Glucose Uptake In Tissue Research Articles

High-fructose feeding suppresses cold-stimulated brown adipose tissue glucose uptake independently of changes in thermogenesis and the gut microbiome

SummaryDiets rich in added sugars are associated with metabolic diseases, and studies have shown a link between these pathologies and changes in the microbiome. Given the reported associations in animal models between the microbiome and brown adipose tissue (BAT) function, and the alterations in the microbiome induced by high-glucose or high-fructose diets, we investigated the potential causal link between high-glucose or -fructose diets and BAT dysfunction in humans. Primary outcomes are changes in BAT cold-induced thermogenesis and the fecal microbiome (clinicaltrials.gov, NCT03188835). We show that BAT glucose uptake, but not thermogenesis, is impaired by a high-fructose but not high-glucose diet, in the absence of changes in the gastrointestinal microbiome. We conclude that decreased BAT glucose metabolism occurs earlier than other pathophysiological abnormalities during fructose overconsumption in humans. This is a potential confounding factor for studies relying on 18F-FDG to assess BAT thermogenesis.

Zinc(II) – Syringic acid complexation synergistically exerts antioxidant action and modulates glucose uptake and utilization in L-6 myotubes and rat muscle tissue

Zinc and syringic acid have metabolic and antioxidant medicinal potentials. A novel zinc(II)-syringic acid complex with improved anti-hyperglycaemic and antioxidant potential was developed. Zinc(II) was complexed with syringic acid in a 1:2 molar ratio and characterized using FT-IR, 1H NMR and LC-MS. Different experimental models were used to compare the anti-hyperglycaemic and antioxidant properties between the complex and precursors. A Zn(II)-bisyringate.2H2O complex was formed. The in vitro radical scavenging and Fe3+ reducing antioxidant, antiglycation, and α-glucosidase inhibitory activities of the complex were 1.8-5.2 folds stronger than those of the syringic acid precursor and comparable to those of the positive controls. The complex possessed an increased ability to inhibit lipid peroxidation (by 1.6-1.7 folds) and glutathione depletion (2.8-3 folds) relative to syringic acid in Chang liver cells and liver tissues isolated from rats. The complex exhibited a higher glucose uptake effect (EC50 =20.4 and 386µM) than its precursors (EC50 =71.1 and 6460µM) in L6-myotubes and psoas muscle tissues isolated from rats, respectively, which may be linked to the observed increased cellular zinc uptake potentiated by complexation. Tissue glucose uptake activity was accompanied by increased hexokinase activity, suggesting increased glucose utilization. Moreover, treatment increased tissue phospho-Akt/pan-Akt ratio. The complex had strong molecular docking scores than syringic acid with target proteins linked to diabetes. The presence of two syringic acid moieties and Zn(II) in the complex influenced its potency. The complex was not hepatotoxic and myotoxic in vitro. Zinc-syringic acid complexation may be a novel promising therapeutic approach for diabetes and oxidative complications.

Investigating Anti-diabetic Effects of Autoclaved Curcuma longa Linn (turmeric) Extracts using Mouse Tissues in vitro

Curcumin, the active compound found in turmeric, is believed to delay the development of diabetes through several mechanisms. This study aimed to investigate if an aqueous extract of turmeric can improve glucose uptake and uric acid in mouse tissues in vitro, after inclusion of turmeric in the diet for four weeks. Fourteen adult male Swiss mice were divided into three groups. The first group was the control (n=6) that was given clean water, the second group of mice (n=4) was given 5% autoclaved turmeric extract in drinking water, and the third group (n=4) was given 5% non-autoclaved turmeric extract in drinking water. After four weeks, the cardiac muscle, skeletal muscle, pancreas, and liver tissues were dissected and used for analysis. The results showed that the aqueous 5% turmeric extract reduced glucose in cardiac tissues while the plasma glucose was not changed. Cardiac muscle, liver, pancreas, and skeletal muscle showed glucose absorption after the 5% turmeric treatment. This research shows that turmeric did improve glucose uptake in most tissues, although it was not significant due to the limitations of this study. Tissues may need to be cultured longer and media processed quicker to prevent evaporation. Turmeric continues to show great potential in the treatment of type 2 diabetes and may present an alternative way of treating diabetes.

