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1

Pharmacologic characteristics of excitatory gamma-amino-butyric acid (GABA) receptors in a snail neuron.  

PubMed

1. The pharmacologic characteristics of excitatory gamma-aminobutyric acid (GABA) receptors, termed muscimol II type GABA receptors, found in a giant neuron type, v-LCDN (ventral-left cerebral distinct neuron), of an African giant snail (Achatina fulica Férussac), were studied using the mammalian GABA receptor agonists, antagonists and synergists and GABA uptake inhibitor using the voltage clamp technique. 2. GABA and its agonists, ejected by brief pressure, produced an inward current (Iin) of the following order of potency: trans-t-aminocrotonic acid (TACA) > GABA > muscimol > isoguvacine > 5-aminopentanoic acid and cis-4-aminocrotonic acid (CACA). (+/-)-Baclofen and 3-aminopropylphosphonic acid (APPA) were ineffective. The Iin values produced by GABA, TACA, isoguvacine and CACA were stable for at least 60 min, whereas the Iin induced by muscimol was not. 3. According to the dose-response curves of GABA, TACA, isoguvacine and CACA, measured by the varied pressure duration method, the ED50 value of CACA was larger than those of the other compounds, and Emax of TACA was larger than that of GABA, whereas Emax values of isoguvacine and CACA were smaller. 4. The perfusion of beta-alanine, pentobarbital and 5-aminopentanoic acid inhibited the Iin induced by GABA, whereas (-)-bicuculline, pitrazepin, diazepam and 2-hydroxysaclofen had no effect. 5. From the effects of beta-alanine on the dose-response curves of GABA, measured by the varied pressure duration method, beta-alanine competitively inhibited the Iin caused by GABA. According to the effects of pentobarbital on the dose-response curves of GABA, this drug noncompetitively inhibited the Iin using the varied pressure duration method, and partly competitively and partly noncompetitively using the Y-tube method. The effects of 5-aminopentanoic acid on the dose-response curves of GABA indicated that this drug noncompetitively inhibited the Iin using the varied pressure duration method, and partly noncompetitively and partly uncompetitively using the Y-tube method. 6. The pharmacologic features of the Achatina muscimol II type GABA receptors were similar to those of mammalian GABAC (GABAp1) receptors, except for the effects of pentobarbital. PMID:9112076

Zhang, W; Han, X Y; Wong, S M; Takeuchi, H

1997-01-01

2

EFFECT OF LEAD ON GAMMA AMINO BUTYRIC ACID SYNTHESIS  

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...

3

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.

2012-01-01

4

Gamma amino butyric acid (GABA) immunoreactivity in the vestibular nuclei of normal and unilateral vestibular neurectomized cats.  

PubMed

Recent neurochemical investigations of the central vestibular pathways have demonstrated that several neurotransmitters are involved in various operations required for stabilizing posture and gaze. Neurons of the vestibular nuclei (VN) receive GABAergic inhibitory afferents, and GABAergic neurons distributed throughout the vestibular complex are implicated in inhibitory vestibulo-ocular and vestibulo-spinal pathways. The aim of this study was to analyse the modifications of GABA immunoreactivity (GABA-ir) in the cat VN after unilateral vestibular neurectomy (UVN). Indeed, compensation of vestibular deficits is a good model for studying adult central nervous system (CNS) plasticity and the GABAergic system is involved in CNS plasticity. We studied GABA-ir by using a purified polyclonal antibody raised against GABA. Light microscopic preparations of thin (20 microm) sections of cat VN were used to quantify GABA-ir by an image analysing system measuring GABA-positive punctate structures and the number of GABA-positive neurons. Both the lesioned and intact sides were analysed in three populations of UVN cats killed at different times after injury (1 week, 3 weeks and 1 year). These data were compared to those collected in normal unlesioned and sham-operated cats. Results showed a spatial distribution of GABA-ir in the control cats that confirmed previous studies. GABA-ir neurons, fibres and nerve terminals were scattered in all parts of the VN. A higher concentration of GABA-positive neurons (small cells) was detected in the medial and inferior VN (MVN and IVN) and in the dorsal part of the lateral VN (LVNd). A higher level of GABA-positive punctate structures was observed in the MVN and in the prepositus hypoglossi (PH) nucleus. Lesion-induced changes were found at each survival time. One week after injury the number of GABA-positive neurons was significantly increased in the MVN, the IVN and the dorsal part of the LVN on the lesioned side and in the ventral part of the LVN on the intact side. One year later a bilateral increase in GABA-positive neurons was detected in the MVN whilst a bilateral decrease was observed in both the SVN and the ventral part of the LVN. Changes in the GABA-staining varicosities did not strictly coincide with the distribution of GABA-ir cells, suggesting that GABA-ir fibres and nerve terminals were also modified. One week and later after injury, higher GABA-staining varicosities were seen unilaterally in the ipsilateral MVN. In contrast, bilateral increases (in PH) and bilateral decreases (in SVN and the ventral part of the LVN) were recorded in the nearly (3 weeks) or fully (1 year) compensated cats. At this stage GABA-staining varicosities were significantly increased in the lesioned side of the MVN. These findings demonstrate the reorganization of the GABAergic system in the VN and its possible role in recovery process after UVN in the cat. The changes seen during the acute stage could be causally related to the VN neuron deafferentation, contributing to the static vestibular deficits. Those found in the compensated cats would be more functionally implicated in the dynamic aspects of vestibular compensation. PMID:11454029

Tighilet, B; Lacour, M

2001-06-01

5

Production of ?-Amino Butyric Acid in Tea Leaves wit Treatment of Lactic Acid Bacteria  

NASA Astrophysics Data System (ADS)

Lactic acid bacteria was searched for producing termented tea that contained a lot of ?-amino butyric acid(GABA). Also examined were the growth condition, GABA production and changes in catechin contents in the tea leaves. Lactobacillus brevis L12 was found to be suitable for the production of fermented tea since it gave as much GABA as gabaron tea when tea leaves being suspended with water at 10% and incubated for 4 days at 25°C. The amount of GABA produced was more than calculated based upon the content of glutamic acid in tea leaves. It is probable to assume that glutamate derived from glutamine and theanine is converted into GABA.

Watanabe, Yuko; Hayakawa, Kiyoshi; Ueno, Hiroshi

6

Gamma amino butyric acid accumulation in medicinal plants without stress  

PubMed Central

Introduction: Gamma amino butyric acid (GABA) is an important ubiquitous four carbon nonprotein amino acid with an amino group attached to gamma carbon instead of beta carbon. It exists in different organisms including bacteria, plants, and animals and plays a crucial role in humans by regulating neuronal excitability throughout the nervous system. It is directly responsible for the regulation of muscle tone and also effective in lowering stress, blood pressure, and hypertension. Aim and Objective: The aim of the study was to develop the fingerprint profile of selected medicinally and economically important plants having central nervous system (CNS) activity and to determine the quantity of GABA in the selected plants grown under natural conditions without any added stress. Materials and Methods: The high-performance thin layer chromatography analysis was performed on precoated silica gel plate 60F–254 plate (20 cm × 10 cm) in the form of bands with width 8 mm using Hamilton syringe (100 ?l) using n-butanol, acetic acid, and water in the proportion 5:2:2 as mobile phase in a CAMAG chamber which was previously saturated for 30 min. CAMAG TLC scanner 3 was used for the densitometric scanning at 550 nm. Specific marker compounds were used for the quantification. Results and Conclusion: Among the screened medicinal plants, Zingiber officinale and Solanum torvum were found to have GABA. The percentage of GABA present in Z. officinale and S. torvum were found to be 0.0114% and 0.0119%, respectively. The present work confirmed that among the selected CNS active medicinal plants, only two plants contain GABA. We found a negative correlation with plant having CNS activity and accumulation of GABA. The GABA shunt is a conserved pathway in eukaryotes and prokaryotes but, although the role of GABA as a neurotransmitter in mammals is clearly established, its role in plants is still vague.

Anju, P.; Moothedath, Ismail; Rema Shree, Azhimala Bhaskaranpillai

2014-01-01

7

Immediate Post-Reminder Injection of Gamma-Amino Butyric Acid (GABA) Agonist Midazolam Attenuates Reactivation of Forgotten Fear in the Infant Rat  

Microsoft Academic Search

J. H. Kim, G. McNally, and R. Richardson (2006) reported that pretest injection of FG7142, a GABA inverse agonist, alleviated infantile amnesia in rats. From this, it was concluded that GABAergic neurotransmission is involved in the forgetting seen in the developing rat. The present study extends that finding by examining the role of GABA in the reactivation of a forgotten

Jee Hyun Kim; Rick Richardson

2007-01-01

8

Gabapentin inhibits ?-Amino butyric acid release in the locus coeruleus but not in the spinal dorsal horn after peripheral nerve injury in rats  

PubMed Central

Background Gabapentin reduces acute postoperative and chronic neuropathic pain, but its sites and mechanisms of action are unclear. Based on previous electrophysiologic studies, we tested whether gabapentin reduced ?-Amino butyric acid (GABA) release in the locus coeruleus (LC), a major site of descending inhibition, rather than in the spinal cord. Methods Male Sprague-Dawley rats with or without L5-L6 spinal nerve ligation (SNL) were used. Immunostaining for glutamic acid decarboxylase and GABA release in synaptosomes and microdialysates were examined in the LC and spinal dorsal horn. Results Basal GABA release and expression of glutamic acid decarboxylase increased in the LC but decreased in the spinal dorsal horn following SNL. In microdialysates from the LC, intravenously administered gabapentin decreased extracellular GABA concentration in normal and SNL rats. In synaptosomes prepared from the LC, gabapentin and other ?2? ligands inhibited KCl-evoked GABA release in normal and SNL rats. In microdialysates from the spinal dorsal horn, intravenous gabapentin did not alter GABA concentrations in normal rats but slightly increased them in SNL rats. In synaptosomes from the spinal dorsal horn, neither gabapentin nor other ?2? ligands affected KCl-evoked GABA release in normal and SNL rats. Discussion These results suggest that peripheral nerve injury induces plasticity of GABAergic neurons differently in the LC and spinal dorsal horn, and that gabapentin reduces pre-synaptic GABA release in the LC but spinal dorsal horn. The present study supports the idea that gabapentin activates descending noradrenergic inhibition via disinhibition of LC neurons. PMID:22487864

Yoshizumi, Masaru; Parker, Renee A.; Eisenach, James C.; Hayashida, Ken-ichiro

2012-01-01

9

Effect of cyproheptadine, desmethylcyproheptadine, gamma-amino-butyric acid and sodium valproate on adrenocorticotrophin secretion by cultured pituitary tumour cells from three patients with Nelson's syndrome.  

PubMed

The effects of cyproheptadine, desmethylcyproheptadine, serotonin, gamma-amino-butyric acid (GABA) and sodium valproate were studied on ACTH secretion by cultured nonenzymatically dispersed pituitary tumour cells from three patients with Nelson's syndrome. Cyproheptadine (1-10 mumol/l) and desmethylcyproheptadine (1-10 mumol/l) suppressed ACTH secretion significantly (P less than 0.01), while serotonin (10 mumol/l) did not have a direct effect. Serotonin was also not able to reverse the (desmethyl)cyproheptadine-mediated inhibition of ACTH release. Sodium valproate and GABA did not exert a direct effect on hormone release by these cultured pituitary tumour cells. It is suggested that cyproheptadine-mediated inhibition of ACTH release in Nelson's syndrome might be effected by a direct non-serotonin-related effect on the pituitary tumour, while sodium valproate suppresses ACTH release by a suprahypophysial action. PMID:6300275

Lamberts, S W; Verleun, T; Bons, E G; Uitterlinden, P; Oosterom, R

1983-03-01

10

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

PubMed

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

2014-01-01

11

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

1999-01-01

12

[Intracellular concentration of phenylalanine, tyrosine and alpha-amino butyric acid in 13 homozygotes and 19 heterozygotes for phenylketonuria (PKU) compared with 26 normals (author's transl)].  

PubMed

Intracellular concentrations for phenylalanine, tyrosine, alpha-amino butyric acid and 7 other amino acids (glycine, alanine, valin, cystin, methionine, iso-leucin, leucin) were measured in lymphocytes of 13 homozygotes and 19 heterozygotes for phenylketonuria as well as in lymphocytes of 26 normals. Intracellular concentrations for phenylalanine, tyrosine and alpha-amino butyric acid were significantly higher in homo- and heterozygotes than in normals (p less than 0,001--p less than 0,01). For the other 7 amino acids there were no or only questionable differences. Between homo- and heterozygotes there was no difference in any of the amino acids. Intracellular phenylalanine: tyrosine ratio was essentially the same in all three groups of individuals. There was no correlation between intracellular phenylalanine above or below 10 nmol/10(6) cells and IQ in heterozygotes. The same is true for phenylalanine: tyrosine ratio greater or smaller than 1. In Homozygotes there was no correlation between intracellular phenylalanine and age -- to whom DQ/IQ is correlated. There was no significant difference in intracellular phenylalanine between homozygotes with blood levels above and below 908 mumol/l (15 mg/100 ml) at the time of blood sampling and no correlation between intra- and extra-cellular phenylalanine concentrations. Among the 26 normals there were only 2 with intracellular phenylalanine above 10 nmol/10(6) cells, both showing phenylalanine loading test curves suspicious for heterozygosity. The results are discussed and important functions of the cell wall supposed. An abnormal unknown intracellular metabolite being the real noxious agent could explain the incomparably different degree of brain dysfunction in individuals with equal though elevated intracellular phenylalanine concentrations i.e. homozygotes and heterozygotes for PKU. PMID:7194402

Thalhammer, O; Pollak, A; Lubec, G; Königshofer, H

1980-11-01

13

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...

14

Excitatory Sulfur-Containing Amino Acid-Induced Release of [ 3 H]GABA from Rat Olfactory Bulb  

Microsoft Academic Search

The effect of L-cysteine sulfinic acid (CSA) and L-homocysteic acid (HCA) on the release of tritiated ?-amino butyric acid ([3H]GABA), from the external plexiform layer (EPL) of the rat olfactory bulb, was compared with that of glutamate. These amino acids induced release of GABA was strongly inhibited by the glutamate uptake blocker, pyrrolidine-2,4-dicarboxylate (2,4,PDC) (50 µM), while it was not

E. H. Jaffe; Y. Garcia

1997-01-01

15

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

2013-01-01

16

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. PMID:25565970

Yoon, Bo-Eun; Lee, C. Justin

2014-01-01

17

Widespread expression of GABA A receptor subunits in peripheral tissues  

Microsoft Academic Search

The receptor subtypes involved in the physiological and pharmacological actions of ?-amino butyric acid (GABA) in peripheral and endocrine tissues are not clear. Information about the molecular characteristics of GABAA receptors in peripheral endocrine tissues is only available for the pancreas and the adrenal medulla. Using reverse transcription (RT) polymerase chain reaction (PCR), the widespread expression of GABAA receptors subunits

Mualla K Akinci; Peter R Schofield

1999-01-01

18

Metabotropic receptors for glutamate and GABA in pain  

Microsoft Academic Search

Glutamate and ?-amino butyric acid (GABA) are respectively two major excitatory and inhibitory neurotransmitters of the adult mammalian central nervous system. These neurotransmitters exert their action through two types of receptors: ionotropic and metabotropic receptors. While ionotropic receptors are ligand gated ion channels involved in fast synaptic transmission, metabotropic receptors belong to the superfamily of G-protein coupled receptors (GPCRs) and

Cyril Goudet; Valerio Magnaghi; Marc Landry; Frédéric Nagy; Robert W. Gereau IV; Jean-Philippe Pin

2009-01-01

19

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.

2014-01-01

20

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

Microsoft Academic Search

The actions of different insecticides known to affect binding of ligands to y?amino?butyric acid (GABA) receptors were studied on the function of GABAA receptors in rat brain as assayed by GABA?induced Cl 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

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

1986-01-01

21

Effects of aluminium exposure on brain glutamate and GABA systems: an experimental study in rats  

Microsoft Academic Search

It has been postulated that the neurotoxic effects of aluminium could be mediated through glutamate, an excitatory amino acid. Hence the effects of aluminium administration (at a dose of 4.2mg\\/kg body weight daily as aluminium chloride, hexahydrate, intraperitoneally, for 4 weeks) on glutamate and ?-amino butyrate (GABA), an inhibitory amino acid, and related enzyme activities in different regions of the

P Nayak; A. K Chatterjee

2001-01-01

22

Glutamate and GABA systems as targets for novel antidepressant and mood-stabilizing treatments  

Microsoft Academic Search

Glutamate and ?-amino butyric acid (GABA) systems are emerging as targets for development of medications for mood disorders. There is increasing preclinical and clinical evidence that antidepressant drugs directly or indirectly reduce N-methyl-D-aspartate glutamate receptor function. Drugs that reduce glutamatergic activity or glutamate receptor-related signal transduction may also have antimanic effects. Recent studies employing magnetic resonance spectroscopy also suggest that

J H Krystal; G Sanacora; H Blumberg; A Anand; D S Charney; G Marek; C N Epperson; A Goddard; G F Mason

2002-01-01

23

GABA B receptor activation exacerbates spontaneous spike-and-wave discharges in DBA\\/2J mice  

Microsoft Academic Search

Rich evidence has highlighted that stimulation of ?-amino-butyric acid (GABA)B receptors increases the occurrence of spike-and-wave discharges (SWDs), the electroencephalographic (EEG) landmark of absence epilepsy (AE). Recent findings suggest that the outcomes of GABAB activation in vivo are contingent on the chemical characteristics of the agonist. In particular, the endogenous ligand ?-hydroxybutyrate (GHB) and its precursor ?-butyro-lactone (GBL) have been

Marco Bortolato; Roberto Frau; Marco Orrù; Mauro Fà; Christian Dessì; Monica Puligheddu; Luigi Barberini; Giuliano Pillolla; Lorenzo Polizzi; Federico Santoni; Giampaolo Mereu; Francesco Marrosu

2010-01-01

24

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

2014-01-01

25

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

PubMed Central

Taste buds consist of at least three principal cell types that have different functions in processing gustatory signals — glial-like Type I cells, Receptor (Type II) cells, and Presynaptic (Type III) cells. Using a combination of Ca2+ imaging, single cell RT-PCR, and immunostaining, we show that ?-amino butyric acid (GABA) is an inhibitory transmitter in mouse taste buds, acting on GABA-A and GABA-B receptors to suppress transmitter (ATP) secretion from Receptor cells during taste stimulation. Specifically, Receptor cells express GABA-A receptor subunits ?2, ?, ?, as well as GABA-B receptors. In contrast, Presynaptic cells express the GABA-A?3 subunit and only occasionally GABA-B receptors. In keeping with the distinct expression pattern of GABA receptors in Presynaptic cells, we detected no GABAergic suppression of transmitter release from Presynaptic cells. We suggest that GABA may serve function(s) in taste buds in addition to synaptic inhibition. Finally, we also defined the source of GABA in taste buds: GABA is synthesized by GAD65 in Type I taste cells as well as by GAD67 in Presynaptic (Type III) taste cells and is stored in both those two cell types. We conclude that GABA is released during taste stimulation and possibly also during growth and differentiation of taste buds. PMID:21490220

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

2012-01-01

26

Metabotropic receptors for glutamate and GABA in pain.  

PubMed

Glutamate and gamma-amino butyric acid (GABA) are respectively two major excitatory and inhibitory neurotransmitters of the adult mammalian central nervous system. These neurotransmitters exert their action through two types of receptors: ionotropic and metabotropic receptors. While ionotropic receptors are ligand gated ion channels involved in fast synaptic transmission, metabotropic receptors belong to the superfamily of G-protein coupled receptors (GPCRs) and are responsible for the neuromodulatory effect of glutamate and GABA. Metabotropic glutamate receptors (mGluRs) and metabotropic GABA receptors (GABA-B) are present at different levels of the pain neuraxis where they regulate nociceptive transmission and pain. The present review will focus on the role of these receptors in the modulation of pain perception. PMID:19146876

Goudet, Cyril; Magnaghi, Valerio; Landry, Marc; Nagy, Frédéric; Gereau, Robert W; Pin, Jean-Philippe

2009-04-01

27

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

2012-01-01

28

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

2014-01-01

29

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

2010-01-01

30

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

2013-01-01

31

Functional milk beverage fortified with phenolic compounds extracted from olive vegetation water, and fermented with functional lactic acid bacteria  

Microsoft Academic Search

Functional milk beverages (FMB100 and FMB200) fortified with phenolic compounds (100 and 200mg\\/l) extracted from olive vegetable water, and fermented with ?-amino butyric acid (GABA)-producing (Lactobacillus plantarum C48) and autochthonous human gastro-intestinal (Lactobacillus paracasei 15N) lactic acid bacteria were manufactured. A milk beverage (MB), without addition of phenolic compounds, was used as the control. Except for a longer latency phase

M. Servili; C. G. Rizzello; A. Taticchi; S. Esposto; S. Urbani; F. Mazzacane; I. Di Maio; R. Selvaggini; M. Gobbetti; R. Di Cagno

2011-01-01

32

Production of high ?-aminobutyric acid (GABA) sour kimchi using lactic acid bacteria isolated from mukeunjee kimchi  

Microsoft Academic Search

A sour kimchi product with an elevated amount of ?-aminobutyric acid (GABA) was produced using starter lactic acid bacteria\\u000a (LAB) for mukeunjee kimchi fermentation. The starter LAB were screened and isolated from the commercial mukeunjee kimchi product that showed the highest GABA content and was identified as Lactobacillus buchneri. The maximum GABA production of L. buchneri in MRS media was

Seung Yong Cho; Min Jung Park; Ki Myong Kim; Jee-Hoon Ryu; Hyun Jin Park

2011-01-01

33

Mutation of the Drosophila vesicular GABA transporter disrupts visual figure detection  

PubMed Central

The role of gamma amino butyric acid (GABA) release and inhibitory neurotransmission in regulating most behaviors remains unclear. The vesicular GABA transporter (VGAT) is required for the storage of GABA in synaptic vesicles and provides a potentially useful probe for inhibitory circuits. However, specific pharmacologic agents for VGAT are not available, and VGAT knockout mice are embryonically lethal, thus precluding behavioral studies. We have identified the Drosophila ortholog of the vesicular GABA transporter gene (which we refer to as dVGAT), immunocytologically mapped dVGAT protein expression in the larva and adult and characterized a dVGATminos mutant allele. dVGAT is embryonically lethal and we do not detect residual dVGAT expression, suggesting that it is either a strong hypomorph or a null. To investigate the function of VGAT and GABA signaling in adult visual flight behavior, we have selectively rescued the dVGAT mutant during development. We show that reduced GABA release does not compromise the active optomotor control of wide-field pattern motion. Conversely, reduced dVGAT expression disrupts normal object tracking and figure–ground discrimination. These results demonstrate that visual behaviors are segregated by the level of GABA signaling in flies, and more generally establish dVGAT as a model to study the contribution of GABA release to other complex behaviors. PMID:20435823

Fei, Hao; Chow, Dawnis M.; Chen, Audrey; Romero-Calderón, Rafael; Ong, Wei S.; Ackerson, Larry C.; Maidment, Nigel T.; Simpson, Julie H.; Frye, Mark A.; Krantz, David E.

2010-01-01

34

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

2013-01-01

35

Allosteric modulation of retinal GABA receptors by ascorbic acid  

PubMed Central

Summary Ionotropic ?-aminobutyric acid receptors (GABAA and GABAC) belong to the cys-loop receptor family of ligand-gated ion channels. GABAC receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect of ascorbic acid on retinal GABA receptors has not been studied. Here we show that the function of GABAC and GABAA receptors is regulated by ascorbic acid. Patch-clamp recordings from bipolar cell terminals in goldfish retinal slices revealed that GABAC receptor-mediated currents activated by tonic background levels of extracellular GABA, and GABAC currents elicited by local GABA puffs, are both significantly enhanced by ascorbic acid. In addition, a significant rundown of GABA-puff evoked currents was observed in the absence of ascorbic acid. GABA-evoked Cl- currents mediated by homomeric ?1 GABAC receptors expressed in Xenopus laevis oocytes were also potentiated by ascorbic acid in a concentration-dependent, stereospecific, reversible, and voltage-independent manner. Studies involving the chemical modification of sulfhydryl groups showed that the two cys-loop cysteines and histidine 141, all located in the ?1 subunit extracellular domain, each play a key role in the modulation of GABAC receptors by ascorbic acid. Additionally, we show that retinal GABAA IPSCs and heterologously expressed GABAA receptor currents are similarly augmented by ascorbic acid. Our results suggest that ascorbic acid may act as an endogenous agent capable of potentiating GABAergic neurotransmission in the CNS. PMID:21715633

Calero, Cecilia I.; Vickers, Evan; Moraga Cid, Gustavo; Aguayo, Luis G.; von Gersdorff, Henrique; Calvo, Daniel J.

2011-01-01

36

Contribution of GABA(A) and GABA(B) receptors to the discriminative stimulus produced by gamma-hydroxybutyric acid.  

PubMed

The present study examined the involvement of GABA(A) and GABA(B) receptors in the discriminative stimulus effects of gamma-hydroxybutyric acid (GHB). Rats were trained to discriminate either 300 or 700 mg/kg GHB IG from water using a T-maze, food-reinforced drug-discrimination procedure. The direct GABA(B) agonist, baclofen, substituted completely for both training doses of GHB; its potency to substitute for GHB increased moderately as the training dose of GHB was increased. The positive GABA(A) modulator, diazepam, substituted partially for 300 mg/kg GHB, but failed to elicit GHB-appropriate responding in rats trained with the higher GHB dose. Finally, the GABA(B) antagonist, CGP 35348, completely blocked the discriminative stimulus effects of the high training dose of GHB, but only partially antagonized the effects of the low training dose. These results suggest that (a) GHB produces a compound stimulus, and (b) both GABA(B)- and GABA(A)-mediated cues are prominent components of this compound stimulus; the contribution of each component, however, appears to vary as the training dose of GHB is increased. PMID:10515314

Lobina, C; Agabio, R; Reali, R; Gessa, G L; Colombo, G

1999-10-01

37

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

PubMed

This paper investigated the influence of gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid content under hypoxia stress by accurately controlling the level of dissolved oxygen in hydroponics, using the roots of melon 'Xiyu 1' seedlings as the test material. The results showed that compared with the control, the growth of roots was inhibited seriously under hypoxia stress. Meanwhile, the hypoxia-treated roots had significantly higher activities of glutamate decarboxylase (GAD), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS), alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the contents of GABA, pyruvic acid, alanine (Ala) and aspartic acid (Asp). But the contents of glutamic acid (Glu) and alpha-keto glutaric acid in roots under hypoxia stress was obviously lower than those of the control. Exogenous treatment with GABA alleviated the inhibition effect of hypoxia stress on root growth, which was accompanied by an increase in the contents of endogenous GABA, Glu, alpha-keto glutaric acid and Asp. Furthermore, under hypoxia stress, the activities of GAD, GDH, GOGAT, GS, ALT, AST as well as the contents of pyruvic acid and Ala significantly decreased in roots treated with GABA. However, adding GABA and viny-gamma-aminobutyric acid (VGB) reduced the alleviation effect of GABA on melon seedlings under hypoxia stress. The results suggested that absorption of GABA by roots could alleviate the injury of hypoxia stress to melon seedlings. This meant that GABA treatment allows the normal physiological metabolism under hypoxia by inhibiting the GAD activity through feedback and maintaining higher Glu content as well as the bal- ance of carbon and nitrogen. PMID:25345052

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

2014-07-01

38

Elucidation of neuroprotective role of endogenous GABA and energy metabolites middle cerebral artery occluded model in rats.  

PubMed

The excitatory amino acids (EAA) like glutamate, aspartate and inhibitory neurotransmitter GABA (gama amino butyric acid) play an important role in the pathophysiology of cerebral ischemia. The objective of the present study is to elucidate the role of endogenous GABA against EAA release in different regions during ischemia. The transient focal ischemia was induced in rats by using middle cerebral artery occlusion model (MCAo). The results indicate gradual elevation of brain glutamate, aspartate and GABA level at different brain regions and attained peak level at 72 h of ischemic reperfusion (IR). At 168 h of IR the EAA levels declined to base line but GABA level was found to be still elevated. The biochemical analysis shows the depleted brain ATP, Na+K+ATPase content and triphasic response of glutathione activity. It can be concluded that time dependent variation in the EAA and GABA release, endogenous GABA can be neuroprotective and earlier restoration of energy deprivation is essential to prevent further neurodegeneration. To have efficient treatment in ischemic condition, multiple approaches like energy supply, antagonism of EAA, controlling calcium function are essential. PMID:22734249

Ramanathan, M; Babu, C Saravana; Justin, A; Shanthakumari, S

2012-06-01

39

Evidence that GABA ? subunits contribute to functional ionotropic GABA receptors in mouse cerebellar Purkinje cells  

PubMed Central

Ionotropic ?-amino butyric acid (GABA) receptors composed of heterogeneous molecular subunits are major mediators of inhibitory responses in the adult CNS. Here, we describe a novel ionotropic GABA receptor in mouse cerebellar Purkinje cells (PCs) using agents reported to have increased affinity for ? subunit-containing GABAC over other GABA receptors. Exogenous application of the GABAC-preferring agonist cis-4-aminocrotonic acid (CACA) evoked whole-cell currents in PCs, whilst equimolar concentrations of GABA evoked larger currents. CACA-evoked currents had a greater sensitivity to the selective GABAC antagonist (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA) than GABA-evoked currents. Focal application of agonists produced a differential response profile; CACA-evoked currents displayed a much more pronounced attenuation with increasing distance from the PC soma, displayed a slower time-to-peak and exhibited less desensitization than GABA-evoked currents. However, CACA-evoked currents were also completely blocked by bicuculline, a selective agent for GABAA receptors. Thus, we describe a population of ionotropic GABA receptors with a mixed GABAA/GABAC pharmacology. TPMPA reduced inhibitory synaptic transmission at interneurone–Purkinje cell (IN–PC) synapses, causing clear reductions in miniature inhibitory postsynaptic current (mIPSC) amplitude and frequency. Combined application of NO-711 (a selective GABA transporter subtype 1 (GAT-1) antagonist) and SNAP-5114 (a GAT-(2)/3/4 antagonist) induced a tonic GABA conductance in PCs; however, TPMPA had no effect on this current. Immunohistochemical studies suggest that ? subunits are expressed predominantly in PC soma and proximal dendritic compartments with a lower level of expression in more distal dendrites; this selective immunoreactivity contrasted with a more uniform distribution of GABAA ?1 subunits in PCs. Finally, co-immunoprecipitation studies suggest that ? subunits can form complexes with GABAA receptor ?1 subunits in the cerebellar cortex. Overall, these data suggest that ? subunits contribute to functional ionotropic receptors that mediate a component of phasic inhibitory GABAergic transmission at IN–PC synapses in the cerebellum. PMID:16945976

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

2006-01-01

40

Regulation of cell surface GABA(B) receptors: contribution to synaptic plasticity in neurological diseases.  

PubMed

?-Amino butyric acid (GABA(B)) receptors are heterodimeric G protein-coupled receptors expressed throughout the central nervous system in virtually all neurons. They control the excitability of neurons via activation of different downstream effector systems in pre- and postsynaptic neurons and as such regulate all major brain functions including synaptic plasticity, neuronal network activity, and neuronal development. Accordingly, GABA(B) receptors have been implicated in a variety of neurological disorders and thus are regarded as promising drug targets. A key factor determining the extent of GABA(B) receptor-mediated inhibition is the level of receptors at the cell surface available for signaling. There is increasing evidence that cell surface expression of functional GABA(B) receptors is affected in neurological diseases. This diminishes inhibitory control of neuronal excitation and may contribute to the disease state. Here, we discuss recent findings on mechanisms involved in regulating cell surface expression of GABA(B) receptors in addiction, neuropathic pain, and brain ischemia. PMID:25637437

Benke, Dietmar; Balakrishnan, Karthik; Zemoura, Khaled

2015-01-01

41

Increased GABA Levels in Medial Prefrontal Cortex of Young Adults with Narcolepsy  

PubMed Central

Study Objectives: To explore absolute concentrations of brain metabolites including gamma amino-butyric acid (GABA) in the medial prefrontal cortex and basal ganglia of young adults with narcolepsy. Design: Proton magnetic resonance (MR) spectroscopy centered on the medial prefrontal cortex and the basal ganglia was acquired. The absolute concentrations of brain metabolites including GABA and glutamate were assessed and compared between narcoleptic patients and healthy comparison subjects. Setting: Sleep and Chronobiology Center at Seoul National University Hospital; A high strength 3.0 Tesla MR scanner in the Department of Radiology at Seoul National University Hospital. Patients or Participants: Seventeen young adults with a sole diagnosis of HLA DQB1 0602 positive narcolepsy with cataplexy (25.1 ± 4.6 years old) and 17 healthy comparison subjects (26.8 ± 4.8 years old). Interventions: N/A. Measurements and Results: Relative to comparison subjects, narcoleptic patients had higher GABA concentration in the medial prefrontal cortex (t = 4.10, P <0.001). Narcoleptic patients with nocturnal sleep disturbance had higher GABA concentration in the medial prefrontal cortex than those without nocturnal sleep disturbance (t = 2.45, P= 0.03), but had lower GABA concentration than comparison subjects (t = 2.30, P = 0.03). Conclusions: The current study reports that young adults with narcolepsy had a higher GABA concentration in the medial prefrontal cortex, which was more prominent in patients without nocturnal sleep disturbance. Our findings suggest that the medial prefrontal GABA level may be increased in narcolepsy, and the increased medial prefrontal GABA might be a compensatory mechanism to reduce nocturnal sleep disturbances in narcolepsy. Citation: Kim SJ; Lyoo IK; Lee YS; Sung YH; Kim HJ; Kim JH; Kim KH; Jeong DU. Increased GABA levels in medial prefrontal cortex of young adults with narcolepsy. SLEEP 2008;31(3):342-347. PMID:18363310

Kim, Seog Ju; Lyoo, In Kyoon; Lee, Yujin S.; Sung, Young Hoon; Kim, Hengjun J.; Kim, Jihyun H.; Kim, Kye Hyun; Jeong, Do-Un

2008-01-01

42

Involvement of GABA A and GABA B receptors in the mediation of discriminative stimulus effects of ?-hydroxybutyric acid  

Microsoft Academic Search

COLOMBO, G., R. AGABIO, C. LOBINA, R. REALI AND G.L. GESSA. Involvement of GABAA and GABAB receptors in the mediation of discriminative stimulus effects of ?-hydroxybutyric acid. PHYSIOL BEHAV 64(3) 293–302, 1998.—The present study was designed to further investigate the pharmacological profile of the discriminative stimulus effects of ?-hydroxybutyric acid (GHB). Drugs acting at the ?-aminobutyric acid (GABA)B receptor (baclofen

Giancarlo Colombo; Roberta Agabio; Carla Lobina; Roberta Reali; Gian Luigi Gessa

1998-01-01

43

Electronic and structural features of ?-aminobutyric acid (GABA) and four of its direct agonists  

NASA Astrophysics Data System (ADS)

To understand better how the inhibitory neurotransmitter ?-aminobutyric acid (GABA) functions at its postsynaptic receptor site, electronic and structural features of the natural inhibitor were compared with four direct GABA agonists: muscimol, trans-3-amino-1-cyclopentane carboxylic acid ( trans-3 ACPC), isoguvacine and 4,5,6,7-tetrahydroisoxazolo [5,4-c]-pyridin-3-ol (THIP). The structures of isoguvacine and THIP were determined by X-ray crystallography. The structures of GABA and muscimol were retrieved from the literature and that of trans-3 ACPC was computed with AM1. A relationship was found between published IC50 values obtained from ( 3H)-GABA binding data and the per cent polar surface area scaled by molecular ionization potential. The structural features of GABA and its agonists were compared and a hypothesis for GABA agonist activity based upon position of the ammonium ion with respect to the carboxylate is presented.

Lipkowitz, Kenny B.; Gilardi, Richard D.; Aprison, M. H.

1989-04-01

44

Homocysteine alters cerebral microvascular integrity and causes remodeling by antagonizing GABA-A receptor.  

PubMed

High levels of homocysteine (Hcy), known as hyperhomocysteinemia (HHcy), are associated with cerebrovascular diseases, such as vascular dementia, stroke, and Alzheimer's disease. The ?-amino butyric acid (GABA) is an inhibitory neurotransmitter and a ligand of GABA-A receptor. By inhibiting excitatory response, it may decrease complications associated with vascular dementia and stroke. Hcy specifically competes with the GABA-A receptors and acts as an excitotoxic neurotransmitter. Previously, we have shown that Hcy increases levels of NADPH oxidase and reactive oxygen species (ROS), and decreases levels of thioredoxin and peroxiredoxin by antagonizing the GABA-A receptor. Hcy treatment leads to activation of matrix metalloproteinases (MMPs) in cerebral circulation by inducing redox stress and ROS. The hypothesis is that Hcy induces MMPs and suppresses tissue inhibitors of metalloproteinase (TIMPs), in part, by inhibiting the GABA-A receptor. This leads to degradation of the matrix and disruption of the blood brain barrier. The brain cortex of transgenic mouse model of HHcy (cystathionine ?-synthase, CBS-/+) and GABA-A receptor null mice treated with and without muscimol (GABA-A receptor agonist) was analysed. The mRNA levels were measured by Q-RT-PCR. Levels of MMP-2, -9, -13, and TIMP-1, -2, -3, and -4 were evaluated by in situ labeling and PCR-gene arrays. Pial venular permeability to fluorescence-labeled albumin was assessed with intravital fluorescence microscopy. We found that Hcy increases metalloproteinase activity and decreases TIMP-4 by antagonizing the GABA-A receptor. The results demonstrate a novel mechanism in which brain microvascular permeability changes during HHcy and vascular dementias, and have therapeutic ramifications for microvascular disease in Alzheimer's patients. PMID:22886392

Lominadze, David; Tyagi, Neetu; Sen, Utpal; Ovechkin, Alexander; Tyagi, Suresh C

2012-12-01

45

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

PubMed

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

2014-07-25

46

GABA production by glutamic acid decarboxylase is regulated by a dynamic catalytic loop.  

PubMed

Gamma-aminobutyric acid (GABA) is synthesized by two isoforms of the pyridoxal 5'-phosphate-dependent enzyme glutamic acid decarboxylase (GAD65 and GAD67). GAD67 is constitutively active and is responsible for basal GABA production. In contrast, GAD65, an autoantigen in type I diabetes, is transiently activated in response to the demand for extra GABA in neurotransmission, and cycles between an active holo form and an inactive apo form. We have determined the crystal structures of N-terminal truncations of both GAD isoforms. The structure of GAD67 shows a tethered loop covering the active site, providing a catalytic environment that sustains GABA production. In contrast, the same catalytic loop is inherently mobile in GAD65. Kinetic studies suggest that mobility in the catalytic loop promotes a side reaction that results in cofactor release and GAD65 autoinactivation. These data reveal the molecular basis for regulation of GABA homeostasis. PMID:17384644

Fenalti, Gustavo; Law, Ruby H P; Buckle, Ashley M; Langendorf, Christopher; Tuck, Kellie; Rosado, Carlos J; Faux, Noel G; Mahmood, Khalid; Hampe, Christiane S; Banga, J Paul; Wilce, Matthew; Schmidberger, Jason; Rossjohn, Jamie; El-Kabbani, Ossama; Pike, Robert N; Smith, A Ian; Mackay, Ian R; Rowley, Merrill J; Whisstock, James C

2007-04-01

47

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

2014-01-01

48

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

PubMed

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

2014-10-19

49

Serotonin as a Modulator of Glutamate- and GABA-Mediated Neurotransmission: Implications in Physiological Functions and in Pathology  

PubMed Central

The neurotransmitter serotonin (5-HT), widely distributed in the central nervous system (CNS), is involved in a large variety of physiological functions. In several brain regions 5-HT is diffusely released by volume transmission and behaves as a neuromodulator rather than as a “classical” neurotransmitter. In some cases 5-HT is co-localized in the same nerve terminal with other neurotransmitters and reciprocal interactions take place. This review will focus on the modulatory action of 5-HT on the effects of glutamate and ?-amino-butyric acid (GABA), which are the principal neurotransmitters mediating respectively excitatory and inhibitory signals in the CNS. Examples of interaction at pre-and/or post-synaptic levels will be illustrated, as well as the receptors involved and their mechanisms of action. Finally, the physiological meaning of neuromodulatory effects of 5-HT will be briefly discussed with respect to pathologies deriving from malfunctioning of serotonin system. PMID:18615128

Ciranna, L

2006-01-01

50

GABA levels within the medial preoptic area: effects of chronic administration of sodium valproic acid.  

PubMed

Sodium valproic acid (VPA) is a widely prescribed anticonvulsant medication that has been shown to interfere with pubertal maturation of the reproductive system, and induce endocrine abnormalities in adults, within a subset of the clinical population. While VPA's mechanism of action is still poorly understood, it may exert its anti-reproductive effects by enhancing GABAergic inhibition of the GnRH neuronal population within the medial preoptic area (mPOA). The purpose of this study was to determine if chronic administration of VPA alters GABA levels within the mPOA region. In Experiment 1, the mPOA, caudate, and arcuate nucleus regions were harvested from VPA-treated and control mice. Analysis of whole tissue content of GABA revealed that levels were lower in the caudate and arcuate nucleus regions of VPA-treated animals, whereas there were no group differences for the mPOA region. Collapsing across drug group, there was also a trend for males having overall higher levels of GABA as compared to females. In Experiments 2 and 3, mice were implanted with microdialysis probes within the mPOA region and sampled for extracellular GABA levels. Females (Exp. 3) were sampled either on diestrous, proestrous, or estrous. Results from males (Exp. 2) revealed that VPA enhanced extracellular GABA levels in the mPOA region compared with controls. However, GABA levels for both groups remained stable across the sampling period. Conversely, in Exp. 3, females showed cyclical release of GABA across the sampling period. For control females, GABA levels increased during the afternoon on all cycle days, but the rise on proestrus was smaller than on other cycle days. VPA-treated animals showed an overall reduction in GABA levels compared with controls. Furthermore, while GABA increased over sampling time on estrus and diestrus days of the cycle, there was not a significant rise in GABA on proestrus. These data indicate: (1) regional specificity in VPA effects upon GABA levels, (2) a sex difference in the effects of VPA on GABA levels within the mPOA, and (3) GABA levels increase on the afternoon of all days of the estrous cycle with VPA attenuating the rise seen on the afternoon of proestrus. These results provide evidence that VPA effects upon the reproductive axis may involve changes in GABA release, and that males and females show different patterns of neurochemical response to the drug. PMID:10818285

Dodge, J C; Illig, A M; Snyder, P J; Badura, L L

2000-07-01

51

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

PubMed Central

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

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

2014-01-01

52

Desensitization of Gamma Aminobutyric Acid (GABA) Receptors in Muscle Fibers of the Crab Cancer borealis  

PubMed Central

Carcinus muscle fibers respond to ?-aminobutyric acid (GABA) with a conductance increase that subsides rather rapidly. In the larger fibers which have low input resistance the decrease may disappear within 2 min. The inhibition of the excitatory postsynaptic potentials (EPSP's) by GABA nevertheless persists as long as the drug is applied. The subsidence of the increased conductance indicates that the membrane of the inhibitory synapses has become desensitized to GABA. The persistence of inhibition of the EPSP's appears to be due to an action of the drug on the presynaptic terminals of the excitatory axons which reduces or blocks the secretory activity that releases the excitatory transmitter. PMID:4327880

Epstein, René; Grundfest, Harry

1970-01-01

53

Behavioral and Neural Analysis of GABA in the Acquisition, Consolidation, Reconsolidation, and Extinction of Fear Memory  

PubMed Central

The current review systematically documents the role of ?-amino-butyric acid (GABA) in different aspects of fear memory—acquisition and consolidation, reconsolidation, and extinction, and attempts to resolve apparent contradictions in the data in order to identify the function of GABAA receptors in fear memory. First, numerous studies have shown that pre- and post-training administration of drugs that facilitate GABAergic transmission disrupt the initial formation of fear memories, indicating a role for GABAA receptors, possibly within the amygdala and hippocampus, in the acquisition and consolidation of fear memories. Similarly, recent evidence indicates that these drugs are also detrimental to the restorage of fear memories after their reactivation. This suggests a role for GABAA receptors in the reconsolidation of fear memories, although the precise neural circuits are yet to be identified. Finally, research regarding the role of GABA in extinction has shown that GABAergic transmission is also disruptive to the formation of newly acquired extinction memories. We argue that contradictions to these patterns are the result of variations in (a) the location of drug infusion, (b) the dosage of the drug and/or (c) the time point of drug administration. The question of whether these GABA-induced memory deficits reflect deficits in retrieval is discussed. Overall, the evidence implies that the processes mediating memory stability consequent to initial fear learning, memory reactivation, and extinction training are dependent on a common mechanism of reduced GABAergic neurotransmission. PMID:20410874

Makkar, Steve R; Zhang, Shirley Q; Cranney, Jacquelyn

2010-01-01

54

Contents of Neo-flavored Tea (GABA Kintaro) Containing ?-Aminobutyric Acid  

NASA Astrophysics Data System (ADS)

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

Shiraki, Yoshiya

55

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

SciTech Connect

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

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

1991-04-01

56

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

1985-01-01

57

Dopamine-related drugs act presynaptically to potentiate GABA(A) receptor currents in VTA dopamine neurons.  

