Parents' adulthood stress induces behavioral and hormonal alterations in male rat offspring

Exposure to stress can influence hypothalamo-pituitary-adrenal (HPA) axis in mammals and impair their behavioral/hormonal development. Stress during fetal or early life may have wide range effects on the offspring phenotype in rodents. Since the role of parents' adulthood stress before mating is not fully understood yet, we investigated the effects of parents' adulthood stress on behavioral and hormonal parameters in 10- and 30-day-old male offspring. To induce stress in the adult male and female rats, a repeated forced swimming paradigm was employed daily over the course of 21 days. Then, they were categorized into four parental breeding groups: stressed parents (SP), stressed mother (SM), stressed father (SF) and non-stressed parents (NSP). Anxiety-like behavior was tested in adult rats and 30-day-old male pups, using the elevated plus maze (EPM). The level of serum corticosterone was measured by ELISA in all groups. Stressed adult rats showed enhanced serum corticosterone concentration and anxiety-like behavior. Serum corticosterone level of the 10- and 30-day-old pups of the SP, SM and SF groups was significantly higher than pups from the non-stressed group. Furthermore, 30-day-old pups of the SP, SM and SF groups had lower time spent in the open arms compared to the control group, but stress had no significant effects on the percent of entries into the open arms. In addition, serum corticosterone level in 30-day-old pups were raised by a stressed mother was markedly more than 10-day-old pups. These findings revealed that parents' adulthood stress have negative impacts on behavioral and hormonal responses of their male offspring.