Quantitative assessment of cerebral glucose consumption rate (CMRglc) and tricarboxylic acid cycle flux (VTCA) is crucial for understanding neuroenergetics under physiopathological conditions. In this study, we report a novel in vivo Deuterium (2H) MRS (DMRS) approach for simultaneously measuring and quantifying CMRglc and VTCA in rat brains at 16.4 Tesla. Following a brief infusion of deuterated glucose, dynamic changes of isotope-labeled glucose, glutamate/glutamine (Glx) and water contents in the brain can be robustly monitored from their well-resolved 2H resonances. Dynamic DMRS glucose and Glx data were employed to determine CMRglc and VTCA concurrently. To test the sensitivity of this method in response to altered glucose metabolism, two brain conditions with different anesthetics were investigated. Increased CMRglc (0.46 vs. 0.28 µmol/g/min) and VTCA (0.96 vs. 0.6 µmol/g/min) were found in rats under morphine as compared to deeper anesthesia using 2% isoflurane. This study demonstrates the feasibility and new utility of the in vivo DMRS approach to assess cerebral glucose metabolic rates at high/ultrahigh field. It provides an alternative MRS tool for in vivo study of metabolic coupling relationship between aerobic and anaerobic glucose metabolisms in brain under physiopathological states.
Bibliographical noteFunding Information:
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was partly supported by the National Institute of Health, grant numbers R01 NS057560, NS070839, MH111447 and MH111413; R24 MH106049 and MH106049 S1, P41 EB015894, P30 NS076408, and S10 RR025031; and the W.M. Keck Foundation.
© 2017, © The Author(s) 2017.
- Brain glucose metabolisms
- TCA cycle
- cerebral metabolic rate of glucose
- deuterium magnetic resonance spectroscopy (H MRS)