Reduced Plasma Insulin Levels Research Articles

7279 Survodutide and Semaglutide Both Induce Weight Loss but Show Different Effects on Food Preference and Dyslipidemia in the Free Choice Diet-induced Obese Hamster Model

Abstract Disclosure: F. Briand: Employee; Self; Physiogenix. R. Augustin: Employee; Self; Boehringer Ingelheim. K. Bleymehl: Employee; Self; Boehringer Ingelheim. T. Zimmermann: Employee; Self; Boehringer Ingelheim. T. Klöckener: Employee; Self; Boehringer Ingelheim. T. Klein: Employee; Self; Boehringer Ingelheim. Introduction: Semaglutide, a GLP-1 receptor agonist, and survodutide, a GCGR/GLP-1R dual agonist, have demonstrated significant weight loss in patients with obesity. To test whether this weight loss is associated with changes in food preference and improvement in dyslipidemia, we evaluated semaglutide and survodutide in the free choice diet-induced obese and dyslipidemic hamster, a model with a human-like lipoprotein metabolism. Methods: Obesity and dyslipidemia were induced with a 20-week free choice diet, which presents hamsters with a choice between control chow diet or high fat/cholesterol diet, and normal water or 10% fructose water. Obese hamsters were then kept on this free choice diet and treated subcutaneously once daily with vehicle, semaglutide 15 nmol/kg or survodutide 15 nmol/kg for 5 weeks. Results: Compared with vehicle, semaglutide and survodutide led to a 17% and 11% body weight reduction, respectively (both p<0.001 vs vehicle). Compared to vehicle, both chow diet and high fat diet intakes were significantly lower during the first week of semaglutide treatment, but then returned to baseline values. However, semaglutide significantly increased normal water intake and reduced fructose-enriched water intake during the whole treatment period (both p<0.001). Survodutide had a different effect, as it did not alter chow diet and normal water intakes, but significantly reduced high fat diet and fructose-enriched water intakes during the 5-week treatment period. Semaglutide and survodutide significantly reduced plasma insulin levels and the HOMA-IR index of insulin resistance (both p<0.01 vs. vehicle). Both semaglutide and survodutide significantly reduced plasma total cholesterol levels by 24% and 41%, respectively (both p<0.001). This hypocholesterolemic effect led to lower HDL-cholesterol levels (-25%, p<0.001) but unchanged LDL-cholesterol levels for hamsters treated with semaglutide. In contrast, in hamsters treated with survodutide, cholesterol lowering was observed in all lipoprotein fractions, including LDL-cholesterol (-39%, p<0.001). Conclusion: Semaglutide and survodutide both induce weight loss and lower HOMA-IR, but have different effects on food preference and dyslipidemia in the obese hamster model; such effects may be attributed to the GCGR agonism of survodutide. These preclinical data highlight the potential metabolic benefits of the GCGR/GLP-1R dual agonist survodutide for the treatment of obesity and related metabolic comorbidities. Presentation: 6/3/2024

Amylase and lipase levels in the metabolic syndrome and type 2 diabetes: A longitudinal study in rhesus monkeys.

Latent associations between low serum amylase and reduced plasma insulin levels and increased adiposity have been described previously in a small study of asymptomatic middle-aged humans. In the present study, we sought to determine the nature of such changes during the longitudinal progression from metabolically normal to overt type 2 diabetes mellitus (T2DM) in nonhuman primates (NHPs), a disease that appears to be the same in both pathophysiology and underlying mechanisms as that which most commonly develops in middle-aged adult humans. Amylase and lipase levels were characterized in 157 unrelated adult rhesus monkeys (Macaca mulatta); 38% developed T2DM while under study. In all monkeys, multivariable linear regression analysis revealed that amylase could be negatively predicted by % body fat (β -0.29; p = 0.002), age (β -0.27; p = 0.005), and HbA1c (β -0.18; p = 0.037). Amylase levels were positively predicted by lipase levels (β = 0.19; p = -0.024) in all NHPs included in the study. Amylase was significantly lower in NHPs with metabolic syndrome (p < 0.001), prediabetes (PreDM) (p < 0.001), and T2DM (p < 0.001) compared to metabolically normal adult NHPs. Lipase increased in NHPs with PreDM (p = 0.005) and T2DM (p = 0.04) compared to normal NHPs. This is the first longitudinal study of any species, including humans, to show the dynamics of amylase and lipase during the metabolic progression from normal to metabolic syndrome, to PreDM and then to overt T2DM. The extraordinary similarity between humans and monkeys in T2DM, in pancreatic pathophysiology and in metabolic functions give these findings high translational value.

