Development Of Obesity In Mice Research Articles

Skeletal muscle HSF1 prevents insulin resistance by improving glucose utilization.

The regulation of muscle glucose utilization has significant potential for the treatment of type 2 diabetes mellitus (T2DM) and obesity. Heat shock factor 1 (HSF1) is involved in cellular metabolism and regulation of muscle metabolism. However, it is unclear how HSF1 regulates muscle glucose metabolism. In the present study, the development of obesity in mice was associated with HSF1 downregulation. Serum samples and muscle biopsies were obtained from obese and healthy humans. Fasting glucose and insulin levels and the homeostasis model assessment of insulin resistance value showed that obesity was associated with insulin resistance. The skeletal muscle level of HSF1 was decreased in obese and ob/ob mice. HSF1 was selectively over-expressed in the skeletal muscles of high fat diet (HFD)-fed mice. Muscle HSF1 over-expression successfully triggered glycolytic-to-oxidative myofiber switch and increased fatty acid metabolism and insulin sensitivity in the skeletal muscles of HFD-fed mice. Moreover, HSF1 improved energy expenditure and blocked muscle accumulation of triglycerides in HFD-fed mice. Consequently, muscle HSF1 mitigated the impaired muscle insulin signaling and insulin resistance in HFD-fed mice. In conclusion, T2DM and obesity in HFD-fed mice may be treated with selective HSF1-directed programming of exercise-like effects in skeletal muscle. These findings may aid the development of a new therapeutic approach for obesity and T2DM.

Oligosaccharide and short-chain fatty acid: A double-edged sword in obese mice by regulating food intake and fat synthesis

Dietary fiber has been used to prevent obesity by regulating the intestinal flora and promoting the production of short-chain fatty acids (SCFAs). However, it is insufficient to conclude the decisive role of microbiota and SCFAs by adding oligosaccharides to foods without caloric balance. In this study, the effects of oligosaccharides and their regulated microflora on the development of obesity in mice were studied by designing a high-fat diet with equal calories but different contents of oligosaccharides. Isocaloric diets demonstrated that appropriate rather than excess oligosaccharides prevent obesity by regulating appetite. Such an appetite was inhibited by oligosaccharides but promoted by SCFAs. Furthermore, promoted appetite was tightly related to decreased insulin and increased acyl-CoA binding protein, which was correlated with SCFA-induced fat degradation. Interestingly, drinking butyrate alleviated obesity even with higher calorie intake. Molecular docking demonstrated that conversion of butyrate to butyryl-CoA converted from butyrate, as a structural analog of acetyl-CoA, inhibits the activity of acetyl-CoA carboxylase. Together, these findings demonstrate that fermentable fiber supplements may have limits in obesity treatment, and we provide possible obesity therapeutic targets that inhibit bacterial fermentation or increase the ratio of butyrate/acetate.

Bifidobacterium animalis subsp. lactis A6 Enhances Fatty Acid β-Oxidation of Adipose Tissue to Ameliorate the Development of Obesity in Mice.

Fatty acid β-oxidation (FAO) is confirmed to be impaired in obesity, especially in adipose tissues. We previously proved that Bifidobacterium animalis subsp. lactis A6 (BAA6) had protective effects against diet-induced obesity. However, whether BAA6 enhances FAO to ameliorate the development of obesity has not been explored. After being fed with high-fat diet (HFD) for 9 weeks, male C57BL/6J mice were fed HFD or BAA6 for 8 weeks. In vitro study was carried out using 3T3-L1 adipocytes to determine the effect of BAA6 culture supernatant (BAA6-CM). Here, we showed that administration of BAA6 to mice fed with HFD decreased body weight gain (by 5.03 g) and significantly up-regulated FAO in epididymal adipose tissues. In parallel, FAO in 3T3-L1 cells was increased after BAA6-CM treatment. Acetate was identified as a constituent of BAA6-CM that showed a similar effect to BAA6-CM. Furthermore, acetate treatment activated the GPR43-PPARα signaling, thereby promoting FAO in 3T3-L1 cells. The levels of acetate were also elevated in serum and feces (by 1.92- and 2.27-fold) of HFD-fed mice following BAA6 administration. The expression levels of GPR43 and PPARα were increased by 55.45% and 69.84% after BAA6 supplement in the epididymal fat of mice. Together, these data reveal that BAA6 promotes FAO of adipose tissues through the GPR43-PPARα signaling, mainly by increasing acetate levels, leading to alleviating the development of obesity.

Impact of Interplay between Obese Gut Microbiota and Diet in Developing Obesity in Synthetic Community Mice.

