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Diabetes mellitus affects roughly one in ten people globally and is the world's ninth leading cause of death. However, a significant portion of chronic complications that contribute to mortality can be prevented with proper treatment and medication. Glucagon-like peptide 1 receptor agonists, such as Exendin-4, are one of the leading classes of Type 2 diabetes treatments but are prohibitively expensive. In this study, experimental models for recombinant Exendin-4 protein production were designed in both Escherichia coli and Saccharomyces cerevisiae. Protein expression in the chromosomally integrated S. cerevisiae strain was observed at the expected size of Exendin-4 and confirmed by immunoassay. This provides a foundation for the use of this Generally Regarded as Safe organism as an affordable treatment for Type 2 diabetes that can be propagated, prepared, and distributed locally. [ABSTRACT FROM AUTHOR]

Non-somatostatin receptor expressing hypovascular insulinomas can be challenging to prove through imaging. This case highlights the utility of a structured approach to molecular imaging in patients with confirmed endogenous hyperinsulinemia. A 54-year-old woman was admitted because of a sudden loss of consciousness. Her relative reported that she complained of dizziness, intense sweating, blurry vision, and upper extremity tingling before becoming unresponsive for 20 min, after which the patient had little recollection of the event. She experienced similar episodes of shorter duration, trouble recalling everyday events, and unintentional weight gain of over 10 kg during the previous two years. Abdominal magnetic resonance imaging (MRI) and multidetector computerized tomography (MDCT) were unremarkable. Selective arterial calcium stimulation significantly increased hepatic venous insulin concentrations when the superior mesenteric and gastroduodenal arteries were stimulated. Technetium-99m (99mTc) octreotide single-photon emission computed tomography (SPECT) did not localize the lesion. Gallium-68 DOTA-Exendin-4 PET/CT acquisition was performed. A single intense 2 cm hyperperfused pancreatic lesion was located anteriorly in the head of the pancreas. Earlier targeted PET/CT imaging and recognition of significant neuropsychiatric symptoms attributable to the patient's hypoglycemic state might have accelerated the resolution of her condition and obviated the need for unnecessary testing. [ABSTRACT FROM AUTHOR]

Insulinomas are the most common functional pancreatic neuroendocrine neoplasm; when treatment is delayed, they induce hyperinsulinemic hypoglycemia, which is life-threatening. As surgical resection is the only curative treatment for insulinoma, preoperative localization is crucial; however, localization based on conventional imaging modalities such as computed tomography (CT) and magnetic resonance imaging is often inconclusive. Somatostatin receptor-targeted imaging is another option for detecting pancreatic neuroendocrine neoplasms but has low sensitivity and is not specific for insulinoma. The clinical application of other localizing approaches such as selective arterial calcium stimulation and endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) is limited by their being invasive and/or technically complex. Moreover, an EUS-FNA specimen of an insulinoma may be negative on insulin immunostaining. Thus, a noninvasive and clinically practical insulinoma-specific diagnostic tool to discriminate insulinomas with high accuracy is anticipated. Glucagon-like peptide-1 receptor (GLP-1R)-targeted imaging has emerged in the effort to fulfill this need. We recently developed the novel fluorine-18-labeled exendin-4-based probe conjugated with polyethylene glycol, [18F]FB(ePEG12)12-exendin-4 (18F-exendin-4) for positron emission tomography (PET) imaging and reported its clinical benefit in a case of insulinoma in the pancreatic tail. We report here a case of insulinoma in the pancreatic head in which an EUS-FNA specimen was negative on insulin immunostaining while precise preoperative localization and conclusive evidence for curative enucleation was provided by 18F-exendin-4 PET/CT (Japan Registry of Clinical Trials; jRCTs051200156).

Abstract Hypoxic-ischaemic encephalopathy (HIE) arises from diminished blood flow and oxygen to the neonatal brain during labor, leading to infant mortality or severe brain damage, with a global incidence of 1.5 per 1000 live births. Glucagon-like Peptide 1 Receptor (GLP1-R) agonists, used in type 2 diabetes treatment, exhibit neuroprotective effects in various brain injury models, including HIE. In this study, we observed enhanced neurological outcomes in post-natal day 10 mice with surgically induced hypoxic-ischaemic (HI) brain injury after immediate systemic administration of exendin-4 or semaglutide. Short- and long-term assessments revealed improved neuropathology, survival rates, and locomotor function. We explored the mechanisms by which GLP1-R agonists trigger neuroprotection and reduce inflammation following oxygen-glucose deprivation and HI in neonatal mice, highlighting the upregulation of the PI3/AKT signalling pathway and increased cAMP levels. These findings shed light on the neuroprotective and anti-inflammatory effects of GLP1-R agonists in HIE, potentially extending to other neurological conditions, supporting their potential clinical use in treating infants with HIE.

Simple Summary: This study investigated the influence of exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, on fall webworm Hyphantria cunea larvae. We found that exendin-4 induced growth arrest by regulating sugar metabolism, affecting digestive enzyme activities, and altering metabolite profiles. Specifically, it decreased glucose and trehalose levels while increasing the glycogen content, indicating a regulatory effect on blood sugar. Exendin-4 also promoted glycolysis and reduced ATP levels, potentially through the activation of AMPK. These findings enhance our understanding of the physiological effects of GLP-1R agonists in insects and could inform pest management strategies. Insects' growth and development are highly dependent on energy supply, with sugar metabolism playing a pivotal role in maintaining homeostasis and regulating physiological processes. The present study investigated the effects of exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, on the growth, development, glycolysis, and energy metabolism of fourth-instar larvae of the fall webworm, Hyphantria cunea. We determined the impact of exendin-4 on larval growth and nutritional indices, analyzed the responses of glycolytic and metabolic pathways, and revealed the underlying regulatory mechanisms. Exendin-4 treatment significantly decreased growth and nutritional indices, influenced the activity of digestive enzymes, and induced changes in metabolite profiles, particularly affecting energy substance metabolism. We observed an increase in the glycogen content and a decrease in glucose and trehalose levels in the hemolymph, suggesting a regulatory effect on blood sugar homeostasis. Furthermore, exendin-4 promoted glycolysis by enhancing the activities and expressions of key glycolytic enzymes, leading to an increase in pyruvate production. This was accompanied by a reduction in ATP levels and the activation of AMP-activated protein kinase (AMPK), which may underlie the growth arrest in larvae. Our findings provide novel insights into the effects of exendin-4 on insect responses from an energy metabolism perspective and may contribute to the development of GLP-1R agonists for pest management. [ABSTRACT FROM AUTHOR]

