Fasting oxyntomodulin, glicentin, and gastric inhibitory polypeptide levels are associated with activation of reward- and attention-related brain centres in response to visual food cues in adults with obesity: A cross-sectional functional MRI study

Response to lowering plasma glucose is characterised by decreased oxyntomodulin: Results from a randomised controlled trial

BACKGROUND

With the prevalence of diabetes reaching an epidemic level, there is a growing interest in the investigation of its remission. Proglucagon-derived peptides (PGDP) have been shown to have a glucose-regulating effect. However, whether they play a role in diabetes remission remains poorly understood.

AIM

To investigate changes in plasma levels of PGDP in glycaemic responders versus non-responders.

METHODS

The study was a randomised placebo-controlled trial comprising 18 adults with prediabetes (registered at www.

CLINICALTRIALS

gov as NCT03889210). Following an overnight fast, participants consumed ketone β-hydroxybutyrate (KEβHB)-supplemented beverage and placebo beverage in crossover manner. Serial blood samples were collected from baseline to 150 min at 30-min intervals. The endpoints were changes in glucagon-like peptide-1 (GLP-1), glicentin, oxyntomodulin, glucagon, and major proglucagon fragment (MPGF). Participants were stratified into the 'responders' and 'non-responders' subgroups based on their glycaemic changes following the ingestion of KEβHB. The area under the curve (AUC) was calculated to estimate the accumulated changes in the studied PGDP and compared using paired-t test between the KEβHB and placebo beverages.

RESULTS

Responders had a significantly greater reduction in plasma glucose compared with non-responders following acute ketosis (p < 0.001). The AUC0-150 for oxyntomodulin was significantly lower following the KEβHB beverage compared with the placebo (p = 0.045) in responders, but not in non-responders (p = 0.512). No significant differences in AUCs0-150 were found for GLP-1, glicentin, glucagon, and MPGF in either responders or non-responders.

CONCLUSION

Oxyntomodulin is involved in lowering plasma glucose and may play an important role in diabetes remission.

Psychotropic Drug-Related Weight Gain and Its Treatment

Psychotropic drug-related weight gain (PDWG) is a common occurrence and is highly associated with non-initiation, discontinuation, and dissatisfaction with psychiatric drugs. Moreover, PDWG intersects with the elevated risk for obesity and associated morbidity that has been amply reported in the psychiatric population. Evidence indicates that differential liability for PDWG exists for antipsychotics, antidepressants, and anticonvulsants. During the past two decades, agents within these classes have become available with significantly lower or no liability for PDWG and as such should be prioritized. Although lithium is associated with weight gain, the overall extent of weight gain is significantly lower than previously estimated. The benefit of lifestyle and behavioral modification for obesity and/or PDWG in psychiatric populations is established, with effectiveness similar to that in the general population. Metformin is the most studied pharmacological treatment in the prevention and treatment of PDWG, and promising data are emerging for glucagon-like peptide-1 (GLP-1) receptor agonists (e.g., liraglutide, exenatide, semaglutide). Most pharmacologic antidotes for PDWG are supported with low-confidence data (e.g., topiramate, histamine-2 receptor antagonists). Future vistas for pharmacologic treatment for PDWG include large, adequately controlled studies with GLP-1 receptor agonists and possibly GLP-1/glucose-dependent insulinotropic polypeptide co-agonists (e.g., tirzepatide) as well as specific dietary modifications.

How gut hormones shape reward: A systematic review of the role of ghrelin and GLP-1 in human fMRI

The gastrointestinal hormones ghrelin and glucagon-like peptide-1 (GLP-1) have opposite secretion patterns, as well as opposite effects on metabolism and food intake. Beyond their role in energy homeostasis, gastrointestinal hormones have also been suggested to modulate the reward system. However, the potential of ghrelin and GLP-1 to modulate reward responses in humans has not been systematically reviewed before. To evaluate the convergence of published results, we first conduct a multi-level kernel density meta-analysis of studies reporting a positive association of ghrelin (N_comb = 353, 18 contrasts) and a negative association of GLP-1 (N_comb = 258, 12 contrasts) and reward responses measured using task functional magnetic resonance imaging (fMRI). Second, we complement the meta-analysis using a systematic literature review, focusing on distinct reward phases and applications in clinical populations that may account for variability across studies. In line with preclinical research, we find that ghrelin increases reward responses across studies in key nodes of the motivational circuit, such as the nucleus accumbens, pallidum, putamen, substantia nigra, ventral tegmental area, and the dorsal mid insula. In contrast, for GLP-1, we did not find sufficient convergence in support of reduced reward responses. Instead, our systematic review identifies potential differences of GLP-1 on anticipatory versus consummatory reward responses. Based on a systematic synthesis of available findings, we conclude that there is considerable support for the neuromodulatory potential of gut-based circulating peptides on reward responses. To unlock their potential for clinical applications, it may be useful for future studies to move beyond anticipated rewards to cover other reward facets.

