Analysis of time-dependent adaptations in whole-body energy balance in obesity induced by high-fat diet in rats

Abstract Estrogen replacement therapy reduces the incidence of type 2 diabetes in postmenopausal women; however, the mechanism is unknown. Therefore, the aim of this study was to evaluate the metabolic effects of estrogen replacement therapy in an experimental model of menopause. At 8 weeks of age, female mice were ovariectomized (OVX) or sham (SHAM) operated, and OVX mice were treated with vehicle (OVX) or estradiol (E2) (OVX+E2). After 4 weeks of high-fat diet feeding, OVX mice had increased body weight and fat mass compared with SHAM and OVX+E2 mice. OVX mice displayed reduced whole-body energy expenditure, as well as impaired glucose tolerance and whole-body insulin resistance. Differences in whole-body insulin sensitivity in OVX compared with SHAM mice were accounted for by impaired muscle insulin sensitivity, whereas both hepatic and muscle insulin sensitivity were impaired in OVX compared with OVX+E2 mice. Muscle diacylglycerol (DAG), content in OVX mice was increased relative to SHAM and OVX+E2 mice. In contrast, E2 treatment prevented the increase in hepatic DAG content observed in both SHAM and OVX mice. Increases in tissue DAG content were associated with increased protein kinase Cϵ activation in liver of SHAM and OVX mice compared with OVX+E2 and protein kinase Cθ activation in skeletal muscle of OVX mice compared with SHAM and OVX+E2. Taken together, these data demonstrate that E2 plays a pivotal role in the regulation of whole-body energy homeostasis, increasing O2 consumption and energy expenditure in OVX mice, and in turn preventing diet-induced ectopic lipid (DAG) deposition and hepatic and muscle insulin resistance.

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Genetic Deletion of Syndecan-4 Alters Body Composition, Metabolic Phenotypes, and the Function of Metabolic Tissues in Female Mice Fed A High-Fat Diet (Running Title: Sdc4 Deficiency Affects Metabolic Phenotypes)

Nutrients ◽

10.3390/nu11112810 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2810 ◽

Cited By ~ 1

Author(s):

Maria De Luca ◽

Denise Vecchie’ ◽

Baskaran Athmanathan ◽

Sreejit Gopalkrishna ◽

Jennifer A. Valcin ◽

...

Keyword(s):

Insulin Sensitivity ◽

High Fat Diet ◽

Fatty Acid Synthase ◽

Serum Triglyceride ◽

Independent Study ◽

Whole Body ◽

Elderly Subjects ◽

Sensitivity Index ◽

High Fat ◽

Metabolic Phenotypes

Syndecans are transmembrane proteoglycans that, like integrins, bind to components of the extracellular matrix. Previously, we showed significant associations of genetic variants in the Syndecan-4 (SDC4) gene with intra-abdominal fat, fasting plasma glucose levels, and insulin sensitivity index in children, and with fasting serum triglyceride levels in healthy elderly subjects. An independent study also reported a correlation between SDC4 and the risk of coronary artery disease in middle-aged patients. Here, we investigated whether deletion of Sdc4 promotes metabolic derangements associated with diet-induced obesity by feeding homozygous male and female Sdc4-deficient (Sdc4-/-) mice and their age-matched wild-type (WT) mice a high-fat diet (HFD). We found that WT and Sdc4-/- mice gained similar weight. However, while no differences were observed in males, HFD-fed female Sdc4-/- mice exhibited a higher percentage of body fat mass than controls and displayed increased levels of plasma total cholesterol, triglyceride, and glucose, as well as reduced whole-body insulin sensitivity. Additionally, they had an increased adipocyte size and macrophage infiltration in the visceral adipose tissue, and higher triglyceride and fatty acid synthase levels in the liver. Together with our previous human genetic findings, these results provide evidence of an evolutionarily conserved role of SDC4 in adiposity and its complications.

