Glial cells are involved in multiple cerebral functions that profoundly influence brain tissue viability during ischemia, and astrocytes are the main source of extracellular purines as adenosine and guanosine. The endogenous guanine-based nucleoside guanosine is a neuromodulator implicated in important processes in the brain, such as modulation of glutamatergic transmission and protection against oxidative and inflammatory damage. We evaluated if the neuroprotective effect of guanosine is also observed in cultured cortical astrocytes subjected to oxygen/glucose deprivation (OGD) and reoxygenation. We also assessed the involvement of A₁ and A_2A adenosine receptors and phosphatidylinositol-3 kinase (PI3K), MAPK, and protein kinase C (PKC) signaling pathways on the guanosine effects. OGD/reoxygenation decreased cell viability and glutamate uptake and increased reactive oxygen species (ROS) production in cultured astrocytes. Guanosine treatment prevented these OGD-induced damaging effects. Dipropyl-cyclopentyl-xanthine (an adenosine A₁ receptor antagonist) and 4-[2-[[6-amino-9-(N-ethyl-β-d-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl] benzenepropanoic acid hydrochloride (an adenosine A_2A receptor agonist) abolished guanosine-induced protective effects on ROS production, glutamate uptake, and cell viability. The PI3K pathway inhibitor 2-morpholin-4-yl-8-phenylchromen-4-one, the extracellular-signal regulated kinase kinase (MEK) inhibitor 2′-amino-3′-methoxyflavone, or the PKC inhibitor chelerythrine abolished the guanosine effect of preventing OGD-induced cells viability reduction. PI3K inhibition partially prevented the guanosine effect of reducing ROS production, whereas MEK and PKC inhibitions prevented the guanosine effect of restoring glutamate uptake. The total immunocontent of the main astrocytic glutamate transporter glutamate transporter-1 (GLT-1) was not altered by OGD and guanosine. However, MEK and PKC inhibitions also abolished the guanosine effect of increasing cell-surface expression of GLT-1 in astrocytes subjected to OGD. Then, guanosine prevents oxidative damage and stimulates astrocytic glutamate uptake during ischemic events via adenosine A₁ and A_2A receptors and modulation of survival signaling pathways, contributing to microenvironment homeostasis that culminates in neuroprotection.

中文翻译：

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鸟苷可防止皮质星形胶质细胞培养物中氧/葡萄糖剥夺引起的氧化损伤和谷氨酸摄取障碍：参与A1和A2A腺苷受体以及PI3K，MEK和PKC途径。

胶质细胞参与多种脑功能，深刻影响缺血过程中脑组织的活力，星形胶质细胞是腺嘌呤和鸟苷等胞外嘌呤的主要来源。内源性基于鸟嘌呤的核苷鸟苷是一种神经调节剂，与大脑中的重要过程有关，例如调节谷氨酸能的传递以及防止氧化和炎症损害。我们评估了是否在经过氧/葡萄糖剥夺（OGD）和复氧的培养皮质星形胶质细胞中也观察到了鸟苷的神经保护作用。我们还评估了A ₁和A _2A的参与腺苷受体和磷脂酰肌醇3激酶（PI3K），MAPK和蛋白激酶C（PKC）信号通路对鸟苷的影响。OGD /复氧降低了培养的星形胶质细胞的细胞活力和谷氨酸吸收，并增加了活性氧（ROS）的产生。鸟苷治疗防止了这些由OGD引起的破坏作用。二丙基-环戊基-黄嘌呤（腺苷A ₁受体拮抗剂）和4- [2-[[6-氨基-9-（N-乙基-β - d-核呋喃核糖酰胺基）-9H-嘌呤-2-基]氨基]乙基]苯丙酸盐酸盐（腺苷A _2A受体激动剂）取消了鸟苷诱导的对ROS产生，谷氨酸吸收和细胞活力的保护作用。PI3K途径抑制剂2-吗啉-4-基-8-苯基铬-4--4-酮，细胞外信号调节激酶激酶（MEK）抑制剂2'-氨基-3'-甲氧基黄酮或PKC抑制剂白屈菜红碱消除了鸟苷效应防止OGD诱导的细胞活力降低。PI3K抑制部分阻止了降低ROS产生的鸟苷效应，而MEK和PKC抑制阻止了恢复谷氨酸摄取的鸟苷效应。OGD和鸟嘌呤不会改变主要星形细胞谷氨酸转运蛋白谷氨酸转运蛋白1（GLT-1）的总免疫含量。然而，MEK和PKC抑制作用也消除了在接受OGD的星形胶质细胞中增加GLT-1细胞表面表达的鸟苷效应。然后，鸟苷可在缺血事件中通过腺苷A防止氧化损伤并刺激星形胶质谷氨酸的吸收。₁和A _2A受体以及生存信号通路的调节，促成微环境动态平衡，最终达到神经保护作用。