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Peri-islet glial cells (PIGCs) are positioned to control neuronal-endocrine-vascular cell communication within the islet, but their role in islet cell function is not known. Hypothalamic glial cells become reactive in response to high fat diet (HFD) feeding and are implicated in the pathogenesis of obesity and type 2 diabetes. We hypothesize that metabolic stress such as diet-induced obesity and hyperglycemia promote the expansion of PIGCs, similar to what has been observed in the central nervous system. To test this hypothesis, we used the glial cell marker, glial fibrillary acidic protein (GFAP) , to identify PIGCs and compared GFAP immunoreactivity in pancreas from the following groups. First, pancreas was harvested from HFD- or chow fed control C57BL/6J male mice after 2 days, 2 weeks or 8 weeks on diet (n=6-8/group) . Second, pancreas was taken from 12-wk old db/db male mice and their control littermates with or without empagliflozin (EMPA) treatment (20mg/kg/d for 6 weeks; n=4-7/group) . Islet PIGC area was quantified as GFAP-positive area/total islet area x100%. Mann-Whitney test and one-way ANOVA were used for data analysis. We found that HFD feeding increased mouse pancreatic peri-islet GFAP expression relative to chow controls at 2 days (HFD 1.4±0.2%, chow 0.8±0.1%; p=0.02) , 2 weeks (HFD 3.5±0.4%, chow 1.2±0.1%; p In conclusion, these findings indicate that islet gliosis is observed in two obese and hyperglycemic mouse models and raise the possibility that pancreatic ‘gliosis’ may have a relevant role in islet-cell function regulation under metabolic challenge. Disclosure J.Niu: None. J.B.Moss: None. W.Rosario: Employee; Merck & Co., Inc. R.Arumugam: None. D.J.Hackney: None. R.L.Hull-meichle: Research Support; Casma Therapeutics. J.Tong: None. Funding National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (R01DK097550) ;Department of Veterans Affairs (IBX004063)

Activity in the dopaminergic pathways of the brain is highly sensitive to body weight and metabolic states. Animal studies show that dopamine neurons are important targets for the metabolic hormone insulin with abolished effects in the insulin-resistant state, leading to increases in body weight and food intake. In humans, the influence of central acting insulin on dopamine and effects of their interplay are still elusive.We investigated whether central administered insulin influences dopaminergic activity in striatal regions and whole-brain neural activity. Using a positron emission tomography (PET)/magnetic resonance imaging (MRI) hybrid scanner, we simultaneously performed [11C]-raclopride-PET and resting-state functional MRI in 10 healthy normal-weight men after application of intranasal insulin or placebo on 2 separate days in a randomized, placebo-controlled, blinded, crossover trial.In response to central insulin compared with placebo administration, we observed greater [11C]-raclopride binding potential in the bilateral ventral and dorsal striatum. This suggests an insulin-induced reduction in synaptic dopamine levels. Resting-state striatal activity was lower 15 and 30 minutes after nasal insulin compared with placebo. Functional connectivity of the mesocorticolimbic circuitry associated with differences in dopamine levels: individuals with a stronger insulin-induced effect on dopamine levels showed a stronger increase in functional connectivity 45 minutes after intranasal insulin.This study indicates that central insulin modulates dopaminergic tone in the striatum, which may affect regional brain activity and connectivity. Our results deepen the understanding of the insulin-dopamine interaction and the complex network that underlies the regulation of whole-body metabolism.

Glucagon is generally considered to be a counter-regulatory hormone with a primary role to raise blood glucose concentrations by increasing endogenous glucose production (EGP). However, recent preclinical findings support a paracrine action of glucagon to act directly on pancreatic beta cells to promote nutrient-stimulated insulin secretion. In mice, the divergent actions of glucagon are dependent on glycemic status: during fasting glucagon acts predominantly at the liver to raise blood glucose, whereas in the fed state when glycemia is elevated, the insulinotropic effects predominate to lower glucose. These mechanistic findings have not been extended to human physiology. Therefore, we designed a study to test the hypothesis that in healthy humans glucagon actions are also dependent on ambient glycemia. Subjects received glucagon (100 ng/kg) during fasting euglyemia or experimental hyperglycemia (~150 mg/dl) on separate days. On both days, glycemia was maintained for 60 min prior to a glucagon infusion for an additional 60 min. Blood glucose was monitored at bedside and plasma samples were analyzed for C-peptide and di-deuterated glucose enrichment to calculate HGP. During fasting euglycemia, blood glucose was 85 mg/dl and glucagon elicited an increase to a 60 minute average of 132 mg/dl with a peak at ~156 mg/dl at the end of the infusion. Concordant with increased glycemia was an immediate increase in HGP (1.8x) and a delayed increase in C-peptide AUC (1.5x). For the hyperglycemia studies, blood glucose was maintained at 150 mg/dl before and during glucagon administration. Here, glucagon caused a rapid and robust increase in C-peptide AUC (4x) and a more gradual increase in HGP (2x). This glycemic-dependent behavior of glucagon suggests a physiologic role to promote prandial insulin secretion in healthy subjects. This raises the possibility that this incretin function of glucagon plays a role in β-cell function in diabetic subjects. Disclosure S. M. Gray: None. G. Zhang: None. W. Bennett: None. J. Tong: None. J. Campbell: None. D. A. D’alessio: Advisory Panel; Self; Eli Lilly and Company, Sun Pharmaceutical Industries Ltd., Research Support; Self; Eli Lilly and Company, Merck & Co., Inc. Funding National Institutes of Health (F32DK121420, R01DK101991)

The orexigenic gut hormone, ghrelin, has been implicated in the regulation of appetite, energy homeostasis, and adiposity. We investigated associations of plasma ghrelin changes after consuming weight loss diets with improvements in general adiposity, body fat accumulation, and energy metabolism among overweight and obese adults. We also tested whether short-term ghrelin changes in response to weight-loss diets were predictive of long-term successful weight loss. This study included 217 overweight and obese adults who participated in a weight-loss diet intervention study, the POUNDS Lost trial. Plasma ghrelin levels were measured at baseline and 6 months after the intervention. We examined associations of the 6-month changes in plasma ghrelin levels from the baseline with changes in weight, waist circumference (WC), body fat composition assessed by dual-energy X-ray absorptiometry (DEXA), fat distribution assessed by CT scans, and resting energy expenditure (REE). At baseline, higher ghrelin levels were significantly associated with lower adiposity (weight, WC, and body fat composition) and REE (p Disclosure Y. Heianza: None. Q. Xue: None. G. Bray: None. F. Sacks: None. L. Qi: None. J. Tong: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (DK091718, DK100383, DK115679)

Objective Bariatric surgery acutely improves glucose control, an effect that is generally sustained for years in most patients. The acute postoperative glycemic reduction is at least partially mediated by enhanced incretin secretion and islet function, and occurs independent of caloric restriction, whereas the sustained improvement in glucose control is associated with increased insulin sensitivity. However, studies in humans with bariatric surgery suggest that these elevations are not static but undergo coordinated regulation throughout the postoperative time course. The studies described here test the hypothesis that incretin secretion, islet function, and peripheral insulin sensitivity undergo temporal regulation following bariatric surgery as a means to regulate glucose homeostasis. Methods Incretin secretion, islet function, and insulin sensitivity in mice with vertical sleeve gastrectomy (VSG) were compared to sham-operated controls that were pair-fed for 90d, matching food consumption and body-weight between groups. Results Glucose clearance and insulin secretion were enhanced in VSG mice compared to controls during mixed-meal tolerance tests (MMTT) at 12 and 80 days postoperatively, as were prandial GLP-1, GIP, and glucagon levels. Insulin sensitivity was comparable between groups 14d after surgery, but significantly greater in the VSG group at day 75, despite similar body-weight gain between groups. Glucose stimulated insulin secretion was greater in VSG mice compared to controls in vivo (I.P. glucose injection) and ex vivo (islet perifusion) indicating a rapid and sustained enhancement of β-cell function after surgery. Notably, glycemia following a MMTT was progressively higher over time in the control animals but improved in the VSG mice at 80d despite weight regain. However, meal-stimulated incretin secretion decreased in VSG mice from 10 to 80 days postoperative, as did meal-stimulated and I.P. glucose-stimulated insulin secretion. This occurred over the same time period that insulin sensitivity was enhanced in VSG mice, suggesting postoperative islet output is tightly regulated by insulin demand. Conclusions These data demonstrate a dynamic, multifactorial physiology for improved glucose control after VSG, whereby rapidly elevated insulin secretion is complimented by later enhancements in insulin sensitivity. Critically, the glucose lowering effect of VSG is demonstrably larger than that of caloric-restriction, suggesting these adaptations are mediated by surgical modification of gastrointestinal anatomy and not weight-loss per se., Highlights • β-cell glucose sensitivity is enhanced 90d after VSG compared to controls, coincident with improved glucose tolerance. • Prandial GLP-1 and GIP are elevated 12d following VSG but return to preoperative levels 80d after VSG. • Insulin sensitivity is enhanced 75d after surgery, but not 14d after surgery, in mice with VSG compared to controls. • Mixed-meal glucose control is improved from 12d to 80d in VSG mice, but worsens in controls despite similar body-weight.

