Data_Sheet_1_Spatial Memory and Microglia Activation in a Mouse Model of Chronic Neuroinflammation and the Anti-inflammatory Effects of Apigenin.docx

Chronic neuroinflammation characterized by microglia reactivity is one of the main underlying processes in the initiation and progression of neurodegenerative diseases such as Alzheimer’s disease. This project characterized spatial memory during healthy aging and prolonged neuroinflammation in the chronic neuroinflammatory model, glial fibrillary acidic protein-interleukin 6 (GFAP-IL6). We investigated whether chronic treatment with the natural flavonoid, apigenin, could reduce microglia activation in the hippocampus and improve spatial memory. GFAP-IL6 transgenic and wild-type-like mice were fed with apigenin-enriched or control chow from 4 months of age and tested for spatial memory function at 6 and 22 months using the Barnes maze. Brain tissue was collected at 22 months to assess microgliosis and morphology using immunohistochemistry, stereology, and 3D single cell reconstruction. GFAP-IL6 mice showed age-dependent loss of spatial memory recall compared with wild-type-like mice. Chronic apigenin treatment decreased the number of Iba-1+ microglia in the hippocampus of GFAP-IL6 mice and changed microglial morphology. Apigenin did not reverse spatial memory recall impairment in GFAP-IL6 mice at 22 months of age. GFAP-IL6 mice may represent a suitable model for age-related neurodegenerative disease. Chronic apigenin supplementation significantly reduced microglia activation, but this did not correspond with spatial memory improvement in the Barnes Maze.

以小胶质细胞反应性为特征的慢性神经炎症，是阿尔茨海默病等神经退行性疾病发生与进展的主要潜在病理过程之一。本研究针对健康衰老状态，以及慢性神经炎症模型——胶质纤维酸性蛋白-白细胞介素6（glial fibrillary acidic protein-interleukin 6, GFAP-IL6）中的空间记忆进行了系统表征。我们探究了天然黄酮类化合物芹菜素（apigenin）的长期给药方案，能否减轻海马体小胶质细胞活化并改善空间记忆功能。
实验将GFAP-IL6转基因小鼠与野生型相似小鼠分为两组，自4月龄起分别喂食富含芹菜素的饲料或对照饲料，并于6月龄和22月龄时采用巴恩斯迷宫（Barnes maze）检测小鼠的空间记忆能力。于22月龄时采集脑组织样本，通过免疫组织化学（immunohistochemistry）、体视学（stereology）及三维单细胞重建（3D single cell reconstruction）技术，评估小胶质细胞增生情况与细胞形态特征。
结果显示，与野生型相似小鼠相比，GFAP-IL6小鼠表现出随年龄增长的空间记忆回忆能力损伤。长期芹菜素给药可降低GFAP-IL6小鼠海马体中离子钙接头蛋白1阳性（Iba-1+）小胶质细胞的数量，并改变小胶质细胞的形态。但在22月龄时，芹菜素并未逆转GFAP-IL6小鼠的空间记忆回忆损伤。
GFAP-IL6小鼠可作为年龄相关性神经退行性疾病的合适研究模型。长期芹菜素补充可显著减轻小胶质细胞活化，但该效应并未与巴恩斯迷宫检测到的空间记忆改善相一致。