Antidiabetic effect of Euterpe oleracea Mart. (acai) extract and exercise training on high-fat diet and streptozotocin-induced diabetic rats: A positive interaction.
ABSTRACT: A growing body of evidence suggests a protective role of polyphenols and exercise training on the disorders of type 2 diabetes mellitus (T2DM). We aimed to assess the effect of the açaí seed extract (ASE) associated with exercise training on diabetic complications induced by high-fat (HF) diet plus streptozotocin (STZ) in rats. Type 2 diabetes was induced by feeding rats with HF diet (55% fat) for 5 weeks and a single dose of STZ (35 mg/kg i.p.). Control (C) and Diabetic (D) animals were subdivided into four groups each: Sedentary, Training, ASE Sedentary, and ASE Training. ASE (200 mg/kg/day) was administered by gavage and the exercise training was performed on a treadmill (30min/day; 5 days/week) for 4 weeks after the diabetes induction. In type 2 diabetic rats, the treatment with ASE reduced blood glucose, insulin resistance, leptin and IL-6 levels, lipid profile, and vascular dysfunction. ASE increased the expression of insulin signaling proteins in skeletal muscle and adipose tissue and plasma GLP-1 levels. ASE associated with exercise training potentiated the reduction of glycemia by decreasing TNF-? levels, increasing pAKT and adiponectin expressions in adipose tissue, and IR and pAMPK expressions in skeletal muscle of type 2 diabetic rats. In conclusion, ASE treatment has an antidiabetic effect in type 2 diabetic rats by activating the insulin-signaling pathway in muscle and adipose tissue, increasing GLP-1 levels, and an anti-inflammatory action. Exercise training potentiates the glucose-lowering effect of ASE by activating adiponectin-AMPK pathway and increasing IR expression.
Project description:Myostatin (MSTN) is not only a key negative regulator of skeletal muscle secretion, however is also an endocrine factor that is transmitted to bone. To investigate the effect and possible mechanism of weight-bearing treadmill running on bone with poorly controlled Type 1 diabetes, rats were randomly divided into three groups: Normal control (NC), diabetic mellitus (DM) and diabetic exercise training groups (DM-WTR). The DM-WTR rats were trained with weight-bearing running. The results demonstrated that the levels of serum insulin, body weight, bone mass, muscle mass, grip strength, and serum calcium in the DM-WTR rats were significantly increased, whereas the levels of blood glucose, alkaline phosphatase, and tartrate-resistant acid phosphatase were markedly reduced in the DM-WTR rats compared with the DM rats. Weight-bearing running inhibited streptozocin (STZ)-induced MSTN mRNA and protein expression in the diabetic rats. The mRNA and protein expression levels of activin type IIB receptor and mothers against decapentaplegic homolog 2/3 and its phosphorylation in femur DM-WTR rats were reduced compared with DM rats. In addition, weight-bearing running enhanced the STZ-induced Wnt and ?-catenin expression levels and reduced the STZ-induced glycogen synthase kinase (GSK)-3? expression in diabetic rats' femora. In conclusion, the results suggested that weight-bearing running could partially ameliorate STZ-induced femur atrophy via MSTN downregulation, and this may be associated with the inactivation of Activin A Receptor Type 2B/Smad2/3 signaling pathways and the activation of the Wnt/GSK3?/?-catenin signaling pathway. Further studies are needed to verify these conclusions.
Project description:Diabetic myopathy refers to the manifestations in the skeletal muscle as a result of altered glucose homeostasis which reflects as fibrosis. Since physical exercise has been indicated a protective strategy for improving glucose metabolism in skeletal muscle, we tested a hypothesis under which the endurance exercise training could reverse the produced skeletal muscle fibrosis by diabetes. Eight-week-old male Wistar rats were randomly assigned into four groups including healthy control (HC), healthy trained (HT), diabetic control (DC), and diabetic trained (DT) groups. Diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ; 45?mg/kg). Rats in the HT and DT groups carried out an exercise program on a motorized treadmill for five days a week over six weeks. Skeletal muscle levels of NRG1and ErbB2 were measured by the Western blot method. Exercise training decreased blood glucose levels in the DT group. Induction of diabetes increased skeletal muscle fibrosis in both the fast extensor digitorum longus (EDL) and slow soleus muscles, while endurance training modified it in diabetic trained rats. Moreover, muscle NRG1and ErbB2 levels were increased in diabetic rats, while training modified muscle NRG1and ErbB2 levels in diabetic trained rats. Our study provides novel evidence that endurance training could modify skeletal muscle fibrosis through NRG1/ErbB2 modification in STZ-induced diabetic rats.
