Effects of early maternal separation on subsequent reproductive and behavioral outcomes in male rats.

To investigate effects of maternal separation on reproductive and behavioral outcomes, male Wistar rats were separated from their mothers daily for 3 hr (maternal separation; MS) or 0 hr (control) from postnatal day (PND) 1 to 14. Timing of puberty, reproductive parameters, hormone levels, and aggressive behaviors in juvenile and adult rats were examined. Contrary to expectations, there was no effect of maternal separation on any measure of aggression. However, maternal separation altered peripubertal testosterone secretion and increased mean day of preputial separation. In addition, adult MS males demonstrated less total sexual behavior. There was no difference in sperm counts or testosterone levels at necropsy on PND 56 or in adulthood, but seminal vesicle weights were increased in adult MS rats. These results suggest that early life stress may influence hypothalamic-pituitary-gonadal axis development in males, at least during peripuberty.