GLP-1 programs the neurovascular landscape

Structural pharmacology and mechanisms of GLP-1R signaling

Glucagon-like peptide-1 receptor (GLP-1R), a class B1 G protein-coupled receptor, plays critical roles in glucose homeostasis. Recent structural pharmacology studies using cryogenic electron microscopy, X-ray crystallography, mass spectrometry, and functional analyses, have provided valuable insights into its activation by endogenous hormones and mono- or dual agonists like semaglutide and tirzepatide, highly effective in treating type 2 diabetes and obesity. They highlight significant conformational changes in the extracellular and transmembrane domains of GLP-1R that drive receptor activation and downstream signal transduction. Additionally, allosteric modulators, supported by emerging structural information, show great promises as an alternative strategy. Future research investigating unexplored effector interactions, biased signaling, weight rebound mechanisms, and personalized therapy strategies will be critical for developing better therapeutic agents targeting GLP-1R.

Therapeutic Effects of GLP-1 Receptor Agonists and DPP-4 Inhibitors in Neuropathic Pain: Mechanisms and Clinical Implications

Glucagon-like peptide-1 (GLP-1) is a peptide hormone secreted by the small intestine upon food intake. GLP-1 enhances insulin secretion, suppresses glucagon release, and promotes satiety, resulting in reduced food consumption and subsequent weight loss. Endogenous GLP-1 has a very short half-life and is rapidly degraded by the enzyme dipeptidyl-peptidase-IV (DPP-4). To address this limitation, GLP-1 receptor agonists (GLP-1RAs) and DPP-4 inhibitors (DPP-4is) were developed and have demonstrated potency in clinical practice. In recent years, GLP-1RA and DPP4-i therapies are known to have pleiotropic effects, such as a reduction in oxidative stress, autophagy regulation, metabolic reprogramming, enhancement of anti-inflammatory signaling, regulation of gene expression, and being neuroprotective. These effects imply a therapeutic perspective for GLP-1RA and DPP-4i therapies in neuropathic pain treatment. Preclinical and clinical studies increasingly support the hypothesis that these therapies may alleviate neuropathic pain by targeting multiple mechanisms that induce neuropathic pain, such as inflammation, oxidative stress, and mitochondrial dysfunction. This review explores the mechanisms by which GLP-1RAs and DPP-4is alleviate neuropathic pain. It also highlights current advancements in incretin research, focusing on the therapeutic effects of GLP-1RAs and DPP-4-is for neuropathic pain.

Exploration of Bioactive Compounds in Benincasa hispida Seeds: Insight Into Their Therapeutic Potential for Alzheimer's Disease Management Using Computer-Aided Drug Design Platform

Alzheimer's disease (AD) is primarily caused by abnormal protein accumulation, such as β-amyloid plaques and tau tangles, leading to neuronal damage via oxidative stress, neuroinflammation, synaptic dysfunction, and progressive brain atrophy. It is crucial to address and explore alternative therapeutic candidates. Based on traditional reports, the present study investigates the phytochemicals presented in Benincasa hispida (Thunb.) Cogn. seeds and their potency against AD. Primarily, four different solvent systems have been used for crude extraction, and simultaneously 51 phytochemicals (BH_P1-BH_P51) have been selected through chromatography-mass spectrometry (GC-MS) for further study. Five putative AD-associated targets, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), estrogen receptor alpha (ERα), serotonin transporter (SERT), and D2 dopamine receptor (DRD2), were used to explore the individual therapeutic efficacy in the form of docking score using the PyRx 0.8-AutoDock 4.2 platform. According to the docking score (kcal/mol), BH_P19, BH_P20, BH_P30, BH_P18/BH_P31, and BH_P17 are promising ones. Furthermore, the drug-likeness profiles and ligand stability with AChE for 100 nanoseconds in the molecular dynamics simulation study revealed that BH_P19 was the lead therapeutic candidate among all. Overall, the integration of spectral techniques and computational investigations together highlights and encourages the exploration of natural regimens for AD.

Glucagon-like peptide-1 receptor agonists for major neurocognitive disorders

Disease-modifying treatments for major neurocognitive disorders, including Alzheimer's disease, Parkinson's disease and other cognitive deficits, are among the main unmet needs in modern medicine. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), currently licensed for the treatment of type 2 diabetes mellitus and obesity, offer a novel, multilayered mechanism for intervention in neurodegeneration through intermediate, aetiology-agnostic pathways, likely involving metabolic, inflammatory and several other relevant neurobiological processes. In vitro and animal studies have revealed promising signals of neuroprotection, with preliminary supportive evidence emerging from recent pharmacoepidemiological investigations and clinical trials. In this article, we comprehensively review studies that investigate the impact of GLP-1RAs on the various aetiologies of cognitive impairment and dementia syndromes. Focusing on evidence from human studies, we highlight how brain energy homeostasis, neurogenesis, synaptic functioning, neuroinflammation and other cellular stress responses, pathological protein aggregates, proteostasis, cerebrovascular system and blood-brain barrier dynamics may underlie GLP-1RA putative neuroprotective effects. We then report and appraise evidence from clinical studies, including observational investigations, clinical trials and pooled analyses. Finally, we discuss current challenges and perspectives ahead for research and clinical implementation of GLP-1RAs for the care of people with major neurocognitive disorders, including their individual brain penetrance potential, the need for response biomarkers and disease stage-based indications, their possible non-specific effects on brain health, their profile in terms of adverse events and other unwanted effects, the lack of long-term data for efficacy and safety, and issues surrounding cost and availability of treatment.