Objective: Poorly controlled diabetes frequently exacerbates lung infection, thereby complicating treatment strategies. Recent studies have shown that exendin-4 exhibits not only hypoglycemic but also anti-inflammatory properties. This study aimed to explore the role of exendin-4 in lung infection with diabetes, as well as its association with NOD1/NF-κB and the T1R2/T1R3 sweet taste receptor. Methods: 16HBE human bronchial epithelial cells cultured with 20 mM glucose were stimulated with lipopolysaccharide (LPS) isolated from Pseudomonas aeruginosa (PA). Furthermore, Sprague‒Dawley rats were fed a high-fat diet, followed by intraperitoneal injection of streptozotocin and intratracheal instillation of PA. The levels of TNF-α, IL-1β and IL-6 were evaluated using ELISAs and RT‒qPCR. The expression of T1R2, T1R3, NOD1 and NF-κB p65 was assayed using western blotting and immunofluorescence staining. Pathological changes in the lungs of the rats were observed using hematoxylin and eosin (H&E) staining. Results: At the same dose of LPS, the 20 mM glucose group produced more proinflammatory cytokines (TNF-α, IL-1β and IL-6) and had higher levels of T1R2, T1R3, NOD1 and NF-κB p65 than the normal control group (with 5.6 mM glucose). However, preintervention with exendin-4 significantly reduced the levels of the aforementioned proinflammatory cytokines and signaling molecules. Similarly, diabetic rats infected with PA exhibited increased levels of proinflammatory cytokines in their lungs and increased expression of T1R2, T1R3, NOD1 and NF-κB p65, and these effects were reversed by exendin-4. Conclusions: Diabetic hyperglycemia can exacerbate inflammation during lung infection, promote the increase in NOD1/NF-κB, and promote T1R2/T1R3. Exendin-4 can ameliorate PA-related pneumonia with diabetes and overexpression of NOD1/NF-κB. Additionally, exendin-4 suppresses T1R2/T1R3, potentially through its hypoglycemic effect or through a direct mechanism. The correlation between heightened expression of T1R2/T1R3 and an intensified inflammatory response in lung infection with diabetes requires further investigation. [ABSTRACT FROM AUTHOR]

Aims: Necroptosis is one of programmed death that may aggravate spinal cord injury (SCI). We aimed to investigate the effect and mechanism of exendin‐4 (EX‐4) on the recovery of motor function and necroptosis after SCI. Methods: The SD rats with left hemisection in the T10 spinal cord as SCI model were used. The behavior tests were measured within 4 weeks. The effects of EX‐4 on necroptosis‐associated proteins and autophagy flux were explored. In addition, the SHSY5Y cell model was introduced to explore the direct effect of EX‐4 on neurons. The effect of lysosome was explored using mTOR activator and AO staining. Results: EX‐4 could improve motor function and limb strength, promote the recovery of autophagy flux, and accelerate the degradation of necroptosis‐related protein at 3 d after injury in rats. EX‐4 reduced lysosome membrane permeability, promoted the recovery of lysosome function and autophagy flux, and accelerated the degradation of necroptosis‐related proteins by inhibiting the phosphorylation level of mTOR in the SHSY5Y cell model. Conclusion: Our results demonstrated that EX‐4 may improve motor function after SCI via inhibiting mTOR phosphorylation level and accelerating the degradation of necroptosis‐related proteins in neurons. Our findings may provide new therapeutic targets for clinical treatment after SCI. [ABSTRACT FROM AUTHOR]

Introduction: Islet xenotransplantation may be a therapeutic option in type 1 diabetes. Recent advances in generating genetically modified source pigs offer advantages as immune suppressants can potentially be eliminated after the transplantation. Therapy monitoring would greatly benefit from noninvasive methods for assessing the viability of transplanted islets. Peptide-based positron emission tomography (PET) targeting the glucagon-like peptide-1 receptor (GLP1R) expression on beta cells may offer a procedure that can directly be translated from an experimental setting to the clinic. The aim of this study was to establish the labeling of the GLP1R ligand [68Ga]Ga-exendin-4, to demonstrate the feasibility of imaging porcine islet xenografts in vivo and to compare signal quality for three different transplantation sites in a mouse model. Materials and methods: Mice with engrafted neonatal porcine islet cell clusters (NPICCs) under the kidney capsule, into the inguinal fold, or the lower hindlimb muscle were studied. After reaching normoglycemia, the mice were injected with [68Ga]Ga-exendin-4 for PET data acquisition. Subsequent autoradiography (AR) was used for comparing ex vivo data with in vivo uptake. Results: NPICCs in the lower right hindlimb muscle could be detected in vivo and in AR. Due to the high background in the kidney and urinary bladder, islets could not be detected in the PET data at transplantation sites close to these organs, while AR showed a clear signal for the islets in the inguinal fold. Discussion: PET with [68Ga]Ga-exendin-4 detects islets transplanted in the hindlimb muscle tissue of mice, offering the potential of longitudinal monitoring of viable porcine islets. Other sites are not suitable for in vivo imaging owing to high activity accumulation of Exendin-4 in kidney and bladder. [ABSTRACT FROM AUTHOR]

Hypoxic-ischaemic encephalopathy (HIE) arises from diminished blood flow and oxygen to the neonatal brain during labor, leading to infant mortality or severe brain damage, with a global incidence of 1.5 per 1000 live births. Glucagon-like Peptide 1 Receptor (GLP1-R) agonists, used in type 2 diabetes treatment, exhibit neuroprotective effects in various brain injury models, including HIE. In this study, we observed enhanced neurological outcomes in post-natal day 10 mice with surgically induced hypoxic-ischaemic (HI) brain injury after immediate systemic administration of exendin-4 or semaglutide. Short- and long-term assessments revealed improved neuropathology, survival rates, and locomotor function. We explored the mechanisms by which GLP1-R agonists trigger neuroprotection and reduce inflammation following oxygen-glucose deprivation and HI in neonatal mice, highlighting the upregulation of the PI3/AKT signalling pathway and increased cAMP levels. These findings shed light on the neuroprotective and anti-inflammatory effects of GLP1-R agonists in HIE, potentially extending to other neurological conditions, supporting their potential clinical use in treating infants with HIE. Synopsis: Hypoxic-ischaemic encephalopathy (HIE) is caused by complications during labor or the umbilical cord causing reduced oxygen to the baby's brain. This leads to brain injury and lifelong disability or death. Administration of GLP1 receptor agonists to a mouse model of HIE reduces brain damage and improves multiple readouts of efficacy. A single peripheral administration of a GLP1 receptor agonist, used in the clinic to treat diabetes, significantly reduced brain infarct size and improved survival and locomotor function in a mouse model of neonatal HIE. GLP1 receptor agonists activated neuroprotective pathways and reduced markers of inflammatory response in the brain. This study is supportive of further investigating the clinical application of GLP1 receptor agonist for HIE but also more widely for other neurological diseases. Hypoxic-ischaemic encephalopathy (HIE) is caused by complications during labor or the umbilical cord causing reduced oxygen to the baby's brain. This leads to brain injury and lifelong disability or death. Administration of GLP1 receptor agonists to a mouse model of HIE reduces brain damage and improves multiple readouts of efficacy. [ABSTRACT FROM AUTHOR]

