity and sensitivities to changes in sensory experience. In this review we summarize experimental evidence regarding the properties of GABAergic neurons in primary sensory cortex. We will discuss how distinct GABAergic neurons and different forms of GABAergic inhibitory plasticity may contribute to shaping sensory cortical circuit activity and function. PMID:24723851

  11. A novel GABAergic afferent input to the pontine reticular formation: the mesopontine GABAergic column.

    PubMed

    Liang, Chang-Lin; Marks, Gerald A

    2009-11-10

    Pharmacological manipulations of gamma-aminobutyric acid (GABA) neurotransmission in the nucleus pontis oralis (PnO) of the rat brainstem produce alterations in sleep/wake behavior. Local applications of GABA(A) receptor antagonists and agonists increase REM sleep and wake, respectively. These findings support a role for GABAergic mechanisms of the PnO in the control of arousal state. We have been investigating sources of GABA innervation of the PnO that may interact with local GABA(A) receptors in the control of state. Utilizing a retrograde tracer, cholera toxin-B subunit (CTb), injected into the PnO and dual-label immunohistochemistry with an antibody against glutamic acid decarboxalase-67 (GAD67), we report on a previously unidentified GABAergic neuronal population projecting to the contralateral PnO appearing as a column of cells, with long-axis in the sagittal plane, extending through the midbrain and pons. We refer to these neurons as the mesopontine GABAergic column (MPGC). The contiguous, columnar, anatomical distribution suggests operation as a functional neural system, which may influence expression of REM sleep, wake and other behaviors subserved by the PnO.

  12. Early GABAergic circuitry in the cerebral cortex.

    PubMed

    Luhmann, Heiko J; Kirischuk, Sergei; Sinning, Anne; Kilb, Werner

    2014-06-01

    In the cerebral cortex GABAergic signaling plays an important role in regulating early developmental processes, for example, neurogenesis, migration and differentiation. Transient cell populations, namely Cajal-Retzius in the marginal zone and thalamic input receiving subplate neurons, are integrated as active elements in transitory GABAergic circuits. Although immature pyramidal neurons receive GABAergic synaptic inputs already at fetal stages, they are integrated into functional GABAergic circuits only several days later. In consequence, GABAergic synaptic transmission has only a minor influence on spontaneous network activity during early corticogenesis. Concurrent with the gradual developmental shift of GABA action from excitatory to inhibitory and the maturation of cortical synaptic connections, GABA becomes more important in synchronizing neuronal network activity.

  13. GABAergic dysfunction mediates autism-like stereotypies and Rett syndrome phenotypes

    PubMed Central

    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.

    2010-01-01

    Summary Mutations in the X-linked MECP2, which encodes the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2) cause Rett syndrome (RTT) and several neurodevelopmental disorders including cognitive disorders, autism, juvenile-onset schizophrenia, and encephalopathy with early lethality. RTT is characterized by apparently normal early development followed by regression, motor abnormalities, seizures, and features of autism, especially stereotyped behaviors. The mechanisms mediating these striking features are poorly understood. Here we show that mice lacking Mecp2 from γ-amino-butyric-acid-(GABA)-ergic neurons recapitulate numerous RTT and autistic features, including repetitive behaviors. Loss of MeCP2 from a subset of forebrain GABAergic neurons also recapitulates many features of RTT. MeCP2-deficient GABAergic neurons show reduced inhibitory quantal size consistent with presynaptic reduction in glutamic acid decarboxylase-1 and -2 levels and GABA immunoreactivity. These data demonstrate that MeCP2 is critical for normal GABAergic neuronal function and that subtle dysfunction of GABAergic neurons contributes to numerous neuropsychiatric phenotypes. PMID:21068835

  14. Chronically reinforced, operant olfactory conditioning increases the number of newborn GABAergic olfactory periglomerular neurons in the adult rat.

    PubMed

    Tapia-Rodríguez, Miguel; Esquivelzeta-Rabell, José F; Gutiérrez-Ospina, Gabriel

    2012-12-01

    The mammalian brain preserves the ability to replace olfactory periglomerular cells (PGC) throughout life. Even though we have detailed a great deal the mechanisms underlying stem and amplifying cells maintenance and proliferation, as well as those modulating migration and differentiation, our knowledge on PGC phenotypic plasticity is at best fragmented and controversial. Here we explored whether chronically reinforced olfactory conditioning influences the phenotype of newborn PGC. Accordingly, olfactory conditioned rats showed increased numbers of GAD 65/67 positive PGC. Because such phenotypic change was not accompanied neither by increments in the total number of PGC, or periglomerular cell nuclei labeled with bromodeoxyuridine, nor by reductions in the number of tyrosine hydroxylase (TH), calbindin (CB) or calretinin (CR) immunoreactive PGC, we speculate that increments in the number of GABAergic PGC occur at the expense of other PGC phenotypes. In any event, these results support that adult newborn PGC phenotype may be subjected to phenotypic plasticity influenced by sensory stimulation.

  15. The membrane estrogen receptor ligand STX rapidly enhances GABAergic signaling in NPY/AgRP neurons: role in mediating the anorexigenic effects of 17β-estradiol.

    PubMed

    Smith, A W; Bosch, M A; Wagner, E J; Rønnekleiv, O K; Kelly, M J

    2013-09-01

    Besides its quintessential role in reproduction, 17β-estradiol (E2) is a potent anorexigenic hormone. E2 and the selective Gq-coupled membrane estrogen receptor (Gq-mER) ligand STX rapidly increase membrane excitability in proopiomelanocortin (POMC) neurons by desensitizing the coupling of GABAB receptors to G protein-coupled inwardly rectifying K(+) channels (GIRKs), which upon activation elicit a hyperpolarizing outward current. However, it is unknown whether E2 and STX can modulate GABAB signaling in neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons. We used single-cell RT-PCR and whole cell patch clamping with selective pharmacological reagents to show that NPY/AgRP cells of mice express the GABAB-R1 and -R2 receptors and are hyperpolarized by the GABAB agonist baclofen in an E2-dependent manner. In males, E2 rapidly attenuated the coupling of GABAB receptors to GIRKs, which was blocked by the general PI3K inhibitors wortmannin and LY-294002 or the selective p110β subunit inhibitor TGX-221. The ERα-selective agonist propyl pyrazole triol mimicked the effects of E2. STX, in contrast, enhanced the GABAB response in males, which was abrogated by the estrogen receptor (ER) antagonist ICI 182,780. In gonadectomized mice of both sexes, E2 enhanced or attenuated the GABAB response in different NPY/AgRP cells. Coperfusing wortmannin with E2 or simply applying STX always enhanced the GABAB response. Thus, in NPY/AgRP neurons, activation of the Gq-mER by E2 or STX enhances the GABAergic postsynaptic response, whereas activation of ERα by E2 attenuates it. These findings demonstrate a clear functional dichotomy of rapid E2 membrane-initiated signaling via ERα vs. Gq-mER in a CNS neuron vital for regulating energy homeostasis.

  16. Shaping inhibition: activity dependent structural plasticity of GABAergic synapses

    PubMed Central

    Flores, Carmen E.; Méndez, Pablo

    2014-01-01

    Inhibitory transmission through the neurotransmitter γ-aminobutyric acid (GABA) shapes network activity in the mammalian cerebral cortex by filtering synaptic incoming information and dictating the activity of principal cells. The incredibly diverse population of cortical neurons that use GABA as neurotransmitter shows an equally diverse range of mechanisms that regulate changes in the strength of GABAergic synaptic transmission and allow them to dynamically follow and command the activity of neuronal ensembles. Similarly to glutamatergic synaptic transmission, activity-dependent functional changes in inhibitory neurotransmission are accompanied by alterations in GABAergic synapse structure that range from morphological reorganization of postsynaptic density to de novo formation and elimination of inhibitory contacts. Here we review several aspects of structural plasticity of inhibitory synapses, including its induction by different forms of neuronal activity, behavioral and sensory experience and the molecular mechanisms and signaling pathways involved. We discuss the functional consequences of GABAergic synapse structural plasticity for information processing and memory formation in view of the heterogenous nature of the structural plasticity phenomena affecting inhibitory synapses impinging on somatic and dendritic compartments of cortical and hippocampal neurons. PMID:25386117

  17. Shaping inhibition: activity dependent structural plasticity of GABAergic synapses.

    PubMed

    Flores, Carmen E; Méndez, Pablo

    2014-01-01

    Inhibitory transmission through the neurotransmitter γ-aminobutyric acid (GABA) shapes network activity in the mammalian cerebral cortex by filtering synaptic incoming information and dictating the activity of principal cells. The incredibly diverse population of cortical neurons that use GABA as neurotransmitter shows an equally diverse range of mechanisms that regulate changes in the strength of GABAergic synaptic transmission and allow them to dynamically follow and command the activity of neuronal ensembles. Similarly to glutamatergic synaptic transmission, activity-dependent functional changes in inhibitory neurotransmission are accompanied by alterations in GABAergic synapse structure that range from morphological reorganization of postsynaptic density to de novo formation and elimination of inhibitory contacts. Here we review several aspects of structural plasticity of inhibitory synapses, including its induction by different forms of neuronal activity, behavioral and sensory experience and the molecular mechanisms and signaling pathways involved. We discuss the functional consequences of GABAergic synapse structural plasticity for information processing and memory formation in view of the heterogenous nature of the structural plasticity phenomena affecting inhibitory synapses impinging on somatic and dendritic compartments of cortical and hippocampal neurons. PMID:25386117

  18. Seasonal induction of GABAergic excitation in the central mammalian clock

    PubMed Central

    Farajnia, Sahar; van Westering, Tirsa L. E.; Meijer, Johanna H.; Michel, Stephan

    2014-01-01

    The balance between excitation and inhibition is essential for the proper function of neuronal networks in the brain. The inhibitory neurotransmitter γ-aminobutyric acid (GABA) contributes to the network dynamics within the suprachiasmatic nucleus (SCN), which is involved in seasonal encoding. We investigated GABAergic activity and observed mainly inhibitory action in SCN neurons of mice exposed to a short-day photoperiod. Remarkably, the GABAergic activity in a long-day photoperiod shifts from inhibition toward excitation. The mechanistic basis for this appears to be a change in the equilibrium potential of GABA-evoked current. These results emphasize that environmental conditions can have substantial effects on the function of a key neurotransmitter in the central nervous system. PMID:24979761

  19. An extrasynaptic GABAergic signal modulates a pattern of forward movement in Caenorhabditis elegans

    PubMed Central

    Shen, Yu; Wen, Quan; Liu, He; Zhong, Connie; Qin, Yuqi; Harris, Gareth; Kawano, Taizo; Wu, Min; Xu, Tianqi; Samuel, Aravinthan DT; Zhang, Yun

    2016-01-01

    As a common neurotransmitter in the nervous system, γ-aminobutyric acid (GABA) modulates locomotory patterns in both vertebrates and invertebrates. However, the signaling mechanisms underlying the behavioral effects of GABAergic modulation are not completely understood. Here, we demonstrate that a GABAergic signal in C. elegans modulates the amplitude of undulatory head bending through extrasynaptic neurotransmission and conserved metabotropic receptors. We show that the GABAergic RME head motor neurons generate undulatory activity patterns that correlate with head bending and the activity of RME causally links with head bending amplitude. The undulatory activity of RME is regulated by a pair of cholinergic head motor neurons SMD, which facilitate head bending, and inhibits SMD to limit head bending. The extrasynaptic neurotransmission between SMD and RME provides a gain control system to set head bending amplitude to a value correlated with optimal efficiency of forward movement. DOI: http://dx.doi.org/10.7554/eLife.14197.001 PMID:27138642

  20. Subclass-specific formation of perineuronal nets around parvalbumin-expressing GABAergic neurons in Ammon's horn of the mouse hippocampus.

    PubMed

    Yamada, Jun; Jinno, Shozo

    2015-04-01

    Perineuronal nets (PNNs) are closely associated with parvalbumin-positive (PV+) neurons, and play a major role in controlling developmental neural plasticity. Considering the recent advances in classification of PV+ neurons, here we aimed to clarify whether PNNs might be associated with specific subclasses of PV+ neurons in the hippocampus. In this study, we labeled PNNs by Wisteria floribunda agglutinin (WFA), and classified PV+ neurons based on the combination of cellular location, molecular expression (neuropeptide Y [NPY], somatostatin [SOM], special AT-rich sequence-binding protein-1 [SATB1]), and retrograde tracing through stereotaxic injection of Fluoro-Gold (FG) into the medial septum. The criteria of each subclass can be summarized as follows: axo-axonic cells, PV+/SATB1-/NPY- cells in the stratum pyramidale; basket cells, PV+/SATB1+/NPY- cells in the stratum pyramidale; bistratified cells, PV+/SATB1+/NPY+ cells in the stratum pyramidale; oriens-lacunosum-moleculare (O-LM) cells, PV+/SOM+/FG- cells in the stratum oriens; hippocampo-septal projection (H-S) cells, and PV+/SOM+/FG+ cells in the stratum oriens. The ratios of formation of WFA+ PNNs around each subclass of PV+ neurons were estimated according to the optical disector principle. The vast majority (over 90%) of putative PV+ basket cells were surrounded by PNNs, while only a minor population (less than 10%) of putative PV+ axo-axonic, O-LM, and H-S cells were enwrapped with PNNs. The ratios of formation of PNNs around putative PV+ bistratified cells were intermediate (25-50%). These findings indicate that PNNs may be specifically associated with PV+ basket cells, and also provide a key to understand the functional significance of PNNs and PV+ neurons in the hippocampus.

  1. Ursolic acid enhances pentobarbital-induced sleeping behaviors via GABAergic neurotransmission in mice.

    PubMed

    Jeon, Se Jin; Park, Ho Jae; Gao, Qingtao; Pena, Irene Joy Dela; Park, Se Jin; Lee, Hyung Eun; Woo, Hyun; Kim, Hee Jin; Cheong, Jae Hoon; Hong, Eunyoung; Ryu, Jong Hoon

    2015-09-01

    Prunella vulgaris is widely used as a herbal medicine for cancers, inflammatory diseases, and other infections. Although it has long been used, few studies have examined its effects on central nervous system function. Here, we first observed that ethanolic extracts of P. vulgaris (EEPV) prolonged pentobarbital-induced sleep duration in mice. It is known that EEPV consists of many active components including triterpenoid (ursolic acid and oleanolic acid), which have many biological activities. Therefore, we evaluated which EEPV components induced sleep extension in pentobarbital-mediated sleeping model in mice. Surprisingly, despite their structural similarity and other common functions such as anti-inflammation, anti-cancer, and tissue protection, only ursolic acid enhanced sleep duration in pentobarbital-treated mice. These results were attenuated by bicuculline treatment, which is a GABAA receptor antagonist. The present results suggest that ursolic acid from P. vulgaris enhances sleep duration through GABAA receptor activation and could be a therapeutic candidate for insomnia treatment.

  2. Taurine activates GABAergic networks in the neocortex of immature mice

    PubMed Central

    Sava, Bogdan A.; Chen, Rongqing; Sun, Haiyan; Luhmann, Heiko J.; Kilb, Werner

    2014-01-01

    Although it has been suggested that taurine is the main endogenous neurotransmitter acting on glycine receptors, the implications of glycine receptor-mediated taurine actions on immature neocortical networks have not been addressed yet. To investigate the influence of taurine on the excitability of neuronal networks in the immature neocortex, we performed whole-cell patch-clamp recordings from visually identified pyramidal neurons and interneurons in coronal slices from C57Bl/6 and GAD67-green fluorescent protein (GFP) transgenic mice (postnatal days 2–4). In 46% of the pyramidal neurons bath-application of taurine at concentrations ≥ 300 μM significantly enhanced the frequency of postsynaptic currents (PSCs) by 744.3 ± 93.8% (n = 120 cells). This taurine-induced increase of PSC frequency was abolished by 0.2 μM tetrodotoxin (TTX), 1 μM strychnine or 3 μM gabazine, but was unaffected by the glutamatergic antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and (±) R(-)-3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP), suggesting that taurine specifically activates GABAergic network activity projecting to pyramidal neurons. Cell-attached recordings revealed that taurine enhanced the frequency of action potentials (APs) in pyramidal neurons, indicating an excitatory action of the GABAergic PSCs. In order to identify the presynaptic targets of taurine we demonstrate that bath application of taurine induced in GAD67-GFP labeled interneurons an inward current that is mainly mediated by glycine receptors and can generate APs in these cells. We conclude from these results that taurine can enhance network excitability in the immature neocortex by selectively activating GABAergic interneurons via interactions with glycine receptors. PMID:24550782

  3. Glutamatergic and GABAergic energy metabolism measured in the rat brain by (13) C NMR spectroscopy at 14.1 T.

    PubMed

    Duarte, João M N; Gruetter, Rolf

    2013-09-01

    Energy metabolism supports both inhibitory and excitatory neurotransmission processes. This study investigated the specific contribution of astrocytic metabolism to γ-aminobutyric acid (GABA) synthesis and inhibitory GABAergic neurotransmission that remained to be ilucidated in vivo. Therefore, we measured (13)C incorporation into brain metabolites by dynamic (13)C nuclear magnetic resonance spectroscopy at 14.1 T in rats under α-chloralose anaesthesia during infusion of [1,6-(13)C]glucose. The enhanced sensitivity at 14.1 T allowed to quantify incorporation of (13) C into the three aliphatic carbons of GABA non-invasively. Metabolic fluxes were determined with a mathematical model of brain metabolism comprising glial, glutamatergic and GABAergic compartments. GABA synthesis rate was 0.11 ± 0.01 μmol/g/min. GABA-glutamine cycle was 0.053 ± 0.003 μmol/g/min and accounted for 22 ± 1% of total neurotransmitter cycling between neurons and glia. Cerebral glucose oxidation was 0.47 ± 0.02 μmol/g/min, of which 35 ± 1% and 7 ± 1% was diverted to the glutamatergic and GABAergic tricarboxylic acid cycles, respectively. The remaining fraction of glucose oxidation was in glia, where 12 ± 1% of the TCA cycle flux was dedicated to oxidation of GABA. 16 ± 2% of glutamine synthesis was provided to GABAergic neurons. We conclude that substantial metabolic activity occurs in GABAergic neurons and that glial metabolism supports both glutamatergic and GABAergic neurons in the living rat brain. PMID:23745684

  4. Initial loss but later excess of GABAergic synapses with dentate granule cells in a rat model of temporal lobe epilepsy.

    PubMed

    Thind, Khushdev K; Yamawaki, Ruth; Phanwar, Ibanri; Zhang, Guofeng; Wen, Xiling; Buckmaster, Paul S

    2010-03-01

    Many patients with temporal lobe epilepsy display neuron loss in the dentate gyrus. One potential epileptogenic mechanism is loss of GABAergic interneurons and inhibitory synapses with granule cells. Stereological techniques were used to estimate numbers of gephyrin-positive punctae in the dentate gyrus, which were reduced short-term (5 days after pilocarpine-induced status epilepticus) but later rebounded beyond controls in epileptic rats. Stereological techniques were used to estimate numbers of synapses in electron micrographs of serial sections processed for postembedding GABA-immunoreactivity. Adjacent sections were used to estimate numbers of granule cells and glutamic acid decarboxylase-positive neurons per dentate gyrus. GABAergic neurons were reduced to 70% of control levels short-term, where they remained in epileptic rats. Integrating synapse and cell counts yielded average numbers of GABAergic synapses per granule cell, which decreased short-term and rebounded in epileptic animals beyond control levels. Axo-shaft and axo-spinous GABAergic synapse numbers in the outer molecular layer changed most. These findings suggest interneuron loss initially reduces numbers of GABAergic synapses with granule cells, but later, synaptogenesis by surviving interneurons overshoots control levels. In contrast, the average number of excitatory synapses per granule cell decreased short-term but recovered only toward control levels, although in epileptic rats excitatory synapses in the inner molecular layer were larger than in controls. These findings reveal a relative excess of GABAergic synapses and suggest that reports of reduced functional inhibitory synaptic input to granule cells in epilepsy might be attributable not to fewer but instead to abundant but dysfunctional GABAergic synapses.

  5. Regional Differentiation of Retinoic Acid-Induced Human Pluripotent Embryonic Carcinoma Stem Cell Neurons

    PubMed Central

    Coyle, Dennis E.; Li, Jie; Baccei, Mark

    2011-01-01

    The NTERA2 cl D1 (NT2) cell line, derived from human teratocarcinoma, exhibits similar properties as embryonic stem (ES) cells or very early neuroepitheial progenitors. NT2 cells can be induced to become postmitotic central nervous system neurons (NT2N) with retinoic acid. Although neurons derived from pluripotent cells, such as NT2N, have been characterized for their neurotransmitter phenotypes, their potential suitability as a donor source for neural transplantation also depends on their ability to respond to localized environmental cues from a specific region of the CNS. Therefore, our study aimed to characterize the regional transcription factors that define the rostocaudal and dorsoventral identity of NT2N derived from a monolayer differentiation paradigm using quantitative PCR (qPCR). Purified NT2N mainly expressed both GABAergic and glutamatergic phenotypes and were electrically active but did not form functional synapses. The presence of immature astrocytes and possible radial glial cells was noted. The NT2N expressed a regional transcription factor code consistent with forebrain, hindbrain and spinal cord neural progenitors but showed minimal expression of midbrain phenotypes. In the dorsoventral plane NT2N expressed both dorsal and ventral neural progenitors. Of major interest was that even under the influence of retinoic acid, a known caudalization factor, the NT2N population maintained a rostral phenotype subpopulation which expressed cortical regional transcription factors. It is proposed that understanding the regional differentiation bias of neurons derived from pluripotent stem cells will facilitate their successful integration into existing neuronal networks within the CNS. PMID:21283767

  6. GABAergic transmission in the rat paraventricular nucleus of the hypothalamus is suppressed by corticosterone and stress.

    PubMed

    Verkuyl, J Martin; Karst, Henk; Joëls, Marian

    2005-01-01

    Parvocellular neurons in the hypothalamic paraventricular nucleus receive hormonal inputs mediated by corticosterone as well as neuronal inputs, prominent among which is a GABAergic inhibitory projection. In the present study we examined the functional properties of this GABAergic innervation when corticosteroid levels fluctuate. Frequency, amplitude and kinetic properties of miniature inhibitory postsynaptic potentials (mIPSCs), mediated by gamma amino butyric acid (GABA) were studied with whole cell recording in parvocellular neurons. Injection of a high dose of corticosterone in vivo suppressed the frequency but did not change the amplitude and kinetic properties of mIPSCs recorded 1-5 h later in vitro. Similar effects were observed after restraint stress. The corticosteroid actions do not require involvement of extrahypothalamic brain regions, because in vitro administration of 100 nM corticosterone (20 min) directly to a hypothalamic slice also suppressed the frequency of mIPSCs recorded several hours later. Corticosterone administration to hypothalamic slices from restraint rats did not result in stronger reduction of mIPSC frequency than either treatment alone, pointing to a common underlying mechanism. Paired pulse response inhibition was reduced by corticosterone, suggesting that the hormone decreases the release probability of GABA-containing vesicles. Unlike neurosteroids, corticosterone induced no rapid effects on mIPSC properties. These results indicate that increases in glucocorticoid level due to stress can slowly but persistently inhibit the GABAergic tone on parvocellular hypothalamic neurons via a hitherto unknown local mechanism independent of limbic projections.

  7. Lysophosphatidic acid and signaling in sensory neurons.

    PubMed

    Oude Elferink, Ronald P J; Bolier, Ruth; Beuers, Ulrich H

    2015-01-01

    Lysophosphatidic acid is a potent signaling lipid molecule that has initially been characterized as a growth factor. However, later studies have revealed many more functions such as modulation of cell shape, cell migration, prevention of apoptosis, platelet aggregation, wound healing, osteoclast differentiation, vasopressor activity, embryo implantation, angiogenesis, lung fibrosis, hair growth and more. The molecule mainly acts through the activation of a set of at least 6 G-protein-coupled receptors (LPA1-6), but intracellular LPA was also shown to signal through the activation of the nuclear receptor PPARγ. In this short review we discuss the recent observations which suggest that in pathological conditions LPA also modulates signaling in sensory neurons. Thus, LPA has been shown to play a role in the initiation of neuropathic pain and, more recently, a relation was observed between increased LPA levels in the circulation and cholestatic itch. The mechanism by which this occurs remains to be elucidated. This article is part of a Special Issue entitled Linking transcription to physiology in lipodomics. PMID:25218302

  8. Nonviral Approaches for Neuronal Delivery of Nucleic Acids

    PubMed Central

    Bergen, Jamie M.; Park, In-Kyu; Horner, Philip J.

    2007-01-01

    The delivery of therapeutic nucleic acids to neurons has the potential to treat neurological disease and spinal cord injury. While select viral vectors have shown promise as gene carriers to neurons, their potential as therapeutic agents is limited by their toxicity and immunogenicity, their broad tropism, and the cost of large-scale formulation. Nonviral vectors are an attractive alternative in that they offer improved safety profiles compared to viruses, are less expensive to produce, and can be targeted to specific neuronal subpopulations. However, most nonviral vectors suffer from significantly lower transfection efficiencies than neurotropic viruses, severely limiting their utility in neuron-targeted delivery applications. To realize the potential of nonviral delivery technology in neurons, vectors must be designed to overcome a series of extra- and intracellular barriers. In this article, we describe the challenges preventing successful nonviral delivery of nucleic acids to neurons and review strategies aimed at overcoming these challenges. PMID:17932730

  9. Glucagon-Like Peptide-1 Excites Firing and Increases GABAergic Miniature Postsynaptic Currents (mPSCs) in Gonadotropin-Releasing Hormone (GnRH) Neurons of the Male Mice via Activation of Nitric Oxide (NO) and Suppression of Endocannabinoid Signaling Pathways

    PubMed Central

    Farkas, Imre; Vastagh, Csaba; Farkas, Erzsébet; Bálint, Flóra; Skrapits, Katalin; Hrabovszky, Erik; Fekete, Csaba; Liposits, Zsolt

    2016-01-01

    Glucagon-like peptide-1 (GLP-1), a metabolic signal molecule, regulates reproduction, although, the involved molecular mechanisms have not been elucidated, yet. Therefore, responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the GLP-1 analog Exendin-4 and elucidation of molecular pathways acting downstream to the GLP-1 receptor (GLP-1R) have been challenged. Loose patch-clamp recordings revealed that Exendin-4 (100 nM–5 μM) elevated firing rate in hypothalamic GnRH-GFP neurons of male mice via activation of GLP-1R. Whole-cell patch-clamp measurements demonstrated increased excitatory GABAergic miniature postsynaptic currents (mPSCs) frequency after Exendin-4 administration, which was eliminated by the GLP-1R antagonist Exendin-3(9–39) (1 μM). Intracellular application of the G-protein inhibitor GDP-β-S (2 mM) impeded action of Exendin-4 on mPSCs, suggesting direct excitatory action of GLP-1 on GnRH neurons. Blockade of nitric-oxide (NO) synthesis by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME; 100 μM) or N5-[Imino(propylamino)methyl]-L-ornithine hydrochloride (NPLA; 1 μM) or intracellular scavenging of NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO; 1 mM) partially attenuated the excitatory effect of Exendin-4. Similar partial inhibition was achieved by hindering endocannabinoid pathway using cannabinoid receptor type-1 (CB1) inverse-agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-(1-piperidyl) pyrazole-3-carboxamide (AM251; 1 μM). Simultaneous blockade of NO and endocannabinoid signaling mechanisms eliminated action of Exendin-4 suggesting involvement of both retrograde machineries. Intracellular application of the transient receptor potential vanilloid 1 (TRPV1)-antagonist 2E-N-(2, 3-Dihydro-1,4-benzodioxin-6-yl)-3-[4-(1, 1-dimethylethyl)phenyl]-2-Propenamide (AMG9810; 10 μM) or the fatty acid amide hydrolase (FAAH)-inhibitor PF3845 (5 μM) impeded the GLP-1-triggered endocannabinoid

  10. Glucagon-Like Peptide-1 Excites Firing and Increases GABAergic Miniature Postsynaptic Currents (mPSCs) in Gonadotropin-Releasing Hormone (GnRH) Neurons of the Male Mice via Activation of Nitric Oxide (NO) and Suppression of Endocannabinoid Signaling Pathways.

    PubMed

    Farkas, Imre; Vastagh, Csaba; Farkas, Erzsébet; Bálint, Flóra; Skrapits, Katalin; Hrabovszky, Erik; Fekete, Csaba; Liposits, Zsolt

    2016-01-01

    Glucagon-like peptide-1 (GLP-1), a metabolic signal molecule, regulates reproduction, although, the involved molecular mechanisms have not been elucidated, yet. Therefore, responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the GLP-1 analog Exendin-4 and elucidation of molecular pathways acting downstream to the GLP-1 receptor (GLP-1R) have been challenged. Loose patch-clamp recordings revealed that Exendin-4 (100 nM-5 μM) elevated firing rate in hypothalamic GnRH-GFP neurons of male mice via activation of GLP-1R. Whole-cell patch-clamp measurements demonstrated increased excitatory GABAergic miniature postsynaptic currents (mPSCs) frequency after Exendin-4 administration, which was eliminated by the GLP-1R antagonist Exendin-3(9-39) (1 μM). Intracellular application of the G-protein inhibitor GDP-β-S (2 mM) impeded action of Exendin-4 on mPSCs, suggesting direct excitatory action of GLP-1 on GnRH neurons. Blockade of nitric-oxide (NO) synthesis by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME; 100 μM) or N(5)-[Imino(propylamino)methyl]-L-ornithine hydrochloride (NPLA; 1 μM) or intracellular scavenging of NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO; 1 mM) partially attenuated the excitatory effect of Exendin-4. Similar partial inhibition was achieved by hindering endocannabinoid pathway using cannabinoid receptor type-1 (CB1) inverse-agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-(1-piperidyl) pyrazole-3-carboxamide (AM251; 1 μM). Simultaneous blockade of NO and endocannabinoid signaling mechanisms eliminated action of Exendin-4 suggesting involvement of both retrograde machineries. Intracellular application of the transient receptor potential vanilloid 1 (TRPV1)-antagonist 2E-N-(2, 3-Dihydro-1,4-benzodioxin-6-yl)-3-[4-(1, 1-dimethylethyl)phenyl]-2-Propenamide (AMG9810; 10 μM) or the fatty acid amide hydrolase (FAAH)-inhibitor PF3845 (5 μM) impeded the GLP-1-triggered endocannabinoid

  11. Glucagon-Like Peptide-1 Excites Firing and Increases GABAergic Miniature Postsynaptic Currents (mPSCs) in Gonadotropin-Releasing Hormone (GnRH) Neurons of the Male Mice via Activation of Nitric Oxide (NO) and Suppression of Endocannabinoid Signaling Pathways.

    PubMed

    Farkas, Imre; Vastagh, Csaba; Farkas, Erzsébet; Bálint, Flóra; Skrapits, Katalin; Hrabovszky, Erik; Fekete, Csaba; Liposits, Zsolt

    2016-01-01

    Glucagon-like peptide-1 (GLP-1), a metabolic signal molecule, regulates reproduction, although, the involved molecular mechanisms have not been elucidated, yet. Therefore, responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the GLP-1 analog Exendin-4 and elucidation of molecular pathways acting downstream to the GLP-1 receptor (GLP-1R) have been challenged. Loose patch-clamp recordings revealed that Exendin-4 (100 nM-5 μM) elevated firing rate in hypothalamic GnRH-GFP neurons of male mice via activation of GLP-1R. Whole-cell patch-clamp measurements demonstrated increased excitatory GABAergic miniature postsynaptic currents (mPSCs) frequency after Exendin-4 administration, which was eliminated by the GLP-1R antagonist Exendin-3(9-39) (1 μM). Intracellular application of the G-protein inhibitor GDP-β-S (2 mM) impeded action of Exendin-4 on mPSCs, suggesting direct excitatory action of GLP-1 on GnRH neurons. Blockade of nitric-oxide (NO) synthesis by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME; 100 μM) or N(5)-[Imino(propylamino)methyl]-L-ornithine hydrochloride (NPLA; 1 μM) or intracellular scavenging of NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO; 1 mM) partially attenuated the excitatory effect of Exendin-4. Similar partial inhibition was achieved by hindering endocannabinoid pathway using cannabinoid receptor type-1 (CB1) inverse-agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-(1-piperidyl) pyrazole-3-carboxamide (AM251; 1 μM). Simultaneous blockade of NO and endocannabinoid signaling mechanisms eliminated action of Exendin-4 suggesting involvement of both retrograde machineries. Intracellular application of the transient receptor potential vanilloid 1 (TRPV1)-antagonist 2E-N-(2, 3-Dihydro-1,4-benzodioxin-6-yl)-3-[4-(1, 1-dimethylethyl)phenyl]-2-Propenamide (AMG9810; 10 μM) or the fatty acid amide hydrolase (FAAH)-inhibitor PF3845 (5 μM) impeded the GLP-1-triggered endocannabinoid

  12. Glucagon-Like Peptide-1 Excites Firing and Increases GABAergic Miniature Postsynaptic Currents (mPSCs) in Gonadotropin-Releasing Hormone (GnRH) Neurons of the Male Mice via Activation of Nitric Oxide (NO) and Suppression of Endocannabinoid Signaling Pathways

    PubMed Central

    Farkas, Imre; Vastagh, Csaba; Farkas, Erzsébet; Bálint, Flóra; Skrapits, Katalin; Hrabovszky, Erik; Fekete, Csaba; Liposits, Zsolt

    2016-01-01

    Glucagon-like peptide-1 (GLP-1), a metabolic signal molecule, regulates reproduction, although, the involved molecular mechanisms have not been elucidated, yet. Therefore, responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the GLP-1 analog Exendin-4 and elucidation of molecular pathways acting downstream to the GLP-1 receptor (GLP-1R) have been challenged. Loose patch-clamp recordings revealed that Exendin-4 (100 nM–5 μM) elevated firing rate in hypothalamic GnRH-GFP neurons of male mice via activation of GLP-1R. Whole-cell patch-clamp measurements demonstrated increased excitatory GABAergic miniature postsynaptic currents (mPSCs) frequency after Exendin-4 administration, which was eliminated by the GLP-1R antagonist Exendin-3(9–39) (1 μM). Intracellular application of the G-protein inhibitor GDP-β-S (2 mM) impeded action of Exendin-4 on mPSCs, suggesting direct excitatory action of GLP-1 on GnRH neurons. Blockade of nitric-oxide (NO) synthesis by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME; 100 μM) or N5-[Imino(propylamino)methyl]-L-ornithine hydrochloride (NPLA; 1 μM) or intracellular scavenging of NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO; 1 mM) partially attenuated the excitatory effect of Exendin-4. Similar partial inhibition was achieved by hindering endocannabinoid pathway using cannabinoid receptor type-1 (CB1) inverse-agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-(1-piperidyl) pyrazole-3-carboxamide (AM251; 1 μM). Simultaneous blockade of NO and endocannabinoid signaling mechanisms eliminated action of Exendin-4 suggesting involvement of both retrograde machineries. Intracellular application of the transient receptor potential vanilloid 1 (TRPV1)-antagonist 2E-N-(2, 3-Dihydro-1,4-benzodioxin-6-yl)-3-[4-(1, 1-dimethylethyl)phenyl]-2-Propenamide (AMG9810; 10 μM) or the fatty acid amide hydrolase (FAAH)-inhibitor PF3845 (5 μM) impeded the GLP-1-triggered endocannabinoid

  13. Retinoic Acid Receptor β Controls Development of Striatonigral Projection Neurons through FGF-Dependent and Meis1-Dependent Mechanisms.

    PubMed

    Rataj-Baniowska, Monika; Niewiadomska-Cimicka, Anna; Paschaki, Marie; Szyszka-Niagolov, Monika; Carramolino, Laura; Torres, Miguel; Dollé, Pascal; Krężel, Wojciech

    2015-10-28

    The mammalian striatum controls sensorimotor and psychoaffective functions through coordinated activities of its two striatonigral and striatopallidal output pathways. Here we show that retinoic acid receptor β (RARβ) controls development of a subpopulation of GABAergic, Gad65-positive striatonigral projection neurons. In Rarb(-/-) knock-out mice, concomitant reduction of Gad65, dopamine receptor D1 (Drd1), and substance P expression at different phases of prenatal development was associated with reduced number of Drd1-positive cells at birth, in contrast to normal numbers of striatopallidal projection neurons expressing dopamine receptor D2. Fate mapping using BrdU pulse-chase experiments revealed that such deficits may originate from compromised proliferation of late-born striosomal neurons and lead to decreased number of Drd1-positive cells retaining BrdU in postnatal day (P) 0 Rarb(-/-) striatum. Reduced expression of Fgf3 in the subventricular zone of the lateral ganglionic eminence (LGE) at embryonic day 13.5 may underlie such deficits by inducing premature differentiation of neuronal progenitors, as illustrated by reduced expression of the proneural gene Ascl1 (Mash1) and increased expression of Meis1, a marker of postmitotic LGE neurons. In agreement with a critical role of FGF3 in this control, reduced number of Ascl1-expressing neural progenitors, and a concomitant increase of Meis1-expressing cells, were observed in primary cell cultures of Rarb(-/-) LGE. This defect was normalized by addition of fibroblast growth factor (FGF). Such data point to role of Meis1 in striatal development, also supported by reduced neuronal differentiation in the LGE of Meis1(-/-) embryos. Our data unveil a novel mechanism of development of striatonigral projection neurons involving retinoic acid and FGF, two signals required for positioning the boundaries of Meis1-expressing cells.

  14. The effect of propofol postconditioning on the expression of K(+)-Cl(-)-co-transporter 2 in GABAergic inhibitory interneurons of acute ischemia/reperfusion injury rats.

    PubMed

    Wang, Hongbai; Liu, Shuying; Wang, Haiyun; Wang, Guolin; Zhu, Ai

    2015-02-01

    It has been shown in our previous study that propofol postconditioning enhanced the activity of phosphatidylinositol-3-kinase (PI3K) and prevented the internalization of GluR2 subunit of α-amino-3-hydroxyl-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, thus provided neuroprotection in cerebral ischemia/reperfusion (I/R) injury. Regarding inhibitory system in CNS, K(+)-Cl(-)-co-transporter 2 (KCC2), a Cl(-) extruder, plays a critical role in gamma-aminobutyric acid (GABA) inhibitory effect in mature central neurons. However, the effect of propofol postconditioning on the expression of KCC2 in GABAergic interneurons is unclear. Therefore, in this article we describe the role of KCC2 in GABAergic interneurons in the ipsilateral hippocampal CA1 region of adult rats and the effects of propofol postconditioning on this region. Herein we demonstrate that propofol postconditioning (20mg/kg/h, 2h) improved rats' neurobehavioral abilities, increased the number of survival neurons, and up-regulated neuronal KCC2 expression in glutamic acid decarboxylase 67 (GAD67) expressing GABAergic interneurons in hippocampal CA1 region at 24h after I/R. In contrast, when rats were injected with the KCC2 antagonist, [(dihydroindenyl)oxy] alkanoic acid (DIOA), the neuroprotective effects induced by propofol postconditioning were reversed. Our study indicated that propofol postconditioning increased the expression of KCC2 in inhibitory GABAergic interneurons, thus providing acute neuroprotection to rats who had undergone cerebral I/R injury.

  15. GABAergic Signaling as Therapeutic Target for Autism Spectrum Disorders

    PubMed Central

    Cellot, Giada; Cherubini, Enrico

    2014-01-01

    γ-Aminobutyric acid (GABA), the main inhibitory neurotransmitter in the adult brain, early in postnatal life exerts a depolarizing and excitatory action. This depends on accumulation of chloride inside the cell via the cation–chloride importer NKCC1, being the expression of the chloride exporter KCC2 very low at birth. The developmentally regulated expression of KCC2 results in extrusion of chloride with age and a shift of GABA from the depolarizing to the hyperpolarizing direction. The depolarizing action of GABA leads to intracellular calcium rise through voltage-dependent calcium channels and/or N-methyl-d-aspartate receptors. GABA-mediated calcium signals regulate a variety of developmental processes from cell proliferation migration, differentiation, synapse maturation, and neuronal wiring. Therefore, it is not surprising that some forms of neuro-developmental disorders such as autism spectrum disorders (ASDs) are associated with alterations of GABAergic signaling and impairment of the excitatory/inhibitory balance in selective neuronal circuits. In this review, we will discuss how changes of GABAA-mediated neurotransmission affect several forms of ASDs including the Fragile X, the Angelman, and Rett syndromes. Then, we will describe various animal models of ASDs with GABAergic dysfunctions, highlighting their behavioral deficits and the possibility to rescue them by targeting selective components of the GABAergic synapse. In particular, we will discuss how in some cases, reverting the polarity of GABA responses from the depolarizing to the hyperpolarizing direction with the diuretic bumetanide, a selective blocker of NKCC1, may have beneficial effects on ASDs, thus opening new therapeutic perspectives for the treatment of these devastating disorders. PMID:25072038

  16. GABAergic signaling as therapeutic target for autism spectrum disorders.

    PubMed

    Cellot, Giada; Cherubini, Enrico

    2014-01-01

    γ-Aminobutyric acid (GABA), the main inhibitory neurotransmitter in the adult brain, early in postnatal life exerts a depolarizing and excitatory action. This depends on accumulation of chloride inside the cell via the cation-chloride importer NKCC1, being the expression of the chloride exporter KCC2 very low at birth. The developmentally regulated expression of KCC2 results in extrusion of chloride with age and a shift of GABA from the depolarizing to the hyperpolarizing direction. The depolarizing action of GABA leads to intracellular calcium rise through voltage-dependent calcium channels and/or N-methyl-d-aspartate receptors. GABA-mediated calcium signals regulate a variety of developmental processes from cell proliferation migration, differentiation, synapse maturation, and neuronal wiring. Therefore, it is not surprising that some forms of neuro-developmental disorders such as autism spectrum disorders (ASDs) are associated with alterations of GABAergic signaling and impairment of the excitatory/inhibitory balance in selective neuronal circuits. In this review, we will discuss how changes of GABAA-mediated neurotransmission affect several forms of ASDs including the Fragile X, the Angelman, and Rett syndromes. Then, we will describe various animal models of ASDs with GABAergic dysfunctions, highlighting their behavioral deficits and the possibility to rescue them by targeting selective components of the GABAergic synapse. In particular, we will discuss how in some cases, reverting the polarity of GABA responses from the depolarizing to the hyperpolarizing direction with the diuretic bumetanide, a selective blocker of NKCC1, may have beneficial effects on ASDs, thus opening new therapeutic perspectives for the treatment of these devastating disorders. PMID:25072038

  17. A GABAergic nigrotectal pathway for coordination of drinking behavior

    PubMed Central

    Rossi, Mark A.; Li, Haofang E.; Lu, Dongye; Kim, Il Hwan; Bartholomew, Ryan A.; Gaidis, Erin; Barter, Joseph W.; Kim, Namsoo; Cai, Min Tong; Soderling, Scott H.; Yin, Henry H.

    2016-01-01

    The contribution of basal ganglia outputs to consummatory behavior remains poorly understood. We recorded from the substantia nigra pars reticulata (SNR), the major basal ganglia output nucleus, during self-initiated drinking. The firing rates of many lateral SNR neurons were time-locked to individual licks. These neurons send GABAergic projections to the deep layers of the orofacial region of the lateral tectum (superior colliculus, SC). Many tectal neurons are also time-locked to licking, but their activity is usually antiphase to that of SNR neurons, suggesting inhibitory nigrotectal projections. We used optogenetics to selectively activate the GABAergic nigrotectal afferents in the deep layers of the SC. Photo-stimulation of the nigrotectal projections transiently inhibited the activity of the lick-related tectal neurons, disrupted their licking-related oscillatory pattern, and suppressed self-initiated drinking. These results demonstrate that GABAergic nigrotectal projections play a crucial role in coordinating drinking behavior. PMID:27043290

  18. Luteinizing hormone releasing hormone (LHRH) neurons maintained in nasal explants decrease LHRH messenger ribonucleic acid levels after activation of GABA(A) receptors.

    PubMed

    Fueshko, S M; Key, S; Wray, S

    1998-06-01

    Inhibition of the LHRH system appears to play an important role in preventing precocious activation of the hypothalamic-pituitary-gonadal axis. Evidence points to gamma-aminobutyric acid (GABA) as the major negative regulator of postnatal LHRH neuronal activity. Changes in LHRH messenger RNA (mRNA) levels after alterations of GABAergic activity have been reported in vivo. However, the extent to which GABA acts directly on LHRH neurons to effect LHRH mRNA levels has been difficult to ascertain. The present work evaluates the effect of GABAergic activity, via GABA(A) receptors, on LHRH neuropeptide gene expression in LHRH neurons maintained in olfactory explants generated from E11.5 mouse embryos. These explants maintain large numbers of primary LHRH neurons that migrate from bilateral olfactory pits in a directed manner. Using in situ hybridization histochemistry and single cell analysis, we report dramatic alterations in LHRH mRNA levels. Inhibition of spontaneous synaptic activity by GABA(A) antagonists, bicuculline (10(-5) M) or picrotoxin (10(-4) M), or of electrical activity by tetrodotoxin (TTX, 10(-6) M) significantly increased LHRH mRNA levels. In contrast, LHRH mRNA levels decreased in explants cultured with the GABA(A) receptor agonist, muscimol (10(-4) M), or KCl (50 mM). The observed responses suggest that LHRH neurons possess functional pathways linking GABA(A) receptors to repression of neuropeptide gene expression and indicate that gene expression in embryonic LHRH neurons, outside the CNS, is highly responsive to alterations in neuronal activity.

  19. GABAergic agents prevent alpha-melanocyte stimulating hormone induced anxiety and anorexia in rats.

    PubMed

    Rao, T Lakshmi; Kokare, Dadasaheb M; Sarkar, Sumit; Khisti, Rahul T; Chopde, Chandrabhan T; Subhedar, Nishikant

    2003-12-01

    Alpha-melanocyte stimulating hormone (alpha-MSH) is a hypothalamic peptide believed to play a tonic inhibitory role in feeding and energy homeostasis. Systemic administration of alpha-MSH is known to produce anorexia and anxiety. Since synaptic contacts between gamma-aminobutyric acid (GABA)ergic terminals and alpha-MSH neurons in the hypothalamus have been reported, the present work was undertaken to refine our knowledge on the role of GABAergic systems in anxiety and anorexia induced by intracerebroventricular (icv) administration of alpha-MSH in rats. The anxiety was assessed by elevated plus maze, and spontaneous food consumption was monitored during dark cycle. Prior administration of diazepam and muscimol that promote the function of GABA(A) receptors reversed the anxiogenic response and decreased food intake elicited by alpha-MSH. In contrast, bicuculline, the GABA(A) receptor antagonist, not only enhanced the effects of alpha-MSH but also prevented the influence of GABAergic drugs on alpha-MSH-induced anorexia and anxiety. These findings suggest that alpha-MSH-induced anxiety and anorexia are due to its negative influence on GABAergic system.

