%0 Journal Article
%T Intrathecal lidocaine pretreatment attenuates immediate neuropathic pain by modulating Nav1.3 expression and decreasing spinal microglial activation
%A Kuang-I Cheng
%A Chung-Sheng Lai
%A Fu-Yuan Wang
%A Hung-Chen Wang
%A Lin-Li Chang
%A Shung-Tai Ho
%A Hung-Pei Tsai
%A Aij-Li Kwan
%J BMC Neurology
%D 2011
%I BioMed Central
%R 10.1186/1471-2377-11-71
%X Sixty six adult male Sprague-Dawley rats were divided into three treatment groups: (1) sham (Group S), which underwent removal of the L6 transverse process; (2) ligated (Group L), which underwent left L5 spinal nerve ligation (SNL); and (3) pretreated (Group P), which underwent L5 SNL and was pretreated with intrathecal 2% lidocaine (50 ¦Ěl). Neuropathic pain was assessed based on behavioral responses to thermal and mechanical stimuli. Expression of sodium channels (Nav1.3 and Nav1.8) in injured dorsal root ganglia and microglial proliferation/activation in the spinal cord were measured on post-operative days 3 (POD3) and 7 (POD7).Group L presented abnormal behavioral responses indicative of mechanical allodynia and thermal hyperalgesia, exhibited up-regulation of Nav1.3 and down-regulation of Nav1.8, and showed increased microglial activation. Compared with ligation only, pretreatment with intrathecal lidocaine before nerve injury (Group P), as measured on POD3, palliated both mechanical allodynia (p < 0.01) and thermal hyperalgesia (p < 0.001), attenuated Nav1.3 up-regulation (p = 0.003), and mitigated spinal microglial activation (p = 0.026) by inhibiting phosphorylation (activation) of p38 MAP kinase (p = 0.034). p38 activation was also suppressed on POD7 (p = 0.002).Intrathecal lidocaine prior to SNL blunts the response to noxious stimuli by attenuating Nav1.3 up-regulation and suppressing activation of spinal microglia. Although its effects are limited to 3 days, intrathecal lidocaine pretreatment can alleviate acute SNL-induced neuropathic pain.Peripheral nerve injury caused by disease or surgery, such as limb and colon amputation, nerve dissection, mastectomy, and thoracotomy, often results in neuropathic pain [1]. It is a neglected problem for which very few patients are referred for surgical management [2]. Patients who develop postsurgical chronic neuropathic pain suffer from acute postoperative pain and have intraoperative nerve damage [3]. Nearly 50% of
%U http://www.biomedcentral.com/1471-2377/11/71