Reduced Plasma Insulin Research Articles

A novel dual amylin and calcitonin receptor agonist, KBP‐089, induces weight loss through a reduction in fat, but not lean mass, while improving food preference

Obesity and associated co-morbidities, such as type 2 diabetes and non-alcoholic fatty liver disease, are major health challenges. Hence, there is an important need to develop weight loss therapies with the ability to reduce the co-morbidities. The effect of the dual amylin and calcitonin receptor agonist (DACRA), KBP-089, on body weight, glucose homeostasis and fatty acid accumulation in liver and muscle tissue and on food preference was investigated. Furthermore, we elucidated weight-independent effects of KBP-089 using a weight-matched group. Rats fed a high-fat diet were treated, s.c., with KBP-089 0.625, 1.25, 2.5μg·kg-1 or vehicle. KB-089 induced in a dose-dependent and sustained weight loss (~17% by 2.5μg·kg-1 ). Moreover, KBP-089 reduced fat depot size and reduced lipid accumulation in muscle and liver. In Zucker Diabetic Fatty rats, KBP-089 improved glucose homeostasis through improved insulin action. To obtain a weight-matched group, significantly less food was offered (9% less than in the KBP-089 group). Weight matching led to improved glucose homeostasis by reducing plasma insulin; however, these effect were inferior compared to those of KBP-089. In the food preference test, rats fed a normal diet obtained 74% of their calories from chocolate. KBP-089 reduced total caloric intake and induced a relative increase in chow consumption while drastically reducing chocolate consumption compared with vehicle. The novel DACRA, KBP-089, induces a sustained weight loss, leading to improved metabolic parameters including food preference, and these are beyond those observed simply by diet-induced weight loss.

Corticotropin-releasing factor overexpression in mice abrogates sex differences in body weight, visceral fat, and food intake response to a fast and alters levels of feeding regulatory hormones

BackgroundCorticotropin-releasing factor overexpressing (CRF-OE) male mice showed an inhibited feeding response to a fast, and lower plasma acyl ghrelin and Fos expression in the arcuate nucleus compared to wild-type (WT) mice. We investigated whether hormones and hypothalamic feeding signals are impaired in CRF-OE mice and the influence of sex.MethodsMale and female CRF-OE mice and WT littermates (4–6 months old) fed ad libitum or overnight fasted were assessed for body, adrenal glands and perigonadal fat weights, food intake, plasma hormones, blood glucose, and mRNA hypothalamic signals.ResultsUnder fed conditions, compared to WT, CRF-OE mice have increased adrenal glands and perigonadal fat weight, plasma corticosterone, leptin and insulin, and hypothalamic leptin receptor and decreased plasma acyl ghrelin. Compared to male, female WT mice have lower body and perigonadal fat and plasma leptin but higher adrenal glands weights. CRF-OE mice lost these sex differences except for the adrenals. Male CRF-OE and WT mice did not differ in hypothalamic expression of neuropeptide Y (NPY) and proopiomelanocortin (POMC), while female CRF-OE compared to female WT and male CRF-OE had higher NPY mRNA levels. After fasting, female WT mice lost more body weight and ate more food than male WT, while CRF-OE mice had reduced body weight loss and inhibited food intake without sex difference. In male WT mice, fasting reduced plasma insulin and leptin and increased acyl ghrelin and corticosterone while female WT showed only a rise in corticosterone. In CRF-OE mice, fasting reduced insulin while leptin, acyl ghrelin and corticosterone were unchanged with no sex difference. Fasting blood glucose was higher in CRF-OE with female > male. In WT mice, fasting increased hypothalamic NPY expression in both sexes and decreased POMC only in males, while in CRF-OE mice, NPY did not change, and POMC decreased in males and increased in females.ConclusionsThese data indicate that CRF-OE mice have abnormal basal and fasting circulating hormones and hypothalamic feeding-related signals. CRF-OE also abolishes the sex difference in body weight, abdominal fat, and fasting-induced feeding and changes in plasma levels of leptin and acyl ghrelin.

Ghrelin doesn't limit insulin release in pregnant rats fed low protein diet.

