Astrocyte activation in hindlimb somatosensory cortex contributes to electroacupuncture analgesia in acid-induced pain

Qing Ye; Jie Li; Wen-Jing Ren; Ying Zhang; Tao Wang; Patrizia Rubini; Hai-Yan Yin; Peter Illes; Yong Tang

doi:10.3389/fneur.2024.1348038

Astrocyte activation in hindlimb somatosensory cortex contributes to electroacupuncture analgesia in acid-induced pain

Front Neurol. 2024 Apr 3:15:1348038. doi: 10.3389/fneur.2024.1348038. eCollection 2024.

Authors

Qing Ye^#¹, Jie Li^#², Wen-Jing Ren¹, Ying Zhang¹, Tao Wang³, Patrizia Rubini¹, Hai-Yan Yin¹, Peter Illes^{1

4}, Yong Tang^{1

5}

Affiliations

¹ International Joint Research Centre on Purinergic Signalling, School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
² Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, China.
³ Chongqing Traditional Chinese Medicine Hospital, Chongqing, China.
⁴ Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany.
⁵ Acupuncture and Chronobiology Key Laboratory of Sichuan Province, School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China.

^# Contributed equally.

Abstract

Background: Several studies have confirmed the direct relationship between extracellular acidification and the occurrence of pain. As an effective pain management approach, the mechanism of electroacupuncture (EA) treatment of acidification-induced pain is not fully understood. The purpose of this study was to assess the analgesic effect of EA in this type of pain and to explore the underlying mechanism(s).

Methods: We used plantar injection of the acidified phosphate-buffered saline (PBS; pH 6.0) to trigger thermal hyperalgesia in male Sprague-Dawley (SD) rats aged 6-8 weeks. The value of thermal withdrawal latency (TWL) was quantified after applying EA stimulation to the ST36 acupoint and/or chemogenetic control of astrocytes in the hindlimb somatosensory cortex.

Results: Both EA and chemogenetic astrocyte activation suppressed the acid-induced thermal hyperalgesia in the rat paw, whereas inhibition of astrocyte activation did not influence the hyperalgesia. At the same time, EA-induced analgesia was blocked by chemogenetic inhibition of astrocytes.

Conclusion: The present results suggest that EA-activated astrocytes in the hindlimb somatosensory cortex exert an analgesic effect on acid-induced pain, although these astrocytes might only moderately regulate acid-induced pain in the absence of EA. Our results imply a novel mode of action of astrocytes involved in EA analgesia.

Keywords: acid-induced pain; astrocytes; electroacupuncture analgesia; extracellular acidification; hindlimb somatosensory cortex.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by grants from NSFC (82274668 and 82230127), the China Postdoctoral Science Foundation (2023M740384 and GZC20230337), the Innovation Team and Talents Cultivation Program of the National Administration of Traditional Chinese Medicine (ZYYCXTD-D-202003), and the Sichuan Science and Technology Program (2022YFH0006 and 2021YFH0096).