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Unexpected synthesis of conformationally restricted analogues of gamma-amino butyric acid (GABA): mechanism elucidation by electrospray ionization mass spectrometry.  


From previous results with lower homologues, dehydroiodination of the three alkenyl-beta-enamino esters 3a-c was expected to provide six-membered N-heterocyclic products. The reactions of 3a-c with triethylamine are found to lead, however, to the unexpected stereoselective synthesis of the trisubstituted cyclopentane derivatives 4a-c, as confirmed by IR and NMR spectroscopy. Cyclopentanes 4a-c bear two chiral centers and a gamma-amino ester moiety, and are therefore conformationally restricted analogues of gamma-amino butyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system. Use of electrospray ionization mass (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) allowed the key iminium ion intermediates 5a-c(+), as well as the protonated molecules of both the reactant and final products, [3a-c + H](+) and [4a-c + H](+), to be intercepted and structurally characterized. From these findings a mechanism for this unexpected but synthetically attractive and efficient stereoselective reaction is proposed. PMID:15624912

Ferraz, Helena M C; Pereira, Fernando L C; Gonçalo, Erika R S; Santos, Leonardo S; Eberlin, Marcos N




EPA Science Inventory

The project studies the inhibitory effect of lead on the enzymatic activity of brain glutamic amino acid decarboxylase (GADC). The enzyme is responsible for the catalytic formation of gamma amino butyric acid (GABA) inhibitory neurons which is believed to be involved with the tra...


Gamma-amino butyric acid (GABA) prevents the induction of nicotinic receptor-regulated signaling by chronic ethanol in pancreatic cancer cells and normal duct epithelia  

PubMed Central

Pancreatic cancer has a high mortality rate and alcoholism is a risk factor independent of smoking. We have shown that nicotinic acetylcholine receptors (nAChRs) regulate pancreatic ductal epithelia and pancreatic ductal adenocarcinoma (PDAC) cells in an autocrine fashion by stimulating their production of the stress neurotransmitters noradrenaline and adrenaline that signal through beta-adrenergic receptors (?-ARs). Our current study has investigated the modulation of this autocrine regulatory loop by chronic ethanol and explored the potential prevention of these effects by ?-amino butyric acid (GABA). Using MTT assays, cell migration assays, western blotting, immunoassays, and gene knockdown of individual nAChRs in two PDAC cell lines and in immortalized human pancreatic duct epithelial cells, our data show that treatment for seven days with ethanol induced the protein expression and sensitivity of nAChRs ?3, ?5 and ?7 resulting in increased production of noradrenaline and adrenaline which drive proliferation and migration via cAMP-dependent signaling downstream of ?-ARs. Treatment with GABA prevented all of these responses to chronic ethanol, reducing cell proliferation and migration below base levels in untreated cells. Our findings suggest that alcoholism induces multiple cAMP-dependent PDAC stimulating signaling pathways by up-regulating the protein expression and sensitivity of nAChRs that regulate stress neurotransmitter production. Moreover, our data identify GABA as a promising agent for the prevention of PDAC in individuals at risk due to chronic alcohol consumption. PMID:23213073

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



Ondansetron reverses anti-hypersensitivity from clonidine in rats following peripheral nerve injury: Role of ?-amino butyric acid in ?2-adrenoceptor and 5-HT3 serotonin receptor analgesia  

PubMed Central

Introduction Monoaminergic pathways, impinging an ?2-adrenoceptors and 5-HT3 serotonin receptors, modulate nociceptive transmission, but their mechanisms and interactions after neuropathic injury are unknown. Here we examine these interactions in rodents after nerve injury. Methods Male Sprague-Dawley rats following L5-L6 spinal nerve ligation (SNL) were used for either behavioral testing, in vivo microdialysis for ?-amino butyric acid (GABA) and acetylcholine release, or synaptosome preparation for GABA release. Results Intrathecal administration of the ?2-adrenoceptor agonist (clonidine) and 5-HT3 receptor agonist (chlorophenylbiguanide) reduced hypersensitivity in SNL rats via GABA receptor-mediated mechanisms. Clonidine increased GABA and acetylcholine release in vivo in the spinal cord of SNL rats but not in normal rats. Clonidine-induced spinal GABA release in SNL rats was blocked by ?2-adrenergic and nicotinic cholinergic antagonists. The 5-HT3 receptor antagonist ondansetron decreased and chlorophenylbiguanide increased spinal GABA release in both normal and SNL rats. In synaptosomes from the spinal dorsal horn of SNL rats, pre-synaptic GABA release was increased by nicotinic agonists and decreased by muscarinic and ?2-adrenergic agonists. Spinally administered ondansetron significantly reduced clonidine-induced anti-hypersensitivity and spinal GABA release in SNL rats. Conclusion These results suggest that spinal GABA contributes to anti-hypersensitivity from intrathecal ?2-adrenergic and 5-HT3 receptor agonists in the neuropathic pain state, that cholinergic neuroplasticity after nerve injury is critical for ?2-adrenoceptor-mediated GABA release, and that blockade of spinal 5-HT3 receptors reduces ?2-adrenoceptor-mediated anti-hypersensitivity via reducing total GABA release. PMID:22722575

Hayashida, Ken-ichiro; Kimura, Masafumi; Yoshizumi, Masaru; Hobo, Shotaro; Obata, Hideaki; Eisenach, James C.



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


An isolate from kimchi, identified as Lactobacillus brevis, accumulated ?-aminobutyric acid (GABA), a major inhibitory neurotransmitter, in the culture medium. Optimal culture conditions for growth of L. brevis and production of GABA were 6 % (w/v) l-glutamic acid, 4 % (w/v) maltose, 2 % (w/v) yeast extract, 1 % (w/v) NaCl, 1 % (w/v) CaCl2, 2 g Tween 80/l, and 0.02 mM pyridoxal 5?-phosphate at initial pH 5.25 and 37 °C. GABA reached 44.4 g/l after 72 h cultivation with a conversion rate 99.7 %, based on the amount (6 %) of l-glutamic acid added. GABA was purified using ion exchange column chromatography with 70 % recovery and 97 % purity. PMID:24078124

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



Cardiac sympathetic afferent reflex response to intermedin microinjection into paraventricular nucleus is mediated by nitric oxide and ?-amino butyric acid in hypertensive rats.  


Intermedin (IMD) is a member of calcitonin/calcitonin gene-related peptide (CGRP) and involves in the regulation of cardiovascular function in both peripheral tissues and central nervous system (CNS). Paraventricular nucleus (PVN) of hypothalamus is an important site in the control of cardiac sympathetic afferent reflex (CSAR) which participates in sympathetic over-excitation of hypertension. The aim of this study is to investigate whether IMD in the PVN is involved in the inhibition of CSAR and its related mechanism in hypertension. Rats were subjected to two-kidney one-clip (2K1C) surgery to induce renovascular hypertension or sham-operation (Sham). Acute experiments were carried out four weeks later under anesthesia. The CSAR was evaluated with the renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) responses to the epicardial application of capsaicin. The RSNA and MAP were recorded in sinoaortic-denervated, cervical-vagotomized and anesthetized rats. Bilateral PVN microinjection of IMD (25?pmol) caused greater decrease in the CSAR in 2K1C rats than in Sham rats, which was prevented by pretreatment with adrenomedullin (AM) receptor antagonist AM22-52, non-selective nitric oxide (NO) synthase (NOS) inhibitor L-NAME or ?-amino butyric acid (GABA)B receptor blocker CGP-35348. PVN pretreatment with CGRP receptor antagonist CGRP8-37 or GABA(A) receptor blocker gabazine had no significant effect on the CSAR response to IMD. AM22-52, L-NAME and CGP-35348 in the PVN could increase CSAR in Sham and 2K1C rats. These data indicate that IMD in the PVN inhibits CSAR via AM receptor, and both NO and GABA in the PVN involve in the effect of IMD on CSAR in Sham and renovascular hypertensive rats. PMID:24872434

Zhou, Hong; Sun, Hai-jian; Chang, Jin-rui; Ding, Lei; Gao, Qing; Tang, Chao-shu; Zhu, Guo-qing; Zhou, Ye-bo



LeProT1, a transporter for proline, glycine betaine, and gamma-amino butyric acid in tomato pollen.  

PubMed Central

During maturation, pollen undergoes a period of dehydration accompanied by the accumulation of compatible solutes. Solute import across the pollen plasma membrane, which occurs via proteinaceous transporters, is required to support pollen development and also for subsequent germination and pollen tube growth. Analysis of the free amino acid composition of various tissues in tomato revealed that the proline content in flowers was 60 times higher than in any other organ analyzed. Within the floral organs, proline was confined predominantly to pollen, where it represented >70% of total free amino acids. Uptake experiments demonstrated that mature as well as germinated pollen rapidly take up proline. To identify proline transporters in tomato pollen, we isolated genes homologous to Arabidopsis proline transporters. LeProT1 was specifically expressed both in mature and germinating pollen, as demonstrated by RNA in situ hybridization. Expression in a yeast mutant demonstrated that LeProT1 transports proline and gamma-amino butyric acid with low affinity and glycine betaine with high affinity. Direct uptake and competition studies demonstrate that LeProT1 constitutes a general transporter for compatible solutes. PMID:10072398

Schwacke, R; Grallath, S; Breitkreuz, K E; Stransky, E; Stransky, H; Frommer, W B; Rentsch, D



Mutations in y-aminobutyric acid (GABA) transaminase genes in plants or Pseudomonas syringae reduce bacterial virulence  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pseudomonas syringae pv. tomato DC3000 is a bacterial pathogen of Arabidopsis and tomato that grows in the apoplast. The non-protein amino acid '-amino butyric acid (GABA) is produced by Arabidopsis and tomato and is the most abundant amino acid in the apoplastic fluid of tomato. The DC3000 genome h...


Crystal structure and electrospray mass spectrum of N, N-bis(2,5-dioxopyrrolidin-1-ylmethyl)-?-amino-butyric acid and photochromism of its ternary europium system with 1,10-phenanthroline  

NASA Astrophysics Data System (ADS)

The title compound N, N-bis(2,5-dioxopyrrolidin-1-ylmethyl)-?-amino-butyric acid (DOPMABA) was synthesized through the Mannich reaction of succinimide with ?-amino-butyric acid in the formaldehyde solution. The structure and the fragments of DOPMABA were determined by single crystal X-ray diffraction and electrospray ionization mass spectrometry (ESIMS), respectively. The title compound has two kinds of configurations because of the long chain of ?-amino-butyric acid. The ternary Eu 3+ system with DOPMABA and 1,10-phenanthroline (phen) shows good photochromism in aqueous medium. Its decoloration process was investigated. Based on the decoloration curve, its E-diagram was obtained which displays that the decoloration is an independent step.

Zheng, Xiang-jun; Zhuang, Jin-you; Jin, Lin-pei; Wang, Zhe-ming; Yan, Chun-hua; Zhu, Long-gen; Mei, Yu-hua



Upregulation of genes related to bone formation by ?-amino butyric acid and ?-oryzanol in germinated brown rice is via the activation of GABAB-receptors and reduction of serum IL-6 in rats  

PubMed Central

Background Osteoporosis and other bone degenerative diseases are among the most challenging non-communicable diseases to treat. Previous works relate bone loss due to osteoporosis with oxidative stress generated by free radicals and inflammatory cytokines. Alternative therapy to hormone replacement has been an area of interest to researchers for almost three decades due to hormone therapy-associated side effects. Methods In this study, we investigated the effects of gamma-amino butyric acid (GABA), gamma-oryzanol (ORZ), acylated steryl glucosides (ASG), and phenolic extracts from germinated brown rice (GBR) on the expression of genes related to bone metabolism, such as bone morphogenic protein-2 (BMP-2), secreted protein acidic and rich in cysteine (SPARC), runt-related transcription factor 2 (RUNX-2), osteoblast-specific transcription factor osterix (Osx), periostin, osteoblast specific factor (Postn), collagen 1&2 (Col1&2), calcitonin receptor gene (CGRP); body weight measurement and also serum interleukin-6 (IL-6) and osteocalcin, in serum and bone. Rats were treated with GBR, ORZ, GABA, and ASG at (100 and 200 mg/kg); estrogen (0.2 mg/kg), or remifemin (10 and 20 mg/kg), compared to ovariectomized non-treated group as well as non-ovariectomized non-treated (sham) group. Enzyme-linked immunosorbent assay was used to measure the IL-6 and osteocalcin levels at week 2, 4, and 8, while the gene expression in the bone tissue was determined using the Genetic Analysis System (Beckman Coulter Inc., Brea, CA, USA). Results The results indicate that groups treated with GABA (100 and 200 mg/kg) showed significant upregulation of SPARC, calcitonin receptor, and BMP-2 genes (P < 0.05), while the ORZ-treated group (100 and 200 mg/kg) revealed significant (P < 0.05) upregulation of Osx, Postn, RUNX-2, and Col1&2. Similarly, IL-6 concentration decreased, while osteocalcin levels increased significantly (P < 0.05) in the treated groups as compared to ovariectomized non-treated groups. Conclusion GABA and ORZ from GBR stimulates osteoblastogenesis by upregulation of bone formation genes, possibly via the activation of GABAB receptors and by inhibiting the activity of inflammatory cytokines and reactive oxygen species. Therefore, it could be used effectively in the management of osteoporosis. PMID:24098073

Muhammad, Sani Ismaila; Maznah, Ismail; Mahmud, Rozi; Zuki, Abu Bakar Zakaria; Imam, Mustapha Umar



Accumulation, selection and covariation of amino acids in sieve tube sap of tansy (Tanacetum vulgare) and castor bean (Ricinus communis): evidence for the function of a basic amino acid transporter and the absence of a ?-amino butyric acid transporter.  


Sieve tube sap was obtained from Tanacetum by aphid stylectomy and from Ricinus after apical bud decapitation. The amino acids in sieve tube sap were analyzed and compared with those from leaves. Arginine and lysine accumulated in the sieve tube sap of Tanacetum more than 10-fold compared to the leaf extracts and they were, together with asparagine and serine, preferably selected into the sieve tube sap, whereas glycine, methionine/tryptophan and ?-amino butyric acid were partially or completely excluded. The two basic amino acids also showed a close covariation in sieve tube sap. The acidic amino acids also grouped together, but antagonistic to the other amino acids. The accumulation ratios between sieve tube sap and leaf extracts were smaller in Ricinus than in Tanacetum. Arginine, histidine, lysine and glutamine were enriched and preferentially loaded into the phloem, together with isoleucine and valine. In contrast, glycine and methionine/tryptophan were partially and ?-amino butyric acid almost completely excluded from sieve tube sap. The covariation analysis grouped arginine together with several neutral amino acids. The acidic amino acids were loaded under competition with neutral amino acids. It is concluded from comparison with the substrate specificities of already characterized plant amino acid transporters, that an AtCAT1-like transporter functions in phloem loading of basic amino acids, whereas a transporter like AtGAT1 is absent in phloem. Although Tanacetum and Ricinus have different minor vein architecture, their phloem loading specificities for amino acids are relatively similar. PMID:24446756

Bauer, Susanne N; Nowak, Heike; Keller, Frank; Kallarackal, Jose; Hajirezaei, Mohamad-Reza; Komor, Ewald



GABA as a rising gliotransmitter  

PubMed Central

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

Yoon, Bo-Eun; Lee, C. Justin



Disorders of GABA metabolism: SSADH and GABA-transaminase deficiencies  

PubMed Central

Clinical disorders known to affect inherited gamma-amino butyric acid (GABA) metabolism are autosomal recessively inherited succinic semialdehyde dehydrogenase and GABA-transaminase deficiency. The clinical presentation of succinic semialdehyde dehydrogenase deficiency includes intellectual disability, ataxia, obsessive-compulsive disorder and epilepsy with a nonprogressive course in typical cases, although a progressive form in early childhood as well as deterioration in adulthood with worsening epilepsy are reported. GABA-transaminase deficiency is associated with a severe neonatal-infantile epileptic encephalopathy. PMID:25485164

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



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


Clinical disorders known to affect inherited gamma-amino butyric acid (GABA) metabolism are autosomal recessively inherited succinic semialdehyde dehydrogenase and GABA-transaminase deficiency. The clinical presentation of succinic semialdehyde dehydrogenase deficiency includes intellectual disability, ataxia, obsessive-compulsive disorder and epilepsy with a nonprogressive course in typical cases, although a progressive form in early childhood as well as deterioration in adulthood with worsening epilepsy are reported. GABA-transaminase deficiency is associated with a severe neonatal-infantile epileptic encephalopathy. PMID:25485164

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



Effect of rolipram, a phosphodiesterase enzyme type–4 inhibitor, on ?-amino butyric acid content of the frontal cortex in mice exposed to chronic mild stress  

PubMed Central

Objectives: To investigate the alterations in GABA levels by rolipram in the model of depression. Materials and Methods: The alteration of GABA content by rolipram as a phosphodiesterase enzyme type-4 inhibitor in the frontal cortex (FCx; as a brain region crucial for the control of emotion and cognition) obtained from male mice exposed to chronic mild stress (CMS)-induced anhedonia (the loss of pleasure or lack of sensitivity to pleasure stimuli) was recorded. Results: The results demonstrated the reversal of CMS-induced anhedonia after 3 weeks per os of rolipram in a dose of 0.1 mg/kg/day dissolved in distilled water. Furthermore, rolipram showed a significant reduction in duration of immobility in long-term behavioral changes recorded by the FST. Additionally, there was a significant increase in the GABA content of the FCx of rolipram-treated mice exposed to CMS-induced anhedonia. Conclusions: The present study suggested that GABA levels may be decreased in an animal model of depression and its reversal together with the behaviour improvement by rolipram could support the hypothesis that modification in GABAergic activity has a role in mood disorders. These effects may complement the antidepressant effect of rolipram that is originally mediated via inhibition of phosphodiesterase enzyme type-4 [PDE4] that increases cyclic adenosine monophosphate signalling the pharmacotherapy of depression. PMID:22629087

Shalaby, Amany Mohamed; Kamal, Sahar Mohamed



Distribution of GABA-like immunoreactive neurons in the slug Limax maximus  

Microsoft Academic Search

Immunohistochemical techniques were used to study the distribution of gamma-amino butyric acid (GABA)-like immunoreactive neurons in the nervous system of the slug Limax maximus. Approximately 170 GABA-like immunoreactive cell bodies were found in the central nervous system. These were located in the cerebral, buccal and pedal ganglia. Most GABA-like immunoreactive neurons had small cell bodies, which were aggregated into discrete

Ian R. C. Cooke; Alan Gelperin



Distribution of GABA-like immunoreactive neurons in the slug Limax maximus.  


Immunohistochemical techniques were used to study the distribution of gamma-amino butyric acid (GABA)-like immunoreactive neurons in the nervous system of the slug Limax maximus. Approximately 170 GABA-like immunoreactive cell bodies were found in the central nervous system. These were located in the cerebral, buccal and pedal ganglia. Most GABA-like immunoreactive neurons had small cell bodies, which were aggregated into discrete clusters within the cerebral and pedal ganglia. Three pairs of longer, uniquely identifiable, GABA-like immunoreactive cells were found in the cerebral ganglion. GABA-like immunoreactive nerve fibres were also found in all of the central ganglia but were absent from peripheral nerves. These results suggest that GABA acts as a central neurotransmitter in the slug. The possible roles of GABA-ergic neurotransmission in the slug are discussed. PMID:2458189

Cooke, I R; Gelperin, A



The role of GABA in the regulation of GnRH neurons  

PubMed Central

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

Watanabe, Miho; Fukuda, Atsuo; Nabekura, Junichi



Effects of sea anemone (Heteractis magnifica and Actinia equina) cytolysins on synaptosomal uptake of GABA and choline.  


Magnificalysin I and II (HMg I and II) and equinatoxin II (EqTx II) are cytolytic toxins extracted from sea anemones Heteractis magnifica and Actinia equina, respectively. They induced haemolysis in rat red blood cells and inhibited gamma amino butyric acid (GABA) and choline uptake into rat brain synaptosomes. These effects were concentration dependent. The inhibition of GABA and choline uptake could be overcome by the addition of exogenous sphingomyelin, suggesting that there might be interaction between these cytolysins and the phospholipid. Although the precise mechanisms involved in haemolysis and inhibition of GABA and choline uptake are unknown, they appeared to be different. PMID:8599187

Khoo, H E; Lim, J P; Tan, C H



Production of gaba (? – Aminobutyric acid) by microorganisms: a review  

PubMed Central

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

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



[A new role of GABA on synapses].  


Neurons connect and transmit information via synapses. The major excitatory and inhibitory (E-I) neurotransmitters are glutamate and ?-amino butyric acid (GABA), respectively. The E-I balance plays an important role in various brain functions. In this review, we summarize the role of GABA on synaptic integration and synaptic plasticity by introducing our own recent findings. In synaptic integration, GABA is considered to inhibit depolarization induced by glutamate and suppress action potentials. We found that GABA also has a more direct role on the synaptic plasticity of excitatory inputs. GABA effectively promotes the shrinkage and elimination of synapses by suppressing local dendritic Ca(2+) signaling, while keeping the Ca(2+) domain of the NMDA receptors intact. In this manner, GABA promoted the activation of calcineurin, which in turn activated cofilin. Interestingly, shrinkage tended to spread, likely due to the spread of cofilin, and induced competitive selection of synapses via its phosphorylation and dephosphorylation. The selection of synapses is key to the reorganization of the central nervous system during development and in adulthood, and GABA plays key roles in various mental disorders, such as autism and schizophrenia. Our results account well for the in vivo GABA functions on synaptic selection, and may help to develop new therapeutic compounds. PMID:25082320

Hayama, Tatsuya; Kasai, Haruo



GABA(A) receptor modulators from the Chinese herbal drug Junci Medulla--the pith of Juncus effusus.  


The gamma-amino butyric acid (GABA) type A (GABA(A)) receptor represents a crucial target for clinical agents in the treatment of anxiety and insomnia. Using the two-microelectrode voltage clamp technique on recombinant ?????(2S) GABA (A) receptors, effusol (1) and dehydroeffusol (2) were isolated in a bioactivity-guided approach from the pith of Juncus effusus L. Both compounds concentration-dependently enhanced GABA induced chloride currents (I(GABA)) by a maximum 188 ± 20 (1) and 239 ± 18 % (2), independent of the benzodiazepine (BZ) binding site. This activity on the GABA (A) receptor may explain the traditional use of J. effusus as a sedative and anxiolytic agent in Chinese medicine. PMID:22271080

Singhuber, Judith; Baburin, Igor; Khom, Sophia; Zehl, Martin; Urban, Ernst; Hering, Steffen; Kopp, Brigitte



Fast detection of extrasynaptic GABA with a whole-cell sniffer  

PubMed Central

Gamma-amino-butyric acid (GABA) is the main inhibitory transmitter of the brain. It operates by binding to specific receptors located both inside and outside synapses. The extrasynaptic receptors are activated by spillover from GABAergic synapses and by ambient GABA in the extracellular space. Ambient GABA is essential for adjusting the excitability of neurons. However, due to the lack of suitable methods, little is known about its dynamics. Here we describe a new technique that allows detection of GABA transients and measurement of the steady state GABA concentration with high spatial and temporal resolution. We used a human embryonic kidney (HEK) cell line that stably expresses GABAA receptors composed of ?1, ?2, and ?2 subunits. We recorded from such a HEK cell with the whole-cell patch-clamp technique. The presence of GABA near the HEK cell generated a measurable electric current whose magnitude increased with concentration. A fraction of the current did not inactivate during prolonged exposition to GABA. This technique, which we refer to as a “sniffer” allows the measurement of ambient GABA concentration inside nervous tissue with a resolution of few tens of nanomolars. In addition, the sniffer detects variations in the extrasynaptic GABA concentration with millisecond time resolution. Pilot experiments demonstrate that the sniffer is able to report spillover of GABA induced by synaptic activation in real time. This is the first report on a GABA sensor that combines the ability to detect fast transients and to measure steady concentrations. PMID:24860433

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



Role of GABA and serotonin coupled chitosan nanoparticles in enhanced hepatocyte proliferation.  


The development of nanoparticles containing active molecules having improved stability, sustained release and maximum half life helps in cell proliferation result in enhanced tissue regeneration. Our study focuses on the use of Gamma amino butyric acid (GABA) and serotonin (5-HT) coupled chitosan nanoparticles for the active liver regeneration in male Wistar rats. The nanoparticles were prepared and the morphology was studied using SEM. The FT-IR spectra of the nanoparticles and the maximum encapsulation efficiency of GABA and 5-HT binding to chitosan nanoparticles were observed. The in vitro release studies provided the percentage release of GABA and 5-HT from the nanoparticles at different time intervals. The quantification of DNA and protein syntheses was done using [(3)H] thymidine and [(3)H] leucine uptake studies that determined the enhancement in hepatocyte proliferation. Our results project the role of GABA and 5-HT chitosan nanoparticles in the treatment of liver based diseases. PMID:22960799

Shilpa, J; Roshni, B T; Chinthu, R; Paulose, C S



Role of GABA Receptors in Fetal Lung Development in Rats  

PubMed Central

Fluid accumulation is critical for lung distension and normal development. The multi-subunit ?-amino butyric acid type A receptors (GABAA) mainly act by mediating chloride ion (Cl?) fluxes. Since fetal lung actively secretes Cl?-rich fluid, we investigated the role of GABAA receptors in fetal lung development. The physiological ligand, GABA, and its synthesizing enzyme, glutamic acid decarboxylase, were predominantly localized to saccular epithelium. To examine the effect of activating GABAA receptors in fetal lung development in vivo, timed-pregnant rats of day 18 gestation underwent an in utero surgery for the administration of GABAA receptor modulators into the fetuses. The fetal lungs were isolated on day 21 of gestation and analyzed for changes in fetal lung development. Fetuses injected with GABA had a significantly higher body weight and lung weight when compared to phosphate-buffered saline (control)-injected fetuses. GABA-injected fetal lungs had a higher number of saccules than the control. GABA increased the number of alveolar epithelial type II cells as indicated by surfactant protein C-positive cells. However, GABA decreased the number of ?-smooth muscle actin-positive myofibroblasts, but did not affect the number of Clara cells or alveolar type I cells. GABA-mediated effects were blocked by the GABAA receptor antagonist, bicuculline. GABA also increased cell proliferation and Cl? efflux in fetal distal lung epithelial cells. In conclusion, our results indicate that GABAA receptors accelerate fetal lung development, likely through an enhanced cell proliferation and/or fluid secretion. PMID:21152393

Chintagari, Narendranath Reddy; Jin, Nili; Gao, Li; Wang, Yang; Xi, Dong; Liu, Lin



Effect of ?-Aminobutyric Acid (GABA) Producing Bacteria on In vitro Rumen Fermentation, Biogenic Amine Production and Anti-oxidation Using Corn Meal as Substrate  

PubMed Central

The effects and significance of ?-amino butyric acid (GABA) producing bacteria (GPB) on in vitro rumen fermentation and reduction of biogenic amines (histamine, methylamine, ethylamine, and tyramine) using corn meal as a substrate were determined. Ruminal samples collected from ruminally fistulated Holstein cows served as inoculum and corn was used as substrate at 2% dry matter (DM). Different inclusion rates of GPB and GABA were evaluated. After incubation, addition of GPB had no significant effect on in vitro fermentation pH and total gas production, but significantly increased the ammonia nitrogen (NH3-N) concentration and reduced the total biogenic amines production (p<0.05). Furthermore, antioxidation activity was improved as indicated by the significantly higher concentration of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) among treated samples when compared to the control (p<0.05). Additionally, 0.2% GPB was established as the optimum inclusion level. Taken together, these results suggest the potential of utilizing GPB as feed additives to improve growth performance in ruminants by reducing biogenic amines and increasing anti-oxidation. PMID:25049853

Ku, Bum Seung; Mamuad, Lovelia L.; Kim, Seon-Ho; Jeong, Chang Dae; Soriano, Alvin P.; Lee, Ho-Il; Nam, Ki-Chang; Ha, Jong K.; Lee, Sang Suk



Aminooxyacetic acid induced accumulation of GABA in the rat brain  

Microsoft Academic Search

The effect of aminooxyacetic acid (AOAA, 90 mg\\/kg i.v.) on bicuculline, picrotoxin and 3-mercapto-propionic acid (3-MPA) induced convulsions and on GABA concentrations in cerebellum, whole brain and a synaptosomal fraction of whole brain was investigated. At various intervals after AOAA the rats were either injected with one of the convulsive drugs or sacrificed for analysis of the GABA concentration. AOAA

Sonia R. Pagliusi; Cecilia Gomes; José R. Leite; Gustaf Trolin



A functional role for both ?-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

Tonic ?-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

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



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


Gamma-aminobutyric acid (GABA) is a non-protein amino acid commonly present in all organisms. Because cellular levels of GABA in plants are mainly regulated by synthesis (glutamate decarboxylase, GAD) and catabolism (GABA-transaminase, GABA-T), we attempted seed-specific manipulation of the GABA shunt to achieve stable GABA accumulation in rice. A truncated GAD2 sequence, one of five GAD genes, controlled by the glutelin (GluB-1) or rice embryo globulin promoters (REG) and GABA-T-based trigger sequences in RNA interference (RNAi) cassettes controlled by one of these promoters as well, was introduced into rice (cv. Koshihikari) to establish stable transgenic lines under herbicide selection using pyriminobac. T? and T? generations of rice lines displayed high GABA concentrations (2-100 mg/100 g grain). In analyses of two selected lines from the T? generation, there was a strong correlation between GABA level and the expression of truncated GAD2, whereas the inhibitory effect of GABA-T expression was relatively weak. In these two lines both with two T-DNA copies, their starch, amylose, and protein levels were slightly lower than non-transformed cv. Koshihikari. Free amino acid analysis of mature kernels of these lines demonstrated elevated levels of GABA (75-350 mg/100 g polished rice) and also high levels of several amino acids, such as Ala, Ser, and Val. Because these lines of seeds could sustain their GABA content after harvest (up to 6 months), the strategy in this study could lead to the accumulation GABA and for these to be sustained in the edible parts. PMID:23421475

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



Possible role of GABA-B receptor modulation in MPTP induced Parkinson's disease in rats.  


Accumulating evidence strongly suggests that gamma amino butyric acid (GABA) receptors play a crucial role in the pathogenesis of Parkinson's disease (PD). Therefore, the present study was designed to investigate the role of GABA-B receptor modulation in experimental models of MPTP-induced PD. MPTP was administered repeatedly on 1st, 7th and 14th day intranigrally for the induction of PD in Male Wistar rats. Baclofen (10 and 20mg/kg) and GABA-B antagonist CGP35348 (10mg/kg) were given after induction of PD for 14 days. Different behavioural tasks were performed during 1st, 14th, 21st, 28th days after MPTP injection and biochemical parameters were estimated on day 28th. Central administration of MPTP showed significant impairment of motor behaviour and marked increase of oxidative damage LPO and GSH in striatum and cortex. Pro-inflammatory cytokines like TNF-? and IL-? were significantly increased in striatum region of MPTP treated rats. However, post treatment with baclofen significantly improved the motor abnormalities and attenuated the oxidative damage and neuro-inflammation in MPTP treated rats. CGP35348, GABA-B receptor antagonist, reversed the protective effect of baclofen GABA-B receptor play role in the neuroprotection. The present study concluded that baclofen produce beneficial effect against MPTP induced PD like symptoms rats through GABAergic mechanism. PMID:25547370

Tyagi, Ravi Kant; Bisht, Rohit; Pant, Jatin; Kumar, Puneet; Majeed, Abu Bakar Abdul; Prakash, Atish



Antiepileptic activity of lobeline isolated from the leaf of Lobelia nicotianaefolia and its effect on brain GABA level in mice  

PubMed Central

Objective To investigate the anticonvulsant activity of the lobeline isolated from the Lobelia nicotianaefolia in chemoconvulsant-induced seizures and its biochemical mechanism by investigating relationship between seizure activities and altered gamma amino butyric acid (GABA) in brain of mice in Pentylenetetrazol (PTZ) seizure models. Methods The anticonvulsant activity of the isolated lobeline (5, 10, 20 and 30 mg/kg, i.p.) was investigated in PTZ and strychnine induced seizures in mice and the effect of isolated lobeline on brain GABA level in seizures induced by PTZ. Diazepam was used as reference anticonvulsant drugs for comparison. Results Isolated lobeline (10, 20 and 30 mg/kg, i.p.) significantly delayed and antagonized (P < 0.050–0.001) the onset of PTZ-induced seizures. It also antagonized strychnine induced seizures. The mortality was also prevented in the test group of animals. In biochemical evaluation, isolated lobeline (5, 10 and 20 mg/kg, i.p.) significantly increased the brain GABA level. And at dose of 30 mg/kg GABA level showed slight decrease in PTZ model. Conclusions In our findings, isolated lobeline (20mg/kg) exhibited potent anticonvulsant activity against PTZ induced seizures. Also a biochemical evaluation suggested significant increase in barain GABA level at 20 mg/kg i.p. of isolated lobeline. Hence, we may propose that lobeline reduces epileptic seizures by enhancing the GABA release supporting the GABAergic mechanism. PMID:23569966

Tamboli, Abrar M; Rub, Rukhsana A; Ghosh, Pinaki; Bodhankar, SL



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


The effect of orally administrated gamma-aminobutyric acid (GABA) on relaxation and immunity during stress has been investigated in humans. Two studies were conducted. The first evaluated the effect of GABA intake by 13 subjects on their brain waves. Electroencephalograms (EEG) were obtained after 3 tests on each volunteer as follows: intake only water, GABA, or L-theanine. After 60 minutes of administration, GABA significantly increases alpha waves and decreases beta waves compared to water or L-theanine. These findings denote that GABA not only induces relaxation but also reduces anxiety. The second study was conducted to see the role of relaxant and anxiolytic effects of GABA intake on immunity in stressed volunteers. Eight acrophobic subjects were divided into 2 groups (placebo and GABA). All subjects were crossing a suspended bridge as a stressful stimulus. Immunoglobulin A (IgA) levels in their saliva were monitored during bridge crossing. Placebo group showed marked decrease of their IgA levels, while GABA group showed significantly higher levels. In conclusion, GABA could work effectively as a natural relaxant and its effects could be seen within 1 hour of its administration to induce relaxation and diminish anxiety. Moreover, GABA administration could enhance immunity under stress conditions. PMID:16971751

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



Friedreich Ataxia: Failure of GABA-ergic and Glycinergic Synaptic Transmission in the Dentate Nucleus.  


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 ?-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. PMID:25575136

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



A Fluorescence-Coupled Assay for Gamma Aminobutyric Acid (GABA) Reveals Metabolic Stress-Induced Modulation of GABA Content in Neuroendocrine Cancer  

PubMed Central

Pathways involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA) have been implicated in the pathogenesis of high grade neuroendocrine (NE) neoplasms as well as neoplasms from a non-NE lineage. Using The Cancer Genome Atlas, overexpression of the GABA synthetic enzyme, glutamate decarboxylase 1 (GAD1), was found to be associated with decreased disease free-survival in prostate adenocarcinoma and decreased overall survival in clear cell renal cell carcinomas. Furthermore, GAD1 was found to be expressed in castrate-resistant prostate cancer cell lines, but not androgen-responsive cell lines. Using a novel fluorescence-coupled enzymatic microplate assay for GABA mediated through reduction of resazurin in a prostate neuroendocrine carcinoma (PNEC) cell line, acid microenvironment-induced stress increased GABA levels while alkaline microenvironment-induced stress decreased GABA through modulation of GAD1 and glutamine synthetase (GLUL) activities. Moreover, glutamine but not glucose deprivation decreased GABA through modulation of GLUL. Consistent with evidence in prokaryotic and eukaryotic organisms that GABA synthesis mediated through GAD1 may play a crucial role in surviving stress, GABA may be an important mediator of stress survival in neoplasms. These findings identify GABA synthesis and metabolism as a potentially important pathway for regulating cancer cell stress response as well as a potential target for therapeutic strategies. PMID:24551133

Ippolito, Joseph E.; Piwnica-Worms, David



Pu-Erh tea and GABA attenuates oxidative stress in kainic acid-induced status epilepticus  

PubMed Central

Background Pu-Erh tea is one of the most-consumed beverages due to its taste and the anti-anxiety-producing effect of the gamma-aminobutyric acid (GABA) if contains. However the protective effects of Pu-Erh tea and its constituent, GABA to kainic acid (KA)-induced seizure have not been fully investigated. Methods We analyzed the effect of Pu-Erh tea leaf (PETL) and GABA on KA-induced neuronal injury in vivo and in vitro. Results PETL and GABA reduced the maximal seizure classes, predominant behavioral seizure patterns, and lipid peroxidation in male FVB mice with status epilepticus. PETL extracts and GABA were effective in protecting KA-treated PC12 cells in a dose-dependent manner and they decreased Ca2+ release, ROS production and lipid peroxidation from KA-stressed PC12 cells. Western blot results revealed that mitogen-activated protein kinases (MAPKs), RhoA and cyclo-oxygenase-2 (COX-2) expression were increased in PC12 cells under KA stress, and PETL and GABA significantly reduced COX-2 and p38 MAPK expression, but not that of RhoA. Furthermore, PETL and GABA reduced PGE2 production from KA-induced PC12 cells. Conclusions Taken together, PETL and GABA have neuroprotective effects against excitotoxins that may have clinical applications in epilepsy. PMID:22014163



GABA(B) receptor-mediated activation of astrocytes by gamma-hydroxybutyric acid.  


The gamma-aminobutyric acid (GABA) metabolite gamma-hydroxybutyric acid (GHB) shows a variety of behavioural effects when administered to animals and humans, including reward/addiction properties and absence seizures. At the cellular level, these actions of GHB are mediated by activation of neuronal GABA(B) receptors (GABA(B)Rs) where it acts as a weak agonist. Because astrocytes respond to endogenous and exogenously applied GABA by activation of both GABA(A) and GABA(B)Rs, here we investigated the action of GHB on astrocytes on the ventral tegmental area (VTA) and the ventrobasal (VB) thalamic nucleus, two brain areas involved in the reward and proepileptic action of GHB, respectively, and compared it with that of the potent GABA(B)R agonist baclofen. We found that GHB and baclofen elicited dose-dependent (ED50: 1.6 mM and 1.3 µM, respectively) transient increases in intracellular Ca(2+) in VTA and VB astrocytes of young mice and rats, which were accounted for by activation of their GABA(B)Rs and mediated by Ca(2+) release from intracellular store release. In contrast, prolonged GHB and baclofen exposure caused a reduction in spontaneous astrocyte activity and glutamate release from VTA astrocytes. These findings have key (patho)physiological implications for our understanding of the addictive and proepileptic actions of GHB. PMID:25225100

Gould, Timothy; Chen, Lixin; Emri, Zsuzsa; Pirttimaki, Tiina; Errington, Adam C; Crunelli, Vincenzo; Parri, H Rheinallt



Prefrontal GABA and glutathione imbalance in posttraumatic stress disorder: preliminary findings.  


Although posttraumatic stress disorder (PTSD) is associated with a variety of structural and functional brain changes, the molecular pathophysiological mechanisms underlying these macroscopic alterations are unknown. Recent studies support the existence of an altered excitation-inhibition balance in PTSD. Further, there is preliminary evidence from blood-sample studies suggesting heightened oxidative stress in PTSD, potentially leading to neural damage through excessive brain levels of free radicals. In this study we investigated PTSD (n=12) and non-PTSD participants (n=17) using single-voxel proton magnetic resonance spectroscopy (MRS) in dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC). We found significantly higher levels of ?-amino butyric acid (GABA) (a primary inhibitory neurotransmitter) and glutathione (a marker for neuronal oxidative stress) in PTSD participants. Atypically high prefrontal inhibition as well as oxidative stress may be involved in the pathogenesis of PTSD. PMID:25448399

Michels, Lars; Schulte-Vels, Thomas; Schick, Matthis; O'Gorman, Ruth L; Zeffiro, Thomas; Hasler, Gregor; Mueller-Pfeiffer, Christoph




PubMed Central

The principal sites of ?-aminobutyric acid (GABA) uptake in lobster nerve-muscle preparations have been determined with radioautographic techniques after binding of the amino acid to proteins by aldehyde fixation. Semiquantitative studies showed that about 30% of the radioactive GABA taken into the tissue was bound to protein by fixation. Both light and electron micrographs showed dense accumulations of label over Schwann and connective tissue cell cytoplasm; muscle was lightly labeled, but axons and terminals were almost devoid of label. The possible role of Schwann and connective tissue cells in the inactivation of GABA released from inhibitory axons is discussed. PMID:5555581

Orkand, Paula M.; Kravitz, Edward A.



GABA transport and neuroinflammation are coupled in multiple sclerosis: regulation of the GABA transporter-2 by ganaxolone.  


Interactions between neurotransmitters and the immune system represent new prospects for understanding neuroinflammation and associated neurological disease. GABA is the chief inhibitory neurotransmitter but its actions on immune pathways in the brain are unclear. In the present study, we investigated GABAergic transport in conjunction with neuroinflammation in models of multiple sclerosis (MS). Protein and mRNA levels of ?-amino butyric acid transporter 2 (GAT-2) were examined in cerebral white matter from MS and control (Non-MS) patients, in cultured human macrophages, microglia and astrocytes, and in spinal cords from mice with and without experimental autoimmune encephalomyelitis (EAE) using western blotting, immunocytochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). GABA levels were measured by HPLC. The GAT-2's expression was increased in MS patients' (n=6) white matter, particularly in macrophage lineage cells, compared to Non-MS patients (n=6) (p<0.05). Interferon-? (IFN-?) stimulation of human macrophage lineage cells induced GAT-2 expression and reduced extracellular GABA levels (p<0.05) but soluble GABA treatment suppressed HLA-DR?, GAT-2 and XBP-1/s expression in stimulated macrophage lineage cells (p<0.05). Similarly, the synthetic allopregnanolone analog, ganaxolone (GNX), repressed GAT-2, JAK-1 and STAT-1 expression in activated macrophage lineage cells (p<0.05). In vivo GNX treatment reduced Gat-2, Cd3?, MhcII, and Xbp-1/s expression in spinal cords following EAE induction (p<0.05), which was correlated with improved neurobehavioral outcomes and reduced neuroinflammation, demyelination and axonal injury. These findings highlight altered GABAergic transport through GAT-2 induction during neuroinflammation. GABA transport and neuroinflammation are closely coupled but regulated by GNX, pointing to GABAergic pathways as therapeutic targets in neuroinflammatory diseases. PMID:24814730

Paul, A M; Branton, W G; Walsh, J G; Polyak, M J; Lu, J-Q; Baker, G B; Power, C



??????????????????????- ??????????????????????????????????????????????????????? Accumulation of gamma-aminobutyric acid (GABA) in non-waxy and waxy rice germ during water soaking ????? ?????????? ?????? ??????????? ???? ?????????????? ???????? ????????????  

Microsoft Academic Search

Rice germ contains protein, vitamins, minerals, dietary fiber and gamma- aminobutyric acid (GABA). GABA has been proved to be effective for lowering the blood pressure of human being. It has neurotransmission functions and tranquilizer effects. Determination of GABA in rice germ and brown rice were investigated by using low- amylose, high-amylose and waxy rice cultivars. Percentage of germ weight showed

Patcharee Tungtrakul; Vipa Surojanametakul; Ladda Wattanasiritham


Production of gamma-aminobutyric acid from alcohol distillery lees by Lactobacillus brevis IFO-12005.  


Lactobacillus brevis IFO-12005 showed good growth in rice shochu distillery lees (kome shochu kasu). Almost all of the free glutamic acid (10.50 mM) in shochu kasu was converted to gamma-amino-butyric acid (GABA) within 2 d of stationary culture at 30 degrees C. The amount of GABA in the kome shochu kasu medium finally reached 10.18 mM. After centrifugation of the broth culture, the supernatant fraction was treated with a flocculation agent to form a clear solution, then passed through a column containing a synthetic adsorbents, SP-207 to remove the yellow pigment and flavors which are unnecessary from a sensory perspective. An economical and simple production process for GABA was established. PMID:16233172

Yokoyama, Sadaji; Hiramatsu, Jun-Ichi; Hayakawa, Kiyoshi



GABA(B) receptor-mediated increase of neurosteroids by gamma-hydroxybutyric acid.  


Among the pharmacological actions of gamma-hydroxybutyric acid (GHB), some may involve GABA(A) receptor-mediated mechanisms. GHB, however, fails to directly interact with sites for agonists and modulators on the GABA(A) receptor complex. We hypothesized that, in vivo, GHB may interfere with GABA(A) receptor function by altering the brain concentrations of the neurosteroids 3 alpha-hydroxy-5 alpha-pregnan-20-one (allopregnanolone, AP) and 3 alpha,21-dihydroxy-5 alpha-pregnan-20-one (allotetrahydrodeoxycorticosterone, THDOC), positive allosteric modulators of GABA-gated chloride currents. In male Wistar rats, GHB dose-dependently (75-1000 mg/kg, i.p.) increased AP, THDOC and their precursors pregnenolone and progesterone in brain cortex and hippocampus. The increases of AP (4-5 fold) and THDOC (3-4 fold) elicited by 300 mg/kg GHB peaked between 30 and 90 min and abated by 180 min. The selective GABA(B) receptor antagonist SCH 50911 (50 mg/kg, i.p.) prevented the action of GHB, while the GABA(B) receptor agonist baclofen (5-10 mg/kg) mimicked it. NCS-382 (50 mg/kg, i.p.), the purported selective antagonist of the GHB receptor, failed to antagonize GHB, but at 300 mg/kg increased brain cortical neurosteroids to the same extent as 300 mg/kg GHB; coadministration of GHB and NCS-382, however, failed to yield an additive effect. These results strongly suggest that GHB, via a GABA(B) receptor-mediated mechanism, increases the brain concentrations of neurosteroids, whose properties as amplifiers of the GABA-gated chloride conductances may play a role in the GABA(A) receptor-mediated pharmacological actions of GHB. PMID:12015204

Barbaccia, M L; Colombo, G; Affricano, D; Carai, M A M; Vacca, G; Melis, S; Purdy, R H; Gessa, G L



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

SciTech Connect

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

Keir, W.J.; Deitrich, R.A.; Sikela, J.M. (Univ. of Colorado, Denver (USA))



An arylaminopyridazine derivative of gamma-aminobutyric acid (GABA) is a selective and competitive antagonist at the GABAA receptor site.  

PubMed Central

In view of finding a new gamma-aminobutyric acid (GABA) receptor ligand we synthesized an arylaminopyridazine derivative of GABA, SR 95103 [2-(carboxy-3'-propyl)-3-amino-4-methyl-6-phenylpyridazinium chloride]. SR 95103 displaced [3H]GABA from rat brain membranes with an apparent Ki of 2.2 microM and a Hill number near 1.0. SR 95103 (1-100 microM) antagonized the GABA-mediated enhancement of [3H]diazepam binding in a concentration-dependent manner without affecting [3H]diazepam binding per se. SR 95103 competitively antagonized GABA-induced membrane depolarization in rat spinal ganglia. In all these experiments, the potency of SR 95103 was close to that of bicuculline. SR 95103 (100 microM) did not interact with a variety of central receptors--in particular the GABAB, the strychnine, and the glutamate receptors--did not inhibit Na+-dependent synaptosomal GABA uptake, and did not affect GABA-transaminase and glutamic acid decarboxylase activities. Intraperitoneally administered SR 95103 elicited clonicotonic seizures in mice (ED50 = 180 mg/kg). On the basis of these results it is postulated that St 95103 is a competitive antagonist of GABA at the GABAA receptor site. In addition to being an interesting lead structure for the search of GABA ligands, SR 95103 could also be a useful tool to investigate GABA receptor subtypes because it is freely soluble in water and chemically stable. Images PMID:2984669

Chambon, J P; Feltz, P; Heaulme, M; Restle, S; Schlichter, R; Biziere, K; Wermuth, C G



Gamma-aminobutyric acid, a potential tumor suppressor for small airway-derived lung adenocarcinoma  

PubMed Central

Pulmonary adenocarcinoma (PAC) is the leading type of lung cancer in smokers and non-smokers that arises in most cases from small airway epithelial cells. PAC has a high mortality due to its aggressive behavior and resistance to cancer therapeutics. We have shown previously that the proliferation of human PAC cells NCI-H322 and immortalized human small airway epithelial cells HPL1D is stimulated by cyclic adenosine monophosphate (cAMP)/protein kinase A-dependent phosphorylation of cyclic adenosine monophosphate response element-binding (CREB) protein and transactivation of the epidermal growth factor receptor and that this pathway is activated by beta-1-adrenoreceptors (?1-ARs) and the non-genomic estrogen receptor beta. Our current in vitro studies with HPL1D and NCI-H322 cells showed that signaling via the gamma-amino butyric acid receptor (GABABR) strongly inhibited base level and isoproterenol-induced cAMP, p-CREB, cyclic adenosine monophosphate response element-luciferase activity and p-extracellular regulated kinase-1 (ERK1)/2 and effectively blocked DNA synthesis and cell migration. The inhibitory effects of gamma-amino butyric acid (GABA) were disinhibited by the GABABR antagonist CGP-35348 or GABABR knockdown. Immunohistochemical investigation of hamster lungs showed significant underexpression of GABA in animals with small airway-derived PACs induced by the nicotine-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). These findings suggest that GABA may have tumor suppressor function in small airway epithelia and the PACs derived from them and that downregulation of GABA by NNK may contribute to the development of this cancer in smokers. Our findings suggest that marker-guided treatment with GABA or a GABABR agonist of individuals with downregulated pulmonary GABA may provide a novel targeted approach for the prevention of PAC in smokers. PMID:18310090

Schuller, Hildegard M.; Al-Wadei, Hussein A.N.; Majidi, Mourad



2005 Nature Publishing Group GABA (-aminobutyric acid) is the main inhibitory  

E-print Network

© 2005 Nature Publishing Group GABA (-aminobutyric acid) is the main inhibitory neurotransmitter,this leads to a net inward flow of anions and a hyperpolarizing post- synaptic response -- the inhibitory ON AN INHIBITORY THEME: PHASIC AND TONIC ACTIVATION OF GABAA RECEPTORS Mark Farrant* and Zoltan Nusser Abstract

Sandini, Giulio


Hypocretin/orexin antagonism enhances sleep-related adenosine and GABA neurotransmission in rat basal forebrain.  


Hypocretin/orexin (HCRT) neurons provide excitatory input to wake-promoting brain regions including the basal forebrain (BF). The dual HCRT receptor antagonist almorexant (ALM) decreases waking and increases sleep. We hypothesized that HCRT antagonists induce sleep, in part, through disfacilitation of BF neurons; consequently, ALM should have reduced efficacy in BF-lesioned (BFx) animals. To test this hypothesis, rats were given bilateral IgG-192-saporin injections, which predominantly targets cholinergic BF neurons. BFx and intact rats were then given oral ALM, the benzodiazepine agonist zolpidem (ZOL) or vehicle (VEH) at lights-out. ALM was less effective than ZOL at inducing sleep in BFx rats compared to controls. BF adenosine (ADO), ?-amino-butyric acid (GABA), and glutamate levels were then determined via microdialysis from intact, freely behaving rats following oral ALM, ZOL or VEH. ALM increased BF ADO and GABA levels during waking and mixed vigilance states, and preserved sleep-associated increases in GABA under low and high sleep pressure conditions. ALM infusion into the BF also enhanced cortical ADO release, demonstrating that HCRT input is critical for ADO signaling in the BF. In contrast, oral ZOL and BF-infused ZOL had no effect on ADO levels in either BF or cortex. ALM increased BF ADO (an endogenous sleep-promoting substance) and GABA (which is increased during normal sleep), and required an intact BF for maximal efficacy, whereas ZOL blocked sleep-associated BF GABA release, and required no functional contribution from the BF to induce sleep. ALM thus induces sleep by facilitating the neural mechanisms underlying the normal transition to sleep. PMID:25431268

Vazquez-DeRose, Jacqueline; Schwartz, Michael D; Nguyen, Alexander T; Warrier, Deepti R; Gulati, Srishti; Mathew, Thomas K; Neylan, Thomas C; Kilduff, Thomas S



The GABA-synthetic enzyme GAD65 controls circadian activation of conditioned fear pathways.  


Circadian fluctuations of fear and anxiety symptoms are observable in persons with post-traumatic stress disorder, generalized anxiety, and panic disorder; however, the underlying neurobiological mechanisms are not sufficiently understood. In the present study, we investigated the putative role of inhibitory neurotransmission in the circadian fluctuation of fear symptoms, using mice with genetic ablation of the ?-amino butyric acid (GABA) synthesizing isoenzyme, glutamic acid decarboxylase GAD65. We observed in these mutant mice an altered expression of conditioned fear with a profound reduction of freezing, and an increase of hyperactivity bouts occurring only when both fear conditioning training and retrieval testing were done at the beginning of their active phase. Mutants further showed an increased arousal response at this time of the day, although, circadian rhythm of home cage activity was unaltered. Hyperactivity and reduced freezing during fear memory retrieval were accompanied by an increased induction of the immediate early gene cFos suggesting hyperactivation of the hippocampus, amygdala, and medial hypothalamus. Our data suggest a role of GAD65-mediated GABA synthesis in the encoding of circadian information to fear memory. GAD65 deficits in a state-dependent manner result in increased neural activation in fear circuits and elicit panic-like flight responses during fear memory retrieval. PMID:24300892

Bergado-Acosta, Jorge R; Müller, Iris; Richter-Levin, Gal; Stork, Oliver



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


High ?-aminobutyric acid (GABA)-producing lactobacilli are promising for the manufacture of GABA-rich foods and to synthesize GRAS (generally recognized as safe)-grade GABA. However, common chromatography-based screening is time-consuming and inefficient. In the present study, Korean kimchi was used as a model of lactic acid-based fermented foods, and a gas release-based prescreening of potential GABA producers was developed. The ability to produce GABA by potential GABA producers in de Man, Rogosa, and Sharpe medium supplemented with or without monosodium glutamate was further determined by HPLC. Based on the results, 9 isolates were regarded as high GABA producers, and were further genetically identified as Lactobacillus brevis based on the sequences of 16S rRNA gene. Gas release-based prescreening combined with reversed-phase HPLC confirmation was an efficient and cost-effective method to identify high-GABA-producing LAB, which could be good candidates for probiotics. The GABA that is naturally produced by these high-GABA-producing LAB could be used as a food additive. PMID:25497828

Wu, Qinglong; Shah, Nagendra P



?4?? GABA(A) receptors are high-affinity targets for ?-hydroxybutyric acid (GHB).  


?-Hydroxybutyric acid (GHB) binding to brain-specific high-affinity sites is well-established and proposed to explain both physiological and pharmacological actions. However, the mechanistic links between these lines of data are unknown. To identify molecular targets for specific GHB high-affinity binding, we undertook photolinking studies combined with proteomic analyses and identified several GABA(A) receptor subunits as possible candidates. A subsequent functional screening of various recombinant GABA(A) receptors in Xenopus laevis oocytes using the two-electrode voltage clamp technique showed GHB to be a partial agonist at ???- but not ???-receptors, proving that the ?-subunit is essential for potency and efficacy. GHB showed preference for ?4 over ?(1,2,6)-subunits and preferably activated ?4?1? (EC(50) = 140 nM) over ?4?(2/3)? (EC(50) = 8.41/1.03 mM). Introduction of a mutation, ?4F71L, in ?4?1(?)-receptors completely abolished GHB but not GABA function, indicating nonidentical binding sites. Radioligand binding studies using the specific GHB radioligand [(3)H](E,RS)-(6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylidene)acetic acid showed a 39% reduction (P = 0.0056) in the number of binding sites in ?4 KO brain tissue compared with WT controls, corroborating the direct involvement of the ?4-subunit in high-affinity GHB binding. Our data link specific GHB forebrain binding sites with ?4-containing GABA(A) receptors and postulate a role for extrasynaptic ?4?-containing GABA(A) receptors in GHB pharmacology and physiology. This finding will aid in elucidating the molecular mechanisms behind the proposed function of GHB as a neurotransmitter and its unique therapeutic effects in narcolepsy and alcoholism. PMID:22753476

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



Involvement of chloride channel coupled GABA(C) receptors in the peripheral antinociceptive effect induced by GABA(C) receptor agonist cis-4-aminocrotonic acid.  


