n-3 polyunsaturated fatty acids in the regulation of adipose tissue browning and thermogenesis in obesity: Potential relationship with gut microbiota.

BACKGROUND: Obesity is a worldwide public health problem characterized by fat tissue accumulation, favouring adipose tissue and metabolic alterations. Increasing energy expenditure (EE) through brown adipose tissue activation and white adipose tissue (WAT) browning has gained relevance as a therapeutic approach. Different bioactive compounds, such as n-3 polyunsaturated fatty acids (PUFA), have been shown to induce those thermogenic effects. This process is regulated by the gut microbiota as well. Nevertheless, obesity is characterized by gut microbiota dysbiosis, which can be restored by weight loss and n-3 PUFA intake, among other factors. Knowledge gap: However, the role of the gut microbiota on the n-3 PUFA effect in inducing thermogenesis in obesity has not been fully elucidated. OBJECTIVE: This review aims to elucidate the potential implications of this interrelation on WAT browning adiposw sittue (BAT), BAT activity, and EE regulation in obesity models.

miR15a and miR16 in Chilean type 1 diabetes patients: possible association with apoptosis, inflammatory, or autoimmunity markers.

AIM: Type 1 diabetes mellitus (T1D) is an autoimmune disease characterized by the progressive destruction of ß cells, mediated by the interaction between T cells and several cytokines. The pathogenesis of T1D has established its possible relationship with miRNAs. In this study, we analyze the expression profile of miR-15a and miR-16 in peripheral blood mononuclear cells (PBMCs) and their possible association with apoptosis, inflammation, or autoimmunity markers. PATIENTS AND METHODOLOGY: 38 T1D patients and 41 control subjects were recruited. mRNAs were analyzed by means of qPCR and TaqMan probes. PBMCs were treated with different concentrations of glucose (baseline, 11 and 25 mM) with or without an inflammatory stimulus as TNF-α (10 ng/ml). RESULTS: A decrease in the levels of the miR-15a expression in basal conditions is observed in T1D patients compared to healthy control subjects (relative units 0.5 vs. 1.8, p < 0.05). This change in miR-15a and miR-16 is not affected by the addition of TNF-α. No association is observed with inflammatory markers (IL-6, TNF-α, vCAM) or apoptosis (bcl2 expression). The relationship with immunological markers shows an interaction effect between miR16 and IA-2 (p < 0.03). CONCLUSION: TNF-α does not affect the expression profile of miR-15a and miR16 in PBMCs. A weak correlation is observed between miR-16 and with the autoimmunity profile (IA-2 autoantibody).

miR15a and miR16 in Chilean type 1 diabetes patients: possible association with apoptosis, inflammatory, or autoimmunity markers.

AIM: Type 1 diabetes mellitus (T1D) is an autoimmune disease characterized by the progressive destruction of ß cells, mediated by the interaction between T cells and several cytokines. The pathogenesis of T1D has established its possible relationship with miRNAs. In this study, we analyze the expression profile of miR-15a and miR-16 in peripheral blood mononuclear cells (PBMCs) and their possible association with apoptosis, inflammation, or autoimmunity markers. PATIENTS AND METHODOLOGY: 38 T1D patients and 41 control subjects were recruited. mRNAs were analyzed by means of qPCR and TaqMan probes. PBMCs were treated with different concentrations of glucose (baseline, 11 and 25 mM) with or without an inflammatory stimulus as TNF-α (10 ng/ml). RESULTS: A decrease in the levels of the miR-15a expression in basal conditions is observed in T1D patients compared to healthy control subjects (relative units 0.5 vs. 1.8, p < 0.05). This change in miR-15a and miR-16 is not affected by the addition of TNF-α. No association is observed with inflammatory markers (IL-6, TNF-α, vCAM) or apoptosis (bcl2 expression). The relationship with immunological markers shows an interaction effect between miR16 and IA-2 (p < 0.03). CONCLUSION: TNF-α does not affect the expression profile of miR-15a and miR16 in PBMCs. A weak correlation is observed between miR-16 and with the autoimmunity profile (IA-2 autoantibody).

Chemically induced hypoxia promotes differential outcomes over preadipocyte- or adipocyte-macrophage communication.

