Corticotropin-releasing hormone inhibits gonadotropin secretion in the ovariectomized rhesus monkey

To evaluate whether the compromised gonadotropin secretion frequently occurring during stressful conditions in the primate may be related to an inhibitory action of CRH, the effects of ovine (oCRH) or human (hCRH) CRH on gonadotropin and cortisol secretion were studied in ovariectomized rhesus monkeys. LH secretion (assessed as area under the curve) decreased 35% and 21%, and cortisol increased 37% and 90%, 1-3 h after single iv injections of 200 and 500 micrograms oCRH, respectively (P less than 0.05 vs. pre-CRH control period; n = 4-7/dose). Single injections of 200 and 500 micrograms hCRH, respectively, resulted in 35% and 24% decreases in LH and 40% and 79% increases in cortisol secretion (P less than 0.05). Injections of 100 micrograms oCRH and hCRH elicited significant (P less than 0.05) increases in cortisol release (37% and 31%, respectively), but did not affect LH secretion. A 5-h infusion of hCRH (100 micrograms/h) reduced LH levels (23%, 49%, 59%, 61%, and 62% during the first through the fifth hour, respectively; P less than 0.05 for hours 2-5). FSH secretion also decreased during the hCRH infusion (26%, 33%, 42%, 46%, and 49% during the first through the fifth hour, respectively; P less than 0.05 for hours 3-5), while cortisol increased 76%. These data demonstrate that exogenous CRH administration results in inhibition of LH and FSH secretion in ovariectomized rhesus monkeys. These results are consistent with the hypothesis that elevated CRH levels could contribute to decreased LH and FSH secretion and, thus, disruption of reproduction function under conditions of stress in primates.