Article date: 1992/9/1
PubMed ID: 1493256
Journal name: Journal of physiology and pharmacology : an official journal of the Polish Physiological Society (ISSN: 0867-5910)
The effect of gamma-aminobutyric acid-receptor agonists, GABA and muscimol on the pituitary-adrenocortical activity, measured indirectly through corticosterone secretion, and the receptors involved were investigated in conscious rats. GABA given ip induced a dual effect, in lower dose (10 mg/kg) it significantly decreased the resting serum corticosterone levels while in higher doses (100-500 mg/kg) it considerably raised that level. Muscimol (0.5 mg/kg ip) also increased the corticosterone concentration. Both GABA and muscimol given intracerebroventricularly (icv) induced a significant, dose-related increase in serum corticosterone levels. Bicuculline, a GABAA-receptor antagonist, totally abolished the corticosterone response to GABA but did not influence the response to muscimol. Pretreatment with atropine did not affect the corticosterone response to GABA but significantly diminished the response to muscimol. These results suggest that GABA moderately inhibits the pituitary-adrenal axis at the pituitary level but significantly stimulates it at the hypothalamic level. The stimulatory effect of GABA, but not muscimol, is mediated by hypothalamic GABAA-receptors, and in the effect of muscimol hypothalamic cholinergic, muscarinic receptors are involved to a significant extent.
Author List: Borycz J, Borycz J A, Bugajski J
Publication Types: Journal Article
Substances mentioned in the article: Muscimol; gamma-Aminobutyric Acid; Atropine; Corticosterone; Bicuculline;
Mesh terms: Animals; Atropine/administration & dosage; Bicuculline/administration & dosage; Corticosterone/blood; Injections, Intraperitoneal; Injections, Intraventricular; Male; Muscimol/administration & dosage; Rats; Rats, Wistar; gamma-Aminobutyric Acid/administration & dosage;