A comparison of corticoadrenal and gonadal responses to acute immobilization stress in rats and mice.

The effect of different periods of acute immobilization stress on circulating corticosterone and testosterone was studied in adult male rats and mice. Although initial corticoadrenal response to immobilization was similar in both species, this differed after a more prolonged exposure to the stress stimulus. This suggests that behavioral adaptation to long-lasting stimulation and/or effectiveness of corticosterone feedback on the hypothalamus-pituitary-adrenal axis could be different in those species. An inhibition of testosterone secretion after 5 hr of immobilization was observed in both rats and mice. However, mice seem to be more sensitive to stress-induced inhibition of testosterone secretion than rats. No evidence for a biphasic testosterone response to stress was found.