Data_Sheet_1_Environmental Enrichment Improves Cognitive Deficits, AD Hallmarks and Epigenetic Alterations Presented in 5xFAD Mouse Model.pdf

Cumulative evidence shows that modifications in lifestyle factors constitute an effective strategy to modulate molecular events related to neurodegenerative diseases, confirming the relevant role of epigenetics. Accordingly, Environmental Enrichment (EE) represents an approach to ameliorate cognitive decline and neuroprotection in Alzheimer’s disease (AD). AD is characterized by specific neuropathological hallmarks, such as β-amyloid plaques and Neurofibrillary Tangles, which severely affect the areas of the brain responsible for learning and memory. We evaluated EE neuroprotective influence on 5xFAD mice. We found a better cognitive performance on EE vs. Control (Ct) 5xFAD mice, until being similar to Wild-Type (Wt) mice group. Neurodegenerative markers as β-CTF and tau hyperphosphorylation, reduced protein levels whiles APPα, postsynaptic density 95 (PSD95) and synaptophysin (SYN) protein levels increased protein levels in the hippocampus of 5xFAD-EE mice group. Furthermore, a reduction in gene expression of Il-6, Gfap, Hmox1 and Aox1 was determined. However, no changes were found in the gene expression of neurotrophins, such as Brain-derived neurotrophic factor (Bdnf), Nerve growth factor (Ngf), Tumor growth factor (Tgf) and Nerve growth factor inducible (Vgf) in mice with EE. Specifically, we found a reduced DNA-methylation level (5-mC) and an increased hydroxymethylation level (5-hmC), as well as an increased histone H3 and H4 acetylation level. Likewise, we found changes in the hippocampal gene expression of some chromatin-modifying enzyme, such as Dnmt3a/b, Hdac1, and Tet2. Extensive molecular analysis revealed a correlation between neuronal function and changes in epigenetic marks after EE that explain the cognitive improvement in 5xFAD.

累积性研究证据表明，调整生活方式相关因素可有效调控与神经退行性疾病相关的分子事件，这证实了表观遗传学（epigenetics）的关键作用。据此，环境富集（Environmental Enrichment，EE）可作为改善阿尔茨海默病（Alzheimer’s disease，AD）认知衰退、发挥神经保护作用的干预手段。阿尔茨海默病具有特征性的神经病理标志，例如β淀粉样斑块与神经原纤维缠结，这些病变会严重损伤负责学习与记忆的脑区。本研究评估了环境富集对5xFAD小鼠的神经保护作用。结果显示，与对照组（Control，Ct）5xFAD小鼠相比，环境富集组小鼠的认知表现更优，最终其认知水平与野生型（Wild-Type，Wt）小鼠组相当。在5xFAD-EE小鼠的海马体中，β-CTF、tau蛋白过度磷酸化等神经退行性标志物的蛋白水平有所降低，而APPα、突触后致密蛋白95（postsynaptic density 95，PSD95）以及突触素（synaptophysin，SYN）的蛋白水平则显著升高。此外，该组小鼠海马体中白细胞介素6（Il-6）、胶质纤维酸性蛋白（Gfap）、血红素氧合酶1（Hmox1）与醛氧化酶1（Aox1）的基因表达水平均出现下调。然而，环境富集并未改变神经营养因子相关基因的表达，例如脑源性神经营养因子（Brain-derived neurotrophic factor，Bdnf）、神经生长因子（Nerve growth factor，Ngf）、肿瘤生长因子（Tumor growth factor，Tgf）以及神经生长因子诱导蛋白（Nerve growth factor inducible，Vgf）。具体而言，我们检测到环境富集组小鼠的DNA甲基化水平（5-mC）降低、DNA羟甲基化水平（5-hmC）升高，同时组蛋白H3与H4的乙酰化水平也有所上升。同样，我们发现部分染色质修饰酶的海马体基因表达出现变化，包括Dnmt3a/b、Hdac1以及Tet2。深入的分子分析显示，环境富集后神经元功能与表观遗传标记的改变之间存在相关性，这一关联可解释5xFAD小鼠的认知改善现象。