Abstract: Objective To investigate the protein expression of Atg7 and Atg12-Atg5 in myocardium of streptozotocin(STZ) diabetic rats. Methods The diabetic model was made in rats by injection of STZ. The rats were divided into normal control group(NC) and diabetes model group(DM). The left ventricular weight index of rats were detected at the time of 10, 20, 30, 40, 60, 80, 100 d after model formed. The protein expression of Atg7 and Atg12-Atg5 in myocardium of rats was assayed by western blot. The myocardial ultrastructure and autophagosome were observed by electron microscope. Results Compared with rats in NC group at the same period, the left ventricular weight index in DM group increased since 40 d after model formed. The protein expression of Atg7 and Atg12-Atg5 in myocardium of diabetic rats increased a little at 20 d (It had not a statistical significance), but reduced significantly at 80d (P<0.01). The changes in the myocardial ultrastructure and decrease in autophagosome were both obvious in diabetic rats at 80d. Conclusions With the development of diabetes mellitus, the autophagy level in myocardium of STZ diabetic rats finally reduced.

Key words: Streptozotocin, Diabetes, Myocardium, Autophagy