Project description:BACKGROUND: Sleeve gastrectomy (SG) has emerged recently as a stand-alone bariatric procedure to treat morbid obesity and enhance glucose homeostasis. The aim of the study was to evaluate its effects in neonatally streptozotocin (STZ)-induced diabetic rats (n-STZ diabetic rats). METHODOLOGY AND PRINCIPAL FINDINGS: To induce diabetes, STZ (90 mg/kg) was administered intraperitoneally to 2-day-old male pups. When 12 weeks old, diabetic rats were randomized into sleeve operation group (SLG, n = 6) and sham operation group (SOG, n = 6). Body weights were monitored weekly, and daily consumption of water and food were followed for eight consecutive weeks postoperatively. Serum glucose levels were measured periodically at the 4th and 8th week after surgery. Insulin, ghrelin, glucose-dependent insulinotropic polypeptide (GIP) and Glucagon-like peptide-1 (GLP-1) levels were assayed at the end of the study. Our data showed that SLG rats exhibited significantly lower body weight gain in addition to reduced food and water intakes postoperatively compared to their sham-operation counterparts. However, resolution of diabetes was not observed in our study. Correspondingly, there were no significant differences between SOG rats and SLG rats in glucose metabolism-associated hormones, including insulin, GIP and GLP-1. In contrast, ghrelin level significantly decreased (P<0.01) in SLG group (58.01 ± 3.75 pg/ml) after SG surgery compared to SOG group (76.36 ± 3.51 pg/ml). CONCLUSIONS: These observations strongly suggest that SG is effective in controlling body weight. However, SG did not achieve resolution or improvement of diabetes in n-STZ diabetic rats.
Project description:Background & Aims:Accumulating research has addressed the linkage between the changes to gut microbiota structure and type 2 diabetes (T2D). Inulin is one type of soluble dietary fiber that can alleviate T2D. As a prebiotic, inulin cannot be digested by humans, but rather is digested by probiotics. However, whether inulin treatment can benefit the entire gut bacteria community remains unknown. In this study, we evaluated the differences in gut microbiota composition among diabetic, inulin-treated diabetic, normal control, and inulin-treated normal control rats. Methods:A diabetic rat model was generated by a high-fat diet and streptozotocin injections (HF/STZ). Inulin was orally administered to normal and diabetic rats. To determine the composition of the gut microbiota, fecal DNA extraction and 16S rRNA gene 454 pyrosequencing were performed. Results:We found that inulin treatment reduced fasting blood glucose levels and alleviated glucose intolerance and blood lipid panels in diabetic rats. Additionally, inulin treatment increased the serum glucagon-like peptide-1 (GLP-1) level, reduced serum IL-6 level, Il6 expression in epididymal adipose tissue, and Pepck, G6pc expression in liver of diabetic rats. Pyrophosphate sequencing of the 16s V3-V4 region demonstrated an elevated proportion of Firmicutes and a reduced abundance of Bacteroidetes at the phylogenetic level in diabetic rats compared to normal control rats. The characteristics of the gut microbiota in control and inulin-treated rats were similar. Inulin treatment can normalize the composition of the gut microbiota in diabetic rats. At the family and genus levels, probiotic bacteria Lactobacillus and short-chain fatty acid (SCFA)-producing bacteria Lachnospiraceae, Phascolarctobacterium, and Bacteroides were found to be significantly more abundant in the inulin-treated diabetic group than in the non-treated diabetic group. In addition, inulin-treated rats had a lower abundance of Desulfovibrio, which produce lipopolysaccharide (LPS). The abundance of Lachnospiraceae was negatively correlated with the blood glucose response after a glucose load. Conclusion:In summary, diabetic rats have different gut microbiota from control rats. Inulin treatment can alleviate gut microbiota dysbiosis in T2D model rats. Moreover, inulin treatment enhanced serum GLP-1 level to suppress IL-6 secretion and production and hepatic gluconeogenesis, resulted in moderation of insulin tolerance.