Vagotomy suppresses food intake by increasing GLP-1 secretion via the M3 AChR-AMPKα pathway in mice

OBJECTIVE

The gut-brain axis (GBA) is involved in the modulation of multiple physiological activities, and the vagus nerve plays an important role in this process. However, the association between vagus nerve function and nutritional regulation remains unclear. Here, we explored changes in the nutritional status of mice after vagotomy and investigated the underlying mechanisms responsible for these changes.

METHODS

We performed vagotomies in mice and verified nerve resection using immunofluorescence staining. We then observed the food intake and body weight of the mice and tested nutritional and inflammation-related markers using enzyme-linked immunosorbent assay (ELISA) kits. The role of glucagon-like peptide 1 (GLP-1) in the GBA was determined using qRT-PCR and ELISA kits. Western blot and ELISA kits were used to explore the underlying mechanisms.

RESULTS

After vagotomy, the mice experienced a deterioration in their nutritional status, which manifested as a significant reduction in body weight and food intake. The expression of the proglucagon gene (GCG), which encodes GLP-1, significantly increased after vagotomy. Mechanistically, acetylcholine (ACh) reversed the HG (high glucose) -induced elevation of GLP-1 secretion. ACh upregulated AMPKα phosphorylation, thereby reducing GLP-1 secretion. Moreover, the level of AMPKα phosphorylation was enhanced by ACh via M3AChR.

CONCLUSIONS

ACh released by the vagus nerve counteracts the anorectic effects of GLP-1 under normal physiological conditions. Vagotomy blocks this feedback, resulting in a loss of food intake and body weight in mice.

Genetic Evidence of Obesity-Induced Chronic Wounds Mediated by Inflammatory Biomarkers

Background: Obese patients are increasingly recognized as being at higher risk for skin diseases, particularly chronic wounds. While the exact mechanisms remain unclear, obesity is suspected to influence the development of chronic injuries via inflammatory biomarkers. Single nucleotide polymorphisms (SNPs) may further influence gene expression, protein function, and levels of inflammatory biomarkers through various mechanisms, thereby modulating inflammatory responses that contribute to wound pathogenesis. Methods: A two-sample two-step Mendelian Randomization (MR) was employed to explore the causal relationship between obesity and chronic wounds, focusing on the mediating role of inflammatory biomarkers. SNPs were used as instrumental variables (IVs) to infer causality. Obesity-related genetic data were sourced from the UK Biobank and GIANT consortium. Genome-wide association studies provided data on 92 inflammatory biomarkers, involving 14,824 and 575,531 individuals. Pressure injuries, lower limb venous ulcers, and diabetic foot ulcer data were obtained from FinnGen R10 and the Pan-UK Biobank. Results: Obesity significantly increased the risk of pressure injuries, lower limb venous ulcers, and diabetic foot ulcers. CCL19, hGDNF, IL-12B, and TNFRSF9 were identified as mediators in obesity-induced lower limb venous ulcers. Conclusion: This study provides genetic evidence that obesity leads to lower limb venous ulcers via inflammatory biomarkers, suggesting potential therapeutic targets for intervention.

Advances in energy balance & metabolism circuitry

Advancements in informatics, genetics, and neuroscience have greatly expanded our understanding of how the central nervous system (CNS) regulates energy balance and metabolism. This chapter explores the key neural circuits within the hypothalamus and brainstem that integrate behavioral and physiological processes to maintain metabolic homeostasis. It also examines the dynamic interplay between the CNS and peripheral organs, mediated through hormonal and neuronal signals, which fine-tune appetite, energy expenditure, and body weight. Furthermore, we highlight groundbreaking research that unveils molecular and cellular pathways governing energy regulation, representing a new frontier in addressing obesity and metabolic disorders. Innovative approaches, such as neurogenetic and neuromodulation techniques, are explored as promising strategies for improving weight management and metabolic health. By providing a comprehensive perspective on the mechanisms underlying energy balance, this chapter underscores the transformative potential of emerging therapeutic innovations.

