AJP - Endocrinology and Metabolism, Vol 247, Issue 1 84-E87, Copyright © 1984 by American Physiological Society
Small doses of human chorionic gonadotropin prevent estradiol-induced luteolysis
P. K. Westfahl, L. E. Horton, H. L. Stadelman and J. A. Resko
The manner in which exogenous 17 beta-estradiol (E2) induces premature
luteolysis in primates is unclear. In an effort to determine whether
exogenous luteotropic hormone inhibits E2-induced luteolysis, E2 capsules
were implanted subcutaneously in 11 cynomolgus macaques during the early
luteal phase; six animals received injections of human chorionic
gonadotropin (hCG; 7.5, 10, or 15 IU/day) for 10 days, and the remaining
monkeys received saline. Blood was collected once daily for measurement of
E2, progesterone, and bioactive luteinizing hormone (LH). Peak progesterone
concentrations were between 0.7 and 5.0 ng/ml and declined prematurely in
monkeys given E2 plus saline; the luteal phase was 11.5 +/- 0.6 days (mean
+/- SE). With E2 plus hCG treatment, serum progesterone continued to
increase after E2 capsule placement and reached peak levels of 4.0-13.0
ng/ml; the luteal phase was 15.3 +/- 0.5 days. Therefore, E2-induced
luteolysis was overcome by concurrent administration of hCG. These results
suggest that exogenous tropic hormone circumvents the inhibitory influence
of E2 on luteal function, but the details of the interaction remain
unknown.