This study investigated the neuroprotective effects of exendin-4 (EXE-4), an analog of the glucagon-like peptide 1 receptor (GLP-1R) on memory and on the neuronal populations that constitute the hippocampus of rats submitted to a sporadic dementia of Alzheimer's type (SDAT). Male Wistar rats received streptozotocin (STZ icv, 3 mg/kg diluted in aCFS, 5 µl/ventricle) and were treated for 21 days with EXE-4 (10 µg/kg, ip; saline as the vehicle). Four groups were formed: vehicle, EXE-4, STZ, and STZ + EXE-4. The groups were submitted to Y-Maze (YM), object recognition (ORT), and object displacement tasks (ODT) to assess learning and memory. The brains were used for immunohistochemical and immunofluorescent techniques with antibodies to NeuN, cleaved caspase-3 (CC3), PCNA, doublecortin (DCX), synaptophysin (SYP), and insulin receptor (IR). STZ worsened spatial memory in the YMT, as well as short-term (STM) and long-term (LTM) memories in the ORT and ODT, respectively. EXE-4 protected against memory impairment in STZ animals. STZ reduced mature neuron density (NeuN) and increased cell apoptosis (CC3) in the DG, CA1, and CA3. EXE-4 protected against neuronal death in all regions. EXE-4 increased PCNA+ cells in all regions of the hippocampus, and STZ attenuated this effect. STZ reduced neurogenesis in DG per se as well as synaptogenesis induced by EXE-4. EXE-4 increased immunoreactivity to IR in the CA1. From these findings, EXE-4 showed a beneficial effect on hippocampal pyramidal and granular neurons in the SDAT showing anti-apoptotic properties and promoting cell proliferation. In parallel, EXE-4 preserved the memory of SDAT rats. EXE-4 appears to enhance synapses at CA3 and DG. In conclusion, these data indicate that agonists to GLP-1R have a beneficial effect on hippocampal neurons in AD. [ABSTRACT FROM AUTHOR]

Diabetes mellitus affects roughly one in ten people globally and is the world’s ninth leading cause of death. However, a significant portion of chronic complications that contribute to mortality can be prevented with proper treatment and medication. Glucagon-like peptide 1 receptor agonists, such as Exendin-4, are one of the leading classes of Type 2 diabetes treatments but are prohibitively expensive. In this study, experimental models for recombinant Exendin-4 protein production were designed in both Escherichia coli and Saccharomyces cerevisiae. Protein expression in the chromosomally integrated S. cerevisiae strain was observed at the expected size of Exendin-4 and confirmed by immunoassay. This provides a foundation for the use of this Generally Regarded as Safe organism as an affordable treatment for Type 2 diabetes that can be propagated, prepared, and distributed locally.

Nonunions and delayed unions pose significant challenges in orthopedic treatment, with current therapies often proving inadequate. Bone tissue engineering (BTE), particularly through endochondral ossification (ECO), emerges as a promising strategy for addressing critical bone defects. This study introduces mesenchymal stem cells overexpressing Exendin-4 (MSC-E4), designed to modulate bone remodeling via their autocrine and paracrine functions. We established a type I collagen (Col-I) sponge-based in vitro model that effectively recapitulates the ECO pathway. MSC-E4 demonstrated superior chondrogenic and hypertrophic differentiation and enhanced the ECO cell fate in single-cell sequencing analysis. Furthermore, MSC-E4 encapsulated in microscaffold, effectively facilitated bone regeneration in a rat calvarial defect model, underscoring its potential as a therapeutic agent for bone regeneration. Our findings advocate for MSC-E4 within a BTE framework as a novel and potent approach for treating significant bone defects, leveraging the intrinsic ECO process.

Parkinson's disease (PD) is one of the most common neurodegenerative diseases. Recent data highlight similarities between neurodegenerative diseases, including PD and type 2 diabetes mellitus (T2DM), suggesting a crucial interplay between the gut–brain axis. Glucagon-like peptide-1 receptor (GLP-1R) agonists, known for their use in T2DM treatment, are currently extensively studied as novel PD modifying agents. For this narrative review article, we searched PubMed and Scopus databases for peer-reviewed research, review articles and clinical trials regarding GLP-1R agonists and PD published in the English language with no time restrictions. We also screened the references of the selected articles for possible additional articles in order to include most of the key recent evidence. Many data on animal models and preclinical studies show that GLP1-R agonists can restore dopamine levels, inhibit dopaminergic loss, attenuate neuronal degeneration and alleviate motor and non-motor features of PD. Evidence from clinical studies is also very promising, enhancing the possibility of adding GLP1-R agonists to the current armamentarium of drugs available for PD treatment. [ABSTRACT FROM AUTHOR]

The central neuropeptide GLP-1 is synthesized by preproglucagon (PPG) neurons in the brain. GLP-1 receptors are widely distributed in central nervous system. Hippocampus is a key component of the limbic system which is involved in learning, memory, and cognition. Previous studies have shown that overexpression of GLP-1 receptors in the hippocampus could improve the process of learning and memory. However, up to now, the direct electrophysiological effects and possible molecular mechanisms of GLP-1 in hippocampal CAl neurons remain unexplored. The present study aims to evaluate the effects and mechanisms of GLP-1 on the spontaneous firing activity of hippocampal CAl neurons. Employing multibarrel single-unit extracellular recordings, the present study showed that micro-pressure administration of GLP-1 receptor agonist, exendin-4, significantly increased the spontaneous firing rate of hippocampal CA1 neurons in rats. Furthermore, application of the specific GLP-1 receptor antagonist, exendin(9−39), alone significantly decreased the firing rate of CA1 neurons, suggesting that endogenous GLP-1 modulates the firing activity of CA1 neurons. Co-application of exendin(9−39) completely blocked exendin-4-induced excitation of hippocampal CA1 neurons. Finally, the present study demonstrated for the first time that the transient receptor potential canonical 4 (TRPC4)/TRPC5 channels may be involved in exendin-4-induced excitation. The present studies may provide a rationale for further investigation of the modulation of GLP-1 on learning and memory as well as its possible involvement in Alzheimer's disease. • Exendin-4 increased the spontaneous firing rate of hippocampal CA1 neurons. • Endogenous GLP-1 influences the spontaneous firing activity of hippocampal CA1 neurons. • The TRPC4/5 pathway may be involved in the activation of GLP-1R-induced excitation. [ABSTRACT FROM AUTHOR]

Protein folding is a prominent area of research in the life sciences. Exendin-4, a 39-amino acid peptide hormone, is of particular interest due to its potential therapeutic applications. In this study, we employed a steered molecular dynamics method to investigate the folding of Exendin-4. Our simulations reveal an intermediate state during the folding process, suggesting a more complex three-state mode of folding. Structural analysis indicates that Exendin-4 folds through two distinct pathways: pathway 1 involves gradual growth of a helical structure after the collapse of the hydrophobic core in the Trp-cage, while pathway 2 involves initial formation of local microdomains (helical structure and Trp-cage) which then combine with each other to form a stable native structure. We found that the folding along these pathways follows the hydrophobic collapse mechanism and the diffusion-collision mechanism, respectively. We believe that these two mechanisms together govern the folding of Exendin-4. These results significantly differ from those observed in most small protein folding. Our study on the folding of Exendin-4 will advance our understanding of the protein folding mechanism. [ABSTRACT FROM AUTHOR]

Objective: Co-treatment with long acting PYY and the GLP-1 receptor agonists has potential as an efficient obesity treatment. This study investigates whether the mechanisms behind additive reduction of food intake and weight loss depends on complementary effects in brain areas regulating food intake and if restoration of leptin sensitivity is involved. Methods: Diet-induced obese (DIO) mice were co-treated with PYY(3–36) and exendin-4 (Ex4, GLP-1R agonist) for 14 days using minipumps. Leptin responsiveness was evaluated by measuring food intake and body weight after leptin injection, and gene expression profile was investigated in various of brain regions and liver. Results: We show that weight loss associated with co-treatment of PYY(3–36) and Ex4 and Ex4 mono-treatment in DIO mice increased expression of several genes in area postrema (AP) known to be involved in appetite regulation and Cart, Pdyn, Bdnf and Klb were synergistically upregulated by the co-treatment. The upregulations were independent of weight loss, as shown by inclusion of a weight matched control. Moreover, PYY(3–36) and Ex4 co-treatment resulted in synergistically upregulated plasma concentrations of soluble leptin receptor (SLR) and improved sensitivity to exogenous leptin demonstrated by food intake lowering. Conclusion: The study results suggest that synergistic upregulation of appetite-regulating genes in AP and improved leptin sensitivity are important mediators for the additive weight loss resulting from PYY and Ex4 co-treatment.

