ALTERATIONS IN HYPOTHALAMIC NPY AND CRF IN ANOREXIC TUMOR-BEARING RATS

Regional hypothalamic concentrations of neuropeptide Y (NPY) and corti cotropin-releasing factor (CRF), respectively a stimulant and an inhib itor of feeding behavior, were investigated in hypothalamic nuclei in rats carrying the Yoshida sarcoma. Tumor-bearing rats (n = 10), non-tu mor-bearing controls (n = 10), and food-restricted rats (n = 10), whic h did not carry tumors but were pair-fed to match the reduced food int ake of the tumor-bearing group, were studied after 10 days. NPY concen trations in the arcuate nucleus (ARC, the main site of NPY synthesis) were significantly increased above controls (P < 0.01) in both tumor-b earing and food-restricted groups. However, NPY concentrations in the paraventricular nucleus (PVN, an NPY-sensitive site of NPY release) sh owed opposing changes, with a 25% decrease (P = 0.052) in the tumor-be aring but a 48% increase (P < 0.0 1) in the food-restricted group. CRF concentrations in both the PVN and the ARC were significantly reduced (P < 0.01) in the food-restricted group, but remained close to contro l values in the tumor-bearing group (P not significant). Changes in hy pothalamic appetite-regulating neuropeptides in cancer anorexia, which may result from the action of cytokines produced by a host defense re sponse or the tumor itself, may account for reduced feeding. Such chan ges may include impaired activity of NPY or failure of CRF activity to be suppressed after underfeeding and weight loss.