Sustained feeding of a diet high in fat resulted in a decline in the liver's insulin-degrading enzyme levels in association with the induction of oxidative and endoplasmic reticulum stress in adult male rats: Evaluation of 4-phenylbutyric acid

The current study explored the impact of high fat diet (HFD) on hepatic oxidative and endoplasmic reticulum (ER) stress and its insulin degrading enzyme (IDE) content with the injection of 4-phenyl butyric acid (4-PBA) in adult male rats.Following the weaning period, male offspring were distributed among six distinct groups. The corresponding diet was used for 20 weeks, subsequently 4-PBA was administered for three consecutive days. Plasma glucose and insulin levels, HOMA-β (homeostasis model assessment of β-cell), hepatic ER and oxidative stress biomarkers and IDE protein content were assessed.Long-term ingestion of HFD (31 % cow butter) induced oxidative and ER stress in the liver tissue. Accordingly, a rise in the malondialdehyde (MDA) content and catalase enzyme activity and a decrease in the glutathione (GSH) content were detected within the liver of the HFD and HFD + DMSO groups. Consumption of this diet elevated the liver expression of binding immunoglobulin protein (BIP) and C/enhancer-binding protein homologous protein (CHOP) levels while reduced its IDE content. The HOMA-β decreased significantly. The injection of the 4-PBA moderated all the induced changes.Findings from this study indicated that prolonged HFD consumption led to a reduction in plasma insulin levels, likely attributed to pancreatic β cell malfunction, as evidenced by a decline in the HOMA-β index. Also, the HFD appears to have triggered oxidative and ER stress in the liver, along with a decrease in its IDE content.

85-OR: Swi/Snf Controls Transcriptional Programs Required for ß-Cell Development and Postnatal Islet Function

A key feature of diabetes is insufficient functional β-cell mass. Strategies to augment functional β-cell mass include directed differentiation of stem cells towards a β-cell fate, which requires extensive knowledge of transcriptional programs governing differentiation in vivo. Pdx1, an essential transcription factor involved in β-cell differentiation, dynamically recruits coregulators to drive different gene expression programs. A recent study identified the ATP-dependent Swi/Snf chromatin remodeling complex as an important Pdx1-interacting partner. In the developing pancreas, conditional removal of the Brg Swi/Snf ATPase subunit compromised final pancreas mass, and loss of both ATPase subunits, Brg1 and Brm, led to glucose dyshomeostasis. While Swi/Snf is essential during early pancreas development and mature β-cell function, the role of Swi/Snf during endocrine cell development has yet to be explored. Here, we generated a conditional knockout of either Brg1 (Brg1ΔendoBrm+/-), Brm (Brg1Δendo/+Brm-/-), or both subunits (DKOΔendo) during endocrine development using Neurogenin 3 Cre. Four-week-old Brg1ΔendoBrm+/- mice are glucose intolerant, hyperglycemic, and hypoinsulinemic, with no phenotype observed in Brg1Δendo/+Brm-/-mice. Impaired glucose homeostasis of Brg1ΔendoBrm+/- mice was due in part to reduced islet number, impaired insulin secretion, and altered gene expression programs. DKOΔendo mice have not been found at weaning; however, postnatal day 6 DKOΔendo mice are severely hyperglycemic with reduced plasma insulin levels. Single-cell RNA-Seq of embryonic day 15.5 lineage-labeled cells revealed reduced insulin and glucagon transcript in the β-cell and α-cell clusters, respectively, in both Brg1ΔendoBrm+/- and DKOΔendo mice and reduced Neurogenin 3­ transcript in DKOΔendo endocrine progenitor clusters. These data suggest Swi/Snf plays a critical role in governing gene-expression programs essential for endocrine cell development. Disclosure R.K.Davidson: Employee; Eli Lilly and Company. S.Kanojia: None. M.E.Osmulski: None. J.Spaeth: None. Funding National Institutes of Health (R01DK129287, R03DK127129)

81-OR: The Rnf20 Ubiquitin Ligase Is Required for Beta-Cell Identity and Function

