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γ‐Aminobutyric Acid Turnover in Rat Striatum: Effects of Glutamate and Kainic Acid
Author(s) -
Giorgi Osvaldo,
Meek James L.
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb09720.x
Subject(s) - kainic acid , glutamate decarboxylase , gabaergic , glutamate receptor , striatum , gaba transaminase , glutamic acid , gamma aminobutyric acid , aminobutyric acid , biochemistry , chemistry , medicine , biology , pharmacology , endocrinology , dopamine , receptor , amino acid , enzyme
The turnover rate of γ‐aminobutyric acid (GABA) in the rat striatum was estimated by measuring its accumulation after inhibition of GABA‐transaminase (GABA‐T) with gabaculine. Intrastriatal injections of 100 μg gabaculine induced a rapid and complete inhibition of GABA‐T. GABA accumulation was linear with time for at least 60 min (estimated turnover rate = 25 nmol/mg protein/h). The accumulation of GABA after gabaculine administration in animals that had been treated with kainic acid (5 nmol intrastriatally, 7 days) was only 40% of the control value, indicating that a major fraction of the net increase in GABA content induced by gabaculine originates in kainic acid‐sensitive neurons. Intrastriatal injection of a mixture of kainic acid (5 nmol) and gabaculine caused a net increase in striatal GABA content significantly greater than that observed in controls, suggesting that neuronal death induced by kainic acid is preceded by a period of increased neuronal activity. Glutamic acid, the putative neurotransmitter for the excitatory corticostriatal pathway, also produced a significant increase in striatal GABA accumulation when injected together with gabaculine. This effect was blocked by the administration of the glutamate receptor antagonist glutamic acid diethyl ester. The interactions between GABAergic neurons and other neurotransmitters present in the striatum were also analyzed.