Although bariatric surgery was developed primarily to treat morbid obesity, evidence from the earliest clinical observations to the most recent clinical trials consistently demonstrates that these procedures have substantial effects on glucose metabolism. A large base of research indicates that bariatric surgeries such as Roux-en-Y gastric bypass (RYGB), vertical sleeve gastrectomy (VSG), and biliopancreatic diversion (BPD) improve diabetes in most patients, with effects frequently evident prior to substantial weight reduction. There is now unequivocal evidence from randomized controlled trials that the efficacy of surgery is superior to intensive life-style/medical management. Despite advances in the clinical understanding and application of bariatric surgery, there remains only limited knowledge of the mechanisms by which these procedures confer such large changes to metabolic physiology. The improvement of insulin sensitivity that occurs with weight loss (e.g., the result of diet, illness, physical training) also accompanies bariatric surgery. However, there is evidence to support specific effects of surgery on insulin clearance, hepatic glucose production, and islet function. Understanding the mechanisms by which surgery affects these parameters of glucose regulation has the potential to identify new targets for therapeutic discovery. Studies to distinguish among bariatric surgeries on key parameters of glucose metabolism are limited but would be of considerable value to assist clinicians in selecting specific procedures and investigators in delineating the resulting physiology. This review is based on literature related to factors governing glucose metabolism and insulin secretion after the commonly used RYGB and VSG, and the less frequently used BPD and adjustable gastric banding.

Exogenous ghrelin reduces glucose-stimulated insulin secretion and endogenous ghrelin protects against hypoglycemia during starvation. Islet ε-cells produce ghrelin and δ-cells express growth hormone secretagogue receptor (GHSR), suggesting the possibility of a paracrine mechanism for islet ghrelin to reach high local concentrations and affect insulin secretion. GHSR has high constitutive activity and may act independently of ghrelin. The objective in this study was to determine whether an intraislet ghrelin-GHSR axis modulates insulin secretion and glucose metabolism using mouse models lacking ghrelin (Ghrl−/−) or GHSR (Ghsr−/−). Ghsr−/− and Ghsr+/+ mice had comparable islet ghrelin concentrations. Exogenous ghrelin decreased insulin secretion in perifused isolated islets in a GHSR-dependent manner. Islets isolated from Ghrl−/− or Ghsr−/− mice did not differ from controls in glucose-, alanine-, or GLP-1–stimulated insulin secretion during perifusion. Consistent with this finding, Ghrl−/− and Ghsr−/− male mice studied after either 6 or 16 h of fasting had blood glucose concentrations comparable with those of controls following intraperitoneal glucose, or insulin tolerance tests, or after mixed nutrient meals. Collectively, our data provide strong evidence against a paracrine ghrelin-GHSR axis mediating insulin secretion or glucose tolerance in lean, chow-fed adult mice.

Objective The blood–brain barrier (BBB) regulates the entry of substrates and peptides into the brain. Ghrelin is mainly produced in the stomach but exerts its actions in the central nervous system (CNS) by crossing the BBB. Once present in the CNS, ghrelin can act in the hypothalamus to regulate food intake, in the hippocampus to regulate neurogenesis, and in the olfactory bulb to regulate food-seeking behavior. The goal of this study was to determine whether the primary signaling receptor for ghrelin, the growth hormone secretagogue receptor (GHSR), mediates the transport of ghrelin from blood to brain. Methods We utilized the sensitive and quantitative multiple-time regression analysis technique to determine the transport rate of mouse and human acyl ghrelin (AG) and desacyl ghrelin (DAG) in wildtype and Ghsr null mice. We also measured the regional distribution of these ghrelin peptides throughout the brain. Lastly, we characterized the transport characteristics of human DAG by measuring the stability in serum and brain, saturability of transport, and the complete transfer across the brain endothelial cell. Results We found the transport rate across the BBB of both forms of ghrelin, AG, and DAG, were not affected by the loss of GHSR. We did find differences in the transport rate between the two isoforms, with DAG being faster than AG; this was dependent on the species of ghrelin, human being faster than mouse. Lastly, based on the ubiquitous properties of ghrelin throughout the CNS, we looked at regional distribution of ghrelin uptake and found the highest levels of uptake in the olfactory bulb. Conclusions The data presented here suggest that ghrelin transport can occur independently of the GHSR, and ghrelin uptake varies regionally throughout the brain. These findings better our understanding of the gut-brain communication and may lead to new understandings of ghrelin physiology., Highlights • Ghrelin is transported across the BBB in the absence of GHSR. • Human DAG is transported the fastest compared to mDAG > hAG > mAG. • The olfactory bulb contained the greatest amount of ghrelin.

Background Weight regain (WR) has been an emerging problem after Roux-en Y gastric bypass (RYGB) and little is known about the mechanisms of WR after RYGB. Objective To evaluate the mechanisms of WR after RYGB through the postprandial gut hormones response, particularly glucagon-like peptide-1 (GLP-1), which regulates appetite control, energy expenditure, body composition, physical activities, dietary intake, and psychological factors. Setting Duke University Medical Center, Durham, North Carolina. Methods A cross sectional study of 34 patients who underwent RYGB at least 2 years and achieved ≥50% of excess weight loss at 1year was conducted. The subjects were categorized into WR group or sustained weight loss group, based upon whether their WR was ≥15% of postoperative lowest weight. Results The WR group had less augmented postprandial GLP-1 response but exaggerated hyperinsulinemia. Postprandial peptide YY, ghrelin, and glucose were not different between group. Patients who regained weight required less weight-adjusted energy expenditure and had more percentage body fat and less percentage lean mass. The caloric intake and diet composition were comparable between groups; however, the WR group had higher depression scores, binge eating scales, and hunger rating and spent significantly less time on vigorous exercise. Conclusions The mechanisms of WR in patients who were initially successful after RYGB are complex and involved not only the role of postprandial gut hormone response but are also related to energy expenditure adaptation and body composition changes. Moreover, food preference and physical activity may play roles in weight control after bariatric surgery. Further prospective controlled trial is needed to explore the mechanisms of WR.

Context Postbariatric hypoglycemia (PBH), characterized by enteroinsular axis overstimulation and hyperinsulinemic hypoglycemia, is a complication of bariatric surgery for which there is no approved therapy. Objective To evaluate efficacy and safety of avexitide [exendin (9-39)], a glucagon-like peptide-1 antagonist, for treatment of PBH. Methods A multicenter, Phase 2, randomized, placebo-controlled crossover study (PREVENT). Eighteen female patients with PBH were given placebo for 14 days followed by avexitide 30 mg twice daily and 60 mg once daily, each for 14 days in random order. The main outcome measures were glucose nadir and insulin peak during mixed-meal tolerance testing (MMTT) and hypoglycemic events captured by self-monitoring of blood glucose (SMBG), electronic diary, and blinded continuous glucose monitoring (CGM). Results Compared with placebo, avexitide 30 mg twice daily and 60 mg once daily raised the glucose nadir by 21% (P = .001) and 26% (P = .0002) and lowered the insulin peak by 23% (P = .029) and 21% (P = .042), corresponding to 50% and 75% fewer participants requiring rescue during MMTT, respectively. Significant reductions in rates of Levels 1 to 3 hypoglycemia were observed, defined, respectively, as SMBG Conclusion Avexitide administered for 28 days was well tolerated and resulted in robust and consistent improvements across multiple clinical and metabolic parameters, reinforcing the targeted therapeutic approach and demonstrating durability of effect. Avexitide may represent a first promising treatment for patients with severe PBH.

