Vascular smooth muscle cells preloaded with eicosapentaenoic acid and docosahexaenoic acid fail to respond to serotonin stimulation

Epidemiological, animal and clinical studies indicate that n-3 fatty acids may benefit individuals with known history of cardiovascular disease or at risk of developing it. Though there is indirect evidence to suggest that th e beneficial effects of n-3 fatty acids may be because of their ability to inhibit smooth muscle cell (SMC proliferation, there are no studies that ha ve examined this hypothesis, In this study, the mitogenic effect of seroton in (5HT) and platelet derived growth factor (PDGF), known mitogens for vasc ular SMC, on aortic SMCs preloaded with eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) is examined. 5HT and PDGF could only partially s timulate proliferation of SMC that were preloaded with EPA or DHA as compar ed to the control cells, gamma -linolenic acid (LA) and oleic acid (OA) did not block the 5HT or PDGF induced (3)[H]thymidine incorporation suggesting that the anti-proliferative effect was specific to n-3 fatty acids only. F urther, when EPA and DHA were combined in the ratio they are present in fis hoils, there was a synergistic interaction in inhibiting the proliferation of SMC. Further, SMC grown in the presence of EPA or DNA, when stimulated w ith 5HT(2) failed to show an increase in 5HT(2) receptor mRNA. One of the p otential mechanism by which fish oils may prevent the development of athero sclerosis or restenosis could be inhibition of the mitogen induced SMC prol iferation. Combination of EPA with DHA is likely to be more beneficial. (C) 2000 Elsevier Science Ireland Ltd. All lights reserved.