  20. Anti-GAD65 Containing Cerebrospinal Fluid Does not Alter GABAergic Transmission

    PubMed Central

    Hackert, Jana K.; Müller, Lorenz; Rohde, Marco; Bien, Christian G.; Köhling, Rüdiger; Kirschstein, Timo

    2016-01-01

    Glutamic acid decarboxylase of 65 kDa (GAD65) antibodies have been reported in a variety of neurological disorders such as stiff-person syndrome (SPS), sporadic ataxia and some cases of epilepsy. Since the target is believed to be the cytoplasmic enzyme GAD65, the key enzyme of γ-aminobutyric acid (GABA) synthesis, the pathophysiological role of these antibodies is poorly understood. Here, we stereotactically injected human cerebrospinal fluid (CSF) containing GAD65-antibodies into the hippocampus of rats in vivo and then prepared hippocampal slices 1–2 days after post-operative recovery. We characterized both evoked and spontaneous GABAergic transmission in vitro using sharp microelectrode and patch-clamp recordings in CA1 neurons. Intracellular recordings with sharp microelectrodes from CA1 neurons showed that evoked GABAAR- or GABABR-mediated inhibitory postsynaptic potentials (IPSP) remained unaltered in anti-GAD65 tissue. These results were confirmed with patch-clamp recordings showing no difference in evoked gabazine-sensitive inhibitory postsynaptic currents (IPSCs). In addition, spontaneous IPSCs also showed no difference between anti-GAD65 tissue and controls with respect to the mean frequency, the mean amplitude and the sIPSC distribution. In conclusion, stereotactic injection of GAD65-antibodies into the hippocampus leaves evoked and spontaneous GABAergic synaptic transmission intact. Hence, dysfunction of the inhibitory GABAergic system does not appear to be the major mechanism of epileptogenicity in this disease. PMID:27242441

  1. Assortment of GABAergic plasticity in the cortical interneuron melting pot.

    PubMed

    Méndez, Pablo; Bacci, Alberto

    2011-01-01

    Cortical structures of the adult mammalian brain are characterized by a spectacular diversity of inhibitory interneurons, which use GABA as neurotransmitter. GABAergic neurotransmission is fundamental for integrating and filtering incoming information and dictating postsynaptic neuronal spike timing, therefore providing a tight temporal code used by each neuron, or ensemble of neurons, to perform sophisticated computational operations. However, the heterogeneity of cortical GABAergic cells is associated to equally diverse properties governing intrinsic excitability as well as strength, dynamic range, spatial extent, anatomical localization, and molecular components of inhibitory synaptic connections that they form with pyramidal neurons. Recent studies showed that similarly to their excitatory (glutamatergic) counterparts, also inhibitory synapses can undergo activity-dependent changes in their strength. Here, some aspects related to plasticity and modulation of adult cortical and hippocampal GABAergic synaptic transmission will be reviewed, aiming at providing a fresh perspective towards the elucidation of the role played by specific cellular elements of cortical microcircuits during both physiological and pathological operations.

  2. Transplantation of GABAergic cells derived from bioreactor-expanded human neural precursor cells restores motor and cognitive behavioral deficits in a rodent model of Huntington's disease.

    PubMed

    McLeod, Marcus C; Kobayashi, Nao R; Sen, Arindom; Baghbaderani, Behnam A; Sadi, Damaso; Ulalia, Ruperto; Behie, Leo A; Mendez, Ivar

    2013-01-01

    Huntington's disease (HD) is a neurodegenerative disorder that is characterized by progressive dementia, choreiform involuntary movements, and emotional deterioration. Neuropathological features include the progressive degeneration of striatal γ-aminobutyric acid (GABA) neurons. New therapeutic approaches, such as the transplantation of human neural precursor cells (hNPCs) to replace damaged or degenerated cells, are currently being investigated. The aim of this study was to investigate the potential for utilizing telencephalic hNPCs expanded in suspension bioreactors for cell restorative therapy in a rodent model of HD. hNPCs were expanded in a hydrodynamically controlled and homogeneous environment under serum-free conditions. In vitro analysis revealed that the bioreactor-expanded telencephalic (BET)-hNPCs could be differentiated into a highly enriched population of GABAergic neurons. Behavioral assessments of unilateral striatal quinolinic acid-lesioned rodents revealed a significant improvement in motor and memory deficits following transplantation with GABAergic cells differentiated from BET-hNPCs. Immunohistochemical analysis revealed that transplanted BET-hNPCs retained a GABAergic neuronal phenotype without aberrant transdifferentiation or tumor formation, indicating that BET-hNPCs are a safe source of cells for transplantation. This preclinical study has important implications as the transplantation of GABAergic cells derived from predifferentiated BET-hNPCs may be a safe and feasible cell replacement strategy to promote behavioral recovery in HD.

  3. Cholestenoic acids regulate motor neuron survival via liver X receptors

    PubMed Central

    Theofilopoulos, Spyridon; Griffiths, William J.; Crick, Peter J.; Yang, Shanzheng; Meljon, Anna; Ogundare, Michael; Kitambi, Satish Srinivas; Lockhart, Andrew; Tuschl, Karin; Clayton, Peter T.; Morris, Andrew A.; Martinez, Adelaida; Reddy, M. Ashwin; Martinuzzi, Andrea; Bassi, Maria T.; Honda, Akira; Mizuochi, Tatsuki; Kimura, Akihiko; Nittono, Hiroshi; De Michele, Giuseppe; Carbone, Rosa; Criscuolo, Chiara; Yau, Joyce L.; Seckl, Jonathan R.; Schüle, Rebecca; Schöls, Ludger; Sailer, Andreas W.; Kuhle, Jens; Fraidakis, Matthew J.; Gustafsson, Jan-Åke; Steffensen, Knut R.; Björkhem, Ingemar; Ernfors, Patrik; Sjövall, Jan; Arenas, Ernest; Wang, Yuqin

    2014-01-01

    Cholestenoic acids are formed as intermediates in metabolism of cholesterol to bile acids, and the biosynthetic enzymes that generate cholestenoic acids are expressed in the mammalian CNS. Here, we evaluated the cholestenoic acid profile of mammalian cerebrospinal fluid (CSF) and determined that specific cholestenoic acids activate the liver X receptors (LXRs), enhance islet-1 expression in zebrafish, and increase the number of oculomotor neurons in the developing mouse in vitro and in vivo. While 3β,7α-dihydroxycholest-5-en-26-oic acid (3β,7α-diHCA) promoted motor neuron survival in an LXR-dependent manner, 3β-hydroxy-7-oxocholest-5-en-26-oic acid (3βH,7O-CA) promoted maturation of precursors into islet-1+ cells. Unlike 3β,7α-diHCA and 3βH,7O-CA, 3β-hydroxycholest-5-en-26-oic acid (3β-HCA) caused motor neuron cell loss in mice. Mutations in CYP7B1 or CYP27A1, which encode enzymes involved in cholestenoic acid metabolism, result in different neurological diseases, hereditary spastic paresis type 5 (SPG5) and cerebrotendinous xanthomatosis (CTX), respectively. SPG5 is characterized by spastic paresis, and similar symptoms may occur in CTX. Analysis of CSF and plasma from patients with SPG5 revealed an excess of the toxic LXR ligand, 3β-HCA, while patients with CTX and SPG5 exhibited low levels of the survival-promoting LXR ligand 3β,7α-diHCA. Moreover, 3β,7α-diHCA prevented the loss of motor neurons induced by 3β-HCA in the developing mouse midbrain in vivo.Our results indicate that specific cholestenoic acids selectively work on motor neurons, via LXR, to regulate the balance between survival and death. PMID:25271621

  4. Lysophosphatidic acid induces necrosis and apoptosis in hippocampal neurons.

    PubMed

    Holtsberg, F W; Steiner, M R; Keller, J N; Mark, R J; Mattson, M P; Steiner, S M

    1998-01-01

    A diverse body of evidence indicates a role for the lipid biomediator lysophosphatidic acid (LPA) in the CNS. This study identifies and characterizes the induction of neuronal death by LPA. Treatment of cultured hippocampal neurons from embryonic rat brains with 50 microM LPA resulted in neuronal necrosis, as determined morphologically and by the release of lactate dehydrogenase. A concentration of LPA as low as 10 microM led to the release of lactate dehydrogenase. In contrast, treatment of neurons with 0.1 or 1.0 microM LPA resulted in apoptosis, as determined by chromatin condensation. In addition, neuronal death induced by 1 microM LPA was characterized as apoptotic on the basis of terminal dUTP nick end-labeling (TUNEL) staining, externalization of phosphatidylserine, and protection against chromatin condensation, TUNEL staining, and phosphatidylserine externalization by treatment with N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone, a broad-spectrum inhibitor of caspases, i.e., members of the interleukin-1beta converting enzyme family. Studies with antagonists of ionotropic glutamate receptors did not indicate a significant role for these receptors in apoptosis induced by 1 microM LPA. LPA (1 microM) also induced a decrease in mitochondrial membrane potential. Moreover, pretreatment of neurons with cyclosporin A protected against the LPA-induced decrease in mitochondrial membrane potential and neuronal apoptosis. Thus, LPA, at pathophysiological levels, can induce neuronal apoptosis and could thereby participate in neurodegenerative disorders. PMID:9422348

  5. Protective Effect of Spermidine Against Excitotoxic Neuronal Death Induced by Quinolinic Acid in Rats: Possible Neurotransmitters and Neuroinflammatory Mechanism.

    PubMed

    Jamwal, Sumit; Singh, Shamsher; Kaur, Navneet; Kumar, Puneet

    2015-08-01

    Huntington disease is hyperkinetic movement disorder characterized by selective and immense degradation of GABAergic medium spiny neurons in striatum. Quinolinic acid (QA)-induced neurotoxicity involves a cascade of events such as excitotoxicity, ATP depletion, oxidative stress, neuroinflammation, as well as selective GABAergic neuronal loss. Therefore, we investigated spermidine, an endogenous molecule with free radical scavenging, anti-inflammatory, and N-methyl-D-aspartate receptor antagonistic properties, for its beneficial potential if any, in QA-induced Huntington's like symptoms in rats. Rats were administered with QA (200 nmol/2 µl saline) bilaterally on 0 day. Spermidine (5 and 10 mg/kg, p.o.) was administered for 21 days once a day. Behavioral parameters (body weight, locomotor activity, grip strength, and narrow beam walk) observations were done on 1st, 7th, 14th, and 21st day after QA treatment. On 21st day, animals were sacrificed and rat striatum was isolated for biochemical (LPO, GSH, Nitrite), neuroinflammation (TNF-α, IL-1β, and IL-6), and neurochemical analysis (GABA, glutamate, dopamine, norepinephrine, serotonin, DOPAC, HVA, 5-HIAA, adenosine, adenine, hypoxanthine, and inosine). QA treatment significantly altered body weight, locomotor activity, motor coordination, oxidative defense (increased LPO, nitrite, and decreased GSH), pro-inflammatory levels (TNF-α, IL-6 and IL-1β), GABA, glutamate, catecholamines level (norepinephrine, dopamine, and serotonin and their metabolites), and purines level (adenosine, inosine, and hypoxanthine). Spermidine (5 and 10 mg/kg, p.o.) significantly attenuated these alterations in body weight, motor impairments, oxidative stress, neuroinflammatory markers, GABA, glutamate, catecholamines, adenosine, and their metabolites levels in striatum. The neuroprotective effect of spermidine against QA-induced excitotoxic cell death is attributed to its antioxidant, N-methyl-D-aspartate receptor antagonistic, anti

  6. The GABAergic System and the Gastrointestinal Physiopathology.

    PubMed

    Auteri, Michelangelo; Zizzo, Maria Grazia; Serio, Rosa

    2015-01-01

    Since the first report about the presence of γ-aminobutyric acid (GABA) within the gastrointestinal (GI) tract, accumulating evidence strongly supports the widespread representation of the GABAergic system in the enteric milieu, underlining its potential multifunctional role in the regulation of GI functions in health and disease. GABA and GABA receptors are widely distributed throughout the GI tract, constituting a complex network likely regulating the diverse GI behaviour patterns, cooperating with other major neurotransmitters and mediators for maintaining GI homeostasis in physiologic and pathologic conditions. GABA is involved in the circuitry of the enteric nervous system, controlling GI secretion and motility, as well as in the GI endocrine system, possibly acting as a autocrine/paracrine or hormonal agent. Furthermore, a series of investigations addresses the GABAergic system as a potential powerful modulator of GI visceral pain processing, enteric immune system and carcinogenesis. Although overall such actions may imply the consideration of the GABAergic system as a novel therapeutic target in different GI pathologic states, including GI motor and secretory diseases and different enteric inflammatory- and pain-related pathologies, current clinical applications of GABAergic drugs are scarce. Thus, in an attempt to propel novel scientific efforts addressing the detailed characterization of the GABAergic signaling in the GI tract, and consequently the development of novel strategies for the treatment of different GI disorders, we reviewed and discussed the current evidence about GABA actions in the enteric environment, with a particular focus on their possible therapeutic implications. PMID:26365138

  7. Immunohistochemical localization of GABAergic key molecules in the main olfactory bulb of the Korean roe deer, Capreolus pygargus.

    PubMed

    Kim, Jeongtae; Takayama, Chitoshi; Park, Changnam; Ahn, Meejung; Moon, Changjong; Shin, Taekyun

    2015-09-01

    Gamma-amino butyric acid (GABA) negatively regulates the excitatory activity of neurons and is a predominant neurotransmitter in the nervous system. The olfactory bulb, the main center in the olfactory system, is modulated by inhibitory interneurons that use GABA as their main neurotransmitter. The present study aimed to evaluate GABAergic transmission in the main olfactory bulb (MOB) of the Korean roe deer (Capreolus pygargus) by examining the immunohistochemical localization of GABAergic key molecules, including glutamic acid decarboxylase (GAD), vesicular GABA transporter (VGAT), GABA transporters (GATs; GAT-1 and GAT-3), and potassium sodium chloride co-transporter 2 (KCC2). GAD, VGAT, and KCC2 were expressed in the glomerular layer (GL), external plexiform layer (ePL), mitral cell layer (ML), and granule cell layer (GrL). Intense GAT-1 expression was observed in the GL; GAT-1 expression was discernible in the ePL, ML, and GrL. However, intense GAT-3 expression was extensively observed in all layers of the MOB. These results suggest that substantial GABAergic synapses are present in the GL, ePL, ML, and GrL. Furthermore, the released GABA may be removed by GAT-1 and GAT-3 in the GL, and the majority of GABA, which is present in the ePL to GrL, may undergo reuptake by GAT-3. This is the first morphological and descriptive study of GABAergic transmission in the MOB of Korean roe deer. PMID:26115600

  8. Further evidence for involvement of the dorsal hippocampus serotonergic and γ-aminobutyric acid (GABA)ergic pathways in the expression of contextual fear conditioning in rats.

    PubMed

    Almada, Rafael C; Albrechet-Souza, Lucas; Brandão, Marcus L

    2013-12-01

    Intra-dorsal hippocampus (DH) injections of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a serotonin-1A (5-hydroxytryptamine (5-HT)-1A) receptor agonist, were previously shown to inhibit the expression of contextual fear when administered six hours after conditioning. However, further understanding of the consolidation and expression of aversive memories requires investigations of these and other mechanisms at distinct time points and the regions of the brain to which they are transferred. Thus, the purpose of the present study was to investigate the role of DH serotonergic and γ-aminobutyric acid (GABA)ergic mechanisms in the expression of contextual fear 24 h after conditioning, reflected by fear-potentiated startle (FPS) and freezing behavior. The recruitment of the amygdala and medial prefrontal cortex (mPFC) in these processes was also evaluated by measuring Fos protein immunoreactivity. Although intra-DH injections of 8-OH-DPAT did not produce behavioral changes, muscimol reduced both FPS and the freezing response. Fos protein immunoreactivity revealed that contextual fear promoted wide activation of the mPFC, which was significantly reduced after intra-DH infusions of muscimol. The present findings, together with previous data, indicate that in contrast to 5-HT, which appears to play a role during the early phases of contextual aversive memory consolidation, longer-lasting GABA-mediated mechanisms are recruited during the expression of contextual fear memories.

  9. The GABAergic Deficit Hypothesis of Major Depressive Disorder

    PubMed Central

    Luscher, Bernhard; Shen, Qiuying; Sahir, Nadia

    2012-01-01

    Increasing evidence points to an association between major depressive disorders (MDDs) and diverse types of GABAergic deficits. Here we summarize clinical and preclinical evidence supporting a central and causal role of GABAergic deficits in the etiology of depressive disorders. Studies of depressed patients indicate that MDDs are accompanied by reduced brain concentration of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) as well as alterations in the subunit composition of the principal receptors (GABAA receptors) mediating GABAergic inhibition. In addition, there is abundant evidence that GABA plays a prominent role in the brain control of stress, the most important vulnerability factor in mood disorders. Furthermore, preclinical evidence suggests that currently used antidepressant drugs designed to alter monoaminergic transmission as well as non-pharmacologic therapies may ultimately act to counteract GABAergic deficits. In particular, GABAergic transmission plays an important role in the control of hippocampal neurogenesis and neural maturation, which are now established as cellular substrates of most if not all antidepressant therapies. Lastly, comparatively modest deficits in GABAergic transmission in GABAA-receptor-deficient mice are sufficient to cause behavioral, cognitive, neuroanatomical, and neuroendocrine phenotypes as well as antidepressant drug response characteristics expected of an animal model of MDD. The GABAergic hypothesis of MDD suggests that alterations in GABAergic transmission represent fundamentally important aspects of the etiological sequelae of major depressive disorders that are reversed by monoaminergic antidepressant drug action. PMID:21079608

  10. C. elegans fmi-1/flamingo and Wnt pathway components interact genetically to control the anteroposterior neurite growth of the VD GABAergic neurons

    PubMed Central

    Ackley, Brian D

    2013-01-01

    During development, multiple environmental cues, e.g., growth factors, cell adhesion molecules, etc., interact to influence the pattern of outgrowth of axons and dendrites in a cell-specific fashion. As a result, individual neurons may receive similar signals, but make unique choices, leading to distinct wiring within the nervous system. C. elegans has been useful in identifying molecular cues that influence neuronal development, as well as the downstream mechanisms that allow individual neurons to make cell-specific responses. Recently, we described a role for the conserved cadherin domain-containing protein, FMI-1/flamingo, in multiple stages of neural development in C. elegans. During the initial phase of neurite outgrowth, FMI-1 seems to have a relatively cell-specific effect on the VD neurons to promote the initial neurite formed to grow toward the anterior. In this capacity, FMI-1 appears to work coordinately with at least two Wnt ligands, EGL-20 and LIN-44, and multiple downstream Wnt signaling components (including LIN-17/Frizzled, DSH-1/Disheveled, and BAR-1/β-catenin). Here I will discuss some of the ideas we considered about how FMI-1 could affect neurons as they acquire their morphology during development. PMID:24778938

  11. Multiple anxiogenic drugs recruit a parvalbumin-containing subpopulation of GABAergic interneurons in the basolateral amygdala

    PubMed Central

    Hale, Matthew W.; Johnson, Philip L.; Westerman, Alex M.; Abrams, Jolane K.; Shekhar, Anantha; Lowry, Christopher A.

    2010-01-01

    The basolateral amygdala is a nodal structure within a distributed and interconnected network that regulates anxiety states and anxiety-related behavior. Administration of multiple anxiogenic drugs increases cellular responses (i.e., increases c-Fos expression) in a subregion of the basolateral amygdala, but the neurochemical phenotypes of these cells are not known. The basolateral amygdala contains glutamatergic projection neurons and several populations of γ-aminobutyric acid-synthesizing (GABAergic) interneurons, including a population of parvalbumin (PV)-expressing GABAergic interneurons that co-express the excitatory 5-HT2A receptor. The role for these PV-expressing GABAergic interneurons in anxiety-states is unclear. In this experiment we examined the effects of multiple anxiogenic drugs including the 5-HT2A/2C receptor agonist m-chlorophenyl piperazine (mCPP), the adenosine receptor antagonist caffeine, the α2-adrenoreceptor antagonist yohimbine and the partial inverse agonist at the benzodiazepine allosteric site on the GABAA receptor, N-methyl-beta-carboline-3-carboxamide (FG-7142), on c-Fos expression in PV-immunoreactive (PV-ir) interneurons in subdivisions of the basolateral amygdala. All drugs with the exception of mCPP increased c-Fos expression in PV-ir neurons in the basolateral amygdaloid nucleus, anterior part (BLA). The numbers of c-Fos-immunoreactive (c-Fos-ir)/PV-ir GABAergic interneurons in the BLA were positively correlated with the numbers of c-Fos-ir serotonergic neurons in the mid-rostrocaudal dorsal raphe nucleus (DR) and with a measure of anxiety-related behavior. All four drugs increased c-Fos expression in non-PV-ir cells in most of the subdivisions of the basolateral amygdala that were sampled, compared with vehicle-injected controls. Together, these data suggest that the PV/5-HT2A receptor expressing GABAergic interneurons in the basolateral amygdala are part of a DR-basolateral amygdala neuronal circuit modulating anxiety

  12. The amyloid precursor protein controls adult hippocampal neurogenesis through GABAergic interneurons.

    PubMed

    Wang, Baiping; Wang, Zilai; Sun, Lu; Yang, Li; Li, Hongmei; Cole, Allysa L; Rodriguez-Rivera, Jennifer; Lu, Hui-Chen; Zheng, Hui

    2014-10-01

    Impaired neurogenesis in the adult hippocampus has been implicated in AD pathogenesis. Here we reveal that the APP plays an important role in the neural progenitor proliferation and newborn neuron maturation in the mouse dentate gyrus. APP controls adult neurogenesis through a non cell-autonomous mechanism by GABAergic neurons, as selective deletion of GABAergic, but not glutamatergic, APP disrupts adult hippocampal neurogenesis. APP, highly expressed in the majority of GABAergic neurons in the dentate gyrus, enhances the inhibitory tone to granule cells. By regulating both tonic and phasic GABAergic inputs to dentate granule cells, APP maintains excitatory-inhibitory balance and preserves cognitive functions. Our studies uncover an indispensable role of APP in the GABAergic system for controlling adult hippocampal neurogenesis, and our findings indicate that APP dysfunction may contribute to impaired neurogenesis and cognitive decline associated with AD.

  13. Valproic acid protects neurons and promotes neuronal regeneration after brachial plexus avulsion

    PubMed Central

    Li, Qiang; Wu, Dianxiu; Li, Rui; Zhu, Xiaojuan; Cui, Shusen

    2013-01-01

    Valproic acid has been shown to exert neuroprotective effects and promote neurite outgrowth in several peripheral nerve injury models. However, whether valproic acid can exert its beneficial effect on neurons after brachial plexus avulsion injury is currently unknown. In this study, brachial plexus root avulsion models, established in Wistar rats, were administered daily with valproic acid dissolved in drinking water (300 mg/kg) or normal water. On days 1, 2, 3, 7, 14 and 28 after avulsion injury, tissues of the C5–T1 spinal cord segments of the avulsion injured side were harvested to investigate the expression of Bcl-2, c-Jun and growth associated protein 43 by real-time PCR and western blot assay. Results showed that valproic acid significantly increased the expression of Bcl-2 and growth associated protein 43, and reduced the c-Jun expression after brachial plexus avulsion. Our findings indicate that valproic acid can protect neurons in the spinal cord and enhance neuronal regeneration following brachial plexus root avulsion. PMID:25206605

  14. Role of tonic GABAergic currents during pre- and early postnatal rodent development.

    PubMed

    Kilb, Werner; Kirischuk, Sergei; Luhmann, Heiko J

    2013-01-01

    In the last three decades it became evident that the GABAergic system plays an essential role for the development of the central nervous system, by influencing the proliferation of neuronal precursors, neuronal migration and differentiation, as well as by controlling early activity patterns and thus formation of neuronal networks. GABA controls neuronal development via depolarizing membrane responses upon activation of ionotropic GABA receptors. However, many of these effects occur before the onset of synaptic GABAergic activity and thus require the presence of extrasynaptic tonic currents in neuronal precursors and immature neurons. This review summarizes our current knowledge about the role of tonic GABAergic currents during early brain development. In this review we compare the temporal sequence of the expression and functional relevance of different GABA receptor subunits, GABA synthesizing enzymes and GABA transporters. We also refer to other possible endogenous agonists of GABAA receptors. In addition, we describe functional consequences mediated by the GABAergic system during early developmental periods and discuss current models about the origin of extrasynaptic GABA and/or other endogenous GABAergic agonists during early developmental states. Finally, we present evidence that tonic GABAergic activity is also critically involved in the generation of physiological as well as pathophysiological activity patterns before and after the establishment of functional GABAergic synaptic connections.

  15. Genetic dissection of GABAergic neural circuits in mouse neocortex

    PubMed Central

    Taniguchi, Hiroki

    2014-01-01

    Diverse and flexible cortical functions rely on the ability of neural circuits to perform multiple types of neuronal computations. GABAergic inhibitory interneurons significantly contribute to this task by regulating the balance of activity, synaptic integration, spiking, synchrony, and oscillation in a neural ensemble. GABAergic interneurons display a high degree of cellular diversity in morphology, physiology, connectivity, and gene expression. A considerable number of subtypes of GABAergic interneurons diversify modes of cortical inhibition, enabling various types of information processing in the cortex. Thus, comprehensively understanding fate specification, circuit assembly, and physiological function of GABAergic interneurons is a key to elucidate the principles of cortical wiring and function. Recent advances in genetically encoded molecular tools have made a breakthrough to systematically study cortical circuitry at the molecular, cellular, circuit, and whole animal levels. However, the biggest obstacle to fully applying the power of these to analysis of GABAergic circuits was that there were no efficient and reliable methods to express them in subtypes of GABAergic interneurons. Here, I first summarize cortical interneuron diversity and current understanding of mechanisms, by which distinct classes of GABAergic interneurons are generated. I then review recent development in genetically encoded molecular tools for neural circuit research, and genetic targeting of GABAergic interneuron subtypes, particularly focusing on our recent effort to develop and characterize Cre/CreER knockin lines. Finally, I highlight recent success in genetic targeting of chandelier cells, the most unique and distinct GABAergic interneuron subtype, and discuss what kind of questions need to be addressed to understand development and function of cortical inhibitory circuits. PMID:24478631

  16. Brain-derived neurotrophic factor increases inhibitory synapses, revealed in solitary neurons cultured from rat visual cortex.

    PubMed

    Palizvan, M R; Sohya, K; Kohara, K; Maruyama, A; Yasuda, H; Kimura, F; Tsumoto, T

    2004-01-01

    To elucidate chronic actions of brain-derived neurotrophic factor (BDNF) on GABAergic synapses, we examined effects of a long-term application of BDNF for 10-15 days on autapses (synapses) of solitary GABAergic neurons cultured from rat visual cortex. Solitary neuron preparations were used to exclude a possible contamination of BDNF actions on excitatory neurons in dissociated neuron culture or slice preparations. Neurons were confirmed to be GABAergic pharmacologically with bicuculline, a selective antagonist for GABAA receptors and immunocytochemically with antibody against glutamic acid decarboxylase 65, a GABA synthesizing enzyme. To evaluate GABAergic synaptic function, evoked and/or miniature inhibitory postsynaptic currents (IPSCs) were recorded in the whole-cell voltage-clamp mode. The treatment with BDNF at a concentration of 100 ng/ml enhanced the amplitude of evoked IPSCs and the frequency of miniature IPSCs. In contrast, BDNF did not have a detectable effect on the amplitude of miniature IPSCs and the paired pulse ratio of IPSCs evoked by two, successive activations. To evaluate morphological changes, neurons were immunocytochemically stained with antibodies against microtubule-associated protein 2, to visualize somatodendritic region and synapsin I, to visualize presynaptic sites. The quantitative analysis indicated that BDNF increased the area of soma, the numbers of primary dendrites and dendritic branching points, the total length of dendrites and the number of synaptic sites. Such an action of BDNF was seen in both subgroups of GABAergic neurons, parvalbumin-positive and -negative neurons. To visualize functionally active presynaptic sites, neurons were stained with a styryl dye, FM1-43. BDNF increased the number of stained sites that was correlated with the frequency of miniature IPSCs. These results suggest that the chronic treatment with BDNF promotes dendritic and synaptic development of GABAergic neurons in visual cortex.

  17. Quinolinic acid induces disrupts cytoskeletal homeostasis in striatal neurons. Protective role of astrocyte-neuron interaction.

    PubMed

    Pierozan, Paula; Ferreira, Fernanda; de Lima, Bárbara Ortiz; Pessoa-Pureur, Regina

    2015-02-01

    Quinolinic acid (QUIN) is an endogenous metabolite of the kynurenine pathway involved in several neurological disorders. Among the several mechanisms involved in QUIN-mediated toxicity, disruption of the cytoskeleton has been demonstrated in striatally injected rats and in striatal slices. The present work searched for the actions of QUIN in primary striatal neurons. Neurons exposed to 10 µM QUIN presented hyperphosphorylated neurofilament (NF) subunits (NFL, NFM, and NFH). Hyperphosphorylation was abrogated in the presence of protein kinase A and protein kinase C inhibitors H89 (20 μM) and staurosporine (10 nM), respectively, as well as by specific antagonists to N-methyl-D-aspartate (50 µM DL-AP5) and metabotropic glutamate receptor 1 (100 µM MPEP). Also, intra- and extracellular Ca(2+) chelators (10 µM BAPTA-AM and 1 mM EGTA, respectively) and Ca(2+) influx through L-type voltage-dependent Ca(2+) channel (10 µM verapamil) are implicated in QUIN-mediated effects. Cells immunostained for the neuronal markers βIII-tubulin and microtubule-associated protein 2 showed altered neurite/neuron ratios and neurite outgrowth. NF hyperphosphorylation and morphological alterations were totally prevented by conditioned medium from QUIN-treated astrocytes. Cocultured astrocytes and neurons interacted with one another reciprocally, protecting them against QUIN injury. Cocultured cells preserved their cytoskeletal organization and cell morphology together with unaltered activity of the phosphorylating system associated with the cytoskeleton. This article describes cytoskeletal disruption as one of the most relevant actions of QUIN toxicity in striatal neurons in culture with soluble factors secreted by astrocytes, with neuron-astrocyte interaction playing a role in neuroprotection.

  18. Physiological impact of CB1 receptor expression by hippocampal GABAergic interneurons.

    PubMed

    Albayram, Önder; Passlick, Stefan; Bilkei-Gorzo, Andras; Zimmer, Andreas; Steinhäuser, Christian

    2016-04-01

    A subset of hippocampal GABAergic neurons, which are cholecystokinin-positive, highly express cannabinoid type 1 (CB1) receptors. Activation of these receptors inhibits GABA release and thereby limits inhibitory control. While genetic deletion of CB1 receptors from GABAergic neurons led to behavioural alterations and neuroinflammatory reactions, it remained unclear whether these changes in the knockout animals were a direct consequence of the enhanced transmitter release or reflected developmental deficits. The hippocampus is vital for the generation of spatial, declarative and working memory. Here, we addressed the question how CB1 receptors in GABAergic neurons influence hippocampal function. Patch clamp and field potential recordings in mice devoid of CB1 receptors in GABAergic neurons revealed an enhanced frequency and faster kinetics of spontaneous inhibitory postsynaptic currents in CA1 pyramidal neurons while tonic inhibition, paired-pulse facilitation and long-term potentiation in the hippocampus were not affected. Evaluation of cognitive functions demonstrated impaired acquisition of spatial memory and deficits in novel object recognition and partner recognition in the knockout mice, while working memory and spatial memory remained intact. The density of GABAergic neurons was also similar in knockout mice and their littermates, which argues against global deficits in hippocampal development. Together, these results suggest that CB1 receptors in GABAergic neurons influence specific aspects of neuronal excitability and hippocampal learning.

  19. GABAergic feedback signaling into the calyces of the mushroom bodies enables olfactory reversal learning in honey bees

    PubMed Central

    Boitard, Constance; Devaud, Jean-Marc; Isabel, Guillaume; Giurfa, Martin

    2015-01-01

    In reversal learning, subjects first learn to respond to a reinforced stimulus A and not to a non-reinforced stimulus B (A+ vs. B−) and then have to learn the opposite when stimulus contingencies are reversed (A− vs. B+). This change in stimulus valence generates a transitory ambiguity at the level of stimulus outcome that needs to be overcome to solve the second discrimination. Honey bees (Apis mellifera) efficiently master reversal learning in the olfactory domain. The mushroom bodies (MBs), higher-order structures of the insect brain, are required to solve this task. Here we aimed at uncovering the neural circuits facilitating reversal learning in honey bees. We trained bees using the olfactory conditioning of the proboscis extension reflex (PER) coupled with localized pharmacological inhibition of Gamma-AminoButyric Acid (GABA)ergic signaling in the MBs. We show that inhibition of ionotropic but not metabotropic GABAergic signaling into the MB calyces impairs reversal learning, but leaves intact the capacity to perform two consecutive elemental olfactory discriminations with ambiguity of stimulus valence. On the contrary, inhibition of ionotropic GABAergic signaling into the MB lobes had no effect on reversal learning. Our results are thus consistent with a specific requirement of the feedback neurons (FNs) providing ionotropic GABAergic signaling from the MB lobes to the calyces for counteracting ambiguity of stimulus valence in reversal learning. PMID:26283938

  20. GABAergic feedback signaling into the calyces of the mushroom bodies enables olfactory reversal learning in honey bees.

    PubMed

    Boitard, Constance; Devaud, Jean-Marc; Isabel, Guillaume; Giurfa, Martin

    2015-01-01

    In reversal learning, subjects first learn to respond to a reinforced stimulus A and not to a non-reinforced stimulus B (A(+) vs. B(-)) and then have to learn the opposite when stimulus contingencies are reversed (A(-) vs. B(+)). This change in stimulus valence generates a transitory ambiguity at the level of stimulus outcome that needs to be overcome to solve the second discrimination. Honey bees (Apis mellifera) efficiently master reversal learning in the olfactory domain. The mushroom bodies (MBs), higher-order structures of the insect brain, are required to solve this task. Here we aimed at uncovering the neural circuits facilitating reversal learning in honey bees. We trained bees using the olfactory conditioning of the proboscis extension reflex (PER) coupled with localized pharmacological inhibition of Gamma-AminoButyric Acid (GABA)ergic signaling in the MBs. We show that inhibition of ionotropic but not metabotropic GABAergic signaling into the MB calyces impairs reversal learning, but leaves intact the capacity to perform two consecutive elemental olfactory discriminations with ambiguity of stimulus valence. On the contrary, inhibition of ionotropic GABAergic signaling into the MB lobes had no effect on reversal learning. Our results are thus consistent with a specific requirement of the feedback neurons (FNs) providing ionotropic GABAergic signaling from the MB lobes to the calyces for counteracting ambiguity of stimulus valence in reversal learning. PMID:26283938

  1. Frequent coexpression of the vesicular glutamate transporter 1 and 2 genes, as well as coexpression with genes for choline acetyltransferase or glutamic acid decarboxylase in neurons of rat brain.

    PubMed

    Danik, Marc; Cassoly, Estelle; Manseau, Frédéric; Sotty, Florence; Mouginot, Didier; Williams, Sylvain

    2005-08-15

    It is widely believed that expression of the vesicular glutamate transporter genes VGLUT1 and VGLUT2 is restricted to glutamatergic neurons and that the two transporters segregate in different sets of neurons. Using single-cell multiplex RT-PCR (sc-RT-mPCR), we show that VGLUT1 and VGLUT2 mRNAs were coexpressed in most of the sampled neurons from the rat hippocampus, cortex, and cerebellum at postnatal Day (P)14 but not P60. In accordance, changes in VGLUT1 and VGLUT2 mRNA concentrations were found to occur in these and other brain areas between P14 and P60, as revealed by semiquantitative RT-PCR and quantitated by ribonuclease protection assay. VGLUT1 and -2 coexpression in the hippocampal formation is supported further by in situ hybridization data showing that virtually all cells in the CA1-CA3 pyramidal and granule cell layers were highly positive for both transcripts until P14. It was revealed using sc-RT-mPCR that transcripts for VGLUT1 and VGLUT2 were also present in neurons of the cerebellum, striatum, and septum that expressed markers for gamma-aminobutyric acid (GABA)ergic or cholinergic phenotypes, as well as in hippocampal cells containing transcripts for the glial fibrillary acidic protein. Our study suggests that VGLUT1 and VGLUT2 proteins may often transport glutamate into vesicles within the same neuron, especially during early postnatal development, and that they are expressed widely in presumed glutamatergic, GABAergic, and cholinergic neurons, as well as in astrocytes. Furthermore, our study shows that such coexpressing neurons remain in the adult brain and identifies several areas that contain them in both young and adult rats. PMID:15983996

  2. GABAergic Interneurons in the Neocortex: From Cellular Properties to Circuits.

    PubMed

    Tremblay, Robin; Lee, Soohyun; Rudy, Bernardo

    2016-07-20

    Cortical networks are composed of glutamatergic excitatory projection neurons and local GABAergic inhibitory interneurons that gate signal flow and sculpt network dynamics. Although they represent a minority of the total neocortical neuronal population, GABAergic interneurons are highly heterogeneous, forming functional classes based on their morphological, electrophysiological, and molecular features, as well as connectivity and in vivo patterns of activity. Here we review our current understanding of neocortical interneuron diversity and the properties that distinguish cell types. We then discuss how the involvement of multiple cell types, each with a specific set of cellular properties, plays a crucial role in diversifying and increasing the computational power of a relatively small number of simple circuit motifs forming cortical networks. We illustrate how recent advances in the field have shed light onto the mechanisms by which GABAergic inhibition contributes to network operations.

  3. Nitric oxide facilitates GABAergic neurotransmission in the cat oculomotor system: a physiological mechanism in eye movement control

    PubMed Central

    Moreno-López, Bernardo; Escudero, Miguel; Estrada, Carmen

    2002-01-01

    Nitric oxide (NO) synthesis by prepositus hypoglossi (PH) neurons is necessary for the normal performance of horizontal eye movements. We have previously shown that unilateral injections of NO synthase (NOS) inhibitors into the PH nucleus of alert cats produce velocity imbalance without alteration of the eye position control, both during spontaneous eye movements and the vestibulo-ocular reflex (VOR). This NO effect is exerted on the dorsal PH neuropil, whose fibres increase their cGMP content when stimulated by NO. In an attempt to determine whether NO acts by modulation of a specific neurotransmission system, we have now compared the oculomotor effects of NOS inhibition with those produced by local blockade of glutamatergic, GABAergic or glycinergic receptors in the PH nucleus of alert cats. Both glutamatergic antagonists used, 2-amino-5-phosphonovaleric acid (APV) and 2,3-dihydro-6-nitro-7-sulphamoyl-benzo quinoxaline (NBQX), induced a nystagmus contralateral to that observed upon NOS inhibition, and caused exponential eye position drift. In contrast, bicuculline and strychnine induced eye velocity alterations similar to those produced by NOS inhibitors, suggesting that NO oculomotor effects were due to facilitation of some inhibitory input to the PH nucleus. To investigate the anatomical location of the putative NO target neurons, the retrograde tracer Fast Blue was injected in one PH nucleus, and the brainstem sections containing Fast Blue-positive neurons were stained with double immunohistochemistry for NO-sensitive cGMP and glutamic acid decarboxylase. GABAergic neurons projecting to the PH nucleus and containing NO-sensitive cGMP were found almost exclusively in the ipsilateral medial vestibular nucleus and marginal zone. The results suggest that the nitrergic PH neurons control their own firing rate by a NO-mediated facilitation of GABAergic afferents from the ipsilateral medial vestibular nucleus. This self-control mechanism could play an important role

  4. [MOLECULAR MECHANISMS OF ERK1/2 KINASES REGULATION IN THE GLUTAMATE- AND GABA-ERGIC NEURONS DURING SEIZURE EXPRESSION IN KRUSHINSKY-MOLODKINA RATS].

    PubMed

    Korotkov, A A; Glazova, M V; Nikitina, L S; Dorofeeva, N A; Kirillova, O D; Chernigovskaya, E V

    2015-10-01

    The aim of the present study was to analyze a role of the ERK1/2 signaling pathway in the regulation of excitation and inhibitory neurons in the hippocampus and the temporal cortex of Krushinsky-Molodkina rats during seizure development finalizing with ataxia. Analysis was done by Western bloting as well as by immunohistochemistry. The results demonstrated significant up-regulation of ERK1/2 activity in the hippocampus in several seconds after sound stimulation. At the same time increased ERK1/2 activity was correlated with enhanced level of SNARE protein SNAP-25 and activation of synapsin I, the proteins which regulate exocytosis machinery. Decreased level of VGLUT2 associated with activation of ERK1/2 and exocytosis proteins supposed activation of glutamate release in the hippocampus, while in the temporal cortex diminished activity of ERK1/2 and synapsin I associated with VGLUT2 up-regulation assumed inhibition of glutamatergic transmission. Our data let us supposed that decreasing of glutamate release in th& temporal cortex could be a trigger for the inhibition of hippocampal glutamatergic system and the beginning of further ataxia stage. Our data demonstrated correlation between expression and activity of exocytosis proteins and ERK1/2 mainly in the glutamategic neurons of the hippocampus and the temporal cortex that let us proposed significant role of ERK1/2 kinases as a positive regulator of glutamate release and as a result initiation of seizure expression. PMID:26827493

  5. The excitation and depression of spinal neurones by ibotenic acid.

    PubMed Central

    Curtis, D R; Lodge, D; McLennan, H

    1979-01-01

    1. The firing of spinal interneurones and Renshaw cells by microelectrophoretic (+/-)-ibotenate, which was approximately eight times more active as an excitant than L-glutamate, was followed by prolonged depression of the sensitivity of the neurones to excitant amino acids and acetylcholine. 2. The depression, which lasted for 15--30 min when ibotenate was ejected for 3--6 min, was blocked by the GABA-antagonist bicuculline methochloride, and was independent of prior firing since it occurred with subthreshold concentrations of ibotenate and when ibotenate firing had been blocked by DL-alpha-aminoadipate. 3. When administered electrophoretically for 5 min, muscimol, a potent GABA agonist, reduced neuronal excitability for prolonged periods and this effect was also prevented by bicuculline methochloride. 4. The depression of neuronal excitability produced by GABA, taurine, isoguvacine or 3-aminopropane sulphonate, ejected for periods of 5--6 min, recovered rapidly. 5. It is suggested that ibotenate is converted in vivo to muscimol or a related compound which has a prolonged, bicuculline-sensitive depressant action on the excitability of neurones. PMID:480204

  6. Synthesis of docosahexaenoic acid from eicosapentaenoic acid in retina neurons protects photoreceptors from oxidative stress.

    PubMed

    Simón, María Victoria; Agnolazza, Daniela L; German, Olga Lorena; Garelli, Andrés; Politi, Luis E; Agbaga, Martin-Paul; Anderson, Robert E; Rotstein, Nora P

    2016-03-01

    Oxidative stress is involved in activating photoreceptor death in several retinal degenerations. Docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in the retina, protects cultured retina photoreceptors from apoptosis induced by oxidative stress and promotes photoreceptor differentiation. Here, we investigated whether eicosapentaenoic acid (EPA), a metabolic precursor to DHA, had similar effects and whether retinal neurons could metabolize EPA to DHA. Adding EPA to rat retina neuronal cultures increased opsin expression and protected photoreceptors from apoptosis induced by the oxidants paraquat and hydrogen peroxide (H2 O2 ). Palmitic, oleic, and arachidonic acids had no protective effect, showing the specificity for DHA. We found that EPA supplementation significantly increased DHA percentage in retinal neurons, but not EPA percentage. Photoreceptors and glial cells expressed Δ6 desaturase (FADS2), which introduces the last double bond in DHA biosynthetic pathway. Pre-treatment of neuronal cultures with CP-24879 hydrochloride, a Δ5/Δ6 desaturase inhibitor, prevented EPA-induced increase in DHA percentage and completely blocked EPA protection and its effect on photoreceptor differentiation. These results suggest that EPA promoted photoreceptor differentiation and rescued photoreceptors from oxidative stress-induced apoptosis through its elongation and desaturation to DHA. Our data show, for the first time, that isolated retinal neurons can synthesize DHA in culture. Docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in retina photoreceptors, and its precursor, eicosapentaenoic acid (EPA) have multiple beneficial effects. Here, we show that retina neurons in vitro express the desaturase FADS2 and can synthesize DHA from EPA. Moreover, addition of EPA to these cultures protects photoreceptors from oxidative stress and promotes their differentiation through its metabolization to DHA. PMID:26662863

  7. Retinoic acid from the meninges regulates cortical neuron generation.

    PubMed

    Siegenthaler, Julie A; Ashique, Amir M; Zarbalis, Konstantinos; Patterson, Katelin P; Hecht, Jonathan H; Kane, Maureen A; Folias, Alexandra E; Choe, Youngshik; May, Scott R; Kume, Tsutomu; Napoli, Joseph L; Peterson, Andrew S; Pleasure, Samuel J

    2009-10-30

    Extrinsic signals controlling generation of neocortical neurons during embryonic life have been difficult to identify. In this study we demonstrate that the dorsal forebrain meninges communicate with the adjacent radial glial endfeet and influence cortical development. We took advantage of Foxc1 mutant mice with defects in forebrain meningeal formation. Foxc1 dosage and loss of meninges correlated with a dramatic reduction in both neuron and intermediate progenitor production and elongation of the neuroepithelium. Several types of experiments demonstrate that retinoic acid (RA) is the key component of this secreted activity. In addition, Rdh10- and Raldh2-expressing cells in the dorsal meninges were either reduced or absent in the Foxc1 mutants, and Rdh10 mutants had a cortical phenotype similar to the Foxc1 null mutants. Lastly, in utero RA treatment rescued the cortical phenotype in Foxc1 mutants. These results establish RA as a potent, meningeal-derived cue required for successful corticogenesis.

  8. Friedreich ataxia: failure of GABA-ergic and glycinergic synaptic transmission in the dentate nucleus.

    PubMed

    Koeppen, Arnulf H; Ramirez, R Liane; Becker, Alyssa B; Feustel, Paul J; Mazurkiewicz, Joseph E

    2015-02-01

    Atrophy of large neurons in the dentate nucleus (DN) is an important pathologic correlate of neurologic disability in patients with Friedreich ataxia (FA). Thinning of the DN was quantified in 29 autopsy cases of FA and 2 carriers by measuring the thickness of the gray matter ribbon on stains with anti-glutamic acid decarboxylase, the rate-limiting enzyme in the biosynthesis of γ-amino-butyric acid (GABA). The DN was thinner than normal in all cases of FA, and atrophy correlated inversely with disease duration but not with age at onset or length of the homozygous guanine-adenine-adenine trinucleotide expansions. In 13 of the FA cases, frozen DN tissue was available for assay of frataxin. Dentate nucleus atrophy was more severe when frataxin was very low. Immunohistochemical staining for glutamic acid decarboxylase revealed grumose reaction and preservation of small GABA-ergic neurons in the DN of FA patients. Residual small DN neurons and varicose axons also contained the glycine transporter 2, identifying them as glycinergic. Immunohistochemistry also confirmed severe loss of GABA-A and glycine receptors in the DN with comparable depletion of the receptor-anchoring protein gephyrin. Thus, loss of gephyrin and failure to position GABA-A and glycine receptors correctly may reduce trophic support of large DN neurons and contribute to their atrophy. By contrast, Purkinje cells may escape retrograde atrophy in FA by issuing new axonal sprouts to small surviving DN neurons where they form reparative grumose clusters.

