The effect of the mechanical unloading of lower limb on MST1 and Atrogin1 gene expression in Plantaris and soleus muscles of Wistar rats

The mammalian Ste20-like kinase (MST) is involved in the activation of the ubiquitin pathway ligase atrogin1 in denervation atrophy. The aim of the present study was the study of changes in MST1 mRNA and Atrogin1 mRNA gene expression in the muscles of male Wistar rats with mechanical unloading of hind limb muscles. In the present study 10 Wistar rats (4-6 month) divided into 2 groups randomly (control (N=5) and unloading of the hind limb (N=5) groups). The practical group unloaded of hind limb for 14 days and the control group spent the normal life during this period. After 14 days, the rats were sacrificed and their muscles and Plantaris were collected and after weighing the muscle, they were kept in liquid nitrogen. The results of this study showed that after 14 days of lower limb suspension, the relative weight of both soleus and plantar muscles decreased but this reduction was not significant in Plantaris skeletal muscle. In addition, the expression of genes MST1 mRNA (P=0.021) significantly increased and also atrogen-1 mRNA (P=0.056) in soleus muscle increased. Also, MST1 mRNA (P=0.071) and atrogen-1 mRNA (P=0.33) in Plantaris muscle increased insignificantly. Comparison of the genes expression in two skeletal muscles showed that the expression of MST1 mRNA in soleus more than Plantaris, on the other hand, expression of atrogen-1 mRNA in Plantaris increased more than soleus muscle. According to the results of this study, it can be claimed that MST1 can be one of the main targets of controlling atrophy in conditions mechanical unloading, such as hospitalization and space travel. However, the lower targets of MST1 can be different in two muscles.