Abstract

Steroids with little androgenic activity, such as 19-nortestosterone and 4-chloro-19-nortestosterone acetate (SKF 6611), as well as androgenic steroids such as testosterone propionate, methyltestosterone and androstenedione increased the activity of several enzymes in rat liver microsomes when given to adult female rats (20 mg/kg) on alternate days for 4 weeks. All of the steroids produced 2-to 3-fold increases in the activity of the enzyme systems that metabolize hexobarbital, demethylate monomethyl-4-aminoantipyrine and hydroxylate naphthalene, but only 19-nortestosterone, testosterone propionate and methyltestosterone, increased the activity of microsomal TPNH oxidase.

Treatment of castrated male rats with testosterone propionate or 19-nortestosterone ( 2 mg/kg on alternate days for 10 days) increased the weight of levator ani muscle as well as the rate of metabolism of hexobarbital and demethylation of monomethyl-4-aminoantipyrine about 2-fold. Although 19-nortestosterone nearly doubled the weight of the seminal vesicles, testosterone propionate caused a 14-fold increase. These findings suggest that the increase in microsomal enzyme activity is more closely related to the anabolic activity than to the androgenic activity of the steroid.