  9. Development of early-born γ-Aminobutyric acid hub neurons in mouse hippocampus from embryogenesis to adulthood.

    PubMed

    Villette, Vincent; Guigue, Philippe; Picardo, Michel Aimé; Sousa, Vitor Hugo; Leprince, Erwan; Lachamp, Philippe; Malvache, Arnaud; Tressard, Thomas; Cossart, Rosa; Baude, Agnès

    2016-08-15

    Early-born γ-aminobutyric acid (GABA) neurons (EBGNs) are major components of the hippocampal circuit because at early postnatal stages they form a subpopulation of "hub cells" transiently supporting CA3 network synchronization (Picardo et al. [2011] Neuron 71:695-709). It is therefore essential to determine when these cells acquire the remarkable morphofunctional attributes supporting their network function and whether they develop into a specific subtype of interneuron into adulthood. Inducible genetic fate mapping conveniently allows for the labeling of EBGNs throughout their life. EBGNs were first analyzed during the perinatal week. We observed that EBGNs acquired mature characteristics at the time when the first synapse-driven synchronous activities appeared in the form of giant depolarizing potentials. The fate of EBGNs was next analyzed in the adult hippocampus by using anatomical characterization. Adult EBGNs included a significant proportion of cells projecting selectively to the septum; in turn, EBGNs were targeted by septal and entorhinal inputs. In addition, most EBGNs were strongly targeted by cholinergic and monoaminergic terminals, suggesting significant subcortical innervation. Finally, we found that some EBGNs located in the septum or the entorhinal cortex also displayed a long-range projection that we traced to the hippocampus. Therefore, this study shows that the maturation of the morphophysiological properties of EBGNs mirrors the evolution of early network dynamics, suggesting that both phenomena may be causally linked. We propose that a subpopulation of EBGNs forms into adulthood a scaffold of GABAergic projection neurons linking the hippocampus to distant structures. J. Comp. Neurol. 524:2440-2461, 2016. © 2016 Wiley Periodicals, Inc.

  10. Development of early‐born γ‐Aminobutyric acid hub neurons in mouse hippocampus from embryogenesis to adulthood

    PubMed Central

    Villette, Vincent; Guigue, Philippe; Picardo, Michel Aimé; Sousa, Vitor Hugo; Leprince, Erwan; Lachamp, Philippe; Malvache, Arnaud; Tressard, Thomas; Cossart, Rosa

    2016-01-01

    ABSTRACT Early‐born γ‐aminobutyric acid (GABA) neurons (EBGNs) are major components of the hippocampal circuit because at early postnatal stages they form a subpopulation of “hub cells” transiently supporting CA3 network synchronization (Picardo et al. [2011] Neuron 71:695–709). It is therefore essential to determine when these cells acquire the remarkable morphofunctional attributes supporting their network function and whether they develop into a specific subtype of interneuron into adulthood. Inducible genetic fate mapping conveniently allows for the labeling of EBGNs throughout their life. EBGNs were first analyzed during the perinatal week. We observed that EBGNs acquired mature characteristics at the time when the first synapse‐driven synchronous activities appeared in the form of giant depolarizing potentials. The fate of EBGNs was next analyzed in the adult hippocampus by using anatomical characterization. Adult EBGNs included a significant proportion of cells projecting selectively to the septum; in turn, EBGNs were targeted by septal and entorhinal inputs. In addition, most EBGNs were strongly targeted by cholinergic and monoaminergic terminals, suggesting significant subcortical innervation. Finally, we found that some EBGNs located in the septum or the entorhinal cortex also displayed a long‐range projection that we traced to the hippocampus. Therefore, this study shows that the maturation of the morphophysiological properties of EBGNs mirrors the evolution of early network dynamics, suggesting that both phenomena may be causally linked. We propose that a subpopulation of EBGNs forms into adulthood a scaffold of GABAergic projection neurons linking the hippocampus to distant structures. J. Comp. Neurol. 524:2440–2461, 2016. © 2016 Wiley Periodicals, Inc. PMID:26779909

  11. Responses from two firing patterns in inferior colliculus neurons to stimulation of the lateral lemniscus dorsal nucleus

    PubMed Central

    Li, Xiao-ting; Wang, Ning-yu; Wang, Yan-jun; Xu, Zhi-qing; Liu, Jin-feng; Bai, Yun-fei; Dai, Jin-sheng; Zhao, Jing-yi

    2016-01-01

    The γ-aminobutyric acid neurons (GABAergic neurons) in the inferior colliculus are classified into various patterns based on their intrinsic electrical properties to a constant current injection. Although this classification is associated with physiological function, the exact role for neurons with various firing patterns in acoustic processing remains poorly understood. In the present study, we analyzed characteristics of inferior colliculus neurons in vitro, and recorded responses to stimulation of the dorsal nucleus of the lateral lemniscus using the whole-cell patch clamp technique. Seven inferior colliculus neurons were tested and were classified into two firing patterns: sustained-regular (n = 4) and sustained-adapting firing patterns (n = 3). The majority of inferior colliculus neurons exhibited slight changes in response to stimulation and bicuculline. The responses of one neuron with a sustained-adapting firing pattern were suppressed after stimulation, but recovered to normal levels following application of the γ-aminobutyric acid receptor antagonist. One neuron with a sustained-regular pattern showed suppressed stimulation responses, which were not affected by bicuculline. Results suggest that GABAergic neurons in the inferior colliculus exhibit sustained-regular or sustained-adapting firing patterns. Additionally, GABAergic projections from the dorsal nucleus of the lateral lemniscus to the inferior colliculus are associated with sound localization. The different neuronal responses of various firing patterns suggest a role in sound localization. A better understanding of these mechanisms and functions will provide better clinical treatment paradigms for hearing deficiencies. PMID:27335563

  12. GABAergic inhibition and modifications of taste responses in the cortical taste area in rats.

    PubMed

    Ogawa, H; Hasegawa, K; Otawa, S; Ikeda, I

    1998-09-01

    Using multibarrel electrodes, recordings were made in the cortical taste area (CTA), specifically in the granular and dysgranular parts of the insular cortex (areas GI and DI), of urethane-anesthetized rats. The effects of an iontophoretic application of gamma-aminobutylic acid (GABA) and bicuculline methiodide (BMI), a specific antagonist to the GABA(A) receptor, were tested. GABA decreased background discharges in ca. 69% of 509 neurons in both areas, and in ca. 58% of 64 taste neurons. BMI antagonized the inhibitory action of GABA in CTA neurons and facilitated background discharges in ca. 51% of the 390 neurons tested, including ca. 69% of the 52 taste neurons, which indicates that CTA neurons have GABA(A) receptors to receive inhibitory inputs from interneurons. In both areas, the effects of BMI (6-20 nA) on taste responses of the 85 CTA neurons (49 and 36 in areas GI and DI, respectively) to the four basic taste stimuli were examined: 65 neurons were recognized in the absence of BMI, whereas 20 only in the presence of the drug. BMI increased taste responses in 25 of the former group and changed the type of their response profiles in 25 including 12 neurons whose responses were increased. It also changed the best stimulus in 34 neurons. The drug affected the receptive fields in almost all cases examined (n = 23) and increased the size in 78.2% when the value for all four basic taste stimuli were totaled. New receptive fields were uncovered by BMI in varying regions of the oral cavity depending on the taste stimulus. But the drug decreased taste responses in several neurons (n = 8). These findings indicate that the GABAergic inhibitory system apparently contributes to modifying or selecting taste information in both areas of the CTA. PMID:9831255

  13. The lathyrus toxin, {beta}-N-oxalyl-L-{alpha},{beta}-diaminopropionic acid (ODAP), and homocysteic acid sensitize CA1 pyramidal neurons to cystine and L-2-amino-6-phosphonohexanoic acid

    SciTech Connect

    Chase, L.A. . E-mail: chase@hope.edu; Peterson, N.L. . E-mail: nlpeterson@noctrl.edu; Koerner, J.F. . E-mail: koern003@umn.edu

    2007-02-15

    A brief exposure of hippocampal slices to L-quisqualic acid (QUIS) sensitizes CA1 pyramidal neurons 30- to 250-fold to depolarization by certain excitatory amino acids analogues, e.g., L-2-amino-6-phosphonohexanoic acid (L-AP6), and by the endogenous compound, L-cystine. This phenomenon has been termed QUIS sensitization. A mechanism similar to that previously described for QUIS neurotoxicity has been proposed to describe QUIS sensitization. Specifically, QUIS has been shown to be sequestered into GABAergic interneurons by the System x{sub c} {sup -} and subsequently released by heteroexchange with cystine or L-AP6, resulting in activation of non-NMDA receptors. We now report two additional neurotoxins, the Lathyrus excitotoxin, {beta}-N-oxalyl-L-{alpha},{beta}-diaminopropionic acid (ODAP), and the endogenous compound, L-homocysteic acid (HCA), sensitize CA1 hippocampal neurons > 50-fold to L-AP6 and > 10-fold to cystine in a manner similar to QUIS. While the cystine- or L-AP6-mediated depolarization can be inhibited by the non-NMDA receptor antagonist CNQX in ODAP- or QUIS-sensitized slices, the NMDA antagonist D-AP5 inhibits depolarization by cystine or L-AP6 in HCA-sensitized slices. Thus, HCA is the first identified NMDA agonist that induces phosphonate or cystine sensitization. Like QUIS sensitization, the sensitization evoked by either ODAP or HCA can be reversed by a subsequent exposure to 2 mM {alpha}-aminoadipic acid. Finally, we have demonstrated that there is a correlation between the potency of inducers for triggering phosphonate or cystine sensitivity and their affinities for System x{sub c} {sup -} and either the non-NMDA or NMDA receptor. Thus, the results of this study support our previous model of QUIS sensitization and have important implications for the mechanisms of neurotoxicity, neurolathyrism and hyperhomocystinemia.

  14. 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.

  15. Generation of late-born neurons in the ventral spinal cord requires the coordination of retinoic acid and Notch signaling.

    PubMed

    Ryu, Jae-Ho; Kong, Hee Jeong; Park, Jung Youn; Lim, Kyung-Eun; An, Cheul Min; Lee, Jehee; Yeo, Sang-Yeob

    2015-08-18

    Neural progenitor cells generate various types of neurons and glia in a tightly regulated manner. During primary neurogenesis, retinoic acid (RA) acts earlier than Notch signaling and regulates differentiation and proliferation by upregulating proneural and neurogenic genes in the neural plate. However, the relationship between Notch signaling and the retinoid pathway during late neurogenesis remains unclear. We investigated the role of Mindbomb (Mib)-mediated Notch signaling in the differentiation of neural progenitors during late neurogenesis by overexpressing Mib and administering RA to Tg[hsp70-Mib:EGFP]. The majority of cells in the p3 domain differentiated into GABAergic Kolmer-Agduhr (KA) cells in Tg[hsp70-mib:EGFP] embryos heat-shocked during late neurogenesis, whereas these phenotypes were suppressed by exogenous RA. Our observations suggest that Mib-mediated Notch signaling plays a critical role in the temporal differentiation of neural progenitors, and that the generation of late-born KA″ cells is regulated by the interplay between Mib and RA. PMID:26151587

  16. Acid sensing by sweet and bitter taste neurons in Drosophila melanogaster

    PubMed Central

    Charlu, Sandhya; Wisotsky, Zev; Medina, Adriana; Dahanukar, Anupama

    2013-01-01

    Drosophila melanogaster can taste various compounds and separate them into few basic categories such as sweet, bitter and salt taste. Here we investigate mechanisms underlying acid detection in Drosophila and report that the fly displays strong taste aversion to common carboxylic acids. We find that acid tastants act by the activation of a subset of bitter neurons and inhibition of sweet neurons. Bitter neurons begin to respond at pH 5 and show an increase in spike frequency as the extracellular pH drops, which does not rely on previously identified chemoreceptors. Notably, sweet neuron activity depends on the balance of sugar and acid tastant concentrations. This is independent of bitter neuron firing, and allows the fly to avoid acid-laced food sources even in the absence of functional bitter neurons. The two mechanisms may allow the fly to better evaluate the risk of ingesting acidic foods and modulate its feeding decisions accordingly. PMID:23783889

  17. Delays in GABAergic interneuron development and behavioral inhibition after prenatal stress.

    PubMed

    Lussier, Stephanie J; Stevens, Hanna E

    2016-10-01

    Prenatal stress is associated with altered behavioral, cognitive, and psychiatric outcomes in offspring. Due to the importance of GABAergic systems in normal development and in psychiatric disorders, prenatal stress effects on these neurons have been investigated in animal models. Prenatal stress delays GABAergic progenitor migration, but the significance of these early developmental disruptions for the continued development of GABAergic cells in the juvenile brain is unclear. Here, we examined effects of prenatal stress on populations of GABAergic neurons in juvenile and adult medial frontal cortex (mFC) and hippocampus through stereological counting, gene expression, and relevant anxiety-like and social behaviors. Postnatally, the total GABAergic cell number that peaks in adolescence showed altered trajectories in mFC and hippocampus. Parvalbumin neuron proportion in juvenile brain was altered by prenatal stress, but parvalbumin gene expression showed no differences. In adult brain, parvalbumin neuron proportions were altered by prenatal stress with opposite gene expression changes. Adult prenatally stressed offspring showed a lack of social preference on a three-chambered task, increased anxiety-like behavior on the elevated plus maze, and reduced center time in an open field. Despite a lack of significant group differences in adult total GABAergic cell populations, performance of these tasks was correlated with GABAergic populations in mFC and hippocampus. In conclusion, prenatal stress resulted in a delay in GABAergic cell number and maturation of the parvalbumin subtype. Influences of prenatal stress on GABAergic populations during developmentally dynamic periods and during adulthood may be relevant to the anxiety-like behaviors that occur after prenatal stress. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 1078-1091, 2016. PMID:26724783

  18. New GABAergic interneurons in the adult neocortex and striatum are generated from different precursors.

    PubMed

    Dayer, Alexandre G; Cleaver, Kathryn M; Abouantoun, Thamara; Cameron, Heather A

    2005-01-31

    Ongoing neurogenesis in the adult mammalian dentate gyrus and olfactory bulb is generally accepted, but its existence in other adult brain regions is highly controversial. We labeled newly born cells in adult rats with the S-phase marker bromodeoxyuridine (BrdU) and used neuronal markers to characterize new cells at different time points after cell division. In the neocortex and striatum, we found BrdU-labeled cells that expressed each of the eight neuronal markers. Their size as well as staining for gamma-aminobutyric acid (GABA), glutamic acid decarboxylase 67, calretinin and/or calbindin, suggest that new neurons in both regions are GABAergic interneurons. BrdU and doublecortin-immunoreactive (BrdU+/DCX+) cells were seen within the striatum, suggesting migration of immature neurons from the subventricular zone. Surprisingly, no DCX+ cells were found within the neocortex. NG2 immunoreactivity in some new neocortical neurons suggested that they may instead be generated from the NG2+ precursors that reside within the cortex itself.

  19. Afferents to the GABAergic tail of the ventral tegmental area in the rat.

    PubMed

    Kaufling, Jennifer; Veinante, Pierre; Pawlowski, Sophie A; Freund-Mercier, Marie-Jose; Barrot, Michel

    2009-04-20

    We previously showed that chronic psychostimulant exposure induces the transcription factor DeltaFosB in gamma-aminobutyric acid (GABA)ergic neurons of the caudal tier of the ventral tegmental area (VTA). This subregion was defined as the tail of the VTA (tVTA). In the present study, we showed that tVTA can also be visualized by analyzing FosB/DeltaFosB response following acute cocaine injection. This induction occurs in GABAergic neurons, as identified by glutamic acid decarboxylase (GAD) expression. To characterize tVTA further, we mapped its inputs by using the retrograde tracers Fluoro-Gold or cholera toxin B subunit. Retrogradely labeled neurons were observed in the medial prefrontal cortex, the lateral septum, the ventral pallidum, the bed nucleus of the stria terminalis, the substantia innominata, the medial and lateral preoptic areas, the lateral and dorsal hypothalamic areas, the lateral habenula, the intermediate layers of the superior colliculus, the dorsal raphe, the periaqueductal gray, and the mesencephalic and pontine reticular formation. Projections from the prefrontal cortex, the hypothalamus, and the lateral habenula to the tVTA were also shown by using the anterograde tracer biotinylated dextran amine (BDA). We showed that the central nucleus of the amygdala innervates the anterior extent of the VTA but not the tVTA. Moreover, the tVTA mainly receives non-aminergic inputs from the dorsal raphe and the locus coeruleus. Although the tVTA has a low density of dopaminergic neurons, its afferents are mostly similar to those targeting the rest of the VTA. This suggests that the tVTA can be considered as a VTA subregion despite its caudal location.

  20. GABAergic regulation of the HPA and HPG axes and the impact of stress on reproductive function.

    PubMed

    Camille Melón, Laverne; Maguire, Jamie

    2016-06-01

    The hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes are regulated by GABAergic signaling at the level of corticotropin-releasing hormone (CRH) and gonadotropin-releasing hormone (GnRH) neurons, respectively. Under basal conditions, activity of CRH and GnRH neurons are controlled in part by both phasic and tonic GABAergic inhibition, mediated by synaptic and extrasynaptic GABAA receptors (GABAARs), respectively. For CRH neurons, this tonic GABAergic inhibition is mediated by extrasynaptic, δ subunit-containing GABAARs. Similarly, a THIP-sensitive tonic GABAergic current has been shown to regulate GnRH neurons, suggesting a role for δ subunit-containing GABAARs; however, this remains to be explicitly demonstrated. GABAARs incorporating the δ subunit confer neurosteroid sensitivity, suggesting a potential role for neurosteroid modulation in the regulation of the HPA and HPG axes. Thus, stress-derived neurosteroids may contribute to the impact of stress on reproductive function. Interestingly, excitatory actions of GABA have been demonstrated in both CRH neurons at the apex of control of the HPA axis and in GnRH neurons which mediate the HPG axis, adding to the complexity for the role of GABAergic signaling in the regulation of these systems. Here we review the effects that stress has on GnRH neurons and HPG axis function alongside evidence supporting GABAARs as a major interface between the stress and reproductive axes.

  1. GABAergic regulation of the HPA and HPG axes and the impact of stress on reproductive function.

    PubMed

    Camille Melón, Laverne; Maguire, Jamie

    2016-06-01

    The hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes are regulated by GABAergic signaling at the level of corticotropin-releasing hormone (CRH) and gonadotropin-releasing hormone (GnRH) neurons, respectively. Under basal conditions, activity of CRH and GnRH neurons are controlled in part by both phasic and tonic GABAergic inhibition, mediated by synaptic and extrasynaptic GABAA receptors (GABAARs), respectively. For CRH neurons, this tonic GABAergic inhibition is mediated by extrasynaptic, δ subunit-containing GABAARs. Similarly, a THIP-sensitive tonic GABAergic current has been shown to regulate GnRH neurons, suggesting a role for δ subunit-containing GABAARs; however, this remains to be explicitly demonstrated. GABAARs incorporating the δ subunit confer neurosteroid sensitivity, suggesting a potential role for neurosteroid modulation in the regulation of the HPA and HPG axes. Thus, stress-derived neurosteroids may contribute to the impact of stress on reproductive function. Interestingly, excitatory actions of GABA have been demonstrated in both CRH neurons at the apex of control of the HPA axis and in GnRH neurons which mediate the HPG axis, adding to the complexity for the role of GABAergic signaling in the regulation of these systems. Here we review the effects that stress has on GnRH neurons and HPG axis function alongside evidence supporting GABAARs as a major interface between the stress and reproductive axes. PMID:26690789

  2. Histaminergic neurons protect the developing hippocampus from kainic acid-induced neuronal damage in an organotypic coculture system.

    PubMed

    Kukko-Lukjanov, Tiina-Kaisa; Soini, Sanna; Taira, Tomi; Michelsen, Kimmo A; Panula, Pertti; Holopainen, Irma E

    2006-01-25

    The central histaminergic neuron system inhibits epileptic seizures, which is suggested to occur mainly through histamine 1 (H1) and histamine 3 (H3) receptors. However, the importance of histaminergic neurons in seizure-induced cell damage is poorly known. In this study, we used an organotypic coculture system and confocal microscopy to examine whether histaminergic neurons, which were verified by immunohistochemistry, have any protective effect on kainic acid (KA)-induced neuronal damage in the developing hippocampus. Fluoro-Jade B, a specific marker for degenerating neurons, indicated that, after the 12 h KA (5 microM) treatment, neuronal damage was significantly attenuated in the hippocampus cultured together with the posterior hypothalamic slice containing histaminergic neurons [HI plus HY (POST)] when compared with the hippocampus cultured alone (HI) or with the anterior hypothalamus devoid of histaminergic neurons. Moreover, alpha-fluoromethylhistidine, an inhibitor of histamine synthesis, eliminated the neuroprotective effect in KA-treated HI plus HY (POST), and extracellularly applied histamine (1 nM to 100 microM) significantly attenuated neuronal damage only at 1 nM concentration in HI. After the 6 h KA treatment, spontaneous electrical activity registered in the CA1 subregion contained significantly less burst activity in HI plus HY (POST) than in HI. Finally, in KA-treated slices, the H3 receptor antagonist thioperamide enhanced the neuroprotective effect of histaminergic neurons, whereas the H1 receptor antagonists triprolidine and mepyramine dose-dependently decreased the neuroprotection in HI plus HY (POST). Our results suggest that histaminergic neurons protect the developing hippocampus from KA-induced neuronal damage, with regulation of neuronal survival being at least partly mediated through H1 and H3 receptors.

  3. Leptin Responsive and GABAergic Projections to the Rostral Preoptic Area in Mice.

    PubMed

    Zuure, W A; Quennell, J H; Anderson, G M

    2016-03-01

    The adipocyte-derived hormone leptin plays a critical role in the control of reproduction via signalling in hypothalamic neurones. The drivers of the hypothalamic-pituitary-gonadal axis, the gonadotrophin-releasing hormone (GnRH) neurones, do not have the receptors for leptin. Therefore, intermediate leptin responsive neurones must provide leptin-to-GnRH signalling. We investigated the populations of leptin responsive neurones that provide input to the rostral preoptic area (rPOA) where GnRH cell bodies reside. Fluorescent retrograde tracer beads (RetroBeads; Lumafluor Inc., Naples, FL, USA) were injected into the rPOA of transgenic leptin receptor enhanced green fluorescent protein (Lepr-eGFP) reporter mice. Uptake of the RetroBeads by Lepr-eGFP neurones was assessed throughout the hypothalamus. RetroBead uptake was most evident in the medial arcuate nucleus (ARC), the dorsomedial nucleus (DMN) and the ventral premammillary nucleus (PMV) of the hypothalamus. The uptake of RetroBeads specifically by Lepr-eGFP neurones was highest in the medial ARC (18% of tracer-labelled neurones Lepr-eGFP-positive). Because neurones that are both leptin responsive and GABAergic play a critical role in the regulation of fertility by leptin, we next focussed on the location of these populations. To address whether GABAergic neurones in leptin-responsive hypothalamic regions project to the rPOA, the experiment was repeated in GABA neurone reporter mice (Vgat-tdTomato). Between 10% and 45% of RetroBead-labelled neurones in the ARC were GABAergic, whereas uptake of tracer by GABAergic neurones in the DMN and PMV was very low (< 5%). These results show that both leptin responsive and GABAergic neurones from the ARC project to the region of the GnRH cell bodies. Our findings suggest that LEPR-expressing GABA neurones from the ARC may be mediators of leptin-to-GnRH signalling.

  4. GABAergic processes within the median preoptic nucleus promote NREM sleep.

    PubMed

    Benedetto, Luciana; Chase, Michael H; Torterolo, Pablo

    2012-06-15

    GABAergic mechanisms in the preoptic region of the hypothalamus (POA) have been implicated in the generation and maintenance of NREM (quiet) sleep. We recently reported that neurons in the median peptic nucleus (MnPN) in the POA of the cat are selectively activated during NREM sleep. In the present study, we explored the hypothesis that NREM sleep is controlled by GABAergic mechanisms within the MnPN. Consequently, adult cats were utilized to determine GABA immunorreactivity within the MnPN and to examine the effects on sleep of the microinjection of a GABA(A) agonist (muscimol) and a GABA(A) antagonist (bicuculline) into this area. GABAergic neurons were present throughout the MnPN. Compared with control microinjections, after the application of muscimol, the time spent in NREM sleep (59.8±7.5 min) and REM sleep (6.9±4.7 min) decreased compared with control microinjections (103.8±5.2 and 20.2±4.3 min, respectively; P<0.005). In contrast, bicuculline microinjections increased only NREM sleep time (103.0±23.0 vs 77.7±23.7 min; P<0.05). These results demonstrate that GABAergic processes within the MnPN are involved in the generation and maintenance of sleep, especially NREM sleep. PMID:22483998

  5. GABAergic processes within the median preoptic nucleus promote NREM sleep.

    PubMed

    Benedetto, Luciana; Chase, Michael H; Torterolo, Pablo

    2012-06-15

    GABAergic mechanisms in the preoptic region of the hypothalamus (POA) have been implicated in the generation and maintenance of NREM (quiet) sleep. We recently reported that neurons in the median peptic nucleus (MnPN) in the POA of the cat are selectively activated during NREM sleep. In the present study, we explored the hypothesis that NREM sleep is controlled by GABAergic mechanisms within the MnPN. Consequently, adult cats were utilized to determine GABA immunorreactivity within the MnPN and to examine the effects on sleep of the microinjection of a GABA(A) agonist (muscimol) and a GABA(A) antagonist (bicuculline) into this area. GABAergic neurons were present throughout the MnPN. Compared with control microinjections, after the application of muscimol, the time spent in NREM sleep (59.8±7.5 min) and REM sleep (6.9±4.7 min) decreased compared with control microinjections (103.8±5.2 and 20.2±4.3 min, respectively; P<0.005). In contrast, bicuculline microinjections increased only NREM sleep time (103.0±23.0 vs 77.7±23.7 min; P<0.05). These results demonstrate that GABAergic processes within the MnPN are involved in the generation and maintenance of sleep, especially NREM sleep.

  6. Ginseng Rb Fraction Protects Glia, Neurons and Cognitive Function in a Rat Model of Neurodegeneration

    PubMed Central

    Wang, Yan; Ling, Peng; Xie, Xin; Jiang, Chenyao; Zhang, Zhizhen; Lian, Xiao-Yuan

    2014-01-01

    The loss and injury of neurons play an important role in the onset of various neurodegenerative diseases, while both microgliosis and astrocyte loss or dysfunction are significant causes of neuronal degeneration. Previous studies have suggested that an extract enriched panaxadiol saponins from ginseng has more neuroprotective potential than the total saponins of ginseng. The present study investigated whether a fraction of highly purified panaxadiol saponins (termed as Rb fraction) was protective for both glia and neurons, especially GABAergic interneurons, against kainic acid (KA)-induced excitotoxicity in rats. Rats received Rb fraction at 30 mg/kg (ip), 40 mg/kg (ip or saline followed 40 min later by an intracerebroventricular injection of KA. Acute hippocampal injury was determined at 48 h after KA, and impairment of hippocampus-dependent learning and memory as well as delayed neuronal injury was determined 16 to 21 days later. KA injection produced significant acute hippocampal injuries, including GAD67-positive GABAergic interneuron loss in CA1, paralbumin (PV)-positive GABAergic interneuron loss, pyramidal neuron degeneration and astrocyte damage accompanied with reactive microglia in both CA1 and CA3 regions of the hippocampus. There was also a delayed loss of GAD67-positive interneurons in CA1, CA3, hilus and dentate gyrus. Microgliosis also became more severe 21 days later. Accordingly, KA injection resulted in hippocampus-dependent spatial memory impairment. Interestingly, the pretreatment with Rb fraction at 30 or 40 mg/kg significantly protected the pyramidal neurons and GABAergic interneurons against KA-induced acute excitotoxicity and delayed injury. Rb fraction also prevented memory impairments and protected astrocytes from KA-induced acute excitotoxicity. Additionally, microglial activation, especially the delayed microgliosis, was inhibited by Rb fraction. Overall, this study demonstrated that Rb fraction protected both astrocytes and neurons

  7. Glutamatergic neurons are present in the rat ventral tegmental area

    PubMed Central

    Yamaguchi, Tsuyoshi; Sheen, Whitney; Morales, Marisela

    2010-01-01

    The ventral tegmental area (VTA) is thought to play an important role in reward function. Two populations of neurons, containing either dopamine (DA) or γ-amino butyric acid (GABA), have been extensively characterized in this area. However, recent electrophysiological studies are consistent with the notion that neurons that utilize neurotransmitters other than DA or GABA are likely to be present in the VTA. Given the pronounced phenotypic diversity of neurons in this region, we have proposed that additional cell types, such as those that express the neurotransmitter glutamate may also be present in this area. Thus, by using in situ hybridization histochemistry we investigated whether transcripts encoded by genes for the two vesicular glutamate transporters, VGluT1 or VGluT2, were expressed in the VTA. We found that VGluT2 mRNA but not VGluT1 mRNA is expressed in the VTA. Neurons expressing VGluT2 mRNA were differentially distributed throughout the rostro-caudal and medio-lateral aspects of the VTA, with the highest concentration detected in rostro-medial areas. Phenotypic characterization with double in situ hybridization of these neurons indicated that they rarely co–expressed mRNAs for tyrosine hydroxylase (TH, marker for DAergic neurons) or glutamic acid decarboxylase (GAD, marker for GABAergic neurons). Based on the results described here, we concluded that the VTA contains glutamatergic neurons that in their vast majority are clearly non-DAergic and non-GABAergic. PMID:17241272

  8. Colocalization of gamma-aminobutyric acid and acetylcholine in neurons in the laterodorsal and pedunculopontine tegmental nuclei in the cat: a light and electron microscopic study.

    PubMed

    Jia, Hong-Ge; Yamuy, Jack; Sampogna, Sharon; Morales, Francisco R; Chase, Michael H

    2003-12-01

    Cholinergic and gamma-aminobutyric acid (GABA) mechanisms in the dorsolateral pontomesencephalic tegmentum have been implicated in the control of active (REM) sleep and wakefulness. To determine the relationships between neurons that contain these neurotransmitters in this region of the brainstem in adult cats, combined light and electron microscopic immunocytochemical procedures were employed. Light microscopic analyses revealed that choline acetyltransferase (ChAT) and GABA immunoreactive neurons were distributed throughout the laterodorsal and pedunculopontine tegmental nuclei (LDT and PPT). Surprisingly, approximately 50% of the ChAT immunoreactive neurons in these nuclei also contained GABA. Using electron microscopic pre-embedding immunocytochemistry, GABA immunoreactivity was observed in somas, dendrites and axon terminals in both the LDT and PPT. Most of the GABA immunoreactive terminals formed symmetrical synapses with non-immunolabeled dendrites. Electron microscopic double-immunolabeling techniques revealed that ChAT and GABA were colocalized in axon terminals in the LDT/PPT. Approximately 30% of the ChAT immunoreactive terminals were also GABA immunoreactive, whereas only 6-8% of the GABA immunoreactive terminals were ChAT immunoreactive. Most of the ChAT/GABA immunoreactive terminals formed symmetrical synapses with non-immunolabeled dendrites; however, ChAT/GABA immunoreactive terminals were also observed that contacted ChAT immunoreactive dendrites. With respect to ChAT immunoreactive postsynaptic profiles, approximately 40% of the somas and 50% of the dendrites received synaptic contact from GABA immunoreactive terminals in both the LDT and PPT. These findings (a) indicate that there are fundamental interactions between cholinergic and GABAergic neurons within the LDT/PPT that play an important role in the control of active sleep and wakefulness and (b) provide an anatomical basis for the intriguing possibility that a mechanism of acetylcholine and

  9. Trajectory of the main GABAergic interneuron populations from early development to old age in the rat primary auditory cortex.

    PubMed

    Ouellet, Lydia; de Villers-Sidani, Etienne

    2014-01-01

    In both humans and rodents, decline in cognitive function is a hallmark of the aging process; the basis for this decrease has yet to be fully characterized. However, using aged rodent models, deficits in auditory processing have been associated with significant decreases in inhibitory signaling attributed to a loss of GABAergic interneurons. Not only are these interneurons crucial for pattern detection and other large-scale population dynamics, but they have also been linked to mechanisms mediating plasticity and learning, making them a prime candidate for study and modeling of modifications to cortical communication pathways in neurodegenerative diseases. Using the rat primary auditory cortex (A1) as a model, we probed the known markers of GABAergic interneurons with immunohistological methods, using antibodies against gamma aminobutyric acid (GABA), parvalbumin (PV), somatostatin (SOM), calretinin (CR), vasoactive intestinal peptide (VIP), choline acetyltransferase (ChAT), neuropeptide Y (NPY), and cholecystokinin (CCK) to document the changes observed in interneuron populations across the rat's lifespan. This analysis provided strong evidence that several but not all GABAergic neurons were affected by the aging process, showing most dramatic changes in expression of parvalbumin (PV) and somatostatin (SOM) expression. With this evidence, we show how understanding these trajectories of cell counts may be factored into a simple model to quantify changes in inhibitory signaling across the course of life, which may be applied as a framework for creating more advanced simulations of interneuronal implication in normal cerebral processing, normal aging, or pathological processes.

  10. Developmental downregulation of GABAergic drive parallels formation of functional synapses in cultured mouse neocortical networks.

    PubMed

    Klueva, Julia; Meis, Susanne; de Lima, Ana D; Voigt, Thomas; Munsch, Thomas

    2008-06-01

    Networks of cortical neurons in vitro spontaneously develop synchronous oscillatory electrical activity at around the second week in culture. However, the underlying mechanisms and in particular the role of GABAergic interneurons in initiation and synchronization of oscillatory activity in developing cortical networks remain elusive. Here, we examined the intrinsic properties and the development of GABAergic and glutamatergic input onto presumed projection neurons (PNs) and large interneurons (L-INs) in cortical cultures of GAD67-GFP mice. Cultures developed spontaneous synchronous activity already at 5-7 days in vitro (DIV), as revealed by imaging transient changes in Fluo-3 fluorescence. Concurrently, spontaneous glutamate-mediated and GABA(A)-mediated postsynaptic currents (sPSCs) occured at 5 DIV. For both types of neurons the frequency of glutamatergic and GABAergic sPSCs increased with DIV, whereas the charge transfer of glutamatergic sPSCs increased and the charge transfer of GABAergic sPSCs decreased with cultivation time. The ratio between GABAergic and the overall charge transfer was significantly reduced with DIV for L-INs and PNs, indicating an overall reduction in GABAergic synaptic drive with maturation of the network. In contrast, analysis of miniature PSCs (mPSCs) revealed no significant changes of charge transfer with DIV for both types of neurons, indicating that the reduction in GABAergic drive was not due to a decreased number of functional synapses. Our data suggest that the global reduction in GABAergic synaptic drive together with more synaptic input to PNs and L-INs during maturation may enhance rhythmogenesis of the network and increase the synchronization at the level of population bursts. PMID:18361402

  11. GABAergic and glycinergic inhibitory synaptic transmission in the ventral cochlear nucleus studied in VGAT channelrhodopsin-2 mice.

    PubMed

    Xie, Ruili; Manis, Paul B

    2014-01-01

    Both glycine and GABA mediate inhibitory synaptic transmission in the ventral cochlear nucleus (VCN). In mice, the time course of glycinergic inhibition is slow in bushy cells and fast in multipolar (stellate) cells, and is proposed to contribute to the processing of temporal cues in both cell types. Much less is known about GABAergic synaptic transmission in this circuit. Electrical stimulation of the auditory nerve or the tuberculoventral pathway evokes little GABAergic synaptic current in brain slice preparations, and spontaneous GABAergic miniature synaptic currents occur infrequently. To investigate synaptic currents carried by GABA receptors in bushy and multipolar cells, we used transgenic mice in which channelrhodopsin-2 and EYFP is driven by the vesicular GABA transporter (VGAT-ChR2-EYFP) and is expressed in both GABAergic and glycinergic neurons. Light stimulation evoked action potentials in EYFP-expressing presynaptic cells, and evoked inhibitory postsynaptic potentials (IPSPs) in non-expressing bushy and planar multipolar cells. Less than 10% of the IPSP amplitude in bushy cells arose from GABAergic synapses, whereas 40% of the IPSP in multipolar neurons was GABAergic. In voltage clamp, glycinergic IPSCs were significantly slower in bushy neurons than in multipolar neurons, whereas there was little difference in the kinetics of the GABAergic IPSCs between two cell types. During prolonged stimulation, the ratio of steady state vs. peak IPSC amplitude was significantly lower for glycinergic IPSCs. Surprisingly, the reversal potentials of GABAergic IPSCs were negative to those of glycinergic IPSCs in both bushy and multipolar neurons. In the absence of receptor blockers, repetitive light stimulation was only able to effectively evoke IPSCs up to 20 Hz in both bushy and multipolar neurons. We conclude that local GABAergic release within the VCN can differentially influence bushy and multipolar cells.

  12. Leptin potentiates GABAergic synaptic transmission in the developing rodent hippocampus

    PubMed Central

    Guimond, Damien; Diabira, Diabe; Porcher, Christophe; Bader, Francesca; Ferrand, Nadine; Zhu, Mingyan; Appleyard, Suzanne M.; Wayman, Gary A.; Gaiarsa, Jean-Luc

    2014-01-01

    It is becoming increasingly clear that leptin is not only a hormone regulating energy homeostasis but also a neurotrophic factor impacting a number of brain regions, including the hippocampus. Although leptin promotes the development of GABAergic transmission in the hypothalamus, little is known about its action on the GABAergic system in the hippocampus. Here we show that leptin modulates GABAergic transmission onto developing CA3 pyramidal cells of newborn rats. Specifically, leptin induces a long-lasting potentiation (LLP-GABAA) of miniature GABAA receptor-mediated postsynaptic current (GABAA-PSC) frequency. Leptin also increases the amplitude of evoked GABAA-PSCs in a subset of neurons along with a decrease in the coefficient of variation and no change in the paired-pulse ratio, pointing to an increased recruitment of functional synapses. Adding pharmacological blockers to the recording pipette showed that the leptin-induced LLP-GABAA requires postsynaptic calcium released from internal stores, as well as postsynaptic MAPK/ERK kinases 1 and/or 2 (MEK1/2), phosphoinositide 3 kinase (PI3K) and calcium-calmodulin kinase kinase (CaMKK). Finally, study of CA3 pyramidal cells in leptin-deficient ob/ob mice revealed a reduction in the basal frequency of miniature GABAA-PSCs compared to wild type littermates. In addition, presynaptic GAD65 immunostaining was reduced in the CA3 stratum pyramidale of mutant animals, both results converging to suggest a decreased number of functional GABAergic synapses in ob/ob mice. Overall, these results show that leptin potentiates and promotes the development of GABAergic synaptic transmission in the developing hippocampus likely via an increase in the number of functional synapses, and provide insights into the intracellular pathways mediating this effect. This study further extends the scope of leptin's neurotrophic action to a key regulator of hippocampal development and function, namely GABAergic transmission. PMID:25177272

  13. Dopamine synapse is a neuroligin-2-mediated contact between dopaminergic presynaptic and GABAergic postsynaptic structures.

    PubMed

    Uchigashima, Motokazu; Ohtsuka, Toshihisa; Kobayashi, Kazuto; Watanabe, Masahiko

    2016-04-12

    Midbrain dopamine neurons project densely to the striatum and form so-called dopamine synapses on medium spiny neurons (MSNs), principal neurons in the striatum. Because dopamine receptors are widely expressed away from dopamine synapses, it remains unclear how dopamine synapses are involved in dopaminergic transmission. Here we demonstrate that dopamine synapses are contacts formed between dopaminergic presynaptic and GABAergic postsynaptic structures. The presynaptic structure expressed tyrosine hydroxylase, vesicular monoamine transporter-2, and plasmalemmal dopamine transporter, which are essential for dopamine synthesis, vesicular filling, and recycling, but was below the detection threshold for molecules involving GABA synthesis and vesicular filling or for GABA itself. In contrast, the postsynaptic structure of dopamine synapses expressed GABAergic molecules, including postsynaptic adhesion molecule neuroligin-2, postsynaptic scaffolding molecule gephyrin, and GABAA receptor α1, without any specific clustering of dopamine receptors. Of these, neuroligin-2 promoted presynaptic differentiation in axons of midbrain dopamine neurons and striatal GABAergic neurons in culture. After neuroligin-2 knockdown in the striatum, a significant decrease of dopamine synapses coupled with a reciprocal increase of GABAergic synapses was observed on MSN dendrites. This finding suggests that neuroligin-2 controls striatal synapse formation by giving competitive advantage to heterologous dopamine synapses over conventional GABAergic synapses. Considering that MSN dendrites are preferential targets of dopamine synapses and express high levels of dopamine receptors, dopamine synapse formation may serve to increase the specificity and potency of dopaminergic modulation of striatal outputs by anchoring dopamine release sites to dopamine-sensing targets. PMID:27035941

  14. GABAergic parafacial zone is a medullary slow–wave–sleep promoting center

    PubMed Central

    Anaclet, Christelle; Ferrari, Loris; Arrigoni, Elda; Bass, Caroline E.; Saper, Clifford B.

    2014-01-01

    Work in animals and humans suggest the existence of a slow–wave sleep (SWS) promoting/EEG synchronizing center in the mammalian lower brainstem. While sleep–active GABAergic neurons in the medullary parafacial zone (PZ) are needed for normal SWS, it remains unclear if these neurons can initiate and maintain SWS or EEG slow wave activity (SWA) in behaving mice. We used genetically targeted activation and optogenetic–based mapping to uncover the downstream circuitry engaged by SWS–promoting PZ neurons, and we show that this circuit uniquely and potently initiates SWS and EEG SWA, regardless of the time of day. PZ neurons monosynaptically innervate and release synaptic GABA onto parabrachial neurons that in turn project to and release synaptic glutamate onto cortically–projecting neurons of the magnocellular basal forebrain; hence a circuit substrate is in place through which GABAergic PZ neurons can potently trigger SWS and modulate the cortical EEG. PMID:25129078

  15. 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

  16. STEREOLOGICAL ESTIMATES OF THE BASAL FOREBRAIN CELL POPULATION IN THE RAT, INCLUDING NEURONS CONTAINING CHOLINE ACETYLTRANSFERASE (ChAT), GLUTAMIC ACID DECARBOXYLASE (GAD) OR PHOSPHATE-ACTIVATED GLUTAMINASE (PAG) AND COLOCALIZING VESICULAR GLUTAMATE TRANSPORTERS (VGluTs)

    PubMed Central

    GRITTI, I.; HENNY, P.; GALLONI, F.; MAINVILLE, L.; MARIOTTI, M.; JONES, B. E.

    2006-01-01

    The basal forebrain (BF) plays an important role in modulating cortical activity and influencing attention, learning and memory. These activities are fulfilled importantly yet not entirely by cholinergic neurons. Noncholinergic neurons also contribute and are comprised by GABAergic neurons and other possibly glutamatergic neurons. The aim of the present study was to estimate the total number of cells in the BF of the rat and the proportions of that total represented by cholinergic, GABAergic and glutamatergic neurons. For this purpose, cells were counted using unbiased stereological methods within the medial septum, diagonal band, magnocellular preoptic nucleus, substantia innominata and globus pallidus in sections stained for Nissl substance and/or the neurotransmitter enzymes, choline acetyltransferase (ChAT), glutamic acid decarboxylase (GAD) or phosphate-activated glutaminase (PAG). In Nissl-stained sections, the total number of neurons in the BF was estimated as ~355,000 and the numbers of ChAT-immuno-positive (+) as ~22,000, GAD+ ~119,000 and PAG+ ~316,000, corresponding to ~5%, ~35% and ~90% of the total. Thus, of the large population of BF neurons, only a small proportion has the capacity to synthesize acetylcholine (ACh), one third to synthesize GABA and the vast majority to synthesize glutamate (Glu). Moreover, through the presence of PAG, a proportion of ACh- and GABA-synthesizing neurons also have the capacity to synthesize Glu. In sections dual fluorescent immunostained for vesicular transporters, VGluT3 and not VGluT2 was present in the cell bodies of most PAG+ and ChAT+ and half the GAD+ cells. Given previous results showing that VGluT2 and not VGluT3 was present in BF axon terminals and not colocalized with VAChT or VGAT, we conclude that the BF cell population influences cortical and subcortical regions through neurons which release ACh, GABA or Glu from their terminals but which in part can also synthesize and release Glu from their soma or

  17. FOXP2 drives neuronal differentiation by interacting with retinoic acid signaling pathways

    PubMed Central

    Devanna, Paolo; Middelbeek, Jeroen; Vernes, Sonja C.

    2014-01-01

    FOXP2 was the first gene shown to cause a Mendelian form of speech and language disorder. Although developmentally expressed in many organs, loss of a single copy of FOXP2 leads to a phenotype that is largely restricted to orofacial impairment during articulation and linguistic processing deficits. Why perturbed FOXP2 function affects specific aspects of the developing brain remains elusive. We investigated the role of FOXP2 in neuronal differentiation and found that FOXP2 drives molecular changes consistent with neuronal differentiation in a human model system. We identified a network of FOXP2 regulated genes related to retinoic acid signaling and neuronal differentiation. FOXP2 also produced phenotypic changes associated with neuronal differentiation including increased neurite outgrowth and reduced migration. Crucially, cells expressing FOXP2 displayed increased sensitivity to retinoic acid exposure. This suggests a mechanism by which FOXP2 may be able to increase the cellular differentiation response to environmental retinoic acid cues for specific subsets of neurons in the brain. These data demonstrate that FOXP2 promotes neuronal differentiation by interacting with the retinoic acid signaling pathway and regulates key processes required for normal circuit formation such as neuronal migration and neurite outgrowth. In this way, FOXP2, which is found only in specific subpopulations of neurons in the brain, may drive precise neuronal differentiation patterns and/or control localization and connectivity of these FOXP2 positive cells. PMID:25309332

  18. FOXP2 drives neuronal differentiation by interacting with retinoic acid signaling pathways.

    PubMed

    Devanna, Paolo; Middelbeek, Jeroen; Vernes, Sonja C

    2014-01-01

    FOXP2 was the first gene shown to cause a Mendelian form of speech and language disorder. Although developmentally expressed in many organs, loss of a single copy of FOXP2 leads to a phenotype that is largely restricted to orofacial impairment during articulation and linguistic processing deficits. Why perturbed FOXP2 function affects specific aspects of the developing brain remains elusive. We investigated the role of FOXP2 in neuronal differentiation and found that FOXP2 drives molecular changes consistent with neuronal differentiation in a human model system. We identified a network of FOXP2 regulated genes related to retinoic acid signaling and neuronal differentiation. FOXP2 also produced phenotypic changes associated with neuronal differentiation including increased neurite outgrowth and reduced migration. Crucially, cells expressing FOXP2 displayed increased sensitivity to retinoic acid exposure. This suggests a mechanism by which FOXP2 may be able to increase the cellular differentiation response to environmental retinoic acid cues for specific subsets of neurons in the brain. These data demonstrate that FOXP2 promotes neuronal differentiation by interacting with the retinoic acid signaling pathway and regulates key processes required for normal circuit formation such as neuronal migration and neurite outgrowth. In this way, FOXP2, which is found only in specific subpopulations of neurons in the brain, may drive precise neuronal differentiation patterns and/or control localization and connectivity of these FOXP2 positive cells.

