Chronic pain is a major health problem, which can impair quality of life and reduce productivity. Electroacupuncture (EA), a modality of medicine based on the theories of Traditional Chinese Medicine (TCM), presents great therapeutic effects on chronic pain. Its clinical application has gained increasing popularity, and in parallel, more research has been performed on the mechanisms of EA-induced analgesia. The past decades have seen enormous advances both in neuronal circuitry of needle-insertion and in its molecular mechanism. EA may block pain by activating the descending pain inhibitory system, which originates in the brainstem and terminates at the spinal cord. This review article synthesizes corresponding studies to elucidate how EA alleviate pain via the mediation of this descending system. Much emphasis has been put on the implication of descending serotonergic and noradrenergic pathways in the process of pain modulation. Also, other important transmitters and supraspinal regions related to analgesic effects of EA have been demonstrated. Finally, it should be noticed that there exist some shortcomings involved in the animal experimental designed for EA, which account for conflicting results obtained by different studies.

中文翻译：

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下行疼痛抑制系统在电针镇痛中的作用。

慢性疼痛是一个主要的健康问题，会损害生活质量并降低生产力。电针（EA）是一种以中医理论为基础的医学治疗方法，对慢性疼痛具有良好的治疗效果。其临床应用日益普及，同时，针对电针镇痛机制的研究也越来越多。在过去的几十年里，针插入的神经元回路及其分子机制都取得了巨大的进步。电针可以通过激活下行疼痛抑制系统来阻止疼痛，该系统起源于脑干并终止于脊髓。这篇综述文章综合了相应的研究，以阐明电针如何通过这一下行系统的调节来减轻疼痛。人们非常重视血清素能和去甲肾上腺素能下行通路在疼痛调节过程中的影响。此外，与 EA 镇痛作用相关的其他重要递质和脊髓上区域也已得到证实。最后，应该指出的是，针对 EA 设计的动物实验存在一些缺陷，这导致了不同研究获得的结果相互矛盾。