Chronic administration of iron and copper potentiates adipogenic effect of high fat diet in Wistar rats

The primary objective of this research project is explore a possible adipogenic effect of iron and/or copper in albino Wistar rats kept on standard (STD) and high-fat (HFD) diets. The female Wistar rats in the study were divided into eight experimental groups (n = 6). Rats maintained on STD and HFD received 3 mg/l FeSO₄·7H₂O, 4.88 mg/l CuSO₄ and a combination of 1.5 mg/l FeSO₄·7H₂O and 2.44 mg/l CuSO₄ with drinking water. Control groups were kept on STD and HFD and received pure water without metal salts. Consumption of iron and copper in the groups of rats maintained on an STD did not produce a significant increase in weight, adipose tissue content or body mass index. However, the adipocyte size and infiltration were increased in the adipose tissue of STD-fed rats receiving a mixture of iron and copper with drinking water. The rats fed iron and copper and, especially, their combination on a HFD background had a significantly higher weight gain, adipose tissue content, morphometric parameters values and adipocyte size compared to STD- and HFD-fed controls. Iron and copper consumption produced their accumulation in the rats’ adipose tissue. Moreover, the studied metals reduced adipose tissue concentration of chromium and vanadium. The lipoprotein profile and serum oxidative stress biomarkers were affected in the rats receiving the metals and STD. Hyperglycemia was observed in the rats receiving the studied metals on HFD-background. Based on the analysis of the test subjects, the study suggests that iron and copper administration, especially combined, may potentiate adipogenic effect of HFD.     

Effect of Feeding and Withdrawal of Vanadium and Vitamin C on Egg Quality and Vanadium Residual Over Time in Laying Hens

The primary objective of the current study was to assess the influence of early high-fat feeding on tissue trace element content in young male Wistar rats. Twenty weanling male Wistar rats were divided into two groups fed standard (STD) or high-fat diet (HFD) containing 10 and 31.6 % of total calories from fat, respectively, for 1 month. Serum lipid spectrum, apolipoproteins, glucose, insulin, adiponectin, and leptin levels were assessed. The level of trace elements was estimated using inductively coupled plasma mass spectrometry. High-fat feeding significantly increased epidydimal (EDAT) and retroperitoneal adipose tissue (RPAT), as well as total adipose tissue mass by 34, 103, and 59 %, respectively. Serum leptin levels in HFD animals were twofold higher than those in the control rats. No significant difference in serum lipid spectrum, apolipoproteins, glucose, adiponectin, and insulin was detected between the groups. HFD significantly altered tissue trace element content. In particular, HFD-fed animals were characterized by significantly lower levels of Cu, I, Mn, Se, and Zn in the liver; Cr, V, Co, Cu, Fe, and I content of EDAT; Co, Cu, I, Cr, V, Fe, and Zn concentration in RPAT samples. At the same time, only serum Cu was significantly depressed in HFD-fed animals as compared to the control ones. Hair Co, Mn, Si, and V levels were significantly increased in comparison to the control values, whereas Se and I content was decreased. HFD feeding induced excessive adiposity and altered tissue trace element content in rats without insulin resistance, adiponectin deficiency, and proatherogenic state. Hypothetically, trace element disbalance may precede obesity-associated metabolic disturbances.     

Adipose tissue chromium and vanadium disbalance in high-fat fed Wistar rats

The primary objective of the current study is to investigate the relationship between adipose tissue chromium and vanadium content and adipose tissue dysfunction in a model of diet-induced obesity. A total of 26 female Wistar rats were fed either standard or high-fat diet (31.6% of fat from total caloric content) for 3 months. High-fat-feeding resulted in 21 and 33% decrease in adipose tissue chromium and vanadium content, respectively. No change was seen in hair chromium or vanadium levels. Statistical analysis revealed a significant inverse correlation of adipose tissue Cr and V with animal morphometric parameters and adipocyte size. Significant inverse dependence was observed between adipose tissue Cr and V and serum leptin and proinflammatory cytokines’ levels. At the same time, adipose tissue Cr and V levels were characterized by positive correlation between serum adiponectin and adiponectin/leptin ratio. Adipose tissue Cr and V were inversely correlated (p < 0.05) with insulin and homeostatic model assessment insulin resistance index (HOMA-IR) levels. Cr and V concentrations were not correlated with serum glucose in either high-fat fed or control rats; however, both serum glucose and HOMA-IR levels were significantly higher in high-fat fed, compared to control, rats. The results allow to hypothesize that impairment of adipose tissue Cr and V content plays a certain role in the development of adipose tissue endocrine dysfunction in obesity.     

