Regionally Selective Metabolic Effects of Hypoglycemia in Brain

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Abstract
Regional CNS levels of glucose reserves, glycolytic intermediates, and high-energy phosphate reserves were measured in insulin-treated, hypoglycemic rats and correlated with EEG activity. I.v. administration of insulin to paralyzed, ventilated animals causes concomitant reduction of blood glucose levels and progressive abnormality and eventual loss of EEG activity. In all regions of brain examined, glucose and glycogen levels decrease until they are essentially depleted, and G-6-P and fructose-1,6-biphosphate fall approximately 80%. Pyruvate levels decrease 50% in cerebral cortex and brain stem and a lesser amount in striatum, hippocampus, thalamus and cerebellum. Lactate levels fall 50-60% in all regions except cerebellum, where no change is observed. ATP and phosphocreatine levels remain normal until the EEG is isoelectric, and then decrease in all regions except cerebellum. Hypoglycemia does not apparently have a uniform effect on brain glucose and energy metabolism, and cerebellum seems relatively protected.