Circulating levels of gastrointestinal hormones in prediabetes reversing to normoglycemia or progressing to diabetes in a year-A cross-sectional and prospective analysis

AIMS

We aimed to compare the concentrations of GLP-1, glucagon and GIP (established regulators of glucose homeostasis) and glicentin (emerging new metabolic marker)during an OGTT in patients with normal glucose tolerance (NGT), prediabetes and diabetes at onset, and one-year before, when all had prediabetes.

METHODS

GLP-1, glucagon, GIP and glicentin concentrations were measured and compared with markers of body composition, insulin sensitivity and β-cell function at a 5-timepoint OGTT in 125 subjects (30 diabetes, 65 prediabetes, 30 NGT) and in 106 of them one-year before, when all had prediabetes.

RESULTS

At baseline, when all subjects were in prediabetic state, hormonal levels did not differ between groups. One year later, patients progressing to diabetes had lower postprandial increases of glicentin and GLP-1, lower postprandial decrease of glucagon, and higher levels of fasting GIP compared to patients regressing to NGT. Changes in glicentin and GLP-1 AUC within this year correlated negatively with changes in Glucose AUC of OGTT and with changes in markers of beta cell function.

CONCLUSION

Incretins, glucagon and glicentin profiles in prediabetic state cannot predict future glycemic traits, but prediabetes progressing to diabetes is accompanied by deterioration of postprandial increases of GLP-1 and glicentin.

Factors Affecting the Circulating Levels of Oxyntomodulin in Health and After Acute Pancreatitis

OBJECTIVES

To investigate the factors associated with the circulating levels of oxyntomodulin in healthy individuals and individuals after an episode of acute pancreatitis (AP).

METHODS

Blood samples were collected from all participants after an overnight fast and analyzed for 28 biomarkers. Participants also underwent comprehensive body composition analysis on a 3-T magnetic resonance imaging scanner. Regression analyses were done to investigate the associations between oxyntomodulin and the studied factors.

RESULTS

The study included 105 individuals who had a primary diagnosis of AP and 58 healthy individuals. Peptide YY (B coefficient, 0.094; 95% confidence interval [95% CI], 0.164-0.123), pancreatic polypeptide (0.048; 95% CI, 0.030-0.066), and leptin (0.394; 95% CI, 0.128-0.661) had significant associations with oxyntomodulin in healthy individuals. Peptide YY was the most prominent factor associated with oxyntomodulin, explaining 60% of its variance in health. Cholecystokinin (0.014; 95% CI, 0.010-0.018), amylin (-0.107; 95% CI, -0.192 to -0.021), and glycated hemoglobin (-0.761; 95% CI, -1.249 to -0.273) had significant associations with oxyntomodulin in individuals after AP. Cholecystokinin was the most prominent factor associated with oxyntomodulin, explaining 44% of its variance after AP.

CONCLUSIONS

Factors affecting the circulating levels of oxyntomodulin are different in health and after AP. These insights will enable the determination of populations that benefit from oxyntomodulin therapeutics in the future.

Methods paper: Performance characteristics of novel assays for circulating levels of proglucagon-derived peptides and validation in a placebo controlled cross-over randomized clinical trial

BACKGROUND

The measurement of proglucagon-derived peptides (PGDPs) is a challenging task mainly due to major overlaps in their molecular sequence in addition to their low circulating levels. Here, we present the technical characteristics of novel ELISA assays measuring C-peptide and all six PGDPs including, for the first time, major proglucagon fragment (MPGF), and we validate them by performing a pilot in vivo cross-over randomized clinical trial on whether coffee consumption may affect levels of circulating PGDPs.