A type 2 diabetes therapeutic merges two complementary drugs with a depot-forming linker to enable once-weekly dosing., There is great interest in identifying a glucagon-like peptide-1 (GLP-1)–based combination therapy that will more effectively promote weight loss in patients with type 2 diabetes. Fibroblast growth factor 21 (FGF21) is a compelling yet previously unexplored drug candidate to combine with GLP-1 due to its thermogenic and insulin-sensitizing effects. Here, we describe the development of a biologic that fuses GLP-1 to FGF21 with an elastin-like polypeptide linker that acts as a sustained release module with zero-order drug release. We show that once-weekly dual-agonist treatment of diabetic mice results in potent weight-reducing effects and enhanced glycemic control that are not observed with either agonist alone. Furthermore, the dual-agonist formulation has superior efficacy compared to a GLP-1/FGF21 mixture, demonstrating the utility of combining two structurally distinct peptides into one multifunctional molecule. We anticipate that these results will spur further investigation into GLP-1/FGF21 multiagonism for the treatment of metabolic disease.

The insulinotropic actions of glucagon-like peptide 1 receptor (GLP-1R) in β-cells have made it a useful target to manage type 2 diabetes. Metabolic stress reduces β-cell sensitivity to GLP-1, yet the underlying mechanisms are unknown. We hypothesized that Glp1r expression is heterogeneous among β-cells and that metabolic stress decreases the number of GLP-1R–positive β-cells. Here, analyses of publicly available single-cell RNA-Seq sequencing (scRNASeq) data from mouse and human β-cells indicated that significant populations of β-cells do not express the Glp1r gene, supporting heterogeneous GLP-1R expression. To check these results, we used complementary approaches employing FACS coupled with quantitative RT-PCR, a validated GLP-1R antibody, and flow cytometry to quantify GLP-1R promoter activity, gene expression, and protein expression in mouse α-, β-, and δ-cells. Experiments with Glp1r reporter mice and a validated GLP-1R antibody indicated that >90% of the β-cells are GLP-1R positive, contradicting the findings with the scRNASeq data. α-cells did not express Glp1r mRNA and δ-cells expressed Glp1r mRNA but not protein. We also examined the expression patterns of GLP-1R in mouse models of metabolic stress. Multiparous female mice had significantly decreased β-cell Glp1r expression, but no reduction in GLP-1R protein levels or GLP-1R–mediated insulin secretion. These findings suggest caution in interpreting the results of scRNASeq for low-abundance transcripts such as the incretin receptors and indicate that GLP-1R is widely expressed in β-cells, absent in α-cells, and expressed at the mRNA, but not protein, level in δ-cells.

Objective: Because higher iron level is associated with increased risk of type 2 diabetes and bariatric surgery is known to alter iron homeostasis, we examined the effects of tissue iron stores on glycemic outcome after bariatric surgery. Research Design and Methods: We performed a retrospective analysis of glycemia outcomes after Roux-en Y gastric bypass (RYGB) or vertical sleeve gastrectomy (VSG) in individuals with elevated hemoglobin A1c (HbA1c) as a function of serum ferritin before and after surgery, using two large and independent electronic health databases from the Carolinas Collaborative and University of Michigan. Results: Improvement of HbA1c, weight, and alanine aminotransferase (ALT) was comparable between the two procedures 6-12 months after surgery. For gastric bypass procedures, however, the improvement in HbA1c and the chance of normalizing HbA1c were inversely proportional to preoperative ferritin, while no such relationship existed for gastrectomy. The improvement in ALT was correlated with the decrease in serum ferritin after surgery for both surgery types. Changes in hemoglobin were also related to preoperative ferritin. Conclusion: Preoperative iron stores may modulate glycemic improvement after bariatric surgery differentially depending on procedure type. This has implications regarding the operation of choice in certain patient populations. Disclosure J. Tong: None. R. Alvarez: None. G.B. Russell: None. A.N. Khouri: None. R.J. Seeley: Consultant; Self; Ionis Pharmaceuticals, Inc., Kintai, Kintai, Novo Nordisk A/S, Sanofi, Scohia Pharma Inc. Research Support; Self; AstraZeneca, Novo Nordisk A/S, Pfizer Inc. Stock/Shareholder; Self; Redesign Health. D.A. McClain: None. Funding National Institutes of Health (R01DK097550)

Bariatric surgeries improve glucose control in part by enhancing the glucose sensitivity of insulin secretion. In a mouse model of sleeve gastrectomy (SG), prandial secretion of the incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are increased and positively correlated with ex vivo insulin secretion. However, several previous studies suggest that GLP-1 action is dispensable for the effects of SG on glucose homeostasis. Therefore, we hypothesized that improved glucose control and islet function after SG require β-cell GIP receptors (GIPR). We tested this hypothesis using an inducible, β-cell specific GIPR knockout mouse line (GIPRβcell-/-). Within two weeks of surgery control mice with SG have reductions of bodyweight and glucose excursion during either a mixed-meal (MMTT) or intraperitoneal glucose tolerance test (IPGTT) compared to sham-operated animals. Islets isolated from control SG mice have enhanced glucose stimulated insulin secretion (GSIS) compared to islets from sham-operated controls in perifusion experiments, similar to our previous reports. While GIPRβcell-/- mice given SG evince improvements in bodyweight and MMTT glucose disposal compared to sham operated GIPRβcell-/- animals, they do not display the postoperative improvement of IP glucose tolerance seen in control mice given SG. Moreover, islets from GIPRβcell-/- SG mice do not have the improved GSIS typical of this surgery. These data indicate that changes in bodyweight and prandial glucose homeostasis after SG are not dependent on GIPR signaling. However, β-cell GIPR are necessary for enhancing intrinsic islet function after SG. These results support enteroendocrine signaling as a mediator for one of the key components of metabolic improvement after bariatric surgery. Disclosure J.D. Douros: None. J. Campbell: Research Support; Self; Eli Lilly and Company, Novo Nordisk Inc. Speaker’s Bureau; Self; Merck Sharp & Dohme Corp. J. Tong: None. D. D’Alessio: Advisory Panel; Self; Eli Lilly and Company. Consultant; Self; Intarcia Therapeutics. Research Support; Self; Ansh Labs, Eli Lilly and Company, Merck Sharp & Dohme Corp. Other Relationship; Self; Novo Nordisk A/S. Funding 1F32DK115031-01

Circulating proglucagon peptides (PGP) are produced in islet α-cells, enteroendocrine L-cells. Release of PGP is thought to be tissue specific, e.g. α-cells make glucagon and L-cells make GLP-1 through predominant actions of proconvertases 2 and 1/3 (PC2 and PC1/3). However, this dichotomous model has recently been challenged. To address the contribution of the gut and pancreas to plasma PGP we developed 4 novel sandwich ELISA assays and applied them in studies with PGP stimulation from the islet (IV arginine) and intestine (meal). Monoclonal antibodies were raised in mice with genetic ablation of proglucagon transcription. Clones were screened and selected for affinity and specificity, and assays for glucagon, GLP-1, glicentin and oxyntomodulin developed. Eight healthy humans received 5 g arginine intravenously after a 12 hour fast and had blood sampled for 15 minutes; an additional 10 consumed a liquid mixed nutrient meal and prandial blood was taken for 180 minutes. None of the assays registered signal in plasma from proglucagon null mice, and specificity, background and cross-reactivity were acceptable in each. In response to IV arginine plasma glucagon increased 4-fold, and GLP-1 1.5-fold, with significant increases in 15-minute AUC; there was no significant change in either glicentin or oxyntomodulin. In response to meal ingestion there was no change in circulating glucagon, but oxyntomodulin, GLP-1 and glicentin increased 2, 3, and 4-fold respectively. These findings are generally compatible with PC1/3 dominant processing of PGP in the gut, but raise the possibility that α-cells produce both PC2 (glucagon) and PC1/3 (GLP-1) products.

