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Mechanisms Regulating Male Sexual Behavior in the Rat: Role of
3a- and 3-Androstanediols’
ABSTRACT
To assess whether naturally occurring 5a-androstanediols (5a-androstane-3a,17-diol and 5-androstane-33,17[-diol) play
a role in the regulation of male sexual behavior in the rat, their capability to restore copulatory behavior in castrated animals
was evaluated. Androstanediols were chronically administered either alone or in combination with 50a-dihydrotestosterone (DHT)
or with estradiol-17 1 (E,). Animals treated with testosterone (T), DHT, E, and vehicle, either alone or in different combinations,
served as controls. The occurrence of mounting, intromission, and ejaculation as well as detailed parameters of copulatory be
havior were recorded twice per week for 3 weeks. At the end of treatments, the weights of sex accessory organs were also
recorded. When 3P,5a-androstanediol (3-diol; 500 g/day) was administered in combination with DHT (300 pg/day), full
copulatory behavior was restored in all subjects in a manner similar to that obtained with E, plus DHT or T plus DHT combi
nations, thus indicating an estrogen-like behavioral effect of 3[-diol. Administration of 3a,5a-androstanediol (3a-diol; 500 pg/
day) combined with DHT also restored sexual behavior, though to a lesser extent. When 3ca-diol (500 tig/day) was simulta
neously administered with E, (5 lig/day), the copulatory behavior of castrated animals was fully restored in a fashion similar to
that observed after administration of DHT plus E, and T plus E, combinations, indicating a potent androgen-like effect of 3a
diol. The behavioral effect of 3p-diol plus E, was significantly less potent. When given alone, each androstanediol only partially
restored copulatory behavior. Administration of 3a-diol either alone or combined with DHT or E, induced a significant increase
in ventral prostate and seminal vesicle weight, mimicking the effects of T and DHT, whereas 3P-diol had very little effect. The
results suggest that androstanediols may have a role as synergizing molecules in regulating male sexual behavior in rodents. The
data also provide a possible explanation for the behavioral effects of DHT when given at supraphysiological doses.
Mechanisms Regulating Male Sexual Behavior in the Rat Role Of 3a and 3bdiols.pdf (794 KB)