Project description:Using a C57BL6/J mouse model of diet-induced obesit,we observed that mannose supplementation of high fat diet (HFD)-fed mice prevents weight gain,lowers adiposity, reduces liver steatosis, and improves glucose tolerance and insulin sensitivity. We used microarrays to determine the gene expression pattern in epididymal fat frommice weaned on Normal diet (ND), HFD and HFD with mannose (HFDM)
Project description:Regulation of organismal homeostasis in response to nutrient availability is a vital physiological process that involves inter-organ communication. Understanding the mechanisms controlling systemic cross talk for maintenance of metabolic health is critical to counteract diet-induced obesity. Here, we show that cardiac-derived transforming growth factor beta 1 (TGF-b1) protects against weight gain and glucose intolerance in mice subjected to high-fat diet. Secretion of TGF-b1 by cardiomyocytes correlates with bioavailability of this factor in circulation. TGF-b1 prevents adipose tissue inflammation independent of body weight and glucose metabolism phenotypes, suggesting protection from adipocyte dysfunction-driven immune cell recruitment. TGF-b1 alters gene expression programs in white adipocytes, favoring their thermogenic fate and consequently increasing their mitochondrial oxygen consumption rates. Ultimately, subcutaneous and visceral white adipose tissue from heart-specific TGF-b1 transgenic mice fail to undergo cellular hypertrophy, leading to reduced overall adiposity during high-fat feeding. Thus, TGF-b1 is a critical mediator of heart-fat communication for regulation of systemic metabolism.
Project description:Background and aim: Diacylglycerol kinase (DGK) isoforms catalyze an enzymatic reaction that removes diacylglycerol (DAG) and thereby terminates protein kinase C (PKC) signaling by converting DAG to phosphatidic acid (PA). We have reported that downregulation of DGKδ (type II isozyme) causes peripheral insulin resistance, metabolic inflexibility, and obesity. Our aim was to determine whether overexpression of DGKδ protects against the development of metabolic impairments and obesity. Methods: We generated a transgenic mouse model overexpressing the human DGKδ2 isoform under the myosin light change promoter (DGKδ TG). We performed deep metabolic phenotyping of DGKδ TG and wild-type mice fed chow or high-fat diet. Mice were also given free access to running wheels to examine the effects of DGKδ overexpression on exercise-induced metabolic outcomes. Results: DGKδ TG mice were leaner than wild-type littermates, with improved glucose tolerance, increased glycogen storage in skeletal muscle, and enhanced glucose uptake in white adipose tissue. Moreover, DGKδ TG mice were protected against high fat diet (HFD)-induced glucose intolerance and obesity. DGKδ TG mice had reduced epididymal fat pad weight, and enhanced lipolysis. Strikingly, DGKδ overexpression recapitulates the beneficial effects exercise on metabolic outcomes. DGKδ overexpression and exercise have a synergistic effect on body weight reduction. Microarray analysis of skeletal muscle confirmed an overlap between genes associated with exercise and DGKδ overexpression. Gene ontology signatures of exercise and DGKδ overexpression were related to lipid storage, extracellular matrix, and glycogen biosynthesis pathways. Conclusion: We identify a role for DGKδ in glucose and energy homeostasis. Overexpression of DGKδ induces adaptive changes in both skeletal muscle and adipose tissue, resulting in protection against high fat diet-induced obesity. DGKδ overexpression recapitulates exercise-induced adaptations on energy homeostasis and skeletal muscle gene expression profiles.
Project description:To profile the expression of circulating miRNAs in a mouse model of diet-induced obesity (DIO) with subsequent weight-reduction with low-fat diet (LFD), eighteen C57BL/6 male mice were grouped into three subgroups as: (1) Control: the mice fed with the standard AIN-76A (fat: 11.5 kcal%) diet for 12 wks; (2) DIO: the mice fed with 58 kcal% high-fat diet for 12 wks; (3) DIO+LFD: the mice fed with high-fat diet for 8 wks to induce obesity, then changed to 10.5 kcal% low-fat diet for subsequent 4 wks.
Project description:Younger age and obesity increase the incidence and rates of metastasis of triple-negative breast cancer (TNBC), an aggressive subtype of breast cancer. The tissue microenvironment, specifically the extracellular matrix (ECM), is known to promote tumor invasion and metastasis. We sought to characterize the effect of both age and obesity on the ECM of mammary fat pads. We used a diet-induced obesity (DIO) model where 10-week-old female mice were fed a high-fat diet (HFD) for 16 weeks or a control chow diet (CD) where time points were every 4 weeks to monitor age and obesity HFD progression. We isolated the mammary fat pads to characterize the ECM at each time point. Utilizing proteomics, we found that the early stages of obesity were sufficient to induce distinct differences in the ECM composition of mammary fat pads that promote TNBC cell invasion. ECM proteins previously implicated in driving TNBC invasion Collagen IV and Collagen VI, were enriched with weight gain. Together these data implicate ECM changes in the primary tumor microenvironment as mechanisms by which age and obesity contribute to breast cancer progression.
Project description:The aim of this basic research is to test the efficacy of intranasal administration of Galanin-like Peptide (GALP) and its clinical application under the hypothesis that GALP prevents obesity in mice fed a high-fat diet (HFD). Focusing on the mechanism of regulation of lipid metabolism in peripheral tissues via the autonomic nervous system, we confirmed body weight changes after intranasal administration of GALP in diet-induced obesity (DIO) mice.
