延髓头端腹内侧区在慢性胰腺炎大鼠持续性疼痛中的作用

目的 研究延髓头端腹内侧区是否参与调节慢性胰腺炎大鼠的持续性疼痛，探讨CP疼痛维持的神经病理机制。方法 三硝基苯磺酸（TNBS）胆胰管灌注诱导大鼠CP模型，分别通过胰腺病理学和大鼠腹部对von-Frey探针机械性刺激的敏感度来评估胰腺炎的程度以及痛觉过敏；Western blot法检测CP诱导后RVM区c-Fos蛋白表达变化；检测RVM区微量注射罗哌卡因后，CP大鼠机械性痛觉过敏的改变。结果 TNBS成功诱导了大鼠慢性胰腺炎，灌注后第7天即出现明显的腹部痛觉过敏，持续至第28天，并引起了RVM区c-Fos蛋白表达上调；RVM区定向注射罗哌卡因显著抑制了大鼠的机械性痛觉过敏（P<0.05）。结论 RVM内注射罗哌卡因可缓解TNBS诱导的CP疼痛，RVM区参与调控CP的持续性疼痛。

Role of the RVM in the Regulation of Persistent Pain in a Rat Model of Chronic Pancreatitis

Objective To investigate whether the rostral ventromedial medulla (RVM) contributes to persistent pain in a rat model of chronic pancreatitis (CP) and to explore the neuropathic mechanism involved in this type of pain. Methods CP was induced by an intraductal perfusion of trinitrobenzene sulfonic acid (TNBS). The severity of CP was assessed by pancreatic histology. Abdominal hyperalgesia, based on the expression of mechanical sensitivity evoked by von-Frey filament, was evaluated after TNBS infusion and after microinjection of ropivacaine into the RVM respectively. The expression of c-Fos in RVM was evaluated by western blot. Results TNBS produced chronic inflammation of pancreas. Prominent abdominal hyperalgesia appeared from day 7 and persisted up to day 28 after TNBS infusion. The expression of c-Fos was up-regulated in CP rats. Microinjection of ropivacaine into the RVM significantly reversed the increase of mechanic hypersensitivity (P<0.05). Conclusion Microinjection of ropivacaine into the RVM attenuate the TNBS-induced pancreatic pain,indicating that RVM contributes to the persistent pain of CP. These findings provide a new direction to investigate the role of central sensitization in the modulation of chronic visceral pain.