Effects of chronic intermittent immobilization stress on rat testicular androgenic function.

In rats, chronic intermittent immobilization stress induced a drastic fall in the plasma concentration and testicular content of testosterone (T) without detectable changes in plasma LH values. In vitro basal T production by interstitial cell-enriched preparations from stressed rats and the responses to hCG, dibutyryl cAMP, or choleratoxin were suppressed, while cAMP production was not modified. The increase in plasma T concentrations in control animals was identical after the in vivo injection of 5, 10, or 50 IU hCG, while stressed rats failed to respond to 5 IU, but showed a response similar to that of control animals with 10 and 50 IU. These results suggest that chronic intermittent immobilization stress decreases Leydig cell sensitivity to gonadotropins.