Maternal programming of sexual attractivity in female Long Evans rats.

In mammals, maternal care influences the developing offspring across multiple domains. In Long Evans rats, for example, the quality of maternal care received as a pup influences later cognitive function, neuroendocrine responses to stress and behavioral measures of emotionality. Data from humans, non-human primates, and rodents also suggest that early life events may similarly perturb measures of sexual reproduction, with possible consequences for reproductive fitness. The current study examined whether or not male conspecifics differentially prefer females, as adult mating partners, that were reared under varying maternal conditions (assessed via the quantity of licking and grooming received; LG). Additionally, the impact of maternal care on adult female sexual motivation and behavior were quantified to determine if these behavioral characteristics are associated with any preference observed. In a mate preference task, male rats chose, almost exclusively, to mount, copulate and ejaculate with female rats reared under Low LG conditions. Under non-paced mating conditions, female Low LG rats display significantly more paracopulatory and copulatory behaviors compared to High LG rats. Due to its critical role in female paracopulatory behavior, progesterone receptor immunoreactivity (PR-ir) in the ventromedial nucleus of the hypothalamus (VMH) was also assessed in both groups of female rats. Estradiol induced PR-ir in the VMH was significantly higher in Low LG relative to High LG rats. Together, these data suggests that early life parental care may developmentally program aspects of behavior and physiology that subsequently influence sexual attractivity and behavior in adult females.