Intraperitoneal Insulin Tolerance Test Research Articles

Abstract 18139: Genetic Deficiency of Traf-1 Attenuates Diet-Induced Adipose Tissue Inflammation by Limiting the Pool of Circulating and Splenic Monocytes in Mice

Background: Accumulation of inflammatory leukocytes, such as of macrophages, is a prerequisite of adipose tissue inflammation during the metabolic syndrome. We recently reported that genetic deficiency of Tumor necrosis factor receptor-associated factor (TRAF) -1 attenuated inflammatory cell recruitment in atherosclerosis. Here, we tested the hypothesis that TRAF-1 deficiency modulates adipose tissue inflammation in a model of diet-induced obesity (DIO) in mice. Methods and Results: To test the association of TRAFs and adipose tissue inflammation we screened for expression of different TRAFs in mouse adipose tissue after 20 weeks of feeding with a high fat (HFD) or a control diet. HFD induced up-regulation of TRAF-1, -3, -5, -6, and -7 mRNA. Interestingly, the amplitude of gene regulation was highest for TRAF-1 (4.9-fold, n=8 per group, p=0.002). Also, in human subcutaneous tissue TRAF-1 gene expression correlated with body mass index of donors (r=0.94, p=0.019). To test functional relevance of our findings, WT or TRAF-1-/- mice consumed HFD for 12 weeks (n ≥ 10 mice per group). Interestingly, TRAF-1-/- mice gained less weight during DIO (119 ± 7.5 % vs. 41 ± 3.7 % of starting body weight for WT and TRAF-1-/-, respectively). Accordingly, total body weight, weight of visceral and cardiac fat pads was decreased in TRAF-1-/- mice. Moreover, TRAF-1-/- mice demonstrated lower glucose levels after starving and during weight-adapted intraperitoneal glucose and insulin tolerance tests, suggesting functional involvement of TRAF-1 in insulin and glucose signaling. Finally, inflammatory cell recruitment was impaired in TRAF-1-/- mice with reduced numbers of adipose tissue macrophages. Functionally, circulating and splenic, but not bone marrow monocytes were lowered in TRAF-1-/- mice, proposing that TRAF-1 modulates monocyte mobilization during inflammation. Conclusion: We present the novel finding that TRAF-1 is regulated in obese murine and human adipose tissue. Genetic deficiency of TRAF-1 attenuates adipose tissue inflammation in mice by limiting monocyte recruitment. These findings identify TRAF-1 as a potent mediator at the interface of cardiovascular and metabolic disease.

Camel milk ameliorates steatohepatitis, insulin resistance and lipid peroxidation in experimental non-alcoholic fatty liver disease

BackgroundCamel milk (CM) is gaining increasing recognition due to its beneficial effects in the control and prevention of multiple health problems. The current study aimed to investigate the effects of CM on the hepatic biochemical and cellular alterations induced by a high-fat, cholesterol-rich diet (HCD), specifically, non-alcoholic fatty liver disease (NAFLD).MethodsSeventy male Wistar rats were divided into four groups: the Control (C) Group fed a standard diet; the Control + camel milk (CCM) Group fed a standard diet and CM, the Cholesterol (Ch) Group fed a HCD with no CM, and the Cholesterol + camel milk (ChM) Group fed a HCD and CM. The following parameters were investigated in the studied groups; basal, weekly random and final fasting blood glucose levels, intraperitoneal glucose tolerance test (GTT) and insulin tolerance test (ITT), serum insulin, serum lipids, liver functions, lipid peroxidation products, the antioxidant activity of catalase (CAT) and the levels of reduced glutathione (GSH). In addition, HOMA-IR as an index of insulin resistance (IR) and the histopathology of the hepatic tissue were assessed.ResultsThe Ch Group developed features similar to those of non-alcoholic steatohepatitis (NASH), characterized by hepatic steatosis; inflammatory cellular infiltration in liver tissue; altered liver functions; and increased total cholesterol, triglycerides, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, atherogenic index (AI), blood glucose, IR, and malondialdehyde (MDA) levels. Additionally, feeding the HCD to animals in the Ch Group decreased CAT activity and the GSH and high-density lipoprotein (HDL) cholesterol levels. Camel milk intake for eight weeks decreased hepatic fat accumulation and inflammatory cellular infiltration, preserved liver function, increased the GSH levels and CAT activity, decreased the MDA levels, and ameliorated the changes in the lipid profile, AI, and IR in animals from the ChM Group.ConclusionsCM has a unique composition that is rich in minerals; vitamins, insulin and insulin-like protein, and it increased HDL-cholesterol and ameliorated the biochemical and cellular features of NAFLD in rats that received a HCD. The antioxidant effect of CM is a likely mechanism for the altered metabolism and absorption of HCD in the presence of CM. Regular consumption of CM could provide a natural way to protect against NAFLD induced by a high-fat diet.

