The
contraceptive effects of
quinestrol in Mongolian gerbils were examined. The results showed that
body weight significantly increased after
quinestrol treatment, except in the group that received the highest dose. The gonadosomatic index of ovaries decreased, whereas that of uteri increased, and uterine
edema appeared after
quinestrol treatment. Histological examination revealed that the ovaries had a lack of mature follicles and corpora lutea and that the myometrium and endometrium of the uteri became thin after
quinestrol treatment. Persistent estrous appeared after
quinestrol treatment, and time to persistent estrous shortened with increasing doses of
quinestrol. Serum
follicle-stimulating hormone (FSH) and
luteinizing hormone (LH) levels decreased, whereas
estradiol (E2) and
progesterone (P4) levels increased after
quinestrol treatment, and the effects were dose-dependent. During gestation, the serum E2 levels in the different treatment groups were not significantly different. During gestation in the control groups, the serum P4 levels from days 0 to 15 were higher than in the
quinestrol-treated groups; however, they did not show significant differences from days 18 to 24. Doses of 0.1 to 2.7 µg/g
quinestrol over 6 days completely inhibited fertility. Birth time was prolonged with increasing doses of
quinestrol. The findings suggest that
quinestrol has marked
estrogenic effects in Mongolian gerbils and may inhibit follicle maturation and ovulation through lowered
gonadotropin levels. Uterine
edema and abnormal E2 and P4 levels during gestation are important causes of pregnancy failure in
quinestrol-treated Mongolian gerbils.
Quinestrol causes prolonged inhibition of fertility in Mongolian gerbils.