This study aims at investigating the effects of cultured gut microbiota (GM) of obese human coupled high fat diet (HFD) or chow diet (CD) in development of obesity in mice. 20 stool samples were collected from obese patients and isolated bacteria were identified morphologically and biochemically. Identified isolates were mixed in equal proportions to synthesize obese GM. In vivo study was performed using obese GM combined with HFD/CD using mouse model for three months. Albino mice were treated with ampicillin from one week prior to birth until weaning of the pups at seven weeks of age and then inoculated with obese GM. Sixteen mice were divided into four groups: i.e. group 1 (G1) mice fed with CD, group 2 (G2) mice with HFD, group 3 (G3) mice with GM + HFD and group 4 (G4) mice with GM + CD. Mice from groups 3-4 were considered synthetic community (SC) mice due to transfer of synthesize human GM. 16S rRNA sequencing identified five abundant bacteria as Pseudomonas aeruginosa, Staphylococcus sp., Escherichia coli, Morganella morganii, and Klebsiella oxytoca (accession numbers: MZ150742-MZ150746). In vivo study indicated that GM combination with either HFD/CD caused significantly increased body weight in SC mice (BMI; Kg/m2) compared to HFD or CD fed mice groups. One way ANOVA revealed highly significant increase (p ≤ 0.001) in levels of total cholesterol (TC), triglycerides and low density lipoprotein (LDL) in GM coupled diet groups (G3-G4; SC mice) compared to significant increase in HFD group (G2) versus CD group (G1). Our study is first of its kind to report significant effects of using purified strains as obese GM plus diet (HFD/CD) in inducing obesity in SC mice and elevated serum liver parameters as metabolic indicators, hence providing strong evidence about significance of modified GM combination with HFD in developing obesity in SC mice.

73-OR: Gut–Brain Signals That Regulate Hunger

Body weight is regulated by interoceptive neural circuits that track energy need, but how the activity of these circuits is altered in obesity remains poorly understood. Here we describe the in vivo dynamics of hunger-promoting AgRP neurons during the development of diet-induced obesity in mice. We show that high-fat diet attenuates the response of AgRP neurons to an array of stimuli including food cues, intragastric nutrients, and the hormones cholecystokinin and ghrelin. These alterations are nutrient-specific, with AgRP neurons becoming desensitized to dietary fat but not carbohydrate or protein. Subsequent weight loss restores the responsiveness of AgRP neurons to exterosensory cues but fails to rescue their sensitivity to gastrointestinal hormones or nutrients. These findings reveal that obesity triggers broad dysregulation of hypothalamic hunger neurons that is incompletely reversed by weight loss and may contribute to the difficulty of maintaining a reduced weight. Disclosure Z. Knight: None. Funding American Diabetes Association/Pathway to Stop Diabetes (1-16-ACE-29)

Chinese olive (Canarium album L.) fruit regulates glucose utilization by activating AMP-activated protein kinase.

A growing body of evidence demonstrates obesity-induced insulin resistance is associated with the development of metabolic diseases. This study was designed to investigate ethyl acetate fraction of Chinese olive fruit extract (CO-EtOAc)-mediated attenuation of obesity and hyperglycemia in a mouse model. About 60% HFD-fed mice were treated intragastrically with CO-EtOAc for last 6weeks, and body weight, blood biochemical parameters as well as hepatic inflammation response were investigated. Our results showed that CO-EtOAc treatment significantly reduced the formation of hepatic lipid droplets, body weight gain, blood glucose, and improved serum biochemical parameters in HFD-induced obese and insulin resistant mice. We further explored the molecular mechanism underlying the blood glucose modulating effect of CO-EtOAc using L6 myotubes model. We conclude that CO-EtOAc effectively increases the glycogen content and glucose uptake by stimulating the membrane translocation of glucose transporter 4. In addition, CO-EtOAc depolarizes the mitochondrial membrane and decreases the mitochondrial oxygen consumption, which may result in AMPK activation and the consequent mitochondrial fission. This study shows that CO-EtOAc prevents the development of obesity in mice fed with HFD and is also capable of stimulating glucose uptake. The possible mechanism might be due to the effects of CO-EtOAc on activation of AMPK and promotion of mitochondrial fission.