We investigated the effect of chloride and potassium channel blockers on the antinociception induced by GABA(C) receptor agonist CACA (cis-4-aminocrotonic acid) using the paw pressure test, in which pain sensitivity was increased by an intraplantar injection (2 microg) of prostaglandin E(2) (PGE(2)). CACA administered locally into the right hindpaw (25, 50 and 100 microg/paw) elicited a dose-dependent antinociceptive effect which was demonstrated to be local, since only higher doses produced an effect when injected in the contralateral paw. The GABA(C) receptor antagonist (1,2,5,6 tetrahydropyridin-4-yl) methylphosphinic acid (TPMPA; 5, 10 and 20 microg/paw) antagonized, in a dose-dependent manner, the peripheral antinociception induced by CACA (100 microg), suggesting a specific effect. This effect was reversed by the chloride channel coupled receptor blocker picrotoxin (0.8 microg/paw). Glibenclamide (160 microg) and tolbutamide (320 microg), blockers of ATP-sensitive potassium channels, charybdotoxin (2 microg), a large-conductance potassium channel blocker, dequalinium (50 microg), a small-conductance potassium channel blocker, and cesium (500 microg), a non-specific potassium channel blocker did not modify the peripheral antinociception induced by CACA. This study provides evidence that activation of GABA(C) receptors in the periphery induces antinociception, that this effect results from the activation of chloride channel coupled GABA(C) receptors and that potassium channels appear not to be involved. PMID:17316706

Reis, Gláucia Maria Lopes; Duarte, Igor Dimitri Gama



Human Embryonic Stem Cell-Derived GABA Neurons Correct Locomotion Deficits in Quinolinic Acid-Lesioned Mice  

PubMed Central

Degeneration of medium spiny GABA neurons in the basal ganglia underlies motor dysfunction in Huntington’s disease (HD) which presently lacks effective therapy. In this study, we have successfully directed human embryonic stem cells (hESCs) to enriched populations of DARPP32-expressing forebrain GABA neurons. Transplantation of these human forebrain GABA neurons and their progenitors, but not spinal GABA cells, into the striatum of quinolinic acid-lesioned mice results in generation of large populations of DARPP32+ GABA neurons, which project to the substantia nigra as well as receiving glutamatergic and dopaminergic inputs, corresponding to correction of motor deficits. This finding raises hopes for cell therapy for HD. PMID:22424902

Ma, Lixiang; Hu, Baoyang; Liu, Yan; Vermilyea, Scott Christopher; Liu, Huisheng; Gao, Lu; Sun, Yan; Zhang, Xiaoqing; Zhang, Su-Chun



Phosphonic acid analogs of GABA through reductive dealkylation of phosphonic diesters with lithium trialkylborohydrides  

SciTech Connect

Lithium trialkylborohydrides were found to effect rapid monodealkylation of phosphonic diesters, and this reaction was applied to the synthesis of alkylphosphonic acid 2-aminoethyl esters [H2N(CH2)2OP(OH)R, 4], a little-explored class of analogs of the inhibitory neurotransmitter ?-aminobutyric acid (GABA). Compound 4a (R = Me) proved to be a potent antagonist at human ?1 GABAC receptors (expressed in Xenopus laevis oocytes), with an IC50 of 11.1 M, but is inactive at ?1?2?2 GABAA receptors.

Chowdhury, Sarwat [University of Illinois, Chicago; Muni, Niraj J. [University of Illinois, Chicago; Greenwood, Nicholas P. [University of Illinois, Chicago; Pepperberg, Dr. David R. [University of Illinois, Chicago; Standaert, Robert F [ORNL



Temporal- and Location-Specific Alterations of the GABA Recycling System in Mecp2 KO Mouse Brains  

PubMed Central

Rett syndrome (RTT), associated with mutations in methyl-CpG-binding protein 2 (Mecp2), is linked to diverse neurological symptoms such as seizures, motor disabilities, and cognitive impairments. An altered GABAergic system has been proposed as one of many underlying pathologies of progressive neurodegeneration in several RTT studies. This study for the first time investigated the temporal- and location-specific alterations in the expression of ?-amino butyric acid (GABA) transporter 1 (GAT-1), vesicular GABA transporter (vGAT), and glutamic acid decarboxylase 67kD (GAD67) in wild type (WT) and knockout (KO) mice in the Mecp2tm1.1Bird/y mouse model of RTT. Immunohistochemistry (IHC) co-labeling of GAT-1 with vGAT identified GABAergic synapses that were quantitated for mid-sagittal sections in the frontal cortex (FC), hippocampal dentate gyrus (DG), and striatum (Str). An age-dependent increase in the expression of synaptic GABA transporters, GAT-1, and vGAT, was observed in the FC and DG in WT brains. Mecp2 KO mice showed a significant alteration in this temporal profile that was location-specific, only in the FC. GAD67-positive cell densities also showed an age-dependent increase in the FC, but a decrease in the DG in WT mice. However, these densities were not significantly altered in the KO mice in the regions examined in this study. Therefore, the significant location-specific downregulation of synaptic GABA transporters in Mecp2 KO brains with unaltered densities of GAD67-positive interneurons may highlight the location-specific synaptic pathophysiology in this model of RTT. PMID:24737935

Kang, Seok K; Kim, Shin Tae; Johnston, Michael V; Kadam, Shilpa D



Effects of Vigabatrin, an Irreversible GABA Transaminase Inhibitor, on Ethanol Reinforcement and Ethanol Discriminative Stimuli in Mice  

PubMed Central

We tested the hypothesis that the irreversible gamma-amino butyric acid (GABA) transaminase inhibitor, ?-vinyl GABA (Vigabatrin; VGB) would reduce ethanol reinforcement and enhance the discriminative stimulus effect of ethanol, effectively reducing ethanol intake. The present studies used adult C57BL/6J (B6) mice in well-established operant, two-bottle choice consumption, locomotor activity and ethanol discrimination procedures, to examine comprehensively the effects of VGB on ethanol-supported behaviors. VGB dose-dependently reduced operant responding for ethanol as well as ethanol consumption for long periods of time. Importantly, a low dose (200 mg/kg) of VGB was selective for reducing ethanol responding without altering intake of food or water reinforcement. Higher VGB doses (>200 mg/kg) still reduced ethanol intake, but also significantly increased water consumption and, more modestly, increased food consumption. While not affecting locomotor activity on its own, VGB interacted with ethanol to reduce the stimulatory effects of ethanol on locomotion. Finally, VGB (200 mg/kg) significantly enhanced the discriminative stimulus effects of ethanol as evidenced by significant left-ward and up-ward shifts in ethanol generalization curves. Interestingly, VGB treatment was associated with slight increases in blood ethanol concentrations. The reduction in ethanol intake by VGB appears to be related to the ability of VGB to potentiate the pharmacological effects of ethanol. PMID:22336593

Griffin, William C.; Nguyen, Shaun A.; Deleon, Christopher P.; Middaugh, Lawrence D.



Inhibition studies of new ureido-substituted sulfonamides incorporating a GABA moiety against human carbonic anhydrase isoforms I-XIV.  


Reaction of ?-Boc-GABA, prepared by protecting the ?-amino moiety of the amino butyric acid with the tert-butyloxycarbonyl (Boc) protecting group, with 4-methyl/ethyl benzenesulfonamide, followed by removal of the Boc protecting group in 3 M HCl afforded the corresponding hydrochlorides, which were further derivatized by reaction with a varying of aryl isocyanates to give a new classes of ureido substituted benzenesulfonamide containing a GABA moiety. Inhibition studies of the human carbonic anhydrase(CA, EC isoforms, CA I–XIV with these new compounds revealed that they possess moderate-weak inhibition potency against hCA III, IV, VA, VI and XIII, rather efficient inhibitory power against hCA I, VI, and IX, and excellent inhibition of the physiologically relevant hCA II and VII, as well as of the two tumor-associated isoforms CA IX and XII. The inhibition profile of the new ureido-substituted benzenesulfonamides reported here is thus very different from the corresponding ureido-substituted analogs incorporating sulfanilamide, which were previously investigated as inhibitors of some of these enzymes. PMID:25468040

Ceruso, Mariangela; Antel, Sabrina; Vullo, Daniela; Scozzafava, Andrea; Supuran, Claudiu T



Synthesis of novel gamma-aminobutyric acid (GABA) uptake inhibitors. 5.(1) Preparation and structure-activity studies of tricyclic analogues of known GABA uptake inhibitors.  


On the basis of the SAR of a series of known gamma-aminobutyric acid (GABA) uptake inhibitors, including 4 (SKF 89976), new tricyclic analogues have been prepared. These novel compounds are derivatives of nipecotic acid, guvacine, and homo-beta-proline, substituted at the nitrogen of these amino acids by various lipophilic moieties such as (10,11-dihydro-5H-dibenz[b,f]azepin-5-yl)alkoxyalkyl or (10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene)alkoxyalkyl. The in vitro values for inhibition of [(3)H]-GABA uptake in rat synaptosomes was determined for each compound in this new series, and it was found that several of the novel compounds showed a high potency comparable with that of the reference compounds 4, 5 (tiagabine), and 6 (CI-966). Several of the novel compounds were also evaluated for their ability in vivo to inhibit clonic seizures induced by a 15 mg/kg (ip) dose of methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM). One compound, (R)-1-(2-(2-(10,11-dihydro-5H-dibenz[b,f]azepin-5-yl)ethoxy)ethyl)-3-piperidinecarboxylic acid (23), was selected for further biological investigations and showed a protective index comparable to or slightly better than that of the recently launched anticonvulsant product 5 ((R)-1-(4,4-bis(3-methyl-2-thienyl)-3-butenyl)-3-piperidinecarboxylic acid). PMID:11405652

Andersen, K E; Sørensen, J L; Lau, J; Lundt, B F; Petersen, H; Huusfeldt, P O; Suzdak, P D; Swedberg, M D



Exogenous ?-aminobutyric acid (GABA) affects pollen tube growth via modulating putative Ca2+-permeable membrane channels and is coupled to negative regulation on glutamate decarboxylase  

PubMed Central

?-Aminobutyric acid (GABA) is implicated in pollen tube growth, but the molecular and cellular mechanisms that it mediates are largely unknown. Here, it is shown that exogenous GABA modulates putative Ca2+-permeable channels on the plasma membranes of tobacco pollen grains and pollen tubes. Whole-cell voltage-clamp experiments and non-invasive micromeasurement technology (NMT) revealed that the influx of Ca2+ increases in pollen tubes in response to exogenous GABA. It is also demonstrated that glutamate decarboxylase (GAD), the rate-limiting enzyme of GABA biosynthesis, is involved in feedback controls of Ca2+-permeable channels to fluctuate intracellular GABA levels and thus modulate pollen tube growth. The findings suggest that GAD activity linked with Ca2+-permeable channels relays an extracellular GABA signal and integrates multiple signal pathways to modulate tobacco pollen tube growth. Thus, the data explain how GABA mediates the communication between the style and the growing pollen tubes. PMID:24799560

Yu, Guang-Hui; Zou, Jie; Feng, Jing; Peng, Xiong-Bo; Wu, Ju-You; Wu, Ying-Liang; Palanivelu, Ravishankar; Sun, Meng-Xiang



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

PubMed Central

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.

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




EPA Science Inventory

The ventral hippocampi of male, Fischer-344 rats were implanted with microdialysis probes and the effects of systemically administered kainic acid (KA) (8 mg/kg, s.c.) on the in vivo release of amino acids were measured for four hours after administration. n order to measure GABA...


Molecular and Therapeutic Potential and Toxicity of Valproic Acid  

PubMed Central

Valproic acid (VPA), a branched short-chain fatty acid, is widely used as an antiepileptic drug and a mood stabilizer. Antiepileptic properties have been attributed to inhibition of Gamma Amino Butyrate (GABA) transaminobutyrate and of ion channels. VPA was recently classified among the Histone Deacetylase Inhibitors, acting directly at the level of gene transcription by inhibiting histone deacetylation and making transcription sites more accessible. VPA is a widely used drug, particularly for children suffering from epilepsy. Due to the increasing number of clinical trials involving VPA, and interesting results obtained, this molecule will be implicated in an increasing number of therapies. However side effects of VPA are substantially described in the literature whereas they are poorly discussed in articles focusing on its therapeutic use. This paper aims to give an overview of the different clinical-trials involving VPA and its side effects encountered during treatment as well as its molecular properties. PMID:20798865

Chateauvieux, Sébastien; Morceau, Franck; Dicato, Mario; Diederich, Marc



Endogenous kynurenic acid regulates extracellular GABA levels in the rat prefrontal cortex.  


The tryptophan metabolite kynurenic acid (KYNA) is an endogenous antagonist of the ?7 nicotinic acetylcholine receptor (?7nAChR) and, at higher concentrations, inhibits ionotropic glutamate receptors. Increases in KYNA levels are seen in brain and cerebrospinal fluid in individuals with schizophrenia (SZ) and may be causally related to cognitive deficits in SZ and other psychiatric diseases. As dysfunction of circuits involving GABAergic neurons in the prefrontal cortex (PFC) likely plays a role in the cognitive impairments seen in these disorders, we examined the effects of KYNA on extracellular GABA in this brain area. Applied to awake rats for 2 h by reverse dialysis, KYNA concentration-dependently and reversibly reduced extracellular GABA levels, with 300 nM KYNA causing a nadir of ?45% of baseline concentrations. This effect was not duplicated by reverse dialysis of the selective glycineB receptor antagonist 7-Cl-KYNA (100 nM) or the AMPA/kainate receptor antagonist CNQX (100 ?M), and was prevented by co-application of galantamine (5 ?M), a positive allosteric modulator of the ?7nAChR. Conversely, inhibition of endogenous KYNA formation by reverse dialysis of (S)-4-(ethylsulfonyl)benzoylalanine (ESBA; 5 mM) reversibly increased GABA levels in the PFC, reaching a peak of ?160% of baseline concentrations. Co-infusion of 30 nM KYNA neutralized this effect. Taken together, these results demonstrate a role for endogenous KYNA in the bi-directional control of GABAergic neurotransmission in the PFC. Pharmacological manipulation of KYNA may therefore be useful in the treatment of GABAergic impairments in SZ and other brain disorders involving the PFC. PMID:24607890

Beggiato, Sarah; Tanganelli, Sergio; Fuxe, Kjell; Antonelli, Tiziana; Schwarcz, Robert; Ferraro, Luca



Anticonvulsant actions of the putative gamma-aminobutyric acid (GABA)-mimetic, ethylenediamine.  

PubMed Central

1 Ethylenediamine, 31.6-1000 mg/kg intraperitoneally, inhibited the convulsive effects of pentylenetetrazol, 100 mg/kg (i.p.) in mice. 2 Ethylenediamine, 100-1000 mg/kg (i.p.) increased the convulsion threshold to the intravenous infusion of three convulsants in the order pentylenetetrazol greater than bicuculline greater than strychnine. 3 The benzodiazepine antagonist R0 15-1788, 10 mg/kg (i.p.), significantly inhibited the anticonvulsant action of diazepam, 50 micrograms/kg, but not ethylenediamine, 1000 mg/kg. 4 These results clearly indicate that ethylenediamine has anticonvulsant properties and are consistent with the hypothesis that ethylenediamine is a gamma-aminobutyric acid (GABA)-mimetic. PMID:6814559

Morgan, P. F.; Stone, T. W.



Identification of the 64K autoantigen in insulin-dependent diabetes as the GABA-synthesizing enzyme glutamic acid decarboxylase  

Microsoft Academic Search

The pancreatic islet beta-cell autoantigen of relative molecular mass 64,000 (64K), which is a major target of autoantibodies associated with the development of insulin-dependent diabetes mel-litus (IDDM) has been identified as glutamic acid decarboxylase, the biosynthesizing enzyme of the inhibitory neurotransmitter GABA (gamma-aminobutyric acid). Pancreatic beta cells and a subpopulation of central nervous system neurons express high levels of this

Steinunn Baekkeskov; Henk-Jan Aanstoot; Stephan Christgai; Annette Reetz; Michele Solimena; Marilia Cascalho; Franco Folli; Hanne Richter-Olesen; Pietro-De Camilli



A Glutamic Acid-Producing Lactic Acid Bacteria Isolated from Malaysian Fermented Foods  

PubMed Central

l-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L) compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently ?-amino butyric acid (GABA) as a bioactive compound. PMID:22754309

Zareian, Mohsen; Ebrahimpour, Afshin; Bakar, Fatimah Abu; Mohamed, Abdul Karim Sabo; Forghani, Bita; Ab-Kadir, Mohd Safuan B.; Saari, Nazamid



GABA and mood disorders: a brief review and hypothesis  

Microsoft Academic Search

Considerable evidence implicates the neurotransmitter ?-aminobutyric acid (GABA) in the biochemical pathophysiology of mood disorders. Animal models of depression show regional brain GABA deficits and GABA agonists have antidepressant activity in these models. Somatic treatments for depression and mania upregulate the GABAB receptor, similar to the effect of GABA agonists. Clinical data indicate that decreased GABA function accompanies depressed or

Frederick Petty



Evidence for a GABAergic System in Rodent and Human Testis: Local GABA Production and GABA Receptors  

Microsoft Academic Search

The major neurotransmitter of the central nervous system, gamma-aminobutyric acid (GABA), exerts its actions through GABAA, GABAB and GABAC receptors. GABA and GABA receptors are, however, also present in several non-neural tissues, including the endocrine organs pituitary, pancreas and testis. In the case of the rat testis, GABA appears to be linked to the regulation of steroid synthesis by Leydig

Christof Geigerseder; Richard Doepner; Andrea Thalhammer; Monica B. Frungieri; Katia Gamel-Didelon; Ricardo S. Calandra; Frank M. Köhn; Artur Mayerhofer



Detection of amino acid neurotransmitters by surface enhanced Raman scattering and hollow core photonic crystal fiber  

NASA Astrophysics Data System (ADS)

The present work explores the feasibility of using surface enhanced Raman scattering (SERS) for detecting the neurotransmitters such as glutamate (GLU) and gamma-amino butyric acid (GABA). These amino acid neurotransmitters that respectively mediate fast excitatory and inhibitory neurotransmission in the brain, are important for neuroendocrine control, and upsets in their synthesis are also linked to epilepsy. Our SERS-based detection scheme enabled the detection of low amounts of GLU (10-7 M) and GABA (10-4 M). It may complement existing techniques for characterizing such kinds of neurotransmitters that include high-performance liquid chromatography (HPLC) or mass spectrography (MS). This is mainly because SERS has other advantages such as ease of sample preparation, molecular specificity and sensitivity, thus making it potentially applicable to characterization of experimental brain extracts or clinical diagnostic samples of cerebrospinal fluid and saliva. Using hollow core photonic crystal fiber (HC-PCF) further enhanced the Raman signal relative to that in a standard cuvette providing sensitive detection of GLU and GABA in micro-litre volume of aqueous solutions.

Tiwari, Vidhu S.; Khetani, Altaf; Monfared, Ali Momenpour T.; Smith, Brett; Anis, Hanan; Trudeau, Vance L.



Modelling zwitterions in solution: 3-fluoro-?-aminobutyric acid (3F-GABA).  


The conformations and relative stabilities of folded and extended 3-fluoro-?-aminobutyric acid (3F-GABA) conformers were studied using explicit solvation models. Geometry optimisations in the gas phase with one or two explicit water molecules favour folded and neutral structures containing intramolecular NH···O-C hydrogen bonds. With three or five explicit water molecules zwitterionic minima are obtained, with folded structures being preferred over extended conformers. The stability of folded versus extended zwitterionic conformers increases on going from a PCM continuum solvation model to the microsolvated complexes, though extended structures become less disfavoured with the inclusion of more water molecules. Full explicit solvation was studied with a hybrid quantum-mechanical/molecular-mechanical (QM/MM) scheme and molecular dynamics simulations, including more than 6000 TIP3P water molecules. According to free energies obtained from thermodynamic integration at the PM3/MM level and corrected for B3LYP/MM total energies, the fully extended conformer is more stable than folded ones by about -4.5 kJ mol(-1). B3LYP-computed (3)J(F,H) NMR spin-spin coupling constants, averaged over PM3/MM-MD trajectories, agree best with experiment for this fully extended form, in accordance with the original NMR analysis. The seeming discrepancy between static PCM calculations and experiment noted previously is now resolved. That the inexpensive semiempirical PM3 method performs so well for this archetypical zwitterion is encouraging for further QM/MM studies of biomolecular systems. PMID:22161781

Cao, Jie; Bjornsson, Ragnar; Bühl, Michael; Thiel, Walter; van Mourik, Tanja



Investigation of Gamma-aminobutyric acid (GABA) A receptors genes and migraine susceptibility  

PubMed Central

Background Migraine is a neurological disorder characterized by recurrent attacks of severe headache, affecting around 12% of Caucasian populations. It is well known that migraine has a strong genetic component, although the number and type of genes involved is still unclear. Prior linkage studies have reported mapping of a migraine gene to chromosome Xq 24–28, a region containing a cluster of genes for GABA A receptors (GABRE, GABRA3, GABRQ), which are potential candidate genes for migraine. The GABA neurotransmitter has been implicated in migraine pathophysiology previously; however its exact role has not yet been established, although GABA receptors agonists have been the target of therapeutic developments. The aim of the present research is to investigate the role of the potential candidate genes reported on chromosome Xq 24–28 region in migraine susceptibility. In this study, we have focused on the subunit GABA A receptors type ? (GABRE) and type ? (GABRQ) genes and their involvement in migraine. Methods We have performed an association analysis in a large population of case-controls (275 unrelated Caucasian migraineurs versus 275 controls) examining a set of 3 single nucleotide polymorphisms (SNPs) in the coding region (exons 3, 5 and 9) of the GABRE gene and also the I478F coding variant of the GABRQ gene. Results Our study did not show any association between the examined SNPs in our test population (P > 0.05). Conclusion Although these particular GABA receptor genes did not show positive association, further studies are necessary to consider the role of other GABA receptor genes in migraine susceptibility. PMID:19087248

Fernandez, Francesca; Esposito, Teresa; Lea, Rod A; Colson, Natalie J; Ciccodicola, Alfredo; Gianfrancesco, Fernando; Griffiths, Lyn R



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

SciTech Connect

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

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



[Arachidonoyl amino acids and arachidonoyl peptides: synthesis and properties].  


N-Arachidonoyl (AA) derivatives of amino acids (glycine, phenylalanine, proline, valine, gamma-amino butyric acid (GABA), dihydroxyphenylalanine, tyrosine, tryptophan, and alanine) and peptides (Semax, MEHFPGP, and PGP) were synthesized in order to study the biological properties of acylamino acids. The mass spectra of all the compounds at atmospheric pressure electrospray ionization display the most intense peaks of protonated molecular ions; the detection limits for these compounds are 10 fmol per sample. AA-Gly showed the highest inhibitory activity toward fatty acid amide hydrolase from rat brain (IC50 6.5 microM) among all the acylamino acids studied. AA-Phe, AA-Tyr, and AA-GABA exhibited a weak but detectable inhibitory effect (IC50 55, 60, and 50 microM, respectively). The acylated amino acids themselves, except for AA-Gly, were stable to the hydrolysis by this enzyme. All the arachidonoylamino acids inhibited cabbage phospholipase D to various degrees; AA-GABA and AA-Phe proved to be the most active (IC50 20 and 27 microM, respectively). Attempts to detect the biosynthesis of AA-Tyr in homogenates of rat liver and nerve tissue showed no formation in vitro of either this acylamino acid or AA-dopamine and AA-Phe, the products of its metabolism. The highest contents of these metabolites were detected in liver homogenate and in the brain homogenate, respectively. Acylamino acids exert no cytotoxic effect toward the glioma C6 cells. It was shown that N-acylation of Semax with arachidonic acid results in enhancement of its hydrolytic stability and increases its affinity for the sites of specific binding in rat cerebellum membranes. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also PMID:16808168

Bezuglov, V V; Gretskaia, N M; Blazhenova, A V; Adrianova, E L; Akimov, A V; Bobrov, M Iu; Nazimov, I V; Kisel', M I; Sharko, O L; Novikov, A V; Krasnov, N V; Shevchenko, V P; V'iunova, T V; Miasoedova, N F



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

Technology Transfer Automated Retrieval System (TEKTRAN)

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


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


Liver is one of the major organs in vertebrates and hepatocytes are damaged by many factors. The liver cell maintenance and multiplication after injury and treatment gained immense interest. The present study investigated the role of Gamma aminobutyric acid (GABA) and serotonin or 5-hydroxytryptamine (5-HT) coupled with chitosan nanoparticles in the functional regulation of Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors mediated cell signaling mechanisms, extend of DNA methylation and superoxide dismutase activity during enhanced liver cell proliferation. Liver injury was achieved by partial hepatectomy of male Wistar rats and the GABA and 5-HT chitosan nanoparticles treatments were given intraperitoneally. The experimental groups were sham operated control (C), partially hepatectomised rats with no treatment (PHNT), partially hepatectomised rats with GABA chitosan nanoparticle (GCNP), 5-HT chitosan nanoparticle (SCNP) and a combination of GABA and 5-HT chitosan nanoparticle (GSCNP) treatments. In GABA and 5-HT chitosan nanoparticle treated group there was a significant decrease (P<0.001) in the receptor expression of Gamma aminobutyric acid B and a significant increase (P<0.001) in the receptor expression of 5-hydroxy tryptamine 2A when compared to PHNT. The cyclic adenosine monophosphate content and its regulatory protein, presence of methylated DNA and superoxide dismutase activity were decreased in GCNP, SCNP and GSCNP when compared to PHNT. The Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors coupled signaling elements played an important role in GABA and 5-HT chitosan nanoparticles induced liver cell proliferation which has therapeutic significance in liver disease management. PMID:23748019

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



Light-evoked changes in chick optic lobe GABA system.  


In young chicks the effects of 3 min stroboscope stimulation on GABA and free glutamic acid content and on GAD and GABA-T activity in optic lobes were studied. A significant depletion in GABA and glutamic acid levels was found to occur. In addition a sustained increase in GABA-T and GAD activity was observed. In conclusion present experiments are in favour of an inhibitory role played by GABA in chick optic tectum during stroboscope stimulation. PMID:451334

Nisticò, G; Ientile, R; Rotiroti, D; Di Giorgio, R M



Leaf Senescence and GABA Shunt  

PubMed Central

Leaf senescence is highly regulated and complex developmental process that involves degradation of macromolecules as well as its recycling. Senescence process involves loss of chlorophyll, degradation of proteins, nucleic acid, lipid and mobilization of nutrients through its transport to the growing parts, developing fruits and seeds. Nitrogen is the most important nutrient to be recycled in senescence process. GABA-transaminase (?-aminobutyric acid) is found to play very important role in nitrogen recycling process through GABA-shunt. Therefore, it is of interest to review the significance of GABA shunt in leaf senescence.

Ansari, Mohammad Israil; Hasan, Saba; Jalil, Syed Uzma



gamma-Aminobutyric acid (GABA)-induced currents of skate Muller (glial) cells are mediated by neuronal-like GABAA receptors.  

PubMed Central

Radial glia (Muller cells) of the vertebrate retina appear to be intimately involved in regulating the actions of amino acid neurotransmitters. One of the amino acids thought to be important in mediating retinal information flow is gamma-aminobutyric acid (GABA). The findings of this study indicate that enzymatically isolated skate Muller cells are depolarized by GABA and the GABAA agonist muscimol and that the actions of these agents are reduced by bicuculline and picrotoxin. Membrane currents induced by GABA under voltage clamp were dose dependent, were associated with an increase in membrane conductance, and showed marked desensitization when the concentration of GABA exceeded 2.5 microM. The responses had a reversal potential close to that calculated for chloride, indicating that the currents were generated by ions passing through channels. These data support the view that skate Muller cells possess functional GABAA receptors. The presence of such receptors on retinal glia may have important implications for the role of Muller cells in maintaining the constancy of the extracellular milieu, for neuron-glia interactions within the retina, and for theories concerning the generation of the electroretinogram. Images PMID:2567001

Malchow, R P; Qian, H H; Ripps, H



Influence of a Gamma Amino Acid on the Structures and Reactivity of Peptide a3 Ions  

PubMed Central

Collision-induced dissociation of protonated AGabaAIG (where Gaba is gamma-amino butyric acid, NH2-(CH2)3-COOH) leads to an unusually stable a3 ion. Tandem mass spectrometry and theory are used here to probe the enhanced stability of this fragment, whose counterpart is not usually observed in CID of protonated peptides containing only alpha amino acids. Experiments are carried out on the unlabelled and 15N-Ala labeled AGabaAIG (labeled separately at residue one or three) probing the b3, a3, a3-NH3 (a3*), and b2 fragments while theory is used to characterize the most stable b3, a3, and b2 structures and the formation and dissociation of the a3 ion. Our results indicate the AGabaA oxazolone b3 isomer undergoes head-to-tail macrocyclization and subsequent ring opening to form the GabaAA sequence isomer while this chemistry is energetically disfavored for the AAA sequence. The AGabaA a3 fragment also undergoes macrocyclization and rearrangement to form the rearranged imine-amide isomer while this reaction is energetically disfavored for the AAA sequence. The barriers to dissociation of the AGabaA a3 ion via the a3?b2 and a3?a3* channels are higher than the literature values reported for the AAA sequence. These two effects provide a clear explanation for the enhanced stability of the AGabaA a3 ion. PMID:23258959

Bernier, Matthew C.; Paizs, Bela; Wysocki, Vicki H.



GABA transporters in the mammalian cerebral cortex: localization, development and pathological implications  

E-print Network

-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the mammalian cerebral cortex, are regulated neurotransmitters; Neurotransmitter uptake; Neurons; Glia; Inhibitory synapses Contents 1. Introduction placed to mediate GABA uptake at fast inhibitory synapses, terminating GABA's action and shaping

Sandini, Giulio


In vitro studies on GABA release  

PubMed Central

1 Recent studies have demonstrated growing evidence for a primary action of the benzodiazepines on gabaminergic neurones which induces a facilitation of ?-aminobutyric acid (GABA)-mediated neurotransmission. As enhancement of GABA release has been suggested to account for their activation of GABA mechanisms, the effect of diazepam and clobazam, and of several other psychotropic drugs, on stimulated GABA release have been studied. 2 Using rat brain cortex slices saturated with [3H]-GABA, the electrically stimulated overflow of GABA is reduced in a concentration-dependent manner in the presence of both diazepam and clobazam. 3 The benzodiazepine-induced reduction in GABA overflow during electrical stimulation is antagonized by the GABA receptor blocker bicuculline, whereas bicuculline alone at 10-6 M concentration does not change the overflow. 4 Among some other centrally active drugs tested, hexobarbitone and the `second messenger' cyclic GMP also induce a significant but less marked reduction in GABA release. 5 A schematic model of a central gabaminergic synapse is proposed, which may explain the benzodiazepine effects on stimulated GABA release by suggesting an inhibitory feedback control of transmitter release mediated by presynaptic GABA receptors (`autoreceptors'). PMID:35201

Schacht, U.; Bäcker, G.



Anthelmintic efficacy of genistein, the active principle of Flemingia vestita (Fabaceae): alterations in the free amino acid pool and ammonia levels in the fluke, Fasciolopsis buski.  


The crude root-peel extract of Flemingia vestita, its active principle genistein and the reference flukicide oxyclozanide were tested against Fasciolopsis buski, the giant intestinal trematode. The amino acid composition of F. buski was demonstrated using HPLC and it was observed that the free amino acid (FAA) pool of the control worm consisted of aspartate, threonine, serine, glutamic acid, glutamine, proline, glycine, alanine, valine, methionine, isoleucine, leucine, tyrosine, lysine, histidine, arginine, phosphoserine, taurine, citrulline, ornithine, beta-alanine, and gamma-amino butyric acid (GABA). Of the amino acids detected valine was found to be the maximum in quantitative analysis. In qualitative analysis the FAA pool of the parasites under various treatments remained same as that of the control; however, quantitatively the level of various FAAs in the parasite was significantly affected. The treated parasites showed a marked decrease in the levels of arginine, ornithine, tyrosine, leucine, isoleucine, valine, alanine, glycine, proline, serine, threonine, and taurine following treatment with 20 mg/ml of crude peel extract, 0.5 mg/ml of genistein and 20 mg/ml of the reference drug, though an increase in the levels of glutamic acid, glutamine, phosphoserine, citrulline and GABA was noticeable. Enhanced levels of GABA and citrulline under the influence of genistein may be implicated in alterations of nitric oxide release and consequent neurological change (e.g. paralysis) in the parasite. Ammonia in the tissue homogenate as well as in the incubation medium showed a quantitative increase compared to the controls after treatment with the various test materials. The ammonia level increased by 40.7%, 66.4% and 18.16% in treatments with F. vestita, genistein and oxyclozanide, respectively, at the mentioned dosages. The changes in the levels of the amino acids and nitrogen components post treatment suggest that the amino acid metabolism in the parasite may have been altered under the influence of the test materials. PMID:15464437

Kar, Pradip Kumar; Tandon, Veena; Saha, Nirmalendu



GABA Neurotransmitter  

NSDL National Science Digital Library

GABA occurs in 30-40% of all synapses-only glutamate is more widely distributed. Neurons in every region of the brain use GABA to fine-tune neurotransmission. Increasing GABA at the neuronal synapse inhibits the generation of the action potential of the neuron, thereby making it less likely to excite nearby neurons. A single neuron may have thousands of other neurons synapsing onto it. Some of these release activating (or depolarizing) neurotransmitters; others release inhibitory (or hyperpolarizing) neurotransmitters. GABA is the primary inhibitory neurotransmitter, which means it decreases the neuron's action potential. When the action potential drops below a certain level, known as the threshold potential, the neuron will not generate action potentials and thus not excite nearby neurons. The nucleus of a neuron is located in the cell body. Extending out from the cell body are dendrites and axons. Dendrites conduct impulses toward the cell body, Axons conducting impulses away from the cell body. A recording electrode has been attached to a voltmeter to record the charge across the cell membrane, the thin layer that controls movement in and out of the neuron. The resting potential in excitable neurons is usually around -65 to -70 millivolts (mV), which can be seen on the voltmeter. Excitatory synapses reduce the membrane potential: The synapses labeled A, B, and C are excitatory (e.g. glutamate ACH). These synapses release activating neurotransmitters, which reduce the resting potential of the neuron. If the voltage reaches the threshold potential, typically around -50 mv, an action potential is generated, which will travel down the axon, where it will communicate with a nearby cell. The strength of the stimuli that produce an action potential is important only insomuch as it reaches threshold potential. The resultant action potential is always the same, whether it was created by relatively strong or relatively weak stimuli. action potential is a constant. Decreasing the action potential: GABA is the primary inhibitory neurotransmitter, which means it decreases the neuron�s action potential. When the action potential drops below the threshold potential, the neuron will not excite nearby neurons. Exitatory PostSynaptic Potential (EPSP): The Exitatory PostSynaptic Potential (EPSP) of a single excitatory synapse is not sufficient to reach the threshold of the neuron. Rather, when a number of EPSPs are created in quick succession, their charges sum together. It is the combined sum of these EPSPs that creates an action potential Activation of inhibitory synapses such as GABA, on the other hand, makes resting potential more negative. This hyperpolarization is called an inhibitory postsynaptic potential (IPSP). Activation of inhibitory synapses (D and E) makes the resting potential of the neuron more negative. The resulting IPSP may also prevent what would otherwise have been effective EPSPs from triggering an action potential. It is the total summation of the EPSPs and IPSPs that determines whether a neuron�s charge is sufficient to cross the potential threshold.



Variations nycthmrales de l'incorporation de l'acide ?-aminobutyrique (GABA) et  

E-print Network

injected and their concentration both in pineal gland and cerebellum were measured at several times along in the uptake of two neurotransmitters, y-aminobutyric acid (GABAJ and taurine in CD mice. Pineal uptake of two uptake was high during the night, when the gland was active and low during the day. It corresponded

Paris-Sud XI, Université de


GABA Neuron Systems in Hypothalamus and the Pituitary Gland  

Microsoft Academic Search

The distribution of ?-aminobutyric acid (GABA) nerve fibers and cell bodies in the rat hypothalamus and pituitary gland was immunohistochemically examined using antibodies against the GABA-synthesizing enzyme glutamate decarboxylase (GAD). A dense network of GAD-positive nerve fibers was observed to be essentially evenly distributed throughout the hypothalamus. A plexus of GABA terminals was also demonstrated both in the median eminence

Steven R. Vincent; Tomas Hökfelt; Jang-Yen Wu



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

NASA Technical Reports Server (NTRS)

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

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



Comparison of bioactive components in GABA tea and green tea produced in Taiwan  

Microsoft Academic Search

The aim of this study is to investigate the bioactive components of GABA (?-aminobutyric acid) tea as compared with green tea produced in Taiwan. Using in total 56 tea samples (28 green tea and 28 GABA tea), moisture content, Hunter L, a and b values, phenolic compounds, amino acids including GABA, fatty acids and ascorbic acid were determined. The results

Hsueh Fang Wang; Yung Sheng Tsai; Mu Lien Lin; Andi Shau-mei Ou



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


GABA transaminase (GABA-T) catalyses the conversion of GABA to succinate semialdehyde (SSA) in the GABA shunt pathway. The GABA-T from Saccharomyces cerevisiae (ScGABA-TKG) is an ?-ketoglutarate-dependent enzyme encoded by the UGA1 gene, while higher plant GABA-T is a pyruvate/glyoxylate-dependent enzyme encoded by POP2 in Arabidopsis thaliana (AtGABA-T). The GABA-T from A. thaliana is localized in mitochondria and mediated by an 18-amino acid N-terminal mitochondrial targeting peptide predicated by both web-based utilities TargetP 1.1 and PSORT. Yeast UGA1 appears to lack a mitochondrial targeting peptide and is localized in the cytosol. To verify this bioinformatic analysis and examine the significance of ScGABA-TKG and AtGABA-T compartmentation and substrate specificity on physiological function, expression vectors were constructed to modify both ScGABA-TKG and AtGABA-T, so that they express in yeast mitochondria and cytosol. Physiological function was evaluated by complementing yeast ScGABA-TKG deletion mutant ?uga1 with AtGABA-T or ScGABA-TKG targeted to the cytosol or mitochondria for the phenotypes of GABA growth defect, thermosensitivity and heat-induced production of reactive oxygen species (ROS). This study demonstrates that AtGABA-T is functionally interchangeable with ScGABA-TKG for GABA growth, thermotolerance and limiting production of ROS, regardless of location in mitochondria or cytosol of yeast cells, but AtGABA-T is about half as efficient in doing so as ScGABA-TKG. These results are consistent with the hypothesis that pyruvate/glyoxylate-limited production of NADPH mediates the effect of the GABA shunt in moderating heat stress in Saccharomyces. PMID:23740823

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



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


The western corn rootworm, Diabrotica virgifera virgifera, is a damaging pest of cultivated corn that was controlled by applications of cyclodiene insecticides from the late 1940s until resistance evolved ?10 years later. Range expansion from the western plains into eastern USA coincides with resistance development. An alanine to serine amino acid substitution within the Rdl subunit of the gamma-aminobutyric acid (GABA) receptor confers resistance to cyclodiene insecticides in many species. We found that the non-synonymous single nucleotide polymorphism (SNP) G/T at the GABA receptor cDNA position 838 (G/T(838)) of D.?v. virgifera resulted in the alanine to serine change, and the codominant SNP allele T(838) was genetically linked to survival of beetles in aldrin bioassays. A phenotypic gradient of decreasing susceptibility from west to east was correlated with higher frequencies of the resistance-conferring T(838) allele in the eastern-most populations. This pattern exists in opposition to perceived selective pressures since the more eastern and most resistant populations probably experienced reduced exposure. The reasons for the observed distribution are uncertain, but historical records of the range expansion combined with the distribution of susceptible and resistant phenotypes and genotypes provide an opportunity to better understand factors affecting the species' range expansion. PMID:23841833

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



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


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 ?-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. PMID:23535348

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



Muscimol as an ionotropic GABA receptor agonist.  


Muscimol, a psychoactive isoxazole from Amanita muscaria and related mushrooms, has proved to be a remarkably selective agonist at ionotropic receptors for the inhibitory neurotransmitter GABA. This historic overview highlights the discovery and development of muscimol and related compounds as a GABA agonist by Danish and Australian neurochemists. Muscimol is widely used as a ligand to probe GABA receptors and was the lead compound in the development of a range of GABAergic agents including nipecotic acid, tiagabine, 4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol, (Gaboxadol(®)) and 4-PIOL. PMID:24473816

Johnston, Graham A R



Effects of yoga on the autonomic nervous system, gamma-aminobutyric-acid, and allostasis in epilepsy, depression, and post-traumatic stress disorder.  


A theory is proposed to explain the benefits of yoga practices in diverse, frequently comorbid medical conditions based on the concept that yoga practices reduce allostatic load in stress response systems such that optimal homeostasis is restored. It is hypothesized that stress induces (1) imbalance of the autonomic nervous system (ANS) with decreased parasympathetic nervous system (PNS) and increased sympathetic nervous system (SNS) activity, (2) underactivity of the gamma amino-butyric acid (GABA) system, the primary inhibitory neurotransmitter system, and (3) increased allostatic load. It is further hypothesized that yoga-based practices (4) correct underactivity of the PNS and GABA systems in part through stimulation of the vagus nerves, the main peripheral pathway of the PNS, and (5) reduce allostatic load. Depression, epilepsy, post traumatic stress disorder (PTSD), and chronic pain exemplify medical conditions that are exacerbated by stress, have low heart rate variability (HRV) and low GABAergic activity, respond to pharmacologic agents that increase activity of the GABA system, and show symptom improvement in response to yoga-based interventions. The observation that treatment resistant cases of epilepsy and depression respond to vagal nerve stimulation corroborates the need to correct PNS underactivity as part of a successful treatment plan in some cases. According to the proposed theory, the decreased PNS and GABAergic activity that underlies stress-related disorders can be corrected by yoga practices resulting in amelioration of disease symptoms. This has far-reaching implications for the integration of yoga-based practices in the treatment of a broad array of disorders exacerbated by stress. PMID:22365651

Streeter, C C; Gerbarg, P L; Saper, R B; Ciraulo, D A; Brown, R P



Mice Lacking the 65 kDa Isoform of Glutamic Acid Decarboxylase (GAD65) Maintain Normal Levels of GAD67 and GABA in Their Brains but Are Susceptible to Seizures  

Microsoft Academic Search

The gene encoding of the 65 kDa isoform of the ?-aminobutyric acid (GABA)-synthesizing enzyme, glutamic acid decarboxylase (GAD), GAD65, was targeted in mice by homologous recombination. Viable GAD65 ?\\/? mice were obtained with the expected mendelian frequency and displayed no gross morphological defects. Despite the complete loss of GAD65 mRNA and protein in a homozygous mutant, there was no difference

Hideo Asada; Yuuki Kawamura; Kei Maruyama; Hideaki Kume; Ri-gao Ding; Feng Yun Ji; Nobuko Kanbara; Hiroko Kuzume; Makoto Sanbo; Takeshi Yagi; Kunihiko Obata



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

SciTech Connect

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

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



The GABA Hypothesis in Essential Tremor: Lights and Shadows  

PubMed Central

Background The gamma-aminobutyric acid (GABA) hypothesis in essential tremor (ET) implies a disturbance of the GABAergic system, especially involving the cerebellum. This review examines the evidence of the GABA hypothesis. Methods The review is based on published data about GABA dysfunction in ET, taking into account studies on cerebrospinal fluid, pathology, electrophysiology, genetics, neuroimaging, experimental animal models, and human drug therapies. Results Findings from several studies support the GABA hypothesis in ET. The hypothesis follows four steps: 1) cerebellar neurodegeneration with Purkinje cell loss; 2) a decrease in GABA system activity in deep cerebellar neurons; 3) disinhibition in output deep cerebellar neurons with pacemaker activity; and 4) an increase in rhythmic activity of the thalamus and thalamo-cortical circuit, contributing to the generation of tremor. Doubts have been cast on this hypothesis, however, by the fact that it is based on relatively few works, controversial post-mortem findings, and negative genetic studies on the GABA system. Furthermore, GABAergic drug efficacy is low and some GABAergic drugs do not have antitremoric efficacy. Discussion The GABA hypothesis continues to be the most robust pathophysiological hypothesis to explain ET. There is light in all GABA hypothesis steps, but a number of shadows cannot be overlooked. We need more studies to clarify the neurodegenerative nature of the disease, to confirm the decrease of GABA activity in the cerebellum, and to test more therapies that enhance the GABA transmission specifically in the cerebellum area. PMID:25120944

Gironell, Alexandre



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

Microsoft Academic Search

In the immature brain, GABA (?-aminobutyric acid) is excitatory, and GABA-releasing synapses are formed before glutamatergic contacts in a wide range of species and structures. GABA becomes inhibitory by the delayed expression of a chloride exporter, leading to a negative shift in the reversal potential for choride ions. I propose that this mechanism provides a solution to the problem of

Yehezkel Ben-Ari



GABA Promotes Human ?-Cell Proliferation and Modulates Glucose Homeostasis.  


?-Aminobutyric acid (GABA) exerts protective and regenerative effects on mouse islet ?-cells. However, in humans it is unknown whether it can increase ?-cell mass and improve glucose homeostasis. To address this question, we transplanted a suboptimal mass of human islets into immunodeficient NOD-scid-? mice with streptozotocin-induced diabetes. GABA treatment increased grafted ?-cell proliferation, while decreasing apoptosis, leading to enhanced ?-cell mass. This was associated with increased circulating human insulin and reduced glucagon levels. Importantly, GABA administration lowered blood glucose levels and improved glucose excursion rates. We investigated GABA receptor expression and signaling mechanisms. In human islets, GABA activated a calcium-dependent signaling pathway through both GABA A receptor and GABA B receptor. This activated the phosphatidylinositol 3-kinase-Akt and CREB-IRS-2 signaling pathways that convey GABA signals responsible for ?-cell proliferation and survival. Our findings suggest that GABA regulates human ?-cell mass and may be beneficial for the treatment of diabetes or improvement of islet transplantation. PMID:25008178

Purwana, Indri; Zheng, Juan; Li, Xiaoming; Deurloo, Marielle; Son, Dong Ok; Zhang, Zhaoyun; Liang, Christie; Shen, Eddie; Tadkase, Akshaya; Feng, Zhong-Ping; Li, Yiming; Hasilo, Craig; Paraskevas, Steven; Bortell, Rita; Greiner, Dale L; Atkinson, Mark; Prud'homme, Gerald J; Wang, Qinghua



Systemic administration of 1R,4S-4-amino-cyclopent-2-ene-carboxylic acid, a reversible inhibitor of GABA transaminase, blocks expression of conditioned place preference to cocaine and nicotine in rats.  


We examined the effect of 1R,4S-4-amino-cyclopent-2-ene-carboxylic acid (ACC), a reversible inhibitor of GABA transaminase, on the expression of conditioned place preference response to cocaine and nicotine in rats. Cocaine (20 mg/kg i.p.) and nicotine (0.4 mg/kg s.c.), but not vehicle or 300 mg/kg i.p. of ACC, produced a significant conditioned place preference response. Pretreatment of animals with 300 and 75 mg/kg i.p. of ACC significantly attenuated the expression of the cocaine- and nicotine-induced conditioned place preference responses, respectively. These results are the first to suggest that reversible inhibition of GABA transaminase may be useful in blocking cue-induced relapse to nicotine and cocaine. PMID:11891877

Ashby, Charles R; Paul, Mousumi; Gardner, Eliot L; Gerasimov, Madina R; Dewey, Stephen L; Lennon, Ian C; Taylor, Stephen J C



Lactic acid bacteria contribution to gut microbiota complexity: lights and shadows  

PubMed Central

Lactic Acid Bacteria (LAB) are ancient organisms that cannot biosynthesize functional cytochromes, and cannot get ATP from respiration. Besides sugar fermentation, they evolved electrogenic decarboxylations and ATP-forming deiminations. The right balance between sugar fermentation and decarboxylation/deimination ensures buffered environments thus enabling LAB to survive in human gastric trait and colonize gut. A complex molecular cross-talk between LAB and host exists. LAB moonlight proteins are made in response to gut stimuli and promote bacterial adhesion to mucosa and stimulate immune cells. Similarly, when LAB are present, human enterocytes activate specific gene expression of specific genes only. Furthermore, LAB antagonistic relationships with other microorganisms constitute the basis for their anti-infective role. Histamine and tyramine are LAB bioactive catabolites that act on the CNS, causing hypertension and allergies. Nevertheless, some LAB biosynthesize both gamma-amino-butyrate (GABA), that has relaxing effect on gut smooth muscles, and beta-phenylethylamine, that controls satiety and mood. Since LAB have reduced amino acid biosynthetic abilities, they developed a sophisticated proteolytic system, that is also involved in antihypertensive and opiod peptide generation from milk proteins. Short-chain fatty acids are glycolytic and phosphoketolase end-products, regulating epithelial cell proliferation and differentiation. Nevertheless, they constitute a supplementary energy source for the host, causing weight gain. Human metabolism can also be affected by anabolic LAB products such as conjugated linoleic acids (CLA). Some CLA isomers reduce cancer cell viability and ameliorate insulin resistance, while others lower the HDL/LDL ratio and modify eicosanoid production, with detrimental health effects. A further appreciated LAB feature is the ability to fix selenium into seleno-cysteine. Thus, opening interesting perspectives for their utilization as antioxidant nutraceutical vectors. PMID:22919677

Pessione, Enrica



Development and Validation of a HPTLC Method for Simultaneous Estimation of L-Glutamic Acid and ?-Aminobutyric Acid in Mice Brain.  


A new robust, simple and economic high performance thin layer chromatographic method was developed for simultaneous estimation of L-glutamic acid and ?-amino butyric acid in brain homogenate. The high performance thin layer chromatographic separation of these amino acid was achieved using n-butanol:glacial acetic acid:water (22:3:5 v/v/v) as mobile phase and ninhydrin as a derivatising agent. Quantitation of the method was achieved by densitometric method at 550 nm over the concentration range of 10-100 ng/spot. This method showed good separation of amino acids in the brain homogenate with Rf value of L-glutamic acid and ?-amino butyric acid as 21.67±0.58 and 33.67±0.58, respectively. The limit of detection and limit of quantification for L-glutamic acid was found to be 10 and 20 ng and for ?-amino butyric acid it was 4 and 10 ng, respectively. The method was also validated in terms of accuracy, precision and repeatability. The developed method was found to be precise and accurate with good reproducibility and shows promising applicability for studying pathological status of disease and therapeutic significance of drug treatment. PMID:24591747

Sancheti, J S; Shaikh, M F; Khatwani, P F; Kulkarni, Savita R; Sathaye, Sadhana



GABA Predicts Time Perception  

PubMed Central

Our perception of time constrains our experience of the world and exerts a pivotal influence over a myriad array of cognitive and motor functions. There is emerging evidence that the perceived duration of subsecond intervals is driven by sensory-specific neural activity in human and nonhuman animals, but the mechanisms underlying individual differences in time perception remain elusive. We tested the hypothesis that elevated visual cortex GABA impairs the coding of particular visual stimuli, resulting in a dampening of visual processing and concomitant positive time-order error (relative underestimation) in the perceived duration of subsecond visual intervals. Participants completed psychophysical tasks measuring visual interval discrimination and temporal reproduction and we measured in vivo resting state GABA in visual cortex using magnetic resonance spectroscopy. Time-order error selectively correlated with GABA concentrations in visual cortex, with elevated GABA associated with a rightward horizontal shift in psychometric functions, reflecting a positive time-order error (relative underestimation). These results demonstrate anatomical, neurochemical, and task specificity and suggest that visual cortex GABA contributes to individual differences in time perception. PMID:24647956

Russo, Sonia; Near, Jamie; Stagg, Charlotte J.; Cohen Kadosh, Roi



Characterization of GABA Receptors  

PubMed Central

Described in this unit are ligand binding assays for GABAA, GABAB, and the homomeric ? GABAA (formerly GABAC) receptor recognition sites in brain tissue. Although GABA binding sites are present in peripheral organs, most research is directed toward examining these receptors in the CNS. These assays may also be used to determine the affinity of an unlabeled compound for the GABA binding sites. Excluded from the unit are ligand binding assays for other components of the GABAA receptor complex, such as the benzodiazepine (Unit 1.16) or ion channel (Unit 1.18) binding sites. PMID:24510754

Enna, S.J.; McCarson, Kenneth E.



Long-term reproducibility of GABA magnetic resonance spectroscopy.  


Recent findings suggest that cortical gamma aminobutyric acid (GABA) levels may provide a surrogate marker for a number of psychiatric and neurological conditions, as well as behavioural traits. However, the natural variability of GABA levels in the human brain over long periods of time (>8 days) has not yet been studied. The purpose of this work was to investigate the long-term variability of GABA concentrations in the human occipital cortex. Nineteen healthy male participants were recruited and underwent two sessions of magnetic resonance spectroscopy (MRS) to determine occipital GABA levels with an average between-session interval of 7 months. We assessed between-session variability, as well as the correlation between session 1 and session 2 GABA measurements. The mean coefficient of variation between sessions was 4.3% (bootstrap 95% confidence interval: 2.5, 6.4), which is comparable to reported GABA variability measurements over much shorter time intervals (<8 days). A significant positive correlation was observed between session 1 and session 2 GABA measurements (r=0.53, p=0.014), and the intra-class correlation coefficient was calculated to be 0.52 which was also statistically significant (p=0.012). These findings establish experimentally that GABA concentrations in the occipital cortex, as measured by MRS, are relatively stable over periods as long as 7 months. The findings have significant implications for the internal validity of longitudinal studies of GABA levels in the human brain, and they lend foundational support to studies relating GABA levels to behavioural traits in healthy individuals. PMID:24875142

Near, Jamie; Ho, Yi-Ching Lynn; Sandberg, Kristian; Kumaragamage, Chathura; Blicher, Jakob Udby



Depolarizing GABA and Developmental Epilepsies.  


Early in development, GABA, which is the main inhibitory neurotransmitter in adult brain, depolarizes immature neurons and exerts dual-excitatory and shunting/inhibitory-effects in the developing neuronal networks. The present review discusses some general questions, including the properties of excitation at depolarizing GABAergic synapse and shunting inhibition by depolarizing GABA; technical issues in exploration of depolarizing GABA using various techniques and preparations, including the developmental aspects of traumatic injury and what is known (or rather unknown) on the actions of GABA in vivo; complex roles of depolarizing GABA in developmental epilepsies, including a contribution of depolarizing GABA to enhanced excitability in the immature networks, caused by repetitive seizures accumulation of intracellular chloride concentration that increases excitatory GABA power and its synchronizing proconvulsive effects, and correction of chloride homeostasis as a potential strategy to treat neonatal seizures. PMID:25438879

Khazipov, Roustem; Valeeva, Guzel; Khalilov, Ilgam



Molecular cloning and differential expression of an ?-aminobutyrate transaminase gene, OsGABA-T , in rice ( Oryza sativa ) leaves infected with blast fungus  

Microsoft Academic Search

?-Aminobutyrate transaminase (GABA-T) catalyzes the conversion of GABA to succinic semialdehyde. Using differential display PCR and cDNA library screening, a full-length GABA-T cDNA (OsGABA-T) was isolated from rice (Oryza sativa) leaves infected with an incompatible race of Magnaporthe grisea. The deduced amino acid sequence comprises 483 amino acid residues and shares 85–69% identity with GABA-T sequences from other plants.\\u000a OsGABA-T

Chunxia Wu; Shanyue Zhou; Quan Zhang; Wensheng Zhao; Youliang Peng



Associate editor: B.L. Roth The human reelin gene: Transcription factors (+), repressors (-)  

E-print Network

-Woodruff, J. H., & Knable, M. B. (2005). Neurochemical markers for schizophrenia, bipolar disorder amd major, bipolar disorder; Dnmt, DNA methyltransferase; GABA, gamma-amino butyric acid; GAD, glutamic acid of Medicine, University of Illinois at Chicago, 1601 W. Taylor St., Chicago, IL 60612, United States Abstract

Champagne, Frances A.


Simultaneous determination of monoamine and amino acid neurotransmitters in rat endbrain tissues by pre-column derivatization with high-performance liquid chromatographic fluorescence detection and mass spectrometric identification.  


A sensitive and efficient method for simultaneous determination of glutamic acid (Glu), gamma-amino-butyric acid (GABA), dopamine (DA), 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) in rat endbrains was developed by high-performance liquid chromatography (HPLC) with fluorescence detection and on-line mass spectrometric identification following derivatization with 1,2-benzo-3,4-dihydrocarbazole-9-ethyl chloroformate (BCEOC). Different parameters which influenced derivatization and separation were optimized. The complete separation of five neurotransmitter (NT) derivatives was performed on a reversed-phase Hypersil BDS-C(18) column with a gradient elution. The rapid structure identification of five neurotransmitter derivatives was carried out by on-line mass spectrometry with electrospray ionization (ESI) source in positive ion mode, and the BCEOC-labeled derivatives were characterized by easy-to-interpret mass spectra. Stability of derivatives, repeatability, precision and accuracy were evaluated and the results were excellent for efficient HPLC analysis. The quantitative linear range of five neurotransmitters were 2.441-2x10(4) nM, and limits of detection were in the range of 0.398-1.258 nM (S/N=3:1). The changes of their concentrations in endbrains of three rat groups were also studied using this HPLC fluorescence detection method. The results indicated that exhausting exercise could obviously influence the concentrations of neurotransmitters in rat endbrains. The established method exhibited excellent validity, high sensitivity and convenience, and provided a new technique for simultaneous analysis of monoamine and amino acid neurotransmitters in rat brain. PMID:18585341

Zhao, Xian-En; Suo, You-Rui



GABA-Activated Chloride Channels in Secretory Nerve Endings  

NASA Astrophysics Data System (ADS)

Neurotransmitters acting on presynaptic terminals regulate synaptic transmission and plasticity. Because of the difficulty of direct electrophysiological recording from small presynaptic terminals, little is known about the ion channels that mediate these actions or about the mechanisms by which transmitter secretion is altered. The patch-clamp technique is used to show that the predominant inhibitory presynaptic neurotransmitter, ?-aminobutyric acid (GABA), activates a GABA_A receptor and gates a chloride channel in the membranes of peptidergic nerve terminals of the posterior pituitary. The opening of a chloride channel by GABA weakly depolarizes the nerve terminal membrane and blocks action potentials. In this way, GABA limits secretion by retarding the spread of excitation into the terminal arborization.

