Article

Molecular mechanisms of the analgesic action of Wu-tou Decoction on neuropathic pain in mice revealed using microarray and network analysis

Authors: Yan-qiong ZHANG1, Chao WANG1, Qiu-yan GUO1, Chun-yan ZHU1, Chen YAN1, Dan-ni SUN1, Qiong-hong XU1, Na LIN1
1 Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China
Corresponding to: Yan-qiong ZHANG: yqzhang@icmm.ac.cn, Na LIN: nlin@icmm.ac.cn,
DOI: 10.1038/aps.2017.110
Received: 3 April 2017
Accepted: 19 May 2017
Advance online: 17 August 2017

Abstract

Abstract
Wu-tou Decoction (WTD) is a classic herbal formula in traditional Chinese medicine for the treatment of joint diseases, neuropathic pain (NP) and inflammatory pain. In this study we investigated whether WTD produced analgesic action in a mouse spinal nerve ligation (SNL) model and elucidated the underlying molecular mechanisms. Mice were subjected to SNL and orally treated with WTD (3.15, 6.30 or 12.60 g·kg-1·d-1) for 21 d. SNL induced mechanical hyperalgesia and heat hyperalgesia characterized by rapid and persistent pain hypersensitivity. In addition, the expression levels of IL-1β, TNF-α, CCL2 and CXCL1 in the spinal cord dorsal horn were dramatically increased on the 10th d post-surgery. Oral administration of WTD dose-dependently suppressed both mechanical and heat hyperalgesia as well as the expression levels of inflammatory cytokines in the spinal cord dorsal horn on the 21st d post-surgery. Then whole-genome microarray analyses were conducted to detect the gene expression profiles of spinal cord dorsal horn in SNL mice with or without WTD treatment. After construction of the WTD-SNL-network and topological analysis, a list of candidate target genes of WTD acting on SNL-induced NP was identified and found to be functionally enriched in several glial cell activation-related pathways and neuroinflammatory pathways. Our data have clarified the gene expression patterns in the mouse spinal cord under the NP condition. We also demonstrate the analgesic action of WTD through suppression of glial cell activation and neuroinflammation, which suggest the potential of WTD as a promising candidate for the treatment of NP.
Keywords: Wu-tou Decoction; herbal formula; neuropathic pain; spinal nerve ligation; hyperalgesia; inflammatory cytokines; microarray analysis; network pharmacology; glial cell activation; neuroinflammation