Li Hong-Ping, Wang Xiao-Yu, Chen Chao, Li Jing-Jing, Yu Chi, Lin Li-Xue, Yu Zi-E, Jin Zhi-Yuan, Zhu He, Xiang Hong-Chun, Hu Xue-Fei, Cao Jie, Jing Xiang-Hong, Li Man
Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China.
Front Neurosci. 2021 Feb 16;15:625471. doi: 10.3389/fnins.2021.625471. eCollection 2021.
Clinical studies have shown that electroacupuncture (EA) alleviates chronic itch. Gastrin-releasing peptide receptor (GRPR) and dynorphin (DYN) in the spinal dorsal horn positively or negatively regulate itch, respectively. However, which frequency of EA is effective on relieving chronic itch and reducing the expression of GRPR, whether DYN-A in the spinal cord is involved in the underlying mechanism of the antipruritus effect of EA remains unknown.
The mixture of acetone and diethyl ether (1:1) [designated as AEW (acetone/diethyl ether and water) treatment] was used to induce the dry skin model of chronic itch. EA was applied to Quchi (LI11) and Hegu (LI4). Western blot was used to detect the expression of GRPR and DYN-A. Immunofluorescence was used to detect the expression of DYN-A.
The AEW administration induced remarkable spontaneous scratching, enhanced the expression of GRPR, and reduced the expression of DYN-A. Compared with the sham EA, 2 Hz EA, or 15 Hz EA group, 100 Hz EA was the most effective frequency for relieving chronic itch, reducing the expression of GRPR, and increasing the expression of DYN-A in the cervical dorsal horn. Furthermore, intraperitoneal injection of kappa opioid receptors (KORs) antagonist nor-Binaltorphimine dihydrochloride (nor-BNI) significantly reversed the effect of 100 Hz EA on the inhibition of both itching behavior and GRPR expression.
EA at 100 Hz is the most effective frequency that inhibits chronic itch and GRPR expression through activation of KORs in the spinal dorsal horn, which can effectively guide the clinical treatment and improve the antipruritic effect of acupuncture.
临床研究表明，电针（EA）可缓解慢性瘙痒。脊髓背角中的胃泌素释放肽受体（GRPR）和强啡肽（DYN）分别对瘙痒起正向或负向调节作用。然而，何种频率的电针对缓解慢性瘙痒及降低GRPR表达有效，脊髓中的强啡肽A（DYN-A）是否参与电针止痒作用的潜在机制尚不清楚。
使用丙酮和乙醚的混合物（1:1）[称为AEW（丙酮/乙醚和水）处理]诱导慢性瘙痒的干性皮肤模型。电针刺激曲池（LI11）和合谷（LI4）。采用蛋白质免疫印迹法检测GRPR和DYN-A的表达。采用免疫荧光法检测DYN-A的表达。
给予AEW可引起明显的自发性搔抓，增强GRPR的表达，并降低DYN-A的表达。与假电针组、2Hz电针组或15Hz电针组相比，100Hz电针是缓解慢性瘙痒、降低GRPR表达及增加颈背角DYN-A表达最有效的频率。此外，腹腔注射κ阿片受体（KORs）拮抗剂盐酸去甲二氢吗啡酮（nor-BNI）可显著逆转100Hz电针对瘙痒行为和GRPR表达抑制的作用。
100Hz电针是通过激活脊髓背角中的KORs来抑制慢性瘙痒和GRPR表达的最有效频率，可有效指导临床治疗并提高针刺的止痒效果。
