Free diet selection by broilers as influenced by dietary macronutrient ratio and corticosterone supplementation. 1. Diet selection, organ weights, and plasma metabolites

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dietary, anthropometric, and biochemical determinants of plasma high-density lipoprotein-cholesterol in free-living adults

The level of high-density lipoprotein is thought to be critical in inhibiting lesion formation as well as reducing the lipid load of preexisting atherosclerotic lesions. With the aim of determining the main determinants of plasma HDL-cholesterol (HDL-c) in free-living adults, 997 individuals (52.3 10 years, 67 females) were selected for a descriptive cross-sectional study. The used data corresponded to the baseline obtained from participants clinically selected for a lifestyle modification program. Covariables of clinical, anthropometry, food intake, aerobic fitness, and plasma biochemistry were analyzed against plasma HDL-c either as continuous or categorized variables. After adjustments for age, gender, and BMI the excess of abdominal fat along with high carbohydrate-energy intake and altered plasma triglycerides were the stronger predictors of reduced plasma HDL-c. In conclusion lifestyle interventions aiming to normalize abdominal fatness and plasma triglycerides are recommended to restore normal levels of HDL-c in these free-living adults. Copyright © 2011 Erick Prado de Oliveira et al.

The Higher Plasma Malondialdehyde Concentrations Are Determined by Metabolic Syndrome-Related Glucolipotoxicity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of community-based physical exercise interventions carried out in primary helath care on plasma inflammatory biomarkers and cardiorespiratory fitness

Pós-graduação em Ciências da Motricidade - IBRC

Efeito do plasma rico em glicose na apoptose de neutrófilos de cães

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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.

Strength training improves plasma parameters, body composition and liver morphology in ovariectomized rats

Objective. - The aim of this study was to identify the effects of strength training on plasma parameters, body composition and the liver of ovariectomized rats. Methods. - Wistar sedentary (SHAM), ovariectomized (OVX), and ovariectomized trained rats (strength training [OVX-EXE]) of 85% of one maximal repetition (1 RM), three times per week, for 10 weeks, were used on this study. We monitored the body weight and visceral (uterine, mesenteric and retroperitoneal) and subcutaneous adiposity, total cholesterol, triglycerides, HDL, blood glucose and liver morphology to identify the presence of macrovesicular steotosis (haematoxylin and eosin staining). Results. - We observed that strength training changed body weight (SHAM 293.0 +/- 14.5 g; OVX 342.6 +/- 10.8 g; OVX-EXE 317.7 +/- 11.9 g, P < 0.05), visceral and subcutaneous adiposity, glucose (SHAM 111.2 +/- 10.0 mg/dL; OVX 147.4 +/- 18.8 mg/dL; OVX-EXE 118.5 +/- 2.2 mg/dL, P < 0.05), increased HDL (SHAM 82.7 +/- 1.4 mg/dL; OVX 64.6 +/- 2.8 mg/dL; OVX-EXE 91.4 +/- 2.6 mg/dL, P < 0.05) and reduced macrovesicular steatosis in liver tissue. Conclusions. - Considering the data obtained in this research, we emphasise the use of strength exercise training as a therapeutic means to combat or control the metabolic disturbances associated with menopause, including adiposity, and adverse changes in blood glucose, blood HDL and macrovesicular steatosis. (C) 2011 Elsevier Masson SAS. All rights reserved.

Induced hypoglycemia for 48 hours indicates differential glucose and insulin effects on liver metabolism in dairy cows

Hypoglycemia is a characteristic condition of early lactation dairy cows and is subsequently dependent on, and may affect, metabolism in the liver. The objective of the present study was to investigate the effects of induced hypoglycemia, maintained for 48 h, on metabolic parameters in plasma and liver of mid-lactation dairy cows. The experiment involved 3 treatments, including a hyperinsulinemic hypoglycemic clamp (HypoG, n=6) to obtain a glucose concentration of 2.5 mmol/L, a hyperinsulinemic euglycemic clamp (EuG, n=6) in which the effect of insulin was studied, and a control treatment with a 0.9% saline solution (NaCl, n=6). Blood samples for measurements of insulin, metabolites, and enzymes were taken at least once per hour. Milk yield was recorded and milk samples were collected before and after treatment. Liver biopsies were obtained before and after treatment to measure mRNA abundance by real-time, quantitative reverse transcription-PCR of 12 candidate genes involved in the main metabolic pathways. Milk yield decreased in HypoG and NaCl cows, whereas it remained unaffected in EuG cows. Energy-corrected milk yield (kg/d) was only decreased in HypoG cows. In plasma, concentration of beta-hydroxybutyrate decreased in response to treatment in EuG cows and was lower (0.41+/-0.04 mmol/L) on d 2 of the treatment compared with that in HypoG and NaCl cows (on average 0.61+/-0.03 mmol/L, respectively). Nonesterified fatty acids remained unaffected in all treatments. In the liver, differences between treatments for their effects were only observed in case of mitochondrial phosphoenolpyruvate carboxykinase (PEPCKm) and glucose-6-phosphatase (G6PC). In HypoG, mRNA abundance of PEPCKm was upregulated, whereas in EuG and NaCl cows, it was downregulated. The EuG treatment downregulated mRNA expression of G6PC, a marked effect compared with the unchanged transcript expression in NaCl. The mRNA abundance of the insulin receptor remained unaffected in all treatments, and no significant treatment differences were observed for genes related to lipid metabolism. In conclusion, low glucose concentrations in dairy cows affect liver metabolism at a molecular level through upregulation of PEPCKm mRNA abundance. Metabolic regulatory events in the liver are directed, apart from hormones, by the level of metabolites, either in excess (e.g., free fatty acids) or in shortage (e.g., glucose).