To test the hypothesis that insulin secretion in pregnant rats fed LP diet is reduced by ghrelin signaling in pancreatic islets, we investigated plasma insulin levels, expression of ghrelin and its receptor and glucose stimulated insulin secretion (GSIS) of pancreatic islets in response to ghrelin. Plasma insulin levels were lower and ghrelin receptor abundance in islets was unaltered in LP rats. In the presence of both 2.8 and 16.7 mM glucose, GSIS was lower in LP compared to CT rats. In the presence of 2.8 mM glucose, GSIS was unaltered by ghrelin and its antagonist in both CT and LP rats. In the presence of 16.7 mM glucose, GSIS in LP rats was unchanged while in CT rats was reduced by ghrelin and reversed by ghrelin antagonist. These results indicate ghrelin signaling inhibits GSIS of pancreatic islets in pregnant rats fed CT diet, but it is blunted in pregnant rats fed LP diet and thus may not contribute to the reduction of plasma insulin and GSIS of pancreatic islets in late pregnancy.

LDB1 Regulates Energy Homeostasis During Diet-Induced Obesity.

The broadly expressed transcriptional coregulator LDB1 is essential for β-cell development and glucose homeostasis. However, it is unclear whether LDB1 has metabolic roles beyond the β-cell, especially under metabolic stress. Global Ldb1 deletion results in early embryonic lethality; thus, we used global heterozygous Ldb1+/- and inducible β-cell-specific Ldb1-deficient (Ldb1Δβ-cell) mice. We assessed glucose and insulin tolerance, body composition, feeding, and energy expenditure during high-fat diet exposure. Brown adipose tissue (BAT) biology was evaluated by thermogenic gene expression and LDB1 chromatin immunoprecipitation analysis. We found that partial loss of Ldb1 does not impair the maintenance of glucose homeostasis; rather, we observed improved insulin sensitivity in these mice. Partial loss of Ldb1 also uncovered defects in energy expenditure in lean and diet-induced obese (DIO) mice. This decreased energy expenditure during DIO was associated with significantly altered BAT gene expression, specifically Cidea, Elovl3, Cox7a1, and Dio2. Remarkably, the observed changes in energy balance during DIO were absent in Ldb1Δβ-cell mice, despite a similar reduction in plasma insulin, suggesting a role for LDB1 in BAT. Indeed, LDB1 is expressed in brown adipocytes and occupies a regulatory domain of Elovl3, a gene crucial to normal BAT function. We conclude that LDB1 regulates energy homeostasis, in part through transcriptional modulation of critical regulators in BAT function.

Tumor Necrosis Factor Inhibitors May Improve Glycemic Control in Patients Rheumatoid Arthritis and Concomitant Type 2 Diabetes Mellitus

Insulin resistance is a key feature of obesity, metabolic syndrome, and Type 2 Diabetes Mellitus (T2DM). Inflammation and insulin resistance are closely linked with each other. I. Tumor necrosis factor-α (TNF-α) has been found to impair the insulin sensitivity and promote insulin resistance through multiple actions on the insulin sensitive tissues. Inflammatory cytokines such as TNF, Interleukin (IL)-6, IL-1 and IL-8 may inhibit insulin signaling.1 Hotamisligil et al2 did the pioneering work in 1993 confirming the link between TNF-α and insulin resistance in mice. Animal studies have confirmed that the TNF-α interferes with phosphorylation cascades of the insulin receptor beta subunit and insulin receptor substrate-1, thereby altering the transmembrane signaling that is essential for insulin action in various insulin sensitive tissues.3-5 Also TNF-α causes depletion of GLUT 4, the insulin sensitive glucose transporter in adipocytes and muscles.2,6,7 A intravenous administration of a recombinant TNF-α receptor antibody resulted in improvement in insulin sensitivity2 and dramatic reductions in plasma insulin, glucose, and non-esterified fatty acid levels5 in obese, as compared with lean rats

Robust Reductions of Excess Weight and Hyperphagia by Beloranib in Rat Models of Genetic and Hypothalamic Obesity.

