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-induced 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.