The High-Fat Diet-Fed Mouse: A Model for Studying Mechanisms and Treatment of Impaired Glucose Tolerance and Type 2 Diabetes

Recent studies suggest that a circulating protein called TRAIL (TNF-related apoptosis inducing ligand) may have an important role in the treatment of type 2 diabetes. It has been shown that TRAIL deficiency worsens diabetes and that TRAIL delivery, when it is given before disease onset, slows down its development. The present study aimed at evaluating whether TRAIL had the potential not only to prevent, but also to treat type 2 diabetes. Thirty male C57BL/6J mice were randomized to a standard or a high-fat diet (HFD). After 4 weeks of HFD, mice were further randomized to receive either placebo or TRAIL, which was delivered weekly for 8 weeks. Body weight, food intake, fasting glucose, and insulin were measured at baseline and every 4 weeks. Tolerance tests were performed before drug randomization and at the end of the study. Tissues were collected for further analyses. Parallel in vitro studies were conducted on HepG2 cells and mouse primary hepatocytes. TRAIL significantly reduced body weight, adipocyte hypertrophy, free fatty acid levels, and inflammation. Moreover, it significantly improved impaired glucose tolerance, and ameliorated non-alcoholic fatty liver disease (NAFLD). TRAIL treatment reduced liver fat content by 47% in vivo as well as by 45% in HepG2 cells and by 39% in primary hepatocytes. This was associated with a significant increase in liver peroxisome proliferator-activated receptor (PPAR) γ (PPARγ) co-activator-1 α (PGC-1α) expression both in vivo and in vitro, pointing to a direct protective effect of TRAIL on the liver. The present study confirms the ability of TRAIL to significantly attenuate diet-induced metabolic abnormalities, and it shows for the first time that TRAIL is effective also when administered after disease onset. In addition, our data shed light on TRAIL therapeutic potential not only against impaired glucose tolerance, but also against NAFLD.

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Polyphenol-Rich Fraction of Brown AlgaEcklonia cavaCollected from Gijang, Korea, Reduces Obesity and Glucose Levels in High-Fat Diet-Induced Obese Mice

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2012/418912 ◽

2012 ◽

Vol 2012 ◽

pp. 1-11 ◽

Cited By ~ 15

Author(s):

Eun Young Park ◽

Eung Hwi Kim ◽

Mi Hwi Kim ◽

Young Wan Seo ◽

Jung Im Lee ◽

...

Keyword(s):

Type 2 Diabetes ◽

Body Weight ◽

Glucose Tolerance ◽

Mrna Expression ◽

Inflammatory Cytokines ◽

High Fat Diet ◽

Obese Mice ◽

High Fat ◽

Glucose Levels

Ecklonia cava (E. cava)is a brown alga that has beneficial effects in models of type 1 and type 2 diabetes. However, the effects ofE. cavaextracts on diet-induced obesity and type 2 diabetes have not been specifically examined. We investigated the effects ofE. cavaon body weight, fat content, and hyperglycemia in high-fat diet- (HFD) induced obese mice and sought the mechanisms involved. C57BL/6 male mice were fed a HFD (60% fat) diet or normal chow. After 3 weeks, the HFD diet group was given extracts (200 mg/kg) ofE. cavaharvested from Jeju (CA) or Gijang (G-CA), Korea or PBS by oral intubation for 8 weeks. Body weights were measured weekly. Blood glucose and glucose tolerance were measured at 7 weeks, and fat pad content and mRNA expression of adipogenic genes and inflammatory cytokines were measured after 8 weeks of treatment. G-CA was effective in reducing body weight gain, body fat, and hyperglycemia and improving glucose tolerance as compared with PBS-HFD mice. The mRNA expression of adipogenic genes was increased, and mRNA expression of inflammatory cytokines and macrophage marker gene was decreased in G-CA-treated obese mice. We suggest that G-CA reduces obesity and glucose levels by anti-inflammatory actions and improvement of lipid metabolism.