Hypothalamic lesions or deficient melanocortin (MC) signaling via MC4 receptor (MC4r) mutations often lead to hyperphagia and severe treatment-resistant obesity. We tested the methionine aminopeptidase 2-inhibitor beloranib (ZGN-440) in 2 male rat models of obesity, one modeling hypothalamic obesity with a combined medial hypothalamic lesion (CMHL) and the other modeling a monogenic form of obesity with MC4r mutations (MC4r knockout [MC4rKO]). In CMHL rats (age 3 months), postsurgery excess weight gain was significantly inhibited (ZGN-440, 0.2 ± 0.7 g/d; vehicle, 3.8 ± 0.6 g/d; P < 0.001) during 12 days of ZGN-440 treatment (0.1 mg/kg daily subcutaneously) together with a 30% reduction of daily food intake vs vehicle injection. In addition, ZGN-440 treatment improved glucose tolerance and reduced plasma insulin, and circulating levels of α-melanocyte stimulating hormone were increased. Serum lipid levels did not differ significantly in ZGN-440-treated vs vehicle-treated rats. Similar results were found in MC4rKO rats: ZGN-440 treatment (14-21 d) was associated with significant reductions of body weight gain (MC4rKO, -1.7 ± 0.6 vs 2.8 ± 0.4 g/d; lean wild-type controls, -0.7 ± 0.2 vs 1.7 ± 0.7 g/d; ZGN-440 vs vehicle, respectively), reduction of food intake (MC4rKO, -28%; lean controls, -7.5%), and insulin resistance, whereas circulating levels of interleukin-1β did not change. In both obesity models, body temperature and locomotor activity were not affected by ZGN-440 treatment. In conclusion, the robust reduction of body weight in response to ZGN-440 observed in rats with severe obesity is related to a strong reduction of food intake that is likely related to changes in the central regulation of feeding.

Meldonium

Meldonium

Impact of Perturbed Pancreatic β-Cell Cholesterol Homeostasis on Adipose Tissue and Skeletal Muscle Metabolism.

Elevated pancreatic β-cell cholesterol levels impair insulin secretion and reduce plasma insulin levels. This study establishes that low plasma insulin levels have a detrimental effect on two major insulin target tissues: adipose tissue and skeletal muscle. Mice with increased β-cell cholesterol levels were generated by conditional deletion of the ATP-binding cassette transporters, ABCA1 and ABCG1, in β-cells (β-DKO mice). Insulin secretion was impaired in these mice under basal and high-glucose conditions, and glucose disposal was shifted from skeletal muscle to adipose tissue. The β-DKO mice also had increased body fat and adipose tissue macrophage content, elevated plasma interleukin-6 and MCP-1 levels, and decreased skeletal muscle mass. They were not, however, insulin resistant. The adipose tissue expansion and reduced skeletal muscle mass, but not the systemic inflammation or increased adipose tissue macrophage content, were reversed when plasma insulin levels were normalized by insulin supplementation. These studies identify a mechanism by which perturbation of β-cell cholesterol homeostasis and impaired insulin secretion increase adiposity, reduce skeletal muscle mass, and cause systemic inflammation. They further identify β-cell dysfunction as a potential therapeutic target in people at increased risk of developing type 2 diabetes.

Effects of metformin on hyperglycemia in an experimental model of tacrolimus- and sirolimus-induced diabetic rats.

