Inhibitors of prostaglandin synthesis do not improve food intake or body weight of tumor-bearing rats

Interleukin-l (IL-I) and tumor necrosis factor (TNF) are immunoregulatory c ytokines that mediate many aspects of the acute phase response to infection and injury. It has been hypothesized that these cytokines mediate the onse t of the cachexia-anorexia syndrome with tumor growth. The anorexigenic eff ects of IL-l are mediated in part by prostaglandins (PG). Therefore, the pu rpose of the present study was to determine if administration of ibuprofen (ibu) or indomethacin (indo), which inhibit PG synthesis, would affect the food intake and body weight of tumor-bearing rats. Rats were implanted with the Morris 7777 hepatoma, a tumor known to induce anorexia and weight loss in rats, and weight loss and leukocyte synthesis of IL-l and TNF in mice. Treatment with indo or ibu did not improve food intake or body weight in th e tumor-bearing rats. However, administration of ibu coincident with tumor implantation did result in smaller tumor mass compared to placebo-treated c ontrols. The results of the present study suggest that PG synthesis is not a major factor in the onset of anorexia in this animal model of tumor-induc ed anorexia. However, further studies of the effects of inhibitors of PG sy nthesis on the kinetics of tumor growth are clearly indicated. (C) 1999 Joh n Wiley & Sons, Inc.