Weight-loss maintenance is accompanied by interconnected alterations in circulating FGF21-adiponectin-leptin and bioactive sphingolipids.

Weight loss is often followed by weight regain. Characterizing endocrine alterations accompanying weight reduction and regain may disentangle the complex biology of weight-loss maintenance. Here, we profile energy-balance-regulating metabokines and sphingolipids in adults with obesity undergoing an initial low-calorie diet-induced weight loss and a subsequent weight-loss maintenance phase with exercise, glucagon-like peptide-1 (GLP-1) analog therapy, both combined, or placebo. We show that circulating growth differentiation factor 15 (GDF15) and C16:0-C18:0 ceramides transiently increase upon initial diet-induced weight loss. Conversely, circulating fibroblast growth factor 21 (FGF21) is downregulated following weight-loss maintenance with combined exercise and GLP-1 analog therapy, coinciding with increased adiponectin, decreased leptin, and overall decrements in ceramide and sphingosine-1-phosphate levels. Subgroup analyses reveal differential alterations in FGF21-adiponectin-leptin-sphingolipids between weight maintainers and regainers. Clinically, cardiometabolic health outcomes associate with selective metabokine-sphingolipid remodeling signatures. Collectively, our findings indicate distinct FGF21, GDF15, and ceramide responses to diverse phases of weight change and suggest that weight-loss maintenance involves alterations within the metabokine-sphingolipid axis.

Intraduodenal calcium enhances the effects of L-tryptophan to stimulate gut hormone secretion and suppress energy intake in healthy males: a randomized, cross-over, clinical trial.

BACKGROUND: In humans, intraduodenal infusion of L-tryptophan (Trp) increases plasma concentrations of gastrointestinal hormones and stimulates pyloric pressures, both key determinants of gastric emptying and associated with potent suppression of energy intake. The stimulation of gastrointestinal hormones by Trp has been shown, in preclinical studies, to be enhanced by extracellular calcium and mediated in part by the calcium-sensing receptor. OBJECTIVE: To determine whether intraduodenal calcium can enhance the effects of Trp to stimulate gastrointestinal hormones and pyloric pressures, and if so, whether it is associated with greater suppression of energy intake, in healthy males. METHODS: Fifteen males with normal weight (mean±SD; age: 26±7 years; body mass index: 22±2 kg/m2), received on three separate occasions, 150-min intraduodenal infusions of 0, 500 or 1000 mg calcium (Ca), each combined with Trp (load: 0.1 kcal/min, with submaximal energy intake-suppressant effects) from t=75-150 min, in a randomized, double-blind, cross-over study. Plasma concentrations of GI hormones (gastrin, cholecystokinin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY)), and Trp, and antropyloroduodenal pressures were measured throughout. Immediately post-infusions (t=150-180 min), energy intake at a standardized buffet-style meal was quantified. RESULTS: In response to calcium alone, both 500-mg and 1000-mg doses stimulated PYY, while only the 1000-mg dose stimulated GLP-1 and pyloric pressures (all P<0.05). The 1000-mg dose also enhanced the effects of Trp to stimulate cholecystokinin and GLP-1, and both doses stimulated PYY, but, surprisingly, reduced the stimulation of GIP (all P<0.05). Both doses substantially and dose-dependently enhanced the effects of Trp to suppress energy intake (kcal; Ca-0+Trp: 1108±70, Ca-500+Trp: 961±90, Ca-1000+Trp: 922±96; P<0.05). CONCLUSIONS: Intraduodenal administration of calcium enhances the effect of Trp to stimulate plasma cholecystokinin, GLP-1 and PYY, and suppress energy intake, in health. These findings have potential implications for novel nutrient-based approaches to energy intake regulation in obesity. CLINICAL TRIAL REGISTRY: The trial was registered with the Australian New Zealand Clinical Trial Registry (www.anzctr.org.au; trial number: ACTRN12620001294943).

Altered desensitization and internalization patterns of rodent versus human glucose-dependent insulinotropic polypeptide (GIP) receptors. An important drug discovery challenge.

BACKGROUND AND PURPOSE: The gut hormone glucose-dependent insulinotropic polypeptide (GIP) signals via the GIP receptor (GIPR), resulting in postprandial potentiation of glucose-stimulated insulin secretion. The translation of results from rodent studies to human studies has been challenged by the unexpected effects of GIPR-targeting compounds. We, therefore, investigated the variation between species, focusing on GIPR desensitization and the role of the receptor C-terminus. EXPERIMENTAL APPROACH: The GIPR from humans, mice, rats, pigs, dogs and cats was studied in vitro for cognate ligand affinity, G protein activation (cAMP accumulation), recruitment of beta-arrestin and internalization. Variants of the mouse, rat and human GIPRs with swapped C-terminal tails were studied in parallel. KEY RESULTS: The human GIPR is more prone to internalization than rodent GIPRs. Despite similar agonist affinities and potencies for Gαs activation, especially, the mouse GIPR shows reduced receptor desensitization, internalization and beta-arrestin recruitment. Using an enzyme-stabilized, long-acting GIP analogue, the species differences were even more pronounced. 'Tail-swapped' human, rat and mouse GIPRs were all fully functional in their Gαs coupling, and the mouse GIPR regained internalization and beta-arrestin 2 recruitment properties with the human tail. The human GIPR lost the ability to recruit beta-arrestin 2 when its own C-terminus was replaced by the rat or mouse tail. CONCLUSIONS AND IMPLICATIONS: Desensitization of the human GIPR is dependent on the C-terminal tail. The species-dependent functionality of the C-terminal tail and the different species-dependent internalization patterns, especially between human and mouse GIPRs, are important factors influencing the preclinical evaluation of GIPR-targeting therapeutic compounds.

