Steroid Hormones After Sciatic Nerve Injury, Spinal Cord Anterior Horn Motor Neuron Repair

Objective: To establish animal model,and study the morphologic changes of anterior horn motor neurons of spinal cord induced by Dexamethasone,and the effect of Dexamethasone on the expression of bFGF and CGRP on the anterior horn motor neurons of spinal cord following sciatic nerve injury in adult rats.Methods: Wistar rats were randomly divided into 4 groups. In nerve injury group, the sciatic nerve injury model was established by clamping the nerve in the right. In dexamethasone group,the dexamethasone was immediately applied to injury side 0.5mg/kg/d. In saline group, after sciatic nerve injury ,the saline was applied to the injury side instead of dexamethasone. Rats without any treatment. The L4-L6 spinal cord were removed,the morphologic changes of anterior horn motor neurons were observed with light microscope and TEM sections stained with immunohistochemistry to observe theexpression of bFGF and CGRP anterior horn motor neurons of spinal cord.ResuIts:(1).Morphologic observation show that in nerve injury group,the number of neuron and Niss1 bodies decreased and the neurons become smaller. Loose rough endoplasmic arranged loosely reticulum there were some swelling mitochondria with fractured crest. But in dexamethasone group,the number of neuron increased , and Niss1 bodies gave almost normal morphological appearance, and ultrastructure of neuron was improved greatly. (2). In nerve injury group the expression of bFGF and CGRP in anterior horn motor neurons increased slightly. Dexamethasone group gave more positive result of bFGF and CGRP, cytoplasm is deeply stained.Conclusion (1).Dexamethasone can stabilize and recover the structure of neuron. (2).Dexamethasone increase the expression of bFGF in neuron of spinal cord after sciatic nerve injury,the effect of bFGF can protect neuron in the early time, CGRP may be one of the important factors protecting in nervous system from injury. Dexamethasone increase the expression of CGRP in anterior horn motor neuron of spinal cord,it is maybe one of way in promoting the recovery of injuryed neurons.