Hypothalamic concentration and release of neuropeptide Y into microdialysates is reduced in anorectic tumor-bearing rats.

Hypothalamic concentration of neuropeptide Y was decreased significantly in anorectic tumor-bearing rats, while NPY level was increased significantly in matched carcass weight control rats as compared with freely-feeding controls. In vivo microdialysis of the perifornical hypothalamic area of tumor-bearing rats prior to the development of anorexia revealed no alteration in NPY in dialysates. Following the development of anorexia, however, tumor-bearing rats exhibited significant reduction 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 selectively in anorectic tumor-bearing rats. Since NPY also elicits less feeding in tumor-bearing rats, dysfunction of hypothalamic NPY feeding mechanisms may be of primary importance in cancer anorexia.