Decrease In Glucose Infusion Rate Research Articles

Continuous subcutaneous insulin infusion via an insulin pump in extremely premature neonates—a case series

Extremely preterm infants are prone to hyperglycemia which is associated with increased mortality and morbidity. Insulin sensitivity is variable in extreme prematurity, and its monitoring, prevention, and treatment are a significant challenge in the NICU. Frequent changes in fluid composition and volumes, as well as large growth and adaptational nutrient requirements are limited by difficult vascular access and blood sampling and risk of drug incompatibilities. Insulin treatment requires specific access and significantly increases fluid intake and sampling. Clinicians, therefore, often compromise by reducing glucose intake and accepting higher glycemia. We report a case series of 11 extremely low birth weight (ELBW) preterms, born between 23 5/7 and 27 6/7 weeks of gestation, treated for transient hyperglycemia during the first 2 weeks of life by continuous subcutaneous insulin infusion (CSII). Insulin concentration was 10 IU/ml, administered via 13 mm Accu-Chek® Tenderlink catheters and a commercial insulin pump (Accu-Chek® Combo, Roche Diabetes Care). Insulin treatment was initiated when glycemia was > 252 mg/dL (14 mmol/l) in two consecutive blood glucose determinations, except for one case when glycemia was 234 mg/dL (13 mmol/l), despite a previous decrease in glucose infusion rate. The starting dose for the CSII was between 0.01 and 0.08 IU/kg/h. The average duration of the CSII was 5 days (1–16 days). CSII in extreme preterm neonates with hyperglycemia was clinically feasible and practical by sparing IV lines and volume and appeared as more rapidly effective than continuous IV administration. No adverse events like hypoglycemia or skin infection were recorded.

Efficacy of Dose-Titrated Glucagon Infusions in the Management of Congenital Hyperinsulinism: A Case Series.

Background: Congenital hyperinsulinism (CHI), a rare disease of excessive and dysregulated insulin secretion, can lead to prolonged and severe hypoglycemia. Dextrose infusions are a mainstay of therapy to restore normal glycemia, but can be associated with volume overload, especially in infants. By releasing intrahepatic glucose stores, glucagon infusions can reduce dependency on dextrose infusions. Recent studies have reported positive outcomes with glucagon infusions in patients with CHI; however, to date, there are no reports describing the clinical utility of titrated doses of infused glucagon to achieve glycemic stability.Objective: To assess the potential clinical utility of dose-titrated glucagon infusions in stabilizing glycemic status in pediatric patients with CHI, who were managed by medical and/or surgical approaches.Methods: Patients with CHI (N = 33), with or without mutations in the ATP-sensitive K+ channel genes, ABCC8, and KCNJ11 requiring glucagon by dose titration in addition to intravenous dextrose and medical therapy with diazoxide/octreotide to achieve glycemic stability were recruited. Following glucagon titration and a 24-h glucose stable period, glucose infusion rate (GIR) was reduced over a 24-h period. Achievement of glycemic stability and decrease in GIR were considered end points of the study.Results: All patients achieved glycemic stability with glucagon infusion, demonstrating clinical benefit. GIR reduced from 15.6 (4.5) to 13.4 (4.6) mg/kg/min mean (SD) (p = 0.00019 for difference; n = 32; paired t-test) over 24 h. By univariate analysis, no individual baseline characteristic was associated with changes in the GIR. However, by baseline-adjusted modeling, mutational status of the patient (p = 0.011) was inversely associated with a reduction in GIR. Adverse events were infrequent with diarrhea possibly attributed to glucagon treatment in 1 patient. With long-term treatment following GIR reduction, necrolytic migratory erythema was observed in another patient.Conclusion: These data suggest that dose-titrated glucagon infusion therapy aids hypoglycemia prevention and reduction in GIR in the clinical management of patients with CHI.

120-OR: MicroRNA-7a-5p Overexpression in the VMH Restores the Sympathoadrenal Response to Hypoglycemia in Recurrently Hypoglycemic Rats

