The Experts below are selected from a list of 5193 Experts worldwide ranked by ideXlab platform
Jian Fei - One of the best experts on this subject based on the ideXlab platform.
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GABA Transporter 1 deficiency confers schizophrenia like behavioral phenotypes
PLOS ONE, 2013Co-Authors: Jian Fei, You Qing Cai, Qi Fang, Zhong Chen, Xian Xiao, Yi Zhi Wang, Hui Cao, Neng GongAbstract:The mechanism underlying the pathogenesis of schizophrenia remains poorly understood. The hyper-dopamine and hypo-NMDA receptor hypotheses have been the most enduring ideas. Recently, emerging evidence implicates alterations of the major inhibitory system, GABAergic neurotransmission in the schizophrenic patients. However, the pathophysiological role of GABAergic system in schizophrenia still remains dubious. In this study, we took advantage of GABA Transporter 1 (GAT1) knockout (KO) mouse, a unique animal model with elevated ambient GABA, to study the schizophrenia-related behavioral abnormalities. We found that GAT1 KO mice displayed multiple behavioral abnormalities related to schizophrenic positive, negative and cognitive symptoms. Moreover, GAT1 deficiency did not change the striatal dopamine levels, but significantly enhanced the tonic GABA currents in prefrontal cortex. The GABAA receptor antagonist picrotoxin could effectively ameliorate several behavioral defects of GAT1 KO mice. These results identified a novel function of GAT1, and indicated that the elevated ambient GABA contributed critically to the pathogenesis of schizophrenia. Furthermore, several commonly used antipsychotic drugs were effective in treating the locomotor hyperactivity in GAT1 KO mice, suggesting the utility of GAT1 KO mice as an alternative animal model for studying schizophrenia pathogenesis and developing new antipsychotic drugs.
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GABA Transporter 1 activity modulates hippocampal theta oscillation and theta burst stimulation induced long term potentiation
The Journal of Neuroscience, 2009Co-Authors: Neng Gong, Guo Qiang Cai, Rui Fang Niu, Qi Fang, Zhong Chen, Long Nian Lin, Jian FeiAbstract:The network oscillation and synaptic plasticity are known to be regulated by GABAergic inhibition, but how they are affected by changes in the GABA Transporter activity remains unclear. Here we show that in the CA1 region of mouse hippocampus, pharmacological blockade or genetic deletion of GABA Transporter-1 (GAT1) specifically impaired long-term potentiation (LTP) induced by theta burst stimulation, but had no effect on LTP induced by high-frequency stimulation or long-term depression induced by low-frequency stimulation. The extent of LTP impairment depended on the precise burst frequency, with significant impairment at 3-7 Hz that correlated with the time course of elevated GABAergic inhibition caused by GAT1 disruption. Furthermore, in vivo electrophysiological recordings showed that GAT1 gene deletion reduced the frequency of hippocampal theta oscillation. Moreover, behavioral studies showed that GAT1 knock-out mice also exhibited impaired hippocampus-dependent learning and memory. Together, these results have highlighted the important link between GABAergic inhibition and hippocampal theta oscillation, both of which are critical for synaptic plasticity and learning behaviors.
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Hypoalgesia in mice lacking GABA Transporter subtype 1.
Journal of neuroscience research, 2008Co-Authors: You Qing Cai, Zhe Jing Sheng, Zhugang Wang, Jie Jiang, Guo Qiang Cai, Jian FeiAbstract:g-Aminobutyric acid (GABA) Transporters play a key role in the regulation of GABA neurotransmission. We reported previously that overexpression of the GABA Transporter subtype 1 (GAT1), the major form of the GABA Transporter in the CNS, led to hyperalgesia in mice. In the present study, nociceptive responses of GAT1-knockout mice (GAT1 2/2 ) were compared with those of heterozygous (GAT 1/2 ) and wild-type (GAT 1/1 ) mice by four conventional pain models (tail-immersion test, hot-plate test, acetic acid–induced abdominal constriction test, and formalin test). In addition, the analgesic effects of two GAT1-selective inhibitors, NO711 and tiagabine, were examined in all three genotypes using the same four models. Our data demonstrated that GAT1 deficiency because of genetic knockout or acute blockade by selective inhibitors leads to hypoalgesia in mice. These results confirmed the crucial role of GAT1 in the regulation of nociceptive threshold and suggested that GAT1 inhibitors have the potential for clinical use in pain therapy. V C 2007 Wiley-Liss, Inc.