Type 1 and Type 2 Diabetes are characterized by a loss of functional β-cell mass. With the incidence of diabetes rising globally, a better understanding of the gene regulatory mechanisms maintaining β-cell functional identity is imperative to improve diabetes therapies. Islet 1 (Isl1) is a LIM-homeodomain class transcription factor that is essential for β-cell maturation and function. Our previous Isl1 studies revealed that it interacts with the histone ubiquitin ligases Ring Finger 20 (Rnf20) and Rnf40 in mouse β-cells, mouse islets, and human islets. Rnf20 and Rnf40 act as homo- or heterodimeric complexes wherein they monoubiquitinate histone 2B to regulate transcription. In mouse β-cell lines, we demonstrated that Rnf20 and Rnf40 are important for β-cell gene expression and insulin secretion, perhaps mediated by their occupancy of Slc2a2 and MafA. Additionally, using proximity ligation assay we showed a robust increase in Isl1 and Rnf20 interactions under high glucose conditions. Based on these findings, we hypothesized that at least Rnf20 is required for β-cell function in adult islets. To evaluate the contribution of Rnf complexes to β-cell maintenance, we developed an adult-inducible Rnf20 β-cell-specific knockout mouse model, termed Rnf20Δβ-cell. By 8 weeks of age (2 weeks after tamoxifen induction) male and female Rnf20Δβ-cell mice became hyperglycemic, severely glucose intolerant, and had reduced plasma insulin levels following a glucose challenge. Additionally, Rnf20Δβ-cell mice had reduced β-cell mass, in parallel with dysregulated expression of glucose-stimulated insulin secretion and β-cell identity mRNAs including Ins I, Slc2a2, Ucn3, Ngn3, and Aldh1a3. Our in vivo findings resemble those observed in adult Isl1 knockout mice. Paired with similar changes in gene expression in the Rnf20 and Isl1 models, and the glucose-responsive interaction between Isl1 and Rnf20 in vitro, our data support the hypothesis that Isl1-Rnf complexes are critical regulators of β-cell function. Disclosure T.Pierre: None. Y.Liu: None. C.S.Hunter: None. Funding National Institutes of Health (DK111483, DK128132)

257-LB: A Novel MODY-Associated Gain-of-Function Mutation in TALK-1 Leads to Islet Dysfunction and Glucose Intolerance

The most islet-restricted and abundantly expressed K+ channel of the human ꞵ-cell, TALK-1, regulates electrical activity and glucose-stimulated insulin secretion (GSIS) . Recently we identified a gain-of-function (GOF) mutation near the pore domain of TALK-1 (Leu114Pro) that causes Maturity-Onset Diabetes of the Young (MODY) in an autosomal dominant manner, but only in a single family. To confirm TALK-1-Leu114Pro as the mutation that causes the MODY phenotype and investigate the impact of TALK-1 GOF on glucose homeostasis, a mouse model containing the TALK-1-Leu114Pro mutation was generated. Interestingly, mice with TALK-1-Leu114Pro mutation show neonatal lethality which may be due to alterations of islet hormone secretion during neonatal development (this was observed in heterozygous TALK-1-Leu114Pro C57BL/6J and homozygous TALK-1-Leu114Pro CD-1 (ICR) mice) . We first confirmed that TALK-1-Leu114Pro mutation resulted in a GOF in β-cell whole-cell K+ currents. On the ꞵ-cell plasma membrane the resulting TALK-1-Leu114Pro hyperpolarizing current blunted glucose-stimulated Ca2+ entry and subsequent Ca2+ oscillations, whereas on the endoplasmic reticulum membrane TALK-1-Leu114Pro enhanced IP3-induced Ca2+ release. TALK-1-Leu114Pro+/- islets also showed decreased GSIS and reduced plasma insulin levels in TALK-1-Leu114Pro+/- mice when compared to controls. TALK-1-Leu114Pro+/- mice exhibit a significant impairment in glucose homeostasis which is likely due to reduced islet Ca2+ influx and GSIS. However, TALK-1 activity in other islet cell types may also contribute to glucose dyshomeostasis in TALK-1-Leu114Pro+/- mice. For example, pancreatic α-cell area and islet glucagon secretion are increased TALK-1-Leu114Pro+/- mice. Taken together, these data prove that the MODY-associated TALK-1-Leu114Pro mutation disrupts glucose homeostasis and suggests that TALK-1 is an islet-restricted target for the treatment for diabetes. Disclosure A. Y. Nakhe: None. P. Dadi: None. K. E. Zaborska: None. D. Jacobson: None.

Reviewing physical exercise in non-obese diabetic Goto-Kakizaki rats.

