Microglial cytokines mediate plasticity induced by 10 Hz repetitive magnetic stimulation

Microglia—the resident immune cells of the central nervous system—sense the activity of neurons and regulate physiological brain functions. They have been implicated in the pathology of brain diseases associated with alterations in neural excitability and plasticity. However, experimental and therapeutic approaches that modulate microglia function in a brain-region-specific manner have not been established. In this study, we tested for the effects of repetitive transcranial magnetic stimulation (rTMS), a clinically employed non-invasive brain stimulation technique, on microglia-mediated synaptic plasticity. 10 Hz electromagnetic stimulation triggered a release of plasticity-promoting cytokines from microglia in organotypic brain tissue cultures, while no changes in microglial morphology or microglia dynamics were observed. Indeed, substitution of tumor necrosis factor alpha (TNFα) and interleukin 6 (IL6) preserved synaptic plasticity induced by 10 Hz stimulation in the absence of microg..., Ethics statement. Mice were maintained in a 12 h light/dark cycle with food and water available ad libitum. Every effort was made to minimize distress and pain of animals. All experimental procedures were performed according to German animal welfare legislation and approved by the competent authority (Regierungspräsidium Freiburg, G-20/154) appropriate animal welfare committee and the animal welfare officer of Albert-Ludwigs-University Freiburg, Faculty of Medicine (X-17/07K, X-17/09C, X-18/02C). Preparation of tissue cultures. Entorhino-hippocampal tissue cultures were prepared at postnatal day 3–5 from C57BL/6J, HexB-tdTom (Masuda et al., 2020), and C57BL/6-Tg(TNFa-eGFP) (Lenz et al., 2020) mice of either sex as previously described (Del Turco and Deller, 2007). Cultivation medium contained 50% (v/v) MEM, 25% (v/v) basal medium eagle, 25% (v/v) heat-inactivated normal horse serum, 25 mM HEPES buffer solution, 0.15% (w/v) bicarbonate, 0.65% (w/v) glucose, 0.1 mg/ml streptomycin, 100 U/..., Data were analyzed using GraphPad Prism 7 and 9 (GraphPad software, USA).小胶质细胞（Microglia）——中枢神经系统的常驻免疫细胞——能够感知神经元活动并调控大脑的生理功能。它们与伴随神经兴奋性与可塑性改变的脑部疾病病理过程密切相关。然而，能够以脑区特异性方式调控小胶质细胞功能的实验及治疗手段尚未建立。本研究探究了重复性经颅磁刺激（repetitive transcranial magnetic stimulation, rTMS）——一种临床应用的非侵入性脑刺激技术——对小胶质细胞介导的突触可塑性的影响。在器官型脑组织培养体系中，10Hz电磁刺激可触发小胶质细胞释放促进突触可塑性的细胞因子，而未观察到小胶质细胞形态或动力学特征的改变。事实上，在缺乏小胶质细胞的情况下，补充肿瘤坏死因子α（tumor necrosis factor alpha, TNFα）与白细胞介素6（interleukin 6, IL6）可保留10Hz刺激诱导的突触可塑性……（原文此处截断）。 伦理声明：小鼠饲养于12小时明暗循环环境中，自由进食饮水。实验人员尽一切努力减少动物的痛苦与应激。所有实验操作均符合德国动物福利法规，并经主管部门（弗赖堡行政专区政府，G-20/154）、相应动物伦理委员会及弗莱堡阿尔伯特-路德维希大学医学院动物福利官员（X-17/07K、X-17/09C、X-18/02C）批准。 组织培养制备：内嗅皮层-海马组织培养按此前报道的方法（Del Turco与Deller, 2007），于出生后3-5天的雌雄C57BL/6J、HexB-tdTom（Masuda等, 2020）及C57BL/6-Tg(TNFα-eGFP)（Lenz等, 2020）小鼠中制备。培养体系包含50%（体积比）Minimum Essential Medium (MEM)、25%（体积比）基础培养基Eagle、25%（体积比）热灭活正常马血清、25mM HEPES缓冲液、0.15%（质量体积比）碳酸氢盐、0.65%（质量体积比）葡萄糖、0.1mg/ml链霉素、100U/……（原文此处截断）。数据分析采用GraphPad Prism 7和9软件（GraphPad软件公司，美国）。