Neuropathic Pain Model Induced by Electrical Injury of Sciatic Nerve in Rats

Lee, Yang Soo; Lee, Ki Hoon; Kim, Young Eun; Jung, Tae Du; Kim, Poong Taek

Abstract

OBJECTIVE
The purpose of this study was to develop a new neuropathic pain model in rat. METHOD: Twenty Sprague-Dawley adult male rats, 10 for control and 10 for experimental, were anesthetized and their sciatic nerves were exposed. In an experimental group, exposed nerve was injured with 10 volts electrical current for 10 seconds. The mechanical and thermal allodynia and pain behavior were evaluated in pre-electrical injury and post-injury 1, 2, 3 days, 1, 2, 3, 4, 6 and 8 weeks. The mechanical allodynia was evaluated by the frequency of response to 5 stimulations of von Frey hairs (4.31 and 4.56) and the thermal allodynia was tested by withdrawal latency to stimulation with radiant heat. Spontaneous pain behavior (paw shaking, paw elevation) was observed for 5 minutes in the cage.
RESULTS
The experimental group exhibited significantly higher withdrawal frequency to mechanical stimulation: from post-injury 3 days to 6 weeks for von Frey hair 4.31 and from 2 days to 4 weeks for von Frey hair 4.56 (p<0.05). There was no difference between two groups in withdrawal latency to radiant heat stimulation. The experimental group showed spontaneous pain behavior but control group did not. In electron microscopic finding, prominent myelin destruction and axonal sprouting were observed in experimental group.
CONCLUSION
These results suggest that a new neuropathic pain model can be made by 10 volts electrical injury for 10 seconds to rat sciatic nerve.