HVEM-deficient mice fed a high-fat diet are protected from adipose tissue inflammation and glucose intolerance

HVEM is a member of the TNF receptor superfamily that plays a role in the development of various inflammatory diseases. In this study, we show that HVEM deficiency attenuates adipose tissue inflammatory responses and glucose intolerance in diet-induced obesity. Feeding a high-fat diet (HFD) to HVEM-deficient mice elicited a reduction in the number of macrophages and T cells infiltrated into adipose tissue. Proinflammatory cytokine levels in the adipose tissue decreased in HFD-fed HVEM-deficient mice, while levels of the anti-inflammatory cytokine IL-10 increased. Moreover, glucose intolerance and insulin sensitivity were markedly improved in the HFD-fed HVEM-deficient mice. These findings indicate that HVEM may be a useful target for combating obesity-induced inflammatory responses and insulin resistance.     

Stevioside ameliorates high-fat diet-induced insulin resistance and adipose tissue inflammation by downregulating the NF-κB pathway

Accumulating evidence suggests that adipose tissue is the main source of pro-inflammatory molecules that predispose individuals to insulin resistance. Stevioside (SVS) is a widely used sweetener with multiple beneficial effects for diabetic patients. In this study, we investigated the effect of SVS on insulin resistance and the pro-inflammatory state of adipose tissue in mice fed with a high-fat diet (HFD). Oral administration of SVS for 1month had no effect on body weight, but it significantly improved fasting glucose, basal insulin levels, glucose tolerance and whole body insulin sensitivity. Interestingly, these changes were accompanied with decreased expression levels of several inflammatory cytokines in adipose tissue, including TNF-α, IL6, IL10, IL1β, KC, MIP-1α, CD11b and CD14. Moreover, macrophage infiltration in adipose tissue was remarkably reduced by SVS. Finally, SVS significantly suppressed the nuclear factor-kappa b (NF-κB) signaling pathway in adipose tissue. Collectively, these results suggested that SVS may ameliorate insulin resistance in HFD-fed mice by attenuating adipose tissue inflammation and inhibiting the NF-κB pathway.     

Betaine Down Regulates Apelin Gene Expression in Cardiac and Adipose Tissues of Insulin Resistant Diabetic Rats Fed by High-Calorie Diet

Apelin is a newly discovered peptide that its serum level increases in diabetic patients with cardiovascular dysfunction. Recent studies indicate the beneficial actions of betaine in reducing the cardiovascular and metabolic complications, however data related to its effect on adipocytokine expression is limited. The aim of this study was to evaluate the effect of betaine supplementation on Apelin gene expression in cardiac muscle and adipose tissue of insulin resistance, diabetic rats fed by a high calorie diet. To induce insulin resistance rats were fed with high fat/high carbohydrate diet for five weeks and then 30 mg/kg STZ was injected intraperitoneally. After confirming of diabetes incidence (serum glucose above 7.5 mmol/l) the animals were treated with 1 % betaine in drinking water for 28 days. At days 14 and 28 after treatment, animals were euthanized and Apelin gene expression was evaluated by real time PCR and western blot in heart and adipose tissues. Serum levels of insulin, Apelin and glucose and HOMA–IR were also measured. Our results showed that feeding of rats by a high calorie diets caused insulin resistance, which was manifested by elevated plasma insulin, glucose and Apelin levels and also HOMA–IR. Apelin gene expression in heart and adipose tissues were significantly increased simultaneously with the progression of diabetes. Betaine supplementation decreased serum Apelin and down regulated Apelin expression in adipose tissue and cardiac muscle, particularly at day 28 of treatment. We concluded that betaine might improve metabolic and cardiovascular complications in diabetic patients by regulation of Apelin expression and secretion.     

