RAPID COMMUNICATION: Suppression of Nitric Oxide Production in Lipopolysaccharide‐stimulated Macrophage Cells by ω3 Polyunsaturated Fatty Acids

Although nitric oxide (NO) is an important biological mediator, its excessive production in inflammation is thought to be a causative factor for cellular injury and, over the long term, cancer. In the present study, the effects of several fatty acids on NO production in murine macrophage cell line RAW264 cells stimulated with lipopolysaccharide were examined. Suppression of NO production was observed with the ω3 polyunsaturated fatty acids (PUFAs), docosahexaenoic acid, eicosapentaenoic acid and α‐linolenic acid, in a dose‐dependent fashion. In contrast, no inhibition was observed with ω6 PUFA (linoleic acid),ω9 PUFA (oleic acid) or a saturated fatty acid (stearic acid). Western and northern blot analyses suggested that suppression of the induction of inducible NO synthase gene expression is responsible for the inhibition of NO production by ω3 PUFAs. The inhibitory effect of ω3 PUFA on NO production in activated macrophages could contribute to their cancer chemopreven‐tive influence.