Intestinal gluconeogenesis and glucose transport according to body fuel availability in rats
| Autor: | Jean-Hervé Lignot, Hugues Oudart, Caroline Habold, Yvon Le Maho, Charlotte Foltzer-Jourdainne |
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| Rok vydání: | 2005 |
| Předmět: |
2. Zero hunger
endocrine system 0303 health sciences medicine.medical_specialty Physiology Glucose uptake Glucose transporter Biology Apical membrane digestive system 03 medical and health sciences 0302 clinical medicine Intestinal hexose absorption Endocrinology Gluconeogenesis Biochemistry Internal medicine medicine biology.protein GLUT2 Phosphoenolpyruvate carboxykinase 030217 neurology & neurosurgery Cellular localization 030304 developmental biology |
| Zdroj: | The Journal of Physiology. 566:575-586 |
| ISSN: | 0022-3751 |
| DOI: | 10.1113/jphysiol.2005.085217 |
| Popis: | Intestinal hexose absorption and gluconeogenesis have been studied in relation to refeeding after two different fasting phases: a long period of protein sparing during which energy expenditure is derived from lipid oxidation (phase II), and a later phase characterized by a rise in plasma corticosterone triggering protein catabolism (phase III). Such a switch in body fuel uses, leading to changes in body reserves and gluconeogenic precursors, could modulate intestinal gluconeogenesis and glucose transport. The gene and protein levels, and the cellular localization of the sodium–glucose cotransporter SGLT1, and of GLUT5 and GLUT2, as well as that of the key gluconeogenic enzymes phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (Glc6Pase) were measured. PEPCK and Glc6Pase activities were also determined. In phase III fasted rats, SGLT1 was up-regulated and intestinal glucose uptake rates were higher than in phase II fasted and fed rats. PEPCK and Glc6Pase mRNA, protein levels and activities also increased in phase III. GLUT5 and GLUT2 were down-regulated throughout the fast, but increased after refeeding, with GLUT2 recruited to the apical membrane. The increase in SGLT1 expression during phase III may allow glucose absorption at low concentrations as soon as food is available. Furthermore, an increased epithelial permeability due to fasting may induce a paracellular movement of glucose. In the absence of intestinal GLUT2 during fasting, Glc6Pase could be involved in glucose release to the bloodstream via membrane trafficking. Finally, refeeding triggered GLUT2 and GLUT5 synthesis and apical recruitment of GLUT2, to absorb larger amounts of hexoses. |
| Databáze: | OpenAIRE |
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