Brown-fat-mediated tumour suppression by cold-altered global metabolism

Glucose uptake is essential for cancer glycolysis and is involved in non-shivering thermogenesis of adipose tissues1–6. Most cancers use glycolysis to harness energy for their infinite growth, invasion and metastasis2,7,8. Activation of thermogenic metabolism in brown adipose tissue (BAT) by cold and drugs instigates blood glucose uptake in adipocytes4,5,9. However, the functional effects of the global metabolic changes associated with BAT activation on tumour growth are unclear. Here we show that exposure of tumour-bearing mice to cold conditions markedly inhibits the growth of various types of solid tumours, including clinically untreatable cancers such as pancreatic cancers. Mechanistically, cold-induced BAT activation substantially decreases blood glucose and impedes the glycolysis-based metabolism in cancer cells. The removal of BAT and feeding on a high-glucose diet under cold exposure restore tumour growth, and genetic deletion of Ucp1—the key mediator for BAT-thermogenesis—ablates the cold-triggered anticancer effect. In a pilot human study, mild cold exposure activates a substantial amount of BAT in both healthy humans and a patient with cancer with mitigated glucose uptake in the tumour tissue. These findings provide a previously undescribed concept and paradigm for cancer therapy that uses a simple and effective approach. We anticipate that cold exposure and activation of BAT through any other approach, such as drugs and devices either alone or in combination with other anticancer therapeutics, will provide a general approach for the effective treatment of various cancers.

637 Non-redundant roles for GLUT1 and GLUT3 in melanoma and primary melanocytes

The GLUT1 transporter mediates glucose uptake in most tissues and is upregulated in both inflammatory and malignant skin diseases. Most melanomas overexpress both GLUT1 and GLUT3, but it is unclear whether the closely related transporters are functionally redundant. Consistent with its function in keratinocytes, GLUT1 knockdown in melanoma cells (UACC-62 and Mel-juso) inhibited glucose uptake and cell proliferation. Notably, GLUT3 knockdown did not impair glucose transport yet showed even more dramatic effects on cell proliferation and morphology. Fractionation revealed the preferential localization of GLUT1 to the plasma membrane while GLUT3 preferentially localized to endosomes. RNA-sequencing, Western blotting, and immunofluorescence revealed an essential role for GLUT3 in signal transducer and activator of transcription 3 (STAT3) activation, which has been implicated in melanoma growth and metastasis. Deletion of GLUT1 or GLUT3 in primary mouse melanocytes through Tyrosinase-cre expression confirmed a critical role for GLUT3 in STAT3 activation and non-redundant roles for GLUT1 and GLUT3 in pigmentation and melanocyte proliferation ex vivo. These studies identify unique functions for GLUT1 and GLUT3 in melanoma and melanocytes and highlight the GLUT3-STAT3 signaling axis as a potential therapeutic target in melanoma.

The Molecular Effects of BDNF Synthesis on Skeletal Muscle: A Mini-Review.

The brain-derived neurotrophic factor (BDNF) is a member of the nerve growth factor family which is generated mainly by the brain. Its main role involve synaptic modulation, neurogenesis, neuron survival, immune regulation, myocardial contraction, and angiogenesis in the brain. Together with the encephalon, some peripheral tissues synthesize BDNF like skeletal muscle. On this tissue, this neurotrophin participates on cellular mechanisms related to muscle function maintenance and plasticity as reported on recent scientific works. Moreover, during exercise stimuli the BDNF contributes directly to strengthening neuromuscular junctions, muscle regeneration, insulin-regulated glucose uptake and β-oxidation processes in muscle tissue. Given its vital relevance on many physiological mechanisms, the current mini-review focuses on discussing up-to-date knowledge about BDNF production in skeletal muscle and how this neurotrophin impacts skeletal muscle biology.

Regenerating islet-derived protein 3α: A promising therapy for diabetes. Preliminary data in rodents and in humans

The aim of our study was to test the hypothesis that administration of Regenerating islet-derived protein 3α (Reg3α), a protein described as having protective effects against oxidative stress and anti-inflammatory activity, could participate in the control of glucose homeostasis and potentially be a new target of interest in the treatment of type 2 diabetes. To that end the recombinant human Reg3α protein was administered for one month in insulin-resistant mice fed high fat diet. We performed glucose and insulin tolerance tests, assayed circulating chemokines in plasma and measured glucose uptake in insulin sensitive tissues. We evidenced an increase in insulin sensitivity during an oral glucose tolerance test in ALF-5755 treated mice vs controls and decreased the pro-inflammatory cytokine C-X-C Motif Chemokine Ligand 5 (CXCL5). We also demonstrated an increase in glucose uptake in skeletal muscle. Finally, correlation studies using human and mouse muscle biopsies showed negative correlation between intramuscular Reg3α mRNA expression (or its murine isoform Reg3γ) and insulin resistance. Thus, we have established the proof of concept that Reg3α could be a novel molecule of interest in the treatment of T2D by increasing insulin sensitivity via a skeletal muscle effect.

