Lesion of central nucleus of amygdala promotes fat gain without preventing effect of exercise on energy balance

Abstract

Male Wistar rats with intact or lesioned central nucleus of amygdala (CeA) were kept at rest or subjected to a treadmill running program for 21 consecutive days. Food intake and body weight were monitored throughout the exercise training program. At the end of the program, rats were killed and their carcasses processed for analysis of the contents in energy, fat, and protein. Exercise and CeA lesions induced opposite effects on energy balance; exercise delayed gains in body energy and fat, whereas CeA lesions promoted them. Total energy intake was lower in exercised rats than in sedentary ones over the 12 and 24 h that followed exercise. Food intake was higher in lesioned rats than in intact animals over the second half of the 12-h period that followed exercise. There was no interaction effect of exercise and CeA lesions on energy balance and intake and on body composition. Plasma levels of adrenocorticotropin hormone and corticosterone were higher in exercised rats than in sedentary ones, but there was no difference between lesioned and intact rats. This study, as well as confirming the effect of exercise on energy balance, indicates that CeA lesions may promote energy deposition in rats. Above all the present results provide evidence that CeA does not represent a necessary neuroanatomic structure in the effect of exercise on energy balance.