醋酸棉酚对雌性大鼠的抗早孕作用

大鼠于妊娠第6～9天,喂以醋酸棉酚80 mg/kg/d, 有明显的抗早孕作用。皮下注射孕酮5 mg/d或hCG 25 IU/d可拮抗醋酸棉酚的抗早孕作用。醋酸棉酚80 mg/kg/d对去卵巢后给以外源性雌酮和孕酮以维持妊娠的大鼠无抗早孕作用。正常妊娠大鼠,给醋酸棉酚后,血清孕酮水平下降,妊娠中止,若同时注射hCG,孕酮水平回升接近对照动物的水平,药物抗早孕作用消失,但仍低于单给hCG组大鼠血清孕酮水平,说明醋酸棉酚可阻断hCG促黄体分泌孕酮的作用,这可能是醋酸棉酚抗早孕作用的主要机理之一。

EFFECT OF GOSSYPOL ACETIC ACID ON EARLY PREGNANCY IN RATS

Administration of gossypol acetic acid 80 mg/kg/day to rats on day 6～9 of gestation terminated early pregnancy. Progesterone 5 mg/day or hCG 25 IU/day was shown to block the antifertility effect of gossypol treatment.Rats ovariectomized on day 6 of pregnancy were injected daily with progesterone 10 mg/day and 1 μg/day until day 15. The fetuses were found to be alive on day 16 of gestation. When gossypol acetic acid 80 mg/kg/day was given to these rats, no antifertility effect was observed.Serum progesterone level of rats treated with gossypol acetic acid alone was found to be markedly lower than that of control animals. Intact rats were injected subcutaneously hCG with or without gossypol acetic acid on day 6～9 of gestation. Steroidogenic response of rat ovary to hCG was inhibited by gossypol acetic acid. It is postulated that the blockade of gonadotrophic effect of hCG may be the chief mechanism by which gossypol acetic acid interrupts early pregnancy in female rats.