PERIPHERAL AND CENTRAL ANDROGENIC STIMULATION OF SEXUAL BEHAVIOUR OF CASTRATED MALE RATS

Abstract

The effects of androgens on the maintenance and restoration of sexual behavior (mounts, intromissions and ejaculations) of castrated male rats were studied. In the maintenance study the rats were treated for 5 wk, starting 1 day following castration. Testosterone propionate maintained sexual behavior at an almost normal level. The androgen-estrogen intermediate 19-hydroxytestosterone propionate was unable to prevent the decline in the number of ejaculations over the weeks, although this hormone maintained the post-ejaculatory refractory period in those rats that ejaculated and maintained normal sexual latencies. In the restoration study administration of testosterone propionate for 7 wk to long-term castrated rats restored sexual behavior to normal. 19-Hydroxytestosterone propionate treated rats displayed mounts but no other signs of sexual behavior. The 5.alpha.-reduced androgen dihydrotestosterone propionate did not restore sexual behavior. Testosterone propionate and dihydrotestosterone propionate stimulated peripheral target organs; 19-hydroxytestosterone propionate was ineffective in this respect. It has been suggested that testosterone might stimulate sexual behavior in rats in 2 ways, i.e., via its aromatization to estradiol in the brain, and by stimulating growth of peripheral tissues via its 5.alpha.-reduction to dihydrotestosterone. In support for this view the combination of 19-hydroxytestosterone propionate and dihydrotestosterone propionate was effective in restoring the full pattern of sexual behavior in castrated male rats.