Folic acid supplementation alters the DNA methylation profile and improves insulin resistance in high-fat-diet-fed mice

Folic acid (FA) supplementation may protect from obesity and insulin resistance, the effects and mechanism of FA on chronic high-fat-diet-induced obesity-related metabolic disorders are not well elucidated. We adopted a genome-wide approach to directly examine whether FA supplementation affects the DNA methylation profile of mouse adipose tissue and identify the functional consequences of these changes. Mice were fed a high-fat diet (HFD), normal diet (ND) or an HFD supplemented with folic acid (20 μg/ml in drinking water) for 10 weeks, epididymal fat was harvested, and genome-wide DNA methylation analyses were performed using methylated DNA immunoprecipitation sequencing (MeDIP-seq). Mice exposed to the HFD expanded their adipose mass, which was accompanied by a significant increase in circulating glucose and insulin levels. FA supplementation reduced the fat mass and serum glucose levels and improved insulin resistance in HFD-fed mice. MeDIP-seq revealed distribution of differentially methylated regions (DMRs) throughout the adipocyte genome, with more hypermethylated regions in HFD mice. Methylome profiling identified DMRs associated with 3787 annotated genes from HFD mice in response to FA supplementation. Pathway analyses showed novel DNA methylation changes in adipose genes associated with insulin secretion, pancreatic secretion and type 2 diabetes. The differential DNA methylation corresponded to changes in the adipose tissue gene expression of Adcy3 and Rapgef4 in mice exposed to a diet containing FA. FA supplementation improved insulin resistance, decreased the fat mass, and induced DNA methylation and gene expression changes in genes associated with obesity and insulin secretion in obese mice fed a HFD.     

Topiramate treatment causes skeletal muscle insulin sensitization and increased Acrp30 secretion in high-fat-fed male Wistar rats

We show that Topiramate (TPM) treatment normalizes whole body insulin sensitivity in high-fat diet (HFD)-fed male Wistar rats. Thus drug treatment markedly lowered glucose and insulin levels during glucose tolerance tests and caused increased insulin sensitization in adipose and muscle tissues as assessed by euglycemic clamp studies. The insulin-stimulated glucose disposal rate increased twofold (indicating enhanced muscle insulin sensitivity), and suppression of circulating FFAs increased by 200 to 300%, consistent with increased adipose tissue insulin sensitivity. There were no effects of TPM on hepatic insulin sensitivity in these TPM-treated HFD-fed rats. In addition, TPM administration resulted in a three- to fourfold increase in circulating levels of total and high-molecular-weight (HMW) adiponectin (Acrp30). Western blot analysis revealed normal AMPK (Thr(172)) phosphorylation in liver with a twofold increased phospho-AMPK in skeletal muscle in TPM-treated rats. In conclusion, 1) TPM treatment prevents overall insulin resistance in HFD male Wistar rats; 2) drug treatment improved insulin sensitivity in skeletal muscle and adipose tissue associated with enhanced AMPK phosphorylation; and 3) the tissue "specific" effects are associated with increased serum levels of adiponectin, particularly the HMW component.     

Changes in Serum Adiponectin in Mice Chronically Exposed to Inorganic Arsenic in Drinking Water

Cardiovascular disease and diabetes mellitus are prominent features of glucose and lipid metabolism disorders. Adiponectin is a key adipokine that is largely involved in glucose and lipid metabolism processes. A growing body of evidence suggests that chronic exposure to inorganic arsenic is associated with cardiovascular disease and diabetes mellitus. We hypothesized that arsenic exposure may increase the risk of cardiovascular disease and diabetes mellitus by affecting the level of adiponectin. In this study, we examined serum adiponectin levels, as well as serum levels of metabolic measures (including fasting blood glucose, insulin, total cholesterol, triglyceride, and high-density lipoprotein (HDL)-cholesterol) in C57BL/6 mice exposed to inorganic arsenic in drinking water (5 and 50 ppm NaAsO₂) for 18 weeks. Body mass and adiposity were monitored throughout the study. We found no significant changes in serum insulin and glucose levels in mice treated with arsenic for 18 weeks. However, arsenic exposure decreased serum levels of adiponectin, triglyceride, and HDL-cholesterol. Further, an inverse relationship was observed between urinary concentrations of total arsenic and serum levels of adiponectin. This study suggests that arsenic exposure could disturb the metabolism of lipids and increase the risk of cardiovascular disease by reducing the level of adiponectin.     

