Effects of Orally Administered Baclofen in the Animal Model for Neuropathic Pain

Lee, Jung Seok; Yoon, Seok Hwa; Oh, Sae Cheol; Lee, Won Hyung; Kim, Hae Ja; Choi, Sae Jin

Abstract

The aim of this study was to compare with the effects of baclofen using an animal model of neuropathic pain. The sciatic nerve of rats was ligated unilaterally about dorsal half-portion in the tight according to the method of Seltzer and his colleague. After surgical operation, the rats showed painful symptoms of the ipsilateral hind paw, suggesting the possibility of spontaneous pain. And then, the paw withdrawal latency to the local heating on the paw through the glass plate and the frequency of paw withdrawal response to innocuous mechanical stimulation with modified von Frey filaments were determined to compare with the effects of pre-and post-medication of baclofen, respectively, at postoperative 3, 7, and 10 days. The results obtained were as follows: 1) The thermal hyperalgesia and mechanical allodynia produced by partially tight ligation of sciatic nerve appeared continously postoperative 3 days later. 2) In the hyperesthetic rats, the thermal hyperalgesia was inhibited from the 3rd posroperative day with orally administered baclofen 0.2mg and 1.0mg. 3) In the hyperesthetic rats, the mechanical allodynia was inhibited with baclofen 0.2mg, but not with baclofen 1.0mg, These results suggest that baclofen have more specific effects on thermal hyperalgesia than mechanical allodynia.