| Objectives To observe the changes of miRNA-1 and miRNA-133 in myocardium at the early stage after high level spinal cord injury(SCI)in rats,and to explore how miRNA-1 and miRNA-133 work in the apoptosis of myocardial cells after SCI and to investigate whether it is one of the mechanisms of myocardial injury in rats with high spinal cord injury.Methods1.Foty-two healthy male Sprague-Dawley rats,8-10 weeks old,weighing 250-300 g,were divided into seven groups randomly(n=6): the control check group(CK group),the sham operation control group(Sham group),4 h after high spinal cord injury group(SCI 1 group),12 h after high spinal cord injury group(SCI 2 group),24 h after high spinal cord injury group(SCI 3 group),36 h after high spinal cord injury group(SCI 4group)and 48 h after high spinal cord injury group(SCI 5 group).2.Using the modified Allen’s combat method to model the high-level SCI rats,and the Sham group did not strike after exposing the spinal cord.Observing the postoperative performance and the limb movement of rats and using Basso-Beattie-Bresnahan(BBB)scoring method to score,and myocardial tissue from the same part were taken for detection.3.Ultrastructural changes of myocardial cells were observed by transmission electron microscopy.4.TUNEL assay was used to detect the apoptosis of myocardial cells.5.The expression of miRNA-1 and miRNA-133 in myocardial tissue were determined by fluorescence quantitative PCR.6.The expression of HSP60,Bcl2,Bax and Caspase-9 in myocardial tissue were determined by Western blot assay.Results1.Postoperative limb mobility of rats in the Sham group were normal,and BBB scores were 21 points,and the difference was not significant compared with that in the CK group(P > 0.05).In SCI groups,the intraoperative shock point were grey,postoperative activity and food intake were significantly reduced,flaccid paralysis were observed in both lower extremities,and BBB scores were close to 0,the difference was significant compared with the Sham group(P < 0.05).2.Transmission electron microscopy results showed that the myocardial ultrastructure of the rats in Sham group was intact like CK group.While the myocardial ultrastructure in SCI group changed a lot,including myofibrillolysis,sarcoplasmic reticulum dilation,lysosome increasing,organelle structure destruction,cell swelling and even rupture.3.The results of TUNEL assay showed that,there was no obvious difference in apoptosis rate of myocardial cells between the Sham group and the CK group(P > 0.05).The apoptosis rate of myocardial cells in SCI groups were increased comparing with the Sham group,and SCI 3 group,SCI 4 group and SCI 5 group were statistically significant(P < 0.05).4.The results of PCR showed that,Compared with CK group,miRNA-1 and miRNA-133 in Sham group were not significantly different(P > 0.05).The relative expression of miRNA-1 in SCI 2 group and SCI 5 group were significantly increased Comparing with the Sham group.And the relative expression of miRNA-133 in SCI 1group,SCI 2 group and SCI 3 group were significantly increased(P < 0.05).5.The results of Western blot showed that the expression of HSP60,Bcl2,Bax and Caspase-9 in myocardial tissue were no significant difference between Sham group and CK group(P > 0.05).Compared with the Sham group,the content of HSP60 in the myocardial tissue of SCI 1 group,SCI 2 group,SCI 3 group and SCI 4 group were decreased and the expression of Bcl-2 in the myocardial tissue of SCI 1 group,SCI 2group and SCI 3 group were significantly decreased too,while the expression of Bax and Caspase-9 in the myocardial tissue of SCI 1 group,SCI 2 group and SCI 3 group were increased,with significant differences(P < 0.05).Conclusion1.The ultrastructural changes of cardiomyocyte appeared in the early stage after high level spinal cord injury in rats,which was closely related to apoptosis.2.After high level spinal cord injury,the expression of miRNA-1 and miRNA-133 in myocardial tissue were increased in the early stage.And miRNA-1 may target HSP60 to promote the decrease of Bcl-2 and the increase of Bax to promote apoptosis,while miRNA-133 inhibits the apoptosis of myocardial cells to protect the myocardium. |
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