PubMed

Electrical activity of ventral tegmental area (VTA) dopamine (DA) neurons is immediately inhibited following in vivo administration of cocaine and other DA-related drugs. While various forms of synaptic modulation were demonstrated in the VTA following exposure to DA-related drugs, comprehensive understanding of their ability to inhibit the activity of DA neurons, however, is still lacking. In this study, using whole-cell patch-clamp recordings from rat brain slices, a novel form of synaptic modulation induced by DA-related drugs was isolated. DA exposure was shown to cause potentiation of ?-amino-butyric acid (GABA) receptor type A (GABA(A)R)-mediated evoked inhibitory postsynaptic currents (eIPSCs), recorded from VTA DA neurons, under conditions of potassium channels blockade. The potentiation of these eIPSCs lasted for more than twenty minutes, could be mimicked by activation of D2-like but not D1-like DA receptors, and was accompanied by an increase in the frequency of GABA(A)R-mediated spontaneous miniature inhibitory postsynaptic currents (mIPSCs). Furthermore, exposure to inhibitors of DA transporter (DAT) led to potentiation of GABA(A) currents in a manner similar to the DA-mediated potentiation. Finally, a prolonged presence of l-NAME, an inhibitor of nitric-oxide (NO) signaling was found to conceal the potentiation of GABA(A) currents induced by the DA-related drugs. Taken together, this study demonstrates a new modulatory form of VTA GABA(A) neurotransmission mediated by DA-related drugs. These results also suggest better understanding of the initial inhibitory action of DA-related drugs on the activity of DA neurons in the VTA. PMID:21527263

Michaeli, Avner; Yaka, Rami

2011-01-01

58

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

PubMed

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

2014-03-01

59

?-Aminobutyric acid (GABA) concentration inversely correlates with basal perfusion in human occipital lobe.  

PubMed

Commonly used neuroimaging approaches in humans exploit hemodynamic or metabolic indicators of brain function. However, fundamental gaps remain in our ability to relate such hemo-metabolic reactivity to neurotransmission, with recent reports providing paradoxical information regarding the relationship among basal perfusion, functional imaging contrast, and neurotransmission in awake humans. Here, sequential magnetic resonance spectroscopy (MRS) measurements of the primary inhibitory neurotransmitter, ?-aminobutyric acid (GABA+macromolecules normalized by the complex N-acetyl aspartate-N-acetyl aspartyl glutamic acid: [GABA(+)]/[NAA-NAAG]), and magnetic resonance imaging (MRI) measurements of perfusion, fractional gray-matter volume, and arterial arrival time (AAT) are recorded in human visual cortex from a controlled cohort of young adult male volunteers with neurocognitive battery-confirmed comparable cognitive capacity (3?T; n=16; age=23±3 years). Regression analyses reveal an inverse correlation between [GABA(+)]/[NAA-NAAG] and perfusion (R=-0.46; P=0.037), yet no relationship between AAT and [GABA(+)]/[NAA-NAAG] (R=-0.12; P=0.33). Perfusion measurements that do not control for AAT variations reveal reduced correlations between [GABA(+)]/[NAA-NAAG] and perfusion (R=-0.13; P=0.32). These findings largely reconcile contradictory reports between perfusion and inhibitory tone, and underscore the physiologic origins of the growing literature relating functional imaging signals, hemodynamics, and neurotransmission. PMID:24398941

Donahue, Manus J; Rane, Swati; Hussey, Erin; Mason, Emily; Pradhan, Subechhya; Waddell, Kevin W; Ally, Brandon A

2014-03-01

60

A Single Amino Acid in the Second Transmembrane Domain of GABA ? Receptors Regulates Channel Conductance  

PubMed Central

GABAC receptors, expressed predominately in vertebrate retina, are thought to be formed mainly by GABA ? subunits, each of which exhibits distinct physiological and pharmacological properties. In this study, the receptors formed by perch GABA ? subunits were expressed in HEK cells, and their single channel conductances were determined using noise analysis techniques. The receptors formed by the perch ?1A subunit gate a channel with a conductance of 0.2 pS, whereas the receptors formed by GABA ?2 subunits exhibit much higher channel conductances, i.e., 3.2 pS and 3.5 pS for perch ?2A and ?2B receptors, respectively. A comparison of the amino acid sequences of the channel- forming TMII regions of the various subunits suggested that a single amino acid at position 2? was a potential site for the large differential in conductance. We found that switching the serine residue at that site in the GABA ?2 subunit to the proline residue present in the ?1 subunit reduced the channel conductance to a level similar to that of the wild type ?1 receptor. Conversely, mutating proline to serine in the amino acid sequence of the ?1 receptor significantly increased its unitary conductance. These results indicate that a single amino acid in the TMII region plays an important role in determining the single channel conductance of the GABAC receptors. PMID:17398006

Zhu, Yujie; Ripps, Harris; Qian, Haohua

2007-01-01

61

?(5)GABA(A) receptors mediate primary afferent fiber tonic excitability in the turtle spinal cord.  

PubMed

?-Amino butyric acid (GABA) plays a key role in the regulation of central nervous system by activating synaptic and extrasynaptic GABAA receptors. It is acknowledged that extrasynaptic GABAA receptors located in the soma, dendrites, and axons may be activated tonically by low extracellular GABA concentrations. The activation of these receptors produces a persistent conductance that can hyperpolarize or depolarize nerve cells depending on the Cl(-) equilibrium potential. In an in vitro preparation of the turtle spinal cord we show that extrasynaptic ?5GABAA receptors mediate the tonic state of excitability of primary afferents independently of the phasic primary afferent depolarization mediated by synaptic GABAA receptors. Blockade of ?5GABAA receptors with the inverse agonist L-655,708 depressed the dorsal root reflex (DRR) without affecting the phasic increase in excitability of primary afferents. Using RT-PCR and Western blotting, we corroborated the presence of the mRNA and the ?5GABAA protein in the dorsal root ganglia of the turtle spinal cord. The receptors were localized in primary afferents in dorsal root, dorsal root ganglia, and peripheral nerve terminals using immunoconfocal microscopy. Considering the implications of the DRR in neurogenic inflammation, ?5GABAA receptors may serve as potential pharmacological targets for the treatment of pain. PMID:23966669

Loeza-Alcocer, Emanuel; Canto-Bustos, Martha; Aguilar, Justo; González-Ramírez, Ricardo; Felix, Ricardo; Delgado-Lezama, Rodolfo

2013-11-01

62

Oral administration of ?-aminobutyric acid affects heat production in a hot environment in resting humans  

PubMed Central

Background Central administration of ?-amino butyric acid (GABA) induces lower body temperature in animals in hot ambient air. However, it is still unknown whether oral GABA administration affects temperature regulation at rest in a hot environment in humans. Therefore, in the present study, we specifically hypothesized that systemic administration of GABA in humans would induce hypothermia in a hot environment and that this response would be observed in association with decreased heat production. Methods Eight male participants drank a 200-ml sports drink with 1 g of GABA (trial G) or without GABA (trial C), then rested for 30 minutes in a sitting position in a hot environment (ambient air temperature 33°C, relative humidity 50%). Results We found that changes in esophageal temperature from before drinking the sports drink were lower in trial G than in trial C (-0.046 ± 0.079°C vs 0.001 ± 0.063°C; P < 0.05), with lower heat production calculated by oxygen consumption (41 ± 5 W/m2 vs 47 ± 8 W/m2; P < 0.05). Conclusions In this study, we have demonstrated that a single oral administration of GABA induced a larger decrease in body core temperature compared to a control condition during rest in a hot environment and that this response was concomitant with a decrease in total heat production. PMID:22738209

2012-01-01

63

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

PubMed

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

2015-02-01

64

Analogues of ?-aminobutyric acid (GABA) and trans-4-aminocrotonic acid (TACA) substituted in the 2 position as GABAC receptor antagonists  

PubMed Central

?-Aminobutyric acid (GABA) and trans-4-aminocrotonic acid (TACA) have been shown to activate GABAC receptors. In this study, a range of C2, C3, C4 and N-substituted GABA and TACA analogues were examined for activity at GABAC receptors. The effects of these compounds were examined by use of electrophysiological recording from Xenopus oocytes expressing the human ?1 subunit of GABAC receptors with the two-electrode voltage-clamp method. trans-4-Amino-2-fluorobut-2-enoic acid was found to be a potent agonist (KD=2.43??M). In contrast, trans-4-amino-2-methylbut-2-enoic acid was found to be a moderately potent antagonist (IC50=31.0??M and KB=45.5??M). These observations highlight the possibility that subtle structural substitutions may change an agonist into an antagonist. 4-Amino-2-methylbutanoic acid (KD=189??M), 4-amino-2-methylenebutanoic acid (KD=182??M) and 4-amino-2-chlorobutanoic acid (KD=285??M) were weak partial agonists. The intrinsic activities of these compounds were 12.1%, 4.4% and 5.2% of the maximal response of GABA, respectively. These compounds more effectively blocked the effects of the agonist, GABA, giving rise to KB values of 53??M and 101??M, respectively. The sulphinic acid analogue of GABA, homohypotaurine, was found to be a potent partial agonist (KD=4.59??M, intrinsic activity 69%). It was concluded that substitution of a methyl or a halo group in the C2 position of GABA or TACA is tolerated at GABAC receptors. However, there was dramatic loss of activity when these groups were substituted at the C3, C4 and nitrogen positions of GABA and TACA. Molecular modelling studies on a range of active and inactive compounds indicated that the agonist/competitive antagonist binding site of the GABAC receptor may be smaller than that of the GABAA and GABAB receptors. It is suggested that only compounds that can attain relatively flat conformations may bind to the GABAC receptor agonist/competitive antagonist binding site. PMID:9422798

Chebib, Mary; Vandenberg, Robert J; Johnston, Graham A R

1997-01-01

65

Decreased Hepatocyte Growth Factor (HGF) and Gamma Aminobutyric Acid (GABA) in Individuals with Obsessive-Compulsive Disorder (OCD)  

PubMed Central

Introduction There is support for the role of gamma aminobutyric acid (GABA) in the etiology of mood disorders. Recent research has shown that hepatocyte growth factor (HGF) modulates GABAergic inhibition and seizure susceptibility. This study was designed to determine and correlate plasma levels of HGF and GABA as well as symptom severity in individuals with obsessive-compulsive disorder (OCD). Subjects and methods Plasma from 15 individuals with OCD (9 males, 6 females;, mean age 38.7 years) and 17 neurotypical controls (10 males, 7 females; mean age 35.2 years) was assessed for HGF, GABA, urokinase plasminogen activator (uPA), and urokinase plasminogen activator receptor (uPAR) concentration using enzyme-linked immunosorbest assays ELISAs. Symptom severity was assessed in these OCD individuals and compared with HGF and GABA concentrations. Results In this preliminary study, individuals with OCD had significantly decreased HGF levels, decreased plasma levels of GABA and decreased uPA. We found that both uPA and uPAR levels correlate with HGF. Both low uPA and low uPAR levels correlate with high symptom severity in individuals with OCD. Low GABA levels in OCD individuals also correlate with high symptom severity. Discussion These results demonstrate a preliminary association between HGF, GABA, uPA levels, and OCD and suggest that plasma GABA and uPA levels are related to symptom severity in individuals with OCD. PMID:24023510

Russo, Anthony J.; Pietsch, Stefanie C.

2013-01-01

66

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

2014-01-01

67

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

2010-01-01

68

Probing the orthosteric binding site of GABAA receptors with heterocyclic GABA carboxylic acid bioisosteres.  

PubMed

The ionotropic GABAA receptors (GABAARs) are widely distributed in the central nervous system where they play essential roles in numerous physiological and pathological processes. A high degree of structural heterogeneity of the GABAAR has been revealed and extensive effort has been made to develop selective and potent GABAAR agonists. This review investigates the use of heterocyclic carboxylic acid bioisosteres within the GABAAR area. Several heterocycles including 3-hydroxyisoxazole, 3-hydroxyisoxazoline, 3-hydroxyisothiazole, and the 1- and 3-hydroxypyrazole rings have been employed in order to map the orthosteric binding site. The physicochemical properties of the heterocyclic moieties making them suitable for bioisosteric replacement of the carboxylic acid in the molecule of GABA are discussed. A variety of synthetic strategies for synthesis of the heterocyclic scaffolds are available. Likewise, methods for introduction of substituents into specific positions of the heterocyclic scaffolds facilitate the investigation of different regions in the orthosteric binding pocket in close vicinity of the core scaffolds of muscimol/GABA. The development of structural models, from pharmacophore models to receptor homology models, has provided more insight into the molecular basis for binding. Similar binding modes are proposed for the heterocyclic GABA analogues covered in this review by use of ligand-receptor docking into the receptor homology model and the presented structure-activity relationships. A network of interactions between the analogues and the binding pocket is leaving no room for substituents and underline the limited space in the GABAAR orthosteric binding site when in the agonist conformation. PMID:24362592

Petersen, Jette G; Bergmann, Rikke; Krogsgaard-Larsen, Povl; Balle, Thomas; Frølund, Bente

2014-06-01

69

Detection of ?-Aminobutyric Acid (GABA) by Longitudinal Scalar Order Difference Editing  

NASA Astrophysics Data System (ADS)

Two novel spectral editing techniques for the in vivo detection of ?-aminobutyric acid (GABA) are presented. The techniques rely on the generation of longitudinal scalar order (LSO) coherences, which in combination with J-difference editing results in the selective detection of GABA. The utilization of LSO coherences makes the editing sequences insensitive to phase and frequency instabilities. Furthermore, the spectral editing selectivity can be increased independent of the echo time, thereby opening the echo time for state-of-the-art water suppression and/or spatial localization techniques. The performance of the LSO editing techniques is theoretically demonstrated with product operator calculations and density matrix simulations and experimentally evaluated on phantoms in vitro and on human brain in vivo.

de Graaf, Robin A.; Rothman, Douglas L.

2001-09-01

70

Synthesis of ?-aminobutyric acid (GABA) by Lactobacillus plantarum DSM19463: functional grape must beverage and dermatological applications  

Microsoft Academic Search

Agriculture surplus were used as substrates to synthesize ?-aminobutyric acid (GABA) by Lactobacillus plantarum DSM19463 for the manufacture of a functional beverage or as a novel application for dermatological purposes. Dilution of\\u000a the grape must to 1 or 4% (w\\/v) of total carbohydrates favored higher cell yield and synthesis of GABA with respect to whey milk. Optimal conditions for\\u000a synthesizing

Raffaella Di Cagno; Francesco Mazzacane; Carlo Giuseppe Rizzello; Maria De Angelis; Giammaria Giuliani; Marisa Meloni; Barbara De Servi; Marco Gobbetti

2010-01-01

71

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

PubMed Central

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

Wu, Yuantai; Janetopoulos, Chris

2013-01-01

72

Regulation of ?-aminobutyric acid (GABA) release in cerebral cortex in the ?-hydroxybutyric acid (GHB) model of absence seizures in rat  

Microsoft Academic Search

?-Hydroxybutyric acid (GHB) has the ability to induce absence seizures. The precise way in which GHB causes seizures remains unclear, but GABAB- and\\/or GHB-mediated presynaptic mechanisms within thalamocortical circuitry may play a role. In the present study, we determined the basal and K+-evoked release of GABA and glutamate in the superficial laminae of frontal cortex during GHB-induced absence seizures. Our

R. Q Hu; P. K Banerjee; O. C Snead III

2000-01-01

73

Effect of GABA on oxidative stress in the skeletal muscles and plasma free amino acids in mice fed high-fat diet.  

PubMed

Increased levels of plasma free amino acids (pFAAs) can disturb the blood glucose levels in patients with obesity, diabetes mellitus and metabolic syndrome (MS) and are associated with enhanced protein oxidation. Oxidation of proteins, especially in the muscles, can promote protein degradation and elevate the levels of pFAAs. Gamma-aminobutyric acid (GABA), a food additive, can reduce high-fat diet (HFD)-induced hyperglycaemia; however, the mechanisms remain unclear. The aim of this study was to evaluate the effects of GABA on protein oxidation and pFAAs changes. One hundred male C57BL/6 mice were randomly divided into five groups that were fed with control diet, HFD and HFD supplied with 0.2%, 0.12% and 0.06% GABA in drinking water for 20 weeks respectively. HFD feeding led to muscular oxidative stress, protein oxidation, pFAA disorders, hyperglycaemia and augmented plasma GABA levels. Treatment with GABA restored normally fasting blood glucose level and dose-dependently inhibited body weight gains, muscular oxidation and protein degradation. While medium and low doses of GABA mitigated HFD-induced pFAA disorders, the high dose of GABA deteriorated the pFAA disorders. Medium dose of GABA increased the levels of GABA, but high dose of GABA reduced the levels of plasma GABA and increased the activity of succinic semialdehyde dehydrogenase in the liver. Therefore, treatment with GABA mitigated HFD-induced hyperglycaemia probably by repairing HFD-induced muscular oxidative stress and pFAA disorders in mice. Our data also suggest that an optimal dose of GABA is crucial for the prevention of excess GABA-related decrease in the levels of pFAA and GABA as well as obesity. PMID:25266692

Xie, Z X; Xia, S F; Qiao, Y; Shi, Y H; Le, G W

2015-06-01

74

SYSTEMIC ADMINISTRATION OF KAINIC ACID INCREASES GABA LEVELS IN PERFUSATE FROM THE HIPPOCAMPUS OF RATS IN VIVO  

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...

75

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

E-print Network

hypermethylation facilitated by the over-expression of the methylating enzyme DNA methyltransferase (Dnmt) 1. Using: Schizophrenia; Methylation; Migration; GABA; Gene; Promoter; Histone deacetylase; DNA methyltransferase, bipolar disorder; Dnmt, DNA methyltransferase; GABA, gamma-amino butyric acid; GAD, glutamic acid

Champagne, Frances A.

76

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

2012-01-01

77

Promoters inducible by aromatic amino acids and ?-aminobutyrate (GABA) for metabolic engineering applications in Saccharomyces cerevisiae.  

PubMed

A wide range of promoters with different strengths and regulatory mechanisms are valuable tools in metabolic engineering and synthetic biology. While there are many constitutive promoters available, the number of inducible promoters is still limited for pathway engineering in Saccharomyces cerevisiae. Here, we constructed aromatic amino-acid-inducible promoters based on the binding sites of Aro80 transcription factor, which is involved in the catabolism of aromatic amino acids through transcriptional activation of ARO9 and ARO10 genes in response to aromatic amino acids. A dynamic range of tryptophan-inducible promoter strengths can be obtained by modulating the number of Aro80 binding sites, plasmid copy numbers, and tryptophan concentrations. Using low and high copy number plasmid vectors and different tryptophan concentrations, a 29-fold range of fluorescence intensities of enhanced green fluorescent protein (EGFP) reporter could be achieved from a synthetic U4C ARO9 promoter, which is composed of four repeats of Aro80 binding half site (CCG) and ARO9 core promoter element. The U4C ARO9 promoter was applied to express alsS and alsD genes from Bacillus subtilis for acetoin production in S. cerevisiae, resulting in a gradual increase in acetoin titers depending on tryptophan concentrations. Furthermore, we demonstrated that ?-aminobutyrate (GABA)-inducible UGA4 promoter, regulated by Uga3, can also be used in metabolic engineering as a dose-dependent inducible promoter. The wide range of controllable expression levels provided by these tryptophan- and GABA-inducible promoters might contribute to fine-tuning gene expression levels and timing for the optimization of pathways in metabolic engineering. PMID:25573467

Kim, Sujin; Lee, Kyusung; Bae, Sang-Jeong; Hahn, Ji-Sook

2015-03-01

78

Kynurenic acid, by targeting ?7 nicotinic acetylcholine receptors, modulates extracellular GABA levels in the rat striatum in vivo.  

PubMed

Kynurenic acid (KYNA) is an astrocyte-derived non-competitive antagonist of the ?7 nicotinic acetylcholine receptor (?7nAChR) and inhibits the NMDA receptor (NMDAR) competitively. The main aim of the present study was to examine the possible effects of KYNA (30 - 1000 nm), applied locally by reverse dialysis for 2 h, on extracellular GABA levels in the rat striatum. KYNA concentration-dependently reduced GABA levels, with 300 nm KYNA causing a maximal reduction to ~60% of baseline concentrations. The effect of KYNA (100 nm) was prevented by co-application of galantamine (5 ?m), an agonist at a site of the ?7nAChR that is very similar to that targeted by KYNA. Infusion of 7-chlorokynurenic acid (100 nm), an NMDAR antagonist acting selectively at the glycineB site of the receptor, affected neither basal GABA levels nor the KYNA-induced reduction in GABA. Inhibition of endogenous KYNA formation by reverse dialysis of (S)-4-(ethylsulfonyl)benzoylalanine (ESBA; 1 mm) increased extracellular GABA levels, reaching a peak of 156% of baseline levels after 1 h. Co-infusion of 100 nm KYNA abolished the effect of ESBA. Qualitatively and quantitatively similar, bi-directional effects of KYNA on extracellular glutamate were observed in the same microdialysis samples. Taken together, the present findings suggest that fluctuations in endogenous KYNA levels, by modulating ?7nAChR function, control extracellular GABA levels in the rat striatum. This effect may be relevant for a number of physiological and pathological processes involving the basal ganglia. PMID:23442092

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

2013-05-01

79

Gamma-hydroxybutyric acid (GHB) and the mesoaccumbens reward circuit: evidence for GABA(B) receptor-mediated effects.  

PubMed

Gamma-hydroxybutyric acid (GHB) is a short-chain fatty acid naturally occurring in the mammalian brain, which recently emerged as a major recreational drug of abuse. GHB has multiple neuronal mechanisms including activation of both the GABA(B) receptor, and a distinct GHB-specific receptor. This complex GHB-GABA(B) receptor interaction is probably responsible for the multifaceted pharmacological, behavioral and toxicological profile of GHB. Drugs of abuse exert remarkably similar effects upon reward-related circuits, in particular the mesolimbic dopaminergic system and the nucleus accumbens (NAc). We used single unit recordings in vivo from urethane-anesthetized rats to characterize the effects of GHB on evoked firing in NAc "shell" neurons and on spontaneous activity of antidromically identified dopamine (DA) cells located in the ventral tegmental area. GHB was studied in comparison with the GABA(B) receptor agonist baclofen and antagonist (2S)(+)-5,5-dimethyl-2-morpholineacetic acid (SCH50911). Additionally, we utilized a GHB analog, gamma-(p-methoxybenzil)-gamma-hydroxybutyric acid (NCS-435), devoid of GABA(B) binding properties, but with high affinity for specific GHB binding sites. In common with other drugs of abuse, GHB depressed firing in NAc neurons evoked by the stimulation of the basolateral amygdala. On DA neurons, GHB exerted heterogeneous effects, which were correlated to the baseline firing rate of the cells but led to a moderate stimulation of the DA system. All GHB actions were mediated by GABA(B) receptors, since they were blocked by SCH50911 and were not mimicked by NCS-435. Our study indicates that the electrophysiological profile of GHB is close to typical drugs of abuse: both inhibition of NAc neurons and moderate to strong stimulation of DA transmission are distinctive features of diverse classes of abused drugs. Moreover, it is concluded that addictive and rewarding properties of GHB do not necessarily involve a putative high affinity GHB receptor. PMID:15708487

Pistis, M; Muntoni, A L; Pillolla, G; Perra, S; Cignarella, G; Melis, M; Gessa, G L

2005-01-01

80

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

1990-01-01

81

Zirconium-mediated intramolecular ester transfer reaction: synthesis of alpha-substituted gamma-aminobutyric acid (GABA) derivatives.  

PubMed

[reaction: see text]. The zirconium-mediated intramolecular ester transfer reaction of N-alkenyl carbamate derivatives proceeded to give alpha-substituted gamma-aminobutyric acid (GABA) derivatives in good to excellent yields. Quenching experiments of the reaction mixture with iodine or O2 indicated the presence of a cyclopropane intermediate. The resulting iodide was converted to 2-substituted pyrrolidine-3-carboxylate and/or alpha-alkylidene-gamma-aminobutyric acid derivatives in a stereospecific manner. PMID:11975613

Ito, Hisanaka; Omodera, Katsunori; Takigawa, Yasushi; Taguchi, Takeo

2002-05-01

82

Intraocular injections of nipecotic acid produce a preferential block of neuronal /sup 3/H-GABA accumulation in adult rabbit retina  

SciTech Connect

A procedure by which the activity of the retinal GABA uptake system can be manipulated in vivo has been developed. Intraocular injections of nipecotic acid, a proported GABA uptake blocker, were administered to adult rabbits every 48 hours for a two-week period. No behavioral or systemic changes were observed. Injections were well-tolerated with less than 10% loss of the tissue caused by physical damage or injection. Biochemical analyses demonstrated a dose-dependent inhibition of /sup 14/C-GABA uptake into retinal tissue. No effect on uptake was observed for saline-treated tissue. Autoradiographic analyses showed that in vivo treatment with nipecotic acid preferentially blocked accumulation of /sup 3/H-GABA into the amacrine cell bodies and processes in the inner plexiform layer. This treatment may be especially useful in assessing the functional significance of GABA transport in vivo.

Madtes, P. Jr.; Redburn, D.A.

1983-07-01

83

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.

2012-03-01

84

Acute effects of sodium valproate and gamma-vinyl GABA on regional amino acid metabolism in the rat brain: incorporation of 2-[14C]glucose into amino acids.  

PubMed

Amino acid concentrations have been determined in rat brain regions (cortex, striatum, cerebellum, and hippocampus) by HPLC after administration of acute anticonvulsant doses of sodium valproate (400 mg/kg, i.p.) and gamma-vinyl-GABA (1 g/kg, i.p.). After valproate administration the GABA level increases only in the cortex; aspartic acid concentration decreases in the cortex and hippocampus, and glutamic acid decreases in the hippocampus and striatum and increases in the cortex and cerebellum. There are no changes in the concentrations of glutamine, taurine, glycine, serine, and alanine following valproate administration. Only the GABA level increases in all the regions after gamma-vinyl-GABA administration. Cortical analyses 2, 4 and 10 minutes after pulse labeling with 2-[14C]glucose, i.v., show no change in the rate of cortical glucose utilization in the valproate treated group. The rate of labeling of glutamic acid is also unchanged, but the rate of labeling of GABA is reduced following valproate administration. After gamma-vinyl-GABA administration there is no change in the rate of labeling of GABA. These biochemical findings can be interpreted in terms of a primary anticonvulsant action of valproate on membrane receptors with secondary effects on the metabolism of amino acid neurotransmitters. This contrasts with the primary action of gamma-vinyl-GABA on GABA-transaminase activity. PMID:6817155

Chapman, A G; Riley, K; Evans, M C; Meldrum, B S

1982-09-01

85

Does gamma-aminobutyric acid (GABA) influence the development of chronic inflammation in rheumatoid arthritis?  

Microsoft Academic Search

BACKGROUND: Recent studies have demonstrated a role for spinal p38 MAP kinase (MAPK) in the development of chronic inflammation and peripheral arthritis and a role for GABA in the inhibition of p38 MAPK mediated effects. Integrating these data suggests that GABA may play a role in downregulating mechanisms that lead to the production of proinflammatory agents such as interleukin-1, interleukin-6,

James M Kelley; Laura B Hughes; S Louis Bridges Jr

2008-01-01

86

Allosteric ligands and their binding sites define ?-aminobutyric acid (GABA) type A receptor subtypes.  

PubMed

GABAA receptors (GABA(A)Rs) mediate rapid inhibitory transmission in the brain. GABA(A)Rs are ligand-gated chloride ion channel proteins and exist in about a dozen or more heteropentameric subtypes exhibiting variable age and brain regional localization and thus participation in differing brain functions and diseases. GABA(A)Rs are also subject to modulation by several chemotypes of allosteric ligands that help define structure and function, including subtype definition. The channel blocker picrotoxin identified a noncompetitive channel blocker site in GABA(A)Rs. This ligand site is located in the transmembrane channel pore, whereas the GABA agonist site is in the extracellular domain at subunit interfaces, a site useful for low energy coupled conformational changes of the functional channel domain. Two classes of pharmacologically important allosteric modulatory ligand binding sites reside in the extracellular domain at modified agonist sites at other subunit interfaces: the benzodiazepine site and the high-affinity, relevant to intoxication, ethanol site. The benzodiazepine site is specific for certain GABA(A)R subtypes, mainly synaptic, while the ethanol site is found at a modified benzodiazepine site on different, extrasynaptic, subtypes. In the transmembrane domain are allosteric modulatory ligand sites for diverse chemotypes of general anesthetics: the volatile and intravenous agents, barbiturates, etomidate, propofol, long-chain alcohols, and neurosteroids. The last are endogenous positive allosteric modulators. X-ray crystal structures of prokaryotic and invertebrate pentameric ligand-gated ion channels, and the mammalian GABA(A)R protein, allow homology modeling of GABA(A)R subtypes with the various ligand sites located to suggest the structure and function of these proteins and their pharmacological modulation. PMID:25637441

Olsen, Richard W

2015-01-01

87

Contribution of GABA A and GABA B Receptors to the Discriminative Stimulus Produced by Gamma-Hydroxybutyric Acid  

Microsoft Academic Search

The present study examined the involvement of GABAA and GABAB receptors in the discriminative stimulus effects of gamma-hydroxybutyric acid (GHB). Rats were trained to discriminate either 300 or 700 mg\\/kg GHB IG from water using a T-maze, food-reinforced drug-discrimination procedure. The direct GABAB agonist, baclofen, substituted completely for both training doses of GHB; its potency to substitute for GHB increased

Carla Lobina; Roberta Agabio; Roberta Reali; Gian Luigi Gessa; Giancarlo Colombo

1999-01-01

88

Why Are Cortical GABA Neurons Relevant to Internal Focus in Depression? A cross-level model linking cellular, biochemical, and neural network findings  

PubMed Central

Major Depression is a complex and severe psychiatric disorder whose symptomatology encompasses a critical shift in awareness, specifically in the balance from external to internal mental focus. This is reflected by unspecific somatic symptoms and the predominance of the own cognitions manifested in increased self-focus and rumination. We posit here that sufficient empirical data has accumulated to build a coherent biological model that links these psychological concepts and symptom dimensions to observed biochemical, cellular, regional and neural network deficits. Specifically, deficits in inhibitory gamma amino butyric acid (GABA) regulating excitatory cell input/output and local cell circuit processing of information in key brain regions may underlie the shift that is observed in depressed subjects in resting state activities between the perigenual anterior cingulate cortex (PACC) and the dorsolateral prefrontal cortex (DLPFC). This regional dysbalance translates at the network level in a dysbalance between default-mode and executive networks, which psychopathologically surfaces as a shift in focus from external to internal mental content and associated symptoms (See overview in Figure 1). We focus here on primary evidence at each of those levels and on putative mechanistic links between those levels. Apart from its implications for neuropsychiatric disorders, our model provides for the first time a set of hypotheses for cross-level mechanisms of how internal and external mental contents may be constituted and balanced in healthy subjects, and thus also contributes to the neuroscientific debate on the neural correlates of consciousness. PMID:25048001

2014-01-01

89

Presumed case of “stiff–horse syndrome” caused by decreased gamma-aminobutyric acid (GABA) production in an American Paint mare  

PubMed Central

Glutamic acid decarboxylase (GAD) converts glutamic acid into the inhibitory neurotransmitter ?-aminobutyric acid (GABA). Increased serum GAD (auto) antibody concentrations were found in a mare with increased postural musculature tone resulting in stiffness and recumbence. The mare was treated with dexamethasone which resulted in resolution of clinical signs and decreased GAD antibody concentrations. PMID:22753968

Purcell, Tawna Backman; Sellers, Ann Davidson; Goehring, Lutz S.

2012-01-01

90

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

PubMed

In this paper, we disclose the design and synthesis of a series of 2-substituted pyrrolidine-2-yl-acetic acid as core structures and the N-arylalkyl derivatives thereof as potential GABA transport inhibitors. The 2-position in the side chain of pyrrolidine-2-yl-acetic acid derivatives was substituted with alkyl, hydroxy and amino groups to modulate the activity and selectivity to mGAT1 and mGAT4 proteins. SAR studies of the compounds performed for the four mouse GABA transporter proteins (mGAT1-mGAT4) implied significant potencies and subtype selectivities for 2-hydroxy-2-pyrrolidine-2-yl-acetic acid derivatives. The racemate rac-(u)-13c exhibited the highest potency (pIC50 5.67) at and selectivity for mGAT1 in GABA uptake assays. In fact, the potency of rac-(u)-13c at hGAT-1 (pIC50 6.14) was even higher than its potency at mGAT1. These uptake results for rac-(u)-13c are in line with the binding affinities to the aforesaid proteins mGAT1 (pKi 6.99) and hGAT-1 (pKi 7.18) determined by MS Binding Assay based on NO711 as marker quantified by LC-ESI-MS-MS analysis. Interestingly, the 2-hydroxy-2-pyrrolidine-2-yl-acetic acid rac-(u)-13d containing 2-{[tris(4-methoxyphenyl)]methoxy} ethyl group at the nitrogen atom of the pyrrolidine ring showed high potency at mGAT4 and a comparatively better selectivity for this protein (>15 against mGAT3) than the well known mGAT4 uptake inhibitor (S)-SNAP-5114. PMID:25698617

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

2015-03-15

91

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

2008-01-01

92

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.

1989-01-01

93

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 ...

94

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

PubMed

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

2013-09-01

95

Glucose and amino acid metabolism in rat brain during sustained hypoglycemia  

SciTech Connect

The metabolism of glucose in brains during sustained hypoglycemia was studied. (U-/sup 14/C)Glucose (20 microCi) was injected into control rats, and into rats at 2.5 hr after a bolus injection of 2 units of insulin followed by a continuous infusion of 0.2 units/100 g rat/hr. This regimen of insulin injection was found to result in steady-state plasma glucose levels between 2.5 and 3.5 mumol per ml. In the brains of control rats carbon was transferred rapidly from glucose to glutamate, glutamine, gamma-aminobutyric acid and aspartate and this carbon was retained in the amino acids for at least 60 min. In the brains of hypoglycemic rats, the conversion of carbon from glucose to amino acids was increased in the first 15 min after injection. After 15 min, the specific activity of the amino acids decreased in insulin-treated rats but not in the controls. The concentrations of alanine, glutamate, and gamma-amino-butyric acid decreased, and the concentration of aspartate increased, in the brains of the hypoglycemic rats. The concentration of pyridoxal-5'-phosphate, a cofactor in many of the reactions whereby these amino acids are formed from tricarboxylic acid cycle intermediates, was less in the insulin-treated rats than in the controls. These data provide evidence that glutamate, glutamine, aspartate, and GABA can serve as energy sources in brain during insulin-induced hypoglycemia.

Wong, K.L.; Tyce, G.M.

1983-04-01

96

A fluorescent sensor for GABA and synthetic GABA(B) receptor ligands.  

PubMed

While ?-aminobutyric acid (GABA) is the main inhibitory neurotransmitter, suitable tools to measure its concentration in living cells with high spatiotemporal resolution are missing. Herein, we describe the first ratiometric fluorescent sensor for GABA, dubbed GABA-Snifit, which senses GABA with high specificity and spatiotemporal resolution on the surface of living mammalian cells. GABA-Snifit is a semisynthetic fusion protein containing the GABA(B) receptor, SNAP- and CLIP-tag, a synthetic fluorophore and a fluorescent GABA(B) receptor antagonist. When assembled on cell surfaces, GABA-Snifit displays a GABA-dependent fluorescence emission spectrum in the range of 500-700 nm that permits sensing micromolar to millimolar GABA concentrations. The ratiometric change of the sensor on living cells is 1.8. Furthermore, GABA-Snifit can be utilized to quantify the relative binding affinities of GABA(B) receptor agonists, antagonists and the effect of allosteric modulators. These properties make GABA-Snifit a valuable tool to investigate the role of GABA and GABA(B) in biological systems. PMID:23095089

Masharina, Anastasiya; Reymond, Luc; Maurel, Damien; Umezawa, Keitaro; Johnsson, Kai

2012-11-21

97

The effect of sodium valproate on extracellular GABA and other amino acids in the rat ventral hippocampus: an in vivo microdialysis study.  

PubMed

We report the effects of i.p. administration of sodium valproate (VPA) on extracellular concentrations of various amino acids in the rat ventral hippocampus studied using in vivo microdialysis, followed by HPLC with fluorometric detection. At the doses used (100, 200 and 400 mg/kg), VPA had no effect on extracellular aspartate, glutamine and taurine, whilst inducing a small, but not statistically significant increase in glutamate at 200 and 400 mg/kg. In contrast, VPA administration produced a biphasic effect on extracellular GABA levels which was dependent on the dose used. At 100 mg/kg, VPA reduced GABA concentrations by 50% when compared to basal. 200 mg/kg VPA had virtually no effect, whilst 400 mg/kg VPA raised extracellular GABA levels to 200% of basal. The results are discussed in relation to the known pharmacological and anticonvulsant actions of VPA. PMID:1467933

Biggs, C S; Pearce, B R; Fowler, L J; Whitton, P S

1992-10-23

98

Combinations of intrathecal gamma-amino-butyrate receptor agonists and N-methyl-D-aspartate receptor antagonists in rats with neuropathic spinal cord injury pain  

PubMed Central

Underlying below-level cutaneous hypersensitivity observed following spinal cord injury (SCI) is a concurrent loss of inhibition with an increase in excitation in the spinal dorsal horn. Thus, a dual pharmacological approach, increasing spinal ?-aminobutyrate (GABA) inhibition and decreasing N-methyl-D-aspartate (NMDA) receptor-mediated excitation, could be more beneficial than either approach alone. The current study evaluated the antinociceptive effects of lumbar intrathecal (i.t.) administration of GABA receptor agonists and NMDA receptor antagonists alone and in combination in rats with neuropathic SCI pain. Rats developed markedly decreased hind paw withdrawal thresholds following an acute thoracic spinal cord compression, indicative of below-level hypersensitivity. Separately, i.t. GABAA receptor agonist muscimol and GABAB receptor agonist baclofen demonstrated dose-dependent antinociception, whereas i.t. NMDA receptor antagonist ketamine and the endogenous peptide [Ser1]histogranin, a putative NMDA receptor antagonist, demonstrated no efficacy. The combination of baclofen and ketamine resulted in a supra-additive (synergistic) antinociception whereas the combinations with muscimol were merely additive. Intrathecal pretreatment with the GABAB receptor antagonist CGP 35348 prevented the antinociceptive effect of the baclofen and ketamine combination. The data indicate that blocking spinal NMDA receptors alone is not sufficient to ameliorate SCI hypersensitivity, whereas a combined approach, simultaneous activation of spinal GABAB receptors and NMDA receptors blockade with ketamine, leads to significant antinociception. By engaging diverse pain modulating systems at the spinal level, combination drug treatment may be a useful approach in treating neuropathic SCI pain. PMID:22449374

Hama, Aldric; Sagen, Jacqueline

2012-01-01

99

GABA(A) receptor transmembrane amino acids are critical for alcohol action: disulfide cross-linking and alkyl methanethiosulfonate labeling reveal relative location of binding sites.  

PubMed

Alcohols and inhaled anesthetics modulate GABA(A) receptor (GABA(A)R) function via putative binding sites within the transmembrane regions. The relative position of the amino acids lining these sites could be either inter- or intra-subunit. We introduced cysteines in relevant TM locations and tested the proximity of cysteine pairs using oxidizing and reducing agents to induce or break disulfide bridges between cysteines, and thus change GABA-mediated currents in wild-type and mutant ?1?2?2 GABA(A)Rs expressed in Xenopus laevis oocytes. We tested for: (i) inter-subunit cross-linking: a cysteine located in ?1TM1 [either ?1(Q229C) or ?1(L232C)] was paired with a cysteine in different positions of ?2TM2 and TM3; (ii) intra-subunit cross-linking: a cysteine located either in ?2TM1 [?2(T225C)] or in TM2 [?2(N265C)] was paired with a cysteine in different locations along ?2TM3. Three inter-subunit cysteine pairs and four intra-subunits cross-linked. In three intra-subunit cysteine combinations, the alcohol effect was reduced by oxidizing agents, suggesting intra-subunit alcohol binding. We conclude that the structure of the alcohol binding site changes during activation and that potentiation or inhibition by binding at inter- or intra-subunit sites is determined by the specific receptor and ligand. PMID:24117469

Borghese, Cecilia M; Hicks, Jessica A; Lapid, Daniel J; Trudell, James R; Harris, R Adron

2014-02-01

100

Human GABA(B)R genomic structure: evidence for splice variants in GABA(B)R1 but not GABA(B)R2.  

PubMed

The type B gamma-aminobutryic acid receptor (GABA(B)R) is a G protein coupled receptor that mediates slow pre- and post-synaptic inhibition in the nervous system. We find that the human GABA(B)R2 gene spans greater than 350 kb and contains 2.8 kb of coding region in 19 exons. The overall similarity in genomic structure with regard to conservation of intron position and exon size between human or Drosophila GABA(B)R1 and GABA(B)R2 genes suggests a common ancestral origin. Multiple transcripts GABA(B)R1a-c and GABA(B)R2a-c have been described and alternative splicing has been proposed to result in GABA(B)R1c, GABA(B)R2b and GABA(B)R2c. The results described here provide support for the existence of GABA(B)R1c but not for GABA(B)R2b and GABA(B)R2c. Splice junctions present in the GABA(B)R1 gene sequence are consistent with the formation of GABA(B)R1c by exon skipping of one sushi domain module. The GABA(B)R2 gene lacks canonical splice junctions for the reported variants. Consistent with this, RNA analysis demonstrates the presence of GABA(B)R1c and GABA(B)R2 transcripts in fetal and adult human brain RNA but GABA(B)R2b and GABA(B)R2c transcripts are not detected. These results provide insight into the evolution and transcript diversity of the mammalian GABA(B)R genes. PMID:11707323

Martin, S C; Russek, S J; Farb, D H

2001-10-31

101

[GABA-ergic system and antiepileptic drugs].  

