Opposite effects on feeding of suprachiasmatic nucleus neuropeptide Y administration in rats

The effects of injecting or infusing neuropeptide Y (NPY) into the suprachi asmatic nucleus of rats on patterns of individual macronutrient and water i ntake were examined during the following 2 h and also across 12 and 24 h li ght/dark cycles. Increased total energy intake (218 and 170%) and energy in take from the dextrin/sucrose diet (499 and 247%) were observed in the 2 h following injection of 100 pmol NPY at early light and early dark, respecti vely, and in the following 24 h (total energy: 67%, dextrin/sucrose: 73%). Nocturnal casein energy intake was also increased (258%) following NPY inje ction. Continuous infusion of 10 pmol/h of NPY suppressed nocturnal total e nergy (36%) and dextrin/sucrose intake (36%) as well as 24 h energy intake from casein (43%). These results demonstrate divergent effects of NPY subse quent to different mode of administration. (C) 1999 Elsevier Science Inc. A ll rights reserved.