Zhang, Shuanglin J.; Jackson, Meyer B.



Pharmacology of GABA receptor CI channels in rat retinal bipolar cells  

Microsoft Academic Search

gamma-AMlNOBUTYRlC acid (GABA), a major inhibitory neurotransmitter in the mammalian nervous system, is known to operate bicuculline-sensitive CI- channels through GABAA receptors and bicuculline-insensitive cation channels through GABAB receptors1,2. Recent observations indicate that the retina may contain GABA receptors with unusual pharmacological properties3-5. Here we report that GABA gates bicuculline-insensitive CI- channels in rod bipolar cells of the rat retina,

Andreas Feigenspan; Heinz Wässle; Joachim Bormann



Expression and Functional Characterization of GABA Transporters in Crayfish Neurosecretory Cells  

Microsoft Academic Search

The effect of GABA on membrane potential and ionic cur- rents of X-organ neurons isolated from the crayfish eyestalk was investigated. Under voltage-clamp conditions, GABA elicited an inward Na current followed by a sustained out- ward chloride current. Sodium current was partially blocked in a dose-dependent manner by antagonists of GABA plasma membrane transporters such as -alanine, nipecotic acid, 1-(2(((diphenylmethylene)imino)oxy)ethyl)-1,2,5,6-tetrahydro-3-

Julieta Garduno; Sergio Elenes; Jorge Cebada; Elizabeth Becerra; Ubaldo Garcia



Effects of some anticonvulsant drugs on brain GABA level and GAD and GABA-T activities  

Microsoft Academic Search

The effect of anticonvulsant drugs was examined on brain GABA levels and GAD and GABA-T activities. The level of GABA was increased by the treatment with diphenylhydantoin. The drug had no effect on GABA-T activity, whereas GAD activity was inhibited. Carbamazepine increased the GABA level but did not effect GAD and GABA-T activities. Diazepam had no effect on GABA level

Leontino Battistin; Mary Varotto; Giorgio Berlese; Giovanni Roman



Relative efficacies of 1,4-diazepines on GABA-stimulated chloride influx in rat brain vesicles.  


The effects of 1,4-diazepines with two annelated heterocycles [brotizolam (WE 941), ciclotizolam (WE 973) and WE 1008] on gamma-aminobutyric acid (GABA)-stimulated chloride influx into rat brain membrane vesicles were examined. Brotizolam enhanced GABA (30 microM)-stimulated 36Cl- influx (146.1% of control), while ciclotizolam and WE 1008 showed only a small enhancement (119.3% and 119.1%, respectively) of GABA-stimulated 36Cl- uptake. Brotizolam resulted in a left shift of the GABA dose response curve at lower concentrations of GABA (10 microM), while at higher concentrations of GABA (1 mM), brotizolam caused a reduction of the maximal response. The enhancement of GABA-stimulated 36Cl- uptake by brotizolam (0.1 microM) was antagonized by Ro 15-1788. At higher concentration of GABA (300 microM), brotizolam inhibited GABA-stimulated 36Cl- uptake in a dose dependent manner and Ro15-1788 failed to antagonize this effect. These results suggest that 1) brotizolam produces an enhancement of GABA (30 microM)-stimulated chloride influx through the benzodiazepine receptor. 2) brotizolam inhibition of GABA (300 microM)-stimulated chloride influx involves an additional mechanism, and 3) the sedative-hypnotic action of brotizolam may be related to its high efficacy at the benzodiazepine/GABA-gated chloride channel. PMID:2569655

Ikeda, M; Weber, K H; Bechtel, W D; Malatynska, E; Yamamura, H I



Cerebellar Cortex: Computation by Extrasynaptic Inhibition?  

E-print Network

receptors for the inhibitory neurotransmitter -amino butyric acid (GABA) has now led to some fundamental cortex, inhibitory inputs to granule cells exhibit prominent tonic and spillover compo- nents resulting. The glomeruli also contain GABAergic synapses that inhibitory Golgi cells make with the granule cells

De Schutter, Erik


TIFR Centre for Interdisciplinary Sciences, Narsingi, Hyderabad 500075  

E-print Network

are mediated by two different neurotransmitters- glutamate and -amino butyric acid (GABA) at excitatory synapses and inhibitory synapses respectively. These transmitters are released by two different types of neurons in the brain- excitatory principal cells and inhibitory interneurons. Research over the past 25

Shyamasundar, R.K.


Frontiers in Synaptic Neuroscience May 2010 | Volume 2 | Article 4 | 1 SYNAPTIC NEUROSCIENCE  

E-print Network

on the two primary, opposing central neurotransmitters, glutamate and -amino-butyric acid (GABA). Their respective excitatory and inhibitory synapses are characteristically divergent in a range of features, but rather reside on dendritic shafts, nerve cell somata and axon initial segments. These inhibitory synapses

Broadie, Kendal S.


In vivo measurements of glutamate, GABA, and NAAG in schizophrenia.  


The major excitatory and inhibitory neurotransmitters, glutamate (Glu) and gamma-aminobutyric acid (GABA), respectively, are implicated in the pathophysiology of schizophrenia. N-acetyl-aspartyl-glutamate (NAAG), a neuropeptide that modulates the Glu system, may also be altered in schizophrenia. This study investigated GABA, Glu + glutamine (Glx), and NAAG levels in younger and older subjects with schizophrenia. Forty-one subjects, 21 with chronic schizophrenia and 20 healthy controls, participated in this study. Proton magnetic resonance spectroscopy ((1)H-MRS) was used to measure GABA, Glx, and NAAG levels in the anterior cingulate (AC) and centrum semiovale (CSO) regions. NAAG in the CSO was higher in younger schizophrenia subjects compared with younger control subjects. The opposite pattern was observed in the older groups. Glx was reduced in the schizophrenia group irrespective of age group and brain region. There was a trend for reduced AC GABA in older schizophrenia subjects compared with older control subjects. Poor attention performance was correlated to lower AC GABA levels in both groups. Higher levels of CSO NAAG were associated with greater negative symptom severity in schizophrenia. These results provide support for altered glutamatergic and GABAergic function associated with illness course and cognitive and negative symptoms in schizophrenia. The study also highlights the importance of studies that combine MRS measurements of NAAG, GABA, and Glu for a more comprehensive neurochemical characterization of schizophrenia. PMID:23081992

Rowland, Laura M; Kontson, Kimberly; West, Jeffrey; Edden, Richard A; Zhu, He; Wijtenburg, S Andrea; Holcomb, Henry H; Barker, Peter B



Simulated ?-aminobutyric acid (GABA) synaptic input and L-type calcium channels form functional microdomains in hypothalamic gonadotropin releasing-hormone (GnRH) neurons  

PubMed Central

Hypothalamic gonadotropin releasing-hormone neurons integrate the multiple internal and external cues that regulate sexual reproduction. In contrast to other neurons which exhibit extensive dendritic arbors, GnRH neurons usually have a single dendrite with relatively little branching. This largely precludes the integration strategy where a single dendritic branch serves as a unit of integration. In the present study, we identify a gradient in L-type calcium channels in dendrites of mouse GnRH neurons and its interaction with GABAergic and glutamatergic inputs. Higher levels of L-type calcium channels are in somata/proximal dendrites (i.e. 0–26 ?m) and distal dendrites (~130 ?m dendrite length) but intervening mid-lengths of dendrite (~27–130 ?m) have reduced L-type calcium channels. Using uncaging of GABA, there is a decreasing GABAergic influence along the dendrite and the impact of GABA-A receptors is dependent on activation of L-type calcium channels. This results in amplification of proximal GABAergic signals and attenuation of distal dendritic signals. Most interestingly, the intervening dendritic regions create a filter through which only relatively high amplitude, low frequency GABAergic signaling to dendrites elicits action potentials. The findings of the present study suggest that GnRH dendrites adopt an integration strategy whereby segments of single non-branching GnRH dendrites create functional microdomains and thus serve as units of integration. PMID:22745478

Hemond, Peter J.; O’Boyle, Michael P.; Roberts, Carson B.; Delgado-Reyes, Alfonso; Hemond, Zoe; Suter, Kelly J.



Immunocytochemistry of GABA in the antennal lobes of the sphinx moth Manduca sexta  

Microsoft Academic Search

We have prepared and characterized specific rabbit antisera against ?-aminobutyric acid (GABA) coupled covalently to bovine serum albumin and keyhole-limpet hemocyanin. Using these antisera in immunocytochemical staining procedures, we have probed the antennal lobes and their afferent and efferent fiber tracts in the sphinx moth Manduca sexta for GABA-like immunoreactivity in order to map putatively GABAergic central neurons in the

Sally G. Hoskins; Uwe Homberg; Timothy G. Kingan; Thomas A. Christensen; John G. Hildebrand



Structure, pharmacology and function of GABA A receptors in cochlear outer hair cells  

Microsoft Academic Search

There is evidence that the inhibitory neurotransmitter ?-aminobutyric acid (GABA) is released from some efferent olivocochlear nerve endings terminating at outer hair cells (OHCs). Using monoclonal antibodies against postsynaptic GABAA receptor from bovine cerebral cortex we confirm the presence of GABA and benzodiazepine bindings sites of a- and ß-subunits of GABAA receptors at the basal pole of isolated OHCs. Whole-cell

P. K. Plinkert; A. H. Gitter; H. Möhler; H. P. Zenner



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


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

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



Excitatory actions of GABA in the intact neonatal rodent hippocampus in vitro  

PubMed Central

The excitatory action of gamma-aminobutyric acid (GABA) is considered to be a hallmark of the developing nervous system. However, in immature brain slices, excitatory GABA actions may be secondary to neuronal injury during slice preparation. Here, we explored GABA actions in the rodent intact hippocampal preparations and at different depths of hippocampal slices during the early post-natal period [post-natal days (P) 1–7]. We found that in the intact hippocampus at P1–3: (i) GABA exerts depolarizing action as seen in cell-attached single GABA(A) channel recordings; (ii) GABA(A) receptor (GABA(A)-R) agonist isoguvacine and synaptic activation of the GABA(A)-Rs increase the frequency of multiple unit activity and the frequency of the network-driven giant depolarizing potentials (GDPs); and that (iii) Na+–K+–2Cl- cotransporter (NKCC1) antagonist bumetanide suppresses GDPs and the excitatory actions of isoguvacine. In the hippocampal slices at P2–5, isoguvacine and synaptic activation of GABA(A)-Rs-evoked excitatory responses at all slice depths, including surface and core. Thus, GABA exerts excitatory actions in the intact hippocampus (P1–3) and at all depths of hippocampal slices (P2–5). Therefore, the excitatory actions of GABA in hippocampal slices during the first post-natal days are not due to neuronal injury during slice preparation, and the trauma-related excitatory GABA actions at the slice surface are a fundamentally different phenomenon observed during the second post-natal week. PMID:23467988

Valeeva, Guzel; Valiullina, Fliza; Khazipov, Roustem



Lactate-Induced Release of GABA in the Ventromedial Hypothalamus Contributes to Counterregulatory Failure in Recurrent Hypoglycemia and Diabetes  

PubMed Central

Suppression of GABAergic neurotransmission in the ventromedial hypothalamus (VMH) is crucial for full activation of counterregulatory responses to hypoglycemia, and increased ?-aminobutyric acid (GABA) output contributes to counterregulatory failure in recurrently hypoglycemic (RH) and diabetic rats. The goal of this study was to establish whether lactate contributes to raising VMH GABA levels in these two conditions. We used microdialysis to deliver artificial extracellular fluid or l-lactate into the VMH and sample for GABA. We then microinjected a GABAA receptor antagonist, an inhibitor of lactate transport (4CIN), or an inhibitor of lactate dehydrogenase, oxamate (OX), into the VMH prior to inducing hypoglycemia. To assess whether lactate contributes to raising GABA in RH and diabetes, we injected 4CIN or OX into the VMH of RH and diabetic rats before inducing hypoglycemia. l-lactate raised VMH GABA levels and suppressed counterregulatory responses to hypoglycemia. While blocking GABAA receptors did not prevent the lactate-induced rise in GABA, inhibition of lactate transport or utilization did, despite the presence of lactate. All three treatments restored the counterregulatory responses, suggesting that lactate suppresses these responses by enhancing GABA release. Both RH and diabetic rats had higher baseline GABA levels and were unable to reduce GABA levels sufficiently to fully activate counterregulatory responses during hypoglycemia. 4CIN or OX lowered VMH GABA levels in both RH and diabetic rats and restored the counterregulatory responses. Lactate likely contributes to counterregulatory failure in RH and diabetes by increasing VMH GABA levels. PMID:23939392

Chan, Owen; Paranjape, Sachin A.; Horblitt, Adam; Zhu, Wanling; Sherwin, Robert S.



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

E-print Network

, Marseille, France; and yInserm U666, Strasbourg, France SUMMARY Brain slices incubated with glucose have suggested that c-aminobutyric acid (GABA) excites neonatal neurons in conventional glucose-perfused slices the excitatory actions of GABA on neonatal neu- rons. In contrast, lactate, like other weak acids, can pro- duce

Cossart, Rosa


Potentiation of the ionotropic GABA receptor response by whiskey fragrance.  


It is well-known that the target of most mood-defining compounds is an ionotropic gamma-aminobutyric acid receptor (GABA(A) receptor). The potentiation of the response of these inhibitory neurotransmitter receptors induces anxiolytic, sedative, and anesthetic activity in the human brain. To study the effects of whiskey fragrance on the GABA(A) receptor-mediated response, GABA(A) receptors were expressed in Xenopus oocyte by injecting rat whole brain mRNA or cRNA prepared from the cloned cDNA for the alpha(1) and beta(1) subunits of the bovine receptors. Most whiskey components such as phenol, ethoxy, and lactone derivatives potentiated the electrical responses of GABA(A) receptors, especially ethyl phenylpropanoate (EPP), which strongly potentiated the response. When this compound was applied to mice through respiration, the convulsions induced by pentetrazole were delayed, suggesting that EPP was absorbed by the brain, where it could potentiate the GABA(A) receptor responses. The extract of other alcoholic drinks such as wine, sake, brandy, and shochu also potentiated the responses to varying degrees. Although these fragrant components are present in alcoholic drinks at low concentrations (extremely small quantities compared with ethanol), they may also modulate the mood or consciousness of the human through the potentiation of the GABA(A) receptor response after absorption into the brain, because these hydrophobic fragrant compounds are easily absorbed into the brain through the blood-brain barrier and are several thousands times as potent as ethanol in the potentiation of the GABA(A) receptor-mediated response. PMID:12405783

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



GABA as an Inhibitory Neurotransmitter in Human Cerebral Cortex  

Microsoft Academic Search

1. The possible role of y-aminobutyric acid (GABA) as an in- hibitory neurotransmitter in the human cerebral cortex was in- vestigated with the use of intracellular recordings from neocorti- cal slices maintained in vitro. 2. Electrical stimulation of afferents to presumed pyramidal cells resulted in an initial excitatory postsynaptic potential (EPSP) followed by fast and slow inhibitory postsynaptic potentials (IPSPs).




GABA accumulation causes cell elongation defects and a decrease in expression of genes encoding secreted and cell wall-related proteins in Arabidopsis thaliana.  


GABA (?-aminobutyric acid), a non-protein amino acid, is a signaling factor in many organisms. In plants, GABA is known to accumulate under a variety of stresses. However, the consequence of GABA accumulation, especially in vegetative tissues, remains poorly understood. Moreover, gene expression changes as a consequence of GABA accumulation in plants are largely unknown. The pop2 mutant, which is defective in GABA catabolism and accumulates GABA, is a good model to examine the effects of GABA accumulation on plant development. Here, we show that the pop2 mutants have pollen tube elongation defects in the transmitting tract of pistils. Additionally, we observed growth inhibition of primary root and dark-grown hypocotyl, at least in part due to cell elongation defects, upon exposure to exogenous GABA. Microarray analysis of pop2-1 seedlings grown in GABA-supplemented medium revealed that 60% of genes whose expression decreased encode secreted proteins. Besides, functional classification of genes with decreased expression in the pop2-1 mutant showed that cell wall-related genes were significantly enriched in the microarray data set, consistent with the cell elongation defects observed in pop2 mutants. Our study identifies cell elongation defects caused by GABA accumulation in both reproductive and vegetative tissues. Additionally, our results show that genes that encode secreted and cell wall-related proteins may mediate some of the effects of GABA accumulation. The potential function of GABA as a growth control factor under stressful conditions is discussed. PMID:21471118

Renault, Hugues; El Amrani, Abdelhak; Palanivelu, Ravishankar; Updegraff, Emily P; Yu, Agnès; Renou, Jean-Pierre; Preuss, Daphne; Bouchereau, Alain; Deleu, Carole



GABA Accumulation Causes Cell Elongation Defects and a Decrease in Expression of Genes Encoding Secreted and Cell Wall-Related Proteins in Arabidopsis thaliana  

PubMed Central

GABA (?-aminobutyric acid), a non-protein amino acid, is a signaling factor in many organisms. In plants, GABA is known to accumulate under a variety of stresses. However, the consequence of GABA accumulation, especially in vegetative tissues, remains poorly understood. Moreover, gene expression changes as a consequence of GABA accumulation in plants are largely unknown. The pop2 mutant, which is defective in GABA catabolism and accumulates GABA, is a good model to examine the effects of GABA accumulation on plant development. Here, we show that the pop2 mutants have pollen tube elongation defects in the transmitting tract of pistils. Additionally, we observed growth inhibition of primary root and dark-grown hypocotyl, at least in part due to cell elongation defects, upon exposure to exogenous GABA. Microarray analysis of pop2-1 seedlings grown in GABA-supplemented medium revealed that 60% of genes whose expression decreased encode secreted proteins. Besides, functional classification of genes with decreased expression in the pop2-1 mutant showed that cell wall-related genes were significantly enriched in the microarray data set, consistent with the cell elongation defects observed in pop2 mutants. Our study identifies cell elongation defects caused by GABA accumulation in both reproductive and vegetative tissues. Additionally, our results show that genes that encode secreted and cell wall-related proteins may mediate some of the effects of GABA accumulation. The potential function of GABA as a growth control factor under stressful conditions is discussed. PMID:21471118

Renault, Hugues; El Amrani, Abdelhak; Palanivelu, Ravishankar; Updegraff, Emily P.; Yu, Agnès; Renou, Jean-Pierre; Preuss, Daphne; Bouchereau, Alain; Deleu, Carole



Actions of insecticides on the insect GABA receptor complex  

SciTech Connect

The actions of insecticides on the insect gamma-aminobutyric acid (GABA) receptor were investigated using (35S)t-butylbicyclophosphorothionate (( 35S)TBPS) binding and voltage-clamp techniques. Specific binding of (35S)TBPS to a membrane homogenate derived from the brain of Locusta migratoria locusts is characterised by a Kd value of 79.3 {plus minus} 2.9 nM and a Bmax value of 1770 {plus minus} 40 fmol/mg protein. (35S)TBPS binding is inhibited by mM concentrations of barbiturates and benzodiazepines. In contrast dieldrin, ivermectin, lindane, picrotoxin and TBPS are inhibitors of (35S)TBPS binding at the nanomolar range. Bicuculline, baclofen and pyrethroid insecticides have no effect on (35S)TBPS binding. These results are similar to those obtained in electrophysiological studies of the current elicited by GABA in both Locusta and Periplaneta americana central neurones. Noise analysis of the effects of lindane, TBPS, dieldrin and picrotoxin on the cockroach GABA responses reveals that these compounds decrease the variance of the GABA-induced current but have no effect on its mean open time. All these compounds, with the exception of dieldrin, significantly decrease the conductance of GABA-evoked single current.

Bermudez, I.; Hawkins, C.A.; Taylor, A.M.; Beadle, D.J. (School of Biological and Molecular Sciences, Oxford Polytechnic, Headington, Oxford (England))



Microperfusion of 3-MPA into the brain augments GABA  

PubMed Central

In vivo effects of microperfusion of a GABA synthesis inhibitor (3-MPA) into the striatum and hippocampus on amino acid concentrations and electrical neuronal activity were investigated. Paradoxical elevations in GABA in the striatum (5-fold in anesthetized and 50-fold in awake rats) and hippocampus (2-fold in anesthetized and 15-fold in awake rats) were documented under steady-state concentrations of 3-MPA along with expected increases in glutamate (a 15-fold increase and a 250-fold increase in the striatum of anesthetized and awake rats, respectively; a 7-fold increase and a 25-fold increase in the hippocampus of anesthetized and awake rats, respectively). There was no clear epileptiform or seizure activity. Explanations for the paradoxical increase in GABA are offered, and emphasis is placed on the dependency of disinhibition on the model in which its effects are studied as well as on the prevailing level of activation of the probed network. PMID:24094842

Mayer, Andrew P.; Osorio, Ivan; Lunte, Craig E.



Effects of valproate and other antiepileptic drugs on brain glutamate, glutamine, and GABA in patients with refractory complex partial seizures  

Microsoft Academic Search

Preclinical studies suggested valproate increased brain ?-aminobutyric acid (GABA) with no major effects on brain glutamate or glutamine. Valproate increased human cerebrospinal fluid GABA and glutamine in some studies; others reported no effect.In vivomeasurements of glutamate, glutamine, and GABA were made of a 14 cm3volume in the occipital cortex using a1H spectroscopy with a 2.1 Tesla magnetic resonance spectrometer and

O. A. C. Petroff; D. L. Rothman; K. L. Behar; F. Hyder; R. H. Mattson



GABA-shunt enzymes activity in GH3 cells with reduced level of PMCA2 or PMCA3 isoform  

SciTech Connect

Highlights: {yields} Suppression of PMCA2 or PMCA3 slows down proliferation of GH3 cells. {yields} PMCA2 suppression lowers the activity of GABA-shunt enzymes. {yields} PMCA3 suppression increases the expression of glutamate decarboxylase 65. {yields} PMCA2 and PMCA3 function appears to be linked to regulation of GABA metabolism. -- Abstract: GABA ({gamma}-aminobutyric acid) is important neurotransmitter and regulator of endocrine functions. Its metabolism involves three enzymes: glutamate decarboxylase (GAD65 and GAD67), GABA aminotransferase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH). As many cellular processes GABA turnover can depend on calcium homeostasis, which is maintained by plasma membrane calcium ATPases (PMCAs). In excitable cells PMCA2 and PMCA3 isoforms are particularly important. In this study we focused on GABA-metabolizing enzymes expression and activity in rat anterior pituitary GH3 cells with suppressed expression of PMCA2 or PMCA3. We observed that PMCA3-reduced cells have increased GAD65 expression. Suppression of PMCA2 caused a decrease in total GAD and GABA-T activity. These results indicate that PMCA2 and PMCA3 presence may be an important regulatory factor in GABA metabolism. Results suggest that PMCA2 and PMCA3 function is rather related to regulation of GABA synthesis and degradation than supplying cells with metabolites, which can be potentially energetic source.

Kowalski, Antoni, E-mail: [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland)] [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland); Zylinska, Ludmila, E-mail: [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland)] [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland); Boczek, Tomasz, E-mail: [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland)] [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland); Rebas, Elzbieta, E-mail: [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland)] [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland)



GABA Concentration in Posterior Cingulate Cortex Predicts Putamen Response during Resting State fMRI  

PubMed Central

The role of neurotransmitters in the activity of resting state networks has been gaining attention and has become a field of research with magnetic resonance spectroscopy (MRS) being one of the key techniques. MRS permits the measurement of ?-aminobutyric acid (GABA) and glutamate levels, the central biochemical constituents of the excitation-inhibition balance in vivo. The inhibitory effects of GABA in the brain have been largely investigated in relation to the activity of resting state networks in functional magnetic resonance imaging (fMRI). In this study GABA concentration in the posterior cingulate cortex (PCC) was measured using single voxel spectra acquired with standard point resolved spectroscopy (PRESS) from 20 healthy male volunteers at 3 T. Resting state fMRI was consecutively measured and the values of GABA/Creatine+Phosphocreatine ratio (GABA ratio) were included in a general linear model matrix as a step of dual regression analysis in order to identify voxels whose neuroimaging metrics during rest were related to individual levels of the GABA ratio. Our data show that the connection strength of putamen to the default-mode network during resting state has a negative linear relationship with the GABA ratio measured in the PCC. These findings highlight the role of PCC and GABA in segregation of the motor input, which is an inherent condition that characterises resting state. PMID:25184505

Arrubla, Jorge; Tse, Desmond H. Y.; Amkreutz, Christin; Neuner, Irene; Shah, N. Jon



GABA concentration in posterior cingulate cortex predicts putamen response during resting state fMRI.  


The role of neurotransmitters in the activity of resting state networks has been gaining attention and has become a field of research with magnetic resonance spectroscopy (MRS) being one of the key techniques. MRS permits the measurement of ?-aminobutyric acid (GABA) and glutamate levels, the central biochemical constituents of the excitation-inhibition balance in vivo. The inhibitory effects of GABA in the brain have been largely investigated in relation to the activity of resting state networks in functional magnetic resonance imaging (fMRI). In this study GABA concentration in the posterior cingulate cortex (PCC) was measured using single voxel spectra acquired with standard point resolved spectroscopy (PRESS) from 20 healthy male volunteers at 3 T. Resting state fMRI was consecutively measured and the values of GABA/Creatine+Phosphocreatine ratio (GABA ratio) were included in a general linear model matrix as a step of dual regression analysis in order to identify voxels whose neuroimaging metrics during rest were related to individual levels of the GABA ratio. Our data show that the connection strength of putamen to the default-mode network during resting state has a negative linear relationship with the GABA ratio measured in the PCC. These findings highlight the role of PCC and GABA in segregation of the motor input, which is an inherent condition that characterises resting state. PMID:25184505

Arrubla, Jorge; Tse, Desmond H Y; Amkreutz, Christin; Neuner, Irene; Shah, N Jon



Effect of GABA, a Bacterial Metabolite, on Pseudomonas fluorescens Surface Properties and Cytotoxicity.  


Different bacterial species and, particularly Pseudomonas fluorescens, can produce gamma-aminobutyric acid (GABA) and express GABA-binding proteins. In this study, we investigated the effect of GABA on the virulence and biofilm formation activity of different strains of P. fluorescens. Exposure of a psychotropic strain of P. fluorescens (MF37) to GABA (10-5 M) increased its necrotic-like activity on eukaryotic (glial) cells, but reduced its apoptotic effect. Conversely, muscimol and bicuculline, the selective agonist and antagonist of eukaryote GABAA receptors, respectively, were ineffective. P. fluorescens MF37 did not produce biosurfactants, and its caseinase, esterase, amylase, hemolytic activity or pyoverdine productions were unchanged. In contrast, the effect of GABA was associated to rearrangements of the lipopolysaccharide (LPS) structure, particularly in the lipid A region. The surface hydrophobicity of MF37 was marginally modified, and GABA reduced its biofilm formation activity on PVC, but not on glass, although the initial adhesion was increased. Five other P. fluorescens strains were studied, and only one, MFP05, a strain isolated from human skin, showed structural differences of biofilm maturation after exposure to GABA. These results reveal that GABA can regulate the LPS structure and cytotoxicity of P. fluorescens, but that this property is specific to some strains. PMID:23743829

Dagorn, Audrey; Chapalain, Annelise; Mijouin, Lily; Hillion, Mélanie; Duclairoir-Poc, Cécile; Chevalier, Sylvie; Taupin, Laure; Orange, Nicole; Feuilloley, Marc G J



Temperature dependence and GABA modulation of (TH)triazolam binding in the rat brain  

SciTech Connect

The hypnotic triazolam (TZ), a triazolobenzodiazepine displays a short physiological half life and has been used for the treatment of insomnia related to anxiety states. The authors major objectives were the direct measurement of the temperature dependence and the gamma-aminobutyric acid (GABA) effect of (TH)TZ binding in the rat brain. Saturation studies showed a shift to lower affinity with increasing temperatures (K/sub d/ = 0.27 +/- 08 nM at 0C; K/sub d/ = 1.96 +/- 0.85 nM at 37C) while the B/sub max/ values remained unchanged (1220 +/- 176 fmoles/mg protein at 0C and 1160 +/- 383 fmoles/mg protein at 37C). Saturation studies of (TH)TZ binding in the presence or absence of GABA (100 M) showed a GABA-shift. At 0C the K/sub d/ values were (K/sub d/ = 0.24 +/- 0.03 nM/-GABA; K/sub d/ = 0.16 +/- 0.04/+GABA) and at 37C the K/sub d/ values were (K/sub d/ = 1.84 +/- 0.44 nM/-GABA; K/sub d/ = 0.95 +/- 0.29 nM/+GABA). In contrast to reported literature, the authors findings show that TZ interacts with benzodiazepine receptors with a temperature dependence and GABA-shift consistent with predicted behavior for benzodiazepine agonists. 20 references, 3 tables.

Earle, M.E.; Concas, A.; Wamsley, J.K.; Yamamura, H.I.



Oncosecretomics coupled to bioenergetics identifies ?-amino adipic acid, isoleucine and GABA as potential biomarkers of cancer: Differential expression of c-Myc, Oct1 and KLF4 coordinates metabolic changes.  


Bioenergetic profiling of tumors is a new challenge of cancer research and medicine as therapies are currently being developed. Meanwhile, methodological means must be proposed to gather information on tumor metabolism in order to adapt these potential therapies to the bioenergetic specificities of tumors. Studies performed on tumors and cancer cell lines have shown that cancer cells bioenergetics is highly variable. This profile changes with microenvironmental conditions (eg. substrate availability), the oncogenes activated (and the tumor suppressors inactivated) and the interaction with the stroma (i.e. reverse Warburg effect). Here, we assessed the power of metabolic footprinting (MFP) to unravel the bioenergetics and associated anabolic changes induced by three oncogenes, c-Myc, KLF4 and Oct1. The MFP approach provides a quantitative analysis of the metabolites secreted and consumed by cancer cells. We used ultra performance liquid chromatography for quantifying the amino acid uptake and secretion. To investigate the potential oncogene-mediated alterations in mitochondrial metabolism, we measured oxygen consumption rate and ATP production as well as the glucose uptake and lactate release. Our findings show that c-Myc deficiency initiates the Warburg effect along with a reduction of mitochondrial respiration. KLF4 deficiency also stimulated glycolysis, albeit without cellular respiration impairment. In contrast, Oct1 deficiency reduced glycolysis and enhanced oxidative phosphorylation efficiency. MFP revealed that c-Myc, KLF4 and Oct1 altered amino acid metabolism with specific patterns. We identified isoleucine, ?-aminoadipic acid and GABA (?-aminoisobutyric acid) as biomarkers related. Our findings establish the impact of Oct1, KLF4 and c-Myc on cancer bioenergetics and evidence a link between oncosecretomics and cellular bioenergetics profile. PMID:22842522

Bellance, Nadège; Pabst, Lisa; Allen, Genevara; Rossignol, Rodrigue; Nagrath, Deepak



Co-localized GABA and somatostatin use different ionic mechanisms to hyperpolarize target neurons in the lamprey spinal cord.  


gamma-Aminobutyric acid (GABA) and somatostatin are co-localized in cells close to the central canal in the lamprey. These cells project to the lateral margin of the spinal cord where they form a GABA and somatostatin containing plexus. Stretch receptor neurons (edge cells) are situated along the lateral margin of the spinal cord and their dendrites extend into the GABA and somatostatin containing plexus. To investigate whether GABA and/or somatostatin exert an affect on edge cells, these putative transmitters were applied from extracellular pipettes onto edge cells during intracellular recordings. Both GABA and somatostatin hyperpolarized the edge cells but through different ionic mechanisms. GABA activated a chloride current while somatostatin activated a current most likely carried by potassium which, however, could not be blocked by any of the conventional potassium blockers. PMID:1687706

Christenson, J; Alford, S; Grillner, S; Hökfelt, T



Discriminative stimulus effects of gamma-hydroxybutyrate in pigeons: role of diazepam-sensitive and -insensitive GABA(A) and GABA(B) receptors.  


gamma-Hydroxybutyrate (GHB) is an emerging drug of abuse with multiple mechanisms of action. This study is part of an effort to examine the role of GHB, GABA(A), and GABA(B) receptors in the discriminative stimulus (DS) effects of GHB. In pigeons trained to discriminate 100 mg/kg GHB from saline, GHB and its precursors gamma-butyrolactone and 1,4-butanediol produced 80 to 100% GHB-appropriate responding, whereas other compounds such as morphine, naltrexone, cocaine, and haloperidol produced no more than 34%. Compounds interacting with GABA receptors produced different maximal levels of GHB-appropriate responding. For example, the GABA(A) agonist muscimol produced 3%; the GABA(A)-positive modulators diazepam, pentobarbital, and ethanol, and the GABA(B) agonist baclofen produced levels ranging from 54 to 73%; and the benzodiazepine antagonist flumazenil and inverse agonist Ro 15-4513 (ethyl 8-azido-6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-alpha]-[1,4]-benzodiazepine-3-carboxylate) both produced 96%. The putative GHB receptor antagonist (2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid (NCS-382) produced 70% GHB-appropriate responding. The GABA(B) antagonist (3-aminopropyl)(diethoxymethyl)phosphinic acid (CGP 35348) completely blocked the GHB-like DS effects of NCS-382 and baclofen at a dose of 56 mg/kg. CGP 35348 also blocked the DS effects of GHB, but incompletely and only at a dose of 560 mg/kg. Together, these results are consistent with a role for diazepam-sensitive and -insensitive GABA(A) and GABA(B) receptors in the DS effects of GHB. Together with previous findings, the present results suggest that diazepam-insensitive GABA(A) receptors are more prominently involved in the DS effects of GHB in pigeons than in rats, whereas GABA(B) receptors are less prominently involved. Exploring the role of GHB receptors with NCS-382 is hampered by its GABA(B) receptor-mediated, GHB-like agonist activity. PMID:14718595

Koek, Wouter; Flores, Lauren R; Carter, Lawrence P; Lamb, R J; Chen, Weibin; Wu, Huifang; Coop, Andrew; France, Charles P



Effects of nitric oxide and GABA interaction within ventrolateral medulla on cardiovascular responses during static muscle contraction  

Microsoft Academic Search

We hypothesized that nitric oxide (NO) has opposing roles in regulating cardiovascular responses within the rostral (RVLM) and caudal (CVLM) ventrolateral medulla by modulating release of ?-aminobutyric acid (GABA). We have measured GABA concentrations within the RVLM and CVLM during increases in mean arterial pressure (MAP) and heart rate (HR) following a 2-min tibial nerve stimulation-evoked static muscle contraction before

Surya M. Nauli; William J. Pearce; Ahmed Amer; Timothy J. Maher; Ahmmed Ally



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

ERIC Educational Resources Information Center

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

Raccuglia, Davide; Mueller, Uli



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

ERIC Educational Resources Information Center

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…

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



GABA May Act as a Self-Limiting Trophic Factor at Developing Synapses  

NSDL National Science Digital Library

Early in development, synapses with glycine or γ-aminobutyric acid (GABA)-gated chloride channels exhibit the ability to depolarize postsynaptic cells. As the synapses mature and the gradient of chloride ions across the cell membrane is altered, these neurotransmitters signal an inhibitory response, hyperpolarizing the membrane and decreasing neuronal excitability. Kriegstein and Owens discuss how GABA-stimulated up-regulation of the expression of the potassium chloride cotransporter KCC2 may be the mechanism underlying this synaptic switch.

Arnold R. Kriegstein (Columbia College of Physicians and Surgeons;Department of Neurology and Department of Pathology and at the Center for Neurobiology and Behavior REV); David F. Owens (Columbia College of Physicians and Surgeons;Department of Neurology and Department of Pathology and at the Center for Neurobiology and Behavior REV)



Effect of drug-induced increase of brain GABA levels on penicillin focus  

Microsoft Academic Search

Résmé L'acide amino-oxyacétique ou le di-n-propylacétate entrate entraînent und élévation du taux de GABA dans le cerveau chez le rat et le chat. Nous avons étudié l'influence de ces substances sur les décharges épileptiques induites par la pénicilline. En dépit de l'élévation du taux de GABA, aucume protection importante n'a pu être mise en évidence.

Z. Elazar; Zehava Gottesfeld



An association study between polymorphisms in five genes in glutamate and GABA pathway and paranoid schizophrenia  

Microsoft Academic Search

Dysfunctions of glutamatergic and GABAergic neurotransmission are two important hypotheses for the pathogenesis of schizophrenia. Thus, genes in the pathway are candidates for schizophrenia susceptibility. Phosphate-activated glutaminase (GLS), glutamine synthetase (GLUL), glutamic acid decarboxylase (GAD), GABA transaminase (ABAT) and succinic semialdehyde dehydrogenase (ALDH5A1) are five primary enzymes in glutamate and GABA synthetic and degradative pathway. In order to investigate the

Boyu Zhang; Yanbo Yuan; Yanbin Jia; Xin Yu; Qi Xu; Yucun Shen; Yan Shen




PubMed Central

Cl? transport is essential for lung development. Because gamma-aminobutyric acid (GABA) receptors allow the flow of negatively-charged Cl? ions across the cell membrane, we hypothesized that the expression of ionotropic GABA receptors are regulated in the lungs during development. We identified 17 GABA receptor subunits in the lungs by real-time PCR. These subunits were categorized into 4 groups: Group 1 had high mRNA expression during fetal stages and low in adults; Group 2 had steady expression to adult stages with a slight up-regulation at birth; Group 3 showed an increasing expression from fetal to adult lungs; and Group 4 displayed irregular mRNA fluctuations. The protein levels of selected subunits were also determined by Western blots and some subunits had protein levels that corresponded to mRNA levels. Further studied subunits were primarily localized in epithelial cells in the developing lung with differential mRNA expression between isolated cells and whole lung tissues. Our results add to the knowledge of GABA receptor expression in the lung during development. PMID:18539546

Jin, Nili; Guo, Yujie; Sun, Peng; Bell, Anna; Chintagari, Narendranath Reddy; Bhaskaran, Manoj; Rains, Kimberly; Baviskar, Pradyumna; Chen, Zhongming; Weng, Tingting; Liu, Lin



Action of tremorgenic mycotoxins on GABA/sub A/ receptor  

SciTech Connect

The effects of four tremorgenic and one nontremorgenic mycotoxins were studied on ..gamma..-aminobutyric acid (GABA/sub A/) receptor binding and function in rat brain and on binding of a voltage-operated Cl/sup -/ channel in Torpedo electric organ. None of the mycotoxins had significant effect on (/sup 3/H)muscimol or (/sup 3/H)flunitrazepam binding to the GAMA/sup A/ receptor. However, only the four tremorgenic mycotoxins inhibited GABA-induced /sup 36/Cl/sup -/ influx and (/sup 35/S)t-butylbicyclophosphorothionate ((/sup 35/S)TBPS) binding in rate brain membranes, while the nontremorgenic verruculotoxin had no effect. Inhibition of (/sup 35/S)TBPS binding by paspalinine was non-competitive. This suggests that tremorgenic mycotoxins inhibit GABA/sub A/ receptor function by binding close to the receptor's Cl/sup -/ channel. On the voltage-operated Cl/sup -/ channel, only high concentrations of verruculogen and verruculotoxin caused significant inhibition of the channel's binding of (/sup 35/S)TBPS. The data suggest that the tremorgenic action of these mycotoxins may be due in part to their inhibition of GABA/sub A/ receptor function. 21 references, 4 figures, 2 tables.

Gant, D.B.; Cole, R.J.; Valdes, J.J.; Eldefrawi, M.E.; Eldefrawi, A.T.



Comparison of taurine, GABA, Glu, and Asp as scavengers of malondialdehyde in vitro and in vivo  

NASA Astrophysics Data System (ADS)

The purpose of this study is to determine if amino acid neurotransmitters such as gamma-aminobutyric acid (GABA), taurine, glutamate (Glu), and aspartate (Asp) can scavenge activated carbonyl toxicants. In vitro, direct reaction between malondialdehyde (MDA) and amino acids was researched using different analytical methods. The results indicated that scavenging activated carbonyl function of taurine and GABA is very strong and that of Glu and Asp is very weak in pathophysiological situations. The results provided perspective into the reaction mechanism of taurine and GABA as targets of activated carbonyl such as MDA in protecting nerve terminals. In vivo, we studied the effect of taurine and GABA as antioxidants by detecting MDA concentration and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. It was shown that MDA concentration was decreased significantly, and the activities of SOD and GSH-Px were increased significantly in the cerebral cortex and hippocampus of acute epileptic state rats, after the administration of taurine and GABA. The results indicated that the peripherally administered taurine and GABA can scavenge free radicals and protect the tissue against activated carbonyl in vivo and in vitro.

Deng, Yan; Wang, Wei; Yu, Pingfeng; Xi, Zhijiang; Xu, Lijian; Li, Xiaolong; He, Nongyue



Comparison of taurine, GABA, Glu, and Asp as scavengers of malondialdehyde in vitro and in vivo  

PubMed Central

The purpose of this study is to determine if amino acid neurotransmitters such as gamma-aminobutyric acid (GABA), taurine, glutamate (Glu), and aspartate (Asp) can scavenge activated carbonyl toxicants. In vitro, direct reaction between malondialdehyde (MDA) and amino acids was researched using different analytical methods. The results indicated that scavenging activated carbonyl function of taurine and GABA is very strong and that of Glu and Asp is very weak in pathophysiological situations. The results provided perspective into the reaction mechanism of taurine and GABA as targets of activated carbonyl such as MDA in protecting nerve terminals. In vivo, we studied the effect of taurine and GABA as antioxidants by detecting MDA concentration and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. It was shown that MDA concentration was decreased significantly, and the activities of SOD and GSH-Px were increased significantly in the cerebral cortex and hippocampus of acute epileptic state rats, after the administration of taurine and GABA. The results indicated that the peripherally administered taurine and GABA can scavenge free radicals and protect the tissue against activated carbonyl in vivo and in vitro. PMID:23618076



Correlation between the enhancement of flunitrazepam binding by GABA and seizure susceptibility in mice  

SciTech Connect

Various populations of mice exhibit differential sensitivity to seizure-inducing agents. The relationship of seizure susceptibility to alterations in the GABA receptor complex was investigated in six different populations of mice consisting of four inbred strains (C57BL, DBA, C3H, and BALB) and two selected lines (long sleep and short sleep). Seizure activity was induced by intraperitoneal administration of the GAD inhibitor, 3-mercaptopropionic acid, and latencies to seizure onset and tonus were measured. In naive mice of the same populations, GABA enhancement of TH-flunitrazepam binding was measured in extensively washed whole brain membranes at several GABA concentrations. Both differential seizure sensitivity to 3-mercaptopropionic acid and differential enhancement of TH-flunitrazepam binding by GABA were observed in these six populations of mice. Correlational analyses indicated a positive correlation between the degree of GABA enhancement of TH-flunitrazepam binding and resistance to the seizure-inducing properties of 3-mercaptopropionic acid. These data suggest that genetic differences in sensitivity to seizure-inducing agents that disrupt the GABAergic system may be related to differences in coupling between the various receptors associated with the GABA receptor complex.

Marley, R.J.; Wehner, J.M.



GABA-elevating effects of the antidepressant\\/antipanic drug phenelzine in brain: effects of pretreatment with tranylcypromine, (?)-deprenyl and clorgyline  

Microsoft Academic Search

The antidepressant\\/antipanic drug phenelzine (PLZ) is both an inhibitor of, and a substrate for, monoamine oxidase (MAO). PLZ also causes an elevation of brain levels of the amino acid neurotransmitter ?-aminobutyric acid (GABA); this action can be reversed by pretreatment with the MAO inhibitor tranylcypromine (TCP), suggesting that the GABA-elevating effect is largely the result of a metabolite of PLZ

Kathryn G. Todd; Glen B. Baker



The Effects of Anticonvulsant Drugs on NMDA-EPSP, AMPA-EPSP, and GABA-IPSP in the Rat Hippocampus  

Microsoft Academic Search

The effects of phenobarbital, phenytoin, and valproic acid on pharmacologically isolated NMDA-EPSP, AMPA-EPSP, and GABA-IPSPs were examined in rat hippocampal slices. Phenobarbital (0.05 mg\\/ml) had no effect on the NMDA-EPSP, but decreased the slope of the AMPA-EPSP by 13.4% and facilitated the GABA-IPSP slope by 77.12%. Phenytoin (0.02 mg\\/ml) had no effects on the NMDA-EPSP, AMPA-EPSP, or GABA-IPSP. Valproic acid

Gladys Yi-Ping Lee Ko; Laurie M Brown-Croyts; Timothy J Teyler



GABA uptake and heterotransport are impaired in the dentate gyrus of epileptic rats and humans with temporal lobe sclerosis.  


In vivo dialysis and in vitro electrophysiological studies suggest that GABA uptake is altered in the dentate gyrus of human temporal lobe epileptics characterized with mesial temporal sclerosis (MTLE). Concordantly, anatomical studies have shown that the pattern of GABA-transporter immunoreactivity is also altered in this region. This decrease in GABA uptake, presumably due to a change in the GABA transporter system, may help preserve inhibitory tone interictally. However, transporter reversal can also occur under several conditions, including elevations in [K(+)]o, which occurs during seizures. Thus GABA transporters could contribute to seizure termination and propagation through heterotransport. To test whether GABA transport is compromised in both the forward (uptake) and reverse (heterotransport) direction in the sclerotic epileptic dentate gyrus, the physiological effects of microapplied GABA and nipecotic acid (NPA; a compound that induces heterotransport) were examined in granule cells in hippocampal slices from kainate (KA)-induced epileptic rats and patients with temporal lobe epilepsy (TLE). GABA- and NPA-induced responses were prolonged in granule cells from epileptic rats versus controls (51.3 and 31.3% increase, respectively) while the conductance change evoked with NPA microapplication was reduced by 40%. Furthermore the ratio of GABA/NPA conductance, but not duration, was significantly >1 in epileptic rats but not controls, suggesting a compromise in transporter function in both directions. Similar changes were observed in tissue resected from epileptic patients with medial temporal sclerosis but not in those without the anatomical changes associated with MTLE. These data suggest that the GABA transporter system is functionally compromised in both the forward and reverse directions in the dentate gyrus of chronically epileptic tissue characterized by mesial temporal sclerosis. This alteration may enhance inhibitory tone interically yet be permissive for seizure propagation due to a decreased probability for GABA heterotransport during seizures. PMID:11287477

Patrylo, P R; Spencer, D D; Williamson, A



Mood regulation. GABA/glutamate co-release controls habenula output and is modified by antidepressant treatment.  


The lateral habenula (LHb), a key regulator of monoaminergic brain regions, is activated by negatively valenced events. Its hyperactivity is associated with depression. Although enhanced excitatory input to the LHb has been linked to depression, little is known about inhibitory transmission. We discovered that ?-aminobutyric acid (GABA) is co-released with its functional opponent, glutamate, from long-range basal ganglia inputs (which signal negative events) to limit LHb activity in rodents. At this synapse, the balance of GABA/glutamate signaling is shifted toward reduced GABA in a model of depression and increased GABA by antidepressant treatment. GABA and glutamate co-release therefore controls LHb activity, and regulation of this form of transmission may be important for determining the effect of negative life events on mood and behavior. PMID:25237099

Shabel, Steven J; Proulx, Christophe D; Piriz, Joaquin; Malinow, Roberto



Distribution of GABA-like immunoreactive cell bodies in the brains of two amphibians, Rana catesbeiana and Xenopus laevis.  


The distribution of the neurotransmitter gamma-aminobutyric acid (GABA) is not well understood for non-mammalian vertebrates. We thus used immunocytochemistry to locate putative GABAergic cells in the brains of male bullfrogs (Rana catesbeiana) and South African clawed frogs (Xenopus laevis). GABA-immunoreactive cell bodies were broadly distributed throughout the brains of both species with similar general patterns. In both, the greatest numbers of GABA-positive cells were found in the olfactory bulb, thalamus, and optic tectum, but virtually no major brain region lacked GABAergic cells. Species differences were also apparent. The density of GABA-immunoreactive cells was substantially higher in many areas of the bullfrog brain, compared to Xenopus. Bullfrogs possessed extensive cell populations in the medial pallium, preoptic area, optic tectum, torus semicircularis and tegmentum but cells were fewer in these locations in Xenopus. In the bullfrog hindbrain, GABA-immunoreactive cell bodies were restricted to very narrow and distinct populations. In Xenopus, however, cells in a similar position were fewer and spread more extensively. The distribution of GABA cells in the brain of these two species supports the hypotheses that GABA is involved in control of olfaction, audition, vision and vocalization. However, differences in the distribution of GABA between the bullfrog and Xenopus suggest that the extent of the GABAergic influence might vary between species. PMID:15627724

Hollis, David M; Boyd, Sunny K



Structure, function, and plasticity of GABA transporters  

PubMed Central

GABA transporters belong to a large family of neurotransmitter:sodium symporters. They are widely expressed throughout the brain, with different levels of expression in different brain regions. GABA transporters are present in neurons and in astrocytes and their activity is crucial to regulate the extracellular concentration of GABA under basal conditions and during ongoing synaptic events. Numerous efforts have been devoted to determine the structural and functional properties of GABA transporters. There is also evidence that the expression of GABA transporters on the cell membrane and their lateral mobility can be modulated by different intracellular signaling cascades. The strength of individual synaptic contacts and the activity of entire neuronal networks may be finely tuned by altering the density, distribution and diffusion rate of GABA transporters within the cell membrane. These findings are intriguing because they suggest the existence of complex regulatory systems that control the plasticity of GABAergic transmission in the brain. Here we review the current knowledge on the structural and functional properties of GABA transporters and highlight the molecular mechanisms that alter the expression and mobility of GABA transporters at central synapses. PMID:24987330

Scimemi, Annalisa



Characterization of GABA/sub A/ receptor-mediated /sup 36/chloride uptake in rat brain synaptoneurosomes  

SciTech Connect

..gamma..-Aminobutyric acid (GABA) receptor-mediated /sup 36/chloride (/sup 36/Cl/sup -/) uptake was measured in synaptoneurosomes from rat brain. GABA and GABA agonists stimulated /sup 36/Cl/sup -/ uptake in a concentration-dependent manner with the following order of potency: Muscimol>GABA>piperidine-4-sulfonic acid (P4S)>4,5,6,7-tetrahydroisoxazolo-(5,4-c)pyridin-3-ol (THIP)=3-aminopropanesulfonic acid (3APS)>>taurine. Both P4S and 3APS behaved as partial agonists, while the GABA/sub B/ agonist, baclofen, was ineffective. The response to muscimol was inhibited by bicuculline and picrotoxin in a mixed competitive/non-competitive manner. Other inhibitors of GABA receptor-opened channels or non-neuronal anion channels such as penicillin, picrate, furosemide and disulfonic acid stilbenes also inhibited the response to muscimol. A regional variation in muscimol-stimulated /sup 36/Cl/sup -/ uptake was observed; the largest responses were observed in the cerebral cortex, cerebellum and hippocampus, moderate responses were obtained in the striatum and hypothalamus and the smallest response was observed in the pons-medulla. GABA receptor-mediated /sup 36/Cl/sup -/ uptake was also dependent on the anion present in the media. The muscinol response varied in media containing the following anions: Br/sup -/>Cl/sup -/greater than or equal toNO/sub 3//sup -/>I/sup -/greater than or equal toSCN/sup -/>>C/sub 3/H/sub 5/OO/sup -/greater than or equal toClO/sub 4//sup -/>F/sup -/, consistent with the relative anion permeability through GABA receptor-gated anion channels and the enhancement of convulsant binding to the GABA receptor-gated Cl/sup -/ channel. 43 references, 4 figures, 3 tables.

Luu, M.D.; Morrow, A.L.; Paul, S.M.; Schwartz, R.D.



Genome Sequence of Lactococcus lactis subsp. lactis NCDO 2118, a GABA-Producing Strain.  


Lactococcus lactis subsp. lactis NCDO 2118 is a nondairy lactic acid bacterium, a xylose fermenter, and a gamma-aminobutyric acid (GABA) producer isolated from frozen peas. Here, we report the complete genome sequence of L. lactis NCDO 2118, a strain with probiotic potential activity. PMID:25278529

Oliveira, Letícia C; Saraiva, Tessália D L; Soares, Siomar C; Ramos, Rommel T J; Sá, Pablo H C G; Carneiro, Adriana R; Miranda, Fábio; Freire, Matheus; Renan, Wendel; Júnior, Alberto F O; Santos, Anderson R; Pinto, Anne C; Souza, Bianca M; Castro, Camila P; Diniz, Carlos A A; Rocha, Clarissa S; Mariano, Diego C B; de Aguiar, Edgar L; Folador, Edson L; Barbosa, Eudes G V; Aburjaile, Flavia F; Gonçalves, Lucas A; Guimarães, Luís C; Azevedo, Marcela; Agresti, Pamela C M; Silva, Renata F; Tiwari, Sandeep; Almeida, Sintia S; Hassan, Syed S; Pereira, Vanessa B; Abreu, Vinicius A C; Pereira, Ulisses P; Dorella, Fernanda A; Carvalho, Alex F; Pereira, Felipe L; Leal, Carlos A G; Figueiredo, Henrique C P; Silva, Artur; Miyoshi, Anderson; Azevedo, Vasco



Effects of anticonvulsant drug gabapentin on the enzymes in metabolic pathways of glutamate and GABA  

Microsoft Academic Search

Gabapentin is a novel anticonvulsant drug. The anticonvulsant mechanism of gabapentin is not known. Based on the amino acid structure of gabapentin we explored its possible effects on glutamate and ?-aminobutyric acid (GABA) metabolism in brain as they may relate to its anticonvulsant mechanisms of action. Gabapentin was tested for its effects on seven enzymes in the metabolic pathways of

Arie Goldlust; Ti-Zhi Su; Devin F. Welty; Charles P. Taylor; Dale L. Oxender



Genome Sequence of Lactococcus lactis subsp. lactis NCDO 2118, a GABA-Producing Strain  

PubMed Central

Lactococcus lactis subsp. lactis NCDO 2118 is a nondairy lactic acid bacterium, a xylose fermenter, and a gamma-aminobutyric acid (GABA) producer isolated from frozen peas. Here, we report the complete genome sequence of L. lactis NCDO 2118, a strain with probiotic potential activity. PMID:25278529

Oliveira, Letícia C.; Saraiva, Tessália D. L.; Soares, Siomar C.; Ramos, Rommel T. J.; Sá, Pablo H. C. G.; Carneiro, Adriana R.; Miranda, Fábio; Freire, Matheus; Renan, Wendel; Júnior, Alberto F. O.; Santos, Anderson R.; Pinto, Anne C.; Souza, Bianca M.; Castro, Camila P.; Diniz, Carlos A. A.; Rocha, Clarissa S.; Mariano, Diego C. B.; de Aguiar, Edgar L.; Folador, Edson L.; Barbosa, Eudes G. V.; Aburjaile, Flavia F.; Gonçalves, Lucas A.; Guimarães, Luís C.; Azevedo, Marcela; Agresti, Pamela C. M.; Silva, Renata F.; Tiwari, Sandeep; Almeida, Sintia S.; Hassan, Syed S.; Pereira, Vanessa B.; Abreu, Vinicius A. C.; Pereira, Ulisses P.; Dorella, Fernanda A.; Carvalho, Alex F.; Pereira, Felipe L.; Leal, Carlos A. G.; Figueiredo, Henrique C. P.; Silva, Artur; Miyoshi, Anderson



Early development of GABA-like immunoreactive cells in the retina of turtle embryos.  


