Expression Of MicroRNA-1/133a In Denervated Skeletal Muscle Preliminary Study

Objective: To investigate the expression of MicroRNA-1/133a in denervated skeletal muscleat different periods.Methods: From April2012to December2012, a total of54Sprague-Dawle rats weighting(20010)g were used. They were randomly divided into9groups, each group of6.The rightsciatic nerve was cut off in rats (experimental group), with the left one being sham operation(control group) at various time points(0h,8h,1d,3d,1weeks,2weeks,3weeks,4weeks,8weeks). Then after rats were sacrificed by spinal dislocation,the muscle sample (gastrocnemius,extensor digitorum longus and soleus) were harvested and weighed, then stored at-70degreesrefrigerator. MicroRNA-1/133a were detected in each muscle specimens by RT-PCR.Theultrastructural changes of each muscle specimens at different periods were observed by electronmicroscopy.Results: The muscle wet weight ratio of experimental group decreased gradually overtime.Observed by electron microscopy, the different types of muscle fiber were disorderedarrangement at different time points. RT-PCR was performed to quantitatively analyzemiRNA-1/133a expressions of the fast-twitch muscles (i.e., gastrocnemius and extensordigitorum longus) and slow-twitch muscle (soleus). In the control group, miRNA-133andmiRNA-1expression in the soleus muscles were maintained at a certain level,whereas in theexperimental group, these first decreased and then increased, with the lowest at4weeks and thehighest at8weeks.For the gastrocnemius and extensor digitorum longus muscles in theexperimental group, the expressions changed with time, whereas in the control group, thesewere maintained at a certain level. In the experimental group, miRNA-133at1week was thelowest and was always low for all time points, whereas in the experimental group, miRNA-1expression at3days was at a minimum level.The expression of MicroRNA-1/133a in theexperimental group had significant differences than the control group (P <0.05). Conclusion:MicroRNA-1/133a have differrent expression in rat fast and slow denervation muscle atrophy,presumably，It is a key point in the regulation of fast-twitch and slow-twitch muscleaspects.