High-fat diet leads to increased ovarian lipid deposition even in the absence of obesity

We have previously shown that high-fat diet (HFD) feeding leads to depletion of the ovarian reserve, subfertility, and altered expression of key ovarian genes, irrespective of the development of obesity1,2. It has been proposed that HFD-induced ovarian dysfunction is due to increased lipid accumulation in the ovary3,4, however, it is currently unknown if there is increased HFD-induced lipid accumulation in the ovary in the absence of obesity. We hypothesized that HFD exposure would increase ovarian lipid deposition regardless of the induction of obesity. Prospective laboratory animal study. 5-week-old C57BL/6J mice were fed either a 60% HFD or standard chow (N = 15) for 10 weeks. After 10 weeks body weights were determined. Lean and fat mass was measured by quantitative MRI. HFD mice were divided into HFD-lean (HFLn, N=10) and HFD-obese (HFOb, N=9) groups based on body weight: mice < 26 g were considered HFLn and mice ³ 30 g were considered HFOb. Ovaries were collected, one for qRT-PCR analysis of the lipid droplet protein plin2 and the other for immunohistochemical analysis of lipid droplets via anti-plin2 staining. A one-way ANOVA (Tukey’s post hoc) was used for statistical analysis. After 10 weeks of diet HFOb mice weighed more and had a higher percentage of body fat (33.2 ± 0.9 g, 37.2 ± 1.2%, respectively) than both HFLn mice (23.5 ± 0.6g, 17.7 ± 1.5%, respectively) and chow controls (21.6 ± 0.3g, 11.2 ± 0.6%, respectively) (p<0.0001). Ovarian expression of plin2 was dramatically increased after HFD, with a 5-fold increase observed in HFLn mice and a 4.7-fold increase observed in HFOb mice (p = 0.01) compared to chow-fed controls. Immunohistochemical analysis of plin2 in the ovary confirmed our qRT-PCR data showing dramatically increased levels of plin2 in the ovaries of both the HFLn and HFOb mice. In particular, increased lipid deposition was observed in the corpora lutea, ovarian stroma, and outside of the theca cells of large follicles, and to a far lesser extent in the granulosa cells. HFD exposure leads to increased ovarian lipid deposition regardless of the development of obesity in mice. This phenomenon may be responsible for the ovarian dysfunction and reproductive defects observed with HFD exposure, even in the absence of obesity. The presence of increased lipid droplets in the ovaries of lean mice fed a HFD provides further evidence that even if a lean phenotype is maintained, consumption of HFDs will still negatively impact the ovary. More research is needed to determine the exact mechanism by which excessive ovarian lipid accumulation is responsible for the HFD-induced reproductive dysfunction.

Significant Associations Between Sun Exposure and Adiposity Were Not Observed in Breast and Prostate Cancer Patients in a Cross-sectional Analysis.

Obesity is a significant health problem worldwide. Exposure to low-dose ultraviolet radiation (like that in sunlight) suppresses the development of obesity in mice; however, the nature of the associations between sun exposure and adiposity is not well understood in humans. The present study characterized cross-sectional relationships between sun exposure and adiposity in a convenience cohort of breast (n=269; mean age=58years) and prostate (n=78; mean age=69years) cancer patients. Participants were enrolled in a 3-month exercise program in Perth, Australia. Self-reported questionnaires measured time spent outdoors (previous week, winter and summer), sex, age, treatment received and physical activity levels. Adiposity measures included body mass index, waist-hip ratio and body fat percentage (measured via DXA). In unadjusted models, greater time spent outdoors across all times was significantly associated with lower waist-hip ratio, while greater time spent outdoors in the last winter was associated with lower body fat percentage, but not when stratified by sex. There were no statistically significant associations between time spent outdoors and adiposity after adjusting for sex, age, treatments received and physical activity. Longitudinal studies in larger populations may elucidate significant associations not found in our study due to the cross-sectional design and power limitations.

YIPF6 controls sorting of FGF21 into COPII vesicles and promotes obesity

Fibroblast growth factor 21 (FGF21) is an endocrine hormone that regulates glucose, lipid, and energy homeostasis. While gene expression of FGF21 is regulated by the nuclear hormone receptor peroxisome proliferator-activated receptor alpha in the fasted state, little is known about the regulation of trafficking and secretion of FGF21. We show that mice with a mutation in the Yip1 domain family, member 6 gene (Klein-Zschocher [KLZ]; Yipf6KLZ/Y ) on a high-fat diet (HFD) have higher plasma levels of FGF21 than mice that do not carry this mutation (controls) and hepatocytes from Yipf6KLZ/Y mice secrete more FGF21 than hepatocytes from wild-type mice. Consequently, Yipf6KLZ/Y mice are resistant to HFD-induced features of the metabolic syndrome and have increased lipolysis, energy expenditure, and thermogenesis, with an increase in core body temperature. Yipf6KLZ/Y mice with hepatocyte-specific deletion of FGF21 were no longer protected from diet-induced obesity. We show that YIPF6 binds FGF21 in the endoplasmic reticulum to limit its secretion and specifies packaging of FGF21 into coat protein complex II (COPII) vesicles during development of obesity in mice. Levels of YIPF6 protein in human liver correlate with hepatic steatosis and correlate inversely with levels of FGF21 in serum from patients with nonalcoholic fatty liver disease (NAFLD). YIPF6 is therefore a newly identified regulator of FGF21 secretion during development of obesity and could be a target for treatment of obesity and NAFLD.