We tested the hypothesis that the impaired sympathoadrenal response induced by recurrent hypoglycemia (RH) is mediated by changes in key microRNA expression in the ventromedial hypothalamus (VMH). MicroRNA-sequencing data from the VMH of RH rats indicated a 67% downregulation of microRNA-7a-5p and a 2.3-fold upregulation of microRNA-665. Rescue experiments were conducted consisting of lentiviral-mediated overexpression of microRNA-7a-5p or downregulation of microRNA-665 targeted to the VMH. Rats were randomized to, 1) recurrent saline (RS), 2) RH (25-50 mg/dl x 3 days), 3) RH + Lenti-scrambled microRNA, or 4) RH + Lenti-targeted microRNA. All rats were subsequently subjected to hyperinsulinemic-hypoglycemic (40-50 mg/dl) clamps. As expected, RH induced a blunted sympathoadrenal hormone response to hypoglycemia. Targeted VMH overexpression (∼3.5 fold) of microRNA-7a-5p in RH rats normalized the epinephrine response to hypoglycemia coinciding with a 30% decreased glucose infusion rate. Targeted VMH downregulation of microRNA-665, however, did not improve counterreguatory responses. These findings indicate that microRNA-7a-5p is a potential mediator of impaired VMH glucose sensing/counterregulation and may be an effective therapeutic target to restore impaired sympathoadrenal responses to hypoglycemia. Disclosure R. Agrawal: None. M.G. Montgomery: None. D. Verma: None. G.T. Durupt: None. A. Vieira de Abreu: None. S. Swaminathan: None. S. Fisher: None.

Gut ghrelin regulates hepatic glucose production and insulin signaling via a gut-brain-liver pathway

BackgroundGhrelin modulates many physiological processes. However, the effects of intestinal ghrelin on hepatic glucose production (HGP) are still unclear. The current study was to explore the roles of intestinal ghrelin on glucose homeostasis and insulin signaling in the liver.MethodsThe system of intraduodenal infusion and intracerebral microinfusion into the nucleus of the solitary tract (NTS) in the normal chow-diet rats and pancreatic-euglycemic clamp procedure (PEC) combined with [3-3H] glucose as a tracer were used to analyze the effect of intestinal ghrelin. Intraduodenal co-infusion of ghrelin, tetracaine and Activated Protein Kinase (AMPK) activator (AICAR), or pharmacologic and molecular inhibitor of N-methyl-D-aspartate receptors within the dorsal vagal complex, or hepatic vagotomy in rats were used to explore the possible mechanism of the effect of intestinal ghrelin on HGP.ResultsOur results demonstrated that gut infusion of ghrelin inhibited duodenal AMP-dependent protein kinase (AMPK) signal pathways, increased HGP and expression of gluconeogenic enzymes, and decreased insulin signaling in the liver of the rat. Intraduodenal co-infusion of ghrelin receptor antagonist [D-Lys3]-GHRP-6 and AMPK agonist with ghrelin diminished gut ghrelin-induced increase in HGP and decrease in glucose infusion rate (GIR) and hepatic insulin signaling. The effects of gut ghrelin were also negated by co-infusion with tetracaine, or MK801, an N-methyl-D-aspartate (NMDA) receptor inhibitor, and adenovirus expressing the shRNA of NR1 subunit of NMDA receptors (Ad-shNR1) within the dorsal vagal complex, and hepatic vagotomy in rats. When ghrelin and lipids were co-infused into the duodenum, the roles of gut lipids in increasing the rate of glucose infusion (GIR) and lowering HGP were reversed.ConclusionsThe current study provided evidence that intestinal ghrelin has an effect on HGP and identified a neural glucoregulatory function of gut ghrelin signaling.

Central galanin receptor 2 mediates galanin action to promote systemic glucose metabolism of type 2 diabetic rats

Although recent results of our and other studies have showed that galanin (GAL) is an antidiabetic and anti-inflammatory neuropeptide, the molecular mechanism how central GAL regulates energy homeostasis and insulin sensitivity is still not fully understood. The aim of this study was to investigate whether central type 2 of GAL receptors (GALR2) are involved in the regulation of systemic glucose metabolism and its underlying mechanisms. In the present study, type 2 diabetic rats were intracerebroventricularly (i.c.v.) given 100 nM/kg/d GALR2 agonist M1145 or GALR2 antagonist M871 in 5 μl artificial cerebrospinal fluid once a day for consecutive 21 days. Then insulin resistance indexes, inflammatory factor and many genes associated with the function of glucose metabolism were examined in peripheral tissues. The present findings showed that the intracerebroventricular injection of M1145 or M871 respectively increased or decreased glucose infusion rates in hyperinsulinemic euglycemic clamp tests, but attenuated or enhanced the plasma inflammatory factors and glucose concentration in type 2 diabetic rats. Moreover, administration of M1145 markedly increased PGC-1α and GLUT4 expression in skeletal muscles and adipocytes of type 2 diabetic rats. In conclusion, activation of central GALR2 promotes glucose metabolism and ameliorates insulin resistance mainly through the PGC-1α/GLUT4 pathways. The central GALR2 is crucial to whole-body insulin sensitivity and energy homeostasis.