Gamma aminobutyric acid (GABA) is one of the earliest neuroactive substances appearing in the developing central nervous system. The distribution and the time course of the appearance of GABA-like immunoreactivity in the retina of the turtle Emys orbicularis were investigated from embryonic stage 13 to hatching. The first GABA-like immunoreactive cells were observed at stage 14. These cells were located in both the scleral third of the neuroblastic layer and the inner layers of the retina. They were identified as presumptive immature horizontal cells and amacrine cells, respectively. The observation of numerous labelled fibers in the nerve fiber layer suggests that some of the GABA-like immunoreactive cells in the layers were ganglion cells. The development of GABA-like immunoreactive cells followed a gradient of maturation from central to peripheral retina. At hatching, the central retina appeared nearly morphologically mature. In conclusion, GABA is present before the morphofunctional maturation of the retina and this precocious existence supports the idea of its involvement in a neurotrophic role preceding the establishment of synaptic connections and neurotransmitter function. PMID:7697864

Versaux-Botteri, C; Hergueta, S; Pieau, C; Wasowicz, M; Dalil-Thiney, N; Nguyen-Legros, J



Defects in GABA metabolism affect selective autophagy pathways and are alleviated by mTOR inhibition  

PubMed Central

In addition to key roles in embryonic neurogenesis and myelinogenesis, ?-aminobutyric acid (GABA) serves as the primary inhibitory mammalian neurotransmitter. In yeast, we have identified a new role for GABA that augments activity of the pivotal kinase, Tor1. GABA inhibits the selective autophagy pathways, mitophagy and pexophagy, through Sch9, the homolog of the mammalian kinase, S6K1, leading to oxidative stress, all of which can be mitigated by the Tor1 inhibitor, rapamycin. To confirm these processes in mammals, we examined the succinic semialdehyde dehydrogenase (SSADH)-deficient mouse model that accumulates supraphysiological GABA in the central nervous system and other tissues. Mutant mice displayed increased mitochondrial numbers in the brain and liver, expected with a defect in mitophagy, and morphologically abnormal mitochondria. Administration of rapamycin to these mice reduced mTOR activity, reduced the elevated mitochondrial numbers, and normalized aberrant antioxidant levels. These results confirm a novel role for GABA in cell signaling and highlight potential pathomechanisms and treatments in various human pathologies, including SSADH deficiency, as well as other diseases characterized by elevated levels of GABA. PMID:24578415

Lakhani, Ronak; Vogel, Kara R; Till, Andreas; Liu, Jingjing; Burnett, Sarah F; Gibson, K Michael; Subramani, Suresh



Decreased GABA(A) receptor expression in the seizure-prone fragile X mouse.  


The fragile X mental retardation syndrome is due to the transcriptional silence of the fragile X gene, FMR1, and to the resulting loss of the FMR1 product, FMRP. The pathogenesis of the syndrome, however, is not understood. Increased prevalence of childhood seizures is a feature of the fragile X syndrome and increased seizure susceptibility is seen in the fragile X knock out mouse model for this disorder. To investigate the increased seizure susceptibility, we examined GABA(A) receptor expression in the FVB/N fragile X mouse. Western blot analysis revealed that expression of the GABA(A) receptor beta subunit (GABA(A) beta), which is required for receptor function, was reduced in the cortex, hippocampus, diencephalon and brainstem in adult male fragile X mice. Immunohistochemical analysis of brain sections indicated a reduction in GABA(A) beta immunoreactivity. We also found increased expression of glutamic acid decarboxylase, the enzyme responsible for GABA synthesis, in the same regions that showed GABA(A) beta reduction. These results indicate that the absence of Fmrp leads to GABAergic system alterations that could account for the increased seizure susceptibility of the fragile X mouse. These alterations may also be relevant to the seizures and the abnormal behaviors in the human syndrome. PMID:15755515

El Idrissi, Abdeslem; Ding, Xiao-Hua; Scalia, Jason; Trenkner, Ekkhart; Brown, W Ted; Dobkin, Carl



GABA Expression and Regulation by Sensory Experience in the Developing Visual System  

PubMed Central

The developing retinotectal system of the Xenopus laevis tadpole is a model of choice for studying visual experience-dependent circuit maturation in the intact animal. The neurotransmitter gamma-aminobutyric acid (GABA) has been shown to play a critical role in the formation of sensory circuits in this preparation, however a comprehensive neuroanatomical study of GABAergic cell distribution in the developing tadpole has not been conducted. We report a detailed description of the spatial expression of GABA immunoreactivity in the Xenopus laevis tadpole brain at two key developmental stages: stage 40/42 around the onset of retinotectal innervation and stage 47 when the retinotectal circuit supports visually-guided behavior. During this period, GABAergic neurons within specific brain structures appeared to redistribute from clusters of neuronal somata to a sparser, more uniform distribution. Furthermore, we found that GABA levels were regulated by recent sensory experience. Both ELISA measurements of GABA concentration and quantitative analysis of GABA immunoreactivity in tissue sections from the optic tectum show that GABA increased in response to a 4 hr period of enhanced visual stimulation in stage 47 tadpoles. These observations reveal a remarkable degree of adaptability of GABAergic neurons in the developing brain, consistent with their key contributions to circuit development and function. PMID:22242157

Miraucourt, Loïs S.; da Silva, Jorge Santos; Burgos, Kasandra; Li, Jianli; Abe, Hikari; Ruthazer, Edward S.; Cline, Hollis T.



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


Lead (Pb) is a heavy metal that is toxic to numerous physiological processes. Its use in industrial applications is widespread and results in an increased risk of human environmental exposure. The central nervous system (CNS) is most sensitive to Pb exposure during early development due to rapid cell proliferation and migration, axonal growth, and synaptogenesis. One of the key components of CNS development is the Gamma-aminobutyric acid (GABA)-ergic system. GABA is the primary inhibitory neurotransmitter in the adult brain. However, during development GABA acts as an excitatory neurotrophic factor which contributes to these cellular processes. Multiple studies report effects of Pb on GABA in the mature brain; however, little is known regarding the adverse effects of Pb exposure on the GABAergic system during embryonic development. To characterize the effects of Pb on the GABAergic system during development, zebrafish embryos were exposed to 10, 50, or 100 ppb Pb or a control treatment. Tissue up-take, gross morphological alterations, gene expression, and neurotransmitter levels were analyzed. Analysis revealed that alterations in gene expression throughout the GABAergic system and GABA levels were dose and developmental time point specific. These data provide a framework for further analysis of the effects of Pb on the GABAergic system during the excitatory phase and as GABA transitions to an inhibitory neurotransmitter during development. PMID:24875535

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



Structure, pharmacology and function of GABA-A receptors in cochlear outer hair cells.  


There is evidence that the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is released from some efferent olivocochlear nerve endings terminating at outer hair cells (OHCs). Using monoclonal antibodies against postsynaptic GABAA receptor from bovine cerebral cortex we confirm the presence of GABA and benzodiazepine bindings sites of alpha- and beta-subunits of GABAA receptors at the basal pole of isolated OHCs. Whole-cell recording with viable OHCs revealed that the application of 10(-3)-10(-8) M GABA to the cell surface was followed by a concentration-dependent hyperpolarization of the outer cell membrane. Hyperpolarization was increased in the presence of 2.5 x 10(-5) M chlorazepate, a benzodiazepine derivative. Electrophysiological effects caused by GABA alone or in combination with chlorazepate were specifically inhibited by 10(-6) M of the GABA-receptor antagonist picrotoxin. Moreover, 10(-5)-10(-7) M GABA caused reversible slow elongation of the cylindrical hair cell body in OHCs examined. These neurotransmitter-induced motile responses were specifically blocked by 10(-4) M picrotoxin. The results suggest that a subpopulation of OHCs express alpha- and beta-subunits of GABAA receptors which both form a GABA/benzodiazepine-receptor complex at the basal pole of isolated OHCs. These receptors are thought to allow GABA which is released from efferent auditory nerve terminals to bind to the cell surface of OHCs, resulting in GABAA-receptor activation. This probably gates a GABAA-receptor-associated chloride channel in the postsynaptic OHC membrane, allowing hyperpolarization and elongation of the cell. PMID:8260146

Plinkert, P K; Gitter, A H; Möhler, H; Zenner, H P



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


Although recent studies suggest that gamma-aminobutyric acid (GABA) and glycine may be 'inhibitory' to mature neurons, but 'excitatory' to immature neurons under normoxia, it is unknown whether inhibitory neurotransmitters are differentially involved in neuronal response to hypoxia in immature and mature neurons. In the present study, we exposed rat cortical neurons to hypoxia (1% O2) and examined the effects of three major inhibitory neurotransmitters (GABA, glycine and taurine) on the hypoxic neurons at different neuronal ages [days in vitro (DIV)4-20]. Our data showed that the cortical neurons expressed both GABA(A) and glycine receptors with differential developmental profiles. GABA (10-2000 microm) was neuroprotective to hypoxic neurons of DIV20, but enhanced hypoxic injury in neurons of GABA. However, higher concentrations of glycine (1000-2000 microm) for long-term exposure (48-72 h) displayed neuroprotection at all ages (DIV4-20). Taurine (10-2000 microm), unlike GABA and glycine, displayed protection only in DIV4 neurons, and was slightly toxic to neurons>DIV4. In comparison with delta-opioid receptor (DOR)-induced protection in DIV20 neurons exposed to 72 h of hypoxia, glycine-induced protection was weaker than that of DOR but stronger than that of GABA and taurine. These data suggest that the effects of the inhibitory neurotransmitters on hypoxic cortical neurons are age-dependent, with GABA and glycine being neurotoxic to immature neurons and neuroprotective to mature neurons. PMID:16045482

Zhao, Peng; Qian, Hong; Xia, Ying



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

PubMed Central

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

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



GABA receptors on the somatic muscle cells of the parasitic nematode, Ascaris suum: stereoselectivity indicates similarity to a GABAA-type agonist recognition site.  

PubMed Central

1. The gamma-aminobutyric acid (GABA) receptors on the somatic muscle cells of Ascaris, which mediate muscle cell hyperpolarization and relaxation, have been characterized by use of intracellular recording techniques. 2. These receptors are like mammalian GABAA-receptors in that the response is mediated by an increase conductance to chloride ions. The GABAA-mimetic, muscimol, has a relative potency of 0.40 +/- 0.02 (n = 3) compared to GABA. 3. The stereoselectivity of the GABA receptor on Ascaris is identical to that for the mammalian GABAA-receptor, as determined from the relative potency of three pairs of enantiomers of structural analogues of GABA. 4. The most potent agonist is (S)-(+)-dihydromuscimol which is 7.53 +/- 0.98 (n = 5) times more potent than GABA. 5. The Ascaris GABA receptor is not significantly blocked, at concentrations below 100 microM by the potent, competitive GABAA-receptor antagonist, SR95531. 6. The Ascaris GABA receptor does not recognise agents that are known to block the GABA gated chloride channel in mammalian preparations such as t-butylbicyclophosphorothionate (TBPS, 10 microM, n = 2) or the insecticide dieldrin (100 microM, n = 3). 7. GABAergic responses in Ascaris are not potentiated by pentobarbitone (100 microM, n = 3) or flurazepam (100 microM, n = 3). 8. The potencies of various GABA-mimetics in the Ascaris preparation have been compared with their potency at displacing GABAA-receptor binding in mammalian brain. Excluding the sulphonic acid derivatives of GABA, the correlation coefficient (r) between the potencies of compounds in the two systems is 0.74 (P less than 0.01). The significance of this correlation is discussed. 9. The pharmacology of the Ascaris GABA receptor is discussed in relation to other invertebrate systems and the mammalian subclassification of GABA receptors. PMID:2556203

Holden-Dye, L.; Krogsgaard-Larsen, P.; Nielsen, L.; Walker, R. J.



A depolarizing inhibitory response to GABA in brainstem auditory neurons of the chick.  


Neurons in the brainstem auditory nuclei, n. magnocellularis and n. laminaris, of the chick are contacted by terminals containing the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). In this report we describe the physiological response of these neurons to GABA using an in vitro slice preparation. In brainstem auditory neurons, GABA produced a depolarization of up to 20 mV and an associated decrease in input resistance. This depolarization was inhibitory; action potentials generated by orthodromic synaptic drive, antidromic stimulation and intracellular current injection were prevented by GABA application. The GABA response still occurred when synaptic transmission was prevented by perfusing the slice with a medium containing low Ca2+ and high Mg2+ concentrations. Thus, the effects of GABA were directly on the postsynaptic neuron and not via an interneuron. Whole-cell voltage clamp of neurons revealed that the reversal potential of the inward current was approximately -45 mV, suggesting that the channel responsible for this response is not selective for Cl- or K+. Pharmacological analyses suggest that this GABA receptor has properties distinct from those typical of either GABAa or GABAb receptors. Although a similar response was observed with the GABAa agonist, muscimol, it was not blocked by the GABAa antagonist, bicuculline. The response was not evoked by the GABAb agonist, baclofen, and was not blocked by the GABAb antagonist phaclofen. This unusual depolarizing response is not a common feature of all brainstem neurons. Neurons located in the neighboring medial vestibular nucleus show a more traditional response to GABA application. At resting potential, these neurons show a hyperpolarizing or biphasic response associated with a decrease in input resistance and inhibition of their spontaneous activity. GABA-induced responses in the medial vestibular nucleus are blocked by bicuculline. These results suggest that an unusual form of the GABA receptor is present in the brainstem auditory system of the chick. It is possible that this form of GABA receptor provides an efficient mechanism for inhibiting the relatively powerful EPSPs received by brainstem auditory neurons, or it may play a trophic role in the afferent regulation of neuronal integrity in this system. PMID:7606455

Hyson, R L; Reyes, A D; Rubel, E W



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

PubMed Central

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

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



Ontogeny of the calcium binding protein parvalbumin in the rat nervous system  

Microsoft Academic Search

In the adult rat brain, the calcium-binding protein parvalbumin is preferentially associated with spontaneously fast-firing, metabolically active neurons and coexists with gamma-amino-butyric acid (GABA) in cortical inhibitory interneurons. Whether this is so in developing neurons has not been explored. To this end, we have used parvalbumin immunohistochemistry to study expression of this protein in the rat nervous system during pre-

Sven Solbach; Marco R. Celio



GABA tea prevents cardiac fibrosis by attenuating TNF-alpha and Fas/FasL-mediated apoptosis in streptozotocin-induced diabetic rats.  


GABA tea is a tea product that contains a high level of gamma-aminobutyric acid (GABA). This study investigated the effects of GABA tea on the heart in a diabetic rat model. Male Wistar rats were injected with 55mg/kg streptozotocin (STZ) to induce diabetes for 2weeks and then orally given dosages of 4.55 and 45.5mg/kg/day GABA tea extract for 6weeks. The results revealed that fasting blood glucose levels returned to normal levels in GABA tea-treated diabetic rats, but not in the untreated diabetic rats. Additionally, GABA tea effectively inhibited cardiac fibrosis induced by STZ. Further experiments showed that the STZ-induced protein levels of tumor necrosis factor-alpha (TNF-alpha), Fas, activated caspase-8 and caspase-3 were significantly inhibited by the GABA tea treatment. Therefore, our data suggest that the inhibiting effect of GABA tea on STZ-induced cardiac fibrosis in diabetic rats may be mediated by reducing blood glucose and further attenuating TNF-alpha expression and/or Fas/Fas ligand (FasL)-mediated apoptosis. These findings will provide implications for the potential anti-diabetic properties of GABA tea. PMID:24374093

Cherng, Shur-Hueih; Huang, Chih-Yang; Kuo, Wei-Wen; Lai, Shue-Er; Tseng, Chien-Yu; Lin, Yueh-Min; Tsai, Fuu-Jen; Wang, Hsueh-Fang



The Glutamine-Glutamate/GABA Cycle: Function, Regional Differences in Glutamate and GABA Production and Effects of Interference with GABA Metabolism.  


The operation of a glutamine-glutamate/GABA cycle in the brain consisting of the transfer of glutamine from astrocytes to neurons and neurotransmitter glutamate or GABA from neurons to astrocytes is a well-known concept. In neurons, glutamine is not only used for energy production and protein synthesis, as in other cells, but is also an essential precursor for biosynthesis of amino acid neurotransmitters. An excellent tool for the study of glutamine transfer from astrocytes to neurons is [(14)C]acetate or [(13)C]acetate and the glial specific enzyme inhibitors, i.e. the glutamine synthetase inhibitor methionine sulfoximine and the tricarboxylic acid cycle (aconitase) inhibitors fluoro-acetate and -citrate. Acetate is metabolized exclusively by glial cells, and [(13)C]acetate is thus capable when used in combination with magnetic resonance spectroscopy or mass spectrometry, to provide information about glutamine transfer. The present review will give information about glutamine trafficking and the tools used to map it as exemplified by discussions of published work employing brain cell cultures as well as intact animals. It will be documented that considerably more glutamine is transferred from astrocytes to glutamatergic than to GABAergic neurons. However, glutamine does have an important role in GABAergic neurons despite their capability of re-utilizing their neurotransmitter by re-uptake. PMID:25380696

Walls, Anne B; Waagepetersen, Helle S; Bak, Lasse K; Schousboe, Arne; Sonnewald, Ursula



Pharmacological characterization of homobaclofen on wild type and mutant GABA B1b receptors coexpressed with the GABA B2 receptor  

Microsoft Academic Search

Homobaclofen (5-amino-3-(4-chlorophenyl) pentanoic acid) is a homologue of the classical GABAB receptor agonist baclofen. In a recent study, the two enantiomers of this compound were tested in a GABAB receptor selective [3H]?-aminobutyric acid ([3H]GABA) binding assay using rat brain homogenate and in an assay of electrically induced contractions of guinea pig ileum. The results from the two tissues did, however,

Anders A Jensen; Bo E Madsen; Povl Krogsgaard-Larsen; Hans Bräuner-Osborne



Effects of insecticides on GABA-induced chloride influx into rat brain microsacs.  


The actions of different insecticides known to affect binding of ligands to gamma-aminobutyric acid (GABA) receptors were studied on the function of GABAA receptors in rat brain as assayed by GABA-induced 36Cl- influx into membrane microsacs. This flux was inhibited by the competitive antagonist bicuculline and the noncompetitive antagonist t-butylbicyclophosphorothionate, and the GABA effect was potentiated by the tranquilizer flunitrazepam and the depressant pentobarbital, as expected for effects on a GABAA receptor. The GABA-induced 36Cl- flux was inhibited by several cyclodienes and gamma-hexachlorocyclohexane (gamma-BHC) with the following order of decreasing potency: endosulfan I greater than endrin greater than endosulfan II greater than dieldrin greater than heptachlor epoxide greater than gamma-BHC greater than heptachlor. The noninsecticidal beta-BHC had no effect, while the IC 50 values for gamma-BHC and endrin were 1 and 0.2 microM, respectively. The four pyrethroids tested also inhibited the GABA-induced 36Cl- flux with the following decreasing potencies: 1R,cis,alpha S-cypermethrin greater than 1R,trans, alpha S-cypermethrin greater than fluvalinate greater than allethrin. Avermectin B1a was the only insecticide tested that, in the absence of GABA, stimulated 36Cl- flux in a dose-dependent manner, and this flux was inhibited by bicuculline. The stereospecific inhibition of the GABA-induced 36Cl- influx by the cyclodienes and gamma-BHC supports previously published data on their binding to mammalian brain GABAA receptor and suggests that these insecticides inhibit this receptor's function. It is also suggested that type II pyrethroids are potent inhibitors of the same receptor. However, avermectin B1a appears to act as a partial agonist of GABAA receptors. PMID:3009836

Abalis, I M; Eldefrawi, M E; Eldefrawi, A T



VTA GABA neurons modulate specific learning behaviors through the control of dopamine and cholinergic systems  

PubMed Central

The mesolimbic reward system is primarily comprised of the ventral tegmental area (VTA) and the nucleus accumbens (NAc) as well as their afferent and efferent connections. This circuitry is essential for learning about stimuli associated with motivationally-relevant outcomes. Moreover, addictive drugs affect and remodel this system, which may underlie their addictive properties. In addition to dopamine (DA) neurons, the VTA also contains approximately 30% ?-aminobutyric acid (GABA) neurons. The task of signaling both rewarding and aversive events from the VTA to the NAc has mostly been ascribed to DA neurons and the role of GABA neurons has been largely neglected until recently. GABA neurons provide local inhibition of DA neurons and also long-range inhibition of projection regions, including the NAc. Here we review studies using a combination of in vivo and ex vivo electrophysiology, pharmacogenetic and optogenetic manipulations that have characterized the functional neuroanatomy of inhibitory circuits in the mesolimbic system, and describe how GABA neurons of the VTA regulate reward and aversion-related learning. We also discuss pharmacogenetic manipulation of this system with benzodiazepines (BDZs), a class of addictive drugs, which act directly on GABAA receptors located on GABA neurons of the VTA. The results gathered with each of these approaches suggest that VTA GABA neurons bi-directionally modulate activity of local DA neurons, underlying reward or aversion at the behavioral level. Conversely, long-range GABA projections from the VTA to the NAc selectively target cholinergic interneurons (CINs) to pause their firing and temporarily reduce cholinergic tone in the NAc, which modulates associative learning. Further characterization of inhibitory circuit function within and beyond the VTA is needed in order to fully understand the function of the mesolimbic system under normal and pathological conditions. PMID:24478655

Creed, Meaghan C.; Ntamati, Niels R.; Tan, Kelly R.



The Discriminative stimulus effects of gamma-hydroxybutyrate and related compounds in rats discriminating baclofen or diazepam: The role of GABA(B) and GABA(A) receptors.  


The discriminative stimulus effects of gamma-hydroxybutyrate (GHB) can be mimicked by GABA(A) receptor-positive modulators (e.g., diazepam) and GABA(B) receptor agonists (e.g., baclofen). The purposes of this study were to see whether stimulus control could be established with baclofen and to further characterize the role of GABAergic mechanisms in the behavioral actions of GHB by evaluating GHB and related compounds in rats discriminating either diazepam or baclofen. Training criteria were satisfied with baclofen and diazepam after 69 and 44 sessions, respectively. GHB and its precursors gamma-butyrolactone and 1,4-butanediol occasioned >80% responding on the drug-associated lever in rats discriminating baclofen and <11% in rats discriminating diazepam. Diazepam and other GABA(A) receptor-positive modulators occasioned intermediate levels of responding on the baclofen lever, whereas baclofen occasioned less than 4% responding on the diazepam lever. The GABA(B) receptor antagonist CGP 35348 [(3-aminopropyl)(diethoxymethyl) phosphinic acid] partially antagonized the effects of baclofen as well as the baclofen-like effects of GHB, and flumazenil partially antagonized the effects of diazepam. This study established stimulus control with baclofen, and substitution data provided direct evidence for a role of GABAergic, especially GABA(B), mechanisms in the discriminative stimulus effects of GHB. The lack of substitution by GHB or its metabolic precursors for diazepam indicates a comparatively smaller role of GABA(A) mechanisms in these effects of GHB. The inability of CGP 35348 to completely attenuate the effects of baclofen and GHB suggests that multiple receptors could be involved in the discriminative stimulus effects of GHB. PMID:14742739

Carter, L P; Unzeitig, A W; Wu, H; Chen, W; Coop, A; Koek, W; France, C P



A conserved mechanism of GABA binding and antagonism is revealed by structure-function analysis of the periplasmic binding protein Atu2422 in Agrobacterium tumefaciens.  


Bacterial periplasmic binding proteins (PBPs) and eukaryotic PBP-like domains (also called as Venus flytrap modules) of G-protein-coupled receptors are involved in extracellular GABA perception. We investigated the structural and functional basis of ligand specificity of the PBP Atu2422, which is implicated in virulence and transport of GABA in the plant pathogen Agrobacterium tumefaciens. Five high-resolution x-ray structures of Atu2422 liganded to GABA, Pro, Ala, and Val and of point mutant Atu2422-F77A liganded to Leu were determined. Structural analysis of the ligand-binding site revealed two essential residues, Phe(77) and Tyr(275), the implication of which in GABA signaling and virulence was confirmed using A. tumefaciens cells expressing corresponding Atu2422 mutants. Phe(77) restricts ligand specificity to ?-amino acids with a short lateral chain, which act as antagonists of GABA signaling in A. tumefaciens. Tyr(275) specifically interacts with the GABA ?-amino group. Conservation of these two key residues in proteins phylogenetically related to Atu2422 brought to light a subfamily of PBPs in which all members could bind GABA and short ?-amino acids. This work led to the identification of a fingerprint sequence and structural features for defining PBPs that bind GABA and its competitors and revealed their occurrence among host-interacting proteobacteria. PMID:20630861

Planamente, Sara; Vigouroux, Armelle; Mondy, Samuel; Nicaise, Magali; Faure, Denis; Moréra, Solange



Directed differentiation of forebrain GABA interneurons from human pluripotent stem cells  

PubMed Central

Forebrain ?-aminobutyric acid (GABA) interneurons have crucial roles in high-order brain function via modulating network activities and plasticity, and they are implicated in many psychiatric disorders. Availability of enriched functional human forebrain GABA interneurons, especially those from people affected by GABA interneuron deficit disease, will be instrumental to the investigation of disease pathogenesis and development of therapeutics. We describe a protocol for directed differentiation of forebrain GABA interneurons from human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) in a chemically defined system. In this protocol, human PSCs are first induced to primitive neuroepithelial cells over 10 d, and then patterned to NKX2.1-expressing medial ganglionic eminence progenitors by simple treatment with sonic hedgehog or its agonist purmorphamine over the next 2 weeks. These progenitors generate a nearly pure population of forebrain GABA interneurons by the sixth week. This simple and efficient protocol does not require transgenic modification or cell sorting, and it has been replicated with multiple human ESC and iPSC lines. PMID:23928500

Liu, Yan; Liu, Huisheng; Sauvey, Conall; Yao, Lin; Zarnowska, Ewa D; Zhang, Su-Chun



Recruitment of functional GABA(A) receptors to postsynaptic domains by insulin.  


Modification of synaptic strength in the mammalian central nervous system (CNS) occurs at both pre- and postsynaptic sites. However, because postsynaptic receptors are likely to be saturated by released transmitter, an increase in the number of active postsynaptic receptors may be a more efficient way of strengthening synaptic efficacy. But there has been no evidence for a rapid recruitment of neurotransmitter receptors to the postsynaptic membrane in the CNS. Here we report that insulin causes the type A gamma-aminobutyric acid (GABA[A]) receptor, the principal receptor that mediates synaptic inhibition in the CNS, to translocate rapidly from the intracellular compartment to the plasma membrane in transfected HEK 293 cells, and that this relocation requires the beta2 subunit of the GABA(A) receptor. In CNS neurons, insulin increases the expression of GABA(A) receptors on the postsynaptic and dendritic membranes. We found that insulin increases the number of functional postsynaptic GABA(A) receptors, thereby increasing the amplitude of the GABA(A)-receptor-mediated miniature inhibitory postsynaptic currents (mIPSCs) without altering their time course. These results provide evidence for a rapid recruitment of functional receptors to the postsynaptic plasma membrane, suggesting a fundamental mechanism for the generation of synaptic plasticity. PMID:9262404

Wan, Q; Xiong, Z G; Man, H Y; Ackerley, C A; Braunton, J; Lu, W Y; Becker, L E; MacDonald, J F; Wang, Y T



SDF and GABA interact to regulate axophilic migration of GnRH neurons  

PubMed Central

Summary Stromal derived growth factor (SDF-1) and gamma-aminobutyric acid (GABA) are two extracellular cues that regulate the rate of neuronal migration during development and may act synergistically. The molecular mechanisms of this interaction are still unclear. Gonadotropin releasing hormone-1 (GnRH) neurons are essential for vertebrate reproduction. During development, these neurons emerge from the nasal placode and migrate through the cribriform plate into the brain. Both SDF-1 and GABA have been shown to regulate the rate of GnRH neuronal migration by accelerating and slowing migration, respectively. As such, this system was used to explore the mechanism by which these molecules act to produce coordinated cell movement during development. In the present study, GABA and SDF-1 are shown to exert opposite effects on the speed of cell movement by activating depolarizing or hyperpolarizing signaling pathways, GABA via changes in chloride and SDF-1 via changes in potassium. GABA and SDF-1 were also found to act synergistically to promote linear rather than random movement. The simultaneous activation of these signaling pathways, therefore, results in tight control of cellular speed and improved directionality along the migratory pathway of GnRH neurons. PMID:22976302

Casoni, Filippo; Ian Hutchins, B.; Donohue, Duncan; Fornaro, Michele; Condie, Brian G.; Wray, Susan



GABA/benzodiazepine receptor complex in long-sleep and short-sleep mice  

SciTech Connect

LS mice are more sensitive to benzodiazepine-induced anesthesia; however, the two lines do not differ in their hypothermic response to flurazepam. SS mice are more resistant to 3-mercaptopropionic acid-induced seizures and more sensitive to the anticonvulsant effects of benzodiazepines. The various correlates of GABA and benzodiazepine actions probably are the results of different mechanisms of action and/or differential regional control. Bicuculline competition for /sup 3/H-GABA binding sites is greater in SS cerebellar tissue and /sup 3/H-flunitrazepam binding is greater in the mid-brain region of LS mice. GABA enhancement of /sup 3/H-flunitrazepma binding is greater in SS mice. Ethanol also enhances /sup 3/H-flunitrazepam binding and increases the levels of /sup 3/H-flunitrazepam binding above those observed for GABA. Using correlational techniques on data from LS and SS mice and several inbred mouse strains, it was demonstrated that a positive relationship exists between the degree of receptor coupling within the GABA receptor complex and the degree of resistance to seizures.

Marley, R.J.



Ornithine Aminotransferase versus GABA Aminotransferase: Implications for the Design of New Anticancer Drugs.  


Ornithine aminotransferase (OAT) and ?-aminobutyric acid aminotransferase (GABA-AT) are classified under the same evolutionary subgroup and share a large portion of structural, functional, and mechanistic features. Therefore, it is not surprising that many molecules that bind to GABA-AT also bind well to OAT. Unlike GABA-AT, OAT had not been viewed as a potential therapeutic target until recently; consequently, the number of therapeutically viable molecules that target OAT is very limited. In this review the two enzymes are compared with respect to their active-site structures, catalytic and inactivation mechanisms, and selective inhibitors. Insight is offered that could aid in the design and development of new selective inhibitors of OAT for the treatment of cancer. PMID:25145640

Lee, Hyunbeom; Juncosa, Jose I; Silverman, Richard B



The benzodiazepine site of the GABA A receptor: an old target with new potential?  

Microsoft Academic Search

The gamma-aminobutyric acid-A (GABAA) receptors is the target for the most widely prescribed sleep medicines. It is a ligand-gated ion channel, activated by the amino acid neurotransmitter GABA, which normally results in hyperpolarization of neurons leading to reduced action potential firing, and thereby a reduction in neuronal activity. It has a rich pharmacology with a number of separate modulator binding

Alan N Bateson



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

Microsoft Academic Search

Macrophages are key components of the inflammatory response to tissue injury, but their activities can exacerbate neuropathology. High-resolution magnetic resonance spectroscopy was used to identify metabolite levels in perchloric acid extracts of cultured cells of the RAW 264.7 murine macrophage line under resting and lipo- polysaccharide-activated conditions. Over 25 me- tabolites were identified including -aminobutyric acid (GABA), an inhibitory neurotransmitter

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



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

PubMed Central

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

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



Valerian inhibits rat hepatocarcinogenesis by activating GABA(A) receptor-mediated signaling.  


Valerian is widely used as a traditional medicine to improve the quality of sleep due to interaction of several active components with the ?-aminobutyric acid (GABA) A receptor (GABA(A)R) system. Recently, activation of GABA signaling in stem cells has been reported to suppress cell cycle progression in vivo. Furthermore, possible inhibitory effects of GABA(A)R agonists on hepatocarcinogenesis have been reported. The present study was performed to investigate modulating effects of Valerian on hepatocarcinogenesis using a medium-term rat liver bioassay. Male F344 rats were treated with one of the most powerful Valerian species (Valeriana sitchensis) at doses of 0, 50, 500 and 5000 ppm in their drinking water after initiation of hepatocarcinogenesis with diethylnitrosamine (DEN). Formation of glutathione S-transferase placental form positive (GST-P(+)) foci was significantly inhibited by Valerian at all applied doses compared with DEN initiation control rats. Generation of 8-hydroxy-2'-deoxyguanosine in the rat liver was significantly suppressed by all doses of Valerian, likely due to suppression of Nrf2, CYP7A1 and induction of catalase expression. Cell proliferation was significantly inhibited, while apoptosis was induced in areas of GST-P(+) foci of Valerian groups associated with suppression of c-myc, Mafb, cyclin D1 and induction of p21(Waf1/Cip1), p53 and Bax mRNA expression. Interestingly, expression of the GABA(A)R alpha 1 subunit was observed in GST-P(+) foci of DEN control rats, with significant elevation associated with Valerian treatment. These results indicate that Valerian exhibits inhibitory effects on rat hepatocarcinogenesis by inhibiting oxidative DNA damage, suppressing cell proliferation and inducing apoptosis in GST-P(+) foci by activating GABA(A)R-mediated signaling. PMID:25419570

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



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


Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central auditory system. Altered GABAergic neurotransmission has been found in both the inferior colliculus and the auditory cortex in animal models of presbycusis. Edited magnetic resonance spectroscopy (MRS), using the MEGA-PRESS sequence, is the most widely used technique for detecting GABA in the human brain. However, to date there has been a paucity of studies exploring changes to the GABA concentrations in the auditory region of patients with presbycusis. In this study, sixteen patients with presbycusis (5 males/11 females, mean age 63.1±2.6years) and twenty healthy controls (6 males/14 females, mean age 62.5±2.3years) underwent audiological and MRS examinations. Pure tone audiometry from 0.125 to 8kHz and tympanometry were used to assess the hearing abilities of all subjects. The pure tone average (PTA; the average of hearing thresholds at 0.5, 1, 2 and 4kHz) was calculated. The MEGA-PRESS sequence was used to measure GABA+ concentrations in 4×3×3cm(3) volumes centered on the left and right Heschl's gyri. GABA+ concentrations were significantly lower in the presbycusis group compared to the control group (left auditory regions: p=0.002, right auditory regions: p=0.008). Significant negative correlations were observed between PTA and GABA+ concentrations in the presbycusis group (r=-0.57, p=0.02), while a similar trend was found in the control group (r=-0.40, p=0.08). These results are consistent with a hypothesis of dysfunctional GABAergic neurotransmission in the central auditory system in presbycusis and suggest a potential treatment target for presbycusis. PMID:25463460

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



Effects of benzodiazepines and non-benzodiazepine compounds on the GABA-induced response in frog isolated sensory neurones.  

PubMed Central

1. The effects of benzodiazepines and non-benzodiazepine compounds on the gamma-aminobutyric acid (GABA)-induced chloride current (ICl) were studied in frog isolated sensory neurones by use of a concentration-jump (termed 'concentration-clamp') technique, under single-electrode voltage-clamp conditions. The drugs used were classified into four categories as follows: full benzodiazepine receptor agonists (diazepam, clonazepam, nitrazepam, midazolam, clotiazepam and etizolam), partial agonists (CL 218,872, Ro 16-6028, Ro 17-1812 and Ro 23-0364), inverse agonists (Ro 15-3505, FG 7142 and beta-CCE) and a benzodiazepine receptor antagonist, Ro 15-1788 (flumazenil). 2. All full agonists at concentrations of 3 x 10(-6) M or less increased dose-dependently the peak amplitude of ICl elicited by 3 x 10(-6) M GABA to twice to three times larger than the control. However, no further augmentation of the GABA response was observed at concentrations of 1 x 10(-5) M or higher. Partial agonists also showed a dose-dependent augmentation of the GABA response at concentrations ranging from 3 x 10(-8) M to 3 x 10(-5) M, but their efficacies of augmentation of the GABA response were only about half or less of those of full agonists. Of the inverse agonists, beta-CCE had a unique dose-dependent effect on the GABA response. Beta-CCE reduced dose-dependently the GABA response at concentrations of less than 3 x 10(-6) M, but augmented it at concentrations of 3 x 10(-5) M and 6 x 10(-5) M. The inverse agonists reduced dose-dependently the GABA response.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2574062

Yakushiji, T.; Fukuda, T.; Oyama, Y.; Akaike, N.



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


Liposomes are nanosystems that allow a sustained release of entrapped substances. Gamma-aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter of the central nervous system (CNS). We developed a liposomal formulation of GABA for application in long-term CNS functional studies. Two days after liposome-entrapped GABA was injected intracerebroventricularly (ICV), Wistar rats were submitted to the following evaluations: (1) changes in mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) to ICV injection of bicuculline methiodide (BMI) in anesthetized rats; (2) changes in cardiovascular reactivity to air jet stress in conscious rats; and (3) anxiety-like behavior in conscious rats. GABA and saline-containing pegylated liposomes were prepared with a mean diameter of 200nm. Rats with implanted cannulas targeted to lateral cerebral ventricle (n=5-8/group) received either GABA solution (GS), empty liposomes (EL) or GABA-containing liposomes (GL). Following (48h) central microinjection (2?L, 0.09M and 99g/L) of liposomes, animals were submitted to the different protocols. Animals that received GL demonstrated attenuated response of RSNA to BMI microinjection (GS 48±9, EL 43±9, GL 11±8%; P<0.05), blunted tachycardia in the stress trial (?HR: GS 115±14, EL 117±10, GL 74±9bpm; P<0.05) and spent more time in the open arms of elevated plus maze (EL 6±2 vs. GL 18±5%; P=0.028) compared with GS and EL groups. These results indicate that liposome-entrapped GABA can be a potential tool for exploring the chronic effects of GABA in specific regions and pathways of the central nervous system. PMID:25446344

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



Effects of Valeriana Officinalis Extracts on [ 3 H]Flunitrazepam Binding, Synaptosomal [ 3 H]GABA Uptake, and Hippocampal [ 3 H]GABA Release  

Microsoft Academic Search

Extracts of Valeriana officinalis have been used in folkloric medicine for its sedative, hypnotic, tranquilizer and anticonvulsant effects, and may interact with ?-aminobutyric acid (GABA) and\\/or benzodiazepine sites. At low concentrations, valerian extracts enhance [3H]flunitrazepam binding (EC50 4.13 × 10-10 mg\\/ml). However, this increased [3H]flunitrazepam binding is replaced by an inhibition at higher concentrations (IC50 of 4.82 × 10-1 mg\\/ml).

José G. Ortiz; Jennifer Nieves-Natal; Pedro Chavez



Brain GABA and glutamate levels in workers of two ant species (Hymenoptera: Formicidae): interspecific differences and effects of queen presence/absence.  


Presence of amino acid neurotransmitters gamma-aminobutyric acid (GABA) and glutamate (Glu) in ant brains was reported in very few studies. To learn more about factors influencing GABA and Glu levels in ant brains, we applied high-performance liquid chromatography to measure levels of these compounds in single brains of workers of 2 ant species, Myrmica ruginodis (subfamily Myrmicinae) and Formica polyctena (subfamily Formicinae) taken from queenright/queenless colony fragments and tested in dyadic aggression tests consisting of an encounter with a nestmate, an alien conspecific or a small cricket. Brain glutamate levels were higher than those of GABA in both tested species. Brain GABA levels (in ?mol/brain) and GABA : Glu ratio were higher in M. ruginodis (a submissive species) than in F. polyctena (a dominant, aggressive species) in spite of smaller brain weight of M. ruginodis. Brain glutamate levels (in ?mol/brain) did not differ between the tested species, which implies that glutamate concentration (in ?mol/mg of brain tissue) was higher in M. ruginodis. Queen absence was associated with increased worker brain GABA levels in F. polyctena, but not in M. ruginodis. No significant effects of opponent type were discovered. As GABA agonists enhance friendly social behavior in rodents, we hypothesize that elevated brain GABA levels of orphaned workers of F. polyctena facilitate the adoption of a new queen. This is the first report providing information on GABA and glutamate levels in single ant brains and documenting the effects of queen presence/absence on brain levels of amino acid neurotransmitters in workers of social Hymenoptera. PMID:24174300

Wnuk, Andrzej; Kostowski, Wojciech; Korczy?ska, Julita; Szczuka, Anna; Symonowicz, Beata; Bie?kowski, Przemys?aw; Mierzejewski, Pawe?; Godzi?ska, Ewa Joanna



Stimulation of benzodiazepine receptor binding by gamma-aminobutyric acid.  

PubMed Central

The effect of the neurotransmitter gamma-aminobutyric acid (GABA) on high-affinity binding of benzodiazepines to brain membranes has been investigated. GABA stimulated [3H]diazepam binding by more than 100% when extensively washed membranes from brain tissue were used. This GABA-stimulated benzodiazepine binding occurred in all brain regions examined. The stimulation was specific for GABA agonist. It was inhibited by the GABA receptor blocker bicuculline methiodide. A large number of compounds structurally closely related to GABA but without direct effect on the GABA receptor failed to enhance [3H]diazepam binding. The stimulation of benzodiazepine binding was caused by an increase in affinity; the number of binding sites remained unchanged. Half-maximal activation of [3H]diazepam binding occurred in the presence of 300 nM muscimol or 900 nM GABA. beta-Guanidinopropionic acid and imidazoleacetic acid were much weaker activators. It is suggested that the described stimulation of benzodiazepine high-affinity binding is mediated by a receptor for GABA. This site of GABA action exhibits different properties when compared to GABA receptors, as characterized by high-affinity binding of GABA agonists. PMID:284378

Karobath, M; Sperk, G



GABAÂ?s Control of Stem and Cancer Cell Proliferation in Adult Neural and Peripheral Niches  

NSDL National Science Digital Library

Aside from traditional neurotransmission and regulation of secretion, {gamma}-amino butyric acid (GABA) through GABAA receptors negatively regulates proliferation of pluripotent and neural stem cells in embryonic and adult tissue. There has also been evidence that GABAergic signaling and its control over proliferation is not only limited to the nervous system, but is widespread through peripheral organs containing adult stem cells. GABA has emerged as a tumor signaling molecule in the periphery that controls the proliferation of tumor cells and perhaps tumor stem cells. Here, we will discuss GABAÂ?s presence as a near-universal signal that may be altered in tumor cells resulting in modified mitotic activity.

Stephanie Z. Young (Yale University Neurosurgery)



Opioid modulation of GABA release in the rat inferior colliculus  

PubMed Central

Background The inferior colliculus, which receives almost all ascending and descending auditory signals, plays a crucial role in the processing of auditory information. While the majority of the recorded activities in the inferior colliculus are attributed to GABAergic and glutamatergic signalling, other neurotransmitter systems are expressed in this brain area including opiate peptides and their receptors which may play a modulatory role in neuronal communication. Results Using a perfusion protocol we demonstrate that morphine can inhibit KCl-induced release of [3H]GABA from rat inferior colliculus slices. DAMGO ([D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin) but not DADLE ([D-Ala2, D-Leu5]-enkephalin or U69593 has the same effect as morphine indicating that ? rather than ? or ? opioid receptors mediate this action. [3H]GABA release was diminished by 16%, and this was not altered by the protein kinase C inhibitor bisindolylmaleimide I. Immunostaining of inferior colliculus cryosections shows extensive staining for glutamic acid decarboxylase, more limited staining for ? opiate receptors and relatively few neurons co-stained for both proteins. Conclusion The results suggest that ?-opioid receptor ligands can modify neurotransmitter release in a sub population of GABAergic neurons of the inferior colliculus. This could have important physiological implications in the processing of hearing information and/or other functions attributed to the inferior colliculus such as audiogenic seizures and aversive behaviour. PMID:15353008

Tongjaroenbungam, Walaiporn; Jongkamonwiwat, Nopporn; Cunningham, Joanna; Phansuwan-Pujito, Pansiri; Dodson, Hilary C; Forge, Andrew; Govitrapong, Piyarat; Casalotti, Stefano O



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

PubMed Central

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

Tochitani, Shiro; Kondo, Shigeaki



Functioning of the dimeric GABA(B) receptor extracellular domain revealed by glycan wedge scanning  

E-print Network

is made up of two subunits, GABA and GABA . WhileB1 B2 GABA binds agonists, GABA is required for trafficking GABA to the cell surface, increasing agonist affinity to GABA , andB1 B2 B1 B1 activating. Here, we used a glycan wedgeB1 B2 scanning approach to investigate how the GABA VFT dimer controls

Paris-Sud XI, Université de


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

SciTech Connect

The {gamma}-aminobutyric acid (GABA) type A receptor (GABA{sub A}R) is one of the most important targets for insecticide action. The human recombinant {beta}3 homomer is the best available model for this binding site and 4-n-[{sup 3}H]propyl-4'-ethynylbicycloorthobenzoate ([{sup 3}H]EBOB) is the preferred non-competitive antagonist (NCA) radioligand. The uniquely high sensitivity of the {beta}3 homomer relative to the much-less-active but structurally very-similar {beta}1 homomer provides an ideal comparison to elucidate structural and functional features important for NCA binding. The {beta}1 and {beta}3 subunits were compared using chimeragenesis and mutagenesis and various combinations with the {alpha}1 subunit and modulators. Chimera {beta}3/{beta}1 with the {beta}3 subunit extracellular domain and the {beta}1 subunit transmembrane helices retained the high [{sup 3}H]EBOB binding level of the {beta}3 homomer while chimera {beta}1/{beta}3 with the {beta}1 subunit extracellular domain and the {beta}3 subunit transmembrane helices had low binding activity similar to the {beta}1 homomer. GABA at 3 {mu}M stimulated heteromers {alpha}1{beta}1 and {alpha}1{beta}3 binding levels more than 2-fold by increasing the open probability of the channel. Addition of the {alpha}1 subunit rescued the inactive {beta}1/{beta}3 chimera close to wildtype {alpha}1{beta}1 activity. EBOB binding was significantly altered by mutations {beta}1S15'N and {beta}3N15'S compared with wildtype {beta}1 and {beta}3, respectively. However, the binding activity of {alpha}1{beta}1S15'N was insensitive to GABA and {alpha}1{beta}3N15'S was stimulated much less than wildtype {alpha}1{beta}3 by GABA. The inhibitory effect of etomidate on NCA binding was reduced more than 5-fold by the mutation {beta}3N15'S. Therefore, the NCA binding site is tightly regulated by the open-state conformation that largely determines GABA{sub A} receptor sensitivity. - Graphical Abstract: Display Omitted Research Highlights: > The {beta}1 and {beta}3 subunits were compared by chimeragenesis, mutagenesis and modulators. > Low {beta}1 NCA binding was rescued by replacing its transmembrane helices with those of {beta}3. > GABA at 3 {mu}M stimulated heteromers {alpha}1{beta}1 and {alpha}1{beta}3 binding levels more than 2-fold. > Mutation at 15' position in TM2 reduced GABA stimulation of NCA binding. > The open-state conformation largely determines GABAA receptor sensitivity to NCAs.

Chen Ligong [Environmental Chemistry and Toxicology Laboratory, Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720 (United States); Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158 (United States); Xue Ling [Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720 (United States); Giacomini, Kathleen M. [Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158 (United States); Casida, John E., E-mail: [Environmental Chemistry and Toxicology Laboratory, Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720 (United States)



Potency of GABA at human recombinant GABA(A) receptors expressed in Xenopus oocytes: a mini review.  


GABAA receptors are members of the ligand-gated ion channel superfamily that mediate inhibitory neurotransmission in the central nervous system. They are thought to be composed of 2 alpha (?), 2 beta (?) subunits and one other such as a gamma (?) or delta (?) subunit. The potency of GABA is influenced by the subunit composition. However, there are no reported systematic studies that evaluate GABA potency on a comprehensive number of subunit combinations expressed in Xenopus oocytes, despite the wide use of this heterologous expression system in structure-function studies and drug discovery. Thus, the aim of this study was to conduct a systematic characterization of the potency of GABA at 43 human recombinant GABA(A) receptor combinations expressed in Xenopus oocytes using the two-electrode voltage clamp technique. The results show that the ?-subunits and to a lesser extent, the ?-subunits influence GABA potency. Of the binary and ternary combinations with and without the ?2L subunit, the ?6/?2L-containing receptors were the most sensitive to GABA, while the ?2- or ?3-subunit conferred higher sensitivity to GABA than receptors containing the ?1-subunit with the exception of the ?2?1?2L and ?6?1?2L subtypes. Of the ?-subunit containing GABA(A) receptors, ?4/?-containing GABA(A) receptors displayed highest GABA sensitivity, with mid-nanomolar concentrations activating ?4?1? and ?4?3? receptors. At ?4?2?, GABA had low micromolar activity. PMID:23385381

Karim, Nasiara; Wellendorph, Petrine; Absalom, Nathan; Johnston, Graham A R; Hanrahan, Jane R; Chebib, Mary



A role for 5-hydroxytryptamine in the GABA-mimetic potentiation of alpha-flupenthixol-induced catalepsy in the rat.  

PubMed Central

1 alpha-Flupenthixol (alpha-FPT)-induced catalepsy in the rat was potentiated by diaminobutyric acid (DABA), an inhibitor of the neuronal high affinity uptake of gamma-aminobutyric acid (GABA). 2 The depletion of 5-hydroxytryptamine (5-HT) with p-chlorophenylalanine (PCPA) abolished the DABA potentiation of alpha-FPT-induced catalepsy; this response was restored with 5-hydroxytryptophan. 3 Potentiation of alpha-FPT-induced catalepsy by clonazepam was significantly reduced by methysergide. Conversely, the potentiation of catalepsy by clomipramine was significantly reduced by picrotoxin. 4 These results are interpreted as evidence supporting a role for 5-HT in modifying the GABA-ergic inhibition of dopaminergic pathways, possibly by regulating the release of GABA. PMID:6681721

Davies, J. A.; Williams, J.



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


Oxytocin (OT), a neurohypophyseal neuropeptide, affects adaptive processes of the central nervous system. In the present study, we investigated the effects of OT on extracellular levels of glutamate (Glu) and ?-aminobutyric acid (GABA) induced by methamphetamine (MAP) in the medial prefrontal cortex (mPFC) and dorsal hippocampus (DHC) of freely moving mice, using in vivo microdialysis coupled to high-performance liquid chromatography and fluorescence detection. The results showed that OT had no effect on basal Glu levels, but attenuated MAP-induced Glu increase in the mPFC and decrease in the DHC. OT increased the basal levels of extracellular GABA in mPFC and DHC of mice, and inhibited the MAP-induced GABA decrease in DHC. Western blot results indicated that OT significantly inhibited the increased glutamatergic receptor (NR1 subunit) levels in the PFC after acute MAP administration, whereas OT further enhanced the elevated levels of glutamatergic transporter (GLT1) induced by MAP in the hippocampus of mice. Atosiban, a selective inhibitor of OT receptor, antagonized the effects of OT. The results provided the first neurochemical evidence that OT, which exerted its action via its receptor, decreased Glu release induced by MAP, and attenuated the changes in glutamatergic neurotransmission partially via regulation of NR1 and GLT1 expression. OT-induced extracellular GABA increase also suggests that OT acts potentially as an inhibitory neuromodulator in mPFC and DHC of mice. PMID:22507692

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



Evaluation of GABA-chitosan nanoparticle induced cell signaling activation during liver regeneration after partial hepatectomy.  


Liver damage due to infection, cirrhosis, accidents and diseases lead to destruction of hepatocytes and their regeneration to its original form is important for the proper functioning of the body. Gamma aminobutyric acid (GABA), a neurotransmitter, was coupled with a biopolymer chitosan and the nanosized complexes were made. The morphology was studied by scanning electron microscope and the interaction of GABA with chitosan was analysed by FT-IR spectroscopy. The interaction of GABA-chitosan nanoparticles with hepatocytes were observed by FITC labeled nanoparticles. After partial hepatectomy in male Wistar rats, DNA synthesis was estimated by tritiated thymidine uptake and the activity of thymidine kinase and protein synthesis by tritiated leucine uptake in hepatocytes. There was an increase in tritiated thymidine uptake in partially hepatectomised groups with nanoparticle treatment (GCNP) when compared to partially hepatectomised groups without nanoparticle treatment (PHNT) and with pure GABA treatment (G). Inositol 1,4,5 trisphosphate (IP3) content and gene expression of phospholipase C mRNA and nuclear factor kappa-light-chain-enhancer of activated B (NF-KB) mRNA was decreased for groups G and GCNP with respect to PHNT. Thus our results showed increased hepatocyte regeneration with decreased cell death in group G and more better with GCNP when compared to PHNT. PMID:22962720

Shilpa, J; Naijil, G; Nandhu, M S; Paulose, C S



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

NASA Astrophysics Data System (ADS)

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

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


Modulation of ?-aminobutyric acid transport in nerve endings: Role of extracellular ?-aminobutyric acid and of cationic fluxes  

PubMed Central

The aim of the present study was to elucidate the possible functional significance of ?-aminobutyric acid (GABA) homoexchange at nerve endings. Using synaptosomes from adult rat cerebrum, we found that a number of conditions altering cationic fluxes produced a concomitant change in the stoichiometry of GABA homoexchange, In fact, exogenous GABA (10 ?M), while not causing net release of intrasynaptosomal GABA in standard conditions, triggered a large net GABA release in the presence of veratridine, Na+-K+-ATPase inhibitors, or the ionophore A23187, superimposed on that due to the various agents tested alone. This extra release was mediated by the membrane carrier, being largely inhibited by the GABA carrier-blocker L-diaminobutyric acid. The altered stoichiometry of GABA homoexchange observed under these conditions (efflux > influx) appeared to be coupled to the influx of Na+ (or of Ca2+), rather than determined by the establishment of a high intrasynaptosomal [Na+]. Under conditions of reversed Na+ flux (Na+ efflux), the GABA outward/inward flux ratio was also reversed, and the stoichiometry of GABA homoexchange was in favor of net influx. The possible contribution of K+ to the effects observed is also discussed. It is concluded that the GABA transport system of nerve endings is susceptible to fine modulation by changes in cationic fluxes similar to those occurring in vivo during depolarization and repolarization. These fluxes may have a prominent role in determining the direction of net GABA transport in GABA-ergic nerve terminals of the living brain. PMID:351622

Levi, Giulio; Raiteri, Maurizio



Regulation of GABA Receptor Activity by Neurosteroids and Phosphorylation  

NSDL National Science Digital Library

These two animations show two models for how neurosteroids regulate the flow of chloride ions (Cl-) through ionotropic gamma-aminobutyric acid (GABA) receptors. In the first model, binding of the neurosteroid allows a protein kinase C (PKC) phosphorylation site to become accessible. Phosphorylation of the channel increases flux through the channel. In the second model, phosphorylation by PKC allows the neurosteroid to bind and increase flux through the channel. The animations have two parts: (i) a diagrammatic representation of the sequence of events at the channel in the membrane and (ii) a representative current trace of data obtained using electrophysiological techniques. These animations would be useful in teaching how allosteric modulators (neurosteroids) and covalent modulators (kinases) can work together as regulators of protein activity.

Jeffrey Tasker (Tulane University;Department of Cell and Molecular Biology REV)



3D GABA imaging with real-time motion correction, shim update and reacquisition of adiabatic spiral MRSI.  


Gamma-aminobutyric acid (GABA) and glutamate (Glu) are the major neurotransmitters in the brain. They are crucial for the functioning of healthy brain and their alteration is a major mechanism in the pathophysiology of many neuro-psychiatric disorders. Magnetic resonance spectroscopy (MRS) is the only way to measure GABA and Glu non-invasively in vivo. GABA detection is particularly challenging and requires special MRS techniques. The most popular is MEscher-GArwood (MEGA) difference editing with single-voxel Point RESolved Spectroscopy (PRESS) localization. This technique has three major limitations: a) MEGA editing is a subtraction technique, hence is very sensitive to scanner instabilities and motion artifacts. b) PRESS is prone to localization errors at high fields (?3T) that compromise accurate quantification. c) Single-voxel spectroscopy can (similar to a biopsy) only probe steady GABA and Glu levels in a single location at a time. To mitigate these problems, we implemented a 3D MEGA-editing MRS imaging sequence with the following three features: a) Real-time motion correction, dynamic shim updates, and selective reacquisition to eliminate subtraction artifacts due to scanner instabilities and subject motion. b) Localization by Adiabatic SElective Refocusing (LASER) to improve the localization accuracy and signal-to-noise ratio. c) K-space encoding via a weighted stack of spirals provides 3D metabolic mapping with flexible scan times. Simulations, phantom and in vivo experiments prove that our MEGA-LASER sequence enables 3D mapping of GABA+ and Glx (Glutamate+Gluatmine), by providing 1.66 times larger signal for the 3.02ppm multiplet of GABA+ compared to MEGA-PRESS, leading to clinically feasible scan times for 3D brain imaging. Hence, our sequence allows accurate and robust 3D-mapping of brain GABA+ and Glx levels to be performed at clinical 3T MR scanners for use in neuroscience and clinical applications. PMID:25255945

Bogner, Wolfgang; Gagoski, Borjan; Hess, Aaron T; Bhat, Himanshu; Tisdall, M Dylan; van der Kouwe, Andre J W; Strasser, Bernhard; Marja?ska, Ma?gorzata; Trattnig, Siegfried; Grant, Ellen; Rosen, Bruce; Andronesi, Ovidiu C



Effects of endogenous melatonin on glutamate and GABA rhythms in the striatum of unilateral 6-hydroxydopamine-lesioned rats.  


