The adipokine chemerin augments vascular reactivity to contractile stimuli via activation of the MEK-ERK1/2 pathway

Aims: Cytokines interfere with signaling pathways and mediators of vascular contraction. Endothelin-1 (ET-1) plays a major role on vascular dysfunction in conditions characterized by increased circulating levels of adipokines. In the present study we tested the hypothesis that the adipokine chemerin increases vascular contractile responses via activation of ET-1/ET-1 receptors-mediated pathways. Main methods: Male, 10-12 week-old Wistar rats were used. Endothelium-intact and endothelium-denuded aortic rings were incubated with chemerin (0.5 ng/mL or 5 ng/mL, for 1 or 24 h), and isometric contraction was recorded. Protein expression was determined by Western blotting. Key findings: Constrictor responses to phenylephrine (PE) and ET-1 were increased in vessels treated for 1 h with chemerin. Chemerin incubation for 24 h decreased PE contractile response whereas it increased the sensitivity to ET-1. Endothelium removal significantly potentiated chemerin effects on vascular contractile responses to PE and ET-1. Incubation with either an ERK1/2 inhibitor (PD98059) or ETA antagonist (BQ123) abolished chemerin effects on PE- and ET-1-induced vasoconstriction. Phosphorylation of MEK1/2 and ERK1/2 was significantly increased in vessels treated with chemerin for 1 and 24 h. Phosphorylation of these proteins was further increased in vessels incubated with ET-1 plus chemerin. ET-1 increased MEK1/2, ERK1/2 and MKP1 protein expression to values observed in vessels treated with chemerin. Significance: Chemerin increases contractile responses to PE and ET-1 via ERK1/2 activation. Our study contributes to a better understanding of the mechanisms by which the adipose tissue affects vascular function and, consequently, the vascular alterations present in obesity and related diseases. (c) 2012 Elsevier Inc. All rights reserved.

Potencial envolvimento da adiponectina e seus receptores na modulação da esteroidogênese em corpo lúteo de cadelas ao longo do diestro

No ciclo estral de cadelas a fase luteínica, denominada diestro, compreende um período que varia de 60 a 100 dias em animais não-prenhes, caracterizado pela elevação plasmática de progesterona nos primeiros 20 dias pós ovulação (p.o). A adiponectina é a mais abundante proteína secretada pelo tecido adiposo, porém sua concentração plasmática diminui significativamente em alterações metabólicas como resistência insulínica e Diabetes mellitus tipo2, alterações descritas como relacionadas em algumas cadelas com o período de diestro. O objetivo do estudo foi determinar a expressão e imunolocalização do sistema adiponectina (adiponectina e seus receptores, adipoR1 e adipoR2) no corpo lúteo de cadelas ao longo do diestro, correlacionando-o ao perfil hormonal de 17β-estradiol e progesterona, assim como à expressão de um dos genes alvo do sistema, o PPAR-γ. Para realização do estudo foram coletados corpos lúteos de 28 cadelas durante ovariosalpingohisterectomia de eleição nos dias 10, 20, 30, 40, 50, 60 e 70 pós ovulação (o dia zero da ovulação foi considerado aquele no qual a concentração plasmática de progesterona atingiu 5ng/mL). Os corpos lúteos foram avaliados por imunohistoquímica para adiponectina e seus receptores e a expressão do RNAm do PPAR-γ por PCR em tempo real. A análise estatística da avaliação gênica foi realizada com o teste ANOVA, seguido por comparação múltipla Newman-Keuls. O sinal da adiponectina apresentou-se mais intenso até os primeiros 20 dias p.o, momento de regência da progesterona; houve queda gradativa após este período, coincidindo com a ascensão do 17β-estradiol, cujo pico foi notado próximo do dia 40 p.o. A queda marcante da adiponectina ocorreu após 50 dias p.o. O sinal do adipoR1 mostrou-se bem evidente até os 40 dias p.o e o do adipoR2 até os 50 dias p. o, decaindo posteriormente. Foi observada maior expressão do gene PPAR-γ aos 10, 30 e 70 dias p.o. Estes resultados mostram que a expressão protéica da adiponectina e de seus receptores se altera ao longo do diestro e que estas alterações podem estar relacionados às alterações hormonais e expressão do PPAR- γ, participando do mecanismo fisiológico de desenvolvimento, manutenção, atividade e regressão luteínica em cadelas.

