Lifespan Metabolic Neuroprotection during Hypoglycemia

描述(由申请人提供)： 该项目的中心假设集中在代谢性神经保护机制，该机制可以在急性低血糖期间和之后维持神经元代谢。在不同程度的低血糖或能量剥夺后，将使用生理学和线粒体成像技术在急性海马片上研究几种不同形式的代谢增强。将密切监测组织切片中的葡萄糖和氧气水平，以确定实际组织水平。几种机制可能有助于增加急性细胞死亡和对低血糖的易感性，从新生儿到老年人，低血糖的易感性在整个生命周期内有很大的不同。有待研究的神经保护机制包括提供中间代谢物，如丙酮酸、乳酸或酮体，增强神经胶质细胞中的糖原储存，以及探索减少新生儿对葡萄糖的需求。由于切片新陈代谢作为切片氧合、组织年龄和切片条件(即界面条件与浸没切片条件)的函数而变化，因此将在组织中使用克拉克式氧气微电极在与电子记录相同的深度进行直接氧分压测量。氧分压监测将确保代谢底物的供应在切片内得到适当控制。同样，组织中的葡萄糖水平将使用微离子导入电极技术进行监测。这些研究将揭示组织中分级低血糖的影响以及一些代谢性神经保护策略，这些策略可能会扩展到饮食治疗，以缓冲间歇性低血糖。

DESCRIPTION (provided by applicant): The central hypothesis of this project focuses on metabolic neuroprotection mechanisms, which can maintain neuronal metabolism during and following acute hypoglycemia. Several different forms of metabolic enhancement will be studied using physiological and mitochondrial imaging techniques in acute hippocampal slices, following various levels of hypoglycemia or energy deprivation. Both glucose and oxygen levels will be tightly monitored in the tissue slices for actual tissue levels. Several mechanisms likely contribute to enhance acute cell death and susceptibility to hypoglycemia, the susceptibility to which varies considerably across the lifespan, from the neonatal period to aging. Neuroprotective mechanisms to be studied include provision of intermediate metabolites, such as pyruvate, lactate or ketone bodies, enhancement of glycogen stores in glial cells, and exploration as to decreased need for glucose in neonatal individuals. Because slice metabolism varies as a function of slice oxygenation, age of the tissue and slice conditions (i.e., interface versus submerged slice conditions), direct oxygen tension measurements will be performed in the tissue using a Clark-style oxygen microelectrode at the same depth as the electrical recordings. The oxygen tension monitoring will ensure that metabolic substrate provision is controlled appropriately within the slice. Similarly, glucose levels in the tissue will be monitored using micro-iontophoresis electrode techniques. These studies will reveal both the effects of graded hypoglycemia in the tissue as well as a number of metabolic neuroprotective strategies, which may be extended to dietary treatments to buffer intermittent hypoglycemia.