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)

Elevation of brain GABA levels by GABA-T inhibition is accompanied by a decrease of S-adenosylmethionine decarboxylase activity. This is followed by an increase of ornithine decarboxylase activity and a severalfold increase of brain putrescine levels. Spermidine and spermine levels are not significantly affected under these conditions. These unexpected findings support a regulatory interaction between GABA and polyamine metabolism.
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PMID:Regulatory interrelations between GABA and polyamines. I. Brain GABA levels and polyamine metabolism. 48 78

gamma-Acetylenic gamma-aminobutyric acid (GAG), an irreversible inhibitor of GABA transaminase, increased the concentration of GABA in feline spinal cords to 239% of the control value by 225 min after its injection. After administration of GAG to spinally transected cats, the height of the segmentally evoked dorsal root potential (DRP), which is generated at one point via a GABA synapse, was increased to more than twice the control value although the area increased only slightly. However, GAG had no effect on the segmental DRP in the decerebrate cat. In contrast, the DRP evoked in decerebrate cats by electrical stimulation of the brain stem, which is probably mediated by GABA, was decreased by administration of GAG. These effects of GAG were accompanied by the development of spontaneous primary afferent depolarizations which resembled spontaneous DRPs in both spinal and decerebrate cats. The temporal and size correlation between spontaneous DRPs occurring in different spinal roots indicate they are generated by an interneuronal pathway that is released by the action of GAG. The action of GAG on the segmental DRP in the spinal but not decerebrate preparation is also most easily explained by GAG-induced effects on interneuronal pathways. These data suggest GABA transaminase inhibition does not affect the axoaxonic GABA synapse mediating the DRP.
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PMID:Changes in primary afferent depolarization after administration of gamma-acetylenic gamma aminobutyric acid (GAG), a gamma-aminobutyric acid (GABA) transaminase inhibitor. 50 64

In chicks with cannulae chronically implanted into the III cerebral ventricle, the effects of a single dose (10 micrograms) of beta-endorphin on GABA and free glutamic acid content, GAD and GABA-T activities in the diencephalon, brain-stem and brain hemispheres were studied at the time of maximal behavioural stuporous state and analgesia. A significant decrease in GABA concentration both in the diencephalon and brain-stem, accompanied by a significant increase in GABA-T activity in the same areas, was shown to occur. No changes were observed in GAD activity and in glutamic acid content in the studied areas of the brain. In conclusion, present experiments suggest that some central effects of a beta-endorphin may be due to an interference with GABA-ergic transmission.
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PMID:Effects of intraventricular beta-endorphin on GABA system in some areas of chick brain. 52 83

GABA, its derivative -- gamma-hydroxybuturic acid and metabolite --succinic acid have a pronounced dilatatory activity on cerebral circulation in various brain parts. GABA increases cerebral circulation by 25.3%, gamma-hydroxybutyric acid by 35.9% and sucinic acid by 20.4%. In ischaemia of the brain a relationship has been established between cerebral circulation, changes in the GABA system in brain and in the walls of cerebral arteries. The content of GABA increases following enhancement of GAD activity and inhibition of GABA-T. The increase of endogenous GABA level in brain during hypoxia of the brain brings to an improvement of blood circulation through increasing collateral vessels. Experiments with GABA-T inhibition by aminooxyacetic acid give direct evidence about the role of the GABA system in cerebral blood circulation. This mechanism is evaluated by us as an example of an autoregulatory system that is realized by a feed-back mechanism providing the adaptability and compensatory function of cerebral haemodynamics to changing conditions.
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PMID:[Role of GABA and its derivatives in regulating cerebral circulation]. 57 37

