Feeding responses of rats with dorsomedial hypothalamic lesions given ip 2DG or glucose

The glucoprivation effects of 2-deoxy-D-glucose (2DG) on feeding behavior were studied in rats with bilateral lesions of the dorsomedial hypothalamic nucleus (DMN) and sham-operated controls. The lesioned and sham-operated rats were injected intraperitoneally with 2DG (5% wt/vol) at doses of either 150 mg/kg, 300 mg/kg, or 500 mg/kg, or with saline ("control days"). At all doses significantly more sham-operated rats ate and showed an increased food consumption during the first few hours after 2DG injection when compared to saline control days. However, their 24-h food consumption was normal or less than normal, depending on the dose of 2DG. On the other hand, rats with DMN lesions (DMN-L) did not increase their food consumption during the 4 h after the injection at any of the 2DG doses. In a second experiment DMN-L and sham-operated controls were injected intraperitoneally with glucose (1.36 g/kg body wt or 2.72 g/kg body wt) or saline after an overnight fast. Glucose loads, compared to saline injections, significantly depressed the controls' food consumption only during the first hour of refeeding. On the other hand, glucose injections did not depress food intake of the DMN-L rats. It is suggested that DMN lesions may have either destroyed glucoreceptors in the DMN that monitor glucose or the glucoprivation effects caused by 2DG and/or glucoreceptive pathways that pass through the DMN.