Non-alcoholic fatty liver disease (NAFLD) is closely associated with obesity and insulin resistance. To better understand the pathophysiology of obesity-associated NAFLD, the present study examined the involvement of liver and adipose tissues in metformin actions on reducing hepatic steatosis and inflammation during obesity. C57BL/6J mice were fed a high-fat diet (HFD) for 12 weeks to induce obesity-associated NAFLD and treated with metformin (150 mg/kg/d) orally for the last four weeks of HFD feeding. Compared with HFD-fed control mice, metformin-treated mice showed improvement in both glucose tolerance and insulin sensitivity. Also, metformin treatment caused a significant decrease in liver weight, but not adiposity. As indicated by histological changes, metformin treatment decreased hepatic steatosis, but not the size of adipocytes. In addition, metformin treatment caused an increase in the phosphorylation of liver AMP-activated protein kinase (AMPK), which was accompanied by an increase in the phosphorylation of liver acetyl-CoA carboxylase and decreases in the phosphorylation of liver c-Jun N-terminal kinase 1 (JNK1) and in the mRNA levels of lipogenic enzymes and proinflammatory cytokines. However, metformin treatment did not significantly alter adipose tissue AMPK phosphorylation and inflammatory responses. In cultured hepatocytes, metformin treatment increased AMPK phosphorylation and decreased fat deposition and inflammatory responses. Additionally, in bone marrow-derived macrophages, metformin treatment partially blunted the effects of lipopolysaccharide on inducing the phosphorylation of JNK1 and nuclear factor kappa B (NF-κB) p65 and on increasing the mRNA levels of proinflammatory cytokines. Taken together, these results suggest that metformin protects against obesity-associated NAFLD largely through direct effects on decreasing hepatocyte fat deposition and on inhibiting inflammatory responses in both hepatocytes and macrophages.
Metformin Ameliorates Hepatic Steatosis and Inflammation without Altering Adipose Phenotype in Diet-Induced Obesity
S. Woo,Hang Xu,Honggui Li,Yan Zhao,Xiang Hu,Jiajia Zhao,Xin Guo,Ting Guo,Rachel Botchlett,Ting Qi,Ya Pei,Juan Zheng,Yiming Xu,Xiaofei An,Lu-Fang Chen,Lili Chen,Qifu Li,Xiaoqiu Xiao,Yuqing Huo,Chaodong Wu
Published 2014 in PLoS ONE
ABSTRACT
PUBLICATION RECORD
- Publication year
2014
- Venue
PLoS ONE
- Publication date
2014-03-17
- Fields of study
Biology, Medicine, Chemistry, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
- Metformin directly increased AMPK phosphorylation and reduced fat deposition and inflammatory responses in cultured hepatocytes, and it partially blunted LPS-induced JNK1 and NF-kB p65 phosphorylation and proinflammatory cytokine expression in bone marrow-derived macrophages.박진우 (dztg5apj7m) extractionAnonymous (12632b8b5f) review
CONCEPTS
- adipose tissue phenotype
The adipose-tissue state examined through adiposity, adipocyte size, and adipose AMPK and inflammatory readouts.
Aliases: adiposity, adipocyte phenotype
박진우 (dztg5apj7m) extractionAnonymous (12632b8b5f) review - bone marrow-derived macrophages
Macrophages differentiated from bone marrow cells and used to examine metformin effects on inflammatory signaling in vitro.
Aliases: BMDMs
박진우 (dztg5apj7m) extractionAnonymous (12632b8b5f) review - cultured hepatocytes
Isolated liver parenchymal cells used to test direct cellular effects of metformin in vitro.
Aliases: hepatocytes
박진우 (dztg5apj7m) extractionAnonymous (12632b8b5f) review - hepatic steatosis
Excess lipid accumulation in the liver, assessed here by histological changes and liver lipid deposition.
Aliases: fatty liver, liver steatosis
박진우 (dztg5apj7m) extractionAnonymous (12632b8b5f) review - liver ampk phosphorylation
Phosphorylation of AMP-activated protein kinase measured in liver tissue as a signaling readout.
Aliases: hepatic AMPK phosphorylation, AMPK phosphorylation in liver
박진우 (dztg5apj7m) extractionAnonymous (12632b8b5f) review - metformin
An oral antidiabetic drug used in the experiment at 150 mg/kg/day during the final four weeks of high-fat feeding.
Aliases: MET
박진우 (dztg5apj7m) extractionAnonymous (12632b8b5f) review - obesity-associated nafld
A mouse liver disease state induced by high-fat diet feeding and characterized by obesity-related fatty liver changes.
Aliases: NAFLD, non-alcoholic fatty liver disease
박진우 (dztg5apj7m) extractionAnonymous (12632b8b5f) review
REFERENCES
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