Liu Yingjiao, Chu Shifeng, Hu Yaomei, Yang Songwei, Li Xun, Zheng Qinglian, Ai Qidi, Ren Siyu, Wang Huiqin, Gong Limin, Xu Xin, Chen Nai-Hong
College of Pharmacy, Hunan University of Chinese Medicine & Hunan Engineering Technology Center of Standardization and Function of Chinese Herbal Decoction Pieces, Changsha, 410208, China.
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
Cell Mol Neurobiol. 2021 May;41(4):687-704. doi: 10.1007/s10571-020-00876-5. Epub 2020 Jul 6.
Excitatory toxicity is still a hot topic in the study of ischemic stroke, and related research has focused mainly on neurons. Adenosine is an important neuromodulator that is known as a "biosignature" in the central nervous system (CNS). The protective effect of exogenous adenosine on neurons has been confirmed, but its mechanism remains elusive. In this study, astrocytes were pretreated with adenosine, and the effects of an A2a receptor (A2aR) inhibitor (SCH58261) and A2b receptor (A2bR) inhibitor (PSB1115) on excitatory glutamate were investigated. An oxygen glucose deprivation/reoxygenation (OGD/R) and glutamate model was generated in vitro. Post-model assessment included expression levels of glutamate transporters (glt-1), gap junction protein (Cx43) and glutamate receptor (AMPAR), Na-K-ATPase activity, and diffusion distance of dyes. Glutamate and glutamine contents were determined at different time points. The results showed that (1) adenosine could improve the function of Na-K-ATPase, upregulate the expression of glt-1, and enhance the synthesis of glutamine in astrocytes. This effect was associated with A2aR activation but not with A2bR activation. (2) Adenosine could inhibit the expression of gap junction protein (Cx43) and reduce glutamate diffusion. Inhibition of A2aR attenuated adenosine inhibition of gap junction intercellular communication (GJIC) in the OGD/R model, while it enhanced adenosine inhibition of GJIC in the glutamate model, depending on the glutamate concentration. (3) Adenosine could cause AMPAR gradually entered the nucleus from the cytoplasm, thereby reducing the expression of AMPAR on the cell membrane. Taken together, the results indicate that adenosine plays a role of anti-excitatory toxicity effect in protection against neuronal death and the functional recovery of ischemic stroke mainly by targeting astrocytes, which are closely related to A2aR. The present study provided a scientific basis for adenosine prevention and ischemic stroke treatment, thereby providing a new approach for alleviating ischemic stroke.
兴奋性毒性仍是缺血性中风研究中的一个热门话题，相关研究主要集中在神经元上。腺苷是一种重要的神经调节剂，在中枢神经系统（CNS）中被称为“生物标志物”。外源性腺苷对神经元的保护作用已得到证实，但其机制仍不清楚。在本研究中，用腺苷预处理星形胶质细胞，并研究A2a受体（A2aR）抑制剂（SCH58261）和A2b受体（A2bR）抑制剂（PSB1115）对兴奋性谷氨酸的影响。体外建立氧糖剥夺/复氧（OGD/R）和谷氨酸模型。模型后评估包括谷氨酸转运体（glt-1）、缝隙连接蛋白（Cx43）和谷氨酸受体（AMPAR）的表达水平、钠钾ATP酶活性以及染料的扩散距离。在不同时间点测定谷氨酸和谷氨酰胺含量。结果表明：（1）腺苷可改善钠钾ATP酶功能，上调glt-1表达，并增强星形胶质细胞中谷氨酰胺的合成。这种作用与A2aR激活有关，而与A2bR激活无关。（2）腺苷可抑制缝隙连接蛋白（Cx43）的表达并减少谷氨酸扩散。抑制A2aR可减弱腺苷对OGD/R模型中缝隙连接细胞间通讯（GJIC）的抑制作用，而根据谷氨酸浓度，它在谷氨酸模型中增强了腺苷对GJIC的抑制作用。（3）腺苷可使AMPAR逐渐从细胞质进入细胞核，从而降低细胞膜上AMPAR的表达。综上所述，结果表明腺苷在保护神经元死亡和缺血性中风功能恢复方面发挥抗兴奋性毒性作用，主要通过靶向与A2aR密切相关的星形胶质细胞。本研究为腺苷预防和缺血性中风治疗提供了科学依据，从而为减轻缺血性中风提供了新途径。
