Rhein protects the myocardiac cells against hypoxia/reoxygention-induced injury by suppressing GSK3β activity

Background Rhein, an anthraquinone compound isolated from rhubarb, has been shown to protect the pancreatic β cells from hyperglycemia induced apoptosis in our previous studies. Purpose In the present study, we examined whether rhein can protect myocardial cells against ischemia reperfusion (I/R)-induced apoptosis and investigated the underlying mechanism. Methods We used an in vitro model of myocardial hypoxia/reoxygenation (H/R) injury. H9c2 cells were incubated with rhein for 1 h and then subjected to hypoxia for 6 h, followed by reoxygenation for 2 h. Cells viability, apoptosis and ROS were assayed for the treated cells. AKT, p-AKT, GSK3β, p- GSK3β, P38 and p-P38 proteins were analyzed using Western blotting. PI3K/AKT inhibitor, LY294002, and GSK3β siRNA were also used to determine the signaling pathways involved in the protection by rhein. Results Rhein increased viability, decreased apoptosis and ROS production, of the cells that were exposed to H/R. Rhein also increased the phosphorylation of AKT and GSK3β, an effect that was eliminated by LY294002. GSK3β silencing by siRNA showed similar effect as LY294002. The p-P38 level was upregulated by H/R and downregulated in the presence of rhein; however, the p-P38 downregulation was completely abolished by GSK3β silencing. Conclusion Rhein protects myocardial H9c2 cells against hypoxia/reoxygenation induced injury via AKT/ GSK3β/p38 pathway.