Feedback regulation of Arid5a and Ppar-γ2 maintains adipose tissue homeostasis

Immune cells infiltrate adipose tissues and provide a framework to regulate energy homeostasis. However, the precise underlying mechanisms and signaling by which the immune system regulates energy homeostasis in metabolic tissues remain poorly understood. Here, we show that the AT-rich interactive domain 5A (Arid5a), a cytokine-induced nucleic acid binding protein, is important for the maintenance of adipose tissue homeostasis. Long-term deficiency of Arid5a in mice results in adult-onset severe obesity. In contrast, transgenic mice overexpressing Arid5a are highly resistant to high-fat diet-induced obesity. Inhibition of Arid5a facilitates the in vitro differentiation of 3T3-L1 cells and fibroblasts to adipocytes, whereas its induction substantially inhibits their differentiation. Molecular studies reveal that Arid5a represses the transcription of peroxisome proliferator activated receptor gamma 2 (Ppar-γ2) due to which, in the absence of Arid5a, Ppar-γ2 is persistently expressed in fibroblasts. This phenomenon is accompanied by enhanced fatty acid uptake in Arid5a-deficient cells, which shifts metabolic homeostasis toward prolipid metabolism. Furthermore, we show that Arid5a and Ppar-γ2 are dynamically counterregulated by each other, hence maintaining adipogenic homeostasis. Thus, we show that Arid5a is an important negative regulator of energy metabolism and can be a potential target for metabolic disorders.

Decrement in resting and insulin-stimulated soleus muscle mitochondrial respiration is an early event in diet-induced obesity in mice.

What is the central question of this study? What are the temporal responses of mitochondrial respiration and mitochondrial responsivity to insulin in soleus muscle fibres from mice during the development of obesity and insulin resistance? What is the main finding and its importance? Short- and long-term feeding with a high-fat diet markedly reduced soleus mitochondrial respiration and mitochondrial responsivity to insulin before any change in glycogen synthesis. Muscle glycogen synthesis and whole-body insulin resistance were present after 14 and 28 days, respectively. Our findings highlight the plasticity of mitochondria during the development of obesity and insulin resistance. Recently, significant attention has been given to the role of muscle mitochondrial function in the development of insulin resistance associated with obesity. Our aim was to investigate temporal alterations in mitochondrial respiration, H2 O2 emission and mitochondrial responsivity to insulin in permeabilized skeletal muscle fibres during the development of obesity in mice. Male Swiss mice (5-6weeks old) were fed with a high-fat diet (60% calories from fat) or standard diet for 7, 14 or 28 days to induce obesity and insulin resistance. Diet-induced obese (DIO) mice presented with reduced glucose tolerance and hyperinsulinaemia after 7days of high-fat diet. After 14days, the expected increase in muscle glycogen content after systemic injection of glucose and insulin was not observed in DIO mice. At 28days, blood glucose decay after insulin injection was significantly impaired. ComplexI (pyruvate+malate) and II (succinate)-linked respiration and oxidative phosphorylation (ADP) were decreased after 7 days of high-fat diet and remained low in DIO mice after 14 and 28 days of treatment. Moreover, mitochondria from DIO mice were incapable of increasing respiratory coupling and ADP responsivity after insulin stimulation in all observed periods. Markers of mitochondrial content were reduced only after 28days of treatment. The mitochondrial H2 O2 emission profile varied during the time course of DIO, with a reduction of H2 O2 emission in the early stages of DIO and an increased emission after 28 days of treatment. Our data demonstrate that DIO promotes transitory alterations in mitochondrial physiology during the early and late stages of insulin resistance related to obesity.

