The effects of cyclooxygenase inhibitors on tumor‐induced anorexia in rats

Abstract

Background. Interleukin‐1 (IL‐1) and tumor necrosis factor (TNF) are potent induces of prostaglandin (PG) synthesis and injection of PGE, IL‐1, or TNF decreases food intake in healthy animals, whereas the anorexigenic effects of injected IL‐1 and TNF are blocked by inhibitors of PG synthesis. It has been hypothesized that host secretion of IL‐1 and TNF contribute to tumor‐induced anorexia. This study was undertaken to determine whether administration of PG inhibitors alters food intake in anorectic rats implanted with Walker 256 carcinoma. Methods. Groups of six tumor‐bearing rats were implanted with slow‐release pellets containing ibuprofen, indomethacin, or acetylsalicylic acid. Food intake, tumor growth, and body temperature were monitored for 14 days and compared with control tumor‐bearing animals implanted with placebo pellets. Results. Tumor growth was associated with anorexia, fever, wieght loss, and increased leukocyte secretion of IL‐1 and TNF. Indomethacin and ibuprofen retarded tumor growth 30–40% and lowered body temperature compared with controls, but had no effect on food intake or body weight of tumor‐bearing animals. Conclusions. Prostaglandins do not mediate tumorinduced anorexia. Copyright © 1993 American Cancer Society