14-3-3zeta Regulates Adipogenesis, Glucose Tolerance and Insulin Sensitivity in Mice

Adipogenesis is a complex process governed by a distinct network of adipogenic transcription factors. As obesity is a growing health concern, a complete understanding of the mechanisms that govern adipocyte differentiation is critical for the development of novel therapies. Molecular adaptors, such as the 14-3-3 protein family, integrate and coordinate signalling events, but whether they facilitate adipocyte differentiation is not known. Therefore, we hypothesized that they are critical for adipogenesis. We utilized knockout mice lacking 14-3-3zeta, an isoform, which we previously reported to regulate pancreatic beta-cell survival. Throughout their lifespan, knockout mice were significantly smaller than wild-type controls. This was attributed to decreased adiposity and smaller adipocytes, as assessed by DEXA and histological studies. Deletion of 14-3-3zeta was also associated with immature adipocytes as serum levels of leptin were significantly decreased, in addition to the expression of mature adipocyte genes (Hsl, Atgl, and Fasn). Knockout mice also exhibited glucose intolerance and insulin resistance, as measured by intraperitoneal glucose (2 g/kg) and insulin (1.5 U/kg) tolerance tests. To further examine the roles of 14-3-3zeta in adipogenesis, 3T3-L1 pre-adipocytes were transfected with 14-3-3zeta siRNA, which blocked differentiation, as observed by Oil Red-O staining and quantitative PCR measurements of Ppparg, Slc2a4, Hsl and Fasn. Furthermore, depletion of 14-3-3zeta promoted the rapid degradation of the critical adipogenic factor, C/EBP-delta, resulting in attenuated nuclear translocation during differentiation. Collectively, this work identifies 14-3-3zeta as a novel regulator of adipogenesis, glucose homeostasis and insulin action, and highlights a potential therapeutic target for the treatment of obesity.

Hydrodynamic Delivery of mIL10 Gene Protects Mice From High-fat Diet-induced Obesity and Glucose Intolerance

High-fat diet (HFD) induced obesity is associated with low-grade inflammation, insulin resistance (IR), and glucose intolerance. The objective of this study is to assess the effect of interleukin 10 (IL10), an anti-inflammatory cytokine, on blocking HFD-induced obesity and obesity-associated metabolic disorders by hydrodynamic delivery of IL10-containing plasmid. Animals fed a regular chow or HFD received two injections (one on day 1 and the other on day 31) of plasmids containing green fluorescence protein (GFP) or mouse IL10 (mIL10) gene. Blood concentration of mIL10 reached ~200 ng/ml on day 7 in animals receiving mIL10 plasmid DNA. The transfection efficiency of liver cells was the same in animals fed a regular chow or HFD. No difference was seen in animals on regular chow when injected with plasmids containing either gfp or mIL10 gene. Overexpression of mIL10 prevented weight gain of animals on HFD. Intraperitoneal glucose tolerance test (IPGTT) and insulin tolerance tests (ITT) showed that mIL10 maintained insulin sensitivity and prevented glucose intolerance. The mechanistic study reveals that mIL10 suppressed macrophage infiltration and reduced the development of crown-like structures in adipose tissue (AT). Collectively, these results suggest that maintaining a higher level of IL10 through gene transfer could be an effective strategy in preventing diet-induced obesity.