Background/AimsMetformin (MET) is a first-line drug for type 2 diabetes mellitus (DM); its effect on new-onset diabetes after transplantation caused by immunosuppressant therapy is unclear. We compared the effects of MET on DM caused by tacrolimus (TAC) or sirolimus (SRL).MethodsDM was induced by injection of TAC (1.5 mg/kg) or SRL (0.3 mg/kg) for 2 weeks in rats, and MET (200 mg/kg) was injected for 2 more weeks. The effects of MET on DM caused by TAC or SRL were evaluated using an intraperitoneal glucose tolerance test (IPGTT) and by measuring plasma insulin concentration, islet size, and glucose-stimulated insulin secretion (GSIS). The effects of MET on the expression of adenosine monophosphate-activated protein kinase (AMPK), a pharmacological target of MET, were compared between TAC- and SRL-treated islets.ResultsIPGTT showed that both TAC and SRL induced hyperglycemia and reduced plasma insulin concentration compared with vehicle. These changes were reversed by addition of MET to SRL but not to TAC. Pancreatic islet cell size was decreased by TAC but not by SRL, but addition of MET did not affect pancreatic islet cell size in either group. MET significantly increased GSIS in SRL- but not in TAC-treated rats. AMPK expression was not affected by TAC but was significantly decreased in SRL-treated islets. Addition of MET restored AMPK expression in SRL-treated islets but not in TAC-treated islets.ConclusionsMET has different effects on hyperglycemia caused by TAC and SRL. The discrepancy between these drugs is related to their different mechanisms causing DM.

One-time injection of AAV8 encoding urocortin 2 provides long-term resolution of insulin resistance.

Using mice rendered insulin resistant with high fat diets (HFD), we examined blood glucose levels and insulin resistance after i.v. delivery of an adeno-associated virus type 8 encoding murine urocortin 2 (AAV8.UCn2). A single i.v. injection of AAV8.UCn2-normalized blood glucose and glucose disposal within weeks, an effect that lasted for months. Hyperinsulinemic-euglycemic clamps showed reduced plasma insulin, increased glucose disposal rates, and increased insulin sensitivity following UCn2 gene transfer. Mice with corticotropin-releasing hormone type 2-receptor deletion that were rendered insulin resistant by HFD showed no improvement in glucose disposal after UCn2 gene transfer, indicating that the effect requires UCn2's cognate receptor. We also demonstrated increased glucose disposal after UCn2 gene transfer in db/db mice, a second model of insulin resistance. UCn2 gene transfer reduced fatty infiltration of the liver in both models of insulin resistance. UCn2 increases Glut4 translocation to the plasma membrane in skeletal myotubes in a manner quantitatively similar to insulin, indicating a mechanism through which UCn2 operates to increase insulin sensitivity. UCn2 gene transfer, in a dose-dependent manner, is insulin sensitizing and effective for months after a single injection. These findings suggest a potential long-term therapy for clinical type-2 diabetes.

Acute Reduction of Incretin Effect and Glucose Intolerance in Rats by Single Intragastric Administration of 3-deoxyglucosone.

Secretion of glucagon-like peptide-1 has been suggested to be impaired in T2DM and in conditions associated with hyperglycemia. 3-Deoxyglucosone, a dietary composition, has been suggested as an independent factor for the development of prediabetes. A-pathophysiological very high condition of 3DG concentrations administered i. v. induced acute glucose intolerance in rats. In this study, to examine the acute effects of single intragastric administration of 3DG at dose of potentially single-meal intake on plasma glucose, insulin, glucagon, total GLP-1 and total GIP levels in response to a glucose load, OGTT was performed immediately in normal Kunming mice or Sprague-Dawleys rats after 3DG administration. GLP-1 secretion, intracellular cAMP levels and 2-NBDG uptake were examined in STC-1 cells exposured to 3DG. In rats, 20 mg/kg 3DG i.g. (3DG-20 i.g.) impaired glucose tolerance (P<0.05) with increased AUC (1 070±105.2 vs. 918.0±91.20, P<0.05). The mice treated with 3DG-20 i.g. exhibited a similar effect, independent of the effect of plasma 3DG concentration. 3DG-20 i.g. treatment reduced plasma insulin concentrations with decreased AUC (3 552±300.2 vs. 4 715±420.5, P<0.05) in rats whereas plasma glucagon levels were not significantly different. These changes occurred in conjunction with decreased plasma GLP-1 and GIP levels (P<0.05). Furthermore, non-cytotoxic 3DG concentrations directly reduced GLP-1 secretion in STC-1, at least in part, by decreasing intracellular cAMP level and glucose uptake. We demonstrated for the first time that single intragastric administration of 3DG resulted in acute reduction of incretin effect and glucose intolerance, which was associated with a decrease in the biological function of GLP-1 by decreasing GLP-1 secretion.

