Tricarboxylic acid cycle of glia in the in vivo human brain

• Published in: NMR in biomedicine Vol. 15; no. 1; pp. 1 - 5
• Main Authors: Blüml, S., Moreno-Torres, A., Shic, F., Nguy, C.-H., Ross, B. D.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.02.2002; Wiley
• Subjects: acetate metabolism; Acetates; Adult; Bicarbonates - metabolism; Biochemistry and metabolism; Biological and medical sciences; Brain - metabolism; Carbon Isotopes; Central nervous system; Citric Acid Cycle; Epilepsy - drug therapy; Epilepsy - metabolism; Female; Fundamental and applied biological sciences. Psychology; glial TCA cycle; Glutamic Acid - metabolism; Glutamine - metabolism; glutamine synthesis; Humans; Investigative techniques, diagnostic techniques (general aspects); Kinetics; Magnetic Resonance Spectroscopy; Male; Medical sciences; Middle Aged; Nervous system; Neuroglia - metabolism; Oxidation-Reduction; proton decoupled 13C MRS; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Valproic Acid - therapeutic use; Vertebrates: nervous system and sense organs; Human; Nervous system diseases; Glial cell; Epilepsy; Central nervous system; NMR spectrometry; Case control study; Cerebral disorder; In vivo; Measurement technique; Central nervous system disease; Oxidation; Quantitative analysis; Brain (vertebrata); Tricarboxylic acid
• ISSN: 0952-3480; 1099-1492
• DOI: 10.1002/nbm.725

In the brain, acetate is exclusively oxidized by glia. To determine the contribution of glial metabolism to the tricarboxylic acid cycle (TCA), 1‐13C‐acetate was infused in six studies in three normal adult subjects and ­one epileptic receiving valproic acid for seizure control. Ten grams of 99% 1‐13C labeled acetate were infused intravenously as a 3.3% w/v solution over 60 min, during which in vivo 13C MR spectra of the brain were acquired. As expected, 13C label rapidly enriched cerebral bicarbonate, glutamate and glutamine C5. The mean rate of acetate oxidation calculated from steady‐state 13C enrichment of bicarbonate in fasted normal subjects was 0.13 ± 0.03 µmol/g/min (n = 4), approximately 20% of the total cerebral TCA cycle rate. Copyright © 2002 John Wiley & Sons, Ltd.