Wnt/Ryk信号通路介导的神经定向芽生对根性痛的作用和机制研究

Root pain is the major symptom of lambar disc herniation, however traditional surgery just releases the suppression of intervertebral disc but can not totally eliminate the chronic neuralgia. It is acknowledged that Aβ primary afferent fiber can sprout into lamina II in spinal dorsal horn, and sympathetic fiber can sprout into dorsal root ganglia during noxious stimuli, inflammation, or damage to dorsal root ganglia. This structrual change can bring about the stimulation of imflmmation and immune response in these area, wich regulate the nuronal plasity. Ryk is a novel molecular that is a recptor for axon growth guidance moleculor-Wnt. In our primary work, we found the expression of Ryk was increased in drosal root ganglia. Then immunohistochemistry result indicates that Ryk receptors were expressed in CTb+ neurons which erupt Aβ primary afferent fiber and TH+ sympathetic fiber. And intrathecal injection of Ryk antibody could get a pain relief for CCD rats. So we speculate that Wnt/Ryk signaling in the target area could regulate the orientated sprouting of Aβ primary afferent fiber and sympathetic fiber, which in turn change the neuronal plasiticity in the target area. This study is to clarify the intracellular function of Wnt/Ryk signaling in inducing axon growth guidance and we hope to determine whether or not block Wnt/Ryk signaling can get a relief for root pain. So a lot of study in behavioral work, cytology and molecular biology research need be supported. And the outcome will bring a lot of benefit for new drugs research and clinical therapy.

顽固性根性痛是腰椎间盘突出症的主要症状，而传统外科手术在解除机械性压迫后并未完全消除慢性疼痛。目前认为，这可能与Aβ初级传入纤维和交感神经定向芽生后，引发中枢感觉神经元可塑性变化有关。然而这些神经的定向芽生机制，目前尚未彻底阐明。前期研究证实，在CCD模型中，与神经定向生长的密切相关的Ryk受体在CTb+神经元和交感神经中表达增加。我们进一步通过鞘内注射Ryk受体特异性抗体，并发现有效缓解了CCD模型的痛敏症状。由此，我们推测："分泌蛋白Wnt在CCD模型大鼠脊髓背角和DRG内表达增高。其结合Aβ初级传入纤维和交感神经上的Ryk受体，介导其定向芽生，引发芽生区域神经元痛觉敏化。"本研究以Wnt/Ryk为切入点，拟用CCD模型、形态学、分子生物学等技术证实其在神经定向芽生和根性痛调控中的作用机制，旨在探究神经定向芽生的影响因素，并试图为临床治疗根性痛提供用药靶点，具有重要的理论和临床意义。

神经病理性疼痛严重危害人类健康被称为不死的癌症。神经病理性疼痛的建立不仅涉及神经细胞，神经胶质细胞也参与其中。这些神经细胞形成复杂的网络调控神经系统的免疫炎症。Ryk受体及Wnt信号通路参与神经损伤后修复及再生的调控，近期研究提示Ryk受体参与神经痛的致病过程，但具体机制不明。在我们的研究中发现，在大鼠脊神经结扎模型后，Ryk及Wnt1蛋白在大鼠脊髓表达增高。而Ryk主要表达于脊髓IB4阳性及CGRP阳性神经纤维，这些神经纤维与痛觉有关。而Wnt1表达于激活的星型胶质细胞。这与其他研究的报道不同。在机制研究方面，我们进一步神经电生理实验证实，这种解剖学定位决定了激活脊髓片背角Ryk受体可以增强突触传递，影响神经元兴奋性。而细胞和动物研究受体证实，阻断Ryk受体可以有效抑制在体动物的疼痛行为学以及细胞CCL2释放。这一研究表明了神经星型胶质细胞、无髓神经纤维、小胶质细胞之间的密切联系，促进了神经病理性疼痛的发生。而在具体机制上Ryk可能调控突触前神经炎性递质的分泌影响疼痛。因此Ryk受体也可以成为有潜力的治痛靶点