Glucagon-like peptide 1 (GLP-1)

Old and new anti-obesity drugs

Obesity is a pandemic problem that correlates with a cluster of metabolic factors leading to poor cardiovascular outcomes, morbidity, and an increased risk of overall mortality. It is necessary to approach obesity with a comprehensive treatment plan, which may involve lifestyle modifications (diet, exercise, and behavioral therapy) and pharmacological interventions. This article provides an overview of the mechanisms of action, efficacy, and safety of available long-term anti-obesity drugs and introduces other potential agents under investigation.

Unlocking the multifaceted roles of GLP-1: Physiological functions and therapeutic potential

Glucagon (GCG) like peptide 1 (GLP-1) has emerged as a powerful player in regulating metabolism and a promising therapeutic target for various chronic diseases. This review delves into the physiological roles of GLP-1, exploring its impact on glucose homeostasis, insulin secretion, and satiety. We examine the compelling evidence supporting GLP-1 receptor agonists (GLP-1RAs) in managing type 2 diabetes (T2D), obesity, and other diseases. The intricate molecular mechanisms underlying GLP-1RAs are explored, including their interactions with pathways like extracellular signal-regulated kinase 1/2 (ERK1/2), activated protein kinase (AMPK), cyclic adenine monophosphate (cAMP), mitogen-activated protein kinase (MAPK), and protein kinase C (PKC). Expanding our understanding, the review investigates the potential role of GLP-1 in cancers. Also, microribonucleic acid (RNA) (miRNAs), critical regulators of gene expression, are introduced as potential modulators of GLP-1 signaling. We delve into the link between miRNAs and T2D obesity and explore specific miRNA examples influencing GLP-1R function. Finally, the review explores the rationale for seeking alternatives to GLP-1RAs and highlights natural products with promising GLP-1 modulatory effects.

Sex-specific signatures of GLP-1 and amylin on resting state brain activity and functional connectivity in awake rats

Gut-produced glucagon-like peptide-1 (GLP-1) and pancreas-made amylin robustly reduce food intake by directly or indirectly affecting brain activity. While for both peptides a direct action in the hindbrain and the hypothalamus is likely, few studies examined their impact on whole brain activity in rodents and did so evaluating male rodents under anesthesia. However, both sex and anesthesia may significantly alter the influence of feeding controlling molecules on brain activity. Therefore, we investigated the effect of GLP-1 and amylin on brain activity and functional connectivity (FC) in awake adult male and female rats using resting-state functional magnetic resonance imaging (rsfMRI). We further examined the relationship between the altered brain activity or connectivity and subsequent food intake in response to amylin or GLP-1. We observed sex divergent effects of amylin and GLP-1 on the brain activity and FC patterns. Most importantly correlation analysis between FC and feeding behavior revealed that different brain areas potentially drive reduced food intake in male and female rats. Our findings underscore the distributed and distinctly sex divergent neural network engaged by each of these anorexic peptides and suggest that different brain areas may be the primary drivers of the feeding outcome in male and female rats. Moreover, prominent activity and connectivity alterations observed in brain areas not typically associated with feeding behavior in both sexes may either indicate novel feeding centers or alternatively suggest the involvement of these substances in behaviors beyond feeding and metabolism. The latter question is of potential translational significance as analogues of both amylin and GLP-1 are clinically utilized.

GLP-1 receptor agonists, are we witnessing the emergence of a paradigm shift for neuro-cardio-metabolic disorders?

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have emerged as groundbreaking therapeutic agents in managing a spectrum of metabolic disorders, demonstrating remarkable efficacy across multiple organ systems and disease states. These compounds are not only well-established in the treatment of type 2 diabetes (T2D) and obesity-conditions for which they have received widespread approval-but also exhibit promising potential in addressing cardiovascular disease (CVD) and Metabolic dysfunction-associated steatotic liver disease (MASLD). Recent investigations have begun to illuminate the utility of GLP-1RAs in the management of type 1 diabetes (T1D), as well as neurodegenerative disorders such as Alzheimer's and Parkinson's disease and various behavioral disorders. A plethora of clinical trials have consistently validated the capacity of GLP-1RAs to improve glycemic control, promote weight loss, and mitigate cardiovascular risk factors in individuals with T2D and obesity. While their application in T1D remains limited due to safety concerns-particularly regarding the risks of hypoglycemia and hyperglycemic ketoacidosis-emerging data suggest that GLP-1RAs may offer hepatoprotective benefits, potentially reducing liver fat content and decelerating the progression of MASLD. The neuroprotective attributes of GLP-1 RAs have garnered significant interest, with research indicating their potential to alleviate cognitive decline associated with neurodegenerative diseases. Furthermore, preliminary findings highlight the role of GLP-1 RAs in addressing behavioral disorders, emphasizing their extensive therapeutic promise. This comprehensive review synthesizes the current evidence supporting the diverse therapeutic applications of GLP-1RAs, positioning them as "magic drug" therapies for metabolic and neurological disorders. As ongoing research continues to explore innovative applications and combinations of GLP-1RAs, the landscape of disease management in metabolic and neurological contexts is poised for transformative advancements. This review will also critically assess safety considerations and underscore the need for personalized treatment strategies to optimize patient outcomes in these complex and often comorbid conditions.

Specific loss of GIPR signaling in GABAergic neurons enhances GLP-1R agonist-induced body weight loss

OBJECTIVES

Dual incretin agonists are among the most effective pharmaceutical treatments for obesity and type 2 diabetes to date. Such therapeutics can target two receptors, such as the glucagon-like peptide-1 (GLP-1) receptor and the glucose-dependent insulinotropic polypeptide (GIP) receptor in the case of tirzepatide, to improve glycemia and reduce body weight. Regarding body weight effects, GIPR signaling is thought to involve at least two relevant mechanisms: the enhancement of food intake reduction and the attenuation of aversive effects caused by GLP-1R agonists. Although it is known that dual GLP-1R-GIPR agonism produces greater weight loss than GLP-1R agonism alone, the precise mechanism is unknown.

METHODS

To address this question, we used mice lacking GIPR in the whole body, GABAergic neurons, or glutamatergic neurons. These mice were given various combinations of GLP-1R and GIPR agonist drugs with subsequent food intake and conditioned taste aversion measurements.

RESULTS

A GIPR knockout in either the whole body or selectively in inhibitory GABAergic neurons protects against diet-induced obesity, whereas a knockout in excitatory glutamatergic neurons had a negligible effect. Furthermore, we found that GIPR in GABAergic neurons is essential for the enhanced weight loss efficacy of dual incretin agonism, yet, surprisingly, its removal enhances the effect of GLP-1R agonism alone. Finally, GIPR knockout in GABAergic neurons prevents the anti-aversive effects of GIPR agonism.

CONCLUSIONS

Our findings are consistent with GIPR research at large in that both enhancement and removal of GIPR signaling are metabolically beneficial. Notably, however, our findings suggest that future obesity therapies designed to modulate GIPR signaling, whether by agonism or antagonism, would be best targeted towards GABAergic neurons.

Role of GLP‑1 receptor agonists in sepsis and their therapeutic potential in sepsis‑induced muscle atrophy (Review)

Sepsis‑induced myopathy (SIM) is a common complication in intensive care units, which is often associated with adverse outcomes, primarily manifested as skeletal muscle weakness and atrophy. Currently, the management of SIM focuses on prevention strategies, as effective therapeutic options remain elusive. Glucagon‑like peptide‑1 (GLP‑1) receptor agonists (GLP‑1RAs) have garnered attention as hypoglycemic and weight‑loss agents, with an increasing body of research focusing on the extrapancreatic effects of GLP‑1. In preclinical settings, GLP‑1RAs exert protective effects against sepsis‑related multiple organ dysfunction through anti‑inflammatory and antioxidant mechanisms. Based on the existing research, we hypothesized that GLP‑1RAs may serve potential protective roles in the repair and regeneration of skeletal muscle affected by sepsis. The present review aimed to explore the relationship between GLP‑1RAs and sepsis, as well as their impact on muscle atrophy‑related myopathy. Furthermore, the potential mechanisms and therapeutic benefits of GLP‑1RAs are discussed in the context of muscle atrophy induced by sepsis.

Biased agonism in peptide-GPCRs: A structural perspective

G protein-coupled receptors (GPCRs) are dynamic membrane receptors that transduce extracellular signals to the cell interior by forming a ligand-receptor-effector (ternary) complex that functions via allosterism. Peptides constitute an important class of ligands that interact with their cognate GPCRs (peptide-GPCRs) to form the ternary complex. "Biased agonism", a therapeutically relevant phenomenon exhibited by GPCRs owing to their allosteric nature, has also been observed in peptide-GPCRs, leading to the development of selective therapeutics with fewer side effects. In this review, we have focused on the structural basis of signalling bias at peptide-GPCRs of classes A and B, and reviewed the therapeutic relevance of bias at peptide-GPCRs, with the hope of contributing to the discovery of novel biased peptide drugs.

