Gonadotropic and antigonadotropic activity of ewe serum following chronic treatment with human chorionic gonadotropin (HCG).

Abstract

SummaryThree ewes were immunized with HCG. All ewes had high anti-HCG titers (>200 rat units/ml) and elevated serum LH levels as determined by ventral prostate weight assays and radioimmunoassays following the third series of immunizing injections. A significant increase in uterine weight was produced by the antisera in intact immature female rats. The antisera failed to neutralize the biological activity of ovine LH in the ventral prostate weight assay, but the antisera were able to block the occurrence of estrus to varying degrees in all ewes and blocked ovulation in two of the ewes as judged by the absence of corpora lutea at the time of laparotomy. One of the ewes showed an enlarged vulva and mammary development 6 weeks following cessation of the third series of injections. It is postulated that the elevated serum LH levels and blockage of estrus and ovulation are due to the ability of the anti-HCG to block the action of endogenous LH on its end organ, thus altering the secretion of the gonadal hormones.