Peripheral and not central suppression of ovarian function during osmotic pump infusion of adrenocorticotropin-(1-24) for one menstrual cycle in the cynomolgus monkey and its partial compensation by a transitory elevation of sex hormone-binding globulin levels.

The purpose of our study was to assess the impact of subchronic administration of ACTH-(1-24) on ovarian function in the primate using a repeated measures experimental design. Osmotic pumps that released ACTH-(1-24) at a dose of 67 micrograms/day were implanted sc in four cynomolgus monkeys for one menstrual cycle. The pumps were filled with saline for the two control cycles, one of which preceded and one of which followed peptide infusion. Administration of ACTH-(1-24) elevated cortisol levels in serum 1.6-fold and those in urine 2.2-fold, without affecting adrenal androgen concentrations. In the follicular phase (FP) of the menstrual cycle, infusion of ACTH-(1-24) did not alter serum levels of estradiol, FSH, or LH. However, immunoreactive estrone excretion in urine was decreased by 71% (P less than 0.05), and serum concentrations of sex hormone-binding globulin (SHBG) were increased by 100% (P less than 0.01). In the luteal phase (LP) of the menstrual cycle, infusion of ACTH-(1-24) suppressed levels of serum estradiol by 54% (P less than 0.001), urinary immunoreactive estrone by 72% (P less than 0.05), serum progesterone by 53% (P less than 0.001), and urinary immunoreactive pregnanediol by 71% (P less than 0.01). Serum FSH concentrations were increased during treatment by 100% (P less than 0.001) in LP, but LH concentrations were not altered. Also, serum levels of SHBG returned to control values in the LP. The lengths of menstrual cycles and the lengths of FP or LP were not affected during or after treatment. These data provide evidence that subchronic infusion of ACTH-(1-24) in primates: 1) suppresses estradiol production by the ovarian follicle as well as estradiol and progesterone production by the corpus luteum, 2) compromises ovarian function without concomitant suppression of serum gonadotropin levels, and 3) induces a transitory elevation of SHBG levels in the circulation, which may compensate for reduced estrogen output.