Central inhibition by gamma-aminobutyric acid of the release of vasopressin by carbachol in the rat.
1. gamma-Aminobutyric acid (GABA) inhibited the antidiuretic response and the increased urinary excretion of vasopressin produced by carbachol when both drugs were injected into a lateral cerebral ventricle (i.c.v.) in the water-loaded rat under ethanol anaesthesia. 2. The inhibitory effect of GABA was mimicked by muscimol and 3-amino-1-propane sulphonic acid (3-APS) and blocked by bicuculline. 3. GABA injected i.v. or into the cisterna magna (i.cist.) did not inhibit the release of vasopressin by carbachol injected i.c.v. 4. The results suggest a role for GABA as a putative inhibitory transmitter in the hypothalamo-neurohypophysial system, acting directly on the supraoptic or paraventricular nuclei in the anterior hypothalamus.
Chowdrey
H S
HS
Medical Unit, Westminster Hospital, London.
Bisset
G W
GW
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002217:Carbachol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004231:Diuresis / Q000187:drug effects; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014667:Vasopressins / Q000652:urine*; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage / Q000494:pharmacology*
D014667:Vasopressins; D005680:gamma-Aminobutyric Acid; D002217:Carbachol