PubMed

gamma-Aminobutyric acid (GABA) belongs to the main inhibitory neurotransmitters in the central nervous system and activates three types of specific receptors--GABAA, GABAB i GABAC. At present, little is known about GABAC-mediated events. GABAB receptors are metabotropic, whilst stimulation of ionotropic GABAA receptors results in opening the chloride channel, followed by influx of chloride ions and hyperpolarization. The GABAA receptor possesses also binding sites for benzodiazepines and barbiturates which, via these sites, enhance GABAA-mediated events. Another antiepileptic drug potentiating GABA-ergic inhibition is valproate, which increases synthesis of GABA and reduces its metabolism. Among new antiepileptic drugs associated with the GABA-ergic system are tiagabine, vigabatrin, and to a certain degree--gabapentin. Tiagabine blocks neuronal and glial uptake of GABA whilst vigabatrin increases the synaptic concentration of GABA by inhibition of GABA aminotransferase. Gabapentin, probably through the activation of glutamic acid decarboxylase, leads to the increase in synaptic GABA. However, this antiepileptic drug also binds to specific sites within voltage-dependent calcium channels, which results in reduced intraneuronal concentration of calcium ions. Presumably, tiagabine and vigabatrin possess only one mechanism of action, associated with increased GABA-ergic inhibition. Although topiramate and felbamate were shown to enhance GABA-mediated events, they have additional mechanisms of action, including blockade of voltage-dependent sodium channels and inhibition of glutamatergic neurotransmission. PMID:10791039

Czuczwar, S J

1999-01-01

102

[GABA-ergic system and antiepileptic drugs].  

PubMed

gamma-Aminobutyric acid (GABA) belongs to main inhibitory neurotransmitters in the central nervous system and activates three types of specific receptors--GABAA, GABAB i GABAC. At present, little is known about GABAC-mediated events. GABAB receptors are metabotropic, whilst stimulation of ionotropic GABAA receptors results in opening the chloride channel, followed by influx of chloride ions and hyperpolarization. The GABAA receptor possesses also binding sites for benzodiazepines and barbiturates which, via these sites, enhance GABAA-mediated events. Another antiepileptic drug potentiating GABA-ergic inhibition is valproate, which increases synthesis of GABA and reduces its metabolism. Among new antiepileptic drugs associated with the GABA-ergic system are tiagabine, vigabatrin, and to a certain degree--gabapentin. Tiagabine blocks neuronal and glial uptake of GABA whilst vigabatrin increases the synaptic concentration of GABA by inhibition of GABA aminotransferase. Gabapentin, probably through the activation of glutamic acid decarboxylase, leads to the increase in synaptic GABA. However, this antiepileptic drugs is also binds to specific sites within voltage-dependent calcium channels, which results in the reduced intraneuronal concentration of calcium ions. Presumably, tiagabine and vigabatrin possess only one mechanism of action, associated with the increased GABA-ergic inhibition. Although topiramate and felbamate were shown to enhance GABA-mediated events, they have additional mechanisms of action, including blockade of voltage-dependent sodium channels and inhibition of glutamatergic neurotransmission. PMID:10768141

Czuczwar, S J

2000-01-01

103

Autoradiographic analysis of 3H-glutamate, 3H-dopamine, and 3H-GABA accumulation in rabbit retina after kainic acid treatment  

SciTech Connect

We have previously reported that exposure of isolated rabbit retina to 10(-3) M kainic acid produces profound morphological changes in specific retinal neurons (Hampton et al, 1981). We noted specific swelling of horizontal cell bodies and neurites, necrosis of cell bodies in the amacrine and ganglion cell layers, and swelling of elements in the inner plexiform layer. We now report a differential sensitivity to kainic acid of specific subclasses of amacrine cells autoradiographically labeled with 3H-glutamate, 3H-GABA, or 3H-dopamine. Three different effects were observed: (1) Labeling of neurons after incubation in 3H-glutamate was uniformly reduced while labeling of glia was much less affected. (2) The accumulation of 3H-dopamine was also decreased by kainic acid in two of the three labeled bands of the inner plexiform layer. The outermost labeled band was insensitive to kainic acid at the highest concentration tested (10(-2) M). These findings provide a basis for the subclassification of dopaminergic amacrine cells into at least two subclasses based on their sensitivity to kainic acid. (3) Kainic acid caused a dramatic increase in the labeling of GABAergic amacrine cell bodies and their terminals. This increased intensity may reflect a compensatory increase in uptake activity in response to kainic acid-induced depletion of endogenous GABA stores. These results confirm the highly toxic nature of kainic acid and demonstrate a high degree of specificity and complexity in its action in the retina.

Hampton, C.K.; Redburn, D.A.

1983-01-01

104

GABA interaction with lipids in organic medium.  

PubMed

The interaction of 3H-GABA (gamma-aminobutyric acid and 14C-glutamate with lipids in an aqueous organic partition system was studied. With this partition system 3H-GABA and 14C-glutamate were able to interact with sphingomyelin, sulfatide, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and phosphatidic acid but not with cholesterol or ceramide. In an homogeneous aqueous medium we could not demonstrate any interaction between 3H-GABA and lipids. The apparent dissociation constants (Kd) for 3H-GABA-lipids or 14C-glutamate-lipids interactions in organic medium were in the millimolar range and maximal charge (Bmax) between 3 and 7 moles of GABA or glutamate by mole of lipid. Amino acids such as glutamic acid, beta-alanine and glycine displaced 3H-GABA with the same potency as GABA itself; thus these results show that the interaction lacks pharmacological specificity. To detect this interaction lipid concentrations higher than 2 microM were required and in the partition system 3H-GABA and lipid phosphorus were both concentrated at the interface. Therefore lipids tested with a biphasic partition system do not fulfill the classical criteria for a neurotransmitter receptor at least not for GABA and glutamate. PMID:2886873

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

1987-08-10

105

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

PubMed

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

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

2015-03-01

106

Genetics Home Reference: Succinic semialdehyde dehydrogenase deficiency  

MedlinePLUS

... the brain (neurotransmitter) called gamma-amino butyric acid (GABA). The primary role of GABA is to prevent the brain from being overloaded ... leads to an increase in the amount of GABA and a related molecule called gamma-hydroxybutyrate (GHB) ...

107

Structural basis for selective GABA binding in bacterial pathogens.  

PubMed

GABA acts as an intercellular signal in eukaryotes and as an interspecies signal in host-microbe interactions. Structural characteristics of selective eukaryotic GABA receptors and bacterial GABA sensors are unknown. Here, we identified the selective GABA-binding protein, called Atu4243, in the plant pathogen Agrobacterium tumefaciens. A constructed atu4243 mutant was affected in GABA transport and in expression of the GABA-regulated functions, including aggressiveness on two plant hosts and degradation of the quorum-sensing signal. The GABA-bound Atu4243 structure at 1.28?Å reveals that GABA adopts a conformation never observed so far and interacts with two key residues, Arg(203) and Asp(226) of which the role in GABA binding and GABA signalling in Agrobacterium has been validated using appropriate mutants. The conformational GABA-analogue trans-4-aminocrotonic acid (TACA) antagonizes GABA activity, suggesting structural similarities between the binding sites of the bacterial sensor Atu4243 and mammalian GABA(C) receptors. Exploration of genomic databases reveals Atu4243 orthologues in several pathogenic and symbiotic proteobacteria, such as Rhizobium, Azospirillum, Burkholderia and Pseudomonas. Thus, this study establishes a structural basis for selective GABA sensors and offers opportunities for deciphering the role of the GABA-mediated communication in several host-pathogen interactions. PMID:23043322

Planamente, Sara; Mondy, Samuel; Hommais, Florence; Vigouroux, Armelle; Moréra, Solange; Faure, Denis

2012-12-01

108

In intact islets interstitial GABA activates GABA(A) receptors that generate tonic currents in ?-cells.  

PubMed

In the rat islets ?-aminobutyric acid (GABA) is produced by the ?-cells and, at least, the ?-cells express the GABA(A) receptors (GABA(A) channels). In this study, we examined in intact islets if the interstitial GABA activated the GABA(A) receptors. We used the patch-clamp technique to record whole-cell and single-channel currents and single-cell RT-PCR to identify the cell-type we recorded from, in the intact rat islets. We further identified which GABA(A) receptor subunits were expressed. We determined the cell-type of 43 cells we recorded from and of these 49%, 28% and 7% were ?, ? and ?-cells, respectively. In the remaining 16% of the cells, mRNA transcripts of more than one hormone gene were detected. The results show that in rat islets interstitial GABA activates tonic current in the ?-cells but not in the ?-cells. Seventeen different GABA(A) receptor subunits are expressed with high expression of ?1, ?2, ?4, ?6, ?3, ?1, ?, ?1, ?2 and ?3 subunits whereas no expression was detected for ?5 or ? subunits. The abundance of the GABA(A) receptor subunits detected suggests that a number of GABA(A) receptor subtypes are formed in the islets. The single-channel and tonic currents were enhanced by pentobarbital and inhibited by the GABA(A) receptor antagonist SR-95531. The single-channel conductance ranged from 24 to 105 pS. Whether the single-channel conductance is related to subtypes of the GABA(A) receptor or variable interstitial GABA concentrations remains to be determined. Our results reveal that GABA is an extracellular signaling molecule in rat pancreatic islets and reaches concentration levels that activate GABA(A) receptors on the glucagon-releasing ?-cells. PMID:23826240

Jin, Yang; Korol, Sergiy V; Jin, Zhe; Barg, Sebastian; Birnir, Bryndis

2013-01-01

109

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

E-print Network

in the uptake of two neurotransmitters, y-aminobutyric acid (GABAJ and taurine in CD mice. Pineal uptake of two injected and their concentration both in pineal gland and cerebellum were measured at several times along to the pineal cycle of indoleamine synthesis. It was particularly sensitive to sudden changes of lighting

Paris-Sud XI, Université de

110

Presynaptic GABA Band ?-hydroxybutyric acid-mediated mechanisms in generalized absence seizures  

Microsoft Academic Search

?-Hydroxybutyric acid (GHB) is a naturally occurring compound which has the ability to induce generalized absence seizures when given to animals. This effect of GHB may be blocked by either GHB or GABAB receptor antagonists. We sought to test the hypothesis that pre-synaptic GHB- and GABAB-mediated mechanisms in thalamus and cortex are operative in the GHB model of generalized absence

O. C. Snead

1996-01-01

111

GABA in the nervous system of the planarian Polycelis nigra  

Microsoft Academic Search

Gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter in vertebrates and it has a similar inhibitory role in several invertebrate taxa. The transmitters serotonin, octopamine, catecholamines and histamine are present in flatworms while evidence for GABA is still lacking. Therefore, we have studied the occurrence of GABA-like immunoreactivity (IR) in the planarian nervous system. Specimens of Polycelis nigra were fixed

Krister Eriksson; Pertti Panula; Maria Reuter

1995-01-01

112

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

1982-01-01

113

Role for Pro-inflammatory Cytokines in Regulating Expression of GABA Transporter Type 1 and 3 in Specific Brain Regions of Kainic Acid-Induced Status Epilepticus.  

PubMed

In general, pro-inflammatory cytokines (PICs) contribute to regulation of epilepsy-associated pathophysiological processes in the central nerve system. In this report, we examined the specific activation of PICs, namely IL-1?, IL-6 and TNF-? in rat brain after kainic acid (KA)-induced status epilepticus (SE). Also, we examined the role played by PICs in regulating expression of GABA transporter type 1 and 3 (GAT-1 and GAT-3, respectively), which are the two important subtypes of GATs responsible for the regulation of extracellular GABA levels in the brain. Our results show that IL-1?, IL-6 and TNF-? were significantly increased in the parietal cortex, hippocampus and amygdala of KA-rats as compared with sham control animals (P < 0.05, KA rats vs. control rats). KA-induced SE also significantly increased (P < 0.05 vs. controls) the protein expression of GAT-1 and GAT-3 in those brain regions. In addition, central administration of antagonists to IL-1? and TNF-? receptors significantly attenuated amplified GAT-1 and GAT-3 (P < 0.05 vs. vehicle control for each antagonist group). However, antagonist to IL-6 receptor failed to attenuate enhancement in expression of GAT-1 and GAT-3 induced by KA-induced SE. Overall, our data demonstrate that PIC pathways are activated in the specific brain regions during SE which thereby selectively leads to upregulation of GABA transporters. As a result, it is likely that de-inhibition of GABA system is increased in the brain. This support a role for PICs in engagement of the adaptive mechanisms associated with epileptic activity, and has pharmacological implications to target specific PICs for neuronal dysfunction and vulnerability related to epilepsy. PMID:25708016

Su, Jing; Yin, Jian; Qin, Wei; Sha, Suxu; Xu, Jun; Jiang, Changbin

2015-03-01

114

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.

2009-04-14

115

GABA B receptor-mediated increase of neurosteroids by ?-hydroxybutyric acid  

Microsoft Academic Search

Among the pharmacological actions of ?-hydroxybutyric acid (GHB), some may involve GABAA receptor-mediated mechanisms. GHB, however, fails to directly interact with sites for agonists and modulators on the GABAA receptor complex. We hypothesized that, in vivo, GHB may interfere with GABAA receptor function by altering the brain concentrations of the neurosteroids 3?-hydroxy-5?-pregnan-20-one (allopregnanolone, AP) and 3?,21-dihydroxy-5?-pregnan-20-one (allotetrahydrodeoxycorticosterone, THDOC), positive allosteric

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

2002-01-01

116

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.

1991-01-01

117

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

ERIC Educational Resources Information Center

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

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

2009-01-01

118

Anti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind study.  

PubMed

The anti-hypertensive effect of GABA-rich Chlorella was studied after oral administration for 12 weeks in the subjects with high-normal blood pressure and borderline hypertension in the placebo-controlled, double-blind manner in order to investigate if GABA-rich Chlorella, a dietary supplement, is useful in control of blood pressure. Eighty subjects with Systolic blood pressure (SBP) 130-159 mmHg or diastolic blood pressure (DBP) 85-99 mmHg (40 subjects/group) took the blinded substance of GABA-rich Chlorella (20 mg as gamma-aminobutyric acid) or placebo twice daily for 12 weeks, and had follow-up observation for an additional 4 weeks. Systolic blood pressure in the subjects given GABA-rich Chlorella significantly decreased compared with placebo (p < 0.01). Diastolic blood pressure had the tendency to decrease after intake of GABA-rich Chlorella. Neither adverse events nor abnormal laboratory findings were reported throughout the study period. Reduction of SBP in the subjects with borderline hypertension was higher than those in the subjects with high-normal blood pressure. These results suggest that GABA-rich Chlorella significantly decreased high-normal blood pressure and borderline hypertension, and is a beneficial dietary supplement for prevention of the development of hypertension. PMID:19811362

Shimada, Morio; Hasegawa, Takashi; Nishimura, Chiaki; Kan, Hiroko; Kanno, Toshihiro; Nakamura, Toshio; Matsubayashi, Tsuneo

2009-06-01

119

GABA transporter preserving ongoing spontaneous neuronal activity at firing subthreshold.  

PubMed

There has been compelling evidence that the GABA transporter is crucial not only for removing gamma-aminobutyric acid (GABA) from but also releasing it into extracellular space, thereby clamping ambient GABA (GABA in extracellular space) at a certain level. The ambient GABA is known to activate extrasynaptic GABA receptors and provide tonic inhibitory current into neurons. We investigated how the transporter regulates the level of ambient GABA, mediates tonic neuronal inhibition, and influences ongoing spontaneous neuronal activity. A cortical neural network model is proposed in which GABA transporters on lateral (L) and feedback (F) inhibitory (GABAergic) interneurons are functionally made. Principal (P) cell assemblies participate in expressing information about elemental sensory features. At membrane potentials below the reversal potential, there is net influx of GABA, whereas at membrane potentials above the reversal potential, there is net efflux of GABA. Through this transport mechanism, ambient GABA concentration is kept within a submicromolar range during an ongoing spontaneous neuronal activity time period. Here we show that the GABA transporter on L cells regulates the overall level of ambient GABA across cell assemblies, and that on F cells it does so within individual cell assemblies. This combinatorial regulation of ambient GABA allows P cells to oscillate near firing threshold during the ongoing time period, thereby reducing their reaction time to externally applied stimuli. We suggest that the GABA transporter, with its forward and reverse transport mechanism, could regulate the ambient GABA. This transporter-mediated ambient GABA regulation may contribute to establishing an ongoing subthreshold neuronal state by which the network can respond rapidly to subsequent sensory input. PMID:19191601

Hoshino, Osamu

2009-06-01

120

4-Hydroxybutyric acid and the clinical phenotype of succinic semialdehyde dehydrogenase deficiency, an inborn error of GABA metabolism.  

PubMed

SSADH deficiency, a rare inborn error of human metabolism, disrupts the normal metabolism of the inhibitory neurotransmitter GABA. In response to the defect, physiologic fluids from patients accumulate GHB, a compound with numerous neuromodulatory properties. Clinical and bio-chemical findings in patients are contrasted with existing neuropharmacologic data on GHB in animals and men. We conclude that GHB contributes to the pathogenesis of SSADH deficiency; whether this effect is mediated by GHB, by GABA following metabolic interconversion, or via synergistic mechanisms by both compounds, remains to be determined. An animal model of SSADH deficiency should further define the role of GHB in the pathogenesis of SSADH deficiency, and provide a useful vehicle for the evaluation of new therapeutic intervention. PMID:9553943

Gibson, K M; Hoffmann, G F; Hodson, A K; Bottiglieri, T; Jakobs, C

1998-02-01

121

Gabapentin may inhibit synaptic transmission in the mouse spinal cord dorsal horn through a preferential block of P\\/Q-type Ca 2+ channels  

Microsoft Academic Search

Gabapentin is a lipophilic analog of ?-amino butyric acid (GABA) with therapeutic activity against certain forms of epilepsy and neuropathic pain. Despite its structural similarity to GABA, it does not bind GABAA or GABAB receptors and the mechanism, especially of its analgesic action, has remained elusive. Here, we have studied its effects on synaptic transmission mediated by the major spinal

Katharina Bayer; Seifollah Ahmadi; Hanns Ulrich Zeilhofer

2004-01-01

122

Muscimol as an ionotropic GABA receptor agonist.  

PubMed

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

2014-10-01

123

Divalproex sodium increases plasma GABA levels in healthy volunteers.  

PubMed

The purpose of this study was to ascertain the effects of divalproex sodium (DVP), an anticonvulsant and mood stabilizer, on plasma gamma-aminobutyric acid (GABA) levels in healthy humans. Twenty healthy volunteers with no lifetime history of psychiatric illness or family history in first-degree relatives were recruited. Each subject received DVP 1000 mg per day for 1 week. Blood samples for assay of plasma levels of GABA were taken from each subject before and after the administration of DVP. GABA concentrations were analysed using high pressure liquid chromatography with fluorescence detection after derivatization with o-phthaldialdehyde. It was found that DVP administration for 1 week resulted in a small, but significant, increase in plasma levels of GABA. Our results suggest that DVP enhances GABA activity in humans. Further treatment studies of DVP on GABA function in patients with psychiatric disorders are needed to explore the significance of the enhancing effect of DVP on GABA activity. PMID:10954062

Shiah, I S; Yatham, L N; Baker, G B

2000-07-01

124

Selected biomarkers as predictive tools in testing efficacy of melatonin and coenzyme Q on propionic acid - induced neurotoxicity in rodent model of autism  

PubMed Central

Background Exposures to environmental toxins are now thought to contribute to the development of autism spectrum disorder. Propionic acid (PA) found as a metabolic product of gut bacteria has been reported to mimic/mediate the neurotoxic effects of autism. Results from animal studies may guide investigations on human populations toward identifying environmental contaminants that produce or drugs that protect from neurotoxicity. Forty-eight young male Western Albino rats were used in the present study. They were grouped into six equal groups 8 rats each. The first group received a neurotoxic dose of buffered PA (250 mg/Kg body weight/day for 3 consecutive days). The second group received only phosphate buffered saline (control group). The third and fourth groups were intoxicated with PA as described above followed by treatment with either coenzyme Q (4.5 mg/kg body weight) or melatonin (10 mg/kg body weight) for one week (therapeutically treated groups). The fifth and sixth groups were administered both compounds for one week prior to PA (protected groups). Heat shock protein70 (Hsp70), Gamma amino-butyric acid (GABA), serotonin, dopamine, oxytocin and interferon ?-inducible protein 16 together with Comet DNA assay were measured in brain tissues of the six studied groups. Results The obtained data showed that PA caused multiple signs of brain toxicity revealed in depletion of GABA, serotonin, and dopamine, are which important neurotransmitters that reflect brain function, interferon ?-inducible protein 16 and oxytocin. A high significant increase in tail length, tail DNA% damage and tail moment was reported indicating the genotoxic effect of PA. Administration of melatonin or coenzyme Q showed both protective and therapeutic effects on PA–treated rats demonstrated in a remarkable amelioration of most of the measured parameters. Conclusion In conclusion, melatonin and coenzyme Q have potential protective and restorative effects against PA-induced brain injury, confirmed by improvement in biochemical markers and DNA double strand breaks. PMID:24568717

2014-01-01

125

A novel type of GABA receptor in rat spinal cord?  

Microsoft Academic Search

The depolarization-evoked release of ?-aminobutyric acid (GABA) and its possible modulation mediated by autoreceptors were studied in nerve endings isolated from rat spinal cord and prelabeled with the radioactive aminoacid. In the presence of the GABA uptake inhibitor SK&F 89976A [N-(4,4-diphenyl-3-butenyl)-nipecotic acid], used to minimize carrier-mediated homoexchange, exogenous GABA (1–10 µmol\\/l) decreased in a concentration-dependent way the release of3H-GABA evoked

Maurizio Raiteri; Graziella Pellegrini; Claudia Cantoni; Giambattista Bonanno

1989-01-01

126

Competitive antagonism of insect GABA receptors by iminopyridazine derivatives of GABA.  

PubMed

A series of 4-(6-imino-3-aryl/heteroarylpyridazin-1-yl)butanoic acids were synthesized and examined for antagonism of GABA receptors from three insect species. When tested against small brown planthopper GABA receptors, the 3,4-methylenedioxyphenyl and the 2-naphthyl analogues showed complete inhibition of GABA-induced fluorescence changes at 100 ?M in assays using a membrane potential probe. Against common cutworm GABA receptors, these analogues displayed approximately 86% and complete inhibition of GABA-induced fluorescence changes at 100 ?M, respectively. The 4-biphenyl and 4-phenoxyphenyl analogues showed moderate inhibition at 10 ?M in these receptors, although the inhibition at 100 ?M was not complete. Against American cockroach GABA receptors, the 4-biphenyl analogue exhibited the greatest inhibition (approximately 92%) of GABA-induced currents, when tested at 500 ?M using a patch-clamp technique. The second most active analogue was the 2-naphthyl analogue with approximately 85% inhibition. The 3-thienyl analogue demonstrated competitive inhibition of cockroach GABA receptors. Homology modeling and ligand docking studies predicted that hydrophobic 3-substituents could interact with an accessory binding site at the orthosteric binding site. PMID:22925448

Rahman, Mohammad Mostafizur; Akiyoshi, Yuki; Furutani, Shogo; Matsuda, Kazuhiko; Furuta, Kenjiro; Ikeda, Izumi; Ozoe, Yoshihisa

2012-10-01

127

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

PubMed Central

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

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

2013-01-01

128

GABA release from proopiomelanocortin neurons.  

PubMed

Neural networks controlling food intake and energy homeostasis clearly involve proopiomelanocortin (POMC) neurons and their peptide transmitters. alpha-melanocyte-stimulating hormone from arcuate POMC neurons potently reduces food intake, whereas arcuate neuropeptide Y (NPY) neurons act in opposition to stimulate food intake. In addition to orexigenic peptides, NPY neurons also release the inhibitory neurotransmitter GABA, which can act in a local circuit to inhibit POMC neuron activity. Whether or not reciprocal inhibition could occur has not yet been determined, because the presence of a rapid neurotransmitter in POMC neurons has not been demonstrated previously. Here, we used primary cultures of fluorescently labeled POMC neurons that had formed recurrent synapses (autapses) to detect the release of neurotransmitter. When an action potential was evoked in the axon of a POMC neuron with autapses, a short-latency synaptic current was recorded in the same cell. The autaptic current was abolished by GABA(A) receptor antagonists and substantially inhibited by opioids. Double-label in situ RNA hybridization for POMC and glutamic acid decarboxylase, the GABA synthetic enzyme, revealed colocalization of mRNAs in approximately one-third of POMC neurons in vivo. Our results suggest that these neurons can exert rapid inhibitory effects via the release of GABA, in addition to the more sustained actions provided by POMC peptides. However, this rapid inhibition may not play a major role within local hypothalamic circuits, but rather is likely to be important in more distant projection areas as indicated by the colocalization of vesicular GABA transporter immunoreactivity predominantly in extrahypothalamic POMC terminals. PMID:14973227

Hentges, Shane T; Nishiyama, Mitsuru; Overstreet, Linda S; Stenzel-Poore, Mary; Williams, John T; Low, Malcolm J

2004-02-18

129

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.

1988-02-01

130

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

2014-01-01

131

GABA and GABA A receptor expression on immune cells in psoriasis: a pathophysiological role  

Microsoft Academic Search

Psoriasis is a chronic inflammatory disease in which pruritus is a common symptom. Pruritus may be associated with the gamma-aminobutyric\\u000a acid (GABA) system. The distribution of GABA and its GABAA receptor (R) was studied in involved and non-involved psoriatic skin, as well as normal healthy control skin, using an immunohistochemistry\\u000a technique. Pruritus was determined using a visual analog scale. Inflammatory

Rishi Nigam; Husameldin El-Nour; Beni Amatya; Klas Nordlind

2010-01-01

132

Modulation by GABA of neuroplasticity in the central and peripheral nervous system  

Microsoft Academic Search

Apart from being a prominent (inhibitory) neurotransmitter that is widely distributed in the central and peripheral nervous system, ?-aminobutyric acid (GABA) has turned out to exert trophic actions. In this manner GABA may modulate the neuroplastic capacity of neurons and neuron-like cells under various conditions in situ and in vitro. In the superior cervical ganglion (SCG) of adult rat, GABA

J. R. Wolff; F. Joó; P. Kfisa

1993-01-01

133

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

2002-01-01

134

Characteristic expressions of GABA receptors and GABA producing/transporting molecules in rat kidney.  

PubMed

Gamma-aminobutyric acid (GABA) is an important neurotransmitter, but recent reports have revealed the expression of GABAergic components in peripheral, non-neural tissues. GABA administration induces natriuresis and lowers blood pressure, suggesting renal GABA targets. However, systematic evaluation of renal GABAergic components has not been reported. In this study, kidney cortices of Wistar-Kyoto rats (WKY) were used to assay for messenger RNAs of GABA-related molecules using RT-PCR. In WKY kidney cortex, GABAA receptor subunits, ?1, ?3, ?, ? and ?, in addition to both types of GABAB receptors, R1 and R2, and GABAC receptor ?1 and ?2 subunit mRNAs were detected. Kidney cortex also expressed mRNAs of glutamate decarboxylase (GAD) 65, GAD67, 4-aminobutyrate aminotransferase and GABA transporter, GAT2. Western blot and/or immunohistochemistry were performed for those molecules detected by RT-PCR. By immunofluorescent observation, co-staining of ?1, ?3, and ? subunits was observed mainly on the apical side of cortical tubules, and immunoblot of kidney protein precipitated with ? subunit antibody revealed ?1 and ?3 subunit co-assembly. This is the first report of GABAA receptor ? subunit in the kidney. In summary, unique set of GABA receptor subunits and subtypes were found in rat kidney cortex. As GABA producing enzymes, transporters and degrading enzyme were also detected, a possible existence of local renal GABAergic system with an autocrine/paracrine mechanism is suggested. PMID:25188493

Takano, Kozue; Yatabe, Midori Sasaki; Abe, Asami; Suzuki, Yu; Sanada, Hironobu; Watanabe, Tsuyoshi; Kimura, Junko; Yatabe, Junichi

2014-01-01

135

Characteristic Expressions of GABA Receptors and GABA Producing/Transporting Molecules in Rat Kidney  

PubMed Central

Gamma-aminobutyric acid (GABA) is an important neurotransmitter, but recent reports have revealed the expression of GABAergic components in peripheral, non-neural tissues. GABA administration induces natriuresis and lowers blood pressure, suggesting renal GABA targets. However, systematic evaluation of renal GABAergic components has not been reported. In this study, kidney cortices of Wistar-Kyoto rats (WKY) were used to assay for messenger RNAs of GABA-related molecules using RT-PCR. In WKY kidney cortex, GABAA receptor subunits, ?1, ?3, ?, ? and ?, in addition to both types of GABAB receptors, R1 and R2, and GABAC receptor ?1 and ?2 subunit mRNAs were detected. Kidney cortex also expressed mRNAs of glutamate decarboxylase (GAD) 65, GAD67, 4-aminobutyrate aminotransferase and GABA transporter, GAT2. Western blot and/or immunohistochemistry were performed for those molecules detected by RT-PCR. By immunofluorescent observation, co-staining of ?1, ?3, and ? subunits was observed mainly on the apical side of cortical tubules, and immunoblot of kidney protein precipitated with ? subunit antibody revealed ?1 and ?3 subunit co-assembly. This is the first report of GABAA receptor ? subunit in the kidney. In summary, unique set of GABA receptor subunits and subtypes were found in rat kidney cortex. As GABA producing enzymes, transporters and degrading enzyme were also detected, a possible existence of local renal GABAergic system with an autocrine/paracrine mechanism is suggested. PMID:25188493

Takano, Kozue; Yatabe, Midori Sasaki; Abe, Asami; Suzuki, Yu; Sanada, Hironobu; Watanabe, Tsuyoshi; Kimura, Junko; Yatabe, Junichi

2014-01-01

136

UV – INDUCED SYNTHESIS OF AMINO ACIDS FROM AQUEOUS STERILIZED SOLUTION OF AMMONIUM FORMATE AND AMMONIA UNDER HETROGENEOUS CONDITIONS  

PubMed Central

Irradiation of sterilized aqueous solution of ammonium formate and ammonia with UV light in the presence and or absence of certain inorganic sensitizers for 25 hrs. gave six ninhydrin positive products in appreciable amounts. Out of the six products observed fiver were characterized as lysine, serine, glutemic acid, n-amino butyric acid and leucine. The sensitizing effect of additives on ammonium formate was observed in the order; uranium oxide > ammonium formate > ferric oxide > arsenic oxide. PMID:22556511

Bisht, G.; Bisht, L. S.

1990-01-01

137

Pharmacological Characterization of Nicotinic Receptor stimulated GABA Release From Mouse Brain Synaptosomes1  

Microsoft Academic Search

Several recent electrophysiological studies have demonstrated that nicotinic agonists stimulate the release of g-aminobutyric acid (GABA) from rodent brain tissue. Our studies used a neu- rochemical approach to characterize nicotinic receptor-stimu- lated (3H)-GABA release from mouse brain synaptosomes. Nicotine increased (3H)-GABA release from synaptosomes pre- loaded with (3H)-GABA in a concentration-dependent manner. This release appeared rapidly, was Ca11 dependent, and

YING LU; SHARON GRADY; MICHAEL J. MARKS; MARINA PICCIOTTO; JEAN-PIERRE CHANGEUX; ALLAN C. COLLINS

138

Regulation of GABA content by glucose in the chick retina.  

PubMed

Some visual information is processed in the retina by ?-aminobutyric acid (GABA) signaling. Once retinal degeneration and visual impairment caused by diabetic retinopathy (DR) are affecting an increasing number of people worldwide, and the disease is characterized by hyper- and hypoglycemic events, the authors aimed to investigate how retinal GABA cell content is affected by variations in glucose availability. Using the ex vivo chick retinas exposed to different glucose concentrations, we observed that amacrine cells from both inner nuclear layer (INL) and ganglion cell layer (GCL) as well as their processes in the inner plexiform layer (IPL) released GABA through GABA transporter-1 (GAT-1) after 30 min of glucose deprivation. Extending this insult to 60 min triggered a permanent loss of GABA-positive amacrine cells, caused swelling of IPL and cell death. High glucose (35 mM) for 30 min induced an increment in GABA immunolabeling in both outer and inner retina. Further, glucose deprivation effects could not be reverted by basal glucose levels and high glucose did not prevent GABA loss upon a glucose deprivation insult. Therefore, GABA cell content is differently affected by short-term variations in glucose availability. While high glucose modulates outer and inner GABAergic circuits, glucose deprivation affects mainly the inner retina. Also, consecutive alteration in glucose supply was not able to rescue basal GABA content. Therefore, glucose oscillations interfering with GABAergic retinal functioning during early stages of retinopathies should be further investigated. PMID:23920155

Miya-Coreixas, Vivian Sayuri; Maggesissi Santos, Raquel; Carpi Santos, Raul; Gardino, Patrícia Franca; Calaza, Karin

2013-10-01

139

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

PubMed

GABA is the major inhibitory transmitter in the brain and is released not only from a subset of neurons but also from glia. Although neuronal GABA is well known to be synthesized by glutamic acid decarboxylase (GAD), the source of glial GABA is unknown. After estimating the concentration of GABA in Bergmann glia to be around 5-10 mM by immunogold electron microscopy, we demonstrate that GABA production in glia requires MAOB, a key enzyme in the putrescine degradation pathway. In cultured cerebellar glia, both Ca(2+)-induced and tonic GABA release are significantly reduced by both gene silencing of MAOB and the MAOB inhibitor selegiline. In the cerebellum and striatum of adult mice, general gene silencing, knock out of MAOB or selegiline treatment resulted in elimination of tonic GABA currents recorded from granule neurons and medium spiny neurons. Glial-specific rescue of MAOB resulted in complete rescue of tonic GABA currents. Our results identify MAOB as a key synthesizing enzyme of glial GABA, which is released via bestrophin 1 (Best1) channel to mediate tonic inhibition in the brain. PMID:25239459

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

2014-11-15

140

GABA promotes human ?-cell proliferation and modulates glucose homeostasis.  

PubMed

?-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

2014-12-01

141

Estrogen regulation of GABA transmission in rat preoptic area.  

PubMed

The medial preoptic area represents a brain region where gonadal steroids act upon classical nuclear receptors to alter brain function. Of all the neuronal phenotypes shown to express estrogen receptors in the preoptic area, GABA neurones are the most abundant and known to be located in several nuclei of the medial preoptic area. Investigators utilising techniques capable of assessing endogenous GABA levels have shown that estrogen increases both basal and stimulated extracellular GABA concentrations within the preoptic area. Experiments have also shown that estrogen is able to modulate the actions of noradrenaline upon preoptic GABA neurones. The precise nature of estrogen's stimulatory influence on preoptic GABA concentrations is not understood fully but appears to involve changes in both the release and reuptake of GABA. As estrogen does not influence glutamic acid decarboxylase activity or gene expression in the preoptic area, the subcellular mechanism(s) through which estrogen enhances GABA release remain unknown. Recent investigations indicate that estrogen upregulates transcription of the GAT-1 GABA transporter gene in the preoptic area, and that this may contribute the stimulatory effect of estrogen on extracellular GABA concentrations. Further studies have identified effects of estrogen on GABA(A) receptor expression and ligand binding and, together with the above observations, demonstrate a coordinated and multifaceted upregulation of the preoptic GABA network by estrogen. It is suggested that estrogen acts directly upon GABA neurones expressing estrogen receptors to alter the dynamics of inhibitory transmission within specific neuronal networks of the preoptic area. This is likely to be of functional significance to the "feedback" influence of estrogen on the neural regulation of reproduction. PMID:9370195

Herbison, A E

1997-01-01

142

REVIEW ARTICLE published: 19 September 2014  

E-print Network

MKII, calcium-calmodulin dependent protein kinase II; cAMP, cyclic adenosine triphosphate; cGMP, cyclic guanine, dehydroascorbic acid; ERK, extracellular signal-regulated kinase; GABA, gamma- amino butyric acid; GAD, glutamic, glutathione disulphide; ipRGCs, intrinsically photoreceptive retinal ganglion cells; JNK, c-jun kinase; K2P

Gillette, Martha U.

143

Gamma-hydroxybutyric acid decreases thalamic sensory excitatory postsynaptic potentials by an action on presynaptic GABA B receptors  

Microsoft Academic Search

The effect of gamma-hydroxybutyric acid (GHB) on the excitatory postsynaptic potential (EPSP) evoked in thalamocortical neurones of the rat dorsal lateral geniculate nucleus and ventrobasal thalamus was investigated in vitro. GHB (0.1–5 mM) dose-dependently and reversibly decreased (36–78%) the amplitude of the sensory EPSP. This effect of GHB was blocked by the GABAB receptor antagonist CGP 35348 (1 mM). NCS

Zsuzsa Emri; Kàroly Antal; Vincenzo Crunelli

1996-01-01

144

Spatial Distributions of GABA Receptors and Local Inhibition of Ca2+ Transients Studied with GABA Uncaging in the Dendrites of CA1 Pyramidal Neurons  

PubMed Central

GABA(?-amino-butylic acid)-mediated inhibition in the dendrites of CA1 pyramidal neurons was characterized by two-photon uncaging of a caged-GABA compound, BCMACM-GABA, and one-photon uncaging of RuBi-GABA in rat hippocampal slice preparations. Although we found that GABAA-mediated currents were diffusely distributed along the dendrites, currents elicited at the branch points of the apical dendritic trunk were approximately two times larger than those elsewhere in the dendrite. We examined the inhibitory action of the GABA-induced currents on Ca2+ transients evoked with a single back-propagating action potential (bAP) in oblique dendrites. We found that GABA uncaging selectively inhibited the Ca2+ transients in the region adjacent (<20 µm) to the uncaging site, and that GABA uncaging was effective only within a short period after bAP (<20 ms). The strength of inhibition was linearly related to the amplitudes of the GABA currents, suggesting that the currents inhibited a sustained, subthreshold after-depolarization without preventing propagation of bAP. GABA uncaging at the dendritic branch points inhibited Ca2+ transients farther into dendritic branches (>20 µm). Our data indicate that GABA inhibition results in spatially confined inhibition of Ca2+ transients shortly after bAP, and suggest that this effect is particularly potent at the dendritic branch points where GABA receptors cluster. PMID:21799926

Kanemoto, Yuya; Matsuzaki, Masanori; Morita, Susumu; Hayama, Tatsuya; Noguchi, Jun; Senda, Naoko; Momotake, Atsuya; Arai, Tatsuo; Kasai, Haruo

2011-01-01

145

Vibrational circular dichroism (VCD) chiral assignment of atropisomers: application to ?-aminobutyric acid (GABA) modulators designed as potential anxiolytic drugs.  

PubMed

Atropisomers exist when axial chirality is present as a result of conformationally restricted rotation around a single bond. The interconversion rate of the individual atropisomers is critical to the assessment of chiral stability of a drug throughout scale-up, development, production, and storage as well as in vivo pharmacokinetics. We describe the application of vibrational circular dichroism spectroscopy coupled with quantum mechanics simulations to assign the absolute axial chirality and measure the racemization half-life of a series of potential anxiolytic drugs that act as ?-aminobutyric acid modulators. PMID:23601535

Pivonka, Don E; Wesolowski, Steven S

2013-04-01

146

GABA Acts as a Ligand Chaperone in the Early Secretory Pathway to Promote Cell Surface Expression of GABAA Receptors  

PubMed Central

GABA (?-aminobutyric acid) is the primary inhibitory neurotransmitter in brain. The fast inhibitory effect of GABA is mediated through the GABAA receptor, a postsynaptic ligand-gated chloride channel. We propose that GABA can act as a ligand chaperone in the early secretory pathway to facilitate GABAA receptor cell surface expression. Forty-two hrs of GABA treatment increased the surface expression of recombinant receptors expressed in HEK 293 cells, an effect accompanied by an increase in GABA-gated chloride currents. In time-course experiments, a 1 hr GABA exposure, followed by a 5 hr incubation in GABA-free medium, was sufficient to increase receptor surface expression. A shorter GABA exposure could be used in HEK 293 cells stably transfected with the GABA transporter GAT-1. In rGAT-1HEK 293 cells, the GABA effect was blocked by the GAT-1 inhibitor NO-711, indicating that GABA was acting intracellularly. The effect of GABA was prevented by brefeldin A (BFA), an inhibitor of early secretory pathway trafficking. Coexpression of GABAA receptors with the GABA synthetic enzyme glutamic acid decarboxylase 67 (GAD67) also resulted in an increase in receptor surface levels. GABA treatment failed to promote the surface expression of GABA binding site mutant receptors, which themselves were poorly expressed at the surface. Consistent with an intracellular action of GABA, we show that GABA does not act by stabilizing surface receptors. Furthermore, GABA treatment rescued the surface expression of a receptor construct that was retained within the secretory pathway. Lastly, the lipophilic competitive antagonist (+)bicuculline promoted receptor surface expression, including the rescue of an secretory pathway-retained receptor. Our results indicate that a neurotransmitter can act as a ligand chaperone in the early secretory pathway to regulate the surface expression of its receptor. This effect appears to rely on binding site occupancy, rather than agonist-induced structural changes, since chaperoning is observed with both an agonist and a competitive antagonist. PMID:20580636

Eshaq, Randa S.; Stahl, Letha D.; Stone, Randolph; Smith, Sheryl S.; Robinson, Lucy C.; Leidenheimer, Nancy J.

2010-01-01

147

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

PubMed

The research described here investigates the role played by inhibitory processes in the discriminations made by the nervous system of humans and animals between familiar and unfamiliar and significant and nonsignificant events. This research compared the effects of two inhibitory mediators of gamma-aminobutyric acid (GABA): 1) phenibut, a nonselective agonist of ionotropic GABA(A) and metabotropic GABA(B) receptors and 2) gaboxadol a selective agonist of ionotropic GABA(A) receptors on the process of developing active defensive and inhibitory conditioned reflexes in alert non-immobilized rabbits. It was found that phenibut, but not gaboxadol, accelerates the development of defensive reflexes at an early stage of conditioning. Both phenibut and gaboxadol facilitate the development of conditioned inhibition, but the effect of gaboxadol occurs at later stages of conditioning and is less stable than that of phenibut. The earlier and more stable effects of phenibut, as compared to gaboxadol, on storage in memory of the inhibitory significance of a stimulus may occur because GABA(B) receptors play the dominant role in the development of internal inhibition during an early stage of conditioning. On the other hand this may occur because the participation of both GABA(A) and GABA(B) receptors are essential to the process. We discuss the polyfunctionality of GABA receptors as a function of their structure and the positions of the relevant neurons in the brain as this factor can affect regulation of various types of psychological processes. PMID:19476215

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

2009-05-01

148

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

2014-01-01

149

Inactivity of phosphoethanolamine, an endogenous GABA analog decreased in Alzheimer's disease, at GABA binding sites.  

PubMed

Phosphoethanolamine (PE) is a metabolite of the phospholipid metabolism which is decreased in Alzheimer's disease brain. PE shows a strong structural similarity to the inhibitory neurotransmitter, GABA, and the GABAB receptor partial agonist, 3-amino-propylphosphonic acid. The ability of PE to compete for binding to GABAA and GABAB binding sites was investigated. GABAA sites were studied using [3H]SR-95531 and [3H]muscimol. GABAB sites were studied using [3H]GABA in the presence of isoguvacine to saturate GABAA sites. Total [3H]GABA binding was also examined. PE showed little activity at any of the GABA binding sites investigated. PE was most potent at GABAB sites, but the IC50 of 7.5 +/- 0.75 mM was considerably higher than its maximal physiologic concentration of approximately 1.5 mM. The efficient exclusion of PE from GABA binding sites may be an important physiologic mechanism in the control of inhibitory neurotransmission. The structural basis for this exclusion is discussed in reference to the GABAB partial agonist 3-amino-propylphosphonic acid. PMID:7791524

Klunk, W E; Debnath, M L; McClure, R J; Pettegrew, J W

1995-01-01

150

GABA receptors in brain development, function, and injury.  

