Cuff electrode implantation around the sciatic nerve is associated with an upregulation of TNF-α and TGF-β1

Epineurial fibrosis, fiber loss, limited reproducibility of recordings and variability of stimulation conditions have been documented after extraneural cuff electrode implantation. These morphological and electrophysiological modifications could be due to the local release of cytokines. We report the expression of two cytokines, tumor necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β1) in the rat sciatic nerve after 'cuff' implantation for 18 h, 7 days and 1 month. Immunohistochemical and Western blot analyses showed a transient upregulation of TNF-α, during the first week, and a prolonged increase of TGF-β1, over the 1-month period duration of this study. Considering the known pro-inflammatory roles of TNF-α and the pro-fibrotic action of TGF-β, our results strongly suggest that these cytokines may contribute to nerve alterations occurring within the acute and sub-acute phases after cuff electrode implantation.