There is a high incidence of non-obese type 2 diabetes mellitus (non-obese-T2DM) cases, particularly in Asian countries, for which the pathogenesis remains mainly unclear. Interestingly, Goto-Kakizaki (GK) rats spontaneously develop insulin resistance (IR) and non-obese-T2DM, making them a lean diabetes model. Physical exercise is a non-pharmacological therapeutic approach to reduce adipose tissue mass, improving peripheral IR, glycemic control, and quality of life in obese animals or humans with T2DM. In this narrative review, we selected and analyzed the published literature on the effects of physical exercise on the metabolic features associated with non-obese-T2DM. Only randomized controlled trials with regular physical exercise training, freely executed physical activity, or skeletal muscle stimulation protocols in GK rats published after 2008 were included. The results indicated that exercise reduces plasma insulin levels, increases skeletal muscle glycogen content, improves exercise tolerance, protects renal and myocardial function, and enhances blood oxygen flow in GK rats.

Administration of MIP3‐alpha neutralizing antibody reduces the renal infiltration of dendritic cells and Th17s and attenuates progressive proteinuria in obese Dahl salt‐sensitive rats

Recently, we reported the early development of renal injury was associated with renal hyperfiltration along with increased renal macrophage infiltration and macrophage inflammatory protein alpha (MIP3α; inflammatory chemoattractant cytokine) expression in obese SSLepRmutant rats prior to puberty. MIP3α signals through the CCR6 receptor to recruit stimulatory dendritic cells (sDCs), which have been shown to play a pivotal role in cardiorenal injury by increasing pro-inflammatory T-helper 17 cells (Th17s). Therefore, the present study examined whether chronic blockade of MIP3α signaling would reduce the renal infiltration of sDCs and Th17s and slow the early progression of proteinuria in obese SSLepRmutant rats prior to puberty. Four-week-old SS and SSLepRmutant rats were separated into four groups (n=5/group): (1) SS and (2) SSLepRmutant rats treated with vehicle-PBS and (3) SS and (4) SSLepRmutant rats treated with MIP3α neutralizing antibody (MNA; 100 µg/kg, i.p., every other day) for 4 weeks. We found a significant increase in the infiltration of sDCs and Th17s in the kidneys from vehicle-SSLepRmutant rats compared to their lean vehicle-SS counterparts. Chronic treatment with MNA only significantly reduced renal sDCs and Th17s in SSLepRmutant rats. While treatment with MNA did not have an effect on blood glucose and plasma triglyceride and cholesterol levels, MNA markedly reduced plasma insulin levels in SSLepRmutant rats (9.7±2.3 vs. 3.5±0.7 ng/ml respectively; p<0.05). MAP was significantly higher in vehicle-SSLepRmutant rats compared to values measured in vehicle-SS rats (160±10 vs. 127±7 mmHg, respectively p<0.05). However, chronic treatment with MNA had no effect on MAP in the SSLepRmutant rats in comparison to the vehicle- SSLepRmutant rats (150±3 mmHg). At baseline, proteinuria was not markedly elevated in SSLepRmutant rats compared to SS rats (31±15 vs. 10±3 mg/day, respectively). However, proteinuria markedly increased in SSLepRmutant rats versus SS rats over the course of the study (446±54 vs. 51±16 mg/day, respectively; p<0.05). Chronic treatment with MNA significantly decreased proteinuria in SSLepRmutant rats (149±19 mg/day; p<0.05 vs. vehicle-SSLepRmutant rats) while not having any effect in SS rats (41±12 mg/day). Overall, these data indicate MIP3α plays a major role in the recruitment of sDCs and Th17s during the early progression of proteinuria in obese SSLepRmutant rats prior to puberty. These results also suggest that MIP3α may be a novel therapeutic target to inhibit insulin resistance and prevent progressive proteinuria in obese children.

The Effects of Large Volume Liposuction on Body Weight

Objective: To study the effect of large volume liposuction on body weight and total body fat in overweight and obese patients (BMI from 25-35) and in patients with localized accumulation of fats in normal person. Background: Liposuction has become one of the most popular cosmetic procedures performed by broad- certified surgeon.Method: This study was conducted on 31 patients presented with localized accumulation of fat either in thigh, abdomen, back or gluteal region and arms or in generalized overweight patients with BMI 25-30 and obese patients class 1 with BMI 30-35 will undergo large volume liposuction in plastic surgery department, faculty of medicine, Menoufia University . All studied patients were subjected to full history general examination, local examination (for the area to be suctioned). Laboratory investigations as: Complete blood counts (CBC), blood glucose level, kidney function tests , liver function tests and bleeding profile. Results: There were statistically significant difference between preoperative measurements of total body fat and (3months, 6 months) postoperatively (P < 0.01).There were statistically significant difference between the preoperative measurements of visceral fat and postoperative measurements (after 3 months and 6 months) (P < 0.01).Conclusion: We found that the large volume liposuction in our patients significantly reduce the weight, BMI, total body fat, visceral fat, circumference of abdomen and gluteal region, also reduced plasma insulin level. Keywords: Body, Effects, Large Volume, Liposuction, Weight.

