Adropin reduces hypoxia/reoxygenation-induced myocardial injury via the reperfusion injury salvage kinase pathway

Adropin is a secreted polypeptide that has been demonstrated to serve an important role in protecting the vascular endothelium. Pharmacological activation of pro-survival kinases, such as PI3K-Akt and ERK1/2, are involved in the reperfusion injury salvage kinase (RISK) pathway. In the present study, the effects of adropin in cardiomyocyte injury induced by simulated ischemia/reperfusion (SI/R) were assessed. Additionally, the current study also assessed the mechanisms that govern SI/R in a H9c2 cardiomyoblast cell model. Cell viability was measured using an MTT assay. Cell injury was assessed using creatine kinase MB measurements. Apoptosis was assessed using flow cytometry and caspase-3 activity. The inflammatory response was measured using tumor necrosis factor alpha and interleukin-10 expression. Oxidative stress was assessed using malondialdehyde and superoxide dismutase. The expression levels of Akt, ERK1/2, glycogen synthase kinase 3 beta (GSK3 beta), Bcl-2 and Bax were determined using western blot analysis. The results of the current study revealed that moderate-dose adropin increased cell viability, reduced early apoptosis and caspase-3 activity, promoted Bcl-2 expression, inhibited Bax and increased the Bcl-2/Bax ratio. Adropin significantly increased the phosphorylation of Akt, ERK1/2 and GSK3 beta, whereas inhibitors of PI3K and ERK1/2, respectively, LY294002 and PD98059, abolished the cardioprotective role of adropin. Furthermore, no significant difference was observed in phosphorylated-STAT3/total-STAT3 expression between the adropin and SI/R groups and Janus kinase 2 inhibitor AG490 did not significantly inhibit the protective role of adropin. These results indicate that adropin exerts a protective effect against SI/R injury through the RISK pathway instead of the survivor activating factor enhancement pathway.