Project description:Adipocyte size and body fat distribution are strongly linked to the metabolic complications of obesity. The aim of the present study was to test the plasticity of white adipose tissue in response to insulin deprivation and replacement. We have characterized the changes of adipose cell size repartition and gene expressions in type 1 diabetes Sprague-Dawley rats and type 1 diabetic supplemented with insulin.Using streptozotocin (STZ)-induced diabetes, we induced rapid changes in rat adipose tissue weights to study the changes in the distribution of adipose cell sizes in retroperitoneal (rWAT), epididymal (eWAT) and subcutaneous adipose tissues (scWAT). Adipose tissue weights of type 1 diabetic rats were then rapidly restored by insulin supplementation. Cell size distributions were analyzed using multisizer IV (Beckman Coulter). Cell size changes were correlated to transcriptional regulation of genes coding for proteins involved in lipid and glucose metabolisms and adipocytokines.The initial body weight of the rats was 465±5.2 g. Insulin privation was stopped when rats lost 100 g which induced reductions in fat mass of 68% for rWAT, 42% for eWAT and 59% for scWAT corresponding to decreased mode cell diameters by 31.1%, 20%, 25.3%, respectively. The most affected size distribution by insulin deprivation was observed in rWAT. The bimodal distribution of adipose cell sizes disappeared in response to insulin deprivation in rWAT and scWAT. The most important observation is that cell size distribution returned close to control values in response to insulin treatment. mRNAs coding for adiponectin, leptin and apelin were more stimulated in scWAT compared to other depots in diabetic plus insulin group.Fat depots have specific responses to insulin deprivation and supplementation. The results show that insulin is a major determinant of bimodal cell repartition in adipose tissues.
Project description:Diabetes and exercise training have been shown to involve interleukin 6 (IL-6) signaling in muscle. However, the relationship between the actions of these two stimuli on muscle IL-6 and their downstream components is still unknown. Thus, the effect of endurance training on the key components of muscle IL-6 signaling transduction was investigated in a rat model of type 2 diabetes.Diabetes was induced by streptozotocin (STZ) in male Wistar rats fed a high-fat diet, with normal rats acting as controls. The animals were left to conduct their normal activities or assigned to endurance training in a treadmill. At the end of 8 weeks, blood biochemical profiles, exercise performance, muscle oxidative capacity, glucose transporter 4 (GLUT4) protein distribution, and expressions of IL-6 and its downstream proteins were determined.Blood biochemical profiles of the diabetic rats were altered compared to normal rats, whereas endurance training improved blood chemistry and exercise performance. It also increased muscle oxidative capacity, and promoted GLUT4 subcellular localization to the membrane in muscles. Furthermore, protein expression of IL-6 receptor (IL-6Rα) was increased in both normal and diabetic rats after endurance training, but no significant changes in IL-6, phosphorylated signal transducer and activator of transcription 3 (p-STAT3), or suppressor of cytokine signaling 3 (SOC3) were observed in muscles of normal and diabetic rats.IL-6 signaling pathway mediating muscle response to endurance training was conserved in type 2 diabetes. There was no link between training-induced IL-6 downstream targets in skeletal muscles and IL-6-induced type 2 diabetes.
Project description:Endurance exercise training has been shown to decrease whole-body and skeletal muscle insulin resistance and increase glucose tolerance in conditions of both pre-diabetes and overt type 2 diabetes. However, the adaptive responses in skeletal muscle at the molecular and genetic level for these beneficial effects of exercise training have not been clearly established in an animal model of pre-diabetes. The present study identifies alterations in skeletal muscle gene expression that occur with exercise training in pre-diabetic, insulin-resistant obese Zucker (fa/fa) rats and insulin-sensitive lean Zucker (Fa/-) rats. Treadmill running for up to 4 weeks caused significant enhancements of glucose tolerance as assessed by the integrated area under the curve for glucose (AUCg) during an oral glucose tolerance test in both lean and obese animals. Using microarray analysis, a set of only 12 genes was identified as both significantly altered (>1.5-fold change relative to sedentary controls; p<0.05) and significantly correlated (p<0.05) with the AUCg. Two of these genes, peroxisome proliferator-activated receptor-g coactivator 1a (PGC-1a) and the z-isoform of protein kinase C (PKC-z), have known involvement in the regulation of skeletal muscle glucose transport. We confirmed that protein expression levels of PGC-1a and PKC-z were positively correlated with the mRNA expression levels for these two genes. Overall, this study has identified a limited number of genes in soleus muscle of lean and obese Zucker rats that are associated with decreased insulin resistance and increase glucose tolerance following endurance exercise training. These findings could guide the development of pharmaceutical exercise mimetics in the treatment of insulin-resistant, pre-diabetic or overtly type 2 diabetic individuals.
