Contributions of glycogen to astrocytic energetics during brain activation.
Contributions of glycogen to astrocytic energetics during brain activation.
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DOI：
10.1007/s11011-014-9493-8
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发表时间：
2015-02
影响因子：
3.6
通讯作者：
Cruz, Nancy F.
中科院分区：
文献类型：
--
作者：
Dienel, Gerald A.;Cruz, Nancy F.
糖原是大脑中葡萄糖的主要储存，主要存在于星形胶质细胞中。未受刺激、被小心处理的大鼠的脑糖原水平为10-12 mol/g，假设星形胶质细胞占脑质量的一半，星形胶质细胞糖原含量是其两倍。糖原的转换在基础条件下是缓慢的，但在激活过程中被动员起来。在激活过程中，葡萄糖的标签结合没有净增加，而预标记糖原的标签释放超过糖原净消耗，在更强的刺激下，糖原净消耗增加。由于糖原水平通过非氧化代谢恢复，星形胶质细胞可以影响氧与葡萄糖利用的整体比例。在糖原磷酸化酶抑制期间，血糖利用的代偿性增加是很大的，近似于感觉刺激期间的糖原溶解率。相比之下，低血糖期间的糖原分解率较低，这是由于持续的葡萄糖输送和内源性底物的氧化；在没有葡萄糖的情况下保持神经元功能的速率也很低，可能是由于代谢物氧化。模型研究预测，糖原溶解在星形胶质细胞中维持高水平的葡萄糖-6-磷酸，以维持己糖激酶的反馈抑制，从而转移葡萄糖供神经元使用。糖原碳在体内的命运尚不清楚，但脑乳酸外排最好地解释了活脑激活期间的主要代谢特征。大量的穿梭加上糖原衍生乳酸的氧化与现有的证据不一致。糖原在星形胶质细胞能量代谢中发挥重要作用，包括葡萄糖保存、细胞外K+水平控制、氧化应激管理和记忆巩固；它是一种多功能化合物。
Glycogen is the major store of glucose in brain and is mainly in astrocytes. Brain glycogen levels in unstimulated, carefully-handled rats are 10-12 mol/g, and assuming that astrocytes account for half the brain mass, astrocytic glycogen content is twice as high. Glycogen turnover is slow under basal conditions, but it is mobilized during activation. There is no net increase in incorporation of label from glucose during activation, whereas label release from pre-labeled glycogen exceeds net glycogen consumption, which increases during stronger stimuli. Because glycogen level is restored by non-oxidative metabolism, astrocytes can influence the global ratio of oxygen to glucose utilization. Compensatory increases in utilization of blood glucose during inhibition of glycogen phosphorylase are large and approximate glycogenolysis rates during sensory stimulation. In contrast, glycogenolysis rates during hypoglycemia are low due to continued glucose delivery and oxidation of endogenous substrates; rates that preserve neuronal function in the absence of glucose are also low, probably due to metabolite oxidation. Modeling studies predict that glycogenolysis maintains a high level of glucose-6-phosphate in astrocytes to maintain feedback inhibition of hexokinase, thereby diverting glucose for use by neurons. The fate of glycogen carbon in vivo is not known, but lactate efflux from brain best accounts for the major metabolic characteristics during activation of living brain. Substantial shuttling coupled with oxidation of glycogen-derived lactate is inconsistent with available evidence. Glycogen has important roles in astrocytic energetics, including glucose sparing, control of extracellular K+ level, oxidative stress management, and memory consolidation; it is a multi-functional compound.
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影响因子：
16.2
作者：
Choi HB;Gordon GR;Zhou N;Tai C;Rungta RL;Martinez J;Milner TA;Ryu JK;McLarnon JG;Tresguerres M;Levin LR;Buck J;MacVicar BA
通讯作者：
MacVicar BA
影响因子：
6.3
作者：
Dalsgaard, Mads K.;Madsen, Flemming F.;Quistorff, Bjorn
通讯作者：
Quistorff, Bjorn
影响因子：
4.2
作者：
Choi, IY;Seaquist, ER;Gruetter, R
通讯作者：
Gruetter, R
DOI：
10.1097/00004647-200106000-00003
发表时间：
2001-06-01
影响因子：
6.3
作者：
Choi, IY;Lee, SP;Gruetter, R
通讯作者：
Gruetter, R
影响因子：
4.7
作者：
Choi, IY;Tkác, I;Gruetter, R
通讯作者：
Gruetter, R