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reduced anxiety and depression like behaviors in mice lacking GABA Transporter subtype 1
Neuropsychopharmacology, 2007Co-Authors: Guoxiang Liu, Zhugang Wang, Jie Jiang, Lihe Guo, Jian Fei, You Qing Cai, Guo Qiang Cai, Zhe Jin Sheng, Zhengtong MeiAbstract:gamma-Aminobutyric acid (GABA) Transporter subtype 1 (GAT1), which transports extracellular GABA into presynaptic neurons, plays an important regulatory role in the function of GABAergic systems. However, the contributions of the GAT1 in regulating mental status are not fully understood. In this paper, we observed the behavioral alterations of GAT1 knockout (GAT1(-/-)) mice using several depression- and anxiety-related models (eg, the forced-swimming test and the tail-suspension test for testing depression- related behaviors; the open-field test, the dark-light exploration test, the emergence test, and the elevated plus maze (EPM) test for anxiety-related behaviors). Here we found that GAT1(-/-) mice showed a lower level of depression- and anxiety-like behaviors in comparison to wild-type mice. Furthermore, GAT1(-/-) mice exhibited measurable insensitivity to selected antidepressants and anxiolytics such as fluoxetine, amitriptyline, buspirone, diazepam, and tiagabine in the tail- suspension test and/or the EPM test. Moreover, the basal level of corticosterone was found to be significantly lower in GAT1(-/-) mice. These results showed that the absence of GAT1 affects mental status through enhancing the GABAergic system, as well as modifying the serotonergic system and the hypothalamic-pituitary-adrenal (HPA) activity in mice.
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the role of n glycosylation in the stability trafficking and GABA uptake of GABA Transporter 1 terminal n glycans facilitate efficient GABA uptake activity of the GABA Transporter
FEBS Journal, 2005Co-Authors: Guo Qiang Cai, Jian Fei, Werner Reutter, Wolfgang Schwarz, Petrus S Salonikidis, Ralf Schulein, Hua FanAbstract:Neurotransmitter Transporters play a major role in achieving low concentrations of their respective transmitter in the synaptic cleft. The GABA Transporter GAT1 belongs to the family of Na(+)- and Cl(-)-coupled transport proteins which possess 12 putative transmembrane domains and three N-glycosylation sites in the extracellular loop between transmembrane domain 3 and 4. To study the significance of N-glycosylation, green fluorescence protein (GFP)-tagged wild type GAT1 (NNN) and N-glycosylation defective mutants (DDQ, DGN, DDN and DDG) were expressed in CHO cells. Compared with the wild type, all N-glycosylation mutants showed strongly reduced protein stability and trafficking to the plasma membrane, which however were not affected by 1-deoxymannojirimycin (dMM). This indicates that N-glycosylation, but not terminal trimming of the N-glycans is involved in the attainment of a correctly folded and stable conformation of GAT1. All N-glycosylation mutants were expressed on the plasma membrane, but they displayed markedly reduced GABA-uptake activity. Also, inhibition of oligosaccharide processing by dMM led to reduction of this activity. Further experiments showed that both N-glycosylation mutations and dMM reduced the V(max) value, while not increasing the K(m) value for GABA uptake. Electrical measurements revealed that the reduced transport activity can be partially attributed to a reduced apparent affinity for extracellular Na+ and slowed kinetics of the transport cycle. This indicates that N-glycans, in particular their terminal trimming, are important for the GABA-uptake activity of GAT1. They play a regulatory role in the GABA translocation by affecting the affinity and the reaction steps associated with the sodium ion binding.
Petrine Wellendorph - One of the best experts on this subject based on the ideXlab platform.