Chinese Olive ( &lt;i&gt;Canarium album L.&lt;/i&gt;) Fruit Regulates Glucose Utilization by Activating Amp-Activated Protein Kinase

Background: A growing body of evidence demonstrates obesity-induced insulin resistance is considered to promote the development of metabolic diseases. This study was designed to investigate ethyl acetate fraction of Chinese olive fruit extract (CO-EtOAc) mediated attenuation of obesity and hyperglycemia in a mouse model. Methods: 60% of HFD-fed mice were treated intragastrically with CO-EtOAc for at last six weeks, and body weight, blood biochemical parameters as well as hepatic inflammation response were investigated. On the other hands, we also investigated the molecular mechanism involved in glucose homeostasis and cellular energy balance using L6 myotubes. Findings: Our results showed that CO-EtOAc treatment significantly reduced the formation of hepatic lipid droplets, body weight gain, blood glucose and improved serum biochemical parameters in HFD induced obese and insulin resistant mice. We further explored the molecular mechanism underlying the blood glucose modulating the effect of CO-EtOAc using L6 myotubes model. We concluded that CO-EtOAc effectively increased glycogen content and glucose uptake by stimulating the membrane translocation of glucose transporter 4. In addition, CO-EtOAc depolarized the mitochondrial membrane potential and decreased mitochondrial oxygen consumption, which may result in AMPK activation and the consequent mitochondrial fission. Interpretation: This study shows that CO-EtOAc prevents the development of obesity in mice fed with HFD and is also capable of stimulating glucose uptake. The possible mechanism might be due to the effects of CO-EtOAc on activation of AMPK and promotion of mitochondrial fission. Funding: This work was supported by grants 36 from the Ministry of Science and Technology (MOST 104‐3011‐B‐010‐001‐1‐4‐2, MOST 104‐2320‐B‐002‐039), Taiwan. Declaration of Interest: The authors declare no competing financial interests. Ethical Approval: All study protocols were approved by the Institutional Animal Care and Use Committee of National Yang-Ming University. In addition, all experiments were performed in accordance with relevant guidelines and regulations.

Disruption of Epithelial HDAC3 in Intestine Prevents Diet-Induced Obesity in Mice

Intestinal microbiota modulate metabolism and associate closely with epithelial cells in the intestine. In intestinal epithelial cells (IECs), histone deacetylase 3 (HDAC3) integrates microbiota-derived signals to control intestinal homeostasis. We investigated whether HDAC3 in IECs regulates metabolism and the development of obesity in mice. Adult C57BL/6 (control) mice and mice with constitutive or inducible IEC-specific disruption of Hdac3 (HDAC3ΔIEC mice) were placed on a standard chow or high-fat diet (HFD, 60% kcal from fat). We measured body composition, weight, glucose tolerance, and energy expenditure. IECs were isolated from small intestine and gene expression, and lipid levels were analyzed. HDAC3 levels were determined in 43 pediatric patient ileal biopsy samples and compared with body weight. Control mice fed an HFD gained weight, became obese, and had reduced glucose tolerance with increased serum insulin, whereas HFD-fed HDAC3ΔIEC mice did not develop obesity. Serum levels of triglycerides were reduced in HDAC3ΔIEC mice, and these mice had less liver fat and smaller adipocytes, compared with HFD-fed control mice. HDAC3ΔIEC mice had similar food intake and activity as control mice, but higher energy expenditure because of increased catabolism. IECs from HDAC3ΔIEC mice had altered expression levels of genes that regulate metabolism in response to the microbiota (such as Chka, Mttp, Apoa1, and Pck1) and accumulated triglycerides compared with IECs from control mice. The microbiota-derived short-chain fatty acid butyrate was decreased in obese mice. Butyrate significantly reduced the activity of HDAC3 and increased Pck1 expression in only control IECs. Administration of butyrate to control mice with diet-induced obesity, but not HDAC3ΔIEC mice, led to significant weight loss. Disruption of HDAC3 in IECs of mice after they became obese led to weight loss and improved metabolic profile. Levels of HDAC3 in intestinal biopsy samples correlated with patient weight. We found that epithelial HDAC3 promotes development of diet-induced obesity in studies of mice and that butyrate reduces activity of HDAC3 in IECs to prevent diet-induced obesity. This pathway might be manipulated to prevent or reduce obesity-associated disease.

