Leucine supplementation combined with resistance exercise improves the plasma lipid profile of dexamethasone-treated rats

The impact of leucine supplementation and resistance exercise (RE) on plasma lipid profile was evaluated in adult rats treated with dexamethasone, an experimental model of dyslipidemia. Total cholesterol did not differ among groups. Furthermore, leucine supplementation did not promote improvement in the plasma total cholesterol and LDL-c of the animals. However, plasma TG and VLDL-c were significantly decreased and HDL-c increased after 7 days of leucine supplementation combined with RE. In conclusion, leucine supplementation combined with RE, but not isolated, improved the plasma lipid profile of dexamethasone-induced dyslipidemic rats.

Serum amyloid A is a growth factor for 3T3-L1 adipocytes, inhibits differentiation and promotes insulin resistance

BACKGROUND/OBJECTIVES: Serum amyloid A (SAA) is an acute-phase protein that has been recently correlated with obesity and insulin resistance. Therefore, we first examined whether human recombinant SAA (rSAA) could affect the proliferation, differentiation and metabolism of 3T3-L1 preadipocytes. DESIGN: Preadipocytes were treated with rSAA and analyzed for changes in viability and [H-3-methyl]-thymidine incorporation as well as cell cycle perturbations using flow cytometry analysis. The mRNA expression profiles of adipogenic factors during the differentiation protocol were also analyzed using real-time PCR. After differentiation, 2-deoxy-[1,2-H-3]-glucose uptake and glycerol release were evaluated. RESULTS: rSAA treatment caused a 2.6-fold increase in cell proliferation, which was consistent with the results from flow cytometry showing that rSAA treatment augmented the percentage of cells in the S phase (60.9 +/- 0.54%) compared with the control cells (39.8 +/- 2.2%, ***P<0.001). The rSAA-induced cell proliferation was mediated by the ERK1/2 signaling pathway, which was assessed by pretreatment with the inhibitor PD98059. However, the exposure of 3T3-L1 cells to rSAA during the differentiation process resulted in attenuated adipogenesis and decreased expression of adipogenesis-related factors. During the first 72 h of differentiation, rSAA inhibited the differentiation process by altering the mRNA expression kinetics of adipogenic transcription factors and proteins, such as PPAR gamma 2 (peroxisome proliferator-activated receptor gamma 2), C/EBP beta (CCAAT/enhancer-binding protein beta) and GLUT4. rSAA prevented the intracellular accumulation of lipids and, in fully differentiated cells, increased lipolysis and prevented 2-deoxy-[1,2-H-3]-glucose uptake, which favors insulin resistance. Additionally, rSAA stimulated the secretion of proinflammatory cytokines interleukin 6 and tumor necrosis factor alpha, and upregulated SAA3 mRNA expression during adipogenesis. CONCLUSIONS: We showed that rSAA enhanced proliferation and inhibited differentiation in 3T3-L1 preadipocytes and altered insulin sensitivity in differentiated cells. These results highlight the complex role of SAA in the adipogenic process and support a direct link between obesity and its co-morbidities such as type II diabetes.

Ectoplacental Cone Induces Resistance to Apoptosis in High Doses of Interferon (IFN)-gamma-Treated Decidual Cells

Problem In this study, we explored the relationship between decidual cells (DC) and interferon (IFN)-gamma, in the presence or absence of ectoplacental cone (EC) using a coculture system. Method of study Decidual cells and EC were isolated from pregnant mice on gestation day 7.5. DCs were cultured for 48 hr and then treated with fresh EC. After characterization, they were treated with IFN-gamma, and cell death was evaluated. Results Interferon-gamma drastically increased decidual apoptosis, which was partially reverted by the addition of EC to the IFN-gamma-treated decidual culture. Moreover, the addition of EC to non-treated DC cultures was also capable of attenuating death rates. Conclusion Resistance to apoptosis may be induced in DC by the EC. This suggests that EC may participate in the inhibition of IFN-gamma-dependent apoptosis and, therefore, play important role for DC survival in a cytokineenriched placental environment.

Single-Nucleotide Polymorphism and Copy Number Variation of the Multidrug Resistance-1 Locus of Plasmodium vivax: Local and Global Patterns

Emerging resistance to chloroquine (CQ) poses a major challenge for Plasmodium vivax malaria control, and nucleotide substitutions and copy number variation in the P. vivax multidrug resistance 1 (pvmdr-1) locus, which encodes a digestive vacuole membrane transporter, may modulate this phenotype. We describe patterns of genetic variation in pvmdr-1 alleles from Acre and Amazonas in northwestern Brazil, and compare then with those reported in other malaria-endemic regions. The pvmdr-1 mutation Y976F, which is associated with CQ resistance in Southeast Asia and Oceania, remains rare in northwestern Brazil (1.8%) and its prevalence mirrors that of CO resistance worldwide. Gene amplification of pvmdr-1, which is associated with mefloquine resistance but increased susceptibility to CO, remains relatively rare in northwestern Brazil (0.9%) and globally (< 4%), but became common (> 10%) in Tak Province, Thailand, possibly because of drug-mediated selection. The global database we have assembled provides a baseline for further studies of genetic variation in pvmdr-1 and drug resistance in P. vivax malaria.

