Editors' ChoiceTraumatic Brain Injury

Amino Acids to the Rescue

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Science Translational Medicine  23 Dec 2009:
Vol. 1, Issue 12, pp. 12ec42
DOI: 10.1126/scitranslmed.3000711

Car crashes, sporting accidents, and domestic violence can result in traumatic brain injury—one of the leading causes of death and disability throughout the world, particularly among young people. Those who survive traumatic brain injury frequently suffer from cognitive difficulties, including problems with learning and memory. Current treatment options, such as reducing pressure in the skull, generally target physical symptoms rather than the underlying mechanisms that cause these impairments. This type of brain injury often damages the hippocampus, a structure necessary for learning and memory, and changes patterns of neuronal behavior. Cole et al. hypothesized that traumatic brain injury–induced variations in the concentrations of the excitatory neurotransmitter glutamate and the inhibitory neurotransmitter γ-aminobutyric acid (GABA) might contribute to this altered neuronal activity. To their surprise, the scientists did not find changes in hippocampal glutamate or GABA concentrations after brain injury in mice. Because these molecules also function in cellular metabolism, this result might indicate an inability to separate the metabolic and neurotransmitter pools. The scientists did, however, see reductions in the concentrations of related molecules—the branched chain amino acids valine, leucine, and isoleucine, which are precursors for glutamate and GABA and required for maintaining the pools of these essential neurotransmitters. Supplying these branched chain amino acids to the mice in their diets after brain injury reversed the changes in neuronal activity patterns and improved the cognitive performance of the mice in behavioral tests. These results indicate that consumption of branched chain amino acids after traumatic brain injury can ameliorate the damage to cognitive function that often occurs.

Cole et al., Dietary branched chain amino acids ameliorate injury-induced cognitive impairment. Proc. Natl. Acad. Sci. U.S.A. 7 December 2009 (10.1073/pnas.0910280107). [Abstract]

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