| The Gene Expression of Dynorphin, Enkephalin, c-Fos in the Neuropathic Rat. |
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Neung Hee Han, Won Hyung Lee, Won Jae Hwang, Sug Hwa Yoon, Yong Sup Shin, Soo Chang Son, Hye Ja Kim, Sae Jin Choi, Kyu Lim, Byung Doo Hwang |
1Department of Anesthesiology, School of Medicine, Chungnam National University, Taejeon, Korea.
2Department of Biochemistry, School of Medicine, Chungnam National University, Taejeon, Korea. |
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| Abstract |
BACKGROUND
We studied the time course of gene expression of dynorphin, enkephalin, c-fos, and the changes of allodynia, and the effect of chemical sympathectomy on the gene expression and allodynia in neuropathic rat.
METHODS
In two groups of rat (Sprague-Dawley), the left L5 and L6 spinal nerves were tight ligated. In gene expression group (N=25), behavioral tests for mechanical allodynia and cold allodynia were perfomed for the next two weeks. After the test of allodynia, the expression of dynorphin, enkephalin, c-fos were assessed by Northern blot hybridization. In chemical sympathectomy group (N=16), after chemical sympathectomy (guanethidine 70 mg/kg intraperitoneally, from postoperative 7 days to 9 days), the changes of allodynia and the gene expression of enkephalin, c-fos were tested.
RESULTS
Mechanical allodynia and cold allodynia was developed on the postoperative 3, 5, 7, 14 days.
Preprodynorphin mRNA expression was reached peak level at the postoperative 8 hrs, sustained increase by the postoperative 3 days, but preproenkephalin mRNA expression increased slightly after operation. c-Fos mRNA expression was increased immediately at the postoperative 30 min, 1 hr, returned to normal level thereafter, and increased again on the postoperative 3, 5, 7 days that neuropathic pain was developed. Mechanical allodynia and cold allodynia were decreased by chemical sympathectomy. The increased c-fos mRNA expression and pain at postoperative 7 days was reduced by chemical sympathectomy.
CONCLUSION
These results suggest that the transient gene expression of dynorphin and c-fos after tight ligation of L5 and L6 spinal nerves induces the development neuropathic pain, and late c-fos expression is related to neuropathic pain. |
| Key Words:
neuropathic pain; c-fos; dynorphin; enkephalin |
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