The effects of running activity on the reproductive axes of rodents

Sexual attractiveness of male chemicals and vocalizations in mice

Male-female interaction is important for finding a suitable mating partner and for ensuring reproductive success. Male sexual signals such as pheromones transmit information and social and sexual status to females, and exert powerful effects on the mate preference and reproductive biology of females. Likewise, male vocalizations are attractive to females and enhance reproductive function in many animals. Interestingly, females' preference for male pheromones and vocalizations is associated with their genetic background, to avoid inbreeding. Moreover, based on acoustic cues, olfactory signals have significant effects on mate choice in mice, suggesting mate choice involves multisensory integration. In this review, we synopsize the effects of both olfactory and auditory cues on female behavior and neuroendocrine functions. We also discuss how these male signals are integrated and processed in the brain to regulate behavior and reproductive function.

Photoperiodic responses of four wild-trapped desert rodent species

The purpose of this study was to examine the effect of the photoperiod on reproductive status and body and lipid masses in four Egyptian desert rodent species (Dipodillus dasyurus, Acomys cahirinus, Gerbillus andersoni, and Gerbillus pyramidum). Adult males and females were housed in long days for 11 wk. At that time, one-half of the animals were killed and the remaining animals were moved to short days (SDs) for 11 wk. Some individuals of Gerbillus andersoni and Gerbillus pyramidum had access to running wheels. Testes index and spermatogenesis, but not testis mass, were decreased in all species in SDs. In contrast, SDs did not affect female reproductive status in all species. Exercise stimulated spermatogenesis but did not affect female reproductive status. SDs increased body and lipid masses in male Acomys cahirinus, but not in other species. Collectively, these desert rodent species were responsive to day length changes, but these changes alone did not induce robust alterations in reproductive status and body and lipid masses.

Running-induced testicular recrudescence in the meadow vole: role of the circadian system

Access to running wheels stimulates testicular recrudescence in meadow voles whose reproductive axes have been suppressed by short day lengths. The present experiments addressed the mechanism by which running stimulates the reproductive system. The results from two experiments suggest that running acts specifically to override the short day length suppression of the gonads: access to running wheels had no stimulatory effect on the testes of meadow voles housed in long day lengths, and the degree to which running stimulated the testes of meadow voles housed under short day lengths was significantly correlated with the degree to which the voles were reproductively photoresponsive. A third experiment queried whether running shifts the circadian clock in such a way as to cause an overlap between the short day length photoperiod and the period of sensitivity to light. This proved not to be the case: access to running wheels stimulated testicular recrudescence in meadow voles housed in constant darkness. Two experiments demonstrated that access to a running wheel did not alter short day length profiles of pineal melatonin content or the nocturnal rise in pineal melatonin content in the absence of light. Finally, daily patterns of circulating corticosterone levels did differ between voles with and without access to running wheels, although the difference could not be attributed to differences in the circadian system. Overall, these experiments suggest that running stimulates gonadal recrudescence by acting on the pathway by which photoperiod suppresses reproduction downstream of melatonin production.