Department of Medical Science and Technology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan.
Brain Res. 2010 Jan 8;1306:62-8. doi: 10.1016/j.brainres.2009.09.117. Epub 2009 Oct 9.
Acupuncture and electroacupuncture are used in pain relief; however, the mechanism underlying the analgesic effect of acupuncture is unclear. Several lines of evidence propose that the periaqueductal gray (PAG), which is one of the regions that contributes to the endogenous pain inhibitory system, is involved in the analgesic effect of acupuncture, and the region receives several neural projections such as histamine and noradrenalin and contains the dopamine cell bodies. The current study examined the effects of electroacupuncture at Zusanli (ST36) and Shangjuxu (ST37) acupoints, which are used for clinical pain control, on the release of neurotransmitters in the PAG in rats. Histamine and dopamine release was increased after pain stimulus, while the changes were completely abolished by electroacupuncture. Pain stimulus had no effect on noradrenalin release, but electroacupuncture increased its release. These findings indicate that acupuncture at Zusanli and Shangjuxu exerts an antinociceptive effect via the activation of neurons in the PAG and that the histaminergic, dopaminergic, and noradrenalinergic systems in the PAG are related to electroacupuncture-induced pain relief.
针刺和电针对缓解疼痛有效；然而，针刺镇痛的机制尚不清楚。有几条证据表明，参与内源性疼痛抑制系统的脑桥导水管周围灰质（periaqueductal gray，PAG）与针刺的镇痛作用有关，该区域接收几种神经投射，如组胺和去甲肾上腺素，并包含多巴胺细胞体。本研究检测了用于临床疼痛控制的足三里（ST36）和上巨虚（ST37）穴位电针对大鼠 PAG 中神经递质释放的影响。疼痛刺激后组胺和多巴胺的释放增加，而电针完全消除了这种变化。疼痛刺激对去甲肾上腺素的释放没有影响，但电针增加了其释放。这些发现表明，针刺足三里和上巨虚通过激活 PAG 中的神经元发挥镇痛作用，而 PAG 中的组胺能、多巴胺能和去甲肾上腺素能系统与电针引起的疼痛缓解有关。
