title: GnRH release from the mediobasal hypothalamus. In vitro regulation by oxytocin.
abstract: The effects of oxytocin (OT) on gonadotropin-releasing hormone (GnRH) release from the adult male rat mediobasal hypothalamus and median eminence were studied in an in vitro incubation system. OT induced a dose-related (10(-13) to 10(-9) M) inhibition of both basal and KCl-stimulated GnRH release from the mediobasal hypothalamus. OT, but not arginine vasopressin, also inhibited GnRH release from the isolated median eminence, and this inhibition was blocked by treatment with an OT receptor antagonist. Moreover, antagonist alone stimulated GnRH release from the isolated median eminence. These results demonstrate that OT can inhibit in vitro release of GnRH by an OT receptor mediated mechanism at the level of neurosecretory terminals in the median eminence and suggest that the hypothalamic OT neuronal system may play an inhibitory role in the modulation of GnRH secretion.
mesh_terms: D000818:Animals; D007033:Hypothalamus, Middle / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008473:Median Eminence / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010121:Oxytocin / Q000494:pharmacology*; D010906:Pituitary Hormone-Releasing Hormones / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011945:Receptors, Angiotensin / Q000187:drug effects / Q000502:physiology; D018045:Receptors, Oxytocin
chemical_list: D010906:Pituitary Hormone-Releasing Hormones; D011945:Receptors, Angiotensin; D018045:Receptors, Oxytocin; D010121:Oxytocin