Kalirin mediates Rac1 activation downstream of calcium/calmodulin-dependent protein kinase II to stimulate glucose uptake during muscle contraction.

In this study, we investigated the role of calcium/calmodulin-dependent protein kinase II (CaMKII) in contraction-stimulated glucose uptake in skeletal muscle. C2C12 myotubes were contracted by electrical pulse stimulation (EPS), and treadmill running was used to exercise mice. The activities of CaMKII, the small G protein Rac1, and the Rac1 effector kinase PAK1 were elevated in muscle by running exercise or EPS, while they were lowered by the CaMKII inhibitor KN-93 and/or small interfering RNA (siRNA)-mediated knockdown. EPS induced the mRNA and protein expression of the Rac1-GEF Kalirin in a CaMKII-dependent manner. EPS-induced Rac1 activation was lowered by the Kalirin inhibitor ITX3 or siRNA-mediated Kalirin knockdown. KN-93, ITX3, and siRNA-mediated Kalirin knockdown reduced EPS-induced glucose uptake. These findings define a CaMKII-Kalirin-Rac1 signaling pathway that contributes to contraction-stimulated glucose uptake in skeletal muscle myotubes and tissue.

Adipocyte-specific ablation of the Ca2+ pump SERCA2 impairs whole-body metabolic function and reveals the diverse metabolic flexibility of white and brown adipose tissue

ObjectiveSarco/endoplasmic reticulum Ca2+-ATPase (SERCA) transports Ca2+ from the cytosol into the endoplasmic retitculum (ER) and is essential for appropriate regulation of intracellular Ca2+ homeostasis. The objective of this study was to test the hypothesis that SERCA pumps are involved in the regulation of white adipocyte hormone secretion and other aspects of adipose tissue function and that this control is disturbed in obesity-induced type-2 diabetes. MethodsSERCA expression was measured in isolated human and mouse adipocytes as well as in whole mouse adipose tissue by Western blot and RT-qPCR. To test the significance of SERCA2 in adipocyte functionality and whole-body metabolism, we generated adipocyte-specific SERCA2 knockout mice. The mice were metabolically phenotyped by glucose tolerance and tracer studies, histological analyses, measurements of glucose-stimulated insulin release in isolated islets, and gene/protein expression analyses. We also tested the effect of pharmacological SERCA inhibition and genetic SERCA2 ablation in cultured adipocytes. Intracellular and mitochondrial Ca2+ levels were recorded with dual-wavelength ratio imaging and mitochondrial function was assessed by Seahorse technology. ResultsWe demonstrate that SERCA2 is downregulated in white adipocytes from patients with obesity and type-2 diabetes as well as in adipocytes from diet-induced obese mice. SERCA2-ablated adipocytes display disturbed Ca2+ homeostasis associated with upregulated ER stress markers and impaired hormone release. These adipocyte alterations are linked to mild lipodystrophy, reduced adiponectin levels, and impaired glucose tolerance. Interestingly, adipocyte-specific SERCA2 ablation leads to increased glucose uptake in white adipose tissue while the glucose uptake is reduced in brown adipose tissue. This dichotomous effect on glucose uptake is due to differently regulated mitochondrial function. In white adipocytes, SERCA2 deficiency triggers an adaptive increase in fibroblast growth factor 21 (FGF21), increased mitochondrial uncoupling protein 1 (UCP1) levels, and increased oxygen consumption rate (OCR). In contrast, brown SERCA2 null adipocytes display reduced OCR despite increased mitochondrial content and UCP1 levels compared to wild type controls. ConclusionsOur data suggest causal links between reduced white adipocyte SERCA2 levels, deranged adipocyte Ca2+ homeostasis, adipose tissue dysfunction and type-2 diabetes.

Protein Tyrosine Phosphatase 1B Deficiency Improves Glucose Homeostasis in Type 1 Diabetes Treated With Leptin.