Antigen peptide transporter 1 is involved in the development of fructose‐induced hepatic steatosis in mice

The purpose of this study is to assess whether the decrease in CD8 cells has any role in the development of non-alcoholic fatty liver disease (NAFLD). In this study, we therefore used antigen peptide transporter 1 (TAP1(-/-)) mice that cannot transport major histocompatibility complex class I antigens onto the cell surface resulting in failure of the generation of CD8 cells. Wild-type C57Bl/6J and TAP1(-/-) mice were fed with 30% fructose solution for 8 weeks. The percentage of CD4, CD8 cells in peripheral blood mononuclear cells, and liver were sorted by fluorescence-activated cell sorting in both control and fructose-treated mice. Bodyweight, histopathological changes, oil red O staining, glucose tolerance test, intraperitoneal insulin tolerance test, serum levels of triglycerides, cholesterol, aspartate aminotransferase, and alanine aminotransferase were also evaluated. Quantitative real-time polymerase chain reaction was performed to determine the expression of specific genes involved in development of fatty changes in the liver. Chronic consumption of fructose in TAP1(-/-) mice did not develop NAFLD, insulin resistance, or change in level of CD8 cells. Moreover, there was delay in relative expression levels of genes involved in development of NAFLD in fructose-treated TAP1(-/-) mice. Taken together, the data suggest that TAP1(-/-) -deficient mice displayed reduced levels of CD8 cells that have a vital role in the initiation and propagation of liver inflammation and is a casual role in the beginning of fructose-induced liver damage as well as insulin resistance in mice.

Resveratrol supplementation improves white adipose tissue function in a depot-specific manner in Zucker diabetic fatty rats

Resveratrol (RSV) is a polyphenolic compound suggested to have anti-diabetic properties. Surprisingly, little is known regarding the effects of RSV supplementation on adipose tissue (AT) metabolism in vivo. The purpose of this study was to assess the effects of RSV on mitochondrial content and respiration, glyceroneogenesis (GNG), and adiponectin secretion in adipose tissue from Zucker diabetic fatty (ZDF) rats. Five-week-old ZDF rats were fed a chow diet with (ZDF RSV) or without (ZDF chow) RSV (200 mg/kg body wt) for 6 wk. Changes in adipose tissue metabolism were assessed in subcutaneous (scAT) and intra-abdominal [retroperitoneal (rpWAT), epididymal (eWAT)] adipose tissue depots. ZDF RSV rats showed lower fasting glucose and higher circulating adiponectin, as well as lower glucose area under the curve during intraperitoneal glucose and insulin tolerance tests than ZDF chow. [¹⁴C]pyruvate incorporation into triglycerides and adiponectin secretion were higher in scAT from ZDF RSV rats, concurrent with increases in adipose tissue triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and the phosphorylation of pyruvate dehydrogenase-E1α (PDH) (Ser293) protein content in this depot. Moreover, uncoupled mitochondrial respiration and complex I and II-supported respiration were increased in both scAT and rpWAT, which correlated with increases in cytochrome c oxidase subunit IV (COX4) protein content. In vitro treatment of scAT with RSV (50 μmol/l; 24 h) induced pyruvate dehydrogenase kinase 4 (PDK4) and peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α) mRNA expression. Collectively, these data demonstrate that RSV can induce adipose tissue mitochondrial biogenesis in parallel with increases in GNG and adiponectin secretion.

Glucose Homeostasis in Mice Is Transglutaminase 2 Independent

Transglutaminase type 2 (TG2) has been reported to be a candidate gene for maturity onset diabetes of the young (MODY) because three different mutations that impair TG2 transamidase activity have been found in 3 families with MODY. TG2 null (TG2−/−) mice have been reported to be glucose intolerant and have impaired glucose-stimulated insulin secretion (GSIS). Here we rigorously evaluated the role of TG2 in glucose metabolism using independently generated murine models of genetic TG2 disruption, which show no compensatory enhanced expression of other TGs in pancreatic islets or other tissues. First, we subjected chow- or fat-fed congenic SV129 or C57BL/6 wild type (WT) and TG2−/− littermates, to oral glucose gavage. Blood glucose and serum insulin levels were similar for both genotypes. Pancreatic islets isolated from these animals and analysed in vitro for GSIS and cholinergic potentiation of GSIS, showed no significant difference between genotypes. Results from intraperitoneal glucose tolerance tests (GTTs) and insulin tolerance tests (ITTs) were similar for both genotypes. Second, we directly investigated the role of TG2 transamidase activity in insulin secretion using a coisogenic model that expresses a mutant form of TG2 (TG2R579A), which is constitutively active for transamidase activity. Intraperitoneal GTTs and ITTs revealed no significant differences between WT and TG2R579A/R579A mice. Given that neither deletion nor constitutive activation of TG2 transamidase activity altered basal responses, or responses to a glucose or insulin challenge, our data indicate that glucose homeostasis in mice is TG2 independent, and question a link between TG2 and diabetes.

