Electroacupuncture (EA) treatment has proved to significantly decrease nociception in inflammatory nociception model by suppressing the phosphorylation of p38 mitogen-activated protein kinase (p38MAPK). However, repeated EA treatment results in gradual attenuation of its analgesic effects, which was defined as “EA tolerance.” Recent studies have shown that let-7b-5p microRNA (miRNA) contributes to the EA tolerance. The present study aimed to explore the function of let-7b-5p in p38MAPK pathway and the development of EA tolerance in the inflammatory nociception. Dual luciferase reporter gene experiments were used in cortical neurons to determine the target gene locus of let-7b-5p. The threshold of nociception was assessed by tail flick latency (TFL) and paw withdrawal threshold (PWT). Western blots were used to measure the expression of mitogen-activated protein kinase phosphatase 1 (MKP-1) and phosphorylation level of p38MAPK after intracerebroventricular (ICV) injections of let-7b-5p agomir, antagomir, and controls. In vitro dual luciferase experiments demonstrated that the MKP-1-3′ untranslated region (UTR) is a target of let-7b-5p. In vivo experiment, rat with repeated EA treatment exhibits gradual decrease in TFL and PWT, which showed formation of EA tolerance. This trend was delayed after IVC injection of let-7b-5p antagomir and facilitated after IVC injection of let-7b-5p agomir. The protein levels of MKP-1 in the EA+let-7b-5p antagomir group were significantly higher than in the EA + let-7b-5p agomir group. However, P-p38MAPK in the EA+let-7b-5p antagomir group was significantly lower than in the EA+let-7b-5p agomir group. By upregulating the p38MAPK pathway through the inactivation of the MKP-1 gene, let-7b-5p contributes to EA tolerance in complete Freund’s adjuvant (CFA)-induced inflammatory nociception rats. Our work revealed the mechanism of EA tolerance and indicated that let-7b-5p could be targeted to improve the long-term effects of EA.

中文翻译：

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MicroRNA Let-7b-5p通过下调CFA诱导的炎性痛觉大鼠的MKP-1基因来诱导电针耐受。

事实证明，电针（EA）治疗可通过抑制p38丝裂原活化蛋白激酶（p38MAPK）的磷酸化来显着降低炎症性伤害感受模型的伤害感受。但是，反复进行EA治疗会导致其镇痛作用逐渐减弱，这被定义为“ EA耐受性”。最近的研究表明，let-7b-5p microRNA（miRNA）有助于EA耐受。本研究旨在探讨let-7b-5p在p38MAPK途径中的功能以及炎性伤害感受中EA耐受性的发展。在皮质神经元中使用双重荧光素酶报告基因实验确定let-7b-5p的靶基因基因座。通过甩尾潜伏期（TFL）和缩脚阈值（PWT）评估伤害感受阈值。Western印迹用于测量脑室内（ICV）注射let-7b-5pagomir，antagomir和对照后丝裂原激活的蛋白激酶磷酸酶1（MKP-1）的表达和p38MAPK的磷酸化水平。体外双重荧光素酶实验证明，MKP-1-3'非翻译区（UTR）是let-7b-5p的靶标。在体内实验中，反复进行EA处理的大鼠的TFL和PWT逐渐降低，这表明形成了EA耐受性。IVC注射let-7b-5p antagomir后，这一趋势被延迟，而IVC注射let-7b-5pagomir后，这种趋势得到了促进。EA + let-7b-5p antagomir组的MKP-1蛋白水平显着高于EA + let-7b-5p agomir组的蛋白水平。然而，EA + let-7b-5p antagomir组的P-p38MAPK显着低于EA + let-7b-5pagomir组。通过失活MKP-1基因上调p38MAPK途径，let-7b-5p有助于完全弗氏佐剂（CFA）诱导的炎症痛觉大鼠的EA耐受性。我们的工作揭示了EA耐受的机制，并指出let-7b-5p可以提高EA的长期疗效。