Bariatric surgeries, including vertical sleeve gastrectomy (VSG), resolve diabetes in 40–50% of patients. Studies examining the molecular mechanisms underlying this effect have centered on the role of the insulinotropic glucagon-like peptide 1 (GLP-1), in great part because of the ∼10-fold rise in its circulating levels after surgery. However, there is currently debate over the role of direct β-cell signaling by GLP-1 to mediate improved glucose tolerance following surgery. In order to assess the importance of β-cell GLP-1 receptor (GLP-1R) for improving glucose control after VSG, a mouse model of this procedure was developed and combined with a genetically modified mouse line allowing an inducible, β-cell–specific Glp1r knockdown (Glp1rβ-cell-ko). Mice with VSG lost ∼20% of body weight over 30 days compared with sham-operated controls and had a ∼60% improvement in glucose tolerance. Isolated islets from VSG mice had significantly greater insulin responses to glucose than controls. Glp1r knockdown in β-cells caused glucose intolerance in diet-induced obese mice compared with obese controls, but VSG improved glycemic profiles to similar levels during oral and intraperitoneal glucose challenges in Glp1rβ-cell-ko and Glp1rWT mice. Therefore, even though the β-cell GLP-1R seems to be important for maintaining glucose tolerance in obese mice, in these experiments it is dispensable for the improvement in glucose tolerance after VSG. Moreover, the metabolic physiology activated by VSG can overcome the deficits in glucose regulation caused by lack of β-cell GLP-1 signaling in obesity.

Ghrelin is a 28-amino acid polypeptide that regulates feeding, glucose metabolism, and emotionality (stress, anxiety, and depression). Plasma ghrelin circulates as desacyl ghrelin (DAG) or, in an acylated form, acyl ghrelin (AG), through the actions of ghrelin O-acyltransferase (GOAT), exhibiting low or high affinity, respectively, for the growth hormone secretagogue receptor (GHSR) 1a. We investigated the role of endogenous AG, DAG, and GHSR1a signaling on anxiety and stress responses using ghrelin knockout (Ghr KO), GOAT KO, and Ghsr stop-floxed (Ghsr null) mice. Behavioral and hormonal responses were tested in the elevated plus maze and light/dark (LD) box. Mice lacking both AG and DAG (Ghr KO) increased anxiety-like behaviors across tests, whereas anxiety reactions were attenuated in DAG-treated Ghr KO mice and in mice lacking AG (GOAT KO). Notably, loss of GHSR1a (Ghsr null) did not affect anxiety-like behavior in any test. Administration of AG and DAG to Ghr KO mice with lifelong ghrelin deficiency reduced anxiety-like behavior and decreased phospho-extracellular signal-regulated kinase phosphorylation in the Edinger-Westphal nucleus in wild-type mice, a site normally expressing GHSR1a and involved in stress- and anxiety-related behavior. Collectively, our data demonstrate distinct roles for endogenous AG and DAG in regulation of anxiety responses and suggest that the behavioral impact of ghrelin may be context dependent.

ObjectiveTo compare the effects of acyl ghrelin (AG) and desacyl ghrelin (DAG) on blood pressure (BP), heart rate (HR) and other autonomic parameters in healthy humans and to elucidate the hormonal mechanisms through which AG could exert its cardiovascular effects.DesignSeventeen healthy participants underwent frequent monitoring of systolic (sBP) and diastolic blood pressure (dBP), HR, respiratory rate (RR) and body surface temperature (Temp) during continuous infusion of AG, DAG, combined AG + DAG or saline control before and during an IV glucose tolerance test on 4 separate days. Plasma catecholamines, renin and aldosterone levels were also measured. Differences in outcome measures between treatment groups were assessed using mixed-model analysis.ResultsCompared to the saline control, AG and combined AG + DAG infusions decreased sBP, dBP, mean arterial blood pressure (MAP), HR and Temp. In contrast, DAG infusion did not alter BP, RR or Temp, but did decrease HR. The AG and AG + DAG infusions also raised plasma aldosterone levels compared to saline (P ConclusionsThe decrease in BP, HR, RR and Temp with AG infusion suggests mediation through the autonomic nervous system. The lack of response to DAG suggests that these autonomic effects require activation of the ghrelin receptor.

Context Eating habits and food craving are strongly correlated with weight status. It is currently not well understood how psychological and behavioral factors influence both weight loss and weight regain. Objective To examine the associations between psychological and behavioral predictors with weight changes and energy intake in a randomized controlled trial on weight loss. Design and setting The Prevention of Obesity Using Novel Dietary Strategies is a dietary intervention trial that examined the efficacy of 4 diets on weight loss over 2 years. Participants were 811 overweight (body mass index, 25-40.9 kg/m2; age, 30-70 years) otherwise healthy adults. Results Every 1-point increase in craving score for high-fat foods at baseline was associated with greater weight loss (-1.62 kg, P = .0004) and a decrease in energy intake (r = -0.10, P = .01) and fat intake (r = -0.16, P Conclusions Craving for high-fat foods is predictive of greater weight loss, whereas craving for carbohydrates is predictive of less weight loss. Cognitive restraint is predictive of less weight loss and more weight regain. Interventions targeting different psychological and behavioral factors can lead to greater success in weight loss.

Background and aim In most species, including humans, food preference is primarily controlled by nutrient value. However, the gut-brain pathways involved in preference learning remain elusive. The aim of the present study, performed in C57BL6/J mice, was to characterize the roles in nutrient preference of two critical elements of gut-brain pathways, i.e. the duodenum and vagal gut innervation. Methods Adult wild-type C57BL6/J mice from a normal-weight cohort sustained one of the following three procedures: duodenal-jejunal bypass intestinal rerouting (DJB), total subdiaphragmatic vagotomy (SDV), or sham surgery. Mice were assessed in short-term two-bottle preference tests before and after 24 h s exposures to solutions containing one of glutamate, lipids, sodium, or glucose. Results DJB and SDV interfered in preference formation in a nutrient-specific manner: whereas normal preference learning for lipids and glutamate was disrupted by both DJB and SDV, these interventions did not alter the formation of preferences for glucose. Interestingly, sodium preferences were abrogated by DJB but not by SDV. Conclusions Different macronutrients make use of distinct gut-brain pathways to influence food preferences, thereby mirroring nutrient-specific processes of food digestion. Specifically, whereas both vagal innervation and duodenal sensing appear critical for generating responses to fats and protein, glucose preferences recruit post-duodenal, vagal-independent pathways in pair with the control of glucose homeostasis. Overall, our data suggest that the physiological processes involved in digesting and absorbing fats, amino acids, and glucose overlap with those mediating learned preferences for each of these nutrients.