Leptin, a hormone secreted by adipocytes, exhibits therapeutic potential for the treatment of type 1 diabetes (T1D). Protein tyrosine phosphatase 1B (PTP1B) is a key enzyme that negatively regulates leptin receptor signaling. Here, the role of PTP1B in the treatment of T1D was investigated using PTP1B-deficient (knockout [KO]) mice and a PTP1B inhibitor. T1D wild-type (WT) mice induced by streptozotocin showed marked hyperglycemia compared with non-T1D WT mice. KO mice displayed significantly improved glucose metabolism equivalent to non-T1D WT mice, whereas peripheral or central administration of leptin partially improved glucose metabolism in T1D WT mice. Peripheral combination therapy of leptin and a PTP1B inhibitor in T1D WT mice improved glucose metabolism to the same level as non-T1D WT mice. Leptin was shown to act on the arcuate nucleus in the hypothalamus to suppress gluconeogenesis in liver and enhance glucose uptake in both brown adipose tissue and soleus muscle through the sympathetic nervous system. These effects were enhanced by PTP1B deficiency. Thus, treatment of T1D with leptin, PTP1B deficiency, or a PTP1B inhibitor was shown to enhance leptin activity in the hypothalamus to improve glucose metabolism. These findings suggest a potential alternative therapy for T1D.

Clinical use of cardiac 18F-FDG viability PET: a retrospective study of 44 patients undergoing post-test revascularization.

The coupling between coronary artery disease and the development of ischemic heart failure is well-established. For these patients, assessment of potentially viable but dysfunctional myocardial tissue (hibernation) is considered critical to guide optimal surgical treatment. Assessment with positron emission tomography (PET) theoretically provides measurements of hibernating tissue and maximal myocardial glucose uptake (MGU) in all cardiac territories. However, the clinical benefits of these measures are not thoroughly studied. We therefore aimed to investigate whether cardiac viability testing with combined Rubidium-82 (82Rb) and 18F-fluorodeoxyglucose (18F-FDG) predicts post-intervention improvement in left ventricle ejection fraction (LVEF) and survival. This retrospective study consisted of 131 patients with ischemic heart failure referred for dynamic 82Rb/18F-FDG PET viability testing prior to revascularization. The FDG viability scan was done during a hyperinsulinemic-euglycemic clamp and included PET measures static FDG hibernation and absolute MGU as well as myocardial blood flow and coronary flow reserve. In total, 44/131 patients undergoing viability testing were subsequently revascularized. Following revascularization, 26 patients had LVEF improvement of at least 5% while 18 patients had no improvement. A poor correlation between areas of intervention and areas of hibernation was observed. Receiver operating characteristics for all PET metrics did not predict improvement in LVEF. Furthermore, hibernation failed to predict survival regardless of whether patients underwent subsequent revascularization. Dynamic viability PET metrics (hibernation and MGU) do not predict post-intervention improvement in LVEF or overall survival in ischemic heart failure patients undergoing revascularization. In a clinical setting, the value of these measurements may therefore be limited. Kindly check and confirm the Given names and Family names for all the authors.All names are correct!

Differential Changes in Circulating Steroid Hormones in Hibernating Brown Bears: Preliminary Conclusions and Caveats.

Brown bears are obese when they enter the den, and after 6 mo of hibernation and physical inactivity, bears show none of the adverse consequences of a sedentary lifestyle in humans, such as cardiovascular disease, type 2 diabetes, and kidney failure. The metabolic mechanisms that drive hibernation physiology in bears are poorly defined, but systemic endocrine regulators are likely involved. To investigate the potential role of steroid hormones, we quantified the total levels of 12 steroid hormones, the precursor cholesterol, sex hormone-binding globulin (SHBG), and corticosterone-binding globulin (CBG) in paired serum samples from subadult free-ranging Scandinavian brown bears during the active and hibernation states. During hibernation, androstenedione and testosterone were significantly decreased in subadult female bears (), whereas they increased in all males but one () and therefore did not reach a significant difference. Despite this difference, SHBG increased more than 20-fold during hibernation for all bears. Compared with SHBG concentrations in humans, bear levels were very low in the active state, but during hibernation, levels equaled high levels in humans. The increased SHBG levels likely maintain a state of relative quiescence of the reproductive hormones in hibernating bears. Interestingly, the combination of SHBG and testosterone levels results in similar free bioavailable testosterone levels of 70-80 pM in both subadult and adult sexually active male bears, suggesting a role for SHBG in controlling androgen action during hibernation in males. Dehydroepiandrosterone sulfate, dihydrotestosterone, and estradiol levels were below the detection limit in all but one animal. The metabolically active glucocorticoids were significantly higher in both sexes during hibernation, whereas the inactive metabolite cortisone was reduced and CBG was low approaching the detection limit. A potential caveat is that the glucocorticoid levels might be affected by the ketamine applied in the anesthetic mixture for hibernating bears. However, increased hibernating cortisol levels have consistently been reported in both black bears and brown bears. Thus, we suggest that high glucocorticoid activity may support the hibernation state, likely serving to promote lipolysis and gluconeogenesis while limiting tissue glucose uptake to maintain a continuous glucose supply to the brain.