Metabolic syndrome in patients with schizophrenia: Underlying mechanisms and therapeutic approaches (Review)

Schizophrenia (SCZ) represents a considerable health concern, not only due to its impact on cognitive and psychiatric domains, but also because of its association with metabolic abnormalities. Individuals with SCZ face an increased risk of developing metabolic syndrome (MS), which contributes to the increased cardiovascular burden and reduced life expectancy observed in this population. Metabolic alterations are associated with both the SCZ condition itself and extrinsic factors, particularly the use of antipsychotic medications. Additionally, the link between SCZ and MS seems to be guided by distinct genetic parameters. The present narrative review summarizes the relationship between SCZ and MS and emphasizes the various therapeutic approaches for managing its components in patients with these conditions. Recommended therapeutic approaches include lifestyle modifications as the primary strategy, with a focus on behavioral lifestyle programs, addressing dietary patterns and physical activity. Pharmacological interventions include administering common antidiabetic medications and the selection of less metabolically harmful antipsychotics. Alternative interventions with limited clinical application are also discussed. Ultimately, a personalized therapeutic approach encompassing both the psychological and metabolic aspects is essential for the effective management of MS in patients with SCZ.

GLP-1 as a regulator of sepsis outcomes: Insights into cellular metabolism, inflammation, and therapeutic potential

Glucagon-like peptide-1 (GLP-1) has been widely studied in the context of treating obesity and various forms of metabolic disease. Sepsis is a life-threatening medical emergency characterized by the widespread dysregulation of energy metabolism within cells. The potential for GLP-1 to improve sepsis patient outcomes through improvements in energy metabolism and inflammation has been a focus of growing research interest, with many studies of GLP-1 itself and related compounds, including GLP-1 receptor agonists (GLP-1RAs), and dipeptidyl peptidase-4 (DPP-4) inhibitors, having explored the impact on sepsis in cells and organs. Such studies require that attention be paid to both the physiological and potential pathological effects of GLP-1 in sepsis. In many reports, researchers have demonstrated that endogenous GLP-1, GLP-1RAs, or DPP-4 inhibitors (a GLP-1 depressant) can modulate glucose homeostasis, inflammatory activity, immune function, and organ dysfunction in studies of sepsis model systems in vitro and in vivo. To date, GLP-1-based treatments have yet to be specifically used to manage sepsis, but its pleiotropic effects suggest its significant potential in sepsis treatment. This review provides an overview of the relationship between GLP-1 and its related compounds with sepsis, aiming to offer novel perspectives for the diagnosis and treatment of this condition. It highlights that GLP-1 may serve as a new biomarker for assessing the severity and prognosis of sepsis, and potentially contribute to improving clinical outcomes in septic patients. Meanwhile, GLP-1 may function as a messenger of metabolic reprogramming, shifting cellular energy production from oxidative phosphorylation to glycolysis, thereby modulating immune responses and influencing inflammatory reactions to enhance the clearance of pathogens. However, GLP-1 may act as a double-edged sword, the enhanced inflammatory response can potentially induce cytotoxic and organ-damaging effects while exerting beneficial actions.

Metabolic improvement effects of jejunoileal side-to-side anastomosis in patients with type 2 diabetes and the glucagon-like peptide-1 mechanism

Wang et al explored the metabolic improvement effects of jejunoileal side-to-side anastomosis in patients with type 2 diabetes mellitus (T2DM), focusing on its multitarget metabolic regulatory potential through enhanced secretion of glucagon-like peptide-1. This surgical procedure alters the direction of nutrient flow, activates distal ileal L cells, and increases endogenous glucagon-like peptide-1 levels, supporting glucose homeostasis, enhancing insulin sensitivity, regulating body weight, and improving cardiovascular health. This structural adjustment transforms the gastrointestinal tract into an active endocrine regulatory organ, providing a pathway for metabolic improvement in patients with T2DM and other complex metabolic disorders. Although this procedure demonstrates significant metabolic improvements within 3-6 months after surgery, integrating hormone level measurements, metabolic marker analysis, and long-term follow-up has become crucial for exploring the complex mechanisms of T2DM in the field of metabolic surgery and T2DM management. Multidisciplinary collaboration involving support from endocrinology, nutrition, and rehabilitation teams before and after surgery is becoming increasingly vital in the long-term management of patients with T2DM. This collaboration optimizes surgical outcomes and enhances metabolic management. Side-to-side anastomosis shows potential in the multitarget metabolic management of T2DM, providing an additional intervention option for patients with T2DM and metabolic disorders.

Dual and Triple Gut Peptide Agonists on the Horizon for the Treatment of Type 2 Diabetes and Obesity. An Overview of Preclinical and Clinical Data

PURPOSE OF REVIEW

The development of long-acting incretin receptor agonists represents a significant advance in the fight against the concurrent epidemics of type 2 diabetes mellitus (T2DM) and obesity. The aim of the present review is to examine the cellular processes underlying the actions of these new, highly significant classes of peptide receptor agonists. We further explore the potential actions of multi-agonist drugs as well as the mechanisms through which gut-brain communication can be used to achieve long-term weight loss without negative side effects.

RECENT FINDINGS

Several unimolecular dual-receptor agonists have shown promising clinical efficacy studies when used alone or in conjunction with approved glucose-lowering medications. We also describe the development of incretin-based pharmacotherapy, starting with exendin- 4 and ending with the identification of multi-incretin hormone receptor agonists, which appear to be the next major step in the fight against T2DM and obesity. We discuss the multi-agonists currently in clinical trials and how each new generation of these drugs improves their effectiveness. Since most glucose-dependent insulinotropic polypeptide (GIP) receptor: glucagon-like peptide- 1 receptor (GLP- 1) receptor: glucagon receptor triagonists compete in efficacy with bariatric surgery, the success of these agents in preclinical models and clinical trials suggests a bright future for multi-agonists in the treatment of metabolic diseases. To fully understand how these treatments affect body weight, further research is needed.

The promise of tirzepatide: A narrative review of metabolic benefits

Obesity and type 2 diabetes mellites (T2DM) are intertwined epidemics that continue to pose significant challenges to global public health. We aim to review the available evidence on the metabolic effects of tirzepatide, focusing on weight loss and maintenance of lost weight, body composition alterations, appetite regulation, glycemic control, and lipid profile modulation. Tirzepatide administration for 72 weeks elicited significant weight reduction ranging from 5 % to 20.9 % across different trials in a dose-dependent manner. Furthermore, limited evidence showed that lost body weight may be primarily due to fat mass reduction. Tirzepatide also significantly decreased food intake, reduced overall appetite scores and increased fasting visual analog scale scores for satiety and fullness across different clinical trials. Moreover, tirzepatide exhibited favorable effects on glycemic control, with notable reductions in HbA1c levels ranging from 20.4 mmol/mol with the 5 mg dose to 28.2 mmol/mol with the 15 mg dose, following treatment durations lasting 40-52 weeks. Additionally, tirzepatide exerts a beneficial impact on lipid profile parameters, including reductions in total cholesterol, low-density lipoprotein cholesterol, and triglyceride levels, while increasing high-density lipoprotein cholesterol concentrations. Despite its efficacy, tirzepatide is associated with gastrointestinal adverse effects, which requires dose escalation strategies to enhance tolerability. Mild to moderate adverse events are commonly reported at higher doses, with discontinuation rates ranging from 4 % to 10 % across different dosages. In conclusion, tirzepatide has shown multifaceted metabolic effects, along with manageable adverse profiles, which makes it a promising therapeutic agent for addressing both obesity and T2DM. However, further long-term randomized controlled trials are warranted to reveal long-term efficacy and safety outcomes, particularly in diverse patient populations.

Modulating the elasticity of milk exosome-based hybrid vesicles to optimize transepithelial transport and enhance oral peptide delivery

To address challenges such as limited loading capacity, restricted targeting precision, and low yield of natural exosomes as drug carriers, the fusion of liposomes and exosomes to create hybrid vesicles has emerged as a viable solution approach. While current research mainly focuses on designing functionalized liposomes, less attention is given to how liposome membrane materials affect the elasticity of these hybrids and their delivery efficiency. This study utilized milk exosomes (mExos) as model exosomes, and generated hybrid vesicles with varying elasticity through the fusion of phospholipids with differing chain lengths, examining the disparities among various hybrid vesicles in their ability to overcoming the gastrointestinal barriers. It was observed that while hard hybrid vesicles exhibited reduced mucus penetration compared to soft hybrid vesicles, they demonstrated a notably higher efficacy in traversing the epithelial cell barrier. The enhanced transepithelial cell capability of hard vesicles can be attributed to their reduced tendency to aggregate in the lysosome through the down-regulated clathrin-mediated endocytosis pathway, as well as by the strengthening of the endoplasmic reticulum-Golgi exocytosis pathway due to their rigid characteristics. In comparison to soft hybrid vesicles, semaglutide (SET) loaded hard hybrid vesicles demonstrated improved in vivo epithelial permeability, enhanced oral bioavailability, and better therapeutic effectiveness. This study could provide valuable insights for determining the optimal elasticity of exosome-liposome hybrid vesicles in the development of oral nanocarriers.

