Neuropeptide Y Acts at an Atypical Receptor to Evoke Cardiovascular Depression and to Inhibit Glutamate

Microinjection of neuropeptide V (NPY) into the nucleus tractus solitarius (NTS) induces an initial and reversible fall in arterial pressure (AP) and heart rate (HA), along with a delayed and long-lasting blockade of cardiovascular responses to L-glutamate (L-Glu) injected into the same site and an inhibition of the barorefiex arc. By injecting NPY-receptor subtype selective agonists and NPY-related peptides into NTS we have sought to characterize the receptors that mediate these responses. Unilateral injections into NTS (9-90 pmol) of NPY as well as the Yl receptor selective agonist [Pro]NPY and the Y2 receptor selective fragment NPY 1 3-36 evoked comparable dose-dependent falls of AP and HR in the anesthetized and paralyzed rat. Injections into NTS of peptide YY or pancreatic polypeptide had no effect. Preinjection of NPY, [Pro]NPY, NPY 1 3-36 (all at 90 pmol) as well a