[Testicular endocrine function in hamadryas baboons (Papio hamadryas) during chronic emotional stress]

Radioimmunoassay was applied to examine the time course of blood plasma testosterone content in 10 adult male hamadryas baboons under repeated immobilization stress (IS). In the first series of experiments, the monkeys (5) were subjected to daily IS for 2 h during 6 days. In the second series, 5 animals were exposed to 2-hour immobilization 3 days prior to the analogous stressful cycle. In response to intermittent IS the first series males demonstrated profound and long-term suppression of blood testosterone that persisted for 2 days after IS cessation. Preliminary application of a stressful stimulus substantially reduced the degree of blood testosterone suppression. Transitory decrease in blood testosterone was observed 2 hours after the outset of each stressful exposure, followed by complete recovery of testosterone blood level after 6 hours. The differences in the time course of testosterone indicate that the response of the pituitary-gonadal system is dependent on the regimen of stressful stimulus application.