Augmentation of the Effects of Testosterone Propionate by Cortisol in Immature Male Rats

The androgenic activity of testosterone propionate, as measured by its ability to increase the weight of seminal vesicles and ventral prostate of castrated immature rats, is significantly augmented by the simultaneous administration of cortisol. Varying doses of cortisol were employed, the effect being most pronounced in the higher dose levels. The 2 highest doses of cortisol administered alone produced a significant increase in the seminal vesicle weight. However, it was determined that the effect observed with the simultaneous administration of both cortisol and testosterone propionate was greater than an additive effect of the 2 steroids administered alone. The mechanism by which cortisol achieves this augmentation is unknown. It may be the result of competition between cortisol and testosterone for binding sites in certain tissues resulting in an increased unbound androgen available for physiologic action in the target organs. (Endocrinology83: 387, 1968)