Expansion of white adipose tissue induce insufficient vascularization, driving hypoxia and low-grade inflammation. Resident preadipocytes are thought to be involved. We evaluated the effects of hypoxia over preadipocytes and adipocytes, to determine which cellular type impacts the most over macrophages activation. 3T3-L1 cells were either differentiated, or maintained undifferentiated. Each group was subjected to the presence or absence of chemical hypoxia (200 µM CoCl2) for 24 h. Conditioned media were used as treatment for murine RAW264.7 macrophages for 24 h. Gene expression of HIF-1α and TNF-α, and the release of several markers were assessed. It was observed that culture media from hypoxic preadipocytes induced greater expression of inflammatory markers and NO release than culture media from hypoxic adipocytes, by macrophages. Gene expression correlated closer with inflammatory markers release specially on macrophages treated with conditioned media from preadipocytes. Hence, the present work highlights the importance of preadipocytes on inflammatory conditions in vitro.

Effects of hyperoxia exposure on metabolic markers and gene expression in 3T3-L1 adipocytes

Adipose tissue often becomes poorly oxygenated in obese subjects. This feature may provide cellular mechanisms involving chronic inflammation processes such as the release of pro-inflammatory cytokines and macrophage infiltration. In this context, the purpose of the present study was to determine whether a hyperoxia exposure on mature adipocytes may influence the expression of some adipokines and involve favorable changes in specific metabolic variables. Thus, 3T3-L1 adipocytes (14 days differentiated) were treated with 95 % oxygen for 24 h. Cell viability, intra and extracellular reactive oxygen species (ROS) content, glucose uptake, as well as lactate and glycerol concentrations were measured in the culture media. Also, mRNA levels of hypoxia-inducible factor (HIF)-1á, leptin, interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, peroxisome proliferator-activated receptor (PPAR)-Gamma, adiponectin, and angiopoietin-related protein (ANGPTL)4 were analyzed. Hyperoxia treatment increased intra and extracellular ROS content, reduced glucose uptake and lactate release and increased glycerol release. Additionally, a higher oxygen tension led to an upregulation of the expression of IL-6, MCP-1, and PPAR-Gamma, while ANGPTL4 was downregulated in the hyperoxia group with respect to control. The present data shows that hyperoxia treatment seems to produce an inflammatory response due to the release of ROS and the upregulation of pro-inflammatory adipokines, such as IL-6 and MCP-1. On the other hand, hyperoxia may have an indirect effect on insulin sensitivity due to the upregulation of PPAR-Gamma signaling as well as a possible modulation of both glucose and lipid metabolic markers. To our knowledge, this is the first study analyzing the effect of hyperoxia in 3T3-L1 adipocytes (AU)

Effects of hyperoxia exposure on metabolic markers and gene expression in 3T3-L1 adipocytes.

Adipose tissue often becomes poorly oxygenated in obese subjects. This feature may provide cellular mechanisms involving chronic inflammation processes such as the release of pro-inflammatory cytokines and macrophage infiltration. In this context, the purpose of the present study was to determine whether a hyperoxia exposure on mature adipocytes may influence the expression of some adipokines and involve favorable changes in specific metabolic variables. Thus, 3T3-L1 adipocytes (14 days differentiated) were treated with 95 % oxygen for 24 h. Cell viability, intra and extracellular reactive oxygen species (ROS) content, glucose uptake, as well as lactate and glycerol concentrations were measured in the culture media. Also, mRNA levels of hypoxia-inducible factor (HIF)-1α, leptin, interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, peroxisome proliferator-activated receptor (PPAR)-γ, adiponectin, and angiopoietin-related protein (ANGPTL)4 were analyzed. Hyperoxia treatment increased intra and extracellular ROS content, reduced glucose uptake and lactate release and increased glycerol release. Additionally, a higher oxygen tension led to an upregulation of the expression of IL-6, MCP-1, and PPAR-γ, while ANGPTL4 was downregulated in the hyperoxia group with respect to control. The present data shows that hyperoxia treatment seems to produce an inflammatory response due to the release of ROS and the upregulation of pro-inflammatory adipokines, such as IL-6 and MCP-1. On the other hand, hyperoxia may have an indirect effect on insulin sensitivity due to the upregulation of PPAR-γ signaling as well as a possible modulation of both glucose and lipid metabolic markers. To our knowledge, this is the first study analyzing the effect of hyperoxia in 3T3-L1 adipocytes.

