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Quantifying hepatic glycogen synthesis by direct and indirect pathways in rats under normal ad libitum feeding conditions
Author(s) -
Soares Ana F.,
Viega Francisco J.,
Carvalho Rui A.,
Jones John G.
Publication year - 2009
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21830
Subject(s) - glycogen , medicine , endocrinology , glycogen synthase , chemistry , streptozotocin , meal , diabetes mellitus , pathophysiology , biology
Hepatic glycogen synthesis from intact hexose (direct pathway) relative to that from gluconeogenic precursors (indirect pathway) was quantified in ad libitum‐fed rats. Following 2 H 2 O administration and overnight feeding, the livers were removed and glycogen 2 H‐enrichment was measured by 2 H NMR. Six controls and six rats rendered hyperglycemic by streptozotocin (STZ; fasting blood glucose = 385 ± 31 mg/dl) were studied. The indirect pathway contribution, estimated as glycogen hydrogen 5 relative to hydrogen 2 enrichment, was 54% ± 4% for control rats—similar to values from healthy, meal‐fed humans. In STZ‐treated rats, the indirect pathway contribution was significantly higher (68% ± 4%, P < 0.05 vs. controls), similar to that of Type 1 diabetic (T1D) patients. In conclusion, sources of hepatic glycogen synthesis in rats during ad libitum nocturnal feeding were quantified by analysis of glycogen enrichment from 2 H 2 O. STZ caused alterations resembling the pathophysiology of hepatic glycogen synthesis in T1D patients. Magn Reson Med 61:1–5, 2009. © 2008 Wiley‐Liss, Inc.