scholarly journals Obesity-Induced Inflammation in White Adipose Tissue Is Attenuated by Loss of Melanocortin-3 Receptor Signaling

Endocrinology ◽  
2007 ◽  
Vol 148 (12) ◽  
pp. 6186-6194 ◽  
Author(s):  
Kate L. J. Ellacott ◽  
Jonathan G. Murphy ◽  
Daniel L. Marks ◽  
Roger D. Cone
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Adipose Tissue ◽  
Liver Disease ◽  
Inflammatory Response ◽  
White Adipose Tissue ◽  
Fatty Liver Disease ◽  
Chow Diet ◽  
High Fat ◽  
Deficient Mice

Metabolic syndrome, a complex of highly debilitating disorders that includes insulin resistance, hypertension, and dyslipidemia, is associated with the development of obesity in humans as well as rodent models. White adipose tissue (WAT) inflammation, caused in part by macrophage infiltration, and fat accumulation in the liver are both linked to development of the metabolic syndrome. Despite large increases in body fat, melanocortin 3-receptor (MC3-R)-deficient mice do not get fatty liver disease or severe insulin resistance. This is in contrast to obese melanocortin 4-receptor (MC4-R)-deficient mice and diet-induced obese (DIO) mice, which show increased adiposity, fatty liver disease, and insulin resistance. We hypothesized that defects in the inflammatory response to obesity may underlie the protection from metabolic syndrome seen in MC3-R null mice. MC4-R mice fed a chow diet show increased proinflammatory gene expression and macrophage infiltration in WAT, as do wild-type (WT) DIO mice. In contrast, MC3-R-deficient mice fed a normal chow diet show neither of these inflammatory changes, despite their elevated adiposity and a comparable degree of adipocyte hypertrophy to the MC4-R null and DIO mice. Furthermore, even when challenged with high-fat chow for 4 wk, a period of time shown to induce an inflammatory response in WAT of WT animals, MC3-R nulls showed an attenuated up-regulation in both monocyte chemoattractant protein-1 (MCP-1) and TNFα mRNA in WAT compared with WT high-fat-fed animals.

scholarly journals Estrogens Protect against High-Fat Diet-Induced Insulin Resistance and Glucose Intolerance in Mice

Endocrinology ◽  
2009 ◽  
Vol 150 (5) ◽  
pp. 2109-2117 ◽  
Author(s):  
Elodie Riant ◽  
Aurélie Waget ◽  
Haude Cogo ◽  
Jean-François Arnal ◽  
Rémy Burcelin ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Glucose Intolerance ◽  
High Fat Diet ◽  
Chow Diet ◽  
High Fat ◽  
Normal Chow ◽  
Visceral Adipose ◽  
Deficient Mice ◽  
Normal Chow Diet

Although corroborating data indicate that estrogens influence glucose metabolism through the activation of the estrogen receptor α (ERα), it has not been established whether this pathway could represent an effective therapeutic target to fight against metabolic disturbances induced by a high-fat diet (HFD). To this end, we first evaluated the influence of chronic 17β-estradiol (E2) administration in wild-type ovariectomized mice submitted to either a normal chow diet or a HFD. Whereas only a modest effect was observed in normal chow diet-fed mice, E2 administration exerted a protective effect against HFD-induced glucose intolerance, and this beneficial action was abolished in ERα-deficient mice. Furthermore, E2 treatment reduced HFD-induced insulin resistance by 50% during hyperinsulinemic euglycemic clamp studies and improved insulin signaling (Akt phosphorylation) in insulin-stimulated skeletal muscles. Unexpectedly, we found that E2 treatment enhanced cytokine (IL-6, TNF-α) and plasminogen activator inhibitor-1 mRNA expression induced by HFD in the liver and visceral adipose tissue. Interestingly, although the proinflammatory effect of E2 was abolished in visceral adipose tissue from chimeric mice grafted with bone marrow cells from ERα-deficient mice, the beneficial effect of the hormone on glucose tolerance was not altered, suggesting that the metabolic and inflammatory effects of estrogens can be dissociated. Eventually comparison of sham-operated with ovariectomized HFD-fed mice demonstrated that endogenous estrogens levels are sufficient to exert a full protective effect against insulin resistance and glucose intolerance. In conclusion, the regulation of the ERα pathway could represent an effective strategy to reduce the impact of high-fat diet-induced type 2 diabetes.