299-OR: Molecular and Physiological Consequences of the Diabetes-Related PGC1A Gly482Ser Polymorphism

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1A) is a nuclear transcriptional coregulator that plays a major role in the control of metabolism and mitochondrial biogenesis. We showed that a diabetes-linked single nucleotide polymorphism (SNP rs8192678) within the coding region of PPARGC1A gene (Gly482Ser) results in decreased protein stability and half-life in liver and beta-cell lines and human induced pluripotent stem cells (iPSCs) . Our mass spectrometry data suggest that degradation of the S482 variant is mediated by phosphorylation at amino acid 482 when a serine is present. A kinome screen identified three potential kinases (NEK2, MARK4 and S6K2) that can modify this site. We found that mutation of the mouse homolog at the conserved site (serine to glycine) similarly stabilized mouse PGC1A. To study the physiological consequences of this SNP, we generated whole-body homozygous glycine (G/G) , serine (S/S) and heterozygous (S/G) mice. We analyzed various metabolic parameters in male (N=10-per genotype) and female (N=8-9) mice subjected to standard chow or high fat, high fructose diet (HFHF) for 14 or 24 weeks. We found that G/G male and female mice had increased caloric intake using metabolic cages without increased body weight. Male mice on a HFHF diet carrying a glycine allele (G/G or S/G) were more resistant to insulin in an insulin tolerance test (ITT) , secreted less insulin in response to a mixed-meal challenge and had decreased glucose uptake in muscle and adipose tissue. In line in humans, non-diabetic subjects with G/G (N=20) or G/S (N=22) variants oxidize more fat while those with S/S variant (N=6) oxidize more carbohydrate over 6-hours following the ingestion of a high-fat meal (68% fat, 18% carbohydrate) . In summary, these results demonstrate that differences in PGC1A stability associated with phosphorylation at site 482 may lead to differences in glucose and fat metabolism, which could explain the link between this SNP and metabolic diseases. Disclosure M.Galipeau: None. M.Faraj: None. M.Oeffinger: None. F.C.Lynn: None. R.A.Screaton: None. T.Alquier: None. J.L.Estall: None. N.Jouvet: None. E.Courty: None. R.Vandenbeek: None. N.P.Khan: None. K.Bouyakdan: None. C.Nian: None. C.Iorio: None. D.D.Scott: None. Funding CIHR (PJT-148771) CIHR (PJT-168853)

824-P: Dual Amylin and Calcitonin Receptor Agonists Improve Insulin Sensitivity and Increase Tissue-Specific Glucose Uptake Independent of Weight Loss

Dual amylin and calcitonin receptor agonists (DACRAs) are known to induce a significant weight loss and improve glucose tolerance and glucose control in rats. However, it is unknown if DACRAs has an insulin sensitizing effect beyond that induced by weight loss and if DACRAs affect tissue specific glucose uptake. Additionally, clamp studies with DACRAs have not previously been performed in diabetic rats. Pre-diabetic ZDSD and diabetic ZDF rats were treated with the DACRA KBP-088 (1.5 nmol//kg, s.c.) for 12 days, and a hyperinsulinemic clamp was conducted on day 13, 24 h post-dosing. In ZDSD rats a hyperinsulinemic euglycemic clamp was carried out, while a hyperinsulinemic isoglycemic clamp was carried out in ZDF rats. In addition, specific glucose uptake was assessed during a hyperinsulinemic isoglycemic clamp in ZDF rats. In ZDSD rats, KBP-088 treatment resulted in a significant reduction in body weight and fasting blood glucose, and improved insulin sensitivity by increasing the glucose infusion rate (GIR) (vehicle: 8.6, KBP-088: 12 mg glucose/kg/min) . In ZDF rats, KBP-088 significantly reduced fasting blood glucose and improved insulin sensitivity (GIR, vehicle: 1.5, KBP-088: 16.5 mg glucose/kg/min) , independent on weight loss. In both studies, KBP-088 increased the rate of glucose clearance, likely be increasing glucose storage, but without altering the endogenous glucose production. Direct assessment of tissue specific glucose uptake showed, that KBP-088 significantly increased glucose uptake in both muscles and adipose tissues when compared to vehicle. In summary, KBP-088 significantly improved insulin sensitivity in both pre-diabetic and diabetic rats and markedly increased tissue specific glucose uptake. Importantly, KBP-088 has an insulin sensitizing effect independent of weight loss, highlighting DACRAs as promising agents for treatment of diabetes. Disclosure A.T.Larsen: Employee; Nordic Bioscience. N.Sonne: None. E.Bredtoft: None. M.A.Karsdal: Employee; Nordic Bioscience A/S, Nordic Bioscience A/S, Nordic Bioscience A/S. K.Henriksen: Employee; Nordic Bioscience A/S, Stock/Shareholder; Nordic Bioscience A/S.

