Fish oil constituent eicosapentaenoic acid inhibits endothelin-induced cardiomyocyte hypertrophy via PPAR-α.

Aims: A growing body of evidence shows the cardiovascular benefits of fish oil ingredients, including eicosapentaenoic acid (EPA), in humans and experimental animals. However, the effects of EPA on endothelin (ET)-1-induced cardiomyocyte hypertrophy and the involved signaling cascade are largely unknown. A previous study has demonstrated that peroxisomal proliferator-activated receptor (PPAR)-α ligand (fenofibrate) prevents ET-1-induced cardiomyocyte hypertrophy. Although EPA is a ligand of PPAR-α, to date, no study has examined a relationship between EPA and PPAR-α in cardiomyocyte hypertrophy. Here, we investigated whether EPA can block ET-1-induced cardiomyocyte hypertrophy and the possible underlying mechanisms.

Main Methods: At day 4 of culture, neonatal rat cardiomyocytes were divided into four groups: control, control cells treated with EPA (10 μM), ET-1 (0.1 nM) administered only and EPA-pre-treated ET-1 administered groups. Also, the cardiomyocytes were treated with PPAR-α siRNA in order to elucidate the mechanisms that may underlie suppression of hypertrophy via the EPA-PPAR system.

Key Findings: Following ET-1 treatment, 2.12- and 1.92-fold increases in surface area and total protein synthesis rate in cardiomyocytes, respectively, were observed and these changes were greatly blocked by EPA pre-treatment. Further, the expression of PPAR-α increased in EPA-treated groups. PPAR-PPRE binding activity was suppressed in ET-1 administered cardiomyocyte and this suppression was improved by EPA treatment. Lastly, pre-treatment of cardiomyocytes with PPAR-α siRNA prior to EPA treatment attenuated the suppressing effects of EPA on cardiomyocyte hypertrophy.

Significance: In conclusion, the present study shows that EPA attenuates ET-1 induced cardiomyocyte hypertrophy by up regulating levels of PPAR-α pathway.