Abstract P203: pNaktide Targeted to Adipocytes Inhibits Na/k-atpase Reactive Oxygen Species, Systemic Inflammation, and Obesity Development in Mice Fed a Western Diet (WD)

Introduction: Obesity is a worldwide epidemic with many comorbidities. It has been demonstrated that oxidative stress can exacerbate obesity development. We have previously published that systemic administration of pNaKtide, a Na/K-ATPase signaling antagonist, was able to decrease oxidative stress and adipogenesis by blocking Na/K-ATPase signaling mediated amplification of oxidative stress. Hypothesis: Adipocyte dysfunction in mice fed western diet (WD) may be prevented by lentiviral-mediated adipocyte-specific delivery of pNaKtide. Methods: C57Bl6 mice were randomly divided into five groups: 1) normal chow 2) normal chow+lenti-adipo-pNaKtide 3) WD 4) WD+lenti-adipo-GFP and 5) WD+lenti-adipo-pNaKtide (n=6-8/group). Lentiviral constructs with pNaKtide driven by an adiponectin promoter were used to achieve pNaKtide expression specifically in adipose tissue. Groups 2 and 5 were given an intraperitoneal injection of lenti-adipo-pNaKtide and group 4 was given an intraperitoneal injection of lenti-adipo-GFP at beginning of the experiment and again at week 2; total time=12 weeks. Body weight was measured weekly. Glucose clearance was determined using an intraperitoneal glucose tolerance test before termination of the experiment. At sacrifice body weight, visceral and subcutaneous fat content of all mice were measured. Blood samples were collected for determination of inflammatory cytokines. Tissues were flash frozen and maintained at -80°C. Results: Lenti-adipo-pNaKtide significantly reduced WD-induced weight gain, and visceral and subcutaneous fat content. Lenti-adipo-pNaKtide reduced WD-induced changes in glucose tolerance and inflammatory markers TNFα, IL-6 and MCP-1 (p&lt;0.05). An increase in cardiac hypertrophy in WD animals was attenuated with lenti-adipo-pNaKtide (p&lt;0.05). Visceral fat of WD mice expressed higher levels of adipogenic markers PPARγ, FAS, and C/EBP. WD-induced Na/K-ATPase signaling was decreased. Conclusion: Collectively this study introduces the novel idea that adipocytes may have a systemic effect. Specifically targeting pNaKtide to the adipocytes with lenti-adipo-pNaKtide ameliorates this systemic effect. This new information is important in the development of new therapeutic targets for obesity.

Abstract 024: Angiotensin-(1-7) Attenuates Diet-induced Obesity in Mice by Browning White Adipose Tissue to Enhance Energy Expenditure

Overactivation of the renin-angiotensin (Ang) system, and in particular Ang II, contributes to obesity-induced insulin resistance via multiple mechanisms. Obesity is also associated with deficiency of Ang-(1-7), a beneficial hormone that opposes Ang II actions. In this study, we tested the hypothesis that Ang-(1-7) could prevent development of diet-induced obesity in mice. To test this hypothesis, adult male C57BL/6J mice received 12-week Ang-(1-7) (400 ng/kg/min; n=7) or saline (n=6) infusion via subcutaneous osmotic mini-pumps. Mice were placed on 60% high fat diet (HFD) immediately following mini-pump implantation. Body composition, energy balance, and insulin sensitivity were measured during the last week of treatment. Ang-(1-7) attenuated HFD-induced weight gain (39.7±1.3 vs. 43.9±0.7 g saline; p=0.023) and adiposity (32±1 vs. 29±1% saline; p=0.050). This weight-reducing effect was due to enhanced average energy expenditure [0.55±0.02 vs. 0.42±0.06 kcal/hour saline, p=0.038], with no changes in locomotor activity or food intake. Ang-(1-7) attenuated HFD-induced hyperinsulinemia (1.4±0.4 vs. 5.3±1.6-ng/mL saline; p=0.032) and improved the ability of intraperitoneal insulin to decrease blood glucose levels (20% reduction in area under the curve vs. saline; p=0.015), consistent with insulin-sensitizing effects. Given effects of Ang-(1-7) on energy expenditure, we performed blinded histological and semi-quantitative real-time PCR analysis of brown and white adipose tissue. Ang-(1-7) reduced HFD-induced lipid droplet accumulation in brown adipose, but did not improve thermogenesis markers (e.g. uncoupling protein-1). Ang-(1-7) improved inflammation in visceral white adipose (mean number crown-like structures: 3±1 vs. 8±2 saline; p=0.046). Ang-(1-7) reduced adipocyte size and increased gene expression of the browning marker PRDM16 (1.7±0.2 vs. 1.1±0.1; p=0.024) in subcutaneous white adipose. These data suggest that Ang-(1-7) attenuates diet-induced obesity in mice by enhancing energy expenditure, in part by browning of white adipose tissue. These overall findings provide rationale for targeting Ang-(1-7) to prevent development of obesity and related pathology such as insulin resistance and adipose inflammation.