PubMed

This review presents a brief overview of the ?-aminobutyric acid (GABA) system in the developing and mature central nervous system (CNS) and its potential connections to pathologies of the CNS. ?-aminobutyric acid (GABA) is a major neurotransmitter expressed from the embryonic stage and throughout life. At an early developmental stage, GABA acts in an excitatory manner and is implicated in many processes of neurogenesis, including neuronal proliferation, migration, differentiation, and preliminary circuit-building, as well as the development of critical periods. In the mature CNS, GABA acts in an inhibitory manner, a switch mediated by chloride/cation transporter expression and summarized in this review. GABA also plays a role in the development of interstitial neurons of the white matter, as well as in oligodendrocyte development. Although the underlying cellular mechanisms are not yet well understood, we present current findings for the role of GABA in neurological diseases with characteristic white matter abnormalities, including anoxic-ischemic injury, periventricular leukomalacia, and schizophrenia. Development abnormalities of the GABAergic system appear particularly relevant in the etiology of schizophrenia. This review also covers the potential role of GABA in mature brain injury, namely transient ischemia, stroke, and traumatic brain injury/post-traumatic epilepsy. PMID:24820774

Wu, Connie; Sun, Dandan

2015-04-01

151

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.

2014-01-01

152

Characterization of GABA receptors.  

PubMed

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 or ion-channel binding sites. PMID:24510754

Enna, S J; McCarson, Kenneth E

2013-01-01

153

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

PubMed

gamma-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. OsGABA-T expression is induced by blast fungus infection, mechanical wounding and ultraviolet radiation in rice leaves and is not detected in normal rice organs. This gene is also induced by defense signal molecules such as salicylic acid and abscisic acid, but not by jasmonic acid. Our data suggest that OsGABA-T (GABA shunt) may play a role in restricting the levels of cell death during the host-pathogen interaction. PMID:16896530

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

2006-11-01

154

A Gut Feeling about GABA: Focus on GABAB Receptors  

PubMed Central

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

Hyland, Niall P.; Cryan, John F.

2010-01-01

155

Benzodiazepines modulate GABAA receptors by regulating the preactivation step after GABA binding.  

PubMed

GABA(A) receptors (GABA(A)Rs) composed of ??? subunits are allosterically modulated by the benzodiazepines (BDZs). Agonists at the BDZ binding site potentiate submaximal GABA responses by increasing the apparent affinity of GABA(A)Rs for GABA. Although BDZs were initially thought to affect the binding of GABA agonists, recent studies suggest an effect on receptor gating; however, the involvement of preactivation steps in the modulation by BDZs has not been considered. Consequently, we examined whether BDZ agonists could exert their modulatory effect by displacing the equilibrium between resting and preactivated states of recombinant ?1?2?2 GABA(A)Rs expressed in Xenopus oocytes. For GABA and the partial agonists 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol and piperidine-4-sulfonic acid, we examined BDZ modulation using a simple three-step model incorporating agonist binding, receptor preactivation, and channel opening. The model accounted for diazepam modulation simply by increasing the preactivation constant by approximately fourfold. To assess whether BDZs preferentially affected a specific GABA binding site, pentameric concatamers were used. This demonstrated that single GABA-binding site mutant receptors were equally sensitive to modulation by BDZs compared with wild-type counterparts. Overall, our results suggest that BDZs affect the preactivation step to cause a global conformational rearrangement of GABA(A)Rs, thereby modulating receptor function. PMID:22539833

Gielen, Marc C; Lumb, Michael J; Smart, Trevor G

2012-04-25

156

Relation of the [ 3H]?-hydroxybutyric acid (ghb) binding site to the ?-aminobutyric acid b (gaba b) receptor in rat brain  

Microsoft Academic Search

Hydroxybutyric acid (GHB) is a naturally occurring compound that has the ability to induce generalized absence seizures when given to animals. GHB has been hypothesized to induce this effect via the postsynaptic ?-aminobutyric acidB (GABAB) receptor. We sought to test this hypothesis by examining the affinity of GABAB agonists and antagonists for the [3H]GHB binding site, the affinity of GHB

O. Carter Snead

1996-01-01

157

Bioactivity-guided isolation of GABA(A) receptor modulating constituents from the rhizomes of Actaea racemosa.  

PubMed

Black cohosh (Actaea racemosa) is a frequently used herbal remedy for the treatment of mild climacteric symptoms. In the present study, the modulation of ?-aminobutryic acid (GABA)-induced chloride currents (I(GABA)) through GABA type A (GABA(A)) receptors by black cohosh extracts and isolated compounds was investigated. GABA(A) receptors, consisting of ?(1), ?(2), and ?(2S) subunits, were expressed in Xenopus laevis oocytes, and potentiation of I(GABA) was measured using the two-microelectrode voltage clamp technique. In a bioactivity-guided isolation procedure the positive modulation of I(GABA) could be restricted to the plant terpenoid fractions, resulting in the isolation of 11 cycloartane glycosides, of which four significantly (p < 0.05) enhanced I(GABA). The most efficient effect was observed for 23-O-acetylshengmanol 3-O-?-d-xylopyranoside (4, 100 ?M), enhancing I(GABA) by 1692 ± 201%, while actein (1), cimigenol 3-O-?-d-xylopyranoside (6), and 25-O-acetylcimigenol 3-O-?-l-arabinopyranoside (8) were significantly less active. In the absence of GABA, only 4 induced small (not exceeding 1% of I(GABA-max)) chloride inward currents through GABA(A) receptors. It is hypothesized that the established positive allosteric modulation of GABA(A) receptors may contribute to beneficial effects of black cohosh extracts in the treatment of climacteric symptoms. PMID:21082802

Cicek, Serhat S; Khom, Sophia; Taferner, Barbara; Hering, Steffen; Stuppner, Hermann

2010-12-27

158

Different Subtypes of GABA-A Receptors Are Expressed in Human, Mouse and Rat T Lymphocytes  

PubMed Central

?-aminobutyric acid (GABA) is the most prominent neuroinhibitory transmitter in the brain, where it activates neuronal GABA-A receptors (GABA-A channels) located at synapses and outside of synapses. The GABA-A receptors are primary targets of many clinically useful drugs. In recent years, GABA has been shown to act as an immunomodulatory molecule. We have examined in human, mouse and rat CD4+ and CD8+ T cells which subunit isoforms of the GABA-A channels are expressed. The channel physiology and drug specificity is dictated by the GABA-A receptor subtype, which in turn is determined by the subunit isoforms that make the channel. There were 5, 8 and 13 different GABA-A subunit isoforms identified in human, mouse and rat CD4+ and CD8+ T cells, respectively. Importantly, the ?2 subunit that imposes benzodiazepine sensitivity on the GABA-A receptors, was only detected in the mouse T cells. Immunoblots and immunocytochemistry showed abundant GABA-A channel proteins in the T cells from all three species. GABA-activated whole-cell transient and tonic currents were recorded. The currents were inhibited by picrotoxin, SR95531 and bicuculline, antagonists of GABA-A channels. Clearly, in both humans and rodents T cells, functional GABA-A channels are expressed but the subtypes vary. It is important to bear in mind the interspecies difference when selecting the appropriate animal models to study the physiological role and pharmacological properties of GABA-A channels in CD4+ and CD8+ T cells and when selecting drugs aimed at modulating the human T cells function. PMID:22927941

Jin, Zhe; Birnir, Bryndis

2012-01-01

159

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

1993-01-01

160

GABA in regulation of communicative activity and sexual motivation of male mice with different psychoemotional status.  

PubMed

We studied the effects of drugs modulating GABA content in the brain on communicative activity and sexual motivation of male mice. The effects of the drug depended on animal genotype and initial psychoemotional status. Aminooxyacetic acid elevating GABA content did not modulate communicative activity of intact males, reduced it in aggressive animals, restored in anxious animals, and promoted exhaustion of sexual motivation in anxious animals. Thiosemicarbazide reducing GABA level produced an anxiogenic effect and destabilized sexual motivation in intact males. PMID:17970208

Amikishieva, A V

2007-02-01

161

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.

1993-01-01

162

Alterations of cortical GABA neurons and network oscillations in schizophrenia.  

PubMed

The hypothesis that alterations of cortical inhibitory gamma-aminobutyric acid (GABA) neurons are a central element in the pathology of schizophrenia has emerged from a series of postmortem studies. How such abnormalities may contribute to the clinical features of schizophrenia has been substantially informed by a convergence with basic neuroscience studies revealing complex details of GABA neuron function in the healthy brain. Importantly, activity of the parvalbumin-containing class of GABA neurons has been linked to the production of cortical network oscillations. Furthermore, growing knowledge supports the concept that gamma band oscillations (30-80 Hz) are an essential mechanism for cortical information transmission and processing. Herein we review recent studies further indicating that inhibition from parvalbumin-positive GABA neurons is necessary to produce gamma oscillations in cortical circuits; provide an update on postmortem studies documenting that deficits in the expression of glutamic acid decarboxylase67, which accounts for most GABA synthesis in the cortex, are widely observed in schizophrenia; and describe studies using novel, noninvasive approaches directly assessing potential relations between alterations in GABA, oscillations, and cognitive function in schizophrenia. PMID:20556669

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

2010-08-01

163

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

PubMed Central

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

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

2014-01-01

164

Ionic Mechanisms of Neuronal Excitation by Inhibitory GABA_A Receptors  

NASA Astrophysics Data System (ADS)

Gamma-aminobutyric acid A (GABA_A) receptors are the principal mediators of synaptic inhibition, and yet when intensely activated, dendritic GABA_A receptors excite rather than inhibit neurons. The membrane depolarization mediated by GABA_A receptors is a result of the differential, activity-dependent collapse of the opposing concentration gradients of chloride and bicarbonate, the anions that permeate the GABA_A ionophore. Because this depolarization diminishes the voltage-dependent block of the N-methyl-D-aspartate (NMDA) receptor by magnesium, the activity-dependent depolarization mediated by GABA is sufficient to account for frequency modulation of synaptic NMDA receptor activation. Anionic gradient shifts may represent a mechanism whereby the rate and coherence of synaptic activity determine whether dendritic GABA_A receptor activation is excitatory or inhibitory.

Staley, Kevin J.; Soldo, Brandi L.; Proctor, William R.

1995-08-01

165

GABA stimulation and blockade in the hypothalamus and midbrain: effects on feeding and locomotor activity.  

PubMed

Microinjections of the gamma-aminobutyric acid (GABA) antagonist, bicuculline methiodide (BM) (100 ng), into the anterolateral hypothalamus (LH) increased ingestion of sweet milk. A subsequent injection of BM 48 hrs. later produced a type of kindling effect consisting of feeding related automatisms, such as gnawing and biting. The behavioral effects of injections of 100 ng of GABA into the LH were variable. GABA injections into the ventromedial hypothalamus (VMH) reliably increased food intake. GABA injections into the origin of the nigrostriatal dopamine (DA) neurons in the substantia nigra (SN) suppressed it. Similar injections into the origin of the mesolimbic DA cells in the ventral tegmental area (VTA) had no effect on feeding behavior. Following BM injections into the SN, a moderate increase in tilt box activity was observed. A second injection of the GABA blocker 6 days later exaggerated this effect. Short latency extreme hyperactivation was accompanied by unidirectional barrel rolling which persisted until blocked by local injections of GABA. PMID:594097

Kelly, J; Alheid, G F; Newberg, A; Grossman, S P

1977-12-01

166

Aza-THIP and related analogues of THIP as GABA C antagonists.  

PubMed

The potency of a series of eight compounds structurally related with 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP), a potent GABA(A) partial agonist exhibiting GABA(C) rho(1) antagonist effect (K(i)=25 microM), was determined electrophysiologically using homomeric human GABA(C) rho(1) receptors expressed in Xenopus oocytes. Protolytic properties (pK(a) values for the acidic bioisosteric groups) and the presence of steric bulk in the molecules appear to be structural parameters of importance for blockade of the GABA(C) rho(1) receptor. Within this series of moderately potent GABA(C) antagonists, only 4,5,6,7-tetrahydropyrazolo[5,4-c]pyridin-3-ol (Aza-THIP) does not interact detectably with GABA(A) receptors, and Aza-THIP has the potential of being a useful tool for molecular and behavioural pharmacological studies. PMID:14604650

Krehan, Dorte; Frølund, Bente; Ebert, Bjarke; Nielsen, Birgitte; Krogsgaard-Larsen, Povl; Johnston, Graham A R; Chebib, Mary

2003-11-17

167

Alterations in GABA-related transcriptome in the dorsolateral prefrontal cortex of subjects with schizophrenia  

Microsoft Academic Search

In subjects with schizophrenia, impairments in working memory are associated with dysfunction of the dorsolateral prefrontal cortex (DLPFC). This dysfunction appears to be due, at least in part, to abnormalities in ?-aminobutyric acid (GABA)-mediated inhibitory circuitry. To test the hypothesis that altered GABA-mediated circuitry in the DLPFC of subjects with schizophrenia reflects expression changes of genes that encode selective presynaptic

T Hashimoto; D Arion; T Unger; J G Maldonado-Avilés; H M Morris; D W Volk; K Mirnics; D A Lewis; DA Lewis

2008-01-01

168

Mechanisms of sleep induction by GABA(A) receptor agonists.  

PubMed

Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system. GABA(A) receptors are pentameric complexes that function as ligand-gated chloride ion channels. Two types of inhibitory neurotransmission are mediated via GABA(A) receptors. Phasic inhibition results from the activation of receptors at the synapse by intermittent release of high concentrations of GABA from presynaptic terminals. Tonic inhibition, in contrast, is mediated by the continuous activation of receptors located outside the synaptic cleft by low concentrations of ambient GABA. These "extrasynaptic" receptors have a higher affinity for GABA and slower rates of desensitization and deactivation than do the classical "synaptic" receptors. A variety of subunit families make up GABA(A) receptors; a total of 19 distinct subunits have been cloned. This diversity in subunit composition results in substantial anatomical, functional, and pharmacologic heterogeneity. Receptors containing the alpha1, alpha2, or alpha3 subunits with gamma2 are usually found at synapses and are sensitive to benzodiazepines and zolpidem, whereas alpha4 and alpha6 subunits are often found with delta and play a role in extrasynaptic receptors (in thalamus and dentate), as does the alpha5 subunit (in CA1). The alpha4betadelta receptors are insensitive to benzodiazepines and zolpidem, but show high sensitivity to other sedative-hypnotic drugs, including ethanol and the novel hypnotic drug gaboxadol (THIP). This review will examine the role of heterogeneity of GABA(A) receptors, and recent research demonstrating subunit-dependent modulation of receptors by novel pharmacologic agents will be discussed. PMID:17539703

Harrison, Neil L

2007-01-01

169

Downregulation of GABA[Subscript A] Receptor Protein Subunits a6, ß2, d, e, ?2, ?, and ?2 in Superior Frontal Cortex of Subjects with Autism  

ERIC Educational Resources Information Center

We measured protein and mRNA levels for nine gamma-aminobutyric acid A (GABA[subscript A]) receptor subunits in three brain regions (cerebellum, superior frontal cortex, and parietal cortex) in subjects with autism versus matched controls. We observed changes in mRNA for a number of GABA[subscript A] and GABA[subscript B] subunits and overall…

Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Rustan, Oyvind G.; Rooney, Robert J.; Thuras, Paul D.

2014-01-01

170

Changes in rectal temperature and ECoG spectral power of sensorimotor cortex elicited in conscious rabbits by i.c.v. injection of GABA, GABA(A) and GABA(B) agonists and antagonists.  

PubMed

1. In order to ascertain whether both GABA(A) and GABA(B), or only GABA(B) receptors, directly modulate thermoregulation in conscious rabbits, GABA(A)/GABA(B) agonist and antagonist agents were injected intracerebroventricularly in conscious rabbits while monitoring changes in rectal temperature (RT), gross motor behaviour (GMB) and electrocorticogram (ECoG) power spectra (ps) from sensorimotor cortices. 2. GABA (48 micromol), nipecotic acid (50 nmol), THIP (60 nmol), muscimol (18 nmol) and baclofen (8 nmol) induced hypothermia (-deltaRTmax values of 1.70+/-0.1, 1.4+/-0.2, 1.0+/-0.4, 1.1+/-0.2 and 1.6+/-0.3 degrees C, respectively), accompanied by inhibition of GMB and ECoG synchronization. THIP increased ps at delta frequency band (1.1-3.3 Hz), while GABA, nipecotic acid, muscimol and baclofen did the same at both delta and (4.6-6.5 Hz) frequency bands. ECoG ps changes were concomitant or even preceded hypothermia. 3. Bicuculline (1.8 nmol) induced hyperthermia (deltaRTmax 1.2+/-0.5 degrees C) and slight excitation of GMB, while CGP35348 (1.2 micromol) did not affect RT nor GMB. Both compounds did not affect ECoG ps. 4. Bicuculline potentiated muscimol-induced hypothermia, inhibition of GMB and synchronization of ECoG, while CGP35348 fully antagonized these effects. 5. In conclusion, the present results, while confirming the prevailing role of GABA(B), also outline a direct involvement of GABA(A) receptors in the central mechanisms of thermoregulation. Ascending inhibition towards discrete cortical areas controlling muscular activity and thermogenesis may result from GABA receptor activation in neurones proximal to the ventricles, thus contributing to hypothermia, although hypothermia-induced reduction of neuronal activity of these cortical areas cannot be ruled out. PMID:14662729

Frosini, Maria; Valoti, Massimo; Sgaragli, Giampietro

2004-01-01

171

Identification of GABA receptors in chick cornea  

PubMed Central

Purpose The cornea has an important role in vision, is highly innervated and many neurotransmitter receptors are present, e.g., muscarine, melatonin, and dopamine receptors. ?-aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the retina and central nervous system, but it is unknown whether GABA receptors are present in cornea. The aim of this study was to determine if GABA receptors are located in chick cornea. Methods Corneal tissues were collected from 25, 12-day-old chicks. Real time PCR, western blot, and immunohistochemistry were used to determine whether alpha1 GABAA, GABAB, and rho1 GABAC receptors were expressed and located in chick cornea. Results Corneal tissue was positive for alpha1 GABAA and rho1 GABAC receptor mRNA (PCR) and protein (western blot) expression but was negative for GABAB receptor mRNA and protein. Alpha1 GABAA and rho1 GABAC receptor protein labeling was observed in the corneal epithelium using immunohistochemistry. Conclusions These investigations clearly show that chick cornea possesses alpha1 GABAA, and rho1 GABAC receptors, but not GABAB receptors. The purpose of the alpha1 GABAA and rho1 GABAC receptors in cornea is a fascinating unexplored question. PMID:22605922

Cheng, Zhen-Ying; Chebib, Mary

2012-01-01

172

Disappearance of gamma-aminobutyric acid (GABA)B receptor-mediated cAMP suppression in mouse cerebrum after chronic treatment with morphine.  

PubMed

The effects of chronic morphine administration (dependence) and naloxone-induced withdrawal on cerebral GABAB receptor and its signal transduction system were examined. Alterations in receptor affinity and number and in the amount of Gi protein were determined by radioligand binding assay and immunoblotting with Gi protein antibody, respectively. [3H]GABA binding to GABAB receptors in the brain of morphine-dependent and -withdrawn mice showed no significant change in either high or low affinity sites. Similarly, no alterations were noted in the coupling between GABAB receptor and Gi protein or in the amount of protein. However, the suppressive effect of baclofen, a GABAB agonist, on forskolin-stimulated cAMP formation in cerebral cortical slices of these animals was abolished. These results indicate that chronic morphine administration may induce functional deterioration in the coupling between Gi protein and the adenylate cyclase system. PMID:8950321

Ichida, T; Kuriyama, K

1996-01-01

173

Conformationally sensitive proximity of extracellular loops 2 and 4 of the ?-aminobutyric acid (GABA) transporter GAT-1 inferred from paired cysteine mutagenesis.  

PubMed

The sodium- and chloride-coupled GABA transporter GAT-1 is a member of the neurotransmitter:sodium:symporters, which are crucial for synaptic transmission. Structural work on the bacterial homologue LeuT suggests that extracellular loop 4 closes the extracellular solvent pathway when the transporter becomes inward-facing. To test whether this model can be extrapolated to GAT-1, cysteine residues were introduced at positions 359 and 448 of extracellular loop 4 and transmembrane helix 10, respectively. Treatment of HeLa cells, expressing the double cysteine mutant S359C/K448C with the oxidizing reagent copper(II)(1,10-phenantroline)3, resulted in a significant inhibition of [(3)H]GABA transport. However, transport by the single cysteine mutant S359C was also inhibited by the oxidant, whereas its activity was almost 4-fold stimulated by dithiothreitol. Both effects were attenuated when the conserved cysteine residues, Cys-164 and/or Cys-173, were replaced by serine. These cysteines are located in extracellular loop 2, the role of which in the structure and function of the eukaryotic neurotransmitter:sodium:symporters remains unknown. The inhibition of transport of S359C by the oxidant was markedly reduced under conditions expected to increase the proportion of inward-facing transporters, whereas the reactivity of the mutants to a membrane-impermeant sulfhydryl reagent was not conformationally sensitive. Our data suggest that extracellular loops 2 and 4 come into close proximity to each other in the outward-facing conformation of GAT-1. PMID:25339171

Hilwi, Maram; Dayan, Oshrat; Kanner, Baruch I

2014-12-01

174

Molecular mechanisms supporting a paracrine role of GABA in rat adrenal medullary cells  

PubMed Central

GABA is known to produce membrane depolarization and secretion in adrenal medullary (AM) cells in various species. However, whether the GABAergic system is intrinsic or extrinsic or both in the adrenal medulla and the role that GABA plays are controversial. Therefore, these issues were addressed by combining a biochemical and functional analysis. Glutamic acid decarboxylase (GAD), a GABA synthesizing enzyme, and vesicular GABA transporter (VGAT) were expressed in rat AM cells at the mRNA and protein levels, and the adrenal medulla had no nerve fibre-like structures immunoreactive to an anti-GAD Ab. The double staining for VGAT and chromogranin A indicates that GABA was stored in chromaffin granules. The ?1, ?3, ?2/3, ?2 and ? subunits of GABAA receptors were identified in AM cells at the mRNA and protein levels. Pharmacological properties of GABA-induced Cl? currents, immunoprecipitation experiments and immunocytochemistry indicated the expression of not only ?2-, but also ?-containing GABAA receptors, which have higher affinities for GABA and neurosteroids. Expression of GATs, which are involved in the clearance of GABA at GABAergic synapses, were conspicuously suppressed in the adrenal medulla, compared with expression levels of GABAA receptors. Increases in Ca2+ signal in AM cells evoked trans-synaptically by nerve stimulation were suppressed during the response to GABA, and this suppression was attributed to the shunt effect of the GABA-induced increase in conductance. Overall Ca2+ responses to electrical stimulation and GABA in AM cells were larger or smaller than those to electrical stimulation alone, depending on the frequency of stimulation. The results indicate that GABA functions as a paracrine in rat AM cells and this function may be supported by the suppression of GAT expression and the expression of not only ?2-, but also ?-GABAA receptors. PMID:18755746

Matsuoka, Hidetada; Harada, Keita; Endo, Yutaka; Warashina, Akira; Doi, Yoshiaki; Nakamura, Jun; Inoue, Masumi

2008-01-01

175

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

PubMed

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

2011-05-01

176

A comparative density functional theory study of electronic structure and optical properties of ?-aminobutyric acid and its cocrystals with oxalic and benzoic acid  

NASA Astrophysics Data System (ADS)

In this letter, we study the electronic structure and optical properties of the active medicinal component ?-aminobutyric acid (GABA) and its cocrystals with oxalic (OXA) and benzoic (BZA) acid by means of the density functional theory formalism. It is shown that the cocrystallization strongly weakens the zwitterionic character of the GABA molecule leading to striking differences among the electronic band structures and optical absorption spectra of the GABA crystal and GABA:OXA, GABA:BZA cocrystals, originating from distinct sets of hydrogen bonds. Calculated band widths and ?-sol band gap estimates indicate that both GABA and GABA:OXA, GABA:BZA cocrystals are indirect gap insulators.

da Silva Filho, J. G.; Freire, V. N.; Caetano, E. W. S.; Ladeira, L. O.; Fulco, U. L.; Albuquerque, E. L.

2013-11-01

177

Decreased intracellular GABA levels contribute to spinal cord stimulation-induced analgesia in rats suffering from painful peripheral neuropathy: the role of KCC2 and GABA(A) receptor-mediated inhibition.  

PubMed

Elevated spinal extracellular ?-aminobutyric acid (GABA) levels have been described during spinal cord stimulation (SCS)-induced analgesia in experimental chronic peripheral neuropathy. Interestingly, these increased GABA levels strongly exceeded the time frame of SCS-induced analgesia. In line with the former, pharmacologically-enhanced extracellular GABA levels by GABA(B) receptor agonists in combination with SCS in non-responders to SCS solely could convert these non-responders into responders. However, similar treatment with GABA(A) receptor agonists and SCS is known to be less efficient. Since K? Cl? cotransporter 2 (KCC2) functionality strongly determines proper GABA(A) receptor-mediated inhibition, both decreased numbers of GABA(A) receptors as well as reduced KCC2 protein expression might play a pivotal role in this loss of GABA(A) receptor-mediated inhibition in non-responders. Here, we explored the mechanisms underlying both changes in extracellular GABA levels and impaired GABA(A) receptor-mediated inhibition after 30 min of SCS in rats suffering from partial sciatic nerve ligation (PSNL). Immediately after cessation of SCS, a decreased spinal intracellular dorsal horn GABA-immunoreactivity was observed in responders when compared to non-responders or sham SCS rats. One hour later however, GABA-immunoreactivity was already increased to similar levels as those observed in non-responder or sham SCS rats. These changes did not coincide with alterations in the number of GABA-immunoreactive cells. C-Fos/GABA double-fluorescence clearly confirmed a SCS-induced activation of GABA-immunoreactive cells in responders immediately after SCS. Differences in spinal dorsal horn GABA(A) receptor-immunoreactivity and KCC2 protein levels were absent between all SCS groups. However, KCC2 protein levels were significantly decreased compared to sham PSNL animals. In conclusion, reduced intracellular GABA levels are only present during the time frame of SCS in responders and strongly point to a SCS-mediated on/off GABAergic release mechanism. Furthermore, a KCC2-dependent impaired GABA(A) receptor-mediated inhibition seems to be present both in responders and non-responders to SCS due to similar KCC2 and GABA(A) receptor levels. PMID:22107704

Janssen, S P; Gerard, S; Raijmakers, M E; Truin, M; Van Kleef, M; Joosten, E A

2012-01-01

178

Thalamic nuclei that project to reptilian telencephalon lack GABA and GAD immunoreactive neurons and puncta.  

PubMed

Brains of reptiles, Caiman crocodilus, were processed by standard immunocytochemical methodology using a polyclonal antibody to gamma-aminobutyric acid (GABA) raised in rabbit and a polyclonal antibody to glutamic acid decarboxylase (GAD) raised in sheep. No GABA(+) or GAD(+) cells or puncta were observed over any thalamic nucleus known to project to the telencephalon in Caiman. These findings suggest that all thalamic nuclei that project to the telencephalon in Caiman lack intrinsic cells and presumably direct inhibitory input mediated by GABA. PMID:3167560

Pritz, M B; Stritzel, M E

1988-08-01

179

GABA transporter GAT1 prevents spillover at proximal and distal GABA synapses onto primate prefrontal cortex neurons.  

PubMed

The plasma membrane GABA transporter GAT1 is thought to mediate uptake of synaptically released GABA. In the primate dorsolateral prefrontal cortex (DLPFC), GAT1 expression changes significantly during development and in schizophrenia. The consequences of such changes, however, are not well understood because GAT1's role has not been investigated in primate neocortical circuits. We thus studied the effects of the GAT1 blocker 1,2,5,6-tetrahydro-1-[2-[[(diphenylmethylene)amino]oxy]ethyl]-3-pyridinecarboxylic acid hydrochloride (NO711) on GABA transmission onto pyramidal neurons of monkey DLPFC. As in rat cortex, in monkey DLPFC NO711 did not substantially alter miniature GABA transmission, suggesting that GAT1 does not regulate single-synapse transmission. In rat cortical circuits, between-synapse GABA spillover produced by NO711 clearly prolongs the inhibitory postsynaptic currents, but whether NO711 also prolongs the inhibitory postsynaptic potentials (IPSPs) is unclear. Moreover, whether spillover differentially affects perisomatic versus dendritic inputs has not been examined. Here we found that NO711 prolonged the GABAA receptor-mediated IPSPs (GABAAR-IPSPs) evoked by stimulating perisomatic synapses. Dendritic, but not perisomatic, synapse stimulation often elicited a postsynaptic GABAB receptor-mediated IPSP that was enhanced by NO711. Blocking GABAB receptors revealed that NO711 prolonged the GABAAR-IPSPs evoked by stimulation of dendrite-targeting inputs. We conclude that a major functional role for GAT1 in primate cortical circuits is to prevent the effects of GABA spillover when multiple synapses are simultaneously active. Furthermore, we report that, at least in monkey DLPFC, GAT1 similarly restricts GABA spillover onto perisomatic or dendritic inputs, critically controlling the spatiotemporal specificity of inhibitory inputs onto proximal or distal compartments of the pyramidal cell membrane. PMID:19073797

Gonzalez-Burgos, Guillermo; Rotaru, Diana C; Zaitsev, Aleksey V; Povysheva, Nadezhda V; Lewis, David A

2009-02-01

180

Actions of insecticides on the insect GABA receptor complex.  

PubMed

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 +/- 2.9 nM and a Bmax value of 1770 +/- 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. PMID:1653332

Bermudez, I; Hawkins, C A; Taylor, A M; Beadle, D J

1991-01-01

181

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))

1991-01-01

182

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.

2014-01-01

183

Bi-directional transport of GABA in human embryonic kidney (HEK-293) cells stably expressing the rat GABA transporter GAT-1  

PubMed Central

Bi-directional GABA-transport was studied by performing uptake and superfusion experiments in human embryonic kidney 293 cells stably expressing the rat GABA transporter rGAT-1.KM and Vmax values for [3H]-GABA uptake were 11.7±1.8??M and 403±55?pmol?min?1 10?6 cells (n=9), respectively.Kinetic analysis of outward transport was performed by pre-labelling the cells with increasing concentrations of [3H]-GABA and triggering outward transport with 333??M GABA. Approximate apparent KM and Vmax values were 12?mM and 50?pmol?min?1 10?6 cells, respectively.GABA re-uptake inhibitors (RI; e.g. tiagabine), as well as, substrates of the rGAT-1 (e.g. GABA, nipecotic acid) concentration dependently decreased [3H]-GABA uptake and increased efflux of [3H]-GABA from pre-labelled cells. The IC50 values for inhibiting uptake and the EC50 values for increasing efflux were significantly correlated (r2=0.99).On superfusion, RI antagonized the efflux-enhancing effect of the substrates. The effect of the latter was markedly augmented in the presence of ouabain (100??M), whereas the effect of RI remained unchanged. The most likely explanation for the release enhancing effect of RI is interruption of ongoing re-uptake.The structural GABA-analogue 2,4-diamino-n-butyric acid (DABA) exhibited a bell-shaped concentration response curve on [3H]-GABA efflux with the maximum at 1?mM, and displayed a deviation from the sigmoidal inhibition curve in uptake experiments in the same concentration range. At concentrations below 1?mM, DABA inhibited [3H]-GABA uptake non-competitively, while at 1?mM and above the inhibition of uptake followed a competitive manner.The results provide information of GABA inward and outward transport, and document a complex interaction of the rGAT-1 with its substrate DABA. PMID:11786484

Sitte, Harald H; Singer, Ernst A; Scholze, Petra

2002-01-01

184

Competitive antagonism of insect GABA receptors by 4-substituted 5-(4-piperidyl)-3-isothiazolols.  

PubMed

?-Aminobutyric acid (GABA) receptors are important targets of parasiticides/insecticides. Several 4-substituted analogs of the partial GABAA receptor agonist 5-(4-piperidyl)-3-isothiazolol (Thio-4-PIOL) were synthesized and examined for their antagonism of insect GABA receptors expressed in Drosophila S2 cells or Xenopus oocytes. Thio-4-PIOL showed weak antagonism of three insect GABA receptors. The antagonistic activity of Thio-4-PIOL was enhanced by introducing bicyclic aromatic substituents into the 4-position of the isothiazole ring. The 2-naphthyl and the 3-biphenylyl analogs displayed antagonist potencies with half maximal inhibitory concentrations in the low micromolar range. The 2-naphthyl analog induced a parallel rightward shift of the GABA concentration-response curve, suggesting competitive antagonism by these analogs. Both compounds exhibited weak insecticidal activities against houseflies. Thus, the orthosteric site of insect GABA receptors might be a potential target site of insecticides. PMID:25112550

Liu, Genyan; Furuta, Kenjiro; Nakajima, Hiromitsu; Ozoe, Fumiyo; Ozoe, Yoshihisa

2014-09-01

185

Excitatory Synaptic Responses Mediated by GABA_A Receptors in the Hippocampus  

NASA Astrophysics Data System (ADS)

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

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

1991-09-01

186

Drosophila melanogaster GRD and LCCH3 subunits form heteromultimeric GABA-gated cation channels  

PubMed Central

In addition to its action as a fast inhibitory neurotransmitter, ?-aminobutyric acid (GABA) is thought to mediate excitatory action by activating cation currents in some cell types in invertebrates. However, to date no GABA receptor capable of mediating such action has been identified at the molecular level in insects. Using a systematic expression screening approach, we found that the Drosophila ligand-gated ion channel subunits GRD and LCCH3 combine to form cation-selective GABA-gated ion channels when coexpressed in Xenopus laevis oocytes. The heteromultimeric receptor is activated by GABA (EC50=4.5 ?M), muscimol (EC50=4.8 ?M) and trans-4-aminocrotonic acid (EC50=104.5 ?M), and partially by cis-4-aminocrotonic acid (EC50=106.3 ?M). Picrotoxin effectively blocked the GABA-gated channel (IC50=0.25 ?M), but bicuculline, TPMTA, dieldrin and lindane did not. The benzodiazepines flunitrazepam and diazepam did not potentiate the GABA-evoked current. Our data suggest that heteromultimeric channels composed of GRD and LCCH3 subunits form GABA-gated cation channels in insects. PMID:15148245

Gisselmann, Günter; Plonka, Justina; Pusch, Hermann; Hatt, Hanns

2004-01-01

187

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: antoni.kowalski@umed.lodz.pl [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: ludmila.zylinska@umed.lodz.pl [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: tomasz.boczek@umed.lodz.pl [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: elzbieta.rebas@umed.lodz.pl [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)

2011-08-12

188

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

2014-01-01

189

Effects of tea components on the response of GABA(A) receptors expressed in Xenopus Oocytes.  

PubMed

To study the effects of tea components on ionotropic gamma-aminobutyric acid (GABA) receptor response, ionotropic GABA receptors (GABA(A) receptors) were expressed in Xenopus oocytes by injecting cRNAs synthesized from cloned cDNAs of the alpha(1) and beta(1) subunits of the bovine receptors, and their electrical responses were measured by a voltage clamping method. Extracts of green tea, black tea, and oolong tea in an aqueous solution induced the GABA-elicited response, which showed that these teas contain GABA, whereas coffee does not. Caffeine weakly inhibited the response in a competitive manner (K(i) = 15 mM), and (+)-catechin inhibited it in a noncompetitive one (K(i) = 1.7 mM). Especially, two catechin derivatives, (-)-epicatechin gallate and (-)-epigallocatechin gallate, inhibited the response strongly. Alcohols such as leaf alcohol or linalool potentiated the response, possibly because their binding to the potentiation site enhances the GABA-binding affinity to GABA(A) receptors when they bind. Extracts of green tea made with ethyl ether, which must contain lipophilic components of green tea, inhibited the response elicited by GABA, possibly because the amounts of caffeine and catechin derivatives were much larger than fragrant alcohols in such extracts of tea. PMID:12083865

Hossain, Sheikh Julfikar; Hamamoto, Koutaro; Aoshima, Hitoshi; Hara, Yukihiko

2002-07-01

190

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.

1987-07-27

191

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

PubMed Central

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.

2013-01-01

192

Genetic heterogeneity for autosomal recessive pyridoxine-dependent seizures  

Microsoft Academic Search

Pyridoxine-dependent seizure (PDS) is a rare autosomal recessive intractable seizure disorder only controlled by a daily supplementation\\u000a of pharmacological doses of pyridoxine (Vitamin B6). Although glutamate decarboxylase utilizes pyridoxal phosphate as a cofactor\\u000a during conversion of the excitatory amino acid, glutamate, to the inhibitory neurotransmitter, ?-amino butyric acid (GABA),\\u000a several studies have failed to demonstrate a linkage to either of

C. L. Bennett; H. M. Huynh; P. F. Chance; I. A. Glass; S. M. Gospe

2005-01-01

193

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

2013-01-01

194

DNA sequence and site of mutation of the GABA receptor of cyclodiene-resistant red flour beetle, Tribolium castaneum  

Microsoft Academic Search

Using polymerase chain reactions (PCR) on cDNA, the DNA sequence of a membrane spanning region of a GABA receptor of the red flour beetle, Tribolium castaneum was identified. The deduced amino acid sequence indicates that its basic structure is similar to the GABA receptor of Rdl type subunits of Drosophila melanogaster and of Blattella germanica. Particularly conserved are M1, M2

Masahiro Miyazaki; Fumio Matsumura; Richard W. Beeman

1995-01-01

195

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.

2007-01-01

196

GABA-B receptors in the PNS have a role in Schwann cells differentiation?  

PubMed Central

?-aminobutyric acid type B (GABA-B) receptor mediates the inhibitory transmission of ?-aminobutyric acid in the mammalian nervous system, being present in neurons and also in glial cells. Recently the presence of GABA-B has been demonstrated in Schwann cells (SC) suggesting its contribution in regulating the cell fate, maturation, and plasticity. Here, we further support the functional presence of GABA-B receptor in SC plasma membrane. By confocal microscopy immunofluorescence we provide evidences that GABA-B localization on the cell elongated processes correlates with the morphological changes occurring in the differentiated SC. In vivo most of the GABA-B receptors seem to be present in non-myelinating SC, which are committed to ensheath the nociceptive fibers. Therefore, we argue that GABA-B receptors do not control exclusively the in vivo differentiation yielding the myelinating SC, but are also fundamental in regulating the SC plasticity versus the non-myelinating state. Data from the literature and our recent findings corroborate the role of the GABAergic system and GABA-B receptors in the peripheral nervous system, opening new perspectives on the mechanisms controlling the differentiation of SC. PMID:23335881

Procacci, Patrizia; Ballabio, Marinella; Castelnovo, Luca F.; Mantovani, Cristina; Magnaghi, Valerio

2013-01-01

197

Effects of GABA agonists on body temperature regulation in GABA(B(1))-/- mice.  

PubMed

1. Activation of GABA(B) receptors evokes hypothermia in wildtype (GABA(B(1))+/+) but not in GABA(B) receptor knockout (GABA(B(1))-/-) mice. The aim of the present study was to determine the hypothermic and behavioural effects of the putative GABA(B) receptor agonist gamma-hydroxybutyrate (GHB), and of the GABA(A) receptor agonist muscimol. In addition, basal body temperature was determined in GABA(B(1))+/+, GABA(B(1))+/- and GABA(B(1))-/- mice. 2. GABA(B(1))-/- mice were generated by homologous recombination in embryonic stem cells. Correct gene targeting was assessed by Southern blotting, PCR and Western blotting. GABA(B) receptor-binding sites were quantified with radioligand binding. Measurement of body temperature was done using subcutaneous temperature-sensitive chips, and behavioural changes after drug administration were scored according to a semiquantitative scale. 3. GABA(B(1))-/- mice had a short lifespan, probably caused by generalised seizure activity. No histopathological or blood chemistry changes were seen, but the expression of GABA(B(2)) receptor protein was below the detection limit in brains from GABA(B(1))-/- mice, in the absence of changes in mRNA levels. 4. GABA(B) receptor-binding sites were absent in brain membranes from GABA(B(1))-/- mice. 5. GABA(B(1))-/- mice were hypothermic by approximately 1 degrees C compared to GABA(B(1))+/+ and GABA(B(1))+/- mice. 6. Injection of baclofen (9.6 mg kg-1) produced a large reduction in body temperature and behavioural effects in GABA(B(1))+/+ and in GABA(B(1))+/- mice, but GABA(B(1))-/- mice were unaffected. The same pattern was seen after administration of GHB (400 mg kg-1). The GABA(A) receptor agonist muscimol (2 mg kg-1), on the other hand, produced a more pronounced hypothermia in GABA(B(1))-/-mice. In GABA(B(1))+/+ and GABA(B(1))+/- mice, muscimol induced sedation and reduced locomotor activity. However, when given to GABA(B(1))-/- mice, muscimol triggered periods of intense jumping and wild running. 7. It is concluded that hypothermia should be added to the characteristics of the GABAB(1)-/-phenotype. Using this model, GHB was shown to be a selective GABAB receptor agonist. In addition, GABAB(1)-/- mice are hypersensitive to GABAA receptor stimulation, indicating that GABAB tone normally balances GABAA-mediated effects. PMID:12970075

Quéva, Christophe; Bremner-Danielsen, Marianne; Edlund, Anders; Ekstrand, A Jonas; Elg, Susanne; Erickson, Sven; Johansson, Thore; Lehmann, Anders; Mattsson, Jan P

2003-09-01

198

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  

Microsoft Academic Search

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

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

1988-01-01

199

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

SciTech Connect

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

Kamei, Yuka; Tamura, Takayuki [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan)] [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan); Yoshida, Ryo [Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)] [Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Ohta, Shinji [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan)] [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan); Fukusaki, Eiichiro [Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)] [Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Mukai, Yukio, E-mail: y_mukai@nagahama-i-bio.ac.jp [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan)] [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan)

2011-04-01

200

GABA-mediated inhibition of the anaphylactic response in the guinea-pig trachea.  

PubMed Central

1. In sensitized guinea-pigs, the effects of gamma-aminobutyric acid (GABA) and GABAmimetic drugs have been investigated on tracheal segments contracted by cumulative application of an allergen (ovoalbumin, OA) and on serosal mast cells. The same drugs have also been tested on activation of alveolar macrophages isolated from unsensitized guinea-pigs. 2. Superfusion with GABA (1-1000 microM) reduced the contraction intensity of tracheal strips. The effect of GABA (100 microM) was not affected by the carrier blockers, nipecotic acid and beta-alanine (300 microM each). It was mimicked by the GABAB agonist (-)-baclofen (100 microM) but not 3-aminopropanephosphinic acid (100 microM, 3-APA). The GABAA agonist, isoguvacine (100 microM) did not exert any effect. GABA (10 microM)-induced inhibition of tracheal contractions was reduced by the GABAB antagonist, 2-hydroxysaclofen (100 microM, 2-HS), but not by the GABAA antagonist, bicuculline (30 microM). 3. The reduction in contraction intensity induced by GABA (100 microM) was prevented by a 40 min preincubation of tracheal strips with capsaicin (10 microM), but not tetrodotoxin (TTX, 0.3 microM). The effect of GABA (1000 microM) was absent after preincubation with indomethacin (2.8 microM) but unmodified when nordihydroguaiaretic acid (NDGA, 3.3 microM) was used. Finally, removal of the epithelium prevented the GABA effect. 4. Anaphylactic histamine release from serosal mast cells isolated from sensitized animals was not affected either by GABA (10-1000 microM) or the selective receptor agonists (-)-baclofen (0.1-1000 microM) and isoguvacine (10-1000 microM).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7582447

Gentilini, G.; Franchi-Micheli, S.; Mugnai, S.; Bindi, D.; Zilletti, L.

