Matrix Metalloproteinase-1 (MMP-1) Expression in Rat Spinal Cord Injury Model

Matrix metalloproteinase-1 (MMP-1), a member of the matrix metalloproteinases family, plays an integral role in extracellular matrix degradation and has been reportedly involved in the regulation of the brain or spinal cord traumatic neurovascular remodeling. Although the critical involvement of MMP-1 in the metastasis of tumors has been extensively documented, the role of MMP-1 in the pathology of neurological diseases remains largely elusive. In the present study, we established an adult rat spinal cord injury (SCI) model and investigated a potential role of MMP-1 in the pathological process of SCI. Using Western blot analysis, we identified notable expression change of MMP-1 after SCI. Immunohistochemistry showed that MMP-1 was distributed widely in rat spinal cord. Double immunofluorescence staining revealed that MMP-1 immunoreactivity was predominantly increased in neurons and astrocytes following SCI. Moreover, after injury, colocalization of MMP-1/active caspase-3 in neurons (NeuN-positive), and colocalization of MMP-1/PCNA in astrocytes (GFAP-positive) were clearly observed. We also examined the protein expression of PCNA, active caspase-3, Bcl-2, and Bax and found that the expression of the proteins was closely correlated with that of MMP-1. Taken together, our findings indicate that MMP-1 might play an important role in the regulation of neuronal apoptosis and astrocyte proliferation after SCI.