BRAIN NPY Y-1 RECEPTORS RAPIDLY MEDIATE THE BEHAVIORAL-RESPONSE TO NOVELTY AND A COMPARTMENT-SPECIFIC MODULATION OF GRANULOCYTE FUNCTION INBLOOD AND SPLEEN

Neuropeptide Y (NPY) alters behavioral activity and innate immune func tions of rats within minutes of intracerebroventricular (i.c.v.) appli cation. Using combinations of the Y-1-5a,Y-b(6) agonist NPY, the Y-1,Y -3,Y-5 agonist [Leu(31)-Pro(34)]NPY (LP-NPY), and the selective Y, ant agonist BIBP3226 (BIBP), we investigated whether the NPY-Y-1 receptor (Y1R) subtype regulates NPY-induced behavioral and immunological effec ts at 15 min after i.c.v, application. Administration of both NPY and LP-NPY decreased rearing activity in the open field and suppressed gra nulocyte function in the blood. These effects were blocked by BIBP pre -treatment. In contrast to the blood, NPY and BIBP + NPY treatments st imulated granulocyte function within the splenic compartment. In addit ion, a blood leukophilia composed of granulocytes and NK cells was ind uced by NPY only. We conclude that the tested early effects of NPY are mediated by either the Y1R (rearing, blood granulocyte function), or a non-Y1R (splenic granulocyte function), or by a combined receptor ac tivation (leukocyte mobilization). Furthermore, the immunological effe cts of NPY demonstrate compartment specificity. (C) 1998 Elsevier Scie nce B.V. All rights reserved.