Differential neuronal and glial metabolic response during hypothermia in an experimental animal model.

Abstract

To study the effect of hypothermia on metabolic compartmentalization in an animal model. [1-(13)C] glucose, [2-(13)C] glucose, [3-(13)C] lactate, and [2-(13)C] acetate were infused into male Sprague-Dawley rats. The (13)C label was detected using (13)C-edited H magnetic resonance spectroscopy or (13)C magnetic resonance spectroscopy to determine the isotopic enrichment of both glutamate and glutamine. The infusion was carried out at either normothermia (37 degrees C) or hypothermia (31 degrees C). The [1-(13)C] glucose infusion during hypothermia resulted in decreased labeling of glutamate and glutamine consistent with decreased metabolism or the shunting of glucose through the pentose phosphate pathway. Unexpectedly, [2-(13)C] glucose infusion during hypothermia resulted in decreased labeling of glutamate but not glutamine, implying decreased neuronal but unaltered glial metabolism. The lactate and acetate infusion showed no temperature effect on labeling, indicating that the dampened neuronal metabolism occurred during glycolysis. The results may explain the mechanism of action of hypothermia by differentially preserving the protective metabolism in glia while selectively dampening neuronal metabolism.