Suppressing hyperinsulinemia prevents obesity but causes rapid onset of diabetes in leptin-deficient Lepob/ob mice

ObjectiveHyperinsulinemia is commonly associated with obesity. Mice deficient in the adipose-derived hormone leptin (Lepob/ob) develop hyperinsulinemia prior to onset of obesity and glucose intolerance. Whether the excess of circulating insulin is a major contributor to obesity and impaired glucose homeostasis in Lepob/ob mice is unclear. It has been reported previously that diet-induced obesity in mice can be prevented by reducing insulin gene dosage. In the present study, we examined the effects of genetic insulin reduction in Lepob/ob mice on circulating insulin, body composition, and glucose homeostasis. MethodsLeptin expressing (Lepwt/wt) mice lacking 3 insulin alleles were crossed with Lepob/ob mice to generate Lepob/ob and Lepwt/wt littermates lacking 1 (Ins1+/+;Ins2+/−), 2 (Ins1+/+;Ins2−/−) or 3 (Ins1+/−;Ins2−/−) insulin alleles. Animals were assessed for body weight gain, body composition, glucose homeostasis, and islet morphology. ResultsWe found that in young Lepob/ob mice, loss of 2 or 3 insulin alleles reduced plasma insulin levels by 75–95% and attenuated body weight gain by 50–90% compared to Ins1+/+;Ins2+/−;Lepob/ob mice. This corresponded with ∼30% and ∼50% reduced total body fat in Ins1+/+;Ins2−/−;Lepob/ob and Ins1+/−;Ins2−/−;Lepob/ob mice, respectively. Loss of 2 or 3 insulin alleles in young Lepob/ob mice resulted in onset of fasting hyperglycemia by 4 weeks of age, exacerbated glucose intolerance, and abnormal islet morphology. In contrast, loss of 1,2 or 3 insulin alleles in Lepwt/wt mice did not significantly alter plasma insulin levels, body weight, fat mass, fasting glycemia, or glucose tolerance. ConclusionTaken together, our findings indicate that hyperinsulinemia is required for excess adiposity in Lepob/ob mice and sufficient insulin production is necessary to maintain euglycemia in the absence of leptin.

The fruit of Acanthopanax senticosus (Rupr. et Maxim.) Harms improves insulin resistance and hepatic lipid accumulation by modulation of liver adenosine monophosphate–activated protein kinase activity and lipogenic gene expression in high-fat diet–fed obese mice

Obesity-associated insulin resistance is a major risk factor for most metabolic diseases, including dyslipidemia and type 2 diabetes. Acanthopanax senticosus (Rupr. et Maxim.) Harms (Goka) root has been used in traditional Chinese medicine for treatment of diabetes and other conditions; however, little is known about the effects of Goka fruit (GF). Goka fruit is rich in anthocyanin, which has beneficial effects on obesity and insulin resistance via activation of adenosine monophosphate–activated protein kinase (AMPK). We hypothesized that GF can improve obesity-associated insulin resistance. The aim of the present study was to investigate whether GF improves insulin resistance in high-fat diet (HFD)–induced obese mice. High-fat diet mice treated with GF (500 and 1000 mg/kg) for 12 weeks showed an improved glucose tolerance and insulin sensitivity, as well as reduced plasma insulin and liver lipid accumulation. Moreover, GF administration to HFD mice resulted in down-regulation of fatty acid synthase expression and up-regulation of cholesterol 7-alpha-hydroxylase expression in the liver. Notably, AMPK phosphorylation in the liver increased after GF administration. In summary, GF supplementation improved obesity-associated insulin resistance and hepatic lipid accumulation through modulation of AMPK activity and lipid metabolism–associated gene expression.

Changes in aerobic capacity and glycaemic control in response to reduced-exertion high-intensity interval training (REHIT) are not different between sedentary men and women.