Regulation by chronic-mild stress of glucocorticoids, monocyte chemoattractant protein-1 and adiposity in rats fed on a high-fat diet.

Stress has been reported as a widespread problem and several studies have linked obesity and inflammation-related diseases. Moreover, the combination of suffering from chronic stress and high energy intake might be related to the onset of some metabolic diseases. To study the possible relationships between stress, inflammatory status and obesity, a chronic-mild stress (CMS) paradigm with a high-fat dietary intake model (Cafeteria diet) was implemented on male Wistar rats for 11 weeks. Stress and dietary intake effects on animal adiposity, serum biochemical as well as glucocorticoids and inflammation markers were all analyzed. As expected, consuming a high-fat diet increased body weight, adiposity and insulin resistance in non-stressed animals. A decrease of total white adipose tissue (WAT) and an increase of fecal glucocorticoids, as well as angiotensinogen, and monocyte chemoattractant protein-1 (MCP-1) expression level in retroperitoneal WAT were found only on control-stressed rats. Regarding the serum MCP-1, a decrease was observed on animals under CMS while being fed Cafeteria diet. Furthermore, 11ß-hydroxysteroid dehydrogenase activity, a glucocorticoid and obesity biomarker in the liver, was influenced by high-fat diet intake but not by stress. Finally, statistical analysis showed a strong relation between MCP-1 expression levels in retroperitoneal WAT, fecal corticosterone and total WAT. This trial proved that CMS induced a glucocorticoid-mediated response, which was reduced by the intake of a Cafeteria diet. These findings suggest that a high-fat diet could protect against a stress condition and revealed a different behavior to a stressful environment depending on the nutritional status.

Vitamin C inhibits leptin secretion and some glucose/lipid metabolic pathways in primary rat adipocytes.

Antioxidant-based treatments are emerging as an interesting approach to possibly counteract obesity fat accumulation complications, since this is accompanied by an increased systemic oxidative stress. The aim of this study was to analyze specific metabolic effects of vitamin C (VC) on epididymal primary rat adipocytes. Cells were isolated and incubated for 72 h in culture medium, in the absence or presence of 1.6 nM insulin, within a range of VC concentrations (5-1000 microM). Glucose- and lipid-related variables as well as the secretion/expression patterns of several obesity-related genes were assessed. It was observed that VC dose dependently inhibited glucose uptake and lactate production, and also reduced glycerol release in both control and insulin-treated cells. Also, VC caused a dramatic concentration-dependent fall in leptin secretion especially in insulin-stimulated cells. In addition, VC (200 microM) induced Cdkn1a and Casp8, partially inhibited Irs3, and together with insulin drastically reduced Gpdh (listed as Gpd1 in the MGI database) gene expressions. Finally, VC and insulin down-regulatory effects were observed on extracellular and intracellular reactive oxygen species production respectively. In summary, this experimental assay describes a specific effect of VC in isolated rat adipocytes on glucose and fat metabolism, and on the secretion/expression of important obesity-related proteins.

High fat diet-induced obesity modifies the methylation pattern of leptin promoter in rats.

Leptin is an adipokine involved in body weight and food intake regulation whose promoter region presents CpG islands that could be subject to dynamic methylation. This methylation process could be affected by environmental (e.g. diet) or endogenous (e.g., adipocyte differentiation, inflammation, hypoxia) factors, and could influence adipocyte leptin gene expression. The aim of this article was to study whether a high-energy diet may affect leptin gene promoter methylation in rats. A group of eleven male Wistar rats were assigned into two dietary groups, one fed on a control diet for 11 weeks and the other on a high-fat cafeteria diet. Rats fed a high-energy diet become overweight and hyperleptinemic as compared to the controls. DNA isolated from retroperitoneal adipocytes was treated with bisulfite and a distal portion of leptin promoter (from -694 to -372 bp) including 13 CpG sites was amplified by PCR and sequenced. The studied promoter portion was slightly more methylated in the cafeteria-fed animals, which was statistically significant (p < 0.05) for one of the CpG sites (located at the position -443). In obese rats, such methylation was associated to lower circulating leptin levels, suggesting that this position could be important in the regulation of leptin gene expression, probably by being a target sequence of different transcription factors. Our findings reveal, for the first time, that leptin methylation pattern can be influenced by diet-induced obesity, and suggest that epigenetic mechanisms could be involved in obesity by regulating the expression of important epiobesigenic genes.