Bone remodeling in survivors of pediatric hematopoietic stem cell transplantation: Impact of heavy resistance training.

BACKGROUND: Early-onset osteoporosis is a frequent late effect after pediatric hematopoietic stem cell transplantation (HSCT). It remains unknown if physical training can improve bone formation in these patients, as the transplantation procedure may cause sustained dysregulation of the bone-forming osteoblast progenitor cells. OBJECTIVE: We aimed to explore the effect of resistance training on bone remodeling in long-term survivors of pediatric HSCT. PROCEDURE: In this prospective, controlled intervention study, we included seven HSCT survivors and 15 age- and sex-matched healthy controls. The participants completed a 12-week heavy load, lower extremity resistance training intervention with three weekly sessions. We measured fasting serum levels of the bone formation marker "N-terminal propeptide of type I procollagen" (P1NP), and the bone resorption marker "C-terminal telopeptide of type I collagen" (CTX). The hypothesis was planned before data collection began. The trial was registered at Clinicaltrials.gov before including the first participant, with trial registration no. NCT04922970. RESULTS: Resistance training led to significantly increased levels of fasting P1NP in both patients (from 57.62 to 114.99 ng/mL, p = .03) and controls (from 66.02 to 104.62 ng/mL, p < .001). No significant changes in fasting CTX levels were observed. CONCLUSIONS: Despite previous high-dose cytotoxic therapy, long-term survivors of pediatric HSCT respond to resistance training with improvement of bone formation, comparable to that of healthy controls. This suggests that resistance training might be a promising non-pharmacological approach to prevent the early decline in bone mass, and should be considered as part of a follow-up program to counteract long-term sequela after pediatric HSCT.

Glucagon resistance in individuals with obesity and hepatic steatosis can be measured using the GLUSENTIC test and index.

Increased plasma levels of glucagon (hyperglucagonaemia) promote diabetes development but is also observed in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). This may reflect hepatic glucagon resistance towards amino acid catabolism. A clinical test for measuring glucagon resistance has not been validated. We evaluated our glucagon sensitivity (GLUSENTIC) test, consisting of two study days: a glucagon injection and measurements of plasma amino acids, and an infusion of mixed amino acids and subsequent calculation of the GLUSENTIC index (primary outcome measure) from measurements of glucagon and amino acids. To distinguish glucagon-dependent from insulin-dependent actions on amino acid metabolism, we also studied patients with type 1 diabetes (T1D). The delta-decline in total amino acids was 49% lower in MASLD following exogenous glucagon (p=0.01), and the calculated GLUSENTIC index was 34% lower in MASLD (p<0.0001), but not T1D (p>0.99). In contrast, glucagon-induced glucose increments were similar in controls and MASLD (p=0.41). The GLUSENTIC test and index may be used to measure glucagon resistance in individuals with obesity and MASLD.

Bone Health After Exercise Alone, GLP-1 Receptor Agonist Treatment, or Combination Treatment: A Secondary Analysis of a Randomized Clinical Trial.

