Insulin promotes LTP in mice by switching the energy substrate preference of astrocytes to fatty acids [Rattus]

A total of 37,185 transcripts were detected from RNA extracts from primary cultured astrocytes, and neurons isolated from Rattus hippocampus. After exposing astrocytes to insulin (200 nM) for 6h, 883 transcripts were upregulated 2SD or greater and 852 transcripts were downregulated 2SD or greater compared with vehicle treated control astrocyte cultures. This general pattern of gene expression was maintained for at least 12h in astrocytes where the expression of 811 genes were increased and 849 genes decreased compared with vehicle treated astrocytes. Informatic interrogation of genes with expression greater or less than 2 SD at the 6h and 12h time points in astrocytes identified signaling pathways associated with fatty acid activation, fatty acid β-oxidation, cAMP, gap junction, dendritic cell maturation ceramide degradation, triacylglycerol degradation and phospholipase activation. The functional association of gene changes in astrocytes after treatment with insulin for 6 and 12 h were almost exclusively related to the synthesis and storage of diacylglycerides, sterols, and other lipids. After exposing primary cultured Rattus hippocampal neurons to insulin (200 nM) for 6h, 753 genes were upregulated and 660 genes downregulated. This general pattern of gene expression was maintained for at least 12h when 768 genes were upregulated versus 736 genes downregulated in insulin treated neurons. Changes in gene expression profiles of neurons exposed to insulin for 6h, and 12h identified signaling pathways associated with actin-based motility, tight junctions, dendritic cell maturation, serotonin receptor, CREB (cAMP-response element binding protein), and axonal guidance. The functional association of gene changes in neurons after treatment with insulin for 6h, and 12h were largely related to neuroprotective/neurotrophic effects including tyrosine kinase tec-1 activation, synaptogenesis activation, and regulation of actin based cytoskeleton activation by the Rho family GTPases. These data suggest that insulin regulates neurotrophic signaling/functions in neurons and primary regulates lipid metabolism associated with fatty acid oxidation in astrocytes. Effect of Insulin exposure in the regulation of lipid metabolism in the brain. There are two cell types, astrocytes and neurons. For each cell type one sample was treated with insulin for either 6hours, or 12hours and compared to a control of 0minutes treatment, for a total of six samples.

从原代培养的星形胶质细胞以及分离自大鼠海马的神经元的RNA提取物中，共检测到37185个转录本（transcript）。将星形胶质细胞置于200 nM胰岛素中处理6小时后，与溶剂对照的星形胶质细胞培养物相比，有883个转录本的表达上调2倍标准差及以上，852个转录本的表达下调2倍标准差及以上。该基因表达的整体模式在星形胶质细胞中至少可持续12小时：与溶剂对照星形胶质细胞相比，此时有811个基因表达上调，849个基因表达下调。对6小时和12小时时间点下星形胶质细胞中表达差异达2倍标准差以上的基因进行生物信息学分析，发现其富集的信号通路包括脂肪酸激活、脂肪酸β氧化、环磷酸腺苷（cAMP）、间隙连接、树突状细胞成熟、神经酰胺降解、三酰甘油降解及磷脂酶激活通路。胰岛素处理6小时和12小时后，星形胶质细胞中基因表达变化的功能关联几乎全部集中于二酰甘油、固醇及其他脂质的合成与储存过程。将原代培养的大鼠海马神经元置于200 nM胰岛素中处理6小时后，有753个基因表达上调，660个基因表达下调。该基因表达模式至少可持续12小时：胰岛素处理组神经元此时有768个基因上调，736个基因下调。对胰岛素处理6小时和12小时的神经元的基因表达谱变化进行分析，发现其富集的信号通路包括基于肌动蛋白的运动、紧密连接、树突状细胞成熟、5-羟色胺受体、环磷酸腺苷反应元件结合蛋白（CREB，cAMP-response element binding protein）以及轴突导向通路。胰岛素处理6小时和12小时后，神经元中基因表达变化的功能关联主要集中于神经保护/神经营养效应，包括酪氨酸激酶tec-1激活、突触发生激活，以及Rho家族GTP酶对基于肌动蛋白的细胞骨架激活的调控。上述数据表明，胰岛素可调控神经元的神经营养信号通路与功能，并主要调控星形胶质细胞中与脂肪酸氧化相关的脂质代谢过程。本研究探讨胰岛素暴露对大脑脂质代谢的调控作用。实验涉及两种细胞类型：星形胶质细胞与神经元。针对每种细胞类型，分别设置胰岛素处理6小时、12小时的样本，并以未处理（0分钟）的样本作为对照，总计6个样本。