Ji Ning-Ning, Kang Jie, Hua Rong, Zhang Yong-Mei
a Jiangsu Province Key Laboratory of Anesthesiology , Xuzhou Medical University , Xuzhou , China.
c Emergency Center of the Affiliated Hospital of Xuzhou Medical University , Xuzhou , China.
Neurol Res. 2018 Aug;40(8):650-657. doi: 10.1080/01616412.2018.1460702. Epub 2018 Apr 6.
Objective We aimed to investigate the mechanism of paraventricular nucleus (PVN) and ventral tegmental area (VTA) circuit in the pathogenesis of visceral pain-depression with a rat model induced by neonatal and adult colorectal distension (CRD). Methods Neonate male Sprague-Dayley (SD) rats underwent CRD on postnatal days 8, 10, and 12, and when matured, were tested for adult abdominal withdrawal reflex (AWR) scores to assess visceral hypersensitivity. The forced swimming test was employed to evaluate depression-like behaviors. The rats exhibiting visceral pain-depressive behaviors underwent lidocaine injection in the VTA to explore the relationship between VTA and visceral pain. Moreover, double immunofluorescence was employed to evaluate the qualitative and quantitative expression of dopamine/ c-Fos in CRD rats. After verifying the existed fiber projection from PVN to VTA, the intra-PVN microinjection of CRH-RNAi lentivirus to inhibit corticotropin-releasing hormone (CRH) expression, behavioral changes were assessed by AWR score and FST. Thereafter, with the sacrifice of the rats, the variations of TH protein in rats were evaluated by immunofluorescence and Western blot. Results Intra-VTA microinjection of lidocaine increased the pain threshold of CRD group. After intra-VTA microinjection of green retrograde tracer, immunofluorescence photomicrographs visualized the PVN with a typical green retrograde tracer. Intra-PVN microinjection of CRH-RNAi lentivirus alleviated the visceral pain-depression behaviors and decreased the TH protein expression in the VTA. Conclusion These data demonstrated that the VTA played a functional role in chronic visceral pain and depression, and the CRH-containing neurons in hypothalamic PVN may be implicated in the onset and maintenance of the chronic visceral pain and depression via the activation of dopamine in the VTA.
我们旨在通过新生和成年大鼠结肠扩张（CRD）诱导的大鼠模型，研究室旁核（PVN）和腹侧被盖区（VTA）回路在内脏痛性抑郁发病机制中的作用。方法：新生雄性Sprague-Dawley（SD）大鼠在出生后第8、10和12天接受CRD，成年后检测成年腹部退缩反射（AWR）评分以评估内脏超敏反应。采用强迫游泳试验评估抑郁样行为。对表现出内脏痛性抑郁行为的大鼠在VTA注射利多卡因，以探讨VTA与内脏痛之间的关系。此外，采用双重免疫荧光法评估CRD大鼠中多巴胺/c-Fos的定性和定量表达。在证实从PVN到VTA存在纤维投射后，向PVN内微量注射CRH-RNAi慢病毒以抑制促肾上腺皮质激素释放激素（CRH）表达，通过AWR评分和FST评估行为变化。此后，处死大鼠，通过免疫荧光和蛋白质免疫印迹法评估大鼠中TH蛋白的变化。结果：向VTA内微量注射利多卡因可提高CRD组的痛阈。向VTA内微量注射绿色逆行示踪剂后，免疫荧光显微镜照片显示PVN带有典型的绿色逆行示踪剂。向PVN内微量注射CRH-RNAi慢病毒可减轻内脏痛性抑郁行为，并降低VTA中TH蛋白的表达。结论：这些数据表明，VTA在慢性内脏痛和抑郁中发挥功能性作用，下丘脑PVN中含CRH的神经元可能通过激活VTA中的多巴胺参与慢性内脏痛和抑郁的发生和维持。
