Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P80404 (GABA transaminase)
 786 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Characteristics of 3H-GABA binding to rat brain synaptic membranes in vitro have been investigated. The specific binding of 3H-GABA displays saturation kinetics. Only one single population of receptor sites was found (Km = 31.3 nM) with a concentration of 2.09 pmol/mg protein. Only GABA agonists show inhibitory effect on the binding, whereas GABA antagonists, GABA-uptake inhibitors, and inhibitors of GAD and GABA-T are without effect. The order of potencies for GABA agonists are: Muscimol greater than GABA greater than or equal to 4,5-dihydromuscimol greater than 3-aminoproprane sulphonic acid greater than isoguvacine greater than THIP greater than 3-hydroxy-GABA greater than imidazol-4-acetic acid. Agonists and antagonists from other neurone systems as well as neuroleptics and benzodiazepines had no or only a very slight potency in the binding test.
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PMID:Characterization of 3H-GABA receptor binding to rat brain synaptosomal membranes: effect of non GABAergic compounds. 22 5

Effects of drugs which enhance or reduce GABAergic neurotransmission upon conflict behavior were evaluated with a modified Vogel procedure which was shown to be insensitive to variations in motivation to drink and to the analgesic effects of morphine. In addition, the effects of these drugs on ambulatory activity and motor execution were quantified. For comparison, the benzodiazepines diazepam and chlordiazepoxide were used. Anticonflict actions of diazepam were obtained with a shock current of 0.25 mA but not with 0.05 or 0.5 mA, whereas the proconflict effect of FG7142 was obtained with 0.05 mA but not with higher currents. Diazepam and chlordiazepoxide had anxiolytic effect in a dose similar to that required to reduce ambulatory activity, but below that needed to affect motor execution. At doses high enough to impair motor execution, anticonflict effects were considerable. The GABA-A receptor agonist THIP and the GABA-B receptor agonist baclofen lacked effect on conflict behavior in moderate doses, which reduced ambulatory activity. In doses which produced motor deficiencies these drugs reduced licking both in the conflict test and when tested without shock administration. The effects of the GABA transaminase inhibitors gamma-acetylene GABA and sodium valproate were similar to those of the receptor agonists. The GABA reuptake inhibitor SKF 100330A produced anticonflict effect in a dose below that needed to reduce ambulatory activity, but lacked effect on conflict behavior in higher doses. The GABA antagonist picrotoxin, and the GABA synthesis inhibitors 4-deoxypyridoxine and isoniazide, reduced licking both in the absence and presence of shock, and affected motor functions in the same doses. Bicuculline, at the doses used, had no behavioral effects.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:GABAergic drugs and conflict behavior in the rat: lack of similarities with the actions of benzodiazepines. 166 Jan 3

Benzodiazepine (BZD) anxiolytics, through their activation of the BZD-GABA receptor complex, display robust anxiolytic-like effects following systemic administration in both conditioned and non-conditioned behavioral procedures. The present results show that the GABAA agonists muscimol (0.5-1.0 mg/kg), THIP (2.5-10.0 mg/kg), and isoguvacine (25.0 mg/kg) as well as the GABA transaminase (GABA-T) inhibitor AOAA (aminooxyacetic acid; 5.0-20.0 mg/kg) following intraperitoneal administration exert anxiolytic-like activity of similar magnitude to that of diazepam in two non-conditioned procedures, namely the social interaction and the elevated plus maze tests. We have also extended our original findings that the anti-epileptic drug sodium valproate exerts an anxiolytic-like effect in the Geller conflict paradigm, to show this agent's robust activity in the social interaction and elevated plus maze tests following systemic administration (100-400 mg/kg). These results show that GABAergic agents that facilitate GABA transmission are effective following systemic administration in non-conditioned anxiety procedures and may indicate potential therapeutic efficacy in certain anxiety states.
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PMID:GABAmimetic agents display anxiolytic-like effects in the social interaction and elevated plus maze procedures. 168 57

