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，其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，将使用生理和线粒体成像技术在急性海马切片中研究几种不同形式的代谢增强。将在组织切片中密切监测葡萄糖和氧气水平，以确定实际组织水平。几种机制可能有助于增强急性细胞死亡和对低血糖的易感性，从新生儿期到衰老，对低血糖的易感性在整个生命周期中变化很大。待研究的神经保护机制包括提供中间代谢物，如丙酮酸盐、乳酸盐或酮体，增强神经胶质细胞中的糖原储存，以及探索新生儿个体对葡萄糖的需求减少。因为切片代谢作为切片氧合、组织年龄和切片条件（即，界面与浸没切片条件），将使用Clark型氧微电极在与电记录相同的深度处在组织中进行直接氧张力测量。氧分压监测将确保在切片内适当控制代谢底物供应。类似地，将使用微离子电渗电极技术监测组织中的葡萄糖水平。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，这些策略可以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.