Neural network based glucose - insulin metabolism models for children with Type 1 diabetes

In this paper two models for the simulation of glucose-insulin metabolism of children with Type 1 diabetes are presented. The models are based on the combined use of Compartmental Models (CMs) and artificial Neural Networks (NNs). Data from children with Type 1 diabetes, stored in a database, have been used as input to the models. The data are taken from four children with Type 1 diabetes and contain information about glucose levels taken from continuous glucose monitoring system, insulin intake and food intake, along with corresponding time. The influences of taken insulin on plasma insulin concentration, as well as the effect of food intake on glucose input into the blood from the gut, are estimated from the CMs. The outputs of CMs, along with previous glucose measurements, are fed to a NN, which provides short-term prediction of glucose values. For comparative reasons two different NN architectures have been tested: a Feed-Forward NN (FFNN) trained with the back-propagation algorithm with adaptive learning rate and momentum, and a Recurrent NN (RNN), trained with the Real Time Recurrent Learning (RTRL) algorithm. The results indicate that the best prediction performance can be achieved by the use of RNN.

Hepatic gene expression involved in glucose and lipid metabolism in transition cows: effects of fat mobilization during early lactation in relation to milk performance and metabolic changes.

Insufficient feed intake during early lactation results in elevated body fat mobilization to meet energy demands for milk production. Hepatic energy metabolism is involved by increasing endogenous glucose production and hepatic glucose output for milk synthesis and by adaptation of postcalving fuel oxidation. Given that cows differ in their degree of fat mobilization around parturition, indicated by variable total liver fat concentration (LFC), the study investigated the influence of peripartum fat mobilization on hepatic gene expression involved in gluconeogenesis, fatty acid oxidation, ketogenesis, and cholesterol synthesis, as well as transcriptional factors referring to energy metabolism. German Holstein cows were grouped according to mean total LFC on d 1, 14, and 28 after parturition as low [<200mg of total fat/g of dry matter (DM); n=10], medium (200-300 mg of total fat/g of DM; n=10), and high (>300 mg of total fat/g of DM; n=7), indicating fat mobilization during early lactation. Cows were fed total mixed rations ad libitum and held under equal conditions. Liver biopsies were taken at d 56 and 15 before and d 1, 14, 28, and 49 after parturition to measure mRNA abundances of pyruvate carboxylase (PC); phosphoenolpyruvate carboxykinase; glucose-6-phosphatase; propionyl-coenzyme A (CoA) carboxylase α; carnitine palmitoyl-transferase 1A (CPT1A); acyl-CoA synthetase, long chain 1 (ASCL1); acyl-CoA dehydrogenase, very long chain; 3-hydroxy-3-methylglutaryl-CoA synthase 1 and 2; sterol regulatory element-binding factor 1; and peroxisome proliferator-activated factor α. Total LFC postpartum differed greatly among cows, and the mRNA abundance of most enzymes and transcription factors changed with time during the experimental period. Abundance of PC mRNA increased at parturition to a greater extent in high- and medium-LFC groups than in the low-LFC group. Significant LFC × time interactions for ACSL1 and CPT1A during the experimental period indicated variable gene expression depending on LFC after parturition. Correlations between hepatic gene expression and performance data and plasma concentrations of metabolites and hormones showed time-specific relations during the transition period. Elevated body fat mobilization during early lactation affected gene expression involved in gluconeogenesis to a greater extent than gene expression involved in lipid metabolism, indicating the dependence of hepatic glucose metabolism on hepatic lipid status and fat mobilization during early lactation.