Exendin-4 (Ex4) is a 39-amino acid peptide isolated from the salivary secretions of the lizard Heloderma susceptum and it has similar biological function as glucan-like peptide (GLP-1) receptor. The most important physiological role of GLP-1 is to regulate the amount of glucose metabolism by reducing the entry of glucose into the cells. The binding of Ex4 to cholera toxin B subunit (CTB) increases its efficacy by binding to the receptor of intestinal epithelial cells. Transgenic plants can be used as factories for the production of recombinant proteins. In order to maximize the efficiency of transgenic plants, the expression of foreign genes can be regulated in terms of time and place under the regulation of different promoters. Considering the nutritional value of carrot tuber and its fresh consumption, in this study, CTBEx4 gene was expressed in carrot plant using a root-specific promoter. In this study, in order to specifically express the CTBEx4 gene in carrot root, the Major Latex-Like promoter (MLL) related to the specific expression in sugar beet storage root tissue was replaced by the CaMV35S promoter in the pBI121 construct and were used for the transformation of carrot explants. Materials and methods Using the CTAB method, DNA was extracted from the leaves of the sugar beet plant, then the PCR reaction was performed using specific MLL primers. The obtained fragment was replaced by the CaMV35S promoter in the pBI121 construct using restriction enzymes. Both pBI121-Mll)CTBEx4 and pBI121-CamV35S-CTBEx4 constructs were used to transform carrot leaf explants using Agrobacterium tumefaciens bacteria. Transgenic explants were indirectly regenerated into plants in MS culture media in vitro and then transferred to pot. Finally, the CTBEx4 gene expression of the transgenic plants was analyzed at mRNA and protein levels using RT-PCR and ELISA. Results The results of the expression analysis using RT-PCR and ELISA methods indicated that the expression of CTBEx4 gene in carrot root tissue was regulated by MLL promoter, while no expression was observed in leaf tissue. Also, the results showed that the CTBEx4 gene was expressed under CaMV35S promoter regulation in both root and leaf tissues, but its expression in roots was lower (30%) than that under MLL promoter regulation. The obtained results indicated the ability of the MLL promoter to specific expression the CTBEx4 gene in the roots of carrot plants. Conclusions The MLL promoter was able to express the CTBEx4 gene in the root tissue of carrot plants at the mRNA and protein level, Also, CTBEx4 protein under MLL promoter had higher expression level compared to CaMV35S promoter. [ABSTRACT FROM AUTHOR]

Abstract Background Peptidic radiotracers are preferentially excreted through the kidneys, which often results in high persistent renal retention of radioactivity, limiting or even preventing therapeutic clinical translation of these radiotracers. Exendin-4, which targets the glucagon-like-peptide 1 receptor (GLP-1R) overexpressed in insulinomas and in congenital hyperinsulinism, is an example thereof. The use of the tripeptide MVK, which is readily cleaved between methionine and valine by neprilysin at the renal brush border membrane, already showed promising results in reducing kidney uptake as reported in the literature. Based on our previous findings we were interested how linker variants with multiple copies of the MV-motive influence renal washout of radiolabelled exendin-4. Results Three exendin-4 derivatives, carrying either one MVK, a MV-MVK or a MVK-MVK linker were synthesized and compared to a reference compound lacking a cleavable linker. In vivo results of a biodistribution in GLP-1R overexpressing tumour bearing mice at 24 h post-injection demonstrated a significant reduction (at least 57%) of renal retention of all 111In-labeled exendin-4 compounds equipped with a cleavable linker compared to the reference compound. While the insertion of the single linker MVK led to a reduction in kidney uptake of 70%, the dual approach with the linker MV-MVK slightly, but not significantly enhanced this effect, with 77% reduction in kidney uptake compared to the reference. In vitro IC50 and cell uptake studies were conducted and demonstrated that though the cleavable linkers negatively influenced the affinity towards the GLP-1R, cell uptake remained largely unaffected, except for the MV-MVK cleavable linker conjugate, which displayed lower cell uptake than the other compounds. Importantly, the tumour uptake in the biodistribution study was not significantly affected with 2.9, 2.5, 3.2 and 1.5% iA/g for radiolabelled Ex4, MVK-Ex4, MV-MVK-Ex4 and MVK-MVK-Ex4, respectively. Conclusion Cleavable linkers are highly efficient in reducing the radioactivity burden in the kidney. Though the dual linker approach using the instillation of MV-MVK or MVK-MVK between exendin-4 and the radiometal chelator did not significantly outperform the single cleavable linker MVK, further structural optimization or the combination of different cleavable linkers could be a stepping stone in reducing radiation-induced nephrotoxicity.

Corneal confocal microscopy (CCM) is emerging as a tool for identifying small fiber neuropathy in both peripheral neuropathies and neurodegenerative disease of the central nervous system (CNS). The value of corneal nerves as biomarkers for efficacy of clinical interventions against small fiber neuropathy and neurodegenerative disease is less clear but may be supported by preclinical studies of investigational agents. We, therefore, used diverse investigational agents to assess concordance of efficacy against corneal nerve loss and peripheral neuropathy in a mouse model of diabetes. Ocular delivery of the peptides ciliary neurotrophic factor (CNTF) or the glucagon-like peptide (GLP) analog exendin-4, both of which prevent diabetic neuropathy when given systemically, restored corneal nerve density within 2 weeks. Similarly, ocular delivery of the muscarinic receptor antagonist cyclopentolate protected corneal nerve density while concurrently reversing indices of systemic peripheral neuropathy. Conversely, systemic delivery of the muscarinic antagonist glycopyrrolate, but not gallamine, prevented multiple indices of systemic peripheral neuropathy and concurrently protected against corneal nerve loss. These data highlight the potential for use of corneal nerve quantification by confocal microscopy as a bridging assay between in vitro and whole animal assays in drug development programs for neuroprotectants and support its use as a biomarker of efficacy against peripheral neuropathy.