scholarly journals Betaine improved adipose tissue function in mice fed a high-fat diet: a mechanism for hepatoprotective effect of betaine in nonalcoholic fatty liver disease

2010 ◽  
Vol 298 (5) ◽  
pp. G634-G642 ◽  
Author(s):  
Zhigang Wang ◽  
Tong Yao ◽  
Maria Pini ◽  
Zhanxiang Zhou ◽  
Giamila Fantuzzi ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Liver Disease ◽  
Fatty Liver ◽  
High Fat Diet ◽  
Fatty Liver Disease ◽  
Control Diet ◽  
High Fat ◽  
Nonalcoholic Fatty Liver ◽  
Betaine Supplementation

Adipose tissue dysfunction, featured by insulin resistance and/or dysregulated adipokine production, plays a central role not only in disease initiation but also in the progression to nonalcoholic steatohepatitis and cirrhosis. Promising beneficial effects of betaine supplementation on nonalcoholic fatty liver disease (NAFLD) have been reported in both clinical investigations and experimental studies; however, data related to betaine therapy in NAFLD are still limited. In this study, we examined the effects of betaine supplementation on hepatic fat accumulation and injury in mice fed a high-fat diet and evaluated mechanisms underlying its hepatoprotective effects. Male C57BL/6 mice weighing 25 ± 0.5 (SE) g were divided into four groups (8 mice/group) and started on one of four treatments: control diet, control diet supplemented with betaine, high-fat diet, and high-fat diet supplemented with betaine. Betaine was supplemented in the drinking water at a concentration of 1% (wt/vol) (anhydrous). Our results showed that long-term high-fat feeding caused NAFLD in mice, which was manifested by excessive neutral fat accumulation in the liver and elevated plasma alanine aminotransferase levels. Betaine supplementation alleviated hepatic pathological changes, which were concomitant with attenuated insulin resistance as shown by improved homeostasis model assessment of basal insulin resistance values and glucose tolerance test, and corrected abnormal adipokine (adiponectin, resistin, and leptin) productions. Specifically, betaine supplementation enhanced insulin sensitivity in adipose tissue as shown by improved extracellular signal-regulated kinases 1/2 and protein kinase B activations. In adipocytes freshly isolated from mice fed a high-fat diet, pretreatment of betaine enhanced the insulin signaling pathway and improved adipokine productions. Further investigation using whole liver tissues revealed that betaine supplementation alleviated the high-fat diet-induced endoplasmic reticulum stress response in adipose tissue as shown by attenuated glucose-regulated protein 78/C/EBP homologous protein (CHOP) protein abundance and c-Jun NH2-terminal kinase activation. Our findings suggest that betaine might serve as a safe and efficacious therapeutic tool for NAFLD by improving adipose tissue function.

scholarly journals Osteocalcin Protects Against Nonalcoholic Steatohepatitis in a Mouse Model of Metabolic Syndrome

Endocrinology ◽  
2014 ◽  
Vol 155 (12) ◽  
pp. 4697-4705 ◽  
Author(s):  
Anisha A. Gupte ◽  
Omaima M. Sabek ◽  
Daniel Fraga ◽  
Laurie J. Minze ◽  
Satoru K. Nishimoto ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Liver Disease ◽  
Nonalcoholic Steatohepatitis ◽  
Fatty Liver Disease ◽  
High Cholesterol Diet ◽  
Cholesterol Diet ◽  
High Cholesterol ◽  
High Fat ◽  
Nonalcoholic Fatty Liver

Nonalcoholic fatty liver disease, particularly its more aggressive form, nonalcoholic steatohepatitis (NASH), is associated with hepatic insulin resistance. Osteocalcin, a protein secreted by osteoblast cells in bone, has recently emerged as an important metabolic regulator with insulin-sensitizing properties. In humans, osteocalcin levels are inversely associated with liver disease. We thus hypothesized that osteocalcin may attenuate NASH and examined the effects of osteocalcin treatment in middle-aged (12-mo-old) male Ldlr−/− mice, which were fed a Western-style high-fat, high-cholesterol diet for 12 weeks to induce metabolic syndrome and NASH. Mice were treated with osteocalcin (4.5 ng/h) or vehicle for the diet duration. Osteocalcin treatment not only protected against Western-style high-fat, high-cholesterol diet-induced insulin resistance but substantially reduced multiple NASH components, including steatosis, ballooning degeneration, and fibrosis, with an overall reduction in nonalcoholic fatty liver disease activity scores. Further, osteocalcin robustly reduced expression of proinflammatory and profibrotic genes (Cd68, Mcp1, Spp1, and Col1a2) in liver and suppressed inflammatory gene expression in white adipose tissue. In conclusion, these results suggest osteocalcin inhibits NASH development by targeting inflammatory and fibrotic processes.