Glutamate-induced obesity leads to decreased sperm reserves and acceleration of transit time in the epididymis of adult male rats

Background: Given the established fact that obesity interferes with male reproductive functions, the present study aimed to evaluate sperm production in the testis and storage in the epididymis in a glutamate-induced model of obesity. Methods: Male rats were treated neonatally with monosodium glutamate (MSG) at doses of 4 mg/kg subcutaneously, or with saline solution (control group), on postnatal days 2, 4, 6, 8 and 10. On day 120, obesity was confirmed by the Lee index in all MSG-treated rats. After this, all animals from the two experimental groups were anesthetized and killed to evaluate body and reproductive organ weights, sperm parameters, plasma hormone levels (FSH, LH and testosterone), testicular and epididymal histo-morphometry and histopathology. Results: Significant reductions in absolute and relative weights of testis, epididymis, prostate and seminal vesicle were noted in MSG-treated animals. In these same animals plasma testosterone and follicle-stimulating hormone (FSH) concentrations were decreased, as well as sperm counts in the testis and epididymis and seminiferous epithelium height and tubular diameter. The sperm transit time was accelerated in obese rats. However, the number of Sertoli cells per seminiferous tubule and stereological findings on the epididymis were not markedly changed by obesity. Conclusions: Neonatal MSG-administered model of obesity lowers sperm production and leads to a reduction in sperm storage in the epididymis of adult male rats. The acceleration of sperm transit time can have implications for the sperm quality of these rats.

Kinin B1 Receptor in Adipocytes Regulates Glucose Tolerance and Predisposition to Obesity

Background: Kinins participate in the pathophysiology of obesity and type 2 diabetes by mechanisms which are not fully understood. Kinin B-1 receptor knockout mice (B-1(-/-)) are leaner and exhibit improved insulin sensitivity. Methodology/Principal Findings: Here we show that kinin B-1 receptors in adipocytes play a role in controlling whole body insulin action and glucose homeostasis. Adipocytes isolated from mouse white adipose tissue (WAT) constitutively express kinin B-1 receptors. In these cells, treatment with the B-1 receptor agonist des-Arg(9)-bradykinin improved insulin signaling, GLUT4 translocation, and glucose uptake. Adipocytes from B-1(-/-) mice showed reduced GLUT4 expression and impaired glucose uptake at both basal and insulin-stimulated states. To investigate the consequences of these phenomena to whole body metabolism, we generated mice where the expression of the kinin B-1 receptor was limited to cells of the adipose tissue (aP2-B-1/B-1(-/-)). Similarly to B-1(-/-) mice, aP2-B-1/B-1(-/-) mice were leaner than wild type controls. However, exclusive expression of the kinin B1 receptor in adipose tissue completely rescued the improved systemic insulin sensitivity phenotype of B-1(-/-) mice. Adipose tissue gene expression analysis also revealed that genes involved in insulin signaling were significantly affected by the presence of the kinin B-1 receptor in adipose tissue. In agreement, GLUT4 expression and glucose uptake were increased in fat tissue of aP2-B-1/B-1(-/-) when compared to B-1(-/-) mice. When subjected to high fat diet, aP2-B-1/B-1(-/-) mice gained more weight than B-1(-/-) littermates, becoming as obese as the wild types. Conclusions/Significance: Thus, kinin B-1 receptor participates in the modulation of insulin action in adipocytes, contributing to systemic insulin sensitivity and predisposition to obesity.

Monosodium glutamate neonatal treatment induces cardiovascular autonomic function changes in rodents

OBJECTIVES: The aim of this study was to evaluate cardiovascular autonomic function in a rodent obesity model induced by monosodium glutamate injections during the first seven days of life. METHOD: The animals were assigned to control (control, n = 10) and monosodium glutamate (monosodium glutamate, n = 13) groups. Thirty-three weeks after birth, arterial and venous catheters were implanted for arterial pressure measurements, drug administration, and blood sampling. Baroreflex sensitivity was evaluated according to the tachycardic and bradycardic responses induced by sodium nitroprusside and phenylephrine infusion, respectively. Sympathetic and vagal effects were determined by administering methylatropine and propranolol. RESULTS: Body weight, Lee index, and epididymal white adipose tissue values were higher in the monosodium glutamate group in comparison to the control group. The monosodium glutamate-treated rats displayed insulin resistance, as shown by a reduced glucose/insulin index (-62.5%), an increased area under the curve of total insulin secretion during glucose overload (39.3%), and basal hyperinsulinemia. The mean arterial pressure values were higher in the monosodium glutamate rats, whereas heart rate variability (>7 times), bradycardic responses (>4 times), and vagal (similar to 38%) and sympathetic effects (similar to 36%) were reduced as compared to the control group. CONCLUSION: Our results suggest that obesity induced by neonatal monosodium glutamate treatment impairs cardiac autonomic function and most likely contributes to increased arterial pressure and insulin resistance.

