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)

Chronically alcoholized intoxication (1.5--2 months) induces adaptation of cerebral neurones to changing equilibrium states of biochemical processes by altering the activity of enzymes of GABA metabolism, reduction of alanine and aspartate transaminase activity and increase of LDH and succinate dehydrogenase activity. In the cerebellum and cerebral hemispheres during alcohol abstinacy the activity of GABA-T, succinate dehydrogenase and aspartate transaminase was reduced while that of LDH and alanine transaminase was increased. The administration of fusarinic acid (100 mg/kg i. p.) to control animals induced a sharp increase of GAD activity in both structures of the brain. The stimulatory effects of fusarinic acid were not observed when it was administered to animals receiving alcohol chronically. Motor activity or rats was markedly reduced during chronical alcoholism and the first days of alcohol abstinacy (24--48 h), as well as following injection fusarinic acid and homopantothenic acid. The increase of locomotion and the vertical component of motor activity was observed only following one week or one month after alcohol abstinacy.
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PMID:[Adaptive changes in brain metabolism during chronic alcoholic intoxication]. 57 38

A synaptic vesicle fraction was prepared from calf brain cortex, containing 10 identified amino acids and two unidentified ninhydrin-positive compounds, one of which is apparently a peptide. The most plentiful amino acids were taurine (1.8 nmol/g original tissue), glutamic acid (1.8), serine (0.9), aspartic acid (0.8) and GABA (0.8); the others identified were cysteic acid (or cysteinesulphinic acid), glutamine, alanine, glycine and lysine. The unknown peptide occurred in a high concentration (about 16 alanine equivalents/g), and contained mainly aspartic acid and serine. Cysteic acid (or cysteinesulphinic acid) also occurred in relatively high amounts, but its peak contained acid-labile impurities. The influx of [14C]glutamate into the vesicles took place by means of non-saturable migration, while two saturable systems having very similar properties were dominant only at low glutamate concentrations. Influx constants for these quantitatively low uptake systems were Km, 34 and 92 micrometer, and Vmax, 33 and 49 nmol/min/g obtained by v versus v/S plot. Almost the same values were also obtained by a 1/v versus 1/S plot. GAD and GABA-T activities in the vesicles were only 1/200th of those in the synaptosomes.
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PMID:Amino acids in the synaptic vesicle fraction from calf brain: content, uptake and metabolism. 58 77

L-Cycloserine dose-dependently inhibited the activity of gamma-aminobutyric acid (GABA)-transaminase (GABA-T) and elevated the level of GABA in whole mouse brain with a peak effect 3-4 hr after a single intraperitoneal injection. At a dose (30 mg/kg) which elevated the level of GABA almost 4-fold, L-cycloserine moderately increased the content of alanine and slightly reduced that of aspartate, glutamate and glycine in the brain. L-Cycloserine (10-30 mg/kg, p.o. or i.p.) prevented tonic seizures induced by 3-mercaptopropionic acid (3-MPA) and audiogenic seizures in DBA/2 mice, without affecting those evoked by pentylenetetrazol, bicuculline and electroshock. Similarly small doses of L-cycloserine reduced the level of cGMP in the cerebellum of rats, prevented its elevation by 3-MPA and attenuated the hypothalamically-elicited rage reaction in cats. Larger doses of L-cycloserine (greater than 30-100 mg/kg) impaired the performance of mice in the rotarod, chimney and horizontal wire tests, and reduced spontaneous locomotor activity of rats. Upon repeated administration the inhibitory effect of L-cycloserine on the activity of GABA-T and on seizures elicited by 3-MPA in mice increased. In contrast, the depressant action of L-cycloserine on motor performance and locomotion declined in subchronically-treated mice and rats. The levels of amino acids in brain after repeated administration did not differ markedly from those in acutely-treated mice. It is suggested that small doses of L-cycloserine, probably by increasing GABAergic inhibition, reduce hyperexcitability in the brain in acute- and subchronically-treated animals. Larger doses of L-cycloserine, possibly by inducing multiple neurochemical changes, evoke central depressant effects which diminish during subchronic treatment.
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PMID:L-cycloserine: behavioural and biochemical effects after single and repeated administration to mice, rats and cats. 301 1

