HYPOTHALAMIC CONCENTRATION AND RELEASE OF NEUROPEPTIDE-Y INTO MICRODIALYSATES IS REDUCED IN ANORECTIC TUMOR-BEARING RATS

Hypothalamic concentration of neuropeptide Y was decreased significant ly in anorectic tumor-bearing rats, while NPY level was increased sign ificantly in matched carcass weight control rats as compared with free ly-feeding controls. In vivo microdialysis of the perifomical hypothal amic area of tumor-bearing rats prior to the development of anorexia r evealed no alteration in NPY in dialysates. Following the development of anorexia, however, tumor-bearing rats exhibited significant reducti on in NPY concentration in dialysates as compared with either matched carcass weight or freely-feeding control group. These results suggest that hypothalamic NPY concentration and release are decreased selectiv ely in anorectic tumor-bearing rats. Since NPY also elicits less feedi ng in tumor-bearing rats, dysfunction of hypothalamic NPY feeding mech anisms may be of primary importance in cancer anorexia.