Experimental Basis and New Insights for Cell Therapy in Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) can be briefly described as air flow limitation and chronic dyspnea associated to an inflammatory response of the respiratory tract to noxious particles and gases. Its main feature is the obstruction of airflow and consequent chronic dyspnea. Despite recent advances, and the development of new therapeutic, medical and clinical approaches, a curative therapy is yet to be achieved. Therapies involving the use of tissue-specific or donor derived cells present a promising alternative in the treatment of degenerative diseases and injuries. Recent studies demonstrate that mesenchymal stem cells have the capacity to modulate immune responses in acute lung injury and pulmonary fibrosis in animal models, as well as in human patients. Due to these aspects, different groups raised the possibility that the stem cells from different sources, such as those found in bone marrow or adipose tissue, could act preventing the emphysematous lesion progression. In this paper, it is proposed a review of the current state of the art and future perspectives on the use of cell therapy in obstructive lung diseases.

DEPTOR Cell-Autonomously Promotes Adipogenesis, and Its Expression Is Associated with Obesity

DEP domain-containing mTOR-interacting protein (DEPTOR) inhibits the mechanistic target of rapamycin (mTOR), but its in vivo functions are unknown. Previous work indicates that Deptor is part of the Fob3a quantitative trait locus (QTL) linked to obesity/leanness in mice, with Deptor expression being elevated in white adipose tissue (WAT) of obese animals. This relation is unexpected, considering the positive role of mTOR in adipogenesis. Here, we dissected the Fob3a QTL and show that Deptor is the highest-priority candidate promoting WAT expansion in this model. Consistently, transgenic mice overexpressing DEPTOR accumulate more WAT. Furthermore, in humans, DEPTOR expression in WAT correlates with the degree of obesity. We show that DEPTOR is induced by glucocorticoids during adipogenesis and that its overexpression promotes, while its suppression blocks, adipogenesis. DEPTOR activates the proadipogenic Akt/PKB-PPAR-gamma axis by dampening mTORC1-mediated feedback inhibition of insulin signaling. These results establish DEPTOR as a new regulator of adipogenesis.

Ractopamine as a Metabolic Modifier Feed Additive for Finishing Pigs: A Review

The beta-adrenergic agonist ractopamine is increasingly used in the swine industry due to higher consumer demand for leaner pork products. Redirecting nutrients to favor leanness rather than fat deposition, ractopamine improves growth and carcass traits of finishing pigs. However, the impact of this agonist on pork quality is not clearly defined. Understanding the biological effects of dietary ractopamine dose, treatment period, lysine levels, and the lysine to metabolizable energy ratio will help pork producers achieve improvements in animal performance, carcass leanness, and economic efficiency in swine production systems.

Molecular Analysis of the Differentiation Potential of Murine Mesenchymal Stem Cells from Tissues of Endodermal or Mesodermal Origin

Mesenchymal stem cells (MSCs) have received great attention due to their remarkable regenerative, angiogenic, antiapoptotic, and immunosuppressive properties. Although conventionally isolated from the bone marrow, they are known to exist in all tissues and organs, raising the question on whether they are identical cell populations or have important differences at the molecular level. To better understand the relationship between MSCs residing in different tissues, we analyzed the expression of genes related to pluripotency (SOX2 and OCT-4) and to adipogenic (C/EBP and ADIPOR1), osteogenic (OMD and ALP), and chondrogenic (COL10A1 and TRPV4) differentiation in cultures derived from murine endodermal (lung) and mesodermal (adipose) tissue maintained in different conditions. MSCs were isolated from lungs (L-MSCs) and inguinal adipose tissue (A-MSCs) and cultured in normal conditions, in overconfluence or in inductive medium for osteogenic, adipogenic, or chondrogenic differentiation. Cultures were characterized for morphology, immunophenotype, and by quantitative real-time reverse transcription-polymerase chain reaction for expression of pluripotency genes or markers of differentiation. Bone marrow-derived MSCs were also analyzed for comparison of these parameters. L-MSCs and A-MSCs exhibited the typical morphology, immunophenotype, and proliferation and differentiation pattern of MSCs. The analysis of gene expression showed a higher potential of adipose tissue-derived MSCs toward the osteogenic pathway and of lung-derived MSCs to chondrogenic differentiation, representing an important contribution for the definition of the type of cell to be used in clinical trials of cell therapy and tissue engineering.

Uncoupling proteins (UCP) in unicellular eukaryotes: True UCPs or UCP1-like acting proteins?

