Regulatory role of metallothionein-1/2 on development of sex differences in a high-fat diet-induced obesity.

AIMS: To evaluate the role of metallothionein (MT) in sex differences of obesity, we examined the effect of MT on regulation of lipid accumulation in female and male wild type (WT) and MT1/MT2-null (MT-KO) mice. MAIN METHODS: Male and female WT and MT-KO mice fed standard diet (SD) or high-fat diet (HFD) for 35 weeks. Surgical castration in male mice was also performed to examine the effects of androgen on fat accumulation under HFD condition. KEY FINDINGS: The fat mass and size of adipocytes in white adipose tissue (WAT) was greater in adult MT-KO mice than in WT mice after 35 weeks of SD feeding without gender differences, suggesting a role of MT in limiting WAT development during normal growth in both sexes. In female mice fed HFD, weights of WAT and body were greater in MT-KO mice than in WT mice, indicating that MT had a preventive role against excess fat accumulation. In male mice fed HFD, WAT weight hardly increased in MT-KO mice compared to the increase in WT mice. Surgically castrated WT males fed HFD had lower WAT weight compared with sham-treated mice, although castrated MT-KO males fed HFD had greater increases in WAT weight compared with sham-treated mice and castrated WT males. SIGNIFICANCE: These data suggest that MT could enhance the preventive action of estrogen against excess fat accumulation, on the contrary, MT augmented the ability of androgen to increase fat accumulation. MT may act to modify the susceptibility to obesity under sex hormones.

Metformin inhibits both oleic acid-induced and CB1R receptor agonist-induced lipid accumulation in Hep3B cells: The preliminary report.

Fatty liver is characterized by excessive accumulation of triglycerides within hepatocytes. Recent findings indicate that natural history of nonalcoholic fatty liver is regulated, in part, by endogenous cannabinoids. Metformin is an oral hypoglycemic medication which inhibits gluconeogenesis and glycogenolysis in hepatocytes and limits lipid storage in the liver through the inhibition of free fatty acid formation via induction of activated protein kinase activity (AMPK). Both endocannabinoids and metformin may modulate hepatosteatosis; therefore, it was interesting to examine whether metformin may affect lipid accumulation in hepatocytes by acting on cannabinoid receptors, CB1 and CB2, in in vitro study. Hep3B cells were incubated with or without metformin (Met), phosphatidylcholine (PC), and oleic acid (OA). Cells without any of the examined substances served as negative control. Cells treated only with OA served as positive control. The quantity of intracellular lipids was assessed using Oil-Red-O staining. Selective CB1R agonist, arachidonyl-2-chloromethylamide (ACEA), and CB2R agonist, AM1241 (2-iodo-5-nitrophenyl)-[1-(methylpiperidin-2-ylmethyl)-1 H-indol-3-yl]methanone, were also used to treat Hep3B cells. In some experiments, antagonist for CB1R, AM6545, or SR144528 as selective antagonist of CB2R were used. In the study, Met decreased lipid accumulation in cells treated with OA and inhibited CB1R agonist-induced lipid accumulation in hepatocytes. The CB2R agonist-induced hepatic lipid accumulation was not inhibited by metformin. The results indicate that metformin may interact with endocannabinoid system in the liver by inhibiting CB1R agonist-stimulated fat accumulation in hepatocytes.

Swertiamarin decreases lipid accumulation dependent on 3-ketoacyl-coA thiolase.

Natural compounds are important resources for drug discovery. Using Caenorhabditis elegans (C. elegans) models, we screened active natural compounds with lipid lowering effects. Swertiamarin was found as a potent candidate to reduce lipid content in C. elegans. Using RNAi screening, we were able to demonstrate that kat-1 (ketoacyl thiolase-1) is necessary for the lipid lowering effect of swertiamarin. Furthermore, the activity of swertiamarin was verified in high fat diet induced obese mice. Consistent with the results in C. elegans, swertiamarin ameliorated high fat diet induced lipid deposition and hyperlipidemia. These results indicate that swertiamarin exerts lipid-lowering effects through kat-1 regulation and could serve as a possible therapeutic option to improve hyperlipidemia induced comorbidities.

Fermented Platycodon grandiflorum Extract Inhibits Lipid Accumulation in 3T3-L1 Adipocytes and High-Fat Diet-Induced Obese Mice.

The aim of this study was to investigate whether fermented Platycodon grandiflorum (FPG) inhibits lipid accumulation in 3T3-L1 adipocytes and mice with high-fat diet (HFD)-induced obesity. We evaluated the effect of FPG on antiadipogenic activity via regulation of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα), as well as protein expression of their target genes, fatty acid binding protein 4 (FABP4). We further examined the antiobesity effects of FPG on HFD-induced obesity in mice. The FPG was orally administered to mice with a HFD at 50, 100, or 200 mg/kg/day for 8 weeks. Our results show that FPG significantly inhibited fat accumulation during 3T3-L1 adipogenesis through downregulating adipogenic transcript factors. Moreover, FPG markedly reduced the final body weight with a decrease in epididymal adipose tissue mass and adipocyte size compared with the untreated HFD-induced group. The effects of FPG on HFD-induced obesity were primarily responsible for inhibiting adipogenesis in adipose tissue and regulating lipid metabolism, such as through lipogenesis and fatty acid oxidation. Additionally, FPG ameliorated serum total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels. Hence, FPG may be an alternative treatment for controlling obesity through downregulating lipid accumulation.

Flaxseed oil and alpha-lipoic acid combination ameliorates hepatic oxidative stress and lipid accumulation in comparison to lard.

BACKGROUND: Intake of high-fat diet is associated with increased non-alcoholic fatty liver disease (NAFLD). Hepatic lipid accumulation and oxidative stress are key pathophysiological mechanisms in NAFLD. Both flaxseed oil (FO) and α-lipoic acid (LA) exert potential benefit to NAFLD. The aim of this study was to determine the effect of the combination of FO and LA on hepatic lipid accumulation and oxidative stress in rats induced by high-fat diet. METHODS: LA was dissolved in flaxseed oil to a final concentration of 8 g/kg (FO + LA). The rodent diet contained 20% fat. One-fifth of the fat was soybean oil and the others were lard (control group), or 75% lard and 25% FO + LA (L-FO + LA group), or 50% lard and 50% FO + LA (M-FO + LA group), or FO + LA (H-FO + LA group). Male Sprague-Dawley rats were fed for 10 weeks and then killed for liver collection. RESULTS: Intake of high-fat lard caused a significant hepatic steatosis. Replacement with FO + LA was effective in reducing steatosis as well as total triglyceride and total cholesterol contents in liver. The combination of FO and LA also significantly elevated hepatic antioxidant defense capacities, as evaluated by the remarkable increase in the activities of SOD, CAT and GPx as well as the level of GSH, and the significant decline in lipid peroxidation. CONCLUSION: The combination of FO and LA may contribute to prevent fatty livers such as NAFLD by ameliorating hepatic lipid accumulation and oxidative stress.