Loss-of-function of the long non-coding RNA A830019P07Rik in mice does not affect insulin expression and secretion

Long non-coding RNAs (lncRNAs) contribute to diverse cellular functions and the dysregulation of their expression or function can contribute to diseases, including diabetes. The contributions of lncRNAs to β-cell development, function and survival has been extensively studied in vitro. However, very little is currently known on the in vivo roles of lncRNAs in the regulation of glucose and insulin homeostasis. Here we investigated the impact of loss-of-function in mice of the lncRNA A830019P07Rik, hereafter P07Rik, which was previously reported to be associated with reduced plasma insulin levels. Compared with wild-type littermates, male and female P07Rik mutant mice did not show any defect in glycaemia and plasma insulin levels in both fed and fasted state. Furthermore, P07Rik mutant mice displayed similar glucose and insulin levels in response to an intra-peritoneal glucose tolerance test. Ex vivo, islets from mutant P07Rik released similar amount of insulin in response to increased glucose concentration as wildtype littermates. In contrast with previous reports, our characterization of P07Rik mouse mutants revealed that loss of function of this lncRNA does not affect glucose and insulin homeostasis in mice.

Cholesterol 25-hydroxylase (CH25H) as a promoter of adipose tissue inflammation in obesity and diabetes

ObjectiveExpansion of visceral adipose tissue (VAT) and metabolic inflammation are consequences of obesity and associated with type 2 diabetes (T2DM). Metabolically activated adipose tissue macrophages (ATMs) undergo qualitative and quantitative changes that influence their inflammatory responses. How these cells contribute to insulin resistance (IR) in humans is not well understood. Cholesterol 25-Hydroxylase (CH25H) converts cholesterol into 25-Hydroxycholesterol (25-HC), an oxysterol that modulates immune responses. Using human and murine models, we investigated the role of CH25H in metabolic inflammation. MethodsWe performed transcriptomic (RNASeq) analysis on the human whole AT biopsies and sorted ATMs from obese non-diabetic (NDM) and obese diabetic (DM) subjects to inquire if CH25H was increased in DM. We challenged mice lacking Ch25h with a high-fat diet (HFD) to characterize their metabolic and immunologic profiling. Ch25h KO mice and human adipose tissue biopsies from NDM and DM subjects were analyzed. LC-MS was conducted to measure 25-HC level in AT. In vitro analysis permitted us to investigate the effect of 25-HC on cytokine expression. ResultsIn our RNASeq analysis of human visceral and subcutaneous biopsies, gene pathways related to inflammation were increased in obese DM vs. non-DM subjects that included CH25H. CH25H was enriched in the stromal vascular fraction of human adipose tissue and highly expressed in CD206+ human ATMs by flow cytometry analysis. We measured the levels of the oxysterols, 25-HC and 7α25diHC, in human visceral adipose tissue samples and showed a correlation between BMI and 25-HC. Using mouse models of diet-induced obesity (DIO), we found that HFD-induced Ch25h expression in eWAT and increased levels of 25-HC in AT. On HFD, Ch25h KO mice became obese but exhibited reduced plasma insulin levels, improved insulin action, and decreased ectopic lipid deposit. Improved insulin sensitivity in Ch25h KO mice was due to attenuation of CD11c+ adipose tissue macrophage infiltration in eWAT. Finally, by testing AT explants, bone marrow-derived macrophages (BMDMs) and SVF cells from Ch25h deficient mice, we observed that 25-HC is required for the expression of pro-inflammatory genes. 25-HC was also able to induce inflammatory genes in preadipocytes. ConclusionsOur data suggest a critical role for CH25H/25-HC in the progression of meta-inflammation and insulin resistance in obese humans and mouse models of obesity. In response to obesogenic stimuli, CH25H/25-HC could exert a pro-inflammatory role.

