There is growing evidence that preservation of mitochondrial respiratory function during cerebral ischemia-reperfusion predicts the ultimate extent of tissue injury. Because neurons are selectively vulnerable to ischemic injury, many studies have focused on neuronal mitochondrial dysfunction in ischemia. However, positron emission tomography (PET) studies in animals and humans suggest that non-neuronal cells such as astrocytes may also experience mitochondrial metabolic compromise that contributes to ischemic necrosis. Astrocytes carry out a number of functions that are critical to normal nervous system function, including uptake of neurotransmitters, regulation of pH and ion concentrations, and metabolic support of neurons. Mitochondria are important for many of these actions. We have used a cell culture model of stroke, oxygen-glucose deprivation (OGD), to study the response of astrocyte mitochondria to ischemia, and to evaluate how changes in astrocyte mitochondrial function might affect neuronal survival and recovery after ischemia.

Copper toxicity contributes to neuronal death in Wilson's disease and has been speculatively linked to the pathogenesis of Alzheimer's and prion diseases. We examined copper-induced neuronal death with the goal of developing neuroprotective strategies. Copper catalyzed an increase in hydroxyl radical generation in solution, and the addition of 20 microM copper for 22 hours to murine neocortical cell cultures induced a decrease in ATP levels and neuronal death without glial death. This selective neuronal death was associated with activation of caspase-3 and was reduced by free radical scavengers and Z-Val-Ala-Asp fluoromethylketone, consistent with free radical-mediated injury leading to apoptosis. Pyruvate dehydrogenase is especially vulnerable to inhibition by oxygen free radicals, and the upstream metabolites, pyruvate, phosphoenolpyruvate, and 2-phosphoglycerate were elevated in cortical cells after toxic exposure to copper. One approach to protecting pyruvate dehydrogenase from oxidative attack might be to enhance binding to cofactors. Addition of thiamine, dihydrolipoic acid, or pyruvate reduced copper-induced neuronal death. To test efficacy in vivo, we added 1% thiamine to the drinking water of Long Evans Cinnamon rats, an animal model of Wilson's disease. This thiamine therapy markedly extended life span from 6.0 +/- 1.6 months to greater than 16 months.