Previously it has been reported that reduced-exertion high-intensity interval training (REHIT; total training time of 3 × 10 min per week) improves maximal aerobic capacity in both sedentary men and women, but improves insulin sensitivity in men only. The aim of the present study was to determine whether there is a true sex difference in response to REHIT, or that these findings can be explained by the large interindividual variability in response inherent to all exercise training. Thirty-five sedentary participants (18 women; mean ± SD age for men and women, respectively: age, 33 ± 9 and 36 ± 9 years; body mass index, 25.1 ± 2.1 and 24.1 ± 3.5 kg·m-2; maximal aerobic capacity, 38.6 ± 8.3 and 31.6 ± 4.6 mL·kg-1·min-1) completed a 6-week REHIT programme consisting of eighteen 10-min unloaded cycling sessions with 1 (first session) or 2 (all other sessions) "all-out" 10-20-s sprints against a resistance of 5% of body mass. Maximal aerobic capacity and oral glucose tolerance test-derived insulin sensitivity were determined before and after training. REHIT was associated with an increase in maximal aerobic capacity (2.54 ± 0.65 vs. 2.78 ± 0.68 L·min-1, main effect of time: p < 0.01), a trend toward reduced plasma insulin area-under-the-curve (AUC; 6.7 ± 4.8 vs. 6.1 ± 4.0 IU·min-1·mL-1, p = 0.096), but no significant change in plasma glucose AUC or the Cederholm index of insulin sensitivity. Substantial interindividual variability in response to REHIT was observed for all variables, but there was no significant effect of sex. In conclusion, REHIT improves the key health marker of aerobic capacity within a minimal total training time-commitment. There is large interindividual variability in responses to REHIT, but sex differences in the responses are not apparent.

Protein Kinase Mitogen-activated Protein Kinase Kinase Kinase Kinase 4 (MAP4K4) Promotes Obesity-induced Hyperinsulinemia

Previous studies revealed a paradox whereby mitogen-activated protein kinase kinase kinase kinase 4 (Map4k4) acted as a negative regulator of insulin sensitivity in chronically obese mice, yet systemic deletion of Map4k4 did not improve glucose tolerance. Here, we report markedly reduced glucose-responsive plasma insulin and C-peptide levels in whole body Map4k4-depleted mice (M4K4 iKO) as well as an impaired first phase of insulin secretion from islets derived from M4K4 iKO mice ex vivo. After long-term high fat diet (HFD), M4K4 iKO mice pancreata also displayed reduced β cell mass, fewer proliferating β cells and reduced islet-specific gene mRNA expression compared with controls, although insulin content was normal. Interestingly, the reduced plasma insulin in M4K4 iKO mice exposed to chronic (16 weeks) HFD was not observed in response to acute HFD challenge or short term treatment with the insulin receptor antagonist S961. Furthermore, the improved insulin sensitivity in obese M4K4 iKO mice was abrogated by high exogenous insulin over the course of a euglycemic clamp study, indicating that hypoinsulinemia promotes insulin sensitivity in chronically obese M4K4 iKO mice. These results demonstrate that protein kinase Map4k4 drives obesity-induced hyperinsulinemia and insulin resistance in part by promoting insulin secretion from β cells in mice.

Caloric Restriction Paradoxically Increases Adiposity in Mice With Genetically Reduced Insulin.

Antiadiposity effects of caloric restriction (CR) are associated with reduced insulin/IGF-1 signaling, but it is unclear whether the effects of CR would be additive to genetically reducing circulating insulin. To address this question, we examined female Ins1(+/-):Ins2(-/-) mice and Ins1(+/+):Ins2(-/-) littermate controls on either an ad libitum or 60% CR diet. Although Igf1 levels declined as expected, CR was unable to reduce plasma insulin levels in either genotype below their ad libitum-fed littermate controls. In fact, 53-week-old Ins1(+/-):Ins2(-/-) mice exhibited a paradoxical increase in circulating insulin in the CR group compared with the ad libitum-fed Ins1(+/-):Ins2(-/-) mice. Regardless of insulin gene dosage, CR mice had lower fasting glucose and improved glucose tolerance. Although body mass and lean mass predictably fell after CR initiation, we observed a significant and unexpected increase in fat mass in the CR Ins1(+/-):Ins2(-/-) mice. Specifically, inguinal fat was significantly increased by CR at 66 weeks and 106 weeks. By 106 weeks, brown adipose tissue mass was also significantly increased by CR in both Ins1(+/-):Ins2(-/-) and Ins1(+/+):Ins2(-/-) mice. Interestingly, we observed a clear whitening of brown adipose tissue in the CR groups. Mice in the CR group had altered daily energy expenditure and respiratory exchange ratio circadian rhythms in both genotypes. Multiplexed analysis of circulating hormones revealed that CR was associated with increased fasting and fed levels of the obesogenic hormone, glucose-dependent insulinotropic polypeptide. Collectively these data demonstrate CR has paradoxical effects on adipose tissue growth in the context of genetically reduced insulin.

