Abstract: 【Abstract】 Objective To study the effect and role of leptin on myocardial ischemia / reperfusion injury (MIRI) in mouse。Methods：Twenty four male rat were randomized into 4 group:①the sham-operation group;②the myocardial ischemia reperfusion group (MIRI group)，established by blocking left coronary artery anterior descending branch for 30 min followed by reperfusion ③the leptin pretreatment group(leptin+ MIRI group),established by injecting intraperitoneally leptin at 30 min before ischemia; ④the leptin post—treatment group(MIRI +leptin group),established by injecting intraperitoneally leptin at 30 min after reperfusion。Blood and heart samples were harvested from each mouse at 120 min after reperfusion。We then analyzed the samples for leption level associated with MIRI。Results: Leptin treatment increased myocardial infarct size and myocardial leptin levels and serum leptin、creatine kinase (CK)、lactate dehydrogenase (LDH)、aspartate aminotransferase (AST)、Troponin T（TnT） levels. Leptin pretreatment reduces myocardial infarct size and myocardial leptin levels and serum leptin、creatine kinase (CK)、lactate dehydrogenase (LDH)、aspartate aminotransferase (AST) 、Troponin（TnT）levels. Conclusion: Treatment and high level of leptin increased the myocardial ischemia / reperfusion injury, leptin pretreatment reduced myocardial ischemia / reperfusion injury。

Key words: myocardial ischemia / reperfusion injury, Leptin treatment, Leptin pretreatment