RESEARCH ARTICLE
Electroacupuncture Inhibits Spinal Interleukin-17A to Alleviate Inflammatory Pain in a Rat Model
Xianze Meng1, 2, Lixing Lao1, Xue-Yong Shen3, Brian M. Berman1, Ke Ren4, Pin-Kang Wei2, Rui-Xin Zhang1, *
Article Information
Identifiers and Pagination:
Year: 2013Volume: 6
First Page: 183
Last Page: 189
Publisher ID: TOPAINJ-6-183
DOI: 10.2174/1876386320130624001
Article History:
Received Date: 07/05/2013Revision Received Date: 07/06/2013
Acceptance Date: 20/06/2013
Electronic publication date: 26/7/2013
Collection year: 2013
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Although acupuncture analgesia has been reported in clinical trials, its mechanisms have been unclear. It was recently reported that spinal astrocytes-produced interleukin-17A (IL-17A) facilitates inflammatory pain. Hypothesizing that electroacupuncture (EA) would suppress inflammation-enhanced IL-17A synthesis to inhibit pain, we induced hyperalgesia, as measured by decreased paw withdrawal latency (PWL) to a noxious thermal stimulus, by subcutaneously injecting complete Freund's adjuvant (CFA, 0.08 ml, 40 μg Mycobacterium tuberculosis) into the hind paws of rats, or intrathecal (i.t.) IL-17A (400 ng in 10 μl) into the lumbar spinal cord. We then gave EA at acupoint GB30 for two 20-min periods, once immediately after CFA or IL-17A administration and again 2 h post-injection. For sham control, EA needles were inserted into GB30 without stimulation. PWL was measured before and 2.5 and 24 h after injection. Spinal IL-17A, IL-17 receptor A (IL-17RA), and phosphorylated NR1, an essential subunit of the N-methyl D-aspartate receptor (NMDAR), were determined 24 h post-CFA or –IL-17A using immunohistochemistry and western blot. Compared to sham control, EA inhibited CFA-caused thermal hyperalgesia 2.5 and 24 h post-CFA and concurrently suppressed inflammation-enhanced IL-17A and IL-17RA synthesis and NR1 phosphorylation in the ipsilateral spinal cord. EA inhibited IL-17A-produced thermal hyperalgesia, IL-17RA synthesis and NR1 phosphorylation. Our data suggest that EA inhibits inflammatory pain by blocking spinal IL-17A synthesis. Since previous study shows that IL-17A is located in astrocytes and IL-17RA and NR1 are in neurons, the data suggest that EA alleviates pain by modulating glia-neuronal interactions that involve IL-17A, IL-17RA, and NR1 phosphorylation.