Biochemical and pharmacological effects of gamma-vinyl GABA (Vigabatrin, GVG), and irreversible enzyme-activated inhibitor of 4-aminobutyrate: 2-oxoglutarate aminotransferase (EC 2.6.1.19; GABA-T), were measured in mice. This anticonvulsant produced a time- and dose-dependent elevation of the GABA, phenylalanine and lysine contents of cortical tissue and simultaneously decreased glutamate, aspartate and alanine levels. In addition, GVG caused a biphasic change in glutamine concentrations (a decline 1-4 hours after administration, followed 20 hours later by an increase). Moreover, we found a new, as yet unidentified amino acid in the brain eluting with the same retention time as alpha-aminoadipic acid from an HPLC cation-exchange column. The level of this novel chemical entity was greatly increased by GVG 20 hours after injection of the drug. At all tested intervals between 1 and 60 hours after injection, GVG was ineffective against maximal electroshock. The GABA-T inhibitor dose-dependently protected mice against isoniazid-induced seizures, simultaneously causing an increase in brain GABA concentrations. However, this apparent correlation applied only until 4 hours after treatment. To better define the anticonvulsant profile of GVG, groups of mice were treated, 1, 2, 4, and 24 hours prior to challenge with convulsant doses of strychnine, pentetrazole (PTZ), and picrotoxin, and brain amino acid levels, including brain concentrations of GVG, were measured. In all instances, the time dependency of the anticonvulsant effects of GVG and of increases in brain GABA levels differed. Amino acid concentrations in animals treated only with GVG were similar to those in animals given GVG and a chemical convulsant. GVG showed no selectivity for seizures produced by impairment of GABA-ergic neurotransmission. Although GVG is an effective GABA-T inhibitor, it apparently affects several other pyridoxal-phosphate-dependent cerebral enzymes and/or interacts with other neurotransmitter systems as well.
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PMID:Gamma-vinyl GABA: comparison of neurochemical and anticonvulsant effects in mice. 341 34

Metabolism of the glutamate group of amino acids--glutamic acid, gamma-amino-butyric acid, glutamine, aspartic acid and alanine--was studied in the brain of rat as a function of age. The levels of glutamic acid, glutamine and aspartic acid decreased while those of gamma-aminobutyric acid, and alanine increased with age. The results on the activity of the twelve enzymes involved in the metabolism showed that five of them (glutamate dehydrogenase, glutamine synthase, gamma-aminobutyric acid transaminase, succinic semialdehyde dehydrogenase and NAD+-isocitrate dehydrogenase) decreased, while four of them (glutaminase, glutamotransferase, glutamic acid decarboxylase, and alpha-ketoglutarate dehydrogenase) increased. The other three enzymes (aspartate aminotransferase, alanine aminotransferase and NADP+-isocitrate dehydrogenase) did not show any significant change in activity. An age-related increase was seen in alpha-ketoglutarate and ammonia, the intermediates involved in the metabolism of these amino acids. The changes in the level of these amino acids are discussed in relation to the altered energy metabolism during aging.
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PMID:Metabolism of the glutamate group of amino acids in rat brain as a function of age. 614 62

Decreasing concentrations of alanine aminotransferase were observed in nine patients receiving gamma-acetylenic-GABA, an inhibitor of GABA aminotransferase. In vitro studies showed that preincubation at 37 degrees C of serum with gamma-acetylenic-GABA and with urine from a patient receiving the drug led to inhibition of alanine aminotransferase. This inhibition of alanine aminotransferase by gamma-acetylenic-GABA was neutralized by 1-analine, the natural substrate for the enzyme. The mechanism of inhibition may be a competition between the drug and 1-alanine for the substrate binding site of the enzyme.
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PMID:Decreased alanine aminotransferase activity in serum of man during gamma-acetylenic-GABA treatment. 741 57

The effect of aminooxyacetic acid (AOAA), an inhibitor of pyridoxal phosphate-dependent enzymes (including the aminotransferases), on the K(+)-evoked release of amino acids was studied during microdialysis of neostriatum in anesthetized rats. K(+)-evoked (100 mM) release of aspartate, glutamate, and GABA was inhibited by 74%, 70%, and 63%, respectively, by 20 mM Mg2+ and are therefore reflecting release from the transmitter pools of these amino acids. Treatment with AOAA decreased the K(+)-evoked release of aspartate, glutamate, and GABA instantly, with a delayed decrease in the efflux of glutamine and alanine, arguing that the synthesis of transmitter amino acids in particular is sensitive to the activity of pyridoxal phosphate-dependent enzymes. Interestingly, GABA release increased severalfold following the initial decrease, probably reflecting inhibition by AOAA on GABA aminotransferase, the enzyme most sensitive to inhibition by AOAA, and responsible for enzymatic inactivation of transmitter GABA.
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PMID:Evidence using in vivo microdialysis that aminotransferase activities are important in the regulation of the pools of transmitter amino acids. 809 92

