RESUMO
Postmenopausal women represent a vulnerable population towards endocrine disruptors due to hormonal deficit. We previously demonstrated that chronic exposure of ovariectomized C57Bl6/J mice fed a high-fat, high-sucrose diet to a low-dose mixture of chemicals with one dioxin, one polychlorobiphenyl, one phthalate, and bisphenol A triggered metabolic alterations in the liver but the intestine was not explored. Yet, the gastrointestinal tract is the main route by which pollutants enter the body. In the present study, we investigated the metabolic consequences of ovarian withdrawal and E2 replacement on the various gut segments along with investigating the impact of the mixture of pollutants. We showed that genes encoding estrogen receptors (Esr1, Gper1 not Esr2), xenobiotic processing genes (e.g., Cyp3a11, Cyp2b10), and genes related to gut homeostasis in the jejunum (e.g., Cd36, Got2, Mmp7) and to bile acid biosynthesis in the gut (e.g., Fgf15, Slc10a2) and liver (e.g., Abcb11, Slc10a1) were under estrogen regulation. Exposure to pollutants mimicked some of the effects of E2 replacement, particularly in the ileum (e.g., Esr1, Nr1c1) suggesting that the mixture had estrogen-mimetic activities. The present findings have important implications for the understanding of estrogen-dependent metabolic alterations with regards to situations of loss of estrogens as observed after menopause.
Assuntos
Poluentes Ambientais , Animais , Dieta Hiperlipídica , Poluentes Ambientais/toxicidade , Estradiol , Estrogênios , Feminino , Humanos , Fígado , Camundongos , Camundongos Endogâmicos C57BL , OvariectomiaRESUMO
Environmental pollutants suspected of disrupting the endocrine system are considered etiologic factors in the epidemic of metabolic disorders. As regulation of energy metabolism relies on the integrated action of a large number of hormones, we hypothesized that certain chemicals could trigger changes in glucocorticoid signaling. To this end, we exposed C57Bl6/J female and male mice between 5 and 20 weeks of age to a mixture of 2,3,7,8- tetrachlorodibenzo-p-dioxin (20 pg/kg body weight/day [bw/d]), polychlorobiphenyl 153 (200 ng/kg bw/d), di-[2-ethylhexyl]-phthalate (500 µg/kg bw/d) and bisphenol A (40 µg/kg bw/d). In female mice fed a standard diet (ST), we observed a decrease in plasma levels of leptin as well as a reduced expression of corticoid receptors Nr3c1 and Nr3c2, of leptin and of various canonical genes related to the circadian clock machinery in visceral (VAT) but not subcutaneous (SAT) adipose tissue. However, Nr3c1 and Nr3c2 mRNA levels did not change in high-fat-fed females exposed to pollutants. In ST-fed males, pollutants caused the same decrease of Nr3c1 mRNA levels in VAT observed in ST-fed females but levels of Nr3c2 and other clock-related genes found to be down-regulated in female VAT were enhanced in male SAT and not affected in male VAT. The expression of corticoid receptors was not affected in the livers of both sexes in response to pollutants. In summary, exposure to a mixture of pollutants at doses lower than the no-observed adverse effect levels (NoAELs) resulted in sex-dependent glucocorticoid signaling disturbances and clock-related gene expression modifications in the adipose tissue of ST-fed mice.
