Delayed cerebral oxidative glucose metabolism after traumatic brain injury in young rats
Article first published online: 7 APR 2009
© 2009 The Authors. Journal Compilation © 2009 International Society for Neurochemistry
Journal of Neurochemistry
Special Issue: The Third ISN Special Neurochemistry Conference/8th International Meeting for Brain Energy Metabolism “Neurodegeneration and Regeneration”
Volume 109, Issue Supplement s1, pages 189–197, May 2009
How to Cite
Scafidi, S., O’Brien, J., Hopkins, I., Robertson, C., Fiskum, G. and McKenna, M. (2009), Delayed cerebral oxidative glucose metabolism after traumatic brain injury in young rats. Journal of Neurochemistry, 109: 189–197. doi: 10.1111/j.1471-4159.2009.05896.x
- Issue published online: 7 APR 2009
- Article first published online: 7 APR 2009
- Received November 4, 2008; revised manuscript received November 12, 2008; accepted December 16, 2008.
- 13C-NMR spectroscopy;
- immature brain;
- traumatic brain injury
Traumatic brain injury (TBI) results in a cerebral metabolic crisis that contributes to poor neurologic outcome. The aim of this study was to characterize changes in oxidative glucose metabolism in early periods after injury in the brains of immature animals. At 5 h after controlled cortical impact TBI or sham surgery to the left cortex, 21–22 day old rats were injected intraperitoneally with [1,6-13C]glucose and brains removed 15, 30 and 60 min later and studied by ex vivo 13C-NMR spectroscopy. Oxidative metabolism, determined by incorporation of 13C into glutamate, glutamine and GABA over 15–60 min, was significantly delayed in both hemispheres of brain from TBI rats. The most striking delay was in labeling of the C4 position of glutamate from neuronal metabolism of glucose in the injured, ipsilateral hemisphere which peaked at 60 min, compared with the contralateral and sham-operated brains, where metabolism peaked at 30 and 15 min, respectively. Our findings indicate that (i) neuronal-specific oxidative metabolism of glucose at 5–6 h after TBI is delayed in both injured and contralateral sides compared with sham brain; (ii) labeling from metabolism of glucose via the pyruvate carboxylase pathway in astrocytes was also initially delayed in both sides of TBI brain compared with sham brain; (iii) despite this delayed incorporation, at 6 h after TBI, both sides of the brain showed apparent increased neuronal and glial metabolism, reflecting accumulation of labeled metabolites, suggesting impaired malate aspartate shuttle activity. The presence of delayed metabolism, followed by accumulation of labeled compounds is evidence of severe alterations in homeostasis that could impair mitochondrial metabolism in both ipsilateral and contralateral sides of brain after TBI. However, ongoing oxidative metabolism in mitochondria in injured brain suggests that there is a window of opportunity for therapeutic intervention up to at least 6 h after injury.