As the incidence of diabetes increases, the development of new therapeutic strategies is essential. Recent evidence supports combination therapies that incorporate complementary mechanisms of action as potent and effective. We have developed a unimolecular dual agonist by combining the incretin glucagon-like peptide-1 (GLP-1) and the metabolic regulatory factor fibroblast growth factor 21 (FGF-21). We hypothesized that this agent would merge the insulinotropic and anorectic effects of GLP-1 with enhanced insulin sensitivity and energy expenditure due to FGF-21 signaling. The dual agonist is a single polypeptide fusion, with GLP-1 located at the N-terminus and FGF-21 at the C-terminus. This orientation allows each peptide to activate its receptor, while the linear architecture enables facile synthesis in a bacterial expression system. Fused between GLP-1 and FGF-21 is an elastin-like polypeptide (ELP) that serves as both a flexible linker and a circulation-enhancing scaffold. The ELP used herein is designed such that it undergoes a thermally initiated phase transition triggered by body heat upon subcutaneous (s.c.) injection, resulting in a slow-dissolving drug depot. A single s.c. injection of GLP-1-ELP-FGF-21 into diabetic db/db mice significantly reduced ambient blood glucose levels from above 300 mg/dL to sustained levels below 150 mg/dL for 8 days. Db/db mice treated once-weekly for 4 weeks had mean body weights that were 24% and 16% lower than mice treated weekly with vehicle or long-acting GLP-1, respectively. Dual agonist treatment also conferred greater reductions in % HbA1c and circulating lipids. These results demonstrate the efficacy of a novel unimolecular drug to correct multiple metabolic abnormalities in a diabetic mouse model. Moreover, the improved outcomes compared to a GLP-1-based drug support the dual agonist mechanism. Incorporation of an ELP allows advantageous temporal control of drug delivery, thus making the GLP-1/FGF-21 dual agonist a promising new diabetes treatment. Disclosure C.A. Gilroy: Employee; Spouse/Partner; Becton, Dickinson and Company. M. Capozzi: None. J.C. Su: None. J. Tong: None. D.A. D'Alessio: Advisory Panel; Self; Eli Lilly and Company. Research Support; Self; Eli Lilly and Company, Merck & Co., Inc. J. Campbell: Research Support; Self; Eli Lilly and Company. Speaker's Bureau; Self; Merck Sharp & Dohme Corp. A. Chilkoti: Advisory Panel; Self; PhaseBio Pharmaceuticals, Inc. Funding National Institutes of Health

Ghrelin is a 28-peptide hormone that was originally discovered as a ligand for the growth hormone secretagogue receptor (GHSR) and noted for its roles in food intake and feeding behavior. Beyond this, ghrelin may also regulate glucose tolerance and insulin secretion. In times of starvation, ghrelin defends against hypoglycemia. Contrastingly, ghrelin removal increases insulin secretion and improves glucose tolerance in metabolically-stressed mice. Though ghrelin is predominantly produced by stomach X/A cells, it is also made in the pancreas. Within the pancreatic islet, ghrelin is produced by ε-cells and GHSR is predominantly expressed in somatostatin-secreting δ-cells. This positioning suggests that, locally, islet ghrelin could reach interstitial levels that are higher than detected in circulation and act in a paracrine manner to inhibit insulin secretion. Additionally, GHSR has high constitutive activity and may act in the absence of ghrelin. We hypothesized that a ghrelin-GHSR paracrine axis within the islet modulates insulin secretion and tested this using parallel in vivo and ex vivo approaches in genetic rodent models lacking ghrelin (Ghrl-/-) or GHSR (GHSR-/-). Glycemic responses in GHSR-/- and GHSR+/+male mice did not differ after i.p. glucose tolerance tests (IPGTT) after a 6- or 16-hr fast, oral mixed meal tolerance test (MMTT), or insulin sensitivity during insulin tolerance test (ITT). Female GHSR-/- mice had impaired glucose tolerance after 6-hr fast IPGTT compared to GHSR+/+ (glucose AUC, p=0.01) but did not differ from controls during 16-hr fasted IPGTT, MMTT, or ITT. These data suggest constitutive GHSR activity does not mediate in vivo glucose tolerance. Ghrl-/- and Ghrl+/+ male mice did not differ in glycemia in response to IPGTTs, MMTT, or ITT. Female Ghrl-/- mice showed a slight improvement compared to Ghrl+/+ during MMTT (glucose AUC, p=0.04) but did not differ in other tests. Thus, endogenous ghrelin does not substantially alter glucose tolerance. Given that many factors can affect in vivo glucose tolerance, we perifused isolated islets. Here, exogenous ghrelin robustly decreased glucose-stimulated insulin secretion (GSIS, p

Avexitide (formerly exendin 9-39) is a first-in-class glucagon-like peptide-1 (GLP-1) receptor antagonist in development as a liquid formulation for subcutaneous (SC) injection for treatment of post-bariatric hypoglycemia (PBH). PBH, a rare disease with high unmet medical need and no approved pharmacologic therapy, develops as a late complication of bariatric surgery. Patients with PBH exhibit exaggerated GLP-1 levels with dysregulated secretion of insulin and symptomatic hypoglycemia 1-3 hours after meals, putting them at risk for severe neuroglycopenic outcomes such as loss of consciousness, seizures, falls and motor vehicle accidents. Previous studies involving in-clinic SC injection of avexitide in patients with PBH have demonstrated attenuation of the insulinotropic effect of GLP-1 and prevention of hypoglycemia. PREVENT (NCT03373435), a Phase 2, multi-center, placebo-controlled study is the first to investigate the safety and durability of effect of 28-day outpatient dosing of SC avexitide in patients with severe, refractory PBH. Eighteen patients enrolled across five U.S. academic centers received placebo SC injections for 14 days in a single-blinded manner followed by avexitide SC 30 mg twice daily (BID) injections for 14 days and 60 mg once daily (QD) injections for 14 days, for a total of 28 days active dosing, in a double-blinded to dose, cross-over design. The primary efficacy endpoint of improved postprandial glucose nadir during mixed meal tolerance testing (MMTT) was achieved with avexitide 30 mg BID (57.1 vs 47.1 mg/dL; p = 0.001) and 60 mg QD (59.2 vs 47.1 mg/dL; p=0.0002), with fewer patients requiring glycemic rescue during each of the active dosing regimens than during placebo dosing. The secondary endpoint of reduced postprandial insulin peak during MMTT was achieved with avexitide 30 mg BID (349.5 vs 454.5 μIU/mL; p < 0.03) and 60 mg QD (357.2 vs 454.5 μIU/mL; p = 0.04). Metabolic and clinical improvements were monitored in the outpatient setting with electronic diaries and continuous glucose monitoring (CGM). Patients experienced fewer episodes of hypoglycemia (hypoglycemia symptoms confirmed by self-monitored blood glucose (SMBG) concentrations of

Bariatric surgeries including vertical sleeve gastrectomy (VSG) ameliorate obesity and diabetes. Weight loss and accompanying increases to insulin sensitivity contribute to improved glycemia after surgery; however, studies in humans also suggest weight-independent actions of bariatric procedures to lower blood glucose, possibly by improving insulin secretion. To evaluate this hypothesis, we compared VSG-operated mice with pair-fed, sham-surgical controls (PF-Sham) 2 weeks after surgery. This paradigm yielded similar postoperative body weight and insulin sensitivity between VSG and calorically restricted PF-Sham animals. However, VSG improved glucose tolerance and markedly enhanced insulin secretion during oral nutrient and i.p. glucose challenges compared with controls. Islets from VSG mice displayed a unique transcriptional signature enriched for genes involved in Ca(2+) signaling and insulin secretion pathways. This finding suggests that bariatric surgery leads to intrinsic changes within the islet that alter function. Indeed, islets isolated from VSG mice had increased glucose-stimulated insulin secretion and a left-shifted glucose sensitivity curve compared with islets from PF-Sham mice. Isolated islets from VSG animals showed corresponding increases in the pulse duration of glucose-stimulated Ca(2+) oscillations. Together, these findings demonstrate a weight-independent improvement in glycemic control following VSG, which is, in part, driven by improved insulin secretion and associated with substantial changes in islet gene expression. These results support a model in which β cells play a key role in the adaptation to bariatric surgery and the improved glucose tolerance that is typical of these procedures.

