Effect of Hypoglycemia on brain glycogen metabolism in vivo
Effect of Hypoglycemia on brain glycogen metabolism in vivo
复制标题
DOI：
10.1002/jnr.10574
复制
发表时间：
2003-04-01
影响因子：
4.2
通讯作者：
Gruetter, R
中科院分区：
文献类型：
--
作者：
Choi, IY;Seaquist, ER;Gruetter, R
大脑中含有少量但数量可观的糖原，长期以来一直被认为在大脑中起着微不足道的作用。在这项研究中，使用9.4T的C-13 NMR光谱测量脑糖原代谢。脑糖原代谢受高胰岛素血症的调节，导致净积累。糖原在维持脑功能中的作用尚不清楚;一种可能性是它可能作为内源性葡萄糖储存库，以保护大脑免受严重低血糖的影响。为了解决这种可能性，大鼠受到胰岛素诱导的中度低血糖，当脑葡萄糖水平接近零时，脑糖原含量开始逐渐减少，表明利用了这种葡萄糖储库。然而，即使在2小时的低血糖期间，脑糖原信号也从未变得不可检测。当血浆和脑葡萄糖浓度恢复时，糖原增加，浓度超过降血糖前水平数倍。这些数据表明，当葡萄糖供应不足时，脑糖原可以在很长一段时间内提供燃料。此外，脑糖原可在单次低血糖发作后反弹（超补偿）。我们推测，脑糖原在低血糖期间充当能量储存，并且它可能参与创建对低血糖的生理反应降低，这涉及糖尿病患者中经常观察到的症状，低血糖无意识。(C)2003 Wiley-Liss，Inc.
The brain contains a small but significant amount of glycogen, which has long been considered to play an insignificant role in the brain. In this study, brain glycogen metabolism was measured using C-13 NMR spectroscopy at 9.4 T. Brain glycogen metabolism was modulated by hyperinsulinemia resulting in a net accumulation. The role of glycogen in maintaining brain function is unknown; one possibility is that it may serve as an endogenous glucose reservoir to protect the brain against severe hypoglycemia. To address this possibility, rats were subjected to insulin-induced moderate hypoglycemia and when the level of brain glucose approached zero, brain glycogen content began to decrease gradually, demonstrating utilization of this glucose reservoir. The brain glycogen signal never became undetectable, however, even during 2 hr of hypoglycemia. When plasma and brain glucose concentrations were restored, glycogen increased and the concentration exceeded the prehypoglycemic level by several-fold. The data suggest that brain glycogen can provide fuel for extended periods of time when glucose supply is inadequate. Furthermore, brain glycogen can rebound (super-compensate) after a single episode of hypoglycemia. We postulate that brain glycogen serves as an energy store during hypoglycemia and that it may participate in the creation of reduced physiological responses to hypoglycemia that are involved in a symptom often observed in patients with diabetes, hypoglycemia unawareness. (C) 2003 Wiley-Liss, Inc.