La obesidad inducida por dieta alta en grasas modifica el patrón de metilación del promotor de la leptina en la rata / High fat diet-induced obesity modifies the methylation pattern of leptin promoter in rats

Leptin is an adipokine involved in body weight and food intake regulation whosepromoter region presents CpG islands that could be subject to dynamic methylation.This methylation process could be affected by environmental (e.g. diet) or endogenous(e.g., adipocyte differentiation, inflammation, hypoxia) factors, and could influenceadipocyte leptin gene expression. The aim of this article was to study whether ahigh-energy diet may affect leptin gene promoter methylation in rats. A group ofeleven male Wistar rats were assigned into two dietary groups, one fed on a controldiet for 11 weeks and the other on a high-fat cafeteria diet. Rats fed a high-energy dietbecome overweight and hyperleptinemic as compared to the controls. DNA isolatedfrom retroperitoneal adipocytes was treated with bisulfite and a distal portion of leptinpromoter (from -694 to -372 bp) including 13 CpG sites was amplified by PCRand sequenced. The studied promoter portion was slightly more methylated in thecafeteria-fed animals, which was statistically significant (p<0.05) for one of the CpGsites (located at the position –443). In obese rats, such methylation was associated tolower circulating leptin levels, suggesting that this position could be important in theregulation of leptin gene expression, probably by being a target sequence of differenttranscription factors. Our findings reveal, for the first time, that leptin methylationpattern can be influenced by diet-induced obesity, and suggest that epigenetic mechanismscould be involved in obesity by regulating the expression of important epiobesigenicgenes(AU)

La leptina es una adipoquina implicada en laregulación del peso corporal y la ingesta energéticacuya región promotora presenta islasCpG que podrían ser metiladas dinámicamente.Este proceso de metilación podría verseafectado por factores ambientales, como ladieta, o endógenos, como la diferenciación adipocitaria,inflamación o hipoxia, y podríainfluir en la expresión de leptina por parte delos adipocitos. El objetivo de este artículo esestudiar si una dieta alta en grasa podría afectara la metilación del promotor de la leptina enratas. Un grupo de once ratas Wistar machofue dividido en dos subgrupos, uno alimentadocon dieta control durante 11 semanas y el otrocon dieta alta en grasa (dieta de cafetería). Lasratas alimentadas con la dieta rica en grasa presentaronsobrepeso e hiperleptinemia. El ADNaislado de los adipocitos retroperitoneales fuetratado con bisulfito y una porción distal delpromotor de la leptina (de la base -694 a la -372), conteniendo 13 sitios CpG, fue amplificadapor PCR y secuenciada. Esta región delpromotor apareció ligeramente más metiladaen los animales alimentados con dieta de cafetería,lo cuál fue especialmente significativo (p<0,05) para uno de los sitios CpG (en la posición-443). En las ratas obesas, la metilación seasoció a una disminución de los niveles de leptinacirculante, lo que sugiere que esta posiciónpodría ser importante en la regulación de laexpresión génica de esta adipoquina, probablementepor ser una secuencia diana de diferen-tes factores de transcripción. Nuestros resultados,por primera vez, ponen de manifiesto queel patrón de metilación del promotor de la leptinapuede estar influido por la obesidad inducidapor la dieta, y sugieren que los mecanismosepigenéticos podrían estar implicados enla reciente pandemia de obesidad mediante laregulación de la expresión de importantesgenes epiobesigénicos(AU)

Ascorbic acid oral treatment modifies lipolytic response and behavioural activity but not glucocorticoid metabolism in cafeteria diet-fed rats.

