COMPARISON OF PROTEIN ANABOLIC PROPERTY OF VARIOUS ANDROGENS IN THE CASTRATED RAT

Abstract

The injn. of androgens into adult castrated rats in body wt. and nitrogen equilibrium produces an immediate decrease in N excretion which is maintained at the new level (Maximum N retained per day) for several days and then gradually returns toward the pre-injn. level. If the injns. are further prolonged, a slight negative N balance occurs. On cessation of injns., a negative N balance occurs for several days followed by a return to equilibrium and then a period of slight positive N balance. The changes in N excretion are paralleled by similar changes in urea excretion. The fecal N excretion is not altered. The body wt. is increased by the androgen for 10-14 days, then gradually ceases to increase and with further injns. actually decreases. On cessation of injns. a further decrease in body wt. followed by a gradual and small increase, results. Calculation of the theoretical increase in body wt. from the N retained indicates that the observed value at "high" doses of steroid is not sufficient to account for the N retained, thus suggesting a concomitant loss in another constituent (fat?) of the body. The max. N retained per day, as well as the total N retained, and the max. increase in observed body wt., are related to the dose and efficacy of the steroids. Compounds at several dose levels have been compared with respect to these criteria and the following sequence of potency was noted: testosterone propionate > testosterone >17-methyltestosterone > androstanol-17[alpha] -one-3>androstanediol-3[alpha],17[alpha] > [DELTA]4-androstenedione-3,17> androstanedione-3,17 > androsterone acetate. In single expts. 17-methylandrostanediol-3 alpha,17 alpha and androstanediol-3 alpha 17 alpha acetate-3 demonstrated protein anabolic properties. When testosterone, androstanediol-3 alpha 17 alpha, androstanol-17 alpha one-3 and androsterone were implanted as pellets, their potency was greatly increased. There was no noteworthy qualitative or quantitative difference between the Wistar and Holtzman strains of rats in responses to the steroids.