Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.
BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Sciences, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.
Pharmacol Res Perspect. 2021 Dec;9(6):e00822. doi: 10.1002/prp2.822.
Engineered G protein-coupled receptors (GPCRs) are commonly used in chemogenetics as designer receptors exclusively activated by designer drugs (DREADDs). Although several GPCRs have been studied in astrocytes using a chemogenetic approach, the functional role of the astrocytic G pathway is not clear, as the literature is conflicting depending on the brain regions or behaviors investigated. In this study, we evaluated the role of the astrocytic G pathway in neuroinflammation using a G -coupled DREADD (hM4Di). G -DREADD was expressed in hippocampal astrocytes of a lipopolysaccharide (LPS)-induced neuroinflammation mouse model using adeno-associated viruses. We found that astrocyte G -DREADD stimulation using clozapine N-oxide (CNO) inhibits neuroinflammation, as characterized by decreased levels of proinflammatory cytokines, glial activation, and cognitive impairment in mice. Subsequent experiments using primary astrocyte cultures revealed that G -DREADD stimulation significantly downregulated LPS-induced expression of Nos2 mRNA and nitric oxide production. Similarly, in vitro calcium imaging showed that activation of the astrocytic G pathway attenuated intracellular calcium transients triggered by LPS treatment, suggesting a positive correlation between enhanced calcium transients and the inflammatory phenotype of astrocytes observed in the inflamed brain. Taken together, our results indicate that the astrocytic G pathway plays an inhibitory role in neuroinflammation, providing an opportunity to identify potential cellular and molecular targets to control neuroinflammation.
工程化 G 蛋白偶联受体(GPCRs)在化学遗传学中通常被用作仅被设计药物(DREADDs)激活的设计受体。尽管已经使用化学遗传学方法在星形胶质细胞中研究了几种 GPCRs,但星形胶质细胞 G 途径的功能作用尚不清楚,因为文献根据所研究的脑区或行为而相互矛盾。在这项研究中,我们使用 G 偶联的 DREADD(hM4Di)评估了星形胶质细胞 G 途径在神经炎症中的作用。使用腺相关病毒在脂多糖(LPS)诱导的神经炎症小鼠模型中表达 hM4Di。我们发现,使用氯氮平 N-氧化物(CNO)刺激星形胶质细胞 G-DREADD 可抑制神经炎症,其特征是炎性细胞因子水平降低、神经胶质细胞激活和小鼠认知障碍。使用原代星形胶质细胞培养物进行的后续实验表明,G-DREADD 刺激可显著下调 LPS 诱导的 Nos2 mRNA 表达和一氧化氮产生。同样,在体外钙成像中显示,激活星形胶质细胞 G 途径可减轻 LPS 处理引发的细胞内钙瞬变,这表明增强的钙瞬变与在炎症大脑中观察到的星形胶质细胞的炎症表型之间存在正相关。总之,我们的结果表明,星形胶质细胞 G 途径在神经炎症中发挥抑制作用,为识别控制神经炎症的潜在细胞和分子靶标提供了机会。
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