GABA administration improves liver function and insulin resistance in offspring of type 2 diabetic rats

This study investigated the role of GABA in attenuating liver insulin resistance (IR) in type 2 diabetes parents and reducing its risk in their descendants’ liver. Both sexes’ rats were divided into four groups of non-diabetic control, diabetic control (DC), GABA-treated (GABA), and insulin-treated (Ins). The study duration lasted for six months and the young animals followed for four months. Consequently, hyperinsulinemic-euglycemic clamp was performed for all animals. Apart from insulin tolerance test (ITT), serum and liver lipid profile were measured in all groups. Glycogen levels, expression of Foxo1, Irs2, Akt2, and Pepck genes in the liver were assessed for all groups. Overall, GABA improved ITT, increased liver glycogen levels and decreased lipid profile, blood glucose level, and HbA1c in parents and their offspring in compared to the DC group. GIR also increased in both parents and their offspring by GABA. Moreover, the expression of Foxo1, Irs2, Akt2, and Pepck genes improved in GABA-treated parents and their descendants in compared to DC group. Results indicated that GABA reduced liver IR in both parents and their offspring via affecting their liver insulin signaling and gluconeogenesis pathways.

Transcriptome changes of Takifugu obscurus liver after acute exposure to phenanthrene

Phenanthrene (Phe) is a model compound in PAHs research. Reportedly, Phe treatment induced oxidative stress and histological disorders to Takifugu obscurus liver. In the present study, to further explore the molecular responses of T. obscurus liver to Phe exposure, transcriptome sequencing was applied to compare mRNA transcription profiles between Phe treatment and the control. Compared with the control, 1581 and 1428 genes were significantly upregulated and downregulated in Phe treatment, respectively. Further analysis revealed that Phe treatment mainly upregulated genes in Ras-MAPK and PI3K-akt signaling pathways, which represented insulin resistance and further activated the FOXO signaling pathway. The triacylglycerol biosynthesis was promoted but the gluconeogenesis process was inhibited in response to Phe treatment, demonstrating that Phe exposure disturbed the sugar and lipid metabolism. Moreover, Phe treatment upregulated the apelin-AJP and ErbB signaling pathways, promoting angiogenesis in T. obscurus liver. Insulin resistance, promoted triacylglycerol biosynthesis and angiogenesis might explain the molecular mechanisms underlying carcinogenic toxicity of Phe. Overall, this study provides new insights to understand the environmental risk of Phe to fishes.

Adipocyte-specific deletion of IL-6 does not attenuate obesity-induced weight gain or glucose intolerance in mice

It has been suggested that interleukin-6 (IL-6) produced by adipocytes in obesity leads to liver insulin resistance, although this hypothesis has never been definitively tested. Accordingly, we did so by generating adipocyte-specific IL-6-deficient (AdipoIL-6−/−) mice and studying them in the context of diet-induced and genetic obesity. Mice carrying two floxed alleles of IL-6 (C57Bl/6J) were crossed with Cre recombinase-overexpressing mice driven by the adiponectin promoter to generate AdipoIL-6−/− mice. AdipoIL-6−/− and floxed littermate controls were fed a standard chow or high-fat diet (HFD) for 16 wk and comprehensively metabolically phenotyped. In addition to a diet-induced obesity model, we also examined the role of adipocyte-derived IL-6 in a genetic model of obesity and insulin resistance by crossing the AdipoIL-6−/− mice with leptin-deficient ( ob/ob) mice. As expected, mice on HFD and ob/ob mice displayed marked weight gain and increased fat mass compared with chow-fed and ob/+ (littermate control) animals, respectively. However, deletion of IL-6 from adipocytes in either model had no effect on glucose tolerance or fasting hyperinsulinemia. We concluded that adipocyte-specific IL-6 does not contribute to whole body glucose intolerance in obese mice.

