Application of the Chronic Constriction Injury of the Partial Sciatic Nerve Model to Assess Acupuncture Analgesia
LIU Kun1, ZHI Mujun2, ZHENG Zhouli3, HE Xun1, SUN Guang2, ZHANG Meng4, GAO Xinyan1, ZHU Bing1
(1 Department of Physiology, Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China; 2 College of Acupuncture and Moxibustion, Changchun University of Chinese Medicine, Changchun, People’s Republic of China; 3 College of Acupuncture and Moxibution, Shaanxi University of Chinese Medicine, People’s Republic of China; 4 Department of Chinese Medicine, Dongli Hospital of Traditional
Chinese Medicine, Tianjin, People’s Republic of China)
Abstract: Purpose: To validate and explore the application of a rat model of chronic constriction injury to the partial sciatic nerve in investigation of acupuncture analgesia. Methods: Chronic constriction injury of the sciatic nerve (CCI) and chronic constriction injury of the partial sciatic nerve (CCIp) models were generated by ligating either the sciatic nerve trunk or its branches in rats. Both models were evaluated via paw mechanical withdrawal latency (PMWL), paw mechanical withdrawal threshold (PMWT), nociceptive reflex-induced electromyogram (C-fiber reflex EMG), and dorsal root ganglion immunohistochemistry. Electroacupuncture (EA) was performed at GB30 to study the analgesic effects on neuropathic pain and the underlying mechanisms. Results: Following ligation of the common peroneal and tibial nerves, CCIp rats exhibited hindlimb dysfunction, hind paw shrinkage and lameness, mirroring those of CCI rats (generated by ligating the sciatic nerve trunk). Compared to presurgery measurements, CCIp and CCI modeling significantly decreased the PMWL and PMWT. EA at GB30 increased the PMWL and PMWT in both CCI and CCIp rats. Calcitonin gene-related polypeptide and substance expressions were apparently increased in both CCI and CCIp groups, but were not different from each other. The C-fiber reflex EMG of the biceps femoris was preserved in CCIp rats, but it could not be recorded in CCI rats on the 5th day after nerve ligation. The C-fiber reflex EMG was reduced at 0, 1, and 2 minutes after EA in CCIp rats, but only at 0 and 1 minute after EA in normal rats. Conclusion: The CCIp model is better than the CCI model for studying acupuncture analgesiaon chronic neuropathic pain and the underlying mechanisms.
Key words: neuropathic pain, chronic constriction injury, acupuncture, analgesia, C-fiber reflex