Neuropeptide Y (NPY), a neuropeptide, plays roles in regulating appetite, vasoconstriction, cardiac contractility, and intestinal secretion, acting as an agonist for NPY receptors Y1, Y2, and Y5. Expressed ubiquitously, NPY modulates cellular responses by selectively inhibiting forskolin-induced cAMP accumulation in L-M(TK-) cells expressing rat Y1 or Y2 and in HEK293 cells expressing rat Y5, more so than in cells expressing rat Y4 receptors (EC50s = 0.15, 2.7, 0.66, and >1,000 nM, respectively). Additionally, it elevates perfusion pressure in isolated guinea pig hearts (EC30 = 1.3 nM) and, when administered intracerebroventricularly at 300 pmol/animal, it notably increases food intake in rats.