[Incretins as the basis of obesity treatment]

Obesity represents an immense challenge for patients and physicians due to its numerous comorbidities and complications. For a long time, safe and effective pharmacological treatment remained wishful thinking. Bariatric surgery was considered the only option for sustained weight loss; however, with the advent of incretin-based treatment, initially introduced as a highly effective component of anti-diabetic treatment, research began to focus on the complex gastroenteropancreatic endocrine system, including central hunger and satiety regulation. This shift was driven by the discovery of a remarkable side effect: placebo-controlled weight reduction. Subsequent groundbreaking pharmacological developments based on long-acting peptides, the administration of which could be reduced from twice daily in earlier forms of treatment to once weekly, now enables significant weight reduction of over 20%, with a tolerable safety profile. This article provides an illustrative overview of the corresponding associations and highlights this milestone in obesity treatment.

Incretin-based therapeutics for the treatment of neurodegenerative diseases

Neurodegenerative diseases (NDDs) represent a heterogeneous group of disorders characterized by progressive neuronal loss, which results in significant deficits in memory, cognition, motor skills, and sensory functions. As the prevalence of NDDs rises, there is an urgent unmet need for effective therapies. Current drug development approaches primarily target single pathological features of the disease, which could explain the limited efficacy observed in late-stage clinical trials. Originally developed for the treatment of obesity and diabetes, incretin-based therapies, particularly long-acting GLP-1 receptor (GLP-1R) agonists and GLP-1R-gastric inhibitory polypeptide receptor (GIPR) dual agonists, are emerging as promising treatments for NDDs. Despite limited conclusive preclinical evidence, their pleiotropic ability to reduce neuroinflammation, enhance neuronal energy metabolism and promote synaptic plasticity positions them as potential disease-modifying NDD interventions. In anticipation of results from larger clinical trials, continued advances in next-generation incretin mimetics offer the potential for improved brain access and enhanced neuroprotection, paving the way for incretin-based therapies as a future cornerstone in the management of NDDs.

Examining Weight Suppression, Leptin Levels, Glucagon-Like Peptide 1 Response, and Reward-Related Constructs in Severity and Maintenance of Bulimic Syndromes: Protocol and Sample Characteristics for a Cross-Sectional and Longitudinal Study

BACKGROUND

Bulimia nervosa and related syndromes (BN-S) characterized by binge eating vary considerably in illness severity and course. Using the Research Domain Criteria framework of the National Institute of Mental Health, we developed a model positing that the same set of physiological consequences of weight suppression (WS; defined as the difference between the highest and current adult body weight) contribute to binge-eating severity and maintenance by (1) increasing the drive or motivation to consume food (reward valuation effort [RVE]) and (2) decreasing the ability for food consumption to lead to a state of satiation or satisfaction (reward satiation).

OBJECTIVE

Our funded project aimed to test concurrent associations among WS, physiological factors (leptin concentrations and postprandial glucagon-like peptide 1 [GLP-1] response), behavioral indicators of RVE (breakpoint on progressive ratio tasks) and reward satiation (ad-lib test meal intake), self-report of these core constructs, and binge-eating severity in BN-S (aim 1); test prospective associations to determine whether WS predicts BN-S maintenance in longitudinal models and whether posited mediators also predict BN-S maintenance (aim 2); and determine whether associations between WS and BN-S severity and maintenance are mediated by alterations in leptin levels, GLP-1 response, RVE, and reward satiation (aim 3).

METHODS

We aimed to recruit a sample of 320 women with BN-S or noneating disorder controls, with BMI from 16 kg/m2 to 35 kg/m2, for our study. The study included diagnostic interviews; questionnaires; height, weight, and percentage of body fat measurements; weight history; fasting leptin level; postprandial GLP-1 and insulin responses to a fixed meal; and ad-lib meal and progressive ratio tasks to behaviorally measure reward satiation and RVE, respectively, at baseline, with at least 78.1% (250/320) of the participants providing data at 6- and 12-month follow-up visits. Data will be analyzed using structural equation models to test posited pathways.

RESULTS

Data collection began in November 2016 and ended in April 2023, pausing in-person data collection from March 2020 to February 2021 due to the COVID-19 pandemic. Of 399 eligible women enrolled, 290 (72.7%) provided clinical, behavioral, and biological data at baseline, and 249 (62.4%) provided follow-up data. Measures demonstrated strong psychometric properties.

CONCLUSIONS

We seek to identify biobehavioral predictors to inform treatments that target key factors influencing the severity and course of binge eating. These data, supported solely through federal funding, can inform questions emerging from recent interest and controversy surrounding the use of GLP-1 agonists for binge eating.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/66554.

Hidden in the Fat: Unpacking the Metabolic Tango Between Metabolic Dysfunction-Associated Steatotic Liver Disease and Metabolic Syndrome

Metabolic syndrome (MetS) and metabolic dysfunction-associated steatotic liver disease (MASLD) are closely related, with rapidly increasing prevalence globally, driving significant public health concerns. Both conditions share common pathophysiological mechanisms such as insulin resistance (IR), adipose tissue dysfunction, oxidative stress, and gut microbiota dysbiosis, which contribute to their co-occurrence and progression. While the clinical implications of this overlap, including increased cardiovascular, renal, and hepatic risk, are well recognized, current diagnostic and therapeutic approaches remain insufficient due to the clinical and individuals' heterogeneity and complexity of these diseases. This review aims to provide an in-depth exploration of the molecular mechanisms linking MetS and MASLD, identify critical gaps in our understanding, and highlight existing challenges in early detection and treatment. Despite advancements in biomarkers and therapeutic interventions, the need for a comprehensive, integrated approach remains. The review also discusses emerging therapies targeting specific pathways, the potential of precision medicine, and the growing role of artificial intelligence in enhancing research and clinical management. Future research is urgently needed to combine multi-omics data, precision medicine, and novel biomarkers to better understand the complex interactions between MetS and MASLD. Collaborative, multidisciplinary efforts are essential to develop more effective diagnostic tools and therapies to address these diseases on a global scale.

A double-blind, placebo-controlled trial of exenatide for the treatment of olanzapine-related weight gain in obese and overweight adults

OBJECTIVE

To assess the safety and efficacy of exenatide in overweight or obese patients treated with olanzapine.

METHODS

Adults with stable major mood or psychotic disorders were randomized to double-blind exenatide or placebo for 16 weeks. Weight and body mass index (BMI) were monitored throughout the study. A secondary objective was to evaluate the tolerability of exenatide and its effects on mood and psychotic symptoms.

RESULTS

A significant difference in weight change was detected between the treatment groups. Participants in the exenatide group experienced on average a minor weight loss, while participants in the placebo group on average experienced weight gain (-0.5 kg [-0.6 %] vs. +2.6 kg [+2.8 %], both p < .01). The most common side effects in the exenatide group were gastrointestinal symptoms and headaches. There were no clinically meaningful differences between the groups in changes to mood or psychotic symptoms.

CONCLUSIONS

Exenatide is effective and well-tolerated for attenuating olanzapine-associated weight gain.

CLINICAL TRIAL REGISTRATION INFORMATION

Exenatide for the Treatment of Weight Gain Associated with Olanzapine in Obese Adults. NCT00845507.

Molecular Pharmacology of Glucagon-Like Peptide 1-Based Therapies in the Management of Type Two Diabetes Mellitus and Obesity

Background

The global increase in type 2 diabetes mellitus (DM2) and obesity presents a significant public health challenge, as these interconnected conditions contribute to severe complications, including cardiovascular disease, stroke, and certain cancers. The incretin system, particularly glucagon-like peptide-1 (GLP-1), has emerged as a promising therapeutic target due to its role in glycemic control and weight management.

Objective

This review explores the molecular pharmacology of GLP-1 and its receptor agonists, evaluating their therapeutic efficacy in managing DM2 and obesity.

Methods

A comprehensive literature review was conducted, analyzing recent advancements in GLP-1-based therapies, their mechanisms of action, and their clinical applications. The review also highlights the pharmacokinetic modifications developed to enhance the stability and efficacy of GLP-1 receptor agonists.