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Time course of insulin resistance associated with feeding dogs a high-fat diet

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1997.272.1.e147 ◽

1997 ◽

Vol 272 (1) ◽

pp. E147-E154 ◽

Cited By ~ 13

Author(s):

A. P. Rocchini ◽

P. Marker ◽

T. Cervenka

Keyword(s):

Insulin Resistance ◽

Blood Pressure ◽

Glucose Uptake ◽

Dose Response ◽

High Fat Diet ◽

Time Course ◽

Rapid Development ◽

Diet Group ◽

Whole Body ◽

High Fat

The current study evaluated both the time course of insulin resistance associated with feeding dogs a high-fat diet and the relationship between the development of insulin resistance and the increase in blood pressure that also occurs. Twelve adult mongrel dogs were chronically instrumented and randomly assigned to either a control diet group (n = 4) or a high-fat diet group (n = 8). Insulin resistance was assessed by a weekly, single-dose (2 mU.kg-1.min-1) euglycemic-hyperinsulinemic clamp on all dogs. Feeding dogs a high-fat diet was associated with a 3.7 +/- 0.5 kg increase in body weight, a 20 +/- 4 mmHg increase in mean blood pressure, a reduction in insulin-mediated glucose uptake [(in mumol-kg-1.min-1) decreasing from 72 +/- 6 before to 49 +/- 7 at 1 wk, 29 +/- 3 at 3 wk, and 30 +/- 2 at 6 wk of the high-fat diet, P < 0.01]. and a reduced insulin-mediated increase in cardiac output. In eight dogs (4 high fat and 4 control), the dose-response relationship of insulin-induced glucose uptake also was studied. The whole body glucose uptake dose-response curve was shifted to the right, and the rate of maximal whole body glucose uptake was significantly decreased (P < 0.001). Finally, we observed a direct relationship between the high-fat diet-induced weekly increase in mean arterial pressure and the degree to which insulin resistance developed. In summary, the current study documents that feeding dogs a high-fat diet causes the rapid development of insulin resistance that is the result of both a reduced sensitivity and a reduced responsiveness to insulin.

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Tissue-specific expression of Sprouty1 in mice protects against high-fat diet-induced fat accumulation, bone loss and metabolic dysfunction

British Journal Of Nutrition ◽

10.1017/s0007114511006209 ◽

2011 ◽

Vol 108 (6) ◽

pp. 1025-1033 ◽

Cited By ~ 7

Author(s):

Sumithra Urs ◽

Terry Henderson ◽

Phuong Le ◽

Clifford J. Rosen ◽

Lucy Liaw

Keyword(s):

Adipose Tissue ◽

Bone Loss ◽

Bone Mass ◽

Body Fat ◽

High Fat Diet ◽

Conditional Knockout ◽

Whole Body ◽

High Fat ◽

Tissue Specific ◽

Diet Induced Obesity

We recently characterised Sprouty1 (Spry1), a growth factor signalling inhibitor as a regulator of marrow progenitor cells promoting osteoblast differentiation at the expense of adipocytes. Adipose tissue-specific Spry1 expression in mice resulted in increased bone mass and reduced body fat, while conditional knockout of Spry1 had the opposite effect with decreased bone mass and increased body fat. Because Spry1 suppresses normal fat development, we tested the hypothesis that Spry1 expression prevents high-fat diet-induced obesity, bone loss and associated lipid abnormalities, and demonstrate that Spry1 has a long-term protective effect on mice fed a high-energy diet. We studied diet-induced obesity in mice with fatty acid binding promoter-driven expression or conditional knockout of Spry1 in adipocytes. Phenotyping was performed by whole-body dual-energy X-ray absorptiometry, microCT, histology and blood analysis. In conditional Spry1-null mice, a high-fat diet increased body fat by 40 %, impaired glucose regulation and led to liver steatosis. However, overexpression of Spry1 led to 35 % (P < 0·05) lower body fat, reduced bone loss and normal metabolic function compared with single transgenics. This protective phenotype was associated with decreased circulating insulin (70 %) and leptin (54 %; P < 0·005) compared with controls on a high-fat diet. Additionally, Spry1 expression decreased adipose tissue inflammation by 45 %. We show that conditional Spry1 expression in adipose tissue protects against high-fat diet-induced obesity and associated bone loss.

