Project description:Ob/ob mice were given 0, 12.5 or 25 ng/hr leptin through an osmotic pump. After 12 days, livers RNA was prepared and illumina microarrays were done. We tested whether leptin can ameliorate diabetes independent of weight loss by defining the lowest dose at which leptin treatment of ob/ob mice reduces plasma [glucose] and [insulin]. We found that a leptin dose of 12.5 ng/hour significantly lowers blood glucose and that 25 ng/hour of leptin normalizes plasma glucose and insulin without significantly reducing body weight, thus establishing that leptin exerts its most potent effects on glucose metabolism. To find possible mediators of this effect, we profiled liver mRNA using microarrays and identified IGF Binding Protein 2 as being regulated by leptin with a similarly high potency. Over-expression of IGFBP2 by an adenovirus reversed diabetes in insulin resistant ob/ob, Ay/a and diet-induced obese mice (DIO), as well as insulin deficient streptozotocin-treated mice. Hyperinsulinemic clamp studies showed a three-fold improvement in hepatic insulin sensitivity following IGFBP2 treatment in ob/ob mice. These results show that IGFBP2 can regulate glucose metabolism, a finding with potential implications for the pathogenesis and treatment of diabetes.
Project description:Ob/ob mice are characterized by a defect in leptin synthesis. In this study, the contribution of leptin deficiency to the deregulation of miRNA expression in ob/ob mice was determined by comparing leptin infused ob/ob mice to saline control.
Project description:Caloric Restriction in Leptin Deficiency Worsens Myocardial Steatosis: Failure to Upregulate PPAR gamma and Thermogenic Glyecrolipid/Fatty Acid Cycling Growing evidence supports an anti-lipotoxic role for leptin in preventing inappropriate peripheral tissue lipid deposition. Obese, leptin deficient ob/ob mice develop left ventricular (LV) hypertrophy and myocardial steatosis with increased apoptosis and decreased longevity. Here we investigated the cardiac effects of caloric restriction in leptin deficiency. Echocardiography was performed on C57Bl/6 wild-type mice (WT) and 7-month-old ob/ob mice fed ad lib, leptin-repleted (LR-ob/ob), or calorie-restricted (CR-ob/ob) for four weeks. Ventricular tissue was examined by electron microscopy (EM), mitochondrial coupling assay, and microarray expression profiling. LR and CR-ob/ob mice showed decreased body weight, heart weight, and LV wall thickness compared to ad lib ob/ob mice. LV fractional shortening was decreased in ad lib ob/ob mice, but restored to WT levels in LR and CR groups. However, EM revealed severe cardiac steatosis in the CR-ob/ob group compared to only moderate steatosis in ad lib ob/ob . Despite marked cardiac steatosis, CR (like LR) restored mitochondrial coupling to WT levels. CR up-regulated genes associated with oxidative stress and cell death, changes suggestive of cardiac lipotoxicity. LR, but not CR was shown to induce core genes involved in glycerolipid/free fatty acid cycling, a highly thermogenic pathway that can reduce intracellular lipid stores. LR, but not CR up-regulated and restored PGC1 and PPARto wild type levels; CR paradoxically further suppressed cardiac PPAR. Thus, leptin is essential in protecting the heart from lipotoxicity, and the inability to up-regulate the thermogenic glycerolipid/free fatty acid cycling pathway may impair the response of leptin deficient animals to the lipotoxic stress of calorie restriction. 6 month aged ob/ob mice were either leptin repleted with osmotic mini-pumps, calorie restricted to match the caloric intake of the leptin repleted mice, or fed ad lib for one month. 6-8 month C57Bl/6J mice were aged to serve as controls.
Project description:The purpose of this study was to identify leptin target genes and subsequent pathways correlated with leptin-mediated weight loss. We utilized the microarray technology to compare two types of leptin administration: one involving a direct stimulatory effect when administered peripherally (subcutaneous: SQ) and another that is indirect, involving a hypothalamic relay that suppresses food intake when leptin is administered centrally (intracerebroventricular: ICV). We report here the impact of central and peripheral administration of leptin on food intake, body weight and body fat composition in ob/ob mice. We also report hepatic gene expression changes caused by central versus peripheral leptin administration. Keywords: comparison Leptin deficient (ob/ob) mice were continuously administered leptin over 12-days using central (intracerebroventricular) or peripheral (subcutaneous) route of administration. Liver RNA was extracted and hybridized to Illumina microarrays and gene expression data was analyzed. The global gene expression profiles were compared after the central and peripheral leptin treatments in ob/ob mice and C57BL6 mice were used for the baseline gene expression.
