Changes Of MicroRNA-221 And PTEN Expression In Stump Nerve Tissues After Sciatic Nerve Injury Among Rats

ObjectiveTo study the expression of micro RNA-221 and the protein of phosphatase and tension protein homologue in the proximal and distal rupture ends after sciatic nerve injury in rats,and their correlation with the repair of peripheral nerve injury,so as to provide a new target for clinical diagnosis of peripheral nerve injury.Methods96 SPF male SD rats were used to establish sciatic nerve injury model.Twenty-four rats were sacrificed on postoperative day 0(control group,0 d)and postoperative days 1,4 and 7(experimental group,1d,4d and 7d).The proximal and distal rupture ends of sciatic nerve were taken under aseptic conditions.Rating neurological function by SFI.The expression of miR-221 was detected by real-time quantitative PCR,and the expression of PTEN was detected by Western blot.Pathological analysis of sciatic nerve stump tissue by HE staining and immunofluorescence.The relationship between miR-221 and PTEN was verified by dual-luciferase reporter gene.At the same time,the ultrastructure of nerve tissue was observed by transmission electron microscopy.ResultsThe results of real-time quantitative PCR and Western blot showed that the relative expression of miR-221 in the proximal and distal rupture ends of sciaticnerve of rats increased gradually,and the relative expression of PTEN protein decreased gradually.The difference between the experimental group and the control group had statistical significance(P<0.05).The differences between each of the two experimental groups were statistically significant(P<0.05).The relative expression of miR-221 in the proximal end of nerve tissue in each experimental group was higher than that in the distal end of the same group,the relative expression of PTEN protein was lower than that in the distal end of the same group.There were significant differences between the proximal end and distal end of the same group(P<0.05).And SFI score shown,the experimental group and the control group showed no significant difference(P>0.05).Dual-luciferase reporter gene suggests that PTEN is the target for miR-221.HE staining and immunofluorescence staining shows significant pathological change of Comparative experimental group and control group.The results of transmission electron microscopy showed that the normal morphology of the control group was normal.The proliferation of Schwann cells and the degeneration of axon and myelin were increased with time in each experimental group.Compared with the distal and proximal rupture ends,there was no significant difference in the 1d group.The Schwann cell proliferation of the proximal rupture ends was more than that of the distal fracture ends in the 4d and 7d groups,and the degree of degeneration of axons and myelin sheaths was less.ConclusionsAfter sciatic nerve injury in rats,the expression of miR-221 is up-regulated and the expression of miR-221 and PTEN in proximal and distal rupture ends is decreased,which may play a certain role in promoting the repair of peripheral nerve injury.