NEURON-GLIA INTERACTIONS IN TRIGEMINAL GANGLIA AS A BASIS FOR FUTURE THERAPY

描述(申请人提供)：最近对脊髓和背根神经节中细胞因子作用的研究表明，神经元-神经胶质细胞的相互作用在启动和维持慢性疼痛状态方面非常重要。这一目标是如何实现的，目前尚不清楚。口腔颌面复合体的紊乱往往会给患者带来剧烈的慢性疼痛，并对他们的健康造成毁灭性的后果。这项研究的长期目标是了解三叉神经节(TG)中神经元和胶质细胞的相互作用，三叉神经节是口面部的主要传入结构。我们的重点将是了解从TGS的神经元胞体(细胞体)释放的递质在神经元-卫星神经胶质细胞通讯中所起的关键作用。我们假设，TG神经元的过度放电会引起神经元胞体释放ATP。ATP激活卫星细胞，并从这些细胞中激发细胞因子的释放。细胞因子反过来使神经元胞体敏化，并进一步增强它们的活性。在体外和体内的方法将被用来检验这一正反馈回路的假说。我们将(1)确定TGS神经元胞体释放的递质(2)检测神经元与卫星细胞之间的通讯(3)确定细胞因子对P2X和TRPV受体介导的反应的影响，(4)检测细胞因子对大鼠伤害性反应的作用并确定使用siRNA下调参与神经元-胶质细胞通讯的受体从而减轻口面部伤害性感受的可能性。将使用正常、炎症和神经结扎的大鼠。递质释放和膜电流将用贴片吸管测量；细胞内钙离子浓度将用钙染料监测；P2X和TRPV受体的表达将用免疫细胞化学和Western分析来检测。这些研究应该能更好地理解TGS中神经元-神经胶质细胞相互作用的机制。这些知识对于设计更好的治疗口腔面部疼痛的方法至关重要。

DESCRIPTION (provided by applicant): Recent studies of cytokine actions in the spinal cord and dorsal root ganglia suggest that neuron-glia interactions are important in initiating and maintaining chronic pain states. How this is accomplished remains unclear. Disorders of the orofacial complex often produce intense chronic pain in patients and results in devastating consequences in their well being. The long-term goal of this research is to understand neuron-glia interactions in the trigeminal ganglion (TG), the primary afferent structure for the orofacial region. Our focus will be to understand the critical role that transmitters released from neuronal somata (cell bodies) of TGs play in neuron- satellite glial cell communication. We hypothesize that excessive firing in TG neurons elicits somatic release of ATP from neuronal somata. ATP activates satellite cells and evokes cytokine release from these cells. Cytokines in turn sensitize the neuronal somata and further increase their activity. In vitro and in vivo approaches will be used to test this hypothesis of positive feedback loop. We will (1) identify the transmitters released from neuronal somata of TGs (2) examine the communication between neuron and satellite cells (3) determine the effects of cytokines on P2X and TRPV receptor-mediated responses, (4) examine the action of cytokines on nociceptive responses in rats and determine the possibility of using siRNA to down-regulate receptors involved in neuron-glia communication and thus to relieve orofacial nociception. Normal, inflamed and nerve-ligated rats will be used. Transmitter release and membrane currents will be measured with patch pipettes; intracellular Ca2+ concentrations will be monitored with Ca2+ dyes; expression of P2X and TRPV receptors will be examined with immunocytochemistry and Western analyses. These studies should provide a better understanding of the mechanisms underlying neuron-glia interactions in TGs. The knowledge will be critical for designing better therapies for the treatment of orofacial pain.