不同碳纳米材料对星形胶质细胞神经递质稳态的影响及其机制研究

Carbon nanomaterials (CNMs) have gained great attentions by their applications in industrial and biomedical fields, including the applications in therapy and diagnosis of central nervous system disease. The potential of CNMs to enter into brain tissue raises increasing concerns about their neurotoxicity. However, the effects of CNMs on central nervous system and the underlying mechanisms are still unclear. Based on the evidence that hemichannels involve the regulatory mechanisms of glutamate and ATP homeostasis of astrocytes, we will investigate whether different CNMs (single-walled carbon nanotubes, polyethylene glycol modified single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene and graphene oxide) could regulate glutamate and ATP release from cultured astrocytes, and the involvement of hemichannels and purinergic receptors in the release mechanism. In addition, We will evaluate the effects of CNMs-induced glutamate and ATP release from astrocytes on neuronal cells. Our study will provide novel evidence about the mechanisms for neurotoxicity caused by CNMs. It is also expected to be useful for safety evaluation of CNMs and the development of nanostructure-based medical technology for therapy and diagnosis of brain diseases.

碳纳米材料（CNMs）的广泛应用可能通过环境污染因素和神经生物医学应用两方面增加人体脑组织对其暴露的风险。然而CNMs对中枢神经系统的作用及分子机制目前还不清楚。本项目在间隙连接半通道和腺苷酸受体参与星形胶质细胞神经递质谷氨酸和ATP稳态调节的研究基础上，结合不同CNMs安全性评价的需求，评价单壁碳纳米管、聚乙二醇修饰的单壁碳纳米管、多壁碳纳米管、石墨烯及氧化石墨烯对体外培养的星形胶质细胞谷氨酸和ATP释放的影响及其作用特征，同时探讨CNMs对间隙连接半通道和腺苷酸受体的激活效应及其在谷氨酸和ATP释放中的作用，以阐明CNMs对星形胶质细胞神经递质稳态的影响及其机制；另外，进一步开展谷氨酸和ATP稳态改变对神经元细胞的影响，揭示CNMs神经毒性作用的分子机制；同时比较不同碳纳米材料的效应和特征，为CNMs的设计改进和神经生物医学的安全应用提供科学依据。

碳纳米管可能在制备和使用环节如神经生物医学应用的过程中，增加人体多个系统，包括神经系统的暴露风险。为进一步阐明纳米碳管的生物学作用机制，完善其安全性评价方法，本项目评价了不同修饰和不同长度多壁纳米碳管对体外培养的星形胶质细胞半通道活性及其谷氨酸和ATP释放水平的影响和机制。此外，还探讨了多壁纳米碳管通过星形胶质细胞介导的神经元毒性效应及其机制。研究发现，多壁纳米碳管可使星形胶质细胞半通道活性呈浓度依赖性增加，这与细胞膜上半通道蛋白表达增加以及Ser368位点的半通道蛋白Cx43蛋白去磷酸化水平增加有关。长多壁纳米碳管引起的半通道活性改变比短多壁纳米碳管以及羧基修饰的多壁纳米碳管更加明显。多壁纳米碳管处理后，星形胶质细胞神经递质ATP和谷氨酸释放呈现浓度依赖性增加，且此过程与Cx43和Panx1半通道开放有关；长多壁纳米碳管处理后引起的ATP释放水平较其它两种多壁纳米碳管明显增加。多壁纳米碳管处理后间接引起的神经元损伤与星形胶质细胞半通道激活有关，与胶质细胞神经递质的累积有关，且神经元半通道激活参与到其机制中。阻断星形胶质细胞半通道或阻断神经元表面谷氨酸和ATP受体均能显著降低神经元损伤。研究结果可为临床上相关靶点药物开发提供机制性数据，以及为碳纳米管特性的改进以及在神经生物医学领域的安全应用提供科学依据。