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Pharmacological Characterization of a Betaine/GABA Transporter 1 (BGT1) Inhibitor Displaying an Unusual Biphasic Inhibition Profile and Anti-seizure Effects
Neurochemical Research, 2020Co-Authors: Stefanie Kickinger, Arne Schousboe, H. Steve White, Gerhard F Ecker, Jonas Skovgaard-petersen, Rasmus P. Clausen, Petrine WellendorphAbstract:Focal epileptic seizures can in some patients be managed by inhibiting γ-aminobutyric acid (GABA) uptake via the GABA Transporter 1 (GAT1) using tiagabine (Gabitril®). Synergistic anti-seizure effects achieved by inhibition of both GAT1 and the betaine/GABA Transporter (BGT1) by tiagabine and EF1502, compared to tiagabine alone, suggest BGT1 as a target in epilepsy. Yet, selective BGT1 inhibitors are needed for validation of this hypothesis. In that search, a series of BGT1 inhibitors typified by (1 R ,2 S )-2-((4,4-bis(3-methylthiophen-2-yl)but-3-en-yl)(methyl)amino)cyclohexanecarboxylic acid (SBV2-114) was developed. A thorough pharmacological characterization of SBV2-114 using a cell-based [^3H]GABA uptake assay at heterologously expressed BGT1, revealed an elusive biphasic inhibition profile with two IC_50 values (4.7 and 556 μM). The biphasic profile was common for this structural class of compounds, including EF1502, and was confirmed in the MDCK II cell line endogenously expressing BGT1. The possibility of two binding sites for SBV2-114 at BGT1 was assessed by computational docking studies and examined by mutational studies. These investigations confirmed that the conserved residue Q299 in BGT1 is involved in, but not solely responsible for the biphasic inhibition profile of SBV2-114. Animal studies revealed anti-seizure effects of SBV2-114 in two mouse models, supporting a function of BGT1 in epilepsy. However, as SBV2-114 is apparent to be rather non-selective for BGT1, the translational relevance of this observation is unknown. Nevertheless, SBV2-114 constitutes a valuable tool compound to study the molecular mechanism of an emerging biphasic profile of BGT1-mediated GABA transport and the putative involvement of two binding sites for this class of compounds.
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pharmacological characterization of a betaine GABA Transporter 1 bgt1 inhibitor displaying an unusual biphasic inhibition profile and anti seizure effects
Neurochemical Research, 2020Co-Authors: Maria E K Lie, Arne Schousboe, Gerhard F Ecker, Stefanie Kickinger, Rasmus P. Clausen, Jonas Skovgaardpetersen, Steve H White, Petrine WellendorphAbstract:Focal epileptic seizures can in some patients be managed by inhibiting γ-aminobutyric acid (GABA) uptake via the GABA Transporter 1 (GAT1) using tiagabine (Gabitril®). Synergistic anti-seizure effects achieved by inhibition of both GAT1 and the betaine/GABA Transporter (BGT1) by tiagabine and EF1502, compared to tiagabine alone, suggest BGT1 as a target in epilepsy. Yet, selective BGT1 inhibitors are needed for validation of this hypothesis. In that search, a series of BGT1 inhibitors typified by (1R,2S)-2-((4,4-bis(3-methylthiophen-2-yl)but-3-en-yl)(methyl)amino)cyclohexanecarboxylic acid (SBV2-114) was developed. A thorough pharmacological characterization of SBV2-114 using a cell-based [3H]GABA uptake assay at heterologously expressed BGT1, revealed an elusive biphasic inhibition profile with two IC50 values (4.7 and 556 μM). The biphasic profile was common for this structural class of compounds, including EF1502, and was confirmed in the MDCK II cell line endogenously expressing BGT1. The possibility of two binding sites for SBV2-114 at BGT1 was assessed by computational docking studies and examined by mutational studies. These investigations confirmed that the conserved residue Q299 in BGT1 is involved in, but not solely responsible for the biphasic inhibition profile of SBV2-114. Animal studies revealed anti-seizure effects of SBV2-114 in two mouse models, supporting a function of BGT1 in epilepsy. However, as SBV2-114 is apparent to be rather non-selective for BGT1, the translational relevance of this observation is unknown. Nevertheless, SBV2-114 constitutes a valuable tool compound to study the molecular mechanism of an emerging biphasic profile of BGT1-mediated GABA transport and the putative involvement of two binding sites for this class of compounds.