Non-somatostatin receptor expressing hypovascular insulinomas can be challenging to prove through imaging. This case highlights the utility of a structured approach to molecular imaging in patients with confirmed endogenous hyperinsulinemia. A 54-year-old woman was admitted because of a sudden loss of consciousness. Her relative reported that she complained of dizziness, intense sweating, blurry vision, and upper extremity tingling before becoming unresponsive for 20 min, after which the patient had little recollection of the event. She experienced similar episodes of shorter duration, trouble recalling everyday events, and unintentional weight gain of over 10 kg during the previous two years. Abdominal magnetic resonance imaging (MRI) and multidetector computerized tomography (MDCT) were unremarkable. Selective arterial calcium stimulation significantly increased hepatic venous insulin concentrations when the superior mesenteric and gastroduodenal arteries were stimulated. Technetium-99m (99mTc) octreotide single-photon emission computed tomography (SPECT) did not localize the lesion. Gallium-68 DOTA-Exendin-4 PET/CT acquisition was performed. A single intense 2 cm hyperperfused pancreatic lesion was located anteriorly in the head of the pancreas. Earlier targeted PET/CT imaging and recognition of significant neuropsychiatric symptoms attributable to the patient’s hypoglycemic state might have accelerated the resolution of her condition and obviated the need for unnecessary testing.

Insects’ growth and development are highly dependent on energy supply, with sugar metabolism playing a pivotal role in maintaining homeostasis and regulating physiological processes. The present study investigated the effects of exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, on the growth, development, glycolysis, and energy metabolism of fourth-instar larvae of the fall webworm, Hyphantria cunea. We determined the impact of exendin-4 on larval growth and nutritional indices, analyzed the responses of glycolytic and metabolic pathways, and revealed the underlying regulatory mechanisms. Exendin-4 treatment significantly decreased growth and nutritional indices, influenced the activity of digestive enzymes, and induced changes in metabolite profiles, particularly affecting energy substance metabolism. We observed an increase in the glycogen content and a decrease in glucose and trehalose levels in the hemolymph, suggesting a regulatory effect on blood sugar homeostasis. Furthermore, exendin-4 promoted glycolysis by enhancing the activities and expressions of key glycolytic enzymes, leading to an increase in pyruvate production. This was accompanied by a reduction in ATP levels and the activation of AMP-activated protein kinase (AMPK), which may underlie the growth arrest in larvae. Our findings provide novel insights into the effects of exendin-4 on insect responses from an energy metabolism perspective and may contribute to the development of GLP-1R agonists for pest management.

Tight control of beta cell stimulus-secretion coupling is crucial for maintaining homeostasis of energy-rich nutrients. While glucose serves as a primary regulator of this process, incretins augment beta cell function, partly by enhancing cytosolic [Ca2+] dynamics. However, the details of how precisely they affect beta cell recruitment during activation, their active time, and functional connectivity during plateau activity, and how they influence beta cell deactivation remain to be described. Performing functional multicellular Ca2+ imaging in acute mouse pancreas tissue slices enabled us to systematically assess the effects of the GLP-1 receptor agonist exendin-4 (Ex-4) simultaneously in many coupled beta cells with high resolution. In otherwise substimulatory glucose, Ex-4 was able to recruit approximately a quarter of beta cells into an active state. Costimulation with Ex-4 and stimulatory glucose shortened the activation delays and accelerated beta cell activation dynamics. More specifically, active time increased faster, and the time required to reach half-maximal activation was effectively halved in the presence of Ex-4. Moreover, the active time and regularity of [Ca2+]IC oscillations increased, especially during the first part of beta cell response. In contrast, subsequent addition of Ex-4 to already active cells did not significantly enhance beta cell activity. Network analyses further confirmed increased connectivity during activation and activity in the presence of Ex-4, with hub cell roles remaining rather stable in both control experiments and experiments with Ex-4. Interestingly, Ex-4 demonstrated a biphasic effect on deactivation, slightly prolonging beta cell activity at physiological concentrations and shortening deactivation delays at supraphysiological concentrations. In sum, costimulation by Ex-4 and glucose increases [Ca2+]IC during beta cell activation and activity, indicating that the effect of incretins may, to an important extent, be explained by enhanced [Ca2+]IC signals. During deactivation, previous incretin stimulation does not critically prolong cellular activity, which corroborates their low risk of hypoglycemia.

Objective To investigate the effect of Exendin-4 on the survival of autologous free fat transplantation. Methods According to the different reagents added, rabbits were randomly divided into three groups: control group (normal saline group), experimental group A (10 nmol/L Exendin-4) or experimental group B (20 nmol/L Exendin-4), and the back autologous fat transplantation model was established. At 2, 4 and 12 weeks after operation, the grafts were sampled, the general survival of the grafts was observed, and the mass and volume of the grafts were measured by balance and drainage method. After that, HE staining was performed to observe tissue fibrosis, inflammatory infiltration and cell integrity. The angiogenesis of the grafts was observed by CD31 immunohistochemical staining. Results The weight and volume of fat grafts in the experimental group were significantly higher than those in the control group (P<0.05). At different time points, compared with the control group, the experimental group had less fibrous connective tissue, less inflammatory cell infiltration and less vacuole (P<0.05). With the continuous extension of the experiment time, the vascular density of the grafts in all groups increased. Both experimental group A and experimental group B had better angiogenesis than control group at each time point (P<0.05). Compared with experimental group A, experimental group B had better graft volume retention, better adipocyte integrity, and better angiogenesis. Conclu原 sion Exendin-4 can improve the survival rate of fat grafts by reducing the inflammatory infiltration of transplanted fat tissue, reducing the degree of fibrosis, reducing the formation of vesicles and promoting graft angiogenesis. [ABSTRACT FROM AUTHOR]

Our previous studies showed that microinjection into the median eminence of the sheep of glucagon-like peptide-1 (GLP-1) or its receptor agonist exendin-4 stimulates luteinising hormone (LH) secretion, but it is unknown whether the same effec t may be obtained by systemic administration of the same. The present study measured the response in terms of plasma LH concentrations to intravenous (iv) infusion of exendin-4. A preliminary study showed that infusion of 2 mg exendin-4 into ewes produced a greater LH response in the follicular phase of the oestrous cycle than the luteal phase. Accordingly, the main study monitored plasma LH levels in response to either 0.5 mg or 2 mg exendin-4 or vehicle (normal saline) delivered by jugular infusion for 1 h in the follicular phase of the oestrous cycle. Blood samples were collected at 10 min intervals before, during and after infusion. Both doses of exendin-4 increased mean plasma LH concentrations and increased LH peripheral pulse amplitude. There was no effect on inter-pulse interval or timing of the preovulatory LH surge. These doses of exendin-4 did not alter plasma insulin or glucose concentrations. Quantitative PCR of the gastrointestinal tract samples from a population of ewes confirmed the expression of the prepro glucagon gene (GCG). Expression increased aborally and was greatest in the rectum. It is concluded that endogenous GLP-1, most likely derived from the hindgut, may act systemically to stimulate LH secretion. The present data suggest that this effec t may be obtained with levels of agonist that are lower than those functioning as an incretin. [ABSTRACT FROM AUTHOR]