Assuntos
Poluentes Ambientais/toxicidade , Glucocorticoides/metabolismo , Tecido Adiposo/metabolismo , Animais , Compostos Benzidrílicos , Peso Corporal , Poluentes Ambientais/metabolismo , Feminino , Expressão Gênica , Leptina/sangue , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fenóis , Dibenzodioxinas Policloradas/metabolismo , RNA Mensageiro/metabolismo , Sensibilidade e EspecificidadeRESUMO
Postmenopausal women may be at particular risk when exposed to chemicals especially endocrine disruptors because of hormonal deficit. To get more insight, ovariectomized C57Bl6/J mice fed a high-fat high-sucrose diet were chronically exposed from 5 to 20 weeks of age to a low-dose mixture of chemicals with one dioxin, one polychlorobiphenyl, one phthalate and bisphenol A. Part of the mice received as well E2 implants to explore the potential estrogenic dependency of the metabolic alterations. With this model, estrogen loss resulted in glucose but not lipid metabolism impairment, and E2 replacement normalized the enhanced body and fat pad weight, and the glucose intolerance and insulin resistance linked to ovariectomy. It also altered cholesterol metabolism in the liver concurrently with enhanced estrogen receptor Esr1 mRNA level. In addition, fat depots responded differently to estrogen withdrawal (e.g., selective mRNA enhancement of adipogenesis markers in subcutaneous and of inflammation in visceral fat pads) and replacement challenges. Importantly, the pollutant mixture impacted lipid deposition and mRNA expression of several genes related to lipid metabolism but not Esr1 in the liver. Adiponectin levels were altered as well. In addition, the mRNA abundance of the various estrogen receptors was regionally impacted in fat tissues. Besides, xenobiotic processing genes did not change in response to the pollutant mixture in the liver. The present findings bring new light on estrogen-dependent metabolic alterations with regards to situations of loss of estrogens as observed after menopause.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Poluentes Ambientais/toxicidade , Estradiol/administração & dosagem , Gordura Intra-Abdominal/efeitos dos fármacos , Gordura Subcutânea/efeitos dos fármacos , Animais , Estradiol/farmacologia , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/metabolismo , Gordura Intra-Abdominal/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Camundongos Endogâmicos C57BL , Ovariectomia , Gordura Subcutânea/metabolismo , Sacarose/administração & dosagem , Sacarose/efeitos adversos , Testes de Toxicidade Crônica , Xenobióticos/farmacocinéticaRESUMO
White adipose tissues are functionally heterogeneous and differently manage the excess of energy supply. While the expansion of subcutaneous adipose tissues (SAT) is protective in obesity, that of visceral adipose tissues (VAT) correlates with the emergence of metabolic diseases. Maintained in fat pads throughout life, adipose stem cells (ASC) are mesenchymal-like stem cells with adipogenesis and multipotent differentiation potential. ASC from distinct fat pads have long been reported to present distinct proliferation and differentiation potentials that are maintained in culture, yet the origins of these intrinsic differences are still unknown. Metabolism is central to stem cell fate decision in line with environmental changes. In this study, we performed high-resolution nuclear magnetic resonance (NMR) metabolomic analyses of ASC culture supernatants in order to characterize their metabolic phenotype in culture. We identified and quantified 29 ASC exometabolites and evaluated their consumption or secretion over 72 h of cell culture. Both ASC used glycolysis and mitochondrial metabolism, as evidenced by the high secretions of lactate and citrate, respectively, but V-ASC mostly used glycolysis. By varying the composition of the cell culture medium, we showed that glutaminolysis, rather than glycolysis, supported the secretion of pyruvate, alanine, and citrate, evidencing a peculiar metabolism in ASC cells. The comparison of the two types of ASC in glutamine-free culture conditions also revealed the role of glutaminolysis in the limitation of pyruvate routing towards the lactate synthesis, in S-ASC but not in V-ASC. Altogether, our results suggest a difference between depots in the capacity of ASC mitochondria to assimilate pyruvate, with probable consequences on their differentiation potential in pathways requiring an increased mitochondrial activity. These results highlight a pivotal role of metabolic mechanisms in the discrimination between ASC and provide new perspectives in the understanding of their functional differences.
RESUMO
Excessive consumption of industrialized food and beverages is a major etiologic factor in the epidemics of obesity and associated metabolic diseases because these products are rich in fat and sugar. In addition, they contain food contact materials and environmental pollutants identified as metabolism disrupting chemicals. To evaluate the metabolic impact of these dietary threats (individually or combined), we used a male mouse model of chronic exposure to a mixture of low-dose archetypal food-contaminating chemicals that was added in standard or high-fat, high-sucrose (HFHS) diet. Specifically, the mixture contained bisphenol A, diethylhexylphthalate, 2,3,7,8-tetrachlorodibenzo-p-dioxine and polychlorinated biphenyl 153. Exposure lasted from 5 to 20 weeks of age. Metabolic exploration was conducted setting the basis of candidate gene expression mRNA analyses in liver, jejunum and adipose tissue depots from 20 week-old mice. Strong metabolic deleterious effects of the HFHS diet were demonstrated in line with obesity-associated metabolic features and insulin resistance. Pollutant exposure resulted in significant changes on plasma triglyceride levels and on the expression levels of genes mainly encoding xenobiotic processing in jejunum; estrogen receptors, regulators of lipoprotein lipase and inflammatory markers in jejunum and adipose tissues as well as adipogenesis markers. Importantly, the impact of pollutants was principally evidenced under standard diet. In addition, depending on nutritional conditions and on the metabolic tissue considered, the impact of pollutants could mimic or oppose the HFHS effects. Collectively, the present study extends the cocktail effect concept of a low-dosed pollutant mixture and originally points to tissue-specificity responsiveness especially in jejunum and adipose tissues.