1922-P: Branched-Chain Ketoacid Dehydrogenase Kinase Inhibition Acutely Improves Glycemia and Alters the Response to Feeding in Mice

Circulating increases in branched chain amino acid (BCAA) levels have long been associated with type 2 diabetes and metabolic syndrome. Emerging data also suggest that BCAA catabolism may play a role in heart failure progression. It is hypothesized that decreased catabolism, rather than increased consumption of BCAAs, is responsible for these correlations. Branched chain ketoacid (BCKA) dehydrogenase (BCKDH) kinase (BCKDK) is a negative regulator of BCAA catabolism through its inhibitory phosphorylation of the BCKDH E1a subunit. Using the BCKDK inhibitor molecule BT2, we demonstrate here a reduction of BCAA, BCKA and tissue p-BCKDH levels concomitant with improved glucose tolerance and reduced insulin levels in diet-induced obese mice after only one day of treatment. To investigate the mechanisms underlying this protection, we assessed plasma biomarkers and tissue gene expression after fasting and re-feeding in glucose intolerant high fat diet-fed animals. Remarkably, BT2 treated animals demonstrated reduced plasma glucose levels after re-feed, which was accompanied by dramatic reductions in plasma insulin levels, reduced activation of Akt in peripheral tissues, and a failure to suppress plasma free fatty acids and lipolytic machinery in adipose tissue. RNAseq was performed in liver to assess changes in gene expression profiles, and while over 400 genes were differentially regulated in vehicle treated re-fed mice compared with vehicle treated fasted mice, there were no differentially regulated genes in BT2 re-fed animals compared with BT2 fasted animals. These data suggest that activation of BCAA catabolism with the BCKDK inhibitor BT2 impairs the systemic response to feeding. Disclosure E. Bollinger: Employee; Self; Pfizer Inc. C.P. Siddall: Employee; Self; Pfizer Inc. Employee; Spouse/Partner; Vertex Pharmaceuticals. T. Greizer: None. J.L. Libera: None. G. Hariri: None. E.E. Pashos: Employee; Self; Pfizer Inc. A. Shipstone: None. A. Hadjipanayis: None. Z. Sun: None. G. Xing: None. M.F. Clasquin: Employee; Spouse/Partner; Merck &amp; Co., Inc. Employee; Self; Pfizer Inc. B.B. Zhang: Employee; Spouse/Partner; Janssen Pharmaceuticals, Inc. Employee; Self; Pfizer Inc. Other Relationship; Self; Eli Lilly and Company. R.A. Miller: Employee; Self; Pfizer Inc. R. Roth Flach: Employee; Self; Pfizer Inc.

Cognitive, behavioral and metabolic effects of oral galactose treatment in the transgenic Tg2576 mice

Alzheimer's disease (AD) is the most common neurodegenerative disorder associated with insulin resistance and glucose hypometabolism in the brain. Oral administration of galactose, a nutrient that provides an alternative source of energy, prevents and ameliorates early cognitive impairment in a streptozotocin-induced model (STZ-icv) of the sporadic AD (sAD). Here we explored the influence of 2-month oral galactose treatment (200 mg/kg/day) in the familial AD (fAD) by using 5- (5M) and 10- (10M) month-old transgenic Tg2576 mice mimicking the presymptomatic and the mild stage of fAD, and compared it to that observed in 7-month old STZ-icv rats mimicking mild-to-moderate sAD. Cognitive and behavioral performance was tested by Morris Water Maze, Open Field and Elevated Plus Maze tests, and metabolic status by intraperitoneal glucose tolerance test and fluorodeoxyglucose Positron-Emission Tomography scan. The level of insulin, glucagon-like peptide-1 (GLP-1) and soluble amyloid β1-42 (sAβ1-42) was measured by ELISA and the protein expression of insulin receptor (IR), glycogen synthase kinase-3β (GSK-3β), and pre-/post-synaptic markers by Western blot analysis. Although galactose normalized alterations in cerebral glucose metabolism in all Tg2576 mice (5M+2M; 10M+2M) and STZ-icv rats, it did not improve cognitive impairment in either model. Improvement of reduced grooming behavior and normalization in reduced plasma insulin levels were seen only in 5M+2M Tg2576 mice while in 10M+2M Tg2576 mice oral galactose induced metabolic exacerbation at the level of plasma insulin, GLP-1 homeostasis and glucose intolerance, and additionally increased hippocampal sAβ1-42 level, decreased IR expression and increased GSK-3β activity. The results indicate that therapeutic potential of oral galactose seems to depend on the stage and the type/model of AD and to differ in the absence and the presence of AD-like pathology.