Drugs which elevate brain levels of the inhibitory amino acid neurotransmitter GABA by inhibiting the GABA catabolizing enzyme GABA transaminase (GABA-T) have been developed for treatment of brain disease, such as epilepsy. Among all GABA-T inhibitors available, vigabatrin is thought to be the most selective compound, and this drug is the only GABA-T inhibitor in clinical use. However, some previous studies have indicated that vigabatrin might affect the metabolism of several amino acids not directly linked to the GABA shunt. In the present study, various amino acids, involving inhibitory and excitatory neurotransmitters, were determined in 12 brain regions and plasma of rats after treatment with anticonvulsant doses of vigabatrin and the less selective GABA-T inhibitors aminooxyacetic acid (AOAA) and gamma-acetylenic GABA (GAG). Furthermore, the antiepileptic drug valproate, which is also thought to act via the GABA system, was included for comparison. The GABA-T inhibitors markedly enhanced GABA levels in all brain regions examined, while valproate induced only moderate increases in some regions. All drugs, including valproate, significantly decreased aspartate in the brain to a similar extent, and the GABA-T inhibitors but not valproate decreased levels of glutamate. The decreases in aspartate and glutamate levels were not correlated with the different magnitudes of GABA increase produced by GABA-T inhibitors, suggesting that these effects were not simply due to the altered GABA degradation. In addition to glutamate and aspartate, alanine levels were decreased by GABA-T inhibitors but not valproate in several regions. Brain levels of glutamine were decreased by GAG and vigabatrin but increased by valproate and partly also by AOAA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential effects of vigabatrin, gamma-acetylenic GABA, aminooxyacetic acid, and valproate on levels of various amino acids in rat brain regions and plasma. 820 5

Gamma-vinyl GABA (GVG, Vigabatrin), an irreversible inhibitor of GABA transaminase (GABA-T) that inhibits cocaine-induced place preference and self administration has been proposed as a treatment for cocaine addiction. It was therefore important to assess if there was an enhanced toxicity from the combination of GVG with cocaine. No mortality was observed with administration of GVG (60 mg/kg i.v.) alone (n=8) or in combination (n=6) with cocaine (5 mg/kg i.v.). Cocaine-induced EKG alterations were not affected by GVG pretreatment. Plasma alanine amino transferase activity was reduced by GVG treatment and this was not further modified by cocaine administration. These results suggest that acute co-administration of GVG and cocaine does not result in immediate cardiovascular or hepatic toxicity of sufficient significance, to preclude further clinical trials.
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PMID:Co-administration of gamma-vinyl GABA and cocaine: preclinical assessment of safety. 1050 33

1. Phenelzine (PLZ) is an antidepressant with anxiolytic properties. Acute and chronic PLZ administration increase brain GABA levels, an effect due, at least in part, to an inhibition of the activity of the GABA metabolizing enzyme, GABA transaminase (GABA-T). 2. Previous preliminary reports have indicated that acute PLZ treatment also elevates brain alanine levels. As with GABA, the metabolism of alanine involves a pyridoxal phosphate-dependent transaminase. 3. In the study reported here, the effects of acute PLZ treatment on the levels of various amino acids, some of which are also metabolized by pyridoxal phosphate-dependent transaminases were compared in rat whole brain. Of the 6 amino acids investigated, only GABA and alanine levels were elevated (in a time- and dose-dependent manner). 4. The elevation in brain alanine levels could be explained, at least in part, by a time- and dose-dependent inhibitory effect of PLZ on alanine transaminase (ALA-T), although as with GABA the increases are higher than expected from the degree of enzyme inhibition produced. In addition, we also showed that the elevation in alanine levels and the inhibition of alanine transaminase in the brain are retained after 14 days of PLZ treatment, and that PLZ produces a marked increase in extracellular levels of alanine. 5. These results are discussed in terms of their relevance to synaptic function and to the pharmacological profile of PLZ.
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PMID:Effects of the antidepressant/antipanic drug phenelzine on alanine and alanine transaminase in rat brain. 1177 64


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