Testosterone-induced copulatory behavior is affected by the postcastration interval.
A well entrenched hypothesis regarding hormonal action is that as the time interval following hormonal deprivation increases there is a corresponding decrease in the sensitivity of the system to the effects of hormone replacement. With this in mind, we examined the effects of a prolonged period of hormonal deprivation (9 mo), and compared these to the effects of a shorter period (1 month), on the restoration of copulatory behavior and seminal vesicle weights. Castration of sexually vigorous male Long-Evans rats at 6 mo of age was followed by the virtual disappearance of ejaculatory behavior within 1 mo. Testosterone (T) was administered (5 mm or 20 mm T-containing Silastic capsules) either 1 or 9 mo after castration, and copulatory tests were conducted 3, 7, 10, 14, and 17 days later. 5 mmT and 20 mmT were equally effective in restoring behavior in the rats treated 1 mo after castration. In contrast, 5 mmT was more effective in inducing copulatory behavior than 20 mmT in the rats treated 9 mo after castration. The time course to maximal effect was longer in the rats given T 9 mo after castration. Rats were sacrificed 21 days after T administration. Expressed seminal vesicle weights and plasma testosterone were increased in a dose-dependent manner independent of the postcastration interval. These data indicate that somatic and behavioral effects of T are differentially modified by the period of preceding hormonal deprivation.
Clark
J T
JT
Department of Physiology, Meharry Medical College, Nashville, TN 37208, USA.
Micevych
P E
PE
Panossian
V
V
Keaton
A K
AK
D000375:Aging / Q000502:physiology; D000818:Animals; D003307:Copulation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D004542:Ejaculation / Q000187:drug effects; D005260:Female; D008297:Male; D009919:Orchiectomy; D051381:Rats; D012669:Seminal Vesicles / Q000187:drug effects / Q000254:growth & development; D012746:Sexual Abstinence; D013739:Testosterone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D013997:Time Factors
D004343:Drug Implants; D013739:Testosterone