Androgen control of male sex behavior in the crested newt (Triturus cristatus carnifex Laur.): castration and sex steroid administration.

Castration significantly lowers serum testosterone in sexually active male Triturus cristatus. Replacement therapy by implants of testosterone in silastic capsules elevates the serum testosterone level to higher values than normal. Sex behavior is depressed by castration and partially reinstated by replacement therapy with testosterone. 5 alpha-dihydrotestosterone was the only testosterone metabolite showing some behavioral effectiveness in castrates; estradiol and 5 beta-dihydrotestosterone failed to elicit sex behavior.