Impaired nerve regeneration and Schwann cell activation after repair with tension.

The aim was to investigate the relation between axonal outgrowth (neurofilaments) and Schwann cell activation (activating transcription factor 3) and apoptosis (caspase 3) 10 days after nerve repair with no, minor (3 mm defect) and moderate (6 mm defect) tension in rat sciatic nerve using immunohistochemistry. After repair with no tension, axons grew 11.75 mm, but repair with minor and moderate tension impaired axonal outgrowth by 29 and 48%, respectively, with a reduced number of activating transcription factor 3 stained and an increased number of caspase 3 stained Schwann cells. Axonal outgrowth correlated with activation of and inversely with apoptosis of Schwann cells. Tension induces impaired activation of Schwann cells, and a higher amount of apoptotic Schwann cells, with a subsequent deteriorated axonal outgrowth