Increased Expression of miR-1 in Fast-Twitch Skeletal Muscle in Response to Resistance Exercise

The response of microRNA (miR-1), upstream regulators (Myogenic Differentiation 1 (MyoD1) and Myocyte Enhancer Factor 2C (Mef2C)), and a downstream target (Histone Deacetylase 4 (Hdac4)) to an acute bout of Resistance Exercise (RE) in Extensor Digitorum Longus (EDL) and soleus muscles has remained elusive. In this experimental study, we investigated the effect of an acute bout of RE on the expression of miR-1, MyoD1, Mef2C, and Hdac4 genes in the slow and fast-twitch muscle of rats. The current study was conducted at Tarbiat Modares University, Tehran, Iran, in 2017. Fifteen male Wistar rats were randomly divided into two groups, control (n = 5) and RE (n = 10). The RE protocol consisted of four sets of five repetitions of climbing a ladder with weights attached to the tails of rats. The soleus and EDL muscles of rats were collected at 3 h (n = 5) and 6 h (n = 5) post-RE. The real-time polymerase chain reaction was used to measure the levels of miR-1, MyoD1, Mef2C, and Hdac4 mRNA expression. The miR-1 expression in EDL muscle was significantly lower at 3 h and 6 h post-exercise in the RE group than in the control group (P < 0.01). The miR-1 expression in soleus muscle was significantly lower at 3 h post-exercise in the RE group than in the control group (P < 0.007) but it was significantly higher at 6 h post-exercise (P < 0.036). The expression of MyoD1, Mef2C, and Hdac4 genes in the EDL muscle was higher in the RE group than in the control group (P < 0.01). The expression of these genes in response to RE had more fluctuations in soleus muscle. It can be concluded that miR-1 expression in extensor digitorum longus and soleus muscles of rats responds to resistance exercise in different manners and this coincides with a change in upstream regulators and downstream target.