Grape seed proanthocyanidin reduces cardiomyocyte apoptosis by inhibiting ischemia/reperfusion-induced activation of JNK-1 and C-JUN.

The mechanism of cardioprotection with red wine consumption was studied by examining the antideath signaling cascade of one of the principle components of red wine, proanthocyanidins. Grape seed proanthocyanidin extract (GSPE) was administered orally (100 mg/kg/d) supplemented with regular diet for 3 weeks to a group of rats while the other group was given the regular diet only for the same period of time. After 3 weeks, rats were sacrificed, hearts excised, and perfused via Langendorff mode. After stabilization, hearts were perfused in the working mode for baseline measurement of contractile function. Hearts were then made globally ischemic for 30 min followed by 2 h of reperfusion. Contractile function was continuously monitored during reperfusion, and free radical production was examined by electron spin resonance (ESR) technique. Cardiomyocyte apoptosis was examined by TUNEL staining in conjunction with an antibody against myocin heavy chain to specifically detect myocytes. Induction of JNK-1 and c-fos proteins was studied by Western blot analysis using respective antibodies followed by densitometric scanning. The results indicated significant induction of JNK-1 and c-fos proteins in the ischemic/reperfused myocardium, which was inhibited by the proanthocyanidin extract. In concert, GSPE significantly reduced the appearance of apoptotic cardiomyocytes in the ischemic/reperfused hearts. GSPE also significantly reduced the appearance of the reactive oxygen species in the hearts. Improved postischemic contractile recovery was achieved with GSPE suggesting its cardioprotective action. The results of this study indicated that GSPE functioned as an in vivo antioxidant, and its cardioprotective properties may be at least partially attributed to its ability to block antideath signal through the inhibition of proapoptotic transcription factor and gene, JNK-1 and c-Jun.