Expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in sciatic nerves after chronic constriction injury

Abstract

Objective To investigate the expression of matrix metalloproteinase-9 ( MMP-9 ) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in the sciatic nerve after chronic constriction injury.Methods Ninety male SD rats were divided into control group and constriction group randomly.The chronic sciatic nerve constriction injury model was made by Mackinnon method in the constriction group.Reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry staining techniques were applied to detect the expression of MMP-9 and TIMP-1 in the sciatic nerve.Results After chronic constriction injury of the sciatic nerves,demyelination occurred in the nerve fibers at the 2nd week ; at the 4th week,there was obvious hyperplasia of connective tissue; after 12 weeks,fibrous separations were increased in the nerves progressively,and fibrosis occurred in the constricted nerve.During the early phase of the constriction,the expression of MMP-9 and TIMP-1 was increased,MMP-9 mRNA reached the peak at the 2nd week by 0.0485,and TIMP-1 at the 10th week by O.1592,MMP-9/TIMP-1 was increased.As time prolonged,the expression of MMP-9 was significantly reduced while TIMP-I was elevated continuously; MMP-9/TIMP-1 was decreased evidently.Conclusion Chronic constriction injury causes the peripheral nerve fibrosis,which is related to the abnormal changes of MMP-9/TIMP-1. Key words: Peripheral nerve; Chronic constriction injury; Matrix metalloproteinase-9; Tissue inhibitor of matrix metalloproteinase-1; Fibrosis