Corticotropin-releasing factor and gonadotropin-releasing hormone pulse generator activity in the rhesus monkey. Electrophysiological studies.
The effect of corticotropin-releasing factor (CRF) on the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator, the central neuronal system governing pulsatile pituitary luteinizing hormone (LH) secretion, was studied electro-physiologically in 6 ovariectomized rhesus monkeys bearing bilateral arrays of recording electrodes implanted in the mediobasal hypothalamus. 'Volleys' of increased multiunit activity (MUA) were recorded for 6-10 h in animals placed in primate chairs. The circulating concentrations of LH and cortisol were determined by radioimmunoassay in blood samples taken every 10 min for 3-4 h prior to the administration of CRF (200 micrograms, i.v.) and for 3-6 h thereafter. CRF resulted in a significant decrease in the frequency of pulse generator activity in 4 of 6 animals, a significant decrease in the duration of MUA volleys and a rise in circulating cortisol levels in all 6 monkeys. Treatment with metyrapone (30 mg/kg, i.m.), an inhibitor of adrenal steroidogenesis that prevented the CRF-induced rise in serum cortisol levels, did not reverse the inhibitory effects of CRF on the frequency or duration of MUA volleys. The opiate antagonist naloxone (0.8 mg/kg, i.v., 10 min prior to CRF followed by 0.8 mg/kg/h infusion) blocked the effects of CRF on MUA volley frequency in 2 of 3 animals, but failed to block the effect of CRF on MUA volley duration, suggesting that endogenous opioids may mediate the action of CRF on pulse generator frequency but not on duration.
Williams
C L
CL
Laboratory for Neuroendocrinology, University of Texas Medical School, Houston.
Nishihara
M
M
Thalabard
J C
JC
Grosser
P M
PM
Hotchkiss
J
J
Knobil
E
E
D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000502:physiology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D008253:Macaca mulatta; D008797:Metyrapone / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D010052:Ovariectomy; D012636:Secretory Rate / Q000502:physiology
D007987:Gonadotropin-Releasing Hormone; D009270:Naloxone; D003346:Corticotropin-Releasing Hormone; D008797:Metyrapone