Effects of testosterone on behavior in monkeys
The behavioral thresholds of testosterone in castrated male rhesus monkeys (Macaca mulatta).
Michaelet al., Hormones & Behavior 18(161-176) 1984.
| To determine the lowest doses of testosterone propionate (TP) that cause clearcut behavioral changes in castrated male rhesus monkeys, observations were made on 8 males during successive 4-wk treatment periods while they received daily doses of TP (25 mug to 12.8 mg, sc). Ss were tested with each of the same 4 ovariectomized females. Two females were untreated and the other 2 received stradiol or benzoate (5 or 15 mug/day, sc). Individual Ss had widely different thresholds. Ss showed (1) a graded increase in ejaculatory activity as plasma testosterone values increased, and (2) in which there were no further increases in ejaculation with increasing plasma levels once the behavioral threshold had been reached. At levels below physiological range, small changes in plasma testosterone were associated with marked changes in behavior. The female partner exerted a pronounced effect on the responses of males to TP treatment. |
Michael, et al., Physiology & Behavior. 36: 349-355, 1986.
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Observed
4 castrated male cynomolgus monkeys during successive 4-wk treatment
periods while they received 25, 50, 100, 200, 400, and 800 mug/day
subcutaneous administrations of either testosterone proprionate
(TP) or dihydrotestosterone proprionate (DHTP) in counterbalanced
order. Males were tested with each of the same 4 female partners
(16 pairs, 1,024 1-hr behavior tests). Results indicate that physiological
plasma levels of testosterone resulted from the 200 mug and 400
mug TP treatments and were associated with significantly increased
ejaculatory behavior. Physiological plasma levels of dihydrotestosterone
resulted from the 50 mug and 100 mug DHTP treatments, but there
were no changes in ejaculatory behavior over the entire DHTP dose
range used (25-800mg). |