Bilateral lesions of the SCN abolish lipolytic and hyperphagic responses to 2DG

The effects of intracranial injection of 2-deoxy-D-glucose (2DG) on the plasma free fatty acid (FFA) concentration and food intake in the light (11:00 hr) and dark (23:00 hr) period were examined in male Wistar rats under a 12-hr light (08:00-20:00) and 12-hr dark (20:00-08:00) cycle. In sham-operated rats 2DG injection induced increase in plasma FFA concentration and in food intake in the light period, but not in the dark period. Bilateral lesions of the suprachiasmatic nucleus (SCN) resulted in complete loss of the lipolytic and feeding responses to 2DG in the light period. From these findings it is concluded that the lipolytic and feeding responses to 2DG are photoperiodic and that the SCN is involved in these phenomena.