Mitofusin-2 induced by exercise modifies lipid droplet-mitochondria communication, promoting fatty acid oxidation in male mice with NAFLD.

BACKGROUND AND AIM: The excessive accumulation of lipid droplets (LDs) is a defining characteristic of nonalcoholic fatty liver disease (NAFLD). The interaction between LDs and mitochondria is functionally important for lipid metabolism homeostasis. Exercise improves NAFLD, but it is not known if it has an effect on hepatic LD-mitochondria interactions. Here, we investigated the influence of exercise on LD-mitochondria interactions and its significance in the context of NAFLD. APPROACH AND RESULTS: Mice were fed high-fat diet (HFD) or HFD-0.1 % methionine and choline-deficient diet (MCD) to emulate simple hepatic steatosis or non-alcoholic steatohepatitis, respectively. In both models, aerobic exercise decreased the size of LDs bound to mitochondria and the number of LD-mitochondria contacts. Analysis showed that the effects of exercise on HOMA-IR and liver triglyceride levels were independent of changes in body weight, and a positive correlation was observed between the number of LD-mitochondria contacts and NAFLD severity and with the lipid droplet size bound to mitochondria. Cellular fractionation studies revealed that ATP-coupled respiration and fatty acid oxidation (FAO) were greater in hepatic peridroplet mitochondria (PDM) from HFD-fed exercised mice than from equivalent sedentary mice. Finally, exercise increased FAO and mitofusin-2 abundance exclusively in PDM through a mechanism involving the curvature of mitochondrial membranes and the abundance of saturated lipids. Accordingly, hepatic mitofusin-2 ablation prevented exercise-induced FAO in PDM. CONCLUSIONS: This study demonstrates that aerobic exercise has beneficial effects in murine NAFLD models by lessening the interactions between hepatic LDs and mitochondria, and by decreasing LD size, correlating with a reduced severity of NAFLD. Additionally, aerobic exercise increases FAO in PDM and this process is reliant on Mfn-2 enrichment, which modifies LD-mitochondria communication.

The interplay between leptin, glucocorticoids, and GLP1 regulates food intake and feeding behaviour.

Nutritional, endocrine, and neurological signals converge in multiple brain centres to control feeding behaviour and food intake as part of the allostatic regulation of energy balance. Among the several neuroendocrine systems involved, the leptin, glucocorticoid, and glucagon-like peptide 1 (GLP1) systems have been extensively researched. Leptin is at the top hierarchical level since its complete absence is sufficient to trigger severe hyperphagia. Glucocorticoids are key regulators of the energy balance adaptation to stress and their sustained excess leads to excessive adiposity and metabolic perturbations. GLP1 participates in metabolic adaptation to food intake, regulating insulin secretion and satiety by parallel central and peripheral signalling systems. Herein, we review the brain and peripheral targets of these three hormone systems that integrate to regulate food intake, feeding behaviour, and metabolic homeostasis. We examine the functional relationships between leptin, glucocorticoids, and GLP1 at the central and peripheral levels, including the cross-regulation of their circulating levels and their cooperative or antagonistic actions at different brain centres. The pathophysiological roles of these neuroendocrine systems in dysregulated intake are explored in the two extremes of body adiposity - obesity and lipodystrophy - and eating behaviour disorders.

Corrigendum: Impact of short and long exposure to cafeteria diet on food intake and white adipose tissue lipolysis mediated by glucagon-like peptide 1 receptor.

[This corrects the article DOI: 10.3389/fendo.2023.1164047.].

Impact of short and long exposure to cafeteria diet on food intake and white adipose tissue lipolysis mediated by glucagon-like peptide 1 receptor.

