Stroke is the leading cause of death and disability worldwide. Novel and effective therapies for ischemic stroke are urgently needed. Here, we report that melatonin receptor 1A (MT1) agonist ramelteon is a neuroprotective drug candidate as demonstrated by comprehensive experimental models of ischemic stroke, including a middle cerebral artery occlusion (MCAO) mouse model of cerebral ischemia in vivo, organotypic hippocampal slice cultures ex vivo, and cultured neurons in vitro; the neuroprotective effects of ramelteon are diminished in MT1-knockout (KO) mice and MT1-KO cultured neurons. For the first time, we report that the MT1 receptor is significantly depleted in the brain of MCAO mice, and ramelteon treatment significantly recovers the brain MT1 losses in MCAO mice, which is further explained by the Connectivity Map L1000 bioinformatic analysis that shows gene-expression signatures of MCAO mice are negatively connected to melatonin receptor agonist like Ramelteon. We demonstrate that ramelteon improves the cerebral blood flow signals in ischemic stroke that is potentially mediated, at least, partly by mechanisms of activating endothelial nitric oxide synthase. Our results also show that the neuroprotection of ramelteon counteracts reactive oxygen species-induced oxidative stress and activates the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 pathway. Ramelteon inhibits the mitochondrial and autophagic death pathways in MCAO mice and cultured neurons, consistent with gene set enrichment analysis from a bioinformatics perspective angle. Our data suggest that Ramelteon is a potential neuroprotective drug candidate, and MT1 is the neuroprotective target for ischemic stroke, which provides new insights into stroke therapy. MT1-KO mice and cultured neurons may provide animal and cellular models of accelerated ischemic damage and neuronal cell death.

中文翻译：

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MT1受体作为雷美替胺对缺血性中风神经保护的靶点

中风是全世界死亡和残疾的主要原因。迫切需要针对缺血性中风的新颖有效的疗法。在这里，我们报告褪黑素受体 1A (MT1) 激动剂雷美替胺是一种神经保护候选药物，缺血性中风的综合实验模型证明了这一点，包括大脑中动脉闭塞 (MCAO) 小鼠体内脑缺血模型、器官型海马切片培养物体内和体外培养的神经元；雷美替胺的神经保护作用在 MT1 敲除 (KO) 小鼠和 MT1-KO 培养的神经元中减弱。我们首次报告 MCAO 小鼠大脑中 MT1 受体显着减少，而雷美替胺治疗显着恢复了 MCAO 小鼠大脑中 MT1 的损失，显示基因表达的 Connectivity Map L1000 生物信息学分析进一步解释了这一点MCAO 小鼠的特征与 Ramelteon 等褪黑激素受体激动剂呈负相关。我们证明雷美替胺可以改善缺血性中风中的脑血流信号，这可能至少部分是通过激活内皮一氧化氮合酶的机制介导的。我们的结果还表明，雷美替胺的神经保护作用可以抵消活性氧诱导的氧化应激，并激活核因子红细胞 2 相关因子 2/血红素加氧酶-1 通路。Ramelteon 抑制 MCAO 小鼠和培养神经元的线粒体和自噬死亡途径，这与生物信息学角度的基因集富集分析一致。我们的数据表明，Ramelteon 是一种潜在的神经保护候选药物，而 MT1 是缺血性脑卒中的神经保护靶点，这为脑卒中治疗提供了新的见解。MT1-KO小鼠和培养的神经元可以提供加速缺血性损伤和神经元细胞死亡的动物和细胞模型。