7-week aerobic exercise training reduces adipocyte area and improves insulin sensitivity in Wistar rats fed a highly palatable diet

The aim of this study was to evaluate the effect aerobic exercise training on fat pad mass, adipocyte size, leptin release and insulin sensitivity in rats fed with high fat-palatable diet. Twenty-four male Wistar rats (250-260g) were divided into four groups: sedentary control (CTR/SD), trained control (CTR/TR), obese sedentary (OB/SD) and obese trained (OB/TR). Obese groups were fed with high fat-palatable diet (27% of fat) and control groups fed with AIN-93. Our results showed that aerobic exercise training was effective to reduce body weight and epididymal fat mass in CTR/TR and OB/TR. Insulin and glucose levels were increased in OB/TR compared with OB/SD. Aerobic exercise training reduced the average area of adipocytes in CTR/TR and OB/TR and it was associated with reduced plasma insulin and leptin. In conclusion, 7-week aerobic exercise training reduces adipocyte area and improves insulin sensitivity and leptin levels in high fat-palatable diet-fed Wistar rats.

Abstract 18321: Analysis of a Consanguineous Cohort to Identify and Characterize Human Knockouts

Background: Experimental disruption of both gene copies (“knockout”) in model organisms has proven useful to understand gene function. Identification of “human knockouts” (i.e., individuals in which null mutations disrupt both copies of a given gene) should therefore provide valuable insights to a gene function that could be of direct relevance to humans. Objective and Methods: We leverage naturally-occurring null mutations and consanguinity in the human population in order to: 1) identify humans knocked out for genes; and 2) characterize the phenotypic consequences of complete gene disruption. We performed whole-exome sequencing in 7,078 individuals living in Pakistan, a region of the world with high levels of consanguinity, and tested whether knockouts differed from wild-type participants across a range of &gt;200 cardiometabolic traits. Results: Median length of genome-wide homozygosity among Pakistani participants was 6-7 times higher than participants of European (CEU, TSI), East Asian (CHB, JPT, CHD) and African ancestries (YRI, MKK), respectively. In Pakistanis, we were able to enumerate 47,656 mutations predicted to be null (nonsense, frameshift, or canonical splice-site); variants were further filtered based on MAF, transcript position, splice sites, and conservation to identify 36,850 “high-confidence” null mutations across 12,131 autosomal genes. Across all participants, 961 distinct genes were completely disrupted by homozygous null mutations. 1,306 participants (18.4%) had at least one gene knocked out. In a phenotypic screen, homozygosity for null mutations at APOC3 was associated with absent plasma apolipoprotein C-III levels; at PLAG27 , with absent enzymatic activity of lipoprotein-associated phospholipase A2 in the blood; at CYP2F1 , with higher plasma interleukin-8 concentrations; and at either A3GALT2 or NRG4 , with markedly reduced plasma insulin C-peptide concentrations. After physiologic challenge with oral fat, APOC3 knockouts, when compared to wild-type family members, displayed marked blunting of the usual post-prandial rise in plasma triglycerides. Conclusion: These observations provide a roadmap to understand the consequences of complete disruption of a large fraction of genes in the human genome.

Quantitative Assessment of Proliferative Effects of Oral Vanadium on Pancreatic Islet Volumes and Beta Cell Numbers of Diabetic Rats.

