Mesencephalic lesions followed by normophagia but decreased body weight.

Twenty mature male Sprague-Dawley rats were lesioned in the area of the ascending ventral noradrenergic bundle in the mesencephalon. Nine sham-operated animals served as controls. Food intake between the lesioned and nonlesioned groups was not significantly different except for the first day post surgery. However, body weight of the lesioned group was significantly below that of the controls when measured 15 days after the operation. The lesioned animals weighed significantly less than the controls throughout the rest of the experiment. They also were hypoactive when compared to the sham-operated rats. Control rats and lesioned rats did not differ significantly in deep rectal temperature. It is suggested that the significant decrease in body weight of the lesioned rats in the presence of normophagia may be caused by alterations in the animal's metabolism.