Effect of ursodeoxycholic acid on glycemic markers: A systematic review and meta-analysis of clinical trials.

Ursodeoxycholic acid (UDCA) is widely used to treat liver diseases; however, its potential effect on metabolic parameters has been poorly investigated. Additionally, owing to divergent data, the objective of this meta-analysis was to evaluate the effect of UDCA on glycemic parameters in clinical trials. Clinical trials investigating the impact of UDCA treatment on glycemic markers were searched in PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases (from inception to April 16, 2018). A random-effects model and generic inverse variance method were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. A weighted random-effects meta-regression was performed to evaluate the impact of potential confounders on glycemic parameters. Meta-analysis of seven studies comprising eight treatment arms revealed a significant reduction of fasting glucose levels following UDCA therapy (WMD: -3.30 mg/dL, 95% CI: -6.36, -0.24, p = 0.034; I2 = 28.95%). Also, meta-analysis of two treatment arms indicated a significant reduction of glycated hemoglobin (HbA1c) concentrations (WMD: -0.41% mg/dL, 95% CI: -0.81, -0.01, p = 0.042; I2 = 0%). Additionally, meta-analysis of four treatment arms also revealed a significant reduction in plasma insulin levels (WMD: -1.50 mg/dL, 95% CI: -2.81, -0.19, p = 0.025; I2 = 67.90%) but not significant effect HOMA-IR (WMD: -0.20 mg/dL, 95% CI: -0.42, 0.01, p = 0.057; I2 = 85.34%). Results of this meta-analysis showed that UDCA significantly reduces fasting plasma glucose, HbA1c, and insulin concentrations suggesting a positive impact on glucose homeostasis.

Islet Beta-Cell Specific Deletion of UBL5 Gene Associated with Mitochondrial Stress Leads to Diabetes in Mice and Beta-Cell Impairment/Death

Hyperglycaemia has been shown to cause oxidative stress in pancreatic β-cells, leading to activation of stress responses such as the mitochondrial unfolded protein response (UPRmt). Failure of these responses to adapt to or repair damage from stress results in dysfunction and death of β-cells. Ubiquitin-like protein 5 (UBL-5) is a protein known to have a crucial role in the UPRmt in C. elegans and upregulated during the UPRmt mammals. The aim of this study was to determine whether UBL-5 has a role in maintaining β-cell mass and function through modulating the UPRmt, by generating and characterising tamoxifen-inducible islet β-cell specific UBL-5 knockout mice. Homozygous β-cell UBL-5 knockout mice (UBL5-/-) showed glucose intolerance and lower plasma insulin levels during the OGTT while heterozygous mice (UBL5+/-) showed no difference. UBL5-/- had significantly reduced plasma insulin levels during IVGTT compared to control. Interestingly, UBL5+/- had significantly increased plasma insulin levels during IVGTT. Beta-cell mass was also significantly reduced in UBL5-/-, with most showing signs of frank diabetes (blood glucose &amp;gt;20 mM), polyuria and polydipsia, while UBL5+/- had increased β-cell mass. One week post UBL5 deletion, UBL5-/- mice had significantly increased blood glucose levels and islet cleaved caspase-3 levels compared to controls despite no difference in β-cell mass. In addition islets taken from UBL5-/- mice 1 week post UBL5 gene deletion showed significant decrease in insulin secretion, suggesting that β-cell dysfunction precedes the decrease in β-cell mass. Islets taken from UBL5+/- mice had increased insulin secretion compared to control. Real time PCR data showed a decrease in UPRmt genes (Clpx, Clpp, CHOP, Lonp1, HSP10, HSP70, ATF5) with HSP60 showing increased expression in the UBL5-/- mice one week after gene deletion, while the UBL5+/- mice showed an overall increase in most UPRmt related genes. Disclosure C. Haralambous: None. V. Ntouma: None.

Decreased insulin secretion in pregnant rats fed a low protein diet.

