Treatment with cyclosporine A promotes axonal regeneration in rats submitted to transverse section of the spinal cord.

The abortive axonal regeneration in the central nervous system (CNS) of mammals has been attributed to a series of inhibitory factors. Previous reports suggest the development of autoimmune reactions following CNS lesion in mammals. In this study we investigated whether immunosuppressive treatment with cyclosporine A is able to facilitate axonal regeneration in rats submitted to complete transverse section of the spinal cord at the level of T7-T8. Treated animals received daily subcutaneous injections of cyclosporine A (2.5 mg/kg), while control rats were given a similar treatment with saline. Immunosuppression was begun immediately after spinal cord transection. Strong evidence of morphological axonal regeneration was observed 15 days after surgery in all cyclosporine A treated animals. Furthermore, treatment with cyclosporine A markedly reduced the seric immune reaction elicited by the lesion. The results of this study, although preliminary, provide further evidence for the development of autoimmune processes following lesion in the CNS, and suggest that blocking of the immune reaction facilitates axonal regeneration in the rat.