Sympathetic-Sensory Coupling as a Potential Mechanism for Acupoints Sensitization

Xiang Cui,1 Ziyi Zhang,1,2 Hanqing Xi,1 Kun Liu,1 Bing Zhu,1 Xinyan Gao1 1Department of Physiology, Institute of Acupuncture and Moxibustion, Academy of Chinese Medical Sciences, Beijing, 100700, People’s Republic of China; 2College of Acupuncture and Tuina, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi Province, 712046, People’s Republic of ChinaCorrespondence: Xiang Cui; Xinyan Gao, Department of Physiology, Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, 100700, People’s Republic of China, Tel +86-10-64089422 ; +86-10-64089420, Email drcuixiang@163.com; xinyangao2001@msn.comAbstract: A series of studies have demonstrated acupoint sensitization, in which acupoints can be activated in combination with sensory hypersensitivity and functional plasticity during visceral disorders. However, the mechanisms of acupoint sensitization remain unclear. Neuroanatomy evidence showed nociceptors innervated in acupoints contribute to the mechanism of acupoint sensitization. Increasing studies suggested sympathetic nerve plays a key role in modulating sensory transmission by sprouting or coupling with sensory neuron/nociceptor in the peripheral, forming the functional structure of the sympathetic-sensory coupling. Notably, the sensory inputs of the disease-induced sensitized acupoint contribute to the homeostatic regulation and also involve in delivering therapeutic information under acupuncture, hence, the role of sprouted sympathetic in acupoint function should be given attention. We herein reviewed the current knowledge of sympathetic and its sprouting in pain modulation, then discussed and highlighted the potential value of sympathetic-sensory coupling in acupoint functional plasticity.Keywords: referred pain, hyperalgesia, acupuncture, nociceptor, Somato-sympathetic-viscera reflex