Environmental cues evoke differential responses in pituitary-testicular function in deer mice.

Abstract

Pituitary-testicular function was assessed in deer mice (Peromyscus maniculatus bairdii) after exposure to external cues predicting seasonal climatic changes. Mice were exposed to either a 14-h light, 10-h dark cycle (L:D;14:10) or L:D;10:14 at 0, 23, or 32 C for 80–90 days. Spermatogenic arrest occurred in about one fourth of the mice exposed to short photoperiods at 23 C. Exposure to L:D;10:14 at 0 C significantly (P < 0.05) enhanced the proportion of mice with atrophic testes over that induced at 23 C. In contrast, L:D;14:10 at 0 C failed to affect gonadal function. Modest to severe testicular dysfunction was evident in at least 80% of mice exposed to 32 C at either L:D;14:10 or L:D;10:14. Certain mice (∼20%), however, failed to undergo testicular regression even after exposure to L:D;10:14 at 0, 23, or 32 C. Graded restrictions in food intake, over 4 weeks, triggered testicular atrophy in about 70% of the males whose gonads failed to regress after provocative exposure to photic and thermal cues. Testi...