Inhibition of ovulation in immature mice by thioproline

Thioproline 30 or 40 mg/kg ip to the immature mice after sc PMSG 36, 48, 56 h inhibited significantly the ovulation induced by hCG. During the early stage of preovulatory period (5—5.5 h after hCG), the plasma progesterone concentration and the affinity of LH/hCG receptors were reduced, but the number of receptors were not significantly decreased. When thioproline was ip simultaneously with a proper dosage of progesterone, the inhibition of ovulation would be released markedly. These results suggest that the antiovulatory effect of thioproline in immature mice is its inhibition of the ovarian LH/hCG receptor function and progesterone production during the course of preovulatory period.