Eicosapentaenoic acid prevents endothelin-1-induced cardiomyocyte hypertrophy in vitro through the suppression of TGF-β1 and phosphorylated JNK

Abstract

The cardiovascular benefit of fish oil in humans and experimental animals has been reported. Endothelin (ET)-1 is a well-known cardiac hypertrophic factor. However, although many studies link a fish oil extract, eicosapentaenoic acid (EPA), to cardiac protection, the effects of EPA on cardiac hypertrophy and underlying mechanism(s) are unclear. The present study investigated whether EPA prevents ET-1-induced cardiomyocyte hypertrophy; the potential pathways likely to underlie such an effect were also investigated. Cardiomyocytes were isolated from neonatal rat heart, cultured for 3 days, and then treated for 24 h with vehicle only (control), treated with 0.1 nM ET-1 only, or pretreated with 10 microM EPA and then treated with 0.1 nM ET-1. The cells were harvested, and changes in cell surface area, protein synthesis, expression of a cytoskeletal (alpha-actinin) protein, and cell signaling were analyzed. ET-1 induced a 97% increase in cardiomyocyte surface area, a 72% increase in protein synthesis rate, and an increase in expression of alpha-actinin and signaling molecule [transforming growth factor-beta 1 (TGF-beta 1), c-Jun NH2-terminal kinase (JNK), and c-Jun]. Development of these ET-1-induced cellular changes was attenuated by EPA. Moreover, the hypertrophied cardiomyocytes showed a 1.5- and a 1.7-fold increase in mRNA expression of atrial and brain natriuretic peptides, the classical molecular markers of cardiac hypertrophy, respectively; these changes were also suppressed by EPA. Here we show that ET-1 induces cardiomyocyte hypertrophy and expression of hypertrophic markers, possibly mediated by JNK and TGF-beta 1 signaling pathways. These ET-1-induced effects were blocked by EPA, a major fish oil ingredient, suggesting that fish oil may have beneficial protective effects on cardiac hypertrophy.

The H9C2 cell line and primary neonatal cardiomyocyte cells show similar hypertrophic responses in vitro

“…1b). All these responses are comparable with previous reports (Pedram et al 2005;Shimojo et al 2006;Frank et al 2007). H9C2 cells are generally larger than primary cardiomyocytes but, other than this intrinsic difference, they displayed similar structural responses to the Ang II-treated PNCMs (Fig.…”

ET-1 from endothelial cells is required for complete angiotensin II-induced cardiac fibrosis and hypertrophy

“…In the hypertrophic heart, the expression of ANP and BNP is elevated and it is therefore considered as reliable prognostic markers (Shimojo et al, 2006). It is established that the cardiac expression of natriuretic peptides is under the control of ET-1 (Bianciotti and de Bold, 2000).…”

“…It is known that TGFβ is required for the cardiac hypertrophic effect of AngII (Shimojo et al, 2006). The main sources of TGFβ are the fibroblasts and the cardiomyocytes.…”

Dietary fish oil is antihypertrophic but does not enhance postischemic myocardial function in female mice

“…Takahashi et al (45) observed that dietary FO prevented the membrane translocation of several cytosolic protein kinase C isozymes and suggested that this may be the mechanism for the hypertrophy suppression in the JVS mice. In vitro studies in isolated neonatal rat cardiac myocytes (sex of rats not reported) have demonstrated that DHA and EPA inhibit the growth response (i.e., protein synthesis) induced by phenylephrine and endothelin-1 stimulation via the Ras/Raf/Erk1/2 and JNK signaling pathways (41,42). In the present study, the growth reduction effect of FO diet was observed without a prior hemodynamic loading stimulus and therefore likely reflects a direct modulation of intrinsic myocardial trophic maintenance signaling.…”