In vivo 13C NMR assessment of brain glycogen concentration and turnover in the awake rat.
Brain glycogen metabolism was recently observed in vivo and found to be very slow in the lightly alpha-chloralose anesthetized rat [J. Neurochem. 73 (1999) 1300]. Based on that slow turnover, the total glycogen content in the awake rat brain and its turnover time were assessed after administering 13C-labeled glucose for 48 h. Label incorporation into glycogen, glucose, amino acid, and N-acetyl-aspartate (NAA) resonances was observed. The amount of 13C label incorporated into glycogen was variable and did not correlate with that in glutamate (r=-0.1, P>0.86). However, the amount of 13C label incorporated into glycogen was very similar to that in NAA (r=0.93), implying similar turnover times between brain glycogen and NAA (approximately 10 h). Absolute quantification of the total concentration of brain glycogen in the awake, normoglycemic rat yielded 3.3+/-0.8 micromol/g (n=6, mean+/-S.D.).
Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota Medical School, 2021 6th Street SE, Minneapolis, MN 55455, USA.
In-Young
IY
Choi
Rolf
R
Gruetter
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002247:Carbon Isotopes; D006003:Glycogen / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014851:Wakefulness
D002247:Carbon Isotopes; D006003:Glycogen