title: On the use of enzyme inhibitors to study the synthesis and utilization of brain GABA.
abstract: Changes in the GABA concentration in different parts of the rat brain were studied following inhibition of the glutamic acid decarboxylase or the GABA-alpha-ketoglutaric acid aminotransferase. The GABA concentration was reduced by the decarboxylase inhibitors 4-deoxypyridoxine and isoniazid, but not by 3-mercaptopropionic acid and DL-allylglycine. The aminotransferase inhibitor gamma-acetylenic GABA increased the concentration of GABA and this effect was markedly inhibited by 3-mercaptopropionic acid and partly by 4-deoxypyridoxine and isoniazid. The 4-deoxypyridoxine-induced decrease in GABA concentration was approximately maximal after 400 mg/kg intraperitoneally and 90 min. The brain DOPA decarboxylase activity in vivo was not inhibited by 4-deoxypyridoxine. The GABA concentration in the substantia nigra was reduced by 75 per cent 4 days after section of the striato-nigral GABA neurones. In the denervated substantia nigra, 4-deoxypyridoxine did not change the concentration of GABA whereas the effect of gamma-acetylenic GABA was reduced by 70 per cent.
mesh_terms: D000612:4-Aminobutyrate Transaminase / Q000037:antagonists & inhibitors*; D000480:Alkynes; D000614:Aminocaproates / Q000494:pharmacology; D000818:Animals; D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D001921:Brain / Q000378:metabolism*; D005968:Glutamate Decarboxylase / Q000037:antagonists & inhibitors*; D007538:Isoniazid / Q000494:pharmacology; D008297:Male; D011736:Pyridoxine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D000480:Alkynes; D000614:Aminocaproates; D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D011956:Receptors, Cell Surface; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; C013785:4-amino-5-hexynoic acid; C004675:4-deoxypyridoxine; D000612:4-Aminobutyrate Transaminase; D005968:Glutamate Decarboxylase; D011736:Pyridoxine; D007538:Isoniazid