BACKGROUND AND PURPOSE Ischemic stroke significantly perturbs neuronal homeostasis leading to a cascade of pathologic events causing brain damage. In this study, we assessed acute stroke outcome after chemogenetic inhibition of forebrain excitatory neuronal activity. METHODS We generated hM4Di-TG transgenic mice expressing the inhibitory hM4Di, a Designer Receptors Exclusively Activated by Designer Drugs (DREADD)-based chemogenetic receptor, in forebrain excitatory neurons. Clozapine-N-oxide (CNO) was used to activate hM4Di DREADD. Ischemic stroke was induced by transient occlusion of the middle cerebral artery. Neurologic function and infarct volumes were evaluated. Excitatory neuronal suppression in the hM4Di-TG mouse forebrain was assessed electrophysiologically in vitro and in vivo, based on evoked synaptic responses, and in vivo based on occurrence of potassium-induced cortical spreading depolarizations. RESULTS Detailed characterization of hM4Di-TG mice confirmed that evoked synaptic responses in both in vitro hippocampal slices and in vivo motor cortex were significantly reduced after CNO-mediated activation of the inhibitory hM4Di DREADD. Further, CNO treatment had no obvious effects on physiology and motor function in either control or hM4Di-TG mice. Importantly, hM4Di-TG mice treated with CNO at either 10 min before ischemia or 30 min after reperfusion exhibited significantly improved neurologic function and smaller infarct volumes compared to CNO-treated control mice. Mechanistically, we showed that potassium-induced cortical spreading depression episodes were inhibited, including frequency and duration of DC shift, in CNO-treated hM4Di-TG mice. CONCLUSIONS Our data demonstrate that acute inhibition of a subset of excitatory neurons after ischemic stroke can prevent brain injury and improve functional outcome. This study, together with the previous work in optogenetic neuronal modulation during the chronic phase of stroke, supports the notion that targeting neuronal activity is a promising strategy in stroke therapy.

中文翻译：

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化学遗传学介导的对兴奋性神经元活动的急性抑制可改善卒中预后。

背景与目的缺血性中风会显着干扰神经元稳态，导致一系列病理事件引起脑损伤。在这项研究中，我们评估了前脑兴奋性神经元活动的化学抑制后的急性中风预后。方法我们在前脑兴奋性神经元中表达了表达抑制性hM4Di的hM4Di-TG转基因小鼠，hM4Di是一种基于设计药物（DREADD）的化学生成受体独家激活的设计受体。使用氯氮平-N-氧化物（CNO）激活hM4Di DREADD。缺血性中风是由大脑中动脉的短暂闭塞引起的。评价神经功能和梗死体积。根据诱发的突触反应，在体外和体内通过电生理学评估了hM4Di-TG小鼠前脑的兴奋性神经元抑制作用，并根据钾诱导的皮层扩张去极化的发生在体内进行研究。结果hM4Di-TG小鼠的详细特征证实，在CNO介导的抑制性hM4Di DREADD激活后，体外海马切片和体内运动皮质的诱发突触反应显着降低。此外，CNO处理对对照组或hM4Di-TG小鼠的生理和运动功能均无明显影响。重要的是，与CNO处理的对照小鼠相比，缺血前10分钟或再灌注后30分钟用CNO处理的hM4Di-TG小鼠表现出明显改善的神经功能和较小的梗塞体积。从机理上讲，我们显示了在CNO处理的hM4Di-TG小鼠中，钾诱导的皮质扩散性抑郁发作受到抑制，包括DC移位的频率和持续时间。结论我们的数据表明缺血性中风后急性抑制一部分兴奋性神经元可以预防脑损伤并改善功能结局。这项研究与中风慢性期光遗传神经元调节的先前研究一起，支持了针对神经元活性是中风治疗中一种有前途的策略的观点。