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Whole body metabolism is improved by hemin added to high fat diet while counteracted by nitrite: a mouse model of processed meat consumption.

Food & Function ◽

10.1039/d1fo01199e ◽

2021 ◽

Author(s):

Diana Abu Halaka ◽

Ofer Gover ◽

Einat Rauchbach ◽

Shira Zelber-Sagi ◽

Betty Schwartz ◽

...

Keyword(s):

High Fat Diet ◽

Food Industry ◽

Food Additives ◽

Whole Body ◽

Processed Meat ◽

Traditional Food ◽

High Fat ◽

Curing Agents ◽

Whole Body Metabolism ◽

Processed Meat Consumption

Nitrites and nitrates are traditional food additives used as curing agents in the food industry. They inhibit the growth of microorganisms and convey a typical pink color to the meat....

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Baicalin Attenuates High Fat Diet-Induced Obesity and Liver Dysfunction: Dose-Response and Potential Role of CaMKKβ/AMPK/ACC Pathway

Cellular Physiology and Biochemistry ◽

10.1159/000374037 ◽

2015 ◽

Vol 35 (6) ◽

pp. 2349-2359 ◽

Cited By ~ 42

Author(s):

Youli Xi ◽

Miaozong Wu ◽

Hongxia Li ◽

Siqi Dong ◽

Erfei Luo ◽

...

Keyword(s):

Protein Kinase ◽

Fatty Liver ◽

High Fat Diet ◽

Molecular Mechanisms ◽

Liver Steatosis ◽

Serum Levels ◽

Whole Body ◽

Therapeutic Effects ◽

High Fat ◽

Dependent Protein

Background/Aims: Obesity-associated fatty liver disease affects millions of individuals. This study aimed to evaluate the therapeutic effects of baicalin to treat obesity and fatty liver in high fat diet-induced obese mice, and to study the potential molecular mechanisms. Methods: High fat diet-induced obese animals were treated with different doses of baicalin (100, 200 and 400 mg/kg/d). Whole body, fat pad and liver were weighed. Hyperlipidemia, liver steatosis, liver function, and hepatic Ca2+/CaM-dependent protein kinase kinase β (CaMKKβ) / AMP-activated protein kinase (AMPK) / acetyl-CoA carboxylase (ACC) were further evaluated. Results: Baicalin significantly decreased liver, epididymal fat and body weights in high fat diet-fed mice, which were associated with decreased serum levels of triglycerides, total cholesterol, LDL, alanine transaminase and aspartate transaminase, but increased serum HDL level. Pathological analysis revealed baicalin dose-dependently decreased the degree of hepatic steatosis, with predominantly diminished macrovesicular steatosis at lower dose but both macrovesicular and microvesicular steatoses at higher dose of baicalin. Baicalin dose-dependently inhibited hepatic CaMKKβ/AMPK/ACC pathway. Conclusion: These data suggest that baicalin up to 400 mg/kg/d is safe and able to decrease the degree of obesity and fatty liver diseases. Hepatic CaMKKβ/AMPK/ACC pathway may mediate the therapeutic effects of baicalin in high fat diet animal model.

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Effect of selective expression of dominant-negative PPARγ in pro-opiomelanocortin neurons on the control of energy balance

Physiological Genomics ◽

10.1152/physiolgenomics.00032.2016 ◽

2016 ◽

Vol 48 (7) ◽

pp. 491-501 ◽

Cited By ~ 9

Author(s):

Madeliene Stump ◽

Deng-Fu Guo ◽

Ko-Ting Lu ◽

Masashi Mukohda ◽

Xuebo Liu ◽

...

