Abstract: Objective: To investigate the effect of Schisandrae Chinensis extracts (SCE) on the expressions of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits NOX2 and p47phox in myocardium tissue of the diabetic rats, and to clarify its protective effect on myocardium of the rats. Methods: Forty-nine clean healthy male Wistar rats were given single intraperitoneal injection of streptozotocin (STZ) to establish the diabetic rat models. Forty-five model rats were randomly divided into model group (n=12), low dose (100 mg·kg^-1) of SCE group(n=1), medium dose (200 mg·kg^-1) of SCE group(n=11) and high dose (400 mg·kg^-1) of SCE group(n=11); another 10 rats were selected as normal control group. After 12 weeks of intervention, the blood sample was obtained from abdominal aorta after anesthesia,and the serum was isolated;the heart was obtained and the weight of left ventricle was weighed,and the left ventricular mass index(LVMI) was calculated;the levels of fasting blood glucose(FBG), creatine kinase (CK) and lactate dehydrogenase (LDH) in serum of the rats in various groups were detected by automatic analyzer, the pathological changes of myocardium tissue were observed by HE staining, the levels of malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) and glutathione kinase (GSH) in myocardium tissue were determined by colorimetry, the expression levels of NOX2 mRNA and p47phox mRNA in myocardium tissue of the rats were detected by real-time fluorescence quantitative PCR, and the expression levels of NOX2 and p47phox proteins in myocardium tissue of the rats were detected by Western blotting method. Results: Compared with normal control group, the LVMI of the rats in model group was increased(P<0.01), the arrangement of myocardial cells was disordered, the levels of serum FBG, CK, LDH and MDA in myocardium tissue were increased (P<0.05 or P<0.01), the activities of SOD and GSH in myocardium tissue were decreased (P<0.05), and the expression levels of NOX2 and p47phox mRNA and proteins were increased (P<0.01). Compared with model group, the LVMI of the rats in different doses of SCE groups was decreased(P<0.05 or P<0.01),the myocardial damages were reduced, the levels of serum FBG, CK, LDH and MDA in myocardium tissue were decreased (P<0.05 or P<0.01), the SOD and GSH activities were increased (P<0.05), and the expression levels of NOX2 and p47phox mRNA and proteins were decreased (P<0.05) in a dose-dependent manner. Conclusion: SCE can reduce the FBG level of the diabetic rats, inhibit the expression of NADPH oxidase in myocardium tissue, and reduce the level of oxidative stress in myocardium tissue, which may be related to its myocardial protective effect.

Key words: Schisandrae Chinensis extracts, diabetes mellitus, cardiomyopathy, reduced nicotinamide adenine dinucleotide phosphate oxidase, NOX2, p47phox