Effects of colostrum versus formula feeding on hepatic glucocorticoid and α1- and β2-adrenergic receptors in neonatal calves and their effect on glucose and lipid metabolism

Neonatal energy metabolism in calves has to adapt to extrauterine life and depends on colostrum feeding. The adrenergic and glucocorticoid systems are involved in postnatal maturation of pathways related to energy metabolism and calves show elevated plasma concentrations of cortisol and catecholamines during perinatal life. We tested the hypothesis that hepatic glucocorticoid receptors (GR) and α₁- and β₂-adrenergic receptors (AR) in neonatal calves are involved in adaptation of postnatal energy metabolism and that respective binding capacities depend on colostrum feeding. Calves were fed colostrum (CF; n=7) or a milk-based formula (FF; n=7) with similar nutrient content up to d 4 of life. Blood samples were taken daily before feeding and 2h after feeding on d 4 of life to measure metabolites and hormones related to energy metabolism in blood plasma. Liver tissue was obtained 2 h after feeding on d 4 to measure hepatic fat content and binding capacity of AR and GR. Maximal binding capacity and binding affinity were calculated by saturation binding assays using [(3)H]-prazosin and [(3)H]-CGP-12177 for determination of α₁- and β₂-AR and [(3)H]-dexamethasone for determination of GR in liver. Additional liver samples were taken to measure mRNA abundance of AR and GR, and of key enzymes related to hepatic glucose and lipid metabolism. Plasma concentrations of albumin, triacylglycerides, insulin-like growth factor I, leptin, and thyroid hormones changed until d 4 and all these variables except leptin and thyroid hormones responded to feed intake on d 4. Diet effects were determined for albumin, insulin-like growth factor I, leptin, and thyroid hormones. Binding capacity for GR was greater and for α₁-AR tended to be greater in CF than in FF calves. Binding affinities were in the same range for each receptor type. Gene expression of α₁-AR (ADRA1) tended to be lower in CF than FF calves. Binding capacity of GR was related to parameters of glucose and lipid metabolism, whereas β₂-AR binding capacity was negatively associated with glucose metabolism. In conclusion, our results indicate a dependence of GR and α₁-AR on milk feeding immediately after birth and point to an involvement of hepatic GR and AR in postnatal adaptation of glucose and lipid metabolism in calves.

The Glucose-Dependent Insulinotropic Polypeptide Receptor: A Novel Target for Neuroendocrine Tumor Imaging-First Preclinical Studies

A new family of peptide receptors, the incretin receptor family, overexpressed on many neuroendocrine tumors (NETs) is of great importance because it may enable the in vivo peptide-based receptor targeting of a category of NETs that does not express the somatostatin receptor. Impressive in vivo diagnostic data were published for glucagonlike peptide 1 receptor-targeting radiopeptides. Recently, promising in vitro data have appeared for the second member of the incretin family, the glucose-dependent insulinotropic polypeptide (GIP) receptor. This prompted us to develop and evaluate a new class of radioligands with the potential to be used for the in vivo targeting of GIP receptor-positive tumors. METHODS GIP(1-42) was modified C-terminally, and the truncated peptides [Lys(30)(aminohexanoic acid [Ahx]-DOTA)]GIP(1-30)NH2 (EG1), [Lys(16)(Ahx-DOTA)]GIP(1-30)NH2 (EG2), and [Nle(14), Lys(30)(Ahx-DOTA)]GIP(1-30)NH2 (EG4) were conjugated with Ahx-DOTA via the Lys(16) and Lys(30) side chains. Their inhibitory concentration of 50% (IC50) was determined using [(125)I-Tyr(10)]GIP(1-30) as radioligand and GIP(1-30) as control peptide. The DOTA conjugates were labeled with (111)In and (68)Ga. In vitro evaluation included saturation and internalization studies using the pancreatic endocrine cell line INR1G9 transfected with the human GIP receptor (INR1G9-hGIPr). The in vivo evaluation consisted of biodistribution and PET imaging studies on nude mice bearing INR1G9-hGIPr tumors. RESULTS Binding studies (IC50 and saturation studies) showed high affinity toward GIP receptor for the GIP conjugates. Specific in vitro internalization was found, and almost the entire cell-associated activity was internalized (>90% of the cell-bound activity), supporting the agonist potency of the (111)In-vectors. (111)In-EG4 and (68)Ga-EG4 were shown to specifically target INR1G9-hGIPr xenografts, with tumor uptake of 10.4% ± 2.2% and 17.0% ± 4.4% injected activity/g, 1 h after injection, respectively. Kidneys showed the highest uptake, which could be reduced by approximately 40%-50% with a modified-fluid-gelatin plasma substitute or an inhibitor of the serine protease dipeptidyl peptidase 4. The PET images clearly visualized the tumor. CONCLUSION The evaluation of EG4 as a proof-of-principle radioligand indicated the feasibility of imaging GIP receptor-positive tumors. These results prompt us to continue the development of this family of radioligands for imaging of a broad spectrum of NETs.

