Alterations in cerebral mitochondria during acute hypoglycemia

To test the hypothesis that acute hypoglycemia leads to free radical induced alterations in cerebral mitochondria, newborn piglets were subjected to 2 h of insulin-induced hypoglycemia (blood glucose 1 mmol/l). The effects of free radicals were determined in cerebral cortical synaptosomes, mitochondria, and neuronal nuclei by measuring membrane lipid peroxidation. Fragmentation of nuclear and mitochondrial DNA was also examined. Lipid peroxidation was significantly increased in hypoglycemic mitochondrial membranes as compared to controls, but no increase in peroxidation in hypoglycemic synaptosomal or nuclear membranes was observed. An increase in low molecular weight DNA fragments was observed only in mitochondrial DNA from hypoglycemic piglets. We speculate that alteration of cerebral mitochondria due to increased free radical production is one of the early events in the pathogenesis of hypoglycemic brain injury.