Results

GLP-1 receptor agonists have demonstrated significant benefits in improving glycemic control, reducing body weight, and addressing metabolic complications. Novel therapeutic approaches, including dual and triple incretin receptor agonists, are showing enhanced efficacy in both diabetes and obesity management. However, challenges remain in optimizing treatment outcomes, addressing patient variability, and improving long-term adherence.

Conclusion

GLP-1-based therapies have revolutionized the management of DM2 and obesity. Continued research is essential to refine these treatments, overcome existing limitations, and develop personalized approaches to maximize patient outcomes.

Are Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists Central Nervous System (CNS) Penetrant: A Narrative Review

INTRODUCTION

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that modulates glucose metabolism and insulin secretion. Recent translational and clinical research has evaluated the effects of GLP-1 receptor agonists (GLP-1 RAs), a class of drugs that mimic the action of native GLP-1 in the central nervous system (CNS). In addition to the efficacy of GLP-1 for the treatment of diabetes mellitus and obesity, preliminary evidence indicates GLP-1s have neuroprotective, therapeutic, and disease modification effects for select neurodegenerative disorders (e.g. Parkinson's disease, Alzheimer's disease). Among the available GLP-1 RAs, relatively few have been shown to be CNS penetrant. This article synthesizes extant literature reporting on CNS penetrants of GLP-1 RAs as proxied by brain imaging studies. Where available, studies that reported on the bioavailability of GLP-1 RAs in the CNS were identified.

METHODS

A comprehensive search of PubMed, Ovid, and Web of Science from database inception to July 2024 was conducted. Inclusion criteria were English language publications with no date restrictions, preclinical and clinical studies with participants aged 18-80 and studies which focused on GLP-1 RAs including: "Semaglutide" or "Ozempic" or "Rybelsus" or "Wegovy" or "Dulaglutide" or "Trulicity" or "Exenatide" or "Byetta" or "Bydureon" or "Liraglutide" or "Lixisenatide" or "Tirzepatide" or "Mounjaro" or "Zepbound" or "Bydureon BCise" or "Adlyxin" or "Victoza" or "Saxenda".

RESULTS

We identified 14 studies that were included in this synthesis. Preclinical studies suggest that select GLP-1 RAs cross the blood-brain barrier (BBB) (i.e. liraglutide, semaglutide, and exenatide). Replicated evidence suggests that CNS penetration of GLP-1 RAs can be proxied by reported effects of GLP-1 RAs on brain connectivity in human participants.

CONCLUSION

 Preclinical studies indicate that select GLP-1 RAs are CNS penetrant; whether GLP-1 RAs reproducibly engage neural targets hypothesized to subserve dimensions of psychopathology (e.g., general cognitive functions) remains incompletely characterized.

A glucose-responsive alginate-based hydrogel laden with modified GLP-1 and telmisartan ameliorates type 2 diabetes and reduces liver and kidney toxicities

The pathophysiology associated with type 2 diabetes mellitus (T2DM) includes insulin resistance, increased oxidative stress, a pro-inflammatory macrophage population, and dysfunction of pancreatic β cells in the islets of Langerhans, along with hepato- and nephro-toxicity. In this study, an injectable glucose-responsive hydrogel (Diabogel) was developed using alginate and 3-aminophenyl boronic acid to deliver modified glucagon-like peptide-1, insulinoma cell-derived extracellular vesicles, and telmisartan. Diabogel demonstrated cytocompatibility, decreased reactive oxygen species, enhanced insulin synthesis, and improved glucose uptake in vitro. In a high-fat diet/streptozotocin-induced murine model of T2DM, Diabogel lowered blood glucose levels, maintained body weight, and increased insulin expression. Furthermore, it promoted an anti-inflammatory microenvironment in the pancreas by regulating macrophage phenotype and the expression of NF-κB, supported cellular proliferation, and restored the pancreatic islets. In addition, Diabogel treatment significantly lowered the serum levels of pro-inflammatory cytokines and enhanced anti-inflammatory cytokines. Interestingly, Diabogel treatment also lowered diabetes-associated hepato- and nephro-toxicity. Taken together, Diabogel may serve as a potential approach for the treatment of T2DM, regulating blood glucose levels, restoring pancreatic β cell function, and reducing hepatic and renal toxicities.

Obesity-associated Inflammation and Alloimmunity

Obesity is a worldwide health problem with a rapidly rising incidence. In organ transplantation, increasing numbers of patients with obesity accumulate on waiting lists and undergo surgery. Obesity is in general conceptualized as a chronic inflammatory disease, potentially impacting alloimmune response and graft function. Here, we summarize our current understanding of cellular and molecular mechanisms that control obesity-associated adipose tissue inflammation and provide insights into mechanisms affecting transplant outcomes, emphasizing on the beneficial effects of weight loss on alloimmune responses.

Antidiabetic constituents of Kaempferiae rhizoma: Previously undescribed O-linked diarylheptanoid dimers promoting GLP-1 secretion via PKA-CREB pathway

Glucagon-like peptide-1 (GLP-1) is a fascinating target for the treatment of diabetes to avoid hypoglycemia. Kaempferiae Rhizoma (KR), the dried rhizomes of Kaempferia galanga, is a famous pungent medicine used for activating Qi, warming interior, removing digestion and relieving pain in China. In order to characterize the antidiabetic effects of KR, 21 previously undescribed O-linked diarylheptanoid dimers, kaemgalangins A1-A4 (1-4), B1-B13 (5-17) and C1-C4 (18-21), were isolated from the ethyl acetate fraction. Their structures were determined by extensive spectroscopic analyses, quantum computation and chemical methods. All compounds were tested for their GLP-1 stimulating effects on NCI-H716 cells, most of which showed obvious activity representing a new type of antidiabetic constituents. Especially, compounds 1, 2 and 16 showed spectacular GLP-1 stimulation with promoting rates of 146.6 ± 31.1 %, 159.0 ± 16.6 % and 142.9 ± 2.7 %, more potent than the positive control. Mechanism study manifested that kaemgalangin A1 (1) promoted GLP-1 secretion through up-regulating the mRNA expression of Gcg and Pc1/3, and the phosphorylation of PKA and CREB, but independent on TGR5 and GPR119 receptors. Furthermore, network pharmacology analysis suggested that the GLP-1 secretion induced by 1 was closely related to MAPK and PI3K-Akt signaling pathways. This investigation first revealed that KR was rich in diarylheptanoid dimers with GLP-1 promoting effects, which provides scientific basis for the antidiabetic application of K. galanga.

Subgroup analysis by sex and baseline BMI in people with a BMI ≥27 kg/m2 in the phase 2 trial of survodutide, a glucagon/GLP-1 receptor dual agonist

AIM

To explore the effects of sex and baseline body mass index (BMI) on the efficacy and safety of survodutide in people with a BMI ≥27 kg/m2.

MATERIALS AND METHODS

Totally 387 people (aged 18-75 years, BMI ≥27 kg/m2, without diabetes) were randomized 1:1:1:1:1 to once-weekly subcutaneous survodutide (0.6, 2.4, 3.6 or 4.8 mg) or placebo for 46 weeks (20-week dose escalation; 26-week dose maintenance). Participants were categorized according to sex and baseline BMI. Data were analysed descriptively for the full analysis set (FAS), according to dose assigned at randomization (planned treatment) using on-treatment data or all data censored for COVID-19-related treatment discontinuations. (ClinicalTrials.gov number: NCT04667377).

RESULTS

After 46 weeks of survodutide treatment, females had greater reductions in bodyweight and waist circumference than males. Participants with a lower baseline BMI had greater proportional reductions in bodyweight than those with a higher baseline BMI; the trend was reversed for reductions in waist circumference. Rates of adverse events (AEs) were comparable between subgroups for sex and baseline BMI. Nausea was the most frequently reported gastrointestinal AE in all subgroups.

CONCLUSIONS

In people with a BMI ≥27 kg/m2, survodutide was associated with clinically meaningful reductions in bodyweight and waist circumference when compared with placebo, in prespecified subgroups based on sex and baseline BMI, and was tolerated at all doses tested.

Hypothalamus and brainstem circuits in the regulation of glucose homeostasis

The central nervous system (CNS) senses and integrates blood glucose status, regulating its levels through communication with peripheral organs. Since traditional wisdom holds that the hypothalamus primarily controls glucose homeostasis, the brainstem, although less studied, has been emerging as a key player in blood glucose metabolism. Although the brainstem is reciprocally wired with the hypothalamus, their interactions are crucial for glucose control. Here, we focus on classic discoveries and recent advancements of hypothalamic and brainstem nodes that regulate glucose homeostasis. Based on the current progress and development for central regulation of blood sugar, we propose that the circuitry and cellular mechanisms for how hypothalamus and brainstem coordinate in blood sugar regulation are crucial; hence, a deeper understanding of both nuclei could shed light on a future cure for diabetes.