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Exposição Ambiental/efeitos adversos , Poluentes Ambientais/efeitos adversos , Sacarose/metabolismo , Tecido Adiposo/metabolismo , Animais , Perfilação da Expressão Gênica , Jejuno/metabolismo , Masculino , Camundongos , Obesidade/metabolismo , Distribuição TecidualRESUMO
Obesity and diabetes have reached epidemic proportions the past few decades and continue to progress worldwide with no clear sign of decline of the epidemic. Obesity is of high concern because it is the main risk factor for a number of non-communicable diseases such as cardiovascular diseases and type 2 diabetes. Metabolic diseases constitute a major challenge as they are associated with an overall reduced quality of life and impose a heavy economic burden on countries. These are multifactorial diseases and it is now recognized that environmental exposure to man-made chemical pollutants is part of the equation. Yet, risk assessment procedures are based on a one-by-one chemical evaluation which does not meet the specificities of the multi-exposure scenario of life, e.g., a combined and long-term exposure to even the smallest amounts of chemicals. Indeed, it is assumed that environmental exposure to chemicals will be negligible based on the low potency of each chemical and that they do not interact. Within this mini-review, strong evidences are brought that exposure to low levels of multiple chemicals especially those shown to interfere with hormonal action, the so-called endocrine disrupting compounds do trigger metabolic disturbances in conditions in which no effect was expected if considering the concentration of each individual chemical in the mixture. This is known as the cocktail effect. It means that risk assessment procedures are not protective enough and thus that it should be revisited for the sake of Public Health.
RESUMO
We recently hypothesized that a mixture of low-dosed dioxin, polychlorobiphenyl, phthalate and bisphenol may induce estrogeno-mimetic activities in a model of lifelong-exposed female mice. Herein, we evaluated the impact of this mixture in estrogen deficiency conditions. Based on the protective effects of estrogens against metabolic disorders, we reasoned that exposure to pollutants should attenuate the deleterious metabolic effects induced by ovariectomy. In line with the hypothesis, exposure to pollutants was found to reduce the impact of ovariectomy on glucose intolerance and insulin resistance, to enhance the expression levels of the hepatic estrogen receptor α and to attenuate the ovariectomy-induced enhancement of the chemokine MCP-1/CCL2 considered as an indicator of estrogen signalling. Because of the very low doses of pollutants used in mixture, these findings may have strong implications in terms of understanding the potential role of environmental contaminants in the development of metabolic diseases, specifically in females during menopausal transition.
Assuntos
Poluentes Ambientais/farmacologia , Estrogênios/farmacologia , Ovariectomia , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/metabolismo , Animais , Compostos Benzidrílicos/farmacologia , Glicemia/análise , Quimiocina CCL2/metabolismo , Dietilexilftalato/farmacologia , Receptor alfa de Estrogênio , Feminino , Insulina/sangue , Resistência à Insulina , Fígado/efeitos dos fármacos , Fígado/metabolismo , Camundongos Endogâmicos C57BL , Fenóis/farmacologia , Bifenilos Policlorados/farmacologia , Dibenzodioxinas Policloradas/farmacologiaRESUMO
Obesity and associated metabolic disorders represent a major societal challenge in health and quality of life with large psychological consequences in addition to physical disabilities. They are also one of the leading causes of morbidity and mortality. Although, different etiologic factors including excessive food intake and reduced physical activity have been well identified, they cannot explain the kinetics of epidemic evolution of obesity and diabetes with prevalence rates reaching pandemic proportions. Interestingly, convincing data have shown that environmental pollutants, specifically those endowed with endocrine disrupting activities, could contribute to the etiology of these multifactorial metabolic disorders. Within this review, we will recapitulate characteristics of endocrine disruption. We will demonstrate that metabolic disorders could originate from endocrine disruption with a particular focus on convincing data from the literature. Eventually, we will present how handling an original mouse model of chronic exposition to a mixture of pollutants allowed demonstrating that a mixture of pollutants each at doses beyond their active dose could induce substantial deleterious effects on several metabolic end-points. This proof-of-concept study, as well as other studies on mixtures of pollutants, stresses the needs for revisiting the current threshold model used in risk assessment which does not take into account potential effects of mixtures containing pollutants at environmental doses, e.g., the real life exposure. Certainly, more studies are necessary to better determine the nature of the chemicals to which humans are exposed and at which level, and their health impact. As well, research studies on substitute products are essential to identify harmless molecules.