Aging, vascular dysfunction, and the blood-brain barrier: unveiling the pathophysiology of stroke in older adults

The progressive decline of vascular integrity and blood-brain barrier (BBB) function is associated with aging, a major risk factor for stroke. This review describes the cellular and molecular changes in the brain microvasculature of the neurovascular unit (NVU) that contribute to the development of BBB dysfunction in aging, such as endothelial cell senescence, oxidative stress, and degradation of tight junction proteins. Stroke severity and recovery are exacerbated by BBB breakdown, leading to neuroinflammation, neurotoxicity, and cerebral oedema while identifying molecular mechanisms such as the NLRP3 inflammasome, matrix metalloproteinases (MMPs), and non-coding RNAs (e.g., miRNAs and circRNAs) that drive BBB disruption in aging and stroke. Real-time assessment of BBB permeability in stroke pathophysiology is made possible using advanced imaging techniques, such as dynamic contrast-enhanced MRI and positron emission tomography. Furthermore, biomarkers, including claudin-5, PDGFRβ, or albumin concentration, serve as markers of BBB integrity and vascular health. Restoration of BBB function and stroke recovery with emerging therapeutic strategies, including sirtuin modulators (SIRT1 and SIRT3 activators to enhance endothelial function and mitochondrial health), stem cell-derived extracellular vesicles (iPSC-sEVs for BBB repair and neuroprotection), NLRP3 inflammasome inhibitors (MCC950 to attenuate endothelial pyroptosis and inflammation), hydrogen-rich water therapy (to counteract oxidative stress-induced BBB damage), and neuropeptides such as cortistatin (to regulate neuroinflammation and BBB stability), is promising. This review explores the pathophysiological mechanisms of BBB dysfunction in aging and stroke, their relation to potential therapeutic targets, and novel approaches to improve vascular health and neuroprotection.

Comparative effectiveness of SGLT2 inhibitors and GLP-1 receptor agonists in preventing Alzheimer's disease, vascular dementia, and other dementia types among patients with type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with an elevated risk of dementia, including Alzheimer's disease (AD) and vascular dementia (VaD). While sodium-glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists have shown neuroprotective potential, comparative data on their efficacy in dementia prevention remain scarce.

METHODS

- We conducted a retrospective cohort study using the TriNetX database, including 307,103 SGLT2 inhibitor users and 348,686 GLP-1 receptor agonist users with T2DM. Propensity score matching yielded 221,883 pairs with balanced baseline characteristics. The primary outcome was overall dementia incidence, with secondary outcomes including AD, VaD, and all-cause mortality. Hazard ratios (HRs) were calculated using Cox proportional hazards models.

RESULTS

SGLT2 inhibitors were associated with a significantly lower incidence of overall dementia compared to GLP-1 receptor agonists (2.7 % vs. 3.6 %; HR, 0.92; 95 % CI, 0.89-0.95). The risk of VaD (HR, 0.89; 95 % CI, 0.84-0.95) and AD (HR, 0.90; 95 % CI, 0.86-0.94) was also reduced with SGLT2 inhibitors. All-cause mortality was lower in the SGLT2 group (3.6 % vs. 4.6 %; HR, 0.95; 95 % CI, 0.92-0.98). No significant difference was observed in other dementia subtypes (HR, 0.96; 95 % CI, 0.91-1.01).

CONCLUSIONS

In this large, real-world cohort, SGLT2 inhibitors demonstrated superior efficacy over GLP-1 receptor agonists in reducing the risks of overall dementia, VaD, and AD among patients with T2DM. These findings support the preferential use of SGLT2 inhibitors in mitigating dementia risk in this population, though randomized controlled trials are warranted for confirmation.

Metformin's Effects on Cognitive Function from a Biovariance Perspective: A Narrative Review

This study examines the effects of metformin on brain functions focusing on the variability of the results reported in the literature. While some studies suggest that metformin may have neuroprotective effects in diabetic patients, others report an insignificant impact of metformin on cognitive function, or even a negative effect. We propose that this inconsistency may be due to intrinsic cellular-level variability among individuals, which we term "biovariance". Biovariance persists even in demographically homogeneous samples due to complex and stochastic biological processes. Additionally, the complex metabolic actions of metformin, including its influence on neuroenergetics and neuronal survival, may produce different effects depending on individual metabolic characteristics.

Dysregulation of Metabolic Peptides in the Gut-Brain Axis Promotes Hyperinsulinemia, Obesity, and Neurodegeneration

Metabolic peptides can influence metabolic processes and contribute to both inflammatory and/or anti-inflammatory responses. Studies have shown that there are thousands of metabolic peptides, made up of short chains of amino acids, that the human body produces. These peptides are crucial for regulating many different processes like metabolism and cell signaling, as they bind to receptors on various cells. This review will cover the role of three specific metabolic peptides and their roles in hyperinsulinemia, diabetes, inflammation, and neurodegeneration, as well as their roles in type 3 diabetes and dementia. The metabolic peptides glucagon-like peptide 1 (GLP-1), gastric inhibitor polypeptide (GIP), and pancreatic peptide (PP) will be discussed, as dysregulation within their processes can lead to the development of various inflammatory and neurodegenerative diseases. Research has been able to closely investigate the connections between these metabolic peptides and their links to the gut-brain axis, highlighting changes made in the gut that can lead to dysfunction in processes in the brain, as well as changes made in the brain that can lead to dysregulation in the gut. The role of metabolic peptides in the development and potentially reversal of diseases such as obesity, hyperinsulinemia, and type 2 diabetes will also be discussed. Furthermore, we review the potential links between these conditions and neuroinflammation and the development of neurodegenerative diseases like dementia, specifically Parkinson's disease and Alzheimer's disease.