Physiological Fatty Acid-Stimulated Insulin Secretion and Redox Signaling Versus Lipotoxicity

Significance: Type 2 diabetes as a world-wide epidemic is characterized by the insulin resistance concomitant to a gradual impairment of β-cell mass and function (prominently declining insulin secretion) with dysregulated fatty acids (FAs) and lipids, all involved in multiple pathological development. Recent Advances: Recently, redox signaling was recognized to be essential for insulin secretion stimulated with glucose (GSIS), branched-chain keto-acids, and FAs. FA-stimulated insulin secretion (FASIS) is a normal physiological event upon postprandial incoming chylomicrons. This contrasts with the frequent lipotoxicity observed in rodents. Critical Issues: Overfeeding causes FASIS to overlap with GSIS providing repeating hyperinsulinemia, initiates prediabetic states by lipotoxic effects and low-grade inflammation. In contrast the protective effects of lipid droplets in human β-cells counteract excessive lipids. Insulin by FASIS allows FATP1 recruitment into adipocyte plasma membranes when postprandial chylomicrons come late at already low glycemia. Future Directions: Impaired states of pancreatic β-cells and peripheral organs at prediabetes and type 2 diabetes should be revealed, including the inter-organ crosstalk by extracellular vesicles. Details of FA/lipid molecular physiology are yet to be uncovered, such as complex phenomena of FA uptake into cells, postabsorptive inactivity of G-protein-coupled receptor 40, carnitine carrier substrate specificity, the role of carnitine-O-acetyltransferase in β-cells, and lipid droplet interactions with mitochondria. Antioxid. Redox Signal. 42, 566-622.

Exendin-4 improves cerebral ischemia by relaxing microvessels, rapidly increasing cerebral blood flow after reperfusion

Intravenous thrombolysis remains the cornerstone for restoring cerebral reperfusion post-stroke. Despite recombinant tissue plasminogen activator (rtPA) achieving arterial reperfusion within 6 h, persistent microcirculatory blood flow reduction often hampers recovery. Exendin-4, a glucagon-like peptide-1 receptor agonist (GLP-1RA), has demonstrated potential for improving stroke outcomes, though its mechanisms remain partially unclear. This study investigated the role of Exendin-4 in restoring microcirculatory blood flow post-stroke. Using ischemic stroke models in 8-week-old male C57BL/6j mice, induced by transient middle cerebral artery occlusion or bilateral common carotid artery ligation, Exendin-4 (150 μg/kg) was administered intravenously. Infarct size and neurological deficits were evaluated using TTC staining and neurological severity scores. Real-time cerebral blood flow (CBF) and microvascular changes were measured with laser speckle imaging and two-photon microscopy. Mechanistic studies employed immunofluorescence and infrared differential interference contrast microscopy. Our findings demonstrated that Exendin-4 significantly reduced infarct size and improved neurological outcomes, independent of blood glucose levels. Immunofluorescence revealed GLP-1 receptor expression in arteriolar smooth muscle cells, endothelial cells, and pericytes. Exendin-4 enhanced microvascular blood flow via vasodilation, confirmed through real-time imaging. In vitro, Exendin-4 relaxed pre-constricted vessels, an effect that was abolished by eNOS and adenylate cyclase (AC) inhibitors. However, guanylate cyclase (GC) inhibition failed to block Exendin-4-induced vasodilation, suggesting a non-cGMP-dependent NO pathway may be involved. Furthermore, prostaglandin E2 (PGE2) signaling via EP4 receptors was identified as a critical contributor to Exendin-4's vasodilatory effect, highlighting the involvement of multiple signaling pathways. These findings suggest that Exendin-4 preserves cerebral microcirculation through a multifaceted mechanism involving GLP-1R-mediated AC-cAMP signaling, PGE2-EP4 signaling, and a non-cGMP-dependent NO pathway. This study positions GLP-1 receptor agonists as promising therapeutic candidates for enhancing cerebral microcirculation and improving outcomes following stroke.

Full-fat versus non-fat yogurt consumption improves glucose homeostasis and metabolic hormone regulation in individuals with prediabetes: A randomized-controlled trial

Dietary guidance recommends consuming low- or non-fat dairy foods for metabolic health, yet observational research indicates full-fat yogurt intake may not detrimentally affect type 2 diabetes risk. Randomized-controlled trials are needed to further explore this relationship. Our aim was to evaluate the effect of substituting full-fat (3.25%) yogurt for non-fat yogurt on type 2 diabetes risk in individuals with prediabetes. We hypothesized beneficial effects on measures of glucose homeostasis, insulin sensitivity, and metabolic hormone response following short-term consumption of 3 full-fat yogurt servings daily. Thirteen individuals completed the 8-week randomized, double-masked crossover controlled-feeding trial comprised 2, 3-week experimental diet periods in which participants consumed 3 daily servings of full-fat or non-fat yogurt; a 1-week control preceded each diet period. Following each diet period, changes in whole-body glucose handling and metabolic hormone concentrations were measured using mixed meal and oral glucose tolerance tests. Our primary outcome measure was the blood glucose concentration at the 120-minute time point during the oral glucose tolerance test. Though differences in the primary outcome measure were not observed, the full-fat yogurt diet resulted in lower concentrations of blood fructosamine, a marker of average blood glucose concentrations over 2 to 3 weeks. Further, fasting glucagon-like peptide-1 and post-prandial glucose-dependent insulinotropic polypeptide concentrations were greater following the full-fat yogurt diet. Our preliminary results indicate that short-term consumption of full-fat relative to non-fat yogurt beneficially affected aspects of glucose homeostasis and metabolic hormone regulation in individuals with prediabetes, warranting further randomized-controlled research. This trial is registered at clinicaltrials.gov (NCT03577119).

Targeting central pathway of Glucose-Dependent Insulinotropic Polypeptide, Glucagon and Glucagon-like Peptide-1 for metabolic regulation in obesity and type 2 diabetes

Obesity and type 2 diabetes are significant public health challenges that greatly impact global well-being. The development of effective therapeutic strategies has become more and more concentrated on the central nervous system and metabolic regulation. The primary pharmaceutical interventions for the treatment of obesity and uncontrolled hyperglycemia are now generally considered to be incretin-based anti-diabetic treatments, particularly glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide receptor agonists. This is a result of their substantial influence on the central nervous system and the consequent effects on energy balance and glucose regulation. It is increasingly crucial to understand the neural pathways of these pharmaceuticals. The purpose of this review is to compile and present the most recent central pathways regarding glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide and glucagon receptors, with a particular emphasis on central metabolic regulation.

Current Insights, Advantages and Challenges of Small Molecule Glucagon-like Peptide 1 Receptor Agonists: A Scoping Review

Type 2 diabetes mellitus (T2DM) is a prevalent chronic condition with significant morbidity and mortality, largely due to its vascular complications. The emergence of novel pharmacological agents, particularly glucagon-like peptide-1 receptor agonists (GLP-1RAs), has revolutionized T2DM management by addressing glycemic control and comorbidities such as cardiovascular and renal diseases. Traditionally, GLP-1RAs require subcutaneous injection, presenting challenges in patient adherence and limiting combination therapy options. Recent advancements have introduced orally available small-molecule GLP-1RAs, which retain the physiological benefits of peptide-based GLP-1RAs, such as promoting insulin secretion, reducing appetite, and improving weight loss. These small molecules offer enhanced tissue permeability, extended half-lives, and the potential for fixed-dose combinations, addressing limitations of injectable formulations. This review explores the preclinical and clinical progress of small-molecule GLP-1RAs, highlighting their potential to redefine diabetes care by improving convenience, adherence, and accessibility for patients.

Unexpected cardiovascular risks of glucagon-like peptide-1 receptor agonist and aspirin co-administration in individuals with obesity, with and without type 2 diabetes: A propensity score matched cohort study

AIMS

To examine the cardiovascular safety of combining glucagon-like peptide-1 receptor agonists (GLP-1 RAs) with aspirin in individuals with obesity, both with and without type 2 diabetes (T2D).

MATERIALS AND METHODS

This propensity score matched cohort study analysed data from 2 946 579 individuals with obesity, with and without T2D, using the TriNetX US and Global dataset. Participants were categorized into four matched groups: those receiving GLP-1 RA plus aspirin versus those receiving GLP-1 RA alone, for both diabetic and non-diabetic individuals. Cardiovascular outcomes and adverse events were evaluated over 5 years using Cox proportional hazards models.