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structural and molecular aspects of betaine GABA Transporter 1 bgt1 and its relation to brain function
Neuropharmacology, 2019Co-Authors: Stefanie Kickinger, Arne Schousboe, Gerhard F Ecker, Eva Hellsberg, Bente Frolund, Petrine WellendorphAbstract:ɣ-aminobutyric-acid (GABA) functions as the principal inhibitory neurotransmitter in the central nervous system. Imbalances in GABAergic neurotransmission are involved in the pathophysiology of various neurological diseases such as epilepsy, Alzheimer's disease and stroke. GABA Transporters (GATs) facilitate the termination of GABAergic signaling by transporting GABA together with sodium and chloride from the synaptic cleft into presynaptic neurons and surrounding glial cells. Four different GATs have been identified that all belong to the solute carrier 6 (SLC6) Transporter family: GAT1-3 (SLC6A1, SLC6A13, SLC6A11) and betaine/GABA Transporter 1 (BGT1, SLC6A12). BGT1 has emerged as an interesting target for treating epilepsy due to animal studies that reported anticonvulsant effects for the GAT1/BGT1 selective inhibitor EF1502 and the BGT1 selective inhibitor RPC-425. However, the precise involvement of BGT1 in epilepsy remains elusive because of its controversial expression levels in the brain and the lack of highly selective and potent tool compounds. This review gathers the current structural and functional knowledge on BGT1 with emphasis on brain relevance, discusses all available compounds, and tries to shed light on the molecular determinants driving BGT1 selectivity. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
Arne Schousboe - One of the best experts on this subject based on the ideXlab platform.
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Pharmacological Characterization of a Betaine/GABA Transporter 1 (BGT1) Inhibitor Displaying an Unusual Biphasic Inhibition Profile and Anti-seizure Effects
Neurochemical Research, 2020Co-Authors: Stefanie Kickinger, Arne Schousboe, H. Steve White, Gerhard F Ecker, Jonas Skovgaard-petersen, Rasmus P. Clausen, Petrine WellendorphAbstract:Focal epileptic seizures can in some patients be managed by inhibiting γ-aminobutyric acid (GABA) uptake via the GABA Transporter 1 (GAT1) using tiagabine (Gabitril®). Synergistic anti-seizure effects achieved by inhibition of both GAT1 and the betaine/GABA Transporter (BGT1) by tiagabine and EF1502, compared to tiagabine alone, suggest BGT1 as a target in epilepsy. Yet, selective BGT1 inhibitors are needed for validation of this hypothesis. In that search, a series of BGT1 inhibitors typified by (1 R ,2 S )-2-((4,4-bis(3-methylthiophen-2-yl)but-3-en-yl)(methyl)amino)cyclohexanecarboxylic acid (SBV2-114) was developed. A thorough pharmacological characterization of SBV2-114 using a cell-based [^3H]GABA uptake assay at heterologously expressed BGT1, revealed an elusive biphasic inhibition profile with two IC_50 values (4.7 and 556 μM). The biphasic profile was common for this structural class of compounds, including EF1502, and was confirmed in the MDCK II cell line endogenously expressing BGT1. The possibility of two binding sites for SBV2-114 at BGT1 was assessed by computational docking studies and examined by mutational studies. These investigations confirmed that the conserved residue Q299 in BGT1 is involved in, but not solely responsible for the biphasic inhibition profile of SBV2-114. Animal studies revealed anti-seizure effects of SBV2-114 in two mouse models, supporting a function of BGT1 in epilepsy. However, as SBV2-114 is apparent to be rather non-selective for BGT1, the translational relevance of this observation is unknown. Nevertheless, SBV2-114 constitutes a valuable tool compound to study the molecular mechanism of an emerging biphasic profile of BGT1-mediated GABA transport and the putative involvement of two binding sites for this class of compounds.