Uncoupling proteins belong to the superfamily of mitochondrial anion carriers. They are apparently present throughout the Eukarya domain in which only some members have an established physiological function, i.e. UCP1 from brown adipose tissue is involved in non-shivering thermogenesis. However, the proteins responsible for the phenotype observed in unicellular organisms have not been characterized. In this report we analyzed functional evidence concerning unicellular UCPs and found that true UCPs are restricted to some taxonomical groups while proteins conferring a UCP1-like phenotype to fungi and most protists are the result of a promiscuous activity exerted by other mitochondrial anion carriers. We describe a possible evolutionary route followed by these proteins by which they acquire this promiscuous mechanism. (C) 2012 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.

Is zinc-alpha 2-glycoprotein a cardiovascular protective factor for patients undergoing hemodialysis?

Background: Zinc-alpha 2-glycoprotein (ZAG) is a lipid mobilizing factor. Its anti-inflammatory action and expression pattern suggest that ZAG could act by protecting against the obesity-associated disorders. In hemodialysis (HD) patients, ZAG levels were described to be elevated but its effects on markers of inflammation and LDL oxidation are still unclear. We investigated the relationship between ZAG and markers of systemic inflammation and LDL atherogenic modification profile in HD patients. Methods: Forty-three patients regularly on HD were studied and compared to 20 healthy subjects. Plasma ZAG, adiponectin, electronegative LDL [LDL(-)], an atherosclerotic negatively charged LDL subtraction, and anti-LDL(-) autoantibodies levels were measured by ELISA. Markers of inflammation and atherogenic cell recruitment (TNF-alpha, interleukin-6, VCAM-1, ICAM-1, MCP-1 and PAI-1) were also determined. Results: Inflammatory markers and atherogenic cell recruitment were higher in HD patients when compared to healthy subjects. ZAG levels were also higher in HD patients (151.5 +/- 50.1 mg/l vs 54.6 +/- 23.0 mg/l; p<0.0001) and its levels were negatively correlated with TNF-alpha (r= -0.39; p = 0.001) and VCAM-1 (r= -0.52; p<0.0001) and, positively correlated with anti-LDL(-) autoantibodies (r = 038; p = 0.016). On multivariate analyses, plasma ZAG levels were independently associated with VCAM-1 (p = 0.01). Conclusion: ZAG is inversely associated with markers of pro-atherogenic factors linked to systemic inflammation and oxidative stress. Thus, this adipokine may constitute a novel marker of a favorable metabolic profile regarding cardiovascular risk factors in HD population. (C) 2011 Elsevier B.V. All rights reserved.

Acute hypoxia induces hypertriglyceridemia by decreasing plasma triglyceride clearance in mice

Jun JC, Shin MK, Yao Q, Bevans-Fonti S, Poole J, Drager LF, Polotsky VY. Acute hypoxia induces hypertriglyceridemia by decreasing plasma triglyceride clearance in mice. Am J Physiol Endocrinol Metab 303: E377-E388, 2012. First published May 22, 2012; doi:10.1152/ajpendo.00641.2011.-Obstructive sleep apnea (OSA) induces intermittent hypoxia (IH) during sleep and is associated with elevated triglycerides (TG). We previously demonstrated that mice exposed to chronic IH develop elevated TG. We now hypothesize that a single exposure to acute hypoxia also increases TG due to the stimulation of free fatty acid (FFA) mobilization from white adipose tissue (WAT), resulting in increased hepatic TG synthesis and secretion. Male C57BL6/J mice were exposed to FiO(2) = 0.21, 0.17, 0.14, 0.10, or 0.07 for 6 h followed by assessment of plasma and liver TG, glucose, FFA, ketones, glycerol, and catecholamines. Hypoxia dose-dependently increased plasma TG, with levels peaking at FiO(2) = 0.07. Hepatic TG levels also increased with hypoxia, peaking at FiO(2) = 0.10. Plasma catecholamines also increased inversely with FiO(2). Plasma ketones, glycerol, and FFA levels were more variable, with different degrees of hypoxia inducing WAT lipolysis and ketosis. FiO(2) = 0.10 exposure stimulated WAT lipolysis but decreased the rate of hepatic TG secretion. This degree of hypoxia rapidly and reversibly delayed TG clearance while decreasing [H-3]triolein-labeled Intralipid uptake in brown adipose tissue and WAT. Hypoxia decreased adipose tissue lipoprotein lipase (LPL) activity in brown adipose tissue and WAT. In addition, hypoxia decreased the transcription of LPL, peroxisome proliferator-activated receptor-gamma, and fatty acid transporter CD36. We conclude that acute hypoxia increases plasma TG due to decreased tissue uptake, not increased hepatic TG secretion.