Background: Insulinomas are the most common functioning pancreatic neuroendocrine neoplasms, and these tumors induce hypoglycemia due to hyperinsulinemia. Hypoglycemia caused by insulinomas can cause seizures, coma or death due to the delayed diagnosis. The only curative treatment is surgical resection. To perform curative surgical resection of insulinomas, preoperative localization is crucial. However, localization of insulinomas is often challenging using conventional imaging methods such as computed tomography (CT) and magnetic resonance imaging. Although endoscopic ultrasound (EUS) fine-needle aspiration and selective arterial calcium stimulation test, which can reflect the endocrine character of the tumor, are performed in such cases, these modalities are invasive and require operatordependent techniques. Additionally, somatostatin receptor (SSTR)-targeted imaging has a relatively low sensitivity for detecting insulinomas due to its low SSTR type 2 expression. Thus, there is an urgent need for developing a noninvasive diagnostic technique which is specific for detecting insulinomas. Consequently, glucagon-like peptide-1 receptor-targeted imaging has recently emerged and gained a wide interest. Recently, we have developed a novel 18Flabeled exendin-4-based probe conjugated with polyethylene glycol, [18F]FB (ePEG12)12-exendin-4 (18F-exendin-4), for positron emission tomography (PET) imaging. Here we report a case of insulinoma in which 18F-exendin-4 PET/CT noninvasively provided critical information for localization. Case description: This is a case of a 58-year-old male with symptomatic hypoglycemia for 10 years; however, a preoperative diagnosis of insulinoma was not established due to the difficulty in differentiating it from an accessory spleen using conventional imaging. Moreover, the patient requested to avoid invasive diagnostic procedures including EUS. 18F-exendin-4 PET/CT revealed significant uptakes in the pancreatic tail whereas no apparent uptakes were observed in the spleen; thus, curative laparoscopic enucleation of the pancreatic tail was performed. The diagnosis of insulinoma was confirmed via histopathological examination. This is the first case report of insulinoma diagnosed using 18F-exendin-4 PET/CT. Conclusion: In this case, PET information led to curative resection through enucleation of the pancreas. 18F-exendin-4 PET/CT may serve as a useful noninvasive clinical tool for insulinoma localization. [ABSTRACT FROM AUTHOR]

Background: Peptidic radiotracers are preferentially excreted through the kidneys, which often results in high persistent renal retention of radioactivity, limiting or even preventing therapeutic clinical translation of these radiotracers. Exendin-4, which targets the glucagon-like-peptide 1 receptor (GLP-1R) overexpressed in insulinomas and in congenital hyperinsulinism, is an example thereof. The use of the tripeptide MVK, which is readily cleaved between methionine and valine by neprilysin at the renal brush border membrane, already showed promising results in reducing kidney uptake as reported in the literature. Based on our previous findings we were interested how linker variants with multiple copies of the MV-motive influence renal washout of radiolabelled exendin-4. Results: Three exendin-4 derivatives, carrying either one MVK, a MV-MVK or a MVK-MVK linker were synthesized and compared to a reference compound lacking a cleavable linker. In vivo results of a biodistribution in GLP-1R overexpressing tumour bearing mice at 24 h post-injection demonstrated a significant reduction (at least 57%) of renal retention of all 111In-labeled exendin-4 compounds equipped with a cleavable linker compared to the reference compound. While the insertion of the single linker MVK led to a reduction in kidney uptake of 70%, the dual approach with the linker MV-MVK slightly, but not significantly enhanced this effect, with 77% reduction in kidney uptake compared to the reference. In vitro IC50 and cell uptake studies were conducted and demonstrated that though the cleavable linkers negatively influenced the affinity towards the GLP-1R, cell uptake remained largely unaffected, except for the MV-MVK cleavable linker conjugate, which displayed lower cell uptake than the other compounds. Importantly, the tumour uptake in the biodistribution study was not significantly affected with 2.9, 2.5, 3.2 and 1.5% iA/g for radiolabelled Ex4, MVK-Ex4, MV-MVK-Ex4 and MVK-MVK-Ex4, respectively. Conclusion: Cleavable linkers are highly efficient in reducing the radioactivity burden in the kidney. Though the dual linker approach using the instillation of MV-MVK or MVK-MVK between exendin-4 and the radiometal chelator did not significantly outperform the single cleavable linker MVK, further structural optimization or the combination of different cleavable linkers could be a stepping stone in reducing radiation-induced nephrotoxicity. [ABSTRACT FROM AUTHOR]

Nausea, the unpleasant sensation of visceral malaise, remains a mysterious process. The area postrema is implicated in some nausea responses and is anatomically privileged to detect blood-borne signals. To investigate nausea mechanisms, we built an area postrema cell atlas through single-nucleus RNA sequencing, revealing a few neuron types. Using mouse genetic tools for cell-specific manipulation, we discovered excitatory neurons that induce nausea-related behaviors, with one neuron type mediating aversion imposed by multiple poisons. Nausea-associated responses to agonists of identified area postrema receptors were observed and suppressed by targeted cell ablation and/or gene knockout. Anatomical mapping revealed a distributed network of long-range excitatory but not inhibitory projections with subtype-specific patterning. These studies reveal the basic organization of area postrema nausea circuitry and provide a framework toward understanding and therapeutically controlling nausea.

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases. Recent data highlight similarities between neurodegenerative diseases, including PD and type 2 diabetes mellitus (T2DM), suggesting a crucial interplay between the gut–brain axis. Glucagon-like peptide-1 receptor (GLP-1R) agonists, known for their use in T2DM treatment, are currently extensively studied as novel PD modifying agents. For this narrative review article, we searched PubMed and Scopus databases for peer-reviewed research, review articles and clinical trials regarding GLP-1R agonists and PD published in the English language with no time restrictions. We also screened the references of the selected articles for possible additional articles in order to include most of the key recent evidence. Many data on animal models and preclinical studies show that GLP1-R agonists can restore dopamine levels, inhibit dopaminergic loss, attenuate neuronal degeneration and alleviate motor and non-motor features of PD. Evidence from clinical studies is also very promising, enhancing the possibility of adding GLP1-R agonists to the current armamentarium of drugs available for PD treatment.

BackgroundInsulinomas are the most common functioning pancreatic neuroendocrine neoplasms, and these tumors induce hypoglycemia due to hyperinsulinemia. Hypoglycemia caused by insulinomas can cause seizures, coma or death due to the delayed diagnosis. The only curative treatment is surgical resection. To perform curative surgical resection of insulinomas, preoperative localization is crucial. However, localization of insulinomas is often challenging using conventional imaging methods such as computed tomography (CT) and magnetic resonance imaging. Although endoscopic ultrasound (EUS) fine-needle aspiration and selective arterial calcium stimulation test, which can reflect the endocrine character of the tumor, are performed in such cases, these modalities are invasive and require operator-dependent techniques. Additionally, somatostatin receptor (SSTR)-targeted imaging has a relatively low sensitivity for detecting insulinomas due to its low SSTR type 2 expression. Thus, there is an urgent need for developing a noninvasive diagnostic technique which is specific for detecting insulinomas. Consequently, glucagon-like peptide-1 receptor-targeted imaging has recently emerged and gained a wide interest. Recently, we have developed a novel 18F-labeled exendin-4-based probe conjugated with polyethylene glycol, [18F]FB(ePEG12)12-exendin-4 (18F-exendin-4), for positron emission tomography (PET) imaging. Here we report a case of insulinoma in which 18F-exendin-4 PET/CT noninvasively provided critical information for localization.Case descriptionThis is a case of a 58-year-old male with symptomatic hypoglycemia for 10 years; however, a preoperative diagnosis of insulinoma was not established due to the difficulty in differentiating it from an accessory spleen using conventional imaging. Moreover, the patient requested to avoid invasive diagnostic procedures including EUS. 18F-exendin-4 PET/CT revealed significant uptakes in the pancreatic tail whereas no apparent uptakes were observed in the spleen; thus, curative laparoscopic enucleation of the pancreatic tail was performed. The diagnosis of insulinoma was confirmed via histopathological examination. This is the first case report of insulinoma diagnosed using 18F-exendin-4 PET/CT.ConclusionIn this case, PET information led to curative resection through enucleation of the pancreas. 18F-exendin-4 PET/CT may serve as a useful noninvasive clinical tool for insulinoma localization.

