Expression Of MicroRNA-124a In Injuried Spinal Cord Of Rats And Its Correlation With Calpain1

Objective: To investigate and analyse the expression of microRNA-124a in injuriedspinal cord of rats and its correlation with calpain1, and provide experimentalevidence for exploring therapeutic targets of spinal cord injury.Method: Sprague-Dawley rats were subjected to acute spinal cord injury with themodified Allen methods.108adult SD rats were assigned randomly to blank controlgroup and SCI groups. Rats in SCI groups were subjected T10spinal cord andallowed to survived6h，12h，24h，3d and7d. Neurologic function score of hindlimb(BBB grade) was observed after operation. The expression and location ofmiRNA-124a and calpain1gene were determined by using real time RT-PCR and insitu hybridization(each time point) technique.Result:1BBB grade: Compared with group A, the BBB grade of group B was significantlylower(P<0.05).2HE staining: Spinal cord in group A is normal, and group B shows obvious injuriedspinal cord of rats. Extensive neuronal edema appears at6hours after SCI. Theprimary pathological change in the period of12hours to24hours after SCI isneuronal necrosis and acute inflammatory reaction; and increased vascularpermeability and abundant inflammatory-cell infiltrate can be observed in the periodof24hours to7days after SCI.3Real-time PCR: Compared with group A, the relative expression of miRNA-124ain group B is significantly lower, and the relative expression of calpain1in group Bwas significantly higher than that of the blank control samples(set at1.000, P<0.05)except the point of7days after SCI(P>0.05). There was a negative correlationbetween the expression of miRNA-124a and calpain1in injuried spinal cord of rat (r=-0.89，P<0.05). 4In Situ Hybridization(ISH): miRNA-124a mainly distributed in group A and thepoint of7days after spinal cord injury, especially in ventral horn motor neurons.Calpain1mRNAs mainly distributed in the period of6hours to3days after spinalcord injury, also in ventral horn motor neurons.Conclusion: The expression of miRNA-124a gene is significantly decreased afterspinal cord injury, and calpain1is elevated. There is a negative correlation betweenthe expression of miRNA-124a and calpain1after SCI. The expression of calpain1may be regulated by miRNA-124a.