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pharmacological characterization of a betaine GABA Transporter 1 bgt1 inhibitor displaying an unusual biphasic inhibition profile and anti seizure effects
Neurochemical Research, 2020Co-Authors: Maria E K Lie, Arne Schousboe, Gerhard F Ecker, Stefanie Kickinger, Rasmus P. Clausen, Jonas Skovgaardpetersen, Steve H White, Petrine WellendorphAbstract:Focal epileptic seizures can in some patients be managed by inhibiting γ-aminobutyric acid (GABA) uptake via the GABA Transporter 1 (GAT1) using tiagabine (Gabitril®). Synergistic anti-seizure effects achieved by inhibition of both GAT1 and the betaine/GABA Transporter (BGT1) by tiagabine and EF1502, compared to tiagabine alone, suggest BGT1 as a target in epilepsy. Yet, selective BGT1 inhibitors are needed for validation of this hypothesis. In that search, a series of BGT1 inhibitors typified by (1R,2S)-2-((4,4-bis(3-methylthiophen-2-yl)but-3-en-yl)(methyl)amino)cyclohexanecarboxylic acid (SBV2-114) was developed. A thorough pharmacological characterization of SBV2-114 using a cell-based [3H]GABA uptake assay at heterologously expressed BGT1, revealed an elusive biphasic inhibition profile with two IC50 values (4.7 and 556 μM). The biphasic profile was common for this structural class of compounds, including EF1502, and was confirmed in the MDCK II cell line endogenously expressing BGT1. The possibility of two binding sites for SBV2-114 at BGT1 was assessed by computational docking studies and examined by mutational studies. These investigations confirmed that the conserved residue Q299 in BGT1 is involved in, but not solely responsible for the biphasic inhibition profile of SBV2-114. Animal studies revealed anti-seizure effects of SBV2-114 in two mouse models, supporting a function of BGT1 in epilepsy. However, as SBV2-114 is apparent to be rather non-selective for BGT1, the translational relevance of this observation is unknown. Nevertheless, SBV2-114 constitutes a valuable tool compound to study the molecular mechanism of an emerging biphasic profile of BGT1-mediated GABA transport and the putative involvement of two binding sites for this class of compounds.
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structural and molecular aspects of betaine GABA Transporter 1 bgt1 and its relation to brain function
Neuropharmacology, 2019Co-Authors: Stefanie Kickinger, Arne Schousboe, Gerhard F Ecker, Eva Hellsberg, Bente Frolund, Petrine WellendorphAbstract:ɣ-aminobutyric-acid (GABA) functions as the principal inhibitory neurotransmitter in the central nervous system. Imbalances in GABAergic neurotransmission are involved in the pathophysiology of various neurological diseases such as epilepsy, Alzheimer's disease and stroke. GABA Transporters (GATs) facilitate the termination of GABAergic signaling by transporting GABA together with sodium and chloride from the synaptic cleft into presynaptic neurons and surrounding glial cells. Four different GATs have been identified that all belong to the solute carrier 6 (SLC6) Transporter family: GAT1-3 (SLC6A1, SLC6A13, SLC6A11) and betaine/GABA Transporter 1 (BGT1, SLC6A12). BGT1 has emerged as an interesting target for treating epilepsy due to animal studies that reported anticonvulsant effects for the GAT1/BGT1 selective inhibitor EF1502 and the BGT1 selective inhibitor RPC-425. However, the precise involvement of BGT1 in epilepsy remains elusive because of its controversial expression levels in the brain and the lack of highly selective and potent tool compounds. This review gathers the current structural and functional knowledge on BGT1 with emphasis on brain relevance, discusses all available compounds, and tries to shed light on the molecular determinants driving BGT1 selectivity. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Hippocampal betaine/GABA Transporter mRNA expression is not regulated by inflammation or dehydration post-status epilepticus.