RESUMO
Environmental pollutants are potential etiologic factors of obesity and diabetes that reach epidemic proportions worldwide. However, it is important to determine if pollutants could exert metabolic defects without directly inducing obesity. The metabolic disturbances triggered in nonobese mice lifelong exposed to a mixture of low-dose pollutants (2,3,7,8-tetrachlorodibenzo-p-dioxine, polychlorinated biphenyl 153, diethylhexyl-phthalate, and bisphenol A) were compared with changes provoked by a high-fat high-sucrose (HFHS) diet not containing the pollutant mixture. Interestingly, females exposed to pollutants exhibited modifications in lipid homeostasis including a significant increase of hepatic triglycerides but also distinct features from those observed in diet-induced obese mice. For example, they did not gain weight nor was glucose tolerance impacted. To get more insight, a transcriptomic analysis was performed in liver for comparison. We observed that in addition to the xenobiotic/drug metabolism pathway, analysis of the hepatic signature illustrated that the steroid/cholesterol, fatty acid/lipid and circadian clock metabolic pathways were targeted in response to pollutants as observed in the diet-induced obese mice. However, the specific sets of dysregulated annotated genes (>1300) did not overlap more than 40% between both challenges with some genes specifically altered only in response to pollutant exposure. Collectively, results show that pollutants and HFHS affect common metabolic pathways, but by different, albeit overlapping, mechanisms. This is highly relevant for understanding the synergistic effects between pollutants and the obesogenic diet reported in the literature.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Poluentes Ambientais/administração & dosagem , Poluentes Ambientais/toxicidade , Fígado/efeitos dos fármacos , Animais , Compostos Benzidrílicos/administração & dosagem , Compostos Benzidrílicos/toxicidade , Relógios Circadianos/efeitos dos fármacos , Relógios Circadianos/genética , Duodeno/efeitos dos fármacos , Exposição Ambiental/efeitos adversos , Ácidos Graxos/genética , Ácidos Graxos/metabolismo , Feminino , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Inativação Metabólica/genética , Resistência à Insulina , Fígado/fisiologia , Camundongos Endogâmicos C57BL , Fenóis/administração & dosagem , Fenóis/toxicidade , Dibenzodioxinas Policloradas/administração & dosagem , Dibenzodioxinas Policloradas/toxicidade , Reprodutibilidade dos Testes , Esteroides/biossínteseRESUMO
Obesity is a major public health problem because it is a risk factor for metabolic disorders including type 2 diabetes and cardiovascular disorders. Notably, pollutants endowed with endocrine disrupting activities have been charged to contribute to the etiology of obesity and type 2 diabetes, especially if exposure occurs during the early life shown to be a highly vulnerable window of time. An overview on endocrine disrupters in relation with the obesogen and metabolic disruption hypothesis is presented. Convincing data support the plausibility of such hypothesis. They also highlight the limits of the current threshold model used in risk assessment which focused on single chemicals and does not take into account potential effects of mixtures containing pollutants at environmental doses, e.g. the real life exposure. Certainly, the principle of precaution should guide the making of decisions especially when considering early life exposure.
