Intraventricular administration of arginine vasopressin suppresses prolactin release via a dopaminergic mechanism.
The present study was conducted to determine the effects of intracerebroventricular administration of arginine vasopressin (AVP) on the preovulatory prolactin (PRL) surge. Hourly injections of 1 or 5 micrograms AVP from 1200 to 1700 hr on proestrus prevented increases in plasma PRL levels that afternoon. However, following cessation of AVP treatment, a marked increase in PRL levels occurred between 1830 and 2030 hr. This "rebound" secretion of PRL was greater in rats given 5 micrograms AVP than in rats given the lower dose. The suppression of PRL release by AVP appears to be mediated by dopamine since 5 micrograms AVP failed to inhibit PRL release in animals pretreated with the dopamine antagonist domperidone. Interestingly, under these conditions, AVP increased PRL release compared to levels observed in saline-treated rats. In addition to suppressing PRL release, AVP exerted a dose-dependent inhibition of preovulatory LH release. The results suggest a possible interaction between AVP and dopamine in controlling PRL release which likely takes place within the median eminence.
D000818:Animals; D001127:Arginine Vasopressin / Q000008:administration & dosage / Q000494:pharmacology*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D004294:Domperidone / Q000494:pharmacology*; D004298:Dopamine / Q000502:physiology*; D005260:Female; D007276:Injections, Intraventricular; D007700:Kinetics; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D001127:Arginine Vasopressin; D004294:Domperidone; D011388:Prolactin; D004298:Dopamine