Eicosapentaenoic acid protects against palmitate induced cell death of h9c2 cardiomyoblasts

Intracellular accumulation of fatty acid metabolites in non-adipose tissues has been proposed to play an important role in the pathogenesis of diabetes mellitus. Moreover, lipotoxicity may contribute to cell death and cardiac dysfunction. Evidence is emerging that saturated fatty acids induce cell death through apoptosis and this effect is specific for palmitate and stearate. On the other hand, n-3 polyunsaturated fatty acids (PUFAs) have been implicated in the protection against cardiovascular diseases, cardiac ischemic damage and myocardial dysfunction. In the present study we show- that supplementation with the n-3 PUFA- eicosapentaenoic acid (EPA)- to culture medium of H9c2 rat cardiomyoblasts protects cells against palmitate-induced apoptosis. Experiments were performed by using H9c2 rat ventricular cardiomyoblasts. Apoptosis was detected by trypan blue exclusion, MTT or caspase activity assays. Gene expression was investigated by Real Time PCR. Signal transduction pathways were investigated by western blotting. Our results indicate that palmitate induces apoptosis in a dose dependent manner. In particular, an approximately 4-fold increase in caspase activity was observed after 24 h of treatment with 500 M palmitate. The incubation with 60 M EPA inhibited palmitate-induced apoptosis of H9c2 cells. Preliminary results indicate that the anti-apoptotic effect of EPA could be mediated by the modulation of the transcriptional peroxisome proliferator–activated receptor  coactivator-1 considered a master regulator of myocardial energy metabolism in diverse pathophysiological conditions, and may involve the rapamycin-insensitive companion of mammalian target of rapamycin (mTOR) (Rictor), a key member of mTOR complex-2 that promotes cellular survival.