AIM: To analyse the effects of vitamin C (VC), a potent dietary antioxidant, oral supplementation on body weight gain, behavioural activity, lipolytic response and glucocorticoid metabolism in the early stages of diet-induced overweight in rats. METHODS: Food intake, locomotive activity and faecal corticosterone were assessed during the 14 day trial period. After 2 weeks, the animals were sacrificed and the body composition, biochemical markers and lipolytic response from isolated adipocytes from retroperitoneal white adipose tissue were examined. RESULTS: The intake of a high-fat diet by rats induced a significant increase in body weight, adiposity and insulin resistance markers as well as a decrease in faecal corticosterone levels compared with standard diet-fed rats. Interestingly, the animals fed on the cafeteria diet showed a significant increase in the isoproterenol-induced lipolytic response in isolated adipocytes. Furthermore, this cafeteria-fed group showed a reduced locomotive behaviour than the control rats. On the other hand, oral VC supplementation in animals receiving the high-fat diet restored the cafeteria diet effect in some of the analysed variables such as final body weight and plasma insulin to control group levels. Remarkably, increases in locomotive behaviour and a significant decrease in the lipolytic response induced by isoproterenol on isolated adipocytes from animals treated with VC were observed. CONCLUSION: This work demonstrates that an oral ascorbic acid supplementation has direct effects on behavioural activity and on adipocyte lipolysis in early obesity stages in rats, which could indicate a protective short-term role of this vitamin against adiposity induced by chronic high-fat diet consumption.

A high-sucrose isocaloric pair-fed model induces obesity and impairs NDUFB6 gene function in rat adipose tissue.

BACKGROUND/AIM: Changes in dietary macronutrient content are involved in altered energy metabolism and obesity development. However, there are controversial views about the obesogenic effects of high-sucrose (HS) diets, which usually lead to obesity and insulin resistance but are sometimes associated with reduced weight gain. The aim of this study was to investigate the effect of consumption of a pair-fed HS diet on weight gain and energy homeostasis in rats, as well as to assess the effects on expression of the NADH dehydrogenase (ubiquinone) 1beta subcomplex 6 (NDUFB6) gene in adipose tissue. METHODS/RESULTS: Although both dietary groups, i.e. HS and control, were pair-fed (isoenergetic feeding), the HS diet increased adiposity and decreased plasma total and high-density lipoprotein cholesterol levels. While no significant differences were found with regard to serum glucose, insulin, adiponectin, free fatty acids and liver malondialdehyde, a slight increase in serum and liver triglycerides was observed. Interestingly, the gene expression of NDUFB6, an inner mitochondrial membrane protein involved in mitochondrial electron transport, was reduced in epididymal adipose tissue when compared to the control-fed group. CONCLUSION: These results suggest, apparently for the first time, that high-sugar diets appear to induce mitochondrial dysfunction in adipose tissue, which may be related to greater weight gain and metabolic impairment.

Influence of dietary macronutrient composition on adiposity and cellularity of different fat depots in Wistar rats.

The aim of this study was to investigate the role of dietary macronutrient content on adiposity parameters and adipocyte hypertrophy/hyperplasia in subcutaneous and visceral fat depots from Wistar rats using combined histological and computational approaches. For this purpose, male Wistar rats were distributed into 4 groups and were assigned to different nutritional interventions: Control group (chow diet); high-fat group, HF (60% E from fat); high-fat-sucrose group, HFS (45% E from fat and 17% from sucrose); and high-sucrose group, HS (42% E from sucrose). At day 35, rats were sacrificed, blood was collected, tissues were weighed and fragments of different fat depots were kept for histological analyses with the new softwareAdiposoft. Rats fed with HF, HFS and HS diets increased significantly body weight and total body fat against Control rats, being metabolic impairments more pronounced on HS rats than in the other groups. Cellularity analyses usingAdiposoft revealed that retroperitoneal adipose tissue is histologically different than mesenteric and subcutaneous ones, in relation to bigger adipocytes. The subcutaneous fat pad was the most sensitive to the diet, presenting adipocyte hypertrophy induced by HF diet and adipocyte hyperplasia induced by HS diet. The mesenteric fat pad had a similar but attenuated response in comparison to the subcutaneous adipose tissue, while retroperitoneal fat pad only presented adipocyte hyperplasia induced by the HS diet intake after 35 days of intervention. These findings provide new insights into the role of macronutrients in the development of hyperplastic obesity, which is characterized by the severity of the clinical features. Finally, a new tool for analyzing histological adipose samples is presented.