Formononetin, an isoflavone, activates AMP-activated protein kinase/β-catenin signalling to inhibit adipogenesis and rescues C57BL/6 mice from high-fat diet-induced obesity and bone loss.

Balance between adipocyte and osteoblast differentiation is the key link of disease progression in obesity and osteoporosis. We have previously reported that formononetin (FNT), an isoflavone extracted from Butea monosperma, stimulates osteoblast formation and protects against postmenopausal bone loss. The inverse relationship between osteoblasts and adipocytes prompted us to analyse the effect of FNT on adipogenesis and in vivo bone loss, triggered by high-fat diet (HFD)-induced obesity. The anti-obesity effect and mechanism of action of FNT was determined in 3T3-L1 cells and HFD-induced obese male mice. Our findings show that FNT suppresses the adipogenic differentiation of 3T3-L1 fibroblasts, through down-regulation of key adipogenic markers such as PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα) and sterol regulatory element-binding protein (SREBP) and inhibits intracellular TAG accumulation. Increased intracellular reactive oxygen species levels and AMP-activated protein kinase (AMPK) activation accompanied by stabilisation of β-catenin were attributed to the anti-adipogenic action of FNT. In vivo, 12 weeks of FNT treatment inhibited the development of obesity in mice by attenuating HFD-induced body weight gain and visceral fat accumulation. The anti-obesity effect of FNT results from increased energy expenditure. FNT also protects against HFD-induced dyslipidaemia and rescues deterioration of trabecular bone volume by increasing bone formation and decreasing bone resorbtion caused by HFD. FNT's rescuing action against obesity-induced osteoporosis commenced at the level of progenitors, as bone marrow progenitor cells, obtained from the HFD mice group supplemented with FNT, showed increased osteogenic and decreased adipogenic potentials. Our findings suggest that FNT inhibits adipogenesis through AMPK/β-catenin signal transduction pathways and protects against HFD-induced obesity and bone loss.

Abstract 082: Chronic Angiotensin-(1-7) Attenuates the Development of Obesity in Mice by Enhancing Energy Expenditure

Activation of the renin-angiotensin system, and in particular angiotensin (Ang) II, is observed in obese patients and closely correlates with insulin resistance. Obesity is also associated with deficiency of Ang-(1-7), a vasodilatory peptide that mitigates Ang II actions. Accumulating evidence suggests that Ang-(1-7) has direct positive metabolic effects including reducing adiposity and reversing whole-body glucose intolerance and insulin resistance in animal models of cardiometabolic syndrome. In this study, we tested the hypothesis that chronic Ang-(1-7) administration would prevent high fat diet-induced obesity in mice, and determined potential mechanisms underlying this effect. To test this hypothesis, adult male C57BL/6J mice received a 12-week systemic infusion of Ang-(1-7) (400 ng/kg/min; n=7) or saline (n=6) via subcutaneous osmotic mini-pumps. Immediately following mini-pump implantation, mice were placed on a 60% high fat diet, with body mass measured weekly. Body composition (mq10 nuclear magnetic resonance analyzer), food and water intake, and energy expenditure (indirect calorimetry) were measured during the last week of treatment. Ang-(1-7) attenuated high fat diet-induced weight gain [39.7±1.3 Ang-(1-7) vs. 43.9±0.7 g saline at 12 weeks; p=0.023) and adiposity [32±1 Ang-(1-7) vs. 29±1% saline; p=0.050). The reduced gain in body weight following Ang-(1-7) was associated with increased average energy expenditure [0.55±0.02 Ang-(1-7) vs. 0.42±0.06 kcal/hour saline, p=0.038] and oxygen consumption [1.84±0.07 Ang-(1-7) vs. 1.39±0.23 ml/min saline, p=0.049] during the dark cycle, with no effect on locomotor activity. A similar trend for Ang-(1-7) to increase energy expenditure and oxygen consumption was observed during the light cycle. There were no significant differences in food or water intake following chronic Ang-(1-7) versus saline infusion. These findings suggest that targeting of Ang-(1-7) may be a novel strategy to prevent the development of obesity by enhancing energy expenditure, and further highlight the importance of the renin-angiotensin system in metabolic regulation.