1995-01-01

201

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

NSDL National Science Digital Library

Early in development, synapses with glycine or ?-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)

2001-08-14

202

GABA in regulation of communicative activity and sexual motivation of male mice with different psychoemotional status  

Microsoft Academic Search

We studied the effects of drugs modulating GABA content in the brain on communicative activity and sexual motivation of male\\u000a mice. The effects of the drug depended on animal genotype and initial psychoemotional status. Aminooxyacetic acid elevating\\u000a GABA content did not modulate communicative activity of intact males, reduced it in aggressive animals, restored in anxious\\u000a animals, and promoted exhaustion of

A. V. Amikishieva

2007-01-01

203

Alterations in GABA-related transcriptome in the dorsolateral prefrontal cortex of subjects with schizophrenia  

Microsoft Academic Search

In subjects with schizophrenia, impairments in working memory are associated with dysfunction of the dorsolateral prefrontal cortex (DLPFC). This dysfunction appears to be due, at least in part, to abnormalities in c-aminobutyric acid (GABA)-mediated inhibitory circuitry. To test the hypothesis that altered GABA-mediated circuitry in the DLPFC of subjects with schizophrenia reflects expression changes of genes that encode selective presynaptic

T Hashimoto; D Arion; T Unger; JG Maldonado-Aviles; HM Morris; DW Volk; K Mirnics; DA Lewis

2007-01-01

204

The Impact of Gabapentin Administration on Brain GABA and Glutamate Concentrations: A 7T 1H-MRS Study  

PubMed Central

Gamma-aminobutyric acid (GABA) and glutamate are implicated in numerous neuropsychiatric and substance abuse conditions, but their spectral overlap with other resonances makes them a challenge to quantify in humans. Gabapentin, marketed for the treatment of seizures and neuropathic pain, has been shown to increase in vivo GABA concentration in the brain of both rodents and humans. Gabapentin effects on glutamate are not known. We conducted a gabapentin (900?mg) challenge in healthy human subjects to confirm and explore its effects on GABA and glutamate concentrations, respectively, and to test the ability of single voxel localized proton magnetic resonance spectroscopy (1H-MRS) to reliably measure GABA and glutamate in the visual cortex at the ultra-high magnetic field of 7 Tesla. Reproducibility of GABA and glutamate measurements was determined in a comparison group without drug twice within day and 2 weeks apart. Although GABA concentration changes were small both within day (average 5.6%) and between day (average 4.8%), gabapentin administration was associated with an average increase in GABA concentration of 55.7% (6.9–91.0%). Importantly, drug-induced change in GABA levels was inversely correlated to the individual's baseline GABA level (R2=0.72). Mean glutamate concentrations did not change significantly with or without drug administration. In conclusion, localized 1H-MRS at 7 Tesla can be successfully applied to the measurement of GABA concentration and is sensitive to acute drug-induced changes in cortical GABA. Whether baseline GABA concentrations predict clinical efficacy of gabapentin is an area worthy of exploration. PMID:22871916

Cai, Kejia; Nanga, Ravi PR; Lamprou, Lisa; Schinstine, Claudia; Elliott, Mark; Hariharan, Hari; Reddy, Ravinder; Epperson, C Neill

2012-01-01

205

Noradrenergic control of neuronal firing in cerebellar nuclei: modulation of GABA responses.  

PubMed

The effects of noradrenaline (NA) on inhibitory responses to gamma aminobutyric acid (GABA) in neurones of the deep cerebellar nuclei were studied in vivo in rats, using extracellular single-unit recordings and microiontophoretic drug application. NA application altered GABA-evoked responses in 95 % of the neurones tested, but the effects differed between nuclei. Application of NA depressed GABA responses in the medial (MN) and posterior interpositus (PIN) nuclei, but enhanced GABA responses in the anterior interpositus nucleus (AIN). Comparable proportions of enhancing (57 %) and depressive (43 %) effects were found in the lateral nucleus (LN). The alpha2 noradrenergic receptor agonist clonidine mimicked the depressive effect of NA on GABA responses in MN and PIN and its enhancing effects in AIN and LN, while the alpha2 antagonist yohimbine partially blocked these effects. The beta-adrenergic agonist isoproterenol and antagonist timolol respectively induced and partially blocked enhancements of GABA responses in all nuclei except for LN, where isoproterenol had a weak depressive effect. It is concluded that NA modulates GABA responses by acting on both alpha2 and beta receptors. Activation of these receptors appears to be synergistic in the AIN and opposite in the remaining deep nuclei. These results support the hypothesis that the noradrenergic system participates in all the regulatory functions involving the cerebellum in a specific and differential manner, and suggest that any change in NA content, as commonly observed in ageing or stress, could influence cerebellar activity. PMID:23096094

Di Mauro, Michela; Li Volsi, Guido; Licata, Flora

2013-06-01

206

Single rodent mesohabenular axons release glutamate and GABA.  

PubMed

The lateral habenula (LHb) is involved in reward, aversion, addiction and depression through descending interactions with several brain structures, including the ventral tegmental area (VTA). The VTA provides reciprocal inputs to LHb, but their actions are unclear. Here we show that the majority of rat and mouse VTA neurons innervating LHb coexpress markers for both glutamate signaling (vesicular glutamate transporter 2; VGluT2) and GABA signaling (glutamic acid decarboxylase; GAD, and vesicular GABA transporter; VGaT). A single axon from these mesohabenular neurons coexpresses VGluT2 protein and VGaT protein and, surprisingly, establishes symmetric and asymmetric synapses on LHb neurons. In LHb slices, light activation of mesohabenular fibers expressing channelrhodopsin2 driven by VGluT2 (Slc17a6) or VGaT (Slc32a1) promoters elicits release of both glutamate and GABA onto single LHb neurons. In vivo light activation of mesohabenular terminals inhibits or excites LHb neurons. Our findings reveal an unanticipated type of VTA neuron that cotransmits glutamate and GABA and provides the majority of mesohabenular inputs. PMID:25242304

Root, David H; Mejias-Aponte, Carlos A; Zhang, Shiliang; Wang, Hui-Ling; Hoffman, Alexander F; Lupica, Carl R; Morales, Marisela

2014-11-01

207

Ionotropic GABA Receptors and Distal Retinal ON and OFF Responses.  

PubMed

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

Popova, E

2014-01-01

208

Cocaine inhibition of GABA(A) current: role of dephosphorylation.  

PubMed

Acute cocaine toxicity is frequently associated with seizures. The mechanisms underlying the convulsant effect of cocaine are not well understood. Previously, we have shown that cocaine depresses whole-cell current evoked by gamma-aminobutyric acid (GABA) in hippocampal neurons freshly isolated from rats. Cocaine's effect was voltage-independent and concentration-dependent. In the present study, using whole-cell patch-clamp recording on rat neurons freshly isolated from hippocampus, we examined the intracellular mechanisms involved in cocaine's action. Increasing intracellular Ca(2+) concentration ([Ca]i) from 0.01 to 5 microM strongly increased the depressant effect of cocaine. By contrast, 1-[N, O-bis (5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN-62), a specific antagonist of Ca/calmodulin-dependent protein kinase (CaMKII), attenuated or enhanced cocaine's action in different neurons: in three out of nine neurons dialysed with 5 microM KN-62,1 mM cocaine depressed GABA current by only 33%, but in another three out of nine neurons, cocaine depressed GABA current by as much as 83%. Chelerythrine (a specific CaCa(2+)/phospholipid-dependent protein kinase C [PKC] antagonist) had minimal effect on cocaine's action. We suggest that cocaine induces an increase in [Ca]i, which stimulates phosphatase activity and thus leads to dephosphorylation of GABA receptors. This dephosphorylation-mediated disinhibitory action may play a role in cocaine-induced convulsant states. PMID:17725511

Ye, Jiang-Hong; Ren, Jun

2006-01-01

209

Ionotropic GABA Receptors and Distal Retinal ON and OFF Responses  

PubMed Central

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

Popova, E.

2014-01-01

210

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.

1987-11-09

211

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

2013-04-01

212

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.

1987-06-08

213

Selective antagonists of benzodiazepines  

Microsoft Academic Search

Benzodiazepines produce most, if not all, of their numerous effects on the central nervous system (CNS) primarily by increasing the function of those chemical synapses that use gamma-amino butyric acid (GABA) as transmitter1,2. This specific enhancing effect on GABAergic synaptic inhibition is initiated by the interaction of benzodiazepines with membrane proteins of certain central neurones, to which drugs of this

W. Hunkeler; H. Möhler; L. Pieri; P. Polc; E. P. Bonetti; R. Cumin; R. Schaffner; W. Haefely

1981-01-01

214

Neuroprotective effect of the systemic administration of MK-801 on the pedunculopontine nucleus of hemiparkinsonian rats  

Microsoft Academic Search

Glutamatergic antagonists were administered in rats, as part of the current pharmacological therapies for neuroprotection of patients with Parkinson disease, due to glutamatergic hyperactivity and the deleterious effects of this condition. The effect of the systemic administration of MK-801, an antagonist of N-methyl-D-aspartate (NMDA) receptors, was evaluated on the extracellular concentrations of glutamate (Glu) and gamma amino butyric acid (GABA),

Lisette Blanco; Lourdes Lorigados; Lisis Martínez; Nancy Pavón; María Elena González; Teresa Serrano; Vivian Blanco

215

Neurochemical characterization of nervous elements innervating the body wall of earthworms ( Lumbricus , Eisenia ): immunohistochemical and pharmacological studies  

Microsoft Academic Search

The distribution and chemical neuroanatomy of nervous elements and certain pharmacological–physiological characteristics of the innervation of the body wall in earthworms are described. Solitary sensory bipolar cells can be found among the epithelial cells. These bipolar cells contain serotonin, tyrosine hydroxylase, histamine, gamma-amino-butyric acid (GABA), Eisenia tetradecapeptide, proctolin or rhodopsin in various combinations. In the body wall, the plexus submuscularis

Mária Csoknya; Boglárka Takács; Anna Koza; Viktória Dénes; Márta Wilhelm; László Hiripi; Jan Kaslin; Károly Elekes

2005-01-01

216

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

1991-01-01

217

Cyclooxygenase2 inhibitor inhibits the hippocampal synaptic reorganization by inhibiting MAPK\\/ERK activity and modulating GABAergic transmission in pilocarpine-induced status epilepticus rats  

Microsoft Academic Search

Recurring and spontaneous seizures in epilepsy result from cell signaling aberrations thought to include synaptic reorganization\\u000a and various neurotransmitter abnormalities, especially gamma-amino butyric acid (GABA) and glutamate. Cyclooxygenase-2 (COX-2)\\u000a activity produces oxidative stress and results in the production of prostaglandins that have many injurious effects. COX-2\\u000a transcription is induced by synaptic activity; therefore COX-2 may play a significant role in

Zhang Haiju; Sun Ruopeng; Lei Gefei; Yang Lu; Liu Chunxi

2009-01-01

218

Expression cloning of GABAB receptors uncovers similarity to metabotropic glutamate receptors  

Microsoft Academic Search

GABA (gamma-amino-butyric acid), the principal inhibitory neurotransmitter in the brain, signals through ionotropic (GABAA\\/GABAC) and metabotropic (GABAB) receptor systems. Here we report the cloning of GABAB receptors. Photoaffinity labelling experiments suggest that the cloned receptors correspond to two highly conserved GABAB receptor forms present in the vertebrate nervous system. The cloned receptors negatively couple to adenylyl cyclase and show sequence

Klemens Kaupmann; Katharina Huggel; Jakob Heid; Peter J. Flor; Serge Bischoff; Stuart J. Mickel; Gary McMaster; Christof Angst; Helmut Bittiger; Wolfgang Froestl; Bernhard Bettler

1997-01-01

219

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

PubMed

The squid has been the most studied cephalopod, and it has served as a very useful model for investigating the events associated with nerve impulse generation and synaptic transmission. While the physiology of squid giant axons has been extensively studied, very little is known about the distribution and function of the neurotransmitters and receptors that mediate inhibitory transmission at the synapses. In this study we investigated whether ?-aminobutyric acid (GABA) activates neurotransmitter receptors in stellate ganglia membranes. To overcome the low abundance of GABA-like mRNAs in invertebrates and the low expression of GABA in cephalopods, we used a two-electrode voltage clamp technique to determine if Xenopus laevis oocytes injected with cell membranes from squid stellate ganglia responded to GABA. Using this method, membrane patches containing proteins and ion channels from the squid's stellate ganglion were incorporated into the surface of oocytes. We demonstrated that GABA activates membrane receptors in cellular membranes isolated from squid stellate ganglia. Using the same approach, we were able to record native glutamate-evoked currents. The squid's GABA receptors showed an EC(50) of 98 ?mol l(-1) to GABA and were inhibited by zinc (IC(50) = 356 ?mol l(-1)). Interestingly, GABA receptors from the squid were only partially blocked by bicuculline. These results indicate that the microtransplantation of native cell membranes is useful to identify and characterize scarce membrane proteins. Moreover, our data also support the role of GABA as an ionotropic neurotransmitter in cephalopods, acting through chloride-permeable membrane receptors. PMID:23493508

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

2013-02-01

220

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

PubMed

Extrasynaptic ?-aminobutyric acid type A (GABA(A)) receptors that contain the ? subunit (?GABA(A) receptors) are expressed in several brain regions including the dentate gyrus (DG) and CA1 subfields of the hippocampus. Drugs that increase ?GABA(A) receptor activity have been proposed as treatments for a variety of disorders including insomnia, epilepsy and chronic pain. Also, long-term pretreatment with the ?GABA(A) receptor-preferring agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) enhances discrimination memory and increases neurogenesis in the DG. Despite the potential therapeutic benefits of such treatments, the effects of acutely increasing ?GABA(A) receptor activity on memory behaviors remain unknown. Here, we studied the effects of THIP (4 mg/kg, i.p.) on memory performance in wild-type (WT) and ?GABA(A) receptor null mutant (Gabrd(-/-)) mice. Additionally, the effects of THIP on long-term potentiation (LTP), a molecular correlate of memory, were studied within the DG and CA1 subfields of the hippocampus using electrophysiological recordings of field potentials in hippocampal slices. The results showed that THIP impaired performance in the Morris water maze, contextual fear conditioning and object recognition tasks in WT mice but not Gabrd(-/-) mice. Furthermore, THIP inhibited LTP in hippocampal slices from WT but not Gabrd(-/-) mice, an effect that was blocked by GABA(A) receptor antagonist bicuculline. Thus, acutely increasing ?GABA(A) receptor activity impairs memory behaviors and inhibits synaptic plasticity. These results have important implications for the development of therapies aimed at increasing ?GABA(A) receptor activity. PMID:24062648

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

2013-01-01

221

Electrospray ionization tandem mass spectrometric study on the effect of N-terminal beta- and gamma-carbo amino acids on fragmentation of GABA-hybrid peptides.  

PubMed

The fragmentations of protonated and deprotonated ions of a new class of N-blocked hybrid Boc-carbopeptides containing repeats of gamma-Caa/gammaAbu- and beta-Caa/gammaAbu- (Caa==C-linked carbo gamma(4)-/beta(3)- amino acids derived from D-xylose, gammaAbu = gamma-aminobutyric acid) have been studied using electrospray ionization (ESI) ion-trap tandem mass spectrometry (MS/MS). MS/MS of a pair of these protonated diastereomers produces distinct fragmentation of the Boc group. The formation of [M + H-56](+) corresponding to loss of isobutylene is more pronounced for Boc-NH-(R)-gamma-Caa-gammaAbu-OH (2) whereas it is of low abundance for Boc-NH-(S)-gamma-Caa-gammaAbu--OH (1). Similarly, MS(2) of [M--H](-) of 2 produces an abundant [M--H--C(CH(3))(3)OH--CO(2)](-) ion, which is absent for its diastereomeric isomer 1. From this, it can be suggested that MS/MS of N-blocked Boc-protected carbopeptides may be helpful in distinguishing the stereochemistry of the N-terminus Caa. MS(3) of [M + H-Boc + H](+) ions of peptides with a gamma-amino acid (gamma-Caa/gammaAbu) at the N-terminus produces only abundant y(n) (+) ions. On the other hand, characteristic fragmentations involving the peptide backbone (b(n) (+) and y(n) (+)) and the side chain are seen when beta-Caa is at the N-terminus of the peptides. MS(3) of the [M--H--C(CH(3))(3)OH](-) ion of peptides containing gamma-Caa/gammaAbu at the N-terminus gave y(n) (-) and [M--H--C(CH(3))(3)OH--CO(2)](-) ions, whereas the presence of beta-Caa at the N-terminus yielded predominantly [M--H--C(CH(3))(3)OH--HNCO](-). Thus, on the basis of our previous study and that presented here we propose that the fragmentation of these hybrid carbopeptides is highly influenced by the type of carbo amino acid present at the N-terminus. PMID:18837002

Ramesh, V; Ramesh, M; Srinivas, R; Sharma, G V M; Jayaprakash, P

2008-11-01

222

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

ERIC Educational Resources Information Center

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

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

2010-01-01

223

Looking for GABA in All the Wrong Places: The Relevance of Extrasynaptic GABAA Receptors to Epilepsy  

PubMed Central

It comes as no surprise that a high concentration of ?-aminobutyric acid (GABA)A receptors exists across the synapse from presynaptic terminals that contain GABA. Oddly, though, many GABAA receptors also are far away from synapses. These extrasynaptic GABAA receptors are tonically activated by the low levels of GABA normally present in the extracellular space. Many of these extrasynaptic GABAA receptors contain the ? subunit. This subunit confers molecular properties on GABAA receptors that are well suited for a function in tonic inhibition, with a high affinity for GABA and little desensitization to continuous activation. Recent data linked a genetic variant of the ? subunit to epilepsy, providing a missing link between tonic inhibition and control of brain excitability. PMID:16059513

Richerson, George B.

2004-01-01

224

Airway epithelium is a predominant source of endogenous airway GABA and contributes to relaxation of airway smooth muscle tone  

PubMed Central

Chronic obstructive pulmonary disease and asthma are characterized by hyperreactive airway responses that predispose patients to episodes of acute airway constriction. Recent studies suggest a complex paradigm of GABAergic signaling in airways that involves GABA-mediated relaxation of airway smooth muscle. However, the cellular source of airway GABA and mechanisms regulating its release remain unknown. We questioned whether epithelium is a major source of GABA in the airway and whether the absence of epithelium-derived GABA contributes to greater airway smooth muscle force. Messenger RNA encoding glutamic acid decarboxylase (GAD) 65/67 was quantitatively measured in human airway epithelium and smooth muscle. HPLC quantified GABA levels in guinea pig tracheal ring segments under basal or stimulated conditions with or without epithelium. The role of endogenous GABA in the maintenance of an acetylcholine contraction in human airway and guinea pig airway smooth muscle was assessed in organ baths. A 37.5-fold greater amount of mRNA encoding GAD 67 was detected in human epithelium vs. airway smooth muscle cells. HPLC confirmed that guinea pig airways with intact epithelium have a higher constitutive elution of GABA under basal or KCl-depolarized conditions compared with epithelium-denuded airway rings. Inhibition of GABA transporters significantly suppressed KCl-mediated release of GABA from epithelium-intact airways, but tetrodotoxin was without effect. The presence of intact epithelium had a significant GABAergic-mediated prorelaxant effect on the maintenance of contractile tone. Airway epithelium is a predominant cellular source of endogenous GABA in the airway and contributes significant prorelaxant GABA effects on airway smooth muscle force. PMID:23204068

Townsend, Elizabeth; Yim, Peter; Virag, Laszlo; Zhang, Yi; Xu, Dingbang; Bacchetta, Matthew; Emala, Charles W.

2013-01-01

225

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

PubMed

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

2014-09-19

226

Quantum dot conjugates of GABA and muscimol: binding to ?1?2?2 and ?1 GABA(A) receptors.  

PubMed

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

Gussin, Hélène A; Tomlinson, Ian D; Cao, Dingcai; Qian, Haohua; Rosenthal, Sandra J; Pepperberg, David R

2013-03-20

227

Anion transport and GABA signaling  

PubMed Central

Whereas activation of GABAA receptors by GABA usually results in a hyperpolarizing influx of chloride into the neuron, the reversed chloride driving force in the immature nervous system results in a depolarizing efflux of chloride. This GABAergic depolarization is deemed to be important for the maturation of the neuronal network. The concept of a developmental GABA switch has mainly been derived from in vitro experiments and reliable in vivo evidence is still missing. As GABAA receptors are permeable for both chloride and bicarbonate, the net effect of GABA also critically depends on the distribution of bicarbonate. Whereas chloride can either mediate depolarizing or hyperpolarizing currents, bicarbonate invariably mediates a depolarizing current under physiological conditions. Intracellular bicarbonate is quickly replenished by cytosolic carbonic anhydrases. Intracellular bicarbonate levels also depend on different bicarbonate transporters expressed by neurons. The expression of these proteins is not only developmentally regulated but also differs between cell types and even subcellular regions. In this review we will summarize current knowledge about the role of some of these transporters for brain development and brain function. PMID:24187533

Hübner, Christian A.; Holthoff, Knut

2013-01-01

228

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.

1987-09-07

229

Duplication of the Rdl GABA receptor subunit gene in an insecticide-resistant aphid, Myzus persicae  

Microsoft Academic Search

Resistance to cyclodiene insecticides is associated with replacements of a single amino acid (alanine 302) in a ?-aminobutyric acid (GABA) receptor subunit encoded by the single-copy gene Resistance to dieldrin (Rdl). Alanine 302 is predicted to reside within the second membrane-spanning region of the Rdl receptor, a region that is thought to line the integral chloride ion channel pore. In

N. Anthony; T. Unruh; D. Ganser; R. ffrench-Constant

1998-01-01

230

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

2014-01-01

231

Fine-structural changes of synapses in the superior cervical ganglion of adult rats after long-term administration of GABA  

Microsoft Academic Search

The superior cervical ganglion (SCG) of adult rats was exposed to ?-aminobutyric acid (GABA) by means of long-term microapplication. Serial sections were cut from GABA-treated and control ganglia, and subsequently the fine structure of individual synapses was investigated. The quantitative analysis of structural parameters of studied synapses showed that significant changes consisting of (1) a reduction in size of presynaptic

Ferenc Joó; László Siklós; Wendelin Dames; Joachim R. Wolff

1987-01-01

232

Molecular basis of the alternative recruitment of GABA(A) versus glycine receptors through gephyrin.  

PubMed

?-Aminobutyric acid type A and glycine receptors (GABA(A)Rs, GlyRs) are the major inhibitory neurotransmitter receptors and contribute to many synaptic functions, dysfunctions and human diseases. GABA(A)Rs are important drug targets regulated by direct interactions with the scaffolding protein gephyrin. Here we deduce the molecular basis of this interaction by chemical, biophysical and structural studies of the gephyrin-GABA(A)R ?3 complex, revealing that the N-terminal region of the ?3 peptide occupies the same binding site as the GlyR ? subunit, whereas the C-terminal moiety, which is conserved among all synaptic GABA(A)R ? subunits, engages in unique interactions. Thermodynamic dissections of the gephyrin-receptor interactions identify two residues as primary determinants for gephyrin's subunit preference. This first structural evidence for the gephyrin-mediated synaptic accumulation of GABA(A)Rs offers a framework for future investigations into the regulation of inhibitory synaptic strength and for the development of mechanistically and therapeutically relevant compounds targeting the gephyrin-GABA(A)R interaction. PMID:25531214

Maric, Hans Michael; Kasaragod, Vikram Babu; Hausrat, Torben Johann; Kneussel, Matthias; Tretter, Verena; Strømgaard, Kristian; Schindelin, Hermann

2014-01-01

233

Wavelength-Selective One- and Two-Photon Uncaging of GABA  

PubMed Central

We have synthesized photolabile 7-diethylamino coumarin (DEAC) derivatives of ?-aminobutyric acid (GABA). These caged neurotransmitters efficiently release GABA using linear or nonlinear excitation. We used a new DEAC-based caging chromophore that has a vinyl acrylate substituent at the 3-position that shifts the absorption maximum of DEAC to about 450 nm and thus is named “DEAC450”. DEAC450-caged GABA is photolyzed with a quantum yield of 0.39 and is highly soluble and stable in physiological buffer. We found that DEAC450-caged GABA is relatively inactive toward two-photon excitation at 720 nm, so when paired with a nitroaromatic caged glutamate that is efficiently excited at such wavelengths, we could photorelease glutamate and GABA around single spine heads on neurons in brain slices with excellent wavelength selectivity using two- and one-photon photolysis, respectively. Furthermore, we found that DEAC450-caged GABA could be effectively released using two-photon excitation at 900 nm with spatial resolution of about 3 ?m. Taken together, our experiments show that the DEAC450 caging chromophore holds great promise for the development of new caged compounds that will enable wavelength-selective, two-color interrogation of neuronal signaling with excellent subcellular resolution. PMID:24304264

2013-01-01

234

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

NASA Astrophysics Data System (ADS)

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

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

2006-02-01

235

Thalamic GABA predicts fine motor performance in manganese-exposed smelter workers.  

PubMed

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

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

2014-01-01

236

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.

2013-01-01

237

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

PubMed

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 [(3)H]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 [(3)H]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; Caspary, Donald M

2014-01-01

238

Interactions of flavonoids with ionotropic GABA receptors.  

PubMed

In this overview, we highlight some recent advances in the interaction of natural and synthetic flavonoids with ionotropic GABA receptors. Examples of positive, negative, and neutralizing allosteric modulators as well as allosteric agonists are given. Flavonoids appear to act via multiple binding sites on GABA receptors. Unraveling these active sites remains a major task. PMID:25600371

Hanrahan, Jane R; Chebib, Mary; Johnston, Graham A R

2015-01-01

239

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

2014-01-01

240

Electroacupuncture modulates vlPAG release of GABA through presynaptic cannabinoid CB1 receptors  

PubMed Central

Previous studies have demonstrated that electroacupuncture (EA) attenuates sympathoexcitatory reflex responses by activating a long-loop pathway involving the hypothalamic arcuate nucleus (ARC), midbrain ventrolateral periaqueductal gray (vlPAG), and rostral ventrolateral medulla (rVLM). Neurons in the ARC provide excitatory input to the vlPAG, whereas the vlPAG inhibits neuronal activity in the rVLM. ?-Aminobutyric acid (GABA) and glutamate (Glu) have been identified in the vlPAG. Endocannabinoids (ECs), acting as atypical neurotransmitters, inhibit the release of both neurotransmitters in the hypothalamus and midbrain through a presynaptic cannabinoid type 1 (CB1) receptor mechanism. The EC system has been observed in the dorsal but not in the vlPAG. Since it is uncertain whether ECs influence GABA and Glu in the vlPAG, the present study tested the hypothesis that EA modulates the release of these neurotransmitters in the vlPAG through a presynaptic CB1 receptor mechanism. We measured the release of GABA and Glu simultaneously by using HPLC to assess samples collected with microdialysis probes inserted unilaterally into the vlPAG of intact anesthetized rats. Twenty-eight min of EA (2 Hz, 2–4 mA, 0.5 ms) at the P5–6 acupoints reduced the release of GABA by 39% during EA and by 44% 15 min after EA. Thirty-five minutes after EA, GABA concentrations returned to pre-EA levels. In contrast, sham EA did not change the vlPAG GABA concentration. Blockade of CB1 receptors with AM251, a selective CB1 receptor antagonist, reversed the EA-modulated changes in GABA concentration, whereas microinjection of vehicle into the vlPAG did not alter EA-modulated GABA changes. In addition, we observed no changes in the vlPAG Glu concentrations during EA, although the baseline concentration of Glu was much higher than that of GABA (3,541 ± 373 vs. 33.8 ± 8.7 nM, Glu vs. GABA). These results suggest that EA modulates the sympathoexcitatory reflex responses by decreasing the release of GABA, but not Glu, in the vlPAG, most likely through a presynaptic CB1 receptor mechanism. PMID:19359606

Fu, Liang-Wu; Longhurst, John C.

2009-01-01

241

Ca , GABA Cl , NMDA NMDA  

E-print Network

1 , P450 . , . , . 1 , GABA , 2 , 3 P , 4 . 1 1 . PREGS . PREGS , PREGS , 2 . DHEA , DHEA 2 3 HO P450scc P45017 P45017 O O O O O O O H3C H3C OH H3C OH O O O HO PREGS DHEA E2 C O 11- P45011 P450C21 CORT, HO HO HO 3-HSD P450arom3-HSD 17-HSD 17-HSD HO DHEA 1 , . P450scc , P45017 P450arom

Kawato, Suguru

242

Cyclopropane-based conformational restriction of GABA by a stereochemical diversity-oriented strategy: identification of an efficient lead for potent inhibitors of GABA transports.  

PubMed

A series of cyclopropane-based conformationally restricted ?-aminobutyric acid (GABA) analogs with stereochemical diversity, that is, the trans- and cis-2,3-methano analogs Ia and Ib and their enantiomers ent-Ia and ent-Ib, and also the trans- and cis-3,4-methano analogs IIa and IIb and their enantiomers ent-IIa and ent-Iib, were synthesized from the chiral cyclopropane units Type-a and Type-b that we developed. These analogs were systematically evaluated with four GABA transporter (GAT) subtypes. The trans-3,4-methano analog IIa had inhibitory effects on GAT3 (IC50=23.9?M) and betaine-GABA transporter1 (5.48?M), indicating its potential as an effective lead compound for the development of potent GAT inhibitors due to its hydrophilic and low molecular weight properties and excellent ligand efficiency. PMID:23886812

Nakada, Kazuaki; Yoshikawa, Mamie; Ide, Soichiro; Suemasa, Akihiro; Kawamura, Shuhei; Kobayashi, Takaaki; Masuda, Eiji; Ito, Yoshihiko; Hayakawa, Wataru; Katayama, Takahiro; Yamada, Shizuo; Arisawa, Mitsuhiro; Minami, Masabumi; Shuto, Satoshi

2013-09-01

243

5-HT2C Receptors Localize to Dopamine and GABA Neurons in the Rat Mesoaccumbens Pathway  

PubMed Central

The serotonin 5-HT2C receptor (5-HT2CR) is localized to the limbic-corticostriatal circuit, which plays an integral role in mediating attention, motivation, cognition, and reward processes. The 5-HT2CR is linked to modulation of mesoaccumbens dopamine neurotransmission via an activation of ?-aminobutyric acid (GABA) neurons in the ventral tegmental area (VTA). However, we recently demonstrated the expression of the 5-HT2CR within dopamine VTA neurons suggesting the possibility of a direct influence of the 5-HT2CR upon mesoaccumbens dopamine output. Here, we employed double-label fluorescence immunochemistry with the synthetic enzymes for dopamine (tyrosine hydroxylase; TH) and GABA (glutamic acid decarboxylase isoform 67; GAD-67) and retrograde tract tracing with FluoroGold (FG) to uncover whether dopamine and GABA VTA neurons that possess 5-HT2CR innervate the nucleus accumbens (NAc). The highest numbers of FG-labeled cells were detected in the middle versus rostral and caudal levels of the VTA, and included a subset of TH- and GAD-67 immunoreactive cells, of which >50% also contained 5-HT2CR immunoreactivity. Thus, we demonstrate for the first time that the 5-HT2CR colocalizes in DA and GABA VTA neurons which project to the NAc, describe in detail the distribution of NAc-projecting GABA VTA neurons, and identify the colocalization of TH and GAD-67 in the same NAc-projecting VTA neurons. These data suggest that the 5-HT2CR may exert direct influence upon both dopamine and GABA VTA output to the NAc. Further, the indication that a proportion of NAc-projecting VTA neurons synthesize and potentially release both dopamine and GABA adds intriguing complexity to the framework of the VTA and its postulated neuroanatomical roles. PMID:21687728

Bubar, Marcy J.; Stutz, Sonja J.; Cunningham, Kathryn A.

2011-01-01

244

The GABA Transaminase, ABAT, Is Essential for Mitochondrial Nucleoside Metabolism.  

PubMed

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

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

2015-03-01

245

Increased GAD67 mRNA levels are correlated with in vivo GABA synthesis in the MPTP-treated catecholamine-depleted goldfish brain.  

PubMed

The role of catecholamine neuronal input on GABAergic activity in the hypothalamus, telencephalon, optic tectum, and cerebellum was investigated in early recrudescent female goldfish (Carassius auratus). A new quantitative technique was developed and validated, permitting concomitant quantification and correlational analysis of glutamic acid decarboxylase 65 (GAD65), GAD67, and GAD3 mRNA levels and in vivo GABA synthesis. Catecholamine depletion was achieved by the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 50 microg/g body weight) and dopamine (DA) depletion verified by HPLC. Endogenous GABA levels were increased by intraperitoneal administration of gamma-vinyl GABA (GVG; 300 microg/g body weight), an inhibitor of the GABA catabolic enzyme GABA transaminase. Treatment with MPTP resulted in a greater than twofold increase in GABA synthesis rate in the optic tectum and telencephalon. The increase in GABA synthesis rate was highly correlated with an increase in GAD67, but not GAD65 or GAD3 mRNA levels. These results suggest that catecholaminergic input exerts inhibitory effects on GABA synthesis rates through the modulation of GAD67 in the optic tectum and telencephalon. Together with previously published observations in rodents and primates, it is suggested that catecholaminergic control of GABA synthesis must have evolved more than 200 million years ago, before the emergence of the teleost fishes. PMID:15363887

Hibbert, Benjamin; Fung, Irene; McAuley, Rebecca; Larivière, Katherine; MacNeil, Brian; Bafi-Yeboa, Nana; Livesey, John; Trudeau, Vance

2004-09-28

246

An atlas of glycine- and GABA-like immunoreactivity and colocalization in the cochlear nuclear complex of the guinea pig  

Microsoft Academic Search

The distribution and colocalization of ?-aminobutyric acid (GABA)- and glycine-like immunoreactivity in the cochlear nuclear complex of the guinea pig have been studied to produce a light microscopic atlas. The method used was based on post-embedding immunocytochemistry in pairs of 0.5-µm-thick plastic sections treated with polyclonal antibodies against conjugated GABA and glycine respectively. Immunoreactive cells, presumably short axon neurones, predominated

J. Kolston; K. K. Osen; C. M. Hackney; O. P. Ottersen; J. Storm-Mathisen

1992-01-01

247

Vibrational Spectra of ?-Aminobutyric Acid  

NASA Astrophysics Data System (ADS)

The NIR-FT Raman, FT-IR spectral analysis of ?-Aminobutyric acid (GABA) a simple amino acid is carried out by density functional computations. The vibrational spectra confirm the existence of NH3+ in GABA. Hydroxyl groups H-bonded to the different extents are analysed, supported by computed results.

Suresh, D. M.; Sajan, D.; Laladas, K. P.; Joe, I. Hubert; Jayakumar, V. S.

2008-11-01

248

Topiramate increases cerebral GABA in healthy humans.  

PubMed

Topiramate (TOP) is a novel anticonvulsant drug with multiple mechanisms of action used in the treatment of epilepsy. Measurements of cerebral GABA were obtained in six controls using 1H MRS at baseline and at 3 and 6 hours following the administration of 3 mg/kg of TOP. Brain GABA concentrations rose by 72% at 3 hours and by 64% at 6 hours compared with baseline (p < 0.004). This study demonstrates that TOP significantly increases human cerebral GABA concentrations in healthy individuals. PMID:9710056

Kuzniecky, R; Hetherington, H; Ho, S; Pan, J; Martin, R; Gilliam, F; Hugg, J; Faught, E

1998-08-01

249

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)

2009-06-01

250

Activation mechanism of the heterodimeric GABA(B) receptor.  

PubMed

The GABA(B) receptor was the first heteromeric G-protein coupled receptor (GPCR) identified. Indeed, both GABA(B1) and GABA(B2) subunits appear necessary to get a functional GABA(B) receptor. Soon after the cloning of both subunits, it was demonstrated that GABA(B2) was required for GABA(B1) to reach the cell surface. However, even a mutated GABA(B1) able to reach the cell surface is not functional alone despite its ability to bind GABA(B) ligands. This clearly demonstrated that GABA(B2) is not only required for the correct trafficking of GABA(B1) but also for the correct functioning of the receptor. In the present review article, we will summarize our actual knowledge of the specific role of each subunit in ligand recognition, intramolecular transduction, G-protein activation and allosteric modulation. We will show that the GABA(B) receptor is an heterodimer (not an hetero-oligomer), that agonists bind in GABA(B1), whereas GABA(B2) controls agonist affinity and is responsible for G-protein coupling. Finally, we will show that the recently identified positive allosteric modulator CGP7930 acts as a direct activator of the heptahelical domain of GABA(B2), being therefore the first GABA(B2) ligand identified so far. PMID:15451400

Pin, Jean-Philippe; Kniazeff, Julie; Binet, Virginie; Liu, Jianfeng; Maurel, Damien; Galvez, Thierry; Duthey, Béatrice; Havlickova, Michaela; Blahos, Jaroslav; Prézeau, Laurent; Rondard, Philippe

2004-10-15

251

GABA can improve acoustic contrast in the rat ventral cochlear nucleus.  

PubMed

The effect of microiontophoretically applied gamma-aminobutyric acid (GABA) and its agonists and antagonists on the response pattern of single units in the ventral cochlear nucleus (VCN) of the rat was examined in order to study GABA's physiological function in auditory processing. The effects of the drugs were judged by changes of spontaneous and sound-evoked activity in peristimulus-time histograms (PSTHs) of at least 20 consecutive presentations of acoustic stimuli. GABA inhibited the discharge activity of the majority of neurons. All response types found in the VCN except onset-I responders were sensitive to GABA. The GABAergic inhibition is most probably mediated by GABAA receptors, since the GABAA-receptor agonist muscimol, but not the GABAB-receptor agonist baclofen, mimicked the effect of GABA. The GABAA-receptor antagonists, bicuculline and picrotoxin, had an excitatory effect on the neurons' spontaneous activity, suggesting a tonic endogeneous release of GABA which exerts a permanent inhibition on VCN neurons. Although inhibitory, iontophoresis of GABA emphasized the response to stimulus onset in the PSTHs by means of a stronger inhibition of spontaneous activity. When using iontophoretical currents which did not suppress the neuronal activity completely, a strong inhibition of spontaneous activity was accompanied by only a small inhibition of tone-evoked activity. Under these conditions, the response to tone onset was frequently not inhibited at all. Therefore, GABA's physiological function is possibly to improve the contrast between transient acoustic signals and ongoing background activity. In order to test this hypothesis, the test tone was masked by continuous background noise. Indeed, GABA reduced the noise-evoked discharge more than the tone-evoked discharge, leaving the onset peak in the PSTHs almost unchanged. Thus, GABAergic input improves the signal-to-noise ratio for acoustic transients in VCN neurons. Our data suggest that a functional role of GABA in the VCN is to act as a transmitter within a descending inhibitory feedback loop of the auditory brainstem which serves to improve the transmission of relevant acoustic signals in constant background noise. PMID:7672023

Ebert, U; Ostwald, J

1995-01-01

252

GABA Receptors Ameliorate Hcy-Mediated Integrin Shedding and Constrictive Collagen Remodeling in Microvascular Endothelial Cells  

PubMed Central

Mammalian endothelial cells are deficient in cystathionine ? synthetase (CBS) activity, which is responsible for homocysteine (Hcy) clearance. This deficiency makes the endothelium the prime target for Hcy toxicity. Hcy induces integrin shedding in microvascular endothelial cells (MVEC) by increasing matrix metalloproteinase (MMP). Hcy competes with inhibitory neurotransmitter ? aminobutyric acid (GABA)-A receptor. We hypothesized that Hcy transduces MVEC remodeling by increasing metalloproteinase activity and shedding ?-1 integrin by inactivating the GABA-A/B receptors, thus behaving as an excitatory neurotransmitter. MVEC were isolated from mouse brain. The presence of GABA-A receptor was determined by immunolabeling. It was induced by muscimol, an agonist of GABA-A receptor as measured by Western blot analysis. Hcy induced MMP-2 activity in a dose- and time-dependent manner, measured by zymography. GABA-A/B receptors ameliorated the Hcy-mediated MMP-2 activation. Hcy selectively increased the levels of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-3 but decreased the levels of TIMP-4. Treatment with muscimol decreased the levels of TIMP-1 and TIMP-3 and increased the levels of TIMP-4 to control. Hcy caused a robust increase in the levels of a disintegrin and metalloproteinase (ADAM)-12. In the medium of MVEC treated with Hcy, the levels of ?-1 integrin were significantly increased. Treatment with muscimol or baclofen (GABA-B receptor agonist) ameliorated the levels of ?-1 integrin in the medium. These results suggested that Hcy induced ADAM-12. Significantly, Hcy facilitated the ?-1 integrin shedding. Treatment of MVEC with muscimol or baclofen during Hcy administration ameliorated the expression of metalloproteinase, integrin-shedding, and constrictive collagen remodeling, suggesting a role of Hcy in GABA receptor-mediated cerebrovascular remodeling. PMID:16757816

Shastry, Suresh; Tyagi, Neetu; Moshal, Karni S.; Lominadze, David; Hayden, Melvin R.; Tyagi, Suresh C.

2011-01-01

253

Comparative mapping of GABA-immunoreactive neurons in the central nervous systems of nudibranch molluscs.  

PubMed

The relative simplicity of certain invertebrate nervous systems, such as those of gastropod molluscs, allows behaviors to be dissected at the level of small neural circuits composed of individually identifiable neurons. Elucidating the neurotransmitter phenotype of neurons in neural circuits is important for understanding how those neural circuits function. In this study, we examined the distribution of ?-aminobutyric-acid;-immunoreactive (GABA-ir) neurons in four species of sea slugs (Mollusca, Gastropoda, Opisthobranchia, Nudibranchia): Tritonia diomedea, Melibe leonina, Dendronotus iris, and Hermissenda crassicornis. We found consistent patterns of GABA immunoreactivity in the pedal and cerebral-pleural ganglia across species. In particular, there were bilateral clusters in the lateral and medial regions of the dorsal surface of the cerebral ganglia as well as a cluster on the ventral surface of the pedal ganglia. There were also individual GABA-ir neurons that were recognizable across species. The invariant presence of these individual neurons and clusters suggests that they are homologous, although there were interspecies differences in the numbers of neurons in the clusters. The GABAergic system was largely restricted to the central nervous system, with the majority of axons confined to ganglionic connectives and commissures, suggesting a central, integrative role for GABA. GABA was a candidate inhibitory neurotransmitter for neurons in central pattern generator (CPG) circuits underlying swimming behaviors in these species, however none of the known swim CPG neurons were GABA-ir. Although the functions of these GABA-ir neurons are not known, it is clear that their presence has been strongly conserved across nudibranchs. PMID:24638845

Gunaratne, Charuni A; Sakurai, Akira; Katz, Paul S

2014-03-01

254

Brain regional distribution of GABAA receptors exhibiting atypical GABA agonism: roles of receptor subunits  

PubMed Central

The major inhibitory neurotransmitter in the brain, ?-aminobutyric acid (GABA), has only partial efficacy at certain subtypes of GABAA receptors. To characterize these minor receptor populations in rat and mouse brains, we used autoradiographic imaging of t-butylbicyclophosphoro[35S]thionate ([35S]TBPS) binding to GABAA receptors in brain sections and compared the displacing capacities of 10 mM GABA and 1 mM 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP), a competitive GABA-site agonist. Brains from GABAA receptor ?1, ?4, ?, and ?4 + ? subunit knockout (KO) mouse lines were used to understand the contribution of these particular receptor subunits to “GABA-insensitive” (GIS) [35S]TBPS binding. THIP displaced more [35S]TBPS binding than GABA in several brain regions, indicating that THIP also inhibited GIS-binding. In these regions, GABA prevented the effect of THIP on GIS-binding. GIS-binding was increased in the cerebellar granule cell layer of ? KO and ?4 + ? KO mice, being only slightly diminished in that of ?1 KO mice. In the thalamus and some other forebrain regions of wild-type mice, a significant amount of GIS-binding was detected. This GIS-binding was higher in ?4 KO mice. However, it was fully abolished in ?1 KO mice, indicating that the ?1 subunit was obligatory for the GIS-binding in the forebrain. Our results suggest that native GABAA receptors in brain sections showing reduced displacing capacity of [35S]TBPS binding by GABA (partial agonism) minimally require the assembly of ?1 and ? subunits in the forebrain and of ?6 and ? subunits in the cerebellar granule cell layer. These receptors may function as extrasynaptic GABAA receptors. PMID:19397945

Halonen, Lauri M.; Sinkkonen, Saku T.; Chandra, Dev; Homanics, Gregg E.; Korpi, Esa R.