Diet-induced obesity and associated disorders are prevented by natural bioactive type 1 fish collagen peptides (Naticol®) treatment

To fight against metabolic disorders such as insulin resistance, new alimentary behaviors are developed. For instance, hyperproteined, gluten-free, or collagen-enriched diets could be preconized in order to reduce the consequences of obesity. In this aim, this study evaluates the potential effects of warm sea fish collagen peptides (Naticol®) on representative metabolic and inflammatory parameters. For that, male C57Bl6/J mice fed with either a chow- (CD) or high-fat diet (HFD) were submitted or not to specific collagen peptides in drinking water (4 g/kg bw/d) for 20 weeks. Weight, body composition, glucose tolerance, and insulin sensitivity were followed up. Effects of fish collagen peptides on various blood parameters reflecting the metabolism status were also measured (free fatty acids, triglycerides, cholesterol, hormones) together with adipocyte inflammation. Results showed that HFD-fed mice supplemented by fish collagen peptides exhibited a significant lower increase in body weight as soon as the twelfth week of treatment whereas no effect of the peptide was observed in CD fed mice. In line with this result, a weaker increase in fat mass in HFD-fed mice supplemented with Naticol® at both 9 and 18 weeks of treatment was also observed. In spite of this resistance to obesity promoted by fish collagen peptides treatment, no difference in glucose tolerance was found between groups whereas mice treated with Naticol® exhibited a lower basal glycemia. Also, even if no effect of the treatment on adipocyte lipolysis was found, a decrease of inflammatory cytokines was retrieved in collagen-supplemented group arguing for a potential better insulin sensitivity. Altogether, these results need to be completed but are the first describing a benefic role of warm sea fish collagen peptides in a context of metabolic disease paving the route for a potential utilization in human obesity-associated disorders.     

Female Mice are Protected against High-Fat Diet Induced Metabolic Syndrome and Increase the Regulatory T Cell Population in Adipose Tissue

Sex differences in obesity-induced complications such as type 2 diabetes have been reported. The aim of the study was to pinpoint the mechanisms resulting in different outcome of female and male mice on a high-fat diet (HFD). Mice fed control or HFD were monitored for weight, blood glucose, and insulin for 14 weeks. Circulating chemokines, islet endocrine function and blood flow, as well as adipose tissue populations of macrophages and regulatory T-lymphocytes (T_reg) were thereafter assessed. Despite similar weight (43.8±1.0 and 40.2±1.5 g, respectively), male but not female mice developed hyperinsulinemia on HFD as previously described (2.5±0.7 and 0.5±0.1 pmol/l, respectively) consistent with glucose intolerance. Male mice also exhibited hypertrophic islets with intact function in terms of insulin release and blood perfusion. Low-grade, systemic inflammation was absent in obese female but present in obese male mice (IL-6 and mKC, males: 77.4±17 and 1795±563; females: 14.6±4.9 and 240±22 pg/ml), and the population of inflammatory macrophages was increased in intra-abdominal adipose tissues of high-fat-fed male but not female mice. In contrast, the anti-inflammatory T_reg cell population increased in the adipose tissue of female mice in response to weight gain, while the number decreased in high-fat-fed male mice. In conclusion, female mice are protected against HFD-induced metabolic changes while maintaining an anti-inflammatory environment in the intra-abdominal adipose tissue with expanded T_reg cell population, whereas HFD-fed male mice develop adipose tissue inflammation, glucose intolerance, hyperinsulinemia, and islet hypertrophy.     