Project description:Glucagon-like peptide 1 (GLP-1) mimetics have been approved as an adjunct therapy for glycemic control in type 2 diabetic patients for the increased insulin secretion under hyperglycemic conditions. Recently, it is reported that such agents elicit neuroprotective effects against diabetes-associated cognitive decline. However, there is an issue of poor compliance by multiple daily subcutaneous injections for sufficient glycemic control due to their short duration, and neuroprotective actions were not fully studied, yet. In this study, using the prepared exendin-4 fusion protein agent, we investigated the pharmacokinetic profile and the role of this GLP-1 mimetics on memory deficits in a high-fat diet (HFD)/streptozotocin (STZ) mouse model of type 2 diabetic mellitus. After induction of diabetes, mice were administered weekly by intraperitoneal injection of GLP-1 mimetics for 6 weeks. This treatment reversed HFD/STZ-induced metabolic symptoms of increased body weight, hyperglycemia, and hepatic steatosis. Furthermore, the impaired cognitive performance of diabetic mice was significantly reversed by GLP-1 mimetics. GLP-1 mimetic treatment also reversed decreases in GLP-1/GLP-1 receptor expression levels in both the pancreas and hippocampus of diabetic mice; increases in hippocampal inflammation, mitochondrial fission, and calcium-binding protein levels were also reversed. These findings suggest that GLP-1 mimetics are promising agents for both diabetes and neurodegenerative diseases that are associated with increased GLP-1 expression in the brain.
Project description:Previous studies have demonstrated that an acute bout of aerobic exercise induces a subsequent delayed onset of hypoglycemia among patients with type 1 diabetes. However, the mechanisms of exercise-induced hypoglycemia in type 1 diabetes are still unclear. Streptozotocin (STZ) was injected to 6-week-old male Wistar rats, and three days after STZ injection, animals were randomly assigned into 2 groups: STZ with insulin only (STZ) and STZ with insulin and exercise (STZ+EX). Normal Wistar rats with exercise were used as control (CON+EX). Insulin was intraperitoneally injected (0.5 U/kg) to both STZ groups (-0.5 h), and a bout of aerobic exercise (15 m/min for 30 min) was conducted at euglycemic conditions (0 h). Blood was collected at 0, 1, 3, and 5 h after exercise from the carotid artery. While the blood glucose level was stable during the post-exercise period (0-5 h) in the STZ and CON+EX groups, it decreased significantly only in the STZ+EX group at 3 h. Plasma glucagon, adrenalin, and noradrenalin levels significantly increased at 1 h in the STZ group, whereas significant hormonal responses were observed at 5 h in the STZ+EX group. In skeletal muscle glucose metabolism-related pathway, the level of glucose transporter-4 (GLUT-4) translocation was significantly higher at 1 h in the CON and STZ groups. However, in the STZ+EX group, these activations were maintained by 5 h, indicating a sustained glucose metabolism in the STZ+EX group. A single bout of aerobic exercise induced a delayed onset of hypoglycemia in STZ-treated rats. A prolonged enhancement of GLUT-4 translocation and delayed counter-regulatory hormone responses may have contributed to the induction of hypoglycemia.
Project description:Induced oxidative stress in diabetes mellitus (DM) plays a critical role in insulin resistance. Fork head-related transcription factor (FOXO) proteins are important transcriptional factors involved in oxidative stress and insulin resistance. Resveratrol (RSV) is a polyphenol with hypoglycemic and antioxidant properties. The aims of the present study were to examine the effects of RSV on FOXO gene expression, serum superoxide dismutase (SOD) activity, insulin level, and insulin resistance in type 2 diabetic (T2DM) rats. Thirty male Wistar rats were used in this study. DM was induced in rats (n=24) using streptozotocin (STZ) and nicotinamide; then, they were divided into 4 groups of 6 rats each. Six untreated normal rats were used as normal control group; diabetic rats in groups 2 to 5 were treated with 0, 1, 5 and 10 mg /kg body weight of RSV, respectively for 30 days. At the end of the experimental period, the rats were sacri?ced, their sera were separated, and adipose tissues were obtained and stored at -80 °C. Serum glucose and SOD activity levels were determined biochemically, and serum insulin level was determined by ELISA method. Gere expression in FOXO1 and FOXO3a in adipose tissue was evaluated using real-time PCR. Results indicated that RSV significantly reduced blood glucose level, increased insulin level and improved insulin sensitivity. RSV resulted in an increased serum SOD activity and caused decreased FOXO1 and FOXO3a expression in adipose tissue of rats with T2DM. Therefore, by attenuation of FOXO expression in adipose tissue of T2DM rats, RSV showed a hypoglycemic potential and antioxidant properties, and consequently ameliorated insulin resistance.