Targeted Deletion of Growth Hormone (GH) Receptor in Macrophage Reveals Novel Osteopontin-mediated Effects of GH on Glucose Homeostasis and Insulin Sensitivity in Diet-induced Obesity

We investigated GH action on macrophage (MΦ) by creating a MΦ-specific GH receptor-null mouse model (MacGHR KO). On a normal diet (10% fat), MacGHR KO and littermate controls exhibited similar growth profiles and glucose excursions on intraperitoneal glucose (ipGTT) and insulin tolerance (ITT) tests. However, when challenged with high fat diet (HFD, 45% fat) for 18 weeks, MacGHR KO mice exhibited impaired ipGTT and ITT compared with controls. In MacGHR KO, adipose-tissue (AT) MΦ abundance was increased with skewing toward M1 polarization. Expression of pro-inflammatory cytokines (IL1β, TNF-α, IL6, and osteopontin (OPN)) were increased in MacGHR KO AT stromal vascular fraction (SVF). In MacGHR KO AT, crown-like-structures were increased with decreased insulin-dependent Akt phosphorylation. The abundance of phosphorylated NF-κB and of OPN was increased in SVF and bone-marrow-derived MΦ in MacGHR KO. GH, acting via an NF-κB site in the distal OPN promoter, inhibited the OPN promoter. Thus in diet-induced obesity (DIO), lack of GH action on the MΦ exerts an unexpected deleterious effect on glucose homeostasis by accentuating AT inflammation and NF-κB-dependent activation of OPN expression. These novel results in mice support the possibility that administration of GH could have salutary effects on DIO-associated chronic inflammation and insulin resistance in humans.

Effect and the probable mechanisms of silibinin in regulating insulin resistance in the liver of rats with non-alcoholic fatty liver

Our previous study has shown that reduced insulin resistance (IR) was one of the possible mechanisms for the therapeutic effect of silibinin on non-alcoholic fatty liver disease (NAFLD) in rats. In the present study, we investigated the pathways of silibinin in regulating hepatic glucose production and IR amelioration. Forty-five 4- to 6-week-old male Sprague Dawley rats were divided into a control group, an HFD group (high-fat diet for 6 weeks) and an HFD + silibinin group (high-fat diet + 0.5 mg kg-1·day-1 silibinin, starting at the beginning of the protocol). Both subcutaneous and visceral fat was measured. Homeostasis model assessment-IR index (HOMA-IR), intraperitoneal glucose tolerance test and insulin tolerance test (ITT) were performed. The expression of adipose triglyceride lipase (ATGL) and of genes associated with hepatic gluconeogenesis was evaluated. Silibinin intervention significantly protected liver function, down-regulated serum fat, and improved IR, as shown by decreased HOMA-IR and increased ITT slope. Silibinin markedly prevented visceral obesity by reducing visceral fat, enhanced lipolysis by up-regulating ATGL expression and inhibited gluconeogenesis by down-regulating associated genes such as Forkhead box O1, phosphoenolpyruvate carboxykinase and glucose-6-phosphatase. Silibinin was effective in ameliorating IR in NAFLD rats. Reduction of visceral obesity, enhancement of lipolysis and inhibition of gluconeogenesis might be the underlying mechanisms.

