Professor SMG-SNU Boramae Medical Center, Soul National University, College of Medicine
Introduction: Peripheral nerve injury is one of the most disabling condition. To assess the devices or medications for enhancing neural regeneration, a disease model for simulating human nerve injury is necessary. Here we present the rat model of sciatic nerve cut, crush and stretch injury and time course of recovery.
Methods: Male Sprague Dawley (SD) rats of five weeks of age were used. Crush injury was made by an aneurysm clip for a pre-determined time. Stretch injury was made by spring scale by pre-determined time and weight. The cut injury was made by transection and repair. After a sciatic nerve injury, its function was assessed by compound motor action potential (CMAP), von Frey filament test, grip strength (GS), and extensor postural thrust (EPT) after injury, compared to uninjured side.
Results: The difference in motor function between injured and non-injured sites was greatest at 1 to 2 weeks after injury and decreased after that. Motor function recovered to normal level at 10 to 12 weeks after injury. The recovery pattern of EPT is more variable in stretch injury compared to that of crush and injury. CMAP showed the lowest figure in the second week after injury and then started to recover. Von Frey filament test shows reduced sensory threshold after injury, its value was lowest at 2 weeks after injury, then showed recovery comparable to that of the non-injured site at 10 weeks after injury. Although there are some individual variations, the measure values showed good reproducibility.
Conclusion : This sciatic nerve cut, crush, and stretch injury model showed reliability and reproducibility. The period of great difference between injured and uninjured site might be a good candidate for the application of treatment for accelerated neural regeneration. This study also showed that the best modality of assessment may be different according to the type of injury.
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