Liu Pei-Yi, Lee I-Hui, Tan Ping-Heng, Wang Yen-Po, Tsai Chia-Fen, Lin Han-Chieh, Lee Fa-Yauh, Lu Ching-Liang
Institute of Brain Science School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan.
Institute of Brain Science School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Neurology, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan.
Cell Mol Gastroenterol Hepatol. 2015 Jul 22;1(6):710-720.e5. doi: 10.1016/j.jcmgh.2015.07.008. eCollection 2015 Nov.
BACKGROUND & AIMS: Molecular mechanisms underlying the activated spinal microglia in association with the pain in chronic pancreatitis (CP) remain unknown. We tested whether P2X7R on spinal microglia mediates the pathogenesis of visceral pain using a CP rat model.
The CP model was induced via intraductal injection of 2% trinitrobenzene sulfonic acid into male Sprague-Dawley rats. Hyperalgesia was assessed based on the mechanical sensitivity to Von-Frey filaments (VFFs), and nocifensive behaviors were measured in response to electrical stimulation of the pancreas. Three weeks after CP induction, spinal cord samples were harvested for immunostaining, immunoblot, and real-time polymerase chain reaction analyses of the P2X7R. Changes in nocifensive behaviors and associated molecular effectors were assessed by blocking spinal cord P2X7R pharmacologically using the selective P2X7R antagonist brilliant blue G (BBG) or genetically using short interfering RNA (siRNA).
CP induced a significant up-regulation of spinal P2X7R expression, which colocalized with a microglial marker (OX-42). Intrathecal administration of BBG significantly attenuated CP-related visceral hyperalgesia in response to VFF-mediated or electrical stimulation of the pancreas, which was associated with suppressed spinal expression of P2X7R and inhibited activation of spinal microglia. Intrathecal injection of siRNA to knock down P2X7R expression in the spinal cord would suppress the nociceptive behaviors in CP rats.
Spinal microglia P2X7R mediates central sensitization of chronic visceral pain in CP. BBG may represent an effective drug for the treatment of chronic pain in CP patients.
慢性胰腺炎（CP）中脊髓小胶质细胞激活与疼痛相关的分子机制尚不清楚。我们使用CP大鼠模型，测试脊髓小胶质细胞上的P2X7R是否介导内脏痛的发病机制。
通过向雄性Sprague-Dawley大鼠胰管内注射2%三硝基苯磺酸诱导建立CP模型。基于对von-Frey细丝（VFF）的机械敏感性评估痛觉过敏，并测量对胰腺电刺激的伤害性反应行为。CP诱导3周后，采集脊髓样本进行P2X7R的免疫染色、免疫印迹和实时聚合酶链反应分析。通过使用选择性P2X7R拮抗剂亮蓝G（BBG）进行药理学阻断或使用小干扰RNA（siRNA）进行基因阻断脊髓P2X7R，评估伤害性反应行为和相关分子效应器的变化。
CP诱导脊髓P2X7R表达显著上调，其与小胶质细胞标志物（OX-42）共定位。鞘内注射BBG可显著减轻CP相关的内脏痛觉过敏，这与VFF介导的或胰腺电刺激引起的反应有关，同时伴有脊髓P2X7R表达的抑制和脊髓小胶质细胞激活的抑制。鞘内注射siRNA以敲低脊髓中P2X7R的表达可抑制CP大鼠的伤害性反应行为。
脊髓小胶质细胞P2X7R介导CP中慢性内脏痛的中枢敏化。BBG可能是治疗CP患者慢性疼痛的有效药物。