Choline Supplementation Promotes Hepatic Insulin Resistance in Phosphatidylethanolamine N-Methyltransferase-deficient Mice via Increased Glucagon Action

Biosynthesis of hepatic choline via phosphatidylethanolamine N-methyltransferase (PEMT) plays an important role in the development of type 2 diabetes and obesity. We investigated the mechanism(s) by which choline modulates insulin sensitivity. PEMT wild-type (Pemt(+/+)) and knock-out (Pemt(-/-)) mice received either a high fat diet (HF; 60% kcal of fat) or a high fat, high choline diet (HFHC; 4 g of choline/kg of HF diet) for 1 week. Hepatic insulin signaling and glucose and lipid homeostasis were investigated. Glucose and insulin intolerance occurred in Pemt(-/-) mice fed the HFHC diet, but not in their Pemt(-/-) littermates fed the HF diet. Plasma glucagon was elevated in Pemt(-/-) mice fed the HFHC diet compared with Pemt(-/-) mice fed the HF diet, concomitant with increased hepatic expression of glucagon receptor, phosphorylated AMP-activated protein kinase (AMPK), and phosphorylated insulin receptor substrate 1 at serine 307 (IRS1-s307). Gluconeogenesis and mitochondrial oxidative stress were markedly enhanced, whereas glucose oxidation and triacylglycerol biosynthesis were diminished in Pemt(-/-) mice fed the HFHC diet. A glucagon receptor antagonist (2-aminobenzimidazole) attenuated choline-induced hyperglycemia and insulin intolerance and blunted up-regulation of phosphorylated AMPK and IRS1-s307. Choline induces glucose and insulin intolerance in Pemt(-/-) mice through modulating plasma glucagon and its action in liver.

Anti-Hyperglycemic Effect of Single Administered Gardeniae Fructus in Streptozotocin-Induced Diabetic Mice by Improving Insulin Resistance and Enhancing Glucose Uptake in Skeletal Muscle

The mechanisms of Gardeniae Fructus (GF) for anti-hyperglycemic action were demonstrated in streptozotocin (STZ)-diabetic mice. Six hours after single intraperitoneal administration of GF (300 mg/kg) or H2O into 3 hour-fasted STZ-diabetic mice, glucose and insulin tolerances were assessed by intraperitoneal glucose (1.5 g/kg) tolerance test (IPGTT) and intraperitoneal insulin (0.65 U/kg) tolerance test (IPITT), respectively. Effects of GF on insulin signaling pathways in soleus muscle such as glucose uptake, expression of glucose transporter 4 (GLUT4) in the plasma membrane and phosphorylation of Akt (P-Akt) in cytosolic fraction were examined in STZ-diabetic mice. In IPGTT test, GF significantly accelerated clearance of exogenous glucose and its glucose-lowering action was greater than H2O-treated controlin STZ-diabetic mice. GF also promoted an exogenous glucose-increased insulin level in STZ-diabetic mice. In IPITT test, GF decreased glucose level to the greater extent than H2O-treated control in STZ-diabetic mice. Furthermore, GF significantly decreased high HOMA-IR in STZ-diabetic mice from 21.6 ± 2.4 to 12.4 ± 1.9 (mg/dl × μU/ml). These results implied that GF improved insulin resistance in STZ-diabetic mice. GF increased glucose uptake of soleus muscle 1.5 times greater than H2O-treated control in STZ-diabetic mice. GF enlarged insulin (10 nmol/ml)-increased glucose uptake to 1.8 time-greater. Correspondingly, GF increased expression of GLUT4 in the plasma membrane of soleus muscle to 1.4 time-greater, and P-Akt in the cytosolic fraction of soleus muscle to 1.9 time-greater than those in H2O-treated control. In conclusion, the improvement of GF on insulin resistance is associated with the repair of insulin signaling via P-Akt, GLUT4 and glucose uptake pathway in soleus muscle of STZ-diabetic mice.

