Abstract: Objective To investigate the effect of electroacupuncture at Jiaji (EX-B2) points and Stomach Meridian Foot-Yang Ming points on the neurological function and the expression of local Synapsin I in rats after spinal cord injury, and to explore its molecular mechanism. Methods A total of 60 Sprague-Dawley rats were established spinal cord injury model and they were randomly divided into normal control group, Jiaji group and Yang Ming group, with 20 rats in each group. On the third day after operation, Jiaji group and Yang Ming group were treated with electroacupuncture while the normal control group was not. Their neurological function was assessed with BBB every day. Four rats in each group were sacrificed at the end of the 1st, 2nd, 3rd, 4th and 5th week during the intervention period. HE staining was used to observe the morphology of spinal cord. Immumohistochemical staining was used to detect the expression of Synapsin I protein. Reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting was used to detect the content of of Synapsin I mRNA and protein. Results The BBB scores were higher in Jiaji group and Yang Ming group than in the normal control group at all the time points (P < 0.05), and were higher in Yang Ming group than in Jiaji group from one to three weeks (P < 0.05). The immunohistochemical scores of Synapsin I protein were higher in Jiaji group than in the normal control group in the first week (P < 0.05), and were higher in Yang Ming group than in the normal control group from one to four weeks (P < 0.05). The immunohistochemical scores of Synapsin I protein were higher in Yang Ming group than in Jiaji group from three to four weeks (P < 0.05). The expression of Synapsin I mRNA and protein first increased and then decreased in the normal control group; which was higher in Jiaji group than in the normal control group in the first week (P < 0.05) and was higher in Yang Ming group than in the normal control group from one to four weeks (P < 0.05). The Synapsin I mRNA expression in the third week and the Synapsin I protein expression from two to three weeks was higher in Yang Ming group than in Jiaji group (P < 0.05). Conclusion Electroacupuncture at both Jiaji points and Stomach Meridian Foot-Yang Ming points promote the recovery of nerve function in rats with spinal cord injury. It may be related to the elevated level of Synapsin I in the damaged parts of the spinal cord.

Key words: spinal cord injury, electroacupuncture, Jiaji points, Stomach Meridian Foot-Yang Ming points, neurological function, Synapsin I, rats