Keyword(s):

Body Weight ◽

Weight Gain ◽

Energy Balance ◽

High Fat Diet ◽

Control Diet ◽

Cre Recombinase ◽

Dominant Negative ◽

High Fat ◽

Pparγ Agonist ◽

The Brain

Peroxisome proliferator-activated receptor-γ (PPARγ), a master regulator of adipogenesis, was recently shown to affect energy homeostasis through its actions in the brain. Deletion of PPARγ in mouse brain, and specifically in the pro-opiomelanocortin (POMC) neurons, results in resistance to diet-induced obesity. To study the mechanisms by which PPARγ in POMC neurons controls energy balance, we constructed a Cre-recombinase-dependent conditionally activatable transgene expressing either wild-type (WT) or dominant-negative (P467L) PPARγ and the tdTomato reporter. Inducible expression of both forms of PPARγ was validated in cells in culture, in liver of mice infected with an adenovirus expressing Cre-recombinase (AdCre), and in the brain of mice expressing Cre-recombinase either in all neurons (NESCre/PPARγ-P467L) or selectively in POMC neurons (POMCCre/PPARγ-P467L). Whereas POMCCre/PPARγ-P467L mice exhibited a normal pattern of weight gain when fed 60% high-fat diet, they exhibited increased weight gain and fat mass accumulation in response to a 10% fat isocaloric-matched control diet. POMCCre/PPARγ-P467L mice were leptin sensitive on control diet but became leptin resistant when fed 60% high-fat diet. There was no difference in body weight between POMCCre/PPARγ-WT mice and controls in response to 60% high-fat diet. However, POMCCre/PPARγ-WT, but not POMCCre/PPARγ-P467L, mice increased body weight in response to rosiglitazone, a PPARγ agonist. These observations support the concept that alterations in PPARγ-driven mechanisms in POMC neurons can play a role in the regulation of metabolic homeostasis under certain dietary conditions.

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Abstract 58: Angiotensin-(1-7) Mas Receptors In The Arcuate Nucleus Of The Hypothalamus Protect Against High Fat Diet-induced Insulin Resistance In Female Mice

Hypertension ◽

10.1161/hyp.78.suppl_1.58 ◽

2021 ◽

Vol 78 (Suppl_1) ◽

Author(s):

Darren Mehay ◽

Sarah Bingaman ◽

Yuval Silberman ◽

Amy Arnold

Keyword(s):

Body Composition ◽

Insulin Sensitivity ◽

Energy Balance ◽

Glucose Tolerance ◽

High Fat Diet ◽

Metabolic Regulation ◽

Arcuate Nucleus ◽

Control Diet ◽

High Fat ◽

Metabolic Outcomes

Angiotensin (Ang)-(1-7) is a protective hormone of the renin-angiotensin system that improves insulin sensitivity, glucose tolerance, and energy balance in obese rodents. Our recent findings suggest that Ang-(1-7) activates mas receptors (MasR) in the arcuate nucleus of the hypothalamus (ARC), a brain region critical to control of energy balance and glucose homeostasis, to induce these positive metabolic effects. The distribution of MasR in the ARC and their role in metabolic regulation, however, is unknown. We hypothesized: (1) MasR are expressed in the ARC; and (2) deletion of ARC MasR leads to worsened metabolic outcomes following high fat diet (HFD). To test this, male and female C57Bl/6J mice were fed a 60% HFD or matched control diet ad libitum for 12 weeks. RNAscope in situ hybridization was performed on coronal ARC sections in rostral-middle-caudal regions to determine percentage of MasR positive neurons (n=5/group). In a second experiment, we assessed body composition and insulin and glucose tolerance in transgenic mice with deletion of MasR in ARC neurons (MasR-flox with AAV5-hsyn-GFP-Cre). RNAscope revealed a wide distribution on MasR-positive cells throughout the rostral to caudal extent of the ARC. The average percentage of MasR positive neurons was increased in females versus males, with HFD tending to increase MasR expression in both sexes (control diet male: 11±2; control diet female: 17±3; HFD male: 15±5; HFD female: 24±2; p sex : 0.030; p diet : 0.066; p int : 0.615; two-way ANOVA). Deletion of MasR in ARC neurons worsened insulin sensitivity in HFD but not control diet females (area under the curve for change in glucose from baseline: -1989±1359 HFD control virus vs. 2530±1762 HFD Cre virus; p=0.016), while fasting glucose, glucose tolerance, and body composition did not change. There was no effect of ARC MasR deletion on metabolic outcomes in control diet or HFD male mice. These findings suggest females have more MasR positive neurons in the ARC compared to males, which may be a sex-specific protective mechanism for glucose homeostasis. While further studies are needed to explore the role of ARC MasR in metabolic regulation, these findings support targeting Ang-(1-7) as an innovative strategy in obesity.

