Body weight gain after VMH lesions in adult female rats guanethidine-sympathectomized at birth.

The role of the sympathetic nervous system in body weight gain produced by lesions of the ventromedial nucleus of the hypothalamus (VMH) was studied in adult female rats that had been sympathectomized from birth for 3 weeks with daily injections of guanethidine (0.01 ml/g body weight) starting the second day after birth. Female littermates injected with 0.15 M NaCl served as controls. Body weight gain during the dynamic phase after the VMH lesion was the same in the sympathectomized and control groups of rats, whereas the treated rats gained weight at a slower rate than the controls in the static phase. The increase in food intake stimulated by the VMH lesion peaked sooner and remained elevated longer in the controls than in the experimental animals despite the similar increases in body weight gain. These results indicate that the sympathetic nervous system may play an important role in body weight gain during the static phase following a VMH lesion in adulthood.