In vitro effects of androgens upon the spontaneous rat uterine contractility

The effectiveness of ring A reduced (5 alpha and 5 beta) testosterone (T) derivatives upon the rat uterus spontaneous contractility was tested in vitro. Compounds with the 3 alpha-hydroxy-5 alpha reduced configuration, such as androsterone and androstanediol, and one 5 beta reduced (5 beta-dihydrotestosterone) elicited a remarkable inhibitory effect upon the myometrial activity. Although steroids with 5 beta reduction were less potent than 3 alpha-hydroxy-5 alpha reduced compounds for depressing the myometrial activity, they were somewhat more potent than T, DHEA, androstenedione and the remaining 5 alpha reduced compounds tested. Therefore, T could act as a "prehormone", accounting for the maintenance of the physiological myometrial activity through its 5-reduced derivatives.