Centrally injected neuropeptide Y (13-36) produces vasopressor effects and antagonizes the vasodepressor action of neuropeptide Y (1-36) in the awake male rat

Intraventricular injections of the Y2 neuropeptide Y (NPY) receptor agonist porcine NPY (13-36) (pNPY (13-36); 25-3000 pmol) produced a dose-dependent increase (up to 14%; ED50 value of 0.3 nmol for overall effects and 0.97 nmol for the peak effects) in mean arterial blood pressure in the awake, unrestrained male rat without affecting heart rate. Furthermore, a subthreshold dose of pNPY (13-36) (25 pmol) counteracted the vasodepressor action of the parent compound pNPY (1-36) (75 pmol), which also acts at NPY receptors of the Y1 type. These results suggest that NPY receptors of the Y1 and Y2 type have opposing actions in central cardiovascular regulation.