The main objective of this work was to study the role of the GABAergic system on the convulsions elicited by the organochlorine insecticide lindane. The concentration of lindane in rat brain at the onset of the first tonic convulsion was taken as the endpoint for the neurotoxic action of the insecticide administered by intravenous infusion. Pretreatment with the GABA agonists muscimol and progabide, the GABA uptake blocker SK&F 89976-A, the GABA transaminase inhibitor gamma-acetylenic GABA, and the GABA indirect agonist phenobarbital significantly increased the threshold concentration of lindane in brain required to induce convulsions. The GABA agonist THIP, the GABA competitive antagonist bicuculline, and the prodrug cetyl-GABA had no effect on the brain level of lindane required to induce seizures. The noncompetitive GABA antagonists, picrotoxinin and pentylenetetrazol, significantly decreased the brain concentration of lindane needed to elicit convulsions. The concentration of GABA in the brain of lindane-treated rats was only modified by the significant increase produced after gamma-acetylenic GABA pretreatment. These results show that the convulsions elicited by lindane can be facilitated by some GABA antagonists and antagonized by GABA mimetics, especially those that enhance GABA functionality. The present data are consistent with the proposed in vitro competition of lindane for the picrotoxinin binding site associated with the Cl- ionophore of the GABAA receptor, and suggest that lindane may also interact in vivo with this site.
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PMID:GABAergic modulation of lindane (gamma-hexachlorocyclohexane)-induced seizures. 247 71

Agents modifying GABAergic neurotransmission were administered to ovariectomized rats treated with different doses of estradiol benzoate (EB) + progesterone (P) or with EB alone. Hormone treatments were designed to induce an intermediate level of receptivity in order to be able to observe both stimulatory and inhibitory effects on lordosis behavior. Both the GABAA receptor agonist THIP and the GABAB receptor agonist baclofen inhibited lordosis behavior at doses from 20 and 5 mg/kg, respectively. The GABA transaminase inhibitor gamma-acetylen GABA (GAG) and the GABA agonist 3-aminopropanesulfonic acid had no effects, even when high doses were administered. The GABAA receptor antagonist bicuculline had no effect by itself nor did it block the effects of THIP. It is therefore suggested that the GABAA receptor is of slight importance in the control of lordosis behavior. No evidence could be found supporting the hypothesis that an interaction between P and GABA is important for hormone-induced receptivity. It does not appear likely that motor disturbances are responsible for the inhibitory effects of baclofen and THIP. The exact mechanism by which these drugs inhibit lordosis behavior is not clear at present.
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PMID:GABAergic drugs and lordosis behavior in the female rat. 255 11

The GABAA agonists 3-amino-1-propanesulfonic acid and THIP reduced sexual behaviour in male rats only at relatively high doses, whereas baclofen produced an almost complete inhibition at a low dose (2.5 mg/kg). The GABA transaminase inhibitor aminooxyacetic acid had no effects, while gamma-acetylenic GABA produced a slight inhibition of sexual behaviour. The GABAA antagonist bicuculline had no effect. When THIP was administered concurrently with bicuculline, the former drug was potentiated. Therefore it is concluded that the GABAA receptor is not responsible for the inhibitory actions of THIP, and since baclofen was the most potent drug with regard to effects on sexual behaviour, it is suggested that the GABAB rather than the GABAA receptor is involved in the control of that behaviour. The slight effects of the transaminase inhibitors and the lack of effect of bicuculline suggest that the GABAergic neurons participating in the control of sexual activity are not tonically active. Finally, data are presented showing that the effects of GABAergic drugs on sexual behaviour are probably independent from those on locomotor activity.
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PMID:GABAergic drugs and sexual behaviour in the male rat. 299 Sep 71

The locomotion-reducing effect of the GABAB agonist baclofen was compared with that of the GABAA agonists, aminopropanesulfonic acid (APSA) and THIP. It was found that baclofen was more potent than the other drugs. After intraventricular injection, baclofen induced almost complete immobility, whereas APSA did not affect locomotor activity. THIP had an intermediate effect. The GABA transaminase inhibitor gamma-acetylenic GABA (GAG) provoked a dose-dependent reduction of locomotion. Neither the effects of THIP nor those of GAG could be blocked by concurrent administration of bicuculline. The antagonist itself did not affect locomotor activity. It is concluded that the GABAA receptor is not important for the locomotion-reducing effects of GABAergic drugs.
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PMID:The locomotor-reducing effects of GABAergic drugs do not depend on the GABAA receptor. 299 28

