[Expression of mRNA, interleukin-1 beta, interleukin 6 and tumor necrosis factor-alpha during regeneration of the sciatic nerve in rats after tissue loss]

Within the family of proinflammatory cytokines, some exhibit a neurotrophic activity in addition to their proinflammatory functions. However, their role in peripheral nerve regeneration processes is still poorly understood. This study presents the kinetics of expression of mRNAs for different cytokines, IL-1 beta, IL-6, TNF alpha and that of NGF included as control. It was carried out on the rat sciatic nerve regeneration using two models of nerve transection with a 7 mm loss of substance. Nerve regeneration took place through an autologous nerve grafting in the first model, and through a collagenous cylinder in the second one. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to quantify each mRNA of cytokine and that of actin beta gene considered as an endogenous internal standard. The results showed a peak in the expression of IL-1 beta mRNAs in both models at D2 (second bay after operation). This D2-peak was also observed for TNF alpha and IL-6, but only in the model of the cylinder. The level of IL-6 D2-peak was very high compared to the nearly complete absence of IL-6 mRNAs expression in non operated control nerves. According to these results, proinflammatory cytokines and especially IL-6 may play a major role in promoting peripheral nerve regeneration.