Analysis Of MRNA Expression Differences After Overuse Of Supraspinatus Tendon In Rats

Purpose:To detect the gene expression of supraspinatus tendon under overuse in rats by the High-throughput gene sequencing technology,and to study the characteristic changes and potential markers of supraspinatus tendon overuse.Methods:Sixteen 3-month-old SPF male SD rats(Sprague Dawley)were randomly divided into the control group(group C,n=8)and the 16-week exercise group(group ES,n=8).Group C rats were free in the cage.The ES group ran downhill with a slope of-10° and a speed of 17 meters/min,once a day,for 1 hour each time,5 days a week,for 16 weeks.Samples were collected 48 hours after the completion of training.Paraffin sections of supraspinatus tendon of 4 rats in each group were prepared for HE staining and immunohistochemical staining.MRNA expression in the right supraspinatus tendon of the remaining 4 rats was analyzed by rna-seq technique.Results:Results of HE staining showed that,compared with group C,the middle area of the tendons of rats in group ES showed disordered arrangement,with larger and rounded cells.Analysising the difference of gene sequencing results showed that the expression difference multiple |log2Fold Change| > 1,with significant p-value <0.05.There were 182 significant differences in gene expression between group ES and group C,of which 91 were up-regulated and down-regulated.Enrichment analysis of GO and KEEG showed that differentially expressed mrnas were mainly related to extracellular matrix,inflammatory factors and angiogenic factors.The expression of tenascin-c(TNC)was significantly increased,while the expression of inflammatory and angiogenic-related factors was decreased.The results of immunohistochemical qualitative analysis showed that the expression of TNC protein presented an increasing trend.The inflammatory factor TNF was slightly expressed in both groups,while the sox-9index was mainly expressed in the proximal humerus head of the tendon.Conclusions:1.After running downhill for 16 weeks,the cells of supraspinatus tendon of the rats became larger and rounded,the tendon fibers were disordered and partially torn,suggesting that the supraspinatus tendon overuse model was successfully established.2.The results of gene sequencing showed that the supraspinatus tendon showed significant differences in the expression of 182 genes under the condition of overuse,among which 91 genes were up-regulated and 91 genes were down-regulated.3.The expression of TNC gene was significantly increased,and the expression of some inflammatory factors and angiogene-related factors was decreased.The regulatory mechanism of TNC under the condition of overuse of tendons needs to be further studied.4.No changes in expression of sarbox-9 and aggrecan,etc.were observed in the tendons after overuse.