Introduction: The modern food environment facilitates excessive calorie intake, a major driver of obesity. Glucagon-like peptide 1 (GLP1) is a neuroendocrine peptide that has been the basis for developing new pharmacotherapies against obesity. The GLP1 receptor (GLP1R) is expressed in central and peripheral tissues, and activation of GLP1R reduces food intake, increases the expression of thermogenic proteins in brown adipose tissue (BAT), and enhances lipolysis in white adipose tissue (WAT). Obesity decreases the efficiency of GLP1R agonists in reducing food intake and body weight. Still, whether palatable food intake before or during the early development of obesity reduces the effects of GLP1R agonists on food intake and adipose tissue metabolism remains undetermined. Further, whether GLP1R expressed in WAT contributes to these effects is unclear. Methods: Food intake, expression of thermogenic BAT proteins, and WAT lipolysis were measured after central or peripheral administration of Exendin-4 (EX4), a GLP1R agonist, to mice under intermittent-short exposure to CAF diet (3 h/d for 8 days) or a longer-continuous exposure to CAF diet (24 h/d for 15 days). Ex-vivo lipolysis was measured after EX4 exposure to WAT samples from mice fed CAF or control diet for 12 weeks. . Results: During intermittent-short exposure to CAF diet (3 h/d for 8 days), third ventricle injection (ICV) and intra-peritoneal administration of EX4 reduced palatable food intake. Yet, during a longer-continuous exposure to CAF diet (24 h/d for 15 days), only ICV EX4 administration reduced food intake and body weight. However, this exposure to CAF diet blocked the increase in uncoupling protein 1 (UCP1) caused by ICV EX4 administration in mice fed control diet. Finally, GLP1R expression in WAT was minimal, and EX4 failed to increase lipolysis ex-vivo in WAT tissue samples from mice fed CAF or control diet for 12 weeks. . Discussion: Exposure to a CAF diet during the early stages of obesity reduces the effects of peripheral and central GLP1R agonists, and WAT does not express a functional GLP1 receptor. These data support that exposure to the obesogenic food environment, without the development or manifestation of obesity, can alter the response to GLP1R agonists. .

Spheroids derived from the stromal vascular fraction of adipose tissue self-organize in complex adipose organoids and secrete leptin.

BACKGROUND: Adipose tissue-derived stromal vascular fraction (SVF) harbors multipotent cells with potential therapeutic relevance. We developed a method to form adipose spheroids (AS) from the SVF with complex organoid structure and enhanced leptin secretion upon insulin stimulation. METHODS: SVF was generated from the interscapular brown adipose tissue of newborn mice. Immunophenotype and stemness of cultured SVF were determined by flow cytometry and in vitro differentiation, respectively. Spheroids were generated in hanging drops and non-adherent plates and compared by morphometric methods. The adipogenic potential was compared between preadipocyte monolayers and spheroids. Extracellular leptin was quantified by immunoassay. Lipolysis was stimulated with isoprenaline and quantified by colorimetric methods. AS viability and ultrastructure were determined by confocal and transmission electron microscopy analyses. RESULTS: Cultured SVF contained Sca1 + CD29 + CD44 + CD11b- CD45- CD90- cells with adipogenic and chondrogenic but no osteogenic potential. Culture on non-adherent plates yielded the highest quantity and biggest size of spheroids. Differentiation of AS for 15 days in a culture medium supplemented with insulin and rosiglitazone resulted in greater Pparg, Plin1, and Lep expression compared to differentiated adipocytes monolayers. AS were viable and maintained leptin secretion even in the absence of adipogenic stimulation. Glycerol release after isoprenaline stimulation was higher in AS compared to adipocytes in monolayers. AS were composed of outer layers of unilocular mature adipocytes and an inner structure composed of preadipocytes, immature adipocytes and an abundant loose extracellular matrix. CONCLUSION: Newborn mice adipose SVF can be efficiently differentiated into leptin-secreting AS. Prolonged stimulation with insulin and rosiglitazone allows the formation of structurally complex adipose organoids able to respond to adrenergic lipolytic stimulation.

Decreased caveolae in AGPAT2 lacking adipocytes is independent of changes in cholesterol or sphingolipid levels: A whole cell and plasma membrane lipidomic analysis of adipogenesis.

