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[Effect of urokinase plasminogen activator on injured facial nerve of rats].

OBJECTIVE
To observe the effect of uPA on nerve regeneration and the expression of fibronectin and laminin after the facial nerve were transected and anastomosed, and to explore the mechanism of uPA in the microenvironment of nerve regeneration.


METHOD
Twenty four SD rats were randomly divided into two groups: uPA group and control group. Every rat's extracranial facial were transected and anastomosed. Then uPA were injected at the belly of rat subcutaneously for five days in uPA group, three times one day, 5000 U/kg one time. Equal volume saline were injected in control models at the same site and the same time. At 1, 7, 21, 42, 84 day of post-operation, the diameter, perimeter, myelin sheath area of fibers and the expression of fibronectin and laminin in early phase of post-operation were measured by using morphometry, immunochemistry and the image analysis.


RESULT
After operation, myelin sheath area at 21, 42 day and diameter of new regenerated fiber at 42 day in uPA group were better than those in control group (P<0.05). The expression of fibronectin elevated gradually after operation, and it expressed more than that of control group at 14 and 21 day (P<0.05). The expression of laminin decreased after operation, then elevated with the progress of nerve regeneration and showed no significant difference between two groups.


CONCLUSION
The uPA can promote the fibrin degradation and upregulate the fibronectin expression when applicating in rat model, which benefit to improve the microenvironment and enhance facial nerve regeneration.