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Abstract 15813: Loss-of-Function Mutation in Toll-Like Receptor 4 Partially Protects Against Peripheral and Cardiac Insulin Resistance During a Long-Term High-Fat Diet

Circulation ◽

10.1161/circ.130.suppl_2.15813 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Ellen Jackson ◽

Elizabeth Rendina-Ruedy ◽

Matt Priest ◽

Brenda Smith ◽

Veronique Lacombe

Keyword(s):

Insulin Resistance ◽

Protein Content ◽

Glucose Transport ◽

High Fat Diet ◽

Whole Body ◽

Toll Like Receptor ◽

Loss Of Function ◽

High Fat ◽

The Face ◽

Tlr4 Activation

Diabetes mellitus is an epidemic disease characterized by alterations in glucose transport, which is tightly regulated by a family of specialized proteins called the glucose transporters (GLUTs). Although diabetic cardiomyopathy is a common complication in diabetic patients, its pathogenesis is still not well understood. Toll-like receptor (TLR) 4, which plays a central role in pathogen recognition by the innate immune system, may also play a critical role in linking inflammation and metabolic disease. We hypothesized that TLR4 activation triggers cardiac insulin resistance. We used mice with a loss-of function mutation in TLR4 (C3H/HeJ) and age-matched wild-type (WT, C57BL/6N) mice (n=8/group) to investigate how feeding a high-fat diet (HFD, 60% kcal from fat) for 16 weeks affected whole-body and cardiac glucose metabolism. After 16 weeks, WT mice fed a HFD were obese and developed hyperglycemia and insulin resistance compared to WT mice on a control diet (10% kcal from fat). The C3H/HeJ mice were partially protected against HFD-induced obesity and insulin resistance. In the heart, WT mice fed a HFD had a 30% decrease (P<0.05) in GLUT4 protein content as measured by Western Blot of cardiac crude membrane protein extracts. In contrast, the loss-of-function point mutation in TLR4 partially rescued cardiac GLUT4 content in the face of a HFD. Interestingly, there was a 40% increase (P<0.05) in the novel GLUT isoform, GLUT8, in the heart when mice of either genotype were fed a HFD. Additionally, GLUT4 protein content was negatively (P<0.05) correlated with GLUT8 content in the myocardium, suggesting that GLUT8 may act as a compensatory mechanism in the face of HFD-induced GLUT4 downregulation. Phosphorylated Akt, a key protein of the insulin signaling pathway, was positively (P<0.05) correlated with GLUT4 content, while the basal/inactive form was negatively correlated. In conclusion, these data suggest that activation of TLR4 activation during diabetes and obesity alters glucose transport by an Akt mechanism, and as such is a pathogenic factor during peripheral and cardiac insulin resistance. Overall, TLR4 appears to be a key modulator in the cross-talk between inflammatory and metabolic pathways, as well as a potential therapeutic target for diabetes.

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