Importance: A major concern with weight loss is concomitant bone loss. Exercise and glucagon-like peptide-1 receptor agonists (GLP-1RAs) represent weight loss strategies that may protect bone mass despite weight loss. Objective: To investigate bone health at clinically relevant sites (hip, spine, and forearm) after diet-induced weight loss followed by a 1-year intervention with exercise, liraglutide, or both combined. Design, Setting, and Participants: This study was a predefined secondary analysis of a randomized clinical trial conducted between August 2016 and November 2019 at the University of Copenhagen and Hvidovre Hospital in Denmark. Eligible participants included adults aged 18 to 65 years with obesity (body mass index of 32-43) and without diabetes. Data analysis was conducted from March to April 2023, with additional analysis in February 2024 during revision. Interventions: After an 8-week low-calorie diet (800 kcal/day), participants were randomized to 1 of 4 groups for 52 weeks: a moderate- to vigorous-intensity exercise program (exercise alone), 3.0 mg daily of the GLP-1 RA liraglutide (liraglutide alone), the combination, or placebo. Main Outcomes and Measures: The primary outcome was change in site-specific bone mineral density (BMD) at the hip, lumbar spine, and distal forearm from before the low-calorie diet to the end of treatment, measured by dual-energy x-ray absorptiometry in the intention-to-treat population. Results: In total, 195 participants (mean [SD] age, 42.84 [11.87] years; 124 female [64%] and 71 male [36%]; mean [SD] BMI, 37.00 [2.92]) were randomized, with 48 participants in the exercise group, 49 participants in the liraglutide group, 49 participants in the combination group, and 49 participants in the placebo group. The total estimated mean change in weight losses during the study was 7.03 kg (95% CI, 4.25-9.80 kg) in the placebo group, 11.19 kg (95% CI, 8.40-13.99 kg) in the exercise group, 13.74 kg (95% CI, 11.04-16.44 kg) in the liraglutide group, and 16.88 kg (95% CI, 14.23-19.54 kg) in the combination group. In the combination group, BMD was unchanged compared with the placebo group at the hip (mean change, -0.006 g/cm2; 95% CI, -0.017 to 0.004 g/cm2; P = .24) and lumbar spine (-0.010 g/cm2; 95% CI, -0.025 to 0.005 g/cm2; P = .20). Compared with the exercise group, BMD decreased for the liraglutide group at the hip (mean change, -0.013 g/cm2; 95% CI, -0.024 to -0.001 g/cm2; P = .03) and spine (mean change, -0.016 g/cm2; 95% CI, -0.032 to -0.001 g/cm2; P = .04). Conclusions and Relevance: In this randomized clinical trial, the combination of exercise and GLP-1RA (liraglutide) was the most effective weight loss strategy while preserving bone health. Liraglutide treatment alone reduced BMD at clinically relevant sites more than exercise alone despite similar weight loss. Trial Registration: EudraCT: 2015-005585-32.

GLP-1 increases heart rate by a direct action on the sinus node.

AIMS: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are increasingly used to treat type 2 diabetes and obesity. Albeit cardiovascular outcomes generally improve, treatment with GLP-1 RAs is associated with increased heart rate, the mechanism of which is unclear. METHODS AND RESULTS: We employed a large animal model, the female landrace pig, and used multiple in-vivo and ex-vivo approaches including pharmacological challenges, electrophysiology and high-resolution mass spectrometry to explore how GLP-1 elicits an increase in heart rate. In anaesthetized pigs, neither cervical vagotomy, adrenergic blockers (alpha, beta or combined alpha-beta blockade), ganglionic blockade (hexamethonium) nor inhibition of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels (ivabradine) abolished the marked chronotropic effect of GLP-1. GLP-1 administration to isolated perfused pig hearts also increased heart rate, which was abolished by GLP-1 receptor blockade. Electrophysiological characterization of GLP-1 effects in vivo and in isolated perfused hearts localized electrical modulation to the atria and conduction system. In isolated sinus nodes, GLP-1 administration shortened action potential cycle length of pacemaker cells and shifted the site of earliest activation. The effect was independent of HCN blockade. Collectively, these data support a direct effect of GLP-1 on GLP-1 receptors within the heart. Consistently, single nucleus RNA sequencing (snRNAseq) showed GLP-1 receptor expression in porcine pacemaker cells. Quantitative phosphoproteomics analyses of sinus node samples revealed that GLP-1 administration leads to phosphorylation changes of calcium cycling proteins of the sarcoplasmic reticulum, known to regulate heart rate. CONCLUSION: GLP-1 has direct chronotropic effects on the heart mediated by GLP-1 receptors in pacemaker cells of the sinus node, inducing changes in action potential morphology and the leading pacemaker site through a calcium signaling response characterized by PKA-dependent phosphorylation of Ca2+ cycling proteins involved in pace making. Targeting the pacemaker calcium clock may be a strategy to lower heart rate in GLP-1 RA recipients.

Glycodeoxycholic acid inhibits primary bile acid synthesis with minor effects on glucose- and lipid homeostasis in humans.

