Project description:We examined the effect of oral TUDCA treatment on hepatic steatosis and associated changes in hepatic gene expression in ob/ob mice.
Project description:We examined the effect of oral TUDCA treatment on hepatic steatosis and associated changes in hepatic gene expression in ob/ob mice. We administered TUDCA to ob/ob mice at a dose of 500 mg/kg twice a day by gastric gavage for 3 weeks. Body weight, glucose homeostasis, endoplasmic reticulum (ER) stress, and hepatic gene expression were examined in comparison with control ob/ob mice and normal littermate C57BL/6J mice.
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:Non-alcoholic fatty liver disease (NAFLD) is rapidly becoming the most common liver disease worldwide, yet the pathogenesis of NAFLD is only partially understood. Here, we investigated the role of the gut bacteria in NAFLD by stimulating the gut bacteria via feeding mice the fermentable dietary fiber guar gum and suppressing the gut bacteria via chronic oral administration of antibiotics. Guar gum feeding profoundly altered the gut microbiota composition, in parallel with reduced diet-induced obesity and improved glucose tolerance. Strikingly, despite reducing adipose tissue mass and inflammation, guar gum enhanced hepatic inflammation and fibrosis, concurrent with markedly elevated plasma and hepatic bile acid levels. Consistent with a role of elevated bile acids in the liver phenotype, treatment of mice with taurocholic acid stimulated hepatic inflammation and fibrosis. In contrast to guar gum, chronic oral administration of antibiotics effectively suppressed the gut bacteria, decreased portal secondary bile acid levels, and attenuated hepatic inflammation and fibrosis. Neither guar gum or antibiotics influenced plasma lipopolysaccharide levels. In conclusion, our data indicate a causal link between changes in gut microbiota and hepatic inflammation and fibrosis in a mouse model of NAFLD, possibly via alterations in bile acids.
Project description:To test whether NDGA attenuate dyslipidemia and hepatic steatosis by enhancing fatty acid oxidation through activation of PPAR-α. Using wild type (WT, C57BL/6) fed with chow diet as control, WT mice were either fed with high-fat diet or high-fat diet with NDGA (2.5g/kg food); ob/ob mice were fed with either chow or chow with NDGA (2.5 g/kg food), and maintained on the respective diets for 16 weeks. The expression of lipid metabolism related genes in the liver of these mice were analyzed using Phalanx GPL6845 platform (Mouse OneArray V1). Together with other biochemical/physiological data, our results suggest that the beneficial actions of NDGA on dyslipidemia and hepatic steatosis in ob/ob mice are exerted primarily through enhanced fatty acid oxidation and energy utilization via the activation of PPAR- α receptor activity. To examine the changes in gene expression in liver of WT and ob/ob mice with different NDGA diet treatment, RNA isolated from 3 animals of each group were used for studies of gene expression profiles. Phalanx GPL6845 platform (Mouse OneArray V1) was used for the microarrays analysis.
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
Project description:Osteoradionecrosis of the jaw (ORNJ) is a severe complication following head and neck radiotherapy that significantly impacts the quality of life of patients. Currently, there is a lack of comprehensive understanding of the microenvironmental factors involved in ORNJ. In this study, we reveal the activation of taurine metabolism in irradiated mandibular stromal cells using scRNA-Seq and demonstrate a decrease in taurine levels in irradiated bone marrow mesenchymal stromal cells (BMSCs) through metabolomics. Compared with unirradiated BMSCs, taurine uptake in irradiated BMSCs increases. Taurine concentrations in the peripheral blood and jaws of irradiated mice are significantly lower than those in unirradiated mice (P = 0.0064 and 0.0249 respectively). Supplementation with taurine promotes osteogenic differentiation, reduces oxidative stress, and decreases DNA damage in irradiated BMSCs. Oral administration of taurine significantly improves the survival rate of irradiated mice and enhances osteogenesis in irradiated jaws. Our study highlights the role of taurine in the recovery from radiation-induced jaw injury, and suggests its potential as a non-invasive therapeutic option for combating ORNJ.
Project description:We found out that bile acid pathways were deeply altered in cachectic mice bearing ectopic tumor, leading to an increase in portal and liver conjugated bile acid levels. Counteracting this increased level in conjugated bile acids using cholestyramine, a bile acid sequestrant, reduced hepatic inflammation in cachectic mice with no impact on steatosis and minor effects on thermogenesis. Hepatic whole transcriptome analysis identified 16 pathways altered in cachectic mice which were counteracted by cholestyramine, pointing out the large contribution of bile acids to hepatic disturbances occurring in cancer cachexia.
Project description:N-acyl taurines (NAT) are endogenous, bioactive conjugates of fatty acids and taurine with roles in glucose and lipid metabolism. In the liver, NATs share the taurine conjugation enzyme, bile acid-CoA:amino acid N-acyltransferase (BAAT), with bile acids, suggesting the potential of an overlapping hepatic synthesis pathway. However, the remaining enzymes involved in NAT production in the liver remain unknown. This study aimed to investigate the overlap between hepatic NAT and bile acid synthesis to identify additional enzymes involved in NAT synthesis in the liver. Using transcriptomics of livers with altered NAT metabolism, we identified Slc27a5 which encodes fatty acid transport protein 5 (FATP5), as a potential node in the pathway. Knocking down the enzyme using siRNA in vivo confirmed that FATP5 is necessary for hepatic NAT synthesis and upstream of BAAT, likely through its acyl-CoA synthetase activity. The dual functions of this enzyme in activating both fatty acids and bile acids for conjugation implies functional overlap between the hepatic NAT and bile acid production pathway.
Project description:Metabolic dysfunction-associated steatotic liver disease and its progressive and inflammatory form metabolic dysfunction-associated steatohepatitis represents a global health challenge, with limited treatment options available. In this study we identified an endogenous, understudied omega-6 fatty acid metabolite, arachidonoyl-taurine (ARA-T), capable of mitigating liver disease. ARA-T levels increased in human plasma of chronic and acute fatty liver and their abundance can be driven in humans and mice by dietary supplementation of arachidonic acid. Surprisingly, our genetic model of elevated circulating ARA-T levels prevented inflammation and hepatic steatosis by increased uptake and turnover of fatty acids in the liver. Pharmacological administration of ARA-T reduced liver weight and diet-induced hepatic lipid deposition in mice, demonstrating its potential to protect against and reverse the progression of liver disease. Thus, ARA-T may represent a way to protect against pro-inflammatory actions of omega-6 fatty acids thereby contributing to regulation of inflammation and accumulation of hepatic lipids.