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GABAergic Inhibition of Spinal Cord Dorsal Horns Contributes to Analgesic Effect of Electroacupuncture in Incisional Neck Pain Rats

Authors Wang J, Bai W, Gao Y, Zhang J, Duanmu C, Liu J

Received 13 December 2019

Accepted for publication 23 May 2020

Published 3 July 2020 Volume 2020:13 Pages 1629—1645

DOI https://doi.org/10.2147/JPR.S242330

Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 4

Editor who approved publication: Dr Michael A Überall


Jun-ying Wang,1 Wan-zhu Bai,2 Yong-hui Gao,1 Jian-liang Zhang,1 Cheng-lin Duanmu,1 Jun-ling Liu1

1Department of Physiology, Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, People’s Republic of China; 2Laboratory for Architecture of Acupoints, Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, People’s Republic of China

Correspondence: Jun-ling Liu; Jun-ying Wang Tel +86-10-64089409
; +86-10-64089419
Email 13521898023@163.com; wjyanguning@aliyun.com

Background: Acupuncture has shown to be effective in relieving post-surgical pain. Nonetheless, its underlying mechanisms remain largely unknown. In the present study, we investigated the effect of electroacupuncture (EA) on the expression of GABA, GABA-A receptor (R) and GABA-BR in the spinal cord dorsal horns (DHs), and the involved neural cells in rats with incisional neck pain.
Materials and Methods: Male SD rats were randomly divided into control, model, Futu (LI18), Hegu-Neiguan (LI4-PC6), and Zusanli-Yanglingquan (ST36-GB34) groups. The incisional neck pain model was established by making a longitudinal incision and repeated mechanical separation along the thyroid gland region. EA (2Hz/100Hz, 1mA) was applied to LI18, LI4-PC6, ST36-GB34 separately for 30min, once at 4, 24 and 48h after incision. The local thermal pain threshold (TPT) of the focus was measured and the expression of GABA, and GABAR proteins and mRNAs detected by immunofluorescence stain and quantitative RT-PCR, respectively.
Results: The analgesic effect of LI18 and LI4-PC6 was superior to that of ST36-GB34 in incisional neck pain rats. Moreover, the EA stimulation of LI18 or LI4-PC6 increased the expression of GABA and GABA-Aα 2 and GABA-Aβ 3, GABA-B1, and GABA-B2 mRNAs in spinal DHs 4h after surgery, while GABA-A and GABA-B antagonists inhibited the analgesic effect of LI18. Immunofluorescence double staining showed that GABA was expressed on astrocytes and neurons, and GABA-B expressed only on neurons.
Conclusion: EA of both LI18 and LI4-PC6 has a good analgesic effect in incisional neck pain rats, which is closely related to their effects in upregulating the expression of GABA and its receptors in spinal DHs. The effects of LI18 and LI4-PC6 EA are obviously better that those of ST36-GB34 EA, and GABA is expressed on neurons and astrocytes.

Keywords: electroacupuncture analgesia, incisional neck pain, dorsal horn of spinal cord, GABA, gliacytes

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