RESULTS

Individuals with obesity treated with GLP-1 RAs plus aspirin showed significantly higher risks of various cardiovascular events compared to those on GLP-1 RAs alone. In non-diabetic obese individuals, the combination therapy increased risks of hypertensive heart diseases (HR 1.40, 95% CI 1.15-1.60), ischaemic heart disease (HR 2.39, 95% CI 1.92-2.97) and heart failure (HR 1.97, 95% CI 1.54-2.53). Similar patterns were observed in individuals with T2D. Atrial fibrillation and cardiac arrhythmias showed increasing hazard ratios over time. The combination therapy also led to more frequent adverse events, including gastrointestinal bleeding.

CONCLUSIONS

The combination of GLP-1 RAs with aspirin in individuals with obesity, both with and without T2D, was associated with increased cardiovascular risks compared to GLP-1 RA monotherapy. These findings suggest that there may be risks associated with the combined use of these treatments and highlight the need for further research into this possible complication with regard to treatment.

Abilities of Rare Sugar Members to Release Glucagon-like Peptide-1 and Suppress Food Intake in Mice

Background/Objectives: Rare sugars, which naturally exist in small quantities, have gained attention as next-generation functional sugars due to their sweetness and low calorie content. Some of them have already been commercialized. Rare sugar-containing syrups, produced through alkaline isomerization of high-fructose corn syrup, are effective in preventing obesity and type 2 diabetes. However, the mechanisms underlying these effects remain incompletely understood. Recently, D-allulose has been found to improve hyperphagic obesity by stimulating the secretion of the intestinal hormone glucagon-like peptide-1 (GLP-1). The present study aimed to determine the comparative effects of aldohexoses (D-glucose, D-allose) and ketohexoses (D-fructose, D-allulose, D-tagatose, D-sorbose) on GLP-1 secretion and food intake in male mice. Method and Results: Single peroral administration of four ketohexoses at 1 and 3 g/kg, but not aldohexoses at 1 and 3 g/kg, significantly increased plasma GLP-1 concentrations with comparable efficacy. Moreover, these ketohexoses at 1 g/kg suppressed food intake in the short term, an effect blunted by GLP-1 receptor antagonism. In contrast, zero-calorie D-allose at 3 g/kg suppressed feeding without raising plasma GLP-1 levels. Conclusions: These results demonstrate that D-allulose, D-tagatose, and D-sorbose, which are low-calorie rare sugars classified as ketohexoses, suppress food intake through promoting GLP-1 secretion, showing their potential to prevent and/or ameliorate type 2 diabetes, obesity and related diseases.

In the Era of Cardiovascular-Kidney-Metabolic Syndrome in Cardio-Oncology: From Pathogenesis to Prevention and Therapy

Cardiovascular-kidney-metabolic (CKM) syndrome represents a complex interplay between cardiovascular disease (CVD), chronic kidney disease (CKD), and metabolic disorders, significantly impacting cancer patients. The presence of CKM syndrome in cancer patients not only worsens their prognosis but also increases the risk of major adverse cardiovascular events (MACE), reduces quality of life (QoL), and affects overall survival (OS). Furthermore, several anticancer therapies, including anthracyclines, tyrosine kinase inhibitors, immune checkpoint inhibitors, and hormonal treatments, can exacerbate CKM syndrome by inducing cardiotoxicity, nephrotoxicity, and metabolic dysregulation. This review explores the pathophysiology of CKM syndrome in cancer patients and highlights emerging therapeutic strategies to mitigate its impact. We discuss the role of novel pharmacological interventions, including sodium-glucose cotransporter-2 inhibitors (SGLT2i), proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i), and soluble guanylate cyclase (sGC) activators, as well as dietary and lifestyle interventions. Optimizing the management of CKM syndrome in cancer patients is crucial to improving OS, enhancing QoL, and reducing MACE. By integrating cardiometabolic therapies into oncologic care, we can create a more comprehensive treatment approach that reduces the burden of cardiovascular and renal complications in this vulnerable population. Further research is needed to establish personalized strategies for CKM syndrome prevention and treatment in cancer patients.

Semaglutide improves cognitive function and neuroinflammation in APP/PS1 transgenic mice by activating AMPK and inhibiting TLR4/NF-κB pathway

BackgroundAlzheimer's disease (AD) causes cognitive function disorder and has become the preeminent cause of dementia. Glucagon-like peptide-1 (GLP-1) receptor agonists, semaglutide, have shown positive effects on promoting the cognitive function. However, research about the mechanism of semaglutide as a therapeutic intervention in AD is sparse.ObjectiveThis study was to investigate the therapeutic efficacy of semaglutide in a transgenic mouse model of AD pathology and explored the detailed mechanism by semaglutide modulated neuroinflammatory processes.MethodsMale amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice were treated with semaglutide or vehicle for 8 weeks. Morris water maze test was used to assess the therapeutic efficacy of semaglutide on recognition function. Pathology analysis was performed to detect the deposition of amyloid plaques. High-throughput sequencing analysis was applied to specify the mechanism. Microglia and astrocyte activation were assessed with immunofluorescent staining. Inflammation cytokine levels were evaluated with enzyme-linked immunosorbent assay (ELISA). Related proteins and pathway were evaluated with western blot.ResultsSemaglutide treatment attenuated Aβ accumulation and enhanced cognitive function in APP/PS1 transgenic mice. Through transcriptomic profiling, immunohistochemical staining, and ELISA, semaglutide was substantiated to inhibit the overactivation of microglia and astrocytes, as well as to curtail the secretion of inflammatory mediators. Furthermore, semaglutide robustly activated AMP-activated protein kinase (AMPK) and suppressed the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling cascade, thus reducing the Aβ deposition and dampening the inflammatory cascade.ConclusionsThe results demonstrated that semaglutide mitigated neuroinflammation and decelerated the advance of AD in APP/PS1 transgenic mice.

Variant screening of PYY3-36 leads to potent long-acting PYY analogs with superior Y2 receptor selectivity

Peptide YY (PYY3-36) has attracted attention in diabetes and obesity research because of its involvement in food intake regulation and glucose homeostasis. Native PYY3-36 maintains high potency on the Y2 receptor with a loss of potency on the Y1, Y4, and Y5 receptors. However, PYY3-36 has a relatively short half-life, and the selectivity displayed by the native peptide may not be optimal if a long-acting analog is to be developed. We performed variant screening of PYY3-36 to identify key canonical amino acids that are pivotal to Y2 receptor selectivity, potency, and peptide stability. In combination with fatty diacid derivatization, this afforded highly selective long-acting analogs against the Y2 receptor, which improved glucose metabolism in diabetic db/db mice. When combined with a long-acting glucagon-like peptide 1 (GLP-1) receptor agonist, these analogs showed superior blood glucose lowering in diabetic ZSF1 rats and greater body weight loss in a high-fat diet-induced mouse model of obesity compared with treatment with the GLP-1 analog alone. One of the tested analogs, PYY1875, has progressed into clinical trials for obesity. Together, our results demonstrate the power of variant screening combined with fatty diacid derivatization in the development of a long-acting, highly efficacious PYY clinical candidate.

Insights into GLP-1 and insulin secretion mechanisms in pasireotide-induced hyperglycemia highlight effectiveness of Gs-targeting diabetes treatment

Pasireotide frequently causes severe hyperglycemia; however, its detailed mechanism remains unknown. There are no published guidelines regarding the optimal management of pasireotide-induced hyperglycemia based on its pathophysiology. Herein, we successfully switched a patient with acromegaly from a dipeptidyl peptidase-4 (DPP-4) inhibitor to a glucagon-like peptide-1 (GLP-1) analog due to pasireotide-induced deterioration of glycemic control, and we examined the underlying mechanism for glycemic control. An in vitro study was conducted using pancreatic β-cell line, MIN-6, stably expressing GLP-1R (GLP-1R-MIN-6 cells) and intestinal L-cell line, GLUTag. High glucose levels and Gs-coupled receptor stimulation synergistically triggered insulin and GLP-1 secretion. Gs-coupled receptor stimulation primarily triggered GLP-1 secretion, which was amplified by high glucose levels in GLUTag cells. Pasireotide drastically inhibited GLP-1 secretion induced by Gs-coupled receptor stimulation through SSTR5-Gi-dependent inhibition of cAMP levels, suggesting that the main pathway was completely blocked. Furthermore, administering GLP-1 partially overcame the inhibitory effect of pasireotide in GLP-1R-MIN-6 cells, leading to a partial recovery of insulin secretion. The drastic inhibition of GLP-1 secretion via shutdown of the main pathway is the primary cause of pasireotide-induced hyperglycemia. GLP-1 analogs, rather than DPP-4 inhibitors, can spare pasireotide-induced depletion of endogenous GLP-1 and restore insulin secretion.

