Neural Regeneration Research ›› 2012, Vol. 7 ›› Issue (18): 1378-1385.

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The cumulative analgesic effect of repeated electroacupuncture involves synaptic remodeling in the hippocampal CA3 region

Qiuling Xu1, Tao Liu1, Shuping Chen2, Yonghui Gao2, Junying Wang2, Lina Qiao2, Junling Liu2   

  1.  
    1  Hainan Medical University, Haikou 571101, Hainan Province, China
    2  Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
  • Received:2012-02-22 Revised:2012-05-03 Online:2012-06-25 Published:2012-06-25
  • Contact: Junling Liu, Professor, Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China junling_liu@yahoo.cn
  • About author:Qiuling Xu☆, M.D., Asso-ciate professor, Hainan Medical University, Haikou 571101, Hainan Province, China

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Abstract:

In the present study, we examined the analgesic effect of repeated electroacupuncture at bilateral Zusanli (ST36) and Yanglingquan (GB34) once a day for 14 consecutive days in a rat model of chronic sciatic nerve constriction injury-induced neuropathic pain. In addition, concomitant changes in calcium/calmodulin-dependent protein kinase II expression and synaptic ultrastructure of neurons in the hippocampal CA3 region were examined. The thermal pain threshold (paw withdrawal latency) was increased significantly in both groups at 2 weeks after electroacupuncture intervention compared with 2 days of electroacupuncture. In ovariectomized rats with chronic constriction injury, the analgesic effect was significantly reduced. Electroacupuncture for 2 weeks significantly diminished the injury-induced increase in synaptic cleft width and thinning of the postsynaptic density, and it significantly suppressed the down-regulation of intracellular calcium/ calmodulin-dependent protein kinase II expression in the hippocampal CA3 region. Repeated electroacupuncture intervention had a cumulative analgesic effect on injury-induced neuropathic pain reactions, and it led to synaptic remodeling of hippocampal neurons and upregulated calcium/calmodulin-dependent protein kinase II expression in the hippocampal CA3 region.

Key words: chronic neuropathic pain, acupuncture analgesia, cumulative effect, synaptic plasticity, hippocampal CA3 region, calcium/calmodulin-dependent protein kinase II, neurobiology, electroacupuncture, neural regeneration