Excess hepatic lipid accumulation is the hallmark of non-alcoholic fatty liver disease (NAFLD), for which no medication is currently approved. However, glucagon-like peptide-1 receptor agonists (GLP-1RAs), already approved for treating type 2 diabetes, have lately emerged as possible treatments. Herein we aim to investigate how the GLP-1RA exendin-4 (Ex-4) affects the microRNA (miRNAs) expression profile using an in vitro model of steatosis. Total RNA, including miRNAs, was isolated from control, steatotic, and Ex-4-treated steatotic cells and used for probing a panel of 799 highly curated miRNAs using NanoString technology. Enrichment pathway analysis was used to find the signaling pathways and cellular functions associated with the differentially expressed miRNAs. Our data shows that Ex-4 reversed the expression of a set of miRNAs. Functional enrichment analysis highlighted many relevant signaling pathways and cellular functions enriched in the differentially expressed miRNAs, including hepatic fibrosis, insulin receptor, PPAR, Wnt/β-Catenin, VEGF, and mTOR receptor signaling pathways, fibrosis of the liver, cirrhosis of the liver, proliferation of hepatic stellate cells, diabetes mellitus, glucose metabolism disorder and proliferation of liver cells. Our findings suggest that miRNAs may play essential roles in the processes driving steatosis reduction in response to GLP-1R agonists, which warrants further functional investigation. [ABSTRACT FROM AUTHOR]

Objective: To disuss the effect of glucagon like peptide-1 receptor (GLP-1R) agonist Exendin-4 (E4) on injury of cardiomyocytes in the hyperglycemia and hyperlipidemia (HGHL) environment, and to clarify its related mechanism. Methods: The H9C2 cardiomyocytes of the rats were divided into control group, HGHL group, HGHL+E4 group, HGHL+E4+iron death agonist (Erastin) group. The HGHL model of the H9C2 cells was induced by 33 mmol·L-1 glucose and 500 μmol·L-1 palmitate, and the cells in HGHL+E4 group and HGHL+E4+Erastin group were treated with 100 nmol·L-1 E4 and 5 μmol·L-1 Erastin. CCK-8 assay was used to detect the survival rates of cells in various groups; Hoechst 33258 fluorescence staining was used to observe the apoptosis of cells in various groups; flow cytometry was used to detected the apoptotic rates of cells in various groups; 2', 7'-dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence probe was used to detect the levels of reactive oxygen species (ROS) in the cells in various groups; the corresponding kit was used to detect the levels of glutathione (GSH) and malondialdehyde (MDA) in cells in various groups; JC-1 staining was used to detect the mitochondrial membrane potential (MMP) in cells in various groups; FerroOrange fluorescence probe was used to detect the levels of Fe2+ in the cells in various groups; Western blotting method was used to detect the expression levels of glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) in the cells in various groups. Results: Compared with control group, the survival rate of cells in HGHL group was decreased (P<0. 05), and the cells were fragmented and collapsed, which showed apoptotic morphology; the apoptotic rate and the levels of ROS and MDA in the cells were increased (P<0. 05), the levels of GSH and MMP were decreased (P<0. 05), the level of Fe2+ was increased (P<0. 05), and the expression levels of GPX4 and SLC7A11 proteins were decreased (P<0. 05). Compared with HGHL group, the survival rate of the cells in HGHL+E4 group was increased (P<0. 05), and the apoptosis was decreased; the apoptotic rate and the levels of ROS and MDA were decreased (P<0. 05), while the levels of GSH and MMP were increased (P<0. 05), the level of Fe2+ was decreased (P<0. 05), and the expression levels of GPX4 and SLC7A11 proteins were decreased (P<0. 05). Compared with HGHL+E4 group, the survival rate of the cells in HGHL+E4+Erastin group was decreased (P<0. 05), the cell fragmentation and wrinkling were obviously decreased, the apoptotic rate and the levels of ROS and MDA were increased (P<0. 05), the levels of GSH and MMP were decreased (P<0. 05), the level of Fe2+ was increased (P<0. 05), and the expression levels of GPX4 and SLC7A11 proteins were decreased (P< 0. 05). Conclusion: GLP-1R agonists can reduce the cardiomyocyte injury in the HGHL environment, and the protective effect may be related to inhibiting the iron death. [ABSTRACT FROM AUTHOR]

The updating and optimization of drug delivery systems is critical for better in vivo behaviors of drugs, as well as for improving impaired implant osseointegration in diabetes. Numerous studies have reported the benefits of exendin-4 on diabetic bone, with the potential to enhance osseointegration in diabetes. To construct an appropriate sustained-release system of exendin-4 targeting implant osseointegration in diabetes, this study fabricated exendin-4-loaded microspheres using poly(lactic-co-glycolic acid) (PLGA) and chitosan. The morphology, size, encapsulation efficiency, and drug release behavior of microspheres were investigated. The bioactivity of drug-loaded microspheres on cell proliferation and osteogenic differentiation of diabetic BMSCs was investigated to examine the pharmacologic action of exendin-4 loaded into chitosan–PLGA microspheres. Further, the influence of microspheres on osseointegration was evaluated using type 2 diabetes mellitus (T2DM) rat implant model. After 4 weeks, the samples were evaluated by radiological and histological analysis. The results of in vitro experiments showed that the prepared exendin-4-loaded chitosan–PLGA microspheres have good properties as a drug delivery system, and the chitosan could improve the encapsulation efficiency and drug release of PLGA microspheres. In addition, exendin-4-loaded microspheres could enhance the proliferation and osteogenic differentiation of diabetic BMSCs. The results of in vivo experiments showed the exendin-4-loaded microspheres significantly improved the impaired osseointegration and bone formation around implants in T2DM rats without affecting blood glucose levels. Thus, the local application of exendin-4-loaded chitosan–PLGA microspheres might be a promising therapeutic strategy for improving the efficacy of dental implants in T2DM individuals.