Restrictive eating disorders (ED) are increasing and represent a serious risk to the health of adolescent females. Restrictive ED in youth are often treated through aggressive short-term refeeding. Although evidence supports that this intervention is the “gold standard” for improving ED outcomes in youth, little research has specifically probed appetite and meal-related responses to this type of intensive, short-term refeeding in newly diagnosed individuals. Information about appetite and meal-related dysfunction could provide valuable insights regarding treatment-interfering features of ED in both acute inpatient and longer-term outpatient treatment. The purpose of this study was to evaluate the hunger, fullness, olfactory, and gustatory responses of adolescents with newly-diagnosed restrictive ED and to probe how and when these responses are altered by refeeding. Using a quasi-experimental ecologically valid methodology, this study described and compared profiles of hunger, fullness, olfactory, and gustatory responses in adolescent females (n = 15) with newly diagnosed restrictive ED at hospital admission (i.e., severe malnutrition) and after medical refeeding, in comparison to healthy controls (n = 15). Results showed that newly diagnosed (i.e., malnourished) adolescents with ED showed significantly different meal-related experiences than controls. Refeeding improved some of these differences, but not all. Following refeeding, females with ED continued to show lower hunger, greater fullness, and lower pleasantness of smell ratings compared to controls. Unpleasantness of taste ratings maladaptively increased, such that females who were re-fed reported more aversive scents than pre-treatment. Profiles of meal-related responses were also identified and compared between groups. The applicability of these findings are discussed within the context of critical periods of change during refeeding treatment and potentially promising intervention targets that might enhance treatment outcomes for adolescents with newly onset, restrictive ED.

Reductions in calorie intake contribute significantly to the positive outcome of bariatric surgeries. However, the physiological mechanisms linking the rerouting of the gastrointestinal tract to reductions in sugar cravings remain uncertain. We show that a duodenal-jejunal bypass (DJB) intervention inhibits maladaptive sweet appetite by acting on dopamine-responsive striatal circuitries. DJB disrupted the ability of recurrent sugar exposure to promote sweet appetite in sated animals, thereby revealing a link between recurrent duodenal sugar influx and maladaptive sweet intake. Unlike ingestion of a low-calorie sweetener, ingestion of sugar was associated with significant dopamine effluxes in the dorsal striatum, with glucose infusions into the duodenum inducing greater striatal dopamine release than equivalent jejunal infusions. Consistently, optogenetic activation of dopamine-excitable cells of the dorsal striatum was sufficient to restore maladaptive sweet appetite in sated DJB mice. Our findings point to a causal link between striatal dopamine signaling and the outcomes of bariatric interventions.

The ghrelin-producing ε cell represents the fifth endocrine cell type in human pancreatic islets. The abundance of ε cells in adult pancreas is extremely low, which has hampered the investigation on the molecular pathways regulating the development and the function of this cell type. In this study, we explored the molecular features defining the function of pancreatic ε cells isolated from adult nondiabetic donors using single-cell RNA sequencing technology. We focus on transcription factors, cell surface receptors, and genes involved in metabolic pathways that contribute to regulation of cellular function. Furthermore, the genes that separate ε cells from the other islet endocrine cell types are presented. This study expands prior knowledge about the genes important for ε cell functioning during development and provides a resource to interrogate the transcriptome of this rare human islet cell type.

Consensus on whether preoperative (pre-op) hyperglycemia predicts adverse surgical outcomes is lacking. The objective of the study was to evaluate the relationship between pre-op HbA1c and postoperative (post-op) surgical outcomes in patients with diabetes mellitus (DM). Patients who underwent bariatric surgery between January 2000 and April 2017 and met the diagnostic criteria of DM and had pre-op HbA1c measures were studied. Logistic and GEE linear regression were used to examine the association between pre-op HbA1c and post-op morbidity and mortality and percentage weight loss (%WL) at 30 days and 1 year. A total of 2173 patients (mean age 48.6 ± 10.6, pre-op weight: 297.5 ± 60.3 lb, 75% females) were evaluated. Among them, 49.6% had HbA1c of < 7%, 26.4% had HbA1c 7-8%, and 23.9% had HbA1c > 8%. The incidence of 30-day complications (readmission, reoperation, bleeding, pulmonary embolism, leak) was 6.1% and 30-day mortality was 0.1%. These rates did not differ between HbA1c groups or between Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), gastric band, and duodenal switch (DS) procedures. There was no significant association between pre-op HbA1c and complication rates or %WL at 30 days post-op. However, we detected an association between HbA1c and 1-year %WL (p = 0.014) in that 1% increase in pre-op HbA1c was associated with 0.74% less WL at 1 year after adjusting for confounders (95% CI: -1.08% to -0.41%, p < 0.0001). Females lost less weight than males (p = 0.0009) and patients with ≥ 1 anti-hypertensive medications pre-op lost less weight than those without (p < 0.0001) at 1 year. Furthermore, patients operated with DS lost more while those with SG and banding lost less weight than with RYGB. In conclusion, pre-op HbA1c was not associated with post-op morbidity or mortality but it is a significant predictor for post-op WL at 1 year. Our data suggest that tighter glycemic control pre-op may lead to better weight loss outcomes after bariatric surgery in patients with DM. Disclosure C.B. Ortega: None. H. Lee: None. D. Portenier: Consultant; Self; Medtronic, Allergan, Teleflex, Gore, Intuitive. Research Support; Self; Teleflex. A.D. Guerron: Other Relationship; Self; Medtronic, Gore. Consultant; Self; Mederi, Levita. J. Tong: None.

High dietary iron intake is associated with impaired islet-cell function and increased risk of type 2 diabetes mellitus (T2DM) while iron chelation leads to improved glucose tolerance. Bariatric surgery has multiple metabolic benefits but iron-deficiency anemia is a common occurrence following surgery, presumably because of preferential iron absorption in the upper intestine. We hypothesized that a duodenal-jejunal bypass (DJB) procedure that bypasses the proximal small bowel and vertical sleeve gastrectomy (VSG) that eliminate 80% of the stomach without altering the intestine would have differential effects on iron metabolism and glucose homeostasis. C57BL6J mice were fed either high- (2000 ppm) or low-iron diet (4 ppm) for 16 weeks before DJB (n=6 per diet group), VSG (n=6/7 per diet group) or sham surgery (n = 11 per diet group). Intraperitoneal glucose, and insulin, tolerance tests were performed at Day 0, 10 and 20 after surgery. Compared to animals given a low-iron diet, 4 months of high-iron diet significantly impaired glucose tolerance (p Disclosure J. Niu: None. J.D. Douros: None. J. Campbell: None. M. Capozzi: None. S.M. Gray: None. F. Lorenzo: None. D. D'Alessio: Consultant; Self; Intarcia Therapeutics, Inc., Eli Lilly and Company, Merck & Co., Inc., Novo Nordisk A/S. D. McClain: None. J. Tong: None.

Emerging evidence supports the importance of ghrelin to defend against starvation-induced hypoglycemia. This effect may be mediated by inhibition of glucose-stimulated insulin secretion as well as reduced insulin sensitivity. However, administration of ghrelin during meal consumption also stimulates the release of glucagon-like peptide 1 (GLP-1), an incretin important in nutrient disposition. The objective of this study was to evaluate the interaction between ghrelin and GLP-1 on parameters of glucose tolerance following a mixed-nutrient meal. Fifteen healthy men and women completed the study. Each consumed a standard meal on four separate occasions with a superimposed infusion of 1) saline, 2) ghrelin, 3) the GLP-1 receptor antagonist exendin(9-39) (Ex9), or 4) combined ghrelin and Ex9. Similar to previous studies, infusion of ghrelin caused glucose intolerance, whereas Ex9 had a minimal effect. However, combined ghrelin and Ex9 resulted in greater postprandial glycemia than either alone, and this effect was associated with impaired β-cell function and decreased glucose clearance. These findings suggest that in the fed state, stimulation of GLP-1 mitigates some of the effect of ghrelin on glucose tolerance. This novel interaction between gastrointestinal hormones suggests a system that balances insulin secretion and glucose disposal in the fed and fasting states.

Gastrointestinal (GI) hormones are increasingly recognized for their roles in the control of appetite and obesity. In this chapter, we review selected regulatory factors secreted from the gut including ghrelin, glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY (PYY), fibroblast growth factor 19 (FGF19), and bile acids as they relate to appetite, energy balance, obesity, and obesity-related disease states. We also describe emerging pharmacologic interventions that impact these hormones and promote weight loss. In this rapidly developing field, we have only limited understanding of the broad range of actions of the gastrointestinal hormones, including their interplay with gut microbiota. Not surprisingly, data in the pediatric population are limited. Further research is critical to understand how gastrointestinal hormones affect pediatric obesity and may lead to therapeutic strategies for metabolic and nutritional diseases.

