Modulation of prostaglandin synthesis in rat peritoneal macrophages with ω‐3 fatty acids,

Abstract
In view of the findings that ω3 fatty acids inhibit the synthesis of prostaglandins (PG) from arachidonic acid (20∶4ω6) and that among immunologically active cells, the macrophage, is a major producer of PG, we undertook a study of the effect of dietary α-linolenic acid (18∶3ω3) on PG synthesis in the macrophage. Rats were fed purified diets containing either 10% corn oil (CO) or linseed oil (LO), providing either a low (1/32) or high (3.5/1) ratio of 18∶3ω3 to 18∶2ω6, respectively, for 6 weeks. Fatty acid analysis of macrophage phospholipids showed that there was an appreciable increase in the percentage of ω3 fatty acids and a decrease in the ω6 fatty acids in macrophages from rats fed the LO diet. The changes in fatty acid composition were associated with a significant decrease in the synthesis of prostaglandin E (PGE) by macrophages from rats fed the LO diet. Macrophages from rats fed the 2 dietary, oils did not differ in their ability to degrade PG, thus the difference in PG production appeared to be a consequence of decreased synthesis only. The dietarily induced changes in PGE synthesis were readily overcome in vitro by culturing macrophages with complexes of fat-free bovine serum albumin and either 20∶4ω6 or 20∶5ω3.