Wu Zong-Lin, Xu Yun-Yun, Chen Yue-Rong, Liu Zhe, Tong Si-Yuan, Wang Lin-Bao, Chen Liang, Wang Zhan-Peng, Fang Jian-Qiao, Wu Yuan-Yuan
The Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310005, China.
Hangzhou Red Cross Hospital, Hangzhou 310003.
Zhen Ci Yan Jiu. 2025 Aug 25;50(8):851-861. doi: 10.13702/j.1000-0607.20250181.
OBJECTIVES: This study aims to investigate the intervention effects of electroacupuncture on neuropathic pain and anxiety-like behavior, and to explore the underlying mechanisms of the DRN-BLA (dorsal raphe nucleus serotoninergic - basolateral amygdala) neural circuit. METHODS: Male C57BL/6J mice were selected, and a neuropathic pain model was established through spared nerve injury (SNI) surgery. Electroacupuncture (100 Hz, 0.3 mA, 30 min) was applied to bilateral "Zusanli" (ST36) and "Sanyinjiao"(SP6). Anxiety-like behavior was assessed using the elevated plus maze (EPM) and open field (OF) tests, while mechanical allodynia was evaluated using the Von-Frey test. Viral tracing was used to confirm the anatomical connection between DRN and BLA. Immunofluorescence was used to assess the activity of 5-HT neurons in the DRN. Chemogenetic and calcium imaging techniques were employed to observe changes in the activity of 5-HT neurons in the DRN of DRN-BLA. Chemogenetics were used to observe the effect of inhibiting DRN-BLA on electroacupuncture. RESULTS: SNI model mice showed a significant decrease in mechanical pain threshold (<0.000 1) and exhibited marked anxiety-like behavior in both the EPM and OF tests (<0.01, <0.05). Compared to the model group, electroacupuncture significantly increased the mechanical pain threshold in the electroacupuncture group (<0.000 1). The EPM and OF results indicated that electroacupuncture significantly reduced anxiety-like behavior (<0.05, <0.001) without affecting spontaneous activity. Virus tracing results confirmed the anatomical connection between 5-HT neurons in the DRN and the BLA. Immunofluorescence results showed that the activity of 5-HT neurons in the DRN was significantly reduced (<0.000 1) in SNI model mice, which was significantly reversed by electroacupuncture (<0.01). Calcium imaging revealed that in SNI model mice, the excitability of 5-HT neurons in the DRN-BLA circuit was decreased, and electroacupuncture treatment restored their excitability. After chemogenetic inhibition of the DRN-BLA circuit, electroacupuncture failed to improve mechanical allodynia and anxiety-like behavior in the SNI model mice (<0.05, <0.001, <0.01). CONCLUSIONS: 5-HT neurons in the DRN-BLA circuit play a crucial role in the mechanical allodynia and associated anxiety-like behavior in neuropathic pain. Electroacupuncture activates this circuit, enhancing the activity of 5-HT neurons in the DRN, thereby alleviating mechanical allodynia and anxiety-like behavior in SNI model mice.