Journal of neurochemistry, 2011Co-Authors: Nicole M. Rowley, Misty D. Smith, John G. Lamb, Arne Schousboe, H. Steve WhiteAbstract:Seizure activity can alter GABA Transporter and osmoprotective gene expression, which may be involved in the pathogenesis of epilepsy. However, the response of the betaine/GABA Transporter (BGT1) is unknown. The goal of the present study was to compare the expression of BGT1 mRNA to that of other osmoprotective genes and GABA Transporters following status epilepticus (SE). The possible contributory role of dehydration and inflammation was also investigated because both have been shown to be involved in the regulation of GABA Transporter and/or osmoprotective gene expression. BGT1 mRNA was increased 24 h post-SE, as were osmoprotective genes. BGT1 was decreased 72 h and 4 weeks post-SE, as were the GABA Transporter mRNAs. The mRNA values for osmoprotective genes following 24-h water withdrawal were significantly lower than the values obtained 24 h post-SE despite similarities in their plasma osmolality values. BGT1 mRNA was not altered by lipopolysaccharide-induced inflammation while the transcription factor tonicity-responsive enhancer binding protein and the GABA Transporters 1 and 3 were. These results suggest that neither plasma osmolality nor inflammation fully account for the changes seen in BGT1 mRNA expression post-SE. However, it is evident that BGT1 mRNA expression is altered by SE and displays a temporal pattern with similarities to both GABA and osmolyte Transporters. Further investigation of BGT1 regulation in the brain is warranted.
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Role of the betaine/GABA Transporter (BGT-1/GAT2) for the control of epilepsy.
European Journal of Pharmacology, 2004Co-Authors: Arne Schousboe, Orla M. Larsson, Alan Sarup, H. Steve WhiteAbstract:Inactivation of gamma-aminobutric acid (GABA) as a neurotransmitter is mediated by diffusion in the synaptic cleft followed by binding to Transporter sites and translocation into the intracellular compartment. The GABA Transporters of which four subtypes have been cloned (GAT1-4) are distributed at presynaptic nerve endings as well as extrasynaptically on astrocytic and neuronal elements. This anatomical arrangement of the Transporters appears to be of critical functional importance for the maintenance of GABAergic neurotransmission. Pharmacological characterization of the GABA Transporters using a large number of GABA analogs having restricted conformation and lipophilic character has been of instrumental importance for elucidation of the functional importance of the different Transporters. One such analog EF1502 (N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]-3-hydroxy-4-methylamino-4,5,6,7-tetrahydrobenzo[d]isoxazol-3-ol) has been shown to selectively inhibit GAT1 (GABA Transporter 1) and GAT2/BGT-1 (betaine/GABA Transporter). Moreover, this GABA analog exhibits an unusually high efficiency as an anticonvulsant suggesting a novel role of the betaine/GABA Transporter in epileptic seizure control. It is hypothesized that extrasynaptic actions of GABA may be involved in this phenomenon.
Guo Qiang Cai - One of the best experts on this subject based on the ideXlab platform.
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GABA Transporter 1 activity modulates hippocampal theta oscillation and theta burst stimulation induced long term potentiation
The Journal of Neuroscience, 2009Co-Authors: Neng Gong, Guo Qiang Cai, Rui Fang Niu, Qi Fang, Zhong Chen, Long Nian Lin, Jian FeiAbstract:The network oscillation and synaptic plasticity are known to be regulated by GABAergic inhibition, but how they are affected by changes in the GABA Transporter activity remains unclear. Here we show that in the CA1 region of mouse hippocampus, pharmacological blockade or genetic deletion of GABA Transporter-1 (GAT1) specifically impaired long-term potentiation (LTP) induced by theta burst stimulation, but had no effect on LTP induced by high-frequency stimulation or long-term depression induced by low-frequency stimulation. The extent of LTP impairment depended on the precise burst frequency, with significant impairment at 3-7 Hz that correlated with the time course of elevated GABAergic inhibition caused by GAT1 disruption. Furthermore, in vivo electrophysiological recordings showed that GAT1 gene deletion reduced the frequency of hippocampal theta oscillation. Moreover, behavioral studies showed that GAT1 knock-out mice also exhibited impaired hippocampus-dependent learning and memory. Together, these results have highlighted the important link between GABAergic inhibition and hippocampal theta oscillation, both of which are critical for synaptic plasticity and learning behaviors.
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Hypoalgesia in mice lacking GABA Transporter subtype 1.
