| Hepatic Cannabinoid Receptor-1 Mediates Diet-Induced Insulin Resistance Via Inhibition of Insulin Signaling and Clearance in Mice. | |
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MedLine Citation:
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PMID: 22307032 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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BACKGROUND & AIMS: Obesity-related insulin resistance contributes to cardiovascular disease. Cannabinoid receptor-1 (CB(1)) blockade improves insulin sensitivity in obese animals and people, suggesting endocannabinoid involvement. We explored the role of hepatic CB(1) in insulin-resistance and inhibition of insulin signaling pathways. METHODS: Wild-type mice and mice with disruption of CB(1) (CB(1)(-/-)mice), or with hepatocyte-specific deletion or transgenic overexpression of CB(1)were maintained on regular chow or a high-fat diet (HFD) to induce obesity and insulin resistance. Hyperinsulinemic-euglycemic clamp analysis was used to analyze the role of the liver and hepatic CB(1) in HFD-induced insulin resistance. The cellular mechanisms of insulin resistance were analyzed in mouse and human isolated hepatocytes using small interfering or hairpin RNAs and lentiviral knock-down of gene expression. RESULTS: The HFD induced hepatic insulin resistance in wild-type mice, but not in CB(1)(-/-)mice or mice with hepatocyte-specific deletion of CB(1). CB(1)(-/-)mice that overexpressed CB(1) specifically in hepatocytes became hyperinsulinemic as a result of reduced insulin clearance due to down-regulation of the insulin degrading enzyme. However, they had increased hepatic glucose production due to increased glycogenolysis, indicating hepatic insulin resistance; this was further increased by the HFD. In mice with hepatocytes that express CB(1), the HFD diet or CB(1) activation induced the endoplasmic reticulum (ER) stress response via activation of the Bip-PERK-eIF2α protein translation pathway. In hepatocytes isolated from human or mouse liver, CB(1) activation caused ER stress-dependent suppression of insulin-induced phosphorylation of akt-2 via phosphorylation of IRS1 at serine-307 and by inducing the expression of the serine and threonine phosphatase Phlpp1. Expression of CB(1) was upregulated in samples from patients with non-alcoholic fatty liver disease. CONCLUSIONS: Endocannabinoids contribute to diet-induced insulin resistance in mice via hepatic CB(1)-mediated inhibition of insulin signaling and clearance. |
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Authors:
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Jie Liu; Liang Zhou; Keming Xiong; Grzegorz Godlewski; Bani Mukhopadhyay; Joseph Tam; Shi Yin; Peter Gao; Xin Shan; James Pickel; Ramon Bataller; James O'Hare; Thomas Scherer; Christoph Buettner; George Kunos |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-1-31 |
Journal Detail:
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Title: Gastroenterology Volume: - ISSN: 1528-0012 ISO Abbreviation: - Publication Date: 2012 Jan |
Date Detail:
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Created Date: 2012-2-6 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0374630 Medline TA: Gastroenterology Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved. |
Affiliation:
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Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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