| The significance and the expression changes of slit-2 during the spinal cord injury of ratsObjective: To investigate the ethology, morphology and the expression of axon guidance cue slit-2 mRNA changes in different phases of spinal cord hemisection injury, and to explore the effect of slit-2 in axon regeneration of the mammalian central nervous system injury.Materials and Methods: Forty Sprague-Dawley rats were randomly divided into normal group, control operative group and operative group which includes 6 subgroups (1,3,7,14,21,28 days). The spinal cord hemisection injury model was made by cutting the posterior right side spinal cord. Function changes in the right posterior limb were evaluated by BBB method. The general morphology changes were observed by HE stain. The expression of slit-2 mRNA was detected through in situ hybridization methods. The positive cells were analyzed by a computer image analysis system.Results: The limb function of experimental rats significantly recovered from 7d till 28d after injury. The morphology gradually changed from local hematoma to inflammatory cell infiltrate, scar formation and vacuolar degeneration of the distal as well as the proximal spinal cord tissue. The in situ hybridization results indicated that expression of slit-2 mRNA was low and dispersed in either normal or control operative group, but significantly increased at 3d (P＜0.01) in the operative group, then it decreased significantly at 7d and 14d (P＜0.05), and continued expression until 28d. Meanwhile, in 7d group, the expression of slit-2 mRNA was obviously rising up in the reactive hyperplasia cells around the lesion incision.Conclusions: The injury of adult mammalian spinal cord is a dynamic complex course, the axon guidance cue slit may act as a inhibitory role to repel axon regeneration via mediating migration of inflammatory cells, interacting with several neurogen or cues, participating formation of the scar and other probable mechanisms.
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