MPLA‐induced endotoxin tolerance does not protect against LPS insulin resistance

Healthcare‐associated infections are acquired by over 4% of hospital admissions and result in approximately $28 to $45 billion US dollars of direct hospital costs. In addition, the increased incidence of antibiotic resistance highlights the necessity to develop more effective methods of prevention and/or treatment of bacterial infection. Previous work has shown that exposure of mice to lipopolysaccharide (LPS), which mimics a bacterial infection, results in an elevation in plasma pro‐inflammatory cytokines and activation of the toll‐like receptor 4 (TLR4). Recently, it has also been demonstrated that prior exposure to a TLR4 agonist attenuated plasma pro‐inflammatory cytokine response to LPS and improved survival (i.e. endotoxin tolerance). One such TLR4 agonist is monophosphoryl lipid A (MPLA), an adjuvant designed based on the structure of LPS. When MPLA is given prior to or at the time of infection, there is not only a reduced mortality as the result of the infection but there is also a reduction in the plasma pro‐inflammatory cytokine levels compared to a vehicle prime. These investigations also revealed that prior treatment of MPLA altered the metabolic phenotype of bone‐marrow‐derived macrophages. These macrophages have elevated glycolysis, oxidative capacity, and ATP production. Infection is also associated with hyperglycemia and systemic insulin resistance and proinflammatory cytokines are thought to contribute to the insulin resistance. Thus, we hypothesized that systemic administration of MPLA would also result in improved systemic metabolism and insulin sensitivity. To test this hypothesis, we performed hyperinsulinemic (2 mU·kg−1·min−1), euglycemic clamps on chronically catheterized (carotid artery and jugular vein) wild‐type mice. Three days after catheterization, mice are injected intraperitoneally with MPLA (20 mg) or saline vehicle for 2 days. On day 5 all animals received LPS (2μg/g) and clamps were performed. 3‐3Hglucose and 14C‐2deoxyglucose were infused to assess whole body glucose flux and tissue specific glucose uptake, respectively. Administration of LPS resulted in impaired (~35%) insulin sensitivity in saline group relative to historical controls; as reflected in the decrease in glucose infusion rate (Figure 1). Surprisingly, we demonstrated that mice given MPLA injections had a further impairment in insulin sensitivity compared to saline treated mice in the presence of equivalent increases in insulin levels (Figure 2). This was reflected as decreases in glucose uptake (Rg) in multiple tissues (Figure 3), while insulin suppression of endogenous glucose production was similar. Overall, these data suggest that despite beneficial metabolic changes that occur in bone‐marrow derived macrophages upon exposure to MPLA, prior treatment with MPLA does not protect against LPS‐induced insulin resistance. In fact, MPLA amplifies the insulin resistance in LPS‐treated mice. In summary, the immunological protection conferred by the MPLA shown in previous studies did not protect the mice from the systemic insulin resistance. Therefore, therapies developed to combat bacterial infection may provide immunological protection for the patient without protecting from the comorbidity of hyperglycemia.The impact of pretreatment with MPLA or saline on glucose infusion rates (Figure 1); plasma insulin levels (Figure 2); and tissue glucose uptake (Figure 3) in mice after a LPS challenge.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Skeletal muscle insulin resistance is induced by 4-hydroxy-2-hexenal, a by-product of n-3 fatty acid peroxidation

Aims/hypothesisOxidative stress is involved in the pathophysiology of insulin resistance and its progression towards type 2 diabetes. The peroxidation of n-3 polyunsaturated fatty acids produces 4-hydroxy-2-hexenal (4-HHE), a lipid aldehyde with potent electrophilic properties able to interfere with many pathophysiological processes. The aim of the present study was to investigate the role of 4-HHE in the development of insulin resistance.Methods4-HHE concentration was measured in plasma from humans and rats by GC–MS. Insulin resistance was estimated in healthy rats after administration of 4-HHE using hyperinsulinaemic–euglycaemic clamps. In muscle cells, glucose uptake was measured using 2-deoxy-d-glucose and signalling pathways were investigated by western blotting. Intracellular glutathione was measured using a fluorimetric assay kit and boosted using 1,2-dithiole-3-thione (D3T).ResultsCirculating levels of 4-HHE in type 2 diabetic humans and a rat model of diabetes (obese Zucker diabetic fatty rats), were twice those in their non-diabetic counterparts (33 vs 14 nmol/l, p < 0.001), and positively correlated with blood glucose levels. During hyperinsulinaemic–euglycaemic clamps in rats, acute intravenous injection of 4-HHE significantly altered whole-body insulin sensitivity and decreased glucose infusion rate (24.2 vs 9.9 mg kg−1 min−1, p < 0.001). In vitro, 4-HHE impaired insulin-stimulated glucose uptake and signalling (protein kinase B/Akt and IRS1) in L6 muscle cells. Insulin-induced glucose uptake was reduced from 186 to 141.9 pmol mg−1 min−1 (p < 0.05). 4-HHE induced carbonylation of cell proteins and reduced glutathione concentration from 6.3 to 4.5 nmol/mg protein. Increasing intracellular glutathione pools using D3T prevented 4-HHE-induced carbonyl stress and insulin resistance.Conclusions/interpretation4-HHE is produced in type 2 diabetic humans and Zucker diabetic fatty rats and blunts insulin action in skeletal muscle. 4-HHE therefore plays a causal role in the pathophysiology of type 2 diabetes and might constitute a potential therapeutic target to taper oxidative stress-induced insulin resistance.