Tributyrin attenuates obesity-associated inflammation and insulin resistance in high-fat-fed mice

Vinolo MA, Rodrigues HG, Festuccia WT, Crisma AR, Alves VS, Martins AR, Amaral CL, Fiamoncini J, Hirabara SM, Sato FT, Fock RA, Malheiros G, dos Santos MF, Curi R. Tributyrin attenuates obesity-associated inflammation and insulin resistance in high-fat-fed mice. Am J Physiol Endocrinol Metab 303: E272-E282, 2012. First published May 22, 2012; doi:10.1152/ajpendo.00053.2012.-The aim of this study was to investigate whether treatment with tributyrin (Tb; a butyrate prodrug) results in protection against diet-induced obesity and associated insulin resistance. C57BL/6 male mice fed a standard chow or high-fat diet were treated with Tb (2 g/kg body wt, 10 wk) and evaluated for glucose homeostasis, plasma lipid profile, and inflammatory status. Tb protected mice against obesity and obesity-associated insulin resistance and dyslipidemia without food consumption being affected. Tb attenuated the production of TNF alpha and IL-1 beta by peritoneal macrophages and their expression in adipose tissue. Furthermore, in the adipose tissue, Tb reduced the expression of MCP-1 and infiltration by leukocytes and restored the production of adiponectin. These effects were associated with a partial reversion of hepatic steatosis, reduction in liver and skeletal muscle content of phosphorylated JNK, and an improvement in muscle insulin-stimulated glucose uptake and Akt signaling. Although part of the beneficial effects of Tb are likely to be secondary to the reduction in body weight, we also found direct protective actions of butyrate reducing TNF alpha production after LPS injection and in vitro by LPS- or palmitic acid-stimulated macrophages and attenuating lipolysis in vitro and in vivo. The results, reported herein, suggest that Tb may be useful for the treatment and prevention of obesity-related metabolic disorders.

Administration of a murine diet supplemented with conjugated linoleic acid increases the expression and activity of hepatic uncoupling proteins

Daily intake of conjugated linoleic acid (CLA) has been shown to reduce body fat accumulation and to increase body metabolism; this latter effect has been often associated with the up-regulation of uncoupling proteins (UCPs). Here we addressed the effects of a CLA-supplemented murine diet (similar to 2 % CLA mixture, cis-9, trans-10 and trans-10, cis-12 isomers; 45 % of each isomer on alternating days) on mitochondrial energetics, UCP2 expression/activity in the liver and other associated morphological and functional parameters, in C57BL/6 mice. Diet supplementation with CLA reduced both lipid accumulation in adipose tissues and triacylglycerol plasma levels, but did not augment hepatic lipid storage. Livers of mice fed a diet supplemented with CLA showed high UCP2 mRNA levels and the isolated hepatic mitochondria showed indications of UCP activity: in the presence of guanosine diphosphate, the higher stimulation of respiration promoted by linoleic acid in mitochondria from the CLA mice was almost completely reduced to the level of the stimulation from the control mice. Despite the increased generation of reactive oxygen species through oxi-reduction reactions involving NAD(+)/NADH in the Krebs cycle, no oxidative stress was observed in the liver. In addition, in the absence of free fatty acids, basal respiration rates and the phosphorylating efficiency of mitochondria were preserved. These results indicate a beneficial and secure dose of CLA for diet supplementation in mice, which induces UCP2 overexpression and UCP activity in mitochondria while preserving the lipid composition and redox state of the liver.

Lean and Fat Mass Loss in Obese Patients Before and After Roux-en-Y Gastric Bypass: A New Application for Ultrasound Technique

This study aims to evaluate the thickness of the femoral quadriceps and biceps brachii and brachialis muscles bilaterally and the adjacent subcutaneous fat in patients undergoing gastric bypass Roux-en-Y before and after surgery, using ultrasound as the diagnostic method of choice. We studied 12 patients undergoing this surgical method preoperatively and during the first, third, and sixth postoperative months. During these periods, patients were evaluated by ultrasound to determine the thickness of subcutaneous adipose tissue and muscle of the upper and lower limbs. Postoperatively, these patients showed a reduction in the thickness of the upper and lower extremities muscle and adipose tissue as compared to their preoperative values. There was a significant difference in the loss of muscle thickness in all postoperative months and in the thickness of fatty tissue in the sixth month after surgery, compared to the preoperative muscle and fatty tissue thickness. Ultrasound can be considered as the diagnostic method of choice when assessment of the fat and lean body mass is required in morbidly obese patients before and after bariatric surgery.