  19. GABAergic and Glutamatergic Efferents of the Mouse Ventral Tegmental Area

    PubMed Central

    Taylor, Seth R; Badurek, Sylvia; DiLeone, Ralph J; Nashmi, Raad; Minichiello, Liliana; Picciotto, Marina R

    2014-01-01

    The role of dopaminergic (DA) projections from the ventral tegmental area (VTA) in appetitive and rewarding behavior has been widely studied, but the VTA also has documented DA-independent functions. Several drugs of abuse, including nicotine, act on VTA GABAergic neurons, and most studies have focused on local inhibitory connections. Relatively little is known about VTA GABA projection neurons and their connections to brain sites outside the VTA. In this study, we employed viral-vector mediated cell-type specific anterograde tracing, classical retrograde tracing and immunohistochemistry to characterize VTA GABA efferents throughout the brain. We found that VTA GABA neurons project widely to forebrain and brainstem targets, including the ventral pallidum, lateral and magnocellular preoptic nuclei, lateral hypothalamus and lateral habenula. Minor projections also go to central amygdala, mediodorsal thalamus, dorsal raphe and deep mesencephalic nuclei, and sparse projections go to prefrontal cortical regions and to nucleus accumbens shell and core. Importantly, these projections differ from the major VTA DA target regions. Retrograde tracing studies confirmed results from the anterograde experiments and differences in projections from VTA subnuclei. Retrogradely-labeled GABA neurons were not numerous and most non-TH/retrogradely labeled cells lacked GABAergic markers. Many non-DA/retrogradely labeled cells projecting to several areas express VGluT2. VTA GABA and glutamate neurons project throughout the brain, most prominently to regions with reciprocal connections to the VTA. These data indicate that VTA GABA and glutamate neurons may have more dopamine-independent functions than previously recognized. PMID:24715505

  20. Neto2-null mice have impaired GABAergic inhibition and are susceptible to seizures

    PubMed Central

    Mahadevan, Vivek; Dargaei, Zahra; Ivakine, Evgueni A.; Hartmann, Anna-Maria; Ng, David; Chevrier, Jonah; Ormond, Jake; Nothwang, Hans Gerd; McInnes, Roderick R.; Woodin, Melanie A.

    2015-01-01

    Neto2 is a transmembrane protein that interacts with the neuron-specific K+-Cl− cotransporter (KCC2) in the central nervous system (CNS). Efficient KCC2 transport is essential for setting the neuronal Cl− gradient, which is required for fast GABAergic inhibition. Neto2 is required to maintain the normal abundance of KCC2 in neurons, and increases KCC2 function by binding to the active oligomeric form of this cotransporter. In the present study, we characterized GABAergic inhibition and KCC2-mediated neuronal chloride homeostasis in pyramidal neurons from adult hippocampal slices. Using gramicidin perforated patch clamp recordings we found that the reversal potential for GABA (EGABA) was significantly depolarized. We also observed that surface levels of KCC2 and phosphorylation of KCC2 serine 940 (Ser940) were reduced in Neto2−/− neurons compared to wild-type controls. To examine GABAergic inhibition we recorded spontaneous inhibitory postsynaptic currents (sIPSCs) and found that Neto2−/− neurons had significant reductions in both their amplitude and frequency. Based on the critical role of Neto2 in regulating GABAergic inhibition we rationalized that Neto2-null mice would be prone to seizure activity. We found that Neto2-null mice demonstrated a decrease in the latency to pentylenetetrazole (PTZ)-induced seizures and an increase in seizure severity. PMID:26441539

  1. Pre & Postsynaptic Tuning of Action Potential Timing by Spontaneous GABAergic Activity

    PubMed Central

    Caillard, Olivier

    2011-01-01

    Frequency and timing of action potential discharge are key elements for coding and transfer of information between neurons. The nature and location of the synaptic contacts, the biophysical parameters of the receptor-operated channels and their kinetics of activation are major determinants of the firing behaviour of each individual neuron. Ultimately the intrinsic excitability of each neuron determines the input-output function. Here we evaluate the influence of spontaneous GABAergic synaptic activity on the timing of action potentials in Layer 2/3 pyramidal neurones in acute brain slices from the somatosensory cortex of young rats. Somatic dynamic current injection to mimic synaptic input events was employed, together with a simple computational model that reproduce subthreshold membrane properties. Besides the well-documented control of neuronal excitability, spontaneous background GABAergic activity has a major detrimental effect on spike timing. In fact, GABAA receptors tune the relationship between the excitability and fidelity of pyramidal neurons via a postsynaptic (the reversal potential for GABAA activity) and a presynaptic (the frequency of spontaneous activity) mechanism. GABAergic activity can decrease or increase the excitability of pyramidal neurones, depending on the difference between the reversal potential for GABAA receptors and the threshold for action potential. In contrast, spike time jitter can only be increased proportionally to the difference between these two membrane potentials. Changes in excitability by background GABAergic activity can therefore only be associated with deterioration of the reliability of spike timing. PMID:21789249

  2. Neto2-null mice have impaired GABAergic inhibition and are susceptible to seizures.

    PubMed

    Mahadevan, Vivek; Dargaei, Zahra; Ivakine, Evgueni A; Hartmann, Anna-Maria; Ng, David; Chevrier, Jonah; Ormond, Jake; Nothwang, Hans Gerd; McInnes, Roderick R; Woodin, Melanie A

    2015-01-01

    Neto2 is a transmembrane protein that interacts with the neuron-specific K(+)-Cl(-) cotransporter (KCC2) in the central nervous system (CNS). Efficient KCC2 transport is essential for setting the neuronal Cl(-) gradient, which is required for fast GABAergic inhibition. Neto2 is required to maintain the normal abundance of KCC2 in neurons, and increases KCC2 function by binding to the active oligomeric form of this cotransporter. In the present study, we characterized GABAergic inhibition and KCC2-mediated neuronal chloride homeostasis in pyramidal neurons from adult hippocampal slices. Using gramicidin perforated patch clamp recordings we found that the reversal potential for GABA (EGABA) was significantly depolarized. We also observed that surface levels of KCC2 and phosphorylation of KCC2 serine 940 (Ser940) were reduced in Neto2(-/-) neurons compared to wild-type controls. To examine GABAergic inhibition we recorded spontaneous inhibitory postsynaptic currents (sIPSCs) and found that Neto2(-/-) neurons had significant reductions in both their amplitude and frequency. Based on the critical role of Neto2 in regulating GABAergic inhibition we rationalized that Neto2-null mice would be prone to seizure activity. We found that Neto2-null mice demonstrated a decrease in the latency to pentylenetetrazole (PTZ)-induced seizures and an increase in seizure severity. PMID:26441539

  3. Implications of GABAergic Neurotransmission in Alzheimer’s Disease

    PubMed Central

    Li, Yanfang; Sun, Hao; Chen, Zhicai; Xu, Huaxi; Bu, Guojun; Zheng, Hui

    2016-01-01

    Alzheimer’s disease (AD) is characterized pathologically by the deposition of β-amyloid peptides (Aβ) and the accumulation of neurofibrillary tangles (NFTs) composed of hyper-phosphorylated tau. Regardless of the pathological hallmarks, synaptic dysfunction is widely accepted as a causal event in AD. Of the two major types of synapses in the central nervous system (CNS): glutamatergic and GABAergic, which provide excitatory and inhibitory outputs respectively, abundant data implicate an impaired glutamatergic system during disease progression. However, emerging evidence supports the notion that disrupted default neuronal network underlies impaired memory, and that alterations of GABAergic circuits, either plays a primary role or as a compensatory response to excitotoxicity, may also contribute to AD by disrupting the overall network function. The goal of this review is to provide an overview of the involvement of Aβ, tau and apolipoprotein E4 (apoE4), the major genetic risk factor in late-onset AD (LOAD), in GABAergic neurotransmission and the potential of modulating the GABAergic function as AD therapy. PMID:26941642

  4. Extracellular pH modulates GABAergic neurotransmission in rat hypothalamus.

    PubMed

    Chen, Z L; Huang, R Q

    2014-06-20

    Changes in extracellular pH have a modulatory effect on GABAA receptor function. It has been reported that pH sensitivity of the GABA receptor is dependent on subunit composition and GABA concentration. Most of previous investigations focused on GABA-evoked currents, which only reflect the postsynaptic receptors. The physiological relevance of pH modulation of GABAergic neurotransmission is not fully elucidated. In the present studies, we examined the influence of extracellular pH on the GABAA receptor-mediated inhibitory neurotransmission in rat hypothalamic neurons. The inhibitory postsynaptic currents (IPSCs), tonic currents, and the GABA-evoked currents were recorded with whole-cell patch techniques on the hypothalamic slices from Sprague-Dawley rats at 15-26 postnatal days. The amplitude and frequency of spontaneous GABA IPSCs were significantly increased while the external pH was changed from 7.3 to 8.4. In the acidic pH (6.4), the spontaneous GABA IPSCs were reduced in amplitude and frequency. The pH induced changes in miniature GABA IPSCs (mIPSCs) similar to that in spontaneous IPSCs. The pH effect on the postsynaptic GABA receptors was assessed with exogenously applied varying concentrations of GABA. The tonic currents and the currents evoked by sub-saturating concentration of GABA ([GABA]) (10 μM) were inhibited by acidic pH and potentiated by alkaline pH. In contrast, the currents evoked by saturating [GABA] (1mM) were not affected by pH changes. We also investigated the influence of pH buffers and buffering capacity on pH sensitivity of GABAA receptors on human recombinant α1β2γ2 GABAA receptors stably expressed in HEK 293 cells. The pH influence on GABAA receptors was similar in HEPES- and MES-buffered media, and not dependent on protonated buffers, suggesting that the observed pH effect on GABA response is a specific consequence of changes in extracellular protons. Our data suggest that the hydrogen ions suppress the GABAergic neurotransmission

  5. Energy substrates to support glutamatergic and GABAergic synaptic function: role of glycogen, glucose and lactate.

    PubMed

    Schousboe, Arne; Bak, Lasse K; Sickmann, Helle M; Sonnewald, Ursula; Waagepetersen, Helle S

    2007-12-01

    Maintenance of glutamatergic and GABAergic activity requires a continuous supply of energy since the exocytotic processes as well as high affinity glutamate and GABA uptake and subsequent metabolism of glutamate to glutamine are energy demanding processes. The main energy substrate for the brain under normal conditions is glucose but at the cellular level, i.e., neurons and astrocytes, lactate may play an important role as well. In addition to this the possibility exists that glycogen, which functions as a glucose storage molecule and which is only present in astrocytes, could play a role not only during aglycemia but also during normoglycemia. These issues are discussed and it is concluded that both glucose and lactate are of importance for the maintenance of normal glutamatergic and GABAergic activity. However, with regard to maintenance of an adequate capacity for glutamate transport, it appears that glucose metabolism via the glycolytic pathway plays a fundamental role. Additionally, evidence is presented to support the notion that glycogen turnover may play an important role in this context. Moreover, it should be noted that the amino acid neurotransmitters can be used as metabolic substrates. This requires pyruvate recycling, a process that is discussed as well.

  6. Non-neuronal release of gamma-aminobutyric Acid by embryonic pluripotent stem cells.

    PubMed

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

    2013-11-15

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

  7. Arousal from sleep in response to intermittent hypoxia in rat pups is modulated by medullary raphe GABAergic mechanisms.

    PubMed

    Darnall, Robert A; Schneider, Robert W; Tobia, Christine M; Zemel, Benjamin M

    2012-03-01

    Arousal is an important defense against hypoxia during sleep. Rat pups exhibit progressive arousal impairment (habituation) with multiple hypoxia exposures. The mechanisms are unknown. The medullary raphe (MR) is involved in autonomic functions, including sleep, and receives abundant GABAergic inputs. We hypothesized that inhibiting MR neurons with muscimol, a GABA(A) receptor agonist, or preventing GABA reuptake with nipecotic acid, would impair arousal and enhance arousal habituation and that blocking GABA(A) receptors with bicuculline would enhance arousal and attenuate habituation. Postnatal day 15 (P15) to P25 rat pups were briefly anesthetized, and microinjections with aCSF, muscimol, bicuculline, or nipecotic acid were made into the MR. After a ∼30-min recovery, pups were exposed to four 3-min episodes of hypoxia separated by 6 min of normoxia. The time to arousal from the onset of hypoxia (latency) was determined for each trial. Latency progressively increased across trials (habituation) in all groups. The overall latency was greater after muscimol and nipecotic acid compared with aCSF, bicuculline, or noninjected controls. Arousal habituation was reduced after bicuculline compared with aCSF, muscimol, nipecotic acid, or noninjected pups. Increases in latency were mirrored by decreases in chamber [O2] and oxyhemoglobin saturation. Heart rate increased during hypoxia and was greatest in muscimol-injected pups. Our results indicate that the MR plays an important, not previously described, role in arousal and arousal habituation during hypoxia and that these phenomena are modulated by GABAergic mechanisms. Arousal habituation may contribute to sudden infant death syndrome, which is associated with MR serotonergic and GABAergic receptor dysfunction. PMID:22160541

  8. GABA Regulates the Multidirectional Tangential Migration of GABAergic Interneurons in Living Neonatal Mice

    PubMed Central

    Inada, Hiroyuki; Watanabe, Miho; Uchida, Taku; Ishibashi, Hitoshi; Wake, Hiroaki; Nemoto, Tomomi; Yanagawa, Yuchio; Fukuda, Atsuo; Nabekura, Junichi

    2011-01-01

    Cortical GABAergic interneurons originate from ganglionic eminences and tangentially migrate into the cortical plate at early developmental stages. To elucidate the characteristics of this migration of GABAergic interneurons in living animals, we established an experimental design specialized for in vivo time-lapse imaging of the neocortex of neonate mice with two-photon laser-scanning microscopy. In vesicular GABA/glycine transporter (VGAT)-Venus transgenic mice from birth (P0) through P3, we observed multidirectional tangential migration of genetically-defined GABAergic interneurons in the neocortical marginal zone. The properties of this migration, such as the motility rate (distance/hr), the direction moved, and the proportion of migrating neurons to stationary neurons, did not change through P0 to P3, although the density of GABAergic neurons at the marginal zone decreased with age. Thus, the characteristics of the tangential motility of individual GABAergic neurons remained constant in development. Pharmacological block of GABAA receptors and of the Na+-K+-Cl− cotransporters, and chelating intracellular Ca2+, all significantly reduced the motility rate in vivo. The motility rate and GABA content within the cortex of neonatal VGAT-Venus transgenic mice were significantly greater than those of GAD67-GFP knock-in mice, suggesting that extracellular GABA concentration could facilitate the multidirectional tangential migration. Indeed, diazepam applied to GAD67-GFP mice increased the motility rate substantially. In an in vitro neocortical slice preparation, we confirmed that GABA induced a NKCC sensitive depolarization of GABAergic interneurons in VGAT-Venus mice at P0-P3. Thus, activation of GABAAR by ambient GABA depolarizes GABAergic interneurons, leading to an acceleration of their multidirectional motility in vivo. PMID:22180776

  9. Hairy/Enhancer-of-Split MEGANE and Proneural MASH1 Factors Cooperate Synergistically in Midbrain GABAergic Neurogenesis

    PubMed Central

    Wende, Clara-Zoe; Zoubaa, Saida; Blak, Alexandra; Echevarria, Diego; Martinez, Salvador; Guillemot, François; Wurst, Wolfgang; Guimera, Jordi

    2015-01-01

    GABAergic neurons are the primary inhibitory cell type in the mature brain and their dysfunction is associated with important neurological conditions like schizophrenia and anxiety. We aimed to discover the underlying mechanisms for dorsal/ventral midbrain GABAergic neurogenesis. Previous work by us and others has provided crucial insights into the key function of Mgn and Mash1 genes in determining GABAergic neurotransmitter fate. Induction of dorsal midbrain GABAergic neurons does not take place at any time during development in either of the single mutant mice. However, GABAergic neurons in the ventral midbrain remained unchanged. Thus, the similarities in MB-GABAergic phenotype observed in the Mgn and Mash1 single mutants suggest the existence of other factors that take over the function of MGN and MASH1 in the ventral midbrain or the existence of different molecular mechanisms. We show that this process essentially depends on heterodimers and homodimers formed by MGN and MASH1 and deciphered the in vivo relevance of the interaction by phenotypic analysis of Mgn/Mash1 double knockout and compound mice. Furthermore, the combination of gain- and loss-of-function experiments in the developing midbrain showed co-operative roles for Mgn and Mash1 genes in determining GABAergic identity. Transcription factors belonging to the Enhancer-of-split-related and proneural families have long been believed to counterpart each other’s function. This work uncovers a synergistic cooperation between these two families, and provides a novel paradigm for how these two families cooperate for the acquisition of MB-GABAergic neuronal identity. Understanding their molecular mechanisms is essential for cell therapy strategies to amend GABAergic deficits. PMID:25993409

  10. Hairy/Enhancer-of-Split MEGANE and Proneural MASH1 Factors Cooperate Synergistically in Midbrain GABAergic Neurogenesis.

    PubMed

    Wende, Clara-Zoe; Zoubaa, Saida; Blak, Alexandra; Echevarria, Diego; Martinez, Salvador; Guillemot, François; Wurst, Wolfgang; Guimera, Jordi

    2015-01-01

    GABAergic neurons are the primary inhibitory cell type in the mature brain and their dysfunction is associated with important neurological conditions like schizophrenia and anxiety. We aimed to discover the underlying mechanisms for dorsal/ventral midbrain GABAergic neurogenesis. Previous work by us and others has provided crucial insights into the key function of Mgn and Mash1 genes in determining GABAergic neurotransmitter fate. Induction of dorsal midbrain GABAergic neurons does not take place at any time during development in either of the single mutant mice. However, GABAergic neurons in the ventral midbrain remained unchanged. Thus, the similarities in MB-GABAergic phenotype observed in the Mgn and Mash1 single mutants suggest the existence of other factors that take over the function of MGN and MASH1 in the ventral midbrain or the existence of different molecular mechanisms. We show that this process essentially depends on heterodimers and homodimers formed by MGN and MASH1 and deciphered the in vivo relevance of the interaction by phenotypic analysis of Mgn/Mash1 double knockout and compound mice. Furthermore, the combination of gain- and loss-of-function experiments in the developing midbrain showed co-operative roles for Mgn and Mash1 genes in determining GABAergic identity. Transcription factors belonging to the Enhancer-of-split-related and proneural families have long been believed to counterpart each other's function. This work uncovers a synergistic cooperation between these two families, and provides a novel paradigm for how these two families cooperate for the acquisition of MB-GABAergic neuronal identity. Understanding their molecular mechanisms is essential for cell therapy strategies to amend GABAergic deficits.

  11. Epigenetic GABAergic targets in schizophrenia and bipolar disorder.

    PubMed

    Guidotti, A; Auta, J; Chen, Y; Davis, J M; Dong, E; Gavin, D P; Grayson, D R; Matrisciano, F; Pinna, G; Satta, R; Sharma, R P; Tremolizzo, L; Tueting, P

    2011-06-01

    It is becoming increasingly clear that a dysfunction of the GABAergic/glutamatergic network in telencephalic brain structures may be the pathogenetic mechanism underlying psychotic symptoms in schizophrenia (SZ) and bipolar (BP) disorder patients. Data obtained in Costa's laboratory (1996-2009) suggest that this dysfunction may be mediated primarily by a downregulation in the expression of GABAergic genes (e.g., glutamic acid decarboxylase₆₇[GAD₆₇] and reelin) associated with DNA methyltransferase (DNMT)-dependent hypermethylation of their promoters. A pharmacological strategy to reduce the hypermethylation of GABAergic promoters is to administer drugs, such as the histone deacetylase (HDAC) inhibitor valproate (VPA), that induce DNA-demethylation when administered at doses that facilitate chromatin remodeling. The benefits elicited by combining VPA with antipsychotics in the treatment of BP disorder suggest that an investigation of the epigenetic interaction of these drugs is warranted. Our studies in mice suggest that when associated with VPA, clinically relevant doses of clozapine elicit a synergistic potentiation of VPA-induced GABAergic promoter demethylation. Olanzapine and quetiapine (two clozapine congeners) also facilitate chromatin remodeling but at doses higher than used clinically, whereas haloperidol and risperidone are inactive. Hence, the synergistic potentiation of VPA's action on chromatin remodeling by clozapine appears to be a unique property of the dibenzepines and is independent of their action on catecholamine or serotonin receptors. By activating DNA-demethylation, the association of clozapine or its derivatives with VPA or other more potent and selective HDAC inhibitors may be considered a promising treatment strategy for normalizing GABAergic promoter hypermethylation and the GABAergic gene expression downregulation detected in the postmortem brain of SZ and BP disorder patients. This article is part of a Special Issue entitled

  12. Epigenetic GABAergic Targets in Schizophrenia and Bipolar Disorder

    PubMed Central

    Guidotti, A.; Auta, J.; Chen, Y.; Davis, J.M.; Dong, E.; Gavin, D.P.; Grayson, D.R.; Matrisciano, F.; Pinna, G.; Satta, R.; Sharma, R.P.; Tremolizzo, L.; Tueting, P.

    2014-01-01

    It is becoming increasingly clear that a dysfunction of the GABAergic/glutamatergic network in telencephalic brain structures may be the pathogenetic mechanism underlying psychotic symptoms in schizophrenia (SZ) and bipolar (BP) disorder patients. Data obtained in Costa’s laboratory (1996–2009) suggest that this dysfunction may be mediated primarily by a downregulation in the expression of GABAergic genes (e.g., glutamic acid decarboxylase67 [GAD67] and reelin) associated with DNA-methyltransferase (DNMT)-dependent hypermethylation of their promoters. A pharmacological strategy to reduce the hypermethylation of GABAergic promoters is to administer drugs, such as the histone deacetylase (HDAC) inhibitor valproate (VPA), that induce DNA-demethylation when administered at doses that facilitate chromatin remodeling. The benefits elicited by combining VPA with antipsychotics in the treatment of BP disorder suggest that an investigation of the epigenetic interaction of these drugs is warranted. Our studies in mice suggest that when associated with VPA, clinically relevant doses of clozapine elicit a synergistic potentiation of VPA-induced GABAergic promoter demethylation. Olanzapine and quetiapine (two clozapine congeners) also facilitate chromatin remodeling but at doses higher than used clinically, whereas haloperidol and risperidone are inactive. Hence, the synergistic potentiation of VPA’s action on chromatin remodeling by clozapine appears to be a unique property of the dibenzepines and is independent of their action on catecholamine or serotonin receptors. By activating DNA-demethylation, the association of clozapine or its derivatives with VPA or other more potent and selective HDAC inhibitors may be considered a promising treatment strategy for normalizing GABAergic promoter hypermethylation and the GABAergic gene expression downregulation detected in the postmortem brain of SZ and BP disorder patients. PMID:21074545

  13. GABAergic and non-GABAergic thalamic, hypothalamic and basal forebrain projections to the ventral oral pontine reticular nucleus: their implication in REM sleep modulation.

    PubMed

    Rodrigo-Angulo, Margarita L; Heredero, Susana; Rodríguez-Veiga, Elisia; Reinoso-Suárez, Fernando

    2008-05-19

    The ventral part of the oral pontine reticular nucleus (vRPO) is a demonstrated site of brainstem REM-sleep generation and maintenance. The vRPO has reciprocal connections with structures that control other states of the sleep-wakefulness cycle, many situated in the basal forebrain and the diencephalon. Some of these connections utilize the inhibitory neurotransmitter GABA. The aim of the present work is to map the local origin of the basal forebrain and diencephalon projections to the vRPO whether GABAergic or non-GABAergic. A double-labelling technique combining vRPO injections of the neuronal tracer, cholera-toxin (CTB), with GAD-immunohistochemistry, was used for this purpose in adult cats. All of the numerous CTB-positive neurons in the reticular thalamic and dorsocaudal hypothalamic nuclei were double-labelled (CTB/GAD-positive) neurons. Approximately 15%, 14% and 16% of the CTB-positive neurons in the zona incerta and the dorsal and lateral hypothalamic areas are, respectively, CTB/GAD-positive neurons. However, only some double-labelled neurons were found in other hypothalamic nuclei with abundant CTB-positive neurons, such as the paraventricular nucleus, perifornical area and H1 Forel field. In addition, CTB-positive neurons were abundant in the central amygdaline nucleus, terminal stria bed nuclei, median preoptic nucleus, medial and lateral preoptic areas, dorsomedial and ventromedial hypothalamic nuclei, posterior hypothalamic area and periventricular thalamic nucleus. The GABAergic and non-GABAergic connections described here may be the morphological pillar through which these prosencephalic structures modulate, either by inhibiting or by exciting, the vRPO REM-sleep inducing neurons during the different sleep-wakefulness cycle states.

  14. Identification of a direct GABAergic pallidocortical pathway in rodents

    PubMed Central

    Chen, Michael C.; Ferrari, Loris; Sacchet, Matthew D.; Foland-Ross, Lara C.; Qiu, Mei-Hong; Gotlib, Ian H.; Fuller, Patrick M.; Arrigoni, Elda; Lu, Jun

    2014-01-01

    The basal ganglia, interacting with the cortex, play a critical role in a range of behaviors. Output from the basal ganglia to the cortex is thought to relay through the thalamus, yet an intriguing alternative is that the basal ganglia may directly project to, and communicate with, the cortex. We explored an efferent projection from the globus pallidus externa (GPe), a key hub in the basal ganglia system, to the cortex of rats and mice. Anterograde and retrograde tracing revealed projections to the frontal premotor cortex, especially the deep projecting layers, originating from GPe neurons that receive axonal inputs from the dorsal striatum. Cre-dependent anterograde tracing in GPe Vgat-ires-cre mice confirmed that the pallidocortical projection is GABAergic, and in vitro optogenetic stimulation in the cortex of these projections produced a fast inhibitory postsynaptic current in targeted cells that was abolished by bicucculine. The pallidocortical projections targeted GABAergic interneurons and, to a lesser extent, pyramidal neurons. This GABAergic pallidocortical pathway directly links the basal ganglia and cortex and may play a key role in behavior and cognition in normal and disease states. PMID:25581560

  15. Induction of plasminogen in rat hippocampal pyramidal neurons by kainic acid.

    PubMed

    Matsuoka, Y; Kitamura, Y; Taniguchi, T

    1998-08-14

    Tissue plasminogen activator (tPA) is used to treat acute stroke, but tPA- and plasminogen-gene-deficient mice exhibit resistance to neurodegeneration. Thus, it is unclear whether the tPA-plasminogen system, an extracellular proteolytic cascade plays a helpful or harmful role, and whether plasminogen is induced by neurodegeneration. In the CA3, kainic acid (KA)-injection caused neuronal damage after 6 h, and almost all of the neurons were lost after 7 days. Plasminogen mRNA was strongly induced 6 h after injection, then gradually decreased, and was very weak at 2 days after injection. Plasminogen protein was expressed after 6 h and localized in abnormally shaped neurons. The in vivo expression of plasminogen was synchronous with morphological changes in neurons. These results suggest that the expression of plasminogen induced by KA-injection may disrupt of neuron-extracellular matrix interaction and thereby contribute to cell death in neurons in the hippocampus.

  16. A functional glutamatergic neurone network in the medial septum and diagonal band area.

    PubMed

    Manseau, F; Danik, M; Williams, S

    2005-08-01

    The medial septum and diagonal band complex (MS/DB) is important for learning and memory and is known to contain cholinergic and GABAergic neurones. Glutamatergic neurones have also been recently described in this area but their function remains unknown. Here we show that local glutamatergic neurones can be activated using 4-aminopyridine (4-AP) and the GABA(A) receptor antagonist bicuculline in regular MS/DB slices, or mini-MS/DB slices. The spontaneous glutamatergic responses were mediated by AMPA receptors and, to a lesser extend, NMDA receptors, and were characterized by large, sometimes repetitive activity that elicited bursts of action potentials postsynaptically. Similar repetitive AMPA receptor-mediated bursts were generated by glutamatergic neurone activation within the MS/DB in disinhibited organotypic MS/DB slices, suggesting that the glutamatergic responses did not originate from extrinsic glutamatergic synapses. It is interesting that glutamatergic neurones were part of a synchronously active network as large repetitive AMPA receptor-mediated bursts were generated concomitantly with extracellular field potentials in intact half-septum preparations in vitro. Glutamatergic neurones appeared important to MS/DB activation as strong glutamatergic responses were present in electrophysiologically identified putative cholinergic, GABAergic and glutamatergic neurones. In agreement with this, we found immunohistochemical evidence that vesicular glutamate-2 (VGLUT2)-positive puncta were in proximity to choline acetyltransferase (ChAT)-, glutamic acid decarboxylase 67 (GAD67)- and VGLUT2-positive neurones. Finally, MS/DB glutamatergic neurones could be activated under more physiological conditions as a cholinergic agonist was found to elicit rhythmic AMPA receptor-mediated EPSPs at a theta relevant frequency of 6-10 Hz. We propose that glutamatergic neurones within the MS/DB can excite cholinergic and GABAergic neurones, and that they are part of a connected

  17. A functional glutamatergic neurone network in the medial septum and diagonal band area

    PubMed Central

    Manseau, F; Danik, M; Williams, S

    2005-01-01

    The medial septum and diagonal band complex (MS/DB) is important for learning and memory and is known to contain cholinergic and GABAergic neurones. Glutamatergic neurones have also been recently described in this area but their function remains unknown. Here we show that local glutamatergic neurones can be activated using 4-aminopyridine (4-AP) and the GABAA receptor antagonist bicuculline in regular MS/DB slices, or mini-MS/DB slices. The spontaneous glutamatergic responses were mediated by AMPA receptors and, to a lesser extend, NMDA receptors, and were characterized by large, sometimes repetitive activity that elicited bursts of action potentials postsynaptically. Similar repetitive AMPA receptor-mediated bursts were generated by glutamatergic neurone activation within the MS/DB in disinhibited organotypic MS/DB slices, suggesting that the glutamatergic responses did not originate from extrinsic glutamatergic synapses. It is interesting that glutamatergic neurones were part of a synchronously active network as large repetitive AMPA receptor-mediated bursts were generated concomitantly with extracellular field potentials in intact half-septum preparations in vitro. Glutamatergic neurones appeared important to MS/DB activation as strong glutamatergic responses were present in electrophysiologically identified putative cholinergic, GABAergic and glutamatergic neurones. In agreement with this, we found immunohistochemical evidence that vesicular glutamate-2 (VGLUT2)-positive puncta were in proximity to choline acetyltransferase (ChAT)-, glutamic acid decarboxylase 67 (GAD67)- and VGLUT2-positive neurones. Finally, MS/DB glutamatergic neurones could be activated under more physiological conditions as a cholinergic agonist was found to elicit rhythmic AMPA receptor-mediated EPSPs at a theta relevant frequency of 6–10 Hz. We propose that glutamatergic neurones within the MS/DB can excite cholinergic and GABAergic neurones, and that they are part of a connected

  18. New Role of ATM in Controlling GABAergic Tone During Development.

    PubMed

    Pizzamiglio, Lara; Focchi, Elisa; Murru, Luca; Tamborini, Matteo; Passafaro, Maria; Menna, Elisabetta; Matteoli, Michela; Antonucci, Flavia

    2016-10-01

    The capacity to guarantee the proper excitatory/inhibitory balance is one of the most critical steps during early development responsible for the correct brain organization, function, and plasticity. GABAergic neurons guide this process leading to the right structural organization, brain circuitry, and neuronal firing. Here, we identified the ataxia telangiectasia mutated (ATM), a serine/threonine protein kinase linked to DNA damage response, as crucial in regulating neurotransmission. We found that reduced levels of ATM in the hippocampal neuronal cultures produce an excitatory/inhibitory unbalance toward inhibition as indicated by the higher frequency of miniature inhibitory postsynaptic current events and an increased number of GABAergic synapses. In vivo, the increased inhibition still persists and, even if a higher excitation is also present, a reduced neuronal excitability is found as indicated by the lower action potential frequency generated in response to high-current intensity stimuli. Finally, we found an elevated extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in heterozygous hippocampi associated with lower expression levels of the ERK1/2 phosphatase PP1. Given that the neurodegenerative condition associated with genetic mutations in the Atm gene, ataxia telangiectasia, presents a variable phenotype with impairment in cognition, our molecular findings provide a logical frame for a more clear comprehension of cognitive defects in the pathology, opening to novel therapeutic strategies.

  19. New Role of ATM in Controlling GABAergic Tone During Development.

    PubMed

    Pizzamiglio, Lara; Focchi, Elisa; Murru, Luca; Tamborini, Matteo; Passafaro, Maria; Menna, Elisabetta; Matteoli, Michela; Antonucci, Flavia

    2016-10-01

    The capacity to guarantee the proper excitatory/inhibitory balance is one of the most critical steps during early development responsible for the correct brain organization, function, and plasticity. GABAergic neurons guide this process leading to the right structural organization, brain circuitry, and neuronal firing. Here, we identified the ataxia telangiectasia mutated (ATM), a serine/threonine protein kinase linked to DNA damage response, as crucial in regulating neurotransmission. We found that reduced levels of ATM in the hippocampal neuronal cultures produce an excitatory/inhibitory unbalance toward inhibition as indicated by the higher frequency of miniature inhibitory postsynaptic current events and an increased number of GABAergic synapses. In vivo, the increased inhibition still persists and, even if a higher excitation is also present, a reduced neuronal excitability is found as indicated by the lower action potential frequency generated in response to high-current intensity stimuli. Finally, we found an elevated extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in heterozygous hippocampi associated with lower expression levels of the ERK1/2 phosphatase PP1. Given that the neurodegenerative condition associated with genetic mutations in the Atm gene, ataxia telangiectasia, presents a variable phenotype with impairment in cognition, our molecular findings provide a logical frame for a more clear comprehension of cognitive defects in the pathology, opening to novel therapeutic strategies. PMID:27166172

  20. Fatty acid biosynthesis from glutamate and glutamine is specifically induced in neuronal cells under hypoxia.

    PubMed

    Brose, Stephen A; Marquardt, Amanda L; Golovko, Mikhail Y

    2014-05-01

    Hypoxia is involved in many neuronal and non-neuronal diseases, and defining the mechanisms for tissue adaptation to hypoxia is critical for the understanding and treatment of these diseases. One mechanism for tissue adaptation to hypoxia is increased glutamine and/or glutamate (Gln/Glu) utilization. To address this mechanism, we determined incorporation of Gln/Glu and other lipogenic substrates into lipids and fatty acids in both primary neurons and a neuronal cell line under normoxic and hypoxic conditions and compared this to non-neuronal primary cells and non-neuronal cell lines. Incorporation of Gln/Glu into total lipids was dramatically and specifically increased under hypoxia in neuronal cells including both primary (2.0- and 3.0-fold for Gln and Glu, respectively) and immortalized cultures (3.5- and 8.0-fold for Gln and Glu, respectively), and 90% to 97% of this increase was accounted for by incorporation into fatty acids (FA) depending upon substrate and cell type. All other non-neuronal cells tested demonstrated decreased or unchanged FA synthesis from Gln/Glu under hypoxia. Consistent with these data, total FA mass was also increased in neuronal cells under hypoxia that was mainly accounted for by the increase in saturated and monounsaturated FA with carbon length from 14 to 24. Incorporation of FA synthesized from Gln/Glu was increased in all major lipid classes including cholesteryl esters, triacylglycerols, diacylglycerols, free FA, and phospholipids, with the highest rate of incorporation into triacylglycerols. These results indicate that increased FA biosynthesis from Gln/Glu followed by esterification may be a neuronal specific pathway for adaptation to hypoxia. We identified a novel neuronal specific pathway for adaptation to hypoxia through increased fatty acid biosynthesis from glutamine and glutamate (Gln/Glu) followed by esterification into lipids. All other non-neuronal cells tested demonstrated decreased or unchanged lipid synthesis from Gln

  1. Duration sensitivity of neurons in the primary auditory cortex of albino mouse.

    PubMed

    Wang, Xin; Qi, Qiaozhen; Huang, Caifei; Chomiak, Taylor; Luo, Feng

    2016-02-01

    Many neurons in the central auditory system of a number of species have been found to be sensitive to the duration of sound stimuli. While previous studies have shown that γ-aminobutyric acid (GABA)-ergic inhibitory input is important for duration sensitivity in the inferior colliculus (IC), it is still unknown whether (GABA)-ergic inhibitory input plays an important role in generating duration sensitivity in the cortex. Using free-field sound stimulation and in vivo extracellular recording, we investigated duration sensitivity in primary auditory cortical (AI) neurons of the Nembutal anesthetized albino mouse (Mus musculus, Km) and examined the effect of the GABAA receptor antagonist bicuculline on AI neuron duration sensitivity. A total of 63 duration tuning curves were measured in AI neurons. Of these, 44% (28/63) exhibited duration sensitive responses, while 43% (27/63) lacked duration sensitivity. The remaining 13% (8/63) exhibited long-pass properties likely reflecting both duration sensitive and insensitive features. We found that duration sensitive neurons had shorter first spike latency (FSL) and longer firing duration (FD) when stimulated with best duration (p < 0.05), while duration insensitive neurons had invariable FSL and FD at different sound durations (p>0.05). Furthermore, 60% (6/10) of duration sensitive neurons and 75% (3/4) long-pass neurons lost duration sensitivity following bicuculline application. Taken together, our results show that cortical neurons in the albino mouse are sensitive to sound duration, and that GABAergic inhibition may play an important role in the formation of de novo duration sensitivity in AI. The possible mechanism and behavioral significance of duration sensitivity in AI neurons is discussed. PMID:26529681

  2. [Ammonia and GABA-ergic neurotransmission in pathogenesis of hepatic encephalopathy].

    PubMed

    Helewski, Krzysztof; Kowalczyk-Ziomek, Grazyna; Konecki, Janusz

    2003-01-01

    Pathogenesis of hepatic encephalopathy has not been fully revealed and there are many factors which may affect its development. Ammonia and changes in GABA-ergic neurotransmission seem to be the most essential of these factors. Hepatic encephalopathy is frequently, though not always, accompanied by elevated blood ammonia level. Due to the changes in permeability of blood-brain barrier the ammonia level in the brain also increases which results in both stimulating and inhibitory neurotransmission disturbances. Ammonia also affects abnormal interaction of metabolic neurones and astrocytes as well as glutamine-serotonin balance. Another essential factor affecting hepatic encephalopathy development are disturbances in GABA-ergic neurotransmission connected with GABAA receptor complex. When the liver is damaged GABA-ergic neurotransmission increases due to a higher GABA level, natural benzodiazepine receptor agonists as well as neurosteroids synthesised in astrocytes. Many studies point to the fact that ammonia and GABA-ergic neurotransmission disturbances interrelate with each other. There is a concept saying that both these factors cause hepatic encephalopathy. Ammonia may indirectly increase GABA-ergic neurotransmission and also inhibit the function of the central nervous system by synergistic activity with benzodiazepine receptor ligands. So far it is not known whether GABA-ergic neurotransmission is affected by ammonia only or by other factors as well. PMID:15058165

  3. Differential regulation of the postsynaptic clustering of γ-aminobutyric acid type A (GABAA) receptors by collybistin isoforms.

    PubMed

    Chiou, Tzu-Ting; Bonhomme, Bevan; Jin, Hongbing; Miralles, Celia P; Xiao, Haiyan; Fu, Zhanyan; Harvey, Robert J; Harvey, Kirsten; Vicini, Stefano; De Blas, Angel L

    2011-06-24

    Collybistin promotes submembrane clustering of gephyrin and is essential for the postsynaptic localization of gephyrin and γ-aminobutyric acid type A (GABA(A)) receptors at GABAergic synapses in hippocampus and amygdala. Four collybistin isoforms are expressed in brain neurons; CB2 and CB3 differ in the C terminus and occur with and without the Src homology 3 (SH3) domain. We have found that in transfected hippocampal neurons, all collybistin isoforms (CB2(SH3+), CB2(SH3-), CB3(SH3+), and CB3(SH3-)) target to and concentrate at GABAergic postsynapses. Moreover, in non-transfected neurons, collybistin concentrates at GABAergic synapses. Hippocampal neurons co-transfected with CB2(SH3-) and gephyrin developed very large postsynaptic gephyrin and GABA(A) receptor clusters (superclusters). This effect was accompanied by a significant increase in the amplitude of miniature inhibitory postsynaptic currents. Co-transfection with CB2(SH3+) and gephyrin induced the formation of many (supernumerary) non-synaptic clusters. Transfection with gephyrin alone did not affect cluster number or size, but gephyrin potentiated the clustering effect of CB2(SH3-) or CB2(SH3+). Co-transfection with CB2(SH3-) or CB2(SH3+) and gephyrin did not affect the density of presynaptic GABAergic terminals contacting the transfected cells, indicating that collybistin is not synaptogenic. Nevertheless, the synaptic superclusters induced by CB2(SH3-) and gephyrin were accompanied by enlarged presynaptic GABAergic terminals. The enhanced clustering of gephyrin and GABA(A) receptors induced by collybistin isoforms was not accompanied by enhanced clustering of neuroligin 2. Moreover, during the development of GABAergic synapses, the clustering of gephyrin and GABA(A) receptors preceded the clustering of neuroligin 2. We propose a model in which the SH3- isoforms play a major role in the postsynaptic accumulation of GABA(A) receptors and in GABAergic synaptic strength.

  4. Differentiation of neuronal stem cells into motor neurons using electrospun poly-L-lactic acid/gelatin scaffold.

    PubMed

    Binan, Loïc; Tendey, Charlène; De Crescenzo, Gregory; El Ayoubi, Rouwayda; Ajji, Abdellah; Jolicoeur, Mario

    2014-01-01

    Neural stem cells (NSCs) provide promising therapeutic potential for cell replacement therapy in spinal cord injury (SCI). However, high increases of cell viability and poor control of cell differentiation remain major obstacles. In this study, we have developed a non-woven material made of co-electrospun fibers of poly L-lactic acid and gelatin with a degradation rate and mechanical properties similar to peripheral nerve tissue and investigated their effect on cell survival and differentiation into motor neuronal lineages through the controlled release of retinoic acid (RA) and purmorphamine. Engineered Neural Stem-Like Cells (NSLCs) seeded on these fibers, with and without the instructive cues, differentiated into β-III-tubulin, HB-9, Islet-1, and choactase-positive motor neurons by immunostaining, in response to the release of the biomolecules. In addition, the bioactive material not only enhanced the differentiation into motor neuronal lineages but also promoted neurite outgrowth. This study elucidated that a combination of electrospun fiber scaffolds, neural stem cells, and controlled delivery of instructive cues could lead to the development of a better strategy for peripheral nerve injury repair. PMID:24161168

  5. Pathological alterations in GABAergic interneurons and reduced tonic inhibition in the basolateral amygdala during epileptogenesis

    PubMed Central

    Fritsch, Brita; Qashu, Felicia; Figueiredo, Taiza H.; Aroniadou-Anderjaska, Vassiliki; Rogawski, Michael A.; Braga, Maria F.M.

    2009-01-01

    An acute brain insult such as traumatic head/brain injury, stroke, or an episode of status epilepticus can trigger epileptogenesis, which, after a latent, seizure-free period, leads to epilepsy. The discovery of effective pharmacological interventions that can prevent the development of epilepsy requires knowledge of the alterations that occur during epileptogenesis in brain regions that play a central role in the induction and expression of epilepsy. In the present study, we investigated pathological alterations in GABAergic interneurons in the rat basolateral amygdala (BLA), and the functional impact of these alterations on inhibitory synaptic transmission, on days 7 to 10 after SE induced by kainic acid. Using design-based stereology combined with GAD67 immunohistochemistry, we found a more extensive loss of GABAergic interneurons compared to the loss of principal cells. Fluoro-Jade C staining showed that neuronal degeneration was still ongoing. These alterations were accompanied by an increase in the levels of glutamate decarboxylase and the α1 subunit of the GABAA receptor, and a reduction in the GluK1 (previously known as GluR5) subunit, as determined by Western blots. Whole-cell recordings from BLA pyramidal neurons showed a significant reduction in the frequency and amplitude of action potential-dependent spontaneous IPSCs, a reduced frequency but not amplitude of miniature IPSCs, and impairment in the modulation of IPSCs via GluK1-containing kainate receptors (GluK1Rs). Thus, in the BLA, GABAergic interneurons are more vulnerable to seizure-induced damage than principal cells. Surviving interneurons increase their expression of glutamate decarboxylase and the α1 GABAA receptor subunit, but this does not compensate for the interneuronal loss; the result is a dramatic reduction of tonic inhibition in the BLA circuitry. As activation of GluK1Rs by ambient levels of glutamate facilitates GABA release, the reduced level and function of these receptors may

  6. Fatty acid biosynthesis from glutamate and glutamine is specifically induced in neuronal cells under hypoxia

    PubMed Central

    Brose, Stephen A.; Marquardt, Amanda L.; Golovko, Mikhail Y.

    2014-01-01

    Hypoxia is involved in many neuronal and non-neuronal diseases, and defining the mechanisms for tissue adaptation to hypoxia is critical for the understanding and treatment of these diseases. One mechanism for tissue adaptation to hypoxia is increased glutamine and/or glutamate (Gln/Glu) utilization. To address this mechanism, we determined total Gln/Glu incorporation into lipids and fatty acids in both primary neurons and a neuronal cell line under normoxic and hypoxic conditions and compared this to non-neuronal primary cells and non-neuronal cell lines. Incorporation of Gln/Glu into total lipids was dramatically and specifically increased under hypoxia in neuronal cells including both primary (2.0- and 3.0- fold for Gln and Glu, respectively) and immortalized cultures (3.5- and 8.0- fold for Gln and Glu, respectively), and 90% to 97% of this increase was accounted for by incorporation into fatty acids (FA) depending upon substrate and cell type. All other non-neuronal cells tested demonstrated decreased or unchanged FA synthesis from Gln/Glu under hypoxia. Consistent with these data, total FA mass was also increased in neuronal cells under hypoxia that was mainly accounted for by the increase in saturated and monounsaturated FA with carbon length from 14 to 24. Incorporation of FA synthesized from Gln/Glu was increased in all major lipid classes including cholesteryl esters, TAGs, DAGs, free FA, and phospholipids, with the highest rate of incorporation into TAGs. These results indicate that increased FA biosynthesis from Gln/Glu followed by esterification may be a neuronal specific pathway for adaptation to hypoxia. PMID:24266789

  7. Dendritic and Axonal Wiring Optimization of Cortical GABAergic Interneurons.

    PubMed

    Anton-Sanchez, Laura; Bielza, Concha; Benavides-Piccione, Ruth; DeFelipe, Javier; Larrañaga, Pedro

    2016-10-01

    The way in which a neuronal tree expands plays an important role in its functional and computational characteristics. We aimed to study the existence of an optimal neuronal design for different types of cortical GABAergic neurons. To do this, we hypothesized that both the axonal and dendritic trees of individual neurons optimize brain connectivity in terms of wiring length. We took the branching points of real three-dimensional neuronal reconstructions of the axonal and dendritic trees of different types of cortical interneurons and searched for the minimal wiring arborization structure that respects the branching points. We compared the minimal wiring arborization with real axonal and dendritic trees. We tested this optimization problem using a new approach based on graph theory and evolutionary computation techniques. We concluded that neuronal wiring is near-optimal in most of the tested neurons, although the wiring length of dendritic trees is generally nearer to the optimum. Therefore, wiring economy is related to the way in which neuronal arborizations grow irrespective of the marked differences in the morphology of the examined interneurons.