METHODS

The performance and technical characteristics of novel ELISA assays from Ansh measuring GLP-1, GLP-2, oxyntomodulin, glicentin, glucagon, MPGF and C-peptide were first evaluated in vitro in procured samples from a commercial vendor as well as in deidentified human samples from three previously performed clinical studies. Their performance was further evaluated in vivo in the context of a cross-over randomized controlled trial, in which 33 subjects consumed in random order and together with a standardized meal, 200 ml of either (a) instant coffee with 3 mg/kg caffeine, or (b) instant coffee with 6 mg/kg caffeine, (c) or water.

RESULTS

All assays demonstrated high accuracy (spike and recovery and average linearity recovery ±15%), precision (inter-assay CV ≤ 6.4%), specificity (no significant cross-reactivities) and they were sensitive in low concentrations. Measurements of glicentin in archived random human samples using the Ansh assay correlated strongly with the glicentin measurements of Mercodia assay (r = 0.968) and of GLP-1 modestly with Millipore GLP-1 assay (r = 0.440). Oxyntomodulin, glicentin and glucagon concentrations were 2-5 fold higher in plasma compared to serum and serum concentrations correlated modestly (for oxyntomodulin and glicentin) or poorly (for glucagon) with the plasma concentrations. The evaluated assays detected a postprandial increase of gut-secreted PGDPs (GLP-1, GLP-2, oxyntomodulin and glicentin) and a postprandial decrease of pancreas-secreted PGDPs (glucagon, MPGF) in response to consuming coffee in comparison to consuming water with breakfast (enter here composition of breakfast). Only coffee consumption at the high dose alter levels of gut-secreted PGDPs and both at low and high dose to lower levels of pancreas-secreted PGDPs compared to water consumption during breakfast.

CONCLUSION

Accurate, precise and specific measurement of six PGDPs is possible with novel assays. A randomized controlled trial demonstrated in vivo utility of those assays and supports the notion that coffee may exert part of its beneficial effects on glucose homeostasis in the short term through the regulation of PGDPs.

Integrative Hedonic and Homeostatic Food Intake Regulation by the Central Nervous System: Insights from Neuroimaging

Food intake regulation in humans is a complex process controlled by the dynamic interaction of homeostatic and hedonic systems. Homeostatic regulation is controlled by appetitive signals from the gut, adipose tissue, and the vagus nerve, while conscious and unconscious reward processes orchestrate hedonic regulation. On the one hand, sight, smell, taste, and texture perception deliver potent food-related feedback to the central nervous system (CNS) and influence brain areas related to food reward. On the other hand, macronutrient composition stimulates the release of appetite signals from the gut, which are translated in the CNS into unconscious reward processes. This multi-level regulation process of food intake shapes and regulates human ingestive behavior. Identifying the interface between hormones, neurotransmitters, and brain areas is critical to advance our understanding of conditions like obesity and develop better therapeutical interventions. Neuroimaging studies allow us to take a glance into the central nervous system (CNS) while these processes take place. This review focuses on the available neuroimaging evidence to describe this interaction between the homeostatic and hedonic components in human food intake regulation.

Post-pancreatitis diabetes mellitus: investigational drugs in preclinical and clinical development and therapeutic implications

Introduction: Post-pancreatitis diabetes mellitus is one of the most common types of secondary diabetes. The pharmaceutical armamentarium in the field of diabetology can be broadened if the design of novel drugs is informed by pathogenetic insights from studies on post-pancreatitis diabetes mellitus.Areas covered: The article provides an overview of preclinical and clinical studies of compounds selectively antagonizing the gastric inhibitory peptide receptor, simultaneously stimulating both the glucagon-like peptide-1 and glucagon receptors, and activating ketogenesis.Expert opinion: The current pharmacotherapy for post-pancreatitis diabetes mellitus is relatively ineffective. This type of diabetes represents a unique platform for rigorous, efficient, and practical search for glucose-lowering therapeutic candidates. Various methods of gastric inhibitory peptide receptor (expressed in the pancreas) antagonism have undergone extensive preclinical testing in diabetes, with promising compounds being trialed in man. Molecular mimicry with oxyntomodulin ─ an extra-pancreatic hormone homologous with pancreatic hormone glucagon and involved in the regulation of exocrine pancreatic function ─ could be harnessed. The emerging findings of a salutary effect of ketosis mimetics in people with prediabetes set the stage for a novel approach to preventing diabetes.