Project description:Background: Post-menopausal obesity is an established risk factor for breast cancer. Consumption of diets high in fat is known to be highly correlated with obesity. In this, we sought to evaluate the interaction(s) between high fat diet, weight gain and mammary carcinogenesis using an obese-resistant and obese-prone rat model with direct correlates to human disease. Methods: Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly. Results: The DMBA-treated OR rats on the 39% safflower diet had significantly greater incidence of ductal carcinoma-in-situ (DCIS) lesions and significantly greater DCIS multiplicity than DMBA-treated OR rats on the 10% safflower diet. These differences were not seen in the OP strain. Gene expression analysis of mammary ductal epithelium from OR rats on the high fat diet showed significant upregulation of proliferation-related genes compared to those consuming the low fat safflower diet. Again, these differences were not seen in the OP strain. Conclusion: Our findings indicate that consumption of high fat safflower diet enhances mammary carcinogenesis in an OR rat strain through increased proliferation of mammary epithelium at the time of exposure, but not in the OP rat strain. Thus, the diet-induced increase in sensitivity was strain-specific and independent of weight gain or obesity level. Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly.
Project description:Background: Post-menopausal obesity is an established risk factor for breast cancer. Consumption of diets high in fat is known to be highly correlated with obesity. In this, we sought to evaluate the interaction(s) between high fat diet, weight gain and mammary carcinogenesis using an obese-resistant and obese-prone rat model with direct correlates to human disease. Methods: Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly. Results: The DMBA-treated OR rats on the 39% safflower diet had significantly greater incidence of ductal carcinoma-in-situ (DCIS) lesions and significantly greater DCIS multiplicity than DMBA-treated OR rats on the 10% safflower diet. These differences were not seen in the OP strain. Gene expression analysis of mammary ductal epithelium from OR rats on the high fat diet showed significant upregulation of proliferation-related genes compared to those consuming the low fat safflower diet. Again, these differences were not seen in the OP strain. Conclusion: Our findings indicate that consumption of high fat safflower diet enhances mammary carcinogenesis in an OR rat strain through increased proliferation of mammary epithelium at the time of exposure, but not in the OP rat strain. Thus, the diet-induced increase in sensitivity was strain-specific and independent of weight gain or obesity level.
Project description:Physical exercise is a cornerstone for preventing diet-induced obesity, while it is unclear whether physical exercise could offset high-fat, high-calories diet (HFCD)-induced cardiac dysfunction. Here, mice were fed with HFCD and simultaneously subjected to physical exercise. As expected, physical exercise prevented HFCD-induced whole-body fat deposition. However, physical exercise exacerbated HFCD-induced cardiac damage. Further metabolomic analysis results showed that physical exercise induced circulating lipid redistribution, leading to excessive cardiac lipid uptake and lipotoxicity. Our study provides valuable insights into the cardiac effects of exercise in mice fed with HFCD, suggesting that counteracting the negative effect of HFCD by simultaneous physical exercise might be detrimental. Moreover, inappropriate physical exercise may damage certain organs even though it leads to weight loss and overall metabolic benefits. Of note, the current findings are based on animal experiments, the generalizability of these findings beyond this specific diet and mouse strain remains to be further explored.
Project description:We studied the effect of dietary fat type, varying in polyunsaturated/saturated fatty acid ratio's (P/S) on development of metabolic syndrome. C57Bl/6J mice were fed purified high-fat diets (45E% fat) containing palm oil (HF-PO; P/S 0.4), olive oil (HF-OO; P/S 1.1) or safflower oil (HF-SO; P/S 7.8) for 8 weeks. A low-fat palm oil diet (LF-PO; 10E% fat) was used as a reference. Additionally, we analyzed diet-induced changes in gut microbiota composition and mucosal gene expression. The HF-PO diet induced a higher body weight gain and liver triglyceride content compared to the HF-OO, HF-SO or LF-PO diet. In the intestine, the HF-PO diet reduced microbial diversity and increased the Firmicutes/Bacteroidetes ratio. Although this fits a typical obesity profile, our data clearly indicate that an overflow of the HF-PO diet to the distal intestine, rather than obesity itself, is the main trigger for these gut microbiota changes. A HF-PO diet-induced elevation of lipid metabolism-related genes in the distal small intestine confirmed the overflow of palm oil to the distal intestine. Some of these lipid metabolism-related genes were previously already associated with the metabolic syndrome. In conclusion, our data indicate that saturated fat (HF-PO) has a more stimulatory effect on weight gain and hepatic lipid accumulation than unsaturated fat (HF-OO and HF-SO). The overflow of fat to the distal intestine on the HF-PO diet induced changes in gut microbiota composition and mucosal gene expression. We speculate that both are directly or indirectly contributive to the saturated fat-induced development of obesity and hepatic steatosis. Keywords: Diet intervention study Nine-week-old C57Bl/6J mice were fed a low-fat diet (LF-PO) and three different types of high-fat diet, based on palm oil (HF-PO; P/S1.0), olive oil (HF-OO; P/S4.6) and safflower oil (HF-SO; P/S10.1) for 8 weeks. Body weight was recorded weekly and after 7 weeks of diet intervention an oral glucose tolerance test was performed. After 2 weeks of diet intervention, 6 mice per high-fat diet group were anaesthetized with a mixture of isofluorane (1.5%), nitrous oxide (70%) and oxygen (30%) and the small intestines were excised. Adhering fat and pancreatic tissue were carefully removed. The small intestines were divided in three equal parts along the proximal to distal axis (SI 1, SI 2 and SI 3) and microarray analysis was performed on mucosal scrapings.