BACKGROUND: Bile acids play vital roles in control of lipid-, glucose-, and energy metabolism by activating Takeda G protein-coupled receptor 5 (TGR5) and Farnesoid X receptor (FXR), the latter promoting production of the endocrine-acting fibroblast growth factor 19 (FGF19). Short-term administration of single bile acids has been reported to enhance plasma levels of GLP-1 and to enhance energy expenditure. However, prolonged bile acid supplementation, e.g. of chenodeoxycholic acid (CDCA) for gallstone dissolution, has been reported to have adverse effects. STUDY DESIGN: In this proof-of-concept study, we assessed the safety and metabolic effects of oral glycine-conjugated deoxycholic acid (GDCA) administration at 10 mg/kg/day using regular and slow-release capsules (mimicking physiological bile acid release) over 30 days in two groups of each 10 healthy lean men respectively. MAIN FINDINGS: GDCA increased postprandial total bile acid and FGF19 concentrations while suppressing those of the primary bile acids CDCA and cholic acid. Plasma levels of 7α-hydroxy-4-cholesten-3-one were reduced, indicating repressed hepatic bile acid synthesis. There were minimal effects on indices of lipid-, glucose-, and energy metabolism. No serious adverse events were reported during GDCA administration in either capsule types, although 50% of participants showed mild increases in plasma levels of liver transaminases and 80% (regular capsules) and 50% (slow-release capsules) of participants experienced gastrointestinal adverse events. CONCLUSION: GDCA administration leads to elevated FGF19 levels and effectively inhibits primary bile acid synthesis, supporting therapy compliance and its effectiveness. However, effects on lipid, glucose- and energy metabolism were minimal, indicating that expanding the pool of this relatively hydrophobic bile acid does not impact energy metabolism in healthy subjects.

Effect of the glucagon-like peptide-1 (GLP-1) receptor agonist semaglutide on alcohol consumption in alcohol-preferring male vervet monkeys.

RATIONALE: Glucagon-like peptide-1 (GLP-1) receptor agonists reduce alcohol consumption in rodents and non-human primates. Semaglutide is a new long-acting GLP-1 receptor agonist, widely used in the clinic against type 2 diabetes and obesity. It is also reported to reduce alcohol intake in rodents. OBJECTIVES: This study investigates the possible inhibitory effect of semaglutide on alcohol intake in alcohol-preferring African green monkeys. METHODS: We performed a vehicle-controlled study on male monkeys that had demonstrated a preference for alcohol. In the monkeys selected for voluntary alcohol drinking, alcohol consumption was measured for ten days at baseline (Monday to Friday for two weeks). During this period, the monkeys had access to alcohol 4 h per day and free access to water 24 h per day. After two weeks of baseline measurements, the monkeys were randomized to semaglutide or vehicle. Each group consisted of ten monkeys, and the two groups were balanced with respect to baseline alcohol intake. Following the baseline period, the monkeys were treated with escalating doses of semaglutide (up to 0.05 mg/kg) or vehicle subcutaneously twice weekly for two weeks during which period alcohol was not available. After uptitration, the monkeys had access to alcohol 4 h daily for 20 days (Monday to Friday for 4 weeks), and alcohol consumption was measured. During this alcohol exposure period, treatment with semaglutide (0.05 mg/kg twice weekly) or vehicle continued for three weeks followed by a one-week washout period. RESULTS: Compared to the vehicle, semaglutide significantly reduced alcohol intake. There were no signs of emetic events or changes in water intake. CONCLUSIONS: These data demonstrate for the first time the potent effect of semaglutide in reducing voluntary alcohol intake in non-human primates and further substantiate the need for clinical trials investigating the effect of semaglutide in patients with alcohol-use disorder.

Glucagon agonism in the treatment of metabolic diseases including type 2 diabetes mellitus and obesity.

Type 2 diabetes mellitus (T2DM) is associated with obesity and, therefore, it is important to target both overweight and hyperglycaemia. Glucagon plays important roles in glucose, amino acid and fat metabolism and may also regulate appetite and energy expenditure. These physiological properties are currently being exploited therapeutically in several compounds, most often in combination with glucagon-like peptide-1 (GLP-1) agonism in the form of dual agonists. With this combination, increases in hepatic glucose production and hyperglycaemia, which would be counterproductive, are largely avoided. In multiple randomized trials, the co-agonists have been demonstrated to lead to significant weight loss and, in participants with T2DM, even improved glycated haemoglobin (HbA1c) levels. In addition, significant reductions in hepatic fat content have been observed. Here, we review and discuss the studies so far available. Twenty-six randomized trials of seven different GLP-1 receptor (GLP-1R)/glucagon receptor (GCGR) co-agonists were identified and reviewed. GLP-1R/GCGR co-agonists generally provided significant weight loss, reductions in hepatic fat content, improved lipid profiles, insulin secretion and sensitivity, and in some cases, improved HbA1c levels. A higher incidence of adverse effects was present with GLP-1R/GCGR co-agonist treatment than with GLP-1 agonist monotherapy or placebo. Possible additional risks associated with glucagon agonism are also discussed. A delicate balance between GLP-1 and glucagon agonism seems to be of particular importance. Further studies exploring the optimal ratio of GLP-1 and glucagon receptor activation and dosage and titration regimens are needed to ensure a sufficient safety profile while providing clinical benefits.

L-valine is a powerful stimulator of GLP-1 secretion in rodents and stimulates secretion through ATP-sensitive potassium channels and voltage-gated calcium channels.

