Tumour necrosis factor-alpha has few morphological effects within the dorsal columns of the spinal cord, in contrast to its effects in the peripheralnervous system

There is circumstantial evidence implicating the pro-inflammatory cytokine tumour necrosis factor (TNF) in the pathogenesis of multiple sclerosis (MS) , but there is no direct evidence that TNF can produce demyelination in the central nervous system (CNS). We demonstrate here that single injections o f TNF into the dorsal columns of adult rats produced a mild inflammatory re sponse indistinguishable from that seen in control cords, but did not induc e demyelination. A similar response was seen when TNF-alpha was injected in to dorsal columns where central axons had been remyelinated by Schwann cell s. In marked contrast, single intraneural injections of TNF into sciatic ne rves produced acute changes in the endoneurial microvascular bed that were followed by demyelination and degeneration. (C) 2000 Elsevier Science B.V. All rights reserved.