Metabolomic Response of Skeletal Muscle to Aerobic Exercise Training in Insulin Resistant Type 1 Diabetic Rats.

The etiology of insulin resistance in Type 1 Diabetes (T1D) is unknown, however it affects approximately 20% of T1D patients. Intramyocellular lipids (IMCL) have been identified as a mechanism of insulin resistance. We examined skeletal muscle of T1D rats to determine if alterations in lipid metabolism were evident and whether aerobic exercise training improves IMCL and insulin resistance. To do so, 48 male Sprague-Dawley rats were divided into control (C), sedentary diabetes (D) and diabetes exercise (DX) groups. Following multiple low-dose Streptozotocin (STZ) injections (20 mg/kg), glycemia (9–15 mM) was maintained using insulin treatment. DX were treadmill trained at high intensity (~75% V02max; 5days/week) for 10 weeks. The results demonstrate that D exhibited insulin resistance compared with C and DX, indicated by decreased glucose infusion rate during a hyperinsulinemic-euglycemic clamp (p < 0.05). There were no differences between C and DX, suggesting that exercise improved insulin resistance (p < 0.05). Metabolomics analysis revealed a significant shift in lipid metabolism whereby notable fatty acid metabolites (arachidonic acid, palmitic acid and several polyunsaturated fatty acids) were significantly elevated in D compared to C and DX. Based on the intermediates observed, insulin resistance in T1D is characterized by an insulin-desensitizing intramyocellular fatty acid metabolite profile that is ameliorated with exercise training.

Enhancement of insulin-mediated rat muscle glucose uptake and microvascular perfusion by 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside.

BackgroundInsulin-induced microvascular recruitment is important for optimal muscle glucose uptake. 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR, an activator of AMP-activated protein kinase), can also induce microvascular recruitment, at doses that do not acutely activate glucose transport in rat muscle. Whether low doses of AICAR can augment physiologic insulin action is unknown. In the present study we used the euglycemic hyperinsulinemic clamp to assess whether insulin action is augmented by low dose AICAR.MethodsAnesthetized rats were studied during saline infusion or euglycemic insulin (3 mU/kg/min) clamp for 2 h in the absence or presence of AICAR for the last hour (5 mg bolus followed by 3.75 mg/kg/min). Muscle glucose uptake (R’g) was determined radioisotopically with 14C-2-deoxyglucose and muscle microvascular perfusion by contrast-enhanced ultrasound with microbubbles.ResultsAICAR did not affect blood glucose, or lower leg R’g, although it significantly (p < 0.05) increased blood lactate levels and augmented muscle microvascular blood volume via a nitric oxide synthase dependent pathway. Insulin increased femoral blood flow, whole body glucose infusion rate (GIR), R’g, hindleg glucose uptake, and microvascular blood volume. Addition of AICAR during insulin infusion increased lactate production, further increased R’g in Type IIA (fast twitch oxidative) and IIB (fast twitch glycolytic) fiber containing muscles, and hindleg glucose uptake, but decreased R’g in the Type I (slow twitch oxidative) fiber muscle. AICAR also decreased GIR due to inhibition of insulin-mediated suppression of hepatic glucose output. AICAR augmented insulin-mediated microvascular perfusion.ConclusionsAICAR, at levels that have no direct effect on muscle glucose uptake, augments insulin-mediated microvascular blood flow and glucose uptake in white fiber type muscles. Agents targeted to endothelial AMPK activation are promising insulin sensitizers, however, the decrease in GIR and the propensity to increase blood lactate cautions against AICAR as an acute insulin sensitizer.

Resveratrol prevents insulin resistance caused by short-term elevation of free fatty acids in vivo.

