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Dynamics of insulin signalling in liver during hyperinsulinemic euglycaemic clamp conditions in vivo and the effects of high-fat feeding in male mice

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Author: Korsheninnikova, E. · Voshol, P.J. · Baan, B. · Zon, G.C.M. van der · Havekes, L.M. · Romijn, J.A. · Maassen, J.A. · Ouwens, D.M.
Type:article
Date:2007
Institution: TNO Kwaliteit van Leven
Source:Archives of Physiology and Biochemistry, 4-5, 113, 173-185
Identifier: 240235
doi: doi:10.1080/13813450701669084
Keywords: Biology · Biomedical Research · Hepatic glucose production · High-fat diet · Insulin resistance · Insulin signalling · Liver · glucose · insulin · insulin receptor · phosphatidylinositol 3 kinase · protein kinase B · animal · article · blood · C57BL mouse · drug effect · fat intake · gene expression regulation · glucose clamp technique · hyperinsulinism · liver · male · metabolism · mouse · signal transduction · 1-Phosphatidylinositol 3-Kinase · Animals · Dietary Fats · Gene Expression Regulation, Enzymologic · Glucose · Glucose Clamp Technique · Hyperinsulinism · Insulin · Liver · Male · Mice · Mice, Inbred C57BL · Proto-Oncogene Proteins c-akt · Receptor, Insulin · Signal Transduction · Mus

Abstract

Insulin is an important regulator of hepatic carbohydrate, lipid, and protein metabolism, and the regulation of these processes by insulin is disturbed under conditions of insulin resistance and type 2 diabetes. Despite these alterations, the impact of insulin resistance on insulin signalling in the liver is not well defined. Variations in time and dose of insulin stimulation as well as plasma glucose levels may underlie this. The present study aimed at determining the dynamics of activation of hepatic insulin signalling in vivo at insulin concentrations resembling those achieved after a meal, and addressing the effects of high-fat feeding. An unexpected finding of this study was the biphasic activation pattern of the IRS-PI3K-PKB/Akt pathway. Our findings indicate that the first burst of activation contributes to regulation of glucose metabolism. The physiological function of the second peak is still unknown, but may involve regulation of protein synthesis. Finally, high-fat feeding caused hepatic insulin resistance, as illustrated by a reduced suppression of hepatic glucose production. A sustained increased phosphorylation of the serine/threonine kinases p70S6kinase and Jun N-terminal kinase in the absence of insulin may underlie the abrogated phosphorylation of the IRS proteins and their downstream targets.