Volume 21, Issue 5 p. A665-A665
Biochemistry (American Society for Biochemistry and Molecular Biology)
Free Access

Absence of gluconeogenesis in the rat small intestine: In vitro carbon 13 NMR and in vivo evidence

Gabriel Baverel

Gabriel Baverel

Metabolomics and Metabolic Diseases, INSERM Unit #499, Laennec Faculty of Medicine, rue G. Paradin, Lyon Cedex 08, 69372 France

Search for more papers by this author
Bernard Ferrier

Bernard Ferrier

Metabolomics and Metabolic Diseases, INSERM Unit #499, Laennec Faculty of Medicine, rue G. Paradin, Lyon Cedex 08, 69372 France

Search for more papers by this author
Mireille Martin

Mireille Martin

Metabolomics and Metabolic Diseases, INSERM Unit #499, Laennec Faculty of Medicine, rue G. Paradin, Lyon Cedex 08, 69372 France

Search for more papers by this author
Agnès Conjard

Agnès Conjard

Metabolomics and Metabolic Diseases, INSERM Unit #499, Laennec Faculty of Medicine, rue G. Paradin, Lyon Cedex 08, 69372 France

Search for more papers by this author
Fadi Saadé

Fadi Saadé

Metabolomics and Metabolic Diseases, INSERM Unit #499, Laennec Faculty of Medicine, rue G. Paradin, Lyon Cedex 08, 69372 France

Search for more papers by this author
Michelle Boghossian

Michelle Boghossian

Metabolomics and Metabolic Diseases, INSERM Unit #499, Laennec Faculty of Medicine, rue G. Paradin, Lyon Cedex 08, 69372 France

Search for more papers by this author
Rémi Nazaret

Rémi Nazaret

Metabolomics and Metabolic Diseases, INSERM Unit #499, Laennec Faculty of Medicine, rue G. Paradin, Lyon Cedex 08, 69372 France

Search for more papers by this author
Guy Martin

Guy Martin

Metabolomics and Metabolic Diseases, INSERM Unit #499, Laennec Faculty of Medicine, rue G. Paradin, Lyon Cedex 08, 69372 France

Search for more papers by this author
First published: 01 April 2007

Abstract

Recent reports have indicated that 48–72h of fasting, type 1 diabetes and high-protein feeding induce gluconeogenesis in the small intestine of adult rats in vivo. Since this would

  1. represent a dramatic revision of the prevailing view that only the liver and the kidneys are gluconeogenic, and
  2. have major consequences in the metabolism, nutrition and diabetes fields, we have thoroughly re-examined this question in the situation reported to induce the highest rate of gluconeogenesis.

For this, metabolically viable small intestinal segments from 72h-fasted adult rats were incubated with [3–13C]glutamine as substrate. After incubation, substrate utilization and product accumulation were measured by enzymatic and NMR methods. Although the segments utilized 13C-glutamine at high rates and accumulated 13C-labeled products linearly for 30 min in vitro, no substantial glucose synthesis could be detected. This was not due to the re-utilization of 13C-glucose initially synthesized. Arteriovenous metabolite concentration difference measurements across the portal vein-drained viscera of 72h-fasted Wistar and Sprague-Dawley rats clearly indicated that glutamine, the main if not the only gluconeogenic precursor taken up, could not give rise to detectable glucose production in vivo. Therefore, we challenge the view that the small intestine of the adult rat is a gluconeogenic organ.

Supported by the INSERM.