Long-term interdisciplinary therapy reduces endotoxin level and insulin resistance in obese adolescents

Abstract Aim The purpose of the present study was to assess the dietary fat intake, glucose, insulin, Homeostasis model assessment for insulin resistance HOMA-IR, and endotoxin levels and correlate them with adipokine serum concentrations in obese adolescents who had been admitted to long-term interdisciplinary weight-loss therapy. Design The present study was a longitudinal clinical intervention of interdisciplinary therapy. Adolescents (n = 18, aged 15–19 y) with a body mass index > 95th percentile were admitted and evaluated at baseline and again after 1 year of interdisciplinary therapy. We collected blood samples, and IL-6, adiponectin, and endotoxin concentrations were measured by ELISA. Food intake was measured using 3-day diet records. In addition, we assessed glucose and insulin levels as well as the homeostasis model assessment for insulin resistance (HOMA-IR). Results The most important finding from the present investigation was that the long-term interdisciplinary lifestyle therapy decreased dietary fat intake and endotoxin levels and improved HOMA-IR. We observed positive correlations between dietary fat intake and endotoxin levels, insulin levels, and the HOMA-IR. In addition, endotoxin levels showed positive correlations with IL-6 levels, insulin levels and the HOMA-IR. Interestingly, we observed a negative correlation between serum adiponectin and both dietary fat intake and endotoxin levels. Conclusions The present results indicate an association between dietary fat intake and endotoxin level, which was highly correlated with a decreased pro-inflammatory state and an improvement in HOMA-IR. In addition, this benefits effect may be associated with an increased adiponectin level, which suggests that the interdisciplinary therapy was effective in improving inflammatory pathways.

Infliximab prevents increased systolic blood pressure and upregulates the AKT/eNOS pathway in the aorta of spontaneously hypertensive rats

High systolic blood pressure caused by endothelial dysfunction is a comorbidity of metabolic syndrome that is mediated by local inflammatory signals. Insulin-induced vasorelaxation due to endothelial nitric oxide synthase (eNOS) activation is highly dependent on the activation of the upstream insulin-stimulated serine/threonine kinase (AKT) and is severely impaired in obese, hypertensive rodents and humans. Neutralisation of circulating tumor necrosis factor-α (TNFα) with infliximab improves glucose homeostasis, but the consequences of this pharmacological strategy on systolic blood pressure and eNOS activation are unknown. To address this issue, we assessed the temporal changes in the systolic pressure of spontaneously hypertensive rats (SHR) treated with infliximab. We also assessed the activation of critical proteins that mediate insulin activity and TNFα-mediated insulin resistance in the aorta and cardiac left ventricle. Our data demonstrate that infliximab prevents the upregulation of both systolic pressure and left ventricle hypertrophy in SHR. These effects paralleled an increase in AKT/eNOS phosphorylation and a reduction in the phosphorylation of inhibitor of nuclear factor-κB (Iκβ) and c-Jun N-terminal kinase (JNK) in the aorta. Overall, our study revealed the cardiovascular benefits of infliximab in SHR. In addition, the present findings further suggested that the reduction of systolic pressure and left ventricle hypertrophy by infliximab are secondary effects to the reduction of endothelial inflammation and the recovery of AKT/eNOS pathway activation.

Changes in food intake, metabolic parameters and insulin resistance are induced by an isoenergetic, medium-chain fatty acid diet and are associated with modifications in insulin signalling in isolated rat pancreatic islets

LLong-chain fatty acids are capable of inducing alterations in the homoeostasis of glucose-stimulated insulin secretion (GSIS), but the effect of medium-chain fatty acids (MCFA) is poorly elucidated. In the present study, we fed a normoenergetic MCFA diet to male rats from the age of 1 month to the age of 4 months in order to analyse the effect of MCFA on body growth, insulin sensitivity and GSIS. The 45% MCFA substitution of whole fatty acids in the normoenergetic diet impaired whole body growth and resulted in increased body adiposity and hyperinsulinaemia, and reduced insulin-mediated glucose uptake in skeletal muscle. In addition, the isolated pancreatic islets from the MCFA-fed rats showed impaired GSIS and reduced protein kinase Ba (AKT1) protein expression and extracellular signal-related kinase isoforms 1 and 2 (ERK(1/2)) phosphorylation, which were accompanied by increased cellular death. Furthermore, there was a mildly increased cholinergic sensitivity to GSIS. We discuss these findings in further detail, and advocate that they might have a role in the mechanistic pathway leading to the compensatory hyperinsulinaemic status found in this animal model.