Assuntos
Poluentes Ambientais/toxicidade , Saúde , Doenças Metabólicas/induzido quimicamente , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Adulto , Disruptores Endócrinos/toxicidade , Exposição Ambiental/efeitos adversos , Feminino , Humanos , Recém-Nascido , Masculino , Gravidez , Efeitos Tardios da Exposição Pré-Natal/induzido quimicamente , Fatores de RiscoRESUMO
Pollutants are suspected to contribute to the etiology of obesity and related metabolic disorders. Apart from occupational exposure which concerns a subset of chemicals, humans are mostly exposed to a large variety of chemicals, all life-long and at low doses. Food ingestion is a major route of exposure and it is suggested that pollutants have a worsened impact when combined with a high-fat diet. In the experimental studies described herein, we aimed to add further evidence on the metabolic impact of food pollutants using a recently set up model in which mice are life-long fed a high-fat/high-sucrose diet (HFSD) with/without common food pollutants shown to exhibit metabolic disrupting activities. Specifically, this mixture comprised bisphenol A, dioxin, polychlorobiphenyl PCB153, and phthalate and was added in HFSD at doses resulting in mice exposure at the Tolerable Daily Intake dose range for each pollutant. We herein focused on the 7-week-old females which exhibited early signs of obesity upon HFSD feeding. We observed no signs of toxicity and no additional weight gain following exposure to the mixture but alleviated HFSD-induced glucose intolerance in the absence of alteration of gluconeogenesis and steatosis. It suggested that the observed metabolic improvement was more likely due to effects on muscle and/or adipose tissues rather than on the liver. Consistently, female mice exhibited enhanced lean/fat mass ratio and skeletal muscle insulin sensitivity. Moreover, expression levels of inflammatory markers were reduced in adipose tissue at 7 but enhanced at 12 weeks of age in agreement with the inverse alterations of glucose tolerance observed at these ages upon pollutant exposure in the HFSD-fed females. Collectively, these data suggest apparent biphasic effects of pollutants upon HFSD feeding along with obesity development. These effects were not observed in males and may depend on interactions between diet and pollutants.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Poluentes Ambientais/efeitos adversos , Metaboloma , Metabolômica , Obesidade/etiologia , Obesidade/metabolismo , Tecido Adiposo/metabolismo , Tecido Adiposo/patologia , Animais , Peso Corporal , Modelos Animais de Doenças , Ácidos Graxos/metabolismo , Feminino , Expressão Gênica , Mediadores da Inflamação/metabolismo , Fígado/metabolismo , Metabolômica/métodos , Camundongos , Oxirredução , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Sulfotransferases/genética , Sulfotransferases/metabolismo , Fatores de TempoAssuntos
Doenças Cardiovasculares/induzido quimicamente , Diabetes Mellitus Tipo 2/induzido quimicamente , Sistema Endócrino/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Contaminação de Alimentos , Obesidade/induzido quimicamente , Doenças Cardiovasculares/economia , Doenças Cardiovasculares/epidemiologia , Diabetes Mellitus Tipo 2/economia , Diabetes Mellitus Tipo 2/epidemiologia , Humanos , Doenças Metabólicas/induzido quimicamente , Doenças Metabólicas/economia , Doenças Metabólicas/epidemiologia , Nível de Efeito Adverso não Observado , Obesidade/economia , Obesidade/epidemiologiaRESUMO
Environmental contaminants are suspected to be involved in the epidemic incidence of metabolic disorders, food ingestion being a primarily route of exposure. We hypothesized that life-long consumption of a high-fat diet that contains low doses of pollutants will aggravate metabolic disorders induced by obesity itself. Mice were challenged from preconception throughout life with a high-fat diet containing pollutants commonly present in food (2,3,7,8-tetrachlorodibenzo-p-dioxin, polychlorinated biphenyl 153, diethylhexyl phthalate, and bisphenol A), added at low doses in the tolerable daily intake range. We measured several blood parameters, glucose and insulin tolerance, hepatic lipid accumulation, and gene expression in adult mice. Pollutant-exposed mice exhibited significant sex-dependent metabolic disorders in the absence of toxicity and weight gain. In males, pollutants increased the expression of hepatic genes (from 36 to 88%) encoding proteins related to cholesterol biosynthesis and decreased (40%) hepatic total cholesterol levels. In females, there was a marked deterioration of glucose tolerance, which may be related to the 2-fold induction of estrogen sulfotransferase and reduced expression of estrogen receptor α (25%) and estrogen target genes (>34%). Because of the very low doses of pollutants used in the mixture, these findings may have strong implications in terms of understanding the potential role of environmental contaminants in food in the development of metabolic diseases.