scholarly journals Plasma adiponectin is decreased in nonalcoholic fatty liver disease

2005 ◽  
Vol 152 (1) ◽  
pp. 113-118 ◽  
Author(s):  
Claudio Pagano ◽  
Giorgio Soardo ◽  
Walter Esposito ◽  
Francesco Fallo ◽  
Lorenza Basan ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Adipose Tissue ◽  
Liver Disease ◽  
Fatty Liver ◽  
Nonalcoholic Fatty Liver Disease ◽  
Fatty Liver Disease ◽  
Nonalcoholic Fatty Liver ◽  
Plasma Adiponectin ◽  
Simple Steatosis

Objectives: Nonalcoholic fatty liver disease (NAFLD) is a major cause of liver-related morbidity and is frequently associated with obesity and metabolic syndrome. The recently discovered hormone adiponectin is produced by adipose tissue, and low plasma adiponectin is considered a key factor in the development of the insulin resistance underlying metabolic syndrome. Animal studies suggest that adiponectin may protect against non-alcoholic steatohepatitis, but direct evidence in humans is lacking. We therefore conducted this study to assess the relationship between plasma adiponectin and nonalcoholic fatty liver disease to explore its role in the pathogenesis of this disease. Design and methods: We measured plasma adiponectin and anthropometric, biochemical, hormonal and metabolic correlates in a group of 17 NAFLD patients with diagnosis confirmed by biopsy, and 20 controls with comparable age, body-mass index and sex. Furthermore we compared plasma adiponectin in patients with simple steatosis and steatohepatitis. Results: Plasma adiponectin was significantly lower in NAFLD patients than controls (5.93±0.45 vs 15.67±1.60 ng/ml). Moreover, NAFLD patients were significantly more insulin resistant while having similar serum leptin. Adiponectin was similar in simple steatosis and in steatohepatitis (6.16±0.78 vs 5.69±0.49 ng/ml). An inverse correlation was observed between adiponectin and homeostatic model assessment (HOMA) of insulin resistance (P = 0.008), while adiponectin did not correlate with serum transaminases and lipid values. Conclusions: These data support a role for low circulating adiponectin in the pathogenesis of NAFLD and confirm the strict association between reduced adiponectin production by adipose tissue, NAFLD and insulin resistance.

Irisin induces white adipose tissue browning in mice as assessed by magnetic resonance imaging

2021 ◽  
pp. 153537022110060
Author(s):  
Yue Chen ◽  
Jie Ding ◽  
Yufei Zhao ◽  
Shenghong Ju ◽  
Hui Mao ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Adipose Tissue ◽  
Magnetic Resonance ◽  
White Adipose Tissue ◽  
High Fat Diet ◽  
Chow Diet ◽  
Resonance Imaging ◽  
High Fat ◽  
White Adipocytes ◽  
Fat Fraction

This study aimed to track and evaluate the effect of low-dose irisin on the browning of white adipose tissue (WAT) in mice using magnetic resonance imaging (MRI) noninvasively in vivo. Mature white adipocytes extracted from mice were cultured, induced and characterized before being treated by irisin. The volume and fat fraction of WAT were quantified using MRI in normal chow diet and high fat mice after injection of irisin. The browning of cultured white adipocytes and WAT in mice were validated by immunohistochemistry and western blotting for uncoupling protein 1 (UCP1) and deiodinase type II (DIO2). The serum indexes were examined with high fat diet after irisin intervention. UCP1 and DIO2 in adipocytes showed increases responding to the irisin treatment. The size of white adipocytes in mice receiving irisin intervention was reduced. MRI measured volumes and fat fraction of WAT were significantly lower after Irisin treatment. Blood glucose and cholesterol levels were reduced in high fat diet mice after irisin treatment. Irisin intervention exerted browning of WAT, resulting reduction of volume and fat fraction of WAT as measured by MRI. Furthermore, it improved the condition of mice with diet-induced obesity and related metabolic disorders.

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