Impact of Glucagon-like Peptide-1 Receptor Agonists on Mental Illness: Evidence from a Mendelian Randomization Study

Emerging evidence suggests that glucagon-like peptide-1 receptor (GLP1R) agonists may have potential benefits for mental illnesses. However, their exact effects remain unclear. This study investigated the causal relationship between glucagon-like peptide-1 receptor agonist (GLP1RA) and the risk of 10 common mental illnesses, including attention deficit and hyperactivity disorder, anorexia nervosa, anxiety disorder, autism spectrum disorder, bipolar disorder, major depressive disorder, post-traumatic stress disorder, schizophrenia, cannabis use disorder, and alcohol use disorder. We selected GLP1RA as the exposure and conducted a Mendelian randomization (MR) analysis. The cis-eQTLs of the drug target gene GLP1R, provided by eQTLGen, were used to simulate the pharmacological effects of GLP1RA. Type 2 diabetes and BMI were included as positive controls. Using data from both the Psychiatric Genomic Consortium and FinnGen, we conducted separate MR analyses for the same disease across these two independent databases. Meta-analysis was used to pool the results. We found genetic evidence suggesting a causal relationship between GLP1RA and a reduced risk of schizophrenia [OR (95% CI) = 0.84 (0.71-0.98), I2 = 0.0%, common effects model]. Further mediation analysis indicated that this effect might be unrelated to improvements in glycemic control but rather mediated by BMI. However, the findings of this study provide insufficient evidence to support a causal relationship between GLP1RA and other mental illnesses. Sensitivity analyses did not reveal any potential bias due to horizontal pleiotropy or heterogeneity in the above results (p > 0.05). This study suggests that genetically proxied activation of glucagon-like peptide-1 receptor is associated with a lower risk of schizophrenia. GLP1R is implicated in schizophrenia pathogenesis, and its agonists may exert potential benefits through weight management. Our study provides useful information for understanding the neuropsychiatric effects of GLP1RA, which may contribute to refining future research designs and guiding clinical management. Moreover, our findings could have significant implications for overweight individuals at high risk of schizophrenia when selecting weight-loss medications. Future research should further investigate the potential mechanisms underlying the relationship between GLP1RA and schizophrenia.

Effect and mechanism of GLP-1 on cognitive function in diabetes mellitus

Background

Diabetes mellitus (DM) is a metabolic disorder associated with cognitive impairment. Glucagon-like peptide-1 (GLP-1) and its receptor (GLP-1R) have shown neuroprotective effects.

Scope of review

This review explores the impact of DM on cognitive function. Diabetes-related cognitive impairment is divided into three stages: diabetes-associated cognitive decrements, mild cognitive impairment (MCI), and dementia. GLP-1R agonists (GLP-1RAs) have many functions, such as neuroprotection, inhibiting infection, and metabolic regulation, and show good application prospects in improving cognitive function. The mechanisms of GLP-1RAs neuroprotection may be interconnected, warranting further investigation. Understanding these mechanisms could lead to targeted treatments for diabetes-related cognitive dysfunction.

Major conclusions

Therefore, this paper reviewed the regulatory effects of GLP-1 on cognitive dysfunction and its possible mechanism. Further research is required to fully explore the potential of GLP-1 and its analogs in this context.

The role of GIPR in food intake control

Glucose-dependent insulinotropic polypeptide (GIP) is one of two incretin hormones playing key roles in the control of food intake, nutrient assimilation, insulin secretion and whole-body metabolism. Recent pharmacological advances and clinical trials show that unimolecular co-agonists that target the receptors for the incretins - GIP and glucagon-like peptide 1 (GLP-1) - offer more effective treatment strategies for obesity and type 2 diabetes mellitus (T2D) compared with GLP-1 receptor (GLP1R) agonists alone, suggesting previously underappreciated roles of GIP in regulating food intake and body weight. The mechanisms by which GIP regulates energy balance remain controversial as both agonism and antagonism of the GIP receptor (GIPR) produce weight loss and improve metabolic outcomes in preclinical models. Recent studies have shown that GIPR signalling in the central nervous system (CNS), especially in regions of the brain that regulate energy balance, is essential for its action on appetite regulation. This finding has sparked interest in understanding the mechanisms by which GIP engages brain circuits to reduce food intake and body weight. In this review, we present key knowledge around the actions of GIP on food intake regulation and the potential mechanisms by which GIPR and GIPR/GLP1R agonists may regulate energy balance.

GLP-1 receptor agonists significantly impair taste function

Over 10% of the US population are prescribed glucagon-like peptide-1 receptor agonists (GLP-1 RAs) to combat obesity. Although they decrease cravings for foods, their influence on chemosensory function is unknown. We employed state-of-the-art quantitative taste and smell tests to address this issue. The 53-item Waterless Empirical Taste Test (WETT®) and the 40-item University of Pennsylvania Smell Identification Test (UPSIT®) were completed by 46 persons taking GLP-1 RAs and 46 controls matched on age, sex, smoking behavior, and COVID-19 infection histories. Data were analyzed using analyses of variance. The WETT® scores were significantly diminished in the GLP-1 RA group relative to controls [total means (95% CIs) = 28.61 (25.66,31.56) and 40.63 (38.35,42.91), p < 0.001, η2 = 0.37]. Eighty five percent of the GLP-1 subjects scored worse than their individually matched controls. All 5 WETT® subtest scores were similarly affected (ps < 0.001). Smell function, although slightly decreased on average, was not significantly impacted (p = 0.076). Women outperformed men on all tests. Remarkably, UPSIT® and WETT® scores were higher, i.e., better, in those reporting nausea, diarrhoea, and other GLP-1-related side effects. This study demonstrates, for the first time, that GLP-1 RAs alter the function of a major sensory system, significantly depressing the perception of all five basic taste qualities. The physiologic basis of this effect is unknown but may involve GLP-1 receptors in the brainstem and afferent taste pathways, as well as vagus nerve-related processes.

Investigating the impact of intestinal glucagon-like peptide-1 on hypoglycemia in type 1 diabetes

Recent advances in understanding type 1 diabetes (T1D) highlight the complexity of managing hypoglycemia, a frequent and perilous complication of diabetes therapy. This letter delves into a novel study by Jin et al, which elucidates the role of intestinal glucagon-like peptide-1 (GLP-1) in the counterregulatory response to hypoglycemia in T1D models. The study employed immunofluorescence, Western blotting, and enzyme-linked immunosorbent assay to track changes in GLP-1 and its receptor expression in diabetic mice subjected to recurrent hypoglycemic episodes. Findings indicate a significant increase in intestinal GLP-1 and GLP-1 receptor expression, correlating with diminished adrenal and glucagon responses, crucial for glucose stabilization during hypoglycemic events. This letter aims to explore the implications of these findings for future therapeutic strategies and the broader understanding of T1D management.

An update on current type 2 diabetes mellitus (T2DM) druggable targets and drugs targeting them

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia and affects millions of people globally. Even after advancement and development in medical science, it is a big task to achieve victory over type 2 diabetes mellitus (T2DM). T2DM can be a reason for fatal events like stroke, cardiac failure, nephropathy, and retinopathy. Many advanced antidiabetic drugs have been introduced in the market in the past two decades, leading researchers to hunt for new target proteins and their potential modulators that can help develop newer antidiabetic drugs. This review article comprises a broad literature of the latest developments in the management of T2DM concerning new target proteins, their inhibitors, or drugs from the clinical arena employed for the successful management of symptoms of T2DM using mono, dual, or triple combination medication therapy. The review categorizes antidiabetic drugs into three general classes that include conventional drug targets, currently explored targets, and upcoming emerging targets. The review aims to merge information on the medicines affecting these targets, their mechanisms, followed by the chemical structures, and recent advancements.

Weight Reduction with GLP-1 Agonists and Paths for Discontinuation While Maintaining Weight Loss

Worldwide, nearly 40% of adults are overweight and 13% are obese. Health consequences of excess weight include cardiovascular diseases, type 2 diabetes, dyslipidemia, and increased mortality. Treating obesity is challenging and calorie restriction often leads to rebound weight gain. Treatments such as bariatric surgery create hesitancy among patients due to their invasiveness. GLP-1 medications have revolutionized weight loss and can reduce body weight in obese patients by between 15% and 25% on average after about 1 year. Their mode of action is to mimic the endogenous GLP-1, an intestinal hormone that regulates glucose metabolism and satiety. However, GLP-1 drugs carry known risks and, since their use for weight loss is recent, may carry unforeseen risks as well. They carry a boxed warning for people with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2. Gastrointestinal adverse events (nausea, vomiting, diarrhea) are fairly common while pancreatitis and intestinal obstruction are rarer. There may be a loss of lean body mass as well as premature facial aging. A significant disadvantage of using these medications is the high rate of weight regain when they are discontinued. Achieving success with pharmacologic treatment and then weaning to avoid future negative effects would be ideal.