BACKGROUND: Adipocytes from lipodystrophic Agpat2-/- mice have impaired adipogenesis and fewer caveolae. Herein, we examined whether these defects are associated with changes in lipid composition or abnormal levels of caveolae-associated proteins. Lipidome changes were quantified in differentiated Agpat2-/- adipocytes to identify lipids with potential adipogenic roles. METHODS: Agpat2-/- and wild type brown preadipocytes were differentiated in vitro. Plasma membrane was purified by ultracentrifugation. Number of caveolae and caveolae-associated proteins, as well as sterol, sphingolipid, and phospholipid lipidome were determined across differentiation. RESULTS: Differentiated Agpat2-/- adipocytes had decreased caveolae number but conserved insulin signaling. Caveolin-1 and cavin-1 levels were equivalent between Agpat2-/- and wild type adipocytes. No differences in PM cholesterol and sphingolipids abundance were detected between genotypes. Levels of phosphatidylserine at day 10 of differentiation were increased in Agpat2-/- adipocytes. Wild type adipocytes had increased whole cell triglyceride, diacylglycerol, phosphatidylglycerol, phosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine, and trihexosyl ceramide, and decreased 24,25-dihydrolanosterol and sitosterol, as a result of adipogenic differentiation. By contrast, adipogenesis did not modify whole cell neutral lipids but increased lysophosphatidylcholine, sphingomyelin, and trihexosyl ceramide levels in Agpat2-/- adipocytes. Unexpectedly, adipogenesis decreased PM levels of main phospholipids in both genotypes. CONCLUSION: In Agpat2-/- adipocytes, decreased caveolae is not associated with changes in PM cholesterol nor sphingolipid levels; however, increased PM phosphatidylserine content may be implicated. Abnormal lipid composition is associated with the adipogenic abnormalities of Agpat2 -/- adipocytes but does not prevent insulin signaling.

Eating behaviour in contrasting adiposity phenotypes: Monogenic obesity and congenital generalized lipodystrophy.

Most known types of nonsyndromic monogenic obesity are caused by rare mutations in genes of the leptin-melanocortin pathway controlling appetite and adiposity. In contrast, congenital generalized lipodystrophy represents the most extreme form of leanness in humans caused by recessive mutations in four genes involved in phospholipid/triglyceride synthesis and lipid droplet/caveolae structure. In this disease, the inability to store triglyceride in adipocytes results in hypoleptinemia and ectopic hepatic and muscle fat accumulation leading to fatty liver, hypertriglyceridemia and severe insulin resistance. As a result of hypoleptinemia, patients with lipodystrophy show alterations in eating behaviour characterized by constant increased energy intake. As it occurs in obesity caused by genetic leptin deficiency, exogenous leptin rapidly reduces hunger scores in patients with congenital generalized lipodystrophy, with additional beneficial effects on glucose homeostasis and metabolic profile normalization. The melanocortin-4 receptor agonist setmelanotide has been used in the treatment of monogenic obesities. There is only one report on the effect of setmelanotide in a patient with partial lipodystrophy resulting in mild reductions in hunger scores, with no improvements in metabolic status. The assessment of contrasting phenotypes of obesity/leanness represents an adequate strategy to understand the pathophysiology and altered eating behaviour associated with adipose tissue excessive accumulation/paucity.

Toxicological, enzymatic, and immunochemical characterization of Bothrops asper (Serpentes: Viperidae) reference venom from Panama / Caracterización toxicológica, enzimática e inmunoquímica del veneno de referencia de Bothrops asper (Serpentes: Viperidae) de Panamá

Introduction: It is estimated that 2 000 snakebites occur in Panama every year, 70 % of which are inflicted by Bothrops asper. Objective: To determine the biochemical and toxicologic effects and to assess the immunochemical characteristics of a reference pool of B. asper venom representative of Panama. Methods: The reference venom was prepared as a homogeneous mixture of the venoms obtained from 78 adult snakes collected in four geographic areas of Panama. Enzymatic and toxicological activities were assessed. The electrophoretic pattern was studied by SDS-PAGE. Immunoreactivity of various antivenoms was analyzed by Western blot. Results: B. asper reference venom has lethal, hemorrhagic, myotoxic, edema-forming, coagulant, defibrinating, proteinase and phospholipase A2 activities. SDS-PAGE showed the presence of protein bands with molecular weights ranging from 8 to 70 kDa, with the presence of predominant bands at ≈ 15 kDa and ≈ 30 to 66 kDa, which likely correspond to phospholipases A2 and metalloproteinases, respectively. Immunoblotting showed a high degree of recognition by various antivenoms, especially by antivenoms from Colombia and Costa Rica. Conclusions: Following recommendations by the World Health Organization, this reference venom of B. asper of Panama will become a useful tool for the preclinical evaluation of antivenoms distributed in this country.

