MiR-21 antagomir improves insulin resistance and lipid metabolism disorder in streptozotocin-induced type 2 diabetes mellitus rats

Background Type 2 diabetes mellitus (T2DM) is a major cause of death with an increasing incidence at an epidemic rate. The existing treatments for T2DM lack long-term effective blood glucose control. In this study, the effects of miR-21 antagomir on T2DM and the related mechanism were investigated using streptozotocin (STZ)-induced T2DM rats. Methods 30 T2DM rats were randomly divided into 3 groups (n=10): T2DM group, T2DM rats with miR-21 antagomir group, T2DM rats with NC antagomir group. The expression of miR-21 in rats was detected by qRT-PCR. blood glucose, triacylglycerol (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-Cho), insulin, adiponectin, ITT and GTT were detected. The expression of TIMP3 in si-TIMP3 rats and the expression of TIMP3 in T2DM rats with miR-21 antagomir and si-TIMP3 was detected by Western blotting. Results We found that miR-21 antagomir reduced blood glucose concentration in T2DM rats. MiR21 antagomir improved lipid metabolic disorder by decreasing the levels of triacylglycerol (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-Cho) and increasing the level of high-density lipoprotein cholesterol (HDL-Cho). Also, miR-21 antagomir reduced the value of homeostasis model assessment of insulin resistance (HOMA-IR), hemoglobin A1c (HbAc1), plasma insulin, and up-regulated the plasma adiponectin. These results, combined with insulin tolerance tests (ITT) and glucose tolerance tests (GTT) results, showed that miR-21 improved insulin resistance in STZ-induced T2DM rats. Then the target relationship between miR-21 and tissue inhibitor of metalloproteinases 3 (TIMP3) was proved by luciferase reporter assay. More impressively, miR-21 significantly increased the expression level of TIMP3 in STZ-induced T2DM rats. Conclusions Our study taken together has shown that miR-21 antagomir improved insulin resistance and lipid metabolism disorder in STZ-induced T2DM rats by up-regulating the expression level of TIMP3. This study suggested that miR-21 antagomir could be used as an effective therapeutic strategy and the underlying mechanism was revealed.