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

Ketamine in a dose of 100 mg/kg (IP) produced stereotypic behavior and vigorous rotation in adult male Sprague-Dawley rats. The first rotation phase, accompanied by head swinging, was short and terminated by the anesthetic phase which lasted 20-30 min. The second rotation phase began 1-3 min after the end of the anesthetic phase. A single dose of GABA-T inhibitors, gamma-vinyl GABA (1200 mg/kg, IP) or gamma-acetylenic GABA (100 mg/kg, IP) administered 4 hours prior to ketamine, shortened the first rotation phase, increased the anesthetic phase, changed the pattern of postanesthetic rotation and reduced total and net rotation scores. Picrotoxin (3 mg/kg) given 10 min prior to ketamine tended to act in the opposite direction although none of its effects reached statistical significance.
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PMID:Ketamine-induced rotation: interaction with GABA-transaminase inhibitors and picrotoxin. 57 19

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

The effects were examined of two inhibitors of GABA-aminotransferase, amino-oxyacetic acid (AOAA) and RMI-71645-16, on depolarization-induced (30 mM K+) dopamine (DA) release from rat striatal slices. When added to the medium, these drugs increased the release of radiolabeled DA, either accumulated by high-affinity uptake or synthesized from 14C-tyrosine. AOAA did not modify the release of 14C-acetylcholine from striatal slices or 3H-noradrenaline from cortical slices. Moreover, 3H-DA release from substantia nigra was not affected. The data suggest the possibility that the effects of GABA-T inhibitors on striatal DA release are mediated by intrinsic GABA-ergic neurons.
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PMID:Increased dopamine release from rat striatal slices by inhibitors of GABA-aminotransferase. 59 Mar 29

The administration of L-cycloserine to mice resulted in a dramatic decrease in the activities of 4-aminobutyrate:2-oxoglutarate aminotransferase (GABA-T) and L-alanine:2-oxoglutarate aminotransferase (ALA-T) in both brain and liver. L-Aspartate:2-oxoglutarate aminotransferase was inhibited only slightly, and brain glutamic acid decarboxylase not at all. Liver ALA-T activity returned to near normal levels within 24 h of L-cycloserine administration whereas liver GABA-T and brain ALA-T activities had returned only halfway to normal levels in the same time period. The recovery in the activity of brain GABA-T was even slower. A consequence of the inhibition of brain GABA-T activity was an elevation in the GABA content of the tissue which was maximal 3 h after L-cycloserine administration and which was still noticeable 8 h after the drug treatment. L-Cycloserine was also a potent in vitro inhibitor of brain GABA-T activity. The inhibition was competitive with respect to GABA, the Ki value being 3.1 X 10(-5) M. The prior administration of L-cycloserine to mice significantly delayed the onset of isonicotinic acid hydrazide induced convulsions.
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PMID:Effect of L-cycloserine on brain GABA metabolism. 63 58

Gabaculine, a specific inhibitor of GABA transaminase, was injected bilaterally into the substantia nigra of rats. One day after injection, GABA was increased 11-fold in the nigra, 6-fold in thalamus and pons-medulla, and 2-fold in pallidum. 5 h after operation, rats showed continuous sniffing and head movement. This behaviour was blocked by a small dose of picrotoxin injected bilaterally into the nigra, but haloperidol (i.p.) was less effective. One day after injection, rats showed high ambulation and this ambulation was blocked by high doses of picrotoxin. On the second day, GABA contents in all regions were less than twice the control level and behaviour had returned to normal. Rats with gabaculine injected into the pallidum or medulla did not show changes of behaviour as seen in rats with injections into the substantia nigra at any of the times. Striatum dopamine turnover was slightly but significantly decreased at 5 h but not at 24 h after intra-nigral injection with gabaculine. The results suggest that gabaculine-induced sniffing and head movement were mediated by nigral GABAergic synapses and were independent of any dopaminergic system, and that the high ambulation at 24 h after operation may have been due to a non-specific effect of abnormal GABA elevation in thalamus and/or nigra.
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PMID:The effects of elevating gamma-amino butyrate content in the substantia nigra on the behaviour of rats. 68 78


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