Obesity and Insulin Resistance Are Inversely Associated with Serum and Adipose Tissue Carotenoid Concentrations in Adults

ABSTRACT Background Low tissue concentrations of carotenoids have been suggested to contribute to insulin resistance in obesity. Objectives The objectives of the study were to 1) evaluate the relations of adipose tissue and serum carotenoids with body fat, abdominal fat distribution, muscle, adipose tissue and liver insulin resistance, and dietary intake; 2) evaluate the relations and distributions of carotenoids detected in adipose tissue and serum; and 3) compare serum carotenoids and retinol concentrations in subjects with and without obesity. Methods Post hoc analysis of serum and adipose tissue carotenoids in individuals [n = 80; 31 men, 49 women; age (mean ± SEM): 51.4 ± 1.1 y] who participated in 2 separate studies conducted at the Clinical Research Facility at the Garvan Institute of Medical Research (Sydney) between 2008 and 2013. Retinol, α-carotene, β-carotene, ζ-carotene, lutein, lycopene, phytoene, and phytofluene were measured using HPLC. Body composition was measured by dual-energy X-ray absorptiometry. Insulin resistance was measured by 2-step hyperinsulinemic-euglycemic clamps with deuterated glucose (n = 64), and subcutaneous and visceral abdominal volume and liver and pancreatic fat by MRI (n = 60). Periumbilical subcutaneous fat biopsy was performed and carotenoids and retinol measured in the tissue (n = 16). Results We found that ζ-carotene, phytoene, and phytofluene were stored in considerable amounts in adipose tissue (25% of adipose tissue carotenoids). Carotenoid concentrations in adipose tissue and serum correlated significantly, but they followed different distributions: ζ-carotene was 3-fold higher in adipose tissue compared with serum, while lutein and lycopene made up 20% and 21% of serum carotenoids compared with 2% and 12% of adipose tissue carotenoids, respectively. Liver (P ≤ 0.028) and adipose tissue (P = 0.023), but not muscle (P ≥ 0.16), insulin resistance correlated inversely with many of the serum carotenoids. Conclusions Multiple serum and adipose tissue carotenoids are associated with favorable metabolic traits, including insulin sensitivity in liver and adipose tissue in humans.

Liraglutide improves hepatic steatosis and metabolic dysfunctions in a 3-week dietary mouse model of non-alcoholic steatohepatitis

ABSTRACTAimNon-alcoholic steatohepatitis (NASH) is an emerging health problem worldwide. However, efficacious pharmacological treatment for NASH is lacking. A major issue for preclinical evaluation of potential therapeutics for NASH is the limited number of appropriate animal models, i.e., models that do not require long-term dietary intervention and adequately mimic disease progression in humans. The present study aimed to evaluate a 3-week dietary mouse model of NASH and to validate it by studying the effects of liraglutide, a compound in advanced clinical development for NASH.MethodsC57BL6/J mice were fed a diet high in fat (60%), cholesterol (1.25%) and cholic acid (0.5%) along with 2% hydroxypropyl-β-cyclodextrin in drinking water (HFCC-CDX diet). Histological and biological parameters were measured at 1 and 3 weeks. Following 1-week diet induction, liraglutide was administrated daily for 2 weeks, and then NASH-associated phenotypic aspects were evaluated in comparison with control mice.ResultsPrior to treatment with liraglutide, mice fed the HFCC-CDX diet for 1 week developed liver steatosis and had increased levels of oxidative-stress markers and hepatic and systemic inflammation. For mice not treated with liraglutide, these aspects were even more pronounced after 3 weeks of the dietary period, with additional liver insulin resistance and fibrosis. Liraglutide treatment corrected the diet-induced alterations in glucose metabolism and significantly reduced hepatic steatosis and inflammation.ConclusionThis study provides a novel 3-week dietary model of mice that rapidly develop NASH features, and this model will be suitable for evaluating the therapeutic efficacy of compounds in preclinical drug development for NASH.

New therapy for fatty liver

Non-alcoholic fatty liver disease (NAFLD) is a leading cause of death from liver cirrhosis, endstage liver disease, and hepatocellular carcinoma. It is also associated with increased cardiovasculardisease and cancer related mortality. While lifestyle modifications are the mainstay of treatment,only a proportion of patients are able to make due to difficult to achieve and maintain, and so moretreatment options are required such as pharmacotherapy. This review presents the drugs used inmanaging NAFLD and their pharmacologic targets. Therapies are currently directed towards improvingthe metabolic status of the liver, insulin resistance, cell oxidative stress, apoptosis, inflammation orfibrosis. Several agents are now in large clinical trials and within the next few years, the availability oftherapeutic options for NAFLD will be approved. Keywords: nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, fibrosis, cirrhosis