Short photoperiods affect male hamster sociosexual behaviors in the presence and absence of testosterone.

Male hamsters were exposed to long (LD 14:10) or short (LD 8:16) photoperiods (LP; SP) to evaluate the effects of these environmental conditions on sociosexual behaviors. In Experiment 1, gonadally intact males in SP exhibited deficits in sexual behavior, reflected both in performance as well as initiation measures. Some aspects of the males' chemoinvestigation of females or their odors were also significantly different between LP and SP hamsters. In Experiment 2, castration resulted in the development of copulatory impairments, but they occurred more rapidly among males in SP conditions. Subsequent testosterone (T) replacement restored mounts, intromissions and ejaculations on tests given 2 and 4 weeks after T, but this happened more quickly in the LP group. SP males were still slower than LP males to initiate mounts and intromissions on their second test. These influences of photoperiod are discussed in the context of steroid-independent and steroid-dependent effects on behavior and the role of impaired processing of chemosensory information is evaluated.