Dihydromyricetin Promotes Glucagon-Like Peptide-1 Secretion and Improves Insulin Resistance by Modulation of the Gut Microbiota-CDCA Pathway

Insulin resistance is a common metabolic disease, and its pathogenesis is still unclear. The decrease of glucagon-like peptide-1 (GLP-1) level mediated by the alteration of gut microbiota may be the pathogenesis. The study was to investigate the regulatory effect of dihydromyricetin (DHM) on GLP-1 level and insulin resistance induced by high-fat diet (HFD), and to further explore its possible molecular mechanism. Mice were fed an HFD to establish the model of insulin resistance to determine whether DHM had a protective effect. DHM could improve insulin resistance. DHM increased serum GLP-1 by improving intestinal GLP-1 secretion and inhibiting GLP-1 decomposition, associated with the alteration of intestinal intraepithelial lymphocytes (IELs) proportions and decreased expression of CD26 in IELs and TCRαβ+ CD8αβ+ IELs in HFD-induced mice. DHM could ameliorate GLP-1 level and insulin resistance by modulation of gut microbiota and the metabolites, particularly the regulation of chenodeoxycholic acid (CDCA) content, followed by the inhibition of farnesoid X receptor (FXR) expression in intestinal L cells and increased glucagon gene (Gcg) mRNA expression and GLP-1 secretion. This research demonstrates the role of "gut microbiota-CDCA" pathway in the improvement of intestinal GLP-1 levels in HFD-induced mice by DHM administration, providing a new target for the prevention of insulin resistance.

Improvement of irritable bowel syndrome with glucagon like peptide-1 receptor agonists: a systematic review and meta-analysis

Introduction

Irritable bowel syndrome (IBS) is a severe gastrointestinal condition with symptoms like pain, bloating, diarrhea, and constipation. Glucagon-like peptide-1 (GLP-1) receptors, expressed in the central nervous system and peripheral tissues, have been found to affect gut motility. GLP-1 and its analog ROSE-010 have been shown to inhibit the migrating motor complex and decrease gastrointestinal motility in IBS patients.

Aim

This systematic review and meta-analysis aim to assess the efficacy and safety of GLP-1 receptor agonists in providing pain and symptom relief for individuals with IBS.

Methods

The study conducted extensive searches across various databases, including Cochrane Library, Web of Science, PubMed, Google Scholar, and Science Direct, to identify studies on IBS and related drugs. A search strategy using keywords and medical subject heading terms (MeSH) was developed to ensure inclusivity. Exclusion criteria included non-English language studies, books, conference papers, case reports, in vitro studies, animal studies, and non-original articles.

Results

The study found that ROSE-010 (100 µg) significantly lowered pain intensity in IBS patients compared to a placebo, with an overall odds ratio of 2.30, 95% CI: 1.53-3.46. ROSE-010 (300 µg) is more effective than a placebo for all irritable bowel syndrome subtypes, with consistent effects across trials. ROSE-010 is linked to a greater incidence of nausea, vomiting, and headache than placebo.

Conclusion

ROSE-010, a glucagon-like peptide-1 receptor agonist, has been shown to reduce pain in individuals with IBS. However, its higher frequency of nausea, vomiting, and headache suggests the need for close monitoring and individualized treatment plans. Further investigation is needed to understand its impact on different IBS subtypes and long-term effects.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42024613545.

The immunomodulatory effects of GLP-1 receptor agonists in neurogenerative diseases and ischemic stroke treatment

Glucagon-like peptide-1 (GLP-1) receptor is widely distributed in the digestive system, cardiovascular system, adipose tissue and central nervous system. Numerous GLP-1 receptor-targeting drugs have been investigated in clinical studies for various indications, including type 2 diabetes and obesity (accounts for 70% of the total studies), non-alcoholic steatohepatitis, Alzheimer's disease, and Parkinson's disease. This review presented fundamental information regarding two categories of GLP-1 receptor agonists (GLP-1RAs): peptide-based and small molecule compounds, and elaborated their potential neuroprotective effects by inhibiting neuroinflammation, reducing neuronal apoptosis, and ultimately improving cognitive function in various neurodegenerative diseases. As a new hypoglycemic drug, GLP-1RA has a unique role in reducing the concurrent risk of stroke in T2D patients. Given the infiltration of various peripheral immune cells into brain tissue, particularly in the areas surrounding the infarct lesion, we further investigated the potential immune regulatory mechanisms. GLP-1RA could not only facilitate the M2 polarization of microglia through both direct and indirect pathways, but also modulate the quantity and function of T cell subtypes, including CD4, CD8, and regulatory T cells, resulting into the inhibition of inflammatory responses and the promotion of neuronal regeneration through interleukin-10 secretion. Therefore, we believe that the "Tregs-microglia-neuron/neural precursor cells" axis is instrumental in mediating immune suppression and neuroprotection in the context of ischemic stroke. Given the benefits of rapid diffusion, favorable blood-brain barrier permeability and versatile administration routes, these small molecule compounds will be one of the important candidates of GLP-1RA. We look forward to the further clinical evidence of small molecule GLP-1RA intervention in ischemic stroke or T2D complicated by ischemic stroke.

Discovery and identification of semaphorin 4D as a bioindicator of high fracture incidence in type 2 diabetic mice with glucose control

INTRODUCTION

Bone fracture is increasing in patients with type 2 diabetes mellitus (T2DM) due to skeletal fragility. Most antidiabetics are expected to reduce the incidence of fracture in patients with T2DM, however the results are disappointing. Metformin and GLP-1 receptor agonists have a neutral or minor positive effect in reducing fractures.

OBJECTIVES

We aim to reveal the mechanism of fracture in patients with T2DM treated with metformin or exendin-4, explore the key regulators responsible for bone fragility in T2DM.

METHODS

Trabecular and cortical masses in mice with T2DM were analyzed using micro-computed tomography. Biomechanical strength of bone was determined according to three-point bending, and the expression of bone-associated factors was examined with enzyme-linked immunosorbent assays. Important proteins and miRNAs were identified using proteomics analysis and deep screening analysis. Lastly, immunoprecipitation-mass spectrometry and dual-luciferase reporter analysis were used to identify key molecular signals.

RESULTS

We found that sermaphorin 4D (Sema4D) is the key regulator of bone fragility in T2DM. Exendin-4 increased the biomechanical properties of bone by decreasing serum Sema4D levels, and metformin has little effect on Sema4D. Anti-sema4D treatment could improve bone strength in T2DM mice compared with metformin or exendin-4. The biomechanical properties of bone were comparable between anti-Sema 4D and the combination of metformin and exendin-4. Exendin-4 promoted osteogenesis of BMSCs by activating CRMP2 to reverse the effect of sema4D. Metformin increased miR-140-3p levels, which decreased plexin B1 expression in bone mesenchymal stem cells. Metformin increased the effect of exendin-4 with more GLP-1 receptor expression to increase the biomechanical strength of bone via miR-140-3p-STAT3-miR-3657 signaling.

CONCLUSION

Blood glucose level is not the major factor contributing to impairment in bone remodeling. Sema4D is responsible for the increase in the incidence of bone fractures in T2DM. Accordingly, we proposed an effective therapeutic strategy to eliminate the effect of sema4D.

Regulation of GLP-1 and Glucagon Receptor Function by β-Arrestins in Metabolically Important Cell Types

Glucagon-like peptide-1 (GLP-1) and glucagon (GCG) are polypeptides derived from a common precursor (preproglucagon) that modulates the activity of numerous cell types involved in regulating glucose and energy homeostasis. GLP-1 and GCG exert their biological functions via binding to specific G protein-coupled receptors (GLP-1Rs and GCGRs). Ligand-activated GLP-1Rs and GCGRs preferentially activate the heterotrimeric G protein Gs, resulting in increased cytosolic cAMP levels. However, activation of the two receptors also leads to the recruitment of β-arrestin-1 and -2 (βarr1 and βarr2, respectively) to the intracellular surface of the receptor proteins. The binding of β-arrestins to the activated receptors contributes to the termination of receptor-stimulated G protein coupling. In addition, receptor-β-arrestin complexes can act as signaling nodes in their own right by modulating the activity of many intracellular signaling pathways. In this Review, we will discuss the roles of βarr1 and βarr2 in regulating key metabolic functions mediated by activated GLP-1Rs and GCGRs. During the past decade, GLP-1R agonists have emerged as highly efficacious antidiabetic and antiobesity drugs. Moreover, dual agonists that stimulate both GLP-1Rs and GCGRs are predicted to offer additional therapeutic benefits as compared to GLP-1R agonist monotherapy. We will summarize and try to synthesize a series of studies suggesting that the development of G protein-biased GLP-1R and/or GCGR agonists, which do not lead to the recruitment of β-arrestins, may lead to even more efficacious therapeutic agents.