Omega-3 and Omega-6 Fatty Acids Kill Thymocytes and Increase Membrane Fluidity~!2010-02-13~!2010-04-12~!2010-05-25~!

Background: Omega-3 but not omega-6 fatty acids are thought to promote cardiovascular health by increasing membrane fluidity. Methods: The actions of acute application of omega-3 (docosahexaenoic acid (DHA, 22:6n-3), eicosapentaenoic (EPA, 20:5n-3) and � -linolenic acid (ALA, 18:3n-3)) and omega-6 (docosatetraenoic acid (DTA, 22:4n-6), arachidonic acid (ARA, 20:5n-6) and linoleic acid (LNA, 18:2n-6)) fatty acids on plasma membrane fluidity and cytotoxicity were investigated using mouse thymocytes. Membrane fluidity was assessed by determining fluorescence polarization of 1, 6- diphenyl-1, 3, 5-hexatriene (DPH) and cell death was assessed by using propidium iodide (PI). Results: Membrane fluidity in omega-3 treated cells was significantly increased in the order of DHA>EPA>ALA, but DTA and ARA also increased fluidity and were even more potent. Both omega-3 and omega-6 fatty acids were acutely cytotoxic to thymocytes at concentrations that altered membrane fluidity, and omega-6 fatty acids caused more cell death than omega-3s. Conclusions: The omega-6 fatty acids, DTA and ARA, are more potent than long chain omega-3 fatty acids in causing an increase in membrane fluidity in thymocytes. General Significance: Our results suggest that the beneficial effects of fish consumption are unlikely to be secondary to a selective action of omega-3 fatty acids on membrane fluidity.

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