GABA receptor stimulation increases the release of vasopressin and oxytocin in vitro.
The release of oxytocin and vasopressin from rat neurointermediate lobes was determined in vitro. The electrically evoked release of posterior pituitary hormones was markedly potentiated by the GABA receptor agonist, isogauvacin, an effect which was abolished by the GABAA receptor antagonist bicuculline. Spontaneous hormone outflow was not affected by the substances tested. The results suggest the existence of a GABA receptor on the terminal fibres in the pituitary, facilitating the release of oxytocin and vasopressin.
Fjalland
B
B
Department of Biology, Royal Danish School of Pharmacy, Copenhagen, Denmark.
Christensen
J D
JD
Grell
S
S
D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D001640:Bicuculline / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D007539:Isonicotinic Acids / Q000494:pharmacology; D010121:Oxytocin / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000502:physiology*; D014590:Uterine Contraction / Q000187:drug effects; D014667:Vasopressins / Q000378:metabolism*
D007457:Iodine Radioisotopes; D007539:Isonicotinic Acids; D011963:Receptors, GABA-A; D014667:Vasopressins; D001127:Arginine Vasopressin; D010121:Oxytocin; D001640:Bicuculline; C015300:isoguvacine