Short- and long-periods of neonatal maternal separation differentially affect anxiety and feeding in adult rats: gender-dependent effects

Abstract

Environmental manipulations during early development can induce permanent alterations in hypothalamic-pituitary-adrenal (HPA) and behavioral responses to stressors. However, little is known about the impact of early life experiences on appetitive responses. The present investigation assessed the effects of brief handling/separation or protracted separation from the dams, on feeding and anxiety responses during development. During the first 3 weeks post-partum, Sprague–Dawley rat pups were exposed daily to either brief (15 min) handling/isolation (H), a more protracted (3 h) period of maternal separation (MS), or were not handled (NH). When tested on the elevated plus-maze (at 5–6 weeks) H groups displayed less anxiety than NH gender-matched controls. Surprisingly, so did the MS females. At weaning (Day 22), the MS rats weighed significantly less than both the H and NH animals; the difference between the H and MS was more robust and persisted throughout the experiment (D 62). The H animals of both genders, and the females of the MS group, consumed more of the palatable `snack' than their NH counterparts. The feeding suppressant response to the various satiety peptides (bombesin, cholecystokinin, and amylin) was not affected by the early life experience, with exception of cholecystokinin (CCK) effects, which were more pronounced in H and MS males. These results suggest that early life events may contribute to anxiety and/or ingestive disorders such as anorexia nervosa, bulimia and obesity.