? 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. ? ?
