基于Orai1蛋白探讨桑白皮治疗糖尿病周围神经病变的分子机制

Diabetic peripheral neuropathy (DPN), one of the most common chronic complications in diabetes mellitus (DM), is characterized by necrosis of dorsal root ganglia (DRG) and axonal degeneration. The internal mechanism is intracellular and extracellular calcium dyshomeostasis of neuron. Increasing evidences indicated that Cortex Mori Radicis could repair nervous injury of DPN, but the detail mechanisms were still unknown. A recent study demonstrated that Orai1, the key component protein of store operated calcium channel (SOCC), was closely related to neuron viability and growth cone sensitivity. Our previous study showed that Cortex Mori Radicis had the hypoglycem effect. Additionally, Cortex Mori Radicis could increase the expression of Orai1, inhibit calcium influx and promote neurite-outgrowth in PC12 cells, which was associated with phosphorylation of ERK1/2. Based on these findings, we hypothesized that the activation of Orai1 related to MAPK signaling pathway might be the molecular mechanism of Cortex Mori Radicis in treatment of DPN. In this study, DRG from STZ-induced diabetic rats and PC12 cells were used to investigate neuron viability, intracellular calcium concentration, expression of Orai1 protein, and change of the MAPK signaling pathway in the presence or absence of Cortex Mori Radicis. Furthermore, we also explored the molecular mechanism of Cortex Mori Radicis on nerve regeneration based on Orai1 protein and Orai1 mediated calcium influx, which would provide the theoretical basis and new option for the clinical treatment of DPN.

糖尿病周围神经病变（DPN）是以背根神经节（DRG）神经元坏死及轴突变性为特征的糖尿病（DM）并发症，内在发病机制是神经元内、外钙失衡。有研究报道：桑白皮可修复DPN神经损伤，但机制不明。最新研究表明：钙池操控钙通道（SOCC）组成蛋白Orai1与神经元活性及生长锥敏感性直接相关。我们前期研究发现：桑白皮能降血糖；能增加PC12细胞中Orai1蛋白表达，抑制钙内流，促进突起生长，其效应机制涉及ERK1/2磷酸化。据此，我们提出：活化Orai1介导的MAPK信号通路，可能是桑白皮治疗DPN的分子机制。本研究拟以DM大鼠DRG神经元和PC12细胞为研究对象，通过桑白皮干预，观察神经元活性、胞内钙浓度、Orai1表达、MAPK通路等的变化，探讨桑白皮对Orai1及介导的Ca2+内流影响神经再生的分子机制，为临床拓展DPN治疗提供科学依据。

糖尿病周围神经病变（DPN）是以背根神经节（DRG）神经元坏死及轴突变性为特征的糖尿病（DM）并发症，其机制是神经元内、外钙失衡。钙池操控钙通道（SOCC）组成蛋白与神经元活性及功能直接相关。桑白皮可修复DPN神经损伤，但机制不明。桑白皮能降血糖；能增加PC12细胞中Orai1蛋白表达，抑制钙内流，促进突起生长，其效应机制涉及MAPKs磷酸化。本研究以DM大鼠DRG神经元和PC12细胞为研究对象，通过桑白皮干预，观察神经元活性、胞内钙浓度、SOCC表达等的变化，探讨桑白皮对SOCC及介导的Ca2+内流影响神经再生的分子机制。本项目研究主要结果： 桑白皮含药血清促进糖尿病大鼠DRG神经元突起生长并减少尼氏体丢失；恢复糖尿病大鼠DRG神经元生长锥对NGF转向；对糖尿病神经元损伤的修复是通过抑制钙内流实现的；对糖尿病大鼠DRG神经元损伤是通过上调TRPC1蛋白表达并通过活化PI3K/Akt途径实现的；可恢复高血糖小鼠DRG神经元尼氏体丢失。因此，我们得出以下结论：桑白皮可明显修复神经元损伤，同时恢复神经元突起功能；其修复作用的可能机制是通过抑制TRPC1介导的钙内流从而从而活化PI3K/Akt信号通路实现的。同时，为了贯彻中医“治未病”思想，借鉴中医药预防糖尿病的养生思路，对小鼠高血糖状态展开进一步探讨，以期找到预防糖尿病的靶点。