BACKGROUND: We previously reported that, among all the naturally occurring amino acids, L-valine is the most powerful luminal stimulator of glucagon-like peptide 1 (GLP-1) release from the upper part of the rat small intestine. This makes L-valine an interesting target for nutritional-based modulation of GLP-1 secretion. However, the molecular mechanism of L-valine-induced secretion remains unknown. METHODS: We aimed to investigate the effect of orally given L-valine in mice and to identify the molecular details of L-valine stimulated GLP-1 release using the isolated perfused rat small intestine and GLUTag cells. In addition, the effect of L-valine on hormone secretion from the distal intestine was investigated using a perfused rat colon. RESULTS: Orally given L-valine (1 g/kg) increased plasma levels of active GLP-1 comparably to orally given glucose (2 g/kg) in male mice, supporting that L-valine is a powerful stimulator of GLP-1 release in vivo (P > 0.05). Luminal L-valine (50 mM) strongly stimulated GLP-1 release from the perfused rat small intestine (P < 0.0001), and inhibition of voltage-gated Ca2+-channels with nifedipine (10 µM) inhibited the GLP-1 response (P < 0.01). Depletion of luminal Na+ did not affect L-valine-induced GLP-1 secretion (P > 0.05), suggesting that co-transport of L-valine and Na+ is not important for the depolarization necessary to activate the voltage-gated Ca2+-channels. Administration of the KATP-channel opener diazoxide (250 µM) completely blocked the L-valine induced GLP-1 response (P < 0.05), suggesting that L-valine induced depolarization arises from metabolism and opening of KATP-channels. Similar to the perfused rat small intestine, L-valine tended to stimulate peptide tyrosine-tyrosine (PYY) and GLP-1 release from the perfused rat colon. CONCLUSIONS: L-valine is a powerful stimulator of GLP-1 release in rodents. We propose that intracellular metabolism of L-valine leading to closure of KATP-channels and opening of voltage-gated Ca2+-channels are involved in L-valine induced GLP-1 secretion.

The impact of short-term eucaloric low- and high-carbohydrate diets on liver triacylglycerol content in males with overweight and obesity: a randomized crossover study.

BACKGROUND: Intrahepatic triacylglycerol (liver TG) content is associated with hepatic insulin resistance and dyslipidemia. Liver TG content can be modulated within days under hypocaloric conditions. OBJECTIVES: We hypothesized that 4 d of eucaloric low-carbohydrate/high-fat (LC) intake would decrease liver TG content, whereas a high-carbohydrate/low-fat (HC) intake would increase liver TG content, and further that alterations in liver TG would be linked to dynamic changes in hepatic glucose and lipid metabolism. METHODS: A randomized crossover trial in males with 4 d + 4 d of LC and HC, respectively, with ≥2 wk of washout. 1H-magnetic resonance spectroscopy (1H-MRS) was used to measure liver TG content, with metabolic testing before and after intake of an LC diet (11E% carbohydrate corresponding to 102 ± 12 {mean ± standard deviation [SD]) g/d, 70E% fat} and an HC diet (65E% carbohydrate corresponding to 537 ± 56 g/d, 16E% fat). Stable [6,6-2H2]-glucose and [1,1,2,3,3-D5]-glycerol tracer infusions combined with hyperinsulinemic-euglycemic clamps and indirect calorimetry were used to measure rates of hepatic glucose production and lipolysis, whole-body insulin sensitivity and substrate oxidation. RESULTS: Eleven normoglycemic males with overweight or obesity (BMI 31.6 ± 3.7 kg/m2) completed both diets. The LC diet reduced liver TG content by 35.3% (95% confidence interval: -46.6, -24.1) from 4.9% [2.4-11.0] (median interquartile range) to 2.9% [1.4-6.9], whereas there was no change after the HC diet. After the LC diet, fasting whole-body fat oxidation and plasma beta-hydroxybutyrate concentration increased, whereas markers of de novo lipogenesis (DNL) diminished. Fasting plasma TG and insulin concentrations were lowered and the hepatic insulin sensitivity index increased after LC. Peripheral glucose disposal was unchanged. CONCLUSIONS: Reduced carbohydrate and increased fat intake for 4 d induced a marked reduction in liver TG content and increased hepatic insulin sensitivity. Increased rates of fat oxidation and ketogenesis combined with lower rates of DNL are suggested to be responsible for lowering liver TG. This trial was registered at clinicaltrials.gov as NCT04581421.

Characterization of genetic variants of GIPR reveals a contribution of ß-arrestin to metabolic phenotypes.

