Effects of neuropeptide Y on appetite.

Neuropeptide Y (NPY) is a polypeptide containing 36 amino acids. Circulating NPY originates predominantly from the sympatho-adrenomedullary nervous system. It has a vasoconstrictive and mitogenic effect on blood vessels and seems to be involved in blood pressure regulation and angiogenesis. NPY is a potent orexigenic agent and is presumed to play a leading role in the regulation of eating behavior. Stimulation of the NPY-ergic arcuate - paraventricular nucleus (ARC-PVN) pathway by exercise, fasting, energy loss (glucosuria) is followed by increased appetite and food intake and increased parasympathetic activity, but suppression of sympathetic activity and energy expenditure. The end result of this process is an increase of energy stores. Activity of the NPY-ergic ARC-PVN pathway is suppressed by leptin - a polypeptide produced by adipocytes. Although functioning of an NPY-leptin feedback was found in rodents, it seems likely that also in man the NPY-leptin axis is involved in the regulation of food intake and energy expenditure.