Ghrelin is a 28-amino acid peptide secreted mainly from the X/A-like cells of the stomach. Ghrelin is found in circulation in both des-acyl (dAG) and acyl forms (AG). Acylation is catalyzed by the enzyme ghrelinO-acyltransferase (GOAT). AG acts on the GH secretagogue receptor (GHSR) in the CNS to promote feeding and adiposity and also acts on GHSR in the pancreas to inhibit glucose-stimulated insulin secretion. These well-described actions of AG have made it a popular target for obesity and type 2 diabetes mellitus pharmacotherapies. However, despite the lack of a cognate receptor, dAG appears to have gluco-regulatory action, which adds an additional layer of complexity to ghrelin's regulation of glucose metabolism. This review discusses the current literature on the gluco-regulatory action of the ghrelin system (dAG, AG, GHSR, and GOAT) with specific emphasis aimed toward distinguishing AG vs dAG action.

Unacylated ghrelin (UAG) is the predominant ghrelin isoform in the circulation. Despite its inability to activate the classical ghrelin receptor, preclinical studies suggest that UAG may promote β-cell function. We hypothesized that UAG would oppose the effects of acylated ghrelin (AG) on insulin secretion and glucose tolerance. AG (1 µg/kg/h), UAG (4 µg/kg/h), combined AG+UAG, or saline were infused to 17 healthy subjects (9 men and 8 women) on four occasions in randomized order. Ghrelin was infused for 30 min to achieve steady-state levels and continued through a 3-h intravenous glucose tolerance test. The acute insulin response to glucose (AIRg), insulin sensitivity index (SI), disposition index (DI), and intravenous glucose tolerance (kg) were compared for each subject during the four infusions. AG infusion raised fasting glucose levels but had no effect on fasting plasma insulin. Compared with the saline control, AG and AG+UAG both decreased AIRg, but UAG alone had no effect. SI did not differ among the treatments. AG, but not UAG, reduced DI and kg and increased plasma growth hormone. UAG did not alter growth hormone, cortisol, glucagon, or free fatty acid levels. UAG selectively decreased glucose and fructose consumption compared with the other treatments. In contrast to previous reports, acute administration of UAG does not have independent effects on glucose tolerance or β-cell function and neither augments nor antagonizes the effects of AG.

Neural centers in the hypothalamus regulate food intake and body weight in response to hormones and other neural stimuli, and dysfunctional communication between the brain and gut underlies metabolic disorders, including obesity. In this issue of the JCI, Steculorum and colleagues present evidence that the gastric peptide ghrelin mediates neural fiber growth in the arcuate nucleus of the hypothalamus during the neonatal period. Neonatal mice subjected to either increased or decreased ghrelin action during this developmental period had an increased risk of obesity in adulthood. Together, the results of this study support a model whereby neural organization at key stages of development sets the foundation for metabolic health later in life.

Purpose: Confirmatory factor analysis (CFA) was used to test the hypothesis whether adipocytokines are associated with the risk factor cluster that characterizes the metabolic syndrome (MetS). Methods: Data from 134 nondiabetic subjects were analyzed using CFA. Insulin sensitivity (SI) was quantified using intravenous glucose tolerance tests, visceral fat area by computed tomography and fasting high-density lipoprotein, triglycerides, monocyte chemoattractant protein-1 (MCP-1), serum amyloid A (SAA), tumor necrosis factor (TNF)-α, adiponectin, resistin, leptin, interleukin (IL)-6, C-reactive protein (CRP), and plasminogen activator inhibitor (PAI)-1 were measured. Results: The basic model representing the MetS included six indicators comprising obesity, SI, lipids, and hypertension, and demonstrated excellent goodness of fit. Using multivariate analysis, MCP-1, SAA, and TNF-α were not independently associated with any of the MetS variables. Adiponectin, resistin, leptin, CRP, and IL-6 were associated with at least one of the risk factors, but when added to the basic model decreased all goodness-of-fit parameters. PAI-1 was associated with all cardiometabolic factors and improved goodness-of-fit compared with the basic model. Conclusions: Addition of PAI-1 increased the CFA model goodness of fit compared with the basic model, suggesting that this protein may represent an added feature of the MetS.

Infusion of ghrelin to supraphysiologic levels inhibits glucose-stimulated insulin secretion, reduces insulin sensitivity, and worsens glucose tolerance in humans.The purpose of this study was to determine the effects of lower doses of ghrelin on insulin secretion and insulin sensitivity in healthy men and women.Acyl ghrelin (0.2 and 0.6 nmol kg(-1) h(-1)) or saline was infused for 225 minutes in 16 healthy subjects on 3 separate occasions in randomized order. An i.v. glucose tolerance test was performed, and the insulin sensitivity index (SI) was derived from the minimal model. Insulin secretion was measured as the acute insulin response to glucose (AIRg) and the disposition index was computed as AIRg × SI.Ghrelin infusions at 0.2 and 0.6 nmol kg(-1) h(-1) raised steady-state plasma total ghrelin levels 2.2- and 6.1-fold above fasting concentrations. Neither dose of ghrelin altered fasting plasma insulin, glucose, or SI, but both doses reduced insulin secretion compared with the saline control, computed either as AIRg (384 ± 75 and 354 ± 65 vs 520 ± 110 pM · min [mean ± SEM], respectively; P.01 for both low- and high-dose vs saline) or disposition index (2238 ± 421 and 2067 ± 396 vs 3339 ± 705, respectively; P.02 for both comparisons). The high-dose ghrelin infusion also decreased glucose tolerance.Ghrelin infused to levels occurring in physiologic states such as starvation decreases insulin secretion without affecting insulin sensitivity. These findings are consistent with a role for endogenous ghrelin in the regulation of insulin secretion and suggest that ghrelin antagonism could improve β-cell function.

Much recent evidence suggest that obesity and related comorbidities contribute to cognitive decline, including the development of non age-related dementia and Alzheimer's disease. Obesity is a serious threat to public health, and few treatments offer proven long-term weight loss. In fact, bariatric surgery remains the most effective long-term therapy to reduce weight and alleviate other aspects of the metabolic syndrome (MetS). Unlike the demonstrated benefits of caloric restriction to prevent weight gain, few if any studies have compared various means of weight loss on central nervous system function and hippocampal-dependent cognitive processes.Our studies comprise the first direct comparisons of caloric restriction to two bariatric surgeries (Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG)) on cognitive function. Weight loss following caloric restriction, RYGB and VSG was associated with generalized improvements in metabolic health and hippocampal-dependent learning, as measured in the radial arm maze and spontaneous alternation tests. However, VSG-treated rats exhibited deficits on spatial learning tasks in the Morris water maze. In addition, whereas VSG animals had elevated hippocampal inflammation, comparable to that of obese controls, RYGB and calorie-restricted (pair-fed, PF) controls exhibited an amelioration of inflammation, as measured by the microglial protein ionized calcium binding adaptor molecule 1 (IBA1). We also assessed whether GHR (ghrelin) replacement would attenuate hippocampal inflammation in VSG, as post-surgical GHR levels are significantly reduced in VSG relative to RYGB and PF rats. However, GHR treatment did not attenuate the hippocampal inflammation.Although VSG was comparably effective at reducing body weight and improving glucose regulation as RYGB, VSG did not appear to confer an equal benefit on cognitive function and markers of inflammation.

Adiponectin plays key roles in regulating appetite and food intake.To investigate interactions between the genetic risk score (GRS) for adiponectin levels and weight-loss diets varying in macronutrient intake on long-term changes in appetite and adiponectin levels.A GRS was calculated based on 5 adiponectin-associated variants in 692 overweight adults from the 2-year Preventing Overweight Using Novel Dietary Strategies trial.Repeated measurements of plasma adiponectin levels and appetite-related traits, including cravings, fullness, prospective consumption, and hunger.Dietary fat showed nominally significant interactions with the adiponectin GRS on changes in appetite score and prospective consumption from baseline to 6 months (P for interaction = 0.014 and 0.017, respectively) after adjusting for age, sex, ethnicity, baseline body mass index, and baseline respective outcome values. The GRS for lower adiponectin levels was associated with a greater decrease in appetite (P0.001) and prospective consumption (P = 0.008) among participants consuming a high-fat diet, whereas no significant associations were observed in the low-fat group. Additionally, a significant interaction was observed between the GRS and dietary fat on 6-month changes in adiponectin levels (P for interaction = 0.021). The lower GRS was associated with a greater increase in adiponectin in the low-fat group (P = 0.02), but it was not associated with adiponectin changes in the high-fat group (P = 0.31).Our findings suggest that individuals with varying genetic architecture of circulating adiponectin may respond divergently in appetite and adiponectin levels to weight-loss diets varying in fat intake.