Assuntos
Fígado/efeitos dos fármacos , Fígado/metabolismo , Animais , Compostos Benzidrílicos/toxicidade , Western Blotting , Peso Corporal/efeitos dos fármacos , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Fenóis/toxicidade , Bifenilos Policlorados/toxicidade , Dibenzodioxinas Policloradas/toxicidade , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
CD36 is a ubiquitous membrane glycoprotein that binds long-chain fatty acids. The presence of a functional CD36 is required for the induction of satiety by a lipid load and its role as a lipid receptor driving cellular signal has recently been demonstrated. Our project aimed to further explore the role of intestinal CD36 in the regulation of food intake. Duodenal infusions of vehicle or sulfo-N-succinimidyl-oleate (SSO) was performed prior to acute infusions of saline or Intralipid (IL) in mice. Infusion of minute quantities of IL induced a decrease in food intake (FI) compared to saline. Infusion of SSO had the same effect but no additive inhibitory effect was observed in presence of IL. No IL- or SSO-mediated satiety occurred in CD36-null mice. To determine whether the CD36-mediated hypophagic effect of lipids was maintained in animals fed a satietogen diet, mice were subjected to a High-Protein diet (HPD). Concomitantly with the satiety effect, a rise in intestinal CD36 gene expression was observed. No satiety effect occurred in CD36-null mice. HPD-fed WT mice showed a diminished FI compared to control mice, after saline duodenal infusion. But there was no further decrease after lipid infusion. The lipid-induced decrease in FI observed on control mice was accompanied by a rise in jejunal oleylethanolamide (OEA). Its level was higher in HPD-fed mice than in controls after saline infusion and was not changed by lipids. Overall, we demonstrate that lipid binding to intestinal CD36 is sufficient to produce a satiety effect. Moreover, it could participate in the satiety effect induced by HPD. Intestine can modulate FI by several mechanisms including an increase in OEA production and CD36 gene expression. Furthermore, intestine of mice adapted to HPD have a diminished capacity to modulate their food intake in response to dietary lipids.
Assuntos
Antígenos CD36/metabolismo , Dieta , Mucosa Intestinal/metabolismo , Resposta de Saciedade , Animais , Antígenos CD36/genética , Ingestão de Alimentos/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Intestinos/efeitos dos fármacos , Ligantes , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ácidos Oleicos/biossíntese , Ácidos Oleicos/metabolismo , Ácidos Oleicos/farmacologia , Ligação Proteica , Resposta de Saciedade/efeitos dos fármacos , Succinimidas/metabolismo , Succinimidas/farmacologia , Fatores de TempoRESUMO
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related substances are ubiquitous environmental pollutants that exert adverse effects on reproductive processes. In testis, Leydig cells which produce testosterone are under hormonal and local control exerted by cytokines including TNFα. Using mouse Leydig primary cell cultures as a model, we studied the effects of TCDD on the steroidogenic outcome of Leydig cells and the gene expression levels of Ccl5 and Cxcl4, previously shown to be target genes of TCDD in testis. We found that TCDD did not alter the steroidogenic outcome of Leydig cells but that it up-regulated Cxcl4 gene expression levels. TCDD also impacted Ccl5 gene expression when cells had been co-treated with TNFα. TCDD action probably initiated with binding to the aryl hydrocarbon receptor (AhR) present on Leydig cells. TCDD regulated the gene expression levels of AhR (transient down-regulation) and its repressor AhRR and Cyp1b1 (up-regulation). The trophic human chorionic gonadotropin (hCG) hormone did not impact AhR, its repressor AhRR or Cyp1b1 but it opposed the TCDD-enhanced AhRR mRNA levels. Conversely, TNFα stimulated AhR gene expression levels. Collectively, it is suggested that the impact of TCDD on expression of target genes in Leydig cells may operate under the complex network of hormones and cytokines.
Assuntos
Células Intersticiais do Testículo/efeitos dos fármacos , Dibenzodioxinas Policloradas/toxicidade , Animais , Hidrocarboneto de Aril Hidroxilases/biossíntese , Fatores de Transcrição Hélice-Alça-Hélice Básicos/biossíntese , Fatores de Transcrição Hélice-Alça-Hélice Básicos/efeitos dos fármacos , Células Cultivadas , Quimiocina CCL5/metabolismo , Citocromo P-450 CYP1B1 , Expressão Gênica/efeitos dos fármacos , Técnicas In Vitro , Células Intersticiais do Testículo/metabolismo , Masculino , Camundongos , Fator Plaquetário 4/metabolismo , Receptores de Hidrocarboneto Arílico/biossíntese , Receptores de Hidrocarboneto Arílico/efeitos dos fármacos , Proteínas Repressoras/biossíntese , Proteínas Repressoras/efeitos dos fármacos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Testosterona/biossíntese , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
