Effect of miR-9 on myocardial fibrosis in rats via TGF-β1/Smads signaling pathway.

Objective: To observe the effect of micro ribonucleic acid (miR)-9 on the myocardial fibrosis (MF) in rats and explore its mechanism of action.

Methods: A total of 30 rats were selected to prepare the models of MF and randomly divided into Sham group, Model group and MiR-9 group. The rat heart weight (HW)/body weight (BW) and left ventricular weight (LVW)/BW were determined. The content of hydroxyproline (Hyp) in the myocardial tissues of left ventricle was measured using a spectrophotometer. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the levels of type I and type III collagens in myocardial tissues, and the level of miR-9 in myocardial tissues was determined via reverse transcription-polymerase chain reaction (RT-PCR). Finally, Western blotting was conducted to measure the levels of transforming growth factor-β1 (TGF-β1) and Smads2 proteins.

Results: Compared with Sham group, Model group exhibited increased HW/BW and LVW/BW and markedly raised Hyp content and type I collagen, type III collagen, TGF-β1 protein and Smads2 protein levels, but significantly declined miR-9 expression levels in rats. In MiR-9 group, the rats had substantially decreased HW/BW, LVW/BW, Hyp content, and type I and type III collagen levels as well as lowered TGF-β1 protein and Smads2 protein levels.

Conclusions: MiR-9 can alleviate the MF in rats by inhibiting the TGF-β1/Smads signaling pathway.