Introducción: Se estima que 2 000 mordeduras de serpiente ocurren en Panamá cada año, el 70 % de las cuales son infligidas por Bothrops asper. Objetivo: Determinar los efectos bioquímicos y toxicológicos y evaluar las características inmunoquímicas del veneno de referencia de B. asper representativo de Panamá. Métodos: El veneno de referencia se preparó como una mezcla homogénea de los venenos obtenidos de 78 serpientes adultas recolectadas en cuatro áreas geográficas de Panamá. Se evaluaron las actividades enzimáticas y toxicológicas. El patrón electroforético se estudió mediante SDS-PAGE. La inmunoreactividad de varios antivenenos se analizó mediante transferencia de Western. Resultados: El veneno de referencia de B. asper tiene actividades letales, hemorrágicas, miotóxicas, formadoras de edema, coagulantes, desfibrinante, proteolítica y de fosfolipasa A2. El análisis de SDS-PAGE mostró la presencia de bandas de proteínas con pesos moleculares que varían de 8 a 70 kDa, con la presencia de bandas predominantes a ≈ 15 kDa y ≈ 30 a 66 kDa, que probablemente corresponden a fosfolipasas A2 y metaloproteinasas, respectivamente. La inmunotransferencia mostró un alto grado de reconocimiento por varios antivenenos, especialmente por antivenenos de Colombia y de Costa Rica. Conclusiones: Siguiendo las recomendaciones de la Organización Mundial de la Salud, este veneno de referencia de B. asper de Panamá se convertirá en una herramienta útil para la evaluación preclínica de antivenenos distribuidos en este país.

Hipertensión portal secundario a trombosis de la vena porta y várices esofágicas / Secondary portal hypertension to portal venous thrombosis and esophageal varices

Resumen La hipertensión portal se define como la alteración patológica en el gradiente de presión a nivel del sistema portal, es decir, la diferencia entre la presión de la vena porta y la vena cava inferior. El valor normal es entre 1-5 mm Hg y se considera hipertensión cuando es mayor de 10 mm Hg. En este artículo, se describe el caso de una paciente de 5 años con un cuadro de hipertensión portal secundario a várices esofágicas y trombosis de la vena porta, confirmado por endoscopia de vías digestivas alta y angioresonancia magnética. La paciente fue atendida en la Fundación Clínica Infantil Club Noel de la ciudad de Cali, Colombia, entre los meses de diciembre del 2018 y febrero del 2019.

Abstract Portal hypertension is defined as the pathological increase in the portal pressure gradient, which is the difference between the pressure of the portal vein and the inferior vena cava. Normally portal vein pressure ranges between 1-5 mmHg and is considered hypertension when it is higher than 10 mmHg. In this study the case of a 5-year-old patient that suffers from secondary portal hypertension to portal venous thrombosis and esophageal varices is presented. The diagnostic is confirmed by an endoscopy of the upper gastrointestinal tract and by a magnetic angioresonance. The patient was treated at the Fundacion Clinica Infantil Club Noel located in Cali, Colombia, between the months of December 2018 and February 2019.

Pathophysiological connections between gallstone disease, insulin resistance, and obesity.

Obesity and cholesterol gallstone disease (GSD) are frequently coexisting diseases; therefore and considering the current worldwide obesity epidemics, a precise understanding of the pathophysiological relationships between GSD and insulin resistance (IR) is important. Classically, obesity has been understood as a risk factor for GSD and the gallbladder (GB) viewed as a simple bile reservoir, with no metabolic roles whatsoever. However, consistent evidence has showed that both GSD and cholecystectomy associates with fatty liver and IR, raising the possibility that the GB is indeed an organ with metabolic regulatory roles. Herein, we review the pathophysiological mechanisms by which GSD, IR, and obesity are interconnected, with emphasis in the actions of the GB as a regulator of bile acids kinetics and a hormone secreting organ, with metabolic actions at the systemic level. We also examine the relationships between increased hepatic lipogenic in IR states and GSD pathogenesis. We propose a model in which GSD and hepatic IR mutually interact to determine a state of dysregulated lipid and energy metabolism that potentiate the metabolic dysregulation of obesity.

