TY - JOUR
T1 - Human brain glycogen content and metabolism
T2 - Implications on its role in brain energy metabolism
AU - Oz, Gulin
AU - Seaquist, Elizabeth R
AU - Kumar, Anjali
AU - Criego, Amy B.
AU - Benedict, Luke E.
AU - Rao, Jyothi P.
AU - Henry, Pierre-Gilles
AU - Van de Moortele, Pierre-Francois
AU - Gruetter, Rolf
PY - 2007/3
Y1 - 2007/3
N2 - The adult brain relies on glucose for its energy needs and stores it in the form of glycogen, primarily in astrocytes. Animal and culture studies indicate that brain glycogen may support neuronal function when the glucose supply from the blood is inadequate and/or during neuronal activation. However, the concentration of glycogen and rates of its metabolism in the human brain are unknown. We used in vivo localized 13C-NMR spectroscopy to measure glycogen content and turnover in the human brain. Nine healthy volunteers received intravenous infusions of [1-13C]glucose for durations ranging from 6 to 50 h, and brain glycogen labeling and washout were measured in the occipital lobe for up to 84 h. The labeling kinetics suggest that turnover is the main mechanism of label incorporation into brain glycogen. Upon fitting a model of glycogen metabolism to the time courses of newly synthesized glycogen, human brain glycogen content was estimated at ∼3.5 μmol/g, i.e., three- to fourfold higher than free glucose at euglycemia. Turnover of bulk brain glycogen occurred at a rate of 0.16 μmol·g-1·h -1, implying that complete turnover requires 3-5 days. Twenty minutes of visual stimulation (n = 5) did not result in detectable glycogen utilization in the visual cortex, as judged from similar [13C]glycogen levels before and after stimulation. We conclude that the brain stores a substantial amount of glycogen relative to free glucose and metabolizes this store very slowly under normal physiology.
AB - The adult brain relies on glucose for its energy needs and stores it in the form of glycogen, primarily in astrocytes. Animal and culture studies indicate that brain glycogen may support neuronal function when the glucose supply from the blood is inadequate and/or during neuronal activation. However, the concentration of glycogen and rates of its metabolism in the human brain are unknown. We used in vivo localized 13C-NMR spectroscopy to measure glycogen content and turnover in the human brain. Nine healthy volunteers received intravenous infusions of [1-13C]glucose for durations ranging from 6 to 50 h, and brain glycogen labeling and washout were measured in the occipital lobe for up to 84 h. The labeling kinetics suggest that turnover is the main mechanism of label incorporation into brain glycogen. Upon fitting a model of glycogen metabolism to the time courses of newly synthesized glycogen, human brain glycogen content was estimated at ∼3.5 μmol/g, i.e., three- to fourfold higher than free glucose at euglycemia. Turnover of bulk brain glycogen occurred at a rate of 0.16 μmol·g-1·h -1, implying that complete turnover requires 3-5 days. Twenty minutes of visual stimulation (n = 5) did not result in detectable glycogen utilization in the visual cortex, as judged from similar [13C]glycogen levels before and after stimulation. We conclude that the brain stores a substantial amount of glycogen relative to free glucose and metabolizes this store very slowly under normal physiology.
KW - C nuclear magnetic resonance spectroscopy
KW - Glucose
KW - Visual stimulation
UR - http://www.scopus.com/inward/record.url?scp=33947102530&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33947102530&partnerID=8YFLogxK
U2 - 10.1152/ajpendo.00424.2006
DO - 10.1152/ajpendo.00424.2006
M3 - Article
C2 - 17132822
AN - SCOPUS:33947102530
SN - 0193-1849
VL - 292
SP - E946-E951
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 3
ER -