Chronic Resveratrol Treatment Protects Pancreatic Islets against Oxidative Stress in db/db Mice

Resveratrol (RSV) has anti-inflammatory and anti-oxidant actions which may contribute to its cardiovascular protective effects. We examined whether RSV has any beneficial effects on pancreatic islets in db/db mice, an animal model of type 2 diabetes. The db/db and db/dm mice (non-diabetic control) were treated with (db-RSV) or without RSV (db-control) (20 mg/kg daily) for 12 weeks. After performing an intraperitoneal glucose tolerance test and insulin tolerance test, mice were sacrificed, the pancreas was weighed, pancreatic β-cell mass was quantified by point count method, and the amount of islet fibrosis was determined. 8-Hydroxydeoxyguanosine (8-OHdG), an oxidative stress marker, was determined in 24 h urine and pancreatic islets. RSV treatment significantly improved glucose tolerance at 2 hrs in db/db mice (P = 0.036), but not in db/dm mice (P = 0.623). This was associated with a significant increase in both pancreas weight (P = 0.011) and β-cell mass (P = 0.016). Islet fibrosis was much less in RSV-treated mice (P = 0.048). RSV treatment also decreased urinary 8-OHdG levels (P = 0.03) and the percentage of islet nuclei that were positive for 8-OHdG immunostaining (P = 0.019). We conclude that RSV treatment improves glucose tolerance, attenuates β-cell loss, and reduces oxidative stress in type 2 diabetes. These findings suggest that RSV may have a therapeutic implication in the prevention and management of diabetes.

Effect of Pulses as Part of a Low Glycemic Index Diet on Glycemic Control and Cardiovascular Risk Factors in Type 2 Diabetes

s / Can J Diabetes 36 (2012) S2eS22 S19 the involvement of 14-3-3 proteins inmetabolism invivo,we focused our efforts onknockout (KO)mice lacking14-3-3z, an isoform thatwe recently found to be critical for b-cell survival. At weaning, KO mice were significantly smaller than wild-type (WT) controls, but were indistinguishable fromWTmice by 8 weeks. Intraperitoneal glucose (2g/kg) and insulin (0.75U/kg) tolerance tests demonstrated that 143-3z KO mice were glucose intolerant and insulin resistant. b-cell mass, as measured by fluorescent microscopy, was 1.5-fold higher (p<0.05) in KO mice, and this was also associated with a 2-fold increase (p<0.05) in random-fed insulin levels. Serum triglycerides were 1.5-fold higher (p<0.05) in KO mice, and analysis of lipogenic genes in white adipose tissue showed significantly decreased transcript expression of hormone sensitive lipase, fatty acid synthase, and acetyl-CoA carboxylase. Taken together, these findings demonstrate, for the first time, that 14-3-3 proteins and in particular the z isoform are required for insulin signaling and glucose homeostasis in vivo. Further work is required to examine the mechanisms that alter metabolism in the absence of 14-3-3z.

Perinatal exercise improves glucose homeostasis in adult offspring

Emerging research has shown that subtle factors during pregnancy and gestation can influence long-term health in offspring. In an attempt to be proactive, we set out to explore whether a nonpharmacological intervention, perinatal exercise, might improve offspring health. Female mice were separated into sedentary or exercise cohorts, with the exercise cohort having voluntary access to a running wheel prior to mating and during pregnancy and nursing. Offspring were weaned, and analyses were performed on the mature offspring that did not have access to running wheels during any portion of their lives. Perinatal exercise caused improved glucose disposal following an oral glucose challenge in both female and male adult offspring (P < 0.05 for both). Blood glucose concentrations were reduced to lower values in response to an intraperitoneal insulin tolerance test for both female and male adult offspring of parents with access to running wheels (P < 0.05 and P < 0.01, respectively). Male offspring from exercised dams showed increased percent lean mass and decreased fat mass percent compared with male offspring from sedentary dams (P < 0.01 for both), but these parameters were unchanged in female offspring. These data suggest that short-term maternal voluntary exercise prior to and during healthy pregnancy and nursing can enhance long-term glucose homeostasis in offspring.