A minor role for lipocalin 2 in high-fat diet-induced glucose intolerance

Adipose tissue controls energy homeostasis and systemic insulin sensitivity through the elaboration of a series of cytokines and hormones, collectively termed "adipokines." We and others have identified Lcn2 as a novel adipokine, but its exact role in obesity-induced insulin resistance remains controversial. The aim of this study was to examine the metabolic phenotype of Lcn2(-/-) mice to clarify the role of Lcn2 in metabolism. Male and female Lcn2(-/-) and wild-type (WT) littermates were placed on either chow or high-fat diet (HFD) to characterize their metabolic phenotype. Studies included body weight and body composition, glucose and insulin tolerance tests, and adipokine expression studies in serum and in white adipose tissue (WAT). Neither chow nor HFD cohorts showed any differences in body weight or body composition. Chow-fed Lcn2(-/-) mice did not exhibit any difference in glucose homeostasis compared with WT mice. Fasting serum glucose levels were lower in the chow-fed Lcn2(-/-) mice, but this finding was not seen in the HFD cohort. Serum adiponectin, leptin, resistin, and RBP4 levels were not different between WT and Lcn2(-/-) on chow diet. HFD-fed male Lcn2(-/-) mice did display a small improvement in glucose tolerance, but no difference in insulin sensitivity was seen in either male or female Lcn2(-/-) mice on HFD. We conclude that the global ablation of Lcn2 has a minimal effect on obesity-associated glucose intolerance but does not appear to affect either age- or obesity-mediated insulin resistance in vivo.     

Quercetin reduces obesity-associated ATM infiltration and inflammation in mice: a mechanism including AMPKα1/SIRT1

Adipose tissue macrophage (ATM) plays a central role in obesity-associated inflammation and insulin resistance. Quercetin, a dietary flavonoid, possesses anti-inflammation and anti-insulin resistance properties. However, it is unclear whether quercetin can alleviate high-fat diet (HFD)-induced ATM infiltration and inflammation in mice. In this study, 5-week-old C57BL/6 mice were fed low-fat diet, HFD, or HFD with 0.l% quercetin for 12 weeks, respectively. Dietary quercetin reduced HFD-induced body weight gain and improved insulin sensitivity and glucose intolerance in mice. Meanwhile, dietary quercetin enhanced glucose transporter 4 translocation and protein kinase B signal in epididymis adipose tissues (EATs), suggesting that it heightened glucose uptake in adipose tissues. Histological and real-time PCR analysis revealed that quercetin attenuated mast cell and macrophage infiltration into EATs in HFD-fed mice. Dietary quercetin also modified the phenotype ratio of M1/M2 macrophages, lowered the levels of proinflammatory cytokines, and enhanced adenosine monophosphate-activated protein kinase (AMPK) α1 phosphorylation and silent information regulator 1 (SIRT1) expression in EATs. Further, using AMPK activator 5-aminoimidazole-4-carboxamide-1-β4-ribofuranoside and inhibitor Compound C, we found that quercetin inhibited polarization and inflammation of mouse bone marrow-derived macrophages through an AMPKα1/SIRT1-mediated mechanism. In conclusion, dietary quercetin might suppress ATM infiltration and inflammation through the AMPKα1/SIRT1 pathway in HFD-fed mice     

Protective effects of azelaic acid against high-fat diet-induced oxidative stress in liver, kidney and heart of C57BL/6J mice

Excess fat intake induces hyperinsulinaemia, increases nutrient uptake and lipid accumulation, amplifies ROS generation, establishes oxidative stress and morphological changes leading to tissue injury in the liver, kidney and heart of high-fat diet (HFD)-fed mice. The effect of azelaic acid (AzA), a C9 α,ω-dicarboxylic acid, against HFD-induced oxidative stress was investigated by assaying the activities and levels of antioxidants and oxidative stress markers in the liver, kidney and heart of C57BL/6J mice. Mice were segregated into two groups, one fed standard diet (NC) and the other fed high-fat diet (HFD) for 15 weeks. HFD-fed mice were subjected to intragastric administration of AzA (80 mg/kg BW)/RSG (10 mg/kg BW) during 11-15 weeks. Glucose, insulin, triglycerides, hepatic and nephritic markers were analysed in the plasma and the activity of enzymatic, non-enzymatic antioxidants and lipid peroxidation markers were examined in the plasma/erythrocytes, liver, kidney and heart of normal and experimental mice. We inferred significant decrease in enzymatic and non-enzymatic antioxidants along with significant increase in glucose, insulin, hepatic and nephritic markers, triglycerides and lipid peroxidation markers in HFD-fed mice. Administration of AzA could positively restore the levels of plasma glucose, insulin, triglycerides, hepatic and nephritic markers to near normal. AzA increased the levels of enzymatic and nonenzymatic antioxidants with significant reduction in the levels of lipid peroxidation markers. Histopathological examination of liver, kidney and heart substantiated these results. Hence, we put forward that AzA could counteract the potential injurious effects of HFD-induced oxidative stress in C57BL/6J mice.     