  8. Dendritic and Axonal Wiring Optimization of Cortical GABAergic Interneurons.

    PubMed

    Anton-Sanchez, Laura; Bielza, Concha; Benavides-Piccione, Ruth; DeFelipe, Javier; Larrañaga, Pedro

    2016-10-01

    The way in which a neuronal tree expands plays an important role in its functional and computational characteristics. We aimed to study the existence of an optimal neuronal design for different types of cortical GABAergic neurons. To do this, we hypothesized that both the axonal and dendritic trees of individual neurons optimize brain connectivity in terms of wiring length. We took the branching points of real three-dimensional neuronal reconstructions of the axonal and dendritic trees of different types of cortical interneurons and searched for the minimal wiring arborization structure that respects the branching points. We compared the minimal wiring arborization with real axonal and dendritic trees. We tested this optimization problem using a new approach based on graph theory and evolutionary computation techniques. We concluded that neuronal wiring is near-optimal in most of the tested neurons, although the wiring length of dendritic trees is generally nearer to the optimum. Therefore, wiring economy is related to the way in which neuronal arborizations grow irrespective of the marked differences in the morphology of the examined interneurons. PMID:27345531

  9. Arachidonic acid-induced oxidative injury to cultured spinal cord neurons.

    PubMed

    Toborek, M; Malecki, A; Garrido, R; Mattson, M P; Hennig, B; Young, B

    1999-08-01

    Spinal cord trauma can cause a marked release of free fatty acids, in particular, arachidonic acid (AA), from cell membranes. Free fatty acids, and AA by itself, may lead to secondary damage to spinal cord neurons. To study this hypothesis, cultured spinal cord neurons were exposed to increasing concentrations of AA (0.01-10 microM). AA-induced injury to spinal cord neurons was assessed by measurements of cellular oxidative stress, intracellular calcium levels, activation of nuclear factor-KB (NF-kappaB), and cell viability. AA treatment increased intracellular calcium concentrations and decreased cell viability. Oxidative stress increased significantly in neurons exposed to 1 and 10 microM AA. In addition, AA treatment activated NF-kappaB and decreased levels of the inhibitory subunit, IKB. It is interesting that manganese superoxide dismutase protein levels and levels of intracellular total glutathione increased in neurons exposed to this fatty acid for 24 h, consistent with a compensatory response to increased oxidative stress. These results strongly support the hypothesis that free fatty acids contribute to the tissue injury observed following spinal cord trauma. PMID:10428065

  10. An interneuron progenitor maintains neurogenic potential in vivo and differentiates into GABAergic interneurons after transplantation in the postnatal rat brain

    PubMed Central

    Wang, Qi; Hong, Peiwei; Gao, Hui; Chen, Yuntian; Yang, Qi; Jiang, Mei; Li, Hedong

    2016-01-01

    Dysfunction of cortical GABAergic interneurons are involved in numerous neurological disorders including epilepsy, schizophrenia and autism; and replenishment of these cells by transplantation strategy has proven to be a feasible and effective method to help revert the symptoms in several animal models. To develop methodology of generating transplantable GABAergic interneurons for therapy, we previously reported the isolation of a v-myc-induced GABAergic interneuron progenitor clone GE6 from embryonic ganglionic eminence (GE). These cells can proliferate and form functional inhibitory synapses in culture. Here, we tested their differentiation behavior in vivo by transplanting them into the postnatal rat forebrain. We found that GE6 cells migrate extensively in the neonatal forebrain and differentiate into both neurons and glia, but preferentially into neurons when compared with a sister progenitor clone CTX8. The neurogenic potential of GE6 cells is also maintained after transplantation into a non-permissive environment such as adult cortex or when treated with inflammatory cytokine in culture. The GE6-derived neurons were able to mature in vivo as GABAergic interneurons expressing GABAergic, not glutamatergic, presynaptic puncta. Finally, we propose that v-myc-induced human interneuron progenitor clones could be an alternative cell source of transplantable GABAergic interneurons for treating related neurological diseases in future clinic. PMID:26750620

  11. Dopamine synapse is a neuroligin-2–mediated contact between dopaminergic presynaptic and GABAergic postsynaptic structures

    PubMed Central

    Uchigashima, Motokazu; Ohtsuka, Toshihisa; Kobayashi, Kazuto; Watanabe, Masahiko

    2016-01-01

    Midbrain dopamine neurons project densely to the striatum and form so-called dopamine synapses on medium spiny neurons (MSNs), principal neurons in the striatum. Because dopamine receptors are widely expressed away from dopamine synapses, it remains unclear how dopamine synapses are involved in dopaminergic transmission. Here we demonstrate that dopamine synapses are contacts formed between dopaminergic presynaptic and GABAergic postsynaptic structures. The presynaptic structure expressed tyrosine hydroxylase, vesicular monoamine transporter-2, and plasmalemmal dopamine transporter, which are essential for dopamine synthesis, vesicular filling, and recycling, but was below the detection threshold for molecules involving GABA synthesis and vesicular filling or for GABA itself. In contrast, the postsynaptic structure of dopamine synapses expressed GABAergic molecules, including postsynaptic adhesion molecule neuroligin-2, postsynaptic scaffolding molecule gephyrin, and GABAA receptor α1, without any specific clustering of dopamine receptors. Of these, neuroligin-2 promoted presynaptic differentiation in axons of midbrain dopamine neurons and striatal GABAergic neurons in culture. After neuroligin-2 knockdown in the striatum, a significant decrease of dopamine synapses coupled with a reciprocal increase of GABAergic synapses was observed on MSN dendrites. This finding suggests that neuroligin-2 controls striatal synapse formation by giving competitive advantage to heterologous dopamine synapses over conventional GABAergic synapses. Considering that MSN dendrites are preferential targets of dopamine synapses and express high levels of dopamine receptors, dopamine synapse formation may serve to increase the specificity and potency of dopaminergic modulation of striatal outputs by anchoring dopamine release sites to dopamine-sensing targets. PMID:27035941

  12. Four GABAergic interneurons impose feeding restraint in Drosophila

    PubMed Central

    Pool, Allan-Hermann; Kvello, Pal; Mann, Kevin; Cheung, Samantha K.; Gordon, Michael D.; Wang, Liming; Scott, Kristin

    2014-01-01

    Summary Feeding is dynamically regulated by the palatability of the food source and the physiological needs of the animal. How consumption is controlled by external sensory cues and internal metabolic state remains under intense investigation. Here, we identify four GABAergic interneurons in the Drosophila brain that establish a central feeding threshold which is required to inhibit consumption. Inactivation of these cells results in indiscriminate and excessive intake of all compounds, independent of taste quality or nutritional state. Conversely, acute activation of these neurons suppresses consumption of water and nutrients. The output from these neurons is required to gate activity in motor neurons that control meal initiation and consumption. Thus, our study reveals a new layer of inhibitory control in feeding circuits that is required to suppress a latent state of unrestricted and non-selective consumption. PMID:24991960

  13. Sensing the neuronal glycocalyx by glial sialic acid binding immunoglobulin-like lectins.

    PubMed

    Linnartz-Gerlach, B; Mathews, M; Neumann, H

    2014-09-01

    Sialic acid binding immunoglobulin-like lectins (Siglecs) are cell surface receptors of microglia and oligodendrocytes that recognize the sialic acid cap of healthy neurons and neighboring glial cells. Upon ligand binding, Siglecs typically signal through an immunoreceptor tyrosine-based inhibition motif (ITIM) to keep the cell in a homeostatic status and support healthy neighboring cells. Siglecs can be divided into two groups; the first, being conserved among different species. The conserved Siglec-4/myelin-associated glycoprotein is expressed on oligodendrocytes and Schwann cells. Siglec-4 protects neurons from acute toxicity via interaction with sialic acids bound to neuronal gangliosides. The second group of Siglecs, named CD33-related Siglecs, is almost exclusively expressed on immune cells and is highly variable among different species. Microglial expression of Siglec-11 is human lineage-specific and prevents neurotoxicity via interaction with α2.8-linked sialic acid oligomers exposed on the neuronal glycocalyx. Microglial Siglec-E is a mouse CD33-related Siglec member that prevents microglial phagocytosis and the associated oxidative burst. Mouse Siglec-E of microglia binds to α2.8- and α2.3-linked sialic acid residues of the healthy glycocalyx of neuronal and glial cells. Recently, polymorphisms of the human Siglec-3/CD33 were linked to late onset Alzheimer's disease by genome-wide association studies. Human Siglec-3 is expressed on microglia and produces inhibitory signaling that decreases uptake of particular molecules such as amyloid-β aggregates. Thus, glial ITIM-signaling Siglecs recognize the intact glycocalyx of neurons and are involved in the modulation of neuron-glia interaction in healthy and diseased brain.

  14. New insights into the classification and nomenclature of cortical GABAergic interneurons

    PubMed Central

    DeFelipe, Javier; López-Cruz, Pedro L.; Benavides-Piccione, Ruth; Bielza, Concha; Larrañaga, Pedro; Anderson, Stewart; Burkhalter, Andreas; Cauli, Bruno; Fairén, Alfonso; Feldmeyer, Dirk; Fishell, Gord; Fitzpatrick, David; Freund, Tamás F.; González-Burgos, Guillermo; Hestrin, Shaul; Hill, Sean; Hof, Patrick R.; Huang, Josh; Jones, Edward G.; Kawaguchi, Yasuo; Kisvárday, Zoltán; Kubota, Yoshiyuki; Lewis, David A.; Marín, Oscar; Markram, Henry; McBain, Chris J.; Meyer, Hanno S.; Monyer, Hannah; Nelson, Sacha B.; Rockland, Kathleen; Rossier, Jean; Rubenstein, John L. R.; Rudy, Bernardo; Scanziani, Massimo; Shepherd, Gordon M.; Sherwood, Chet C.; Staiger, Jochen F.; Tamás, Gábor; Thomson, Alex; Wang, Yun; Yuste, Rafael; Ascoli, Giorgio A.

    2013-01-01

    A systematic classification and accepted nomenclature of neuron types is much needed but is currently lacking. This article describes a possible taxonomical solution for classifying GABAergic interneurons of the cerebral cortex based on a novel, web-based interactive system that allows experts to classify neurons with pre-determined criteria. Using Bayesian analysis and clustering algorithms on the resulting data, we investigated the suitability of several anatomical terms and neuron names for cortical GABAergic interneurons. Moreover, we show that supervised classification models could automatically categorize interneurons in agreement with experts’ assignments. These results demonstrate a practical and objective approach to the naming, characterization and classification of neurons based on community consensus. PMID:23385869

  15. Revisiting the Lamotrigine-Mediated Effect on Hippocampal GABAergic Transmission

    PubMed Central

    Huang, Yu-Yin; Liu, Yu-Chao; Lee, Cheng-Ta; Lin, Yen-Chu; Wang, Mong-Lien; Yang, Yi-Ping; Chang, Kaung-Yi; Chiou, Shih-Hwa

    2016-01-01

    Lamotrigine (LTG) is generally considered as a voltage-gated sodium (Nav) channel blocker. However, recent studies suggest that LTG can also serve as a hyperpolarization-activated cyclic nucleotide-gated (HCN) channel enhancer and can increase the excitability of GABAergic interneurons (INs). Perisomatic inhibitory INs, predominantly fast-spiking basket cells (BCs), powerfully inhibit granule cells (GCs) in the hippocampal dentate gyrus. Notably, BCs express abundant Nav channels and HCN channels, both of which are able to support sustained action potential generation. Using whole-cell recording in rat hippocampal slices, we investigated the net LTG effect on BC output. We showed that bath application of LTG significantly decreased the amplitude of evoked compound inhibitory postsynaptic currents (IPSCs) in GCs. In contrast, simultaneous paired recordings from BCs to GCs showed that LTG had no effect on both the amplitude and the paired-pulse ratio of the unitary IPSCs, suggesting that LTG did not affect GABA release, though it suppressed cell excitability. In line with this, LTG decreased spontaneous IPSC (sIPSC) frequency, but not miniature IPSC frequency. When re-examining the LTG effect on GABAergic transmission in the cornus ammonis region 1 (CA1) area, we found that LTG markedly inhibits both the excitability of dendrite-targeting INs in the stratum oriens and the concurrent sIPSCs recorded on their targeting pyramidal cells (PCs) without significant hyperpolarization-activated current (Ih) enhancement. In summary, LTG has no effect on augmenting Ih in GABAergic INs and does not promote GABAergic inhibitory output. The antiepileptic effect of LTG is likely through Nav channel inhibition and the suppression of global neuronal network activity. PMID:27455251

  16. Increased acid responsiveness in vagal sensory neurons in a guinea pig model of eosinophilic esophagitis.

    PubMed

    Hu, Youtian; Liu, Zhenyu; Yu, Xiaoyun; Pasricha, Pankaj J; Undem, Bradley J; Yu, Shaoyong

    2014-07-15

    Eosinophilic esophagitis (EoE) is characterized with eosinophils and mast cells predominated allergic inflammation in the esophagus and present with esophageal dysfunctions such as dysphagia, food impaction, and heartburn. However, the underlying mechanism of esophageal dysfunctions is unclear. This study aims to determine whether neurons in the vagal sensory ganglia are modulated in a guinea pig model of EoE. Animals were actively sensitized by ovalbumin (OVA) and then challenged with aerosol OVA inhalation for 2 wk. This results in a mild esophagitis with increases in mast cells and eosinophils in the esophageal wall. Vagal nodose and jugular neurons were disassociated, and their responses to acid, capsaicin, and transient receptor potential vanilloid type 1 (TRPV1) antagonist AMG-9810 were studied by calcium imaging and whole cell patch-clamp recording. Compared with naïve animals, antigen challenge significantly increased acid responsiveness in both nodose and jugular neurons. Their responses to capsaicin were also increased after antigen challenge. AMG-9810, at a concentration that blocked capsaicin-evoked calcium influx, abolished the increase in acid-induced activation in both nodose and jugular neurons. Vagotomy strongly attenuated those increased responses of nodose and jugular neurons to both acid and capsaicin induced by antigen challenge. These data for the first time demonstrated that prolonged antigen challenge significantly increases acid responsiveness in vagal nodose and jugular ganglia neurons. This sensitization effect is mediated largely through TRPV1 and initiated at sensory nerve endings in the peripheral tissues. Allergen-induced enhancement of responsiveness to noxious stimulation by acid in sensory nerve may contribute to the development of esophageal dysfunctions such as heartburn in EoE.

  17. Differential Control of Cocaine Self-Administration by GABAergic and Glutamatergic CB1 Cannabinoid Receptors.

    PubMed

    Martín-García, Elena; Bourgoin, Lucie; Cathala, Adeline; Kasanetz, Fernando; Mondesir, Miguel; Gutiérrez-Rodriguez, Ana; Reguero, Leire; Fiancette, Jean-François; Grandes, Pedro; Spampinato, Umberto; Maldonado, Rafael; Piazza, Pier Vincenzo; Marsicano, Giovanni; Deroche-Gamonet, Véronique

    2016-08-01

    The type 1 cannabinoid receptor (CB1) modulates numerous neurobehavioral processes and is therefore explored as a target for the treatment of several mental and neurological diseases. However, previous studies have investigated CB1 by targeting it globally, regardless of its two main neuronal localizations on glutamatergic and GABAergic neurons. In the context of cocaine addiction this lack of selectivity is critical since glutamatergic and GABAergic neuronal transmission is involved in different aspects of the disease. To determine whether CB1 exerts different control on cocaine seeking according to its two main neuronal localizations, we used mutant mice with deleted CB1 in cortical glutamatergic neurons (Glu-CB1) or in forebrain GABAergic neurons (GABA-CB1). In Glu-CB1, gene deletion concerns the dorsal telencephalon, including neocortex, paleocortex, archicortex, hippocampal formation and the cortical portions of the amygdala. In GABA-CB1, it concerns several cortical and non-cortical areas including the dorsal striatum, nucleus accumbens, thalamic, and hypothalamic nuclei. We tested complementary components of cocaine self-administration, separating the influence of primary and conditioned effects. Mechanisms underlying each phenotype were explored using in vivo microdialysis and ex vivo electrophysiology. We show that CB1 expression in forebrain GABAergic neurons controls mouse sensitivity to cocaine, while CB1 expression in cortical glutamatergic neurons controls associative learning processes. In accordance, in the nucleus accumbens, GABA-CB1 receptors control cocaine-induced dopamine release and Glu-CB1 receptors control AMPAR/NMDAR ratio; a marker of synaptic plasticity. Our findings demonstrate a critical distinction of the altered balance of Glu-CB1 and GABA-CB1 activity that could participate in the vulnerability to cocaine abuse and addiction. Moreover, these novel insights advance our understanding of CB1 neuropathophysiology.

  18. Suppression of inhibitory GABAergic transmission by cAMP signaling pathway: alterations in learning and memory mutants

    PubMed Central

    Ganguly, Archan; Lee, Daewoo

    2013-01-01

    The cAMP signaling pathway mediates synaptic plasticity and is essential for memory formation in both vertebrate and invertebrates. In the fruit fly Drosophila melanogaster, mutations in the cAMP pathway lead to impaired olfactory learning. These mutant genes are preferentially expressed in the mushroom body (MB), an anatomical structure essential for learning. While cAMP-mediated synaptic plasticity is known to be involved in facilitation at the excitatory synapses, little is known about its function in GABAergic synaptic plasticity and learning. In this study, using whole-cell patch clamp technique on Drosophila primary neuronal cultures, we demonstrate that focal application of an adenylate cyclase activator forskolin (FSK) suppresses inhibitory GABAergic postsynaptic currents (IPSCs). We observed a dual regulatory role of FSK on GABAergic transmission, where it increases overall excitability at GABAergic synapses, while simultaneously acting on postsynaptic GABA receptors to suppress GABAergic IPSCs. Further we show that cAMP decreases GABAergic IPSCs in a PKA-dependent manner through a postsynaptic mechanism. PKA acts through the modulation of ionotropic GABA receptor sensitivity to the neurotransmitter GABA. This regulation of GABAergic IPSCs is altered in the cAMP pathway and short-term memory mutants dunce and rutabaga, with both showing altered GABA receptor sensitivity. Interestingly, this effect is also conserved in the MB neurons of both these mutants. Thus, our study suggests that alterations of cAMP-mediated GABAergic plasticity, particularly in the MB neurons of cAMP mutants, account for their defects in olfactory learning. PMID:23387411

  19. GABAergic signaling in the rat pineal gland.

    PubMed

    Yu, Haijie; Benitez, Sergio G; Jung, Seung-Ryoung; Farias Altamirano, Luz E; Kruse, Martin; Seo, Jong Bae; Koh, Duk-Su; Muñoz, Estela M; Hille, Bertil

    2016-08-01

    Pinealocytes secrete melatonin at night in response to norepinephrine released from sympathetic nerve terminals in the pineal gland. The gland also contains many other neurotransmitters whose cellular disposition, activity, and relevance to pineal function are not understood. Here, we clarify sources and demonstrate cellular actions of the neurotransmitter γ-aminobutyric acid (GABA) using Western blotting and immunohistochemistry of the gland and electrical recording from pinealocytes. GABAergic cells and nerve fibers, defined as containing GABA and the synthetic GAD67, were identified. The cells represent a subset of interstitial cells while the nerve fibers were distinct from the sympathetic innervation. The GABAA receptor subunit α1 was visualized in close proximity of both GABAergic and sympathetic nerve fibers as well as fine extensions among pinealocytes and blood vessels. The GABAB 1 receptor subunit was localized in the interstitial compartment but not in pinealocytes. Electrophysiology of isolated pinealocytes revealed that GABA and muscimol elicit strong inward chloride currents sensitive to bicuculline and picrotoxin, clear evidence for functional GABAA receptors on the surface membrane. Applications of elevated potassium solution or the neurotransmitter acetylcholine depolarized the pinealocyte membrane potential enough to open voltage-gated Ca(2+) channels leading to intracellular calcium elevations. GABA repolarized the membrane and shut off such calcium rises. In 48-72-h cultured intact glands, GABA application neither triggered melatonin secretion by itself nor affected norepinephrine-induced secretion. Thus, strong elements of GABA signaling are present in pineal glands that make large electrical responses in pinealocytes, but physiological roles need to be found.

  20. Excitatory amino acid transporter 2 downregulation correlates with thalamic neuronal death following kainic acid-induced status epilepticus in rat.

    PubMed

    Sakurai, Masashi; Kurokawa, Haruna; Shimada, Akinori; Nakamura, Kazuhiro; Miyata, Hajime; Morita, Takehito

    2015-02-01

    Recurrent seizures without interictal resumption (status epilepticus) have been reported to induce neuronal death in the midline thalamic region that has functional roles in memory and decision-making; however, the pathogenesis underlying status epilepticus-induced thalamic neuronal death is yet to be determined. We performed histological and immunohistochemical studies as well as cerebral blood flow measurement using 4.7 tesla magnetic resonance imaging spectrometer on midline thalamic region in Sprague-Dawley rats (n = 75, male, 7 weeks after birth, body weight 250-300 g) treated with intraperitoneal injection of kainic acid (10 mg/kg) to induce status epilepticus (n = 55) or normal saline solution (n = 20). Histological study using paraffin-embedded specimens revealed neuronal death showing ischemic-like changes and Fluoro-Jade C positivity with calcium deposition in the midline thalamic region of epileptic rats. The distribution of neuronal death was associated with focal loss of immunoreactivity for excitatory amino acid transporter 2 (EAAT2), stronger immunoreaction for glutamate and increase in number of Iba-1-positive microglial cells showing swollen cytoplasm and long processes. Double immunofluorescence study demonstrated co-expression of interleukin-1 beta (IL-1β) and inducible nitric oxide synthase (iNOS) within microglial cells, and loss of EAAT2 immunoreactivity in reactive astrocytes. These microglial alterations and astrocytic EAAT2 downregulation were also observed in tissue without obvious neuronal death in kainic acid-treated rats. These results suggest the possible role of glutamate excitotoxicity in neuronal death in the midline thalamic region following kainic acid-induced status epilepticus due to astrocytic EAAT2 downregulation following microglial activation showing upregulation of IL-1β and iNOS.

  1. Intracellular pH regulation by acid-base transporters in mammalian neurons

    PubMed Central

    Ruffin, Vernon A.; Salameh, Ahlam I.; Boron, Walter F.; Parker, Mark D.

    2014-01-01

    Intracellular pH (pHi) regulation in the brain is important in both physiological and physiopathological conditions because changes in pHi generally result in altered neuronal excitability. In this review, we will cover 4 major areas: (1) The effect of pHi on cellular processes in the brain, including channel activity and neuronal excitability. (2) pHi homeostasis and how it is determined by the balance between rates of acid loading (JL) and extrusion (JE). The balance between JE and JL determine steady-state pHi, as well as the ability of the cell to defend pHi in the face of extracellular acid-base disturbances (e.g., metabolic acidosis). (3) The properties and importance of members of the SLC4 and SLC9 families of acid-base transporters expressed in the brain that contribute to JL (namely the Cl-HCO3 exchanger AE3) and JE (the Na-H exchangers NHE1, NHE3, and NHE5 as well as the Na+- coupled HCO3− transporters NBCe1, NBCn1, NDCBE, and NBCn2). (4) The effect of acid-base disturbances on neuronal function and the roles of acid-base transporters in defending neuronal pHi under physiopathologic conditions. PMID:24592239

  2. Drosophila fatty acid taste signals through the PLC pathway in sugar-sensing neurons.

    PubMed

    Masek, Pavel; Keene, Alex C

    2013-01-01

    Taste is the primary sensory system for detecting food quality and palatability. Drosophila detects five distinct taste modalities that include sweet, bitter, salt, water, and the taste of carbonation. Of these, sweet-sensing neurons appear to have utility for the detection of nutritionally rich food while bitter-sensing neurons signal toxicity and confer repulsion. Growing evidence in mammals suggests that taste for fatty acids (FAs) signals the presence of dietary lipids and promotes feeding. While flies appear to be attracted to fatty acids, the neural basis for fatty acid detection and attraction are unclear. Here, we demonstrate that a range of FAs are detected by the fly gustatory system and elicit a robust feeding response. Flies lacking olfactory organs respond robustly to FAs, confirming that FA attraction is mediated through the gustatory system. Furthermore, flies detect FAs independent of pH, suggesting the molecular basis for FA taste is not due to acidity. We show that low and medium concentrations of FAs serve as an appetitive signal and they are detected exclusively through the same subset of neurons that sense appetitive sweet substances, including most sugars. In mammals, taste perception of sweet and bitter substances is dependent on phospholipase C (PLC) signaling in specialized taste buds. We find that flies mutant for norpA, a Drosophila ortholog of PLC, fail to respond to FAs. Intriguingly, norpA mutants respond normally to other tastants, including sucrose and yeast. The defect of norpA mutants can be rescued by selectively restoring norpA expression in sweet-sensing neurons, corroborating that FAs signal through sweet-sensing neurons, and suggesting PLC signaling in the gustatory system is specifically involved in FA taste. Taken together, these findings reveal that PLC function in Drosophila sweet-sensing neurons is a conserved molecular signaling pathway that confers attraction to fatty acids.

  3. Is there in vivo evidence for amino acid shuttles carrying ammonia from neurons to astrocytes?

    PubMed

    Rothman, Douglas L; De Feyter, Henk M; Maciejewski, Paul K; Behar, Kevin L

    2012-11-01

    The high in vivo flux of the glutamate/glutamine cycle puts a strong demand on the return of ammonia released by phosphate activated glutaminase from the neurons to the astrocytes in order to maintain nitrogen balance. In this paper we review several amino acid shuttles that have been proposed for balancing the nitrogen flows between neurons and astrocytes in the glutamate/glutamine cycle. All of these cycles depend on the directionality of glutamate dehydrogenase, catalyzing reductive glutamate synthesis (forward reaction) in the neuron in order to capture the ammonia released by phosphate activated glutaminase, while catalyzing oxidative deamination of glutamate (reverse reaction) in the astrocytes to release ammonia for glutamine synthesis. Reanalysis of results from in vivo experiments using (13)N and (15)N labeled ammonia and (15)N leucine in rats suggests that the maximum flux of the alanine/lactate or branched chain amino acid/branched chain amino acid transaminase shuttles between neurons and astrocytes are approximately 3-5 times lower than would be required to account for the ammonia transfer from neurons to astrocytes needed for glutamine synthesis (amide nitrogen) to sustain the glutamate/glutamine cycle. However, in the rat brain both the total ammonia fixation rate by glutamate dehydrogenase and the total branched chain amino acid transaminase activity are sufficient to support a branched chain amino acid/branched chain keto acid shuttle, as proposed by Hutson and coworkers, which would support the de novo synthesis of glutamine in the astrocyte to replace the ~20 % of neurotransmitter glutamate that is oxidized. A higher fraction of the nitrogen needs of total glutamate neurotransmitter cycling could be supported by hybrid cycles in which glutamate and tricarboxylic acid cycle intermediates act as a nitrogen shuttle. A limitation of all in vivo studies in animals conducted to date is that none have shown transfer of nitrogen for glutamine amide

  4. Environmental enrichment as a therapeutic avenue for anxiety in aged Wistar rats: Effect on cat odor exposition and GABAergic interneurons.

    PubMed

    Sampedro-Piquero, P; Castilla-Ortega, E; Zancada-Menendez, C; Santín, L J; Begega, A

    2016-08-25

    The use of more ethological animal models to study the neurobiology of anxiety has increased in recent years. We assessed the effect of an environmental enrichment (EE) protocol (24h/day over a period of two months) on anxiety-related behaviors when aged Wistar rats (21months old) were confronted with cat odor stimuli. Owing to the relationship between GABAergic interneurons and the anxiety-related neuronal network, we examined changes in the expression of Parvalbumin (PV) and 67kDa form of glutamic acid decarboxylase (GAD-67) immunoreactive cells in different brain regions involved in stress response. Behavioral results revealed that enriched rats traveled further and made more grooming behaviors during the habituation session. In the cat odor session, they traveled longer distances and they showed more active interaction with the odor stimuli and less time in freezing behavior. Zone analysis revealed that the enriched group spent more time in the intermediate zone according to the proximity of the predator odor. Regarding the neurobiological data, the EE increased the expression of PV-positive cells in some medial prefrontal regions (cingulate (Cg) and prelimbic (PL) cortices), whereas the GAD-67 expression in the basolateral amygdala was reduced in the enriched group. Our results suggest that EE is able to reduce anxiety-like behaviors in aged animals even when ethologically relevant stimuli are used. Moreover, GABAergic interneurons could be involved in mediating this resilient behavior. PMID:27235742

  5. Environmental enrichment as a therapeutic avenue for anxiety in aged Wistar rats: Effect on cat odor exposition and GABAergic interneurons.

    PubMed

    Sampedro-Piquero, P; Castilla-Ortega, E; Zancada-Menendez, C; Santín, L J; Begega, A

    2016-08-25

    The use of more ethological animal models to study the neurobiology of anxiety has increased in recent years. We assessed the effect of an environmental enrichment (EE) protocol (24h/day over a period of two months) on anxiety-related behaviors when aged Wistar rats (21months old) were confronted with cat odor stimuli. Owing to the relationship between GABAergic interneurons and the anxiety-related neuronal network, we examined changes in the expression of Parvalbumin (PV) and 67kDa form of glutamic acid decarboxylase (GAD-67) immunoreactive cells in different brain regions involved in stress response. Behavioral results revealed that enriched rats traveled further and made more grooming behaviors during the habituation session. In the cat odor session, they traveled longer distances and they showed more active interaction with the odor stimuli and less time in freezing behavior. Zone analysis revealed that the enriched group spent more time in the intermediate zone according to the proximity of the predator odor. Regarding the neurobiological data, the EE increased the expression of PV-positive cells in some medial prefrontal regions (cingulate (Cg) and prelimbic (PL) cortices), whereas the GAD-67 expression in the basolateral amygdala was reduced in the enriched group. Our results suggest that EE is able to reduce anxiety-like behaviors in aged animals even when ethologically relevant stimuli are used. Moreover, GABAergic interneurons could be involved in mediating this resilient behavior.

  6. Altered expression of KCC2 in GABAergic interneuron contributes prenatal stress-induced epileptic spasms in infant rat.

    PubMed

    Baek, Hyunjung; Yi, Min-Hee; Pandit, Sudip; Park, Jin Bong; Kwon, Hyeok Hee; Zhang, Enji; Kim, Sena; Shin, Nara; Kim, Eunjee; Lee, Young Ho; Kim, Yonghyun; Kim, Dong Woon; Kang, Joon Won

    2016-07-01

    Long-term stress during pregnancy causes neurologic deficits to offspring with altered gamma-aminobutyric acid (GABA) system in the brain. However, it is not clear how prenatal stress affects the maturing GABAergic interneurons and the resulting abnormalities in infantile seizures. Here, we showed that prenatal stress alters the maturation of GABA inhibitory system using a seizure model induced by prenatal stress. Prenatal stress with betamethasone or acute immobilization stress (AIS) on gestational day 15 increased the seizure susceptibility to N-methyl-d-aspartate-triggered spasms on postnatal day 15. The expression of GABA was lower in the prenatally stressed group, which compromise the decrease of glutamate decarboxylase 67-immunopositive cells. Prenatal stress markedly decreased the expression of K(+)/Cl(-) co-transporter (KCC2) in the cortex. GABA induced membrane depolarization demonstrated prenatal stress models had significant higher membrane depolarization compared to control. GABA increased KCC2 expression in cultured cortex-containing slices. Taken together, our results showed that prenatal stress with betamethasone or AIS altered the maturation of GABAergic progenitors and resulted in the lack of GABA input, which in turn, decreased KCC2 expression and lowered seizure threshold. We conclude that delayed GABA excitatory/inhibitory shift would render the cortical neuronal circuit more susceptible to excitatory input in prenatal stress induced seizure. PMID:27180051

  7. Conditional deletion of Mecp2 in parvalbumin-expressing GABAergic cells results in the absence of critical period plasticity.

    PubMed

    He, Ling-jie; Liu, Nan; Cheng, Tian-lin; Chen, Xiao-jing; Li, Yi-ding; Shu, You-sheng; Qiu, Zi-long; Zhang, Xiao-hui

    2014-10-09

    Mutations in the X-linked gene encoding the transcriptional modulator methyl-CpG-binding protein 2 (MeCP2) impair postnatal development of the brain. Here we use neuronal-type specific gene deletion in mice to show that conditional Mecp2 deletion in GABAergic parvalbumin-expressing (PV) cells (PV-Mecp2(-/y)) does not cause most Rett-syndrome-like behaviours, but completely abolishes experience-dependent critical period plasticity of primary visual cortex (V1) that develops normal visual functions. However, selective loss of Mecp2 in GABAergic somatostatin-expressing cells or glutamatergic pyramidal cells does not affect the critical period plasticity. MeCP2-deficient PV cells exhibit high intrinsic excitability, selectively reduced efficacy of recurrent excitatory synapses in V1 layer 4 circuits, and decreased evoked visual responses in vivo. Enhancing cortical gamma-aminobutyric acid (GABA) inhibition with diazepam infusion can restore critical period plasticity in both young and adult PV-Mecp2(-/y) mice. Thus, MeCP2 expression in inhibitory PV cells during the critical period is essential for local circuit functions underlying experience-dependent cortical plasticity.

  8. Amino acids modify thalamo-cortical response transformation expressed by neurons of the ventrobasal complex.

    PubMed

    Vahle-Hinz, C; Hicks, T P; Gottschaldt, K M

    1994-02-21

    The hypothesis has been tested that inhibitory mechanisms, active spatially and temporally between the input and the output of thalamic neurons, determine the nature of the information transmitted to the cerebral cortex. To enable this assessment, in barbiturate-anesthetized cats and urethane-anesthetized rats juxtacellular recordings were performed together with microiontophoretic ejection of transmitter agonists and antagonists. The effects of these drugs were studied on responses evoked by mechanical stimulation of cutaneous receptive fields (RFs) of neurons in the thalamic ventrobasal complex (VB). Neurons from different parts of the VB were investigated: 29 units were located medially, in the ventral posteromedial nucleus (VPM; facial RFs), and 11 units were located laterally, in the ventral posterolateral nucleus (VPL; forepaw and body RFs). A further eleven VB units had no detectable RF. Twenty-six neurons were tested with electrical stimulation of the somatosensory cortex (SI), 17 of these being identified as thalamo-cortical relay neurons and 5 being classified as presumed interneurons; the remaining 4 could not be activated. Four additional recordings were from trigemino-thalamic or thalamo-cortical fibers. For the quantitative assessment of the neurons' input and output, neuronal activity was induced by feedback-controlled, mechanical trapezoidal and/or sinusoidal stimuli applied to sinus hairs, fur or skin and the numbers of prepotentials and soma spikes were compared in peristimulus time histograms (PSTHs) generated simultaneously for both types of signal from 'DC' recordings. Iontophoretic administration of excitatory amino acids (EAAs) or bicuculline methiodide (BMI) increased output-input ratios in 87% of the cases tested, due to a higher rate of conversion of prepotentials into soma spikes taking place. In cases of neurons exhibiting a sustained-to-transient response pattern, changes to sustained-to-sustained patterns were demonstrated. Tests with

  9. Akting up in the GABA hypothesis of schizophrenia: Akt1 deficiency modulates GABAergic functions and hippocampus-dependent functions.

    PubMed

    Chang, Chia-Yuan; Chen, Yi-Wen; Wang, Tsu-Wei; Lai, Wen-Sung

    2016-01-01

    Accumulating evidence implies that both AKT1 and GABAA receptor (GABAAR) subunit genes are involved in schizophrenia pathogenesis. Activated Akt promotes GABAergic neuron differentiation and increases GABAAR expression on the plasma membrane. To elucidate the role of Akt1 in modulating GABAergic functions and schizophrenia-related cognitive deficits, a set of 6 in vitro and in vivo experiments was conducted. First, an Akt1/2 inhibitor was applied to evaluate its effect on GABAergic neuron-like cell formation from P19 cells. Inhibiting Akt resulted in a reduction in parvalbumin-positive neuron-like cells. In Akt1(-/-) and wild-type mice, seizures induced using pentylenetetrazol (a GABAAR antagonist) were measured, and GABAAR expression and GABAergic interneuron abundance in the brain were examined. Female Akt1(-/-) mice, but not male Akt1(-/-) mice, exhibited less pentylenetetrazol-induced convulsive activity than their corresponding wild-type controls. Reduced parvalbumin-positive interneuron abundance and GABAAR subunit expression, especially in the hippocampus, were also observed in female Akt1(-/-) mice compared to female wild-type mice. Neuromorphometric analyses revealed significantly reduced neurite complexity in hippocampal pyramidal neurons. Additionally, female Akt1(-/-) mice displayed increased hippocampal oscillation power and impaired spatial memory compared to female wild-type mice. Our findings suggest that Akt1 deficiency modulates GABAergic interneurons and GABAAR expression, contributing to hippocampus-dependent cognitive functional impairment.

  10. Modulation of GABAergic transmission in development and neurodevelopmental disorders: investigating physiology and pathology to gain therapeutic perspectives

    PubMed Central

    Deidda, Gabriele; Bozarth, Ignacio F.; Cancedda, Laura

    2014-01-01

    During mammalian ontogenesis, the neurotransmitter GABA is a fundamental regulator of neuronal networks. In neuronal development, GABAergic signaling regulates neural proliferation, migration, differentiation, and neuronal-network wiring. In the adult, GABA orchestrates the activity of different neuronal cell-types largely interconnected, by powerfully modulating synaptic activity. GABA exerts these functions by binding to chloride-permeable ionotropic GABAA receptors and metabotropic GABAB receptors. According to its functional importance during development, GABA is implicated in a number of neurodevelopmental disorders such as autism, Fragile X, Rett syndrome, Down syndrome, schizophrenia, Tourette's syndrome and neurofibromatosis. The strength and polarity of GABAergic transmission is continuously modulated during physiological, but also pathological conditions. For GABAergic transmission through GABAA receptors, strength regulation is achieved by different mechanisms such as modulation of GABAA receptors themselves, variation of intracellular chloride concentration, and alteration in GABA metabolism. In the never-ending effort to find possible treatments for GABA-related neurological diseases, of great importance would be modulating GABAergic transmission in a safe and possibly physiological way, without the dangers of either silencing network activity or causing epileptic seizures. In this review, we will discuss the different ways to modulate GABAergic transmission normally at work both during physiological and pathological conditions. Our aim is to highlight new research perspectives for therapeutic treatments that reinstate natural and physiological brain functions in neuro-pathological conditions. PMID:24904277

  11. Akting up in the GABA hypothesis of schizophrenia: Akt1 deficiency modulates GABAergic functions and hippocampus-dependent functions.

    PubMed

    Chang, Chia-Yuan; Chen, Yi-Wen; Wang, Tsu-Wei; Lai, Wen-Sung

    2016-01-01

    Accumulating evidence implies that both AKT1 and GABAA receptor (GABAAR) subunit genes are involved in schizophrenia pathogenesis. Activated Akt promotes GABAergic neuron differentiation and increases GABAAR expression on the plasma membrane. To elucidate the role of Akt1 in modulating GABAergic functions and schizophrenia-related cognitive deficits, a set of 6 in vitro and in vivo experiments was conducted. First, an Akt1/2 inhibitor was applied to evaluate its effect on GABAergic neuron-like cell formation from P19 cells. Inhibiting Akt resulted in a reduction in parvalbumin-positive neuron-like cells. In Akt1(-/-) and wild-type mice, seizures induced using pentylenetetrazol (a GABAAR antagonist) were measured, and GABAAR expression and GABAergic interneuron abundance in the brain were examined. Female Akt1(-/-) mice, but not male Akt1(-/-) mice, exhibited less pentylenetetrazol-induced convulsive activity than their corresponding wild-type controls. Reduced parvalbumin-positive interneuron abundance and GABAAR subunit expression, especially in the hippocampus, were also observed in female Akt1(-/-) mice compared to female wild-type mice. Neuromorphometric analyses revealed significantly reduced neurite complexity in hippocampal pyramidal neurons. Additionally, female Akt1(-/-) mice displayed increased hippocampal oscillation power and impaired spatial memory compared to female wild-type mice. Our findings suggest that Akt1 deficiency modulates GABAergic interneurons and GABAAR expression, contributing to hippocampus-dependent cognitive functional impairment. PMID:27615800

  12. Akting up in the GABA hypothesis of schizophrenia: Akt1 deficiency modulates GABAergic functions and hippocampus-dependent functions

    PubMed Central

    Chang, Chia-Yuan; Chen, Yi-Wen; Wang, Tsu-Wei; Lai, Wen-Sung

    2016-01-01

    Accumulating evidence implies that both AKT1 and GABAA receptor (GABAAR) subunit genes are involved in schizophrenia pathogenesis. Activated Akt promotes GABAergic neuron differentiation and increases GABAAR expression on the plasma membrane. To elucidate the role of Akt1 in modulating GABAergic functions and schizophrenia-related cognitive deficits, a set of 6 in vitro and in vivo experiments was conducted. First, an Akt1/2 inhibitor was applied to evaluate its effect on GABAergic neuron-like cell formation from P19 cells. Inhibiting Akt resulted in a reduction in parvalbumin-positive neuron-like cells. In Akt1−/− and wild-type mice, seizures induced using pentylenetetrazol (a GABAAR antagonist) were measured, and GABAAR expression and GABAergic interneuron abundance in the brain were examined. Female Akt1−/− mice, but not male Akt1−/− mice, exhibited less pentylenetetrazol-induced convulsive activity than their corresponding wild-type controls. Reduced parvalbumin-positive interneuron abundance and GABAAR subunit expression, especially in the hippocampus, were also observed in female Akt1−/− mice compared to female wild-type mice. Neuromorphometric analyses revealed significantly reduced neurite complexity in hippocampal pyramidal neurons. Additionally, female Akt1−/− mice displayed increased hippocampal oscillation power and impaired spatial memory compared to female wild-type mice. Our findings suggest that Akt1 deficiency modulates GABAergic interneurons and GABAAR expression, contributing to hippocampus-dependent cognitive functional impairment. PMID:27615800

  13. Xanthurenic acid is localized in neurons in the central nervous system.

    PubMed

    Roussel, Guy; Bessede, Alban; Klein, Christian; Maitre, Michel; Mensah-Nyagan, Ayikoe Guy

    2016-08-01

    Kynurenine pathway metabolites (KPM) are thought to be synthesized mainly by non-neuronal cells in the mammalian brain. KPM are of particular interest because several studies demonstrated their implication in various disorders of the nervous system. Among KPM is xanthurenic acid (XA) deriving from the catabolism of 3-hydroxykynurenine. Based on its chemical structure, XA appears as a close analog of kynurenic acid which has been extensively investigated and is considered as a potent neuroprotective compound. Contrary to kynurenic acid (KYNA), XA has received little attention and its role in the brain remains not elucidated. We have previously described several characteristics of XA, suggesting its possible involvement in neurotransmission. XA is also proposed as a potential modulator at glutamatergic synapses. Here, we used a selective antibody against XA and various neuronal, glial and synaptic markers to show that XA is essentially localized in the soma and dendrites of brain neurons, but is absent from axonal compartments and terminal endings. Our results also reveal that XA-like immunoreactivity is not expressed by glial cells. To double-check our findings, we have also used another XA antibody obtained from a commercial source to confirm the neuronal expression of XA. Together, our results suggest that, differently to several other KPM produced by glial cells, XA exhibits a neuronal distribution in the mouse brain. PMID:27167083

  14. VTA glutamatergic inputs to nucleus accumbens drive aversion by acting on GABAergic interneurons

    PubMed Central

    Qi, Jia; Zhang, Shiliang; Wang, Hui-Ling; Barker, David J.; Miranda-Barrientos, Jorge; Morales, Marisela

    2016-01-01

    The ventral tegmental area (VTA) is best known for its dopamine neurons, some of which project to nucleus accumbens (nAcc). However, the VTA also has glutamatergic neurons that project to nAcc. The function of the mesoaccumbens-glutamatergic pathway remains unknown. Here, we report that nAcc photoactivation of mesoaccumbens-glutamatergic fibers promotes aversion. Although we found that these mesoaccumbens-glutamate-fibers lack GABA, the aversion evoked by their photoactivation depends on glutamate and GABA receptor signaling, and not on dopamine receptor signaling. We found that mesoaccumbens-glutamatergic-fibers establish multiple asymmetric synapses on single parvalbumin-GABAergic interneurons, and that nAcc photoactivation of these fibers drives AMPA-mediated cellular firing of parvalbumin-GABAergic interneurons. These parvalbumin-GABAergic-interneurons, in turn, inhibit nAcc medium spiny output neurons, as such, controlling inhibitory neurotransmission within nAcc. The mesoaccumbens-glutamatergic pathway is the first glutamatergic input to nAcc shown to mediate aversion, instead of reward, and the first pathway shown to establish excitatory synapses on nAcc parvalbumin-GABAergic interneurons. PMID:27019014

  15. Reducing GABAergic inhibition restores cognitive functions in a mouse model of Down syndrome.

    PubMed

    Potier, Marie-Claude; Braudeau, Jérôme; Dauphinot, Luce; Delatour, Benoît

    2014-02-01

    Alterations in excitatory-inhibitory balance occur in Down syndrome and could be responsible for cognitive deficits observed through the life of all individuals carrying an extra copy of chromosome 21. Excess of inhibition in the adult could produce synaptic plasticity deficits that may be a primary mechanism contributing to learning and memory impairments. In this study we discuss pharmacological treatments that could potentially alleviate neuronal inhibition and have been tested in a mouse model of Down syndrome. γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mature central nervous system that binds to GABA-benzodiazepine receptors, opens a chloride channel and reduces neuronal excitability. These receptors have been extensively studied as targets for treatment of epilepsy, anxiety, sleep, cognitive disorders and the induction of sedation. Molecules that are either antagonists or inverse agonists of the GABA-benzodiazepine receptors are able to reduce inhibitory GABAergic transmission. However modulating the excitatory-inhibitory balance towards increase of cognition without inducing seizures remains difficult particularly when using GABA antagonists. In this study we review data from the literature obtained using inverse agonists selective for the α5-subunit containing receptor. Such inverse agonists, initially developed as cognitive enhancers for treatment of memory impairments, proved to be very efficient in reversing learning and memory deficits in a Down syndrome mouse model after acute treatment.

  16. Genetic disruption of Met signaling impairs GABAergic striatal development and cognition

    PubMed Central

    Martins, Gabriela J.; Shahrokh, Mondona; Powell, Elizabeth M.