Elevated levels of plasma free fatty acids (FFA), which are commonly found in obesity, induce insulin resistance. FFA activate protein kinases including the proinflammatory IκBα kinase β (IKKβ), leading to serine phosphorylation of insulin receptor substrate 1 (IRS-1) and impaired insulin signaling. To test whether resveratrol, a polyphenol found in red wine, prevents FFA-induced insulin resistance, we used a hyperinsulinemic-euglycemic clamp with a tracer to assess hepatic and peripheral insulin sensitivity in overnight-fasted Wistar rats infused for 7 h with saline, Intralipid plus 20 U·mL(-1) heparin (IH; triglyceride emulsion that elevates FFA levels in vivo; 5.5 μL·min(-1)) with or without resveratrol (3 mg·kg(-1)·h(-1)), or resveratrol alone. Infusion of IH significantly decreased glucose infusion rate (GIR; P < 0.05) and peripheral glucose utilization (P < 0.05) and increased endogenous glucose production (EGP; P < 0.05) during the clamp compared with saline infusion. Resveratrol co-infusion, however, completely prevented the effects induced by IH infusion: it prevented the decreases in GIR (P < 0.05 vs. IH), peripheral glucose utilization (P < 0.05 vs. IH), and insulin-induced suppression of EGP (P < 0.05 vs. IH). Resveratrol alone had no effect. Furthermore, IH infusion increased serine (307) phosphorylation of IRS-1 in soleus muscle (∼30-fold, P < 0.001), decreased total IRS-1 levels, and decreased IκBα content, consistent with activation of IKKβ. Importantly, all of these effects were abolished by resveratrol (P < 0.05 vs. IH). These results suggest that resveratrol prevents FFA-induced hepatic and peripheral insulin resistance and, therefore, may help mitigate the health consequences of obesity.

184 Temporospatial Effects of Endothelium Specific Inhibition of Shc Homology 2 -containing Inositol 5´ Phosphatase 2 on Nitric Oxide Bioavailability and Whole Body Insulin Sensitivity

IntroductionAgeing is an important risk factor for diabetes and cardiovascular disease. Integrity of the endothelium plays a critical role in cardiovascular pathophysiology. Insulin signalling in endothelial cells modulates the generation...

Xylazine-induced reduction of tissue sensitivity to insulin leads to acute hyperglycemia in diabetic and normoglycemic monkeys

BackgroundThe α2-adrenoceptor agonist xylazine as an anesthetic has been widely used either alone or in combination with other anesthetics, such as ketamine, in veterinary clinic and research. In the last decade xylazine has been used in drug abusers in certain geographic area. This study investigated the effects of xylazine on blood glucose level and insulin secretion in normoglycemic and insulin-dependent diabetic monkeys.MethodsBoth adult cynomolgus (n = 10) and rhesus (n = 8) monkeys with either sex were used in the study. Xylazine (1–2 mg/kg) was administrated intramuscularly. Blood glucose, insulin, glucagon and glucagon-like peptide 1 in overnight-fasted monkeys were measured immediately before and after xylazine administration. The hyperinsulinemic-euglycemic clamp method was used in the study for assessing the potential mechanism of xylazine-induced hyperglycemia.ResultsXylazine administration increased the blood glucose levels from 58 ± 3 to 108 ± 12 mg/dL in normoglycemic (n = 5, p < 0.01) and from 158 ± 9 to 221 ± 13 mg/dL in insulin-dependent diabetic (n = 5, p < 0.01) monkeys and was not accompanied by any significant changes in blood insulin, glucagon, and glucagon-like peptide-1. Xylazine-induced hyperglycemia occurred within 10 min and reached the peak at 35 min after injection. Xylazine-induced hyperglycemia declined slowly in diabetic animals. The α2-adrenoceptor antagonist yohimbine was administrated to bring down the elevated glucose level to the pre-xylazine one in 4 out of 5 diabetic animals. To assess the potential mechanism, the hyperinsulinemic-euglycemic clamp was used to maintain a nearly saturated and constant insulin level for minimizing endogenous insulin glucoregulation. Xylazine administration decreased glucose infusion rate, from 14.3 ± 1.4 to 8.3 ± 0.8 mg/min/kg (n = 6, p < 0.01) in normoglycemic rhesus monkeys, which indicates that the glucose metabolic rate (M rate) was decreased by xylazine. In addition, after clamping blood glucose level in a range of 55 to 75 mg/dL for 40 min with constant glucose infusion, xylazine administration still increased blood glucose concentration.ConclusionsWe conclude that xylazine administration induces hyperglycemia in normoglycemic and insulin-dependent diabetic monkeys potentially via stimulation of α2-adrenoceptors and then reducing tissue sensitivity to insulin and glucose uptake.

Grape Polyphenols Prevent Fructose-Induced Oxidative Stress and Insulin Resistance in First-Degree Relatives of Type 2 Diabetic Patients

