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- Title
Human Brain Glycogen Metabolism During and After Hypoglycemia.
- Authors
Öz, Gülin; Kumar, Anjali; Rao, Jyothi P.; Kodl, Christopher T.; Chow, Lisa; Eberly, Lynn E.; Seaquist, Elizabeth R.
- Abstract
OBJECTIVE--We tested the hypotheses that human brain glycogen is mobilized during hypoglycemia and its content increases above normal levels ("supercompensates") after hypoglycemia. RESEARCH DESIGN AND METHODS--We utilized in vivo 13C nuclear magnetic resonance spectroscopy in conjunction with intravenous infusions of [13C]glucose in healthy volunteers to measure brain glycogen metabolism during and after euglycemic and hypoglycemic clamps. RESULTS--After an overnight intravenous infusion of 99% enriched [1-13C]glucose to prelabel glycogen, the rate of label wash-out from [1-13C]glycogen was higher (0.12 ± 0.05 vs. 0.03 ± 0.06 µmol ⋅ g-1 ⋅ h-1, means ± SD, P < 0.02, n = 5) during a 2-h hyperinsulinemic-hypoglycemic clamp (glucose concentration 57.2 ± 9.7 mg/dl) than during a hyperinsulinemic-euglycemic clamp (95.3 ± 3.3 mg/dl), indicating mobilization of glucose units from glycogen during moderate hypoglycemia. Five additional healthy volunteers received intravenous 25-50% enriched [1-13C]glucose over 22-54 h after undergoing hyperinsulinemic-euglycemic (glucose concentration 92.4 ± 2.3 mg/dl) and hyperinsulinemic-hypoglycemic (52.9 ± 4.8 mg/all) clamps separated by at least 1 month. Levels of newly synthesized glycogen measured from 4 to 80 h were higher after hypoglycemia than after euglycemia (P ± 0.01 for each subject), indicating increased brain glycogen synthesis after moderate hypoglycemia. CONCLUSIONS--These data indicate that brain glycogen supports energy metabolism when glucose supply from the blood is inadequate and that its levels rebound to levels higher than normal after a single episode of moderate hypoglycemia in humans. Diabetes 58:1978-1985, 2009
- Subjects
GLYCOGEN; BRAIN; ENERGY metabolism; HYPOGLYCEMIA; BLOOD sugar
- Publication
Diabetes, 2009, Vol 58, Issue 9, p1978
- ISSN
0012-1797
- Publication type
Article
- DOI
10.2337/db09-0226