Project description:We hypothesize that gene expression in the lungs of these differentially-treated mice are divergent thus contributing to the disparity in their phenotypes. More specifically, (1) Effects of Leptin-treatment of ob/ob postnatal mice lungs are known to be volume-dependent from 2 to 10 wks of age, and are independent of the hypometabolism associated with leptin deficiency. ; (2) Leptin is critical to postnatal lung remodeling, particularly related to enlarged alveolar surface area. In order to test these hypotheses at the gene expression level, we utilized microarray analysis to examine transcriptional differences between lungs of leptin or saline-treated ob/ob postnatal mice. Keywords: leptin, ob, lung
Project description:Caloric Restriction in Leptin Deficiency Worsens Myocardial Steatosis: Failure to Upregulate PPAR gamma and Thermogenic Glyecrolipid/Fatty Acid Cycling Growing evidence supports an anti-lipotoxic role for leptin in preventing inappropriate peripheral tissue lipid deposition. Obese, leptin deficient ob/ob mice develop left ventricular (LV) hypertrophy and myocardial steatosis with increased apoptosis and decreased longevity. Here we investigated the cardiac effects of caloric restriction in leptin deficiency. Echocardiography was performed on C57Bl/6 wild-type mice (WT) and 7-month-old ob/ob mice fed ad lib, leptin-repleted (LR-ob/ob), or calorie-restricted (CR-ob/ob) for four weeks. Ventricular tissue was examined by electron microscopy (EM), mitochondrial coupling assay, and microarray expression profiling. LR and CR-ob/ob mice showed decreased body weight, heart weight, and LV wall thickness compared to ad lib ob/ob mice. LV fractional shortening was decreased in ad lib ob/ob mice, but restored to WT levels in LR and CR groups. However, EM revealed severe cardiac steatosis in the CR-ob/ob group compared to only moderate steatosis in ad lib ob/ob . Despite marked cardiac steatosis, CR (like LR) restored mitochondrial coupling to WT levels. CR up-regulated genes associated with oxidative stress and cell death, changes suggestive of cardiac lipotoxicity. LR, but not CR was shown to induce core genes involved in glycerolipid/free fatty acid cycling, a highly thermogenic pathway that can reduce intracellular lipid stores. LR, but not CR up-regulated and restored PGC1-alpha and PPAR-alpha to wild type levels; CR paradoxically further suppressed cardiac PPAR-alpha. Thus, leptin is essential in protecting the heart from lipotoxicity, and the inability to up-regulate the thermogenic glycerolipid/free fatty acid cycling pathway may impair the response of leptin deficient animals to the lipotoxic stress of calorie restriction.
Project description:Leptin deficient mice is an appealing model for studying of metabolic syndromes. In this data, we provide 7 different tissues’ RNA-seq reads for each leptin-deficient mice (ob/ob) and wild type mice.
Project description:Leptin protein was thought to be unique to leptin receptor (LepR), but the phenotypes of mice with mutation in LepR (db/db) and leptin (ob/ob) are not identical, and the cause remains unclear. Here, we show that db/db, but not ob/ob mice had defect in tenotomy-induced heterotopic ossification (HO), implicating alternative ligand(s) for LepR might be involved. Ligand screening revealed that ANGPTL4, a stress and fasting-induced factor, was elicited from brown adipose tissue after tenotomy, bound to LepR on PRRX1+ mesenchymal cells at the HO cite, thus promotes chondrogenesis and HO development. Disruption of LepR in PRRX1+ cells, or lineage ablation of LepR+ cells, or deletion of ANGPTL4 impeded chondrogenesis and HO in mice. Surprisingly, exogenous ANGPTL4 treatment not only promoted HO, but facilitated the transformation from white to brown adipose tissue in mice. These findings identify ANGPTL4 as a novel ligand for LepR to stimulate HO and regulate fat metabolism.