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Baicalein Protects against Type 2 Diabetes via Promoting Isletβ-Cell Function in Obese Diabetic Mice

International Journal of Endocrinology ◽

10.1155/2014/846742 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 26

Author(s):

Yu Fu ◽

Jing Luo ◽

Zhenquan Jia ◽

Wei Zhen ◽

Kequan Zhou ◽

...

Keyword(s):

Type 2 Diabetes ◽

Insulin Secretion ◽

Glucose Tolerance ◽

High Fat Diet ◽

Cell Function ◽

Diabetic Mice ◽

Obese Mice ◽

High Fat ◽

Middle Aged

In both type 1 (T1D) and type 2 diabetes (T2D), the deterioration of glycemic control over time is primarily caused by an inadequate mass and progressive dysfunction ofβ-cell, leading to the impaired insulin secretion. Here, we show that dietary supplementation of baicalein, a flavone isolated from the roots of Chinese herbScutellaria baicalensis, improved glucose tolerance and enhanced glucose-stimulated insulin secretion (GSIS) in high-fat diet (HFD-) induced middle-aged obese mice. Baicalein had no effect on food intake, body weight gain, circulating lipid profile, and insulin sensitivity in obese mice. Using another mouse model of type 2 diabetes generated by high-fat diet (HFD) feeding and low doses of streptozotocin injection, we found that baicalein treatment significantly improved hyperglycemia, glucose tolerance, and blood insulin levels in these middle-aged obese diabetic mice, which are associated with the improved isletβ-cell survival and mass. In thein vitrostudies, baicalein significantly augmented GSIS and promoted viability of insulin-secreting cells and human islets cultured either in the basal medium or under chronic hyperlipidemic condition. These results demonstrate that baicalein may be a naturally occurring antidiabetic agent by directly modulating pancreaticβ-cell function.

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Novel canine models of obese prediabetes and mild type 2 diabetes

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00466.2009 ◽

2010 ◽

Vol 298 (1) ◽

pp. E38-E48 ◽

Cited By ~ 30

Author(s):

Viorica Ionut ◽

Huiwen Liu ◽

Vahe Mooradian ◽

Ana Valeria B. Castro ◽

Morvarid Kabir ◽

...

Keyword(s):

Insulin Resistance ◽

Type 2 Diabetes ◽

Glucose Tolerance ◽

Impaired Glucose Tolerance ◽

Low Dose ◽

Cell Function ◽

High Fat ◽

Β Cell ◽

Β Cell Function

Human type 2 diabetes mellitus (T2DM) is often characterized by obesity-associated insulin resistance (IR) and β-cell function deficiency. Development of relevant large animal models to study T2DM is important and timely, because most existing models have dramatic reductions in pancreatic function and no associated obesity and IR, features that resemble more T1DM than T2DM. Our goal was to create a canine model of T2DM in which obesity-associated IR occurs first, followed by moderate reduction in β-cell function, leading to mild diabetes or impaired glucose tolerance. Lean dogs ( n = 12) received a high-fat diet that increased visceral (52%, P < 0.001) and subcutaneous (130%, P < 0.001) fat and resulted in a 31% reduction in insulin sensitivity (SI) (5.8 ± 0.7 × 10−4 to 4.1 ± 0.5 × 10−4 μU·ml−1·min−1, P < 0.05). Animals then received a single low dose of streptozotocin (STZ; range 30–15 mg/kg). The decrease in β-cell function was dose dependent and resulted in three diabetes models: 1) frank hyperglycemia (high STZ dose); 2) mild T2DM with normal or impaired fasting glucose (FG), 2-h glucose >200 mg/dl during OGTT and 77–93% AIRg reduction (intermediate dose); and 3) prediabetes with normal FG, normal 2-h glucose during OGTT and 17–74% AIRg reduction (low dose). Twelve weeks after STZ, animals without frank diabetes had 58% more body fat, decreased β-cell function (17–93%), and 40% lower SI. We conclude that high-fat feeding and variable-dose STZ in dog result in stable models of obesity, insulin resistance, and 1) overt diabetes, 2) mild T2DM, or 3) impaired glucose tolerance. These models open new avenues for studying the mechanism of compensatory changes that occur in T2DM and for evaluating new therapeutic strategies to prevent progression or to treat overt diabetes.

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