Protective effect of eicosapentaenoic acid on palmitate-induced apoptosis in neonatal cardiomyocytes

Long chain polyunsaturated fatty acids (PUFAs) play an important role in cardioprotection. These effects have been largely attributed to membrane docosahexaenoic acid. Conversely, saturated fatty acids trigger apoptosis in cardiomyocytes, with modifications of mitochondrial properties including cardiolipin loss, cytochrome c release and caspase-3 activation. The purpose of this study was to investigate the chronic effect of eicosapentaenoic acid (EPA) on mitochondrial apoptosis induced by palmitate treatment and the associated signalling pathways. Confluent cultures of rat neonatal cardiomyocytes were treated for 2 days in media enriched with either EPA or arachidonic acid (AA) and then exposed to palmitate (0.5 mM) to induce apoptosis, in the absence of PUFA supplements. The EPA treatment resulted in significant membrane enrichment in n-3 PUFAs, especially in docosapentaenoic acid (DPA), and a large decrease in AA. Both AA and EPA treatments prevented caspase-3 activation, translocation of Bax to the mitochondria and release of cytochrome c induced by palmitate treatment. Furthermore, EPA, but not AA prevented the loss' of mitochondrial cardiolipin due to apoptosis. These results suggest that EPA supplementation is able to protect cardiomyocytes against palmitate-induced apoptosis via an implication of different mitochondrial elements, possibly through its elongation to DPA, which is very efficient in cardiomyocytes. (C) 2008 Elsevier B.V. All rights reserved.