OBJECTIVETo assess the clinical efficacy of nutritional amounts of grape polyphenols (PPs) in counteracting the metabolic alterations of high-fructose diet, including oxidative stress and insulin resistance (IR), in healthy volunteers with high metabolic risk.RESEARCH DESIGN AND METHODSThirty-eight healthy overweight/obese first-degree relatives of type 2 diabetic patients (18 men and 20 women) were randomized in a double-blind controlled trial between a grape PP (2 g/day) and a placebo (PCB) group. Subjects were investigated at baseline and after 8 and 9 weeks of supplementation, the last 6 days of which they all received 3 g/kg fat-free mass/day of fructose. The primary end point was the protective effect of grape PPs on fructose-induced IR.RESULTSIn the PCB group, fructose induced 1) a 20% decrease in hepatic insulin sensitivity index (P < 0.05) and an 11% decrease in glucose infusion rate (P < 0.05) as evaluated during a two-step hyperinsulinemic-euglycemic clamp, 2) an increase in systemic (urinary F2-isoprostanes) and muscle (thiobarbituric acid–reactive substances and protein carbonylation) oxidative stress (P < 0.05), and 3) a downregulation of mitochondrial genes and decreased mitochondrial respiration (P < 0.05). All the deleterious effects of fructose were fully blunted by grape PP supplementation. Antioxidative defenses, inflammatory markers, and main adipokines were affected neither by fructose nor by grape PPs.CONCLUSIONSA natural mixture of grape PPs at nutritional doses efficiently prevents fructose-induced oxidative stress and IR. The current interest in grape PP ingredients and products by the global food and nutrition industries could well make them a stepping-stone of preventive nutrition.

Blocking central galanin receptors attenuates insulin sensitivity in myocytes of diabetic trained rats

Galanin (Gal), a bioactive neuropeptide, is widely distributed throughout the central nervous system and has diverse modulatory effects. To understand the central effect of this training-stimulatory peptide on insulin sensitivity, its antagonist M35 was injected into the cerebral ventricle in type 2 diabetic rats. A treadmill running of the rats was used to stimulate circulating Gal secretion and central Gal mRNA expression. The results showed that M35 significantly decreased glucose infusion rates in euglycemic-hyperinsulinemic clamp tests as well as 2-deoxy-[(3) H]D-glucose uptake and peroxisome proliferator-activated receptor-α expression levels in skeletal muscles. M35 also attenuated glucose transporter 4 (GLUT4) concentration in plasma membranes and total cell membranes of myocytes, and the ratios of the GLUT4 contents in the former to the latter in M35 groups were lower than those of each diabetic control. These results imply that endogenous Gal, acting through its central receptor, may facilitate GLUT4 translocation from cytoplasm vesicles to cellular surface of myocytes to accelerate glucose uptake and to enhance insulin sensitivity in healthy and type 2 diabetic rats. Gal and its relative agents are potential targets for treatment of type 2 diabetes mellitus and its complications.

241 ENDOTHELIAL SHIP2 CONFERS AGE-DEPENDENT CONTRASTING AFFECTS ON WHOLE BODY GLUCOSE HOMEOSTASIS AND VASCULAR FUNCTION

<h3>Introduction</h3> Aging is an important risk factor for diabetes and cardiovascular disease and integrity of the endothelium plays a critical role in cardiovascular pathophysiology. Although the vascular implications of endothelial insulin resistance are well understood, the effect of <i>enhanced</i> endothelial insulin signaling on whole body glucose regulation and vascular function remains poorly characterized. We therefore generated mice with endothelial-specific downregulation of the lipid phosphatase SHIP2 (a negative regulator of insulin signaling) to investigate whether enhanced insulin signaling in the endothelium modulates vascular function and whole body glucose regulation. <h3>Methods</h3> Exons 18–19 of the ship 2 gene were deleted using Cre-Lox technology under control of the Tie2 promoter generating a catalytically inactivate protein. Male heterozygotes for the inactive protein (EC-SHIP2^+/−) were compared to sex-matched littermate controls. <h3>Results</h3> EC-SHIP^+/− mice were morphologically indistinguishable from controls, exhibiting normal development. At 8 weeks of age EC-SHIP2^+/− mice displayed increased glucose tolerance after glucose challenge (P=0.03) and improved insulin sensitivity (P=0.02) after insulin challenge compared to controls. Surprisingly however, by 40 weeks of age this phenotype was reversed; EC-SHIP2^+/− mice revealed significant insulin resistance 60 min after insulin challenge (P=&lt;0.05). This phenotype was confirmed by euglycemic hyperinsulinemic clamping showing whole body insulin resistance in EC-SHIP^+/− mice (decreased glucose infusion rate of 26% P&lt;0.05). In young mice <i>ex vivo</i> aortic vasomotor studies in both controls and EC-SHIP^+/− revealed similar contractile responses to phenylephrine and displayed decreased contraction after insulin incubation (Emax 0.88±0.05g vs 0.62±0.05g P=0.002 and 0.83±0.05g vs 0.69±0.05g P=0.025 respectively). Both groups displayed increased contraction after NO synthase inhibitor LNMMA incubation (Emax 0.88±0.05g vs 1.31±0.11g P=0.01 and 0.83±0.05g vs 1.28±0.02g P=&lt;0.0001 respectively). However, at 40 weeks old in EC-SHIP2^+/− mice the vasodilatory aortic ring response to insulin was abolished (Emax controls 0.59±0.04g vs 0.47±0.03g P=0.04, EC-SHIP2^+/− 0.64±0.04g vs 0.63±0.06g P=0.9) and EC-SHIP2^+/− displayed no increase in contraction to LNMMA incubation (Emax controls 0.59±0.04g vs 0.82±0.08g P=0.02, EC-SHIP2^+/− 0.64±0.04g vs 0.69±0.07g P=0.5) indicating insulin resistance and lower basal NO production, suggesting the change in glucose homeostasis may be mediated by changes in NO bioavailability. <h3>Conclusion</h3> Endothelial functional downregulation of SHIP2 augments whole body glucose disposal in young mice but attenuates whole body glucose disposal in older mice. Although further studies are required to elucidate the molecular mechanisms our data suggest a previously unrecognised age dependent role for the vascular endothelium in whole body glucose regulation.