Journal of neuroscience research, 2008Co-Authors: You Qing Cai, Zhe Jing Sheng, Zhugang Wang, Jie Jiang, Guo Qiang Cai, Jian FeiAbstract:g-Aminobutyric acid (GABA) Transporters play a key role in the regulation of GABA neurotransmission. We reported previously that overexpression of the GABA Transporter subtype 1 (GAT1), the major form of the GABA Transporter in the CNS, led to hyperalgesia in mice. In the present study, nociceptive responses of GAT1-knockout mice (GAT1 2/2 ) were compared with those of heterozygous (GAT 1/2 ) and wild-type (GAT 1/1 ) mice by four conventional pain models (tail-immersion test, hot-plate test, acetic acid–induced abdominal constriction test, and formalin test). In addition, the analgesic effects of two GAT1-selective inhibitors, NO711 and tiagabine, were examined in all three genotypes using the same four models. Our data demonstrated that GAT1 deficiency because of genetic knockout or acute blockade by selective inhibitors leads to hypoalgesia in mice. These results confirmed the crucial role of GAT1 in the regulation of nociceptive threshold and suggested that GAT1 inhibitors have the potential for clinical use in pain therapy. V C 2007 Wiley-Liss, Inc.
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reduced anxiety and depression like behaviors in mice lacking GABA Transporter subtype 1
Neuropsychopharmacology, 2007Co-Authors: Guoxiang Liu, Zhugang Wang, Jie Jiang, Lihe Guo, Jian Fei, You Qing Cai, Guo Qiang Cai, Zhe Jin Sheng, Zhengtong MeiAbstract:gamma-Aminobutyric acid (GABA) Transporter subtype 1 (GAT1), which transports extracellular GABA into presynaptic neurons, plays an important regulatory role in the function of GABAergic systems. However, the contributions of the GAT1 in regulating mental status are not fully understood. In this paper, we observed the behavioral alterations of GAT1 knockout (GAT1(-/-)) mice using several depression- and anxiety-related models (eg, the forced-swimming test and the tail-suspension test for testing depression- related behaviors; the open-field test, the dark-light exploration test, the emergence test, and the elevated plus maze (EPM) test for anxiety-related behaviors). Here we found that GAT1(-/-) mice showed a lower level of depression- and anxiety-like behaviors in comparison to wild-type mice. Furthermore, GAT1(-/-) mice exhibited measurable insensitivity to selected antidepressants and anxiolytics such as fluoxetine, amitriptyline, buspirone, diazepam, and tiagabine in the tail- suspension test and/or the EPM test. Moreover, the basal level of corticosterone was found to be significantly lower in GAT1(-/-) mice. These results showed that the absence of GAT1 affects mental status through enhancing the GABAergic system, as well as modifying the serotonergic system and the hypothalamic-pituitary-adrenal (HPA) activity in mice.
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mice with genetically altered GABA Transporter subtype i gat1 expression show altered behavioral responses to ethanol
Journal of Neuroscience Research, 2006Co-Authors: You Qing Cai, Guo Qiang Cai, Guoxiang Liu, Zhe Jin Sheng, Qing Cai, Jia Hao Shi, Jun Shi, Sun Kai, Xia Sun, Zhen Tong MeiAbstract:It is widely accepted that the GABAergic system plays an important role in the action of ethanol in vivo. GABA Transporter subtype 1 (GAT1) constructs high affinity reuptake sites in the CNS and regulates GABAergic transmissions. In this study, mice lacking the GAT1 were developed by homologous recombination. Both hetero- and homozygous GAT1 mutant mice were tested for ethanol, saccharin or quinine consumption, ethanol-conditioned place preference, ethanol-conditioned taste aversion, ethanol-simulated motor activity, and ethanol-induced sedation/hypnosis. The GAT1(-/-) mice showed decreased ethanol aversion and ethanol reward, and insensitivity to both the sedative/hypnotic and the motor stimulant effects of ethanol, along with increased avoidance of quinine preference and consumption. GAT1(+/-) mice showed significantly increased consumption of ethanol and saccharin, however, enhanced the rewarding and preference effect of ethanol, increased avoidance of quinine, and higher sensitivity to the motor stimulant effect of ethanol. These results demonstrate that GAT1, perhaps in a bi-directional way, modulates some behavioral effects of ethanol. The GAT1 mutant mice provided us a very useful model to investigate the mechanisms of ethanol action in vivo.
