Instituto de Tecnologia Química e Biológica - Universidade Nova de Lisboa, and Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal.
J Neurochem. 2010 May;113(3):735-48. doi: 10.1111/j.1471-4159.2010.06636.x. Epub 2010 Feb 5.
Disruption of brain energy metabolism is the hallmark of cerebral ischemia, a major cause of death worldwide. Astrocytes play a key role in the regulation of brain metabolism and their vulnerability to ischemia has been described. Aiming to quantify the effects of an ischemic insult in astrocytic metabolism, primary cultures of astrocytes were subjected to 5 h of oxygen and glucose deprivation in a bioreactor. Flux distributions, before and after ischemia, were estimated by metabolic flux analysis using isotopic information and the consumption/secretion rates of relevant extracellular metabolites as constraints. During ischemia and early recovery, 30% of cell death was observed; several metabolic alterations were also identified reflecting a metabolic response by the surviving cells. In the early recovery ( approximately 10 h), astrocytes up-regulated glucose utilization by 30% and increased the pentose phosphate pathway and tricarboxylic acid cycle fluxes by three and twofold, respectively. Additionally, a two to fivefold enhancement in branched-chain amino acids catabolism suggested the importance of anaplerotic molecules to the fast recovery of the energetic state, which was corroborated by measured cellular ATP levels. Glycolytic metabolism was predominant in the late recovery. In summary, this work demonstrates that changes in fluxes of key metabolic pathways are implicated in the recovery from ischemia in astrocytes.
脑能量代谢障碍是脑缺血的标志，脑缺血是全球范围内主要的死亡原因之一。星形胶质细胞在调节脑代谢中起着关键作用，其对缺血的易感性已被描述。为了定量研究星形胶质细胞代谢受到缺血性损伤的影响，在生物反应器中对星形胶质细胞原代培养物进行了 5 小时的氧葡萄糖剥夺处理。通过代谢通量分析，利用同位素信息和相关细胞外代谢物的消耗/分泌率作为约束条件，在缺血前和缺血后估计通量分布。在缺血和早期恢复期间，观察到 30%的细胞死亡；还确定了几种代谢改变，反映了存活细胞的代谢反应。在早期恢复（约 10 小时）期间，星形胶质细胞将葡萄糖利用率提高了 30%，并使戊糖磷酸途径和三羧酸循环的通量分别增加了 3 倍和 2 倍。此外，支链氨基酸分解代谢增强了 2 到 5 倍，表明了补料分子对能量状态快速恢复的重要性，这与测量的细胞 ATP 水平相符。在晚期恢复中，糖酵解代谢占主导地位。总之，这项工作表明，关键代谢途径通量的变化与星形胶质细胞从缺血中恢复有关。
