Increased collapsin response mediator protein 2 in spinal cord neurons promotes axon regeneration after brachial plexus injury

Abstract

Objective To research the expression and effects of collapsin-response-mediator-protein 2 (CRMP2) in rats spinal cord after brachial plexus injury. Methods The rat model of brachial plexus avulsion was made. The spinal cord was harvested at the 1st, 3rd, 7th, 10th day post-operation. The expression and phosphorylation of CRMP2 were tested using real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) and Western blotting. The spatial expression of CRMP2 in spinal cord was tested using immuno-fluorescence method. Further in vitro, CRMP2 was regulated using adenovirus and the effects on axon regeneration were evaluated. Results After 1, 3, 7, 10 days of brachial plexus avulsion, using RT-qPCR and Western blotting, the expression of CRMP2 was significantly increased. On the 3rd and 7th day post-operation, the level of phosphorylation CRMP2 was 0.154±0.113 and 0.124±0.200 in BPI group, while it was 0.342±0.200 and 0.434±0.165 in sham group. The level of phosphorylation CRMP2 was decreased in BPI group. In the spinal cord, CRMP2 was expressed in neurons but not in astrocytes and microglia. In vitro, the length of axon and number of dendrites was 7.066±1.762 and 24.500±8.816 in up-regulated group, while it was 1.044±0.556 and 8.000±3.295 in down-regulated group. Up-regulated CRMP2 resulted in longer axon and more dendrites of neurons. Conclusion After brachial plexus avulsion, increased CRMP2 in spinal cord neurons can promote axon regeneration, which benefits to function recovery. Key words: Brachial plexus injury; Collapsin response mediator protein 2; Spinal cord neurons; Rats