Role of PI3K/Akt signaling pathway in hydrogen-induced inhibition of cell apoptosis during myocardial ischemia/reperfusion in rats

Objective To evaluate the role of phosphoinositide 3 kinase/protein kinase B (PI3K/Akt) signaling pathway in hydrogen-induced inhibition of cell apoptosis during myocardial ischemia/reperfusion (I/R) in rats.Methods Forty healthy male Sprague-Dawley rats,weighing 300-350 g,were randomly allocated into 4 groups (n =10 each) using a random number table:sham operation group (S group),I/R group,hydrogen group (group H),and hydrogen + LY294002 group (group HL).Myocardial I/R was induced by occlusion of the anterior descending branch of left coronary artery for 30 min followed by 120 min reperfusion.In H and HL groups,99.6 ％ hydrogen 5 ml/kg was injected intraperitoneally immediately after beginning of reperfusion,and in addition LY294002 (0.3 mg/kg) was injected through the caudal vein before hydrogen injection in group HL.Arterial blood samples were collected at the end of 120 min reperfusion for determination of serum creatine kinase isoenzyme-MB (CK-MB) and lactate dehydrogenase (LDH) activities.The rats were then sacrificed.Myocardial apoptosis was detected by TUNEL and apoptosis index (AI) was calculated.The expression of Bcl-2,Bax and caspase-3 was detected by immuno-histochemistry.Bcl-2/Bax ratio was calculated.Results The serum CK-MB and LDH activities and AI were significantly increased,the expression of myocardial Bcl-2,Bax and caspase-3 was upregulated,and the ratio of Bcl-2/Bax was decreased in group I/R as compared with group S.Compared with group I/R,the serum CK-MB and LDH activities and AI were significantly decreased,the expression of myocardial Bcl2 was up-regulated,while the expression of myocardial Bax and caspase-3 was down-regulated,and the ratio of Bcl-2/Bax was increased in group H,and no significant changes were found in the parameters mentioned above in group HL.The serum CK-MB and LDH activities and AI were significantly increased,the expression of myocardial Bcl-2 was down-regulated,while the expression of myocardial Bax and caspase-3 was up-regulated,and Bcl-2/Bax ratio was decreased in group HL as compared with group H.Conclusion Hydrogen can activate the PI3K/Akt signaling pathway,and further up-regulates Bcl-2 expression and down-regulates Bax and Caspase-3 expression,thus inhibiting cell apoptosis during myocardial I/R in rats. Key words: 1-Phosphatidylinositol 3-kinase ;  Protein-serine-threonine kinases ;  Hydrogen ; Myocardial reperfusion injury;  Apoptosis