Chronic mild stress induces variations in locomotive behavior and metabolic rates in high fat fed rats

Chronic mild stress (CMS) has been often associated to the pathogenesis of manydiseases including obesity. Indeed, visceral obesity has been linked to the developmentof metabolic syndrome features and constitutes a serious risk factor for cardiovasculardiseases and diabetes. In order to study possible mechanistic relationshipsbetween stress and the onset of obesity, we developed during 11 weeks a model ofhigh-fat dietary intake (cafeteria diet) together with a CMS regimen in male Wistarrats. During the experimental period, basal metabolism by indirect calorimetry, rectaltemperature, food intake, and locomotive markers were specifically analyzed.After 77 days, animals were sacrificed and body, adiposity and plasma biochemicalprofiles were also examined. As expected, cafeteria diet in unstressed animals induceda significative increase in body weight, adiposity, and insulin resistance markers.Locomotive variables, specifically distance, rearing and meander, were significantlyincreased by CMS on the first weeks of stress. Moreover, this model of CMS in Wistarrats increased significantly energy expenditure, and apparently interplayed withthe dietary treatment on the muscle weight/fat weight ratio. In summary, this chronicstress model did not affected weight gain in control and high fat fed animals, butinduced an interaction concerning the metabolic muscle/fat repartitioning (AU)

No disponible

Chronic mild stress induces variations in locomotivebehavior and metabolic rates in high fat fed rats

Chronic mild stress (CMS) has been often associated to the pathogenesis of manydiseases including obesity. Indeed, visceral obesity has been linked to the developmentof metabolic syndrome features and constitutes a serious risk factor for cardiovasculardiseases and diabetes. In order to study possible mechanistic relationshipsbetween stress and the onset of obesity, we developed during 11 weeks a model ofhigh-fat dietary intake (cafeteria diet) together with a CMS regimen in male Wistarrats. During the experimental period, basal metabolism by indirect calorimetry, rectaltemperature, food intake, and locomotive markers were specifically analyzed.After 77 days, animals were sacrificed and body, adiposity and plasma biochemicalprofiles were also examined. As expected, cafeteria diet in unstressed animals induceda significative increase in body weight, adiposity, and insulin resistance markers.Locomotive variables, specifically distance, rearing and meander, were significantlyincreased by CMS on the first weeks of stress. Moreover, this model of CMS in Wistarrats increased significantly energy expenditure, and apparently interplayed withthe dietary treatment on the muscle weight/fat weight ratio. In summary, this chronicstress model did not affected weight gain in control and high fat fed animals, butinduced an interaction concerning the metabolic muscle/fat repartitioning (AU)

No disponible

Chronic mild stress induces variations in locomotive behavior and metabolic rates in high fat fed rats.

Chronic mild stress (CMS) has been often associated to the pathogenesis of many diseases including obesity. Indeed, visceral obesity has been linked to the development of metabolic syndrome features and constitutes a serious risk factor for cardiovascular diseases and diabetes. In order to study possible mechanistic relationships between stress and the onset of obesity, we developed during 11 weeks a model of high-fat dietary intake (cafeteria diet) together with a CMS regimen in male Wistar rats. During the experimental period, basal metabolism by indirect calorimetry, rectal temperature, food intake, and locomotive markers were specifically analyzed. After 77 days, animals were sacrificed and body, adiposity and plasma biochemical profiles were also examined. As expected, cafeteria diet in unstressed animals induced a significative increase in body weight, adiposity, and insulin resistance markers. Locomotive variables, specifically distance, rearing and meander, were significantly increased by CMS on the first weeks of stress. Moreover, this model of CMS in Wistar rats increased significantly energy expenditure, and apparently interplayed with the dietary treatment on the muscle weight/fat weight ratio. In summary, this chronic stress model did not affected weight gain in control and high fat fed animals, but induced an interaction concerning the metabolic muscle/fat repartitioning.