We have previously reported a time-dependent increase in melatonin (MLT) and decrease in dopamine (DA) in striatal dialysate 3weeks after unilateral 6-hydroxydopamine (6-OHDA) lesioning in the rat substantia nigra pars compacta (SNc) and medial forebrain bundle (MFB). This study aimed to investigate dynamic and circadian variations in DA, MLT, glutamate (Glu) and ?-aminobutyric acid (GABA) in striatal dialysates in the same 6-OHDA animal model. These neurotransmitters were determined using high-performance liquid chromatography (HPLC). Three weeks following 6-OHDA lesioning, there was a significant increase in extracellular Glu (156%) and decrease in GABA (15%) and DA (85%) in the lesioned striatum. These changes continued over time. Concomitantly, MLT was increased by 107% in the lesioned striatal dialysates after 4weeks, and continued to increase gradually over time. Six weeks post-treatment, levels of MLT secretion at 12 time points were higher, and the peak time of MLT secretion was earlier, in 6-OHDA-lesioned rats compared with vehicle-treated rats. In addition, significant variations in extracellular levels of Glu and GABA between day and night were observed in vehicle-treated rat striatum. However, no circadian variations were observed in the striatum of unilateral 6-OHDA-lesioned rats. Six weeks post-treatment, MLT levels correlated well with Glu and GABA levels at corresponding time-points in the striatum ipsilateral to the injected side in both groups, and increased MLT levels also correlated well with changes in Glu and GABA in the striatum in 6-OHDA-lesioned rats. These data suggest that 6-OHDA lesioning affects the endogenous productions of DA, MLT, Glu and GABA, and changes the MLT secretion pattern. Augmented striatal MLT levels and advanced MLT secretion pattern caused by unilateral intracerebral injection of 6-OHDA may influence the variations in Glu and GABA between day and night. PMID:25499317

Meng, T; Yuan, S; Zheng, Z; Liu, T; Lin, L



Manganese exposure inhibits the clearance of extracellular GABA and influences taurine homeostasis in the striatum of developing rats  

PubMed Central

Manganese (Mn) accumulation in the brain has been shown to alter the neurochemistry of the basal ganglia. Mn-induced alterations in dopamine biology are fairly well understood, but recently more evidence has emerged characterizing the role of ?-aminobutyric acid (GABA) in this dysfunction. The purpose of this study was to determine if the previously observed Mn-induced increase in extracellular GABA (GABAEC) was due to altered GABA transporter (GAT) function, and whether Mn perturbs other amino acid neurotransmitters, namely taurine and glycine (known modulators of GABA). Extracellular GABA, taurine, and glycine concentrations were collected from the striatum of control (CN) or Mn-exposed Sprague-Dawley rats using in vivo microdialysis, and the GAT inhibitor nipecotic acid (NA) was used to probe GAT function. Tissue and extracellular Mn levels were significantly increased, and the Fe:Mn ratio was decreased 36-fold in the extracellular space due to Mn exposure. NA led to a 2-fold increase in GABAEC of CNs, a response that was attenuated by Mn. Taurine responded inversely to GABA, and a novel 10-fold increase in taurine was observed after the removal of NA in CNs. Mn blunted this response and nearly abolished extracellular taurine throughout collection. Striatal taurine transporter (Slc6a6) mRNA levels were significantly increased with Mn exposure, and Mn significantly increased 3H-Taurine uptake after 3-minute exposure in primary rat astrocytes. These data suggest that Mn increases GABAEC by inhibiting the function of GAT, and that perturbed taurine homeostasis potentially impacts neural function by jeopardizing the osmoregulatory and neuromodulatory functions of taurine in the brain. PMID:20832424

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



GABA, glycine, aspartate, glutamate and taurine in the vestibular nuclei: an immunocytochemical investigation in the cat  

Microsoft Academic Search

The distributions of five amino acids with well-established neuroexcitatory or neuroinhibitory properties were investigated in the feline vestibular complex. Consecutive semithin sections of plastic-embedded tissue were incubated with antisera raised against protein-glutaraldehyde conjugates of GABA, glycine, aspartate, glutamate and taurine. This approach allowed us to study the relative densities of the different immunoreactivities at the level of individual cell profiles.

F. Walberg; O. P. Ottersen; E. Rinvik



Comment on "Oxytocin-mediated GABA inhibition during delivery attenuates autism pathogenesis in rodent offspring".  


Tyzio et al. (Reports, 7 February 2014, p. 675) reported that bumetanide restored the impaired oxytocin-mediated ?-aminobutyric acid (GABA) excitatory-inhibitory shift during delivery in animal models of autism, ameliorating some autistic-like characteristics in the offspring. However, standard practices in the study of these models, such as the use of sex-dimorphic or males-only analyses and implementation of tests measuring social behavior, are lacking to definitely associate their findings to autism. PMID:25301610

Bambini-Junior, Victorio; Nunes, Gustavo Della Flora; Schneider, Tomasz; Gottfried, Carmem



GABA? expression in the medial nucleus of the trapezoid body.  


The Calyx of Held (CoH) synapse is the largest synapse in mammals. It is located in the medial nucleus of the trapezoid body (MNTB) and forms part of the auditory pathway. Modest GABAergic signaling is present in the CoH before hearing onset, when glutamatergic transmission predominates. In mice, after postnatal day 12, the absolute strength of glycinergic transmission increases markedly, while GABAergic signaling remains constant. The persistent GABAergic transmission in the MNTB is mediated by a slowly desensitizing component. In this study we recorded GABA-mediated responses from postsynaptic principal neurons (PPNs) of the MNTB and found that they are sensitive to TPMPA, suggesting the involvement of GABA? subunits. RT-PCR and immunohistofluorescence in the MNTB confirmed GABA? expression in PPNs. Interestingly, GABA?3 was present only before hearing onset, and there was a switch to GABA?1 and GABA?2 expression in adult animals. PMID:23123780

Reyes-Haro, Daniel; Rosas-Arellano, Abraham; González-González, María Alejandra; Mora-Loyola, Ernesto; Miledi, Ricardo; Martínez-Torres, Ataúlfo



Fine structure of the dorsal lateral geniculate nucleus of the turtle, Emys orbicularis: a Golgi, combined HRP tracing and GABA immunocytochemical study.  


The afferent and efferent cortical projections of the dorsal lateral geniculate nucleus (GLD) of adult specimens of the turtle Emys orbicularis were investigated after intraocular or intracortical injections of horseradish peroxidase (HRP), and the distribution of gamma aminobutyric acid (GABA) immunoreactivity in the nucleus was carried out by immunocytochemical techniques, both techniques being combined with light and electron microscopy. In addition, some specimens were prepared for double-labeling of HRP and GABA immunoreactivity, and additional samples impregnated by a rapid Golgi technique. On purely morphological grounds, four types of neurons can be distinguished by light microscopy: two types of large cells in the cell plate which project to the cortex, and two types of smaller cells in the neuropil and optic tract which do not. The small cells are consistently GABA-immunoreactive, while the former are, with extremely rare exceptions, immunonegative for GABA. The supposition that the small neurons of the neuropil are interneurons is supported by electron microscopic observations; these strongly GABA-immunoreactive cells have large plicated nuclei surrounded by a thin layer of cytoplasm poorly endowed with organelles. The dendrites of these cells may contain pleomorphic synaptic vesicles (DCSVs) and appear to be presynaptic to other dendritic profiles. These DCSVs are occasionally contacted by GABA-immunoreactive axon terminals, and more frequently by retinal terminals consistently immunonegative for GABA. The latter, frequently organized in glomeruli, also make synaptic contacts with immunonegative dendrites arising from corticopetal neurons of the cell plate. Two major categories of GABA-immunoreactive axon terminals can be distinguished, and we are led to the conclusion that one of these represents an intrinsic GABAergic innervation of the GLD, while the second is tentatively interpreted as an extrinsic source of GABA to the nucleus, possibly from ventral thalamic structures. The fine structure of the dorsal lateral geniculate nucleus of Emys orbicularis thus shows many similarities with that of mammals. PMID:7560269

Kenigfest, N B; Repérant, J; Rio, J P; Belekhova, M G; tumanova, N L; Ward, R; Vesselkin, N P; Herbin, M; Chkeidze, D D; Ozirskaya, E V



Increased GABA Contributes to Enhanced Control over Motor Excitability in Tourette Syndrome  

PubMed Central

Summary Tourette syndrome (TS) is a developmental neurological disorder characterized by vocal and motor tics [1] and associated with cortical-striatal-thalamic-cortical circuit dysfunction [2, 3], hyperexcitability within cortical motor areas [4], and altered intracortical inhibition [4–7]. TS often follows a developmental time course in which tics become increasingly more controlled during adolescence in many individuals [1], who exhibit enhanced control over their volitional movements [8–11]. Importantly, control over motor outputs appears to be brought about by a reduction in the gain of motor excitability [6, 7, 12, 13]. Here we present a neurochemical basis for a localized gain control mechanism. We used ultra-high-field (7 T) magnetic resonance spectroscopy to investigate in vivo concentrations of ?-aminobutyric acid (GABA) within primary and secondary motor areas of individuals with TS. We demonstrate that GABA concentrations within the supplementary motor area (SMA)—a region strongly associated with the genesis of motor tics in TS [14]—are paradoxically elevated in individuals with TS and inversely related to fMRI blood oxygen level-dependent activation. By contrast, GABA concentrations in control sites do not differ from those of a matched control group. Importantly, we also show that GABA concentrations within the SMA are inversely correlated with cortical excitability in primary motor cortex and are predicted by motor tic severity and white-matter microstructure (FA) within a region of the corpus callosum that projects to the SMA within each hemisphere. Based upon these findings, we propose that extrasynaptic GABA contributes to a form of control, based upon localized tonic inhibition within the SMA, that may lead to the suppression of tics. PMID:25264251

Draper, Amelia; Stephenson, Mary C.; Jackson, Georgina M.; Pépés, Sophia; Morgan, Paul S.; Morris, Peter G.; Jackson, Stephen R.



Hypothalamic oxytocin attenuates CRF expression via GABA(A) receptors in rats.  


Centrally released oxytocin (OXT) has anxiolytic and anti-stress effects. Delayed gastric emptying (GE) induced by acute restraint stress (ARS) for 90 min is completely restored following 5 consecutive days of chronic homotypic restraint stress (CHS), via up-regulating hypothalamic OXT expression in rats. However, the mechanism behind the restoration of delayed GE following CHS remains unclear. Gamma-aminobutyric acid (GABA)-projecting neurons in the paraventricular nucleus (PVN) have been shown to inhibit corticotropin releasing factor (CRF) synthesis via GABA(A) receptors. We hypothesized that GABA(A) receptors are involved in mediating the inhibitory effect of OXT on CRF expression in the PVN, which in turn restores delayed GE following CHS. OXT (0.5 ?g) and selective GABA(A) receptor antagonist, bicuculline methiodide (BMI) (100 ng), were administered intracerebroventricularly (icv). Solid GE was measured under non-stressed (NS), ARS and CHS conditions. Expression of CRF mRNA in the PVN was evaluated by real time RT-PCR. Neither OXT nor BMI changed GE and CRF mRNA expression under NS conditions. Delayed GE and increased CRF mRNA expression induced by ARS were restored by icv-injection of OXT. The effects of OXT on delayed GE and increased CRF mRNA expression in ARS were abolished by icv-injection of BMI. Following CHS, delayed GE was completely restored in saline (icv)-injected rats, whereas daily injection of BMI (icv) attenuated the restoration of delayed GE. Daily injection of BMI (icv) significantly increased CRF mRNA expression following CHS. It is suggested that central OXT inhibits ARS-induced CRF mRNA expression via GABA(A) receptors in the PVN. GABAergic system is also involved in OXT-mediated adaptation response of delayed GE under CHS conditions. PMID:21382355

Bülbül, Mehmet; Babygirija, Reji; Cerjak, Diana; Yoshimoto, Sazu; Ludwig, Kirk; Takahashi, Toku



Colocalization of serotonin and GABA in retinal neurons of Ichthyophis kohtaoensis (amphibia; Gymnophiona).  


Ichthyophis kohtaoensis, a member of the limbless Gymnophiona, has a specialized subterranean burrowing mode of life and a predominantly olfactory-guided orientation. The only visually guided behavior seems to be negative phototaxis. As these animals possess extremely small eyes (only 540 microm in diameter in adults), functional investigations of single retinal cells by electrophysiological methods have so far failed. Therefore, the content and distribution of retinal transmitters have been investigated as indications of a functioning sense organ in an animal that is supposed to be blind. Previous immunohistochemical investigation of the retinal transmitter system revealed immunoreactivity for gamma-aminobutyric acid (GABA), serotonin, dopamine and tyrosine hydroxylase, the rate-limiting enzyme in the catecholamine synthetic pathway. The present studies have been performed in order to determine a possible colocalization of serotonin and GABA in retinal neurons of the caecilian retina. Therefore retinal cryostat sections of various developmental stages have been investigated by the indirect fluorescence method. In single-label preparations, serotonin is localized to cells in the inner nuclear layer and the ganglion cell layer. GABA immunocytochemistry labels a variety of cell types in the inner nuclear layer as well as cell bodies in the ganglion cell layer. In double-label preparations, some of the serotonergic cells are found to express GABA immunoreactivity and some GABAergic neurons also label for serotonin immunocytochemistry. Thus, despite the fact that caecilians mainly rely on olfaction and are believed to have a reduced visual system, their retina exhibits a surprisingly "normal" distribution of neurotransmitters and neuromodulators, also typical of other anamniotes with a well-developed visual system, including the partial colocalization of serotonin and GABA at all developmental stages of I. kohtaoensis. These results indicate that a functional system that is under no strong selective pressure obviously has a long evolutionary persistence irrespective of its need for use. PMID:9462859

Dünker, N



Increased GABA contributes to enhanced control over motor excitability in Tourette syndrome.  


Tourette syndrome (TS) is a developmental neurological disorder characterized by vocal and motor tics and associated with cortical-striatal-thalamic-cortical circuit dysfunction, hyperexcitability within cortical motor areas, and altered intracortical inhibition. TS often follows a developmental time course in which tics become increasingly more controlled during adolescence in many individuals, who exhibit enhanced control over their volitional movements. Importantly, control over motor outputs appears to be brought about by a reduction in the gain of motor excitability. Here we present a neurochemical basis for a localized gain control mechanism. We used ultra-high-field (7 T) magnetic resonance spectroscopy to investigate in vivo concentrations of ?-aminobutyric acid (GABA) within primary and secondary motor areas of individuals with TS. We demonstrate that GABA concentrations within the supplementary motor area (SMA)--a region strongly associated with the genesis of motor tics in TS--are paradoxically elevated in individuals with TS and inversely related to fMRI blood oxygen level-dependent activation. By contrast, GABA concentrations in control sites do not differ from those of a matched control group. Importantly, we also show that GABA concentrations within the SMA are inversely correlated with cortical excitability in primary motor cortex and are predicted by motor tic severity and white-matter microstructure (FA) within a region of the corpus callosum that projects to the SMA within each hemisphere. Based upon these findings, we propose that extrasynaptic GABA contributes to a form of control, based upon localized tonic inhibition within the SMA, that may lead to the suppression of tics. PMID:25264251

Draper, Amelia; Stephenson, Mary C; Jackson, Georgina M; Pépés, Sophia; Morgan, Paul S; Morris, Peter G; Jackson, Stephen R



A unified model of the GABA(A) receptor comprising agonist and benzodiazepine binding sites.  


We present a full-length ?(1)?(2)?(2) GABA receptor model optimized for agonists and benzodiazepine (BZD) allosteric modulators. We propose binding hypotheses for the agonists GABA, muscimol and THIP and for the allosteric modulator diazepam (DZP). The receptor model is primarily based on the glutamate-gated chloride channel (GluCl) from C. elegans and includes additional structural information from the prokaryotic ligand-gated ion channel ELIC in a few regions. Available mutational data of the binding sites are well explained by the model and the proposed ligand binding poses. We suggest a GABA binding mode similar to the binding mode of glutamate in the GluCl X-ray structure. Key interactions are predicted with residues ?(1)R66, ?(2)T202, ?(1)T129, ?(2)E155, ?(2)Y205 and the backbone of ?(2)S156. Muscimol is predicted to bind similarly, however, with minor differences rationalized with quantum mechanical energy calculations. Muscimol key interactions are predicted to be ?(1)R66, ?(2)T202, ?(1)T129, ?(2)E155, ?(2)Y205 and ?(2)F200. Furthermore, we argue that a water molecule could mediate further interactions between muscimol and the backbone of ?(2)S156 and ?(2)Y157. DZP is predicted to bind with interactions comparable to those of the agonists in the orthosteric site. The carbonyl group of DZP is predicted to interact with two threonines ?(1)T206 and ?(2)T142, similar to the acidic moiety of GABA. The chlorine atom of DZP is placed near the important ?(1)H101 and the N-methyl group near ?(1)Y159, ?(1)T206, and ?(1)Y209. We present a binding mode of DZP in which the pending phenyl moiety of DZP is buried in the binding pocket and thus shielded from solvent exposure. Our full length GABA(A) receptor is made available as Model S1. PMID:23308109

Bergmann, Rikke; Kongsbak, Kristine; Sørensen, Pernille Louise; Sander, Tommy; Balle, Thomas



Response to Comment on "Oxytocin-mediated GABA inhibition during delivery attenuates autism pathogenesis in rodent offspring".  


Bambini-Junior et al. questioned whether our treatment in two rodent models of autism has a long-lasting effect into adulthood. In response, we show that bumetanide treatment around delivery attenuates autistic behavioral features in adult offspring. Therefore, the polarity of ?-aminobutyric acid (GABA) actions during delivery exerts long-lasting priming actions after birth. PMID:25301611

Eftekhari, Sanaz; Shahrokhi, Amene; Tsintsadze, Vera; Nardou, Romain; Brouchoud, Corinne; Conesa, Magali; Burnashev, Nail; Ferrari, Diana C; Ben-Ari, Yehezkel



Cloning, Expression Patterns, and Chromosome Localization of Three Human and Two Mouse Homologues of GABA A Receptor-Associated Protein  

Microsoft Academic Search

Type A receptors of ?-aminobutyric acid (GABA), an inhibitory neurotransmitter, contain ?, ?, ?, ?, and ? subunits. The ? subunit has four subtypes: ?1, ?2, ?3, and?4. GABAA receptor-associated protein (GABARAP) was previously demonstrated to act as a linker protein between microtubules and the ?2 subunit of GABAA receptors. However, no other linker proteins have been identified as mediating

Yurong Xin; Long Yu; Zheng Chen; Lihua Zheng; Qiang Fu; Jianmin Jiang; Pingzhao Zhang; Romu Gong; Shouyuan Zhao



Brain gamma-aminobutyric acid deficiency in dialysis encephalopathy.  


We measured levels of gamma-aminobutyric acid (GABA) in the CSF and in the autopsied brain of patients with dialysis encephalopathy. GABA concentrations were low in the CSF of three of five living patients. Mean GABA content was reduced by 30 to 50% in five brain regions (frontal, occipital, and cerebellar cortex, caudate nucleus, and medial dorsal thalamus) in five fatal cases. GABA content was normal in brain regions where GABA is characteristically reduced in Huntington's disease. Choline acetyltransferase activity was diminished (by 25 to 35%) in cerebral cortex of the dialysis encephalopathy patients. PMID:3969205

Sweeney, V P; Perry, T L; Price, J D; Reeve, C E; Godolphin, W J; Kish, S J



Alterations of GABA and glutamate-glutamine levels in premenstrual dysphoric disorder: A 3T proton magnetic resonance spectroscopy study.  


Increasing evidence has suggested that the GABAergic neurotransmitter system is involved in the pathogenesis of premenstrual dysphoric disorder (PMDD). We used proton magnetic resonance spectroscopy ((1)H MRS) to investigate whether PMDD is associated with alterations in brain GABA levels. Levels of glutamate-glutamine (Glx) were also explored. Participants comprised 22 women with PMDD and 22 age-matched healthy controls who underwent 3T (1)H MRS during the late luteal phase of the menstrual cycle. GABA+ and Glx levels were quantified in the anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC) and the left basal ganglia (ltBG). Water-scaled GABA+ concentrations and GABA+/tCr ratios were significantly lower in both the ACC/mPFC and ltBG regions of PMDD women than in healthy controls. Glx/tCr ratios were significantly higher in the ACC/mPFC region of PMDD women than healthy controls. Our preliminary findings provide the first report of abnormal levels of GABA+ and Glx in mood-related brain regions of women with PMDD, indicating that dysregulation of the amino acid neurotransmitter system may be an important neurobiological mechanism in the pathogenesis of PMDD. PMID:25465316

Liu, Bo; Wang, Guangbin; Gao, Dongmei; Gao, Fei; Zhao, Bin; Qiao, Mingqi; Yang, Huan; Yu, Yanhong; Ren, Fuxin; Yang, Ping; Chen, Weibo; Rae, Caroline D



GABA and its B-receptor are present at the node of Ranvier in a small population of sensory fibers, implicating a role in myelination.  


The ?-aminobutyric acid (GABA) type B receptor has been implicated in glial cell development in the peripheral nervous system (PNS), although the exact function of GABA signaling is not known. To investigate GABA and its B receptor in PNS development and degeneration, we studied the expression of the GABAB receptor, GABA, and glutamic acid decarboxylase GAD65/67 in both development and injury in fetal dissociated dorsal root ganglia (DRG) cell cultures and in the rat sciatic nerve. We found that GABA, GAD65/67, and the GABAB receptor were expressed in premyelinating and nonmyelinating Schwann cells throughout development and after injury. A small population of myelinated sensory fibers displayed all of these molecules at the node of Ranvier, indicating a role in axon-glia communication. Functional studies using GABAB receptor agonists and antagonists were performed in fetal DRG primary cultures to study the function of this receptor during development. The results show that GABA, via its B receptor, is involved in the myelination process but not in Schwann cell proliferation. The data from adult nerves suggest additional roles in axon-glia communication after injury. © 2014 Wiley Periodicals, Inc. PMID:25327365

Corell, Mikael; Wicher, Grzegorz; Radomska, Katarzyna J; Da?l?koca, E Duygu; Godskesen, Randi Elberg; Fredriksson, Robert; Benedikz, Eirikur; Magnaghi, Valerio; Fex Svenningsen, Asa



Synthesis of  -Aminobutyric Acid by Lactic Acid Bacteria Isolated from a Variety of Italian Cheeses  

Microsoft Academic Search

The concentrations of -aminobutyric acid (GABA) in 22 Italian cheese varieties that differ in several technological traits markedly varied from 0.26 to 391 mg kg1. Presumptive lactic acid bacteria were isolated from each cheese variety (total of 440 isolates) and screened for the capacity to synthesize GABA. Only 61 isolates showed this activity and were identified by partial sequencing of

S. Siragusa; M. De Angelis; R. Di Cagno; C. G. Rizzello; R. Coda; M. Gobbetti



Anticonvulsant effects of some inhibitory neurotransmitter amino acids  

Microsoft Academic Search

The anticonvulsive effects of GABA, taurine, and glycine were investigated on several chemically-induced and genetic seizure models. Intravenous injections of either GABA, taurine, or glycine provided protection against 3-mercaptopropionic acid (MPA)-induced convulsions in adult Swiss mice. GABA was partially effective against isonicotinic acid hydrazide and was without effect against bicuculline-induced convulsions bProlonged administration of glycine prevented MPA-induced convulsions but not

Eugene Toth; Abel Lajtha; Shakir Sarhan; Nikolaus Seiler



Dissecting perception and memory-driven imagery by boosting GABA-ergic neurotransmission.  


Flanking lateral masks enhance or weaken the detection of a low-contrast visual target. This effect depends on the target-to-mask distance. An improvement of stimulus detection can also be observed when participants imagine (i.e., retrieve from memory) the previously presented masks. In this double-blind, placebo-controlled study, we show that the gamma-aminobutyric acid-A (GABAA) receptor agonist alprazolam disrupts perceptual but not imagery enhancement of contrast detection in individuals with generalized anxiety and adjustment disorder. The weakened target detection at short target-to-mask distances became more pronounced after the administration of the GABA-agonist in both perception and imagery conditions. Healthy control participants did not differ from individuals with generalized anxiety and adjustment disorder receiving placebo. These results indicate that perception and imagery can be dissociated by boosting GABA-ergic neurotransmission. Further studies are warranted to investigate this effect in healthy individuals. PMID:25451240

Kéri, Szabolcs



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

SciTech Connect

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

Huang, Fang; Fei, Jian; Guo, Li-He [Shanghai Institute of Cell Biology, Shanghai (China)] [and others] [Shanghai Institute of Cell Biology, Shanghai (China); and others



GABA and valproate modulate trigeminovascular nociceptive transmission in the thalamus  

Microsoft Academic Search

Objective: To study the role of GABA receptors in thalamic relay neurons in the ventroposteromedial (VPM) nucleus of the rat activated by a trigeminovascular nociceptive stimulus in relationship to migraine, and the potential modulation of nociceptive transmission by GABA acting anti-convulsants.Methods: Trigeminovascular nociceptive afferents were identified in the VPM by electrical stimulation of the superior sagittal sinus (SSS), and cell

Anna P. Andreou; Kevin G. Shields; Peter J. Goadsby



Neurotransmitter GABA Activates Muscle but Not ?7 Nicotinic Receptors.  


Cys-loop receptors are neurotransmitter-activated ion channels involved in synaptic and extrasynaptic transmission in the brain and are also present in non-neuronal cells. As GABAA and nicotinic receptors (nAChR) belong to this family, we explored by macroscopic and single-channel recordings whether the inhibitory neurotransmitter GABA has the ability to activate excitatory nAChRs. GABA differentially activates nAChR subtypes. It activates muscle nAChRs, with maximal peak currents of about 10% of those elicited by acetylcholine (ACh) and 15-fold higher EC50 with respect to ACh. At the single-channel level, the weak agonism is revealed by the requirement of 20-fold higher concentration of GABA for detectable channel openings, a major population of brief openings, and absence of clusters of openings when compared with ACh. Mutations at key residues of the principal binding-site face of muscle nAChRs (?Y190 and ?G153) affect GABA activation similarly as ACh activation, whereas a mutation at the complementary face (?G57) shows a selective effect for GABA. Studies with subunit-lacking receptors show that GABA can activate muscle nAChRs through the ?/? interface. Interestingly, single-channel activity elicited by GABA is similar to that elicited by ACh in gain-of-function nAChR mutants associated to congenital myasthenic syndromes, which could be important in the progression of the disorders due to steady exposure to serum GABA. In contrast, GABA cannot elicit single-channel or macroscopic currents of ?7 or the chimeric ?7-serotonin-type 3 receptor, a feature important for preserving an adequate excitatory/inhibitory balance in the brain as well as for avoiding activation of non-neuronal receptors by serum GABA. PMID:25492812

Dionisio, Leonardo; Bergé, Ignacio; Bravo, Matías; Esandi, María Del Carmen; Bouzat, Cecilia



Neurosteroids and GABA-A Receptor Function  

PubMed Central

Neurosteroids represent a class of endogenous steroids that are synthesized in the brain, the adrenals, and the gonads and have potent and selective effects on the GABAA-receptor. 3?-hydroxy A-ring reduced metabolites of progesterone, deoxycorticosterone, and testosterone are positive modulators of GABAA-receptor in a non-genomic manner. Allopregnanolone (3?-OH-5?-pregnan-20-one), 5?-androstane-3?, 17?-diol (Adiol), and 3?5?-tetrahydrodeoxycorticosterone (3?5?-THDOC) enhance the GABA-mediated Cl- currents acting on a site (or sites) distinct from the GABA, benzodiazepine, barbiturate, and picrotoxin binding sites. 3?5?-P and 3?5?-THDOC potentiate synaptic GABAA-receptor function and activate ?-subunit containing extrasynaptic receptors that mediate tonic currents. On the contrary, 3?-OH pregnane steroids and pregnenolone sulfate (PS) are GABAA-receptor antagonists and induce activation-dependent inhibition of the receptor. The activities of neurosteroid are dependent on brain regions and types of neurons. In addition to the slow genomic action of the parent steroids, the non-genomic, and rapid actions of neurosteroids play a significant role in the GABAA-receptor function and shift in mood and memory function. This review describes molecular mechanisms underlying neurosteroid action on the GABAA-receptor, mood changes, and cognitive functions. PMID:22654809

Wang, Mingde



Evidence for an Extended Duration of GABA-Mediated Excitation in the Developing Male Versus Female Hippocampus  

PubMed Central

?-Aminobutyric acid (GABA) is as an excitatory neurotransmitter during brain development. Activation of GABAA receptors in neonatal rat hippocampus results in chloride efflux and membrane depolarization sufficient to open voltage sensitive calcium channels. As development progresses, there is a decline in the magnitude of calcium influx subsequent to GABAA receptor activation and the number of cells that respond to GABA with excitation. By the second postnatal week in the rat, GABA action in the hippocampus is predominantly inhibitory. The functional consequences and endogenous regulation of developmental GABA-mediated excitation remains under-explored. Hippocampal neurons in the newborn male and female rat respond to GABAA receptor activation with increased intracellular calcium and are susceptible to GABA-mediated damage – both being indicative of the excitatory nature of GABA. In the present study we observed that by postnatal day 7, only males are susceptible to GABAA agonist-induced damage and respond to GABAA agonist administration with elevated levels of intracellular calcium in cultured hippocampal neurons. By postnatal day 14, GABAA agonist administration was without effect on intracellular calcium in both males and females. The age-related sex difference in the impact of GABAA receptor activation correlates with a sex difference in chloride co-transporter expression. Males have elevated protein levels of pNKCC1 on PN0 and PN7, with no sex difference by PN14. In contrast, females displayed elevated levels of KCC2 on PN7. This converging evidence infers that sex affects the duration of GABAA receptor-mediated excitation during normal hippocampal development, and provides a mechanism by which the effect is mediated. PMID:17823921

Nuñez, Joseph L.; McCarthy, Margaret M.



GABA-, glycine-, and glutamate-immunoreactive bouton profiles in apposition to neurons of the central cervical nucleus in the rat.  


The neurons of the central cervical nucleus (CCN) convey information about the position and movements of the head, and receive excitatory input from dorsal neck muscles and the labyrinth. Both of these afferent sources form glutamatergic synaptic contacts with CCN neurons. However, these sensory afferent sources can also inhibit CCN neurons. To further elucidate the synaptic organization, we made an electron microscopic investigation, identifying and evaluating the relative frequency of bouton profiles containing the inhibitory transmitters GABA and glycine in apposition to identified CCN neurons. In addition, labeling for glutamate was performed. The identification of the CCN neurons was made possible by injections of retrograde tracer substances into the cerebellum. These substances were made visible by preembedding immunocytochemistry or postembedding immunogold staining. Such staining was also used to detect the three amino acids that were found in boutons apposed to the identified neurons (cf. Ornung et al., J. Comp. Neurol. 1996;365:413-426; Lindå et al., J. Comp. Neurol. 2000;425:10-23). Due to the relatively poor transport of the tracer substances into dendrites of the CCN neurons, the analysis was restricted to the cell body and included bouton profiles in direct apposition to the soma membrane. Data from 10 CCN neurons revealed that about 50% of the apposing bouton profiles were immunoreactive for GABA, and about 34% for glycine. In four neurons, the degree of colocalization of GABA and glycine was determined to be close to 30%. Thus, the vast majority of glycine-labeled profiles also contained GABA, while a considerable fraction of the profiles were immunoreactive for only GABA. The values for glycine immunoreactive bouton profiles presented here may represent somewhat low estimates, depending on the method used. Data from four neurons showed that about 18% of the profiles were labeled for glutamate. The large fraction of purely GABA immunoreactive profiles, or at least a substantial group of them, is suggestive of their derivation from axons descending from the brainstem. PMID:11920385

Ragnarson, Birger; Yi, Seong Joon; Ulfhake, Brun; Grant, Gunnar



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

SciTech Connect

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

Peoples, R.W.



Competing pathways in the photo-Favorskii rearrangement and release of esters: Studies on fluorinated p-hydroxyphenacyl GABA and glutamate phototriggers  

PubMed Central

Three new trifluoromethylated p-hydroxyphenacyl (pHP) caged ?-aminobutyric acid (GABA) and glutamate (Glu) derivatives have been examined for their efficacy as photoremovable protecting groups in aqueous solution. By replacing hydrogen with fluorine, e.g., a m-trifluoromethyl or a m-trifluoromethoxy vs. m-methoxy substituents on the pHP chromophore, modest increases in the quantum yields for release of the amino acids GABA and glutamate were realized as well as improved lipophilicity. The pHP triplet undergoes a photo-Favorskii rearrangement with concomitant release of the amino acid substrate. Deprotonation competes with the rearrangement from the triplet excited state and yields the pHP conjugate base that, upon reprotonation, regenerate the starting ketoester, a chemically unproductive or “energy wasting” process. Employing picosecond pump–probe spectroscopy, GABA derivatives 2 – 5 are characterized by short triplet lifetimes, a manifestation of their rapid release of GABA. The bioavailability of released GABA at the GABAA receptor improved when the release took place from m-OCF3 (2) but decreased for m-CF3 (3) when compared with the parent pHP derivative. These studies demonstrate that pKa and lipophilicity exert significant but sometimes opposing influences on the photochemistry and biological activity of pHP phototriggers. PMID:19572582

Stensrud, Kenneth; Noh, Jihyun; Kandler, Karl; Wirz, Jakob; Heger, Dominik



Virus-induced gene silencing reveals control of reactive oxygen species accumulation and salt tolerance in tomato by ?-aminobutyric acid metabolic pathway.  


?-Aminobutyric acid (GABA) accumulates in many plant species in response to environmental stress. However, the physiological function of GABA or its metabolic pathway (GABA shunt) in plants remains largely unclear. Here, the genes, including glutamate decarboxylases (SlGADs), GABA?transaminases (SlGABA-Ts) and succinic semialdehyde dehydrogenase (SlSSADH), controlling three steps of the metabolic pathway of GABA, were studied through virus-induced gene silencing approach in tomato. Silencing of SlGADs (GABA biosynthetic genes) and SlGABA-Ts (GABA catabolic genes) led to increased accumulation of reactive oxygen species (ROS) as well as salt sensitivity under 200?mm NaCl treatment. Targeted quantitative analysis of metabolites revealed that GABA decreased and increased in the SlGADs- and SlGABA-Ts-silenced plants, respectively, whereas succinate (the final product of GABA metabolism) decreased in both silenced plants. Contrarily, SlSSADH-silenced plants, also defective in GABA degradation process, showed dwarf phenotype, curled leaves and enhanced accumulation of ROS in normal conditions, suggesting the involvement of a bypath for succinic semialdehyde catabolism to ?-hydroxybutyrate as reported previously in Arabidopsis, were less sensitive to salt stress. These results suggest that GABA shunt is involved in salt tolerance of tomato, probably by affecting the homeostasis of metabolites such as succinate and ?-hydroxybutyrate and subsequent ROS accumulation under salt stress. PMID:25074245

Bao, Hexigeduleng; Chen, Xianyang; Lv, Sulian; Jiang, Ping; Feng, Juanjuan; Fan, Pengxiang; Nie, Lingling; Li, Yinxin



Immunocytochemical Localization of Amines and GABA in the Optic Lobe of the Butterfly, Papilio xuthus  

PubMed Central

Butterflies have sophisticated color vision. While the spectral organization of the compound eye has been well characterized in the Japanese yellow swallowtail butterfly, Papilio xuthus, neural mechanisms underlying its color vision are largely unexplored. Towards a better understanding of signal processing in the visual system of P. xuthus, we used immunocytochemical techniques to analyze the distribution of transmitter candidates, namely, histamine, serotonin, tyramine and ?-aminobutyric acid (GABA). Photoreceptor terminals in the lamina and medulla exhibited histamine immunoreactivity as demonstrated in other insects. The anti-histamine antiserum also labeled a few large medulla neurons. Medulla intrinsic neurons and centrifugal neurons projecting to the lamina showed serotonin immunoreactivity. Tyramine immunostaining was detected in a subset of large monopolar cells (LMCs) in the lamina, transmedullary neurons projecting to the lobula plate, and cell bodies surrounding the first optic chiasma. An anti-GABA antiserum labeled a subset of LMCs and populations of columnar and tangential neurons surrounding the medulla. Each of the four antisera also labeled a few centrifugal neurons that innervate the lobula complex from the central brain, suggesting that they have neuromodulatory roles. A distinctive feature we found in this study is the possibility that tyramine and GABA act as transmitters in LMCs of P. xuthus, which has not been reported in any other insects so far. PMID:22844431

Hamanaka, Yoshitaka; Kinoshita, Michiyo; Homberg, Uwe; Arikawa, Kentaro



Glutamate spillover augments GABA synthesis and release from axodendritic synapses in rat hippocampus  

PubMed Central

Tight coupling between GABA synthesis and vesicle filling suggests that the presynaptic supply of precursor glutamate could dynamically regulate inhibitory synapses. Although the neuronal glutamate transporter Excitatory Amino Acid Transporter 3 (EAAT3) has been proposed to mediate such a metabolic role, highly efficient astrocytic uptake of synaptically released glutamate normally maintains low extracellular glutamate levels. We examined whether axodendritic inhibitory synapses in stratum radiatum of hippocampal area CA1, which are closely positioned among excitatory glutamatergic synapses, are regulated by synaptic glutamate release via presynaptic uptake. Under conditions of spatially and temporally coordinated release of glutamate and GABA within pyramidal cell dendrites, blocking glial glutamate uptake enhanced quantal release of GABA in a transporter-dependent manner. These physiological findings correlated with immunohistochemical studies revealing expression of EAAT3 by interneurons and uptake of D-asparate into putative axodendritic inhibitory terminals only when glial uptake was blocked. These results indicate that spillover of glutamate between adjacent excitatory and inhibitory synapses can occur under conditions when glial uptake incompletely clears synaptically released glutamate. Our anatomical studies also suggest that perisomatic inhibitory synapses, unlike synapses within dendritic layers of hippocampus, are not capable of glutamate uptake and therefore transporter-mediated dynamic regulation of inhibition is a unique feature of axodendritic synapses that may play a role in maintaining a homeostatic balance of inhibition and excitation. PMID:19338018

Stafford, Misty M.; Brown, Molly N.; Mishra, Puneet; Stanwood, Gregg D.; Mathews, Gregory C.



Analysis of Glutamate, GABA, Noradrenaline, Dopamine, Serotonin, and Metabolites Using Microbore UHPLC with Electrochemical Detection  

PubMed Central

The applicability of microbore ultrahigh performance liquid chromatography (UHPLC) with electrochemical detection for offline analysis of a number of well-known neurotransmitters in less than 10 ?L microdialysis fractions is described. Two methods are presented for the analysis of monoamine or amino acid neurotransmitters, using the same UHPLC instrument. Speed of analysis of noradrenaline (NA), dopamine (DA), serotonin (5-HT), and the metabolites homovanillic acid (HVA), 5-hydroxyindole aceticacid (5-HIAA), and 3,4-dihydroxyphenylacetic acid (DOPAC) was predominated by the retention behavior of NA, the nonideal behavior of matrix components, and the loss in signal of 5-HT. This method was optimized to meet the requirements for detection sensitivity and minimizing the size of collected fractions, which determines temporal resolution in microdialysis. The amino acid neurotransmitters glutamate (Glu) and ?-aminobutyric acid (GABA) were analyzed after an automated derivatization procedure. Under optimized conditions, Glu was resolved from a number of early eluting system peaks, while the total runtime was decreased to 15 min by a 4-fold increase of the flow rate under UHPLC conditions. The detection limit for Glu and GABA was 10 nmol/L (15 fmol in 1.5 ?L); the monoamine neurotransmitters had a detection limit between 32 and 83 pmol/L (0.16–0.42 fmol in 5 ?L) in standard solutions. Using UHPLC, the analysis times varied from 15 min to less than 2 min depending on the complexity of the samples and the substances to be analyzed. PMID:23642417



Polycomblike protein PHF1b: a transcriptional sensor for GABA receptor activity  

PubMed Central

Background The ?-aminobutyric acid (GABA) type A receptor (GABAAR) contains the recognition sites for a variety of agents used in the treatment of brain disorders, including anxiety and epilepsy. A better understanding of how receptor expression is regulated in individual neurons may provide novel opportunities for therapeutic intervention. Towards this goal we have studied transcription of a GABAAR subunit gene (GABRB1) whose activity is autologously regulated by GABA via a 10 base pair initiator-like element (?1-INR). Methods By screening a human cDNA brain library with a yeast one-hybrid assay, the Polycomblike (PCL) gene product PHD finger protein transcript b (PHF1b) was identified as a ?1-INR associated protein. Promoter/reporter assays in primary rat cortical cells demonstrate that PHF1b is an activator at GABRB1, and chromatin immunoprecipitation assays reveal that presence of PHF1 at endogenous Gabrb1 is regulated by GABAAR activation. Results PCL is a member of the Polycomb group required for correct spatial expression of homeotic genes in Drosophila. We now show that PHF1b recognition of ?1-INR is dependent on a plant homeodomain, an adjacent helix-loop-helix, and short glycine rich motif. In neurons, it co-immunoprecipitates with SUZ12, a key component of the Polycomb Repressive Complex 2 (PRC2) that regulates a number of important cellular processes, including gene silencing via histone H3 lysine 27 trimethylation (H3K27me3). Conclusions The observation that chronic exposure to GABA reduces PHF1 binding and H3K27 monomethylation, which is associated with transcriptional activation, strongly suggests that PHF1b may be a molecular transducer of GABAAR function and thus GABA-mediated neurotransmission in the central nervous system. PMID:23879974



Compartmentalization of GABA Synthesis by GAD67 Differs between Pancreatic Beta Cells and Neurons  

PubMed Central

The inhibitory neurotransmitter GABA is synthesized by the enzyme glutamic acid decarboxylase (GAD) in neurons and in pancreatic ?-cells in islets of Langerhans where it functions as a paracrine and autocrine signaling molecule regulating the function of islet endocrine cells. The localization of the two non-allelic isoforms GAD65 and GAD67 to vesicular membranes is important for rapid delivery and accumulation of GABA for regulated secretion. While the membrane anchoring and trafficking of GAD65 are mediated by intrinsic hydrophobic modifications, GAD67 remains hydrophilic, and yet is targeted to vesicular membrane pathways and synaptic clusters in neurons by both a GAD65-dependent and a distinct GAD65-independent mechanism. Herein we have investigated the membrane association and targeting of GAD67 and GAD65 in monolayer cultures of primary rat, human, and mouse islets and in insulinoma cells. GAD65 is primarily detected in Golgi membranes and in peripheral vesicles distinct from insulin vesicles in ?-cells. In the absence of GAD65, GAD67 is in contrast primarily cytosolic in ?-cells; its co-expression with GAD65 is necessary for targeting to Golgi membranes and vesicular compartments. Thus, the GAD65-independent mechanism for targeting of GAD67 to synaptic vesicles in neurons is not functional in islet ?-cells. Therefore, only GAD65:GAD65 homodimers and GAD67:GAD65 heterodimers, but not the GAD67:GAD67 homodimer gain access to vesicular compartments in ?-cells to facilitate rapid accumulation of newly synthesized GABA for regulated secretion and fine tuning of GABA-signaling in islets of Langerhans. PMID:25647668

Kanaani, Jamil; Cianciaruso, Chiara; Phelps, Edward A.; Pasquier, Miriella; Brioudes, Estelle; Billestrup, Nils; Baekkeskov, Steinunn



Non-neuronal, slow GABA signalling in the ventrobasal thalamus targets ?-subunit-containing GABAA receptors  

PubMed Central

The rodent ventrobasal (VB) thalamus contains a relatively uniform population of thalamocortical (TC) neurons that receive glutamatergic input from the vibrissae and the somatosensory cortex, and inhibitory input from the nucleus reticularis thalami (nRT). In this study we describe ?-aminobutyric acid (GABA)A receptor-dependent slow outward currents (SOCs) in TC neurons that are distinct from fast inhibitory postsynaptic currents (IPSCs) and tonic currents. SOCs occurred spontaneously or could be evoked by hypo-osmotic stimulus, and were not blocked by tetrodotoxin, removal of extracellular Ca2+ or bafilomycin A1, indicating a non-synaptic, non-vesicular GABA origin. SOCs were more common in TC neurons of the VB compared with the dorsal lateral geniculate nucleus, and were rarely observed in nRT neurons, whilst SOC frequency in the VB increased with age. Application of THIP, a selective agonist at ?-subunit-containing GABAA receptors, occluded SOCs, whereas the benzodiazepine site inverse agonist ?-CCB had no effect, but did inhibit spontaneous and evoked IPSCs. In addition, the occurrence of SOCs was reduced in mice lacking the ?-subunit, and their kinetics were also altered. The anti-epileptic drug vigabatrin increased SOC frequency in a time-dependent manner, but this effect was not due to reversal of GABA transporters. Together, these data indicate that SOCs in TC neurons arise from astrocytic GABA release, and are mediated by ?-subunit-containing GABAA receptors. Furthermore, these findings suggest that the therapeutic action of vigabatrin may occur through the augmentation of this astrocyte–neuron interaction, and highlight the importance of glial cells in CNS (patho) physiology. PMID:21395866

Jiménez-González, Cristina; Pirttimaki, Tiina; Cope, David W; Parri, H R



Motor dysfunction in cerebellar Purkinje cell-specific vesicular GABA transporter knockout mice  

PubMed Central

?-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the adult mammalian central nervous system and plays modulatory roles in neural development. The vesicular GABA transporter (VGAT) is an essential molecule for GABAergic neurotransmission due to its role in vesicular GABA release. Cerebellar Purkinje cells (PCs) are GABAergic projection neurons that are indispensable for cerebellar function. To elucidate the significance of VGAT in cerebellar PCs, we generated and characterized PC-specific VGAT knockout (L7-VGAT) mice. VGAT mRNAs and proteins were specifically absent in the 40-week-old L7-VGAT PCs. The morphological characteristics, such as lamination and foliation of the cerebellar cortex, of the L7-VGAT mice were similar to those of the control littermate mice. Moreover, the protein expression levels and patterns of pre- (calbindin and parvalbumin) and postsynaptic (GABA-A receptor ?1 subunit and gephyrin) molecules between the L7-VGAT and control mice were similar in the deep cerebellar nuclei that receive PC projections. However, the L7-VGAT mice performed poorly in the accelerating rotarod test and displayed ataxic gait in the footprint test. The L7-VGAT mice also exhibited severer ataxia as VGAT deficits progressed. These results suggest that VGAT in cerebellar PCs is not essential for the rough maintenance of cerebellar structure, but does play an important role in motor coordination. The L7-VGAT mice are a novel model of ataxia without PC degeneration, and would also be useful for studying the role of PCs in cognition and emotion. PMID:24474904

Kayakabe, Mikiko; Kakizaki, Toshikazu; Kaneko, Ryosuke; Sasaki, Atsushi; Nakazato, Yoichi; Shibasaki, Koji; Ishizaki, Yasuki; Saito, Hiromitsu; Suzuki, Noboru; Furuya, Nobuhiko; Yanagawa, Yuchio



Mechanisms of carbacholine and GABA action on resting membrane potential and Na+/K+-ATPase of Lumbricus terrestris body wall muscles.  


This work was aimed to identify the action of several ion channel and pump inhibitors as well as nicotinic, GABAergic, purinergic and serotoninergic drugs on the resting membrane potential (RMP) and assess the role of cholinergic and GABAergic sensitivity in earthworm muscle electrogenesis. The nicotinic agonists acetylcholine (ACh), carbacholine (CCh) and nicotine depolarize the RMP at concentrations of 5 ?M and higher. The nicotinic antagonists (+)tubocurarine, ?-bungarotoxin, muscarinic antagonists atropine and hexamethonium do not remove or prevent the CCh-induced depolarization. Verapamil, tetrodotoxin, removal of Cl(-) and Ca(2+) from the solution also cannot prevent the depolarization by CCh. In a Na(+)-free medium, however, CCh lost this depolarization ability and this indicates that the drug opens the sodium permeable pathway. Serotonin, glutamate, glycine, adenosine triphosphate (ATP) and cis-4-aminocrotonic acid (GABA(C) receptor antagonist) had no effect on the RMP. On the other hand, isoguvacin, ?-aminobutyric acid (GABA) and baclofen (GABA(B) receptor agonist) hyperpolarized the RMP. Ouabain, bicucullin (GABA(A) antagonist) and phaclofen (GABA(B) antagonist), as well as the removal of Cl(-), suppressed the effect of GABA and baclofen. CCh did not enhance the depolarization generated by ouabain but, on the other hand, hindered the hyperpolarizing activity of baclofen both in the absence and presence of atropine and (+)tubocurarine. The long-term application of CCh depolarizes the RMP primarily by inhibiting the Na(+)/K(+)-ATPase. The muscle membrane also contains A and B type GABA binding sites, the activation of which increases the RMP at the expense of increasing the action of ouabain- and Cl(-) -sensitive electrogenic pumps. PMID:21184841

Volkov, Eugeny M; Nurullin, Leniz F; Volkov, Michael E; Nikolsky, Eugeny E; Vysko?il, Frantisek



Presynaptic modulation by L-glutamate and GABA of sympathetic co-transmission in rat isolated vas deferens.  

PubMed Central

1. The modulatory effects of L-glutamate and its structural analogues, and of gamma-aminobutyric acid (GABA), on sympathetic co-transmission were studied in the rat isolated vas deferens exposed to electrical field stimulation (EFS). 2. Application of exogenous L-glutamate caused a concentration-dependent (1 microM-3 mM) inhibition of the rapid twitch component of the biphasic EFS contraction. However, L-glutamate (1 microM-3 mM) had a minimal effect on the phasic contraction induced by exogenous adenosine 5'-triphosphate (ATP, 150 microM) and noradrenaline (50 microM). Unlike L-glutamate, D-glutamate had no effect on the EFS contraction. 3. The L-glutamate-induced inhibition of the EFS contractions was significantly attenuated by the glutamate decarboxylase (GAD) inhibitor 3-mercapto-propionic acid (150 microM) and was abolished in the presence of the GABA transaminase (GABA-T) inhibitor, 2-aminoethyl hydrogen sulphate (500 microM). 4. The L-glutamate-induced inhibition of the electrically evoked contraction was not affected by the adenosine A1-receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX)(30 nM), reactive blue 2 (30 microM) or the GABAA receptor antagonist bicuculline (50 microM). However, the GABAB receptor antagonist 2-hydroxysaclofen (50 microM) significantly inhibited the L-glutamate effect. 5. Similar to L-glutamate, GABA also caused a concentration-dependent (0.1-100 microM) inhibition of the EFS contractions. This GABA-induced inhibition was not affected by either the GABAA receptor antagonist bicuculline (50 microM) or reactive blue 2 (30 microM). However, a significant attenuation of the GABA-mediated effect was recorded with the GABAB receptor antagonist 2-hydroxysaclofen (50 microM). Contractions of the vas deferens induced by exogenous ATP and noradrenaline were not affected by GABA (0.1-100 microM). 6. The L-glutamate analogues, N-methyl-D-aspartate (NMDA) (1 microM-1 mM) and quisqualate (Quis 0.1 microM-0.3 mM) had no effect, whilst kainate (Kain, 1 microM-1 mM) caused an inhibition of the EFS-induced contractions. Effects of Kain could be abolished by the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dioxine (CNQX, 10 microM). NMDA, Quis and Kain had no effect on the exogenous ATP- or noradrenaline-induced contractions. 7. It is concluded that the excitatory amino acid L-glutamate modulates the electrically evoked vas deferens contraction through conversion to the inhibitory amino acid GABA by a specific GABA transaminase. The GABA formed may then act on GABAB receptors and cause inhibition of the contraction through a presynaptic mechanism. PMID:8762104

Kwan, Y. W.; Ngan, M. P.; Tsang, K. Y.; Lee, H. M.; Chu, L. A.



Contribution of GABA(A) and GABA(B) receptors to thalamic neuronal activity during spontaneous absence seizures in rats.  


The contribution of GABAergic mechanisms in thalamic relay nuclei to spike and wave discharges (SWDs) during spontaneous seizures was assessed using the WAG/Rij strain of rats, an established genetic model of absence epilepsy, in combination with single-unit recordings and microiontophoretic techniques in the ventrobasal thalamic complex in vivo. Spontaneous SWDs occurring on the electroencephalogram at 5-9 Hz were associated with burst firing in thalamocortical neurons, which was phase-locked with the spike component. Microiontophoretic application of the GABA(A) receptor antagonist bicuculline significantly increased the magnitude of SWD-related firing in all tested cells. Application of the GABA(B) receptor antagonist CGP 55845A exerted a statistically insignificant modulatory effect on neuronal activity during spontaneous SWDs but significantly attenuated the bicuculline-evoked aggravation of SWD-related firing. The data indicate that, in thalamocortical neurons, (1) GABA(A) receptor-mediated events are recruited with each SWD, (2) SWD-related activity can be evoked with no significant contribution of GABA(B) receptors, and (3) blockade of GABA(A) receptors potentiates SWD-related activity, presumably through an indirect effect mediated through GABA(B) receptors. These results vote against a predominant or even exclusive contribution of GABA(B) receptors to spontaneous SWDs in thalamic relay nuclei in the WAG/Rij strain, but rather point to a critical role of GABA(A) receptor activation. This conclusion is in support of the view that the two subtypes of GABA receptors play a differential role in fast (5-10 Hz) and slow (3 Hz) spike-wave paroxysms observed during absence seizures. PMID:11160409

Staak, R; Pape, H C



Endogenous GABA(A) and GABA(B) receptor-mediated electrical suppression is critical to neuronal anoxia tolerance.  


Anoxic insults cause hyperexcitability and cell death in mammalian neurons. Conversely, in anoxia-tolerant turtle brain, spontaneous electrical activity is suppressed by anoxia (i.e., spike arrest; SA) and cell death does not occur. The mechanism(s) of SA is unknown but likely involves GABAergic synaptic transmission, because GABA concentration increases dramatically in anoxic turtle brain. We investigated this possibility in turtle cortical neurons exposed to anoxia and/or GABA(A/B) receptor (GABAR) modulators. Anoxia increased endogenous slow phasic GABAergic activity, and both anoxia and GABA reversibly induced SA by increasing GABA(A)R-mediated postsynaptic activity and Cl(-) conductance, which eliminated the Cl(-) driving force by depolarizing membrane potential (?8 mV) to GABA receptor reversal potential (?-81 mV), and dampened excitatory potentials via shunting inhibition. In addition, both anoxia and GABA decreased excitatory postsynaptic activity, likely via GABA(B)R-mediated inhibition of presynaptic glutamate release. In combination, these mechanisms increased the stimulation required to elicit an action potential >20-fold, and excitatory activity decreased >70% despite membrane potential depolarization. In contrast, anoxic neurons cotreated with GABA(A+B)R antagonists underwent seizure-like events, deleterious Ca(2+) influx, and cell death, a phenotype consistent with excitotoxic cell death in anoxic mammalian brain. We conclude that increased endogenous GABA release during anoxia mediates SA by activating an inhibitory postsynaptic shunt and inhibiting presynaptic glutamate release. This represents a natural adaptive mechanism in which to explore strategies to protect mammalian brain from low-oxygen insults. PMID:21690381

Pamenter, Matthew E; Hogg, David W; Ormond, Jake; Shin, Damian S; Woodin, Melanie A; Buck, Leslie T



gamma-Aminobutyric acid stimulates ethylene biosynthesis in sunflower.  

PubMed Central

gamma-Aminobutyric acid (GABA), a nonprotein amino acid, is often accumulated in plants following environmental stimuli that can also cause ethylene production. We have investigated the relationship between GABA and ethylene production in excised sunflower (Helianthus annuus L.) tissues. Exogenous GABA causes up to a 14-fold increase in the ethylene production rate after about 12 h. Cotyledons fed with [14C]GABA did not release substantial amounts of radioactive ethylene despite its chemical similarity to 1-aminocyclopropane-1-carboxylic acid (ACC), indicating that GABA is not likely to be an alternative precursor for ethylene. GABA causes increases in ACC synthase mRNA accumulation, ACC levels, ACC oxidase mRNA levels, and in vitro ACC oxidase activity. In the presence of aminoethoxyvinylglycine or alpha-aminoisobutyric acid, GABA did not stimulate ethylene production. We therefore conclude that GABA stimulates ethylene biosynthesis mainly by promoting ACC synthase transcript abundance. Possible roles of GABA as a signal transducer are suggested. PMID:9306696

Kathiresan, A; Tung, P; Chinnappa, C C; Reid, D M



Morphological heterogeneity of the GABAergic network in the suprachiasmatic nucleus, the brain's circadian pacemaker  

PubMed Central

GABA (gamma-amino-butyric acid) is the predominant neurotransmitter in the mammalian suprachiasmatic nucleus (SCN), with a central role in circadian time-keeping. We therefore undertook an ultrastructural analysis of the GABA-containing innervation in the SCN of mice and rats using immunoperoxidase and immunogold procedures. GABA-immunoreactive (GABA-ir) neurons were identified by use of anti-GABA and anti-GAD (glutamic acid decarboxylase) antisera. The relationship between GABA-ir elements and the most prominent peptidergic neurons in the SCN, containing vasopressin-neurophysin (VP-NP) or vasoactive intestinal polypeptide (VIP), was also studied. Within any given field in the SCN, approximately 40–70% of the neuronal profiles were GABA-ir. In GABA-ir somata, immunogold particles were prominent over mitochondria, sparse over cytoplasm, and scattered as aggregates over nucleoplasm. In axonal boutons, gold particles were concentrated over electron-lucent synaptic vesicles (diameter 40–60 nm) and mitochondria, and in some instances over dense-cored vesicles (DCVs, diameter 90–110 nm). GABA-ir boutons formed either symmetric or asymmetric synaptic contacts with somata, dendritic shafts and spines, and occasionally with other terminals (axo-axonic). Homologous or autaptic connections (GABA on GABA, or GAD on GAD) were common. Although GABA appeared to predominate in most neuronal profiles, colocalisation of GABA within neurons that were predominantly neuropeptide-containing was also evident. About 66% of the VIP-containing boutons and 32% of the vasopressinergic boutons contained GABA. The dense and complex GABAergic network that pervades the SCN is therefore comprised of multiple neuronal phenotypes containing GABA, including a wide variety of axonal boutons that impinge on heterologous and homologous postsynaptic sites. PMID:10697283




Experiment K-6-18. Study of muscarinic and gaba (benzodiazepine) receptors in the sensory-motor cortex, hippcampus and spinal code  

NASA Technical Reports Server (NTRS)

Frontal lobe samples of rat brains flown aboard Cosmos 1887 were processed for the study of muscarinic (cholinergic) and GABA (benzodiazepine) receptors and for immunocytochemical localization of the neurotransmitter gamma-aminobutyric acid (GABA) and glial fibrillary acidic protein (GFAP). Although radioactive labeling of both muscarinic cholinergic and GABA (benzodiazepine) receptors proved to be successful with the techniques employed, distinct receptor localization of individual laminae of the frontal neocortex was not possible since the sampling of the area was different in the various groups of animals. In spite of efforts made for proper orientation and regional identification of laminae, it was found that a densitometric (quantitation of autoradiograms) analysis of the tissue did not contribute to the final interpretation of the effects of weightlessness on these receptors. As to the immunocytochemical studies the use of both markers, GFAP and GABA antiserum, confirmed the suitability of the techniques for use in frozen material. However, similar problems to those encountered in the receptor studies prevented an adequate interpretation of the effects of micro-G exposure on the localization and distribution of GABA and GFAP. This study did, however, confirm the feasibility of investigating neurotransmitters and their receptors in future space flight experiments.