Lipodistrofias primarias: presentación clínica y diagnóstico / Clinical presentation and treatment of primary lipodystrophies

Lipodystrophies are a heterogeneous group of syndromes defined by a severe reduction of the adipose tissue. These can be congenital or acquired. Anatomically, they can be partial or generalized. The etiology of several lipodystrophies is well known. However, the cause of many others remains unknown. The commonest lipodystrophy worldwide is secondary to highly active anti-retroviral therapy in HIV-infected patients. By contrast, primary lipodystrophies (those not associated to any known disease or condition) are much less common and represent a diagnostic challenge. The major complications of lipodystrophies are metabolic, often resulting in severe insulin resistance, diabetes and dyslipidemia. No cure is available for lipodystrophies but the supplementation with recombinant leptin potently controls the metabolic abnormalities when there is a leptin deficiency. Herein, we review the clinical presentation, diagnostic process and therapeutic principles of the main primary lipodystrophy syndromes.

Insulin increases cholesterol uptake, lipid droplet content, and apolipoprotein B secretion in CaCo-2 cells by upregulating SR-BI via a PI3K, AKT, and mTOR-dependent pathway.

The actions of insulin on intestinal cholesterol absorption and lipoprotein secretion are not well understood. Herein, we determined the effects of insulin on the levels of cholesterol transporter scavenger receptor, class B, type I (SR-BI), cellular cholesterol uptake, intracellular lipid accumulation, and lipoprotein secretion in a cellular model of human intestinal epithelium. METHODS: CaCo-2 cells were cultured to postconfluency in Transwell filters and stimulated with glucose (25 mM) in the presence or absence of insulin (100 nM) at their basolateral surface. SR-BI mRNA and protein levels were quantified by quantitative reverse transcription-PCR and immunoblot, respectively. Polarized localization of SR-BI was determined by cell surface proteins biotinylation and streptavidin precipitation. Activities of PI3K, AKT, mTOR, and SR-BI were pharmacologically antagonized. Cholesterol uptake was assessed by NBD-cholesterol incorporation. Apolipoprotein (apo) B concentration was quantified by ELISA. Subcellular localization of neutral lipids (BODIPY) and SR-BI (immunofluorescence) was determined by confocal microscopy. RESULTS: In polarized CaCo-2 cells, insulin increased SR-BI at the mRNA and protein levels. SR-BI was exclusively present at apical cell surface, as indicated by biotinylation and confocal microscopy analysis. Glucose did not modify SR-BI abundance or subcellular localization. Effects of insulin on SR-BI levels were abrogated by PI3K, AKT, or mTOR pharmacological antagonism. Cholesterol uptake, neutral lipid abundance, and apo B secretion were increased by insulin in CaCo-2 cells, and these effects were prevented by SR-BI pharmacological antagonism with block lipid transport-1. CONCLUSIONS: insulin promotes cholesterol uptake, intracellular lipid store, and apo B-containing lipoproteins secretion by SR-BI-dependent mechanisms in a model of human intestinal epithelium.

[Clinical presentation and treatment of primary lipodystrophies]. / Lipodistrofias primarias: presentación clínica y diagnóstico.

Lipodystrophies are a heterogeneous group of syndromes defined by a severe reduction of the adipose tissue. These can be congenital or acquired. Anatomically, they can be partial or generalized. The etiology of several lipodystrophies is well known. However, the cause of many others remains unknown. The commonest lipodystrophy worldwide is secondary to highly active anti-retroviral therapy in HIV-infected patients. By contrast, primary lipodystrophies (those not associated to any known disease or condition) are much less common and represent a diagnostic challenge. The major complications of lipodystrophies are metabolic, often resulting in severe insulin resistance, diabetes and dyslipidemia. No cure is available for lipodystrophies but the supplementation with recombinant leptin potently controls the metabolic abnormalities when there is a leptin deficiency. Herein, we review the clinical presentation, diagnostic process and therapeutic principles of the main primary lipodystrophy syndromes.

Periodontal inflammation correlates with systemic inflammation and insulin resistance in patients with recent diagnosis of type 2 diabetes / La inflamación periodontal se correlaciona con la inflamación sistémica y la insulina. resistencia en pacientes con diagnóstico reciente de diabetes tipo 2