BACKGROUND: Dietary interventions are critical in the prevention of metabolic diseases. Yet, the effects of fatty fish consumption on type 2 diabetes remain unclear. The aim of this study was to investigate whether a diet containing farmed salmon prevents or contributes to insulin resistance in mice. METHODOLOGY/PRINCIPAL FINDINGS: Adult male C57BL/6J mice were fed control diet (C), a very high-fat diet without or with farmed Atlantic salmon fillet (VHF and VHF/S, respectively), and Western diet without or with farmed Atlantic salmon fillet (WD and WD/S, respectively). Other mice were fed VHF containing farmed salmon fillet with reduced concentrations of persistent organic pollutants (VHF/S(-POPs)). We assessed body weight gain, fat mass, insulin sensitivity, glucose tolerance, ex vivo muscle glucose uptake, performed histology and immunohistochemistry analysis, and investigated gene and protein expression. In comparison with animals fed VHF and WD, consumption of both VHF/S and WD/S exaggerated insulin resistance, visceral obesity, and glucose intolerance. In addition, the ability of insulin to stimulate Akt phosphorylation and muscle glucose uptake was impaired in mice fed farmed salmon. Relative to VHF/S-fed mice, animals fed VHF/S(-POPs) had less body burdens of POPs, accumulated less visceral fat, and had reduced mRNA levels of TNFα as well as macrophage infiltration in adipose tissue. VHF/S(-POPs)-fed mice further exhibited better insulin sensitivity and glucose tolerance than mice fed VHF/S. CONCLUSIONS/SIGNIFICANCE: Our data indicate that intake of farmed salmon fillet contributes to several metabolic disorders linked to type 2 diabetes and obesity, and suggest a role of POPs in these deleterious effects. Overall, these findings may participate to improve nutritional strategies for the prevention and therapy of insulin resistance.
Assuntos
Poluentes Atmosféricos/toxicidade , Resistência à Insulina/fisiologia , Obesidade/induzido quimicamente , Compostos Orgânicos/toxicidade , Salmão , Alimentos Marinhos/efeitos adversos , Células 3T3-L1 , Animais , Glicemia/metabolismo , Peso Corporal/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Intolerância à Glucose/induzido quimicamente , Imuno-Histoquímica , Insulina/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase em Tempo RealRESUMO
The hypothalamic melanocortin system--the melanocortin receptor of type 4 (MC4R) and its ligands: α-melanin-stimulating hormone (α-MSH, agonist, inducing hypophagia), and agouti-related protein (AgRP, antagonist, inducing hyperphagia)--is considered to play a central role in the control of food intake. We tested its implication in the mediation of the hunger-curbing effects of protein-enriched diets (PED) in mice. Whereas there was a 20% decrease in food intake in mice fed on the PED, compared to mice fed on an isocaloric starch-enriched diet, there was a paradoxical decrease in expression of the hypothalamic proopiomelanocortin gene, precursor of α-MSH, and increase in expression of the gene encoding AgRP. The hypophagia effect of PED took place in mice with invalidation of either MC4R or POMC, and was even strengthened in mice with ablation of the AgRP-expressing neurons. These data strongly suggest that the hypothalamic melanocortin system does not mediate the hunger-curbing effects induced by changes in the macronutrient composition of food. Rather, the role of this system might be to defend the body against the variations in food intake generated by the nutritional environment.
Assuntos
Proteínas Alimentares/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Proteína Relacionada com Agouti/genética , Proteína Relacionada com Agouti/metabolismo , Animais , Peso Corporal/efeitos dos fármacos , Ingestão de Alimentos/genética , Masculino , Camundongos , Pró-Opiomelanocortina/genética , Pró-Opiomelanocortina/metabolismo , Receptor Tipo 4 de Melanocortina/genética , Receptor Tipo 4 de Melanocortina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , alfa-MSH/genética , alfa-MSH/metabolismoRESUMO
To study the consequences of maternal obesity during gestation and suckling periods on metabolic features and expression of genes belonging to the melanocortinergic system, we developed Diet-Induced-Obesity (DIO) in mice fed high-fat-diet (HFD). After weaning, F1-descendants were fed the same diet than dams up to 16 weeks or received a 2-week standard chow at several time points. From birth, F1-DIO displayed higher body weight than F1-control. Hyperinsulinemia, hypertriglyceridemia, hyperleptinemia were detected from P10 and fasting hyperglycaemia from 2 week-post-weaning. From late gestation to 16-week-post-weaning the expression of MC4-R gene and/or the POMC/AgRP ratio was increased, suggesting an activation of this pathway to compensate the deleterious effects of HFD. Standard chow replacement at weaning normalized metabolic status but a partial recovery was obtained for later changes. Concomitant variations in the expression of the melanocortinergic genes were observed. Therefore, early nutritional intervention could override the impact of maternal and postnatal over-nutrition.