Normal hepatic glucose production in the absence of GLUT2 reveals an alternative pathway for glucose release from hepatocytes

Glucose production by liver is a major physiological function, which is required to prevent development of hypoglycemia in the postprandial and fasted states. The mechanism of glucose release from hepatocytes has not been studied in detail but was assumed instead to depend on facilitated diffusion through the glucose transporter GLUT2. Here, we demonstrate that in the absence of GLUT2 no other transporter isoforms were overexpressed in liver and only marginally significant facilitated diffusion across the hepatocyte plasma membrane was detectable. However, the rate of hepatic glucose output was normal. This was evidenced by (i) the hyperglycemic response to i.p. glucagon injection; (ii) the in vivo measurement of glucose turnover rate; and (iii) the rate of release of neosynthesized glucose from isolated hepatocytes. These observations therefore indicated the existence of an alternative pathway for hepatic glucose output. Using a [14C]-pyruvate pulse-labeling protocol to quantitate neosynthesis and release of [14C]glucose, we demonstrated that this pathway was sensitive to low temperature (12°C). It was not inhibited by cytochalasin B nor by the intracellular traffic inhibitors brefeldin A and monensin but was blocked by progesterone, an inhibitor of cholesterol and caveolae traffic from the endoplasmic reticulum to the plasma membrane. Our observations thus demonstrate that hepatic glucose release does not require the presence of GLUT2 nor of any plasma membrane glucose facilitative diffusion mechanism. This implies the existence of an as yet unsuspected pathway for glucose release that may be based on a membrane traffic mechanism.

Development of an in vitro reconstitution assay for glucose transporter 4 translocation

In an attempt to define the mechanism of insulin-regulated glucose transporter 4 (Glut4) translocation, we have developed an in vitro reconstitution assay. Donor membranes from 3T3-L1 adipocytes transfected with mycGlut4 were incubated with plasma membrane (PM) from nontransfected 3T3-L1 cells, and the association was assessed by using two types of centrifugation assays. Association of mycGlut4 vesicles derived from donor membranes with the PM was concentration-, temperature-, time-, and Ca2+-dependent but ATP-independent. Addition of a syntaxin 4 fusion protein produced a biphasic response, increasing association at low concentration and inhibiting association at higher concentrations. PM from insulin-stimulated cells showed an enhanced association as compared with those from untreated cells. Use of donor membranes from insulin-stimulated cells further enhanced the association and also enhanced association to the PM from isolated rat adipocytes. Addition of cytosol, GTP, or guanosine 5′-[γ-thio]triphosphate decreased the association. In summary, insulin-induced Glut4 translocation can be reconstituted in vitro to a limited extent by using isolated membranes. This association appears to involve protein–protein interactions among the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex proteins. Finally, the ability of insulin to enhance association depends on insulin-induced changes in the PM and, to a lesser extent, in the donor membranes.

Differential Regulation of Secretory Compartments Containing the Insulin-responsive Glucose Transporter 4 in 3T3-L1 Adipocytes

Insulin and guanosine-5′-O-(3-thiotriphosphate) (GTPγS) both stimulate glucose transport and translocation of the insulin-responsive glucose transporter 4 (GLUT4) to the plasma membrane in adipocytes. Previous studies suggest that these effects may be mediated by different mechanisms. In this study we have tested the hypothesis that these agonists recruit GLUT4 by distinct trafficking mechanisms, possibly involving mobilization of distinct intracellular compartments. We show that ablation of the endosomal system using transferrin-HRP causes a modest inhibition (∼30%) of insulin-stimulated GLUT4 translocation. In contrast, the GTPγS response was significantly attenuated (∼85%) under the same conditions. Introduction of a GST fusion protein encompassing the cytosolic tail of the v-SNARE cellubrevin inhibited GTPγS-stimulated GLUT4 translocation by ∼40% but had no effect on the insulin response. Conversely, a fusion protein encompassing the cytosolic tail of vesicle-associated membrane protein-2 had no significant effect on GTPγS-stimulated GLUT4 translocation but inhibited the insulin response by ∼40%. GTPγS- and insulin-stimulated GLUT1 translocation were both partially inhibited by GST-cellubrevin (∼50%) but not by GST-vesicle-associated membrane protein-2. Incubation of streptolysin O-permeabilized 3T3-L1 adipocytes with GTPγS caused a marked accumulation of Rab4 and Rab5 at the cell surface, whereas other Rab proteins (Rab7 and Rab11) were unaffected. These data are consistent with the localization of GLUT4 to two distinct intracellular compartments from which it can move to the cell surface independently using distinct sets of trafficking molecules.