Incretin-based therapies are highly successful in combatting obesity and type 2 diabetes1. Yet both activation and inhibition of the glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) in combination with glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) activation have resulted in similar clinical outcomes, as demonstrated by the GIPR-GLP-1R co-agonist tirzepatide2 and AMG-133 (ref. 3) combining GIPR antagonism with GLP-1R agonism. This underlines the importance of a better understanding of the GIP system. Here we show the necessity of ß-arrestin recruitment for GIPR function, by combining in vitro pharmacological characterization of 47 GIPR variants with burden testing of clinical phenotypes and in vivo studies. Burden testing of variants with distinct ligand-binding capacity, Gs activation (cyclic adenosine monophosphate production) and ß-arrestin 2 recruitment and internalization shows that unlike variants solely impaired in Gs signalling, variants impaired in both Gs and ß-arrestin 2 recruitment contribute to lower adiposity-related traits. Endosomal Gs-mediated signalling of the variants shows a ß-arrestin dependency and genetic ablation of ß-arrestin 2 impairs cyclic adenosine monophosphate production and decreases GIP efficacy on glucose control in male mice. This study highlights a crucial impact of ß-arrestins in regulating GIPR signalling and overall preservation of biological activity that may facilitate new developments in therapeutic targeting of the GIPR system.

Exogenous glucagon-like peptide 2 counteracts exogenous cholecystokinin-induced gallbladder contraction in healthy men.

BACKGROUND AND OBJECTIVE: Studies in humans and mice have demonstrated that the gut hormone glucagon-like peptide 2 (GLP-2) promotes gallbladder relaxation and refilling. Here, we assessed the effect of exogenous GLP-2 on gallbladder motility in the fasted state of healthy men with and without infusion of the potent gallbladder-contracting hormone cholecystokinin (CCK). METHODS: In a randomized, double-blind, placebo-controlled, crossover study, 15 male participants (mean [SD]: age 24.7 [3.6] years; body mass index 22.9 [1.6] kg/m2) underwent four experimental days receiving two infusions on each day: either CCK (0.4 pmol × kg-1 × min-1, time 0-180 min) + GLP-2 (10 pmol × kg-1 × min-1, time 30-240 min), CCK + placebo, placebo + GLP-2, or placebo + placebo, respectively. Gallbladder volume was measured at baseline and throughout the 4-hour study day using ultrasonography. RESULTS: Compared to placebo + placebo, GLP-2 + placebo did not affect gallbladder volume, but when infused in combination with CCK, GLP-2 completely abolished the strong gallbladder-contracting effect seen during CCK + placebo infusion, restoring baseline levels of gallbladder volume. CONCLUSION: Exogenous GLP-2 counteracts exogenous CCK-induced gallbladder emptying in healthy men, pointing to a possible therapeutic potential for GLP-2 as a relaxing modulator of gallbladder smooth muscle tone (e.g., as bridge to surgery in biliary colic). The effect may also explain the gallbladder-related adverse events reported for GLP-2 receptor agonists used in the treatment of short bowel syndrome.

Gluco-metabolic response to exogenous oxytocin in totally pancreatectomized patients and healthy individuals.

Oxytocin has been proposed to possess glucose-stabilizing effects through the release of insulin and glucagon from the pancreas. Also, exogenous oxytocin has been shown to stimulate extrapancreatic glucagon secretion in depancreatized dogs. Here, we investigated the effect of exogenous oxytocin on circulating levels of pancreatic and gut-derived glucose-stabilizing hormones (insulin [measured as C-peptide], glucagon, glucagon-like peptide 1 [GLP-1], and glucose-dependent insulinotropic polypeptide). We studied nine pancreatectomized (PX) patients and nine healthy controls (CTRLs) (matched on age and body mass index) before, during, and after an intravenous infusion of 10 IU of oxytocin administered over 12 min. Oxytocin did not increase plasma glucagon levels, nor induce any changes in plasma glucose, C-peptide, or GIP in any of the groups. Oxytocin decreased plasma glucagon levels by 19 ± 10 % in CTRLs (from 2.0 ± 0.5 [mean ± SEM] to 1.3 ± 0.2 pmol/l, P = 0.0025) and increased GLP-1 by 42 ± 22 % in PX patients (from 9.0 ± 1.0-12.7 ± 1.0 pmol/l, P = 0.0003). Fasting plasma glucose levels were higher in PX patients compared with CTRLs (13.1 ± 1.1 vs. 5.1 ± 0.1 mmol/l, P < 0.0001). In conclusion, the present findings do not support pancreas-mediated glucose-stabilizing effects of acute oxytocin administration in humans and warrant further investigation of oxytocin's gluco-metabolic effects.

Determinants of plasma levels of proglucagon and the metabolic impact of glucagon receptor signalling: a UK Biobank study.