Effect of Aronia melanocarpa (Black Chokeberry) supplementation on the development of obesity in mice fed a high-fat diet

BACKGROUND: Products derived from black chokeberry are claimed to be beneficial in treating chronic diseases, such as obesity and diabetes. OBJECTIVE: The objective of this study was to determine if supplementation with Aronia melanocarpa (black chokeberry) juice concentrate (AJC) has anti-obesity properties in mice fed obesogenic diets. METHODS: Male C57BL/6J mice (n = 10/dietary treatment) were placed on either a low-fat, high-sucrose (LFHS; 5% fat), LFHS+AJC (1.44 g AJC/kg diet), high-fat (HF; 30% fat), or HF+AJC for 12-weeks. RESULTS: Final body weight was lower in LFHS+AJC compared to LFHS, HF and HF+AJC (∼14, 20% and ∼16%, respectively; P < 0.05). Mice receiving LFHS and LFHS+AJC had significantly higher (P = 0.001) energy intake than HF and HF+AJC. LFHS-fed mice had less (–30%) epididymal fat (p < 0.05) than HF-fed mice, however mice on the LFHS+AJC had less epididymal fat per gram body weight than LFHS controls. There was no effect of diet or AJC on adipose tissue gene expression. There was no difference in plasma insulin, glucose or triglycerides between groups, however there was a positive effect of AJC on adiponectin (P = 0.059). There was also a significant effect of diet (LFHS versus HF) on HOMA-IR (P = 0.004) and HOMA-BCF (P = 0.002). CONCLUSIONS: The results from this study demonstrate that AJC supplementation has the potential to prevent weight gain and markers of obesity. Further research is needed to determine mechanisms of action.

MafB deficiency accelerates the development of obesity in mice.

MafB, a transcription factor expressed selectively in macrophages, has important roles in some macrophage‐related diseases, especially in atherosclerosis. In this study, we investigated the mechanism by which hematopoietic‐specific MafB deficiency induces the development of obesity. Wild‐type and hematopoietic cell‐specific Mafb‐deficient mice were fed a high‐fat diet for 10 weeks. The Mafb‐deficient mice exhibited higher body weights and faster rates of body weight increase than control mice. The Mafb‐deficient mice also had a higher percentage of body fat than the wild‐type mice, due to increased adipocyte size and serum cholesterol levels. Reverse transcription‐PCR analysis showed a reduction in apoptosis inhibitor of macrophage (AIM) in Mafb‐deficient adipose tissue. AIM is known as an inhibitor of lipogenesis in adipocytes and is expressed in adipose tissue macrophages. Collectively, our data suggest that Mafb deficiency in hematopoietic cells accelerates the development of obesity.

Abstract 19498: Scavenger Receptor BI (SR-BI) Deficiency Uncouples Obesity From Glucose Intolerance in Mice

Introduction: Scavenger receptor BI (SR-BI) is a multi-purpose player in cholesterol metabolism. Interestingly, several studies in humans have suggested that a significant relationship exists between the presence of common variants in the SR-BI gene and a higher body mass index. We therefore evaluated the contribution of SR-BI to high fat diet-induced obesity in mice. Methods and Results: Male SR-BI knockout (SR-BI KO; N=10) and wild-type (WT; N=9) mice were fed a diet containing 45% energy as fat for 12 weeks. SR-BI KO mice exhibited a worsened metabolic plasma profile as compared to WT controls with higher fasting levels of free cholesterol (+111%; P&lt;0.001), cholesterol esters (+84%; P&lt;0.001), triglycerides (+40%; P&lt;0.01), and glucose (+20%; P&lt;0.01). Daily food intake was similar in the two types of mice; 4.5±0.3 g for SR-BI KO vs 4.1±0.3 g for WT. Importantly, the relative increase in body weight over time was significantly greater in SR-BI KO mice (+51%) as compared to WT controls (+33%; two-way ANOVA P&lt;0.001 for genotype). The exacerbated increase in body weight could be attributed to a higher white adipose tissue mass (correlation coefficient R=0.87; P&lt;0.001). High fat diet-fed WT mice were glucose intolerant, but remained resistant to atherosclerosis. In contrast, atherosclerotic lesions could be readily detected in the aortic root of SR-BI KO mice (6.9±1.5 x 10 3 μm 2 ; P&lt;0.001), while their glucose tolerance was remarkably higher compared to that of controls (oral glucose tolerance test AUC 484±68 mM.min for SR-BI KO vs 875±130 mM.min for WT; P&lt;0.05). SR-BI deficiency thus uncouples obesity from glucose intolerance in mice. Conclusions: Our studies for the first time show that a proper SR-BI function inhibits the development of obesity in mice. Furthermore, these data imply that SR-BI may serve as therapeutic target to overcome the glucose intolerance normally associated with the presence of (morbid) obesity.