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

The enzymes responsible for both the formation and degradation of gamma-aminobutyric acid (GABA) are known to exist in the thyroid gland. The thyroid is also equipped with high- and low-affinity uptake mechanisms for GABA. We therefore investigated the effects of GABA on basal and TSH-stimulated thyroid hormone secretion in the mouse according to the McKenzie technique. Iodine-deficient mice were pretreated with Na125I and thyroxine. GABA (1-100 nmol/kg iv) did not affect basal radioiodine levels. However, the neurotransmitter inhibited the TSH-induced increase in blood radioiodine levels. Thus, the increase after iv injection of TSH at 70 microU/animal (205 +/- 15%) was inhibited by GABA at 10 nmol/kg (to 155 +/- 14%; P less than 0.05). In contrast, a dose as high as 100 nmol/kg was necessary to inhibit the effect of TSH at its high dose of 350 microU/animal. The GABAA-receptor antagonist bicuculline counteracted this inhibitory action of GABA. Furthermore, pretreatment with the inhibitor of GABA-degrading enzyme GABA transaminase (gamma-vinyl GABA) impaired the stimulatory effect of TSH on blood radioiodine levels. Thus, at 350 microU/animal, TSH increased blood radioiodine levels by 363 +/- 34% in controls vs by only 246 +/- 32% in animals pretreated with gamma-vinyl-GABA (P less than 0.05). We conclude that GABA is an inhibitor of TSH-stimulated thyroid hormone secretion.
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PMID:GABA inhibits thyroid hormone secretion in the mouse. 248 71

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-methyl-4-phenylpyridinium iodide (MPP+) and gamma-vinyl-gamma-aminobutyric acid (gamma-vinyl GABA) are drugs demonstrated to alter catecholamine or gamma-aminobutyric acid (GABA) concentrations in vertebrate nervous tissue. MPTP and MPP+, which are potent and selective vertebrate neurotoxins, are effective in depleting noradrenaline and dopamine concentrations in goldfish. However, only MPP+ depletes dopamine in the central nervous tissues of the cockroach, and only when injected directly into the nervous tissue. Systemic injection of gamma-vinyl GABA, a selective GABA transaminase inhibitor in vertebrates, increases GABA concentrations in goldfish but not cockroach nervous tissue. Incubations of both goldfish hypothalamus and cockroach nervous tissue demonstrated the presence of GABA transaminase activity in vitro. However, the GABA transaminase activity obtained from goldfish tissues was much more sensitive to inhibition by gamma-vinyl GABA than that obtained from cockroach nervous tissue. These results demonstrate that MPTP, MPP+ and gamma-vinyl GABA are useful pharmacological tools which can alter neurotransmitter concentrations in a lower vertebrate. Unfortunately, they possess limited effectiveness in the cockroach.
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PMID:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and gamma-vinyl-gamma-aminobutyric acid (gamma-vinyl GABA) alter neurotransmitter concentrations in the nervous tissue of the goldfish (Carassius auratus) but not the cockroach (Periplaneta americana). 809 92