    2011-01-01

    The largest structure of the basal ganglia, the striatum, modulates motor activity and cognitive function and is composed of GABAergic projection neurons and interneurons. To better understand the mechanisms underlying the development of the striatal neurons and their assembly into functional circuits, we used a mouse with a targeted conditional Met mutation in post-mitotic cells of the ventral telencephalon. Characterization of the ontogeny of the striatal neuronal populations demonstrated that disruption of Met signaling specifically altered the GABAergic interneurons. Medium spiny neurons and cholinergic interneurons were largely unaffected. Mice lacking Met signaling have increased numbers of striatal GABAergic interneurons in the lateral sensorimotor areas with distinct behavioral deficits. Motor function and memory formation and consolidation appeared intact, but procedural learning on the cued task of the Morris water maze was delayed. MET is a susceptibility gene in Tourette Syndrome and autism, which are human disorders with impaired procedural learning. This study reveals how a striatal targeted disruption in Met signaling after generation of striatal neurons produces behavioral phenotypes shared by Tourette Syndrome and autism, linking the human genetics with the mechanism underlying the disorders. PMID:21195751

  17. Gamma-aminobutyric acid circuits shape response properties of auditory cortex neurons.

    PubMed

    Wang, Jian; McFadden, Sandra L; Caspary, Donald; Salvi, Richard

    2002-07-19

    Neurons containing gamma aminobutyric acid (GABA) are widely distributed throughout the primary auditory cortex (AI). We investigated the effects of endogenous GABA by comparing response properties of 110 neurons in chinchilla AI before and after iontophoresis of bicuculline, a GABA(A) receptor antagonist, and/or CGP35348, a GABA(B) receptor antagonist. GABA(A) receptor blockade significantly increased spontaneous and driven discharge rates, dramatically decreased the thresholds of many neurons, and constricted the range of thresholds across the neural population. Some neurons with 'non-onset' temporal discharge patterns developed an onset pattern that was followed by a long pause. Interestingly, the excitatory response area typically expanded on both sides of the characteristic frequency; this expansion exceeded one octave in a third of the sample. Although GABA(B) receptor blockade had little effect alone, the combination of CGP35348 and bicuculline produced greater increases in driven rate and expansion of the frequency response area than GABA(A) receptor blockade alone, suggesting a modulatory role of local GABA(B) receptors. The results suggest that local GABA inhibition contributes significantly to intensity and frequency coding by controlling the range of intensities over which cortical neurons operate and the range of frequencies to which they respond. The inhibitory circuits that generate nonmonotonic rate-level functions are separate from those that influence other response properties of AI neurons. PMID:12106684

  18. Spike timing-dependent plasticity at GABAergic synapses in the ventral tegmental area.

    PubMed

    Kodangattil, Jayaraj N; Dacher, Matthieu; Authement, Michael E; Nugent, Fereshteh S

    2013-10-01

    Persistent changes in excitatory and inhibitory synaptic strengths to the ventral tegmental area (VTA) dopamine (DA) neurons in response to addictive drugs may underlie the transition from casual to compulsive drug use. While an enormous amount of work has been done in the area of glutamatergic plasticity of the VTA, little is known regarding the learning rules governing GABAergic plasticity in the VTA. Spike timing-dependent plasticity, STDP, has attracted considerable attention primarily due to its potential roles in processing and storage of information in the brain and there is emerging evidence for the existence of STDP at inhibitory synapses. We therefore used whole-cell recordings in rat midbrain slices to investigate whether near-coincident pre- and postsynaptic firing induces a lasting change in synaptic efficacy of VTA GABAergic synapses. We found that a Hebbian form of STDP including long-term potentiation (LTP) and long-term depression (LTD) can be induced at GABAergic synapses onto VTA DA neurons and relies on the precise temporal order of pre- and postsynaptic spiking. Importantly, GABAergic STDP is heterosynaptic (NMDA receptor dependent): triggered by correlated activities of the presynaptic glutamatergic input and postsynaptic DA cells. GABAergic STDP is postsynaptic and has an associative component since pre- or postsynaptic spiking per se did not induce STDP. STDP of GABAergic synapses in the VTA provides physiologically relevant forms of inhibitory plasticity that may underlie natural reinforcement of reward-related behaviours. Moreover, this form of inhibitory plasticity may mediate some of the reinforcing, aversive and addictive properties of drugs of abuse.

  19. Shift from phasic to tonic GABAergic transmission following laser-lesions in the rat visual cortex.

    PubMed

    Imbrosci, Barbara; Neubacher, Ute; White, Robin; Eysel, Ulf T; Mittmann, Thomas

    2013-06-01

    Reduction in the strength of GABAergic neurotransmission has often been reported following brain lesions. This weakened inhibition is believed to influence neurological deficits, neuronal hyperexcitability and functional recovery after brain injuries. Uncovering the mechanisms underlying the altered inhibition is therefore crucial. In the present study we used an ex vivo-in vitro model of laser lesions in the rat visual cortex to characterize the cellular correlates of changes in GABAergic transmission in the tissue adjacent to the injury. In the first week post-injury the number of VGAT positive GABAergic terminals as well as the expression level of the GABA synthesizing enzymes GAD67 and GAD65 remained unaltered. However, a reduced frequency of miniature inhibitory postsynaptic currents (mIPSCs) together with an increased paired-pulse ratio (PPR) of evoked IPSCs suggested a functional reduction of phasic GABA release. In parallel, we found an enhancement in the GABAA receptor-mediated tonic inhibition. On the basis of these findings, we propose that cortical lesions provoke a shift in GABAergic transmission, decreasing the phasic and reinforcing the tonic component. We therefore suggest that it is not, as traditionally assumed, the overall inhibitory strength to be primarily compromised by a cortical lesion but rather the temporal accuracy of the GABAergic synaptic signaling. PMID:23224682

  20. NMDA-Dependent Switch of proBDNF Actions on Developing GABAergic Synapses

    PubMed Central

    Langlois, Anais; Diabira, Diabe; Ferrand, Nadine; Porcher, Christophe

    2013-01-01

    The brain-derived neurotrophic factor (BDNF) has emerged as an important messenger for activity-dependent development of neuronal network. Recent findings have suggested that a significant proportion of BDNF can be secreted as a precursor (proBDNF) and cleaved by extracellular proteases to yield the mature form. While the actions of proBDNF on maturation and plasticity of excitatory synapses have been studied, the effect of the precursor on developing GABAergic synapses remains largely unknown. Here, we show that regulated secretion of proBDNF exerts a bidirectional control of GABAergic synaptic activity with NMDA receptors driving the polarity of the plasticity. When NMDA receptors are activated during ongoing synaptic activity, regulated Ca2+-dependent secretion of proBDNF signals via p75NTR to depress GABAergic synaptic activity, while in the absence of NMDA receptors activation, secreted proBDNF induces a p75NTR-dependent potentiation of GABAergic synaptic activity. These results revealed a new function for proBDNF-p75NTR signaling in synaptic plasticity and a novel mechanism by which synaptic activity can modulate the development of GABAergic synaptic connections. PMID:22510533

  1. Behavioral and EEG effects of GABAergic manipulation of the nigro-tectal pathway in the Wistar audiogenic rat (WAR) strain II: an EEG wavelet analysis and retrograde neuronal tracer approach.

    PubMed

    Rossetti, Franco; Rodrigues, Marcelo Cairrão Araújo; Marroni, Simone S; Fernandes, Artur; Foresti, Maira Licia; Romcy-Pereira, Rodrigo N; de Araújo, Dráulio Barros; Garcia-Cairasco, Norberto

    2012-08-01

    The role of the substantia nigra pars reticulata (SNPr) and superior colliculus (SC) network in rat strains susceptible to audiogenic seizures still remain underexplored in epileptology. In a previous study from our laboratory, the GABAergic drugs bicuculline (BIC) and muscimol (MUS) were microinjected into the deep layers of either the anterior SC (aSC) or the posterior SC (pSC) in animals of the Wistar audiogenic rat (WAR) strain submitted to acoustic stimulation, in which simultaneous electroencephalographic (EEG) recording of the aSC, pSC, SNPr and striatum was performed. Only MUS microinjected into the pSC blocked audiogenic seizures. In the present study, we expanded upon these previous results using the retrograde tracer Fluorogold (FG) microinjected into the aSC and pSC in conjunction with quantitative EEG analysis (wavelet transform), in the search for mechanisms associated with the susceptibility of this inbred strain to acoustic stimulation. Our hypothesis was that the WAR strain would have different connectivity between specific subareas of the superior colliculus and the SNPr when compared with resistant Wistar animals and that these connections would lead to altered behavior of this network during audiogenic seizures. Wavelet analysis showed that the only treatment with an anticonvulsant effect was MUS microinjected into the pSC region, and this treatment induced a sustained oscillation in the theta band only in the SNPr and in the pSC. These data suggest that in WAR animals, there are at least two subcortical loops and that the one involved in audiogenic seizure susceptibility appears to be the pSC-SNPr circuit. We also found that WARs presented an increase in the number of FG+ projections from the posterior SNPr to both the aSC and pSC (primarily to the pSC), with both acting as proconvulsant nuclei when compared with Wistar rats. We concluded that these two different subcortical loops within the basal ganglia are probably a consequence of the WAR

  2. Prenatal exposure to the CB1 and CB2 cannabinoid receptor agonist WIN 55,212-2 alters migration of early-born glutamatergic neurons and GABAergic interneurons in the rat cerebral cortex.

    PubMed

    Saez, Trinidad M M; Aronne, María P; Caltana, Laura; Brusco, Alicia H

    2014-05-01

    The endocannabinoid system, composed of cannabinoid receptors, endocannabinoids, and synthesis and degradation enzymes, is present since early stages of brain development. During this period, the endocannabinoid system is involved in the regulation of neural progenitor proliferation and specification as well as the migration and differentiation of pyramidal neurons and interneurons. Marijuana consumption during pregnancy represents a serious risk in relation to the fetal brain development since Δ(9) -tetrahidrocannabinol, the main active compound of cannabis, can reach the fetus through placenta and hemato-encephalic barrier. Cohort studies performed on children and adolescents of mothers who consumed marijuana during pregnancy reported cognitive and comportamental abnormalities. In the present study, we examined the expression of the cannabinoid receptor CB1 R during corticogenesis in radially and tangentially migrating post-mitotic neurons. We found that prenatal exposure to WIN impaired tangential and radial migration of post-mitotic neurons in the dorsal pallium. In addition, we described alterations of two transcription factors associated with proliferating and newly post-mitotic glutamatergic cells in the dorsal pallium, Tbr1 and Tbr2, and disruption in the number of Cajal-Retzius cells. The present results contribute to the knowledge of neurobiological substrates that determine neuro-comportamental changes that will persist through post-natal life.

  3. Structural and functional characterization of dendritic arbors and GABAergic synaptic inputs on interneurons and principal cells in the rat basolateral amygdala

    PubMed Central

    Klenowski, Paul M.; Fogarty, Matthew J.; Belmer, Arnauld; Noakes, Peter G.; Bellingham, Mark C.

    2015-01-01

    The basolateral amygdala (BLA) is a complex brain region associated with processing emotional states, such as fear, anxiety, and stress. Some aspects of these emotional states are driven by the network activity of synaptic connections, derived from both local circuitry and projections to the BLA from other regions. Although the synaptic physiology and general morphological characteristics are known for many individual cell types within the BLA, the combination of morphological, electrophysiological, and distribution of neurochemical GABAergic synapses in a three-dimensional neuronal arbor has not been reported for single neurons from this region. The aim of this study was to assess differences in morphological characteristics of BLA principal cells and interneurons, quantify the distribution of GABAergic neurochemical synapses within the entire neuronal arbor of each cell type, and determine whether GABAergic synaptic density correlates with electrophysiological recordings of inhibitory postsynaptic currents. We show that BLA principal neurons form complex dendritic arborizations, with proximal dendrites having fewer spines but higher densities of neurochemical GABAergic synapses compared with distal dendrites. Furthermore, we found that BLA interneurons exhibited reduced dendritic arbor lengths and spine densities but had significantly higher densities of putative GABAergic synapses compared with principal cells, which was correlated with an increased frequency of spontaneous inhibitory postsynaptic currents. The quantification of GABAergic connectivity, in combination with morphological and electrophysiological measurements of the BLA cell types, is the first step toward a greater understanding of how fear and stress lead to changes in morphology, local connectivity, and/or synaptic reorganization of the BLA. PMID:26041829

  4. Amino acid suppression of taurine-sensitive chemosensory neurons.

    PubMed

    Gleeson, R A; Ache, B W

    1985-05-27

    Single unit recordings from chemoreceptors on the antennule of the spiny lobster revealed a population of taurine-sensitive cells whose response is suppressed when taurine is presented in mixture with certain amino acids. A synthetic mixture of 21 amino acids plus betaine, which mimics the composition of a natural food stimulus (crab muscle tissue) and itself contains taurine, totally and reversibly blocked the taurine response of this group of receptor cells. An analysis of the contribution to this suppression by the six major components (based on concentration) in the mixture revealed partial or complete inhibitory activity by five of the compounds. In a sample group of the inhibited cells, mean percent suppression of the taurine response was 99% for glycine and L-arginine, 98% for L-glutamine, 60% for L-alanine and 43% for L-proline. Both glycine and alanine in binary mixture with taurine caused a right-shift in the concentration-response function for taurine, suggesting a competitive mechanism of suppression. pA2 values determined from these data yielded 4.17 for glycine and 3.55 for alanine. These results suggest that the processing of chemical information in quality and/or intensity coding of natural stimulus mixtures can be tempered by interactions of the components at the receptor-cell level, and possibly at the receptor-sites themselves.

  5. Glutamatergic axon-derived BDNF controls GABAergic synaptic differentiation in the cerebellum.

    PubMed

    Chen, Albert I; Zang, Keling; Masliah, Eliezer; Reichardt, Louis F

    2016-01-01

    To study mechanisms that regulate the construction of inhibitory circuits, we examined the role of brain-derived neurotrophic factor (BDNF) in the assembly of GABAergic inhibitory synapses in the mouse cerebellar cortex. We show that within the cerebellum, BDNF-expressing cells are restricted to the internal granular layer (IGL), but that the BDNF protein is present within mossy fibers which originate from cells located outside of the cerebellum. In contrast to deletion of TrkB, the cognate receptor for BDNF, deletion of Bdnf from cerebellar cell bodies alone did not perturb the localization of pre- or postsynaptic constituents at the GABAergic synapses formed by Golgi cell axons on granule cell dendrites within the IGL. Instead, we found that BDNF derived from excitatory mossy fiber endings controls their differentiation. Our findings thus indicate that cerebellar BDNF is derived primarily from excitatory neurons--precerebellar nuclei/spinal cord neurons that give rise to mossy fibers--and promotes GABAergic synapse formation as a result of release from axons. Thus, within the cerebellum the preferential localization of BDNF to axons enhances the specificity through which BDNF promotes GABAergic synaptic differentiation. PMID:26830657

  6. Apolipoprotein E4 produced in GABAergic interneurons causes learning and memory deficits in mice.

    PubMed

    Knoferle, Johanna; Yoon, Seo Yeon; Walker, David; Leung, Laura; Gillespie, Anna K; Tong, Leslie M; Bien-Ly, Nga; Huang, Yadong

    2014-10-15

    Apolipoprotein (apo) E4 is expressed in many types of brain cells, is associated with age-dependent decline of learning and memory in humans, and is the major genetic risk factor for AD. To determine whether the detrimental effects of apoE4 depend on its cellular sources, we generated human apoE knock-in mouse models in which the human APOE gene is conditionally deleted in astrocytes, neurons, or GABAergic interneurons. Here we report that deletion of apoE4 in astrocytes does not protect aged mice from apoE4-induced GABAergic interneuron loss and learning and memory deficits. In contrast, deletion of apoE4 in neurons does protect aged mice from both deficits. Furthermore, deletion of apoE4 in GABAergic interneurons is sufficient to gain similar protection. This study demonstrates a detrimental effect of endogenously produced apoE4 on GABAergic interneurons that leads to learning and memory deficits in mice and provides a novel target for drug development for AD related to apoE4.

  7. Trinitrobenzenesulphonic acid colitis alters Na 1.8 channel expression in mouse dorsal root ganglia neurons.

    PubMed

    King, D E; Macleod, R J; Vanner, S J

    2009-08-01

    Visceral inflammation evokes hyperexcitability in nociceptive dorsal root ganglia (DRG) neurons and these changes are associated with increased voltage-gated sodium channel (Na(v)) 1.8 current density, but the molecular determinants of these changes are unclear. This study used Western blotting to measure changes in Na(v) 1.7, 1.8 and 1.9 protein expression during trinitrobenzenesulphonic acid (TNBS) colitis and quantitative polymerase chain reaction (PCR) to examine corresponding changes in mRNA. Colonic neurons were labelled with the retrograde tracer Fast Blue injected into the wall of the distal colon and quantitative PCR performed on laser-captured labelled colonic neurons from ganglia at T9-13 or unlabelled DRG neurons from the upper spinal cord. Immunohistochemistry and western blots were performed on whole DRG from the same sites. Fast Blue-labelled neurons demonstrated Na(v) 1.7, 1.8 and 1.9 immunoreactivity. On day 7 of colitis, which correlated with electrophysiological studies, there was a threefold increase in Na(v) 1.8 protein in ganglia from T9 to 13, but Na(v) 1.7 and 1.9 levels were unchanged. There was no corresponding change in the Na(v) 1.8 alpha-subunit mRNA levels. However, on days 2 and 4, Na(v) 1.8 mRNA was decreased 10-fold. Na(v) 1.8 protein and mRNA levels were unchanged in neurons isolated from ganglia in the upper spinal cord, where colonic neurons are not found. These findings suggest that the TNBS evoked increase in Na(v) 1.8 currents is associated with increased numbers of channels. The absence of corresponding changes in transcript suggests a translational or post-translational mechanism, but the 10-fold recovery of transcript preceding this time point also demonstrates a complex transcriptional regulation. PMID:19239624

  8. Acid Sensing Ion Channels (ASICs) in NS20Y cells - potential role in neuronal differentiation.

    PubMed

    O'Bryant, Zaven; Leng, Tiandong; Liu, Mingli; Inoue, Koichi; Vann, Kiara T; Xiong, Zhi-Gang

    2016-01-01

    Cultured neuronal cell lines can express properties of mature neurons if properly differentiated. Although the precise mechanisms underlying neuronal differentiation are not fully understood, the expression and activation of ion channels, particularly those of Ca(2+)-permeable channels, have been suggested to play a role. In this study, we explored the presence and characterized the properties of acid-sensing ion channels (ASICs) in NS20Y cells, a neuronal cell line previously used for the study of neuronal differentiation. In addition, the potential role of ASICs in cell differentiation was explored. Reverse Transcription Polymerase Chain Reaction and Western blot revealed the presence of ASIC1 subunits in these cells. Fast drops of extracellular pH activated transient inward currents which were blocked, in a dose dependent manner, by amiloride, a non-selective ASIC blocker, and by Psalmotoxin-1 (PcTX1), a specific inhibitor for homomeric ASIC1a and heteromeric ASIC1a/2b channels. Incubation of cells with PcTX1 significantly reduced the differentiation of NS20Y cells induced by cpt-cAMP, as evidenced by decreased neurite length, dendritic complexity, decreased expression of functional voltage gated Na(+) channels. Consistent with ASIC1a inhibition, ASIC1a knockdown with small interference RNA significantly attenuates cpt-cAMP-induced increase of neurite outgrowth. In summary, we described the presence of functional ASICs in NS20Y cells and demonstrate that ASIC1a plays a role in the differentiation of these cells. PMID:27342076

  9. Reduced GABAergic Action in the Autistic Brain.

    PubMed

    Robertson, Caroline E; Ratai, Eva-Maria; Kanwisher, Nancy

    2016-01-11

    An imbalance between excitatory/inhibitory neurotransmission has been posited as a central characteristic of the neurobiology of autism [1], inspired in part by the striking prevalence of seizures among individuals with the disorder [2]. Evidence supporting this hypothesis has specifically implicated the signaling pathway of the inhibitory neurotransmitter, γ-aminobutyric acid (GABA), in this putative imbalance: GABA receptor genes have been associated with autism in linkage and copy number variation studies [3-7], fewer GABA receptor subunits have been observed in the post-mortem tissue of autistic individuals [8, 9], and GABAergic signaling is disrupted across heterogeneous mouse models of autism [10]. Yet, empirical evidence supporting this hypothesis in humans is lacking, leaving a gulf between animal and human studies of the condition. Here, we present a direct link between GABA signaling and autistic perceptual symptomatology. We first demonstrate a robust, replicated autistic deficit in binocular rivalry [11], a basic visual function that is thought to rely on the balance of excitation/inhibition in visual cortex [12-15]. Then, using magnetic resonance spectroscopy, we demonstrate a tight linkage between binocular rivalry dynamics in typical participants and both GABA and glutamate levels in the visual cortex. Finally, we show that the link between GABA and binocular rivalry dynamics is completely and specifically absent in autism. These results suggest a disruption in inhibitory signaling in the autistic brain and forge a translational path between animal and human models of the condition.

  10. Generation of glutamatergic neurons from postnatal and adult subventricular zone with pyramidal-like morphology.

    PubMed

    Sequerra, Eduardo B; Miyakoshi, Leo M; Fróes, Maira M; Menezes, João R L; Hedin-Pereira, Cecilia

    2010-11-01

    The mammalian subventricular zone (SVZ) contains progenitors derived from cerebral cortex radial glia cells, which give rise to glutamatergic pyramidal neurons during embryogenesis. However, during postnatal life, SVZ generates neurons that migrate and differentiate into olfactory bulb γ-aminobutyric acid (GABA)ergic interneurons. In this work, we tested if SVZ cells are able to produce glutamatergic neurons if confronted with the embryonic cortical ventricular zone environment. Different from typical SVZ chain migration, cells from P9-P11 SVZ explants migrate into embryonic cortical slices individually, many of which radially oriented. An average of 82.5% of green fluorescent protein-positive cells were immunolabeled for neuronal marker class III β-tubulin. Invading cells differentiate into multiple morphologies, including a pyramidal-like morphotype. A subset of these cells are GABAergic; however, about 28% of SVZ-derived cells are immunoreactive for glutamate. Adult SVZ explants also give rise to glutamatergic neurons in these conditions. Taken together, our results indicate that SVZ can be a source of glutamatergic cortical neurons when submitted to proper environmental cues.

  11. Cannabinoids Inhibit Acid-Sensing Ion Channel Currents in Rat Dorsal Root Ganglion Neurons

    PubMed Central

    Qiu, Chun-Yu; Cai, Qi; Zou, Pengcheng; Wu, Heming; Hu, Wang-Ping

    2012-01-01

    Local acidosis has been found in various pain-generating conditions such as inflammation and tissue injury. Cannabinoids exert a powerful inhibitory control over pain initiation via peripheral cognate receptors. However, the peripheral molecular targets responsible for the antinociceptive effects of cannabinoids are still poorly understood. Here, we have found that WIN55,212-2, a cannabinoid receptor agonist, inhibits the activity of native acid-sensing ion channels (ASICs) in rat dorsal root ganglion (DRG) neurons. WIN55,212-2 dose-dependently inhibited proton-gated currents mediated by ASICs. WIN55,212-2 shifted the proton concentration–response curve downwards, with an decrease of 48.6±3.7% in the maximum current response but with no significant change in the EC50 value. The inhibition of proton-gated current induced by WIN55,212-2 was almost completely blocked by the selective CB1 receptor antagonist AM 281, but not by the CB2 receptor antagonist AM630. Pretreatment of forskolin, an AC activator, and the addition of cAMP also reversed the inhibition of WIN55,212-2. Moreover, WIN55,212-2 altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. Finally, WIN55,212-2 attenuated nociceptive responses to injection of acetic acid in rats. These results suggest that WIN55,212-2 inhibits the activity of ASICs via CB1 receptor and cAMP dependent pathway in rat primary sensory neurons. Thus, cannabinoids can exert their analgesic action by interaction with ASICs in the primary afferent neurons, which was novel analgesic mechanism of cannabinoids. PMID:23029075

  12. The involvement of the GABAergic system in the formation and expression of the extinction memory in the crab Neohelice granulata.

    PubMed

    Tano, Martin Carbó; Molina, Victor A; Pedreira, Maria Eugenia

    2013-11-01

    There is growing interest in the neurobiological mechanisms involved in the extinction of aversive memory. This cognitive process usually occurs after repeated or prolonged presentation of a conditioned stimulus that was previously associated with an unconditioned stimulus. If extinction is considered to be a new memory, the role of the γ-aminobutyric acid system (GABAergic system) during extinction memory consolidation should be similar to that described for the original trace. It is also accepted that negative modulation of the GABAergic system before testing can impair extinction memory expression. However, it seems possible to speculate that inhibitory mechanisms may be required in order to acquire a memory that is inhibitory in nature. Using a combination of behavioral protocols, such as weak and robust extinction training procedures, and pharmacological treatments, such as the systemic administration of GABAA agonist (muscimol) and antagonist (bicuculline), we investigated the role of the GABAergic system in the different phases of the extinction memory in the crab Neohelice granulata. We show that the stimulation of the GABAergic system impairs and its inactivation facilitates the extinction memory consolidation. Moreover, fine variations in the GABAergic tone affect its expression at testing. Finally, an active GABAergic system is necessary for the acquisition of the extinction memory. This detailed description may contribute to the understanding of the role of the GABAergic system in diverse aspects of the extinction memory.

  13. Developmental changes in synaptic distribution in arcuate nucleus neurons.

    PubMed

    Baquero, Arian F; Kirigiti, Melissa A; Baquero, Karalee C; Lee, Shin J; Smith, M Susan; Grove, Kevin L

    2015-06-01

    Neurons coexpressing neuropeptide Y, agouti-related peptide, and GABA (NAG) play an important role in ingestive behavior and are located in the arcuate nucleus of the hypothalamus. NAG neurons receive both GABAergic and glutamatergic synaptic inputs, however, the developmental time course of synaptic input organization of NAG neurons in mice is unknown. In this study, we show that these neurons have low numbers of GABAergic synapses and that GABA is inhibitory to NAG neurons during early postnatal period. In contrast, glutamatergic inputs onto NAG neurons are relatively abundant by P13 and are comparatively similar to the levels observed in the adult. As mice reach adulthood (9-10 weeks), GABAergic tone onto NAG neurons increases. At this age, NAG neurons received similar numbers of inhibitory and EPSCs. To further differentiate age-associated changes in synaptic distribution, 17- to 18-week-old lean and diet-induced obesity (DIO) mice were studied. Surprisingly, NAG neurons from lean adult mice exhibit a reduction in the GABAergic synapses compared with younger adults. Conversely, DIO mice display reductions in the number of GABAergic and glutamatergic inputs onto NAG neurons. Based on these experiments, we propose that synaptic distribution in NAG neurons is continuously restructuring throughout development to accommodate the animals' energy requirements.

  14. Glutamate neurons within the midbrain dopamine regions.

    PubMed

    Morales, M; Root, D H

    2014-12-12

    Midbrain dopamine systems play important roles in Parkinson's disease, schizophrenia, addiction, and depression. The participation of midbrain dopamine systems in diverse clinical contexts suggests these systems are highly complex. Midbrain dopamine regions contain at least three neuronal phenotypes: dopaminergic, GABAergic, and glutamatergic. Here, we review the locations, subtypes, and functions of glutamatergic neurons within midbrain dopamine regions. Vesicular glutamate transporter 2 (VGluT2) mRNA-expressing neurons are observed within each midbrain dopamine system. Within rat retrorubral field (RRF), large populations of VGluT2 neurons are observed throughout its anteroposterior extent. Within rat substantia nigra pars compacta (SNC), VGluT2 neurons are observed centrally and caudally, and are most dense within the laterodorsal subdivision. RRF and SNC rat VGluT2 neurons lack tyrosine hydroxylase (TH), making them an entirely distinct population of neurons from dopaminergic neurons. The rat ventral tegmental area (VTA) contains the most heterogeneous populations of VGluT2 neurons. VGluT2 neurons are found in each VTA subnucleus but are most dense within the anterior midline subnuclei. Some subpopulations of rat VGluT2 neurons co-express TH or glutamic acid decarboxylase (GAD), but most of the VGluT2 neurons lack TH or GAD. Different subsets of rat VGluT2-TH neurons exist based on the presence or absence of vesicular monoamine transporter 2, dopamine transporter, or D2 dopamine receptor. Thus, the capacity by which VGluT2-TH neurons may release dopamine will differ based on their capacity to accumulate vesicular dopamine, uptake extracellular dopamine, or be autoregulated by dopamine. Rat VTA VGluT2 neurons exhibit intrinsic VTA projections and extrinsic projections to the accumbens and to the prefrontal cortex. Mouse VTA VGluT2 neurons project to accumbens shell, prefrontal cortex, ventral pallidum, amygdala, and lateral habenula. Given their molecular

  15. A proapoptotic effect of valproic acid on progenitors of embryonic stem cell-derived glutamatergic neurons

    PubMed Central

    Fujiki, R; Sato, A; Fujitani, M; Yamashita, T

    2013-01-01

    Valproic acid (VPA) is a branched-chain saturated fatty acid with a long history of clinical use as an antiepileptic drug (AED). VPA is also known to inhibit histone deacetylases (HDACs) and to cause diverse effects on neural progenitor cells (NPCs) and neurons. Although the neuroprotective or neurodestructive effects of VPA have been investigated in heterogeneous cell populations, in this study, we used homogeneous populations of NPCs and glutamatergic cortical pyramidal neurons, which were differentiated from embryonic stem (ES) cells. At therapeutic concentrations, VPA had a proapoptotic effect on ES cell-derived NPCs of glutamatergic neurons, but not on their progeny. This effect of VPA most likely occurred through the inhibition of HDACs, because similar phenotypes were observed following treatment with other HDAC inhibitors (HDACis) such as trichostatin A and sodium butyrate. The proapoptotic phenotype was not observed when cells were exposed to a structural analog of VPA, valpromide (VPM), which has the same antiepileptic effect as VPA, but does not inhibit HDACs. Western blotting confirmed that treatment with HDACis, but not VPM, significantly increased the levels of histone H3 acetylation in NPCs. HDACi treatments did not affect the survival of neurons, although the acetylation levels were increased to a limited extent. These results, which are based on a homogeneous culture system, suggest that VPA inhibits HDAC activity and induces the apoptosis of NPCs that are fated to differentiate into glutamatergic neurons. The dose-dependent effects of VPA both on apoptosis and hyperacetylation of histone H3 in NPCs supported this notion. These cell type- and differentiation stage-specific effects of VPA imply that dysfunction of HDACs during pregnancy significantly increase the risk of congenital malformations associated with VPA administration. PMID:23788034

  16. Neuroprotective effect of Arthrospira (Spirulina) platensis against kainic acid-neuronal death.

    PubMed

    Pérez-Juárez, Angélica; Chamorro, Germán; Alva-Sánchez, Claudia; Paniagua-Castro, Norma; Pacheco-Rosado, Jorge

    2016-08-01

    Context Arthrospira (Spirulina) platensis (SP) is a cyanobacterium which has attracted attention because of its nutritional value and pharmacological properties. It was previously reported that SP reduces oxidative stress in the hippocampus and protects against damaging neurobehavioural effects of systemic kainic acid (KA). It is widely known that the systemic administration of KA induces neuronal damage, specifically in the CA3 hippocampal region. Objective The present study determines if the SP sub-chronic treatment has neuroprotective properties against KA. Materials and methods Male SW mice were treated with SP during 24 d, at doses of 0, 200, and 800 mg/kg, once daily, and with KA (35 mg/kg, ip) as a single dose on day 14. After the treatment, a histological analysis was performed and the number of atrophic neuronal cells in CA3 hippocampal region was quantified. Results Pretreatment with SP does not protect against seizures induced by KA. However, mortality in the SP 200 and the SP 800 groups was of 20%, while for the KA group, it was of 60%. A single KA ip administration produced a considerable neuronal damage, whereas both doses of SP sub-chronic treatment reduced the number of atrophic neurons in CA3 hippocampal region with respect to the KA group. Discussion The SP neurobehaviour improvement after KA systemic administration correlates with the capacity of SP to reduce KA-neuronal death in CA3 hippocampal cells. This neuroprotection may be related to the antioxidant properties of SP. Conclusion SP reduces KA-neuronal death in CA3 hippocampal cells. PMID:26799655

  17. ON and OFF retinal ganglion cells differentially regulate serotonergic and GABAergic activity in the dorsal raphe nucleus

    PubMed Central

    Zhang, Ting; Huang, Lu; Zhang, Li; Tan, Minjie; Pu, Mingliang; Pickard, Gary E.; So, Kwok-Fai; Ren, Chaoran

    2016-01-01

    The dorsal raphe nucleus (DRN), the major source of serotonergic input to the forebrain, receives excitatory input from the retina that can modulate serotonin levels and depressive-like behavior. In the Mongolian gerbil, retinal ganglion cells (RGCs) with alpha-like morphological and Y-like physiological properties innervate the DRN with ON DRN-projecting RGCs out numbering OFF DRN-projecting RGCs. The DRN neurons targeted by ON and OFF RGCs are unknown. To explore retino-raphe anatomical organization, retinal afferents labeled with Cholera toxin B were examined for association with the postsynaptic protein PSD-95. Synaptic associations between retinal afferents and DRN serotonergic and GABAergic neurons were observed. To explore retino-raphe functional organization, light-evoked c-fos expression was examined. Light significantly increased the number of DRN serotonergic and GABAergic cells expressing c-Fos. When ON RGCs were rendered silent while enhancing the firing rate of OFF RGCs, c-Fos expression was greatly increased in DRN serotonergic neurons suggesting that OFF DRN-projecting RGCs predominately activate serotonergic neurons whereas ON DRN-projecting RGCs mainly target GABAergic neurons. Direct glutamatergic retinal input to DRN 5-HT neurons contributes to the complex excitatory drive regulating these cells. Light, via the retinoraphe pathway can modify DRN 5-HT neuron activity which may play a role in modulating affective behavior. PMID:27181078

  18. Neonatal tissue injury reduces the intrinsic excitability of adult mouse superficial dorsal horn neurons.

    PubMed

    Li, J; Baccei, M L

    2014-01-01

    Tissue damage during the neonatal period evokes long-lasting changes in nociceptive processing within the adult spinal cord which contribute to persistent alterations in pain sensitivity. However, it remains unclear if the observed modifications in neuronal activity within the mature superficial dorsal horn (SDH) following early injury reflect shifts in the intrinsic membrane properties of these cells. Therefore, the present study was undertaken to identify the effects of neonatal surgical injury on the intrinsic excitability of both GABAergic and presumed glutamatergic neurons within lamina II of the adult SDH using in vitro patch clamp recordings from spinal cord slices prepared from glutamic acid decarboxylase-green fluorescent protein (Gad-GFP) mice. The results demonstrate that hindpaw surgical incision at postnatal day (P) 3 altered the passive membrane properties of both Gad-GFP and adjacent, non-GFP neurons in the mature SDH, as evidenced by decreased membrane resistance and more negative resting potentials in comparison to naïve littermate controls. This was accompanied by a reduction in the prevalence of spontaneous activity within the GABAergic population. Both Gad-GFP and non-GFP neurons displayed a significant elevation in rheobase and decreased instantaneous firing frequency after incision, suggesting that early tissue damage lowers the intrinsic membrane excitability of adult SDH neurons. Isolation of inward-rectifying K(+) (K(ir)) currents revealed that neonatal incision significantly increased K(ir) conductance near physiological membrane potentials in GABAergic, but not glutamatergic, lamina II neurons. Overall, these findings suggest that neonatal tissue injury causes a long-term dampening of intrinsic firing across the general population of lamina II interneurons, but the underlying ionic mechanisms may be cell-type specific.

  19. GABAergic signalling in a neurogenic niche of the turtle spinal cord

    PubMed Central

    Reali, Cecilia; Fernández, Anabel; Radmilovich, Milka; Trujillo-Cenóz, Omar; Russo, Raúl E

    2011-01-01

    Abstract The region that surrounds the central canal (CC) in the turtle spinal cord is a neurogenic niche immersed within already functional circuits, where radial glia expressing brain lipid binding protein (BLBP) behave as progenitors. The behaviour of both progenitors and neuroblasts within adult neurogenic niches must be regulated to maintain the functional stability of the host circuit. In the brain, GABA plays a major role in this kind of regulation but little is known about GABAergic signalling in neurogenic niches of the postnatal spinal cord. Here we explored the action of GABA around the CC of the turtle spinal cord by combining patch-clamp recordings of CC-contacting cells, immunohistochemistry for key components of GABAergic signalling and Ca2+ imaging. Two potential sources of GABA appeared around the CC: GABAergic terminals and CC-contacting neurones. GABA depolarized BLBP+ progenitors via GABA transporter-3 (GAT3) and/or GABAA receptors. In CC-contacting neurones, GABAA receptor activation generated responses ranging from excitation to inhibition. This functional heterogeneity appeared to originate from different ratios of activity of the Na+–K+–2Cl− co-transporter (NKCC1) and the K+–Cl− co-transporter (KCC2). In both progenitors and immature neurones, GABA induced an increase in intracellular Ca2+ that required extracellular Ca2+ and was blocked by the selective GABAA receptor antagonist gabazine. Our study shows that GABAergic signalling around the CC shares fundamental properties with those in the embryo and adult neurogenic niches, suggesting that GABA may be part of the mechanisms regulating the production and integration of neurones within operational spinal circuits in the turtle. PMID:21911613

  20. The role of GABAergic inhibition in processing of interaural time difference in the owl's auditory system.

    PubMed

    Fujita, I; Konishi, M

    1991-03-01

    The barn owl uses interaural time differences (ITDs) to localize the azimuthal position of sound. ITDs are processed by an anatomically distinct pathway in the brainstem. Neuronal selectivity for ITD is generated in the nucleus laminaris (NL) and conveyed to both the anterior portion of the ventral nucleus of the lateral lemniscus (VLVa) and the central (ICc) and external (ICx) nuclei of the inferior colliculus. With tonal stimuli, neurons in all regions are found to respond maximally not only to the real ITD, but also to ITDs that differ by integer multiples of the tonal period. This phenomenon, phase ambiguity, does not occur when ICx neurons are stimulated with noise. The main aim of this study was to determine the role of GABAergic inhibition in the processing of ITDs. Selectivity for ITD is similar in the NL and VLVa and improves in the ICc and ICx. Iontophoresis of bicuculline methiodide (BMI), a selective GABAA antagonist, decreased the ITD selectivity of ICc and ICx neurons, but did not affect that of VLVa neurons. Responses of VLVa and ICc neurons to unfavorable ITDs were below the monaural response levels. BMI raised both binaural responses to unfavorable ITDs and monaural responses, though the former remained smaller than the latter. During BMI application, ICx neurons showed phase ambiguity to noise stimuli and no longer responded to a unique ITD. BMI increased the response magnitude and changed the temporal discharge patterns in the VLVa, ICc, and ICx. Iontophoretically applied GABA exerted effects opposite to those of BMI, and the effects could be antagonized with simultaneous application of BMI. These results suggest that GABAergic inhibition (1) sharpens ITD selectivity in the ICc and ICx, (2) contributes to the elimination of phase ambiguity in the ICx, and (3) controls response magnitude and temporal characteristics in the VLVa, ICc, and ICx. Through these actions, GABAergic inhibition shapes the horizontal dimension of the auditory receptive

  1. Neuregulin 1 promotes excitatory synapse development and function in GABAergic interneurons.

    PubMed

    Ting, Annie K; Chen, Yongjun; Wen, Lei; Yin, Dong-Min; Shen, Chengyong; Tao, Yanmei; Liu, Xihui; Xiong, Wen-Cheng; Mei, Lin

    2011-01-01

    Neuregulin 1 (NRG1) and its receptor ErbB4 are both susceptibility genes of schizophrenia. However, little is known about the underlying mechanisms of their malfunction. Although ErbB4 is enriched in GABAergic interneurons, the role of NRG1 in excitatory synapse formation in these neurons remains poorly understood. We showed that NRG1 increased both the number and size of PSD-95 puncta and the frequency and amplitude of miniature EPSCs (mEPSCs) in GABAergic interneurons, indicating that NRG1 stimulates the formation of new synapses and strengthens existing synapses. In contrast, NRG1 treatment had no effect on either the number or size of excitatory synapses in glutamatergic neurons, suggesting its synaptogenic effect is specific to GABAergic interneurons. Ecto-ErbB4 treatment diminished both the number and size of excitatory synapses, suggesting that endogenous NRG1 may be critical for basal synapse formation. NRG1 could stimulate the stability of PSD-95 in the manner that requires tyrosine kinase activity of ErbB4. Finally, deletion of ErbB4 in parvalbumin-positive interneurons led to reduced frequency and amplitude of mEPSCs, providing in vivo evidence that ErbB4 is important in excitatory synaptogenesis in interneurons. Together, our findings suggested a novel synaptogenic role of NRG1 in excitatory synapse development, possibly via stabilizing PSD-95, and this effect is specific to GABAergic interneurons. In light of the association of the genes of both NRG1 and ErbB4 with schizophrenia and dysfunction of GABAergic system in this disorder, these results provide insight into its potential pathological mechanism.

  2. Co-localization of Gamma-Aminobutyric Acid and Glutamate in Neurons of the Spider Central Nervous System.

    PubMed

    Fabian-Fine, Ruth; Meisner, Shannon; Torkkeli, Päivi H; Meinertzhagen, Ian A

    2015-12-01

    Spider sensory neurons with cell bodies close to various sensory organs are innervated by putative efferent axons from the central nervous system (CNS). Light and electronmicroscopic imaging of immunolabeled neurons has demonstrated that neurotransmitters present at peripheral synapses include γ-aminobutyric acid (GABA), glutamate and octopamine. Moreover, electrophysiological studies show that these neurotransmitters modulate the sensitivity of peripheral sensory neurons. Here, we undertook immunocytochemical investigations to characterize GABA and glutamate-immunoreactive neurons in three-dimensional reconstructions of the spider CNS. We document that both neurotransmitters are abundant in morphologically distinct neurons throughout the CNS. Labeling for the vesicular transporters, VGAT for GABA and VGLUT for glutamate, showed corresponding patterns, supporting the specificity of antibody binding. Whereas some neurons displayed strong immunolabeling, others were only weakly labeled. Double labeling showed that a subpopulation of weakly labeled neurons present in all ganglia expresses both GABA and glutamate. Double labeled, strongly and weakly labeled GABA and glutamate immunoreactive axons were also observed in the periphery along muscle fibers and peripheral sensory neurons. Electron microscopic investigations showed presynaptic profiles of various diameters with mixed vesicle populations innervating muscle tissue as well as sensory neurons. Our findings provide evidence that: (1) sensory neurons and muscle fibers are innervated by morphologically distinct, centrally located GABA- and glutamate immunoreactive neurons; (2) a subpopulation of these neurons may co-release both neurotransmitters; and (3) sensory neurons and muscles are innervated by all of these neurochemically and morphologically distinct types of neurons. The biochemical diversity of presynaptic innervation may contribute to how spiders filter natural stimuli and coordinate appropriate response

  3. Clavulanic acid increases dopamine release in neuronal cells through a mechanism involving enhanced vesicle trafficking.

    PubMed

    Kost, Gina Chun; Selvaraj, Senthil; Lee, Young Bok; Kim, Deog Joong; Ahn, Chang-Ho; Singh, Brij B

    2011-10-24

    Clavulanic acid is a CNS-modulating compound with exceptional blood-brain barrier permeability and safety profile. Clavulanic acid has been proposed to have anti-depressant activity and is currently entering Phase IIb clinical trials for the treatment of Major Depressive Disorder (MDD). Studies have also shown that clavulanic acid suppresses anxiety and enhances sexual functions in rodent and primate models by a mechanism involving central nervous system (CNS) modulation, although its detailed mechanism of action has yet to be elucidated. To further examine its potential as a CNS modulating agent as well as its mechanism of action, we investigated the effects of clavulanic acid in neuronal cells. Our results indicate that clavulanic acid enhances dopamine release in PC12 and SH-SY5Y cells without affecting dopamine synthesis. Furthermore, using affinity chromatography we were able to identify two proteins, Munc18-1 and Rab4 that potentially bind to clavulanic acid and play a critical role in neurosecretion and the vesicle trafficking process. Consistent with this result, an increase in the translocation of Munc18-1 and Rab4 from the cytoplasm to the plasma membrane was observed in clavulanic acid treated cells. Overall, these data suggest that clavulanic acid enhances dopamine release in a mechanism involving Munc18-1 and Rab4 modulation and warrants further investigation of its therapeutic use in CNS disorders, such as depression.

  4. Clavulanic acid increases dopamine release in neuronal cells through a mechanism involving enhanced vesicle trafficking

    PubMed Central

    Kost, Gina Chun; Selvaraj, Senthil; Lee, Young Bok; Kim, Deog Joong; Ahn, Chang-Ho; Singh, Brij B

    2011-01-01

    Clavulanic acid is a CNS-modulating compound with exceptional blood-brain barrier permeability and safety profile. Clavulanic acid has been proposed to have anti-depressant activity and is currently entering Phase IIb clinical trials for the treatment of Major Depressive Disorder (MDD). Studies have also shown that clavulanic acid suppresses anxiety and enhances sexual functions in rodent and primate models by a mechanism involving central nervous system (CNS) modulation, although its detailed mechanism of action has yet to be elucidated. To further examine its potential as a CNS modulating agent as well as its mechanism of action, we investigated the effects of clavulanic acid in neuronal cells. Our results indicate that clavulanic acid enhances dopamine release in PC12 and SH-SY5Y cells without affecting dopamine synthesis. Furthermore, using affinity chromatography we were able to identify two proteins, Munc18-1 and Rab4 that potentially bind to clavulanic acid and play a critical role in neurosecretion and the vesicle trafficking process. Consistent with this result, an increase in the translocation of Munc18-1 and Rab4 from the cytoplasm to the plasma membrane was observed in clavulanic acid treated cells. Overall, these data suggest that clavulanic acid enhances dopamine release in a mechanism involving Munc18-1 and Rab4 modulation and warrants further investigation of its therapeutic use in CNS disorders, such as depression. PMID:21964384

  5. Flotillin-1 promotes formation of glutamatergic synapses in hippocampal neurons.

    PubMed

    Swanwick, Catherine Croft; Shapiro, Marietta E; Vicini, Stefano; Wenthold, Robert J

    2010-11-01

    Synapse malformation underlies numerous neurodevelopmental illnesses, including autism spectrum disorders. Here we identify the lipid raft protein flotillin-1 as a promoter of glutamatergic synapse formation. We cultured neurons from the hippocampus, a brain region important for learning and memory, and examined them at two weeks in vitro, a time period rich with synapse formation. Double-label immunocytochemistry of native flot-1 with glutamatergic and GABAergic synapse markers showed that flot-1 was preferentially colocalized with the glutamatergic presynaptic marker vesicular glutamate transporter 1 (VGLUT1), compared to the GABAergic presynaptic marker glutamic acid decarboxylase-65 (GAD-65). Triple-label immunocytochemistry of native flot-1, VGLUT1, and NR1, the obligatory subunit of NMDA receptors, indicates that Flot-1 was preferentially localized to synaptic rather than extrasynaptic NR1. Furthermore, electrophysiological results using whole-cell patch clamp showed that Flot-1 increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) but not miniature inhibitory postsynaptic currents (mIPSCs), whereas amplitude and decay kinetics of either type of synaptic current was not affected. Corresponding immunocytochemical data confirmed that the number of glutamatergic synapses increased with flot-1 overexpression. Overall, our anatomical and physiological results show that flot-1 enhances the formation of glutamatergic synapses but not GABAergic synapses, suggesting that the role of flot-1 in neurodevelopmental disorders should be explored. PMID:20669324

  6. Phase dependent sign changes of GABAergic synaptic input explored in-silicio and in-vitro.

    PubMed

    Stiefel, Klaus M; Wespatat, Valérie; Gutkin, Boris; Tennigkeit, Frank; Singer, Wolf

    2005-08-01

    Inhibitory interactions play a crucial role in the synchronization of neuronal activity. Here we investigate the effect of GABAergic PSPs on spike timing in cortical neurons that exhibit an oscillatory modulation of their membrane potential. To this end we combined numerical simulations with in-vitro patch-clamp recordings from layer II/III pyramidal cells of the rat visual cortex. Special emphasis was placed on exploring how the reversal potential of the GABAergic synaptic currents (EGABA) and the phase relations of the PSPs relative to the oscillation cycles affect the timing of spikes riding on the depolarizing peaks of the oscillations. The simulations predicted: (1) With EGABA more negative than the oscillation minima PSPs are hyperpolarizing at all phases and thus delay or prevent spikes. (2) With EGABA being more positive than the oscillation maxima PSPs are depolarizing in a phase-independent way and lead to a phase advance of spikes. (3) In the intermediate case where EGABA lies within oscillation maxima and minima PSPs are either hyper- or depolarizing depending on their phase relations to the V(m) oscillations and can therefore either delay or advance spikes. Experiments conducted in this most interesting last configuration with biphasic PSPs agreed with the model predictions. Additional theoretical investigations revealed the effect of these PSP induced shifts in spike timing on synchronization in neuronal circuits. The results suggest that GABAergic mechanisms can assume highly specific timing functions in oscillatory networks.

