Abstract: Objective To investigate the influence of matrix metalloproteinases-9 (MMP-9) on permeability of blood-spinal cord barrier (BSCB) after spinal cord injury (SCI). Methods 68 male C57BL/6 mice were randomly divided into sham group, 2 days group (S2), 7 days group (S7) and 14 days group (S14) after SCI with 17 mice in each group. All the groups received a moderate impacted spinal cord injury except the sham group. Evan's Blue (EB) was administered intraperitoneally to detect the permeability of BSCB. Occludin was analyzed by immunofluorescence, the expressions of occludin and MMP-9 were detected by Western blotting. Results After SCI, BMS score significantly reduced, compared with S2 group, S14 group showed a significant increase (P<0.01). The permeability of BSCB was seriously damaged after SCI. Compared with S2 group, S14 group showed a notable down-regulation in the permeability of injured micro-vessels (P<0.05). The expression of occludin was down-regulated and the expression of MMP-9 was up-regulated 7 days after SCI (P<0.05). Compared with S2 group, S14 group showed a significant up-regulation of occludin and a remarkable down-regulation of MMP-9 (P<0.05). Conclusion After SCI, MMP-9 might mediate the expression of occludin to influence the BSCB permeability.

Key words: spinal cord injury, blood-spinal cord barrier, matrix metalloproteinases-9, occludin, mice