Daunton, N.; Damelio, F.; Krasnov, I.



Influence of processing on the generation of ? -aminobutyric acid in green coffee beans  

Microsoft Academic Search

A determination of the concentrations of free amino acids in differently processed green coffees indicated the nonprotein amino acid ?-aminobutyric acid (GABA), a well-known plant stress metabolite, to be present in raw coffee beans (Coffea arabica L.) in significantly varying amounts. The GABA content of unwashed Arabica beans (green coffee produced by the dry processing method) was always markedly higher

Gerhard Bytof; Sven-Erik Knopp; Peter Schieberle; Ingo Teutsch; Dirk Selmar



The voltage-dependent nature of the GABA-induced conductance change recorded from the ganglion cell of Aplysia.  


gamma-Aminobutyric acid (GABA) produces 2 types of hyperpolarizing responses in Aplysia ganglion cells: One is fast and Cl(-)-dependent whereas the other is slow and K+-dependent. This experiment was performed only on the cells which showed the fast, Cl(-)-dependent receptor activity. GABA-induced increase in membrane conductance (delta G) was evaluated under the voltage clamp at different potential levels of the resting membrane. The delta G was found to decrease when the membrane was hyperpolarized. The more the membrane was hyperpolarized, the greater was the decrease. The dose-response curve shifted to the right when the resting membrane was hyperpolarized, a fact suggesting an increase in apparent dissociation constant (Kapparent) of the receptor-GABA complex. In fact, Kapparent increased e-fold for every 11-mV hyperpolarization of the resting membrane. In contrast, neither parameter of other receptor activities, such as the rate of desensitization, the intrinsic activity, and the Hill coefficient, was altered by hyperpolarization of the receptor membrane. It was concluded that the voltage dependent nature observed in this type of GABA receptor might be due to the change in stability of the Cl(-)-channel in an open state at the receptor membrane. PMID:6281505

Matsumoto, M



[GABA(B) receptors and sensitization to pain].  


The GABA(B) receptors belong to the family of class C metabotropic receptors. They are inhibitory receptors forming obligatory heterodimers. Their analgesic role in the dorsal horn of the spinal cord is well established since more than 25 years ago. However, Baclofen, the reference agonist of the GABA(B) receptor, proved to have little efficiency in clinics in neuropathic patients. It seems therefore useful to decipher GABA(B) functions in the nociceptive circuitry, and their regulation in conditions of chronic pain. In the present review, we will focus first on the distribution of the GABA(B) subtypes. Then, we will consider their pre- and post-synaptic functions in the dorsal horn of naïve rats. Finally, we will document the mechanisms that may lead to receptor impairment in neuropathic conditions. PMID:19358814

Landry, Marc; Nagy, Frédéric



Discovery and optimization of an azetidine chemical series as a free fatty acid receptor 2 (FFA2) antagonist: from hit to clinic.  


FFA2, also called GPR43, is a G-protein coupled receptor for short chain fatty acids which is involved in the mediation of inflammatory responses. A class of azetidines was developed as potent FFA2 antagonists. Multiparametric optimization of early hits with moderate potency and suboptimal ADME properties led to the identification of several compounds with nanomolar potency on the receptor combined with excellent pharmacokinetic (PK) parameters. The most advanced compound, 4-[[(R)-1-(benzo[b]thiophene-3-carbonyl)-2-methyl-azetidine-2-carbonyl]-(3-chloro-benzyl)-amino]-butyric acid 99 (GLPG0974), is able to inhibit acetate-induced neutrophil migration strongly in vitro and demonstrated ability to inhibit a neutrophil-based pharmacodynamic (PD) marker, CD11b activation-specific epitope [AE], in a human whole blood assay. All together, these data supported the progression of 99 toward next phases, becoming the first FFA2 antagonist to reach the clinic. PMID:25380412

Pizzonero, Mathieu; Dupont, Sonia; Babel, Marielle; Beaumont, Stéphane; Bienvenu, Natacha; Blanqué, Roland; Cherel, Laëtitia; Christophe, Thierry; Crescenzi, Benedetta; De Lemos, Elsa; Delerive, Philippe; Deprez, Pierre; De Vos, Steve; Djata, Fatoumata; Fletcher, Stephen; Kopiejewski, Sabrina; L'Ebraly, Christelle; Lefrançois, Jean-Michel; Lavazais, Stéphanie; Manioc, Murielle; Nelles, Luc; Oste, Line; Polancec, Denis; Quénéhen, Vanessa; Soulas, Florilène; Triballeau, Nicolas; van der Aar, Ellen M; Vandeghinste, Nick; Wakselman, Emanuelle; Brys, Reginald; Saniere, Laurent



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

PubMed Central

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

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



Effects of non-sedative anxiolytic drugs on responses to GABA and on diazepam-induced enhancement of these responses on mouse neurones in cell culture.  

PubMed Central

1. Intracellular microelectrode recording techniques were performed on mouse spinal cord and cerebral hemisphere neurones grown in primary dissociated cell culture. The effects of several anxiolytics applied by local pressure ejection on responses to gamma-aminobutyric acid (GABA) evoked by iontophoresis were investigated. Responses to GABA were depolarizing since intracellular chloride ion concentration was increased by injection from potassium chloride (3M)-filled recording micropipettes and neurones were held at large negative membrane potentials (-70 to -90 mV). The agents studied were six 'non-sedative anxiolytics', CL 218,872 (3-methyl-6-(3-trifluoromethyl-phenyl)1,2,4-triazolo(4,3-b) pyridazine), PK 8165 (2-phenyl-4-(2-(4-piperidinyl)ethyl)-quinoline), PK 9084 (2-phenyl-4-(2-(3-piperidinyl)ethyl)-quinoline), CGS 9896 (2-(4-chlorophenyl)-2,5-dihydropyrazolo(4,3-c)quinoline-3(3H)-one) , ZK 91296 (ethyl 5-benzyloxy-4-methoxymethyl-beta-carboline-3-beta-carboxylate), buspirone (8-4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl-8-azaspiro[4.5]decane- 7,9- dione), and two sedative anxiolytics, diazepam and zopiclone [( 6-(5-chloro-2-pyridyl)-6,7-dihydro-7-oxo-5H-pyrrolo[3,4-b]pyrazin- 5- yl]4-methyl-1-piperazinecarboxylate). 2. Direct effects on responses to GABA were studied for all drugs applied in varying concentrations. For the drugs which significantly altered responses to GABA, the effects of the benzodiazepine receptor antagonists Ro 15-1788 (ethyl-8-fluoro-5,6-dihydro-5-methyl-6-oxo-4H-imidazo(1,5a)-(1,4)benzodi azepine - 3-carboxylate) and CGS 8216 (2-phenylpyrazolo(4,3-c)-quinolin-3(5H)-one) were evaluated. For the drugs devoid of significant direct effect on responses to GABA, the influence on diazepam-induced enhancement of responses to GABA was evaluated. 3. Diazepam, zopiclone and CL 218,872 concentration-dependently and reversibly enhanced responses to GABA. Maximal enhancement was 82% for diazepam (500 nM), 64% for zopiclone (10 microM) and 20% for CL 218,872 (10 microM). PK 8165 effects varied with concentration, enhancing responses to GABA (up to 18%) at nM concentrations and reducing responses to GABA (up to 90%) at microM concentrations. CGS 9896, ZK 9126, PK 9084 and buspirone, in concentrations ranging from 1 nM to 10 microM, lacked significant direct effects on responses to GABA.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2905900

De Deyn, P. P.; Macdonald, R. L.



Gamma-Aminobutyric Acid Binding to Receptor Sites in the Rat Central Nervous System  

PubMed Central

[3H]Gamma-aminobutyric acid (GABA) binds to synaptic membrane fractions of rat brain in a selective fashion representing an interaction with postsynaptic GABA receptors. Inhibition of [3H]GABA binding by a variety of amino acids closely parallels their ability to mimic the synaptic inhibitory actions of GABA and does not correlate with their relative affinity for the presynaptic synaptosomal GABA uptake system. [3H]GABA binding is saturable with an affinity constant of about 0.1 ?M. The GABA antagonist bicuculline inhibits [3H]GABA binding with half maximal effects at 5 ?M, whereas it requires a concentration of 0.5 mM to reduce synaptosomal GABA uptake by 50%. In subcellular fractionation experiments [3H]GABA binding is most enriched in crude synaptic membranes. [3H]GABA binding is greatest in the cerebellum, least in the spinal cord and medulla oblongatapons, with intermediate values in the thalamus, hippocampus, hypothalamus, cerebral cortex, midbrain, and corpus striatum. PMID:4155072

zukin, Stephen R.; Young, Anne B.; Snyder, Solomon H.



Control of cortical neuronal migration by glutamate and GABA  

PubMed Central

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

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



GABA-independent GABAA Receptor Openings Maintain Tonic Currents  

PubMed Central

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

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



Cloning, purification, crystallization and preliminary X-ray analysis of a bacterial GABA receptor with a Venus flytrap fold.  


In response to infection by the pathogen Agrobacterium tumefaciens, plants synthesize several stress amino acids, including gamma-aminobutyric acid (GABA), which modulates the expression of bacterial virulence factors. GABA penetrates into the bacterial cytoplasm via an ABC transporter that is associated with the periplasmic receptor Atu2422. Mature receptor Atu2422 (without its signal peptide) was overexpressed in Escherichia coli, purified and crystallized. A complete data set was collected to 1.35 A resolution at 100 K. The crystals belonged to the monoclinic space group C2 and contained one molecule in the asymmetric unit. Molecular replacement was performed and the initial electron-density maps revealed a closed form of this Venus flytrap (VFT) receptor, suggesting the presence of an endogenous E. coli ligand. PMID:19052373

Moréra, Solange; Gueguen-Chaignon, Virginie; Raffoux, Aurélie; Faure, Denis



Interactions between glutamate, GABA, acetylcholine and histamine in the periaqueductal gray's control of vocalization in the squirrel monkey.  


In the squirrel monkey (Saimiri sciureus), vocalization was elicited by periaqueductal injections of the glutamate agonist homocysteic acid, the acetylcholine agonist carbachol, the GABA antagonist bicuculline and the monoaminergic transmitter histamine. All chemically induced vocalizations could be blocked completely by prior periaqueductal injections of the non-specific glutamate antagonist kynurenic acid and the GABA agonist muscimol. The acetylcholine antagonist scopolamine and the histamine antagonist diphenhydramine, in contrast, blocked their respective transmitter agonists' vocalizations but had only a minor effect on glutamatergically induced vocalizations. It is concluded that the periaqueductal control of vocalization is brought about by the simultaneous activation of glutamatergic and inhibition of GABAergic mechanisms. Acetylcholine and histamine seem to play only a modulatory role. PMID:8100054

Jürgens, U; Lu, C L



Effect of intracerebroventricular injection of GABA receptor agents on morphine-induced antinociception in the formalin test  

Microsoft Academic Search

In the present study, the effects of &ggr;-aminobutyric acid (GABA) receptor agonists and antagonists on antinociception induced by morphine in the formalin test were investigated in rats. Intraperitoneal (i.p.) injection of different doses of morphine (1, 3, 6 and 9 mg\\/kg) and intracerebroventricular (i.c.v.) injection of different doses of muscimol (0.5, 1 and 2 &mgr;g per rat) or baclofen (0.25,

Mitra Mahmoudi; Mohammad-Reza Zarrindast



Correlation between GABA A receptor density and vagus nerve stimulation in individuals with drug-resistant partial epilepsy  

Microsoft Academic Search

Vagus nerve stimulation (VNS) is an important option for the treatment of drug-resistant epilepsy. Through delivery of a battery-supplied intermittent current, VNS protects against seizure development in a manner that correlates experimentally with electrophysiological modifications. However, the mechanism by which VNS inhibits seizures in humans remains unclear. The impairment of ?-aminobutyric acid (GABA)-mediated neuronal inhibition associated with epilepsy has suggested

Francesco Marrosu; Alessandra Serra; Alberto Maleci; Monica Puligheddu; Giovanni Biggio; Mario Piga



The pharmacological profile of ELIC, a prokaryotic GABA-gated receptor  

PubMed Central

The Erwinia ligand-gated ion channel (ELIC) is a bacterial homologue of vertebrate Cys-loop ligand-gated ion channels. It is activated by GABA, and this property, combined with its structural similarity to GABAA and other Cys-loop receptors, makes it potentially an excellent model to probe their structure and function. Here we characterise the pharmacological profile of ELIC, examining the effects of compounds that could activate or inhibit the receptor. We confirm that a range of amino acids and classic GABAA receptor agonists do not elicit responses in ELIC, and we show the receptor can be at least partially activated by 5-aminovaleric acid and ?-hydroxybutyric acid, which are weak agonists. A range of GABAA receptor non-competitive antagonists inhibit GABA-elicited ELIC responses including ?-endosulfan (IC50 = 17 ?M), dieldrin (IC50 = 66 ?M), and picrotoxinin (IC50 = 96 ?M) which were the most potent. Docking suggested possible interactions at the 2? and 6? pore-lining residues, and mutagenesis of these residues supports this hypothesis for ?-endosulfan. A selection of compounds that act at Cys-loop and other receptors also showed some efficacy at blocking ELIC responses, but most were of low potency (IC50 > 100 ?M). Overall our data show that a number of compounds can inhibit ELIC, but it has limited pharmacological similarity to GLIC and to Cys-loop receptors. PMID:22677470

Thompson, Andrew J.; Alqazzaz, Mona; Ulens, Chris; Lummis, Sarah C.R.



GABA Receptors Genes Polymorphisms and Alcohol Dependence: No Evidence of an Association in an Italian Male Population  

PubMed Central

Objective The genes encoding for gamma-aminobutyric acid (GABA) A and B receptors may be considered as candidates for alcoholism; genetic alterations at this level may produce structural and functional diversity and thus play a role in the response to alcohol addiction treatment. To investigate these aspects further, we conducted a preliminary genetic association study on a population of Italian male alcohol addicts, focusing on GABA A and B receptors. Methods A total of 186 alcohol-dependent subjects (in the first phase 139, then 47 more samples) and 182 controls were genotyped for 25 single nucleotide polymorphisms (SNPs) of genes encoding the alpha-1 subunit of GABA A receptor (GABRA1) and subunits 1 and 2 of GABA B receptor (GABBR1 and GABBR2). The chi-squared test for allele and genotype distributions and Hardy-Weinberg equilibrium analysis of both subjects and controls were performed. Bonferroni's correction for multiple comparisons was applied. Results Preliminary results comparing 139 alcohol-dependent subjects and 182 controls showed differences in genotype distribution in the former for SNP rs29253, located in the intron region of the GABBR1 gene. In order to clarify the meaning of this association, 47 more samples from alcohol-dependent subjects were tested for this SNP only: the previously found association was not confirmed. Conclusion The lack of significant differences between the two groups does not provide evidence that GABRA 1 and GABBR1 and 2 genes are candidates for alcoholism in this population. Further studies with larger samples are needed, together with investigation of other components of the GABA pathway. PMID:25191505

Tucci, Marianna; Di Pietra, Laura; Ferrara, Santo Davide



Axonal transport of [3H] GABA and [3H] glutamate in excitatory and inhibitory neurons innervating lobster exoskeletal musculature.  


This paper describes the results of intracellular injections of radiolabelled neurotransmitters and transmitter precursor substances, including glutamate, GABA, aspartate, octopamine, tyramine, tryptophan, and choline, into cell bodies of identified excitatory and inhibitory neurons innervating lobster extensor musculature. The distributions and identities of radioactive substances appearing in axons were examined at various times following injection and in vitro incubation. Injected GABA and glutamate were found in appreciable quantities in both excitatory and inhibitory axons and migrated down axons at an estimated rate of between 16 and 22 mm/day at 12 degrees C, whereas the other substances tested were present in substantially smaller quantities and migrated at an estimated rate of less than 7.5 mm/day at 12 degrees C. Injected GABA, D-glutamate and L-glutamate accumulated proximal to ligatures tied around nerves, whereas neither octopamine nor aspartate accumulated proximal to ligatures. Since GABA is the transmitter substance released by inhibitory neurons and L-glutamate is thought to be released from excitatory nerve terminals, these results are consistent with the suggestion that amino acids serving as neurotransmitters are axonally transported. The specificity of axonal transport does not appear to be restricted to the cognate neurotransmitter, as indicated by the movement of L-glutamate in inhibitory axons and GABA in excitatory axons and of D-glutamate in both excitatory and inhibitory axons, but rather may be relaxed to include substances closely related to the neurotransmitter. Some restrictions, however, are apparently placed on axonal transport of small charged molecules in these neurons in that other substances tested migrated down nerves at a considerably slower rate. PMID:6199461

Woodward, W R



Quantum Dot Conjugates of GABA and Muscimol: Binding to ?1?2?2 and ?1 GABAA Receptors  

PubMed Central

GABAA receptors are ligand-gated ion channels that mediate inhibitory synaptic signaling in the CNS. Fluorescent probes with the ability to target these receptors can provide insights into receptor location, distribution and dynamics in live cells, while revealing abnormalities in their distribution and dynamics that could occur in a variety of diseases. We have developed fluorescent probes of GABAA receptors that are composed of a CdSe/ZnS core–shell nanocrystal (quantum dot; qdot) conjugated to pegylated derivatives of the GABA receptor agonists GABA and muscimol (GABA-qdots and muscimol-qdots, respectively). Quantitative fluorescence imaging was used to analyze the binding activity of these conjugates to ?1?2?2 GABAA and ?1 GABAA receptors expressed in Xenopus oocytes. The selectivity of these conjugates for ?1?2?2 GABAA and ?1 GABAA receptors was determined by their ability to compete with the antagonists bicuculline and methyl-(1,2,3,6-tetrahydropyridin-4-yl)phosphinic acid (TPMPA). Both GABA- and muscimol-qdots exhibited robust binding to both ?1?2?2 and ?1 GABAA receptors. At ?1?2?2 receptors, pretreatment with bicuculline reduced conjugate binding by ?8-fold on average, an extent far exceeding the reduction produced by TPMPA (?30%). Conversely, at ?1 receptors, pretreatment with TPMPA inhibited binding by ?10-fold, an extent greatly exceeding the change produced by bicuculline (?50% or less). These results indicate specific binding of muscimol-qdots and GABA-qdots to ?1?2?2 GABAA and ?1 GABAA receptors in a manner that preserves the respective pharmacological sensitivities of these receptors to TPMPA and bicuculline, and encourage the use of qdot-conjugated neurotransmitter analogs as labeling agents at GABAA receptors. PMID:23509979



Uncoupling at the GABA(A) receptor with chronic ethanol in the rat medial septum/diagonal band (MS/DB)  

E-print Network

suggests that the y-aminobutyric acid typeA(GABA,) receptor is one target of ethanol where such adaptive changes by the CNS may occur. Adaptation could occur by downregulation of GABAAreceptor number or uncoupling of the GABAAreceptor sensitivity to ethanol...

Wallace, Kathleen Allison



Expression of mammalian gamma-aminobutyric acid receptors with distinct pharmacology in Xenopus oocytes.  

PubMed Central

Gamma-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in mammalian brain, is known to interact with two classes of GABA receptors denoted GABAA and GABAB. Using Xenopus oocytes, we compared the electrical and pharmacological properties of GABA receptors expressed by poly(A)+ RNA isolated from mammalian brain and retina. RNA from cerebral cortex expressed GABA responses with features characteristic of currents mediated by GABAA receptors. In contrast, RNA from retina expressed responses mediated by GABAA receptors and, in addition, GABA responses that were insensitive to the GABAA antagonist bicuculline and the GABAB agonist baclofen and showed no modulation by barbiturates or benzodiazepines. The bicuculline/baclofen-insensitive GABA response was a Cl- current that was blocked by picrotoxin but showed little desensitization or outward rectification. Our results suggest that mammalian retina contains RNAs encoding GABA receptors with distinct pharmacology. Images PMID:1709741

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



Cerebral radioprotection by pentobarbital: Dose-response characteristics and association with GABA agonist activity  

SciTech Connect

Pentobarbital reduces cerebral radiation toxicity; however, the mechanism of this phenomenon remains unknown. As an anesthetic and depressant of cerebral metabolism, pentobarbital induces its effects on the central nervous system by stimulating the binding of gamma-aminobutyric acid (GABA) to its receptor and by inhibiting postsynaptic excitatory amino acid activity. The purpose of this study is to investigate the role of these actions as well as other aspects of the radioprotective activity of pentobarbital. Fischer 344 rats were separated into multiple groups and underwent two dose-response evaluations. In one set of experiments to examine the relationship of radioprotection to pentobarbital dose, a range of pentobarbital doses (0 to 75 mg/kg) were given intraperitoneally prior to a constant-level radiation dose (70 Gy). In a second series of experiments to determine the dose-response relationship of radiation protection to radiation dose, a range of radiation doses (10 to 90 Gy) were given with a single pentobarbital dose. Further groups of animals were used to evaluate the importance of the timing of pentobarbital administration, the function of the (+) and (-) isomers of pentobarbital, and the role of an alternative GABA agonist (diazepam). In addition, the potential protective effects of alternative methods of anesthesia (ketamine) and induction of cerebral hypometabolism (hypothermia) were examined. Enhancement of survival time from acute radiation injury due to high-dose single-fraction whole-brain irradiation was maximal with 60 mg/kg of pentobarbital, and occurred over the range of all doses examined between 30 to 90 Gy. Protection was seen only in animals that received the pentobarbital before irradiation. Administration of other compounds that enhance GABA binding (Saffan and diazepam) also significantly enhanced survival time.

Olson, J.J.; Friedman, R.; Orr, K.; Delaney, T.; Oldfield, E.H. (National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD (USA))



Altered GABA Signaling in Early Life Epilepsies  

PubMed Central

The incidence of seizures is particularly high in the early ages of life. The immaturity of inhibitory systems, such as GABA, during normal brain development and its further dysregulation under pathological conditions that predispose to seizures have been speculated to play a major role in facilitating seizures. Seizures can further impair or disrupt GABAA signaling by reshuffling the subunit composition of its receptors or causing aberrant reappearance of depolarizing or hyperpolarizing GABAA receptor currents. Such effects may not result in epileptogenesis as frequently as they do in adults. Given the central role of GABAA signaling in brain function and development, perturbation of its physiological role may interfere with neuronal morphology, differentiation, and connectivity, manifesting as cognitive or neurodevelopmental deficits. The current GABAergic antiepileptic drugs, while often effective for adults, are not always capable of stopping seizures and preventing their sequelae in neonates. Recent studies have explored the therapeutic potential of chloride cotransporter inhibitors, such as bumetanide, as adjunctive therapies of neonatal seizures. However, more needs to be known so as to develop therapies capable of stopping seizures while preserving the age- and sex-appropriate development of the brain. PMID:21826277

Briggs, Stephen W.; Galanopoulou, Aristea S.



Evidence of GABA-immunopositive neurons in the dorsal part of the lateral geniculate nucleus of reptiles: morphological correlates with interneurons.  


The distribution and staining pattern of gamma-aminobutyric acid immunoreactivity have been examined by both light and electron microscopy in the dorsal part of the lateral geniculate nucleus of three reptilian species: the turtle Chinemys reevesi, the lizard Ophisaurus apodus and the snake Vipera aspis. After perfusion of the animals with 1% paraformaldehyde and 1% glutaraldehyde and polyethyleneglycol embedding of the brains, the analysis of sections processed immunocytochemically with an anti-GABA antiserum has revealed a moderate-to-dense labeling of the neurons of the dorsal part of the lateral geniculate complex in these species. Labeled cell bodies are small-sized, either rounded or fusiform and the GABA-positive dendrites emerging from them are not preferentially oriented in any particular direction. Quantitative studies in Vipera indicate that GABA-positive neurons make up about 14% of the population of neurons of the dorsal part of the lateral geniculate nucleus. Electron microscopy of specimens treated by either pre- or post-embedding techniques has confirmed that these cells corresponded to neurons. No glial cells were ever observed to be immunopositive. These GABA-positive neurons, characterized by the presence of pleiomorphic synaptic vesicles localized either in their perikaryon or more often in presynaptic dendrites, established symmetrical synaptic contacts. In this case, the latter were involved both pre- and postsynaptically in serial and, more rarely, in triadic arrangements, a synaptic organization specific to interneurons. The involvement of such GABA-positive neurons in local circuits is discussed. PMID:1641130

Rio, J P; Reperant, J; Ward, R; Miceli, D; Medina, M



Metabotropic ?-aminobutyric acid (GABAB) receptors modulate feeding behavior in the calcisponge Leucandra aspera.  


Here, we report the presence of the ?-aminobutyric acid (GABA)-ergic system in the calcisponge Leucandra aspera and examine the cellular localization of the components of this system, including GABA-like receptors using immunofluorescence and confocal microscopy. Furthermore, we demonstrate for the first time that GABA plays a functional role as a messenger in regulating sponge-feeding behavior. We found that both GABA(B) R1 and R2 subunits are present in the choanocytes of sponges as well as in the eso- and endopinacocytes. The functional role of GABA in the feeding behavior of this sponge was tested. The involvement of GABA receptors in the endocytic processes in L. aspera was demonstrated with dextran conjugated to Texas Red as a marker for material ingestion and by treating isolated sponge cells with a GABA(B) receptor agonist and an antagonist. The amount of dextran that was ingested increased in dissociated sponge cells when the GABA(B) receptor agonist baclofen was used, and this stimulatory effect was prevented by treatment with the GABA(B) receptor antagonist phaclofen. The baclofen effect on uptake was blocked by treatment with pertussis toxin, thus indicating a role for G proteins in modulating feeding behavior in L. aspera. Moreover, we found evidence that GABA receptors are involved in the consumption of dissolved organic matter by sponge cells. These findings suggest that GABA receptors and their functional role are highly conservative traits in the animal kingdom prenervous system evolution. PMID:21370481

Ramoino, Paola; Ledda, Fabio D; Ferrando, Sara; Gallus, Lorenzo; Bianchini, Paolo; Diaspro, Alberto; Fato, Marco; Tagliafierro, Grazia; Manconi, Renata



Molecular pharmacology of an insect GABA receptor  

E-print Network

Abbreviations 3-APP 3-aminopropylphosphonic acid 4-AB 4-amino-1-butanol 5-AV 5-aminopentanoic acid 5-HT 5-hydroxy-tryptamine aa Amino acid Å angstrom (1×10?10 M) ACh Acetylcholine AChBP Acetylcholine binding protein APS Ammonium persulfate...

McGonigle, Ian Vincent



Effect of cocaine on responsiveness of alpha(1)-adrenergic receptors in rat cerebral cortex: modulation by GABA-mimetic drugs.  


We investigated the effects of single doses of cocaine (10 mg/kg, ip) and the gamma-aminobutyric acid (GABA)-mimetics tiagabine (10 mg/kg, ip) and vigabatrin (150 mg/kg, ip) injected separately or concomitantly with cocaine, on the responsiveness of cerebral cortical alpha(1)-adrenergic receptors. The accumulation of noradrenaline-stimulated inositol phosphates was estimated in vitro at 2 and 24 h after the drug injection. Cocaine significantly enhanced alpha(1)-adrenergic receptor responsiveness to noradrenaline. Neither tiagabine nor vigabatrin influenced the accumulation of inositol phosphates. Finally, the cocaine-evoked augmentation of alpha(1)-adrenoceptor responsiveness was counteracted by tiagabine but not by vigabatrin. This effect may represent a characteristic feature of tiagabine, not necessarily shared by other GABA-mimetic drugs. PMID:19211992

Wieczerzak, Krzysztof; Witarski, Tadeusz; Kowalska, Marta; Nawrat, Dominika; Roman, Adam; Bielawski, Adam; Nalepa, Irena



Rapid regulation of tonic GABA currents in cultured rat hippocampal neurons  

PubMed Central

Subacute and chronic changes in tonic GABAergic inhibition occur in human and experimental epilepsy. Less is known about how tonic inhibition is modulated over shorter time frames (seconds). We measured endogenous tonic GABA currents from cultured rat hippocampal neurons to evaluate how they are affected by 1) transient increases in extracellular GABA concentration ([GABA]), 2) transient postsynaptic depolarization, and 3) depolarization of presynaptic cells. Transient increases in [GABA] (1 ?M) reduced tonic currents; this reduction resulted from GABA-induced shifts in the reversal potential for GABA currents (EGABA). Transient depolarization of postsynaptic neurons reversed the effects of exogenous GABA and potentiated tonic currents. The voltage-dependent potentiation of tonic GABA currents was independent of EGABA shifts and represented postdepolarization potentiation (PDP), an intrinsic GABAA receptor property (Ransom CB, Wu Y, Richerson GB. J Neurosci 30: 7672–7684, 2010). Inhibition of vesicular GABA release with concanamycin A (ConA) did not affect tonic currents. In ConA-treated cells, transient application of 12 mM K+ to depolarize presynaptic neurons and glia produced a persistent increase in tonic current amplitude. The K+-induced increase in tonic current was reversibly inhibited by SKF89976a (40 ?M), indicating that this was caused by nonvesicular GABA release from GABA transporter type 1 (GAT1). Nonvesicular GABA release due to GAT1 reversal also occurred in acute hippocampal brain slices. Our results indicate that tonic GABA currents are rapidly regulated by GABA-induced changes in intracellular Cl? concentration, PDP of extrasynaptic GABAA receptors, and nonvesicular GABA release. These mechanisms may influence tonic inhibition during seizures when neurons are robustly depolarized and extracellular GABA and K+ concentrations are elevated. PMID:23114210

Tao, Wucheng; Wu, Yuanming; Spain, William J.; Richerson, George B.



Refuting the challenges of the developmental shift of polarity of GABA actions: GABA more exciting than ever!  

PubMed Central

During brain development, there is a progressive reduction of intracellular chloride associated with a shift in GABA polarity: GABA depolarizes and occasionally excites immature neurons, subsequently hyperpolarizing them at later stages of development. This sequence, which has been observed in a wide range of animal species, brain structures and preparations, is thought to play an important role in activity-dependent formation and modulation of functional circuits. This sequence has also been considerably reinforced recently with new data pointing to an evolutionary preserved rule. In a recent “Hypothesis and Theory Article,” the excitatory action of GABA in early brain development is suggested to be “an experimental artefact” (Bregestovski and Bernard, 2012). The authors suggest that the excitatory action of GABA is due to an inadequate/insufficient energy supply in glucose-perfused slices and/or to the damage produced by the slicing procedure. However, these observations have been repeatedly contradicted by many groups and are inconsistent with a large body of evidence including the fact that the developmental shift is neither restricted to slices nor to rodents. We summarize the overwhelming evidence in support of both excitatory GABA during development, and the implications this has in developmental neurobiology. PMID:22973192

Ben-Ari, Yehezkel; Woodin, Melanie A.; Sernagor, Evelyne; Cancedda, Laura; Vinay, Laurent; Rivera, Claudio; Legendre, Pascal; Luhmann, Heiko J.; Bordey, Angelique; Wenner, Peter; Fukuda, Atsuo; van den Pol, Anthony N.; Gaiarsa, Jean-Luc; Cherubini, Enrico



Glutamate and GABA imbalance promotes neuronal apoptosis in hippocampus after stress  

PubMed Central

Background People who experience traumatic events have an increased risk of post-traumatic stress disorder (PTSD). However, PTSD-related pathological changes in the hippocampus and prefrontal cortex remain poorly understood. Material/Methods We investigated the effect of a PTSD-like animal model induced by severe stress. The experimental rats received 20 inescapable electric foot shocks in an enclosed box for a total of 6 times in 3 days. The physiological state (body weight and plasma corticosterone concentrations), emotion, cognitive behavior, brain morphology, apoptosis, and balance of gamma-aminobutyric acid (GABA) and glutamate in the hippocampus and prefrontal cortex were observed. Cell damages were examined with histological staining (HE, Nissl, and silver impregnation), while apoptosis was analyzed with flow cytometry using an Annexin V and propidium iodide (PI) binding and terminal deoxynucleotidyl transferase mediated-dUTP nick end labeling (TUNEL) method. Results In comparison with the sham litter-mates, the stressed rats showed decreased body weight, inhibition of hypothalamic-pituitary-adrenal (HPA) axis activation, increase in freezing response to trauma reminder, hypoactivity and anxiety-like behaviors in elevated plus maze and open field test, poor learning in Morris water maze, and shortened latency in hot-plate test. There were significant damages in the hippocampus but not in the prefrontal cortex. Imbalance between glutamate and GABA was more evident in the hippocampus than in the prefrontal cortex. Conclusions These results suggest that neuronal apoptosis in the hippocampus after severe traumatic stress is related to the imbalance between glutamate and GABA. Such modifications may resemble the profound changes observed in PTSD patients. PMID:24675061

Gao, Jie; Wang, He; Liu, Yuan; Li, Ying-yu; Chen, Can; Liu, Liang-ming; Wu, Ya-min; Li, Sen; Yang, Ce



Enkephalin-like immunoreactivity in the cat superior colliculus: distribution, ultrastructure, and colocalization with GABA.  


The distribution of enkephalin (ENK) immunoreactivity has been examined in the cat superior colliculus (SC) by means of light and electron microscope immunocytochemistry. The antisera were directed against leucine enkephalin but also recognized methionine enkephalin. Colocalization of ENK with gamma aminobutyric acid (GABA) was studied with a two-chromagen double-labeling technique. Enkephalin antiserum labeling was highly specific. Dense neuropil labeling was found only in a thin band 75-100 microns wide within the upper superficial gray layer of SC. Negligible neuropil labeling was seen deeper, except for patches of label within the intermediate gray layer. Intensely labeled neurons also had a specific distribution. Forty-seven percent were located within the upper 200 microns of SC, 40% within the deep superficial gray layer, 11% in the optic layer, and only 2% below that layer. Almost all ENK-labeled cells were small (mean area of 117 microns2). Some of these had horizontal fusiform cell bodies and horizontally oriented dendrites. Others had small round somata and thin, obliquely oriented dendrites. In double-labeling experiments, 18% of anti-ENK-labeled cells were also immunoreactive for GABA. Four distinct types of ENK-labeled profile were identified with the electron microscope. Presynaptic dendrites (PSD) with loose accumulations of synaptic vesicles were densely labeled with the antiserum. Conventional dendrites were also labeled. Both types of labeled profile received input from unlabeled synaptic terminals, including those from the retina that contained pale mitochondria and round synaptic vesicles and formed asymmetric synaptic contacts. Retinal terminals were never labeled with the antisera. However, some axon terminals with round synaptic vesicles, dark mitochondria, and symmetric synaptic densities were labeled by the antisera, as were some thinly myelinated axons. These results show that there is a small population of enkephalinergic neurons in the cat SC, some of which also contain GABA. Because not all cells with identical morphologies were double labeled, it appears that neurons of like morphology are chemically heterogeneous. PMID:2754046

Mize, R R



GABA-receptor complex in monkeys treated with MPTP  

SciTech Connect

Tissue samples from the brains of monkeys made parkinsonian by the depletion of dopamine (DA) with dopaminergic neurotoxin (N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (1.4-3.4 mg/kg, i.v.) were assayed for changed in GABA ((/sup 3/H)-GABA), benzodiazepine ((/sup 3/H)-flunitrazepam) and picrotoxin ((/sup 35/S)-TBPS) binding sites. One point binding assays were performed on globus pallidus (GP), substantia nigra reticulata (SN/sub R/) and VA-VL thalamic samples. GABA binding was markedly increased in the SN/sub R/ (129 +/- 12%, n = 2) and GP (108 +/- 33%, n = 4) and not altered in the striatum or thalamus. However, benzodiazepine binding was increased in the striatum (170%; 257 fm/mg, control; 692 fm/mg, treated) and GP (28%; 317 fm/mg, control, 405 fm/mg, treated) and (/sup 35/S)-TBPS binding was also increased in GP (100%; 32.5 fm/mg, control; 65.5 fm/mg, treated). atScatchard analysis of (/sup 3/H)-GABA binding was also performed on tissue samples of motor cortex, cerebellar vermis and striatum pooled from half brains of 4 parkinsonian and 2 control monkeys. Depletion of DA (92 +/- 5%) in the striatum of these monkeys was not associated with any change in the K/sub D/ or B/sub max/ for the high or low affinity GABA binding sites in the striatum, motor cortex or cerebellum. Thus, in the basal ganglia, DA depletion is associated with an increase in GABA binding sites in GP and SN/sub R/, an increase in picrotoxin binding sites in GP and an increase in benzodiazepine binding sites in the striatum.

Huffman, R.D.; Ticku, M.K.



New Insights into ?-Aminobutyric Acid Catabolism: Evidence for ?-Hydroxybutyric Acid and Polyhydroxybutyrate Synthesis in Saccharomyces cerevisiae?  

PubMed Central

The ?-aminobutyrate (GABA) shunt, an alternative route for the conversion of ?-ketoglutarate to succinate, involves the glutamate decarboxylase Gad1p, the GABA transaminase Uga1p and the succinate semialdehyde dehydrogenase Uga2p. This pathway has been extensively described in plants and animals, but its function in yeast remains unclear. We show that the flux through Gad1p is insignificant during fermentation in rich sugar-containing medium, excluding a role for this pathway in redox homeostasis under anaerobic conditions or sugar stress. However, we found that up to 4 g of exogenous GABA/liter was efficiently consumed by yeast. We studied the fate of this consumed GABA. Most was converted into succinate, with a reaction yield of 0.7 mol/mol. We also showed that a large proportion of GABA was stored within cells, indicating a possible role for this molecule in stress tolerance mechanisms or nitrogen storage. Furthermore, based on enzymatic and metabolic evidence, we identified an alternative route for GABA catabolism, involving the reduction of succinate-semialdehyde into ?-hydroxybutyric acid and the polymerization of ?-hydroxybutyric acid to form poly-(3-hydroxybutyric acid-co-4-hydroxybutyric acid). This study provides the first demonstration of a native route for the formation of this polymer in yeast. Our findings shed new light on the GABA pathway and open up new opportunities for industrial applications. PMID:19411412

Bach, Benoît; Meudec, Emmanuelle; Lepoutre, Jean-Paul; Rossignol, Tristan; Blondin, Bruno; Dequin, Sylvie; Camarasa, Carole



Modulation of GABA-A receptors of astrocytes and STC-1 cells by taurine structural analogs.  


Taurine activates and modulates GABA receptors in vivo as well as those expressed in heterologous systems. This study aimed to determine whether the structural analogs of taurine: homotaurine and hypotaurine, have the ability to activate GABA-A receptors that include GABA? subunits. The expression of GABA-A receptors containing GABA? has been reported in the STC-1 cells and astrocytes. In both cell types, taurine, homo-, and hypotaurine gated with low efficiency a picrotoxin-sensitive GABA-A receptor. The known bimodal modulatory effect of taurine on GABA? receptors was not observed; however, differences between the activation and deactivation rates were detected when they were perfused together with GABA. In silico docking simulations suggested that taurine, hypo-, and homotaurine do not form a cation-? interaction such as that generated by GABA in the agonist-binding site of GABA?. This observation complements the electrophysiological data suggesting that taurine and its analogs act as partial agonists of GABA-A receptors. All the observations above suggest that the structural analogs of taurine are partial agonists of GABA-A receptors that occupy the agonist-binding site, but their structures do not allow the proper interaction with the receptor to fully gate its Cl(-) channel. PMID:25119985

Reyes-Haro, Daniel; Cabrera-Ruíz, Elizabeth; Estrada-Mondragón, Argel; Miledi, Ricardo; Martínez-Torres, Ataúlfo



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

SciTech Connect

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

Kish, P.E.; Fischer-Bovenkerk, C.; Ueda, T. (Univ. of Michigan, Ann Arbor (USA))



Differential effects of GABAB receptor subtypes, {gamma}-hydroxybutyric Acid, and Baclofen on EEG activity and sleep regulation.  


The role of GABA(B) receptors in sleep is still poorly understood. GHB (?-hydroxybutyric acid) targets these receptors and is the only drug approved to treat the sleep disorder narcolepsy. GABA(B) receptors are obligate dimers comprised of the GABA(B2) subunit and either one of the two GABA(B1) subunit isoforms, GABA(B1a) and GABA(B1b). To better understand the role of GABA(B) receptors in sleep regulation, we performed electroencephalogram (EEG) recordings in mice devoid of functional GABA(B) receptors (1(-/-) and 2(-/-)) or lacking one of the subunit 1 isoforms (1a(-/-) and 1b(-/-)). The distribution of sleep over the day was profoundly altered in 1(-/-) and 2(-/-) mice, suggesting a role for GABA(B) receptors in the circadian organization of sleep. Several other sleep and EEG phenotypes pointed to a more prominent role for GABA(B1a) compared with the GABA(B1b) isoform. Moreover, we found that GABA(B1a) protects against the spontaneous seizure activity observed in 1(-/-) and 2(-/-) mice. We also evaluated the effects of the GHB-prodrug GBL (?-butyrolactone) and of baclofen (BAC), a high-affinity GABA(B) receptor agonist. Both drugs induced a state distinct from physiological sleep that was not observed in 1(-/-) and 2(-/-) mice. Subsequent sleep was not affected by GBL whereas BAC was followed by a delayed hypersomnia even in 1(-/-) and 2(-/-) mice. The differential effects of GBL and BAC might be attributed to differences in GABA(B)-receptor affinity. These results also indicate that all GBL effects are mediated through GABA(B) receptors, although these receptors do not seem to be involved in mediating the BAC-induced hypersomnia. PMID:20962240

Vienne, Julie; Bettler, Bernhard; Franken, Paul; Tafti, Mehdi



The Role of Genetic Sex in Affect Regulation and Expression of GABA-Related Genes Across Species  

PubMed Central

Although circulating hormones and inhibitory gamma-aminobutyric acid (GABA)-related factors are known to affect mood, considerable knowledge gaps persist for biological mechanisms underlying the female bias in mood disorders. Here, we combine human and mouse studies to investigate sexual dimorphism in the GABA system in the context of major depressive disorder (MDD) and then use a genetic model to dissect the role of sex-related factors in GABA-related gene expression and anxiety-/depressive-like behaviors in mice. First, using meta-analysis of gene array data in human postmortem brain (N?=?51 MDD subjects, 50 controls), we show that the previously reported down-regulation in MDD of somatostatin (SST), a marker of a GABA neuron subtype, is significantly greater in women with MDD. Second, using gene co-expression network analysis in control human subjects (N?=?214; two frontal cortex regions) and expression quantitative trait loci mapping (N?=?170 subjects), we show that expression of SST and the GABA-synthesizing enzymes glutamate decarboxylase 67 (GAD67) and GAD65 are tightly co-regulated and influenced by X-chromosome genetic polymorphisms. Third, using a rodent genetic model [Four Core Genotypes (FCG) mice], in which genetic and gonadal sex are artificially dissociated (N???12/group), we show that genetic sex (i.e., X/Y-chromosome) influences both gene expression (lower Sst, Gad67, Gad65 in XY mice) and anxiety-like behaviors (higher in XY mice). This suggests that in an intact male animal, the observed behavior represents the outcomes of male genetic sex increasing and male-like testosterone decreasing anxiety-like behaviors. Gonadal sex was the only factor influencing depressive-like behavior (gonadal males?GABA-related genes and anxiety-like behaviors. PMID:24062698

Seney, Marianne L.; Chang, Lun-Ching; Oh, Hyunjung; Wang, Xingbin; Tseng, George C.; Lewis, David A.; Sibille, Etienne



Activation of the cannabinoid receptor by ? 9-tetrahydrocannabinol reduces ?-aminobutyric acid uptake in the globus pallidus  

Microsoft Academic Search

The interaction between GABA (?-aminobutyric acid) and cannabinoids in the globus pallidus was investigated by evaluating the effects of ?9-tetrahydrocannabinol on [3H]GABA uptake into slices of rat globus pallidus. ?9-Tetrahydrocannabinol caused a concentration-dependent decrease in GABA uptake (51% decrease at 100 ?M ?9-tetrahydrocannabinol, IC50 = 18.95 ?M). This effect was reversed in a concentration-dependent manner (IC50 = 11.9 ?M) by

Yannick P. Maneuf; Joanne E. Nash; Alan R. Crossman; Jonathan M. Brotchie



Brain gamma-aminobutyric acid receptor binding is normal in rats with thioacetamide-induced hepatic encephalopathy despite elevated plasma gamma-aminobutyric acid-like activity.  


Brain gamma-aminobutyric acid (GABA) receptor density, affinity, and function, and plasma GABA-like activity were determined in rats with acute hepatic encephalopathy induced by an intraperitoneal injection of thioacetamide. In addition, the effect of various stress factors on brain GABA binding was assessed. Plasma GABA-like activity was significantly increased in rats with thioacetamide-induced hepatic encephalopathy compared with rats injected with vehicle alone (1506 +/- 993 nM, n = 7 vs. 367 +/- 97 nM, n = 9, mean +/- SD; p less than 0.001). In contrast, there were no alterations in either brain GABA receptor binding or in GABA-enhanced benzodiazepine binding in rats with hepatic encephalopathy when compared with relevant controls. However, rats that had received intraperitoneal injections of thioacetamide or vehicle (0.15 M NaCl) had significantly more low-affinity GABA receptors than rats that had neither been injected nor handled before killing (8769 +/- 1101 vs. 2710 +/- 757 fmol/mg protein, mean +/- SEM, p less than 0.001). We concluded that stress factors appear to be important causes of altered brain GABA binding. Brain GABA receptor binding and function, however, are unaltered in rats with thioacetamide-induced hepatic encephalopathy despite elevated plasma GABA-like activity. PMID:2820827

Maddison, J E; Dodd, P R; Johnston, G A; Farrell, G C



GABA neurons provide a rich input to microvessels but not nitric oxide neurons in the rat cerebral cortex: a means for direct regulation of local cerebral blood flow.  


Basal forebrain neurons project to microvessels and the somata of nitric oxide (NO) synthase-containing neurons in the cerebral cortex, and their stimulation results in increases in cortical perfusion. gamma-Aminobutyric acid (GABA) is the second major neurotransmitter synthesized by these neurons and it has also been reported to modify cerebromicrovascular tone. We thus investigated by light and electron microscopy the association of GABA neurons (labeled for glutamic acid decarboxylase [GAD]) with cortical microvessels and/or NO neurons (identified by nicotinamide adenine dinucleotide [NADPH-D] histochemistry) within the frontoparietal and perirhinal cerebral cortex in the rat. On thick and semithin sections, a high density of GAD puncta was observed, several surrounded intracortical blood vessels and neuronal perikarya. In contrast, NADPH-D cell somata and proximal dendrites were only occasionally contacted by GAD nerve terminals. Perivascular and perisomatic GAD appositions were identified at the ultrastructural level as large (0.44-0.50 microm(2)) neuronal varicosities located in the immediate vicinity of, or being directly apposed to, vessels or unstained neuronal cell bodies. In both cortical areas, perivascular GAD terminals were located at about 1 microm from the vessels and were seen to frequently establish junctional contacts (synaptic frequency of 25-40% in single thin sections) with adjacent neuronal but not vascular elements. Ibotenic or quisqualic acid lesion of the substantia innominata did not significantly affect the density of cortical and perivascular GAD terminals, suggesting that they mostly originated locally in the cortex. These results suggest that GABA terminals can interact directly with the microvascular bed and that the somata and proximal dendrites of NO neurons are not a major target for cortical GABA neurotransmission. However, based on the colocalization of GABA and NADPH-D in a subset of cortical neurons, we suggest that these interneurons could be implicated in the cortical vascular response elicited by stimulation of basal forebrain neurons. PMID:10813779

Vaucher, E; Tong, X K; Cholet, N; Lantin, S; Hamel, E



Intracellular studies of GABA and taurine action on the neurons of the cat sensorimotor cortex.  


The action of taurine and GABA on the cat cerebral cortex neurons was studied. Electrophoretically administered taurine and GABA hyperpolarized the neuron membrane. GABA, in contrast to taurine, sharply increased the somatic membrane conductance. Taurine action was weaker than that of GABA and its effects were not always observed. However, in a number of instances it exerted inhibitory influence similar to GABA action. Some facts make it possible to suppose that taurine acts mainly on the neuron dendrites. The data obtained are in accordance with the supposition that taurine might be an inhibitory transmitter in the cerebral cortex. PMID:423315

Alexandrov, A A; Batuev, A S



Curcumol from Rhizoma Curcumae suppresses epileptic seizure by facilitation of GABA(A) receptors.  


Rhizoma Curcumae is a common Chinese dietary spice used in South Asia and China for thousands of years. As the main extract, Rhizoma Curcumae oil has attracted a great interest due to its newly raised therapeutic activities including its pharmacological effects upon central nervous system such as neuroprotection, cognitive enhancement, and anti-seizure efficacy; however the molecular mechanisms and the target identification remain to be established. Here we characterize an inhibitory effect of curcumol, a major bioactive component of Rhizoma Curcumae oil, on the excitability of hippocampal neurons in culture, the basal locomotor activity of freely moving animals, and the chemically induced seizure activity in vivo. Electrophysiological recording showed that acute application of curcumol significantly facilitated the ?-aminobutyric acid (GABA)-activated current in cultured mouse hippocampal neurons and in human embryonic kidney cells expressing ?1- or ?5-containing A type GABA (GABAA) receptors in a concentration-dependent manner. Measurement of tonic and miniature inhibitory postsynaptic GABAergic currents in hippocampal slices indicated that curcumol enhanced both forms of inhibition. In both pentylenetetrazole and kainate seizure models, curcumol suppressed epileptic activity in mice by prolonging the latency to clonic and tonic seizures and reducing the mortality as well as the susceptibility to seizure, presumably by facilitating the activation of GABAA receptors. Taken together, our results identified curcumol as a novel anti-seizure agent which inhibited neuronal excitability through enhancing GABAergic inhibition. PMID:24565642

Ding, Jing; Wang, Jing-Jing; Huang, Chen; Wang, Li; Deng, Shining; Xu, Tian-Le; Ge, Wei-Hong; Li, Wei-Guang; Li, Fei



Neurofibromin regulation of ERK signaling modulates GABA release and learning  

PubMed Central

Summary We uncovered a new role for ERK signaling in GABA release, long-term potentiation (LTP) and learning, and show that disruption of this mechanism accounts for the learning deficits in a mouse model for Neurofibromatosis type I (NF1), a common genetic cause for learning disabilities. Genetic, pharmacological, electrophysiological and behavioral data demonstrate that neurofibromin modulates ERK/synapsin I dependent GABA release, which in turn modulate hippocampal LTP and learning. An Nf1 heterozygous null mutation, which results in enhanced ERK and synapsin I phosphorylation, increased pre-synaptic GABA release in the hippocampus which was reversed by pharmacologically down-regulating ERK signaling. Importantly, the learning deficits associated with the Nf1 mutation were rescued by a sub-threshold dose of a GABAA antagonist. Accordingly, Cre-deletions of the Nf1 gene showed that only those deletions involving inhibitory neurons caused hippocampal inhibition, LTP and learning abnormalities. Importantly, our results also revealed lasting increases in GABA release triggered by learning, indicating that the mechanisms uncovered here are of general importance for learning and memory. PMID:18984165

Cui, Yijun; Costa, Rui M; Murphy, Geoffrey G; Elgersma, Ype; Zhu, Yuan; Gutmann, David H.; Parada, Luis F.; Mody, Istvan; Silva, Alcino J



Zolpidem increases GABA in depressed volunteers maintained on SSRIs.  


Individuals with major depressive disorder (MDD) often use hypnotics like zolpidem (Ambien(®)) to improve sleep in addition to their selective serotonin reuptake inhibitor (SSRI) regimen. SSRIs act in part to restore disrupted GABAergic activity, but benzodiazepines and related drugs have been shown to lower GABA in a way that may be counter to these therapeutic effects. The present within-subject, single-blind, placebo-controlled study measured changes in GABA in the anterior cingulate (ACC) and thalamus of volunteers maintained on SSRIs for the treatment of MDD (n=14) following zolpidem (10mg) administration. In addition to neurochemical measurements obtained using proton magnetic resonance spectroscopy ((1)H MRS) at 4 T, a series of questionnaires were administered to assess subjective effects associated with acute zolpidem exposure. Zolpidem elevated GABA levels in both voxels of interest (P<0.05) in the depressed participants, which could imply normalization, given the lower baseline levels associated with depression. The subjective drug experience in the depressed cohort was similar to that reported previously by healthy volunteers, and no relationships existed between GABA increases and the observed behavioral effects. Aside from treating insomnia, using zolpidem in the presence of SSRIs may have some unidentified therapeutic effects for depressed individuals. PMID:25082715

Licata, Stephanie C; Jensen, J Eric; Conn, Nina A; Winer, Jeffrey P; Lukas, Scott E



GABA and glycine immunolabeling in the chicken tangential nucleus  

Microsoft Academic Search

In the vestibular nuclei, GABAergic and glycinergic neurons play important roles in signal processing for normal function, during development, and after peripheral vestibular lesions. The chicken tangential nucleus is a major avian vestibular nucleus, whose principal cells are projection neurons with axons transmitting signals to the oculomotor nuclei and\\/or cervical spinal cord. Antibodies against GABA, glycine and glutamate were applied

A. Popratiloff; K. D. Peusner



Ischaemia differentially regulates GABA(B) receptor subunits in organotypic hippocampal slice cultures.  


Reduced synaptic inhibition due to dysfunction of ionotropic GABA(A) receptors has been proposed as one factor in cerebral ischaemia-induced excitotoxic cell death. However, the participation of the inhibitory metabotropic GABA(B) receptors in these pathological processes has not been extensively investigated. We used oxygen-glucose deprivation (OGD) and NMDA-induced excitotoxicity as models to investigate whether ischaemia-like challenges alter the protein levels of GABA(B1) and GABA(B2) receptor subunits in rat organotypic hippocampal slice cultures. Twenty-four hours after the insult both OGD and NMDA produced a marked decrease in the total levels of GABA(B2) (approximately 75%), while there was no significant change in the levels of GABA(B1) after OGD, but an increase after NMDA treatment (approximately 100%). The GABA(B) receptor agonist baclofen (100 microM) was neuroprotective following OGD or NMDA treatment if added before or during the insult. GABA(B) receptors comprise heterodimers of GABA(B1) and GABA(B2) subunits and our results suggest that the separate subunits are independently regulated in response to extreme neuronal stress. However, because GABA(B2) is required for functional surface expression, down-regulation of this subunit removes an important inhibitory feedback mechanism under pathological conditions. PMID:19328818

Cimarosti, Helena; Kantamneni, Sriharsha; Henley, Jeremy M



Functioning of the dimeric GABA(B) receptor extracellular domain revealed by glycan wedge scanning.  