Background: diabetes and periodontitis are common comorbidities; however, the clinical implications of this association remain only partially known. This study was aimed to characterize the periodontal status of type 2 diabetic (T2D) patients and its correlation with metabolic and inflammatory parameters. Methods: patients (n = 30) with 5 or less years since the diagnosis of T2D (18 ­ 65 years old) were recruited. Anthropometric (Body Mass Index, BMI), metabolic (fasting glucose, glycated hemoglobin, insulin, HOMA-IR, HDL, LDL and total cholesterol, triglycerides) and inflammatory parameters (ultrasensitive C reactive protein, usCRP) were quantified. Periodontal evaluation included clinical attachment level (CAL), probing depth (PD), gingival level (GL) and bleeding on probing (BOP) average. Statistical significance was assessed by Mann-Whitney and Spearman correlation tests. Results: mean values of BOP, CAL, PD and GL were 39.3, 2.8, 2.8, and 0.1, respectively. BOP significantly correlated with BMI and HOMA-IR and was higher in patients with elevated usCRP >3 mg/L (p<0.05). Age and duration of T2D directly and inversely correlated with CAL and GL, respectively. BOP correlated with HOMA-IR and usCRP but not with patients´age, duration of T2D or BMI. Conclusions: in patients with recent diagnosis of T2D, BOP is associated with usCRP and HOMA-IR levels, suggesting that periodontal inflammation promotes insulin resistance possibly by increasing systemic inflammation. (AU)

Antecedentes: la diabetes y la periodontitis son comorbilidades comunes; sin embargo, las implicaciones clínicas de esta asociación siguen siendo solo parcialmente conocidas. El objetivo de este estudio fue caracterizar el estado periodontal de los pacientes con diabetes tipo 2 (T2D) y su correlación con los parámetros metabólicos e inflamatorios. Métodos: se reclutaron pacientes (n = 30) con 5 años o menos desde el diagnóstico de DM2 (18-65 años). Se cuantificaron parámetros antropométricos (índice de masa corporal, IMC), metabólicos (glucosa en ayunas, hemoglobina glucosilada, insulina, HOMA-IR, HDL, LDL y colesterol total, triglicéridos) y parámetros inflamatorios (proteína reactiva C ultrasensible, usCRP). La evaluación periodontal incluyó el nivel de inserción clínica (CAL), la profundidad de sondaje (PD), el nivel gingival (GL) y el promedio de sangrado al sondaje (BOP). La significación estadística se evaluó mediante pruebas de correlación de Mann-Whitney y Spearman. Resultados: los valores medios de BOP, CAL, PD y GL fueron 39.3, 2.8, 2.8 y 0.1, respectivamente. La BOP se correlacionó significativamente con el IMC y el HOMA-IR y fue mayor en pacientes con una usCRP elevada> 3 mg / L (p <0.05). La edad y la duración de T2D se correlacionaron directa e inversamente con CAL y GL, respectivamente. La BOP se correlacionó con HOMA-IR y usCRP pero no con la edad de los pacientes, la duración de T2D o IMC. Conclusiones: en pacientes con diagnóstico reciente de T2D, la BOP está asociada con los niveles de usCRP y HOMA-IR, lo que sugiere que la inflamación periodontal promueve la resistencia a la insulina posiblemente al aumentar la inflamación sistémica. (AU)

Abdominal obesity is a common finding in normal and overweight subjects of Chile and is associated with increased frequency of cardiometabolic risk factors.

BACKGROUND/OBJECTIVES: Abdominal obesity (AO) is associated with elevated risk for cardiovascular diseases; however, this association is less clear for non-obese people. We estimated the association of AO and cardiovascular risk factors (CVRF) and disease in non-obese adult individuals from Chile. SUBJECTS/METHODS: 5248 adults (15 years of age or older) of both sexes from the Chilean National Health Survey (October 2009 -September 2010, response rate 85%.) were included. Information on myocardial infarction and stroke was self-reported. BMI, waist circumference (WC), arterial pressure, plasma glucose, and cholesterol levels were measured. Predictive accuracy of WC was evaluated by area under curve of receiver operating characteristic analysis and cut off points were established by Youden Index. Relationship between AO and CVRF was analyzed by Chi-squared tests. RESULTS: Normal weight/overweight/obesity were present in 34.4%/45.2%/18.1% of men and 33.4%/33.6%/27.5% of women. Predictive accuracy of WC to identify at least one CVRF was 0.70/0.67 and optimal cutoff points for WC in non-obese subjects were 91/83 cm in men/women, respectively. AO was present in 98.2%/99.1% of obese, 70.5%/77.4% of overweight and 12.4%/16.4% of normal weight men/women. AO was associated with increased frequency of CVRF in overweight men (6/8 and stroke) and women (4/8) and higher frequency in normal weight men (8/8 and myocardial infarction/stroke) and women (6/8 and myocardial infarction). CONCLUSIONS: WC cutoff points calculated for non-obese chilean population discriminate more differences in CVRF in normal weight woman. AO significantly increases the frequency of CVRF and diseases in overweight and especially normal weight individuals. WC can be used as a low cost, feasible and reproducible predictor for CVRF in non-obese individuals in most clinical settings.