Assuntos
Proteína Relacionada com Agouti/genética , Hipotálamo/metabolismo , Obesidade/metabolismo , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Pró-Opiomelanocortina/genética , Fatores Etários , Proteína Relacionada com Agouti/metabolismo , Análise de Variância , Fenômenos Fisiológicos da Nutrição Animal , Animais , Dieta , Gorduras na Dieta , Feminino , Técnicas Imunoenzimáticas , Insulina/sangue , Leptina/sangue , Masculino , Camundongos , Estado Nutricional/genética , Obesidade/genética , Gravidez , Efeitos Tardios da Exposição Pré-Natal/genética , Pró-Opiomelanocortina/metabolismo , Receptor Tipo 4 de Melanocortina/genética , Receptor Tipo 4 de Melanocortina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Triglicerídeos/sangueRESUMO
CONTEXT: Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder resulting from resistance to the action of ACTH on the adrenal cortex. Affected individuals are deficient in cortisol and, if untreated, are likely to succumb to hypoglycemia and/or overwhelming infection. Mutations of the ACTH receptor (MC2R) and the melanocortin 2 receptor accessory protein (MRAP), FGD types 1 and 2 respectively, account for approximately 45% of cases. OBJECTIVE: A locus on chromosome 8 has previously been linked to the disease in three families, but no underlying gene defect has to date been identified. DESIGN: The study design comprised single-nucleotide polymorphism genotyping and mutation detection. SETTING: The study was conducted at secondary and tertiary referral centers. PATIENTS: Eighty probands from families referred for investigation of the genetic cause of FGD participated in the study. INTERVENTIONS: There were no interventions. RESULTS: Analysis by single-nucleotide polymorphism array of the genotype of one individual with FGD previously linked to chromosome 8 revealed a large region of homozygosity encompassing the steroidogenic acute regulatory protein gene, STAR. We identified homozygous STAR mutations in this patient and his affected siblings. Screening of our total FGD patient cohort revealed homozygous STAR mutations in a further nine individuals from four other families. CONCLUSIONS: Mutations in STAR usually cause lipoid congenital adrenal hyperplasia, a disorder characterized by both gonadal and adrenal steroid deficiency. Our results demonstrate that certain mutations in STAR (R192C and the previously reported R188C) can present with a phenotype indistinguishable from that seen in FGD.
Assuntos
Hiperplasia Suprarrenal Congênita/diagnóstico , Insuficiência Adrenal/diagnóstico , Mutação , Polimorfismo de Nucleotídeo Único , Hiperplasia Suprarrenal Congênita/genética , Insuficiência Adrenal/genética , Criança , Pré-Escolar , Análise Mutacional de DNA , Diagnóstico Diferencial , Feminino , Genótipo , Humanos , Lactente , Masculino , LinhagemRESUMO
The objectives of this study were to identify potential alterations in gene expression of melanocortin-4 receptor (MC4-R), proopiomelanocortin (POMC), and Agouti-related protein (AgRP) in mouse hypothalamus under a chronic peripheral infusion of leptin or at early (8 weeks) and advanced (16 weeks) phases of diet-induced obesity. Control or diet-induced obesity mice (8 or 16 weeks of high-fat diet) were either treated or not treated with leptin. Metabolic features were analyzed and expression of the genes of interest was measured by quantitative reverse transcriptase-PCR (RT-qPCR) and western blot. We reported that in control mice, but not in obese mice, leptin infusion induced an increase in POMC mRNA level as well as in MC4-R mRNA level suggesting that leptin could act directly and/or through alpha-melanocyte-stimulating hormone (alpha-MSH). This hypothesis was reinforced after in vitro studies, using the mouse hypothalamic GT1-7 cell line, since both leptin and Norleucine(4), D-Phenylalanine(7)-alpha-MSH (NDP-alpha-MSH) treatments increased MC4-R expression. After 8 weeks of high-fat diet, nondiabetic obese mice became resistant to the central action of leptin and their hypothalamic content of POMC and AgRP mRNA were decreased without modification of MC4-R mRNA level. After 16 weeks of high-fat diet, mice exhibited more severe metabolic disorders with type 2 diabetes. Moreover, hypothalamic expression of MC4-R was highly increased. In conclusion, several alterations of the melanocortin system were found in obese mice that are probably consecutive to their central resistance to leptin. Moreover, when the metabolic status is highly degraded (with all characteristics of a type 2 diabetes), other regulatory mechanisms (independent of leptin) can also take place.