  7. 17 beta-estradiol modulates GABAergic synaptic transmission and tonic currents during development in vitro.

    PubMed

    Pytel, Maria; Wójtowicz, Tomasz; Mercik, Katarzyna; Sarto-Jackson, Isabella; Sieghart, Werner; Ikonomidou, Chrysanthy; Mozrzymas, Jerzy W

    2007-05-01

    Estrogens exert a variety of modulatory effects on the structure and function of the nervous system. In particular, 17 beta-estradiol was found to affect GABAergic inhibition in adult animals but its action on GABAergic currents during development has not been elucidated. In the present study, we investigated the effect of 17 beta-estradiol on hippocampal neurons developing in vitro. In this model, mIPSC kinetics showed acceleration with age along with increased alpha1 subunit expression, similarly as in vivo. Long-term treatment with 17 beta-estradiol increased mIPSC amplitudes in neurons cultured for 6-8 and 9-11DIV and prolonged the mIPSC decaying phase only in the 9-11DIV group. The time needed for the onset of 17 beta-estradiol effect on mIPSC amplitude was approximately 48 h. In the period of 9-11DIV, treatment with 17 beta-estradiol strongly reduced the tonic conductance activated by low GABA concentrations. The effects of 17 beta-estradiol on mIPSCs and tonic conductance were not correlated with any change in expression of considered GABAAR subunits (alpha1-3, alpha5-6, gamma2) while alpha4 and delta subunits were at the detection limit. In conclusion, we provide evidence that 17 beta-estradiol differentially affects the phasic and tonic components of GABAergic currents in neurons developing in vitro.

  8. GABAergic and glycinergic inhibition modulate monaural auditory response properties in the avian superior olivary nucleus.

    PubMed

    Coleman, W L; Fischl, M J; Weimann, S R; Burger, R M

    2011-05-01

    The superior olivary nucleus (SON) is the primary source of inhibition in the avian auditory brainstem. While much is known about the role of inhibition at the SON's target nuclei, little is known about how the SON itself processes auditory information or how inhibition modulates these properties. Additionally, the synaptic physiology of inhibitory inputs within the SON has not been described. We investigated these questions using in vivo and in vitro electrophysiological techniques in combination with immunohistochemistry in the chicken, an organism for which the auditory brainstem has otherwise been well characterized. We provide a thorough characterization of monaural response properties in the SON and the influence of inhibitory input in shaping these features. We found that the SON contains a heterogeneous mixture of response patterns to acoustic stimulation and that in most neurons these responses are modulated by both GABAergic and glycinergic inhibitory inputs. Interestingly, many SON neurons tuned to low frequencies have robust phase-locking capability and the precision of this phase locking is enhanced by inhibitory inputs. On the synaptic level, we found that evoked and spontaneous inhibitory postsynaptic currents (IPSCs) within the SON are also mediated by both GABAergic and glycinergic inhibition in all neurons tested. Analysis of spontaneous IPSCs suggests that most SON cells receive a mixture of both purely GABAergic terminals, as well as terminals from which GABA and glycine are coreleased. Evidence for glycinergic signaling within the SON is a novel result that has important implications for understanding inhibitory function in the auditory brainstem.

  9. A direct GABAergic output from the basal ganglia to frontal cortex

    PubMed Central

    Saunders, Arpiar; Oldenburg, Ian A.; Berezovskii, Vladimir K.; Johnson, Caroline A.; Kingery, Nathan D.; Elliott, Hunter L.; Xie, Tiao; Gerfen, Charles R.; Sabatini, Bernardo L.

    2014-01-01

    The basal ganglia (BG) are phylogenetically conserved subcortical nuclei necessary for coordinated motor action and reward learning1. Current models postulate that the BG modulate cerebral cortex indirectly via an inhibitory output to thalamus, bidirectionally controlled by the BG via direct (dSPNs) and indirect (iSPNs) pathway striatal projection neurons2–4. The BG thalamic output sculpts cortical activity by interacting with signals from sensory and motor systems5. Here we describe a direct projection from the globus pallidus externus (GP), a central nucleus of the BG, to frontal regions of the cerebral cortex (FC). Two cell types make up the GP-FC projection, distinguished by their electrophysiological properties, cortical projections and expression of choline acetyltransferase (ChAT), a synthetic enzyme for the neurotransmitter acetylcholine (ACh). Despite these differences, ChAT+ cells, which have been historically identified as an extension of the nucleus basalis (NB), as well as ChAT− cells, release the inhibitory neurotransmitter GABA (γ-aminobutyric acid) and are inhibited by iSPNs and dSPNs of dorsal striatum. Thus GP-FC cells comprise a direct GABAergic/cholinergic projection under the control of striatum that activates frontal cortex in vivo. Furthermore, iSPN inhibition of GP-FC cells is sensitive to dopamine 2 receptor signaling, revealing a pathway by which drugs that target dopamine receptors for the treatment of neuropsychiatric disorders can act in the BG to modulate frontal cortices. PMID:25739505

  10. Exposure of C. elegans eggs to a glyphosate-containing herbicide leads to abnormal neuronal morphology.

    PubMed

    McVey, Kenneth A; Snapp, Isaac B; Johnson, Megan B; Negga, Rekek; Pressley, Aireal S; Fitsanakis, Vanessa A

    2016-01-01

    Recent data demonstrate that chronic exposure of Caenorhabditis elegans (C. elegans) to a high-use glyphosate-containing herbicide, Touchdown (TD), potentially damages the adult nervous system. It is unknown, however, whether unhatched worms exposed to TD during the egg stage show abnormal neurodevelopment post-hatching. Therefore, we investigated whether early treatment with TD leads to aberrant neuronal or neurite development in C. elegans. Studies were completed in three different worm strains with green fluorescent protein (GFP)-tagged neurons to facilitate visual neuronal assessment. Initially, eggs from C. elegans with all neurons tagged with GFP were chronically exposed to TD. Visual inspection suggested decreased neurite projections associated with ventral nerve cord neurons. Data analysis showed a statistically significant decrease in overall green pixel numbers at the fourth larval (L4) stage (*p<0.05). We further investigated whether specific neuronal populations were preferentially vulnerable to TD by treating eggs from worms that had all dopaminergic (DAergic) or γ-aminobutyric acid (GABAergic) neurons tagged with GFP. As before, green pixel number associated with these discrete neuronal populations was analyzed at multiple larval stages. Data analysis indicated statistically significant decreases in pixel number associated with DAergic, but not GABAergic, neurons (***p<0.001) at all larval stages. Finally, statistically significant decreases (at the first larval stage, L1) or increases (at the fourth larval stage, L4) in superoxide levels, a developmental signaling molecule, were detected (*p<0.05). These data suggest that early exposure to TD may impair neuronal development, perhaps through superoxide perturbation. Since toxic insults during development may late render individuals more vulnerable to neurodegenerative diseases in adulthood, these studies provide some of the first evidence in this model organism that early exposure to TD may adversely

  11. Exposure of C. elegans eggs to a glyphosate-containing herbicide leads to abnormal neuronal morphology.

    PubMed

    McVey, Kenneth A; Snapp, Isaac B; Johnson, Megan B; Negga, Rekek; Pressley, Aireal S; Fitsanakis, Vanessa A

    2016-01-01

    Recent data demonstrate that chronic exposure of Caenorhabditis elegans (C. elegans) to a high-use glyphosate-containing herbicide, Touchdown (TD), potentially damages the adult nervous system. It is unknown, however, whether unhatched worms exposed to TD during the egg stage show abnormal neurodevelopment post-hatching. Therefore, we investigated whether early treatment with TD leads to aberrant neuronal or neurite development in C. elegans. Studies were completed in three different worm strains with green fluorescent protein (GFP)-tagged neurons to facilitate visual neuronal assessment. Initially, eggs from C. elegans with all neurons tagged with GFP were chronically exposed to TD. Visual inspection suggested decreased neurite projections associated with ventral nerve cord neurons. Data analysis showed a statistically significant decrease in overall green pixel numbers at the fourth larval (L4) stage (*p<0.05). We further investigated whether specific neuronal populations were preferentially vulnerable to TD by treating eggs from worms that had all dopaminergic (DAergic) or γ-aminobutyric acid (GABAergic) neurons tagged with GFP. As before, green pixel number associated with these discrete neuronal populations was analyzed at multiple larval stages. Data analysis indicated statistically significant decreases in pixel number associated with DAergic, but not GABAergic, neurons (***p<0.001) at all larval stages. Finally, statistically significant decreases (at the first larval stage, L1) or increases (at the fourth larval stage, L4) in superoxide levels, a developmental signaling molecule, were detected (*p<0.05). These data suggest that early exposure to TD may impair neuronal development, perhaps through superoxide perturbation. Since toxic insults during development may late render individuals more vulnerable to neurodegenerative diseases in adulthood, these studies provide some of the first evidence in this model organism that early exposure to TD may adversely

  12. Bile Acid Inhibition of N-type Calcium Channel Currents from Sympathetic Ganglion Neurons.

    PubMed

    Lee, Hye Kyung; Lee, Kyoung Hwa; Cho, Eui-Sic

    2012-02-01

    Under some pathological conditions as bile flow obstruction or liver diseases with the enterohepatic circulation being disrupted, regurgitation of bile acids into the systemic circulation occurs and the plasma level of bile acids increases. Bile acids in circulation may affect the nervous system. We examined this possibility by studying the effects of bile acids on gating of neuronal (N)-type Ca(2+) channel that is essential for neurotransmitter release at synapses of the peripheral and central nervous system. N-type Ca(2+) channel currents were recorded from bullfrog sympathetic neuron under a cell-attached mode using 100 mM Ba(2+) as a charge carrier. Cholic acid (CA, 10(-6) M) that is relatively hydrophilic thus less cytotoxic was included in the pipette solution. CA suppressed the open probability of N-type Ca(2+) channel, which appeared to be due to an increase in null (no activity) sweeps. For example, the proportion of null sweep in the presence of CA was ~40% at +40 mV as compared with ~8% in the control recorded without CA. Other single channel properties including slope conductance, single channel current amplitude, open and shut times were not significantly affected by CA being present. The results suggest that CA could modulate N-type Ca(2+) channel gating at a concentration as low as 10(-6) M. Bile acids have been shown to activate nonselective cation conductance and depolarize the cell membrane. Under pathological conditions with increased circulating bile acids, CA suppression of N-type Ca(2+) channel function may be beneficial against overexcitation of the synapses.

  13. Neuronal networks and energy bursts in epilepsy.

    PubMed

    Wu, Y; Liu, D; Song, Z

    2015-02-26

    Epilepsy can be defined as the abnormal activities of neurons. The occurrence, propagation and termination of epileptic seizures rely on the networks of neuronal cells that are connected through both synaptic- and non-synaptic interactions. These complicated interactions contain the modified functions of normal neurons and glias as well as the mediation of excitatory and inhibitory mechanisms with feedback homeostasis. Numerous spread patterns are detected in disparate networks of ictal activities. The cortical-thalamic-cortical loop is present during a general spike wave seizure. The thalamic reticular nucleus (nRT) is the major inhibitory input traversing the region, and the dentate gyrus (DG) controls CA3 excitability. The imbalance between γ-aminobutyric acid (GABA)-ergic inhibition and glutamatergic excitation is the main disorder in epilepsy. Adjustable negative feedback that mediates both inhibitory and excitatory components affects neuronal networks through neurotransmission fluctuation, receptor and transmitter signaling, and through concomitant influences on ion concentrations and field effects. Within a limited dynamic range, neurons slowly adapt to input levels and have a high sensitivity to synaptic changes. The stability of the adapting network depends on the ratio of the adaptation rates of both the excitatory and inhibitory populations. Thus, therapeutic strategies with multiple effects on seizures are required for the treatment of epilepsy, and the therapeutic functions on networks are reviewed here. Based on the high-energy burst theory of epileptic activity, we propose a potential antiepileptic therapeutic strategy to transfer the high energy and extra electricity out of the foci.

  14. Neurons and glia in cat superior colliculus accumulate [3H]gamma-aminobutyric acid (GABA).

    PubMed

    Mize, R R; Spencer, R F; Sterling, P

    1981-11-01

    We have examined by autoradiography the labeling pattern in the cat superior colliculus following injection of tritiated gamma-aminobutyric acid (GABA). Silver grains were heavily distributed within the zonal layer and the upper 200 micrometer of the superficial gray. Fewer grains were observed deeper within the superficial gray, and still fewer were found within the optic and intermediate gray layers. The accumulation of label was restricted to certain classes of neuron and glia. Densely labeled neurons were small (8-12 micrometer in diameter) and located primarily within the upper 200 micrometer. Dark oligodendrocytes and astrocytes showed a moderate accumulation of label while pale oligodendrocytes and microglia were unlabeled. Label was also selectively accumulated over several other types of profile within the neuropil, including presynaptic dendrites, axons, and axon terminals.

  15. Vertical organization of gamma-aminobutyric acid-accumulating intrinsic neuronal systems in monkey cerebral cortex

    SciTech Connect

    DeFelipe, J.; Jones, E.G.

    1985-12-01

    Light and electron microscopic methods were used to examine the neurons in the monkey cerebral cortex labeled autoradiographically following the uptake and transport of (/sup 3/H)-gamma-aminobutyric acid (GABA). Nonpyramidal cell somata in the sensory-motor areas and primary visual area (area 17) were labeled close to the injection site and at distances of 1 to 1.5 mm beyond the injection site, indicating labeling by retrograde axoplasmic transport. This labeling occurred preferentially in the vertical dimension of the cortex. Prior injections of colchicine, an inhibitor of axoplasmic transport, abolished all labeling of somata except those within the injection site. In each area, injections of superficial layers (I to III) produced labeling of clusters of cell somata in layer V, and injections of the deep layers (V and VI) produced labeling of clusters of cell somata in layers II and III. In area 17, injections of the superficial layers produced dense retrograde cell labeling in three bands: in layers IVC, VA, and VI. Vertically oriented chains of silver grains linked the injection sites with the resulting labeled cell clusters. In all areas, the labeling of cells in the horizontal dimension was insignificant. Electron microscopic examination of labeled neurons confirms that the neurons labeled at a distance from an injection site are nonpyramidal neurons, many with somata so small that they would be mistaken for neuroglial cells light microscopically. They receive few axosomatic synapses, most of which have symmetric membrane thickenings. The vertical chains of silver grains overlie neuronal processes identifiable as both dendrites and myelinated axons, but unmyelinated axons may also be included. The clusters of (/sup 3/H)GABA-labeled cells are joined to one another and to adjacent unlabeled cells by junctional complexes, including puncta adherentia and multi-lamellar cisternal complexes.

  16. Co-activation of VTA DA and GABA neurons mediates nicotine reinforcement.

    PubMed

    Tolu, S; Eddine, R; Marti, F; David, V; Graupner, M; Pons, S; Baudonnat, M; Husson, M; Besson, M; Reperant, C; Zemdegs, J; Pagès, C; Hay, Y A H; Lambolez, B; Caboche, J; Gutkin, B; Gardier, A M; Changeux, J-P; Faure, P; Maskos, U

    2013-03-01

    Smoking is the most important preventable cause of mortality and morbidity worldwide. This nicotine addiction is mediated through the nicotinic acetylcholine receptor (nAChR), expressed on most neurons, and also many other organs in the body. Even within the ventral tegmental area (VTA), the key brain area responsible for the reinforcing properties of all drugs of abuse, nicotine acts on several different cell types and afferents. Identifying the precise action of nicotine on this microcircuit, in vivo, is important to understand reinforcement, and finally to develop efficient smoking cessation treatments. We used a novel lentiviral system to re-express exclusively high-affinity nAChRs on either dopaminergic (DAergic) or γ-aminobutyric acid-releasing (GABAergic) neurons, or both, in the VTA. Using in vivo electrophysiology, we show that, contrary to widely accepted models, the activation of GABA neurons in the VTA plays a crucial role in the control of nicotine-elicited DAergic activity. Our results demonstrate that both positive and negative motivational values are transmitted through the dopamine (DA) neuron, but that the concerted activity of DA and GABA systems is necessary for the reinforcing actions of nicotine through burst firing of DA neurons. This work identifies the GABAergic interneuron as a potential target for smoking cessation drug development.

  17. Arachidonic acid-mediated inhibition of a potassium current in the giant neurons of Aplysia

    SciTech Connect

    Carlson, R.O.

    1990-01-01

    Biochemical and electrophysiological approaches were used to investigate the role of arachidonic acid (AA) in the modulation of an inwardly rectifying potassium current (I{sub R}) in the giant neurons of the marine snail, Aplysia californica. Using ({sup 3}H)AA as tracer, the intracellular free AA pool in Aplysia ganglia was found to be in a state of constant and rapid turnover through deacylation and reacylation of phospholipid, primarily phosphatidyl-inositol. This constant turnover was accompanied by a constant release of free AA and eicosanoids into the extracellular medium. The effects of three pharmacological agents were characterized with regard to AA metabolism in Aplysia ganglia. 4-O-tetra-decanoylphorbol 13-acetate (TPA), an activator of protein kinase C, stimulated liberation of AA from phospholipid, and 4-bromophenacylbromide (BPB), an inhibitor of phospholipate A{sub 2}, inhibited this liberation. Indomethacin at 250 {mu}M was found to inhibit uptake of AA, likely through inhibition of acyl-CoA synthetase. These agents were also found to modulate I{sub R} in ways which were consistent with their biological effects: TPA inhibited I{sub R}, and both BPB and indomethacin stimulated I{sub R} . Modulation of I{sub R} by these substances was found not to involve cAMP metabolism. Acute application of exogenous AA did not affect I{sub R}; however, I{sub R} in giant neurons was found to be inhibited after dialysis with AA or other unsaturated fatty acids. Also, after perfusion with BSA overnight, a treatment which strips the giant neurons of AA in lipid storage, I{sub R} was found to have increased over 2-fold. This perfusion-induced increase was inhibited by the presence of AA or by pretreatment of the giant neurons with BPB. These results suggest AA, provided through constant turnover from phospholipid, mediates constitutive inhibition of I{sub R}.

  18. Caffeine-Induced Suppression of GABAergic Inhibition and Calcium-Independent Metaplasticity

    PubMed Central

    Isokawa, Masako

    2016-01-01

    GABAergic inhibition plays a critical role in the regulation of neuron excitability; thus, it is subject to modulations by many factors. Recent evidence suggests the elevation of intracellular calcium ([Ca2+]i) and calcium-dependent signaling molecules underlie the modulations. Caffeine induces a release of calcium from intracellular stores. We tested whether caffeine modulated GABAergic transmission by increasing [Ca2+]i. A brief local puff-application of caffeine to hippocampal CA1 pyramidal cells transiently suppressed GABAergic inhibitory postsynaptic currents (IPSCs) by 73.2 ± 6.98%. Time course of suppression and the subsequent recovery of IPSCs resembled DSI (depolarization-induced suppression of inhibition), mediated by endogenous cannabinoids that require a [Ca2+]i rise. However, unlike DSI, caffeine-induced suppression of IPSCs (CSI) persisted in the absence of a [Ca2+]i rise. Intracellular applications of BAPTA and ryanodine (which blocks caffeine-induced calcium release from intracellular stores) failed to prevent the generation of CSI. Surprisingly, ruthenium red, an inhibitor of multiple calcium permeable/release channels including those of stores, induced metaplasticity by amplifying the magnitude of CSI independently of calcium. This metaplasticity was accompanied with the generation of a large inward current. Although ionic basis of this inward current is undetermined, the present result demonstrates that caffeine has a robust Ca2+-independent inhibitory action on GABAergic inhibition and causes metaplasticity by opening plasma membrane channels. PMID:26998364

  19. The densities of calbindin and parvalbumin, but not calretinin neurons, are sexually dimorphic in the amygdala of the guinea pig.

    PubMed

    Równiak, Maciej; Bogus-Nowakowska, Krystyna; Robak, Anna

    2015-04-16

    In the amygdala, the calcium-binding proteins (calbindin, parvalbumin or calretinin) are useful markers of specific subpopulations of γ-aminobutyric acid (GABA) containing neurons. In the rat and monkey they together mark the vast majority of GABA-containing neurons in this brain region. As GABA involvement in the control of various behaviors in a sex-specific manner and sexual dimorphism of the GABAergic system itself were recently proven, the question is how much dimorphic may be various subpopulations of this system. Thus, the present study investigates for the first time the presence/absence of sexual dimorphism among neurons expressing calbindin (CB), parvalbumin (PV) and calretinin (CR) which form in the amygdala main subsets of GABAergic system. The results show that in the amygdala of the guinea pig the densities of CB and/or PV expressing neurons are sexually dimorphic with the female>male pattern of sex differences in the basolateral amygdala. In the medial and cortical amygdala respectively CB and PV values are also sexually dimorphic, favoring males. The densities of CR expressing neurons are in the amygdala of the guinea pig sexually isomorphic. In conclusion, the results of the present study provide an evidence that in the amygdala of the guinea pig the densities of neurons expressing CB and/or PV are sexually dimorphic what supports the idea that GABA participates in the mediation of sexually dimorphic functions, controlled by this brain area.

  20. BACE1 activity impairs neuronal glucose oxidation: rescue by beta-hydroxybutyrate and lipoic acid

    PubMed Central

    Findlay, John A.; Hamilton, David L.; Ashford, Michael L. J.

    2015-01-01

    Glucose hypometabolism and impaired mitochondrial function in neurons have been suggested to play early and perhaps causative roles in Alzheimer's disease (AD) pathogenesis. Activity of the aspartic acid protease, beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1), responsible for beta amyloid peptide generation, has recently been demonstrated to modify glucose metabolism. We therefore examined, using a human neuroblastoma (SH-SY5Y) cell line, whether increased BACE1 activity is responsible for a reduction in cellular glucose metabolism. Overexpression of active BACE1, but not a protease-dead mutant BACE1, protein in SH-SY5Y cells reduced glucose oxidation and the basal oxygen consumption rate, which was associated with a compensatory increase in glycolysis. Increased BACE1 activity had no effect on the mitochondrial electron transfer process but was found to diminish substrate delivery to the mitochondria by inhibition of key mitochondrial decarboxylation reaction enzymes. This BACE1 activity-dependent deficit in glucose oxidation was alleviated by the presence of beta hydroxybutyrate or α-lipoic acid. Consequently our data indicate that raised cellular BACE1 activity drives reduced glucose oxidation in a human neuronal cell line through impairments in the activity of specific tricarboxylic acid cycle enzymes. Because this bioenergetic deficit is recoverable by neutraceutical compounds we suggest that such agents, perhaps in conjunction with BACE1 inhibitors, may be an effective therapeutic strategy in the early-stage management or treatment of AD. PMID:26483636

  1. Muscarinic presynaptic modulation in GABAergic pallidal synapses of the rat.

    PubMed

    Hernández-Martínez, Ricardo; Aceves, José J; Rueda-Orozco, Pavel E; Hernández-Flores, Teresa; Hernández-González, Omar; Tapia, Dagoberto; Galarraga, Elvira; Bargas, José

    2015-02-01

    The external globus pallidus (GPe) is central for basal ganglia processing. It expresses muscarinic cholinergic receptors and receives cholinergic afferents from the pedunculopontine nuclei (PPN) and other regions. The role of these receptors and afferents is unknown. Muscarinic M1-type receptors are expressed by synapses from striatal projection neurons (SPNs). Because axons from SPNs project to the GPe, one hypothesis is that striatopallidal GABAergic terminals may be modulated by M1 receptors. Alternatively, some M1 receptors may be postsynaptic in some pallidal neurons. Evidence of muscarinic modulation in any of these elements would suggest that cholinergic afferents from the PPN, or other sources, could modulate the function of the GPe. In this study, we show this evidence using striatopallidal slice preparations: after field stimulation in the striatum, the cholinergic muscarinic receptor agonist muscarine significantly reduced the amplitude of inhibitory postsynaptic currents (IPSCs) from synapses that exhibited short-term synaptic facilitation. This inhibition was associated with significant increases in paired-pulse facilitation, and quantal content was proportional to IPSC amplitude. These actions were blocked by atropine, pirenzepine, and mamba toxin-7, suggesting that receptors involved were M1. In addition, we found that some pallidal neurons have functional postsynaptic M1 receptors. Moreover, some evoked IPSCs exhibited short-term depression and a different kind of modulation: they were indirectly modulated by muscarine via the activation of presynaptic cannabinoid CB1 receptors. Thus pallidal synapses presenting distinct forms of short-term plasticity were modulated differently. PMID:25392165

  2. Vinorelbine and epirubicin share common features with polysialic acid and modulate neuronal and glial functions.

    PubMed

    Loers, Gabriele; Saini, Vedangana; Mishra, Bibhudatta; Gul, Sheraz; Chaudhury, Sidhartha; Wallqvist, Anders; Kaur, Gurcharan; Schachner, Melitta

    2016-01-01

    Polysialic acid (PSA), a large, linear glycan composed of 8 to over 100 α2,8-linked sialic acid residues, modulates development of the nervous system by enhancing cell migration, axon pathfinding, and synaptic targeting and by regulating differentiation of progenitor cells. PSA also functions in developing and adult immune systems and is a signature of many cancers. In this study we identified vinorelbine, a semi-synthetic third generation vinca alkaloid, and epirubicin, an anthracycline and 4'-epimer of doxorubicin, as PSA mimetics. Similar to PSA, vinorelbine and epirubicin bind to the PSA-specific monoclonal antibody 735 and compete with the bacterial analog of PSA, colominic acid in binding to monoclonal antibody 735. Vinorelbine and epirubicin stimulate neurite outgrowth of cerebellar neurons via the neural cell adhesion molecule, via myristoylated alanine-rich C kinase substrate, and via fibroblast growth factor receptor, signaling through Erk pathways. Furthermore, the two compounds enhance process formation of Schwann cells and migration of cerebellar neurons in culture, and reduce migration of astrocytes after injury. These novel results show that the structure and function of PSA can be mimicked by the small organic compounds vinorelbine and epirubicin, thus raising the possibility to re-target drugs used in treatment of cancers to nervous system repair. Vinorelbine and epirubicin, identified as PSA mimetics, enhance, like PSA, neuronal migration, neuritogenesis, and formation of Schwann cell processes, and reduce astrocytic migration. Ablating NCAM, inhibiting fibroblast growth factor (FGFR) receptor, or adding the effector domain of myristoylated alanine-rich C kinase substrate (MARCKS) minimize the vinorelbine and epirubicin effects, indicating that they are true PSA mimetics triggering PSA-mediated functions. PMID:26443186

  3. Estrogen administration modulates hippocampal GABAergic subpopulations in the hippocampus of trimethyltin-treated rats

    PubMed Central

    Corvino, Valentina; Di Maria, Valentina; Marchese, Elisa; Lattanzi, Wanda; Biamonte, Filippo; Michetti, Fabrizio; Geloso, Maria Concetta

    2015-01-01

    Given the well-documented involvement of estrogens in the modulation of hippocampal functions in both physiological and pathological conditions, the present study investigates the effects of 17-beta estradiol (E2) administration in the rat model of hippocampal neurodegeneration induced by trimethyltin (TMT) administration (8 mg/kg), characterized by loss of pyramidal neurons in CA1, CA3/hilus hippocampal subfields, associated with astroglial and microglial activation, seizures and cognitive impairment. After TMT/saline treatment, ovariectomized animals received two doses of E2 (0.2 mg/kg intra-peritoneal) or vehicle, and were sacrificed 48 h or 7 days after TMT-treatment. Our results indicate that in TMT-treated animals E2 administration induces the early (48 h) upregulation of genes involved in neuroprotection and synaptogenesis, namely Bcl2, trkB, cadherin 2 and cyclin-dependent-kinase-5. Increased expression levels of glutamic acid decarboxylase (gad) 67, neuropeptide Y (Npy), parvalbumin, Pgc-1α and Sirtuin 1 genes, the latter involved in parvalbumin (PV) synthesis, were also evident. Unbiased stereology performed on rats sacrificed 7 days after TMT treatment showed that although E2 does not significantly influence the extent of TMT-induced neuronal death, significantly enhances the TMT-induced modulation of GABAergic interneuron population size in selected hippocampal subfields. In particular, E2 administration causes, in TMT-treated rats, a significant increase in the number of GAD67-expressing interneurons in CA1 stratum oriens, CA3 pyramidal layer, hilus and dentate gyrus, accompanied by a parallel increase in NPY-expressing cells, essentially in the same regions, and of PV-positive cells in CA1 pyramidal layer. The present results add information concerning the role of in vivo E2 administration on mechanisms involved in cellular plasticity in the adult brain. PMID:26594149

  4. Glycyrrhizin attenuates kainic Acid-induced neuronal cell death in the mouse hippocampus.

    PubMed

    Luo, Lidan; Jin, Yinchuan; Kim, Il-Doo; Lee, Ja-Kyeong

    2013-06-01

    Glycyrrhizin (GL), a triterpene that is present in the roots and rhizomes of licorice (Glycyrrhiza glabra), has been reported to have anti-inflammatory and anti-viral effects. Recently, we demonstrated that GL produced the neuroprotective effects with the suppression of microglia activation and proinflammatory cytokine induction in the postischemic brain with middle cerebral artery occlusion (MCAO) in rats and improved motor impairment and neurological deficits. In the present study, we investigated whether GL has a beneficial effect in kainic acid (KA)-induced neuronal death model. Intracerebroventricular (i.c.v.) injection of 0.94 nmole (0.2 µg) of KA produced typical neuronal death in both CA1 and CA3 regions of the hippocampus. In contrast, administration of GL (10 mg/kg, i.p.) 30 min before KA administration significantly suppressed the neuronal death, and this protective effect was more stronger at 50 mg/kg. Moreover, the GL-mediated neuroprotection was accompanied with the suppression of gliosis and induction of proinflammatory markers (COX-2, iNOS, and TNF-α). The anti-inflammatory and anti-excitotoxic effects of GL were verified in LPS-treated primary microglial cultures and in NMDA- or KA-treated primary cortical cultures. Together these results suggest that GL confers the neuroprotection through the mechanism of anti-inflammatory and anti-excitotoxic effects in KA-treated brain. PMID:23833559

  5. Estradiol-induced synaptic remodeling of tyrosine hydroxylase immunopositive neurons in the rat arcuate nucleus.

    PubMed

    Csakvari, Eszter; Kurunczi, Anita; Hoyk, Zsofia; Gyenes, Andrea; Naftolin, Frederick; Parducz, Arpad

    2008-08-01

    Gonadal steroids induce synaptic plasticity in several areas of the adult nervous system. In the arcuate nucleus of adult female rats, 17beta-estradiol triggers synaptic remodeling, resulting in a decrease in the number of inhibitory synaptic inputs, an increase in the number of excitatory synapses, and an enhancement of the frequency of neuronal firing. In the present paper, we studied the specificity of hormonal effects by determining the changes in synaptic connectivity of tyrosine hydroxylase (TH) immunoreactive (IR) neurons in the arcuate nucleus. We combined pre-embedding TH and post-embedding gamma-aminobutyric acid (GABA) immunostaining, and performed unbiased stereological measurements in gonadectomized and 17beta-estradiol-treated rats. We conclude that the synaptic connectivity of the TH-IR neurons is different from the other, nonlabeled population, and the response to estradiol is not uniform. TH-IR (dopaminergic) arcuate neurons of both male and female rats have more GABAergic (inhibitory) axosomatic inputs than the nondopaminergic population. Our study shows that the effect of 17beta-estradiol is sex and cell specific in the sense that not all arcuate neurons are affected by the structural synaptic remodeling. In ovariectomized females hormone treatment decreased the numerical density of GABAergic axosomatic synapses on TH-IR, but not on nondopaminergic, neurons, whereas in orchidectomized males, 17beta-estradiol treatment increased inhibitory synapses onto nondopaminergic neurons but did not affect the number of inhibitory terminals onto TH-IR neurons. The hormone-induced plastic changes in synaptic connectivity of TH-IR neurons may serve as the morphological basis for the cyclical regulation of the anterior pituitary.

  6. 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

  7. Selective modulation of GABAergic tonic current by dopamine in the nucleus accumbens of alcohol-dependent rats.

    PubMed

    Liang, Jing; Marty, Vincent N; Mulpuri, Yatendra; Olsen, Richard W; Spigelman, Igor

    2014-07-01

    The nucleus accumbens (NAcc) is a key structure of the mesolimbic dopaminergic reward system and plays an important role in mediating alcohol-seeking behaviors. Alterations in glutamatergic and GABAergic signaling were recently demonstrated in the NAcc of rats after chronic intermittent ethanol (CIE) treatment, a model of alcohol dependence. Here we studied dopamine (DA) modulation of GABAergic signaling and how this modulation might be altered by CIE treatment. We show that the tonic current (I(tonic)) mediated by extrasynaptic γ-aminobutyric acid type A receptors (GABA(A)Rs) of medium spiny neurons (MSNs) in the NAcc core is differentially modulated by DA at concentrations in the range of those measured in vivo (0.01-1 μM), without affecting the postsynaptic kinetics of miniature inhibitory postsynaptic currents (mIPSCs). Use of selective D1 receptor (D1R) and D2 receptor (D2R) ligands revealed that I(tonic) potentiation by DA (10 nM) is mediated by D1Rs while I(tonic) depression by DA (0.03-1 μM) is mediated by D2Rs in the same MSNs. Addition of guanosine 5'-O-(2-thiodiphosphate) (GDPβS) to the recording pipettes eliminated I(tonic) decrease by the selective D2R agonist quinpirole (5 nM), leaving intact the quinpirole effect on mIPSC frequency. Recordings from CIE and vehicle control (CIV) MSNs during application of D1R agonist (SKF 38393, 100 nM) or D2R agonist (quinpirole, 2 nM) revealed that SKF 38393 potentiated I(tonic) to the same extent, while quinpirole reduced I(tonic) to a similar extent, in both groups of rats. Our data suggest that the selective modulatory effects of DA on I(tonic) are unaltered by CIE treatment and withdrawal.

  8. Myenteric neurons and intestinal mucosa of diabetic rats after ascorbic acid supplementation

    PubMed Central

    de Freitas, Priscila; Natali, Maria Raquel Marçal; Pereira, Renata Virginia Fernandes; Neto, Marcilio Hubner Miranda; Zanoni, Jacqueline Nelisis

    2008-01-01

    AIM: To investigate the effect of ascorbic acid (AA) dietary supplementation on myenteric neurons and epithelial cell proliferation of the jejunum of adult rats with chronic diabetes mellitus. METHODS: Thirty rats at 90 d of age were divided into three groups: Non-diabetic, diabetic and diabetic treated with AA (DA) (1 g/L). After 120 d of treatment with AA the animals were killed. The myenteric neurons were stained for myosin-V and analyzed quantitatively in an area of 11.2 mm2/animal. We further measured the cellular area of 500 neurons per group. We also determined the metaphasic index (MI) of the jejunum mucosa layer of about 2500 cells in the intestinal crypts, as well as the dimensions of 30 villi and 30 crypts/animal. The data area was analyzed using the Olympus BX40 microscope. RESULTS: There was an increase of 14% in the neuronal density (792.6 ± 46.52 vs 680.6 ± 30.27) and 4.4% in the cellular area (303.4 ± 5.19 vs 291.1 ± 6.0) respectively of the diabetic group treated with AA when compared to control diabetic animals. There were no significant differences in MI parameters, villi height or crypt depths among the groups. CONCLUSION: Supplementation with AA in the diabetic animal promoted moderate neuroprotection. There was no observation of alteration of the cellular proliferation of the jejunum mucosa layer of rats with chronic diabetes mellitus with or without supplementation with AA. PMID:19030205

  9. Modulation of the GABAergic pathway for the treatment of fragile X syndrome

    PubMed Central

    Lozano, Reymundo; Hare, Emma B; Hagerman, Randi J

    2014-01-01

    Fragile X syndrome (FXS) is the most common genetic cause of intellectual disability and the most common single-gene cause of autism. It is caused by mutations on the fragile X mental retardation gene (FMR1) and lack of fragile X mental retardation protein, which in turn, leads to decreased inhibition of translation of many synaptic proteins. The metabotropic glutamate receptor (mGluR) hypothesis states that the neurological deficits in individuals with FXS are due mainly to downstream consequences of overstimulation of the mGluR pathway. The main efforts have focused on mGluR5 targeted treatments; however, investigation on the gamma-aminobutyric acid (GABA) system and its potential as a targeted treatment is less emphasized. The fragile X mouse models (Fmr1-knock out) show decreased GABA subunit receptors, decreased synthesis of GABA, increased catabolism of GABA, and overall decreased GABAergic input in many regions of the brain. Consequences of the reduced GABAergic input in FXS include oversensitivity to sensory stimuli, seizures, and anxiety. Deficits in the GABA receptors in different regions of the brain are associated with behavioral and attentional processing deficits linked to anxiety and autistic behaviors. The understanding of the neurobiology of FXS has led to the development of targeted treatments for the core behavioral features of FXS, which include social deficits, inattention, and anxiety. These symptoms are also observed in individuals with autism and other neurodevelopmental disorders, therefore the targeted treatments for FXS are leading the way in the treatment of other neurodevelopmental syndromes and autism. The GABAergic system in FXS represents a target for new treatments. Herein, we discuss the animal and human trials of GABAergic treatment in FXS. Arbaclofen and ganaxolone have been used in individuals with FXS. Other potential GABAergic treatments, such as riluzole, gaboxadol, tiagabine, and vigabatrin, will be also discussed. Further

  10. DISC1 Protein Regulates γ-Aminobutyric Acid, Type A (GABAA) Receptor Trafficking and Inhibitory Synaptic Transmission in Cortical Neurons.

    PubMed

    Wei, Jing; Graziane, Nicholas M; Gu, Zhenglin; Yan, Zhen

    2015-11-13

    Association studies have suggested that Disrupted-in-Schizophrenia 1 (DISC1) confers a genetic risk at the level of endophenotypes that underlies many major mental disorders. Despite the progress in understanding the significance of DISC1 at neural development, the mechanisms underlying DISC1 regulation of synaptic functions remain elusive. Because alterations in the cortical GABA system have been strongly linked to the pathophysiology of schizophrenia, one potential target of DISC1 that is critically involved in the regulation of cognition and emotion is the GABAA receptor (GABAAR). We found that cellular knockdown of DISC1 significantly reduced GABAAR-mediated synaptic and whole-cell current, whereas overexpression of wild-type DISC1, but not the C-terminal-truncated DISC1 (a schizophrenia-related mutant), significantly increased GABAAR currents in pyramidal neurons of the prefrontal cortex. These effects were accompanied by DISC1-induced changes in surface GABAAR expression. Moreover, the regulation of GABAARs by DISC1 knockdown or overexpression depends on the microtubule motor protein kinesin 1 (KIF5). Our results suggest that DISC1 exerts an important effect on GABAergic inhibitory transmission by regulating KIF5/microtubule-based GABAAR trafficking in the cortex. The knowledge gained from this study would shed light on how DISC1 and the GABA system are linked mechanistically and how their interactions are critical for maintaining a normal mental state.

  11. DISC1 Protein Regulates γ-Aminobutyric Acid, Type A (GABAA) Receptor Trafficking and Inhibitory Synaptic Transmission in Cortical Neurons.

    PubMed

    Wei, Jing; Graziane, Nicholas M; Gu, Zhenglin; Yan, Zhen

    2015-11-13

    Association studies have suggested that Disrupted-in-Schizophrenia 1 (DISC1) confers a genetic risk at the level of endophenotypes that underlies many major mental disorders. Despite the progress in understanding the significance of DISC1 at neural development, the mechanisms underlying DISC1 regulation of synaptic functions remain elusive. Because alterations in the cortical GABA system have been strongly linked to the pathophysiology of schizophrenia, one potential target of DISC1 that is critically involved in the regulation of cognition and emotion is the GABAA receptor (GABAAR). We found that cellular knockdown of DISC1 significantly reduced GABAAR-mediated synaptic and whole-cell current, whereas overexpression of wild-type DISC1, but not the C-terminal-truncated DISC1 (a schizophrenia-related mutant), significantly increased GABAAR currents in pyramidal neurons of the prefrontal cortex. These effects were accompanied by DISC1-induced changes in surface GABAAR expression. Moreover, the regulation of GABAARs by DISC1 knockdown or overexpression depends on the microtubule motor protein kinesin 1 (KIF5). Our results suggest that DISC1 exerts an important effect on GABAergic inhibitory transmission by regulating KIF5/microtubule-based GABAAR trafficking in the cortex. The knowledge gained from this study would shed light on how DISC1 and the GABA system are linked mechanistically and how their interactions are critical for maintaining a normal mental state. PMID:26424793

  12. Involvement of medullary GABAergic system in extraterritorial neuropathic pain mechanisms associated with inferior alveolar nerve transection.

    PubMed

    Okada-Ogawa, Akiko; Nakaya, Yuka; Imamura, Yoshiki; Kobayashi, Masayuki; Shinoda, Masamichi; Kita, Kozue; Sessle, Barry J; Iwata, Koichi

    2015-05-01

    In order to determine if the functional changes in the GABAergic system in the trigeminal spinal subnucleus caudalis (Vc) are involved in the mechanisms underlying extraterritorial neuropathic pain in the orofacial region following inferior alveolar nerve transection (IANX), mechanical noxious behavior, phosphorylated extracellular signal-regulated kinase (pERK) immunohistochemistry and single neuronal activity were analyzed in vesicular GABA transporter (VGAT)-VenusA rats expressing fluorescent protein and the VGAT in Vc neurons. The number of VGAT-VenusA positive neurons was significantly reduced in IANX rats than naive and sham rats at 7days after nerve transection. The number of VGAT-VenusA positive pERK-immunoreactive (IR) cells was significantly increased in IANX rats at 21days after IAN transection compared with naive and sham rats. The background activity and mechanical-evoked responses of Vc nociceptive neurons were significantly depressed after intrathecal application of the GABA receptor agonist muscimol in sham rats but not in IANX rats. Furthermore, the expression of potassium-chloride co-transporter 2 (KCC2) in the Vc was significantly reduced in IANX rats compared with sham rats. The head-withdrawal threshold (HWT) to mechanical stimulation of the whisker pad skin was significantly decreased in IANX rats compared with sham rats on days 7 and 21 after IANX. The significant reduction of the HWT and significant increase in the number of VGAT-VenusA negative pERK-IR cells were observed in KCC2 blocker R-DIOA-injected rats compared with vehicle-injected rats on day 21 after sham treatment. These findings revealed that GABAergic Vc neurons might be reduced in their number at the early period after IANX and the functional changes might occur in GABAergic neurons from inhibitory to excitatory at the late period after IANX, suggesting that the neuroplastic changes occur in the GABAergic neuronal network in the Vc due to morphological and functional changes at

  13. Involvement of medullary GABAergic system in extraterritorial neuropathic pain mechanisms associated with inferior alveolar nerve transection.