Atypical antipsychotics and effects of adrenergic and serotonergic receptor binding on insulin secretion in-vivo: An animal model

Atypical antipsychotics (AAPs) are associated with several metabolic sequelae including increased risk of type 2 diabetes. Growing evidence points to a direct drug effect of these compounds on glucose homeostasis, independent of weight gain. While the responsible mechanisms have yet to be elucidated, the heterogeneous binding profiles of AAPs likely include receptors involved in glucose metabolism. This study aimed to clarify weight-gain independent mechanisms of AAP-induced alterations in insulin secretion. Deconstruction of the receptor binding profiles of these agents was done using representative antagonists. Healthy rats were pre-treated with a single subcutaneous dose of prazosin 0.25mg/kg (n=16), a selective α1 antagonist; idazoxan 0.5mg/kg (n=10), a selective α2 antagonist; SB242084 0.5mg/kg (n=10), a selective 5HT2C antagonist; WAY100635 0.1mg/kg (n=10), a selective 5HT1A antagonist; MDL100907 0.5mg/kg (n=8), a selective 5HT2A antagonist; or vehicle: 0.9% NaCl saline (n=8), DMSO (n=8), or cyclodextrin (n=5). Hyperglycemic clamps were employed following injection, providing an index of secretory capacity of pancreatic β-cells. Treatment with prazosin and MDL100907 resulted in significant decreases in both insulin and C-peptide secretion compared to their respective controls, DMSO and saline. These findings were corroborated with decreased glucose infusion rate and disposition index in the prazosin group. Results suggest that α1 and 5HT2A receptor antagonism may be involved in glucose dysregulation with AAP treatment, however, the exact mechanisms involved remain unknown.

Anesthesia with propofol induces insulin resistance systemically in skeletal and cardiac muscles and liver of rats

Hyperglycemia together with hepatic and muscle insulin resistance are common features in critically ill patients, and these changes are associated with enhanced inflammatory response, increased susceptibility to infection, muscle wasting, and worsened prognosis. Tight blood glucose control by intensive insulin treatment may reduce the morbidity and mortality in intensive care units. Although some anesthetics have been shown to cause insulin resistance, it remains unknown how and in which tissues insulin resistance is induced by anesthetics. Moreover, the effects of propofol, a clinically relevant intravenous anesthetic, also used in the intensive care unit for sedation, on insulin sensitivity have not yet been investigated. Euglycemic hyperinsulinemic clamp study was performed in rats anesthetized with propofol and conscious unrestrained rats. To evaluate glucose uptake in tissues and hepatic glucose output [3H]glucose and 2-deoxy[14C]glucose were infused during the clamp study. Anesthesia with propofol induced a marked whole-body insulin resistance compared with conscious rats, as reflected by significantly decreased glucose infusion rate to maintain euglycemia. Insulin-stimulated tissue glucose uptake was decreased in skeletal muscle and heart, and hepatic glucose output was increased in propofol anesthetized rats. Anesthesia with propofol induces systemic insulin resistance along with decreases in insulin-stimulated glucose uptake in skeletal and heart muscle and attenuation of the insulin-mediated suppression of hepatic glucose output in rats.

