Escape from chronic estrogenic suppression of ovarian function in the adult rhesus monkey: evidence for changing sensitivity of gonadotropin secretion to estrogen inhibition

Endocrinology
R B BilliarB Little

Abstract

Regularly menstruating female rhesus monkeys were implanted sc with Silastic tubing packed with estrone. The implants were replaced every 6-8 months to maintain the serum estrone and estradiol concentrations constantly elevated 1.5-2.5-fold, i.e. in the midfollicular phase range, for 4 yr. Increasing the estrone and estradiol concentrations initially led to anovulation which persisted for 6 to 15 months after which three of four of the estrogen-treated animals resumed ovulatory cycles. These animals then waxed and waned between anovulation and ovulatory cycles for the remainder of the study period. The resumption of ovulatory cycles were attributed to an escape of the central nervous system-pituitary axis from the suppressive effect of the elevated estrogen concentrations, since serum estradiol concentrations did not change. During anovulatory and ovulatory months the basal LH concentration was not significantly increased in the estrogen-treated monkeys compared to the control animals, but it was significantly reduced during anovulatory months compared to ovulatory months. Furthermore, LH secretion in response to a bolus of GnRH was attenuated in the monkeys chronically exposed to the acyclic elevation of blood estrogen levels....Continue Reading

Citations

Jan 1, 1993·Baillière's Clinical Endocrinology and Metabolism·S J Richardson
Jan 1, 1993·The Journal of Urology·A A HassanM M Elhilali

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