GnRH release from the mediobasal hypothalamus: in vitro inhibition by corticotropin-releasing factor.

The effects of corticotropin-releasing factor (CRF) on GnRH release from the adult male rat mediobasal hypothalamus (MBH) and median eminence (ME) were studied in an in vitro incubation system. CRF induced a dose-related inhibition of GnRH release from both the MBH and the isolated ME, and this inhibition was blocked by treatment with CRF receptor antagonist. Moreover, GHRF, a hypothalamic peptide similar in size to CRF, did not alter the ME release of GnRH. These results demonstrate that CRF can inhibit in vitro release of GnRH by a CRF receptor-mediated mechanism at the level of the neurosecretory terminals in the ME. Thus, increased hypothalamic CRF secretion associated with stress and adrenalectomy may inhibit hypothalamic GnRH release and produce the suppression of pituitary luteinizing hormone secretion which occurs under these conditions.