Protease-activated Receptor-2(PAR2) Regulates Glial Scar Formation Via C-jun N-terminal Kinase(JNK)

Objective：Explore the role of PAR2in glial scar formation afterspinal cord injury and the function of JNK signal in it.Methods(1) The Rivlin and Tator’s acute extradural clip compressioninjury(CCI) model was used for producing severe SCI. The adult female SDrats can be divided into four groups according to processing factors: shamoperation group; model group; PAR2inhibitor FSLLRY-NH2group andPAR2agonist SLIGRL-NH2group.(2) The rats were sacrificed after BBB score of rat hind limbs motorfunction at the1st day,7th day,14th day and28th day. Western blottingtechnique was performed to detect the expression of GFAP, Vim and p–JNK in the lesion site. The expression of GFAP in the lesion site wasdetected by immunofluorescence technique to assess the degree of reactiveastrogliosis. Double-immunofluorescence of GFAP and tubulin β wasperformed to evaluate the glial scar formation and residual neurons.(3) With the same model of SCI, the rats can be divided into four groups according to processing factors: sham operation group; model group; PAR2inhibitor FSLLRY-NH2+JNK agonist Anisomycin group and PAR2agonist SLIGRL-NH2+JNK inhibitor SP600125group.(4) The rats were sacrificed after BBB score of rat hind limbs motorfunction at the1st day,7th day,14th day and28th day. Western blottingtechnique was performed to detect the expression of GFAP, Vim and p–JNK in the lesion site.Results(1) Compared with model group, the expression of GFAP and Vim inFSLLRY-NH2group at the7th day,14th day and28th day after SCI and theexpression of p-JNK at the1st day,7th day and14th day after SCI weresignificantly lower. The rat hind limbs motor function improvedsignificantly at the7th day,14th day and28th day after SCI and the glial scarformation was abated at the28thday after SCI. In SLIGRL-NH2group, theexpression of GFAP and Vim at the7th day,14th day and28th day after SCIand the expression of p-JNK at the1st day,7th day and14th day after SCIwere significantly increased. The rat hind limbs motor function becameworse significantly at the7th day,14th day and28th day after SCI and theglial scar formation was enhanced at the28thday after SCI.(2) Compared with model group, the expression of GFAP and Vim inSLIGRL-NH2+SP600125group at the7th day,14th day and28th day afterSCI and the expression of p-JNK at the1st day,7th day and14th day after SCI were significantly lower. The rat hind limbs motor function improvedsignificantly at the7th day,14th day and28th day after SCI. InFSLLRY-NH2+Anisomycin group, the expression of GFAP and Vim at the7th day,14th day and28th day after SCI and the expression of p-JNK at the1st day,7th day and14th day after SCI were significantly increased. The rathind limbs motor function became worse significantly at the7th day,14thday and28th day after SCI.Conclusions: PAR2can regulate the expression of GFAP and Vim,the glial scar formation and the functional recovery of rat hind limbs via JNKsignal in the lesion site after SCI.