[Effects of insulin-like growth factor-1 on the myocardium in diabetic rats]

To observe the effects of insulin-like growth factor-1(IGF-1) on myocardial fibrosis and myocardial cell apoptosis in diabetic rats, so as to clarify the potential benefit of IGF-1 on diabetic cardiomyopathy.

Diabetic rats were induced by caudal injection of STZ, and the diabetic rats were randomly divided into 3 groups:diabetes group, the insulin treatment group and the IGF-1 treatment group.Normal control (NC) group did not receive any therapy. The experiment lasted 10 weeks and the heart weight was recorded to calculate the heart weight index. The serum insulin and IGF-1 level were determined.HE staining and Masson staining were taken on the left ventricular tissue. The cardiomyocyte apoptosis were measured by methods of terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) , the expression levels of IGF-1R in cardiomyocytes were measured by immunohistochemical and Western blot.

Compared with diabetes group, the heart weight index of the insulin treatment group and the IGF-1 treatment group were significantly decreased. Serum levels of IGF-1 in diabetes group were significantly decreased compared with NC group, and the levels were significantly increased in IGF-1 treatment group. The results of HE and Masson staining showed that compared with NC group, diabetes rats' myocardial tissue were damaged. Myocardial tissue pathological changes of rats were significantly improved after insulin and IGF-1 treatment. The result of TUNEL indicant cardiomyocyte apoptosis index in diabetes group was obviously increased than the NC group, and that in IGF-1 treatment group were decreased compared with diabetes group. IGF-1R levels in diabetic rats myocardial tissue were rised than the NC group, it was declined in IGF-1 treatment group, but in insulin treatment group the levels had no obvious change.

IGF-1 can inhibite the myocardial fibrosis and cardiomyocyte apoptosis. It maybe have the possible effect on the treatment of diabetic cardiomyopathy.