Biology and pathological implications of brown adipose tissue: promises and caveats for the control of obesity and its associated complications.

The discovery of metabolically active brown adipose tissue (BAT) in adult humans has fuelled the research of diverse aspects of this previously neglected tissue. BAT is solely present in mammals and its clearest physiological role is non-shivering thermogenesis, owing to the capacity of brown adipocytes to dissipate metabolic energy as heat. Recently, a number of other possible functions have been proposed, including direct regulation of glucose and lipid homeostasis and the secretion of a number of factors with diverse regulatory actions. Herein, we review recent advances in general biological knowledge of BAT and discuss the possible implications of this tissue in human metabolic health. In particular, we confront the claimed thermogenic potential of BAT for human energy balance and body mass regulation, mostly based on animal studies, with the most recent quantifications of human BAT.

Effect of cholecystectomy on hepatic fat accumulation and insulin resistance in non-obese Hispanic patients: a pilot study.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is highly prevalent worldwide. Experimental studies have shown that cholecystectomy (XGB) increases hepatic fat content in mice and appears associated to NAFLD in large retrospective population-based studies. The aim of this study was to prospectively assess the effects of XGB on hepatic fat content (HFC) and insulin resistance (IR) in non-obese, middle aged Hispanic subjects. METHODS: Twenty-six gallstone patients undergoing elective XGB and 16 control subjects with normal livers and gallbladders at ultrasonography were prospectively followed 24 months for changes in HFC and IR. Clinical, biochemical determinations and hepatic imaging were performed at baseline and 24 months after surgery. MRI technique quantified HFC in four hepatic segments. IR was assessed by the Homeostasis Model Assessment (HOMA-IR) index. RESULTS: Initial body mass index (BMI) was 25.6 ± 0.4 and 24.3 ± 1.0 in the control and XGB groups of subjects, respectively. Serum insulin level increased from 8.1 ± 0.7 to 10.0 ± 1.9 (µU/ml) 24 months after surgery in XGB patients (p < 0.05); no significant changes were detected in control individuals. Median HOMA-IR index increased from 1.31 (interquartile range, 1.01-1.68) to 2.20 (interquartile range, 1.57 - 2.60) 24 months after XGB, (p < 0.003). Median HOMA-IR index of control subjects remained unchanged at the end of the study. Serum apoB concentration increased from 61.5 ± 3.4 to 79.0 ± 7.8 (µg/ml) in XGB patients (p < 0.03). Serum apoB levels remained within normal ranges in both periods of the study in control subjects. HFC significantly increased in 2 of the 4 segments 24 months after XGB: right posterior hepatic lobe (from 5.3 ± 0.2% to 6.0 ± 0.2%, p > 0.04) and right anterior hepatic lobe (from 5.8 ± 0.2% to 6.6 ± 0.3%, p < 0.02). The average HFC of the four hepatic segments studied slightly increased from 5.4 ± 0.2 to 5.8 ± 0.3 2 years after XGB (p < 0.03). No significant changes were found in HFC in the control subjects at the end of the study. CONCLUSIONS: Elective XGB increases HFC, HOMA-IR index and serum apoB concentration. These results support the notion that XGB is a risk factor non-alcoholic fatty liver disease and other IR - associated disease conditions.

Prolonged Activation of the Htr2b Serotonin Receptor Impairs Glucose Stimulated Insulin Secretion and Mitochondrial Function in MIN6 Cells.