201-LB: Overexpression of GOT1 in Brown Adipose Tissue Enhances Thermogenesis and Glucose Metabolism by Activating the Malate-Aspartate Shuttle

Brown adipose tissue (BAT) is characterized by thermogenic and glucose-consuming properties. BAT takes up large amounts of circulating glucose during cold exposure or pharmacological stimulation of β3-adrenergic receptors (β3AR) , but glucose oxidation in mitochondria only modestly contributes as a fuel source for thermogenesis. How glucose metabolism supports thermogenesis is incompletely understood. Here, we identify a novel role of the malate-aspartate shuttle (MAS) in enhancing thermogenesis, glucose uptake and glycolysis in brown adipose tissue. We found that glutamic-oxaloacetic transaminase 1 (GOT1) , a key enzyme of the MAS, exists at very low levels in BAT but is markedly induced by cold or β3AR agonists, while other MAS enzymes (GOT2 and MDH1/2) remain unchanged. Enforced expression of Got1 in BAT increased energy expenditure in mice and further enhanced thermogenesis upon cold exposure or β3-adrenergic stimulation. Moreover, mice overexpressing Got1 in BAT exhibited enhanced glucose tolerance. Mechanistically, Got1 overexpression stimulated mitochondrial uncoupled respiration. MAS-driven thermogenesis in turn led to AMPK activation, which likely explains enhanced glucose uptake and glycolysis. Collectively, our data demonstrate a novel GOT1-MAS-AMPK axis that regulates thermogenesis and glucose metabolism in cold-activated BAT. Disclosure C. Park: None. H. Cheng: None. S. R. Lee: None. K. Eilertsen: None. J. Chang: None. Funding NIH (DK104748, 1P30GM118430, P30DK072476)

Antidiabetic activities of menthone on insulin resistant in 3T3-L1 adipocytes

Background: Diabetes mellitus (DM) is a metabolic disorder characterised by chronic hyperglycaemia and metabolic consequences caused by insulin defects. Adipose tissue is an endocrine organ that influences glucose and lipid metabolism by releasing adipokines; adipose tissue is vital for the life of mammals. It represents the major source of fatty acid. Brown adipose tissue (BAT) and white adipose tissue (WAT) are the basic adipose tissue forms. They have different functions and cellular compositions and localization. They are essentially adversarial in terms of functionality. WAT is known to contain the most body fat; its involvement in the storage of excess dietary triglycerides. It is the source of free fatty aid used as energy substrates for the generation through oxidative phosphate of (ATP) high-energy bonds. During insulin resistance, the secretion of the hormone from the pancreatic islet cells cannot trigger glucose uptake in metabolic tissues, leading to elevated blood glucose and insulin levels. Menthone is cyclic monoterpenes and is reported to have several biological activities. This study, explores the potential antidiabetic effects invitro of menthone in the 3T3L1 adipocytes. Methods: The differentiation of 3T3-L1 preadipocytes into mature adipocytes were cultured and maintained.

