Irritable bowel syndrome patients frequently complain of pain in body regions somatotopically distinct from the gut, suggesting the involvement of an exaggerated signaling process in both visceral and somatic sensory pathways. Increasing evidence has shown that sprouting of tyrosine hydroxylase immunoreactive (TH-IR) fibers toward sensory neurons in dorsal root ganglia maintains and exacerbates the neuropathic and inflammatory pain, as well as colonic inflammation. The aim of the present study was to determine whether electroacupuncture could alleviate the visceral and secondary somatic hyperalgesia in colitis rats by suppressing the TH-IR expression in related dorsal root ganglia. After trinitrobenzene sulfonic acid irritation, rats developed inflammatory tissue damage in the distal colon, which was accompanied by visceral hypersensitivity and secondary hind paw hyperalgesia, as indicated by enhanced visceromotor response to colorectal distension and decreased mechanical and thermal withdrawal latency of the hind paw. Additionally, excessive TH-IR fibers sprouted toward calcitonin gene-related peptide immunoreactive sensory neurons, and TH-IR neurons also increased in the sixth lumbar dorsal root ganglia of colitis rats. Both electroacupuncture and guanethidine attenuated visceral and referred hind paw hyperalgesia by inhibiting the over-expression of TH-IR neurons and fibers in the sixth lumbar dorsal root ganglia. Moreover local inflammatory damage in the distal colon was restored after 7 days of electroacupuncture intervention. These results suggest that electroacupuncture relieved visceral and referred hind paw hypersensitivity in colitis rats by inhibiting TH expression in the sixth lumbar dorsal root ganglia.

中文翻译：

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电针抑制第六腰背根神经节酪氨酸羟化酶表达减轻结肠炎大鼠内脏及牵涉后足超敏反应

肠易激综合征患者经常抱怨身体部位与肠道不同的疼痛，这表明在内脏和躯体感觉通路中都涉及夸大的信号传导过程。越来越多的证据表明，酪氨酸羟化酶免疫反应 (TH-IR) 纤维向背根神经节中的感觉神经元发芽可维持和加剧神经性和炎症性疼痛，以及结肠炎症。本研究的目的是确定电针是否可以通过抑制相关背根神经节中 TH-IR 的表达来减轻结肠炎大鼠的内脏和继发性躯体痛觉过敏。三硝基苯磺酸刺激后，大鼠远端结肠出现炎性组织损伤，伴随着内脏超敏反应和继发性后爪痛觉过敏，表现为对结直肠扩张的内脏运动反应增强，后爪的机械和热缩回潜伏期减少。此外，过量的TH-IR纤维向降钙素基因相关肽免疫反应性感觉神经元发芽，结肠炎大鼠第6腰背根神经节的TH-IR神经元也增多。电针和胍乙啶均通过抑制第六腰背根神经节中 TH-IR 神经元和纤维的过度表达来减轻内脏和后爪痛觉过敏。此外，在电针干预 7 天后，远端结肠的局部炎症损伤得到恢复。