2009-01-01

255

New GABA amides activating GABAA-receptors  

PubMed Central

Summary We have prepared a series of new and some literature-reported GABA-amides and determined their effect on the activation of GABAA-receptors expressed in CHO cells. Special attention was paid to the purification of the target compounds to remove even traces of GABA contaminations, which may arise from deprotection steps in the synthesis. GABA-amides were previously reported to be partial, full or superagonists. In our hands these compounds were not able to activate GABAA-receptor channels in whole-cell patch-clamp recordings. New GABA-amides, however, gave moderate activation responses with a clear structure–activity relationship suggesting some of these compounds as promising molecular tools for the functional analysis of GABAA-receptors. PMID:23503884

Raster, Peter; Späth, Andreas; Bultakova, Svetlana; Gorostiza, Pau

2013-01-01

256

Phenotypic characterization of orofacial movement topography in mutants with disruption of amino acid mechanisms: glutamate N2A/B/D [GluR?1/2/4] subtypes and the GABA synthesizing enzyme GAD65.  

PubMed

To investigate the role of glutamate receptor subtypes and GABA in orofacial function, six individual topographies of orofacial movement, both spontaneous and induced by the dopamine D1-like receptor agonist [R/S]-3-methyl-6-chloro-7,8-dihydroxy-1-[3-methyl-phenyl]-2,3,4,5-tetrahydro-1H-3-benzazepine (SKF 83959), were quantified in mutant mice with deletion of (a) GluN2A, B or D receptors, and (b) the GABA synthesizing enzyme, 65-kD isoform of glutamate decarboxylase (GAD65). In GluN2A mutants, habituation of head movements was disrupted and vibrissae movements were reduced, with an overall increase in locomotion; responsivity to SKF 83959 was unaltered. In GluN2B mutants, vertical and horizontal jaw movements and incisor chattering were increased, with an overall decrease in locomotion; under challenge with SKF 83959, head and vibrissae movements were reduced. In GluN2D mutants, horizontal jaw movements, incisor chattering and vibrissae movements were increased, with reduced tongue protrusions and no overall change in locomotion; under challenge with SKF 83959, horizontal jaw movements were increased. In GAD65 mutants, vertical jaw movements were increased, with disruption to habituation of locomotion; under challenge with SKF 83959, vertical and horizontal jaw movements and incisor chattering were decreased. Effects on orofacial movements differed from their effects on regulation of overall locomotor behavior. These findings (a) indicate novel, differential roles for GluN2A, B and D receptors and for GAD65-mediated GABA in the regulation of individual topographies of orofacial movement and (b) reveal how these roles differ from and/or interact with the established role of D1-like receptors in pattern generators and effectors for such movements. PMID:23892010

Tomiyama, K; Kato, R; Hara, Y; Kobayashi, M; Mishina, M; Yanagawa, Y; Kinsella, A; Koshikawa, N; Waddington, J L

2013-10-10

257

Cerebrospinal fluid GABA levels in chronic migraine with and without depression  

Microsoft Academic Search

Psychiatric comorbidity is one of the key elements in chronic migraine (CM) management. Depression is particularly common in these patients, occurring in up to 85%. Preclinical studies have suggested that gamma-aminobutyric acid (GABA) levels may be decreased in animal models of depression. Also, clinical studies have reported low level in mood disorder patients for both plasma and cerebrospinal fluid (CSF)

D. S. S. Vieira; M. G. Naffah-Mazacoratti; E. Zukerman; C. A. Senne Soares; E. O. Alonso; M. H. W. Faulhaber; E. A. Cavalheiro; M. F. P. Peres

2006-01-01

258

Molecular pharmacology of an insect GABA receptor  

E-print Network

Molecular Pharmacology of an Insect GABA Receptor A dissertation submitted to the University of Cambridge for the degree of Doctor of Philosophy Ian Vincent McGonigle (BA) King’s College Cambridge 2010... .1 Future directions 149 8.2 Final remarks 152 References 153 8 List of Tables and Figures Chapter 1. Introduction Page Table 1.1 Pharmacology of insect GABA receptor subunits 36 Fig. 1.1 Chemical...

McGonigle, Ian Vincent

2010-10-12

259

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

SciTech Connect

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

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

1986-12-01

260

BRAIN STIMULATION REWARD IS INTEGRATED BY A NETWORK OF ELECTRICALLY-COUPLED GABA NEURONS  

PubMed Central

The neural substrate of brain stimulation reward (BSR) has eluded identification since its discovery more than a half-century ago. Notwithstanding the difficulties in identifying the neuronal integrator of BSR, the mesocorticolimbic dopamine (DA) system originating in the ventral tegmental area (VTA) of the midbrain has been implicated. We have previously demonstrated that the firing rate of a subpopulation of ?–aminobutyric acid (GABA) neurons in the VTA increases in anticipation of BSR. We show here that GABA neurons in the VTA, midbrain, hypothalamus and thalamus of rats express connexin-36 (Cx36) gap junctions (GJs) and couple electrically upon DA application or by stimulation of the internal capsule (IC), which also supports self-stimulation. The threshold for responding for IC self-stimulation was the threshold for electrical coupling between GABA neurons, the degree of responding for IC self-stimulation was proportional to the magnitude of electrical coupling between GABA neurons, and GJ blockers increased the threshold for IC self-stimulation without affecting performance. Thus, a network of electrically-coupled GABA neurons in the ventral brain may form the elusive neural integrator of BSR. PMID:17524371

Lassen, Matthew B.; Brown, J. Elliott; Stobbs, Sarah H.; Gunderson, Seth H.; Maes, Levi; Valenzuela, C Fernando; Ray, Andrew P.; Henriksen, Steven J.; Steffensen, Scott C.

2013-01-01

261

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.

1987-01-01

262

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

PubMed

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

2015-03-01

263

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

SciTech Connect

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

Wafford, K.A.; Burnett, D.M.; Dunwiddie, T.V.; Harris, R.A. (Univ. of Colorado Health Sciences Center, Denver (USA))

1990-07-20

264

In-vivo MRS measurement of gray-matter and white-matter GABA concentration in sensorimotor cortex using a motion-controlled MEGA-PRESS Sequence  

PubMed Central

Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the brain. Understanding the GABA concentration, in vivo, is important to understand normal brain function. Using MEGA point resolved spectroscopy (MEGA-PRESS) sequence with interleaved water scans to detect subject motion, GABA level of sensorimotor cortex was measured using a voxel was identified from a functional MRI scan. The GABA level in a 20 × 20 × 20 mm3 voxel consisting of 37 ± 7% GM, 52 ± 12% WM, and 11 ± 8% CSF in the sensorimotor region was measured to be 1.43 ± 0.48 mM. In addition, using linear regression analysis, GABA concentrations within gray and white matter were calculated to be 2.87 ± 0.61 and 0.33 ± 0.11 mM, respectively. PMID:21232891

Bhattacharyya, P.K.; Phillips, M.D.; Stone, L.A.; Lowe, M.J.

2010-01-01

265

Synaptic GABA release prevents GABA transporter type-1 reversal during excessive network activity  

PubMed Central

GABA transporters control extracellular GABA, which regulates the key aspects of neuronal and network behaviour. A prevailing view is that modest neuronal depolarization results in GABA transporter type-1 (GAT-1) reversal causing non-vesicular GABA release into the extracellular space during intense network activity. This has important implications for GABA uptake-targeting therapies. Here we combined a realistic kinetic model of GAT-1 with experimental measurements of tonic GABAA receptor currents in ex vivo hippocampal slices to examine GAT-1 operation under varying network conditions. Our simulations predict that synaptic GABA release during network activity robustly prevents GAT-1 reversal. We test this in the 0 Mg2+ model of epileptiform discharges using slices from healthy and chronically epileptic rats and find that epileptiform activity is associated with increased synaptic GABA release and is not accompanied by GAT-1 reversal. We conclude that sustained efflux of GABA through GAT-1 is unlikely to occur during physiological or pathological network activity. PMID:25798861

Savtchenko, Leonid; Megalogeni, Maria; Rusakov, Dmitri A.; Walker, Matthew C.; Pavlov, Ivan

2015-01-01

266

Prebiotic syntheses of vitamin coenzymes: II. Pantoic acid, pantothenic acid, and the composition of coenzyme A  

NASA Technical Reports Server (NTRS)

Pantoic acid can by synthesized in good prebiotic yield from isobutyraldehyde or alpha-ketoisovaleric acid + H2CO + HCN. Isobutyraldehyde is the Strecker precursor to valine and alpha-ketoisovaleric acid is the valine transamination product. Mg2+ and Ca2+ as well as several transition metals are catalysts for the alpha-ketoisovaleric acid reaction. Pantothenic acid is produced from pantoyl lactone (easily formed from pantoic acid) and the relatively high concentrations of beta-alanine that would be formed on drying prebiotic amino acid mixtures. There is no selectivity for this reaction over glycine, alanine, or gamma-amino butyric acid. The components of coenzyme A are discussed in terms of ease of prebiotic formation and stability and are shown to be plausible choices, but many other compounds are possible. The gamma-OH of pantoic acid needs to be capped to prevent decomposition of pantothenic acid. These results suggest that coenzyme A function was important in the earliest metabolic pathways and that the coenzyme A precursor contained most of the components of the present coenzyme.

Miller, S. L.; Schlesinger, G.

1993-01-01

267

Self-enhancement of GABA in rice bran using various stress treatments.  

PubMed

Gamma-aminobutyric acid (GABA) may be synthesized in plant tissues when the organism is under stressful conditions. Rice bran byproduct obtained from the milling of brown rice was treated under anaerobic storage with nitrogen at different temperatures (20-60 °C) and moisture contents (10-50%) up to 12h. For the GABA synthesis, the storage at 30% moisture content and 40 °C appeared optimal. Utilisation of an electrolyzed oxidizing water (EOW, pH 3.3) for moisture adjustment and addition of glutamic acid increased the GABA content in rice bran. The maximum GABA content in rice bran (523 mg/100g) could be achieved by the anaerobic storage at 30% EOW for 5h at 40 °C after an addition of glutamic acid (5mM). This amount was approximately 17 times higher than that in the control (30 mg/100g). The use of EOW also prevented bacterial growth by decreasing the colony counts almost by half. PMID:25442603

Kim, Hyun Soo; Lee, Eun Jung; Lim, Seung-Taik; Han, Jung-Ah

2015-04-01

268

Adaptation of the GABAA-receptor complex in rat brain during chronic elevation of GABA by ethanolamine O-sulphate.  

PubMed Central

Slice preparations of rat cuneate nucleus were used for studies on the gamma-aminobutyric acid GABAA-receptor complex following chronic and acute pretreatment with GABA-alpha-ketoglutarate aminotransferase (GABA-T) inhibitors. The whole brain GABA concentration was significantly increased 2.9 fold and 2.6 fold following treatment with ethanolamine O-sulphate (EOS, orally) for 15-30 days and 56-64 days, respectively. One hour after a single injection of gamma-acetylenic GABA (GAG) i.p., there was a significant 2.1 fold increase in whole brain GABA. Superfusion of a slice with muscimol or the GABA uptake inhibitor nipecotic acid depolarized the afferent nerve fibres. These effects were potentiated by flurazepam (1 microM) and pentobarbitone (10 microM) and antagonized by picrotoxin (3 microM, 30 microM). Following 15-30 days of EOS-treatment, the depolarization response to muscimol was decreased and that to nipecotic acid increased. These changes were no longer significant by 56-64 days of pretreatment. The acute dose of GAG did not affect the depolarization response to muscimol but increased that to nipecotic acid. The potentiations of muscimol by flurazepam (1 microM) and pentobarbitone (10 microM) were enhanced following chronic EOS treatment (15-64 days). The enhancement of flurazepam was less after 56-64 days than after 15-30 days pretreatment whereas the enhancement of pentobarbitone was similar at both times. Acute GAG treatment had no effect. The potency of picrotoxin as an antagonist of muscimol was reduced following chronic EOS treatment; the enhancement was less after 56-64 days than after 15-30 days pretreatment. Acute GAG treatment caused only a very small reduction in picrotoxin potency. Possible adaptations in the GABAA-receptor complex and its modulation during chronic elevation of brain GABA are discussed. PMID:3038247

Lindgren, S.; Simmonds, M. A.

1987-01-01

269

Age-related Hearing Loss: GABA, Nicotinic Acetylcholine and NMDA Receptor Expression Changes in Spiral Ganglion Neurons of the Mouse  

PubMed Central

Age-related hearing loss – presbycusis – is the number one communication disorder and most prevalent neurodegenerative condition of our aged population. Although speech understanding in background noise is quite difficult for those with presbycusis, there are currently no biomedical treatments to prevent, delay or reverse this condition. A better understanding of the cochlear mechanisms underlying presbycusis will help lead to future treatments. Objectives of the present study were to investigate gamma-amino butyric acid A (GABAA) receptor subunit ?1, nicotinic acetylcholine (nACh) receptor subunit ?2, and N-methyl-D-aspartate (NMDA) receptor subunit NR1 mRNA and protein expression changes in spiral ganglion neurons of the CBA/CaJ mouse cochlea, that occur in age-related hearing loss, utilizing quantitative immunohistochemistry and semi-quantitative RT-PCR techniques. We found that auditory brainstem response (ABR) thresholds shifted over 40 dB from 3–48 kHz in old mice compared to young adults. DPOAE thresholds also shifted over 40 dB from 6–49 kHz in old mice, and their amplitudes were significantly decreased or absent in the same frequency range. Spiral ganglion neuron (SGN) density decreased with age in basal, middle and apical turns, and SGN density of the basal turn declined the most. A positive correlation was observed between SGN density and ABR wave 1 amplitude. mRNA and protein expression of GABAAR ?1 and AChR ?2 decreased with age in SGNs in the old mouse cochlea. mRNA and protein expression of NMDAR NR1 increased with age in SGNs of the old mice. These findings demonstrate that there are functionally-relevant age-related changes of GABAAR, nAChR, NMDAR expression in CBA mouse SGNs reflecting their degeneration, which may be related to functional changes in cochlear synaptic transmission with age, suggesting biological mechanisms for peripheral age-related hearing loss. PMID:24316061

Tang, Xiaolan; Zhu, Xiaoxia; Ding, Bo; Walton, Joseph P.; Frisina, Robert D.; Su, Jiping

2014-01-01

270

Astrocytic Control of Biosynthesis and Turnover of the Neurotransmitters Glutamate and GABA  

PubMed Central

Glutamate and GABA are the quantitatively major neurotransmitters in the brain mediating excitatory and inhibitory signaling, respectively. These amino acids are metabolically interrelated and at the same time they are tightly coupled to the intermediary metabolism including energy homeostasis. Astrocytes play a pivotal role in the maintenance of the neurotransmitter pools of glutamate and GABA since only these cells express pyruvate carboxylase, the enzyme required for de novo synthesis of the two amino acids. Such de novo synthesis is obligatory to compensate for catabolism of glutamate and GABA related to oxidative metabolism when the amino acids are used as energy substrates. This, in turn, is influenced by the extent to which the cycling of the amino acids between neurons and astrocytes may occur. This cycling is brought about by the glutamate/GABA – glutamine cycle the operation of which involves the enzymes glutamine synthetase (GS) and phosphate-activated glutaminase together with the plasma membrane transporters for glutamate, GABA, and glutamine. The distribution of these proteins between neurons and astrocytes determines the efficacy of the cycle and it is of particular importance that GS is exclusively expressed in astrocytes. It should be kept in mind that the operation of the cycle is associated with movement of ammonia nitrogen between the two cell types and different mechanisms which can mediate this have been proposed. This review is intended to delineate the above mentioned processes and to discuss quantitatively their relative importance in the homeostatic mechanisms responsible for the maintenance of optimal conditions for the respective neurotransmission processes to operate. PMID:23966981

Schousboe, Arne; Bak, Lasse K.; Waagepetersen, Helle S.

2013-01-01

271

Concentration-dependent effects of GABA on insensitivity to fipronil in the A2'S mutant RDL GABA receptor from fipronil-resistant Oulema oryzae (Coleoptera: Chrysomelidae).  

PubMed

The beetle Oulema oryzae Kuwayama (Coleoptera: Chrysomelidae), an important pest of rice, has developed fipronil resistance in Japan. Molecular cloning and sequence analysis of O. oryzae RDL gamma-aminobutyric acid (GABA) receptor subunit (OO-RDL) genes from fipronil-susceptible and -resistant O. oryzae identified the A2'S mutation (index number for the M2 membrane-spanning region). To investigate the effect of the A2'S mutation on fipronil resistance, we stably expressed the wild-type and mutant OO-RDL homomers in Drosophila Mel-2 cells. A membrane potential assay exhibited that the IC50 values of fipronil for inhibition of the response to EC80 GABA of the wild-type and A2'S mutant OO-RDL homomers were 0.09 microM and 0.11 microM, respectively. However, the IC50 values of fipronil for inhibition of the response to EC95 GABA of the wild-type and A2'S mutant OO-RDL homomers were 0.11 microM and approximately equal to 5 microM, respectively. These results suggest that the GABA concentration is an important factor affecting fipronil resistance in O. oryzae carrying the A2'S mutation in OO-RDL. PMID:23156177

Nakao, Toshifumi; Naoi, Atsuko; Hama, Masako; Kawahara, Nobuyuki; Hirase, Kangetsu

2012-10-01

272

Sustained GABA-induced regulation of the inactivation of the voltage-dependent Ca2+ current in crustacean muscle fibers.  

PubMed

We describe a new form of gamma-aminobutyric acid (GABA) -mediated regulation of the inactivation and of the recovery from inactivation of the L-type Ca2+ current (I(Ca)) in crayfish muscle. GABA (1 mM) was applied during a 2-min period and the peak I(Ca) was measured using two-electrode voltage-clamp recordings 30 min after returning to the control solution. Prepulse-pulse protocols showed that the GABA-mediated inhibition of I(Ca) decreased (>50%) both with increasing prepulse depolarization and as the delay between prepulse and pulse was reduced. GABA also shifted to depolarized values (>5 mV) the S-shaped plots of the peak I(Ca) evoked by a constant depolarizing pulse as a function of prepulse voltage (i.e., inactivation curves) and accelerated the recovery time from the inactivation evoked by depolarizing prepulses (>35%). The effects outlasted GABA application up to 1 h. The observed changes in inactivation properties may be of functional importance because they indicate that previous depolarization relieves the GABA-induced inhibition of I(Ca), implying that this long-lasting inhibition is under the regulation of the prepulse potential and the subsequent Ca2+ entry. PMID:11026730

Castellote, J M; Buño, W

2000-09-01

273

Distinct patterns of expression and regulation of GABA receptors containing the delta subunit in cerebellar granule and hippocampal neurons.  

PubMed

Neuronal plasticity is achieved by regulation of the expression of genes for neurotransmitter receptors such as the type A receptor (GABA(A)R) for gamma-aminobutyric acid. We now show that two different rat neuronal populations in culture manifest distinct patterns of GABA(A)R plasticity in response to identical stimuli. Whereas prolonged exposure to ethanol had no effect on expression of the delta subunit of GABA(A)Rs at the mRNA or protein level in cerebellar granule neurons, it increased the abundance of delta subunit mRNA and protein in hippocampal neurons. Subsequent ethanol withdrawal transiently down-regulated delta subunit expression in cerebellar granule neurons and gradually normalized that in hippocampal neurons. These effects of ethanol exposure and withdrawal were accompanied by corresponding functional changes in GABA(A)Rs. GABA(A)Rs containing the delta subunit were also distributed differentially in the cerebellar and hippocampal neurons. These findings reveal complex and distinct mechanisms of regulation of the expression of GABA(A)Rs that contain the delta subunit in different neuronal types. PMID:16000147

Follesa, Paolo; Mostallino, Maria Cristina; Biggio, Francesca; Gorini, Giorgio; Caria, Stefania; Busonero, Fabio; Murru, Luca; Mura, Maria Luisa; Sanna, Enrico; Biggio, Giovanni

2005-08-01

274

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

PubMed

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

2015-01-29

275

Differential effects of two major neurosteroids on cerebellar and cortical GABA(A) receptor binding and function.  

PubMed

Cerebellar and cerebrocortical A-type ?-aminobutyric acid (GABA(A)) receptors were examined in mice and rats. In wild-type mouse cerebellum, the agonists GABA and gaboxadol exerted heterogeneous displacement of [(3)H]ethynylbicycloorthobenzoate (EBOB) binding with nanomolar and submicromolar affinities. In mouse cerebella lacking ?6 subunits (?6KO), nanomolar displacement by GABA agonists was absent, while micromolar displacement was potentiated to 12-fold by 0.3?M 5?-tetrahydrodeoxycorticosterone (5?-THDOC). In ?6KO cerebellum, 60% of [(3)H]EBOB binding was neurosteroid-insensitive, while 5?-THDOC elicited enhancement with EC(50)=150nM instead of nanomolar displacement. In conclusion, nanomolar displacement of cerebellar [(3)H]EBOB binding by GABA agonists and neurosteroids can be attributed to GABA(A) receptors containing ?6 and ? subunits. In contrast, [(3)H]EBOB binding to rat cerebral cortex was affected by allopregnanolone and 5?-THDOC in bidirectional manner with nanomolar enhancement (EC(50) ~80nM) and micromolar displacement. Nonequilibrium binding conditions with decreased incubation time tripled the maximal enhancement of [(3)H]EBOB binding by 5?-THDOC. 5ß-THDOC enhanced the cortical [(3)H]EBOB binding with EC(50) ~0.5?M and it attenuated bidirectional modulation by 5?-THDOC. Allopregnanolone and 5?-THDOC produced biphasic enhancements of chloride currents elicited by 1?M GABA in cerebellar granule cells, for 5?-THDOC with EC(50,1) ~16nM and EC(50,2) ~1.3?M. Differences in peak current enhancements in the absence minus presence of 0.1mM furosemide corresponding to ?6ß? GABA(A) receptors were augmented only by micromolar 5?-THDOC while the difference curve for allopregnanolone was polyphasic as without furosemide. Consequently, these neurosteroids differentially affected the binding and function of various GABA(A) receptor populations. PMID:20951124

Maksay, Gábor; Fodor, László

2011-01-10

276

Menthol shares general anesthetic activity and sites of action on the GABA(A) receptor with the intravenous agent, propofol.  

PubMed

Menthol and related compounds were investigated for modulation of recombinant human gamma-aminobutyric acid type A (GABA(A), alpha(1)beta(2)gamma(2s)) receptor currents expressed in Xenopus oocytes. Sub-maximal (EC(20)) GABA currents were typically enhanced by co-applications of 3-300 microM (+)-menthol (e.g. by approximately 2-fold at 50 microM) > isopulegol > isomenthol> alpha-terpineol > cyclohexanol. We studied menthol's actions on GABA(A) receptors compared to sedatives (benzodiazepines) and intravenous anesthetics (barbiturates, steroids, etomidate and propofol). Flumazenil (a benzodiazepine antagonist) did not inhibit menthol enhancements while currents directly activated by 50 microM propofol were significantly inhibited (by 26+/-3%) by 50 microM (+)-menthol. GABA(A) receptors containing beta(2) subunits with either a point mutation in a methionine residue to a tryptophan at the 286 position (in transmembrane domain 3, TM-3) or a tyrosine to a tryptophan at the 444 position (TM-4) are insensitive to modulation by propofol. Enhancements of GABA EC(20) currents by menthol were equally abolished in GABA(A) alpha(1)beta(2)(M286W)gamma(2s) and alpha(1)beta(2)(Y444W)gamma(2s) receptors while positive modulations by benzodiazepines, barbiturates and steroids were unaffected. Menthol may therefore exert its actions on GABA(A) receptors via sites distinct from benzodiazepines, steroids and barbiturates, and via sites important for modulation by propofol. Finally, using an in vivo tadpole assay, addition of (+)-menthol resulted in a loss of righting reflex with an EC(50) of 23.5+/-4.7 microM (approximately10-fold less potent anesthesia than propofol). Thus, menthol and analogs share general anesthetic action with propofol, possibly via action at similar sites on the GABA(A) receptor. PMID:18593637

Watt, Erin E; Betts, Brooke A; Kotey, Francesca O; Humbert, Danielle J; Griffith, Theanne N; Kelly, Elizabeth W; Veneskey, Kelley C; Gill, Nikhila; Rowan, Kathleen C; Jenkins, Andrew; Hall, Adam C

2008-08-20

277

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

PubMed

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

2014-10-01

278

Spinal cord GABA receptors modulate the exercise pressor reflex in decerebrate rats.  

PubMed

Neurotransmitters and neuromodulators released by contraction-activated skeletal muscle afferents into the dorsal horn of the spinal cord initiate the central component of the exercise pressor reflex (EPR). Whether ?-aminobutyric acid (GABA), a major inhibitory neurotransmitter within the mammalian central nervous system, is involved in the modulation of the EPR at the level of dorsal horn remains to be determined. We performed local microinjection of either the GABA(A) antagonist bicuculline or the GABA(B) antagonist CGP 52432 into the ipisilateral L4/L5 dorsal horns to investigate the effect of GABA receptor blockade on the pressor response to either static contraction induced by stimulation of the peripheral end of L4/L5 ventral roots, passive stretch, or hindlimb arterial injection of capsaicin (0.1 ?g/0.2 ml) in decerebrate rats. Microinjection of either bicuculline (1 mM, 100 nl) or CGP 52432 (10 mM, 100 nl) into the L4/5 dorsal horns significantly increased the pressor and cardioaccelerator responses to all stimuli. Microinjection of either bicuculline or CGP 52432 into the L5 dorsal horn significantly increased the pressor and cardioaccelerator responses to direct microinjection of l-glutatmate (10 mM, 100 nl) into this spinal segment. The disinhibitory effect of both GABA receptor antagonists on the EPR was abolished by microinjection of the broad-spectrum glutamate receptor antagonist kynurenate (10 mM/100 nl). These data suggest that 1) GABA exerts a tonic inhibition of the EPR at the level of dorsal horn; and 2) that an interaction between glutamatergic and GABAergic inputs exist at the level of dorsal horn, contributing to spinal control of the EPR. PMID:23637133

Wang, Han-Jun; Wang, Wei; Patel, Kaushik P; Rozanski, George J; Zucker, Irving H

2013-07-01

279

Spinal cord GABA receptors modulate the exercise pressor reflex in decerebrate rats  

PubMed Central

Neurotransmitters and neuromodulators released by contraction-activated skeletal muscle afferents into the dorsal horn of the spinal cord initiate the central component of the exercise pressor reflex (EPR). Whether ?-aminobutyric acid (GABA), a major inhibitory neurotransmitter within the mammalian central nervous system, is involved in the modulation of the EPR at the level of dorsal horn remains to be determined. We performed local microinjection of either the GABA(A) antagonist bicuculline or the GABA(B) antagonist CGP 52432 into the ipisilateral L4/L5 dorsal horns to investigate the effect of GABA receptor blockade on the pressor response to either static contraction induced by stimulation of the peripheral end of L4/L5 ventral roots, passive stretch, or hindlimb arterial injection of capsaicin (0.1 ?g/0.2 ml) in decerebrate rats. Microinjection of either bicuculline (1 mM, 100 nl) or CGP 52432 (10 mM, 100 nl) into the L4/5 dorsal horns significantly increased the pressor and cardioaccelerator responses to all stimuli. Microinjection of either bicuculline or CGP 52432 into the L5 dorsal horn significantly increased the pressor and cardioaccelerator responses to direct microinjection of l-glutatmate (10 mM, 100 nl) into this spinal segment. The disinhibitory effect of both GABA receptor antagonists on the EPR was abolished by microinjection of the broad-spectrum glutamate receptor antagonist kynurenate (10 mM/100 nl). These data suggest that 1) GABA exerts a tonic inhibition of the EPR at the level of dorsal horn; and 2) that an interaction between glutamatergic and GABAergic inputs exist at the level of dorsal horn, contributing to spinal control of the EPR. PMID:23637133

Wang, Han-Jun; Wang, Wei; Patel, Kaushik P.; Rozanski, George J.

2013-01-01

280

Prototypic GABA(A) receptor agonist muscimol acts preferentially through forebrain high-affinity binding sites.  

PubMed

Muscimol has been regarded as a universal agonist for all gamma-aminobutyric acid type A receptor (GABA(A)-R) subtypes. However, brain regional distribution of muscimol's high-affinity binding sites greatly differs from those of other binding sites of the GABA(A)-R. To test whether behavioral effects of muscimol correlated with the density of high-affinity [(3)H]muscimol binding, we examined several GABA(A)-R subunit gene-modified mouse lines: alpha1, alpha4, or delta-knockouts (KO), alpha4+delta-double KO, and Thy1.2 promoter-driven alpha6 transgenic mice (Thy1alpha6). We determined the high-affinity [(3)H]muscimol binding in brain sections by quantitative autoradiography and sedative/ataxic effects induced in vivo by muscimol using a constant speed rotarod. alpha4-KO mice had reduced [(3)H]muscimol binding in the caudate-putamen, thalamus, and hippocampus, and were less sensitive to the behavioral impairment by muscimol. Similarly, delta-KO mice also had reduced binding to forebrain regions and a lower behavioral sensitivity to muscimol than their wild-type controls. In contrast, alpha1-KO mice had unaltered behavioral sensitivity to muscimol and unaltered [(3)H]muscimol binding, even though previous studies have demonstrated dramatically reduced binding to various other GABA(A)-R sites in these mice. Finally, Thy1alpha6 mice exhibited increased behavioral sensitivity to muscimol, and to another direct GABA-site agonist gaboxadol, and increased [(3)H]muscimol binding in the cerebral cortex and hippocampus. Thus, the differences in sedative and motor-impairing actions of muscimol in various mouse models correlated with the level of forebrain high-affinity [(3)H]muscimol binding. These data suggest that a small special population of GABA(A)-Rs, most likely extrasynaptic non-alpha1-containing receptors, strongly contributes to the in vivo pharmacological effects of muscimol. PMID:20032968

Chandra, Dev; Halonen, Lauri M; Linden, Anni-Maija; Procaccini, Chiara; Hellsten, Kati; Homanics, Gregg E; Korpi, Esa R

2010-03-01

281

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

2014-01-01

282

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

PubMed

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

2014-01-01

283

Studies on the mechanisms of action of picrotoxin, quercetin and pregnanolone at the GABA?1 receptor  

PubMed Central

The mechanisms of action of antagonists of the ?-aminobutyric acid C (GABAC) receptor picrotoxin, quercetin and pregnanolone were studied. Ionic currents (chloride), mediated through human homomeric GABA?1 receptors expressed in Xenopus oocytes, were recorded by two-electrode voltage clamp. Dose–response (D–R) curves and kinetic measurements of GABA?1 currents were carried out in the presence or absence of antagonists. Use-dependent actions were also evaluated. Picrotoxin, quercetin and pregnanolone exerted noncompetitive actions. IC50 values measured at the EC50 for GABA (1 ?M) were as follows: picrotoxin 0.6±0.1 ?M (Hill coefficient n=1.0±0.2); quercetin 4.4±0.4 ?M (n=1.5±0.2); pregnanolone 2.1±0.5 ?M (n=0.8±0.1). These antagonists produced changes only in the slope of the linear current–voltage relationships, which was indicative of voltage-independent effects. The effect of picrotoxin on GABA?1 currents was use-dependent, strongly relied on agonist concentration and showed a slow onset and offset. The mechanism was compatible with an allosteric inhibition and receptor activation was a prerequisite for antagonism. The effect of quercetin was use-independent, showed relatively fast onset and offset, and resulted in a slowed time course of the GABA-evoked currents. The effect of pregnanolone was use-independent, presented fast onset and a very slow washout, and did not affect current activation. All the antagonists accelerated the time course of deactivation of the GABA?1 currents. PMID:14732759

Goutman, Juan D; Calvo, Daniel J

2004-01-01

284

Dominant role of GABA B2 and G?? for GABA B receptor-mediated-ERK 1\\/2\\/CREB pathway in cerebellar neurons  

Microsoft Academic Search

?-aminobutyric acid type B (GABAB) receptor is an allosteric complex made of two subunits, GABAB1 and GABAB2. GABAB2 plays a major role in the coupling to G protein whereas GABAB1 binds GABA. It has been shown that GABAB receptor activates ERK1\\/2 in neurons of the central nervous system, but the molecular mechanisms underlying this event are poorly characterized. Here, we

Haijun Tu; Philippe Rondard; Chanjuan Xu; Federica Bertaso; Fangli Cao; Xueying Zhang; Jean-Philippe Pin; Jianfeng Liu

2007-01-01

285

Determination of GABA, glutamate and carbamathione in brain microdialysis samples by capillary electrophoresis with fluorescence detection.  

PubMed

Disulfiram has been used as a deterrent in the treatment of alcohol abuse for almost 60 years. Our laboratory has shown that a disulfiram metabolite, S-(N,N-diethylcarbamoyl) glutathione (carbamathione), is formed from disulfiram and appears in the brain after the administration of disulfiram. Carbamathione does not inhibit aldehyde dehydrogenase but has been shown to be a partial non-competitive inhibitor of the N-methyl-D-aspartic acid glutamate (Glu) receptor. In light of disulfiram's apparent clinical effectiveness in cocaine dependence, and carbamathione's effect on the N-methyl-D-aspartic acid receptor, the effect of carbamathione on brain Glu and ?-aminobutyric acid (GABA) needs to be further examined. A CE-LIF method based on derivatization with napthalene-2,3-dicarboxyaldehyde to simultaneously detect both neurotransmitter amino acids and carbamathione in brain microdialysis samples is described. The separation of Glu, GABA and carbamathione was carried out using a 50?mmol/L boric acid buffer (pH 9.6) on a 75?cm×50??m id fused-silica capillary (60?cm effective) at +27.5?kV voltage with a run time of 11?min. The detection limits for Glu, GABA and carbamathione were 6, 10 and 15?nmol/L, respectively. This method was used to monitor carbamathione and the amino acid neurotransmitters in brain microdialysis samples from the nucleus accumbens after the administration of an intravenous dose of the drug (200?mg/kg) and revealed a carbamathione-induced change in GABA and Glu levels. This method demonstrates a simple, rapid and accurate measurement of two amino acid neurotransmitters and carbamathione for in vivo monitoring in the brain using microdialysis sampling. PMID:21254127

Kaul, Swetha; Faiman, Morris D; Lunte, Craig E

2011-01-01

286

Activation of presynaptic GABA(B(1a,2)) receptors inhibits synaptic transmission at mammalian inhibitory cholinergic olivocochlear-hair cell synapses.  

PubMed

The synapse between olivocochlear (OC) neurons and cochlear mechanosensory hair cells is cholinergic, fast, and inhibitory. The inhibitory sign of this cholinergic synapse is accounted for by the activation of Ca(2+)-permeable postsynaptic ?9?10 nicotinic receptors coupled to the opening of hyperpolarizing Ca(2+)-activated small-conductance type 2 (SK2)K(+) channels. Acetylcholine (ACh) release at this synapse is supported by both P/Q- and N-type voltage-gated calcium channels (VGCCs). Although the OC synapse is cholinergic, an abundant OC GABA innervation is present along the mammalian cochlea. The role of this neurotransmitter at the OC efferent innervation, however, is for the most part unknown. We show that GABA fails to evoke fast postsynaptic inhibitory currents in apical developing inner and outer hair cells. However, electrical stimulation of OC efferent fibers activates presynaptic GABA(B(1a,2)) receptors [GABA(B(1a,2))Rs] that downregulate the amount of ACh released at the OC-hair cell synapse, by inhibiting P/Q-type VGCCs. We confirmed the expression of GABA(B)Rs at OC terminals contacting the hair cells by coimmunostaining for GFP and synaptophysin in transgenic mice expressing GABA(B1)-GFP fusion proteins. Moreover, coimmunostaining with antibodies against the GABA synthetic enzyme glutamic acid decarboxylase and synaptophysin support the idea that GABA is directly synthesized at OC terminals contacting the hair cells during development. Thus, we demonstrate for the first time a physiological role for GABA in cochlear synaptic function. In addition, our data suggest that the GABA(B1a) isoform selectively inhibits release at efferent cholinergic synapses. PMID:24068816

Wedemeyer, Carolina; Zorrilla de San Martín, Javier; Ballestero, Jimena; Gómez-Casati, María Eugenia; Torbidoni, Ana Vanesa; Fuchs, Paul A; Bettler, Bernhard; Elgoyhen, Ana Belén; Katz, Eleonora

2013-09-25

287

[The interaction of GABA-A receptors with the serotoninergic system of the brain in regulating the testosterone level by the negative feedback mechanism].  

PubMed

A unilateral hemicastration decreased the serotonin and 5-hydroxyindolacetic acid levels in the Wistar rat mediobasal hypothalamus, but not in the midbrain. These neurotransmitters were shown to interact in the process of androgen restoration after the hemicastration. The maximal contribution of GABAergic mechanisms in the testosterone feedback regulation involves the GABA effect via the central GABA-A receptors of the mediobasal hypothalamus' serotoninergic neurons, thus activating the hormone level restoration. The GABA seems to induce a serotonin-independent inhibition of the testosterone level stabilising after hemicastration. PMID:9162401

Amikishieva, A V; Kozlova, O N; Serov, L I; Naumenko, E V

1996-01-01

288

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

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

2013-01-01

289

Identification of gamma-aminobutyric acid and its binding sites in Caenorhabditis elegans  

SciTech Connect

Gamma-aminobutyric acid (GABA), glutamate decarboxylase and GABA-transaminase were identified in the nematode Caenorhabditis elegans. The concentration of GABA in C. elegans is approximately 10-fold lower than the concentration of GABA in rat brain. Glutamate decarboxylase and GABA-transaminase, the GABA anabolic and catabolic enzymes, are also present in C. elegans. Crude membrane fractions were prepared from C. elegans and used to study specific (/sup 3/H) GABA binding sites. GABA binds to C. elegans membranes with high affinity and low capacity. Muscimol is a competitive inhibitor of specific GABA binding with a K/sub I/ value of 120 nM. None of the other GABA agonists or antagonists inhibited greater than 40% of the specific GABA binding at concentrations up to 10/sup -4/M. Thirteen spider venoms were examined as possible GABA agonists or antagonists, the venom from Calilena agelenidae inhibits specific GABA binding with a K/sub I/ value of 6 nl/ml. These results suggest that GABA has a physiological role as a neurotransmitter in C. elegans.

Schaeffer, J.M.; Bergstrom, A.R.

1988-01-01

290

Proton modulation of recombinant GABAA receptors: influence of GABA concentration and the ? subunit TM2–TM3 domain  

PubMed Central

Regulation of GABAA receptors by extracellular pH exhibits a dependence on the receptor subunit composition. To date, the molecular mechanism responsible for the modulation of GABAA receptors at alkaline pH has remained elusive. We report here that the GABA-activated current can be potentiated at pH 8.4 for both ?? and ??? subunit-containing receptors, but only at GABA concentrations below the EC40. Site-specific mutagenesis revealed that a single lysine residue, K279 in the ? subunit TM2–TM3 linker, was critically important for alkaline pH to modulate the function of both ?1?2 and ?1?2?2 receptors. The ability of low concentrations of GABA to reveal different pH titration profiles for GABAA receptors was also examined at acidic pH. At pH 6.4, GABA activation of ??? receptors was enhanced at low GABA concentrations. This effect was ablated by the mutation H267A in the ? subunit. Decreasing the pH further to 5.4 inhibited GABA responses via ??? receptors, whereas those responses recorded from ?? receptors were potentiated. Inserting homologous ? subunit residues into the ?2 subunit to recreate, in ??? receptors, the proton modulatory profile of ?? receptors, established that in the presence of ?2H267, the mutation ?2T294K was necessary to potentiate the GABA response at pH 5.4. This residue, T294, is homologous to K279 in the ? subunit and suggests that a lysine at this position is an important residue for mediating the allosteric effects of both acidic and alkaline pH changes, rather than forming a direct site for protonation within the GABAA receptor. PMID:15946973

Wilkins, Megan E; Hosie, Alastair M; Smart, Trevor G

2005-01-01

291

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: ectl@berkeley.edu [Environmental Chemistry and Toxicology Laboratory, Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720 (United States)

2011-02-01

292

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

Microsoft Academic Search

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

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

2008-01-01

293

Activation of VTA GABA neurons disrupts reward consumption  

PubMed Central

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

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

2012-01-01

294

GABA pharmacology--what prospects for the future?  

PubMed

Following the recognition of GABA as an inhibitory neurotransmitter, the discovery of high affinity GABA uptake, and the characterisation of GABA receptors great progress has been made in developing GABA pharmacology. Tiagabide, the first marketed GABA uptake inhibitor may be followed by new and more selective uptake inhibitors. Knowledge of the molecular pharmacology of GABA-A receptors, both synaptic and non-synaptic, may lead to improved anti-anxiety/anticonvulsant agents devoid of the sedative and dependence liabilities of earlier compounds and new hypnotics. Gaboxadol (THIP) is an example of a novel hypnotic that acts on GABA-A receptors by a non-benzodiazepine mechanism. Exploiting neurosteroid interactions with GABAergic mechanisms also holds much future promise. PMID:15451396

Iversen, Leslie

2004-10-15

295

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

2007-01-01

296

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

PubMed

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

2013-04-01

297

Glutamate suppresses GABA release via presynaptic metabotropic glutamate receptors at baroreceptor neurones in rats  

PubMed Central

The nucleus tractus solitarii (NTS) is essential for coordinating arterial baroreflex control of blood pressure. The primary baroreceptor afferent fibres make their first excitatory synaptic contact at second-order NTS neurones with glutamate as the major neurotransmitter. Glutamate regulates its own release by activating presynaptic metabotropic glutamate autoreceptors (mGluRs) on the baroreceptor central terminals to suppress its further release in frequency-dependent manner. ?-Aminobutyric acid (GABA) interneurones provide the major inhibitory synaptic input. It is the integration of excitatory and inhibitory inputs that shapes the NTS output of baroreceptor signals. We hypothesized that glutamate released from the primary central afferent terminals can spill over to presynaptic mGluRs on GABA interneurones to suppress GABA release at the second-order baroreceptor neurones. We assessed GABA transmission in second-order baroreceptor neurones identified by attached aortic depressor nerve (ADN) boutons. The medial NTS was stimulated to evoke GABA inhibitory postsynaptic currents (eIPSCs). Glutamate spillover, generated by brief 2 s, 25 Hz trains of stimuli applied to the tractus solitarius (TS), induced a small (10%) but significant reduction in the eIPSC amplitudes. The depression was enhanced to a 25% decrease by increasing glutamate in the cleft with a glutamate-uptake inhibitor (M-trans-pyrrolidine-2,4-dicarboxylic acid, 1 ?m), blocked by a Group II mGluR antagonist (LY341495, 200 nm) and mimicked by a Group II agonist ((2S,3S,4S)-CCG/(2S,1?S,2?S)-2-carboxycyclopropyl; L-CCG-I). A presynaptic mGluR locus was established by the mGluR agonist-mediated increase in the paired-pulse ratio of two consecutive eIPSCs in conjunction with the decrease in the first eIPSC, and a decrease in the frequency (39–46% reduction at EC50 concentration), but not amplitude, of spontaneous and miniature GABA IPSCs. The data indicate that endogenous glutamate activation of Group II presynaptic mGluRs can decrease GABA release at the first central synapses, suggesting a heterosynaptic role for the Group II mGluRs in shaping baroreceptor signal transmission. PMID:15539399

Chen, Chao-Yin; Bonham, Ann C

2005-01-01

298

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.

