Department of Paediatrics, Centre for Hormone Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, University of Melbourne, Parkville, Melbourne, VIC 3052, Australia.
Neurochem Res. 2012 Aug;37(8):1768-82. doi: 10.1007/s11064-012-0789-y. Epub 2012 May 8.
There is increasing evidence for glucose fluctuation playing a role in the damaging effects of diabetes on various organs, including the brain. We aimed to study the effects of glycaemic variation (GV) upon mitochondrial activity using an in vitro human neuronal model. The metabolic disturbance of GV in neuronal cells, was mimicked via exposure of neuroblastoma cells SH-SY5Y to constant glucose or fluctuating (i.e. 6 h cycles) for 24 and 48 h. Mitochondrial dehydrogenase activity was determined via MTT assay. Cell mitochondrial activity (MTT) was moderately decreased in constant high glucose, but markedly decreased following 24 and 48 h of cyclical glucose fluctuations. Glucose transport determined via 2-deoxy-D-[1-(14)C] glucose uptake was regulated in an exaggerated manner in response to glucose variance, accompanied by modest changes in GLUT 1 mRNA abundance. Osmotic components of these glucose effects were investigated in the presence of the osmotic-mimics mannitol and L: -glucose. Both treatments showed that fluctuating osmolality did not result in a significant change in mitochondrial activity and had no effects on (14)Cglucose uptake, suggesting that adverse effects on mitochondrial function were specifically related to metabolically active glucose fluctuations. Apoptosis gene expression showed that both intrinsic and extrinsic apoptotic pathways were modulated by glucose variance, with two major response clusters corresponding to (i) glucose stress-modulated genes, (ii) glucose mediated osmotic stress-modulated genes. Gene clustering analysis by STRING showed that most of the glucose stress-modulated genes were components of the intrinsic/mitochondrial apoptotic pathway including Bcl-2, Caspases and apoptosis executors. On the other hand the glucose mediated osmotic stress-modulated genes were mostly within the extrinsic apoptotic pathway, including TNF receptor and their ligands and adaptors/activators/initiators of apoptosis. Fluctuating glucose levels have a greater adverse effect on neuronal cell energy regulation mechanisms than either sustained high or low glucose levels.
越来越多的证据表明，血糖波动在糖尿病对包括大脑在内的各种器官的损害作用中发挥作用。我们旨在使用体外人神经元模型研究血糖变化（GV）对线粒体活性的影响。通过使神经母细胞瘤细胞 SH-SY5Y 持续暴露于高葡萄糖或波动（即 6 小时周期）24 和 48 小时来模拟神经元细胞中的代谢干扰。通过 MTT 测定法测定线粒体脱氢酶活性。持续高葡萄糖会使细胞线粒体活性（MTT）适度降低，但在 24 和 48 小时的循环葡萄糖波动后明显降低。通过 2-脱氧-D-[1-（14）C]葡萄糖摄取来确定葡萄糖转运，葡萄糖变异性会导致其调节过度，同时 GLUT1mRNA 丰度适度变化。在存在渗透压类似物甘露醇和 L：-葡萄糖的情况下，研究了这些葡萄糖作用的渗透压成分。两种处理方法均表明，波动的渗透压不会导致线粒体活性发生显著变化，也不会影响（14）C 葡萄糖摄取，这表明对线粒体功能的不利影响与代谢活跃的葡萄糖波动有关。凋亡基因表达表明，葡萄糖变异性调节了内在和外在凋亡途径，有两个主要的反应簇对应于（i）葡萄糖应激调节基因，（ii）葡萄糖介导的渗透应激调节基因。通过 STRING 进行的基因聚类分析表明，大多数葡萄糖应激调节基因是内在/线粒体凋亡途径的组成部分，包括 Bcl-2、Caspases 和凋亡效应子。另一方面，葡萄糖介导的渗透应激调节基因主要位于外在凋亡途径中，包括 TNF 受体及其配体以及凋亡的衔接子/激活剂/启动子。波动的葡萄糖水平对神经元细胞能量调节机制的不利影响大于持续高或低血糖水平。