AIMS/HYPOTHESES: Glucagon and glucagon-like peptide-1 (GLP-1) are derived from the same precursor; proglucagon, and dual agonists of their receptors are currently being explored for the treatment of obesity and metabolic dysfunction-associated steatotic liver disease (MASLD). Elevated levels of endogenous glucagon (hyperglucagonaemia) have been linked with hyperglycaemia in individuals with type 2 diabetes but are also observed in individuals with obesity and MASLD. GLP-1 levels have been reported to be largely unaffected or even reduced in similar conditions. We investigated potential determinants of plasma proglucagon and associations of glucagon receptor signalling with metabolic diseases based on data from the UK Biobank. METHODS: We used exome sequencing data from the UK Biobank for ~410,000 white participants to identify glucagon receptor variants and grouped them based on their known or predicted signalling. Data on plasma levels of proglucagon estimated using Olink technology were available for a subset of the cohort (~40,000). We determined associations of glucagon receptor variants and proglucagon with BMI, type 2 diabetes and liver fat (quantified by liver MRI) and performed survival analyses to investigate if elevated proglucagon predicts type 2 diabetes development. RESULTS: Obesity, MASLD and type 2 diabetes were associated with elevated plasma levels of proglucagon independently of each other. Baseline proglucagon levels were associated with the risk of type 2 diabetes development over a 14 year follow-up period (HR 1.13; 95% CI 1.09, 1.17; n=1562; p=1.3×10-12). This association was of the same magnitude across strata of BMI. Carriers of glucagon receptor variants with reduced cAMP signalling had elevated levels of proglucagon (ß 0.847; 95% CI 0.04, 1.66; n=17; p=0.04), and carriers of variants with a predicted frameshift mutation had higher levels of liver fat compared with the wild-type reference group (ß 0.504; 95% CI 0.03, 0.98; n=11; p=0.04). CONCLUSIONS/INTERPRETATION: Our findings support the suggestion that glucagon receptor signalling is involved in MASLD, that plasma levels of proglucagon are linked to the risk of type 2 diabetes development, and that proglucagon levels are influenced by genetic variation in the glucagon receptor, obesity, type 2 diabetes and MASLD. Determining the molecular signalling pathways downstream of glucagon receptor activation may guide the development of biased GLP-1/glucagon co-agonist with improved metabolic benefits. DATA AVAILABILITY: All coding is available through https://github.com/nicwin98/UK-Biobank-GCG.

Increased hepatic glucagon sensitivity in totally pancreatectomised patients.

OBJECTIVE: The metabolic phenotype of totally pancreatectomised patients includes hyperaminoacidaemia and predisposition to hypoglycaemia and hepatic lipid accumulation. We aimed to investigate whether the loss of pancreatic glucagon may be responsible for these changes. METHODS: Nine middle-aged, normal-weight totally pancreatectomised patients, nine patients with type 1 diabetes (C-peptide negative), and nine matched controls underwent two separate experimental days, each involving a 150-min intravenous infusion of glucagon (4 ng/kg/min) or placebo (saline) under fasting conditions while any basal insulin treatment was continued. RESULTS: Glucagon infusion increased plasma glucagon to similar high physiological levels in all groups. The infusion increased hepatic glucose production and decreased plasma concentration of most amino acids in all groups, with more pronounced effects in the totally pancreatectomised patients compared with the other groups. Glucagon infusion diminished fatty acid re-esterification and tended to decrease plasma concentrations of fatty acids in the totally pancreatectomised patients but not in the type 1 diabetes patients. CONCLUSION: Totally pancreatectomised patients were characterised by increased sensitivity to exogenous glucagon at the level of hepatic glucose, amino acid, and lipid metabolism, suggesting that the metabolic disturbances characterising these patients may be rooted in perturbed hepatic processes normally controlled by pancreatic glucagon.

Association between recent exposure to continuous glucose monitoring-recorded hypoglycaemia and counterregulatory and symptom responses to subsequent controlled hypoglycaemia in people with type 1 diabetes.

AIM: Experimental hypoglycaemia blunts the counterregulatory hormone and symptom responses to a subsequent episode of hypoglycaemia. In this study, we aimed to assess the associations between antecedent exposure and continuous glucose monitoring (CGM)-recorded hypoglycaemia during a 1-week period and the counterregulatory responses to subsequent experimental hypoglycaemia in people with type 1 diabetes. MATERIALS AND METHODS: Forty-two people with type 1 diabetes (20 females, mean ± SD glycated haemoglobin 7.8% ± 1.0%, diabetes duration median (interquartile range) 22.0 (10.5-34.9) years, 29 CGM users, and 19 with impaired awareness of hypoglycaemia) wore an open intermittently scanned CGM for 1 week to detect hypoglycaemic exposure before a standardized hyperinsulinaemic-hypoglycaemic [2.8 ± 0.1 mmol/L (50.2 ± 2.3 mg/dl)] glucose clamp. Symptom responses and counterregulatory hormones were measured during the clamp. The study is part of the HypoRESOLVE project. RESULTS: CGM-recorded hypoglycaemia in the week before the clamp was negatively associated with adrenaline response [ß -0.09, 95% CI (-0.16, -0.02) nmol/L, p = .014], after adjusting for CGM use, awareness of hypoglycaemia, glycated haemoglobin and total daily insulin dose. This was driven by level 2 hypoglycaemia [<3.0 mmol/L (54 mg/dl)] [ß -0.21, 95% CI (-0.41, -0.01) nmol/L, p = .034]. CGM-recorded hypoglycaemia was negatively associated with total, autonomic, and neuroglycopenic symptom responses, but these associations were lost after adjusting for potential confounders. CONCLUSIONS: Recent exposure to CGM-detected hypoglycaemia was independently associated with an attenuated adrenaline response to experimental hypoglycaemia in people with type 1 diabetes.

