Sexual Behavior is Enhanced by Regular, Repeated Mating from Young Adulthood to Middle Age in Female Long-Evans Rats.

Abstract

Aging is associated neuroendocrine changes in women. Animals can be used to model these changes, as well as changes in reproductive behavior. The current study was designed to characterize mating behavior across age and assess the effects of age and sexual history on mating behavior. Sexual motivation was assessed using the partner-preference test, in which a female rat is given the choice to interact with a same-sex conspecific or a sexually-vigorous male rat, with which she can mate. Across repeated mating tests (2-12 months of age), female rats spent more time with the male, displayed more solicitation behaviors, were less likely to leave the male after mounts, but visited both stimulus animals less frequently. Comparing a separate group of age-matched, hormoneyoked female rats mated for the first time at 12 months of age to female rats mated for the first time at 2 months of age showed that the 12 month rats visited both stimulus animals less, were less likely to leave the male after mounts, took longer to return to the male after mounts, and displayed fewer solicitation behaviors than their younger counterparts. Relative to middle-aged female rats once they were sexually experienced, 12 month naïve rats spent less time with the male, were more likely to leave the male after mounts, and displayed fewer solicitation behaviors. Furthermore, 12 month naïve rats failed to discriminate between the stimulus animals, visiting both stimulus animals at the same rate unlike 2 month naïve or 12 month experienced rats. Taken together, these results suggest that aging affects some measures of sexual behavior, but most effects of age can be mitigated by regular, repeated mating.