THE EFFECTS OF CENTRAL ADMINISTRATION OF NEUROPEPTIDE-Y ON BEHAVIOR, NEUROTRANSMITTER, AND IMMUNE FUNCTIONS IN THE OLFACTORY BULBECTOMIZED RAT MODEL OF DEPRESSION

The effects of subchronicly administered neuropeptide Y (NPY) intracer ebroventricularly on behavioral, neurochemical, and immunological para meters were examined in sham operated and olfactory bulbectomized (OB) rats. In the untreated OB rats, an increase in ambulation, rearing, g rooming, and defecation scores was found in the novel stressful enviro nment of an ''open field.'' Following 7 days of NPY administration, th ese behaviors were largely attenuated. In the elevated plus-maze appar atus, OB rats showed an increase in the number of entries into the ope n arms and time spent on the open arms compared with sham operated ani mals; NPY had no significant effect on the behavior of either sham ope rated or OB animals in this test. A decrease in the NA concentration w as found in the amygdloid cortex of OB rats. NPY infusion significantl y increased the NA concentration in amygdala, reduced 5-HIAA but incre ased 5-HT concentrations in the hypothalamus, and increased the dopami ne level in the hippocampus. NPY administration also reversed the supp ression of lymphocyte proliferation in the OB rat. However, the change s in the differential white blood cell count and the elevated phytohem agglutinin-induced chemiluminescence of mononuclear cells in the OB we re not altered by NPY. These results suggest that NPY may have a modul atory effect on some behavioral, neurotransmitter, and immune aspects of the OB rat model of depression. (C) 1996 Academic Press, Inc.