Background:Oral vanadyl sulfate (vanadium) induces normoglycemia, proliferates beta cells and prevents pancreatic islet atrophy in streptozotocin-induced diabetic rats. Soteriological method is used to quantitate the proliferative effects of vanadium on beta-cell numbers and islet volumes of normal and diabetic rats. Methods:Adult male Sprague-Dawley rats were made diabetic with intravenous streptozotocin injection (40 mg/kg). Normal and diabetic rats were divided into four groups. While control normal and diabetic (CD) groups used water, vanadium-treated normal (VTN) and diabetic (VTD) groups used solutions containing vanadyl sulfate (0.5-1 mg/mL, VOSO4+5H2O). Tail blood samples were used to measure blood glucose (BG) and plasma insulin. Two months after treatment, rats were sacrificed, pancreata prepared, and stereology method was used to quantitatively evaluate total beta cell numbers (TBCN) and total islet volumes (TISVOL). Results:Normoglycemia persisted in VTN with significantly decreased plasma insulin (0.190.08 vs. 0.970.27 ng/dL, P<0.002). The respective high BG (53249 vs. 14446 mg/dL, P<0.0001) and reduced plasma insulin (0.260.15 vs. 0.540.19 ng/dL, P<0.002) seen in CD were reversed in VTD during vanadium treatment or withdrawal. While the induction of diabetes, compared to their control, significantly decreased TISVOL (1.90.2 vs. 3.030.6 mm3, P<0.003) and TBCN (0.990.1 vs. 3.20.2 x 106, P<0.003), vanadium treatment significantly increased TISVOL (2.90.8 and 4.071.0 mm3, P<0.003) and TBCN (1.50.3 and 3.80.6 x 106, P<0.03). Conclusion:Two-month oral vanadium therapy in STZ-diabetic rats ameliorated hyperglycemia by partially restoring plasma insulin. This action was through proliferative actions of vanadium in preventing islet atrophy by increasing beta-cell numbers.

Abstract 700: Accelerated Glycolysis in Adipose Tissue Macrophages Triggers Hif-1α in Obesity and Promotes Insulin Resistance.

During obesity, macrophages (Mø) accumulate in the visceral adipose tissue (VAT), giving rise to a state of chronic, low-grade inflammation that promotes insulin resistance and type 2 diabetes. We hypothesized that activation of HIF-1α in highly-metabolically active Mø sustains inflammation in obese VAT and promotes metabolic dysfunction. We show that hypoxic Mø, like M1-polarized Mø, shift their metabolism from oxidative phosphorylation to glycolysis, leading to the accumulation of HIF-1α-stabilizing intermediates. Extracellular flux analysis showed that treating Mø with the hypoxia mimetic CoCl2 or the saturated fatty acid palmitate reduced cellular oxygen consumption and increased the rate of extracellular acidification indicative of enhanced glycolysis. Metabolites known to accumulate during persistent glycolysis, such as succinate and lactic acid, activated HIF-1α in Mø and promoted inflammatory gene expression. To test the role of Mø HIF-1α in promoting VAT inflammation and metabolic dysfunction in obesity, we fed wild type or Mø-specific HIF-1α knock-out mice a high-fat diet (60% kcal fat) for 20 weeks. Notably, the ablation of HIF-1α in Mø reduced VAT inflammation as indicated by the reduced accumulation of F4/80+ cells and decreased expression of inflammatory cytokines (TNFα, IL-6, MCP-1). In addition, adipose tissue Mø isolated from Mø-HIF-1α knock-out mice showed increased expression of markers characteristic of M2 reparative Mø (Ym1, Fizz1, Aldh2) and reduced expression of M1 inflammatory Mø markers (Ccl2, Il1b), compared to Mø from WT mice. Furthermore, Mø-HIF-1α knock-out mice showed improved glucose homeostasis and insulin sensitivity, and reduced plasma insulin and free fatty acid levels compared to WT mice. Together, these data indicate that activation of HIF-1α in VAT Mø during obesity promotes tissue inflammation and insulin resistance.