Effect of 3, 6-Dimethylpyrazine-2-thiol on Androstenedione-Induced Increase of Uterine Weight in Female Rats

3, 6-Dimethylpyrazine-2-thiol administered at 10-70 mg/kg, p.o. was found to suppress androstenedione-in-duced increase of uterine weight in female rats. This action was weaker than that of aminoglutethimide (3-30 mg/kg, p.o.). After administration of androstenedione, increased plasma estradiol levels were reduced by 3, 6-dimethylpyrazine-2-thiol. Moreover, in vitro, production of estradiol in the pregnant mare serum gonadotropin (PMSG)-treated ovary was inhibited by 3, 6-dimethylpyrazine-2-thiol. These results suggest that 3, 6-dimethylpyrazine-2-thiol has an inhibitory action on aromatase activity.