Quercetin can reduce insulin resistance without decreasing adipose tissue and skeletal muscle fat accumulation

Quercetin exhibits a wide range of biological functions. The first aim of the present work was to analyze the effects of quercetin on fat accumulation in adipose tissue and glycemic control in rats. Any potential involvement of muscle fatty acid oxidation in its effect on glycemic control was also assessed. Animals were fed a high-fat high-sucrose diet either supplemented with quercetin (30 mg/kg body weight/day), or not supplemented, for 6 weeks. One week before killing, a glucose tolerance test was carried out. Muscle triacylglycerol content, serum glucose, insulin, fructosamine and free fatty acids were measured, and homeostatic model assessment for insulin resistance (HOMA-IR) was calculated. The activities of lipogenic enzymes and lipoprotein lipase in adipose tissue, carnitine palmitoyl transferase-1b (CPT-1b) and citrate synthase in skeletal muscle, and the expression of several genes, ACO, CD36, CPT-1b, PPAR-α, PGC-1α, UCP₃, TFAM and COX-2 in skeletal muscle were analyzed. Quercetin caused no significant reduction in body weight or adipose tissue sizes. However, fructosamine, basal glucose and insulin, and consequently HOMA-IR, were significantly reduced by quercetin. No changes were observed in the activity of lipogenic enzymes and lipoprotein lipase. Muscle triacylglycerol content was similar in both experimental groups. The expression of ACO, CD36, CPT-1b, PPAR-α, PGC-1α, UCP₃, TFAM and COX-2 remained unchanged. It can be concluded that quercetin is more effective as an anti-diabetic than as an anti-obesity biomolecule. The improvement in insulin resistance induced by this flavonoid is not mediated by a delipidating effect in skeletal muscle.     

Development of insulin resistance preceded major changes in iron homeostasis in mice fed a high-fat diet

Type 2 diabetes mellitus (T2DM) and insulin resistance (IR) have been associated with dysregulation of iron metabolism. The basis for this association is not completely understood. To attempt to investigate this, we studied temporal associations between onset of insulin resistance (IR) and dysregulated iron homeostasis, in a mouse model of T2DM.Male C57Bl/6 mice (aged 8 weeks) were fed a high-fat diet (HFD; 60% energy from fat) or a control diet (CD; 10% energy from fat) for 4, 8, 12, 16, 20 and 24 weeks. Development of IR was documented, and various metabolic, inflammatory and iron-related parameters were studied in these mice.HFD-feeding induced weight gain, hepato-steatosis and IR in the mice. Onset of IR occurred from 12 weeks onwards. Hepatic iron stores progressively declined from 16 weeks onwards. Accompanying changes included a decrease in hepatic hepcidin (Hamp1) mRNA expression and serum hepcidin levels and an increase in iron content in the epididymal white adipose tissue (eWAT). Iron content in the liver negatively correlated with that in the eWAT. Factors known to regulate hepatic Hamp1 expression (such as serum iron levels, systemic inflammation, and bone marrow-derived erythroid regulators) were not affected by HFD-feeding. In conclusion, the results show that the onset of IR in HFD-fed mice preceded dysregulation of iron homeostasis, evidence of which were found both in the liver and visceral adipose tissue.     

