| Objective:To explore whether the high expression of miRNA-31 can promote the improvement of spinal cord edema after spinal cord injury in mice,so as to provide better help for the mechanism study and clinical treatment of spinal cord edema after SCI.Methods:The main methods are as follows:(1)the DNA was extracted from the tail tissue of mice and the positive expression of miRNA-31 in transgenic mice was identified by PCR reaction in vitro and agarose gel electrophoresis.The positive mice were used in the follow-up experiment and compared with wild-type FVB mice.(2)miRNA-31 transgenic positive mice and wild type FVB mice were randomly divided into normal group,sham operation group and spinal cord injury group.The mice in the normal group did not receive any special treatment;the mice in the sham operation group only opened the vertebral lamina to expose the spinal cord at the target position without spinal cord injury;and the mice in the spinal cord injury group opened the vertebral lamina through surgical operation.expose the target position of the spinal cord,and use the spinal cord injury percussion instrument to hit the spinal cord.Among them,the mice in sham operation group and spinal cord injury group can be divided into 1,3,7,14 and 21 days after operation.The spinal cord water content of each group of mice was measured,and the changes of spinal cord water content were observed.according to the experimental results,the follow-up experiment was carried out.(3)according to the changes of spinal cord water content,miRNA-31 transgenic positive mice and normal FVB mice and 1,3,7 and 14 days after operation in SCI group were selected for Western Blot test to detect the expression level of target protein AQP-4.The blood spinal cord barrier permeability of mice was detected by Evans Blue staining solution,and the changes of AQP-4 protein expression level and blood spinal cord barrier permeability were observed.Results:(1)Among the 75 selected miRNA-31 transgenic mice,70 mice were identified as transgenic positive mice,with a positive rate of 93.3%,which could be used for subsequent experiments.(2)The spinal cord moisture content of miRNA-31 mice and FVB mice was the same in the normal group and the sham group,and there was no difference.For miRNA-31 mice,the spinal cord moisture content of 1 and 3 days after spinal cord injury was higher than that of the normal group(P < 0.05),and the spinal cord moisture content of 7,14 and 21 days after spinal cord injury was lower than that of 1 day after spinal cord injury(P < 0.05),showing no difference compared with the normal group.For FVB mice,the water content of spinal cord 1,3 and 7 days after spinal cord injury was higher than that of normal group(P < 0.05),and the water content of spinal cord 14 and 21 days after spinal cord injury was lower than that of 1 day after spinal cord injury(P < 0.05),and there was no difference compared with that of normal group.(3)Western Blot showed that AQP-4 protein level was increased on day 1 after spinal cord injury,and decreased on day3,7 and 14 after spinal cord injury,and the AQP-4 protein level in miRNA-31 mice was decreased more than that in FVB mice on day 3 and 7 after spinal cord injury(P < 0.05).By Evans Blue dye solution for the detection of blood spinal cord barrier permeability,found for miRNA-31 and FVB mice,mice in normal group,the low permeability of blood spinal cord barrier,1,3 days after spinal cord injury,blood spinal cord barrier permeability increase,for miRNA-31 mice,can be in 7 days after spinal cord injury,make blood spinal cord barrier permeability drops to near normal levels,while FVB mice in 7 days after spinal cord injury,the permeability of blood spinal cord barrier also higher as compared to normal level,to 14 days after spinal cord injury,returned to normal levels.Conclusion:(1)The positive rate of miRNA-31 mice identified in this study reached 93.3%,indicating a high positive rate.The identified miRNA-31 mice can be used for subsequent experiments.(2)The high expression of miRNA-31 is conducive to the decrease of spinal cord water content and the alleviation of spinal cord edema after spinal cord injury.At 21 days after spinal cord injury,the edema of the spinal cord basically disappeared,and the water content of the spinal cord was basically the same as that in normal condition.(3)The high expression of miRNA-31 can promote the decrease of AQP-4 protein level in the recovery period after spinal cord injury and the decrease of blood-cord barrier permeability,which may jointly promote the decrease of spinal cord water content and the reduction of spinal cord edema after spinal cord injury. |
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