The G-protein-coupled receptor (GPCR) activated by the neurotransmitter GABA is made up of two subunits, GABA(B1) and GABA(B2). GABA(B1) binds agonists, whereas GABA(B2) is required for trafficking GABA(B1) to the cell surface, increasing agonist affinity to GABA(B1), and activating associated G proteins. These subunits each comprise two domains, a Venus flytrap domain (VFT) and a heptahelical transmembrane domain (7TM). How agonist binding to the GABA(B1) VFT leads to GABA(B2) 7TM activation remains unknown. Here, we used a glycan wedge scanning approach to investigate how the GABA(B) VFT dimer controls receptor activity. We first identified the dimerization interface using a bioinformatics approach and then showed that introducing an N-glycan at this interface prevents the association of the two subunits and abolishes all activities of GABA(B2), including agonist activation of the G protein. We also identified a second region in the VFT where insertion of an N-glycan does not prevent dimerization, but blocks agonist activation of the receptor. These data provide new insight into the function of this prototypical GPCR and demonstrate that a change in the dimerization interface is required for receptor activation. PMID:18388862

Rondard, Philippe; Huang, Siluo; Monnier, Carine; Tu, Haijun; Blanchard, Bertrand; Oueslati, Nadia; Malhaire, Fanny; Li, Ying; Trinquet, Eric; Labesse, Gilles; Pin, Jean-Philippe; Liu, Jianfeng



Effects of components in culture medium on glutamate decarboxylase activity and ?-aminobutyric acid accumulation in foxtail millet ( Setaria italica L.) during germination  

Microsoft Academic Search

The effects of glutamic acid (Glu), pyridoxal-5-phosphate (PLP) and calcium chloride (CaCl2) in culture medium on glutamate decarboxylase (GAD) activity and ?-aminobutyric acid (GABA) accumulation in foxtail millet (Setaria italica L.) during germination were investigated in this study. The components in culture medium for GABA accumulation were optimised using response surface methodology (RSM). Results showed that GAD activity and GABA

Qingyun Bai; Meiqing Chai; Zhenxin Gu; Xiaohong Cao; Yan Li; Kunlun Liu



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


In Alzheimer's disease (AD), memory impairment is the most prominent feature that afflicts patients and their families. Although reactive astrocytes have been observed around amyloid plaques since the disease was first described, their role in memory impairment has been poorly understood. Here, we show that reactive astrocytes aberrantly and abundantly produce the inhibitory gliotransmitter GABA by monoamine oxidase-B (Maob) and abnormally release GABA through the bestrophin 1 channel. In the dentate gyrus of mouse models of AD, the released GABA reduces spike probability of granule cells by acting on presynaptic GABA receptors. Suppressing GABA production or release from reactive astrocytes fully restores the impaired spike probability, synaptic plasticity, and learning and memory in the mice. In the postmortem brain of individuals with AD, astrocytic GABA and MAOB are significantly upregulated. We propose that selective inhibition of astrocytic GABA synthesis or release may serve as an effective therapeutic strategy for treating memory impairment in AD. PMID:24973918

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



Caenorhabditis elegans neuromuscular junction: GABA receptors and ivermectin action.  


The prevalence of human and animal helminth infections remains staggeringly high, thus urging the need for concerted efforts towards this area of research. GABA receptors, encoded by the unc-49 gene, mediate body muscle inhibition in Caenorhabditis elegans and parasitic nematodes and are targets of anthelmintic drugs. Thus, the characterization of nematode GABA receptors provides a foundation for rational anti-parasitic drug design. We therefore explored UNC-49 channels from C. elegans muscle cultured cells of the first larval stage at the electrophysiological and behavioral levels. Whole-cell recordings reveal that GABA, muscimol and the anthelmintic piperazine elicit macroscopic currents from UNC-49 receptors that decay in their sustained presence, indicating full desensitization. Single-channel recordings show that all drugs elicit openings of ?2.5 pA (+100 mV), which appear either as brief isolated events or in short bursts. The comparison of the lowest concentration required for detectable channel opening, the frequency of openings and the amplitude of macroscopic currents suggest that piperazine is the least efficacious of the three drugs. Macroscopic and single-channel GABA-activated currents are profoundly and apparently irreversibly inhibited by ivermectin. To gain further insight into ivermectin action at C. elegans muscle, we analyzed its effect on single-channel activity of the levamisol-sensitive nicotinic receptor (L-AChR), the excitatory receptor involved in neuromuscular transmission. Ivermectin produces a profound inhibition of the frequency of channel opening without significant changes in channel properties. By revealing that ivermectin inhibits C. elegans muscle GABA and L-AChR receptors, our study adds two receptors to the already known ivermectin targets, thus contributing to the elucidation of its pleiotropic effects. Behavioral assays in worms show that ivermectin potentiates piperazine-induced paralysis, thus suggesting that their combination is a good strategy to overcome the increasing resistance of parasites, an issue of global concern for human and animal health. PMID:24743647

Hernando, Guillermina; Bouzat, Cecilia



Cell-attached recordings of responses evoked by photorelease of GABA in the immature cortical neurons.  


We present a novel non-invasive technique to measure the polarity of GABAergic responses based on cell-attached recordings of currents activated by laser-uncaging of GABA. For these recordings, a patch pipette was filled with a solution containing RuBi-GABA, and GABA was released from this complex by a laser beam conducted to the tip of the patch pipette via an optic fiber. In cell-attached recordings from neocortical and hippocampal neurons in postnatal days P2-5 rat brain slices in vitro, we found that laser-uncaging of GABA activates integral cell-attached currents mediated by tens of GABA(A) channels. The initial response was inwardly directed, indicating a depolarizing response to GABA. The direction of the initial response was dependent on the pipette potential and analysis of its slope-voltage relationships revealed a depolarizing driving force of +11 mV for the currents through GABA channels. Initial depolarizing responses to GABA uncaging were inverted to hyperpolarizing in the presence of the NKCC1 blocker bumetanide. Current-voltage relationships of the currents evoked by RuBi-GABA uncaging using voltage-ramps at the peak of responses not only revealed a bumetanide-sensitive depolarizing reversal potential of the GABA(A) receptor mediated responses, but also showed a strong voltage-dependent hysteresis. Upon desensitization of the uncaged-GABA response, current-voltage relationships of the currents through single GABA(A) channels revealed depolarizing responses with the driving force values similar to those obtained for the initial response. Thus, cell-attached recordings of the responses evoked by local intrapipette GABA uncaging are suitable to assess the polarity of the GABA(A)-Rs mediated signals in small cell compartments. PMID:23754981

Minlebaev, Marat; Valeeva, Guzel; Tcheremiskine, Vadim; Coustillier, Gaëlle; Khazipov, Rustem



Cell-attached recordings of responses evoked by photorelease of GABA in the immature cortical neurons  

PubMed Central

We present a novel non-invasive technique to measure the polarity of GABAergic responses based on cell-attached recordings of currents activated by laser-uncaging of GABA. For these recordings, a patch pipette was filled with a solution containing RuBi-GABA, and GABA was released from this complex by a laser beam conducted to the tip of the patch pipette via an optic fiber. In cell-attached recordings from neocortical and hippocampal neurons in postnatal days P2-5 rat brain slices in vitro, we found that laser-uncaging of GABA activates integral cell-attached currents mediated by tens of GABA(A) channels. The initial response was inwardly directed, indicating a depolarizing response to GABA. The direction of the initial response was dependent on the pipette potential and analysis of its slope-voltage relationships revealed a depolarizing driving force of +11 mV for the currents through GABA channels. Initial depolarizing responses to GABA uncaging were inverted to hyperpolarizing in the presence of the NKCC1 blocker bumetanide. Current-voltage relationships of the currents evoked by RuBi-GABA uncaging using voltage-ramps at the peak of responses not only revealed a bumetanide-sensitive depolarizing reversal potential of the GABA(A) receptor mediated responses, but also showed a strong voltage-dependent hysteresis. Upon desensitization of the uncaged-GABA response, current-voltage relationships of the currents through single GABA(A) channels revealed depolarizing responses with the driving force values similar to those obtained for the initial response. Thus, cell-attached recordings of the responses evoked by local intrapipette GABA uncaging are suitable to assess the polarity of the GABA(A)-Rs mediated signals in small cell compartments. PMID:23754981

Minlebaev, Marat; Valeeva, Guzel; Tcheremiskine, Vadim; Coustillier, Gaëlle; Khazipov, Rustem



Plasticity of GABA transporters: an unconventional route to shape inhibitory synaptic transmission  

PubMed Central

The brain relies on GABAergic neurons to control the ongoing activity of neuronal networks. GABAergic neurons control the firing pattern of excitatory cells, the temporal structure of membrane potential oscillations and the time window for integration of synaptic inputs. These actions require a fine control of the timing of GABA receptor activation which, in turn, depends on the precise timing of GABA release from pre-synaptic terminals and GABA clearance from the extracellular space. Extracellular GABA is not subject to enzymatic breakdown, and its clearance relies entirely on diffusion and uptake by specific transporters. In contrast to glutamate transporters, GABA transporters are abundantly expressed in neuronal pre-synaptic terminals. GABA transporters move laterally within the plasma membrane and are continuously trafficked to/from intracellular compartments. It is hypothesized that due to their proximity to GABA release sites, changes in the concentration and lateral mobility of GABA transporters may have a significant effect on the time course of the GABA concentration profile in and out of the synaptic cleft. To date, this hypothesis remains to be tested. Here we use 3D Monte Carlo reaction-diffusion simulations to analyze how changes in the density of expression and lateral mobility of GABA transporters in the cell membrane affect the extracellular GABA concentration profile and the activation of GABA receptors. Our results indicate that these manipulations mainly alter the GABA concentration profile away from the synaptic cleft. These findings provide novel insights into how the ability of GABA transporters to undergo plastic changes may alter the strength of GABAergic signals and the activity of neuronal networks in the brain. PMID:24860430

Scimemi, Annalisa



Ketamine reverses stress-induced depression-like behavior and increased GABA levels in the anterior cingulate: an 11.7 T 1H-MRS study in rats.  


Gamma-aminobutyric acid (GABA) is the major inhibitory amino acid neurotransmitter in the brain and is primarily responsible for modulating excitatory tone. Clinical neuroimaging studies show decreased GABA levels in the anterior cingulate of patients with mood disorders, including major depressive disorder. Chronic unpredictable stress (CUS) is an animal model thought to mimic the stressful events that may precipitate clinical depression in humans. In this study male Sprague-Dawley rats were subjected to a modified CUS paradigm that used a random pattern of unpredictable stressors twice daily for 10 days to explore the early developmental stages of depression-like endophenotypes. Control rats were handled daily for 10 days. Some rats from each treatment group received an injection of ketamine (40 mg/kg) after the final stressor. One day following the final stressor rats were tested for behavioral effects in the forced swim test and then euthanized to collect trunk blood and anterior cingulate brain samples. GABA levels were measured in anterior cingulate samples ex vivo using proton magnetic resonance spectroscopy ((1)H-MRS) at 11.7 T. Animals subjected to CUS had lower body weights, higher levels of blood corticosterone, and increased immobility in the forced swim test; all of which suggest that the stress paradigm induced a depression-like phenotype. GABA levels in the anterior cingulate were significantly increased in the stressed animals compared to controls. Administration of ketamine on the last day of treatment blunted the depression-like behavior and increased GABA levels in the anterior cingulate following CUS. These data indicate that stress disrupts GABAergic signaling, which may over time lead to symptoms of depression and ultimately lower basal levels of cortical (1)H-MRS GABA that are seen in humans with depression. Furthermore, the data suggests that ketamine modulates cortical GABA levels as a mechanism of its antidepressant activity. PMID:24246571

Perrine, Shane A; Ghoddoussi, Farhad; Michaels, Mark S; Sheikh, Imran S; McKelvey, George; Galloway, Matthew P



Metabolite profiling of Arabidopsis inoculated with Alternaria brassicicola reveals that ascorbate reduces disease severity.  


The interaction between the pathogenic ascomycete Alternaria brassicicola and Arabidopsis was investigated by metabolite profiling. The effect of A. brassicicola challenge on metabolite levels was substantial, with nearly 50% of detected compounds undergoing significant changes. Mutations blocking ethylene, jasmonic acid, or ethylene signaling had little effect on metabolite levels. The effects of altering levels of some metabolites were tested by exogenous application during A. brassicicola inoculation. Gamma amino-butyric acid (GABA) or xylitol promoted, while trehalose and ascorbate inhibited, disease severity. GABA promoted, and ascorbate strongly inhibited, fungal growth in culture. Arabidopsis vtc1 and vtc2 mutants, that have low levels of ascorbate, were more susceptible to A. brassicicola. Ascorbate levels declined following A. brassicicola inoculation while levels of dehydroascorbate increased, resulting in a shift of the redox balance between these compounds in the direction of oxidation. These results demonstrate that ascorbate is an important component of resistance to this pathogen. PMID:23134520

Botanga, Christopher J; Bethke, Gerit; Chen, Zhong; Gallie, Daniel R; Fiehn, Oliver; Glazebrook, Jane



Local inhibition of GABA affects precedence effect in the inferior colliculus  

PubMed Central

The precedence effect is a prerequisite for faithful sound localization in a complex auditory environment, and is a physiological phenomenon in which the auditory system selectively suppresses the directional information from echoes. Here we investigated how neurons in the inferior colliculus respond to the paired sounds that produce precedence-effect illusions, and whether their firing behavior can be modulated through inhibition with gamma-aminobutyric acid (GABA). We recorded extracellularly from 36 neurons in rat inferior colliculus under three conditions: no injection, injection with saline, and injection with gamma-aminobutyric acid. The paired sounds that produced precedence effects were two identical 4-ms noise bursts, which were delivered contralaterally or ipsilaterally to the recording site. The normalized neural responses were measured as a function of different inter-stimulus delays and half-maximal interstimulus delays were acquired. Neuronal responses to the lagging sounds were weak when the inter-stimulus delay was short, but increased gradually as the delay was lengthened. Saline injection produced no changes in neural responses, but after local gamma-aminobutyric acid application, responses to the lagging stimulus were suppressed. Application of gamma-aminobutyric acid affected the normalized response to lagging sounds, independently of whether they or the paired sounds were contralateral or ipsilateral to the recording site. These observations suggest that local inhibition by gamma-aminobutyric acid in the rat inferior colliculus shapes the neural responses to lagging sounds, and modulates the precedence effect. PMID:25206830

Wang, Yanjun; Wang, Ningyu; Wang, Dan; Jia, Jun; Liu, Jinfeng; Xie, Yan; Wen, Xiaohui; Li, Xiaoting



Supraspinal modulation of pain by cannabinoids: the role of GABA and glutamate  

PubMed Central

Recent physiological, pharmacological and anatomical studies provide evidence that one of the main roles of the endocannabinoid system in the brain is the regulation of ?-aminobutyric acid (GABA) and glutamate release. This article aims to review this evidence in the context of its implications for pain. We first provide a brief overview of supraspinal regulation of nociception, followed by a review of the evidence that the brain's endocannabinoid system modulates nociception. We look in detail at regulation of supraspinal GABAergic and glutamatergic neurons by the endocannabinoid system and by exogenously administered cannabinoids. Finally, we review the evidence that cannabinoid-mediated modulation of pain involves modulation of GABAergic and glutamatergic neurotransmission in key brain regions. PMID:17828292

Rea, K; Roche, M; Finn, D P



[Gamma aminobutyric acid--its function, disorders and their sequelae].  


Gama-Aminobutyric acid (GABA) is an important neurotransmitter that mediates inhibition in the central nervous system. Approximately 30-50% of all synapses are defined as GABA-ergic. GABA is a neurotransmitter in cortical and hippocampal interneurones. GABA-RECEPTORS: Till today, three receptor subtypes have been known: GABAA, GABAB and GABAC, which are pharmacologically different. GABAA receptor is postsynaptic and localized in central and peripheral sympathetic neurones. Its agonist is muscimol and is antagonized by bicucculline. GABAB is a presynaptic receptor of vegetative and central nerve terminals. Its agonist is baclofen. The main difference between these two subtypes is that the first one acts directly on Cl ionphore, while GABAB activity is mediated by Gi protein. GABAC receptors are the integral part of the membrane, which stabilise the resting potential of the cell by increasing conductivity for Cl. Their most effective agonist is TACA. GABA ACTIVITY ON SYNAPSES: GABA is the most powerful inhibitory neurotransmitter in CNS. Synaptic inhibition decreases cell's ability to communicate with other cells and it is realised by various inhibitory mechanism of GABA, such as preventing of stimuluss generation, dendritic inhibition and dendro-dendritic inhibition. GABA AND NEUROENDOCRINE REGULATION: Besides physiological significance in maintaining regular excitation and inhibition balance. GABA plays an important role in neuroendocrine regulation of the following hormones: LH, FSH, PRL, STH, SS, ACTH, TSH, TRH, MSH, VP and OX. GABA IN NEUROLOGICAL DISEASES: Increasing or decreasing of GABA-ergic tone, due to different reasons, may lead to numerous neurodegenerative disorders (epilepsy, hepatic encephalopathy, Huntington's chorea, spinocerebellar degeneration, dementia and psychosis). PMID:9769665

De Luka, S R; Proti?, S; Vrbaski, S R



Short External Loops as Potential Substrate Binding Site of -Aminobutyric Acid Transporters*  

E-print Network

GABA uptake activity. These three amino acids in loop V seem to participate in the -alanine binding do of GABA neurotransmission is achieved by a rapid sodium-dependent uptake system (3). Molecular cloning of Mutants--Oligonucleotide-directed site-specific mu- tagenesis was performed by overlap extension using

Nelson, Nathan


A validated method for gas chromatographic analysis of gamma-aminobutyric acid in tall fescue herbage  

Technology Transfer Automated Retrieval System (TEKTRAN)

Gamma-Aminobutyric acid (GABA) is an inhibitory neurotransmitter in animals that is also found in plants and has been associated with plant responses to stress. A simple and relatively rapid method of GABA separation and quantification was developed from a commercially available kit for serum amino...


Implications of paraquat and hydrogen peroxide-induced oxidative stress treatments on the GABA shunt pathway in Arabidopsis thaliana calmodulin mutants  

Microsoft Academic Search

Arabidopsis mutants with T-DNA insertion in seven calmodulin genes (CAM) were used to determine the specific role of CAM in the tolerance of plants to oxidative stress induced by paraquat and hydrogen\\u000a peroxide (H2O2) treatments. Arabidopsis calmodulin mutants (cam) were screened for seedling growth, seed germination, induced oxidative damage, and levels of ?-aminobutyric acid (GABA)\\u000a shunt metabolites. Only the cam5-4

Nisreen A. AL-QuraanRobert; Robert D. Locy; Narendra K. Singh



GABA Not Only a Neurotransmitter: Osmotic Regulation by GABAAR Signaling  

PubMed Central

Mature macroglia and almost all neural progenitor types express ?-aminobutyric (GABA) A receptors (GABAARs), whose activation by ambient or synaptic GABA, leads to influx or efflux of chloride (Cl?) depending on its electro-chemical gradient (ECl). Since the flux of Cl? is indissolubly associated to that of osmotically obliged water, GABAARs regulate water movements by modulating ion gradients. In addition, since water movements also occur through specialized water channels and transporters, GABAAR signaling could affect the movement of water by regulating the function of the channels and transporters involved, thereby affecting not only the direction of the water fluxes but also their dynamics. We will here review recent observations indicating that in neural cells GABAAR-mediated osmotic regulation affects the cellular volume thereby activating multiple intracellular signaling mechanisms important for cell proliferation, maturation, and survival. In addition, we will discuss evidence that the osmotic regulation exerted by GABA may contribute to brain water homeostasis in physiological and in pathological conditions causing brain edema, in which the GABAergic transmission is often altered. PMID:22319472

Cesetti, Tiziana; Ciccolini, Francesca; Li, Yuting



Early depolarizing GABA controls critical-period plasticity in the rat visual cortex.  


Hyperpolarizing and inhibitory GABA regulates critical periods for plasticity in sensory cortices. Here we examine the role of early, depolarizing GABA in the control of plasticity mechanisms. We report that brief interference with depolarizing GABA during early development prolonged critical-period plasticity in visual cortical circuits without affecting the overall development of the visual system. The effects on plasticity were accompanied by dampened inhibitory neurotransmission, downregulation of brain-derived neurotrophic factor (BDNF) expression and reduced density of extracellular matrix perineuronal nets. Early interference with depolarizing GABA decreased perinatal BDNF signaling, and a pharmacological increase of BDNF signaling during GABA interference rescued the effects on plasticity and its regulators later in life. We conclude that depolarizing GABA exerts a long-lasting, selective modulation of plasticity of cortical circuits by a strong crosstalk with BDNF. PMID:25485756

Deidda, Gabriele; Allegra, Manuela; Cerri, Chiara; Naskar, Shovan; Bony, Guillaume; Zunino, Giulia; Bozzi, Yuri; Caleo, Matteo; Cancedda, Laura



GABA-to-ACh Ratio in Basal Forebrain and Cerebral Cortex Varies Significantly During Sleep  

PubMed Central

Study Objectives: GABAergic and cholinergic transmission within the basal forebrain and cerebral cortex contribute to the regulation of sleep and wakefulness. In contrast to levels of acetylcholine (ACh), levels of endogenous GABA in basal forebrain and cortex during sleep and wakefulness have not previously been quantified. This study (1) tested the hypothesis that there are differential, state-specific changes in GABA levels within the substantia innominata (SI) region of the basal forebrain and somatosensory cortex; and (2) quantified the ratio of GABAergic to cholinergic transmission in the SI, cortex, and pontine reticular formation during rapid eye movement sleep (REM), non-REM sleep (NREM), and wakefulness. Design: Within/between subjects. Setting: University of Michigan. Patients or Participants: Adult, male, purpose bred cats (n = 5). Interventions: In vivo microdialysis, high performance liquid chromatography, electrophysiological recordings. Measurements and Results: In the SI, GABA levels were significantly greater during NREM (17%) than during REM. In the cortex, GABA levels were significantly greater during NREM than during wakefulness (39%) and REM (63%). During prolonged wakefulness, there was a linear increase in cortical GABA levels, and the amount of time spent awake accounted for 87% of the variance in GABA. The GABA-to-ACh ratio was largest during NREM for all brain regions. REM was characterized by a 68% decrease in the GABA-to-ACh ratio across brain regions, always due to a decrease in GABA levels. Conclusion: Three of the brain regions that comprise the anatomically distributed, sleep-generating network have in common a GABA-mediated, sleep-dependent decrease in the GABA-to-ACh ratio. Citation: Vanini G; Lydic R; Baghdoyan HA. GABA-to-ACh ratio in basal forebrain and cerebral cortex varies significantly during sleep. SLEEP 2012;35(10):1325-1334. PMID:23024430

Vanini, Giancarlo; Lydic, Ralph; Baghdoyan, Helen A.



Multiple mechanisms of picrotoxin block of GABA-induced currents in rat hippocampal neurons.  

PubMed Central

1. We have examined the effect of picrotoxin on GABA-induced currents in dissociated rat hippocampal neurons. In addition, we used the putative picrotoxin receptor antagonist, alpha-isopropyl-alpha-methyl-gamma-butyrolactone (alpha IMGBL), and the picrotoxin agonist, beta-ethyl-beta-methyl-gamma-butyrolactone (beta EMGBL) to explore the mechanisms of picrotoxin's interaction with the GABA-Cl- receptor-ionophore complex. 2. The picrotoxin block of GABA current was use dependent, suggesting that the site of picrotoxin block is exposed by the conformational change initiated by GABA binding to the receptor. 3. The alkyl-substituted butyrolactone antagonist, alpha IMGBL, selectively blocked the use-dependent mechanism of picrotoxin effect. After the apparent complete inhibition of the use-dependent effect, there was a residual picrotoxin effect that was independent of the time or concentration of GABA application. This indicates that the picrotoxin block of the GABA current is mediated by two different mechanisms. alpha IMGBL influences just one of these mechanisms. 4. The picrotoxin receptor agonist, beta EMGBL, exclusively blocked the GABA current in a use-dependent manner. Consistent with a use-dependent mechanism, the rate of onset of block increased with GABA concentration. Surprisingly, the fraction of GABA current block decreased with increasing GABA concentration. 5. These results suggest that the relationship of picrotoxin and gamma-butyrolactones with the GABA-Cl- receptor-ionophore is quite complex. They are consistent with at least two possible models of agonist-antagonist interactions. Both cases require different antagonist affinities for the various kinetic states of the GABA-Cl- receptor-ionophore. However, there is no need to require that either picrotoxin or beta EMGBL acts as an open channel blocker. PMID:8229811

Yoon, K W; Covey, D F; Rothman, S M



[Inhibition of mouse-killing behavior by rats with taurine, GABA, and its analogues].  


The injection of Gaba, of taurine or of a structural analog of GABA (n-dipropylacetate) in the olfactive bulb of "killer" Rats was found to inhibit the mouse-killing behaviour of the rat. The same effect was obtained when taurine or n-dipropylacetate (which increases GABA in the central nervous system), was injected intraperitoneally. The experiments reported here are interpreted to explain certain molecular mechanisms of muricidal behaviour. PMID:825280

Mack, G; Mandel, P



Evidence for down-regulation of GABA receptors following long-term gamma-butyrolactone  

Microsoft Academic Search

Long-term oral administration (12 weeks) of ?-butyrolactone (GBL) to mice resulted in pharmacological and neurochemical changes which may be interpreted as a decrease in GABA-mediated synaptic activity. The depression in motor activity produced by the GABA-mimetic muscimol was reduced following long-term GBL. The binding of GABA to its putative receptor was reduced in the GBL group as evidenced by a

G. Gianutsos; P. D. Suzdak



Hyperpolarizing Inhibition Develops without Trophic support by GABA in Cultured Rat Midbrain Neurons  

PubMed Central

During a limited period of early neuronal development, GABA is depolarizing and elevates [Ca2+]i, which mediates the trophic action of GABA in neuronal maturation. We tested the attractive hypothesis that GABA itself promotes the developmental change of its response from depolarizing to hyperpolarizing (Ganguly et al. 2001). In cultured midbrain neurons we found that the GABA response changed from depolarizing to hyperpolarizing, although GABAA receptors had been blocked throughout development. In immature neurons prolonged exposure of the cells to nanomolar concentrations of GABA or brief repetitive applications of GABA strongly diminished the elevation of [Ca2+]i by GABA. As revealed by gramicidin perforated-patch recording, reduced [Ca2+]i responses were due to a diminished driving force for Cl?. This suggests that immature neurons do not have an efficient inward transport that can compensate the loss of cytosolic Cl? resulting from sustained GABAA receptor activation by ambient GABA. Transient increases in external K+, which can induce voltage-dependent Cl? entry, restored GABA-induced [Ca2+]i elevations. In mature neurons, GABA reduced [Ca2+]i provided that background [Ca2+]i was elevated by the application of an L-type Ca2+ channel agonist. This was probably due to a hyperpolarization of the membrane by Cl? currents. K+-Cl? cotransport maintained the gradient for hyperpolarizing Cl? currents. We conclude that in immature midbrain neurons an inward Cl? transport is not effective although the GABA response is depolarizing. Further, GABA itself is not required for the developmental switch of GABAergic responses from depolarizing to hyperpolarizing in cultured midbrain neurons. PMID:12938674

Titz, Stefan; Hans, Michael; Kelsch, Wolfgang; Lewen, Andrea; Swandulla, Dieter; Misgeld, Ulrich



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

PubMed Central

Background Abnormal release of neurotransmitters after microwave exposure can cause learning and memory deficits. This study investigated the mechanism of this effect by exploring the potential role of phosphorylated synapsin I (p-Syn I). Methods Wistar rats, rat hippocampal synaptosomes, and differentiated (neuronal) PC12 cells were exposed to microwave radiation for 5 min at a mean power density of 30 mW/cm2. Sham group rats, synaptosomes, and cells were otherwise identically treated and acted as controls for all of the following post-exposure analyses. Spatial learning and memory in rats was assessed using the Morris Water Maze (MWM) navigation task. The protein expression and presynaptic distribution of p-Syn I and neurotransmitter transporters were examined via western blotting and immunoelectron microscopy, respectively. Levels amino acid neurotransmitter release from rat hippocampal synaptosomes and PC12 cells were measured using high performance liquid chromatograph (HPLC) at 6 hours after exposure, with or without synapsin I silencing via shRNA transfection. Results In the rat experiments, there was a decrease in spatial memory performance after microwave exposure. The expression of p-Syn I (ser-553) was decreased at 3 days post-exposure and elevated at later time points. Vesicular GABA transporter (VGAT) was significantly elevated after exposure. The GABA release from synaptosomes was attenuated and p-Syn I (ser-553) and VGAT were both enriched in small clear synaptic vesicles, which abnormally assembled in the presynaptic terminal after exposure. In the PC12 cell experiments, the expression of p-Syn I (ser-553) and GABA release were both attenuated at 6 hours after exposure. Both microwave exposure and p-Syn I silencing reduced GABA release and maximal reduction was found for the combination of the two, indicating a synergetic effect. Conclusion p-Syn I (ser-553) was found to play a key role in the impaired GABA release and cognitive dysfunction that was induced by microwave exposure. PMID:24743689

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



Treatment of refractory complex partial seizures: role of vigabatrin  

PubMed Central

Vigabatrin (VGB) is an antiepileptic drug that was designed to inhibit GABA-transaminase, and increase levels of ?-amino-butyric acid (GABA), a major inhibitory neurotransmitter in the brain. VGB has demonstrated efficacy as an adjunctive antiepileptic drug for refractory complex partial seizures (CPS) and for infantile spasms (IS). This review focuses on its use for complex partial seizures. Although VGB is well tolerated, there have been significant safety concerns about intramyelinic edema and visual field defects. VGB is associated with a risk of developing bilateral concentric visual field defects. Therefore, the use of VGB for complex partial seizures should be limited to those patients with seizures refractory to other treatments. Patients must have baseline and follow-up monitoring of visual fields, early assessment of its efficacy, and ongoing evaluation of the benefits and risks of VGB therapy. PMID:19851518

Waterhouse, Elizabeth J; Mims, Kimberly N; Gowda, Soundarya N



Rapid substrate-induced charge movements of the GABA transporter GAT1.  


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

Bicho, Ana; Grewer, Christof



Tectorotundal connections in turtles: an electron microscopic tracing and GABA-immunocytochemical study.  


The nucleus rotundus of the turtles Emys orbicularis and Testudo horsfieldi was analysed by axonal tracing methods and post-embedding GABA immunocytochemistry. After injections of horseradish peroxidase or biotinylated dextran amine into the optic tectum, electron microscopic observations showed that the vast majority of ipsilateral tectorotundal axon terminals were small in size, had smooth contours and contained small, round, densely packed synaptic vesicles. These terminals were GABA-immunonegative, often gathered in clusters, and established asymmetrical synaptic contacts with either small- or medium-sized GABA-negative dendritic profiles and with GABA-immunoreactive (GABA-ir) dendrites, which did not contain synaptic vesicles. Occasional GABA-ir-labelled axon terminals were observed; these may arise from the rare GABAergic neurons in the central tectal layer, or from neurons in the ventral pretectal nucleus, which projects both to the optic tectum and nucleus rotundus. In addition to tracer-labelled axon terminals, we observed both GABA-negative and GABA-ir cell bodies and dendrites also labelled by the tracer. No GABA-ir presynaptic dendritic profiles containing synaptic vesicles were observed. The existence in reptiles of reciprocal connections between the nucleus rotundus and the optic tectum as a phylogenetically ancient feedback system is discussed. PMID:17996857

Kenigfest, Natalia B; Rio, Jean Paul; Belekhova, Margarita G; Repérant, Jacques; Ward, Roger; Jay, Bruno; Vesselkin, Nikolai P



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

PubMed Central

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

Volk, David W.; Lewis, David A.



GABA transporter function, oligomerization state, and anchoring: correlates with subcellularly resolved FRET  

PubMed Central

The mouse ?-aminobutyric acid (GABA) transporter mGAT1 was expressed in neuroblastoma 2a cells. 19 mGAT1 designs incorporating fluorescent proteins were functionally characterized by [3H]GABA uptake in assays that responded to several experimental variables, including the mutations and pharmacological manipulation of the cytoskeleton. Oligomerization and subsequent trafficking of mGAT1 were studied in several subcellular regions of live cells using localized fluorescence, acceptor photobleach Förster resonance energy transfer (FRET), and pixel-by-pixel analysis of normalized FRET (NFRET) images. Nine constructs were functionally indistinguishable from wild-type mGAT1 and provided information about normal mGAT1 assembly and trafficking. The remainder had compromised [3H]GABA uptake due to observable oligomerization and/or trafficking deficits; the data help to determine regions of mGAT1 sequence involved in these processes. Acceptor photobleach FRET detected mGAT1 oligomerization, but richer information was obtained from analyzing the distribution of all-pixel NFRET amplitudes. We also analyzed such distributions restricted to cellular subregions. Distributions were fit to either two or three Gaussian components. Two of the components, present for all mGAT1 constructs that oligomerized, may represent dimers and high-order oligomers (probably tetramers), respectively. Only wild-type functioning constructs displayed three components; the additional component apparently had the highest mean NFRET amplitude. Near the cell periphery, wild-type functioning constructs displayed the highest NFRET. In this subregion, the highest NFRET component represented ?30% of all pixels, similar to the percentage of mGAT1 from the acutely recycling pool resident in the plasma membrane in the basal state. Blocking the mGAT1 C terminus postsynaptic density 95/discs large/zona occludens 1 (PDZ)-interacting domain abolished the highest amplitude component from the NFRET distributions. Disrupting the actin cytoskeleton in cells expressing wild-type functioning transporters moved the highest amplitude component from the cell periphery to perinuclear regions. Thus, pixel-by-pixel NFRET analysis resolved three distinct forms of GAT1: dimers, high-order oligomers, and transporters associated via PDZ-mediated interactions with the actin cytoskeleton and/or with the exocyst. PMID:19948998

Moss, Fraser J.; Imoukhuede, P.I.; Scott, Kimberly; Hu, Jia; Jankowsky, Joanna L.; Quick, Michael W.



Alpha Subunit Position and GABA Receptor Function  

NSDL National Science Digital Library

GABAA (γ-aminobutyric acid type A) receptors are ligand-gated ion channels composed of five subunits, generally two αs, two βs, and a γ2. Recent research in which sets of subunits containing α1 or α6 subunits were artificially linked has revealed the importance of subunit position in determining GABAA receptor function. Sensitivity to benzodiazepines depended on juxtaposition of an α1 subunit with the γ2 subunit, whereas sensitivity to furosemide depended only on the presence of an α6 subunit and not on its specific location. The major utility of the linked subunit approach is to provide a mechanism for discovering the functional signatures of defined subunit arrangements, and thus a route to identifying such arrangements in vivo.

David R. Burt (University of Maryland School of Medicine;Department of Pharmacology REV)



The Rhizobium leguminosarum bv. viciae VF39 gamma-aminobutyrate (GABA) aminotransferase gene (gabT) is induced by GABA and highly expressed in bacteroids.  


A Rhizobium leguminosarum bv. viciae VF39 gene (gabT) encoding a gamma-aminobutyrate (GABA) aminotransferase was identified, cloned and characterized. This gene is thought to be involved in GABA metabolism via the GABA shunt pathway, a theoretical bypass of the 2-oxoglutarate dehydrogenase complex. Mutants in gabT are still able to grow on GABA as a sole carbon and nitrogen source. 2-oxoglutarate-dependent GABA aminotransferase activity is absent in these mutants, while pyruvate-dependent activity remains unaffected. This indicates that at least two enzymes with different substrate specifities are involved in the GABA metabolism of R. leguminosarum bv. viciae VF39. The gabT promoter was cloned into a newly constructed, stable promoter-probe vector pJP2, suitable for the study of transcriptional GUS fusions in free-living bacteria and during symbiosis. Under free-living conditions the gabT promoter is induced by GABA and repressed by succinate. Transcriptional regulation is mediated by GabR in a repressor-like manner. During symbiosis with the pea host plant gabT is induced and highly expressed in the symbiotic zone. Nodules induced by gabT mutants, however, are still effective in nitrogen fixation. PMID:11832524

Prell, Jürgen; Boesten, Bert; Poole, Philip; Priefer, Ursula B



GABA-induced uncoupling of GABA/benzodiazepine site interactions is mediated by increased GABAA receptor internalization and associated with a change in subunit composition.  


Persistent activation of GABAA receptors triggers compensatory changes in receptor function that are relevant to physiological, pathological and pharmacological conditions. Chronic treatment of cultured neurons with GABA for 48h has been shown to produce a down-regulation of receptor number and an uncoupling of GABA/benzodiazepine site interactions with a half-time of 24-25h. Down-regulation is the result of a transcriptional repression of GABAA receptor subunit genes and depends on activation of L-type voltage-gated calcium channels. The mechanism of this uncoupling is currently unknown. We have previously demonstrated that a single brief exposure of rat primary neocortical cultures to GABA for 5-10min (t½=3min) initiates a process that results in uncoupling hours later (t½=12h) without a change in receptor number. Uncoupling is contingent upon GABAA receptor activation and independent of voltage-gated calcium influx. This process is accompanied by a selective decrease in subunit mRNA levels. Here, we report that the brief GABA exposure induces a decrease in the percentage of ?3-containing receptors, a receptor subtype that exhibits a high degree of coupling between GABA and benzodiazepine binding sites. Initiation of GABA-induced uncoupling is prevented by co-incubation of GABA with high concentrations of sucrose suggesting that it is dependent on a receptor internalization step. Moreover, results from immunocytochemical and biochemical experiments indicate that GABA exposure causes an increase in GABAA receptor endocytosis. Together, these data suggest that the uncoupling mechanism involves an initial increase in receptor internalization followed by activation of a signaling cascade that leads to selective changes in receptor subunit levels. These changes might result in the assembly of receptors with altered subunit compositions that display a lower degree of coupling between GABA and benzodiazepine sites. Uncoupling might represent a homeostatic mechanism that negatively regulates GABAergic transmission under physiological conditions in which synaptic GABAA receptors are transiently activated for several minutes. PMID:24215979

Gutiérrez, M L; Ferreri, M C; Gravielle, M C



gamma-Aminobutyric Acid is an Inhibitory Neurotransmitter Restricting the Release of Luteinizing Hormone-Releasing Hormone before the Onset of Puberty  

Microsoft Academic Search

To test the hypothesis that the pubertal increase in luteinizing hormone-releasing hormone (LHRH) release is withheld by a dominant inhibitory neuronal system, the role of gamma-aminobutyric acid (GABA), a known inhibitory neurotransmitter, in the control of LHRH release was examined in conscious female monkeys at the prepubertal and pubertal stages using a push-pull perfusion method. GABA, bicuculline (a GABA_A receptor

Dai Mitsushima; David L. Hei; Ei Terasawa



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

PubMed Central

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

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



Protective role of gamma-aminobutyric acid against chronic renal failure in rats.  


The protective effect of gamma-aminobutyric acid (GABA) against chronic renal failure (CRF) was investigated using a remnant kidney model with 5/6 nephrectomized rats. Nephrectomy led to renal dysfunction, which was evaluated via several parameters including serum urea nitrogen, creatinine (Cr) and Cr clearance. However, the administration of GABA ameliorated renal dysfunction, and a longer administration period of GABA increased its protective effect. In addition, nephrectomized control rats showed an elevation in the fractional excretion of sodium (FE(Na)) with an increase in urinary sodium, while GABA led to a significant decline in FE(Na). Moreover, nephrectomy resulted in a decrease of serum albumin and an increase of urinary protein with a change in the urinary protein pattern, whereas the rats administered GABA showed improvement in these changes associated with CRF caused by nephrectomy. This suggests that GABA would inhibit the disease progression and have a protective role against CRF. As one of the risk factors for CRF progression, hypertension was also regulated by GABA. The results also indicate that GABA may play a protective role against CRF through improvement of the serum lipid profile, with reductions in triglyceride and total cholesterol. Furthermore, nephrectomy led to renal oxidative stress with a decrease in the activity of antioxidative enzymes and elevation of lipid peroxidation. The administration of GABA attenuated oxidative stress induced by nephrectomy through an increase in superoxide dismutase and catalase, and decrease in lipid peroxidation. The histopathological lesions, including glomerular, tubular and interstitial lesions, under nephrectomy were also improved by GABA with the inhibition of fibronectin expression. This study demonstrated that GABA attenuated renal dysfunction via regulation of blood pressure and lipid profile, and it also ameliorated the oxidative stress induced by nephrectomy, suggesting the promising potential of GABA in protecting against renal failure progression. PMID:17132215

Sasaki, Sumiyo; Yokozawa, Takako; Cho, Eun Ju; Oowada, Shigeru; Kim, Mujo



MS transport assays for ?-aminobutyric acid transporters--an efficient alternative for radiometric assays.  


Transport assays for neurotransmitters based on radiolabeled substrates are widely spread and often indispensable in basic research and the drug development process, although the use of radioisotopes is inherently coupled to issues concerning radioactive waste and safety precautions. To overcome these disadvantages, we developed mass spectrometry (MS)-based transport assays for ?-aminobutyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system (CNS). These "MS Transport Assays" provide all capabilities of [(3)H]GABA transport assays and therefore represent the first substitute for the latter. The performance of our approach is demonstrated for GAT1, the most important GABA transporter (GAT) subtype. As GABA is endogenously present in COS-7 cells employed as hGAT1 expression system, ((2)H6)GABA was used as a substrate to differentiate transported from endogenous GABA. To record transported ((2)H6)GABA, a highly sensitive, short, robust, and reliable HILIC-ESI-MS/MS quantification method using ((2)H2)GABA as an internal standard was developed and validated according to the Center for Drug Evaluation and Research (CDER) guidelines. Based on this LC-MS quantification, a setup to characterize hGAT1 mediated ((2)H6)GABA transport in a 96-well format was established, that enables automated processing and avoids any sample preparation. The K(m) value for ((2)H6)GABA determined for hGAT1 is in excellent agreement with results obtained from [(3)H]GABA uptake assays. In addition, the established assay format enables efficient determination of the inhibitory potency of GAT1 inhibitors, is capable of identifying those inhibitors transported as substrates, and furthermore allows characterization of efflux. The approach described here combines the strengths of LC-MS/MS with the high efficiency of transport assays based on radiolabeled substrates and is applicable to all GABA transporter subtypes. PMID:25007119

Schmitt, Sebastian; Höfner, Georg; Wanner, Klaus T



Adrenergic regulation of GABA release from presynaptic terminals in rat cerebral cortex.  


The ?1-adrenoceptor agonist phenylephrine and the ?-adrenoceptor agonist isoproterenol have opposite effects on evoked EPSPs (eEPSPs) in the cerebral cortex. The suppressive effects of phenylephrine on eEPSPs are mediated by modulation of postsynaptic glutamate receptors, whereas enhancement of eEPSPs by isoproterenol is due to facilitation of glutamate release from presynaptic terminals. The present study used whole-cell patch-clamp recordings from layer V pyramidal neurons in visuocortical slice preparations to assess the effects of phenylephrine and isoproterenol on the release probability of ?-aminobutyric acid (GABA). The present study recorded evoked inhibitory postsynaptic potentials (eIPSCs) by repetitive electrical stimulation (duration, 100 ?s; 10 stimuli at 33 Hz) and miniature IPSCs (mIPSCs). The effects of phenylephrine (100 ?M) depended on the amplitude of eIPSCs: phenylephrine decreased the paired-pulse ratios (PPRs) of eIPSCs with smaller amplitudes (<~600 pA) but increased PPRs of eIPSCs with larger amplitude. Phenylephrine also exhibited amplitude-dependent modulation of mIPSCs, i.e., an increase in the frequency of smaller mIPSC events (<~20 pA) and a decrease in the frequency of larger events. These findings suggest that ?1-adrenoceptor activation facilitates GABA release from a subpopulation of GABAergic terminals that induce smaller-amplitude IPSCs in postsynaptic neurons. In contrast, isoproterenol (100 ?M) consistently decreased the PPR of eIPSCs and increased the frequency of mIPSCs, suggesting that presynaptic ?-adrenoceptors increase release probability from most GABAergic terminals. The complexity of adrenoceptor modulations in GABAergic synaptic transmission by ?1-adrenoceptor and ?-adrenoceptor activation may be due to the presence of pleiotropic subtypes of GABAergic interneurons in the cerebral cortex. PMID:24739708

Terakado, Masanori



Tonic and phasic alteration in amygdala 5-HT, glutamate and GABA transmission after prefrontal cortex damage in rats.  


The relationship between the ventromedial prefrontal cortex and the amygdala during the presentation of an unconditioned fear stimulus was assessed. Rats underwent bilateral ibotenic acid or vehicle administration into the ventromedial prefrontal cortex. Five weeks later, the behavior as well as the neurochemical changes in the amygdala was evaluated before and after a brief cat presentation. Lesioned animal freezing behavior increased 10 times when compared to controls. In the right basolateral amygdala, basal concentrations of 5-HT, 5-HIAA, glutamate and serine were elevated but basal level of GABA was diminished in lesioned animals relative to controls. Sham but not lesioned animals increased 5-HT and decreased GABA and serine levels after cat presentation. Phasic changes in glutamate were not detected either in lesioned or shams but the difference in amygdala glutamate between lesioned and shams persisted after cat presentation. These data show that increased serotonin and glutamate tone and decreased gabaergic tone in the amygdala correlate to elevated fear and anxiety after prefrontal cortex ibotenic acid lesion. The lesion also seems to produce a failure of adaptive changes in neurotransmitter systems revealing lost of control of the ventromedial prefrontal cortex over the amygdala in frightening situations. PMID:15044074

Gonzalez, Luis E; Quiñonez, Belkis; Rangel, Alejandra; Pino, Silvano; Hernandez, Luis



Synaptic inhibition and ?-aminobutyric acid in the mammalian central nervous system  

PubMed Central

Signal transmission through synapses connecting two neurons is mediated by release of neurotransmitter from the presynaptic axon terminals and activation of its receptor at the postsynaptic neurons. ?-Aminobutyric acid (GABA), non-protein amino acid formed by decarboxylation of glutamic acid, is a principal neurotransmitter at inhibitory synapses of vertebrate and invertebrate nervous system. On one hand glutamic acid serves as a principal excitatory neurotransmitter. This article reviews GABA researches on; (1) synaptic inhibition by membrane hyperpolarization, (2) exclusive localization in inhibitory neurons, (3) release from inhibitory neurons, (4) excitatory action at developmental stage, (5) phenotype of GABA-deficient mouse produced by gene-targeting, (6) developmental adjustment of neural network and (7) neurological/psychiatric disorder. In the end, GABA functions in simple nervous system and plants, and non-amino acid neurotransmitters were supplemented. PMID:23574805

OBATA, Kunihiko



Discovery of novel insomnia leads from screening traditional Chinese medicine database.  


Insomnia is a prominent modern disease that affects an increasing population. Undesirable side effects of commercial drugs highlight the need to develop novel insomnia drugs. Virtual screening of traditional chinese medicine Database@Taiwan (TCM Database@Taiwan) identified 2-O-Caffeoyl tartaric acid (1), 2-O-Feruloyl tartaric acid (2), and Mumefural (3) as potential agonists for both gamma-amino butyric acid (GABA) or benzodiazepine (BZ) binding sites. The TCM candidates exhibited higher affinity than GABA and Zolpidem, a phenomenon that could be attributed to higher quantity of stabilizing H-bonds. Efficacy profiles using support vector machines and pharmacophore contour also suggest drug potential of the TCM candidates. Fragments added to the de novo derivatives 3a, 3b, 3c for GABA binding site, and 1a, 2a, and 3d for BZ binding site contributed to new binding sites and structural stability, further optimizing binding to GABA or BZ binding sites. Increased opening of the ion channel by candidate ligands provide strong support for their potential biological functions. The dual binding properties of the TCM candidates present a unique opportunity to develop twin-targeting drugs with less side effects. Derivative structures can be used as starting points for developing high affinity GABAA receptor agonists with specificity towards GABA binding site and BZ binding site. PMID:23730798

Chen, Hsin-Yi; Chang, Su-sen; Chan, Yueh-Chiu; Chen, Calvin Yu-Chian



GABA suppresses neurogenesis in the adult hippocampus through GABAB receptors.  


Adult neurogenesis is tightly regulated through the interaction of neural stem/progenitor cells (NSCs) with their niche. Neurotransmitters, including GABA activation of GABAA receptor ion channels, are important niche signals. We show that adult mouse hippocampal NSCs and their progeny express metabotropic GABAB receptors. Pharmacological inhibition of GABAB receptors stimulated NSC proliferation and genetic deletion of GABAB1 receptor subunits increased NSC proliferation and differentiation of neuroblasts in vivo. Cell-specific conditional deletion of GABAB receptors supports a cell-autonomous role in newly generated cells. Our data indicate that signaling through GABAB receptors is an inhibitor of adult neurogenesis. PMID:24284211

Giachino, Claudio; Barz, Michael; Tchorz, Jan S; Tome, Mercedes; Gassmann, Martin; Bischofberger, Josef; Bettler, Bernhard; Taylor, Verdon



Ionotropic GABA Receptor From Lobster Olfactory Projection A. B. ZHAINAZAROV,1  

E-print Network

Ionotropic GABA Receptor From Lobster Olfactory Projection Neurons A. B. ZHAINAZAROV,1 M. WACHOWIAK and B. W. Ache. Ionotropic GABA receptor from lobster olfactory additional diversity within these two lobster and analyzed by whole cell and of crustacean (Dudel and Hatt 1976).cell-free patch-clamp recording

Boettcher, Anne


tonic inhibition must be carefully assessed. The source of the increased tonic GABA  

E-print Network

.Thesetimingconstraints pointtooverlappingbeneficialanddetrimental GABA functions and need to be resolved. Clarkson and colleagues' experimental reductionsofGABA-mediatedtonicinhibition affected the entire brain, leaving uncertainty as towhethertheenhancedtonicinhibitioninthe peri of the damaged cortical networks, as opposed to enhancing the long-term recovery of those networks. The latter

Rogers, John A.


Elevated Endogenous GABA Concentration Attenuates Glutamate-Glutamine Cycling between Neurons and Astroglia  

PubMed Central

In this study, the relationship between endogenous brain GABA concentration and glutamate-glutamine cycling flux (Vcyc) was investigated using in vivo 1H and 1H{13C} magnetic resonance spectroscopy techniques. Graded elevations of brain GABA levels were induced in rat brain after administration of the highly specific GABA-transaminase inhibitor vigabatrin (?-vinyl-GABA). The glial-specific substrate [2-13C]acetate and 1H{13C} magnetic resonance spectroscopy were used to measure Vcyc at different GABA levels. Significantly reduced Vcyc was found in rats pretreated with vigabatrin. The reduction in group mean Vcyc over the range of GABA concentrations investigated in this study (1.0 ± 0.3 ~ 5.1 ± 0.5 ?mol/g) was found to be nonlinear: ?Vcyc/Vcyc = [GABA (?mol/g)]?0.35 ? 1.0 (r2 = 0.98). The results demonstrate that Vcyc is modulated by endogenous GABA levels, and that glutamatergic and GABAergic interactions can be studied in vivo using noninvasive magnetic resonance spectroscopy techniques. PMID:19184333

Yang, Jehoon; Shen, Jun



Effects of GABA A receptor ligands on noradrenaline concentration and ?-adrenoceptor binding in mouse cerebral cortex  

Microsoft Academic Search

The present experiments investigated changes in ?-adrenoceptor binding and noradrenaline stores in mouse cerebral cortex after single treatments with drugs which bind to the GABAA receptor but which attenuate the actions of GABA. Neither the GABA antagonist, securinine, nor the picrotoxin\\/Cl? channel ligand, picrotoxin, affected noradrenaline levels or ?-adrenoceptor binding. However, both the benzodiazepine inverse agonist, DMCM, and pentylenetetrazole increased

D. Gettins; N. Goldsack; V. Ibegbuna; S. C. Stanford



GABA Accumulation in Response to Different Nitrogenous Compounds in Unicellular Cyanobacterium Synechocystis sp. PCC 6803.  


GABA accumulation and glutamate decarboxylase (GAD) activity, the principal enzyme involved in GABA formation, was investigated in cyanobacterium Synechocystis sp. PCC 6803 wild-type (WT) and gad knockout mutant strains grown in medium containing different nitrogenous compounds. Nitrate was the best nitrogen source for GAD activity and GABA accumulation followed by nitrite, ammonium, and urea. An increase in the accumulation of GABA was observed in WT and mutant cells grown for 24 h in medium supplemented with 0.5 mM putrescine or spermidine with a parallel increase in GAD activity. The mutant could not accumulate GABA at all the conditions tested except when supplemented with putrescine or spermidine, where high GABA levels were observed in both WT and mutant strains. Glutamate supplementation up to 10 mM for 24 h resulted in a significant increase in both GAD activity and GABA content. Overall results suggested that optimization of nitrogen source and nitrogenous compounds supplementation was effective for the enhancement of GABA accumulation in Synechocystis. PMID:25212770

Kanwal, Simab; Khetkorn, Wanthanee; Incharoensakdi, Aran



Identification of a Subunit TM2 Residue Mediating Proton Modulation of GABA Type A Receptors  

Microsoft Academic Search

GABA type A (GABAA) receptors are functionally regulated by external protons in a manner dependent on the receptor sub- unit composition. Although H can regulate the open proba- bility of single GABA ion channels, exactly what residues and receptor subunits are responsible for proton-induced modula- tion remain unknown. This study resolves this issue by using recombinant 1i subunit GABAA receptors

Megan E. Wilkins; Alastair M. Hosie; Trevor G. Smart



Modulation of GABA(A) receptors by benzodiazepines and barbiturates is autonomous of PKC activation.  


Previous studies have suggested that activation of calcium-phospholipid-dependent protein kinase (PKC) enhances benzodiazepine (BZD)- and pentobarbital (PB)- mediated potentiation of alpha(1)beta(1)gamma(2) GABA(A) receptors (GABA(A)-Rs). To delineate the underlying mechanism(s), voltage-clamp recordings were performed on recombinant alpha(1)beta(1)gamma(2) GABA(A) receptors functionally expressed in Xenopus laevis oocytes. GABA(A)-Rs were tested for their sensitivity to diazepam and PB before and after incubation in phorbol 12-myristate 13-acetate (PMA). PMA (25 nM) significantly attenuated the GABA(A) current (p<0.05, n=12-19) up to 90%. PMA treatment, however, did not alter the sensitivity to diazepam or pentobarbital. Similar results were obtained with recombinant alpha(1)beta(2)gamma(2) GABA receptors. These data suggest that PKC activation does not alter the allosteric modulation of GABA(A)-Rs by benzodiazepines and barbiturates and is consistent with the observation from other studies in oocytes that PMA decreases the amplitude of the GABA-activated currents via receptor internalization rather than modification of receptor kinetics. PMID:11166325

Ghansah, E; Weiss, D S



[Distribution of GABA-immunoreactive elements in the reptile amygdaloid complex].  


GABA-immunoreactive (GABA-I) elements (neuronal somata and neuropile) are detected in turtle Emys orbicularis and lizard Ophysaurus spodus in all structures of ventral and dorsal parts of amygdaloid complex (AC) considered as phylogenetic more ancient and younger, respectively by means of the immunohistochemical method. Their maximal quantity in the ventral section of AC is found in the lateral region, lesser--in the ventral, central and medial regions. Besides in lizards a specialized laminar distribution of GABA-I elements in n. sphaericus is observed. GABA-I neurons are also detected in structures of dorsal part in turtles and lizards against the background of the immunopositive neuropile of a moderate density. It is supposed that GABA-ergic innervation of AC is liable to considerable variations in connection with taxonomic, ecological and other factors. PMID:1584309

Belekhova, M G; Chkheidze, D D; Veselkin, N P; Kenigfest, N B; Kratskin, I L; P'err, Zh; Reperan, Zh



Effect of ligustrazine on levels of amino acid neurotransmitters in rat striatum after cerebral ischemia-reperfusion injury.  