Resveratrol does not increase body fat loss induced by energy restriction

Resveratrol (RSV) is known to have an antiobesogenic effect because it mimics energy restriction. However, hardly any evidence exists concerning the combined effects of RSV and energy restriction on body fat reduction. So, the aim of the present study was to determine whether RSV increases body fat reduction induced by energy restriction. Male Wistar rats were fed a high-fat, high-sucrose diet for 6 weeks to obtain a diet-induced obesity model. Then they were submitted to a mild energy restriction (25 %) without or with RSV supplementation (30 mg/kg body weight/day) for 2 weeks. Final body weight, subcutaneous and intra-abdominal white adipose tissues weights, Adipose Index, and serum triacylglycerol, cholesterol, glucose, and insulin were assessed. Lipoprotein lipase (LPL), fatty acid synthase (FAS), and acetyl coenzyme A carboxylase (ACC) activities, as well as their genetic expressions, were measured in white adipose tissue. Final body weight, white adipose tissue weights, Adipose Index, and serum triacylglycerol, cholesterol, and insulin were reduced in both groups, but no differences were found among them. FAS, ACC, and LPL activities and expressions were also similar in both groups. These results suggest a lack of any adjuvant effect of RSV on energy restriction for obesity treatment purposes.     

Expression of genes associated with inflammation and iron metabolism in 3T3-L1 cells induced with macrophages-conditioned medium,glucose and iron

Obesity is characterized by a chronic inflammatory process, with an increased volume of total adipose tissue, especially visceral, which secretes pro-inflammatory cytokines such as TNF-α and IL-6. Hepcidin (Hpc), a main iron metabolism regulator, is synthetized by an IL-6 stimuli, among others, in liver and adipose tissue, favoring an association between the inflammatory process and iron metabolism. Still there are questions remain regarding the interaction of these factors. Our aim was to study the effect of a macrophage-conditioned medium (MCM) on adipocyte cells challenged with glucose and/or iron. We studied the mRNA relative abundance of genes related to inflammation in differentiated 3T3-L1 cells challenged with Fe (40 µM), glucose (20 mM) or Fe/glucose (40 µM/20 mM) with or without MCM for 24 h. We also measured the intracellular iron levels under these conditions. Our results showed that when adipocytes were challenged with MCM, glucose and/or Fe, the intracellular iron and mRNA levels of pro-inflammatory cytokines increased. These responses were higher when all the stimuli were combined with MCM from macrophages. Thus, we showed that combined high glucose/high Fe alone or with MCM may contribute to an increase on intracellular iron and inflammatory response in 3T3-L1 differentiated cells, by increased mRNA levels of IL-6, TNF-α, MCP-1, Hpc and reducing adiponectin levels, enhancing the inflammatory processes.     

Respective contributions of maternal insulin resistance and diet to metabolic and hypothalamic phenotypes of progeny

Maternal obesity can influence susceptibility to obesity and type 2 diabetes in progeny. We examined the relationship of maternal insulin resistance (IR), a metabolically important consequence of increased adiposity, to adverse consequences of obesity for fetal development. We used mice heterozygous for a null allele of the insulin receptor (Insr) to study the contributions of maternal IR to offspring phenotype without the potential confound of obesity per se, and how maternal consumption of high-fat diet (HFD) may, independently and interactively, affect progeny. In progeny fed a 60% HFD, body weight and adiposity were transiently (5-7 weeks) increased in wild-type (+/+) offspring of Insr(+/-) HFD-fed dams compared to offspring of wild-type HFD-fed dams. Offspring of HFD-fed wild-type dams had increased body weight, blood glucose, and plasma insulin concentrations compared to offspring of chow-fed wild-type dams. Quantification of proopiomelanocortin (POMC) and neuropeptide-Y (NPY) populations in the arcuate nucleus of the hypothalamus (ARH) of offspring of wild-type vs. Insr(+/-) dams was performed to determine whether maternal IR affects the formation of central feeding circuits. We found a 20% increase in the number of Pomc-expressing cells at postnatal day 9 in offspring of Insr(+/-) dams. In conclusion, maternal HFD consumption-distinct from overt obesity per se-was a major contributor to increased body weight, adiposity, IR, and liver triglyceride (TG) phenotypes in progeny. Maternal IR played a minor role in predisposing progeny to obesity and IR, though it acted synergistically with maternal HFD to exacerbate early obesity in progeny.