Berberine promotes nerve regeneration through IGFR-mediated JNK-AKT signal pathway

Berberine presents therapeutic ability for various central nervous system disorders, including Alzheimer's disease and cerebral ischemia. The present study investigated the role of berberine in nerve regeneration and analyzed the potential mechanism mediated by berberine in hippocampal pyramidal neurons. Reverse transcription-quantitative poylmerase chain reaction, western blot, TUNEL assay and immunofluorescence were used to analyze the therapeutic effects of berberine on nerve regeneration. Berberine treatment increased growth and viability of hippocampal pyramidal neurons. Berberine treatment inhibited apoptosis of hippocampal pyramidal neurons and increased apoptosis regulator Bcl-2 and Bcl-w expression. Neuroinflammation of tumor necrosis factor α, interleukin (IL)1β, IL6 levels and autophagy-related proteins microtubule-associated proteins 1A/1B light chain 3B, autophagy related 16 like 1 and autophagy related 7 were downregulated by berberine treatment in hippocampal pyramidal neurons. Notably, study has found that berberine increased insulin-like growth factor receptor (IGFR) and decreased c-Jun N-terminal kinase (JNK) and protein kinase B (AKT) expression in hippocampal pyramidal neurons. IGFR antagonist abolished berberine-increased growth of hippocampal pyramidal neurons. In conclusion, these results indicate that berberine can promote nerve regeneration through IGFR-mediated JNK-AKT signal pathway.