In pulmonary paracoccidioidomycosis IL-10 deficiency leads to increased immunity and regressive infection without enhancing tissue pathology

BACKGROUND: Cellular immunity is the main defense mechanism in paracoccidioidomycosis (PCM), the most important systemic mycosis in Latin America. Th1 immunity and IFN-γ activated macrophages are fundamental to immunoprotection that is antagonized by IL-10, an anti-inflammatory cytokine. Both in human and experimental PCM, several evidences indicate that the suppressive effect of IL-10 causes detrimental effects to infected hosts. Because direct studies have not been performed, this study was aimed to characterize the function of IL-10 in pulmonary PCM. METHODOLOGY/PRINCIPAL FINDINGS: Wild type (WT) and IL-10(-/-) C57BL/6 mice were used to characterize the role of IL-10 in the innate and adaptive immunity against Paracoccidioides brasiliensis (Pb) infection. We verified that Pb-infected peritoneal macrophages from IL-10(-/-) mice presented higher phagocytic and fungicidal activities than WT macrophages, and these activities were associated with elevated production of IFN-γ, TNF-α, nitric oxide (NO) and MCP-1. For in vivo studies, IL-10(-/-) and WT mice were i.t. infected with 1×10(6) Pb yeasts and studied at several post-infection periods. Compared to WT mice, IL-10(-/-) mice showed increased resistance to P. brasiliensis infection as determined by the progressive control of pulmonary fungal loads and total clearance of fungal cells from dissemination organs. This behavior was accompanied by enhanced delayed-type hypersensitivity reactions, precocious humoral immunity and controlled tissue pathology resulting in increased survival times. In addition, IL-10(-/-) mice developed precocious T cell immunity mediated by increased numbers of lung infiltrating effector/memory CD4(+) and CD8(+) T cells. The inflammatory reactions and the production of Th1/Th2/Th17 cytokines were reduced at late phases of infection, paralleling the regressive infection of IL-10(-/-) mice. CONCLUSIONS/SIGNIFICANCE: Our work demonstrates for the first time that IL-10 plays a detrimental effect to pulmonary PCM due to its suppressive effect on the innate and adaptive immunity resulting in progressive infection and precocious mortality of infected hosts.

Resistance exercise acutely enhances mesenteric artery insulin-induced relaxation in healthy rats

AIMS: We evaluated the mechanisms involved in insulin-induced vasodilatation after acute resistance exercise in healthy rats. MAIN METHODS: Wistar rats were divided into 3 groups: control (CT), electrically stimulated (ES) and resistance exercise (RE). Immediately after acute RE (15 sets with 10 repetitions at 70% of maximal intensity), the animals were sacrificed and rings of mesenteric artery were mounted in an isometric system. After this, concentration-response curves to insulin were performed in control condition and in the presence of LY294002 (PI3K inhibitor), L-NAME (NOS inhibitor), L-NAME+TEA (K(+) channels inhibitor), LY294002+BQ123 (ET-A antagonist) or ouabain (Na(+)/K(+) ATPase inhibitor). KEY FINDINGS: Acute RE increased insulin-induced vasorelaxation as compared to control (CT: Rmax=7.3 ± 0.4% and RE: Rmax=15.8 ± 0.8%; p<0.001). NOS inhibition reduced (p<0.001) this vasorelaxation from both groups (CT: Rmax=2.0 ± 0.3%, and RE: Rmax=-1.2 ± 0.1%), while PI3K inhibition abolished the vasorelaxation in CT (Rmax=-0.1±0.3%, p<0.001), and caused vasoconstriction in RE (Rmax=-6.5 ± 0.6%). That insulin-induced vasoconstriction on PI3K inhibition was abolished (p<0.001) by the ET-A antagonist (Rmax=2.9 ± 0.4%). Additionally, acute RE enhanced (p<0.001) the functional activity of the ouabain-sensitive Na(+)/K(+) ATPase activity (Rmax=10.7 ± 0.4%) and of the K(+) channels (Rmax=-6.1±0.5%; p<0.001) in the insulin-induced vasorelaxation as compared to CT. SIGNIFICANCE: Such results suggest that acute RE promotes enhanced insulin-induced vasodilatation, which could act as a fine tuning to vascular tone.