Polyaniline promotes peripheral nerve regeneration by enhancement of the brain-derived neurotrophic factor and ciliary neurotrophic factor expression and activation of the ERK1/2/MAPK signaling pathway

A previous study has demonstrated a progression in the nerve regeneration by polyaniline/cellulose (PANI/RC), although the underlying mechanism was not elucidated. In the present study, regenerated nerves were investigated, using histological techniques, functional assays and western blot analysis. The triceps surae muscle weight ratio percentages of the sham, regenerated cellulose (RC) and the PANI/RC groups were 38.88 +/- 4.76 and 76.32 +/- 7.11%, respectively. The thickness of the myelin sheath for the aforementioned groups were as follows: 1.2 +/- 0.27; 0.49 +/- 0.21 and 0.93 +/- 0.28 mu l. Western blot analysis demonstrated that the ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) were highly expressed in the regenerated nerve in the presence of polyaniline. Phosphorylated extracellular kinase (p-ERK)1/2 expression in the PANI/RC group was significantly elevated compared with the RC group (1.83-fold) and the sham group (4.92-fold). The expression of the axon sprout-associated proteins, such as Tau, alpha-tubulin and growth associated protein-43, were increased (1.64, 1.59 and 1.24-fold, respectively) compared with the RC group. The results demonstrated that PANI enhances the expression and secretion of BDNF and CNTF, activates the ERK1/2 signaling pathway and increases the expression levels of the GAP-43, Tau and alpha-tubulin, suggesting an insight into nerve regeneration and possible clinical interventions in nerve injury.