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Open Access Research article

Intrathecal lidocaine pretreatment attenuates immediate neuropathic pain by modulating Nav1.3 expression and decreasing spinal microglial activation

Kuang-I Cheng123, Chung-Sheng Lai45, Fu-Yuan Wang2, Hung-Chen Wang16, Lin-Li Chang7*, Shung-Tai Ho8, Hung-Pei Tsai1 and Aij-Li Kwan59*

Author Affiliations

1 Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

2 Department of Anesthesiology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

3 Department of Anesthesiology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

4 Department of Surgery, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

5 Division of Plastic and Reconstructive Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

6 Department of Neurosurgery, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan

7 Department of Microbiology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

8 Department of Anesthesiology, Tri-Service General Hospital National Defense Medical Center, Taipei, Taiwan

9 Department of Neurosurgery, Kaohsiung Medical University, Kaohsiung, Taiwan

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BMC Neurology 2011, 11:71  doi:10.1186/1471-2377-11-71

Published: 16 June 2011

Abstract

Background

Intrathecal lidocaine reverses tactile allodynia after nerve injury, but whether neuropathic pain is attenuated by intrathecal lidocaine pretreatment is uncertain.

Methods

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 μl). 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).

Results

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).

Conclusions

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.