The role of the estrous cycle in activity-based anorexia: A comparative study of sexual differences in rats

The present study evaluates the effects of the estrous cycle on activity-based anorexia by identifying the successive phases of the estrous cycle of female rats before, during, and after exposure to the experimental conditions. Activity-based anorexia is established when rats are exposed to a restricted-feeding schedule (1 hour) while having free access to a running wheel (23 hours). Under these conditions rats quickly lose bodyweight, reduce food consumption, and gradually increase their levels of activity on the running wheel. Recent data show that food restriction and the increase of activity interrupt the estrous cycle and that hormonal factors affect the activity level and food consumption of female rats during some phases of the estrous cycle. Results showed increased activity and greater weight loss in females compared to males though during feeding time there were no differences in food and water consumption. Males and females recovered their initial bodyweight after the procedure. Females showed anticipatory activity before eating and their estrous cycles were disturbed during the experimental phase.