Objectives: Administration of ghrelin inhibits the acute insulin response to glucose and worsens IV glucose tolerance in healthy subjects. Evidence from preclinical studies suggests that ghrelin may have differential effects on glucose metabolism during fasting and feeding. Our objective was to test the effects of ghrelin on glucose and insulin responses during a meal tolerance test. Design: Acyl ghrelin (0.26 and 2.0 μg/kg/h) or saline was infused in 13 healthy subjects on three separate occasions in randomized order. Ghrelin was infused for 45 minutes to achieve steady-state levels and continued for 240 minutes after ingestion of a liquid test meal. Primary outcomes were area under the curve for glucose and insulin secretion. Results: We found that ghrelin infusions of 0.26 and 2.0 μg/kg/h raised steady-state plasma total ghrelin levels to 1.7- and 4.8-fold above fasting concentrations, but did not alter fasting plasma glucose or insulin levels. During the meal tolerance test, ghrelin decreased insulin sensitivity, impaired β-cell function, and induced glucose intolerance. The high-dose ghrelin infusion also raised postprandial glucagon like peptide 1 secretion without affecting glucose dependent insulinotropic polypeptide, glucagon, or peptide YY concentrations. Conclusions: We conclude that both physiologic and pharmacologic doses of ghrelin worsen the glucose and β-cell responses to meal ingestion in healthy humans. The increase in postprandial glucagon like peptide 1 secretion by ghrelin suggests a novel enteroendocrine connection, but does not mitigate the glucose intolerance.

Controversies exist in the best surgical approach (open vs. laparoscopy) to large adrenal tumours without peri-operative evidence of primary carcinoma, mainly due to possible capsular disruption of an unsuspected malignancy. In addition, intra-operative blood loss, conversion rate, operative time, and hospital stay may be increased with laparoscopy. The aims of our study were: (1) to compare clinical outcomes of laparoscopic adrenalectomy for large versus small adrenal tumours and (2) to identify risk factors associated with increased operative time and hospital stay in laparoscopic adrenalectomy. This is a multicentre retrospective cohort study in a large patient population (N = 200) who underwent laparoscopic adrenalectomy in 2004–2014 at three Italian academic hospitals. Patients were divided into two cohorts according to tumour size: “large” tumours were defined as ≥5 cm (N = 50) and “small” tumours as

The 20-kDa human GH (hGH) is produced in the pituitary by alternative splicing of the hGH-N gene. The 20-kDa hGH promotes growth similarly to 22-kDa or total hGH, the predominant form in circulation, but the relative effects of these isoforms on glucose metabolism have been debated.To investigate the effect of ghrelin on 20-kDa and total hGH secretion in healthy, nonobese subjects. We also studied associations between basal GH concentration and fasting glucose and insulin as well as between dynamic GH secretion and insulin sensitivity.Synthetic human acyl ghrelin (0.2 or 0.6 nmol/kg · h) or saline was infused in random order in 14 healthy subjects (six males, eight females; age 27.7 ± 6.3 yr; body mass index 22.0 ± 2.7 kg/m(2), mean ± SEM) on 3 separate days. Ghrelin was infused for 45 min to achieve steady-state levels and continued through a 3-h frequently sampled i.v. glucose tolerance test. Insulin sensitivity index was quantified using the minimal model of glucose kinetics.Basal 20-kDa and total GH concentrations were 0.4 ± 0.1 and 2.2 ± 0.4 ng/ml, respectively, with a 20-kDa to total GH ratio of 0.13 ± 0.02. Females had significantly higher baseline GH levels. Ghrelin administration increased 20-kDa and total GH levels in a parallel and dose-dependent fashion, with no significant change in the ratio of the isoforms. Basal 20-kDa and total GH levels were negatively correlated with fasting glucose, insulin, and homeostasis model assessment of insulin resistance. During the frequently sampled iv glucose tolerance test, GH secretion was positively correlated with insulin sensitivity index with saline infusion.Ghrelin dose-dependently increases endogenous 20-kDa and total GH secretion in a parallel fashion in healthy subjects. Both basal and stimulated levels of the different GH isoforms were positively associated with insulin sensitivity in this cohort of healthy men and women.

Ghrelin increases food intake and decreases energy expenditure, promoting a positive energy balance. We observed a single case of serious hypothermia during sustained ghrelin treatment in a male subject, suggesting that ghrelin may play a role in the regulation of body temperature. We therefore investigated the effect of ghrelin treatment on body temperature in rodents and humans under controlled conditions. Intriguingly, we could demonstrate ghrelin binding in axon terminals of the medial preoptic area of the hypothalamus located in the vicinity of cold-sensitive neurons. This localization of ghrelin receptors provides a potential anatomical basis for the regulation of body temperature by ghrelin. However, our follow-up studies also indicated that neither a chronic i.c.v. application of ghrelin in rats, nor a single s.c. injection under cold exposure in mice resulted in a relevant decrease in body core temperature. In addition, a four-hour intravenous ghrelin infusion did not decrease body surface temperature in healthy humans. We concluded that while there is a theoretical molecular basis for ghrelin to modify body temperature in mammals, its magnitude is irrelevant under physiologic circumstances. Hypothermia is not likely to represent a serious risk associated with this agent and pathway.

Incretin hormones are intestinally derived peptides that are known to augment glucose-stimulated insulin secretion and suppress glucagon levels. Incretin mimetics are attractive adjunctive therapy for type 2 diabetes due to its efficacy on reducing hyperglycemia with a minimal risk of hypoglycemia. In contrast to most available hypoglycemia agents that cause weight gain, incretin mimetics are associated with moderate weight loss. In this review, we focused our discussion on the actions of glucagon-like peptide 1 (GLP-1) in the brain regulation of energy expenditure and food intake. Furthermore, we reviewed the data from preclinical and clinical studies in humans and discussed the actions of GLP-1, GLP-1 analogs, dipeptidyl pepidase 4 (DPP-4) inhibitors on body weight regulation as well as mechanism by which these effects may occur. The gastrointestinal side effects common to GLP-1 based therapeutics such as nausea hamper its wide spread use. Here, we discussed theoretical possibilities for maximizing weight loss and minimizing nausea with of incretin-based therapy.

Ghrelin, an orexigenic hormone secreted from the stomach, exists in the circulation in two isoforms: des-acyl and acyl ghrelin. Acylation by the enzyme ghrelin O-acyl-transferase (GOAT) enables ghrelin to activate the ghrelin receptor. This review discusses recent findings illustrating the role of acyl ghrelin, des-acyl ghrelin and GOAT in regulating glucose homeostasis.Recent publications support a role of ghrelin in modulating glucose homeostasis. Novel cellular mechanisms have been proposed to explain these effects. Controversy on this topic continues to exist owing to inconsistent observations made in both rodents and humans. Many recent studies are uncovering a role of des-acyl ghrelin in glucose metabolism specifically in modulating insulin sensitivity and glucose uptake into adipocytes. A novel role of ghrelin acylation by the enzyme GOAT in regulating glucose metabolism during caloric deprivation has newly been discovered.Ghrelin plays a role in regulating glucose homeostasis through the modulation of insulin secretion and insulin sensitivity. Acyl ghrelin and des-acyl ghrelin appear to have opposing glucoregulatory effects and regulation of acylation by the enzyme GOAT appears to play a role in mediating glucose metabolism. Modulation of GOAT or ghrelin signaling may be a clinically relevant strategy to treat metabolic diseases such as type II diabetes.