Prebiotics improve metabolic parameter in uremic mice by reducing intestinal production of p-cresyl sulfate

Chronic kidney disease (CKD) is associated with a large range of metabolic alterations. P-cresyl sulfate (PCS) has been identified as one of the main uremic toxins involved in the pathogenesis of accelerated atherosclerosis in CKD. The prebiotic soluble fibers have the property of selectively stimulate growth and activity of a limited number of beneficial bacteria in the colon. The aim of this study is to assess in mice the effects of prebiotics by the reduction of PCS intestinal production, on metabolic disturbances associated with CKD. Subtotally nephrectomized C57BL/6J wild-type mice were divided into two groups: CKD mice and CKD mice fed with 5% (w/w standard diet) of prebiotic arabinoxylane oligosaccharides (AXOS, WITAXOS SA,). Three weeks after initiation of prebiotics serum cholesterol total, triglycerides, glucose, PCS were measured. The insulin sensitivity was estimated by intra-peritoneal insulin tolerance test and glucose tolerance test. CKD mice treated with AXOS exhibited a significant decrease in serum total PCS (−74%, p =0.03). Prebiotic treatment reduced the loss of fat mass observed in CKD (+33%, p These results suggest that prebiotics AXOS decrease PCS and prevented CKD-induced insulin resistance, the loss of adipose tissue and prevented accumulation of ectopic lipids in muscle and liver.. Because insulin resistance is an important cardiovascular risk factor, novel therapeutic approaches like prebiotics which could decrease PCS and cardio vascular mortality.

Role of lipotoxicity in insulin resistance in subtotally nephrectomized mouse model

Chronic kidney disease (CKD) is associated with a large range of metabolic alterations among which insulin resistance and dyslipidemia. We hypothesize that a phenomenon of lipotoxicity and ectopic fat redistribution could be responsible for the insulin-resistance associated to CKD. C57BL/6 mice underwent a 5/6 nephrectomy and were compared to pair fed sham-operated mice. Insulin sensitivity was estimated through intra-peritoneal insulin (ipITT) and glucose tolerance (ipGTT) tests. Anthropometric (body weight, lean and fad pad mass) and metabolic parameters (glycemia, insulin, cholesterol, triglycerides) were measured. The phosphorylation of a key protein of insulin signaling pathway (protein kinase B, PKB/Akt) was studied by Western blot. The intra-muscular and intra-hepatic lipids were extracted using Chloroform-Methanol (2:1, v/v). The CKD mice exhibited a marked decrease in insulin sensitivity (−76%, p p p p p In subtotally nephrectomized mouse model we showed an ectopic intramuscular and intrahepatic lipid redistribution concomitant with insulin resistance. Insulin resistance and lipotoxicity may represent the missing links (beyond the classical cardiovascular risk factors) that may help explain the increased risk of cardiovascular disease in CKD.

Steam-Dried Ginseng Berry Fermented with Lactobacillus plantarum Controls the Increase of Blood Glucose and Body Weight in Type 2 Obese Diabeticdb/dbMice

This study examined whether steam-dried ginseng berries fermented with Lactobacillus plantarum (FSGB) could improve the indices of type 2 diabetes mellitus (T2DM) in obese db/db mice. FSGB was shown to have an effect on body weight and blood glucose/serum parameters when administered at a dose of 0.5 g/kg. In the intraperitoneal glucose tolerance test (IPGTT) and insulin tolerance test (ITT), FSGB was clearly shown to improve insulin tolerance and glucose tolerance. Moreover, FSGB was shown to enhance immune activities by increasing the immune cell population, and glucose transpoter 1 (GLUT1) mRNA expression in L6 cells was up-regulated, suggesting that FSGB can increase glucose transport activity in target cells. These results indicate that steam- and dry-processed ginseng berries fermented with L. plantarum can be used to effectively control blood sugar metabolism via improving insulin and glucose tolerance and body weight gain in db/db mice.

Serine/threonine protein phosphatase 5 regulates glucose homeostasis in vivo and apoptosis signalling in mouse pancreatic islets and clonal MIN6 cells