Project description:Gallstone disease is a major contributor to health care costs in the United States. Approximately 12 % of the U.S. population has gallstones. As a result, more than 700,000 cholecystectomies are performed in this country each year. Many of these patients are obese and have a positive family history; but surprisingly, little is known about the link between obesity, genetics and gallstone formation. Obese individuals have been shown to have supersaturated bile, larger gallbladder fasting volumes and impaired gallbladder emptying. We have recently demonstrated that leptin plays a role in gallbladder motility. In an effort to understand the genetic basis for these observations, we tested the hypothesis that leptin would alter gallbladder gene expression. Methods: Affymetrix oligonucleotide microarrays 430 2.0 were used to compare gallbladder gene expression profiles from 12 week old control saline-treated leptin-deficient (Lep ob) and from leptin-treated Lep ob female mice. Analyses were performed on pooled RNA (n=4) from the gallbladders of 12 saline-treated Lep ob mice and from 12 Lep ob mice which were administered daily IP 5 ug/g of recombinant murine leptin for 4 weeks. Resulting data were analyzed utilizing Gene Chip Operating Software or MAS 5.0. Results: Of the genes analyzed 314 were upregulated and 108 were downregulated by leptin administration. Numerous genes related to gallstone pathogenesis, gallbladder absorption/secretion, inflammatory cytokines, and insulin resistance were altered by leptin. Experiment Overall Design: Female B6.V-lepob obese mice (n=24) aged 7 weeks were obtained from The Jackson Laboratory (Bar Harbor, ME). Upon arrival, mice were placed on a standard chow diet and were allowed to acclimate for 1 week before starting the experiment. For leptin treatments, mice received daily intraperitoneal injections of either recombinant mouse leptin (R&D Systems, Minneapolis, MN) (n=12) at a dose of 5 µg/g body weight or with saline as a control (n=12) for 4 weeks. At 12 weeks of age, mice were fasted overnight with free access to water. The following morning the mice underwent cholecystectomy. Three gallbladders were pooled to create 4 pools in each treatment and total RNA was isolated. Affymetrix murine 430 2.0 arrays were utilized to examine altered gallbladder gene expression as a result of leptin administration. The resulting data was analyzed utlizing Gene Chip Operating Software or MAS 5.0.
Project description:BACKGOUND: Drinking water can be contaminated with pharmaceuticals. However, it is uncertain whether this contamination can have harmful consequences for the liver, especially in the context of obesity. OBJECTIVES: To determine whether chronic, low dose exposure to pharmaceuticals could have deleterious effects in livers of lean and obese mice. METHODS: Lean and ob/ob male mice (5-week-old) were treated for 4 months with a mixture of 11 drugs (acetaminophen, caffeine, carbamazepine, cotinine, diclofenac, erythromycin, ibuprofen, phenazone, roxithromycin, salicylic acid and sulfamethoxazole) provided in drinking water at a concentration of 1 mg/L (for each drug). At the end of the treatment, investigations were performed in liver and plasma. RESULTS: Some liver and plasma abnormalities were observed in ob/ob mice treated with the cocktail containing 1 mg/L of each drug. For this dosage, a gene expression analysis by microarray showed altered expression of circadian genes (e.g. Bmal1, Dbp, Cry1) in lean and obese mice. RT-qPCR analyses carried out in all groups of animals indicated that expression of 8 different circadian genes was significantly modified in a dose-dependent manner. For some genes, a significant modification was observed for dosages as low as 100-1,000 ng/L. Drug mixture and obesity presented an additive effect on circadian gene expression. These data were confirmed in an independent study performed in female mice. CONCLUSIONS: Chronic, low dose exposure to pharmaceuticals disturbed hepatic expression of circadian genes, especially in obese mice. Because some of the 11 drugs can be found in the drinking water at such concentrations (e.g. acetaminophen, carbamazepine, ibuprofen) our data could be relevant in environmental toxicology, in particular for obese individuals exposed to these contaminants. C57BL/6J lean and ob/ob male mice (5-week-old) were treated for 4 months with a mixture of 11 drugs provided in drinking water at a concentration of 1 mg/L (for each drug). 4 groups were designed: untreated versus treated WT and ob/ob mice (n=6 mice per group).