Resveratrol-Mediated Activation of cAMP Response Element- Binding Protein through Adenosine A3 Receptor by Akt-Dependent and -Independent Pathways

A recent study documented a role of adenosine A3-Akt-cAMP response element-binding protein (CREB) survival signaling in resveratrol preconditioning of the heart. In this study, we demonstrate that resveratrol-mediated CREB activation can also occur through an Akt-independent pathway. Isolated rat hearts were perfused for 15 min with Krebs-Henseleit bicarbonate (KHB) buffer containing resveratrol in the absence or presence of adenosine A3 receptor blocker MRS-1191 [3-ethyl-5-benzyl2-methyl-4-phenylethynyl-6-phenyl-1,4-( )-dihydropyridine3,5-dicar-boxylate], phosphatidylinositol 3 (PI3)-kinase inhibitor LY294002 [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4one hydrochloride], mitogen-activated extracellular signalregulated protein kinase inhibitor PD098059 [2-(2-amino-3methoxyphenyl)-4H-1-benzopyran-4-one], or a combination of LY294002 and PD098059. All hearts were subsequently subjected to 30-min ischemia followed by 2-h reperfusion. Cardioprotection was examined by determining infarct size, cardiomyocyte apoptosis, and ventricular recovery. Resveratrol phosphorylated both Akt and CREB that was blocked by MRS1191, which also abolished cardioprotective abilities of resveratrol. LY294002 completely inhibited Akt phosphorylation but partially blocked the phosphorylation of CREB. Inhibition of PI3-kinase also partially blocked resveratrol’s ability to precondition the heart. PD098059 partially blocked the phosphorylation of CREB and resveratrol-mediated cardioprotection. Preperfusing the hearts with LY294002 and PD098059 together completely abolished the phosphorylation of CREB, simultaneously inhibiting resveratrol-mediated cardioprotection. The results indicate that resveratrol preconditions the hearts through adenosine A3 receptor signaling that triggers the phosphorylation of CREB through both Akt-dependent and -independent pathways, leading to cardioprotection. Resveratrol, a naturally occurring phytoalexin abundant in grapes and red wines, has been found to provide cardioprotection through a mechanism involving pharmacological preconditioning (Bradamante et al., 2000; Hattori et al., 2002; Imamura et al., 2002; Das et al., 2005). The cardioprotective effects of red wine have been attributed to the resveratrol present in red wine (Hung et al., 2004) through diverse mechanisms, including its ability to inhibit low-density lipoprotein (Chen and Pace-Asciak, 1996), block platelet aggregation (Bertelli et al., 1996), and induce NO production (Ma et al., 1993). NO seems to be involved in resveratrolmediated cardioprotection (Chen and Pace-Asciak, 1996; Hattori et al., 2002; Imamura et al., 2002; Bradamante et al., 2003; Hung et al., 2004), which also plays a crucial role in ischemic preconditioning of the heart (Tosaki et al., 1998; Guo et al., 1999). Several reports exist in the literature to indicate a role of adenosine in resveratrol-mediated preconditioning. Similar to NO, adenosine is also involved in resveratrol preconditioning (Bradamante et al., 2003; Das et al.,