During the development of type 2 diabetes mellitus, beta cells are often exposed to a high glucose/hyperlipidaemic environment, in which the levels of reactive oxygen species (ROS) are elevated. In turn, ROS can trigger an apoptotic response leading to beta cell death, by activating mitogen-activated protein kinase (MAPK) signalling cascades. Here we test the hypothesis that serine/threonine protein phosphatase 5 (PP5) acts to suppress proapoptotic c-Jun N-terminal kinase (JNK) signalling in beta cells. Ppp5c(-/-) and Ppp5c(+/+) mice were subjected to intraperitoneal glucose (IPGTT) or insulin tolerance tests. Pancreatic islets from Ppp5c(-/-) and Ppp5c(+/+) mice or MIN6 cells treated with short-interfering RNA targeting PP5 were exposed to palmitate or H(2)O(2) to activate MAPK signalling. Changes in protein phosphorylation, mRNA expression, apoptosis and insulin secretion were detected by western blot analysis, quantitative RT-PCR or ELISA. Ppp5c(-/-) mice weighed less and exhibited reduced fasting glycaemia and improved glucose tolerance during IPGTT, but retained normal insulin sensitivity and islet volume. Comparison of MAPK signalling in islets from Ppp5c(-/-) mice and MIN6 cells revealed that the lack of PP5 was associated with enhanced H(2)O(2)-induced phosphorylation of JNK and c-Jun. Cells with reduced PP5 also showed enhanced JNK phosphorylation and apoptosis after palmitate treatment. PP5 suppression in MIN6 cells correlated with hypersecretion of insulin in response to glucose. PP5 deficiency in mice is associated with reduced weight gain, lower fasting glycaemia, and improved glucose tolerance during IPGTT. At a molecular level, PP5 helps suppress apoptosis in beta cells by a mechanism that involves regulation of JNK phosphorylation.

C57BLKS/J-db/db 마우스에서 흑삼의 항당뇨 효과

SUMMARY AND CONCLUSION This study was designed for the comparison of anti-diabetic effect between white (WG) and black ginseng (BG) in C57BLKS/ J-db/db mice. Six-weeks-old mice male db/db mice were administrated with once daily 300 ㎎/㎏ of each of WG and BG for 6 weeks, db/m mice as normal group and db/db mice as diabetic positive group were fed without treatment of WG and BG. For finding out anti-diabetic effect, food consumption, body weight gain, oral glucose tolerance test (OGTT), intraperitoneal insulin tolerance test (IPITT) and blood level of glucose and insulin were examined. The results were summarized by comparing the results getting from db/db mice administrating WG and BG with those of diabetic positive group for 6 weeks. BG treatment group showed more significant differences on fasting blood glucose, suppression level against increasing blood insulin com-pared with that of WG group. From above results, BG has better anti-diabetic activity than that of WG. REFERENCES

Generation and characterization of a mouse model of the metabolic syndrome: apolipoprotein E and aromatase double knockout mice

The aim of this study was to create a comprehensive mouse model of the metabolic syndrome by crossing aromatase-deficient (ArKO) mice with apolipoprotein E-deficient (ApoE(-/-)) mice. Successive crossbreeding of ArKO with ApoE(-/-)-deficient mice generated double knockout, MetS-Tg mice. The phenotypic characteristics of the MetS-Tg mice were assessed at 3, 6, and 12 mo of age and compared with age- and sex-matched wild-type (WT) controls. Blood pressure and heart rate were recorded by a noninvasive, computerized tail-cuff system. Oral glucose and intraperitoneal insulin tolerance tests were performed. Serum cholesterol levels were measured by a combined quantitative colorimetric assay. Plasma adiponectin, C-reactive protein (CRP), insulin, interleukin-6 (IL-6), leptin, resistin, and tumor necrosis factor-α (TNF-α) were measured by multiplexed ELISA. MetS-Tg mice displayed significantly increased body weight, central obesity, and elevated blood pressure at all three ages compared with WT mice. Elevated serum cholesterol was associated with higher triglycerides and LDL/VLDL cholesterol particles and was accompanied by a decrease in HDL and histological evidence of fatty liver. MetS-Tg mice of all ages showed impaired glucose tolerance. At 12 mo, MetS-Tg mice had elevated plasma levels of CRP, IL-6, leptin, and TNF-α, but resistin levels were largely unchanged. We now report that this combination of gene knockouts produces a novel strain of mice that display the diverse clinical features of the metabolic syndrome, including central obesity, progressive hypertension, an adverse serum lipid profile, fatty liver, glucose intolerance, insulin resistance, and evidence of an inflammatory state.