This study aimed to evaluate the effect of ligustrazine on levels of amino acid transmitters in the extracellular fluid of striatum following cerebral ischemia/reperfusion (I/R) in male Sprague-Dawley rats. A microdialysis cannula guide was implanted into the right striatum. After recovery, animals underwent a sham operation or middle cerebral artery occlusion (MCAO). Those that developed cerebral ischemia after MCAO were randomized to receive propylene glycol salt water and ligustrazine respectively. Striatal fluid samples were collected from all animals at 15-min intervals after treatment and were subjected to HPLC analysis of aspartic acid, glutamic acid, taurine, and ?-amino butyric acid. Upon the last sample collection, animals were sacrificed and brain tissue specimens were collected for triphenyltetrazolium chloride staining and NeuN staining. Compared with the sham operation, MCAO induced significant neurological deficits and increased striatal concentrations of the four neurotransmitters assessed in a time-dependent manner (P < 0.01). Ligustrazine effectively attenuated the detrimental effects of MCAO on the brain. These observations suggest that ligustrazine as a novel cerebral infarction-protective agent may have potential clinical implications for I/R-related brain damage. PMID:25159498

Han, Jin; Wan, Hai-Tong; Yang, Jie-Hong; Zhang, Yu-Yan; Ge, Li-Jun; Bie, Xiao-Dong



Modular pathways for editing non-cognate amino acids by human cytoplasmic leucyl-tRNA synthetase  

PubMed Central

To prevent potential errors in protein synthesis, some aminoacyl-transfer RNA (tRNA) synthetases have evolved editing mechanisms to hydrolyze misactivated amino acids (pre-transfer editing) or misacylated tRNAs (post-transfer editing). Class Ia leucyl-tRNA synthetase (LeuRS) may misactivate various natural and non-protein amino acids and then mischarge tRNALeu. It is known that the fidelity of prokaryotic LeuRS depends on multiple editing pathways to clear the incorrect intermediates and products in the every step of aminoacylation reaction. Here, we obtained human cytoplasmic LeuRS (hcLeuRS) and tRNALeu (hctRNALeu) with high activity from Escherichia coli overproducing strains to study the synthetic and editing properties of the enzyme. We revealed that hcLeuRS could adjust its editing strategy against different non-cognate amino acids. HcLeuRS edits norvaline predominantly by post-transfer editing; however, it uses mainly pre-transfer editing to edit ?-amino butyrate, although both amino acids can be charged to tRNALeu. Post-transfer editing as a final checkpoint of the reaction was very important to prevent mis-incorporation in vitro. These results provide insight into the modular editing pathways created to prevent genetic code ambiguity by evolution. PMID:20805241

Chen, Xin; Ma, Jing-Jing; Tan, Min; Yao, Peng; Hu, Qing-Hua; Eriani, Gilbert; Wang, En-Duo



Presynaptic Control of Corticostriatal Synapses by Endogenous GABA  

PubMed Central

Corticostriatal terminals have presynaptic GABAB receptors that limit glutamate release, but how these receptors are activated by endogenous GABA released by different types of striatal neurons is still unknown. To address this issue, we used single and paired whole-cell recordings combined with stimulation of corticostriatal fibers in rats and mice. In the presence of opioid, GABAA, and NK1 receptor antagonists, antidromic stimulation of a population of striatal projection neurons caused suppression of subsequently evoked EPSPs in projection neurons. These effects were larger at intervals of 500 ms than 1 or 2 s, and were fully blocked by the selective GABAB receptor antagonist CGP 52432. Bursts of spikes in individual projection neurons were not able to inhibit evoked EPSPs. Similarly, spikes in fast spiking interneurons and low-threshold spike interneurons failed to elicit detectable effects mediated by GABAB receptors. Conversely, spikes in individual neurogliaform interneurons suppressed evoked EPSPs, and these effects were blocked by CGP 52432. These results provide the first demonstration of how GABAB receptors are activated by endogenous GABA released by striatal neuronal types. PMID:24068811

Logie, Christopher; Bagetta, Vincenza



Sorting of the Vesicular GABA Transporter to Functional Vesicle Pools by an Atypical Dileucine-like Motif  

PubMed Central

Increasing evidence indicates that individual synaptic vesicle proteins may use different signals, endocytic adaptors, and trafficking pathways for sorting to distinct pools of synaptic vesicles. Here, we report the identification of a unique amino acid motif in the vesicular GABA transporter (VGAT) that controls its synaptic localization and activity-dependent recycling. Mutational analysis of this atypical dileucine-like motif in rat VGAT indicates that the transporter recycles by interacting with the clathrin adaptor protein AP-2. However, mutation of a single acidic residue upstream of the dileucine-like motif leads to a shift to an AP-3-dependent trafficking pathway that preferentially targets the transporter to the readily releasable and recycling pool of vesicles. Real-time imaging with a VGAT-pHluorin fusion provides a useful approach to explore how unique sorting sequences target individual proteins to synaptic vesicles with distinct functional properties. PMID:23804087

Santos, Magda S.; Park, C. Kevin; Foss, Sarah M.; Li, Haiyan



Reduced tonic inhibition in striatal output neurons from Huntington mice due to loss of astrocytic GABA release through GAT-3  

PubMed Central

The extracellular concentration of the two main neurotransmitters glutamate and GABA is low but not negligible which enables a number of tonic actions. The effects of ambient GABA vary in a region-, cell-type, and age-dependent manner and can serve as indicators of disease-related alterations. Here we explored the tonic inhibitory actions of GABA in Huntington's disease (HD). HD is a devastating neurodegenerative disorder caused by a mutation in the huntingtin gene. Whole cell patch clamp recordings from striatal output neurons (SONs) in slices from adult wild type mice and two mouse models of HD (Z_Q175_KI homozygotes or R6/2 heterozygotes) revealed an HD-related reduction of the GABA(A) receptor-mediated tonic chloride current (ITonic(GABA)) along with signs of reduced GABA(B) receptor-mediated presynaptic depression of synaptic GABA release. About half of ITonic(GABA) depended on tetrodotoxin-sensitive synaptic GABA release, but the remaining current was still lower in HD. Both in WT and HD, ITonic(GABA) was more prominent during the first 4 h after preparing the slices, when astrocytes but not neurons exhibited a transient depolarization. All further tests were performed within 1–4 h in vitro. Experiments with SNAP5114, a blocker of the astrocytic GABA transporter GAT-3, suggest that in WT but not HD GAT-3 operated in the releasing mode. Application of a transportable substrate for glutamate transporters (D-aspartate 0.1–1 mM) restored the non-synaptic GABA release in slices from HD mice. ITonic(GABA) was also rescued by applying the hyperagonist gaboxadol (0.33 ?M). The results lead to the hypothesis that lesion-induced astrocyte depolarization facilitates non-synaptic release of GABA through GAT-3. However, the capacity of depolarized astrocytes to provide GABA for tonic inhibition is strongly reduced in HD. PMID:24324407

Wójtowicz, Anna M.; Dvorzhak, Anton; Semtner, Marcus; Grantyn, Rosemarie



Characterization of the production of biogenic amines and gamma-aminobutyric acid in the soybean pastes fermented by Aspergillus oryzae and Lactobacillus brevis.  


The production of gamma-aminobutyric acid (GABA) using GABA-producing lactic acid bacteria (LAB) has been considered to be an attractive strategy. However, some LAB may produce biogenic amines which may be of concern from the safety point. The aim of the present study was to characterize the production of GABA and biogenic amines (BA) in the soybean pastes fermented by Aspergillus oryzae (A. oryzae) FMB S46471 and GABA-producing Lactobacillus brevis (L.brevis) GABA 100. After ripening periods for 90 days, the levels of BA (putrescine, cadaverine, histamine, and tyramine) and GABA in the fermented soybean were assessed by high performance liquid chromatography (HPLC). The soybean pastes fermented by A. oryzae and L. brevis showed a range of 7,130-11,592 mg/kg for GABA, 178-305 mg/kg for tyramine, 139-163 mg/kg for putrescine, 7.4-10.8 mg/kg for histamine, and 7.1-7.9 mg/kg for cadaverine, whereas the soybean pastes fermented by A. oryzae only showed a range of 30-1,671 mg/kg for GABA, 0.8-189 mg/kg for tyramine, 1.3- 85 mg/kg for putrescine, up to 3.6 mg/kg for histamine, and 0.2-2.4 mg/kg for cadaverine. The results showed that the production of GABA was accompanied by the increase in the production of BA even though the production levels of histamine and cadaverine were very low. This is first study to simultaneously characterize the production of BA and GABA in the GABA enriched fermented soybean pastes and warrants further study to minimize the production of BA while optimizing the production of GABA. PMID:25341471

Kim, Nam Yeun; Ji, Geun Eog



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

PubMed Central

Evidence suggesting that central nervous system ?-aminobutyric acid (GABA) concentrations are reduced in patients with major depressive disorder (MDD) has been present since at least 1980, and this idea has recently gained support from more recent magnetic resonance spectroscopy data. These observations have led to the assumption that MDD’s underlying etiology is tied to an overall reduction in GABA-mediated inhibitory neurotransmission. In this paper, we review the mechanisms that govern GABA and glutamate concentrations in the brain, and provide a comprehensive and critical evaluation of the clinical data supporting reduced GABA neurotransmission in MDD. This review includes an evaluation of magnetic resonance spectroscopy data, as well as data on the expression and function of the GABA-synthesizing enzyme glutamic acid decarboxylase, GABA neuron-specific cell markers, such as parvalbumin, calretinin and calbindin, and the GABAA and GABAB receptors in clinical MDD populations. We explore a potential role for glial pathology in MDD-related reductions in GABA concentrations, and evidence of a connection between neurosteroids, GABA neurotransmission, and hormone-related mood disorders. Additionally, we investigate the effects of GABAergic pharmacological agents on mood, and demonstrate that these compounds have complex effects that do not universally support the idea that reduced GABA neurotransmission is at the root of MDD. Finally, we discuss the connections between serotonergic and GABAergic neurotransmission, and show that two serotonin-focused antidepressants – the selective serotonin-reuptake inhibitor fluoxetine and the multimodal antidepressant vortioxetine – modulate GABA neurotransmission in opposing ways, despite both being effective MDD treatments. Altogether, this review demonstrates that there are large gaps in our understanding of the relationship between GABA physiology and MDD, which must be remedied with more data from well-controlled empirical studies. In conclusion, this review suggests that the simplistic notion that MDD is caused by reduced GABA neurotransmission must be discarded in favor of a more nuanced and complex model of the role of inhibitory neurotransmission in MDD. PMID:25653499

Pehrson, Alan L; Sanchez, Connie



High Selectivity of the -Aminobutyric Acid Transporter 2 (GAT-2, SLC6A13) Revealed by Structure-based Approach*S  

E-print Network

neurotransmitter that triggers inhibitory sig- naling pathways via various receptors (e.g., GABAA). The GABA neurotransmitter in the mammalian brain and acts by binding to the GABAergic receptors in inhibitory neu- rons (e of osmolytes such as neurotransmitters and amino acids. Four SLC6 members trans- port GABA, a key

Sali, Andrej


?-Aminobutyric acid induces resistance against Penicillium expansum by priming of defence responses in pear fruit.  


The results from this study showed that treatment with ?-aminobutyric acid (GABA), at 100-1000 ?g/ml, induced strong resistance against blue mould rot caused by Penicillium expansum in pear fruit. Moreover, the activities of five defence-related enzymes (including chitinase, ?-1,3-glucanase, phenylalnine ammonialyase, peroxidase and polyphenol oxidase) and the expression of these corresponding genes were markedly and/or promptly enhanced in the treatment with GABA and inoculation with P. expansum compared with those that were treated with GABA or inoculated with pathogen alone. In addition, the treatment of pear with GABA had little adverse effect on the edible quality of the fruit. To the best of our knowledge, this is the first report that GABA can effectively reduce fungal disease of harvested fruit. Its mechanisms may be closely correlated with the induction of fruit resistance by priming activation and expression of defence-related enzymes and genes upon challenge with pathogen. PMID:24767023

Yu, Chen; Zeng, Lizhen; Sheng, Kuang; Chen, Fangxia; Zhou, Tao; Zheng, Xiaodong; Yu, Ting



Identification and characterization of GABA(A) receptor autoantibodies in autoimmune encephalitis.  


Autoimmune forms of encephalitis have been associated with autoantibodies against synaptic cell surface antigens such as NMDA- and AMPA-type glutamate receptors, GABA(B) receptor, and LGI1. However, it remains unclear how many synaptic autoantigens are yet to be defined. Using immunoproteomics, we identified autoantibodies against the GABA(A) receptor in human sera from two patients diagnosed with encephalitis who presented with cognitive impairment and multifocal brain MRI abnormalities. Both patients had antibodies directed against the extracellular epitope of the ?3 subunit of the GABA(A) receptor. The ?3-subunit-containing GABA(A) receptor was a major target of the patients' serum antibodies in rat hippocampal neurons because the serum reactivity to the neuronal surface was greatly decreased by 80% when the ?3 subunit was knocked down. Our developed multiplex ELISA testing showed that both patients had similar levels of GABA(A) receptor antibodies, one patient also had a low level of LGI1 antibodies, and the other also had CASPR2 antibodies. Application of the patients' serum at the time of symptom presentation of encephalitis to rat hippocampal neuron cultures specifically decreased both synaptic and surface GABA(A) receptors. Furthermore, treatment of neurons with the patients' serum selectively reduced miniature IPSC amplitude and frequency without affecting miniature EPSCs. These results strongly suggest that the patients' GABA(A) receptor antibodies play a central role in the patients' symptoms. Therefore, this study establishes anti-GABA(A) receptor encephalitis and expands the pathogenic roles of GABA(A) receptor autoantibodies. PMID:24920620

Ohkawa, Toshika; Satake, Shin'Ichiro; Yokoi, Norihiko; Miyazaki, Yu; Ohshita, Tomohiko; Sobue, Gen; Takashima, Hiroshi; Watanabe, Osamu; Fukata, Yuko; Fukata, Masaki




PubMed Central

Background Withdrawal from chronic ethanol enhances ventral tegmental area (VTA) GABA neuron excitability and reduces mesolimbic dopamine (DA) neurotransmission, which is suppressed by acupuncture at Shenmen (HT7) points (Zhao et al., 2006). The aim of this study was to evaluate the effects of HT7 acupuncture on VTA GABA neuron excitability, ethanol inhibition of VTA GABA neuron firing rate, and ethanol self-administration. A role for opioid receptors (ORs) in ethanol and acupuncture effects is also explored. Methods Using electrophysiological methods in mature rats, we evaluated the effects of HT7 stimulation and opioid antagonists on VTA GABA neuron firing rate. Using behavioral paradigms in rats, we evaluated the effects of HT7 stimulation and opioid antagonists on ethanol self-administration using a modification of the sucrose fading procedure. Results HT7 stimulation produced a biphasic modulation of VTA GABA neuron firing rate characterized by transient enhancement followed by inhibition and subsequent recovery in 5 min. HT7 inhibition of VTA GABA neuron firing rate was blocked by systemic administration of the non-selective ?-opioid receptor (MOR) antagonist naloxone. HT7 stimulation significantly reduced ethanol suppression of VTA GABA neuron firing rate, which was also blocked by naloxone. HT7 acupuncture reduced ethanol self-administration without affecting sucrose consumption. Systemic administration of the ?-opioid receptor (DOR) antagonist naltrindole blocked ethanol suppression of VTA GABA neuron firing rate and significantly reduced ethanol self-administration without affecting sucrose consumption. Conclusions These findings suggest that DOR-mediated opioid modulation of VTA GABA neurons may mediate acupuncture’s role in modulating mesolimbic DA release and suppressing the reinforcing effects of ethanol. PMID:20860620

Yang, Chae Ha; Yoon, Seong Shoon; Hansen, David M.; Wilcox, Jeffrey D.; Blumell, Bryan R; Park, Jung Jae; Steffensen, Scott C.



Retinal and cortical afferents to the dorsal lateral geniculate nucleus of the turtle, Emys orbicularis: a combined axonal tracing, glutamate, and GABA immunocytochemical electron microscopic study.  


The dorsal lateral geniculate nucleus (GLd) of the turtle Emys orbicularis has been analyzed with axonal tracing methods and immunocytochemical techniques for glutamate (GLU) and gamma-aminobutyric acid (GABA), in combination with a quantitative study of the morphologic characteristics, distribution, and synaptology of the retinofugal and corticofugal terminals. Ultrastructural observations show that the vast majority of retinal terminals (Rtr) have clear, rounded synaptic vesicles and account for 16% of all profiles containing synaptic vesicles (PCSV). Their synaptic index (0.5) is low, and they make three times more contacts with the dendrites of projection cells than with those of interneurons. A low proportion of retinal terminals of a second category contain pleomorphic synaptic vesicles and are highly GABA immunoreactive. Axon terminals, unlabeled after intraocular injection of the tracer (SR), smaller in size and with more rounded clear synaptic vesicles, longer synaptic differentiations, and higher synaptic index than Rtr terminals, account for 19.7% of all PCSV and make asymmetric synaptic contacts with large dendrites of projection cells and less with the dendrites of interneurons. Some SR have been unambiguously identified as corticofugal terminals (Cg), either after cortical injection of the tracer (16%) or cortical lesion (37%). Retinal and Cg/SR terminals are spatially segregated within the GLd. Both are highly GLU immunoreactive, with the highest density of labeling over synaptic vesicles, suggesting that these terminals may use GLU as neurotransmitter. The level of GLU immunoreactivity of GABA-positive profiles is half that of Rtr and Cg/SR terminals and is greatest over mitochondria, possibly reflecting the 'metabolic' pool of GLU that serves as a precursor in the formation of GABA. PMID:9486826

Kenigfest, N B; Repérant, J; Rio, J P; Belekhova, M G; Ward, R; Vesselkin, N P; Miceli, D; Herbin, M



Colocalization of GABA and glycine in the ventral nucleus of the lateral lemniscus in rat: an in situ hybridization and semiquantitative immunocytochemical study.  


We have studied by in situ hybridization for GAD65 mRNA in thick sections and by semiquantitative postembedding immunocytochemistry in consecutive semithin sections, the expression of gamma-aminobutyric acid (GABA) and glycine in cell bodies and axosomatic puncta of the rat ventral nucleus of the lateral lemniscus (VNLL), a prominent monaural brainstem auditory structure. The in situ hybridization and the densitometric analysis of the immunostaining suggest that the rat VNLL contains two main populations of neurons. Approximately one-third of neurons are unstained with either technique and are presumably excitatory; their cell bodies are enveloped by a large number of glycine-immunoreactive puncta. Most if not all of the remaining two-thirds colocalize GABA and glycine and are assumed to be inhibitory. These two populations show a complementary distribution within the VNLL, with inhibitory neurons located mainly ventrally and excitatory neurons dorsally. In scatterplots of gray values measured from cell bodies, the double-labeled cells appear to form a single cluster in terms of their staining intensities for the two transmitter candidates. However, this cluster may have to be further subdivided because cells with extreme GABA/glycine ratios differ from those with average ratios with respect to location or size. The VNLL seems unique among auditory structures by its large number of neurons that colocalize GABA and glycine. Although the functional significance of this colocalization remains unknown, our results suggest that the VNLL exerts convergent excitatory and inhibitory influences over the inferior colliculus, which may underlie the timing processing in the auditory midbrain. PMID:11268006

Riquelme, R; Saldaña, E; Osen, K K; Ottersen, O P; Merchán, M A



Electrical Wiring of the Aldehyde Oxidoreductase PaoABC with a Polymer Containing Osmium Redox Centers: Biosensors for Benzaldehyde and GABA  

PubMed Central

Biosensors for the detection of benzaldehyde and ??aminobutyric acid (GABA) are reported using aldehyde oxidoreductase PaoABC from Escherichia coli immobilized in a polymer containing bound low potential osmium redox complexes. The electrically connected enzyme already electrooxidizes benzaldehyde at potentials below ?0.15 V (vs. Ag|AgCl, 1 M KCl). The pH-dependence of benzaldehyde oxidation can be strongly influenced by the ionic strength. The effect is similar with the soluble osmium redox complex and therefore indicates a clear electrostatic effect on the bioelectrocatalytic efficiency of PaoABC in the osmium containing redox polymer. At lower ionic strength, the pH-optimum is high and can be switched to low pH-values at high ionic strength. This offers biosensing at high and low pH-values. A “reagentless” biosensor has been formed with enzyme wired onto a screen-printed electrode in a flow cell device. The response time to addition of benzaldehyde is 30 s, and the measuring range is between 10–150 µM and the detection limit of 5 µM (signal to noise ratio 3:1) of benzaldehyde. The relative standard deviation in a series (n = 13) for 200 µM benzaldehyde is 1.9%. For the biosensor, a response to succinic semialdehyde was also identified. Based on this response and the ability to work at high pH a biosensor for GABA is proposed by coimmobilizing GABA-aminotransferase (GABA-T) and PaoABC in the osmium containing redox polymer. PMID:25587431

Badalyan, Artavazd; Dierich, Marlen; Stiba, Konstanze; Schwuchow, Viola; Leimkühler, Silke; Wollenberger, Ulla



Renoprotective Effects of Gamma-Aminobutyric Acid on Cisplatin-induced Acute Renal Injury in Rats.  


To investigate the effect of gamma-aminobutyric acid (GABA) on acute renal injury (ARI), we used here a rat model of acute tubular necrosis induced by the anticancer drug cisplatin (CP). GABA was given orally (100 or 500 mg/kg/day for ten consecutive days), and on the 6th day, some of the treated rats were also injected intraperitoneally with either saline or CP (6 mg/kg). Four days after CP treatment, urine was collected from all rats, which were then anaesthetized for blood pressure and renal blood flow monitoring. This was followed by intravenous injection of norepinephrine for the assessment of renal vasoconstrictor responses. Thereafter, blood and kidneys were collected for measurement of several functional, biochemical and structural parameters. GABA treatment (at 500 but not 100 mg/kg) significantly mitigated all the measured physiological and biochemical indices. Sections from saline- and GABA-treated rats showed apparently normal proximal tubules. However, kidneys of CP-treated rats had a moderate degree of necrosis. This was markedly lessened when CP was given simultaneously with GABA (500 mg/kg). The concentration of platinum in the cortical tissues was not significantly altered by GABA treatment. The results suggested that GABA can ameliorate CP nephrotoxicity in rats. Pending further pharmacological and toxicological studies, GABA may be considered a potentially useful nephroprotective agent in CP-induced ARI. PMID:25052259

Ali, Badreldin H; Al-Salam, Suhail; Al Za'abi, Mohammed; Al Balushi, Khalid A; AlMahruqi, Ahmed S; Beegam, Somyia; Al-Lawatia, Intisar; Waly, Mostafa I; Nemmar, Abderrahim



[Determination of gamma-aminobutyric acid and glutamate in human gastric mucosa by high performance liquid chromatography].  


A method for analysis of gamma-aminobutyric acid (GABA) and glutamate (Glu) in human gastric mucosa by high performance liquid chromatography (HPLC) was developed. A gradient elution was used for the separation and quantification of GABA and Glu after pre-column derivatization with phenylisothiocyanate (PITC). The column was Pico x Tag for free amino acids. GABA and Glu were determined with UV detector at 254 nm. Good linearities were observed within the ranges from 0.125 to 6.25 micromol/L for GABA and from 0.025 to 2.5 mmol/L for Glu. The average recoveries were 95.4% for GABA and 93.5% for Glu. The intra- and inter-precision values were within 3.56% and 7.47% for GABA, and 1.12% and 5.98% for Glu, respectively. The method is sensitive, specific and accurate. It can be used in the determination of GABA and Glu in human gastric mucosa tissue. The concentrations of GABA and Glu in cancer tissues are significantly higher than those in normal tissue. PMID:15712869

Tan, Li; Liu, Fangnan; Zhang, Xusong



Identification and Characterization of ?-Aminobutyric Acid Uptake System GabPCg (NCgl0464) in Corynebacterium glutamicum  

PubMed Central

Corynebacterium glutamicum is widely used for industrial production of various amino acids and vitamins, and there is growing interest in engineering this bacterium for more commercial bioproducts such as ?-aminobutyric acid (GABA). In this study, a C. glutamicum GABA-specific transporter (GabPCg) encoded by ncgl0464 was identified and characterized. GabPCg plays a major role in GABA uptake and is essential to C. glutamicum growing on GABA. GABA uptake by GabPCg was weakly competed by l-Asn and l-Gln and stimulated by sodium ion (Na+). The Km and Vmax values were determined to be 41.1 ± 4.5 ?M and 36.8 ± 2.6 nmol min?1 (mg dry weight [DW])?1, respectively, at pH 6.5 and 34.2 ± 1.1 ?M and 67.3 ± 1.0 nmol min?1 (mg DW)?1, respectively, at pH 7.5. GabPCg has 29% amino acid sequence identity to a previously and functionally identified aromatic amino acid transporter (TyrP) of Escherichia coli but low identities to the currently known GABA transporters (17% and 15% to E. coli GabP and Bacillus subtilis GabP, respectively). The mutant RES167 ?ncgl0464/pGXKZ9 with the GabPCg deletion showed 12.5% higher productivity of GABA than RES167/pGXKZ9. It is concluded that GabPCg represents a new type of GABA transporter and is potentially important for engineering GABA-producing C. glutamicum strains. PMID:22307305

Zhao, Zhi; Ma, Wen-hua; Zhou, Ning-Yi



Endospore abundance and D:L-amino acid modeling of bacterial turnover in holocene marine sediment (Aarhus Bay)  

NASA Astrophysics Data System (ADS)

In order to study bacterial activity, and turnover times of bacterial necromass and biomass in marine sediment, two stations from the Aarhus Bay, Denmark were analyzed. Sediment cores were up to 11 m deep and covered a timescale from the present to ˜11,000 years ago. Sediment was analyzed for total hydrolysable amino acids (THAA), total hydrolysable amino sugars, the bacterial endospore marker dipicolinic acid (DPA), and amino acid enantiomers (L- and D-form) of aspartic acid. Turnover times of bacterial necromass and vegetative cells, as well as carbon oxidation rates were estimated by use of the D:L-amino acid racemization model. Diagenetic indicators were applied to evaluate the diagenetic state of the sedimentary organic matter. The contribution of amino acids to total organic carbon, and the ratio between the amino acids aspartic acid and glutamic acid, and their respective non protein degradation products, ?-alanine and ?-amino butyric acid, all indicated increasing degradation state of the organic matter with sediment depth and age. Quantification of DPA showed that endospores were abundant, and increased with depth relative to vegetative cells. Most of the amino acids (97%) could be ascribed to microbial necromass, i.e. the remains of dead bacterial cells. Model estimates showed that the turnover times of microbial necromass were in the range of 0.5-1 × 105 years, while turnover times of vegetative cells were in the range of tens to hundreds of years. The turnover time of the TOC pool increased with depth in the sediment, indicating that the TOC pool became progressively more refractory and unavailable to microorganisms with depth and age of the organic matter.

Langerhuus, Alice T.; Røy, Hans; Lever, Mark A.; Morono, Yuki; Inagaki, Fumio; Jørgensen, Bo B.; Lomstein, Bente Aa.



GABA and glutamate mediate rapid neurotransmission from suprachiasmatic nucleus to hypothalamic paraventricular nucleus in rat.  

PubMed Central

1. Intracellular sharp electrode and whole-cell patch-clamp recording from characterized paraventricular nucleus (PVN) neurones in rat hypothalamic slices were used to study the synaptic mechanism and associated neurotransmitters that mediate their response to suprachiasmatic nucleus (SCN) stimulation. 2. Electrical stimulation restricted to SCN evoked short-latency inhibitory postsynaptic potentials (IPSPs) or combinations of IPSPs and excitatory postsynaptic potentials (EPSPs) in all (n = 59) PVN neurones tested. Type I neurones (n = 18) were magnocellular and a majority (13/18) demonstrated monosynaptic IPSPs that reversed polarity at the chloride equilibrium potential and were sensitive to bicuculline. 3. Type II (n = 10) and III parvocellular (n = 13), and unclassifiable neurones (n = 18) displayed combinations of IPSPs and EPSPs following similar stimuli applied to SCN. IPSP blockade with bicuculline uncovered SCN-evoked monosynaptic dual-component EPSPs that were sensitive to N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists. In addition, chemical microstimulation within SCN was associated with transient increases in spontaneous EPSPs recorded from these PVN neurones. 4. These data imply that the amino acids GABA and glutamate are important mediators of fast monosynaptic transmission from SCN to defined neurones in PVN, and are candidates for conveying circadian rhythmicity to PVN regulation of neuroendocrine and autonomic processes. PMID:8930841

Hermes, M L; Coderre, E M; Buijs, R M; Renaud, L P



Chronic stress shifts the GABA reversal potential in the hippocampus and increases seizure susceptibility.  


The most commonly reported precipitating factor for seizures is stress. However, the underlying mechanisms whereby stress triggers seizures are not yet fully understood. Here we demonstrate a potential mechanism underlying changes in neuronal excitability in the hippocampus following chronic stress, involving a shift in the reversal potential for GABA (EGABA) associated with a dephosphorylation of the potassium chloride co-transporter, KCC2. Mice subjected to chronic restraint stress (30min/day for 14 consecutive days) exhibit an increase in serum corticosterone levels which is associated with increased susceptibility to seizures induced with kainic acid (20mg/kg). Following chronic stress, but not acute stress, we observe a dephosphorylation of KCC2 residue S940, which regulates KCC2 cell surface expression and function, in the hippocampus. To determine the impact of alterations in KCC2 expression following chronic stress, we performed gramicidin perforated patch recordings to measure changes in EGABA and neuronal excitability of principal hippocampal neurons. We observe a depolarizing shift in EGABA in hippocampal CA1 pyramidal neurons after chronic stress. In addition, there is an increase in the intrinsic excitability of CA1 pyramidal neurons, evident by a shift in the input-output curve which could be reversed with the NKCC1 inhibitor, bumetanide. These data uncover a potential mechanism involving chronic stress-induced plasticity in chloride homeostasis which may contribute to stress-induced seizure susceptibility. PMID:25524838

MacKenzie, Georgina; Maguire, Jamie



GABA and benzodiazepine receptors in the gerbil brain after transient ischemia: demonstration by quantitative receptor autoradiography  

SciTech Connect

Quantitative receptor autoradiography was used to measure the binding of gamma-aminobutyric acid (GABA) and benzodiazepine receptors after ischemia by means of transient occlusion of bilateral common carotid arteries in the gerbil. (/sup 3/H)Muscimol was used to label the GABAA receptors and (/sup 3/H)flunitrazepam to label central type benzodiazepine receptors. In the superolateral convexities of the frontal cortices, (/sup 3/H)muscimol binding was increased in 60% of the animals killed 3 days after ischemia, and decreased in 67% of the animals killed 27 days after ischemia. Twenty-seven days after ischemia, (/sup 3/H)flunitrazepam binding in the substantia nigra pars reticulata increased to 252% of the control, though the increase in (/sup 3/H)muscimol binding was not significant. In the dorsolateral region of the caudate putamen, marked neuronal necrosis and depletion of both (/sup 3/H)muscimol and (/sup 3/H)flunitrazepam binding sites were observed 27 days after ischemia, the ventromedial region being left intact. In spite of the depletion of pyramidal cells in the CA1 region of the hippocampus, both (/sup 3/H)muscimol and (/sup 3/H)flunitrazepam binding sites were preserved 27 days after ischemia. Since our previous study revealed that adenosine A1 binding sites were depleted in the CA1 subfield of the hippocampus after ischemia correlating with neuronal damage, GABAA and benzodiazepine receptors may not be distributed predominantly on the pyramidal cells in the CA1 region.

Onodera, H.; Sato, G.; Kogure, K.



Role of medullary GABA signal transduction on parasympathetic reflex vasodilatation in the lower lip.  


In the orofacial area, noxious stimulation of the orofacial structure in the trigeminal region evokes parasympathetic reflex vasodilatation, which occurs via the trigeminal spinal nucleus (Vsp) and the inferior/superior salivatory nucleus (ISN/SSN). However, the neurotransmitter involved in the inhibitory synaptic inputs within these nuclei has never been described. This parasympathetic reflex vasodilatation is suppressed by GABAergic action of volatile anesthetics, such as isoflurane, sevoflurane, and halothane, suggesting that medullary GABAergic mechanism exerts its inhibitory effect on the parasympathetic reflex via an activation of GABA receptors. The aim of the present study was to determine the role of GABA(A) and GABA(B) receptors in the Vsp and the ISN in regulating the lingual nerve (LN)-evoked parasympathetic reflex vasodilatation in the lower lip. Under urethane anesthesia (1g/kg), change in lower lip blood flow elicited by electrical stimulation of the LN was recorded in cervically vago-sympathectomized rats. Microinjection of GABA (10 ?M; 0.3 ?l/site) into the Vsp or the ISN significantly and reversibly attenuated the LN-evoked parasympathetic reflex vasodilatation. Microinjection of the GABA(A) receptor-selective agonist muscimol (100 ?M; 0.3 ?l/site) or the GABA(B) receptor-selective agonist baclofen (100 ?M; 0.3 ?l/site) into the Vsp or the ISN significantly and irreversibly reduced this reflex vasodilatation, and these effects were attenuated by pretreatment with microinjection of each receptor-selective antagonists [GABA(A) receptor selective antagonist bicuculline methiodide (1mM; 0.3 ?l/site) or GABA(B) receptor selective antagonist CGP-35348 (1mM; 0.3 ?l/site)] into the Vsp or the ISN. Microinjection of these antagonists alone into the Vsp or the ISN had no significant effect on this reflex vasodilatation. In addition, microinjection (0.3 ?l/site) of the mixture of muscimol (100 ?M) and baclofen (100 ?M) into the Vsp or the ISN also significantly reduced this reflex vasodilatation. These results suggest that medullary GABA signal transduction inhibits the parasympathetic reflex vasodilatation in the rat lower lip via GABA(A) and GABA(B) receptors in the Vsp and the ISN. PMID:22226507

Kawakami, So; Izumi, Hiroshi; Masaki, Eiji; Kuchiiwa, Satoshi; Mizuta, Kentaro



Identification of Significant Association and Gene-Gene Interaction of GABA Receptor Subunit Genes in Autism  

PubMed Central

Autism is a common neurodevelopmental disorder with a significant genetic component. Existing research suggests that multiple genes contribute to autism and that epigenetic effects or gene-gene interactions are likely contributors to autism risk. However, these effects have not yet been identified. Gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the adult brain, has been implicated in autism etiology. Fourteen known autosomal GABA receptor subunit genes were studied to look for the genes associated with autism and their possible interactions. Single-nucleotide polymorphisms (SNPs) were screened in the following genes: GABRG1, GABRA2, GABRA4, and GABRB1 on chromosome 4p12; GABRB2, GABRA6, GABRA1, GABRG2, and GABRP on 5q34-q35.1; GABRR1 and GABRR2 on 6q15; and GABRA5, GABRB3, and GABRG3 on 15q12. Intronic and/or silent mutation SNPs within each gene were analyzed in 470 white families with autism. Initially, SNPs were used in a family-based study for allelic association analysis—with the pedigree disequilibrium test and the family-based association test—and for genotypic and haplotypic association analysis—with the genotype-pedigree disequilibrium test (geno-PDT), the association in the presence of linkage (APL) test, and the haplotype family-based association test. Next, with the use of five refined independent marker sets, extended multifactor-dimensionality reduction (EMDR) analysis was employed to identify the models with locus joint effects, and interaction was further verified by conditional logistic regression. Significant allelic association was found for markers RS1912960 (in GABRA4; P = .01) and HCV9866022 (in GABRR2; P = .04). The geno-PDT found significant genotypic association for HCV8262334 (in GABRA2), RS1912960 and RS2280073 (in GABRA4), and RS2617503 and RS12187676 (in GABRB2). Consistent with the allelic and genotypic association results, EMDR confirmed the main effect at RS1912960 (in GABRA4). EMDR also identified a significant two-locus gene-gene effect model involving RS1912960 in GABRA4 and RS2351299 in GABRB1. Further support for this two-locus model came from both the multilocus geno-PDT and the APL test, which indicated a common genotype and haplotype combination positively associated with disease. Finally, these results were also consistent with the results from the conditional logistic regression, which confirmed the interaction between GABRA4 and GABRB1 (odds ratio = 2.9 for interaction term; P = .002). Through the convergence of all analyses, we conclude that GABRA4 is involved in the etiology of autism and potentially increases autism risk through interaction with GABRB1. These results support the hypothesis that GABA receptor subunit genes are involved in autism, most likely via complex gene-gene interactions. PMID:16080114

Ma, D. Q.; Whitehead, P. L.; Menold, M. M.; Martin, E. R.; Ashley-Koch, A. E.; Mei, H.; Ritchie, M. D.; DeLong, G. R.; Abramson, R. K.; Wright, H. H.; Cuccaro, M. L.; Hussman, J. P.; Gilbert, J. R.; Pericak-Vance, M. A.



The Role of GABA and Anxiety in the Reconsolidation of Conditioned Fear  

Microsoft Academic Search

The current study examined the effects of systemic administration of a GABA agonist [midazolam (MDZ)] and a GABA antagonist (bicuculline) on fear responding after brief CS exposure, a procedure thought to involve memory reconsolidation. Using a contextual fear-conditioning paradigm, rats were initially given two context-shock training trials, followed 24 hrs later by a 90-s context exposure (reactivation), and 24 hrs

Shirley Zhang; Jacquelyn Cranney



Zinc Enhances Ionic Currents Induced in Skate Muller (Glial) Cells by the Inhibitory Neurotransmitter GABA  

Microsoft Academic Search

We describe here a novel effect of zinc on GABA receptors of glial cells in the skate retina. The GABA-induced currents of skate Muller cells, the radial glia of the retina, are mediated by activation of GABAA receptors (GABAARs). In other parts of the nervous system, GABAA-mediated currents are inhibited by zinc. However, in isolated, voltage-clamped Muller cells, coapplication of

Haohua Qian; Robert Paul Malchow; Richard L. Chappell; Harris Ripps



Effect of THIP and SL 76002, two clinically experimented GABA-mimetic compounds, on anterior pituitary GABA receptors and prolactin secretion in the rat  

SciTech Connect

In the present study, the ability of three direct GABA agonists, muscimol, THIP and SL 76002 to displace /sup 3/H-GABA binding from anterior pituitary and medio-basal hypothalamus membranes was evaluated. Further, the effect of both THIP and SL 76002 on baseline prolactin levels or after stimulation of hormone release with haloperidol has been also studied. Either muscimol, THIP or SL 76002 have shown to posses 7-, 7- and 3-fold higher affinity, respectively, for the central nervous system than for the anterior pituitary /sup 3/H-GABA binding sites. Moreover, THIP and SL 76002 have demonstrated to be respectively, 25- and 1000- fold less potent than muscimol in inhibiting /sup 3/H- GABA binding at the level of the anterior pituitary and about 25- and 2700-fold less potent at the level of the medio-basal hypothalamus. Under basal conditions, either THIP or SL 76002 were ineffective to reduce prolactin release. However, after stimulation of prolactin secretion through blockade of the dopaminergic neurotransmission with haloperidol (0.1 mg/kg), both THIP (10 mg/kg) and SL 76002 (200 mg/kg) significantly counteracted the neuroleptic-induced prolactin rise with a potency which is in line with their ability to inhibit /sup 3/H-GABA binding in the anterior pituitary. The present results indicate that both compounds inhibit prolactin release under specific experimental situations probably through a GABAergic mechanism. In view of the endocrine effects of these GABA-mimetic compounds, the possibility arises for an application of these type of drugs in clinical neuroendocrinology. 35 references, 3 figures, 2 tables.

Apud, J.A.; Masotto, C.; Racagni, G.



Acupuncture improves locomotor function by enhancing GABA receptor expression in transient focal cerebral ischemia rats.  


Stroke is the major cause of long-term disability among adults. Recent studies have found that GABAergic inhibitory neurotransmission plays a vital role in ameliorate locomotor damage after ischemic injury. Acupuncture has been widely used to improve locomotor function. However, the underlying mechanisms remain unclear. The present study is designed to investigate whether GABA and GABA receptors are involved in the mechanism underlying acupuncture treatment in rats with middle cerebral artery occlusion (MCAO). One week after acupuncture at JiaJi acupoint, the locomotor function and infarct volumes were tested. Then level of GABA and the expressions of GABAA?2 and GABABR2 were assessed by high-performance liquid chromatography, immunofluorescence and immunohistochemistry, respectively. Compared with normal group, GABAA?2 and GABABR2 expressions were decreased in striatum and spinal cord of the MCAO group. After acupuncture, the expressions of the two receptors were increased, but levels of GABA and trafficking protein, kinesin binding 1 (TRAK1), which plays a role in the intracellular transport of GABA receptors, were unchanged. The present study suggests that acupuncture could reverse locomotor function by modulating the expressions of GABA receptors in MCAO rats. PMID:25556683

Xu, Qian; Yang, Jing-Wen; Cao, Yan; Zhang, Li-Wen; Zeng, Xiang-Hong; Li, Fang; Du, Si-Qi; Wang, Lin-Peng; Liu, Cun-Zhi



Resting GABA and glutamate concentrations do not predict visual gamma frequency or amplitude  

PubMed Central

Gamma band oscillations arise in neuronal networks of interconnected GABAergic interneurons and excitatory pyramidal cells. A previous study found a correlation between visual gamma peak frequency, as measured with magnetoencephalography, and resting GABA levels, as measured with magnetic resonance spectroscopy (MRS), in 12 healthy volunteers. If true, this would allow studies in clinical populations testing modulation of this relationship, but this finding has not been replicated. We addressed this important question by measuring gamma oscillations and GABA, as well as glutamate, in 50 healthy volunteers. Visual gamma activity was evoked using an established gratings paradigm, and we applied a beamformer spatial filtering technique to extract source-reconstructed gamma peak frequency and amplitude from the occipital lobe. We determined gamma peak frequency and amplitude from the location with maximal activation and from the location of the MRS voxel to assess the relationship of GABA with gamma. Gamma peak frequency was estimated from the highest value of the raw spectra and by a Gaussian fit to the spectra. MRS data were acquired from occipital cortex. We did not replicate the previously found correlation between gamma peak frequency and GABA concentration. Calculation of a Bayes factor provided strong evidence in favor of the null hypothesis. We also did not find a correlation between gamma activity and glutamate or between gamma and the ratio of GABA/glutamate. Our results suggest that cortical gamma oscillations do not have a consistent, demonstrable relationship to excitatory/inhibitory network activity as proxied by MRS measurements of GABA and glutamate. PMID:24927588

Cousijn, Helena; Haegens, Saskia; Wallis, George; Near, Jamie; Stokes, Mark G.; Harrison, Paul J.; Nobre, Anna C.



Synthesis of nylon 4 from gamma-aminobutyrate (GABA) produced by recombinant Escherichia coli.  


In this study, we developed recombinant Escherichia coli strains expressing Lactococcus lactis subsp. lactis Il1403 glutamate decarboxylase (GadB) for the production of GABA from glutamate monosodium salt (MSG). Syntheses of GABA from MSG were examined by employing recombinant E. coli XL1-Blue as a whole cell biocatalyst in buffer solution. By increasing the concentration of E. coli XL1-Blue expressing GadB from the OD??? of 2-10, the concentration and conversion yield of GABA produced from 10 g/L of MSG could be increased from 4.3 to 4.8 g/L and from 70 to 78 %, respectively. Furthermore, E. coli XL1-Blue expressing GadB highly concentrated to the OD??? of 100 produced 76.2 g/L of GABA from 200 g/L of MSG with 62.4 % of GABA yield. Finally, nylon 4 could be synthesized by the bulk polymerization using 2-pyrrolidone that was prepared from microbially synthesized GABA by the reaction with Al?O? as catalyst in toluene with the yield of 96 %. PMID:23010721

Park, Si Jae; Kim, Eun Young; Noh, Won; Oh, Young Hoon; Kim, Hye Young; Song, Bong Keun; Cho, Kwang Myung; Hong, Soon Ho; Lee, Seung Hwan; Jegal, Jonggeon



Functional reconstitution of the bovine brain GABA sub A receptor from solubilized components  

SciTech Connect

The GABA{sub A}/benzodiazepine receptor has been solubilized from membrane preparations of bovine cerebral cortex and has been reconstituted, in a functionally active form, into phospholipid vesicles. In preliminary experiments, the receptor was labeled with the photoactive benzodiazepine ({sup 3}H)flunitrazepam prior to solubilization. A peptide of apparent molecular weight 53,500 was specifically labeled by this method, and this was used as a marker for the receptor during the reconstitution procedures. The labeled protein was solubilized with approximately 40% efficiency by 1% {beta}-octyl glucoside. Reconstitution was achieved by mixing the solubilized proteins with a 4:1 mixture of soybean asolectin and bovine brain phospholipids, followed by chromatography on Sephadex G-50-80 to remove detergent. The incorporation of the GABA{sub A} receptor into membrane vesicles has been verified by sucrose gradient centrifugation in which the ({sup 3}H)-flunitrazepam-labeled peptide comigrated with ({sup 14}C)phosphatidylcholine used as a lipid marker. Vesicles prepared without labeled markers retained the ability to bind both ({sup 3}H)flunitrazepam and the GABA analogue ({sup 3}H)muscimol. A novel fluorescence technique has been used to measure chloride transport mediated by the GABA{sub A} receptor in reconstituted vesicles. Flux was also blocked by pretreatment with the competitive GABA{sub A} receptor blocker bicuculline or with the noncompetitive GABA{sub A} receptor antagonist picrotoxin.

Dunn, S.M.J.; Martin, C.R.; Agey, M.W.; Miyazaki, R. (Univ. of Iowa, Iowa City (USA))



Modulation of ionotropic GABA receptors by 6-methoxyflavanone and 6-methoxyflavone.  


We evaluated the effects of 6-methoxyflavanone and 6-methoxyflavone on wild-type ?1/?2?2?2L GABAA and ?1 GABAC receptors and on mutant ?1I307S, ?1W328 M, ?1I307S/W328 M GABAC receptors expressed in Xenopus oocytes using two-electrode voltage clamp and radioligand binding. 6-Methoxyflavanone and 6-methoxyflavone act as a flumazenil-insensitive positive allosteric modulator of GABA responses at human recombinant ?1?2?2L and ?2?2?2L GABAA receptors. However, unlike 6-methoxyflavone, 6-methoxyflavanone was relatively inactive at ?1?2 GABAA receptors. 6-Methoxyflavanone inhibited [(3)H]-flunitrazepam binding to rat brain membranes. Both flavonoids were found to be inactive as modulators at ?1, ?1I307S and ?1W328 M GABA receptors but acted as positive allosteric modulators of GABA at the benzodiazepine sensitive ?1I307S/W328 M GABA receptors. This double mutant retains ?1 properties of being insensitive to bicuculline and antagonised by TPMPA and THIP. Additionally, 6-methoxyflavanone was also a partial agonist at ?1W328 M GABA receptors. The relative inactivity of 6-methoxyflavanone at ?1?2 GABAA receptors and it's partial agonist action at ?1W328 M GABA receptors suggest that it exhibits a unique profile not matched by other flavonoids. PMID:24078264

Hall, Belinda J; Karim, Nasiara; Chebib, Mary; Johnston, Graham A R; Hanrahan, Jane R



Inhibition of Activity of GABA Transporter GAT1 by ?-Opioid Receptor.  


Analgesia is a well-documented effect of acupuncture. A critical role in pain sensation plays the nervous system, including the GABAergic system and opioid receptor (OR) activation. Here we investigated regulation of GABA transporter GAT1 by ?OR in rats and in Xenopus oocytes. Synaptosomes of brain from rats chronically exposed to opiates exhibited reduced GABA uptake, indicating that GABA transport might be regulated by opioid receptors. For further investigation we have expressed GAT1 of mouse brain together with mouse ?OR and ?OR in Xenopus oocytes. The function of GAT1 was analyzed in terms of Na(+)-dependent [(3)H]GABA uptake as well as GAT1-mediated currents. Coexpression of ?OR led to reduced number of fully functional GAT1 transporters, reduced substrate translocation, and GAT1-mediated current. Activation of ?OR further reduced the rate of GABA uptake as well as GAT1-mediated current. Coexpression of ?OR, as well as ?OR activation, affected neither the number of transporters, nor rate of GABA uptake, nor GAT1-mediated current. Inhibition of GAT1-mediated current by activation of ?OR was confirmed in whole-cell patch-clamp experiments on rat brain slices of periaqueductal gray. We conclude that inhibition of GAT1 function will strengthen the inhibitory action of the GABAergic system and hence may contribute to acupuncture-induced analgesia. PMID:23365600

Pu, Lu; Xu, Nanjie; Xia, Peng; Gu, Quanbao; Ren, Shuanglai; Fucke, Thomas; Pei, Gang; Schwarz, Wolfgang



Resting GABA and glutamate concentrations do not predict visual gamma frequency or amplitude.  


Gamma band oscillations arise in neuronal networks of interconnected GABAergic interneurons and excitatory pyramidal cells. A previous study found a correlation between visual gamma peak frequency, as measured with magnetoencephalography, and resting GABA levels, as measured with magnetic resonance spectroscopy (MRS), in 12 healthy volunteers. If true, this would allow studies in clinical populations testing modulation of this relationship, but this finding has not been replicated. We addressed this important question by measuring gamma oscillations and GABA, as well as glutamate, in 50 healthy volunteers. Visual gamma activity was evoked using an established gratings paradigm, and we applied a beamformer spatial filtering technique to extract source-reconstructed gamma peak frequency and amplitude from the occipital lobe. We determined gamma peak frequency and amplitude from the location with maximal activation and from the location of the MRS voxel to assess the relationship of GABA with gamma. Gamma peak frequency was estimated from the highest value of the raw spectra and by a Gaussian fit to the spectra. MRS data were acquired from occipital cortex. We did not replicate the previously found correlation between gamma peak frequency and GABA concentration. Calculation of a Bayes factor provided strong evidence in favor of the null hypothesis. We also did not find a correlation between gamma activity and glutamate or between gamma and the ratio of GABA/glutamate. Our results suggest that cortical gamma oscillations do not have a consistent, demonstrable relationship to excitatory/inhibitory network activity as proxied by MRS measurements of GABA and glutamate. PMID:24927588

Cousijn, Helena; Haegens, Saskia; Wallis, George; Near, Jamie; Stokes, Mark G; Harrison, Paul J; Nobre, Anna C



Fast Synaptic Inhibition in Spinal Sensory Processing and Pain Control  

PubMed Central

The two amino acids ?-amino butyric acid (GABA) and glycine mediate fast inhibitory neurotransmission in different CNS areas and serve pivotal roles in the spinal sensory processing. Under healthy conditions, they limit the excitability of spinal terminals of primary sensory nerve fibers and of intrinsic dorsal horn neurons through pre- and postsynaptic mechanisms, and thereby facilitate the spatial and temporal discrimination of sensory stimuli. Removal of fast inhibition not only reduces the fidelity of normal sensory processing but also provokes symptoms very much reminiscent of pathological and chronic pain syndromes. This review summarizes our knowledge of the molecular bases of spinal inhibitory neurotransmission and its organization in dorsal horn sensory circuits. Particular emphasis is placed on the role and mechanisms of spinal inhibitory malfunction in inflammatory and neuropathic chronic pain syndromes. PMID:22298656

Zeilhofer, Hanns Ulrich; Wildner, Hendrik; Yevenes, Gonzalo E.



Phosphorylation factors control neurotransmitter and neuromodulator actions at the gamma-aminobutyric acid type A receptor.  


Whole-cell and patch-voltage clamp experiments were carried out on cultured chick spinal cord neurons to investigate the dependence of gamma-aminobutyric acid (GABA)A receptor function on intracellular phosphorylation factors. Without ATP in the intracellular solution, repeated application of 30 microM GABA results in a progressive decline (run-down) of the currents evoked by GABA in standard whole-cell recordings but not when the nystatin-perforated patch method is used. Run-down is also observed in outside-out excised patch recordings, indicating that any enzymatic factors required for run-down must be closely associated with the plasma membrane. Run-down is associated with decreases in both the maximum GABA-induced current and the GABA EC50. Inclusion of magnesium adenosine-5'-O-(3-thio)triphosphate in the intracellular buffer prevents the decline in the maximum GABA response but the GABA EC50 still decreases, resulting in a "run-up" of the response at low (3 microM) GABA concentrations. Run-down is use dependent, requiring repeated activation of the GABAA receptor by high (30 microM) GABA concentrations. However, use-independent run-down can be induced by the inclusion of alkaline phosphatase in the intracellular buffer. The response to 3 microM GABA does not normally run down, but run-down is observed when the response to 3 microM GABA is potentiated with pentobarbital or allopregnanolone, suggesting that run-down is consequence of GABA receptor activation and/or desensitization. Run-down of the potentiated GABA response can be prevented by addition of magnesium adenosine-5'-O-(3-thio)triphosphate to the intracellular solution. Strikingly, run-down results in a significant decrease in the potentiating effects of positive modulators, whereas the inhibitory effects of negative modulators such as pregnenolone sulfate and ZnCl2 are unchanged. The results demonstrate that phosphorylation factors have the capacity to control GABAA receptor pharmacology, affecting the potency and efficacy of GABA, the kinetics of GABAA receptor desensitization, and the sensitivity of the receptor to modulators such as steroids, benzodiazepines, and barbiturates. PMID:7935336

Gyenes, M; Wang, Q; Gibbs, T T; Farb, D H



Trichloroethanol potentiation of gamma-aminobutyric acid-activated chloride current in mouse hippocampal neurones.  

PubMed Central

1. The action of 2,2,2-trichloroethanol on gamma-aminobutyric acid (GABA)-activated Cl- current was studied in mouse hippocampal neurones in tissue culture by use of whole-cell patch-clamp recording. 2. Trichloroethanol increased the amplitude of currents activated by 1 microM GABA or 0.1 microM muscimol. Trichloroethanol, 1-25 mM, potentiated current activated by 1 microM GABA in a concentration-dependent manner with an EC50 of 3.0 +/- 1.4 mM and a maximal response (Emax) of 576 +/- 72% of control. 3. Trichloroethanol potentiated currents activated by GABA concentrations < 10 microM, but did not increase the amplitude of currents activated by concentrations of GABA > or = 10 microM. Despite marked potentiation of currents activated by low concentrations of GABA, trichloroethanol did not significantly alter the EC50, slope, or Emax of the GABA concentration-response curve. 4. Trichloroethanol, 5 mM, potentiated GABA-activated current in neurones in which ethanol, 10-500 mM, did not. The effect of trichloroethanol was not altered by the putative ethanol antagonist, Ro 15-4513. Trichloroethanol did not potentiate currents activated by pentobarbitone. 5. In the absence of exogenous GABA, trichloroethanol at concentrations > or = 2.5 mM activated a current that appeared to be carried by Cl- as its reversal potential changed with changes in the Cl- gradient and as it was inhibited by the GABAA antagonists, bicuculline methiodide and picrotoxin. 6. Since trichloroethanol is thought to be the active metabolite of chloral hydrate and other chloral derivative anaesthetics, potentiation of the GABA-activated current in central nervous system neurones by trichloroethanol may contribute to the sedative/hypnotic effects of these agents. PMID:7834208

Peoples, R W; Weight, F F



Metabotropic glutamate mGlu5 receptor-mediated modulation of the ventral striopallidal GABA pathway in rats. Interactions with adenosine A 2A and dopamine D 2 receptors  

Microsoft Academic Search

Interactions between subtypes of dopamine, glutamate and adenosine receptors seem to play an important integrative role in the function of striatal gamma-aminobutyric acid (GABA)ergic efferent neurons. Recent behavioral and biochemical studies suggest the existence of specific interactions between adenosine A2A receptors (A2AR), dopamine D2 receptors (D2R) and the group I metabotropic mGlu5 receptors (mGlu5R) in the dorsal striatum. The dual-probe

Zaida D??az-Cabiale; Meritxell Vivó; Alberto Del Arco; William T. O'Connor; Michael K. Harte; Christa E. Müller; Emili Mart??nez; Patrizia Popoli; Kjell Fuxe; Sergi Ferré



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


The developing brain is talkative but its language is not that of the adult. Most if not all voltage and transmitter-gated ionic currents follow a developmental sequence and network-driven patterns differ in immature and adult brains. This is best illustrated in studies engaged almost three decades ago in which we observed elevated intracellular chloride (Cl(-))i levels and excitatory GABA early during development and a perinatal excitatory/inhibitory shift. This sequence is observed in a wide range of brain structures and animal species suggesting that it has been conserved throughout evolution. It is mediated primarily by a developmentally regulated expression of the NKCC1 and KCC2 chloride importer and exporter respectively. The GABAergic depolarization acts in synergy with N-methyl-d-aspartate (NMDA) receptor-mediated and voltage-gated calcium currents to enhance intracellular calcium exerting trophic effects on neuritic growth, migration and synapse formation. These sequences can be deviated in utero by genetic or environmental insults leading to a persistence of immature features in the adult brain. This "neuroarcheology" concept paves the way to novel therapeutic perspectives based on the use of drugs that block immature but not adult currents. This is illustrated notably with the return to immature high levels of chloride and excitatory actions of GABA observed in many pathological conditions. This is due to the fact that in the immature brain a down regulation of KCC2 and an up regulation of NKCC1 are seen. Here, I present a personal history of how an unexpected observation led to novel concepts in developmental neurobiology and putative treatments of autism and other developmental disorders. Being a personal account, this review is neither exhaustive nor provides an update of this topic with all the studies that have contributed to this evolution. We all rely on previous inventors to allow science to advance. Here, I present a personal summary of this topic primarily to illustrate why we often fail to comprehend the implications of our own observations. They remind us - and policy deciders - why Science cannot be programed, requiring time, and risky investigations that raise interesting questions before being translated from bench to bed. Discoveries are always on sideways, never on highways. PMID:25168736

Ben-Ari, Y



Structures of a ?-aminobutyrate (GABA) transaminase from the s-triazine-degrading organism Arthrobacter aurescens TC1 in complex with PLP and with its external aldimine PLP–GABA adduct  

PubMed Central

Two complex structures of the ?-aminobutyrate (GABA) transaminase A1R958 from Arthrobacter aurescens TC1 are presented. The first, determined to a resolution of 2.80?Å, features the internal aldimine formed by reaction between the ?-amino group of Lys295 and the cofactor pyridoxal phosphate (PLP); the second, determined to a resolution of 2.75?Å, features the external aldimine adduct formed between PLP and GABA in the first half-reaction. This is the first structure of a microbial GABA transaminase in complex with its natural external aldimine and reveals the molecular determinants of GABA binding in this enzyme. PMID:23027742

Bruce, Heather; Nguyen Tuan, Anh; Mangas Sánchez, Juan; Leese, Charlotte; Hopwood, Jennifer; Hyde, Ralph; Hart, Sam; Turkenburg, Johan P.; Grogan, Gideon



Gamma-Aminobutyric Acid Concentration is Reduced in Visual Cortex in Schizophrenia and Correlates with Orientation-Specific Surround Suppression  

PubMed Central

The neural mechanisms underlying cognitive deficits in schizophrenia remain largely unknown. The gamma-aminobutyric acid (GABA) hypothesis proposes that reduced neuronal GABA concentration and neurotransmission results in cognitive impairments in schizophrenia. However, few in vivo studies ha