Impact of Synbiotic Intake on Liver Metabolism in Metabolically Healthy Participants and Its Potential Preventive Effect on Metabolic-Dysfunction-Associated Fatty Liver Disease (MAFLD): A Randomized, Placebo-Controlled, Double-Blinded Clinical Trial.

Synbiotics modulate the gut microbiome and contribute to the prevention of liver diseases such as metabolic-dysfunction-associated fatty liver disease (MAFLD). This study aimed to evaluate the effect of a randomized, placebo-controlled, double-blinded seven-week intervention trial on the liver metabolism in 117 metabolically healthy male participants. Anthropometric data, blood parameters, and stool samples were analyzed using linear mixed models. After seven weeks of intervention, there was a significant reduction in alanine aminotransferase (ALT) in the synbiotic group compared to the placebo group (-14.92%, CI: -26.60--3.23%, p = 0.013). A stratified analysis according to body fat percentage revealed a significant decrease in ALT (-20.70%, CI: -40.88--0.53%, p = 0.045) in participants with an elevated body fat percentage. Further, a significant change in microbiome composition (1.16, CI: 0.06-2.25, p = 0.039) in this group was found, while the microbial composition remained stable upon intervention in the group with physiological body fat. The 7-week synbiotic intervention reduced ALT levels, especially in participants with an elevated body fat percentage, possibly due to modulation of the gut microbiome. Synbiotic intake may be helpful in delaying the progression of MAFLD and could be used in addition to the recommended lifestyle modification therapy.

Effects of 3 months of 10-h per-day time-restricted eating and 3 months of follow-up on bodyweight and cardiometabolic health in Danish individuals at high risk of type 2 diabetes: the RESET single-centre, parallel, superiority, open-label, randomised controlled trial.

BACKGROUND: Time-restricted eating (TRE) has been suggested to be a simple, feasible, and effective dietary strategy for individuals with overweight or obesity. We aimed to investigate the effects of 3 months of 10-h per-day TRE and 3 months of follow-up on bodyweight and cardiometabolic risk factors in individuals at high risk of type 2 diabetes. METHODS: This was a single-centre, parallel, superiority, open-label randomised controlled clinical trial conducted at Steno Diabetes Center Copenhagen (Denmark). The inclusion criteria were age 30-70 years with either overweight (ie, BMI ≥25 kg/m2) and concomitant prediabetes (ie, glycated haemoglobin [HbA1c] 39-47 mmol/mol) or obesity (ie, BMI ≥30 kg/m2) with or without prediabetes and a habitual self-reported eating window (eating and drinking [except for water]) of 12 h per day or more every day and of 14 h per day or more at least 1 day per week. Individuals were randomly assigned 1:1 to 3 months of habitual living (hereafter referred to as the control group) or TRE, which was a self-selected 10-h per-day eating window placed between 0600 h and 2000 h. Randomisation was done in blocks varying in size and was open for participants and research staff, but outcome assessors were masked during statistical analyses. The randomisation list was generated by an external statistician. The primary outcome was change in bodyweight, assessed after 3 months (12 weeks) of the intervention and after 3 months (13 weeks) of follow-up. Adverse events were reported and registered at study visits or if participants contacted study staff to report events between visits. This trial is registered on ClinicalTrials.gov (NCT03854656). FINDINGS: Between March 12, 2019, and March 2, 2022, 100 participants (66 [66%] were female and 34 [34%] were male; median age 59 years [IQR 52-65]) were enrolled and randomly assigned (50 to each group). Of those 100, 46 (92%) in the TRE group and 46 (92%) in the control group completed the intervention period. After 3 months of the intervention, there was no difference in bodyweight between the TRE group and the control group (-0·8 kg, 95% CI -1·7 to 0·2; p=0·099). Being in the TRE group was not associated with a lower bodyweight compared with the control group after subsequent 3-month follow-up (-0·2 kg, -1·6 to 1·2). In the per-protocol analysis, participants who completed the intervention in the TRE group lost 1·0 kg (-1·9 to -0·0; p=0·040) bodyweight compared with the control group after 3 months of intervention, which was not maintained after the 3-month follow-up period (-0·4 kg, -1·8 to 1·0). During the trial and follow-up period, one participant in the TRE group reported a severe adverse event: development of a subcutaneous nodule and pain when the arm was in use. This side-effect was evaluated to be related to the trial procedures. INTERPRETATION: 3 months of 10-h per-day TRE did not lead to clinically relevant effects on bodyweight in middle-aged to older individuals at high risk of type 2 diabetes. FUNDING: Novo Nordisk Foundation, Aalborg University, Helsefonden, and Innovation Fund Denmark.