Wang Shusheng, Zhu Hong-Yan, Jin Yi, Zhou Youlang, Hu Shufen, Liu Tong, Jiang Xinghong, Xu Guang-Yin
The Affiliated Zhangjiagang Hospital of Soochow University, Suzhou, China;
The Affiliated Zhangjiagang Hospital of Soochow University, Suzhou, China; Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, China;
Am J Physiol Gastrointest Liver Physiol. 2015 Apr 15;308(8):G710-9. doi: 10.1152/ajpgi.00395.2014. Epub 2015 Jan 29.
The mechanism of pain in chronic pancreatitis (CP) is poorly understood. The aim of this study was designed to investigate roles of norepinephrine (NE) and P2X receptor (P2XR) signaling pathway in the pathogenesis of hyperalgesia in a rat model of CP. CP was induced in male adult rats by intraductal injection of trinitrobenzene sulfonic acid (TNBS). Mechanical hyperalgesia was assessed by referred somatic behaviors to mechanical stimulation of rat abdomen. P2XR-mediated responses of pancreatic dorsal root ganglion (DRG) neurons were measured utilizing calcium imaging and whole cell patch-clamp-recording techniques. Western blot analysis and immunofluorescence were performed to examine protein expression. TNBS injection produced a significant upregulation of P2X3R expression and an increase in ATP-evoked responses of pancreatic DRG neurons. The sensitization of P2X3Rs was reversed by administration of β-adrenergic receptor antagonist propranolol. Incubation of DRG neurons with NE significantly enhanced ATP-induced intracellular calcium signals, which were abolished by propranolol, and partially blocked by protein kinase A inhibitor H-89. Interestingly, TNBS injection led to a significant elevation of NE concentration in DRGs and the pancreas, an upregulation of β2-adrenergic receptor expression in DRGs, and amplification of the NE-induced potentiation of ATP responses. Importantly, pancreatic hyperalgesia was markedly attenuated by administration of purinergic receptor antagonist suramin or A317491 or β2-adrenergic receptor antagonist butoxamine. Sensitization of P2X3Rs, which was likely mediated by adrenergic signaling in primary sensory neurons, contributes to pancreatic pain, thus identifying a potential target for treating pancreatic pain caused by inflammation.
慢性胰腺炎（CP）的疼痛机制尚不清楚。本研究旨在探讨去甲肾上腺素（NE）和P2X受体（P2XR）信号通路在CP大鼠模型痛觉过敏发病机制中的作用。通过向成年雄性大鼠胰管内注射三硝基苯磺酸（TNBS）诱导CP。通过大鼠腹部机械刺激引发的躯体行为评估机械性痛觉过敏。利用钙成像和全细胞膜片钳记录技术测量胰腺背根神经节（DRG）神经元的P2XR介导反应。进行蛋白质印迹分析和免疫荧光检测蛋白表达。TNBS注射导致P2X3R表达显著上调，胰腺DRG神经元的ATP诱发反应增加。β-肾上腺素能受体拮抗剂普萘洛尔可逆转P2X3R的敏化作用。用NE孵育DRG神经元可显著增强ATP诱导的细胞内钙信号，普萘洛尔可消除该信号，蛋白激酶A抑制剂H-89可部分阻断该信号。有趣的是，TNBS注射导致DRG和胰腺中NE浓度显著升高，DRG中β2-肾上腺素能受体表达上调，NE诱导的ATP反应增强。重要的是，嘌呤能受体拮抗剂苏拉明或A317491或β2-肾上腺素能受体拮抗剂布托沙明可显著减轻胰腺痛觉过敏。P2X3R的敏化作用可能由初级感觉神经元中的肾上腺素能信号介导，这有助于胰腺疼痛，从而确定了治疗炎症性胰腺疼痛的潜在靶点。
