Dual effects of 2-deoxy-D-glucose on food intake in the rat: inhibition at night and stimulation in the day-time.

The effect of 2-deoxy-D-glucose on food intake in rats has been reexamined. The effects were compared following administration of 2-DG IP (250, 500, 750 mg/kg and saline) either at the beginning of a 12-hr dark or 12-hr light period. Ad lib food intake was recorded during the subsequent 24 hours. In the day-time 2-DG enhanced food intake. The increase was not dose-dependent. It was apparent only during the first four hours and was compensated during the following eight hours. At night, an inhibition in food intake was observed. This inhibition was mainly manifested during the first four hours and was not dose-dependent. However, a dose related compensation during the subsequent hours resulted in a dose-dependent inhibition of the nocturnal intake. A second expermient indicated that after an overnight fast 2-DG also inhibited the high food intake induced in the day-time. In a third experiment, insulin 10 IV SC combined to 2-DG was shown to further increase food intake in the day-time. At night the combined administration of insulin and 2-DG cancelled their respective opposite effects and no change of food consumption was observed. The results are interpreted in terms of the contrasted neuroendocrine and metabolic patterns prevailing in the two parts of the diurnal cycle.