Berberine reducing insulin resistance by up-regulating IRS-2 mRNA expression in nonalcoholic fatty liver disease (NAFLD) rat liver

This study was performed to investigate the molecular mechanism and the therapeutic effect of berberine on nonalcoholic fatty liver disease (NAFLD). Rat models were given a high-fat diet (42% kcal) until they developed NAFLD, then were given normal saline ( n = 10), berberine ( n− = 10) at 187.5 mg/kg/day, or pioglitazone ( n = 10) at 10.0 mg/kg/day intragastrically for 4 weeks, respectively, and evaluated by hyperinsulinemic euglycemic clamping for insulin sensitivity. Serum biochemical markers and liver triglyceride (TG) were analyzed, real-time RT-PCR for mRNA expression and western blotting for protein expression of insulin receptor (IR) and insulin receptor substrate-2 (IRS-2) in liver tissues were performed, and hepatic histopathology in the rat models with NAFLD at the end of treatment was compared with normal controls ( n = 10). The NAFLD rats developed insulin resistance, showing increased fasting blood glucose and insulin levels, decreased glucose infusion rate, increased weight of epididymal fat (g/100 g body weight), obvious hepatic steatosis and inflammation, and down-regulated IRS-2 mRNA and protein levels compared with normal controls (all P < 0.05). In comparison with those treated with saline, model rats treated with berberine or pioglitazone underwent significant recovery, including up-regulated IRS-2 mRNA and protein (all P < 0.05). Our results indicate that berberine may improve insulin resistance of NAFLD by up-regulating mRNA and protein levels of IRS-2, a key molecule in the insulin signaling pathway, suggesting that berberine may be used to treat NAFLD.

A ketogenic diet impairs energy and glucose homeostasis by the attenuation of hypothalamic leptin signaling and hepatic insulin signaling in a rat model of non-obese type 2 diabetes

Ketogenic diets (KTD) are reported to have beneficial effects on the regulation of energy and glucose homeostasis, but remain controversial. We investigated the effects of KTD and ketones on insulin resistance and secretion in non-obese type 2 diabetic rats and their mechanism. KTD (82% energy as fat), intraperitoneal injection of β-hydroxybutyrate (IHB; 150 mg/kg bw/12 h) with a control diet (COD; 20% energy as fat) or saline injection with COD was given to 90% pancreatectomized (Px) diabetic rats for five weeks. KTD increased epididymal fat pads and serum leptin levels without increasing energy intake, but IHB decreased them. KTD, but not IHB, attenuated hypothalamic signal transducer and activator of transcription 3 and 5'-adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in KTD. Serum glucagon levels were markedly higher in the KTD group than in other groups. During an oral glucose tolerance test, serum glucose levels slowly increased until 80 min in the KTD group and then decreased very slowly. Insulin secretion capacity during a hyperglycemic clamp was significantly lower in the IHB group than in other groups. However, a euglycemic hyperinsulinemic clamp revealed that KTD decreased glucose infusion rates and increased hepatic glucose output in hyperinsulinemic states while IHB had opposite effects to KTD. The increased hepatic glucose output in KTD was associated with increased hepatic phosphoenolpyruvate carboxykinase expression through attenuated tyrosine phosphorylation of IRS2 and phosphorylation of Akt(Ser473). Hepatic AMPK(Thr172) phosphorylation was reduced in KTD. In conclusion, KTD impairs energy and glucose homeostasis by exacerbating insulin resistance and attenuating hypothalamic leptin signaling in non-obese type 2 diabetic rats. These changes are not associated with increased serum ketone levels.

Estrogen Replacement Reverses Olanzapine-Induced Weight Gain and Hepatic Insulin Resistance in Ovariectomized Diabetic Rats

Objectives: We investigated whether estrogen replacement modulated energy and glucose metabolic changes induced by olanzapine (OZP) and risperidone (RPD) in 90% pancreatectomized diabetic rats, some of whom had also been ovariectomized (OVX) and some of whom had not (sham). Methods: OVX diabetic rats were subcutaneously injected with estrogen replacement (17β-estradiol, 30 µg/kg/day) or a vehicle. Each group was divided into 3 subgroups, and each subgroup was orally either given a placebo, RPD (0.5 mg/kg body weight/day) or OZP (2 mg/kg body weight/day) for 8 weeks. Sham rats were also divided into 3 subgroups and given drugs in the same manner as the OVX rats were. All rats were fed high-fat diets. Results: OZP increased body weight and epididymal fat pads more than the control (vehicle) in sham and OVX rats. Increased body weight in OZP-treated sham and OVX rats was due to the increment in food intake, which was associated with potentiating the phosphorylation of hypothalamic adenosine-monophosphate-activated protein kinase. At euglycemic hyperinsulinemic clamping, OZP decreased glucose infusion rates and increased hepatic glucose output in OVX diabetic rats. In sham rats, OZP increased hepatic glucose output but not as much as in OVX rats. Hepatic insulin signaling and glucose sensing were attenuated in OZP-treated OVX rats, and the attenuation increased hepatic phosphoenolpyruvate carboxykinase expression to induce gluconeogenesis. These negative and harmful effects noted among OZP-treated OVX rats were reversed by estrogen replacement treatment. However, RPD did not alter body weight and peripheral insulin sensitivity in sham and OVX rats. Conclusions: OZP treatment should be avoided when treating diabetic and schizophrenic women, especially those in their postmenopausal period.