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Gluconeogenesis in the Livers of Diet‐Restricted Rats‐A 13C Nuclear Magnetic Resonance Study
Author(s) -
Liu Katherine J.M.,
Jarad Jehad,
Donahue Philip E.
Publication year - 1996
Publication title -
journal of parenteral and enteral nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.935
H-Index - 98
eISSN - 1941-2444
pISSN - 0148-6071
DOI - 10.1177/0148607196020003178
Subject(s) - gluconeogenesis , medicine , alanine , endocrinology , pyruvate carboxylase , biology , nuclear magnetic resonance spectroscopy , metabolism , biochemistry , chemistry , amino acid , enzyme , organic chemistry
Background: Gluconeogenic activity is reduced during starvation. However, it is less clear whether the utilization of gluconeogenic substrates is diminished with mild but prolonged diet restriction and, if so, whether there are intrinsic changes in the gluconeogenic pathway. We examined gluconeogenesis in the livers of diet‐restricted rats with 13 C nuclear magnetic resonance (NMR) spectroscopy. Methods: Fischer 344 rats were given 88% (DR group) of what was consumed by the weight‐matched ad libitum‐ fed normal rats (CL group). At the end of 5 weeks, the removed livers were perfused with [3‐ 13 C]alanine while 13 C NMR spectroscopy was performed. Results: The fmal body and liver weights were the same for the two groups. In DR rats, both intrahepatic [3‐ 13 C]alanine and metabolites generated via pyruvate and oxaloacetate, including aspartate and carbamoyl aspartate, appeared in significantly reduced amounts. There was also marked diminution in the production of glucose. Conclusions: In the livers of DR rats, alanine uptake through System A transport, the fluxes through pyruvate carboxylase, the biosynthesis of pyrimidine nucleotides, and the production of glucose from alanine were all significantly decreased with mild intake restriction. Attenuated protein synthesis in the liver of diet‐restricted animals may be the cause for this decreased utilization of alanine for gluconeogenesis. (Journal of Parenteral and Enteral Nutrition 20: 178–181, 1996)