Hypothalamic paraventricular nucleus lesions produce overeating and obesity in the rat

Abstract

It has recently been demonstrated that chronic noradrenergic stimulation of the hypothalamic paraventricular nucleus (PVN) or wire knife cuts in the vicinity of the PVN cause hyperphagia and increased body weight. The present study investigates in rats the impact of electrolytic lesions within and around the PVN, on food intake, water intake, and daily body weight gain. Small lesions essentially restricted to the PVN are found to produce overeating and increased body weight, in both female and male rats maintained on either lab chow pellets or high fat mash. This effect appears to be strongest with lesions which damage the caudal aspect of the PVN. Destruction of tissue dorsal, ventral, or rostral to the PVN has no effect, or a suppressive effect, on food intake and body weight. With one exception, larger lesions, which extend beyond the borders of the nucleus, produce no greater response than lesions restricted to the PVN. The exception is a very large lesion which simultaneously damages the PVN and the ventromedial hypothalamic region (in the vicinity of the ventromedial nucleus) and which is somewhat more effective than PVN lesions in causing hyperphagia and obesity.