Directly and indirectly acting GABAergic agonists were assessed for their ability to alter striatal dopamine catabolism after subchronic administration (7-14 days) via subcutaneously implanted osmotic minipumps. THIP, kojic amine and baclofen failed to alter striatal DOPAC and HVA concentrations, but THIP and kojic amine were effective after a single acute dose. Striatal GABA levels proved difficult to elevate when inhibitors of GABA transaminase were released from minipumps, but a high dose of gamma-vinyl GABA increased GABA by 44% of control, although striatal dopamine and DOPAC levels were unaltered. [3H]GABA binding studies revealed that THIP and kojic amine, but not baclofen or gamma-acetylenic GABA, produced large increases in [3H]GABA 'A' binding (150 and 228% of control respectively) which were attributable to altered densities of binding sites without changes in affinity. Despite alterations in GABAergic function, nigrostriatal dopaminergic neurones seem to develop tolerance to the effects of GABAergic drugs.
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PMID:Subchronic administration of GABAergic agonists elevates [3H]GABA binding and produces tolerance in striatal dopamine catabolism. 400 41

beta-Endorphin, Met-enkephalin, substance P, and somatostatin concentrations were evaluated in the hypothalami of rats treated either acutely or chronically (15 days) with sodium valproate, diphenylhydantoin, phenobarbital, or ethosuximide. All of these drugs, with the exception of ethosuximide, induced significant decreases in beta-endorphin concentrations after acute treatment, while only sodium valproate induced a decrease after chronic treatment. The acute and chronic effects of sodium valproate were also produced by aminooxyacetic acid, an inhibitor of gamma-aminobutyric acid (GABA) transaminase, while another GABA transaminase inhibitor, ethanolamine-O-sulphate, and THIP, a GABA receptor agonist, were effective after acute administration. Metenkephalin, substance P, and somatostatin concentrations were never affected by the drugs used. The present results, indicating that antiepileptic agents specifically decrease beta-endorphin concentrations, seem to correlate well with the capacity of these agents to blunt the epileptic activity of the peptides tested. Moreover, our data suggest that GABA may be involved in the anticonvulsant-induced reduction of beta-endorphin concentrations.
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PMID:Antiepileptic agents affect hypothalamic beta-endorphin concentrations. 620 24

Rat brain GABA levels were elevated chronically by daily administration of gamma-vinyl GABA, an enzyme-activated, irreversible inhibitor of GABA:2-oxo-glutarate aminotransferase (GABA-T; EC2.6.1.19). Following various periods of drug treatment and withdrawal, the sensitivity of dopamine and GABA receptors in the CNS was determined by biochemical and behavioral evaluations. In contrast to chronic haloperidol treatment, none of the treatment schedules with gamma-vinyl GABA had any significant effect on parameters such as apomorphine induced locomotor activity, [3H] spiperone binding or dopamine-stimulated adenylate cyclase in the corpus striatum; nor did gamma-vinyl GABA treatment affect [3H] GABA binding or GABA-activated [3H] diazepam binding in the cerebral cortex. Moreover, co-administration of gamma-vinyl GABA and haloperidol did not alter the ability of the neuroleptic to induce supersensitivity in the striatal dopaminergic system. Thus, it appears that, in contrast to reported studies using chronic administration of other less specific GABA-T inhibitors such as gamma-acetylenic GABA, amino-oxyacetic acid and isonicotinic acid hydrazide or direct GABA agonists such as THIP (4,5,6,7-tetrahydroisoxazolo (5,4-c-)-pyridin-3-ol) or kojic amine, gamma-vinyl GABA does not alter the sensitivity of the striatal dopaminergic system.
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PMID:Chronic elevation of brain GABA by gamma-vinyl GABA treatment does not alter the sensitivity of GABAergic or dopaminergic receptors in rat CNS. 630 25


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