AIMS: Pancreatic ß-cells synthesize and release serotonin (5 hydroxytryptamine, 5HT); however, the role of 5HT receptors on glucose stimulated insulin secretion (GSIS) and the mechanisms mediating this function is not fully understood. The aims of this study were to determine the expression profile of 5HT receptors in murine MIN6 ß-cells and to examine the effects of pharmacological activation of 5HT receptor Htr2b on GSIS and mitochondrial function. MATERIALS AND METHODS: mRNA levels of 5HT receptors in MIN6 cells were quantified by RT qPCR. GSIS was assessed in MIN6 cells in response to global serotonergic activation with 5HT and pharmacological Htr2b activation or inhibition with BW723C86 or SB204741, respectively. In response to Htr2b activation also was evaluated the mRNA and protein levels of PGC1α and PPARy by RT-qPCR and western blotting and mitochondrial function by oxygen consumption rate (OCR) and ATP cellular content. RESULTS: We found that mRNA levels of most 5HT receptors were either very low or undetectable in MIN6 cells. By contrast, Htr2b mRNA was present at moderate levels in these cells. Preincubation (6 h) of MIN6 cells with 5HT or BW723C86 reduced GSIS and the effect of 5HT was prevented by SB204741. Preincubation with BW723C86 increased PGC1α and PPARy mRNA and protein levels and decreased mitochondrial respiration and ATP content in MIN6 cells. CONCLUSIONS: Our results indicate that prolonged Htr2b activation in murine ß-cells decreases glucose-stimulated insulin secretion and mitochondrial activity by mechanisms likely dependent on enhanced PGC1α/PPARy expression.

AGPAT2 deficiency impairs adipogenic differentiation in primary cultured preadipocytes in a non-autophagy or apoptosis dependent mechanism.

AIMS: Mutations in 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2) result in lipodystrophy, insulin resistance and diabetes. Autophagy is required for normal adipogenesis and adipose tissue development. The aim of this study was to determine whether impaired autophagy or excessive cell death underlie the adipogenic inability of Agpat2(-/-) mice preadipocytes. METHODS: Preadipocytes were isolated from interscapular brown adipose tissue (BAT) of Agpat2(-/-) and Agpat2(+/+) newborn mice and cultured/differentiated in vitro. Intracellular lipids were quantified by oil red O staining. Cell death was assessed by lactate dehydrogenase (LDH) activity. Apoptosis and autophagy regulatory factors were determined at the mRNA and protein level with Real-time PCR, immunoblot and immunofluorescence. RESULTS: Adipogenically induced Agpat2(-/-) preadipocytes had fewer lipid-loaded cells and lower levels of adipocyte markers than wild type preadipocytes. Before adipogenic differentiation, autophagy-related proteins (ATGs) ATG3, ATG5-ATG12 complex, ATG7 and LC3II were increased but autophagic flux was reduced, as suggested by increased p62 levels, in Agpat2(-/-) preadipocytes. Adipogenic induction increased LDH levels in the culture media in Agpat2(-/-) preadipocytes but no differences were observed in the activation of Caspase 3 or in markers of autophagic flux. CONCLUSIONS: AGPAT2 is required for in vitro adipogenesis of mouse preadipocytes. Autophagy defects or apoptosis are not involved in the adipogenic failure of Agpat2(-/-) preadipocytes.

Metabolic effects of cholecystectomy: gallbladder ablation increases basal metabolic rate through G-protein coupled bile acid receptor Gpbar1-dependent mechanisms in mice.

BACKGROUND & AIMS: Bile acids (BAs) regulate energy expenditure by activating G-protein Coupled Bile Acid Receptor Gpbar1/TGR5 by cAMP-dependent mechanisms. Cholecystectomy (XGB) increases BAs recirculation rates resulting in increased tissue exposure to BAs during the light phase of the diurnal cycle in mice. We aimed to determine: 1) the effects of XGB on basal metabolic rate (BMR) and 2) the roles of TGR5 on XGB-dependent changes in BMR. METHODS: BMR was determined by indirect calorimetry in wild type and Tgr5 deficient (Tgr5-/-) male mice. Bile flow and BAs secretion rates were measured by surgical diversion of biliary duct. Biliary BAs and cholesterol were quantified by enzymatic methods. BAs serum concentration and specific composition was determined by liquid chromatography/tandem mass spectrometry. Gene expression was determined by qPCR analysis. RESULTS: XGB increased biliary BAs and cholesterol secretion rates, and elevated serum BAs concentration in wild type and Tgr5-/- mice during the light phase of the diurnal cycle. BMR was ~25% higher in cholecystectomized wild type mice (p <0.02), whereas no changes were detected in cholecystectomized Tgr5-/- mice compared to wild-type animals. CONCLUSION: XGB increases BMR by TGR5-dependent mechanisms in mice.