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the role of n glycosylation in the stability trafficking and GABA uptake of GABA Transporter 1 terminal n glycans facilitate efficient GABA uptake activity of the GABA Transporter
FEBS Journal, 2005Co-Authors: Guo Qiang Cai, Jian Fei, Werner Reutter, Wolfgang Schwarz, Petrus S Salonikidis, Ralf Schulein, Hua FanAbstract:Neurotransmitter Transporters play a major role in achieving low concentrations of their respective transmitter in the synaptic cleft. The GABA Transporter GAT1 belongs to the family of Na(+)- and Cl(-)-coupled transport proteins which possess 12 putative transmembrane domains and three N-glycosylation sites in the extracellular loop between transmembrane domain 3 and 4. To study the significance of N-glycosylation, green fluorescence protein (GFP)-tagged wild type GAT1 (NNN) and N-glycosylation defective mutants (DDQ, DGN, DDN and DDG) were expressed in CHO cells. Compared with the wild type, all N-glycosylation mutants showed strongly reduced protein stability and trafficking to the plasma membrane, which however were not affected by 1-deoxymannojirimycin (dMM). This indicates that N-glycosylation, but not terminal trimming of the N-glycans is involved in the attainment of a correctly folded and stable conformation of GAT1. All N-glycosylation mutants were expressed on the plasma membrane, but they displayed markedly reduced GABA-uptake activity. Also, inhibition of oligosaccharide processing by dMM led to reduction of this activity. Further experiments showed that both N-glycosylation mutations and dMM reduced the V(max) value, while not increasing the K(m) value for GABA uptake. Electrical measurements revealed that the reduced transport activity can be partially attributed to a reduced apparent affinity for extracellular Na+ and slowed kinetics of the transport cycle. This indicates that N-glycans, in particular their terminal trimming, are important for the GABA-uptake activity of GAT1. They play a regulatory role in the GABA translocation by affecting the affinity and the reaction steps associated with the sodium ion binding.
Fiorenzo Conti - One of the best experts on this subject based on the ideXlab platform.
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Clozapine upregulates the expression of the vesicular GABA Transporter (VGAT) in rat frontal cortex.
Molecular psychiatry, 2007Co-Authors: Luca Bragina, Marcello Melone, Giorgia Fattorini, Fiorenzo ContiAbstract:Clozapine upregulates the expression of the vesicular GABA Transporter (VGAT) in rat frontal cortex
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postnatal development of the vesicular GABA Transporter in rat cerebral cortex
Neuroscience, 2003Co-Authors: Andrea Minelli, Robert H. Edwards, Lidia Alonsonanclares, Javier Defelipe, Fiorenzo ContiAbstract:Abstract Light and electron microscopic immunocytochemical techniques and Western blotting were used to investigate the postnatal development of the vesicular GABA Transporter (VGAT) in the rat somatic sensory cortex. VGAT immunoreactivity was low at birth, it increased gradually through the first and second weeks of life and achieved the adult pattern during the third week. At postnatal day (P)0–P5, VGAT immunoreactivity was associated exclusively to fibers and puncta. Electron microscopic studies performed at P5 showed that all identified synaptic contacts formed by VGAT-positive axonal swellings were of the symmetric type and that a substantial proportion of the boutons appeared not to have formed synapses. From P10 onward, labeled puncta were both scattered in the neuropil and in apposition to unstained cellular profiles; VGAT was also expressed in few GABAergic cell bodies. Western blottings at the same postnatal ages revealed a 55-kDa band whose intensity was weak at P0 (17% of adult), it increased constantly until P15 (P2: 35%; P5: 44%; P10: 68%; P15: 97%), and then leveled off. Overall, the present results show that during neocortical development the expression of VGAT slightly precedes the complete maturation of inhibitory synaptogenesis and suggest that it may contribute to the formation of neocortical GABAergic circuitry.