Low protein (LP) diet during pregnancy leads to reduced plasma insulin levels in rodents, but the underlying mechanisms remain unclear. Glucose is the primary insulin secretagogue, and enhanced glucose-stimulated insulin secretion (GSIS) in beta cells contributes to compensation for insulin resistance and maintenance of glucose homeostasis during pregnancy. In this study, we hypothesized that plasma insulin levels in pregnant rats fed LP diet are reduced due to disrupted GSIS of pancreatic islets. We first confirmed reduced plasma insulin levels, then investigated in vivo insulin secretion by glucose tolerance test and ex vivo GSIS of pancreatic islets in the presence of glucose at different doses, and KCl, glibenclamide, and L-arginine. Main findings include (1) plasma insulin levels were unaltered on day 10, but significantly reduced on days 14-22 of pregnancy in rats fed LP diet compared to those of control (CT) rats; (2) insulin sensitivity was unchanged, but glucose intolerance was more severe in pregnant rats fed LP diet; (3) GSIS in pancreatic islets was lower in LP rats compared to CT rats in the presence of glucose, KCl, and glibenclamide, and the response to L-arginine was abolished in LP rats; and (4) the total insulin content in pancreatic islets and expression of Ins2 were reduced in LP rats, but expression of Gcg was unaltered. These studies demonstrate that decreased GSIS in beta cells of LP rats contributes to reduced plasma insulin levels, which may lead to placental and fetal growth restriction and programs hypertension and other metabolic diseases in offspring.

The mTORC2/PKC pathway sustains compensatory insulin secretion of pancreatic β cells in response to metabolic stress

BackgroundCompensation of the pancreatic β cell functional mass in response to metabolic stress is key to the pathogenesis of Type 2 Diabetes. The mTORC2 pathway governs fuel metabolism and β cell functional mass. It is unknown whether mTORC2 is required for regulating metabolic stress-induced β cell compensation. MethodsWe challenged four-week-old β-cell-specific Rictor (a key component of mTORC2)-knockout mice with a high fat diet (HFD) for 4weeks and measured metabolic and pancreatic morphological parameters. We performed ex vivo experiments to analyse β cell insulin secretion and electrophysiology characteristics. Adenoviral-mediated overexpression and lentiviral-ShRNA-mediated knocking down proteins were applied in Min6 cells and cultured primary mouse islets. ResultsβRicKO mice showed a significant glucose intolerance and a reduced plasma insulin level and an unchanged level β cell mass versus the control mice under HFD. A HFD or palmitate treatment enhanced both glucose-induced insulin secretion (GIIS) and the PMA (phorbol 12-myristate 13-acetate)-induced insulin secretion in the control islets but not in the βRicKO islets. The KO β cells showed similar glucose-induced Ca2+ influx but lower membrane capacitance increments versus the control cells. The enhanced mTORC2/PKC proteins levels in the control HFD group were ablated by Rictor deletion. Replenishing PKCα by overexpression of PKCα-T638D restored the defective GIIS in βRicKO islets. ConclusionsThe mTORC2/Rictor pathway modulates β cell compensatory GIIS under nutrient overload mediated by its phosphorylation of PKCα. General significanceThis study suggests that the mTORC2/PKC pathway in β cells is involved in the pathogenesis of T2D.

Impact of weight loss-associated changes in detailed body composition as assessed by whole-body MRI on plasma insulin levels and homeostatis model assessment index

We assessed the effect of weight loss-associated changes in detailed body composition on plasma insulin levels and homeostatic model assessment (HOMA) index to calculate the magnitude of reduction in different adipose tissue depots required to improve insulin sensitivity. A total of 50 subjects aged 20-69 years were studied. The participants were compiled from low-calorie diet interventions and bariatric surgery and differed in their baseline body mass index (BMI; range 21.6-54.4 kg/m2) and degree of weight losses (range -3.3 to -56.9 kg). Detailed body composition and liver fat were measured using whole-body magnetic resonance imaging (MRI). Insulin resistance was assessed by HOMA. Mean body weight decreased by -16.0±13.6 kg. Significant changes were observed in total adipose tissue (TATMRI, range -0.5 to -36.0 kg), total subcutaneous adipose tissue (SATMRI), visceral adipose tissue (VATMRI), skeletal muscle, liver fat, plasma insulin levels and HOMA. Decreases in insulin and HOMA were correlated with reductions in TATMRI, SATMRI, VATMRI (just with HOMA) and liver fat. Losses of 2.9 and 6.5 kg body weight, 2.0 and 5.0 kg TATMRI as well as 1.6 and 6% liver fat were required to decrease plasma insulin levels by 1 μU/ml and HOMAadjusted for baseline HOMA by 1 point. Multiple regression analysis showed that baseline liver fat and changes in liver fat explained 49.7% and 55.1% of the variance in weight loss-associated changes in plasma insulin and HOMA, respectively. Decreases of adipose tissues and liver fat are the major determinants of reduction in plasma insulin levels and improvement in HOMA index.

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.

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.