Investigating the effect of parental pre-gestational stress on ethological parameters in male rat offspring

Abstract

Chronic stress before pregnancy delays some of the physiological and neurological development and increases the risk of physical and behavioral disorders in offspring later in life. While the effects of maternal stress during pregnancy have been widely studied in humans and rodents, far less is known regarding the effects of each parent's pre-pregnancy stress on behavioral consequences of the offspring. In the present study 36 adult Wistar rats (24 females and 12 males) were divided to control and stress groups. In stress groups, female and male rats were subjected to predatory stress (exposed to cat twice a day, 1h per session) for 15 and 50 consecutive days, respectively. After the stress procedure, the stressed and control rats were mated to create 4 groups of breeding pairs: control male/control female, stressed female/control male, control female/stressed male, and stressed male/stressed female. On postnatal days 30-31, the offspring underwent testing on the elevated plus maze (EPM) for evaluating fear and exploratory behaviors, and a blood sample was taken to measure their plasma corticosterone concentration. Before EPM test, half of the pups of each group were exposed to acute predatory stress. The results indicated that the disparity in corticosterone levels, fear and exploratory behaviors between offspring exposed to acute stress and their non-acute stressed counterparts was more pronounced in the groups with maternal or paternal stress, whereas the difference was minimal in the control groups unexposed to pre-gestational stress. The combined effect of maternal and paternal stressors produced non-additive effects on corticosterone, fear and exploratory responses. These findings suggest that pre-gestational stress can exacerbate the effect of acute stress on offspring ethological parameters and that exposure to stressful environmental conditions prior to pregnancy can exert important effects on offspring brain development and lead to permanent alterations with long-lasting consequences on the physiology and behavior of the offspring later in life.