The Effect of GLP-1 and GIP on the Microvascular Blood Flow after Consuming a Mixed Nutrient Meal: A Research Protocol

Introduction: Nutrient and gas exchange via microvascular blood flow is a key process of circulatory function. There is a significant decrease in the microvascular blood flow to skeletal muscle after orally ingesting glucose. Incretins like glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP), are released in response to glucose in the gut, stimulating insulin release. Incretins roles in promoting glucose uptake is thought to impact vascular blood flow. Our protocol plans to investigate if incretins and the subsequent insulin release contribute to the decrease in microvascular blood flow. Methods: 20 healthy young adults will consume a high glucose mixed nutrient meal. Using contrast-enhanced ultrasound (CEU) and a blood glucose meter, microvascular blood flow and blood glucose will be measured. Blood GLP-1 and GIP will be measured using a sandwich enzyme immunoassay, while an electrochemiluminescence technique using an autoanalyzer will measure insulin. Measurements will be recorded at 0, 1, and 2 hours post-prandial. In a randomized order, the protocol will be repeated with infusion of GIP and GLP-1 inhibitors, GIP(3-30)NH2 and exendin(9-39)NH2 or saline. Results: With normal incretin secretion, we anticipate a significant decrease in microvascular blood flow, along with an increase in blood insulin, GIP/GLP-1 levels. We postulate that supressing incretins will increase the microvascular blood flow along with decreased plasma insulin and no change in GLP-1/GIP levels. Discussion: Through our methods, we propose a study design which evaluates the relationship of incretins and insulin on post-prandial microvascular blood flow. Our expected results aim to provide data that can be applied to the progressive treatment of type II diabetes with incretins like GLP-1. Understanding the impact of incretin treatment on the microvascular blood flow could be beneficial to the discovery of an adverse effect or how glucose uptake in peripheral tissues is altered. These are vital aspects of developing a clinical treatment to diabetes and our results will provide a basis to work off. Conclusion: The goal of this protocol was to investigate and provide insight to fully understand incretins and their effects. It will propel research on the biochemical pathways involving incretin and microvascular blood flow, which then helps progress treatment of complications like diabetes.

FC028: Characterization of Adipocyte Size and Glucose Uptake in Adipose Tissue with Focus on Different Perirenal Fat Depots

Abstract BACKGROUND AND AIMS Previous studies have suggested that the anatomical location of adipose tissue, and the characteristics of the adipocytes regulating adipose tissue function may be of importance for normal renal function and disease. However, in humans, the adipocyte size and metabolism of the fat depots surrounding the kidney have not been thoroughly characterized. The aim of this study was therefore to characterize adipocyte size and glucose uptake in human perirenal, renal sinus and paranephric adipose tissue. SUBJECTS AND METHODS A total of 25 healthy kidney donors [13 (50%) men, age 48 ± 11 years and BMI 25.7 ± 3.1 kg/m2] were included. Perirenal, renal sinus, paranephric, omental and subcutaneous adipose tissue were collected during laparoscopic unilateral nephrectomy. Adipocyte diameter, basal glucose uptake (no insulin) and insulin-stimulated glucose uptake (25 and 1000 µU/mL) were measured in isolated adipocytes from the different tissues. RESULTS The mean adipocyte cell diameters in the renal fat depots (perirenal, renal sinus and paranephric) were smaller than those in omental and subcutaneous tissue (mean ± sd; 69.3 ± 15.5, 65.5 ± 13.5 and 75.9 ± 16.5 versus 80.3 ± 20.5 and 85.5 ± 16.7 µm, respectively) with adipocytes from the renal sinus fat depot having the smallest cell diameter. Detailed data are displayed in Fig. 1. There were no significant gender differences in cell size and adipocyte size from the different depots did not correlate with body mass index (BMI). Insulin resistance index (HOMA-IR) correlated positively and significantly to adipocyte size in the omental (r = 0.607; P = 0.008), perirenal (r = 0.443; P = 0.027) and paranephric (r = 0.479; P = 0.015) depots. Insulin (both with 25 and 1000 µU/mL) significantly up-regulated glucose uptake in subcutaneous (1.6 and 1.9-fold; P < 0.05), perirenal (1.7 and 2.0-fold; P < 0.01) and paranephric (1.5 and 1.6-folds; P < 0.01) adipocytes, compared with basal (no insulin) as shown in Fig. 2. Interestingly, glucose uptake per cell surface was higher in renal sinus than omental adipocytes (basal (no insulin) 1.2-fold; P < 0.001, physiological (25 µU/mL) and supraphysiological (1000 µU/mL) both 1.3-fold higher; P < 0.001) than omental adipocytes (comparison not shown). CONCLUSION This study in healthy kidney donors indicate differences in different fat depots surrounding the kidney that may be of importance for renal function and disease. The fat depot in the renal sinus, with the smallest adipocytes and potentially a higher glucose uptake, is of specific interest. Detailed metabolic characterization of these fat depots is ongoing. Comparison of adipocyte diameter between the different adipose tissue depots: subcutaneous (n = 24), omental (n = 18), perirenal (n = 25), renal sinus (n = 21) and paranephric adipose tissue (n = 25); Values are mean with SEM as data were normally distributed. **P < 0.01 and ***P < 0.001. Physiological and supraphysiological effect of insulin (25 and 1000 µU/mL) on glucose uptake compared with basal (no insulin) by cell surface in adipocytes isolated from subcutaneous (n = 6), omental (n = 3), perirenal (n = 21), renal sinus (n = 4) and paranephric (n = 18) adipose tissue depots, respectively. Values are median and interquartile range as data were not normally distributed. *P < 0.05, **P < 0.01.

