Expression of constitutive endothelial and inducible nitric oxide synthase in the sciatic nerve of Lewis rats with experimental autoimmune neuritis

This study examined the expression of constitutive endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) in the sciatic nerve of Lewis rats with experimental autoimmune neuritis (EAN). Western blot analysis showed that both eNOS and iNOS expressions in the sciatic nerves of rats increased significantly during the peak stage of EAN, but declined thereafter. Only minimal amounts of these enzymes were identified in normal rat sciatic nerves. Immunohistochemical studies showed that eNOS was increased in vascular endothelial cells and Schwann cells, but not in inflammatory cells, during the peak stage of EAN. However, iNOS was found mainly in inflammatory macrophages in sciatic nerve EAN lesions. These findings suggest that, depending on the stage of peripheral nervous system autoimmune disease, the increased expressions of both eNOS and iNOS might be involved in either the production of detrimental effects during the induction stage of EAN or in the recovery from EAN paralysis. (C) 2002 Elsevier Science B.V. All rights reserved.