299

Lamina-specific alterations in cortical GABA(A) receptor subunit expression in schizophrenia.  

PubMed

Dysfunction of the dorsolateral prefrontal cortex (DLPFC) in schizophrenia is associated with lamina-specific alterations in particular subpopulations of interneurons. In pyramidal cells, postsynaptic ?-aminobutyric acid (GABA(A)) receptors containing different ? subunits are inserted preferentially in distinct subcellular locations targeted by inputs from specific interneuron subpopulations. We used in situ hybridization to quantify the laminar expression of ?1, ?2, ?3, and ?5 subunit, and of ?1-3 subunit, mRNAs in the DLFPC of schizophrenia, and matched normal comparison subjects. In subjects with schizophrenia, mean GABA(A) ?1 mRNA expression was 17% lower in layers 3 and 4, ?2 expression was 14% higher in layer 2, ?5 expression was 15% lower in layer 4, and ?3 expression did not differ relative to comparison subjects. The mRNA expression of ?2, which preferentially assembles with ?1 subunits, was also 20% lower in layers 3 and 4, whereas ?1 and ?3 mRNA levels were not altered in schizophrenia. These expression differences were not attributable to medication effects or other potential confounds. These findings suggest that GABA neurotransmission in the DLPFC is altered at the postsynaptic level in a receptor subunit- and layer-specific manner in subjects with schizophrenia and support the hypothesis that GABA neurotransmission in this illness is predominantly impaired in certain cortical microcircuits. PMID:20843900

Beneyto, Monica; Abbott, Andrew; Hashimoto, Takanori; Lewis, David A

2011-05-01

300

A comparison of gamma-aminobutyric acid and the semi-rigid analogues 4-aminotetrolic acid, 4-aminocrotonic acid and imidazole-4-acetic acid on the isolated superior cervical ganglion of the rat.  

PubMed Central

1 The rat superior cervical ganglion possesses receptors for gamma-aminobutyric acid (GABA). This can be demonstrated in vitro by recording the changes in ganglionic surface potential which occur after the addition of GABA to the bathing solution. 2 The action of three conformationally-restricted analogues of GABA namely 4-aminotetrolic acid (4-ATA), trans 4-aminocrotonic acid (4-ACA) and imidazole-4-acetic acid (IAA) have been examined for activity at this peripheral receptor. 3 All three analogues depolarized the ganglion in a manner similar to GABA. Their actions were transient and were 'occluded' by GABA; also the dose-response curve in each case was parallel to that of GABA. Molar potencies relative to GABA (= 1) were 4-ACA = 1.48, IAA = 0.100, 4-ATA = 0.0028. 4 The action of each analogue could be blocked by the GABA antagonists bicuculline and tetramethylenedisulphotetramine at doses which had relatively little effect on responses to the cholinomimetic carbachol. 5 4-ACA and IAA (1 mM) significantly reduced the ganglionic accumulation of [3H]-GABA (0.2 muM) by 88% and 58% respectively whereas 4-ATA (1 mM), caused no significant reduction in [3H]-GABA accumulation. PMID:1260178

Bowery, N G; Jones, G P

1976-01-01

301

Presynaptic Nicotinic ?7 and Non-?7 Receptors Stimulate Endogenous GABA Release from Rat Hippocampal Synaptosomes through Two Mechanisms of Action  

PubMed Central

Background Although converging evidence has suggested that nicotinic acetylcholine receptors (nAChR) play a role in the modulation of GABA release in rat hippocampus, the specific involvement of different nAChR subtypes at presynaptic level is still a matter of debate. In the present work we investigated, using selective ?7 and ?4?2 nAChR agonists, the presence of different nAChR subtypes on hippocampal GABA nerve endings to assess to what extent and through which mechanisms they stimulate endogenous GABA release. Methodology/Findings All agonists elicited GABA overflow. Choline (Ch)-evoked GABA overflow was dependent to external Ca2+, but unaltered in the presence of Cd2+, tetrodotoxin (TTX), dihydro-?-erythroidine (DH?E) and 1-(4,4-Diphenyl-3-butenyl)-3-piperidinecarboxylic acid hydrochloride SKF 89976A. The effect of Ch was blocked by methyllycaconitine (MLA), ?-bungarotoxin (?-BTX), dantrolene, thapsigargin and xestospongin C, suggesting that GABA release might be triggered by Ca2+ entry into synaptosomes through the ?7 nAChR channel with the involvement of calcium from intracellular stores. Additionally, 5-Iodo-A-85380 dihydrochloride (5IA85380) elicited GABA overflow, which was Ca2+ dependent, blocked by Cd2+, and significantly inhibited by TTX and DH?E, but unaffected by MLA, SKF 89976A, thapsigargin and xestospongin C and dantrolene. These findings confirm the involvement of ?4?2 nAChR in 5IA85380-induced GABA release that seems to occur following membrane depolarization and opening calcium channels. Conclusions/Significance Rat hippocampal synaptosomes possess both ?7 and ?4?2 nAChR subtypes, which can modulate GABA release via two distinct mechanisms of action. The finding that GABA release evoked by the mixture of sub-maximal concentration of 5IA85380 plus sub-threshold concentrations of Ch was significantly larger than that elicited by the sum of the effects of the two agonists is compatible with the possibility that they coexist on the same nerve terminals. These findings would provide the basis for possible selective pharmacological strategies to treat neuronal disorders that involve the dysfunction of hippocampal cholinergic system. PMID:21346795

Zappettini, Stefania; Grilli, Massimo; Lagomarsino, Federica; Cavallero, Anna; Fedele, Ernesto; Marchi, Mario

2011-01-01

302

Selective GABA transporter inhibitors tiagabine and EF1502 exhibit mechanistic differences in their ability to modulate the ataxia and anticonvulsant action of the extrasynaptic GABA(A) receptor agonist gaboxadol.  

PubMed

Modulation of the extracellular levels of GABA via inhibition of the synaptic GABA transporter GAT1 by the clinically effective and selective GAT1 inhibitor tiagabine [(R)-N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]nipecotic acid; Gabitril] has proven to be an effective treatment strategy for focal seizures. Even though less is known about the therapeutic potential of other GABA transport inhibitors, previous investigations have demonstrated that N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]-3-hydroxy-4-(methylamino)-4,5,6,7-tetrahydrobenzo[d]isoxazol-3-ol (EF1502), which, like tiagabine, is inactive on GABA(A) receptors, inhibits both GAT1 and the extrasynaptic GABA and betaine transporter BGT1, and exerts a synergistic anticonvulsant effect when tested in combination with tiagabine. In the present study, the anticonvulsant activity and motor impairment associated with systemic administration of gaboxadol (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol), which, at the doses used in this study (i.e., 1-5 mg/kg) selectively activates extrasynaptic ?4-containing GABA(A) receptors, was determined alone and in combination with either tiagabine or EF1502 using Frings audiogenic seizure-susceptible and CF1 mice. EF1502, when administered in combination with gaboxadol, resulted in reduced anticonvulsant efficacy and Rotarod impairment associated with gaboxadol. In contrast, tiagabine, when administered in combination with gaboxadol, did not modify the anticonvulsant action of gaboxadol or reverse its Rotarod impairment. Taken together, these results highlight the mechanistic differences between tiagabine and EF1502 and support a functional role for BGT1 and extrasynaptic GABA(A) receptors. PMID:21450931

Madsen, Karsten K; Ebert, Bjarke; Clausen, Rasmus P; Krogsgaard-Larsen, Povl; Schousboe, Arne; White, H Steve

2011-07-01

303

Morphological and GAD immunocytochemical properties of the dorsal lateral geniculate nucleus in a reptile.  

PubMed

Morphological and glutamic acid decarboxylase (GAD) immunocytochemical properties of the dorsal part of the lateral geniculate nucleus were investigated in reptiles, Caiman crocodilus. GAD immunoreactive neurons, although sparse, were found in the dorsal part of the lateral geniculate nucleus. In addition, puncta and fibers immunoreactive for GAD were also observed in this same nucleus. These results in Caiman utilizing GAD are similar to observations on the dorsal part of the lateral geniculate nucleus of other reptiles in which antisera to gamma amino butyric acid (GABA) were used. PMID:8193926

Pritz, M B; Stritzel, M E

1994-01-01

304

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)

2004-05-25

305

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

PubMed

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

2014-12-01

306

GABA B Receptors Couple Directly to the Transcription Factor ATF4  

Microsoft Academic Search

The inhibitory neurotransmitter ?-aminobutyric acid (GABA), acts at ionotropic (GABAA and GABAC) and metabotropic (GABAB) receptors. Functional GABAB receptors are heterodimers of GABAB(1) and GABAB(2) subunits. Here we show a robust, direct, and specific interaction between the coiled-coil domain present in the C-terminus of the GABAB(1) subunit and the transcription factor ATF4 (also known as CREB2). ATF4 and GABAB(2) binding

Ellen Vernon; Guido Meyer; Lisa Pickard; Kumlesh Dev; Elek Molnar; Graham L. Collingridge; Jeremy M. Henley

2001-01-01

307

The Depolarizing Action of GABA Controls Early Network Activity in the Developing Hippocampus  

Microsoft Academic Search

Early in postnatal life ?-aminobutyric acid (GABA), the primary inhibitory transmitter in adults, excites targeted neurons\\u000a by an outwardly directed flux of chloride which results from the unbalance between the cation–chloride cotransporters NKCC1\\u000a and KCC2, involved in chloride uptake and extrusion, respectively. This effect contributes to generate synchronized network\\u000a activity or giant depolarizing potentials (GDPs) in the developing hippocampus. Here,

Enrico Cherubini; Marilena Griguoli; Victoria Safiulina; Laura Lagostena

2011-01-01

308

Differential expression patterns of GABA transporters (GAT1–3) in the rat olfactory bulb  

Microsoft Academic Search

The localization of GABA transporters 1–3 (GAT1–3) was investigated in the rat olfactory bulb by using in situ hybridization and immunohistochemistry. In the glomerular and the internal granular layers, GAT1 mRNA was expressed in most of periglomerular and granule cells, which are known to be GABAergic. In addition, we compared GAT1 mRNA expression with that of glutamic acid decarboxylase67 (GAD67)

Mitsuhiro Nishimura; Kohji Sato; Makoto Mizuno; Ikuto Yoshiya; Shoichi Shimada; Naoaki Saito; Masaya Tohyama

1997-01-01

309

Molecular and pharmacological evidence for a facilitatory functional role of pre-synaptic GLUK2/3 kainate receptors on GABA release in rat trigeminal caudal nucleus  

PubMed Central

Background Gamma-aminobutyric acid (GABA) and glutamate (GLU) are involved in nociceptive signals processing in the trigeminal system. In this study, we investigated the influence of excitatory transmission on GABA release in nerve terminals isolated from the rat trigeminal caudal nucleus (TCN). Methods We utilize biochemical (superfused synaptosomes loaded with [3H]GABA) and morphological (immunofluorescence experiments with specific antibody) techniques. Results Our results show that GLU potentiates the release of [3H]GABA evoked by 9, 15 and 30 mM [K+]e; 15 mM [K+]e-evoked [3H]GABA release was also reinforced by domoate and kainate (KA), two naturally occurring GLU-receptor agonists. The enhancement of 15 mM [K+]e-evoked [3H]GABA release produced by 100 ?M KA was abolished by NBQX, a mixed AMPA/KA receptor antagonist, but was not affected by GYKI52466, a selective AMPA receptor antagonist. ATPA, a selective agonist for KA receptors containing the GLUK1 subunit, had no effect on depolarization-induced [3H]GABA release, and UBP310, which selectively antagonizes these same receptors, failed to reverse the KA-induced potentiation of 15 mM [K+]e-evoked [3H]GABA release. The KA-induced potentiation was also unaffected by concanavalin A (10 ?M), a positive allosteric modulator of GLUK1- and GLUK2-containing KA receptors. Immunofluorescence experiments revealed that GABAergic nerve terminals in the TCN differentially expressed GLUK subunits, with GLUK2/3-positive terminals being twice more abundant than GLUK1-containing synaptosomes. Conclusions These findings indicate that pre-synaptic KA receptors facilitating GABA release from TCN nerve terminals mainly express GLUK2/GLUK3 subunits, supporting the notion that different types of KA receptors are involved in the various stages of pain transmission. PMID:22392917

Samengo, I; Currò, D; Navarra, P; Barrese, V; Taglialatela, M; Martire, M

2012-01-01

310

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

Microsoft Academic Search

-Aminobutyric acid (GABA) transporters (GATs) play an important role in inhibitory neurotransmission by clearing synaptically released GABA and by maintaining low resting levels of GABA in synaptic and extrasynaptic regions. In certain brain regions, vesicular zinc is colocalized and coreleased with glutamate and modulates the behavior of a number of channels, receptors, and transporters. We examined the effect of zinc

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

2005-01-01

311

Regulation of arterial pressure by the paraventricular nucleus in conscious rats: interactions among glutamate, GABA, and nitric oxide  

PubMed Central

The paraventricular nucleus (PVN) of the hypothalamus is an important site for autonomic and neuroendocrine regulation. Experiments in anesthetized animals and in vitro indicate an interaction among gamma-aminobutyric acid (GABA), nitric oxide (NO), and glutamate in the PVN. The cardiovascular role of the PVN and interactions of these neurotransmitters in conscious animals have not been evaluated fully. In chronically instrumented conscious rats, mean arterial pressure (MAP) and heart rate (HR) responses to microinjections (100 nl) in the region of the PVN were tested. Bilateral blockade of ionotropic excitatory amino acid (EAA) receptors (kynurenic acid, Kyn) in the PVN produced small but significant decreases in MAP and HR. GABAA receptor blockade (bicuculline, Bic), and inhibition of NO synthase [(NOS), N-(G)-monomethyl-L-arginine, L-NMMA] each increased MAP and HR. The NO donor sodium nitroprusside (SNP) produced depressor responses that were attenuated by Bic. NOS inhibition potentiated both pressor responses to the selective EAA agonist, N-methyl-D-aspartic acid (NMDA), and depressor responses to Kyn. Increases in MAP and HR due to Bic were blunted by prior blockade of EAA receptors. Thus, pressor responses to GABA blockade require EAA receptors and GABA neurotransmission contributes to NO inhibition. Tonic excitatory effects of glutamate in the PVN are tonically attenuated by NO. These data demonstrate that, in the PVN of conscious rats, GABA, glutamate, and NO interact in a complex fashion to regulate arterial pressure and HR under normal conditions. PMID:23316170

Martins-Pinge, Marli C.; Mueller, Patrick J.; Foley, C. Michael; Heesch, Cheryl M.; Hasser, Eileen M.

2013-01-01

312

Co-release of acetylcholine and gamma-aminobutyric acid by a retinal neuron  

SciTech Connect

Rabbit retinas were vitally stained with 4',6-diamidino-2-phenylindole (DAPI), a fluorescent compound that selectively accumulates within the cholinergic amacrine cells. The retinas were then incubated in vitro in the presence of radioactive gamma-aminobutyric acid (GABA) and autoradiographed. The cells that accumulated DAPI were found to accumulate GABA, confirming immunohistochemical evidence that the cholinergic amacrine cells contain GABA. Incubation of retinas in the presence of elevated concentrations of K+ caused them to release acetylcholine and GABA, and autoradiography showed depletion of radioactive GABA from the cholinergic amacrine cells. This indicates that the cholinergic amacrine cells can secrete acetylcholine and GABA. Retinas were double-labeled with (14C)GABA and (3H)acetylcholine, allowing simultaneous measurement of their release. The release of (14C)GABA was found to be independent of extracellular Ca2+. Radioactive GABA synthesized endogenously from (14C)glutamate behaved the same way as radioactive GABA accumulated from the medium. In the same experiments the simultaneously measured release of (3H)acetylcholine was strongly Ca2+-dependent, indicating that the releases of acetylcholine and GABA are controlled by different mechanisms. Synaptic vesicles immunologically isolated from double-labeled retinas contained much (3H)acetylcholine and little or no (14C)GABA. These results suggest that the cholinergic amacrine cells release acetylcholine primarily by vesicle exocytosis and release GABA primarily by means of a carrier.

O'Malley, D.M.; Masland, R.H.

1989-05-01

313

Electrophysiological evidence for 4-isobutyl-3-isopropylbicyclophosphorothionate as a selective blocker of insect GABA-gated chloride channels.  

PubMed

Invertebrate ?-aminobutyric acid (GABA)-gated chloride channels (GABACls) and glutamate-gated chloride channels (GluCls), which function as inhibitory neurotransmitter receptors, are important targets of insecticides and antiparasitic agents. The antagonism of GABACls and GluCls by 4-isobutyl-3-isopropylbicyclophosphorothionate (PS-14) was examined in cultured cockroach and rat neurons using a whole-cell patch-clamp method. The results indicated that PS-14 selectively blocks cockroach GABACls relative to cockroach GluCls and rat GABACls. PS-14 represents a useful probe for the study of insect GABA receptors. PMID:23591113

Akiyoshi, Yuki; Ju, Xiu-Lian; Furutani, Shogo; Matsuda, Kazuhiko; Ozoe, Yoshihisa

2013-06-01

314

In Intact Islets Interstitial GABA Activates GABAA Receptors That Generate Tonic Currents in ?-Cells  

PubMed Central

In the rat islets ?-aminobutyric acid (GABA) is produced by the ?-cells and, at least, the ?-cells express the GABAA receptors (GABAA channels). In this study, we examined in intact islets if the interstitial GABA activated the GABAA receptors. We used the patch-clamp technique to record whole-cell and single-channel currents and single-cell RT-PCR to identify the cell-type we recorded from, in the intact rat islets. We further identified which GABAA receptor subunits were expressed. We determined the cell-type of 43 cells we recorded from and of these 49%, 28% and 7% were ?, ? and ?-cells, respectively. In the remaining 16% of the cells, mRNA transcripts of more than one hormone gene were detected. The results show that in rat islets interstitial GABA activates tonic current in the ?-cells but not in the ?-cells. Seventeen different GABAA receptor subunits are expressed with high expression of ?1, ?2, ?4, ?6, ?3, ?1, ?, ?1, ?2 and ?3 subunits whereas no expression was detected for ?5 or ? subunits. The abundance of the GABAA receptor subunits detected suggests that a number of GABAA receptor subtypes are formed in the islets. The single-channel and tonic currents were enhanced by pentobarbital and inhibited by the GABAA receptor antagonist SR-95531. The single-channel conductance ranged from 24 to 105 pS. Whether the single-channel conductance is related to subtypes of the GABAA receptor or variable interstitial GABA concentrations remains to be determined. Our results reveal that GABA is an extracellular signaling molecule in rat pancreatic islets and reaches concentration levels that activate GABAA receptors on the glucagon-releasing ?-cells. PMID:23826240

Jin, Yang; Korol, Sergiy V.; Jin, Zhe; Barg, Sebastian; Birnir, Bryndis

2013-01-01

315

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.

2014-01-01

316

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

PubMed

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

1998-01-01

317

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

PubMed Central

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

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

2014-01-01

318

Molecular regulation of glutamate and GABA transporter proteins by clobazam during epileptogenesis in Fe(+++)-induced epileptic rats.  

PubMed

To assess the molecular effects of the antiepileptic drug clobazam (CLB, 1,5-benzodiazepine), a benzodiazepine effective in the management of epilepsy, we performed a series of experiments using rats with chronic, spontaneous recurrent seizures induced by amygdalar injection of FeCl(3). Experimental animals were treated for 14 days with CLB. We then measured the expression of glutamate and GABA transporter proteins and evaluated the changes that occurred in these proteins using both experimental and control animals. CLB treatment was associated with an increase in the production of GLT-1 in the contra-lateral hippocampus of animals receiving amygdalar FeCl(3) and CLB treatment. CLB treatment up-regulated the GABA transporter GAT3 in the contra-lateral hippocampus of animals with chronic, recurrent seizures. In contrast, CLB had no effect on the expression of EAAC1 and GAT1 in the hippocampus or the cortex in control animal groups. Chronic epileptogenesis may be associated with down-regulation of the production of glial excitatory amino acid transporters, GLAST and GLT-1, proteins that cause increase in the basal extracellular concentrations of glutamate. Elevated GABA transporter expression results in increased reverse transport of GABA to the extracellular space during periods of excitation. In addition to allosteric activation of GABA(A) receptors, this study suggests that CLB might exhibit its antiepileptic action by increasing GLT-1 expression and GAT3 in the hippocampus of rats with chronic seizures. PMID:16274841

Doi, Taku; Ueda, Yuto; Tokumaru, Jun; Willmore, L James

2005-12-14

319

Intracellular pH of crab and crayfish muscle fibre types during GABA application and inhibitory nerve stimulation.  

PubMed

The inhibitory motoneurons of crustaceans form synapses both with the sarcolemma of muscle fibres and with the very distal branchings of the excitatory motoneurons. The transmitter of these synapses is GABA (gamma-aminobutyric acid) which is known to open Cl- channels. Studies on the dactyl opener muscle of crayfish suggest that application of GABA not only leads to an increase in the Cl- permeability but also to a considerable HCO3- conductance that causes an intracellular acidification. To investigate possible physiological implications, we measured the intracellular pH of various muscle fibre types of crayfish and crab using pH-sensitive microelectrodes. Independent of the presence or absence of inhibitory innervation, bath application of 10(-5) mol l(-1) GABA led to acidification in all fibre types (pH change: 0.14 +/- 0.08, n = 11). In no preparation was a change in intracellular pH observed upon stimulation of specific or common inhibitory motoneurons with 1040 pulses s(-1) for 2-5 min. The results suggest that HCO3- conductance cannot be activated through synaptic GABA receptors. However, all crustacean muscle fibre types seem to possess extrasynaptic GABA-sensitive channels that exhibit a considerable HCO3- conductance. The physiological importance of these channels remains to be elucidated. PMID:11128442

Günzel, D; Galler, S

2000-11-01

320

Modulation of diazepam-insensitive GABA(A) receptors by micromolar concentrations of thyroxine and related compounds in vitro.  

PubMed

The effects of thyroxine and its related compounds on the benzodiazepine-insensitive ?-aminobutyric acid type A (GABA(A)) receptors were studied. Thyroxine at micromolar concentrations potentiated the (3)H-Ro15-4513 binding to rat brain membranes in-vitro in the thalamus, striatum, cortex and hippocampus, but not in cerebellum. In the thalamus, the rank order of potency was the following: 3,3',5,5'-tetraiodothyroacetic acid (TETRAC)>L-thyroxine>3,5-diiodo-l-thyronine (3,5-T2). TETRAC induced a slight potentiation of flumazenil binding to diazepam-sensitive GABA(A) receptors in the thalamus and striatum while no effect was found in cortex and hippocampus. Consequently, we examined whether these compounds could exert their modulatory effect on the currents mediated by benzodiazepine-insensitive GABA(A) receptors. The diazepam-insensitive GABA(A) receptor-mediated currents were recorded from acutely isolated rat ventrobasal thalamic neurons by applying low concentrations of 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP). TETRAC and thyroxine at low ?M concentrations potentiated the THIP-evoked currents, although 3,5-T2 had no effect on the THIP-induced currents. Ethanol had no effect on the enhancing effects of TETRAC. TETRAC itself evoked GABA(A) receptor-mediated currents at high concentrations beyond 30 ?M. Although the effects of TETRAC and thyroxine were observed at non-physiological concentrations of hormones, the present results might lead to new lead structures with specificity to diazepam-insensitive GABA(A) receptor subtypes. PMID:23103412

Ishibashi, Hitoshi; Witt, Michael-Robin; Nabekura, Junichi; Nielsen, Mogens

2013-01-15

321

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.

1989-01-01

322

Gamma Hydroxybutyric Acid (GHB) Intoxication  

Microsoft Academic Search

Gamma-aminobutyric acid (GABA) was discovered as the predominant inhibitory central nervous sys- tem (CNS) neurotransmitter in 1956. This prompted a search for a GABA analog that would cross the blood-brain barrier for possible therapeutic use. During this search, gamma-hydroxybutyric acid (GHB) was found in the brain and subsequently synthesized in the laboratory in 1964. 1,2 Since its discovery, GHB has

Phillip E. Mason; William P. Kerns II

2002-01-01

323

Colocalization of synaptic GABA C -receptors with GABA A -receptors and glycine-receptors in the rodent central nervous system  

Microsoft Academic Search

Fast inhibition in the nervous system is preferentially mediated by GABA- and glycine-receptors. Two types of ionotropic GABA-receptor,\\u000a the GABAA-receptor and GABAC-receptor, have been identified; they have specific molecular compositions, different sensitivities to GABA, different kinetics,\\u000a and distinct pharmacological profiles. We have studied, by immunocytochemistry, the synaptic localization of glycine-, GABAA-, and GABAC-receptors in rodent retina, spinal cord, midbrain, and

Renata Frazao; Maria Ines Nogueira; Heinz Wässle

2007-01-01

324

A single point mutation of the GABA(A) receptor alpha5-subunit confers fluoxetine sensitivity.  

PubMed

Fluoxetine has been reported to be a novel allosteric modulator of GABA(A) receptors with the notable exception of receptors that contain the alpha5-subunit isoform [Robinson, R.T., Drafts, B.C., Fisher, J.L., 2003. Fluoxetine increases GABA(A) receptor activity through a novel modulatory site. J. Pharmacol. Exp. Ther. 304, 978-984]. A mutagenic strategy has been used to investigate the structural basis for the insensitivity of this subunit. An alpha1/alpha5-subunit chimeragenesis approach first demonstrated the importance of the alpha1-subunit N-terminal sequence E165-D183 (corresponding to alpha5 E169-D187) in fluoxetine modulation. Specific amino acid substitutions in this domain subsequently revealed that a single mutation in the alpha5-subunit to the equivalent residue in alpha1 (T179A) was sufficient to confer fluoxetine sensitivity to the alpha5-containing receptor. However, the reciprocal mutation in the alpha1-subunit (A175T) did not result in a loss in sensitivity, suggesting the involvement of additional determinants for fluoxetine modulation. A comparative modeling approach was used to probe amino acids that may lie in close proximity to alpha1A175. This led serendipitously to the identification of a specific residue, alpha1F45, which, when mutated to an alanine, resulted in a significant decrease in potency for activation of the receptor by GABA and also reduced the efficacies of the partial agonists, THIP and P4S. PMID:17045313

Derry, Jason M C; Paulsen, Isabelle M; Davies, Martin; Dunn, Susan M J

2007-02-01

325

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

1995-09-01

326

DNA sequence and site of mutation of the GABA receptor of cyclodiene-resistant red flour beetle, Tribolium castaneum.  

PubMed

Using polymerase chain reactions (PCR) on cDNA, the DNA sequence of a membrane spanning region of a GABA receptor of the red flour beetle, Tribolium castaneum was identified. The deduced amino acid sequence indicates that its basic structure is similar to the GABA receptor of Rdl type subunits of Drosophila melanogaster and of Blattella germanica. Particularly conserved are M1, M2 and M3 segments. Within this 146 amino acid stretch, the GABA receptor from the red flour beetle differed from corresponding ones from Drosophila and Rdl subunit of B. germanica by 12 and eight amino acids, respectively. By using an identical approach, the corresponding DNA region was sequenced from the cDNA of a cyclodiene-resistant strain of T. castaneum. While two points of mutation were found only one mutation in DNA was found to result in an amino acid shift. The site of mutation was at the 5th amino acid of the M2 cylinder where G to T conversion of the GCT codon resulted in a conversion of alanine to serine. This is qualitatively the same mutational switch of alanine to serine in resistant strains previously reported to have occurred in cyclodiene-resistant Drosophila melanogaster, Aedes aegypti and Blattella germanica, indicating that this amino acid change is the likely cause for evolution of the nerve insensitive type of resistance to cyclodiene insecticides. PMID:7613764

Miyazaki, M; Matsumura, F; Beeman, R W

1995-07-01

327

Effects of GABA agonists on Herxheimer microshock in guinea pigs  

Microsoft Academic Search

In this paper we describe the first observation of GABA inhibition in an experimental model of asthmain vivo. Guinea-pigs were actively sensitized with ovalbumin i.p. and 20 days later the Herxheimer microshock was performed. GABA and (?)-baclofen injected 20 min previously significantly prevented the development of microshock. Therefore GABAergic drugs appear to modulatein vivo anaphylactic reaction. The value of this

S. Luzzi; S. Franchi-Micheli; M. Ciuffi; Lucilla Zilletti

1986-01-01

328

Early Evolution of Ionotropic GABA Receptors and Selective Regimes Acting on the Mammalian-Specific Theta and Epsilon Subunits  

PubMed Central

Background The amino acid neurotransmitter GABA is abundant in the central nervous system (CNS) of both invertebrates and vertebrates. Receptors of this neurotransmitter play a key role in important processes such as learning and memory. Yet, little is known about the mode and tempo of evolution of the receptors of this neurotransmitter. Here, we investigate the phylogenetic relationships of GABA receptor subunits across the chordates and detail their mode of evolution among mammals. Principal Findings Our analyses support two major monophyletic clades: one clade containing GABAA receptor ?, ?, and ? subunits, and another one containing GABAA receptor ?, ?, ?, ?, and ? subunits. The presence of GABA receptor subunits from each of the major clades in the Ciona intestinalis genome suggests that these ancestral duplication events occurred before the divergence of urochordates. However, while gene divergence proceeded at similar rates on most receptor subunits, we show that the mammalian-specific subunits ? and ? experienced an episode of positive selection and of relaxed constraints, respectively, after the duplication event. Sites putatively under positive selection are placed on a three-dimensional model obtained by homology-modeling. Conclusions Our results suggest an early divergence of the GABA receptor subunits, before the split from urochordates. We show that functional changes occurred in the lineages leading to the mammalian-specific subunit ?, and we identify the amino acid sites putatively responsible for the functional divergence. We discuss potential consequences for the evolution of mammals and of their CNS. PMID:17878929

Martyniuk, Christopher J.; Aris-Brosou, Stéphane; Drouin, Guy; Cahn, Joel; Trudeau, Vance L.

2007-01-01

329

Accumbal and pallidal dopamine, glutamate and GABA overflow during cocaine self-administration and its extinction in rats.  

PubMed

We investigated the changes in dopamine (DA), glutamate and ?-aminobutyric acid (GABA) during cocaine self-administration in rats implanted with guide cannulae into the nucleus accumbens and ventral pallidum. After stabilized cocaine self-administration, separate groups of rats underwent extinction (10 days) procedure in which cocaine infusion was replaced by saline injections. With using a 'yoked' procedure, the effects of cocaine or its withdrawal on the level of neurotransmitters were evaluated by dual-probe microdialysis. Repeated cocaine administration reduced basal glutamate levels in the nucleus accumbens and ventral pallidum, whereas it did not affect basal accumbal DA levels. Only rats that self-administered cocaine had increased basal GABA overflow in both examined brain structures. Active or passive cocaine administration elevated extracellular accumbal DA, however, the extent of cocaine-evoked DA level was significantly higher in rats that self-administered cocaine while both groups of animals showed also an attenuation of GABA level in the nucleus accumbens. On day 10 of extinction training, rats previously given cocaine revealed decreases in the basal accumbal concentration of glutamate while the basal GABA levels were significantly enhanced as compared with baseline of saline-yoked controls. Potassium depolarization delayed the reduction of the accumbal and pallidal extracellular glutamate levels in the active and passive cocaine groups. The present data indicate that changes in DA and GABA neurotransmission during maintenance phase mirror the motivational aspects of cocaine intake. Depending on acute (24 hours) or late (10 days) cocaine withdrawal, different neurotransmitter systems (i.e. glutamate or GABA) seem to be involved. PMID:23311632

Wydra, Karolina; Golembiowska, Krystyna; Zaniewska, Magdalena; Kami?ska, Katarzyna; Ferraro, Luca; Fuxe, Kjell; Filip, Ma?gorzata

2013-03-01

330

Pharmacological characterization of a novel positive modulator at alpha 4 beta 3 delta-containing extrasynaptic GABA(A) receptors.  

PubMed

The in vitro and in vivo pharmacological effects of [2-amino-4-(2,4,6-trimethylbenzylamino)-phenyl]-carbamic acid ethyl ester (AA29504), which is a close analogue of retigabine, have been investigated. AA29504 induced a rightward shift of the activation threshold at cloned KCNQ2, 2/3 and 4 channels expressed in Xenopus oocytes, with a potency 3-4fold lower than retigabine. AA29504 (1 muM) had no agonist activity when tested at alpha(1)beta(3)gamma(2s) or alpha(4)beta(3)delta GABA(A) receptors expressed in Xenopus oocytes, but left-shifted the EC(50) for GABA and gaboxadol (THIP) at both receptors. The maximum GABA response at alpha(1)beta(3)gamma(2s) receptors was unchanged by AA29504 (1 muM), but increased 3-fold at alpha(4)beta(3)delta receptors. In slices prepared from the prefrontal cortex of adult rats AA29504 had no effect alone on the average IPSC or the tonic current in layer II/III pyramidal neurons, but potentiated the effect of gaboxadol on both phasic and tonic currents. Thus, the effects of gaboxadol could be positively modulated by AA29504. Systemic administration of AA29504 at doses relevant for modulating GABA transmission produced anxiolytic effects and reduced motor coordination consistent with activity at GABA(A) receptors. We conclude that AA29504 exerts a major action via alpha(4)beta(3)delta-containing GABA(A) receptors, which will be important for interpreting its effect in vivo. PMID:20060846

Hoestgaard-Jensen, K; Dalby, N O; Wolinsky, T D; Murphey, C; Jones, K A; Rottländer, M; Frederiksen, K; Watson, W P; Jensen, K; Ebert, B

2010-01-01

331

Convergent control of synaptic GABA release from rat dorsal horn neurones by adenosine and GABA autoreceptors  

PubMed Central

Perforated patch clamp recordings were performed on cultured superficial neonatal rat dorsal horn (DH) spinal cord neurones in order to study the presynaptic modulation of GABA release at unitary synaptic connections. Since ATP can be coreleased with GABA at about two-thirds of GABAergic synapses between DH neurones, and can be rapidly metabolized to adenosine in the extracellular space, we investigated the potential role of A1 adenosine receptors and GABAB receptors which might function as inhibitory autoreceptors. Adenosine and GABAB receptor agonists reduced the amplitude of electrically evoked GABAergic inhibitory postsynaptic currents (eIPSCs) as well as the frequency of GABAergic miniature IPSCs, suggesting a presynaptic action of these substances. The actions of adenosine were blocked by the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). The effects of adenosine and GABAB agonists were occlusive, indicating a functional convergence of the signalling pathways engaged by A1 and GABAB receptors. A1 and GABAB antagonists increased the amplitude of eIPSCs in a supra-additive manner, suggesting a tonic activation of these receptors by ambient adenosine and GABA. Moreover, using trains of electrical stimulations, we were able to unravel a phasic (activity-dependent) activation of presynaptic A1 and GABAB autoreceptors only in the case of neurones coreleasing ATP and GABA, despite the presence of functional presynaptic A1 and GABAB receptors on all GABAergic DH neurones. This selective, convergent and activity-dependent inhibition of GABA release by A1 and GABAB autoreceptors might modulate the integrative properties of postsynaptic DH neurones under physiological conditions and/or during the development of pathological pain states. PMID:12844515

Hugel, Sylvain; Schlichter, Rémy

2003-01-01

332

Histaminergic and glycinergic modulation of GABA release in the vestibular nuclei of normal and labyrinthectomised rats  

PubMed Central

Vestibular compensation (the behavioural recovery that follows unilateral vestibular de-afferentation), is facilitated by histamine, and is associated with increased central histamine release and alterations in histamine H3 receptor expression in the vestibular nuclei. However, little is known of the effects of histamine on neurotransmission in the vestibular nuclei, and the mechanisms by which histamine may influence compensation are unclear. Here we examined the modulatory effects of histaminergic agents on the release of amino acid neurotransmitters in slices of the medial vestibular nucleus (MVN) prepared from normal and labyrinthectomised rats. The release of GABA, but not glutamate, glycine or aspartate, was robustly and reproducibly evoked by a high-K+ stimulus applied to normal MVN slices. Histamine inhibited the evoked release of GABA, both through a direct action on presynaptic H3 receptors (presumably located on GABAergic terminals), and through a novel, indirect pathway that involved the increased release of glycine by activation of postsynaptic H1/H2 receptors (presumably on glycinergic neurons). After unilateral labyrinthectomy (UL), the direct H3 receptor-mediated inhibition of GABA release was profoundly downregulated in both ipsi-lesional and contra-lesional MVNs. This effect appeared within 25 h post-UL and persisted for at least 3 weeks post-UL. In addition, at 25 h post-UL the indirect glycinergic pathway caused a marked suppression of GABA release in the contra-lesional but not ipsi-lesional MVN, which was overcome by strychnine. Stimulation of histamine H3 receptors at 25 h post-UL restored contra-lesional GABA release to normal, suggesting that acutely after UL H3 receptors may strongly modulate glycinergic and GABAergic neurotransmission in the MVN. These findings are the first to demonstrate the modulatory actions of the histaminergic system on neurotransmission in the vestibular nuclei, and the changes that occur during vestibular system plasticity. During vestibular compensation, histaminergic modulation of glycine and GABA release may contribute to the rebalancing of neural activity in the vestibular nuclei of the lesioned and intact sides. PMID:17038426

Bergquist, Filip; Ruthven, Alasdair; Ludwig, Mike; Dutia, Mayank B

2006-01-01

333

Neurotransmitter GABA activates muscle but not ?7 nicotinic receptors.  

PubMed

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

2015-01-01

334

Evaluation of improved ?-aminobutyric acid production in yogurt using Lactobacillus plantarum NDC75017.  

PubMed

Most ?-aminobutyric acid (GABA)-producing microorganisms are lactic acid bacteria (LAB), but the yield of GABA is limited in most of these GABA-producing strains. In this study, the production of GABA was carried out by using Lactobacillus plantarum NDC75017, a strain screened from traditional fermented dairy products in China. Concentrations of substrate (l-monosodium glutamate, L-MSG) and coenzyme (pyridoxal-5-phosphate, PLP) of glutamate decarboxylase (GAD) and culture temperature were investigated to evaluate their effects on GABA yield of Lb. plantarum NDC75017. The results indicated that GABA production was related to GAD activity and biomass of Lb. plantarum NDC75017. Response surface methodology was used to optimize conditions of GABA production. The optimal factors for GABA production were L-MSG at 80 mM, PLP at 18?M, and a culture temperature of 36°C. Under these conditions, production of GABA was maximized at 314.56mg/100 g. Addition of Lb. plantarum NDC75017 to a commercial starter culture led to higher GABA production in fermented yogurt. Flavor and texture of the prepared yogurt and the control yogurt did not differ significantly. Thus, Lb. plantarum NDC75017 has good potential for manufacture of GABA-enriched fermented milk products. PMID:25622870

Shan, Y; Man, C X; Han, X; Li, L; Guo, Y; Deng, Y; Li, T; Zhang, L W; Jiang, Y J

2015-04-01

335

?-Aminobutyric acid mimetic drugs differentially inhibit the dopaminergic response to cocaine  

Microsoft Academic Search

Dopaminergic activity in the mesocorticolimbic system is associated with reinforcing properties of psychostimulant drugs. We previously demonstrated that increased ?-aminobutyric acid (GABA)-ergic activity produced by ?-vinyl GABA [d,l-4-amino-hex-5-enoic acid (Vigabatrin®)], an irreversible inhibitor of GABA-transaminase, attenuated cocaine, nicotine, heroin, alcohol, and methamphetamine-induced increases in extracellular nucleus accumbens dopamine as well as behaviors associated with these biochemical changes. In the present

Madina R Gerasimov; Wynne K Schiffer; Jonathan D Brodie; Ian C Lennon; Stephen J. C Taylor; Stephen L Dewey

2000-01-01

336

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

2013-01-01

337

GABA transporter GAT1: a crucial determinant of GABAB receptor activation in cortical circuits?  

PubMed

The GABA transporter 1 (GAT1), the main plasma membrane GABA transporter in brain tissue, mediates translocation of GABA from the extracellular to the intracellular space. Whereas GAT1-mediated uptake could generally terminate the synaptic effects of GABA, recent studies suggest a more complex physiological role. This chapter reviews evidence suggesting that in hippocampal and neocortical circuits, GAT1-mediated GABA transport regulates the electrophysiological effects of GABA(B) receptor (GABA(B)R) activation by synaptically-released GABA. Contrasting with synaptic GABA(A) receptors, GABA(B)Rs display high GABA binding affinity, slow G protein-coupled mediated signaling, and a predominantly extrasynaptic localization. Such GABA(B)R properties determine production of slow inhibitory postsynaptic potentials (IPSPs) and slow presynaptic effects. Such effects possibly require diffusion of GABA far away from the release sites, and consequently both GABA(B)R-mediated IPSPs and presynaptic effects are strongly enhanced when GAT1-mediated uptake is blocked. Studies are reviewed here which indicate that GABA(B)R-mediated IPSPs seem to be produced by dendrite-targeting GABA neurons including specifically, although perhaps not exclusively, the neurogliaform cell class. In contrast, the GABA interneuron subtypes that synapse onto the perisomatic membrane of pyramidal cells mostly signal via synaptic GABA(A)Rs. This chapter reviews data suggesting that neurogliaform cells produce electrophysiological effects onto other neurons in the cortical cell network via GABA(B)R-mediated volume transmission that is highly regulated by GAT1 activity. Therefore, the role of GAT1 in controlling GABA(B)R-mediated signaling is markedly different from its regulation of GABA(A)R-mediated fast synaptic transmission. PMID:20655483

Gonzalez-Burgos, Guillermo

2010-01-01

338

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

PubMed Central

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

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

2013-01-01

339

Electrophysiological characterization of methyleugenol: a novel agonist of GABA(A) receptors.  