    PubMed

    Okada-Ogawa, Akiko; Nakaya, Yuka; Imamura, Yoshiki; Kobayashi, Masayuki; Shinoda, Masamichi; Kita, Kozue; Sessle, Barry J; Iwata, Koichi

    2015-05-01

    In order to determine if the functional changes in the GABAergic system in the trigeminal spinal subnucleus caudalis (Vc) are involved in the mechanisms underlying extraterritorial neuropathic pain in the orofacial region following inferior alveolar nerve transection (IANX), mechanical noxious behavior, phosphorylated extracellular signal-regulated kinase (pERK) immunohistochemistry and single neuronal activity were analyzed in vesicular GABA transporter (VGAT)-VenusA rats expressing fluorescent protein and the VGAT in Vc neurons. The number of VGAT-VenusA positive neurons was significantly reduced in IANX rats than naive and sham rats at 7days after nerve transection. The number of VGAT-VenusA positive pERK-immunoreactive (IR) cells was significantly increased in IANX rats at 21days after IAN transection compared with naive and sham rats. The background activity and mechanical-evoked responses of Vc nociceptive neurons were significantly depressed after intrathecal application of the GABA receptor agonist muscimol in sham rats but not in IANX rats. Furthermore, the expression of potassium-chloride co-transporter 2 (KCC2) in the Vc was significantly reduced in IANX rats compared with sham rats. The head-withdrawal threshold (HWT) to mechanical stimulation of the whisker pad skin was significantly decreased in IANX rats compared with sham rats on days 7 and 21 after IANX. The significant reduction of the HWT and significant increase in the number of VGAT-VenusA negative pERK-IR cells were observed in KCC2 blocker R-DIOA-injected rats compared with vehicle-injected rats on day 21 after sham treatment. These findings revealed that GABAergic Vc neurons might be reduced in their number at the early period after IANX and the functional changes might occur in GABAergic neurons from inhibitory to excitatory at the late period after IANX, suggesting that the neuroplastic changes occur in the GABAergic neuronal network in the Vc due to morphological and functional changes at

  14. Do sensory neurons mediate adaptive cytoprotection of gastric mucosa against bile acid injury?

    PubMed

    Mercer, D W; Ritchie, W P; Dempsey, D T

    1992-01-01

    Pretreatment with the mild irritant 1 mmol acidified taurocholate protects the gastric mucosa from the injury induced by the subsequent application of 5 mmol acidified taurocholate, a phenomenon referred to as "adaptive cytoprotection." How this occurs remains an enigma. The purpose of this study was to investigate the role of sensory neurons and mucus secretion in this phenomenon. Prior to injury with 5 mmol acidified taurocholate (pH 1.2), the stomachs of six groups of rats were subjected to the following protocol. Two groups were topically pretreated with either saline or the mild irritant 1 mmol acidified taurocholate. Two other groups received the topical anesthetic 1% lidocaine prior to pretreatment with either saline or 1 mmol acidified taurocholate. The last two groups got the mucolytic agent 10% N-acetylcysteine (NAC) after pretreatment with either saline or 1 mmol acidified taurocholate. Injury was assessed by measuring net transmucosal ion fluxes, luminal appearance of deoxyribonucleic acid (DNA), and gross and histologic injury. Pretreatment with the mild irritant 1 mmol acidified taurocholate significantly decreased bile acid-induced luminal ion fluxes and DNA accumulation, suggesting mucosal protection (corroborated by gross and histologic injury analysis). This effect was negated by lidocaine but not by NAC. Thus, it appears that sensory neurons, and not increased mucus secretion, play a critical role in adaptive cytoprotection. PMID:1733359

  15. Do sensory neurons mediate adaptive cytoprotection of gastric mucosa against bile acid injury?

    PubMed

    Mercer, D W; Ritchie, W P; Dempsey, D T

    1992-01-01

    Pretreatment with the mild irritant 1 mmol acidified taurocholate protects the gastric mucosa from the injury induced by the subsequent application of 5 mmol acidified taurocholate, a phenomenon referred to as "adaptive cytoprotection." How this occurs remains an enigma. The purpose of this study was to investigate the role of sensory neurons and mucus secretion in this phenomenon. Prior to injury with 5 mmol acidified taurocholate (pH 1.2), the stomachs of six groups of rats were subjected to the following protocol. Two groups were topically pretreated with either saline or the mild irritant 1 mmol acidified taurocholate. Two other groups received the topical anesthetic 1% lidocaine prior to pretreatment with either saline or 1 mmol acidified taurocholate. The last two groups got the mucolytic agent 10% N-acetylcysteine (NAC) after pretreatment with either saline or 1 mmol acidified taurocholate. Injury was assessed by measuring net transmucosal ion fluxes, luminal appearance of deoxyribonucleic acid (DNA), and gross and histologic injury. Pretreatment with the mild irritant 1 mmol acidified taurocholate significantly decreased bile acid-induced luminal ion fluxes and DNA accumulation, suggesting mucosal protection (corroborated by gross and histologic injury analysis). This effect was negated by lidocaine but not by NAC. Thus, it appears that sensory neurons, and not increased mucus secretion, play a critical role in adaptive cytoprotection.

  16. Prefrontal Cortical GABAergic Dysfunction Contributes to Age-Related Working Memory Impairment

    PubMed Central

    Bañuelos, Cristina; Beas, B. Sofia; McQuail, Joseph A.; Gilbert, Ryan J.; Frazier, Charles J.; Setlow, Barry

    2014-01-01

    Working memory functions supported by the prefrontal cortex decline in normal aging. Disruption of corticolimbic GABAergic inhibitory circuits can impair working memory in young subjects; however, relatively little is known regarding how aging impacts prefrontal cortical GABAergic signaling and whether such changes contribute to cognitive deficits. The current study used a rat model to evaluate the effects of aging on expression of prefrontal GABAergic synaptic proteins in relation to working memory decline, and to test whether pharmacological manipulations of prefrontal GABAergic signaling can improve working memory abilities in aged subjects. Results indicate that in aged medial prefrontal cortex (mPFC), expression of the vesicular GABA transporter VGAT was unchanged; however, there was a significant increase in expression of the GABA synthesizing enzyme GAD67, and a significant decrease in the primary neuronal GABA transporter GAT-1 and in both subunits of the GABA(B) receptor (GABA(B)R). Expression of VGAT, GAD67, and GAT-1 was not associated with working memory ability. In contrast, among aged rats, GABA(B)R expression was significantly and negatively associated with working memory performance, such that lower GABA(B)R expression predicted better working memory. Subsequent experiments showed that systemic administration of a GABA(B)R antagonist, CGP55845, dose-dependently enhanced working memory in aged rats. This enhancing effect of systemic CGP55845 was reproduced by direct intra-mPFC administration. Together, these data suggest that age-related dysregulation of GABAergic signaling in prefrontal cortex may play a causal role in impaired working memory and that targeting GABA(B)Rs may provide therapeutic benefit for age-related impairments in executive functions. PMID:24599447

  17. Contribution of the GABAergic pathway(s) to the correlated activities of chicken retinal ganglion cells.

    PubMed

    Liu, Xue; Zhou, Yi; Gong, Hai-Qing; Liang, Pei-Ji

    2007-10-26

    In the present study, the spatiotemporal pattern of chicken retinal ganglion cells' firing activity in response to full-field white light stimulation was investigated. Cross-correlation analysis showed that ganglion cells of sustained subtype fired in precise synchrony with their adjacent neurons of the same subtype (delay lag within 2 ms, narrow correlation). On the other hand, the activities of neighboring ganglion cells of transient subtype were correlated with distributed time lags (10-30 ms, medium correlation). Pharmacological studies demonstrated that the intensity of the medium correlations could be strengthened when exogenous GABA was applied and attenuated when GABA receptors were blocked by picrotoxin. Meanwhile, the GABAergic modulation on the narrow correlations was not consistent. These results suggest that, in the chicken retina, GABAergic pathway(s) are likely involved in the formation of medium correlations between ganglion cells. Neurons might fire at a lower rate but with higher level of synchronization to improve the efficiency of information transmission, with the mechanism involving the GABAergic inhibitory input. PMID:17919471

  18. LAMP5 Fine-Tunes GABAergic Synaptic Transmission in Defined Circuits of the Mouse Brain.

    PubMed

    Tiveron, Marie-Catherine; Beurrier, Corinne; Céni, Claire; Andriambao, Naly; Combes, Alexis; Koehl, Muriel; Maurice, Nicolas; Gatti, Evelina; Abrous, Dhoher Nora; Kerkerian-Le Goff, Lydia; Pierre, Philippe; Cremer, Harold

    2016-01-01

    LAMP5 is member of the LAMP family of membrane proteins. In contrast to the canonical members of this protein family, LAMP1 and LAMP2, which show widespread expression in many tissues, LAMP 5 is brain specific in mice. In C. elegans, the LAMP5 ortholog UNC-46 has been suggested to act a trafficking chaperone, essential for the correct targeting of the nematode vesicular GABA-transporter UNC-47. We show here that in the mouse brain LAMP5 is expressed in subpopulations of GABAergic forebrain neurons in the striato-nigral system and the olfactory bulb. The protein was present at synaptic terminals, overlapping with the mammalian vesicular GABA-transporter VGAT. In LAMP5-deficient mice localization of the transporter was unaffected arguing against a conserved role in VGAT trafficking. Electrophysiological analyses in mutants showed alterations in short term synaptic plasticity suggesting that LAMP5 is involved in controlling the dynamics of evoked GABAergic transmission. At the behavioral level, LAMP5 mutant mice showed decreased anxiety and deficits in olfactory discrimination. Altogether, this work implicates LAMP5 function in GABAergic neurotransmission in defined neuronal subpopulations. PMID:27272053

  19. LAMP5 Fine-Tunes GABAergic Synaptic Transmission in Defined Circuits of the Mouse Brain

    PubMed Central

    Tiveron, Marie-Catherine; Beurrier, Corinne; Céni, Claire; Andriambao, Naly; Combes, Alexis; Koehl, Muriel; Maurice, Nicolas; Gatti, Evelina; Abrous, Dhoher Nora; Kerkerian-Le Goff, Lydia; Pierre, Philippe; Cremer, Harold

    2016-01-01

    LAMP5 is member of the LAMP family of membrane proteins. In contrast to the canonical members of this protein family, LAMP1 and LAMP2, which show widespread expression in many tissues, LAMP 5 is brain specific in mice. In C. elegans, the LAMP5 ortholog UNC-46 has been suggested to act a trafficking chaperone, essential for the correct targeting of the nematode vesicular GABA-transporter UNC-47. We show here that in the mouse brain LAMP5 is expressed in subpopulations of GABAergic forebrain neurons in the striato-nigral system and the olfactory bulb. The protein was present at synaptic terminals, overlapping with the mammalian vesicular GABA-transporter VGAT. In LAMP5-deficient mice localization of the transporter was unaffected arguing against a conserved role in VGAT trafficking. Electrophysiological analyses in mutants showed alterations in short term synaptic plasticity suggesting that LAMP5 is involved in controlling the dynamics of evoked GABAergic transmission. At the behavioral level, LAMP5 mutant mice showed decreased anxiety and deficits in olfactory discrimination. Altogether, this work implicates LAMP5 function in GABAergic neurotransmission in defined neuronal subpopulations. PMID:27272053

  20. Histone Deacetylase Inhibition Rescues Maternal Deprivation-Induced GABAergic Metaplasticity through Restoration of AKAP Signaling.

    PubMed

    Authement, Michael E; Kodangattil, Jayaraj N; Gouty, Shawn; Rusnak, Milan; Symes, Aviva J; Cox, Brian M; Nugent, Fereshteh S

    2015-06-01

    Adverse early-life experiences such as child neglect and abuse increase the risk of developing addiction and stress-related disorders through alterations in motivational systems including the mesolimbic dopamine (DA) pathway. Here we investigated whether a severe early-life stress (i.e., maternal deprivation, MD) promotes DA dysregulation through an epigenetic impairment of synaptic plasticity within ventral tegmental area (VTA) DA neurons. Using a single 24-hr episode of MD and whole-cell patch clamp recording in rat midbrain slices, we show that MD selectively induces long-term depression (LTD) and shifts spike timing-dependent plasticity (STDP) toward LTD at GABAergic synapses onto VTA DA neurons through epigenetic modifications of postsynaptic scaffolding A-kinase anchoring protein 79/150 (AKAP79/150) signaling. Histone deacetylase (HDAC) inhibition rescues GABAergic metaplasticity and normalizes AKAP signaling in MD animals. MD-induced reversible HDAC-mediated GABAergic dysfunction within the VTA may be a mechanistic link for increased propensity to mental health disorders following MD. PMID:26050042

  1. Aprotinin, but not epsilon aminocaproic acid and tranexamic acid, exerts neuroprotection against excitotoxic injury in an in vitro neuronal cell culture model

    PubMed Central

    Lu, Zhaohui; Korotcova, Ludmila; Murata, Akira; Ishibashi, Nobuyuki; Jonas, Richard A.

    2013-01-01

    Objective Lack of availability of aprotinin has resulted in increased clinical use of the alternative antifibrinolytic agents epsilon aminocaproic acid (EACA) and tranexamic acid (TXA) which are known to be associated with an increased risk of seizures. In contrast aprotinin has previously been demonstrated to be neuroprotective through suppression of excitotoxicity-mediated neuronal degeneration via the extracellular plasminogen/plasmin system. We compared the impact of antifibrinolytic agents on neuronal and mixed glial/neuronal cell cultures. Methods Mixed cortical cultures containing neuronal and glial cells were prepared from fetal mice and plated on a layer of confluent astrocytes from postnatal pups. Primary neuronal culture was obtained from the same gestational stage and plated in multiwall vessels. Slowly triggered excitotoxicity was induced by 24-hour exposure to 12.5 mM N-methyl-D-aspartate (NMDA). Apoptotic neuronal cell death was induced by exposure of primary neural cultures to 24 hours of serum deprivation. Results Compared to NMDA alone, no significant changes in cell death were observed for any dose of TXA or EACA in mixed cultures. Conversely, a clinical dose of aprotinin significantly reduced cell death by -31% on average. Aprotinin reduced apoptotic neuronal cell death from 75% to 37.3%, and 34.1% at concentrations of 100 and 200 KIU/mL, and significantly decreased neuronal nuclear damage. These concentrations of aprotinin significantly inhibited caspase 9 and 3/7 activations. 250 KIU/ml aprotinin exerted maximal protection on primary cortical neurons. Conclusions In contrast to aprotinin, EACA and TXA exert no protective effect against excitotoxic neuronal injury that can occur during cardiac surgery. PMID:24237885

  2. Electrophysiological evidence for convergence of inputs from the medial prefrontal cortex and lateral habenula on single neurons in the dorsal raphe nucleus.

    PubMed

    Varga, V; Kocsis, B; Sharp, T

    2003-01-01

    Neuronal projections to the dorsal raphe nucleus (DRN) from the medial prefrontal cortex (mPFC) and lateral habenula nucleus (LHb) provide the two key routes by which information processed by mood regulatory, cortico-limbic-striatal circuits input into the 5-HT system. These two projections may converge as it appears that both activate local GABAergic neurons to inhibit 5-HT neurons in the DRN. Here we have tested this hypothesis by measuring the effect of stimulation of the mPFC and LHb on the activity of 5-HT and non-5-HT, putative gamma-amino butyric acid (GABA) neurons in the DRN using extracellular recordings in anaesthetized rats. A total of 119 5-HT neurons (regular, slow firing, broad spike width) and 21 non-5-HT, putative GABA neurons (fast-firing, narrow spike width) were tested. Electrical stimulation of the mPFC or LHb caused a poststimulus inhibition (30 ms latency) of 101/119 5-HT neurons, of which 61 (60%) were inhibited by both the mPFC and LHb. Electrical stimulation of the mPFC or LHb also caused a short latency (12-20 ms) poststimulus facilitation of 10/21 non-5-HT neurons, of which 5 (50%) were activated by both the mPFC and LHb. These data indicate that a significant number of 5-HT neurons and non-5-HT neurons in the DRN are influenced by both the mPFC and LHb. Moreover, the data are compatible with the hypothesis and that there is a convergence of mPFC and LHb inputs on local circuit GABAergic neurons in the DRN which in turn inhibit the activity of 5-HT neurons.

  3. Exclusive and common targets of neostriatofugal projections of rat striosome neurons: a single neuron-tracing study using a viral vector.

    PubMed

    Fujiyama, Fumino; Sohn, Jaerin; Nakano, Takashi; Furuta, Takahiro; Nakamura, Kouichi C; Matsuda, Wakoto; Kaneko, Takeshi

    2011-02-01

    The rat neostriatum has a mosaic organization composed of striosome/patch compartments embedded in a more extensive matrix compartment, which are distinguished from each other by the input-output organization as well as by the expression of many molecular markers. The matrix compartment gives rise to the dual γ-aminobutyric acid (GABA)ergic striatofugal systems, i.e. direct and indirect pathway neurons, whereas the striosome compartment is considered to involve direct pathway neurons alone. Although the whole axonal arborization of matrix striatofugal neurons has been examined in vivo by intracellular staining, that of striosome neurons has never been studied at the single neuron level. In the present study, the axonal arborizations of single striosome projection neurons in rat neostriatum were visualized in their entirety using a viral vector expressing membrane-targeted green fluorescent protein, and compared with that of matrix projection neurons. We found that not only matrix but also striosome compartments contained direct and indirect pathway neurons. Furthermore, only striatonigral neurons in the striosome compartment projected directly to the substantia nigra pars compacta (SNc), although they sent a substantial number of axon collaterals to the globus pallidus, entopeduncular nucleus and/or substantia nigra pars reticulata. These results suggest that striosome neurons play a more important role in the formation of reward-related signals of SNc dopaminergic neurons than do matrix neurons. Together with data from previous studies in the reinforcement learning theory, our results suggest that these direct and indirect striosome-SNc pathways together with nigrostriatal dopaminergic neurons may help striosome neurons to acquire the state-value function.

  4. Role of Prelimbic GABAergic Circuits in Sensory and Emotional Aspects of Neuropathic Pain.

    PubMed

    Zhang, Zizhen; Gadotti, Vinicius M; Chen, Lina; Souza, Ivana A; Stemkowski, Patrick L; Zamponi, Gerald W

    2015-08-01

    Noxious stimuli are detected by peripheral nociceptors and then transmitted to higher CNS centers, where they are perceived as an unpleasant sensation. The mechanisms that govern the emotional component associated with pain are still incompletely understood. Here, we used optogenetic approaches both in vitro and in vivo to address this issue. We found that peripheral nerve injury inhibits pyramidal cell firing in the prelimbic area of the prefrontal cortex as a result of feed-forward inhibition mediated by parvalbumin-expressing GABAergic interneurons. In addition, activation of inhibitory archaerhodopsin or excitatory channelrhodopsin-2 in these neurons decreased and increased pain responses, respectively, in freely moving mice and accordingly modulated conditioned place preference scores and place escape/avoidance behavior. Our findings thus demonstrate an important role of the prelimbic area in sensory and emotional aspects of pain and identify GABAergic circuits in this region as a potential target for pain therapeutics.

  5. Desensitization of GABAergic receptors as a mechanism of zolpidem-induced somnambulism.

    PubMed

    Juszczak, Grzegorz R

    2011-08-01

    Sleepwalking is a frequently reported side effect of zolpidem which is a short-acting hypnotic drug potentiating activity of GABA(A) receptors. Paradoxically, the most commonly used medications for somnambulism are benzodiazepines, especially clonazepam, which also potentiate activity of GABA(A) receptors. It is proposed that zolpidem-induced sleepwalking can be explained by the desensitization of GABAergic receptors located on serotonergic neurons. According to the proposed model, the delay between desensitization of GABA receptors and a compensatory decrease in serotonin release constitutes the time window for parasomnias. The occurrence of sleepwalking depends on individual differences in receptor desensitization, autoregulation of serotonin release and drug pharmacokinetics. The proposed mechanism of interaction between GABAergic and serotonergic systems can be also relevant for zolpidem abuse and zolpidem-induced hallucinations. It is therefore suggested that special care should be taken when zolpidem is used in patients taking at the same time selective serotonin reuptake inhibitors. PMID:21565448

  6. Desensitization of GABAergic receptors as a mechanism of zolpidem-induced somnambulism.

    PubMed

    Juszczak, Grzegorz R

    2011-08-01

    Sleepwalking is a frequently reported side effect of zolpidem which is a short-acting hypnotic drug potentiating activity of GABA(A) receptors. Paradoxically, the most commonly used medications for somnambulism are benzodiazepines, especially clonazepam, which also potentiate activity of GABA(A) receptors. It is proposed that zolpidem-induced sleepwalking can be explained by the desensitization of GABAergic receptors located on serotonergic neurons. According to the proposed model, the delay between desensitization of GABA receptors and a compensatory decrease in serotonin release constitutes the time window for parasomnias. The occurrence of sleepwalking depends on individual differences in receptor desensitization, autoregulation of serotonin release and drug pharmacokinetics. The proposed mechanism of interaction between GABAergic and serotonergic systems can be also relevant for zolpidem abuse and zolpidem-induced hallucinations. It is therefore suggested that special care should be taken when zolpidem is used in patients taking at the same time selective serotonin reuptake inhibitors.

  7. Cholinergic properties of neurons differentiated from an embryonal carcinoma cell-line (P19).

    PubMed

    Parnas, D; Linial, M

    1995-11-01

    P19 is a mouse-derived embryonal carcinoma cell-line capable of differentiation toward ectodermal, mesodermal and endodermal lineages. Following treatment with retinoic acid these cells differentiate into neurons, astrocytes and fibroblast-like cells. We induced P19 differentiation under conditions which lead to a homogeneous neuronal culture (> 95% neurons). Under these conditions, most cells (approximately 85%) express high levels of the cholinergic markers acetyl cholinesterase and choline acetyltransferase while approximately 10% of cells express the GABAergic marker glutamic acid decarboxylase. While the proportion of the GABAergic neurons is constant at different culture conditions, the cholinergic phenotype is suppressed at high cell densities. The cholinergic nature of P19 neurons is also evident in their ability to form contacts with a muscle cell-line--C2. At day 10 of differentiation cells are capable of depolarization-dependent acetylcholine release. The release is Ca2+ dependent, and drops to baseline levels at 0.5 mM Ca2+. The cells also respond to sub-nM levels of alpha-latrotoxin by acetylcholine release. All major proteins implicated in synapse functionality are expressed prior to day 10 at both at RNA and protein levels. However, the expression pattern of each gene is unique. The genes include cytoskeletal proteins, synaptic vesicle proteins and terminal specific proteins. We suggest that this cell-line can serve as an in-vitro model system for the study of neuronal phenotype acquisition. Under our conditions, the P19 cells can also provide a system in which to study the differentiation of functional cholinergic neurons. PMID:8787867

  8. Ensemble Recording of Electrical Activity in Neurons Derived from P19 Embryonal Carcinoma Cells

    NASA Astrophysics Data System (ADS)

    Takayama, Yuzo; Saito, Atushi; Moriguchi, Hiroyuki; Kotani, Kiyoshi; Jimbo, Yasuhiko

    Regeneration of the central nervous system (CNS) is one of the most important research themes in neuroscience and neuroengineering. It is essential to replenish the lost neurons and to establish appropriate functional neuronal networks using pluripotent stem cells. Little is known, however, about the properties of stem cell-derived neuronal networks, particularly under the differentiation and development processes. In this work, we cultured P19 embryonal carcinoma cells on micro-electrode arrays (MEAs). P19 cells were differentiated into neurons by retinoic acid application and formed densely connected networks. Spontaneous electrical activity was extracellulary recorded through substrate electrodes and analyzed. Synchronized periodic bursts, which were the characteristic features in primary cultured CNS neurons, were observed. Pharmacological studies demonstrated that the glutamatergic excitatory synapses and the GABAergic inhibitory synapses were active in these P19-derived neuronal networks. The results suggested that MEA-based recording was useful for monitoring differentiation processes of stem cells. P19-derived neuronal networks had quite similar network properties to those of primary cultured neurons, and thus provide a novel model system to investigate stem cell-based neuronal regeneration.

  9. The protective role of ascorbic acid on hippocampal CA1 pyramidal neurons in a rat model of maternal lead exposure.

    PubMed

    Sepehri, Hamid; Ganji, Farzaneh

    2016-07-01

    Oxidative stress is a major pathogenic mechanism of lead neurotoxicity. The antioxidant ascorbic acid protects hippocampal pyramidal neurons against cell death during congenital lead exposure; however, critical functions like synaptic transmission, integration, and plasticity depend on preservation of dendritic and somal morphology. This study was designed to examine if ascorbic acid also protects neuronal morphology during developmental lead exposure. Timed pregnant rats were divided into four treatment groups: (1) control, (2) 100mg/kg ascorbic acid once a day via gavage, (3) 0.05% lead acetate in drinking water, and (4) 0.05% lead+100mg/kg oral ascorbic acid. Brains of eight male pups (P25) per treatment group were processed for Golgi staining. Changes in hippocampal CA1 pyramidal neurons' somal size were estimated by cross-sectional area and changes in dendritic arborization by Sholl's analysis. One-way ANOVA was used to compare results among treatment groups. Lead-exposed pups exhibited a significant decrease in somal size compared to controls (P<0.01) that was reversed by cotreatment with ascorbic acid. Sholl's analysis revealed a significant increase in apical dendritic branch points near cell body (P<0.05) and a decreased total dendritic length in both apical and basal dendritic trees of CA1 neurons (P<0.05). Ascorbic acid significantly but only partially reversed the somal and dendritic damage caused by developmental lead exposure. Oxidative stress thus contributes to lead neurotoxicity but other pathogenic mechanisms are also involved.

  10. Genetic cell targeting uncovers specific neuronal types and distinct subregions in the bed nucleus of the stria terminalis.

    PubMed

    Nguyen, Amanda Q; Dela Cruz, Julie A D; Sun, Yanjun; Holmes, Todd C; Xu, Xiangmin

    2016-08-15

    The bed nucleus of the stria terminalis (BNST) plays an important role in fear, stress, and anxiety. It contains a collection of subnuclei delineated by gross cytoarchitecture features; however, there has yet to be a systematic examination of specific BNST neuronal types and their associated neurochemical makeup. The present study focuses on improved characterization of the anterior BNST based on differing molecular and chemical expression aided by mouse genetics. Specific Cre driver lines crossed with a fluorescent reporter line were used for genetic cell targeting and immunochemical staining. Using this new approach, we were able to robustly identify specific excitatory and inhibitory cell types in the BNST. The presence and distribution of excitatory neurons were firmly established; glutamatergic neurons in the anterior BNST accounted for about 14% and 31% of dorsal and ventral BNST cells, respectively. GABAergic neurons expressing different isoforms of glutamic acid decarboxylase were found to have differential subregional distributions. Almost no parvalbumin-expressing cells were found in the BNST, while somatostatin-expressing cells and calretinin-expressing cells account for modest proportions of BNST cells. In addition, vasoactive intestinal peptide-expressing axonal plexuses were prominent in the oval and juxtacapsular subregions. In addition, we discovered that corticotropin-releasing hormone-expressing cells contain GABAergic and glutamatergic subpopulations. Together, this study reveals new information on excitatory and inhibitory neurons in the BNST, which will facilitate genetic dissection and functional studies of BNST subregions. J. Comp. Neurol. 524:2379-2399, 2016. © 2016 Wiley Periodicals, Inc. PMID:26718312

  11. Prenatal betamethasone does not affect glutamatergic or GABAergic neurogenesis in preterm newborns.

    PubMed

    Vose, L R; Vinukonda, G; Diamond, D; Korumilli, R; Hu, F; Zia, M T K; Hevner, R; Ballabh, P

    2014-06-13

    Prenatal glucocorticoids (GCs) are routinely used for pregnant women in preterm labor to prevent respiratory distress syndrome and intraventricular hemorrhage in premature infants. However, the effect of antenatal GCs on neurogenesis in preterm neonates remains elusive. Herein, we hypothesized that prenatal GCs might suppress both glutamatergic and GABAergic neurogenesis in preterm rabbits and that this treatment would induce distinct changes in the expression of transcription factors regulating these developmental events. To test our hypotheses, we treated pregnant rabbits with betamethasone at E27 and E28, delivered the pups at E29 (term=32d), and assessed neurogenesis at birth and postnatal day 3. We quantified radial glia (Sox2(+)) and intermediate progenitor cells (Tbr2(+)) in the dorsal cortical subventricular zone to assess glutamatergic neuronal progenitors, and counted Nkx2.1(+) and Dlx2(+) cells in the ganglionic eminence to evaluate GABAergic neurogenesis. In addition, we assayed transcription factors regulating neurogenesis. We found that prenatal GCs did not affect the densities of radial glia and intermediate progenitors of glutamatergic or GABAergic neurons. The number of GABA(+) interneurons in the ganglionic eminence was similar between the prenatal GC-treated pups compared to untreated controls. Moreover, the mRNA expression of transcription factors, including Pax6, Ngn1/2, Emx1/2, Insm1, Dlx1, Nkx2.1, and Gsh2, were comparable between the two groups. However, there was a transient elevation in Mash1 protein in betamethasone-treated pups relative to controls at birth. These data suggest that prenatal GC treatment does not significantly impact the balance of glutamatergic and GABAergic neurogenesis in premature infants.

  12. Prenatal betamethasone does not affect glutamatergic or GABAergic neurogenesis in preterm newborns

    PubMed Central

    Vose, Linnea R.; Vinukonda, Govindaiah; Diamond, Daniel; Korumilli, Ritesh; Hu, Furong; Zia, Muhammad TK; Hevner, Robert; Ballabh, Praveen

    2014-01-01

    Prenatal glucocorticoids (GCs) are routinely used for pregnant women in preterm labor to prevent respiratory distress syndrome and intraventricular hemorrhage in premature infants. However, the effect of antenatal GCs on neurogenesis in preterm neonates remains elusive. Herein, we hypothesized that prenatal GCs might suppress both glutamatergic and GABAergic neurogenesis in preterm rabbits and that this treatment would induce distinct changes in the expression of transcription factors regulating these developmental events. To test our hypotheses, we treated pregnant rabbits with betamethasone at E27 and E28, delivered the pups at E29 (term=32d), and assessed neurogenesis at birth and postnatal day 3. We quantified radial glia (Sox2+) and intermediate progenitor cells (Tbr2+) in the dorsal cortical subventricular zone to assess glutamatergic neuronal progenitors, and counted Nkx2.1+ and Dlx2+ cells in the ganglionic eminence to evaluate GABAergic neurogenesis. In addition, we assayed transcription factors regulating neurogenesis. We found that prenatal GCs did not affect the densities of radial glia and intermediate progenitors of glutamatergic or GABAergic neurons. The number of GABA+ interneurons in the ganglionic eminence was similar between the prenatal GC treated pups compared to untreated controls. Moreover, the mRNA expression of transcription factors, including Pax6, Ngn1/2, Emx1/2, Insm1, Dlx1, Nkx2.1, and Gsh2, were comparable between the two groups. However, there was a transient elevation in Mash1 protein in betamethasone treated pups relative to controls at birth. This data suggests that prenatal GC treatment does not significantly impact the balance of glutamatergic and GABAergic neurogenesis in premature infants. PMID:24735821

  13. Odd-skipped labels a group of distinct neurons associated with the mushroom body and optic lobe in the adult Drosophila brain.

    PubMed

    Levy, Peter; Larsen, Camilla

    2013-11-01

    Olfactory processing has been intensively studied in Drosophila melanogaster. However, we still know little about the descending neural pathways from the higher order processing centers and how these connect with other neural circuits. Here we describe, in detail, the adult projections patterns that arise from a cluster of 78 neurons, defined by the expression of the Odd-skipped transcription factor. We term these neurons Odd neurons. By using expression of genetically encoded axonal and dendritic markers, we show that a subset of the Odd neurons projects dendrites into the calyx of the mushroom body (MB) and axons into the inferior protocerebrum. We exclude the possibility that the Odd neurons are part of the well-known Kenyon cells whose projections form the MB and conclude that the Odd neurons belong to a previously not described class of extrinsic MB neurons. In addition, three of the Odd neurons project into the lobula plate of the optic lobe, and two of these cells extend axons ipsi- and contralaterally in the brain. Anatomically, these cells do not resemble any previously described lobula plate tangential cells (LPTCs) in Drosophila. We show that the Odd neurons are predominantly cholinergic but also include a small number of γ-aminobutyric acid (GABA)ergic neurons. Finally, we provide evidence that the Odd neurons are a hemilineage, suggesting they are born from a defined set of neuroblasts. Our anatomical analysis hints at the possibility that subgroups of Odd neurons could be involved in olfactory and visual processing.

  14. Genetically Defined Inhibitory Neurons in the Mouse Spinal Cord Dorsal Horn: A Possible Source of Rhythmic Inhibition of Motoneurons during Fictive Locomotion

    PubMed Central

    Wilson, Jennifer M.; Blagovechtchenski, Evgueni; Brownstone, Robert M.

    2016-01-01

    To ensure alternation of flexor and extensor muscles during locomotion, the spinal locomotor network provides rhythmic inhibition to motoneurons. The source of this inhibition in mammals is incompletely defined. We have identified a population of GABAergic inter-neurons located in medial laminae V/VI that express green fluorescent protein (GFP) in glutamic acid decarboxylase-65::GFP transgenic mice. Immunohistochemical studies revealed GFP + terminals in apposition to motoneuronal somata, neurons in Clarke’s column, and in laminae V/VI where they apposed GFP + interneurons, thus forming putative reciprocal connections. Whole-cell patch-clamp recordings from GFP + interneurons in spinal cord slices revealed a range of electrophysiological profiles, including sag and postinhibitory rebound potentials. Most neurons fired tonically in response to depolarizing current injection. Calcium transients demonstrated by two-photon excitation microscopy in the hemisected spinal cord were recorded in response to low-threshold dorsal root stimulation, indicating these neurons receive primary afferent input. Following a locomotor task, the number of GFP + neurons expressing Fos increased, indicating that these neurons are active during locomotion. During fictive locomotion induced in the hemisected spinal cord, two-photon excitation imaging demonstrated rhythmic calcium activity in these interneurons, which correlated with the termination of ventral root bursts. We suggest that these dorsomedial GABAergic interneurons are involved in spinal locomotor networks, and may provide direct rhythmic inhibitory input to motoneurons during locomotion. PMID:20089922

  15. Increased expression of the homologue of enhancer-of-split 1 protects neurons from beta amyloid neurotoxicity and hints at an alternative role for transforming growth factor beta1 as a neuroprotector

    PubMed Central

    2012-01-01

    Introduction Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the deposition of β-amyloid (Aβ) in the brain, which produces progressive neuronal loss and dementia. We recently demonstrated that the noxious effects of Aβ on cultured hippocampal neurons are in part provoked by the antagonism of nerve growth factor (NGF) signalling, which impairs the activation of nuclear factor κB (NF-κB) by impeding the tyrosine phosphorylation of I-κBα. As a result, the expression of the homologue of Enhancer-of split 1 (Hes1) gene is downregulated and ultimately, gamma-aminobutyric acid (GABA)-ergic connectivity is lost. Methods Hes1 activity was promoted in cultured hippocampal neurons by overexpressing a Hes1-encoding plasmid or by upregulating this gene by activating NF-κB through different approaches (overexpressing either the I-κB kinaseβ, or p65/RelA/NF-κB). Alternatively neurons were exposed to TGFβ1. Dendrite patterning, GABAergic connectivity and cell survival were analyzed by immunofluorescence microscopy. Hes1 expression was determined by real-time PCR. NF-κB activation was measured using the dual-luciferase reporter assay. Results The expression of Hes1 abolished the effects of Aβ on dendritic patterning and GABAergic input, and it prevented the death of the cultured neurons. TGFβ1, a known neuroprotector, could counteract the deleterious effects of Aβ by inducing NF-κB activation following the serine phosphorylation of I-κBα. Indeed, the number of GABAergic terminals generated by inducing Hes1 expression was doubled. Conclusion Our data define some of the mechanisms involved in Aβ-mediated cell death and they point to potential means to counteract this noxious activity. PMID:22849569

  16. Sprouty2 and -4 hypomorphism promotes neuronal survival and astrocytosis in a mouse model of kainic acid induced neuronal damage.

    PubMed

    Thongrong, Sitthisak; Hausott, Barbara; Marvaldi, Letizia; Agostinho, Alexandra S; Zangrandi, Luca; Burtscher, Johannes; Fogli, Barbara; Schwarzer, Christoph; Klimaschewski, Lars

    2016-05-01

    Sprouty (Spry) proteins play a key role as negative feedback inhibitors of the Ras/Raf/MAPK/ERK pathway downstream of various receptor tyrosine kinases. Among the four Sprouty isoforms, Spry2 and Spry4 are expressed in the hippocampus. In this study, possible effects of Spry2 and Spry4 hypomorphism on neurodegeneration and seizure thresholds in a mouse model of epileptogenesis was analyzed. The Spry2/4 hypomorphs exhibited stronger ERK activation which was limited to the CA3 pyramidal cell layer and to the hilar region. The seizure threshold of Spry2/4(+/-) mice was significantly reduced at naive state but no difference to wildtype mice was observed 1 month following KA treatment. Histomorphological analysis revealed that dentate granule cell dispersion (GCD) was diminished in Spry2/4(+/-) mice in the subchronic phase after KA injection. Neuronal degeneration was reduced in CA1 and CA3 principal neuron layers as well as in scattered neurons of the contralateral CA1 and hilar regions. Moreover, Spry2/4 reduction resulted in enhanced survival of somatostatin and neuropeptide Y expressing interneurons. GFAP staining intensity and number of reactive astrocytes markedly increased in lesioned areas of Spry2/4(+/-) mice as compared with wildtype mice. Taken together, although the seizure threshold is reduced in naive Spry2/4(+/-) mice, neurodegeneration and GCD is mitigated following KA induced hippocampal lesions, identifying Spry proteins as possible pharmacological targets in brain injuries resulting in neurodegeneration. The present data are consistent with the established functions of the ERK pathway in astrocyte proliferation as well as protection from neuronal cell death and suggest a novel role of Spry proteins in the migration of differentiated neurons.

  17. Luteolin protects the hippocampus against neuron impairments induced by kainic acid in rats.

    PubMed

    Lin, Tzu Yu; Lu, Cheng Wei; Wang, Su Jane

    2016-07-01

    Glutamatergic excitotoxicity is crucial in the pathogenesis of numerous brain disorders. Luteolin, a flavonoid compound, inhibits glutamate release, however, its ability to affect glutamate-induced brain injury is unknown. Therefore, this study evaluated the protective effect of luteolin against brain damage induced by kainic acid (KA), a glutamate analog. Rats were treated with luteolin (10 or 50mg/kg, intraperitoneally) 30min before an intraperitoneal injection of KA (15mg/kg). Luteolin treatment reduced the KA-induced seizure score and elevations of glutamate levels in the hippocampus. A histopathological analysis showed that luteolin attenuated KA-induced neuronal death and microglial activation in the hippocampus. An immunoblotting analysis showed that luteolin restored the KA-induced reduction in Akt phosphorylation in the hippocampus. Furthermore, a Morris water maze test revealed that luteolin effectively prevented KA-induced learning and memory impairments. The results suggest that luteolin protected rat brains from KA-induced excitotoxic damage by reducing glutamate levels, mitigating inflammation, and enhancing Akt activation in the hippocampus. Therefore, luteolin may be beneficial for preventing or treating brain disorders associated with excitotoxic neuronal damage. PMID:27185356

  18. Caffeic acid phenethyl ester protects against the dopaminergic neuronal loss induced by 6-hydroxydopamine in rats.

    PubMed

    Barros Silva, R; Santos, N A G; Martins, N M; Ferreira, D A S; Barbosa, F; Oliveira Souza, V C; Kinoshita, A; Baffa, O; Del-Bel, E; Santos, A C

    2013-03-13

    Caffeic acid phenethyl ester (CAPE) is a botanical compound abundant in honeybees' propolis. It has anti-inflammatory, antiviral, antioxidant, immunomodulatory and antitumor properties. Its beneficial effects against neurodegenerative diseases, including Parkinson's disease, have also been suggested and some mechanisms have been proposed. Mitochondrial damage and oxidative stress are critical events in neurodegeneration. Release of cytochrome c from mitochondria to cytosol and the downstream activation of caspase-3 have been suggested as targets of the protective mechanism of CAPE. Most of the studies addressing the protective effect of CAPE have been performed in cell culture. This is the first study to demonstrate the protective effect of CAPE against the dopaminergic neuronal loss induced by 6-hydroxydopamine (6-OHDA) in rats. It also demonstrates, for the first time, the inhibitory effect of CAPE on mitochondrial permeability transition (MPT), a mediator of neuronal death that triggers cytochrome c release and caspase-3 activation. Scavenging of reactive oxygen species (ROS) and metal chelation was demonstrated in the brain-affected areas of the rats treated with 6-OHDA and CAPE. Additionally, we demonstrated that CAPE does not affect brain mitochondrial function. Based on these findings and on its ability to cross the blood-brain barrier, CAPE is a promising compound to treat Parkinson's and other neurodegenerative diseases.

  19. Folic Acid potentiates the effect of memantine on spatial learning and neuronal protection in an Alzheimer's disease transgenic model.

    PubMed

    Chen, Ta-Fu; Huang, Rwei-Fen S; Lin, Sey-En; Lu, Jyh-Feng; Tang, Ming-Chi; Chiu, Ming-Jang

    2010-01-01

    Folic acid deficiency and hyperhomocysteinemia potentiate amyloid-beta (Abeta) neuron toxicity. Memantine, an NMDA antagonist used in moderate to severe AD, is considered to be neuroprotective. We propose that folic acid might have a synergistic effect for memantine in protecting neurons from Abeta accumulation. We treated 8-month-old Tg2576 transgenic mice with memantine (30 mg/kg/day) with or without folic acid (8 mg/kg/day) for 4 months. Escape latencies in the Morris water maze were significantly shorter in the folic acid-memantine treatment group Tg(+)_M+F compared to both the non-treatment transgenic controls Tg(+) and the memantine-treatment group Tg(+)_M (both p < 0.05). Analysis of Abeta40 and Abeta42 showed lower brain loads in both treatment groups but this did not reach statistical significance. Histopathology analysis showed that Tg(+)_M+F had lower ratios of neuronal damage than Tg(+) (p < 0.001) and Tg(+)_M (p< 0.005). DNA analysis revealed that in the Tg(+)M_+F group, transcription was upregulated in 72 brain genes involved in neurogenesis, neural differentiation, memory, and neurotransmission compared to the Tg(+)_M group. In conclusion, we found that folic acid may potentiate the effect of memantine on spatial learning and neuronal protection. The benefit of combination therapy may be through co-action on the methylation-controlled Abeta production, and modification of brain gene expression.

  20. Inhibitory Input from the Lateral Hypothalamus to the Ventral Tegmental Area Disinhibits Dopamine Neurons and Promotes Behavioral Activation.

    PubMed

    Nieh, Edward H; Vander Weele, Caitlin M; Matthews, Gillian A; Presbrey, Kara N; Wichmann, Romy; Leppla, Christopher A; Izadmehr, Ehsan M; Tye, Kay M

    2016-06-15

    Projections from the lateral hypothalamus (LH) to the ventral tegmental area (VTA), containing both GABAergic and glutamatergic components, encode conditioned responses and control compulsive reward-seeking behavior. GABAergic neurons in the LH have been shown to mediate appetitive and feeding-related behaviors. Here we show that the GABAergic component of the LH-VTA pathway supports positive reinforcement and place preference, while the glutamatergic component mediates place avoidance. In addition, our results indicate that photoactivation of these projections modulates other behaviors, such as social interaction and perseverant investigation of a novel object. We provide evidence that photostimulation of the GABAergic LH-VTA component, but not the glutamatergic component, increases dopamine (DA) release in the nucleus accumbens (NAc) via inhibition of local VTA GABAergic neurons. Our study clarifies how GABAergic LH inputs to the VTA can contribute to generalized behavioral activation across multiple contexts, consistent with a role in increasing motivational salience. VIDEO ABSTRACT. PMID:27238864

  1. The GAD65 knock out mouse - a model for GABAergic processes in fear- and stress-induced psychopathology.

    PubMed

    Müller, Iris; Çalışkan, Gürsel; Stork, Oliver

    2015-01-01

    The γ-amino butyric acid (GABA) synthetic enzyme glutamic acid decarboxylase (GAD)65 is critically involved in the activity-dependent regulation of GABAergic inhibition in the central nervous system. It is also required for the maturation of the GABAergic system during adolescence, a phase that is critical for the development of several neuropsychiatric diseases. Mice bearing a null mutation of the GAD65 gene develop hyperexcitability of the amygdala and hippocampus, and a phenotype of increased anxiety and pathological fear memory reminiscent of posttraumatic stress disorder. Although genetic association of GAD65 in human has not yet been reported, these findings are in line with observations of reduced GABAergic function in these brain regions of anxiety disorder patients. The particular value of GAD65(-/-) mice thus lies in modeling the effects of reduced GABAergic function in the mature nervous system. The expression of GAD65 and a second GAD isozyme, GAD67, are differentially regulated in response to stress in limbic brain areas suggesting that by controlling GABAergic inhibition these enzymes determine the vulnerability for the development of pathological anxiety and other stress-induced phenotypes. In fact, we could recently show that GAD65 haplodeficiency, which results in delayed postnatal increase of GABA levels, provides resilience to juvenile-stress-induced anxiety to GAD65(+/-) mice thus foiling the increased fear and anxiety in homozygous GAD65(-/-) mice. PMID:25470336

  2. Neuroprotective effects of syringic acid against OGD/R-induced injury in cultured hippocampal neuronal cells.

    PubMed

    Cao, Yidong; Zhang, Liang; Sun, Shukai; Yi, Zhenheng; Jiang, Xue; Jia, Dong

    2016-08-01

    Cerebral ischemic injury and treatment are important topics in neurological science. In the present study, an in vitro model of cerebral ischemia was established by subjecting primary cultures of hippocampal neuronal cells to oxygen-glucose deprivation followed by reperfusion (OGD/R), in order to evaluate the possible neuroprotective role of syringic acid (SA). The results of 3-(4,5-dimethylthiazol‑2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays showed that pre-treatment with SA (0.1, 1, 10, and 20 µM) attenuated OGD/R-induced neuronal injury in a dose-dependent manner, with evidence of increased cell viability and decreased LDH leakage. In addition, oxidative stress markers were evaluated using commercial kits, and the results demonstrated that OGD/R exposure induced distinct oxidative stress, accompanied by elevated levels of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) production, and reduced activity of the antioxidant enzyme superoxide dismutase (SOD), which were dose-dependently restored by pre-treatment with SA. In addition, the concentration of intracellular free calcium [Ca2+]i and mitochondrial membrane potential (MMP or Δψm) were determined in order to evaluate the degree of neuronal damage by performing flow cytometric analysis and observing the cells under a fluorescence microscope, respectively. We demonstrated that pre-treatment with SA inhibited elevations in [Ca2+]i, whereas it increased the MMP dose-dependently following exposure to OGD/R. Western blot analysis revealed that OGD/R promoted cell apoptosis with concomitant increases in Bax and caspase-3 expression, and reduced Bcl-2 expression, which was reversed by pre‑treatment with SA in a dose-dependent manner. Moreover, these effects were mediated through the JNK and p38 pathways, as pre‑treatment with SA inhibited the OGD/R-induced increase in phosphorylated (p-)JNK and p-p38 expression. Taken together, these

  3. Delayed translocation of NGFI-B/RXR in glutamate stimulated neurons allows late protection by 9-cis retinoic acid

    SciTech Connect

    Mathisen, Gro H.; Fallgren, Asa B.; Strom, Bjorn O.; Boldingh Debernard, Karen A.; Mohebi, Beata U.; Paulsen, Ragnhild E.

    2011-10-14

    Highlights: {yields} NGFI-B and RXR translocate out of the nucleus after glutamate treatment. {yields} Arresting NGFI-B/RXR in the nucleus protects neurons from excitotoxicity. {yields} Late protection by 9-cis RA is possible due to a delayed translocation of NGFI-B/RXR. -- Abstract: Nuclear receptor and apoptosis inducer NGFI-B translocates out of the nucleus as a heterodimer with RXR in response to different apoptosis stimuli, and therefore represents a potential pharmacological target. We found that the cytosolic levels of NGFI-B and RXR{alpha} were increased in cultures of cerebellar granule neurons 2 h after treatment with glutamate (excitatory neurotransmitter in the brain, involved in stroke). To find a time-window for potential intervention the neurons were transfected with gfp-tagged expressor plasmids for NGFI-B and RXR. The default localization of NGFI-Bgfp and RXRgfp was nuclear, however, translocation out of the nucleus was observed 2-3 h after glutamate treatment. We therefore hypothesized that the time-window between treatment and translocation would allow late protection against neuronal death. The RXR ligand 9-cis retinoic acid was used to arrest NGFI-B and RXR in the nucleus. Addition of 9-cis retinoic acid 1 h after treatment with glutamate reduced the cytosolic translocation of NGFI-B and RXR{alpha}, the cytosolic translocation of NGFI-Bgfp observed in live neurons, as well as the neuronal death. However, the reduced translocation and the reduced cell death were not observed when 9-cis retinoic acid was added after 3 h. Thus, late protection from glutamate induced death by addition of 9-cis retinoic acid is possible in a time-window after apoptosis induction.