Effect of Chronic Hypernatremic Dehydration and Rapid Rehydration on Brain Carbohydrate, Energy, and Amino Acid Metabolism in Weanling Mice

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Abstract
This is a study of the effects of chronic hypernatremic dehydration and rehydration on carbohydrate, energy and amino acid metabolism in the brains of weanling mice. Chronic hypernatremic dehydration induced by 4 days of water deprivation and salt loading was associated with severe weight loss (no other observed clinical effects), increased brain Na+ levels and a decreased brain water content. Changes in the concentrations of brain glucose, glycolytic and citric acid cycle metabolic intermediates and phosphocreatine were compatible with reduced cerebral metabolic rate. In adaptation to chronic hypernatremia, there was a significant increase in the content of the measured brain amino acids. Rapid rehydration over a 4-h period with 2.5% dextrose in water returned plasma Na+ levels and brain Na+ and water contents to normal. After rehydration, metabolites were altered in a manner consistent with increased fluxes through the glycolytic pathway and citric acid cycle; the brain glycogen content almost tripled. Brain taurine and glutamine levels were not lowered by rehydration, and the total content of the measured amino acids in brain was still significantly higher than in controls. These metabolic perturbations may relate to the development of cerebral edema and seizures or coma following rapid rehydration of humans with chronic hypernatremic dehydration.