Effect of adrenalectomy and insulin resistance on non‐shivering thermogenesis in the corpulent rat

Glucocorticoid hormones have been reported to impede optimal insulin sensitivity and glucose uptake in peripheral tissues via interactions with GLUT transporters, leading to insulin resistance and impaired glucose uptake via GLUT transporters. The LA/Ntul//‐cp rat expresses obesity in 25% of the offspring by 5 to 6 weeks of age but remains non diabetic throughout much if not all of its lifespan when normally reared. Groups of congenic lean and obese LA/Ntul//‐cp rats were fed low glycemic Purina Chow diets from 6 to 9 weeks of age or overfed with a high energy cafeteria diet (Café) from 9 until 12 weeks of age. Subgroups of obese animals were adrenalectomized (ADX) at 6 weeks of age (WoA) and subjected to the same dietary regimen to determine if the Café overfeeding could enhance the normal thermic response to norepinephrine (NE) in the obese phenotype and to determine if ADX would result in a restoration of glycemic status and NE‐induced thermogenesis in the obese phenotype. Measures of Oral Glucose Tolerance (OGT), Area under the glucose curve (AUC), and NE‐stimulated VO2 were determined (NE, 200 µg, s.c.) at 6, 9 and 12 WoA in all treatment groups and Insulin:Glucose ratios (I:G) at 12 WoA. Obese animal demonstrated hyperphagia at all ages studied, and Obese ADX hyperphagia from 9 to 12 WoA. OGT and AUC indicated modest glucose intolerance in the obese phenotype, and which was restored following ADX at 6 and 9 WoA. NE resulted in a progressive increase in VO2 in lean rats at each age studied, but NE‐stimulated VO2 was lower in the obese phenotype and decreased further after the Café feeding regimen. ADX was associated with a restoration of OGT, I:G and NE stimulated VO2 equivalent to that observed in lean animals at 12 weeks of age. These results are consistent with adrenocorticoid‐mediated insulin resistance likely due to a receptor level defect in insulin sensitivity as a contributory factor in the impairment in OGT and NST in the obese phenotype of this strain.

Hepatic Stearoyl‐CoA desaturase deficiency‐mediated induction of the insulin‐like growth factor‐binding protein 1 requires FGF21

Stearoyl‐CoA desaturase‐1 (SCD1) catalyzes the rate‐limiting step in the biosynthesis of monounsaturated acids and is a key regulator of systemic glucose metabolism. Hepatic deletion of Scd1protects mice from high‐carbohydrate diet (HCD)‐induced hepatic steatosis and adiposity in part by suppressing hepatic lipogenesis, increasing adipose tissue lipogenesis, and increasing systemic glucose uptake. However, the mechanism leading to these phenotypes is unclear. Given that high carbohydrate diets can lead to chronic metabolic diseases such as obesity, diabetes, and hepatic steatosis, it is critical to understand how SCD1 deficiency alters metabolic pathways to produce metabolically beneficial phenotypes. Here we show that hepatic SCD1 deficiency enhances tissue glucose uptake and is correlated with dramatic increases in the expression and plasma levels of the fibroblast growth factor 21 (FGF21), and Insulin growth factor binding protein‐1 (IGFBP1), both liver derived insulin‐sensitizing hormones that are known to regulate whole body lipid and glucose homeostasis. Feeding both male and female LKO mice with triolein, but not tristearin, supplemented HCD reduced Fgf21 and Igfbp1 expression and restored plasma glucose levels. Inhibition of SCD activity in primary hepatocytes induced the expression of Fgf21 and Igfbp1 which was repressed by treatment with oleate but not stearate. Moreover, we show that the hepatic stearoyl‐CoA desaturase deficiency‐mediated induction of the Igfbp1 is through the oleate‐FGF21 axis.