PubMed

Methyleugenol (ME) is a natural constituent isolated from many plant essential oils having multiple biological effects including anticonvulsant and anesthetic activities, although the underlying mechanisms remain unclear. Here, we identify ME as a novel agonist of ionotropic ?-aminobutyric acid (GABA) receptors. At lower concentrations (?30 ?M), ME significantly sensitized GABA-induced, but not glutamate- or glycine-induced, currents in cultured hippocampal neurons, indicative of a preferentially modulatory role of this compound for A type GABA receptors (GABAARs). In addition, ME at higher concentrations (?100 ?M) induced a concentration-dependent, Cl(-)-permeable current in hippocampal neurons, which was inhibited by a GABAAR channel blocker, picrotoxin, and a competitive GABAAR antagonist, bicuculline, but not a specific glycine receptor inhibitor, strychnine. Moreover, ME activated a similar current mediated by recombinant ?1-?2-?2 or ?5-?2-?2 GABAARs in human embryonic kidney (HEK) cells. Consequently, ME produced a strong inhibition of synaptically driven neuronal excitation in hippocampal neurons. Together, these results suggest that ME represents a novel agonist of GABAARs, shedding additional light on future development of new therapeutics targeting GABAARs. The present study also adds GABAAR activation to the list of molecular targets of ME that probably account for its biological activities. PMID:24980777

Ding, Jing; Huang, Chen; Peng, Zhong; Xie, Yuxuan; Deng, Shining; Nie, Yan-Zhen; Xu, Tian-Le; Ge, Wei-Hong; Li, Wei-Guang; Li, Fei

2014-09-17

340

Structural Rearrangements in Loop F of the GABA Receptor Signal Ligand Binding, Not Channel Activation  

PubMed Central

Abstract Structure-function studies of the Cys loop family of ionotropic neurotransmitter receptors (GABA, nACh, 5-HT3, and glycine receptors) have resulted in a six-loop (A–F) model of the agonist-binding site. Key amino acids have been identified in these loops that associate with, and stabilize, bound ligand. The next step is to identify the structural rearrangements that couple agonist binding to channel opening. Loop F has been proposed to move upon receptor activation, although it is not known whether this movement is along the conformational pathway for channel opening. We test this hypothesis in the GABA receptor using simultaneous electrophysiology and site-directed fluorescence spectroscopy. The latter method reveals structural rearrangements by reporting changes in hydrophobicity around an environmentally sensitive fluorophore attached to defined positions of loop F. Using a series of ligands that span the range from full activation to full antagonism, we show there is no correlation between the rearrangements in loop F and channel opening. Based on these data and agonist docking simulations into a structural model of the GABA binding site, we propose that loop F is not along the pathway for channel opening, but rather is a component of the structural machinery that locks ligand into the agonist-binding site. PMID:19134470

Khatri, Alpa; Sedelnikova, Anna; Weiss, David S.

2009-01-01

341

Perisynaptic GABA Receptors The Overzealous Protector  

PubMed Central

An attempt to find pharmacological therapies to treat stroke patients and minimize the extent of cell death has seen the failure of dozens of clinical trials. As a result, stroke/cerebral ischemia is the leading cause of lasting adult disability. Stroke-induced cell death occurs due to an excess release of glutamate. As a consequence to this, a compensatory increased release of GABA occurs that results in the subsequent internalization of synaptic GABAA receptors and spillover onto perisynaptic GABAA receptors, resulting in increased tonic inhibition. Recent studies show that the brain can engage in a limited process of neural repair after stroke. Changes in cortical sensory and motor maps and alterations in axonal structure are dependent on patterned neuronal activity. It has been assumed that changes in neuronal excitability underlie processes of neural repair and remapping of cortical sensory and motor representations. Indeed, recent evidence suggests that local inhibitory and excitatory currents are altered after stroke and modulation of these networks to enhance excitability during the repair phase can facilitate functional recovery after stroke. More specifically, dampening tonic GABA inhibition can afford an early and robust improvement in functional recovery after stroke. PMID:22461789

Clarkson, Andrew N.

2012-01-01

342

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

Microsoft Academic Search

The G-protein-coupled receptor (GPCR) activated by the neurotransmitter GABA\\u000ais made up of two subunits, GABA(B1) and GABA(B2). GABA(B1) binds agonists,\\u000awhereas GABA(B2) is required for trafficking GABA(B1) to the cell surface,\\u000aincreasing agonist affinity to GABA(B1), and activating associated G proteins.\\u000aThese subunits each comprise two domains, a Venus flytrap domain (VFT) and a\\u000aheptahelical transmembrane domain (7TM). How

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

2008-01-01

343

Dorsal raphe 5-HT2C receptor and GABA networks regulate anxiety produced by cocaine withdrawal.  

PubMed

The serotonin system is intimately linked to both the mediation of anxiety and long-term effects of cocaine, potentially through interaction of inhibitory 5-HT2C receptor and gamma-aminobutyric acid (GABA) networks. This study characterized the function of the dorsal raphe (DR) 5-HT2C receptor and GABA network in anxiety produced by chronic cocaine withdrawal. C57BL/6 mice were injected with saline or cocaine (15 mg/kg) 3 times daily for 10 days, and tested on the elevated plus maze 30 min, 25 h, or 7 days after the last injection. Cocaine-withdrawn mice showed heightened anxiety-like behavior at 25 h of withdrawal, as compared to saline controls. Anxiety-like behavior was not different when mice were tested 30 min or 7 days after the last cocaine injection. Electrophysiology data revealed that serotonin cells from cocaine-withdrawn mice exhibited increased GABA inhibitory postsynaptic currents (IPSCs) in specific DR subregions dependent on withdrawal time (25 h or 7 d), an effect that was absent in cells from non-withdrawn mice (30 min after the last cocaine injection). Increased IPSC activity was restored to baseline levels following bath application of the 5-HT2C receptor antagonist, SB 242084. In a separate cohort of cocaine-injected mice at 25 h of withdrawal, both global and intra-DR blockade of 5-HT2C receptors prior to elevated plus maze testing attenuated anxiety-like behavior. This study demonstrates that DR 5-HT2C receptor blockade prevents anxiety-like behavior produced by cocaine withdrawal, potentially through attenuation of heightened GABA activity, supporting a role for the 5-HT2C receptor in mediating anxiety produced by cocaine withdrawal. PMID:25656481

Craige, Caryne P; Lewandowski, Stacia; Kirby, Lynn G; Unterwald, Ellen M

2015-06-01

344

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

2011-01-01

345

? GABA(A) subunit-orexin receptor interactions activate learning/motivational pathways in the goldfish.  

PubMed

Orexins (ORXs) cross-talking with ?-aminobutyric acid(A) receptor (GABA(A)R) is beginning to constitute a key neuronal signaling feature responsible for the successful promotion of sleep-wake cycle, feeding and motor behaviors plus reward/motivational activities. In this work, ORX-A and the two ? GABA(A)R agonists (zolpidem, ZOL; diazepam, DZP) accounted for very great (p<0.001) increases of feeding while only DZP elicited great (p<0.01) levels of food intake in the goldfish (Carassius auratus). It was, however, T-maze and conditioned place preference (CPP) methods that allowed us to specifically establish learning/reward-related events operating in an ORX-A+GABA(A)R-dependent fashion in our experimental model. T-maze data showed that conditioned ORX-A treated-fish were capable of reaching the red/blue chamber and ingesting their food reward in a very greatly reduced latency time with respect to untreated conditioned fish while DZP and ZOL greatly and moderately (p<0.05) reduced their latency time, respectively. Regarding CPP study, conditioned ORX-A- and DZP-treated animals showed comparably greater preferences for the conditioned compartment that became even greater in ORX-A+DZP-treated fish. Surprisingly, ORX receptor expression of the telencephalon was preferentially activated by ORX-A treatments while diencephalic/mesencephalic structures and namely the tuberculum posterioris (TPp) were more sensitive to DZP especially following treatment with ORX-A+DZP. Overall, behavioral performances along with ORX receptor transcriptional properties tend to point to ? GABA(A)R agonists as enhancers of palatability while the ORXergic system constitutes a crucial link between satiety-related and cognitive centers through the activation of TPp thus proposing this ascending dopaminergic system as a key target of learning/reward processes in fish. PMID:22814116

Facciolo, Rosa Maria; Crudo, Michele; Zizza, Merylin; Giusi, Giuseppina; Canonaco, Marcello

2012-10-01

346

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

2015-01-01

347

The Subcellular Localization of GABA Transporters and Its Implication for Seizure Management.  

PubMed

The ability to modulate the synaptic GABA levels has been demonstrated by using the clinically effective and selective GAT1 inhibitor tiagabine [(R)-N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]nipecotic acid]. N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]-3-hydroxy-4-(methylamino)-4,5,6,7-tetrahydrobenzo[d]isoxazol-3-ol (EF1502) which not only inhibits GAT1 like tiagabine but also BGT1 has been shown to modulate extrasynaptic GABA levels. The simultaneous inhibition of synaptic and extrasynaptic GABA transporters using tiagabine and EF1502, respectively has been demonstrated to exert a synergistic anticonvulsant effect in several seizure models in mice. The pharmacological profile of these and similar compounds has been thoroughly investigated in in vitro systems, comparing the GAT subtype selectivity with the ability to inhibit GABA uptake in primary cultures of neurons and astrocytes. However, an exact explanation has not yet been found. In the present study, the ability of GATs to form homo and/or heterodimers was investigated as well as to which membrane micro environment the GATs reside. To investigate dimerization of GATs, fusion proteins of GATs tagged with either yellow fluorescent protein or cerulean fluorescent protein were made and fluorescence resonance energy transfer (FRET) was measured. It was found that GATs form both homo- and hetero-dimers in N2A and HEK-293 cells. Microdomain localization of GATs as investigated by detergent resistant membrane fractions after treatment of tissue with Brij-98 or Triton X-100 revealed that BGT1 and GAT1 mostly localize to non-membrane rafts independent of the detergent used. However, GAT3 localizes to membrane rafts when using Brij-98. Taken together, these results suggest that the observed hetero dimerization of GATs in the FRET study is unlikely to have functional implications since the GATs are located to very different cellular compartments and cell types. PMID:25519681

Madsen, Karsten K; Hansen, Gert H; Danielsen, E Michael; Schousboe, Arne

2015-02-01

348

Induction of Arabidopsis tryptophan pathway enzymes and camalexin by amino acid starvation, oxidative stress, and an abiotic elicitor.  

PubMed

The tryptophan (Trp) biosynthetic pathway leads to the production of many secondary metabolites with diverse functions, and its regulation is predicted to respond to the needs for both protein synthesis and secondary metabolism. We have tested the response of the Trp pathway enzymes and three other amino acid biosynthetic enzymes to starvation for aromatic amino acids, branched-chain amino acids, or methionine. The Trp pathway enzymes and cytosolic glutamine synthetase were induced under all of the amino acid starvation test conditions, whereas methionine synthase and acetolactate synthase were not. The mRNAs for two stress-inducible enzymes unrelated to amino acid biosynthesis and accumulation of the indolic phytoalexin camalexin were also induced by amino acid starvation. These results suggest that regulation of the Trp pathway enzymes under amino acid deprivation conditions is largely a stress response to allow for increased biosynthesis of secondary metabolites. Consistent with this hypothesis, treatments with the oxidative stress-inducing herbicide acifluorfen and the abiotic elicitor alpha-amino butyric acid induced responses similar to those induced by the amino acid starvation treatments. The role of salicylic acid in herbicide-mediated Trp and camalexin induction was investigated. PMID:9501110

Zhao, J; Williams, C C; Last, R L

1998-03-01

349

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.

1990-01-01

350

Activation of axonal receptors by GABA spillover increases somatic firing.  

PubMed

Axons can be depolarized by ionotropic receptors and transmit subthreshold depolarizations to the soma by passive electrical spread. This raises the possibility that axons and axonal receptors can participate in integration and firing in neurons. Previously, we have shown that exogenous GABA depolarizes cerebellar granule cell axons through local activation of GABA(A) receptors (GABA(A)Rs) and the soma through electrotonic spread of the axonal potential resulting in increased firing. We show here that excitability of granule cells is also increased by release of endogenous GABA from molecular layer interneurons (MLIs) and spillover activation of parallel fiber GABA(A)Rs in mice and rats. Changes in granule cell excitability were assessed by excitability testing after activation of MLIs with channelrhodopsin or electrical stimulation in the molecular layer. In granule cells lacking an axon, excitability was not changed, suggesting that axonal receptors are required. To determine the distance over which subthreshold potentials may spread, we estimated the effective axonal electrical length constant (520 ?m) by excitability testing and focal uncaging of RuBi-GABA on the axon at varying distances from the soma. These data suggest that GABA(A)R-mediated axonal potentials can participate in integration and firing of cerebellar granule cells. PMID:24155298

Pugh, Jason R; Jahr, Craig E

2013-10-23

351

Corelease of acetylcholine and GABA from cholinergic forebrain neurons  

PubMed Central

Neurotransmitter corelease is emerging as a common theme of central neuromodulatory systems. Though corelease of glutamate or GABA with acetylcholine has been reported within the cholinergic system, the full extent is unknown. To explore synaptic signaling of cholinergic forebrain neurons, we activated choline acetyltransferase expressing neurons using channelrhodopsin while recording post-synaptic currents (PSCs) in layer 1 interneurons. Surprisingly, we observed PSCs mediated by GABAA receptors in addition to nicotinic acetylcholine receptors. Based on PSC latency and pharmacological sensitivity, our results suggest monosynaptic release of both GABA and ACh. Anatomical analysis showed that forebrain cholinergic neurons express the GABA synthetic enzyme Gad2 and the vesicular GABA transporter (Slc32a1). We confirmed the direct release of GABA by knocking out Slc32a1 from cholinergic neurons. Our results identify GABA as an overlooked fast neurotransmitter utilized throughout the forebrain cholinergic system. GABA/ACh corelease may have major implications for modulation of cortical function by cholinergic neurons. DOI: http://dx.doi.org/10.7554/eLife.06412.001 PMID:25723967

Saunders, Arpiar; Granger, Adam J; Sabatini, Bernardo L

2015-01-01

352

Design and Mechanism of Tetrahydrothiophene-Based ?-Aminobutyric Acid Aminotransferase Inactivators.  

PubMed

Low levels of ?-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinson's disease, Alzheimer's disease, Huntington's disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the blood-brain barrier and inhibit the activity of ?-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally restricted tetrahydrothiophene-based GABA analogues with a properly positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is 8 times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bonding interactions with Arg-192, a ?-? interaction with Phe-189, and a weak nonbonded S···O?C interaction with Glu-270, thereby inactivating the enzyme. PMID:25781189

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

2015-04-01

353

Design, synthesis and pharmacological evaluation of alpha-substituted N-benzylamides of gamma-hydroxybutyric acid with potential GABA-ergic activity. Part 6. Search for new anticonvulsant compounds.  

PubMed

In the recent study we have extended our investigations to the new anticonvulsant derivatives of alpha-substituted N-benzylamides of gamma-hydroxybutyric acid (GHB). Among the obtained compounds N-benzylamide of alpha-(1,2,3,4-tetrahydroisoquinoline)-GHB (9) has demonstrated activity against maximal electroshock (MES) induced seizures in mice (at 100 mg/kg ip) and in rats (at 30 mg/kg, po dose). Lactone 8 and amide 9 have possessed a weak effect on [3H]-muscimol binding. Molecular modeling studies have revealed that anticonvulsant activity of the alpha-substituted amides of GHB might partially be explained by the orientation of the terminal benzylamide fragment. PMID:17665862

Malawska, Barbara; Kulig, Katarzyna; Gajda, Justyna; Szczeblewski, Dominik; Musia?, Anna; Wieckowski, Krzysztof; Maciag, Dorota; Stables, James P

2007-01-01

354

Inhibitory Action of Antidepressants on Mouse Betaine/GABA Transporter (BGT1) Heterologously Expressed in Cell Cultures  

PubMed Central

Betaine/?-aminobutyric acid (GABA) transporter (BGT1, SLC6A12) is a member of the Na+- and Cl?-dependent neurotransmitter transporter gene family with a homology to the GABA transporters (GATs), GAT1 (SLC6A1), GAT2 (SLC6A13) and GAT3 (SLC6A11) (HUGO nomenclature). Since antidepressants have been reported to inhibit GABA uptake, we examined those effects on mouse BGT1 (mBGT1) in comparison with other mouse GAT (mGAT) subtypes in the heterologously expressed cell cultures. All antidepressants tested here inhibited the [3H]GABA uptake through mBGT1 and mGATs in a rank order of potency with mBGT1 > mGAT1-3. Kinetic analyses for maprotilline, mianserine and trimipramine revealed that they inhibited mBGT1 and mGAT1 noncompetitively, except that mianserine competitively inhibited mBGT1. These results provided a clue to investigate the structure-function relationship of mBGT1 using antidepressants as a tool, leading to the identification of potential candidates for selective and specific inhibitors of mBGT1. PMID:22489112

Gerile; Sogawa, Chiharu; Ohyama, Kazumi; Masuko, Takashi; Kusama, Tadashi; Morita, Katsuya; Sogawa, Norio; Kitayama, Shigeo

2012-01-01

355

Optoactivation of parvalbumin neurons in the spinal dorsal horn evokes GABA release that is regulated by presynaptic GABAB receptors.  

PubMed

Among heterogeneous neural cells in the spinal dorsal horn, parvalbumin (PV)-positive neurons are one subtype of GABA (?-aminobutyric acid)-containing interneurons. Using an optogenetic approach, we expressed blue light-sensitive cation channel channelrhodopsin-2 (ChR2) via a viral vector on PV neurons in the spinal dorsal horn. Combined with in vitro whole-cell recordings, we activated ChR2 expressed on PV neurons by blue light and recorded GABAA receptor-mediated light-evoked inhibitory postsynaptic currents (L-IPSCs). The L-IPSCs were action potential-dependent and abolished by the GABAA receptor antagonist picrotoxin, indicating a synchronic GABA release from presynaptic terminals. Activation of GABAB receptors (the metabotropic receptors of GABA) on presynaptic terminals by a putative agonist, baclofen, depressed the amplitude of L-IPSCs. This depression was largely occluded by pretreatment with the highly selective Cav2.1 (P/Q-type) Ca(2+) channel blocker ?-agatoxin IVA. N-type Ca(2+) channel blocker ?-conotoxin GVIA showed less effects on either L-IPSCs or baclofen depression. We conclude that optoactivation of PV-ChR2 neurons in the spinal dorsal horn induces GABA release from presynaptic terminals, which is modulated by presynaptic GABAB receptors that are coupled to P/Q-type Ca(2+) channels. Importantly, our studies provide a simple and reliable optogenetic approach to study dorsal horn neural circuits. PMID:25817363

Yang, Kun; Ma, Rui; Wang, Qian; Jiang, Ping; Li, Yun-Qing

2015-05-01

356

Prefrontal GABA concentration changes in women-Influence of menstrual cycle phase, hormonal contraceptive use, and correlation with premenstrual symptoms.  

PubMed

Prefrontal regions are involved in processing emotional stimuli and are a topic of interest in clinical and neurological research. Although sex steroids are potent neuromodulators, the influence of menstrual cycle phase and hormonal contraceptive use is rarely taken into account in neuroimaging studies. Our purpose was to evaluate changes in gamma-aminobutyric acid (GABA) in women, as measured by magnetic resonance spectroscopy (MRS), with phases of the menstrual cycle and use of hormonal contraceptives, and to assess correlations with premenstrual symptoms.Three MRI sessions per cycle were obtained in the natural cycle group, and two sessions in the hormonal contraceptives group. In addition to an anatomical scan, single voxel MRS in the prefrontal area was performed. After quality control, 10 women with natural cycle and 21 women taking hormonal contraceptives were included for analysis. Peripheral blood samples were obtained to determine endogenous hormone concentrations. Subjects were asked to complete a daily rating of severity of problems questionnaire, to quantify premenstrual symptoms. In the natural cycle group, we found a significant increase in prefrontal GABA concentration at the time of ovulation. Conversely, in the hormonal contraceptives group, no differences were found between the pill phase and pill-free phase. GABA concentrations did not significantly correlate with endogenous hormone levels, nor with premenstrual symptoms. Our results indicate that spectroscopically measured GABA concentrations are higher during ovulation in women with a natural menstrual cycle. We suggest that neuroimaging studies should take into account this variability. PMID:25481417

De Bondt, Timo; De Belder, Frank; Vanhevel, Floris; Jacquemyn, Yves; Parizel, Paul M

2015-02-01

357

Stress metabolism in green coffee beans (Coffea arabica L.): expression of dehydrins and accumulation of GABA during drying.  

PubMed

In order to produce tradeable standard green coffee, processed beans must be dried. The drying procedure affects the abundance of relevant aroma substances, e.g. carbohydrates. Using molecular tools, the corresponding metabolic basis is analyzed. A decrease in water potential of the still living coffee seeds induces massive drought stress responses. As a marker for these stress reactions, accumulation of a general stress metabolite, GABA (gamma-aminobutyric acid), and associated gene expression of drought stress-associated dehydrins were monitored. The results of this study indicate that metabolism in drying coffee beans is quite complex since several events trigger accumulation of GABA. The first peak of GABA accumulation during drying is correlated with expression of isocitrate lyase and thus with ongoing germination processes in coffee seeds. Two subsequent peaks of GABA accumulation correspond to maxima of dehydrin gene expression and are thought to be induced directly by drought stress in the embryo and endosperm tissue, respectively. Apart from the significance for understanding basic seed physiology, metabolic changes in coffee seeds during processing provide valuable information for understanding the role and effect of the steps of green coffee processing on the quality of the resulting coffee. PMID:20208063

Kramer, Daniela; Breitenstein, Björn; Kleinwächter, Maik; Selmar, Dirk

2010-04-01

358

gamma-Hydroxybutyrate conversion into GABA induces displacement of GABAB binding that is blocked by valproate and ethosuximide.  

PubMed

gamma-Hydroxybutyrate (GHB) has been reported to be a ligand for GABAB receptor(s), although with low or very low affinity (IC50 = 150-796 microM). In addition, several reports argue for a role of GHB via GABAB receptors in both in vivo and in vitro electro-physiological experiments. In the present study, we demonstrate that the inhibition of GHB's conversion into GABA by rat brain membranes blocks the ability of GHB to interfere with GABAB binding. In particular, the inhibition of GHB dehydrogenase by valproate or ethosuximide and the blockade of GABA-T by aminooxyacetic acid induce the disappearance of the GABA-like effect of GHB at GABAB, but also at GABAA, receptors. This finding could explain the misinterpretation of in vitro or in vivo experiments where GHB possesses a GABA-like effect. But in addition, it is postulated that the normal metabolism of GHB in brain induces GABAB mechanisms that could be blocked by the administration of valproate or ethosuximide. PMID:9152382

Hechler, V; Ratomponirina, C; Maitre, M

1997-05-01

359

Functional properties of GABA synaptic inputs onto GABA neurons in monkey prefrontal cortex.  

PubMed

In rodent cortex GABAA receptor (GABAAR)-mediated synapses are a significant source of input onto GABA neurons, and the properties of these inputs vary among GABA neuron subtypes that differ in molecular markers and firing patterns. Some features of cortical interneurons are different between rodents and primates, but it is not known whether inhibition of GABA neurons is prominent in the primate cortex and, if so, whether these inputs show heterogeneity across GABA neuron subtypes. We thus studied GABAAR-mediated miniature synaptic events in GABAergic interneurons in layer 3 of monkey dorsolateral prefrontal cortex (DLPFC). Interneurons were identified on the basis of their firing pattern as fast spiking (FS), regular spiking (RS), burst spiking (BS), or irregular spiking (IS). Miniature synaptic events were common in all of the recorded interneurons, and the frequency of these events was highest in FS neurons. The amplitude and kinetics of miniature inhibitory postsynaptic potentials (mIPSPs) also differed between DLPFC interneuron subtypes in a manner correlated with their input resistance and membrane time constant. FS neurons had the fastest mIPSP decay times and the strongest effects of the GABAAR modulator zolpidem, suggesting that the distinctive properties of inhibitory synaptic inputs onto FS cells are in part conferred by GABAARs containing ?1 subunits. Moreover, mIPSCs differed between FS and RS interneurons in a manner consistent with the mIPSP findings. These results show that in the monkey DLPFC GABAAR-mediated synaptic inputs are prominent in layer 3 interneurons and may differentially regulate the activity of different interneuron subtypes. PMID:25540225

Rotaru, Diana C; Olezene, Cameron; Miyamae, Takeaki; Povysheva, Nadezhda V; Zaitsev, Aleksey V; Lewis, David A; Gonzalez-Burgos, Guillermo

2015-03-15

360

gamma-Aminobutyric acid-mediated regulation of the activity-dependent olfactory bulb dopaminergic phenotype.  

PubMed

gamma-Aminobutyric acid (GABA) regulates the proliferation and migration of olfactory bulb (OB) interneuron progenitors derived from the subventricular zone (SVZ), but the role of GABA in the differentiation of these progenitors has been largely unexplored. This study examines the role of GABA in the differentiation of OB dopaminergic interneurons using neonatal forebrain organotypic slice cultures prepared from transgenic mice expressing green fluorescent protein (GFP) under the control of the tyrosine hydroxylase (Th) gene promoter (ThGFP). KCl-mediated depolarization of the slices induced ThGFP expression. The addition of GABA to the depolarized slices further increased GFP fluorescence by inducing ThGFP expression in an additional set of periglomerular cells. These findings show that GABA promoted differentiation of SVZ-derived OB dopaminergic interneurons and suggest that GABA indirectly regulated Th expression and OB dopaminergic neuron differentiation through an acceleration of the maturation rate for the dopaminergic progenitors. Additional studies revealed that the effect of GABA on ThGFP expression required activation of L- and P/Q-type Ca2+ channels as well as GABA(A) and GABA(B) receptors. These voltage-gated Ca2+ channels and GABA receptors have previously been shown to be required for the coexpressed GABAergic phenotype in the OB interneurons. Together, these findings suggest that Th expression and the differentiation of OB dopaminergic interneurons are coupled to the coexpressed GABAergic phenotype and demonstrate a novel role for GABA in neurogenesis. PMID:19301430

Akiba, Yosuke; Sasaki, Hayato; Huerta, Patricio T; Estevez, Alvaro G; Baker, Harriet; Cave, John W

2009-08-01

361

Selective GABA-receptor actions of amobarbital on thalamic neurons  

PubMed Central

We studied amobarbital's effects on membrane properties and currents, and electrically evoked inhibitory postsynaptic currents (IPSCs) mediated by ?-aminobutyric acid (GABA) in rat thalamic slices. Using concentration–response relationships, we compared amobarbital's effects in nociceptive nuclei and non-nociceptive nucleus reticularis thalami (nRT). Amobarbital decreased input resistance by activating GABAA receptors. Amobarbital produced a larger decrease in ventrobasal than nRT neurons. Amobarbital depressed burst and tonic firing. Depression of burst firing was more effective, particularly in ventrobasal and intralaminar neurons. Depression was reversed by GABAA antagonists, and surmountable by increasing current injection, implicating a receptor-mediated shunt mechanism. Amobarbital did not affect the tetrodotoxin-isolated low threshold Ca2+ spike during GABAA blockade. Amobarbital reduced excitability without altering outward leak, or hyperpolarisation-activated inward currents. Amobarbital increased mean conductance and burst duration of single GABAA channels. Consistent with this, amobarbital increased amplitude and decay time of IPSCs with distinct EC50s, implicating actions at two GABAA receptor sites. Activation of GABAA receptors by low concentrations, fast IPSC amplitude modulation, and failure to affect intrinsic currents distinguished amobarbital's mechanism of action from previously characterised barbiturates. The selective actions of amobarbital on GABAA receptor may have relevance in explaining anaesthetic and analgesic uses. PMID:15381635

Kim, H-S; Wan, X; Mathers, D A; Puil, E

2004-01-01

362

Centrally-mediated antinociceptive actions of GABA(A) receptor agonists in the rat spared nerve injury model of neuropathic pain.  

PubMed

Gamma aminobutyric acid (GABA) plays a major role in the central hyperexcitabilty associated with nerve damage. The precise antinociceptive actions mediated by GABA(A) receptor agonists remain unclear as previous studies have shown mixed results in neuropathic pain models. Thus, various drugs which modulate GABA(A) receptor function were tested in the rat spared nerve injury (SNI) model of neuropathic pain. The selective GABA(A) receptor agonist gaboxadol dose-dependently (6 and 15 mg/kg, s.c.) reversed hindpaw mechanical allodynia and hyperalgesia for at least 150 min after administration. The GABA(A) receptor agonist muscimol (0.02-2 mg/kg, s.c.) also dose-dependently reversed mechanical allodynia, although the maximal effect achieved was less than that observed for gaboxadol. Mechanical hyperalgesia was attenuated only by the highest dose of muscimol. In contrast, the selective GABA(A) receptor agonist isoguvacine (20 mg/kg, s.c.) which has poor central nervous system penetration, and the benzodiazepine-site ligand zolpidem (20 mg/kg, s.c.) were ineffective against either nociceptive behaviour. In the rotarod test, both gaboxadol (15 mg/kg) and zolpidem impaired motor function for at least 60 min after injection; muscimol (2 mg/kg) and gaboxadol (6 mg/kg) were ineffective. Importantly, the ataxic effects induced by gaboxadol resolved 1-2 h after administration, a time point where clear antiallodynic and antihyperalgesic actions still occurred. Thus, systemic administration of blood-brain penetratable selective GABA(A) receptor agonists attenuate nociceptive behaviours in the SNI rat model of neuropathic pain that can be considered to occur independently of other effects on motor function. PMID:15936014

Rode, Frederik; Jensen, Dorthe G; Blackburn-Munro, Gordon; Bjerrum, Ole J

2005-06-01

363

GABA(B) receptors: from monogamy to promiscuity.  

PubMed

The aim of this review is firstly to describe the current understanding of the diverse physiology and pharmacology of GABA(B) receptors in vivo. We will then focus on recent advances made, since the identification of the GABA(B) receptor subunit genes, in our knowledge of the molecular nature of the receptor, and the recently discovered molecular determinants of functions such as ligand binding, trafficking and signalling. We will conclude with a summary of the GABA(B) receptor-interacting proteins that have been described thus far, and discuss how these may, at least in part, account for the paradox of varied receptor pharmacology in the potential context of a single heterodimeric GABA(B) receptor. PMID:12566919

Calver, A R; Davies, C H; Pangalos, M

2002-01-01

364

gamma-Hydroxybutyrate (GHB) induces GABA(B) receptor independent intracellular Ca2+ transients in astrocytes, but has no effect on GHB or GABA(B) receptors of medium spiny neurons in the nucleus accumbens.  

PubMed

We report on cellular actions of the illicit recreational drug gamma-hydroxybutyrate (GHB) in the brain reward area nucleus accumbens. First, we compared the effects of GHB and the GABA(B) receptor agonist baclofen. Neither of them affected the membrane currents of medium spiny neurons in rat nucleus accumbens slices. GABAergic and glutamatergic synaptic potentials of medium spiny neurons, however, were reduced by baclofen but not GHB. These results indicate the lack of GHB as well as postsynaptic GABA(B) receptors, and the presence of GHB insensitive presynaptic GABA(B) receptors in medium spiny neurons. In astrocytes GHB induced intracellular Ca(2+) transients, preserved in slices from GABA(B) receptor type 1 subunit knockout mice. The effects of tetrodotoxin, zero added Ca(2+) with/without intracellular Ca(2+) store depletor cyclopiazonic acid or vacuolar H-ATPase inhibitor bafilomycin A1 indicate that GHB-evoked Ca(2+) transients depend on external Ca(2+) and intracellular Ca(2+) stores, but not on vesicular transmitter release. GHB-induced astrocytic Ca(2+) transients were not affected by the GHB receptor-specific antagonist NCS-382, suggesting the presence of a novel NCS-382-insensitive target for GHB in astrocytes. The activation of astrocytes by GHB implies their involvement in physiological actions of GHB. Our findings disclose a novel profile of GHB action in the nucleus accumbens. Here, unlike in other brain areas, GHB does not act on GABA(B) receptors, but activates an NCS-382 insensitive GHB-specific target in a subpopulation of astrocytes. The lack of either post- or presynaptic effects on medium spiny neurons in the nucleus accumbens distinguishes GHB from many drugs and natural rewards with addictive properties and might explain why GHB has only a weak reinforcing capacity. PMID:19446011

Molnár, T; Antal, K; Nyitrai, G; Emri, Z

2009-08-18

365

Effects of GABA agonists on Herxheimer microshock in guinea pigs.  

PubMed

In this paper we describe the first observation of GABA inhibition in an experimental model of asthma in vivo. Guinea-pigs were actively sensitized with ovalbumin i.p. and 20 days later the Herxheimer microshock was performed. GABA and (-)-baclofen injected 20 min previously significantly prevented the development of microshock. Therefore GABAergic drugs appear to modulate in vivo anaphylactic reaction. The value of this observation with regard to the physiopathology and therapy of asthma remains to be elucidated. PMID:3014844

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

1986-04-01

366

Active Dendritic Conductances Dynamically Regulate GABA Release from Thalamic Interneurons  

Microsoft Academic Search

SUMMARY Inhibitory interneurons in thedorsal lateralgeniculate nucleus (dLGN) process visual information by pre- cisely controlling spike timing and by refining the re- ceptive fields of thalamocortical (TC) neurons. Previ- ous studies indicate that dLGN interneurons inhibit TC neurons by releasing GABA from both axons and dendrites. However, the mechanisms controlling GABA release are poorly understood. Here, using si- multaneous whole-cell

Claudio Acuna-Goycolea; Stephan D. Brenowitz; Wade G. Regehr

2008-01-01

367

Ethers of 3-hydroxyphenylacetic acid as selective gamma-hydroxybutyric acid receptor ligands.  

PubMed

Gamma-hydroxybutyric acid (GHB) is a drug of abuse, a therapeutic, and purportedly a neurotransmitter with a complex mechanism of action in vivo due to direct actions at GABA(B) as well as GHB receptors and because of its metabolism to GABA. Herein, we describe 3-ethers of 3-hydroxyphenylacetic acid, which have relatively high affinity at GHB sites, no significant affinity at GABA receptors, and would not be expected to be rapidly metabolized to GABAergic ligands. The selectivity of these compounds (UMB108, UMB109, and UMB119) could prove to be useful for studying the biology of GHB receptors, free from GABAergic effects. PMID:15927467

Chen, Weibin; Wu, Huifang; Hernandez, R Jason; Mehta, Ashok K; Ticku, Maharaj K; France, Charles P; Coop, Andrew

2005-07-01

368

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.

2013-01-01

369

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.

2015-01-01

370

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

2014-01-01

371

Accuracy and stability of measuring GABA, glutamate, and glutamine by proton magnetic resonance spectroscopy: A phantom study at 4 Tesla  

NASA Astrophysics Data System (ADS)

Proton magnetic resonance spectroscopy has the potential to provide valuable information about alterations in gamma-aminobutyric acid (GABA), glutamate (Glu), and glutamine (Gln) in psychiatric and neurological disorders. In order to use this technique effectively, it is important to establish the accuracy and reproducibility of the methodology. In this study, phantoms with known metabolite concentrations were used to compare the accuracy of 2D J-resolved MRS, single-echo 30 ms PRESS, and GABA-edited MEGA-PRESS for measuring all three aforementioned neurochemicals simultaneously. The phantoms included metabolite concentrations above and below the physiological range and scans were performed at baseline, 1 week, and 1 month time-points. For GABA measurement, MEGA-PRESS proved optimal with a measured-to-target correlation of R2 = 0.999, with J-resolved providing R2 = 0.973 for GABA. All three methods proved effective in measuring Glu with R2 = 0.987 (30 ms PRESS), R2 = 0.996 (J-resolved) and R2 = 0.910 (MEGA-PRESS). J-resolved and MEGA-PRESS yielded good results for Gln measures with respective R2 = 0.855 (J-resolved) and R2 = 0.815 (MEGA-PRESS). The 30 ms PRESS method proved ineffective in measuring GABA and Gln. When measurement stability at in vivo concentration was assessed as a function of varying spectral quality, J-resolved proved the most stable and immune to signal-to-noise and linewidth fluctuation compared to MEGA-PRESS and 30 ms PRESS.

Henry, Michael E.; Lauriat, Tara L.; Shanahan, Meghan; Renshaw, Perry F.; Jensen, J. Eric

2011-02-01

372

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

2012-01-01

373

Suppression of Progesterone-enhanced Hyperactivation in Hamster Spermatozoa by ?-aminobutyric Acid  

PubMed Central

It has been recently shown that mammalian spermatozoa were hyperactivated by steroids, amines and amino acids. In the present study, we investigated whether hyperactivation of hamster sperm is regulated by progesterone (P) and ?-aminobutyric acid (GABA). Although sperm hyperactivation was enhanced by P, GABA significantly suppressed P-enhanced hyperactivation in a dose-dependent manner. Suppression of P-enhanced hyperactivation by GABA was significantly inhibited by an antagonist of the GABAA receptor (bicuculline). Moreover, P bound to the sperm head, and this binding was decreased by GABA. Because the concentrations of GABA and P change in association with the estrous cycle, these results suggest that GABA and P competitively regulate the enhancement of hyperactivation through the GABAA receptor. PMID:24614320

KON, Hiroe; TAKEI, Gen L.; FUJINOKI, Masakatsu; SHINODA, Motoo

2014-01-01

374

Assessment of regional GABA(A) receptor binding using 18F-fluoroflumazenil positron emission tomography in spastic type cerebral palsy.  

PubMed

Periventricular leukomalacia (PVL) due to hypoxic-ischemic insult to the immature brain, chorioamnionitis and maternal infection are the major etiological factors of spastic type cerebral palsy (CP). Despite advances in preventing and treating certain causes of CP, the number of patients has remained essentially unchanged and the pathophysiological mechanisms related to motor dysfunction remain poorly understood. In this study, statistical parametric mapping (SPM) analysis of cerebral gamma-aminobutyric acid (GABA) receptor PET imaging using [18F]-fluoroflumazenil showed increased GABA(A) receptor binding in the bilateral motor and visual cortices in spastic diplegia (SD) type CP patients (n = 20) compared with normal controls (n = 10). As GABA(A) receptor signaling modulates biological perception and production of movement, complex motor skills and use-dependent plasticity in the motor cortex, increased GABA(A) receptor binding in the motor cortex might play a important role in poor motor control. Decreased GABA(A) receptor binding was seen in the brain stem in SD CP patients, which appears to be related to spastic symptom. PMID:17049274

Lee, Jong Doo; Park, Hae-Jeong; Park, Eun Sook; Kim, Dong Goo; Rha, Dong-Wook; Kim, Eung Yeop; Kim, Dong Ik; Kim, Jae-Jin; Yun, Mijin; Ryu, Young Hoon; Lee, Jinu; Jeong, Jae Min; Lee, Dong Soo; Lee, Myung Chul; Park, Chang Il

2007-01-01

375

Effects of thyroxine and its related compounds on cerebral GABA receptors: inhibitory action on benzodiazepine recognition site in GABAA receptor complex.  

PubMed

The effects of thyroxine and its related derivatives on gamma-aminobutyric acid (GABA) receptors in the rat brain were examined. D-Thyroxine strongly inhibited [3H]flunitrazepam binding to benzodiazepine receptor in crude synaptic membrane from the rat brain. The Scatchard analysis of the [3H]flunitrazepam binding in the presence of D-thyroxine indicated the decreases in the affinity and maximum number of binding site. Furthermore, D-thyroxine inhibited the enhancing effect of flunitrazepam on GABA-stimulated 36Cl- influx into membrane vesicles, although GABA-stimulated 36Cl- influx alone was not affected by D-thyroxine. On the other hand, the effects of thyroxine and its related derivatives on cerebral GABAB receptor binding were not noted. These results suggest that D-thyroxine may be a drug which is able to modulate the function of GABAA receptor complex via the inhibitory action on benzodiazepine recognition site. PMID:7849573

Narihara, R; Hirouchi, M; Ichida, T; Kuriyama, K; Roberts, E

1994-11-01

376

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

PubMed

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

2010-10-20

377

Studies on screening of higher ?-aminobutyric acid-producing Monascus and optimization of fermentative parameters  

Microsoft Academic Search

?-Aminobutyric acid (GABA), a hypotensive agent, can be produced by Monascus spp. Two hundred and fifteen GABA-producing Monascus strains were isolated from fermented bean curd and red-mold rice. The strain M6 with the highest production level of GABA\\u000a (3.657 g\\/L) was isolated from fermented bean curd by using PDB with 0.5% monosodium glutamate (MSG) and identified as Monascus ruber based on

Donghua JiangHao; Hao ji; Yan Ye; Jiaheng Hou

2011-01-01

378

Occurrence of ?-aminobutyric acid-transaminase activity in nerve fibers of human thymus  

Microsoft Academic Search

The specific localization of ?-aminobutyric acid-transaminase (GABA-t) in the thymus of young and elderly men was studied. Our results show a specific vascular localization of GABA-t in the human thymus, and deal with the amount and distribution of GABA-t and its changes with age. Samples of human thymus were harvested throughout of 12 autopsies in infants (n = 3), as

Daniela Cavallotti; Marco Artico; Stefano De Santis; Carlo Cavallotti

1999-01-01

379

GABA? subunits confer a bicuculline-insensitive component to GFAP+ cells of cerebellum.  

PubMed

GABA-A receptors mediating synaptic or extrasynaptic transmission are molecularly and functionally distinct, and glial cells are known to express a plethora of GABA-A subunits. Here we demonstrate that GFAP(+) cells of the granular layer of cerebellum express GABA? subunits during early postnatal development, thereby conferring peculiar pharmacologic characteristics to GABA responses. Electron microscopy revealed the presence of GABA? in the plasma membrane of GFAP(+) cells. In contrast, expression in the adult was restricted to Purkinje neurons and a subset of ependymal cells. Electrophysiological studies in vitro revealed that astrocytes express functional receptors with an EC50 of 52.2 ± 11.8 ?M for GABA. The evoked currents were inhibited by bicuculline (100 ?M) and TPMPA (IC50, 5.9 ± 0.6 ?M), indicating the presence of a GABA? component. Coimmunoprecipitation demonstrated protein-protein interactions between GABA?1 and GABA?1, and double immunofluorescence showed that these subunits colocalize in the plasma membrane. Three populations of GABA-A receptors in astrocytes were identified: classic GABA-A, bicuculline-insensitive GABA?, and GABA-A-GABA? hybrids. Clusters of GABA-A receptors were distributed in the perinuclear space and along the processes of GFAP(+) cells. Time-lapse microscopy showed GABA?2-GFP accumulation in clusters located in the soma and along the processes. The clusters were relatively immobile, with mean displacement of 9.4 ± 0.9 ?m and a net distance traveled of 1-2 ?m, owing mainly to directional movement or simple diffusion. Modulation of GABA? dynamics may be a novel mechanism of extrasynaptic transmission regulating GABAergic control of GFAP(+) cells during early postnatal development. PMID:25422464

Pétriz, Adriana; Reyes-Haro, Daniel; González-González, María Alejandra; Miledi, Ricardo; Martínez-Torres, Ataúlfo

2014-12-01

380

The Synthesis of [gamma]-Aminobutyric Acid in Response to Treatments Reducing Cytosolic pH.  

PubMed Central

[gamma]-Aminobutyric acid (GABA) synthesis (L-glutamic acid + H+ -> GABA + CO2) is rapidly stimulated by a variety of stress conditions including hypoxia. Recent literature suggests that GABA production and concomitant H+ consumption ameliorates the cytosolic acidification associated with hypoxia or other stresses. This proposal was investigated using isolated asparagus (Asparagus sprengeri Regel) mesophyll cells. Cell acidification was promoted using hypoxia, H+/L-glutamic acid symport, and addition of butyrate or other permeant weak acids. Sixty minutes of all three treatments stimulated the levels of both intracellular and extracellular GABA by values ranging from 100 to 1800%. At an external pH of 5.0, addition of 5 mM butyrate stimulated an increase in overall GABA level from 3.86 (0.56 [plus or minus] SE) to 20.4 (2.16 [plus or minus] SE) nmol of GABA/106 cell. Butyrate stimulated GABA levels by 200 to 300% within 15 s, and extracellular GABA was observed after 10 min. The acid load due to butyrate addition was assayed by measuring [14C]butyrate uptake. After 45 s of butyrate treatment, H+-consuming GABA production accounted for 45% of the imposed acid load. The cytosolic location of a fluorescent pH probe was confirmed using fluorescent microscopy. Spectrofluorimetry indicated that butyrate addition reduced cytosolic pH by 0.60 units with a half-time of approximately 2 s. The proposal that GABA synthesis ameliorates cytosolic acidification is supported by the data. The possible roles of H+ and Ca2+ in stimulating GABA synthesis are discussed. PMID:12232132

Crawford, L. A.; Bown, A. W.; Breitkreuz, K. E.; Guinel, F. C.

1994-01-01