Early maternal separation increases symptoms of activity-based anorexia in male and female rats

Running activates the hypothalamic-pituitary-adrenal (HPA) axis, increasing the release of stress hormones known to exert anorexic effects. HPA axis reactivity is strongly influenced by early postnatal manipulations, including removal of pups from the dam for short (handling) or prolonged (maternal separation) durations during the preweaning period. The authors examined the effects of handling and maternal separation on food intake, body weight loss, and running rates of young adult male and female rats in the activity-based anorexia (ABA) paradigm. Postnatal treatment did not affect adaptation to a 1-hr restricted feeding schedule before the introduction of wheel running. During the ABA paradigm, maternally separated animals lost weight faster, ate less, ran more, and required fewer days to reach removal criterion compared with handled rats. Females were particularly vulnerable. These findings indicate that early postnatal treatment and sex influence ABA.