Low-Frequency Electroacupuncture Alleviates Chronic Constrictive Injury-Induced Mechanical Allodynia by Inhibiting NR2B Upregulation in Ipsilateral Spinal Dorsal Horn in Rats

Wen-Sheng Zhao; Zhen-Ni Jiang; Hui Shi; Lu-Lu Xu; Yue Yang; Ying-Chao Wang

doi:10.1007/s11655-018-3057-4

Low-Frequency Electroacupuncture Alleviates Chronic Constrictive Injury-Induced Mechanical Allodynia by Inhibiting NR2B Upregulation in Ipsilateral Spinal Dorsal Horn in Rats

Chin J Integr Med. 2019 Jun;25(6):462-467. doi: 10.1007/s11655-018-3057-4. Epub 2018 Nov 22.

Authors

Wen-Sheng Zhao¹, Zhen-Ni Jiang², Hui Shi³, Lu-Lu Xu⁴, Yue Yang⁴, Ying-Chao Wang⁵

Affiliations

¹ Department of Pain Medicine, Hangzhou Red Cross Hospital, Hangzhou, 310003, China.
² Department of Cardiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, 310009, China. ze_jzn@zju.edu.cn.
³ Department of Acupuncture, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, 310009, China.
⁴ The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
⁵ Department of Clinical Research Center, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, 310009, China.

PMID: 30467696
DOI: 10.1007/s11655-018-3057-4

Abstract

Objective: To study the effects of electroacupuncture (EA) in chronic constrictive injury (CCI) rat model and the expression of N-methyl-D-aspartate receptor type 2B (NR2B) in ipsilateral spinal dorsal horn in rats to explore the analgesic mechanisms of EA.

Methods: According to the random number table, totally 180 rats were evenly divided into a sham group, a CCI group, and an EA group. CCI model was conducted with four 4-0 chromic gut ligatures loosely ligated around the left sciatic nerve 1 cm above the trifurcation. Rats in the EA group received 2 Hz EA therapy bilaterally at acupoints of Zusanli (ST 36) and Sanyinjiao (SP 6) once daily (30 min/d) for 30 days after surgery. Paw withdrawal thresholds (PWTs) were measured on 0 (baseline), 1, 3, 7, 15, 30 days after surgery. Rats were sacrificed on 0, 1, 3, 7, 15 and 30 days after surgery, and the L4-5 segments of spinal cord were removed to detect the expression of NR2B by immunohistochemistry and quantitative polymerase chain reaction.

Results: PWTs in the CCI group were significantly lower than the sham group at Day 1-30 after surgery, and reached its lowest at Day 1 (P<0.01). After EA treatment, the PWTs recovered rapidly and were significantly higher than those in the CCI group on 3, 7, 15 and 30 days after surgery (P<0.01). The numbers of NR2B-immunoreactive cells of the CCI group significantly increased after CCI surgery compared with the sham group (P<0.01). Compared with the CCI group, stimulation of EA markedly decreased the numbers of NR2B-immunoreactive cells at Day 3, 7, 15 and 30 (P<0.05). In the sham group, NR2B mRNA was expressed at a low level. It increased after CCI surgery, which increased rapidly at Day 7 (P<0.01) and reached its peak value at Day 15 (P<0.01). After EA stimulation, relative quantity of NR2B mRNA expression was less than that in the CCI group at Day 15 and 30 (P<0.05).

Conclusions: Low frequency of EA had antinociceptive effect in CCI rat model. The analgesic effects of EA might be through the inhibition of NR2B.

Keywords: Chinese medicine; N-methyl-D-aspartate receptor type 2B; chronic constrictive injury; electroacupuncture; sciatica; spinal dorsal horn.

MeSH terms

Animals
Behavior, Animal
Chronic Disease
Constriction, Pathologic
Electroacupuncture*
Hyperalgesia / etiology*
Hyperalgesia / therapy*
Ligation
Male
RNA, Messenger / genetics
RNA, Messenger / metabolism
Rats, Sprague-Dawley
Receptors, N-Methyl-D-Aspartate / genetics*
Receptors, N-Methyl-D-Aspartate / metabolism
Sciatic Nerve / injuries
Spinal Cord Dorsal Horn / pathology*
Time Factors
Up-Regulation / genetics*

Substances

NR2B NMDA receptor
RNA, Messenger
Receptors, N-Methyl-D-Aspartate