Abstract Background Central nervous system (CNS) control of metabolism plays a pivotal role in maintaining energy balance. In the brain, Glucagon-like peptide 1 (GLP-1), encoded by the proglucagon ‘Gcg’ gene, produced in a distinct population of neurons in the nucleus tractus solitarius (NTS), has been shown to regulate feeding behavior leading to the suppression of appetite. However, neuronal networks that mediate endogenous GLP-1 action in the CNS on feeding and energy balance are not well understood. Results We analyzed the distribution of GLP-1R-expressing neurons and axonal projections of NTS GLP-1-producing neurons in the mouse brain. GLP-1R neurons were found to be broadly distributed in the brain and specific forebrain regions, particularly the hypothalamus, including the arcuate nucleus of the hypothalamus (ARC), a brain region known to regulate energy homeostasis and feeding behavior, that receives dense NTSGcg neuronal projections. The impact of GLP-1 signaling in the ARC GLP-1R-expressing neurons and the impact of activation of ARC GLP-1R on food intake was examined. Application of GLP-1R specific agonist Exendin-4 (Exn-4) enhanced a proportion of the ARC GLP-1R-expressing neurons and pro-opiomelanocortin (POMC) neuronal action potential firing rates. Chemogenetic activation of the ARC GLP-1R neurons by using Cre-dependent hM3Dq AAV in the GLP-1R-ires-Cre mice, established that acute activation of the ARC GLP-1R neurons significantly suppressed food intake but did not have a strong impact on glucose homeostasis. Conclusions These results highlight the importance of central GLP-1 signaling in the ARC that express GLP-1R that upon activation, regulate feeding behavior.

Background: Insulinomas are the most common neuroendocrine neoplasms of the pancreas. Diagnosis is made through patient clinical presentation with hypoglycemia symptoms and imaging, such as EUS, CT, MRI, and functional imaging. Exendin-4 PET/CT (and SPECT/CT) is a new prominent radiotracer developed to image insulinomas. The aim of the study is to evaluate whether exendin-4 imaging is a useful tool in imaging for insulinoma patients when other imaging methods do not reach them. Methods: MEDLINE research conducted on PubMed, Scopus, and Web of Science gathered a total of 501 papers. Studies that evaluated exendin-4 SPECT and PET in insulinoma patients were screened and assessed through QUADAS-2 for risk of bias and applicability concerns' assessment. Sensitivity, specificity, and accuracy were reported when available. Results: A total of 13 studies were deemed eligible for a QUADAS 2 review. Studies included ranged from 2009 to 2022. The most-used tracer was 68Ga-DOTA-exendin-4 in PET and 111In-DTPA-exendin-4 in SPECT. Exendin-4 labeled with 99mTc was also reported. The QUADAS-2 risk of bias assessment was overall low, with some unclear reports in the reference and index domains. Only two domains were at high risk of bias because of an explicated non-blind imaging review. Applicability concerns for bias were low in all domains. Reported sensitivities ranged from 95% to 100% and specificities from 20% to 100%. Conclusions: exendin-4 imaging is a sensitive functional imaging tracer in both SPECT and PET applications, especially in suspicion of benign insulinomas located where endoscopic ultrasound cannot reach, being more sensitive than morfostructural imaging. [ABSTRACT FROM AUTHOR]

Background: Diabetes mellitus (DM) is a metabolic disease, characterized by hyperglycemia resulting from defects in insulin secretion and/or insulin action. The current study was designed to assess the therapeutic potential of bone marrow-derived mesenchymal stem cells (BM-MSCs) alone and in combination with pioglitazone (Pz) or exendin-4 (Ex) in high-fat diet/streptozotocin (HFD/STZ)-induced diabetes in rats. Methods: The rats were subjected to the HFD for three weeks before being injected with a single low dosage of STZ (35 mg/kg bw). The animals were assigned to different treatment groups after type II diabetes mellitus (T2DM) induction was confirmed. Results: Severe insulin resistance was verified in untreated HFD/STZ T2DM rats, along with the exaggeration of oxidative stress, inflammation, apoptosis, and autophagy suppression in the adipose tissues. Monotherapy of HFD/T2DM rats with BM-MSCs and Pz or Ex alleviated diabetic complications by increasing insulin sensitivity, decreasing apoptosis and inflammation as evidenced by a decrease in serum tumor necrosis factor-alpha, caspase-3, and nuclear factor-kappa B (NF-ĸB) genes expression and Janus kinase (JNK) protein expression, and enhancing autophagy as revealed by upregulation in beclin and LC3, as well as peroxisome proliferator-activated receptor-ĸ coactivator-1 alpha (PGC-1α) genes expression in the adipose tissues. An augmented ameliorative efficacy was recorded in combined treatments. The biochemical and molecular results were confirmed by histological investigation of pancreatic tissues. Conclusions: Combining Pz or Ex with BM-MSCs is a synergistic therapeutic option that reduces insulin resistance and subsequent complications in T2DM via multiple molecular mechanisms. [ABSTRACT FROM AUTHOR]

IntroductionIslet xenotransplantation may be a therapeutic option in type 1 diabetes. Recent advances in generating genetically modified source pigs offer advantages as immune suppressants can potentially be eliminated after the transplantation. Therapy monitoring would greatly benefit from noninvasive methods for assessing the viability of transplanted islets. Peptide-based positron emission tomography (PET) targeting the glucagon-like peptide-1 receptor (GLP1R) expression on beta cells may offer a procedure that can directly be translated from an experimental setting to the clinic. The aim of this study was to establish the labeling of the GLP1R ligand [68Ga]Ga-exendin-4, to demonstrate the feasibility of imaging porcine islet xenografts in vivo and to compare signal quality for three different transplantation sites in a mouse model.Materials and methodsMice with engrafted neonatal porcine islet cell clusters (NPICCs) under the kidney capsule, into the inguinal fold, or the lower hindlimb muscle were studied. After reaching normoglycemia, the mice were injected with [68Ga]Ga-exendin-4 for PET data acquisition. Subsequent autoradiography (AR) was used for comparing ex vivo data with in vivo uptake.ResultsNPICCs in the lower right hindlimb muscle could be detected in vivo and in AR. Due to the high background in the kidney and urinary bladder, islets could not be detected in the PET data at transplantation sites close to these organs, while AR showed a clear signal for the islets in the inguinal fold.DiscussionPET with [68Ga]Ga-exendin-4 detects islets transplanted in the hindlimb muscle tissue of mice, offering the potential of longitudinal monitoring of viable porcine islets. Other sites are not suitable for in vivo imaging owing to high activity accumulation of Exendin-4 in kidney and bladder.

Objective: To observe the effects of Exendin-4, a glucagon-like peptide-1(GLP-1) receptor agonist, on proliferation and osteogenic differentiation of Mc3t3-E1(mouse embryonic osteoblast precursor cells) in vitro. Methods: Mc3t3-E1 cells were treated with Exendin-4 at a pre-experimental concentration of 30 nmol/L for 72 h. The cells were collected for sequencing, and the RNA-SEQ data were obtained. The differentially expressed genes greater than 2 times were screened and KEGG PATHWAY enrichment analysis and GO enrichment analysis were performed. Results: Mc3t3-E1 cells were proliferated after Exendin-4 treatment, and a total of 418 differentially expressed genes were screened, including 236 up-regulated genes and 182 down-regulated genes. GO enrichment analysis showed that the up-regulated differentially expressed genes were mainly enriched in the immune system, cellular adhesion and proteolytic pathways. KEGG PATHWAY enrichment analysis showed that The down-regulated differentially expressed genes were mainly enriched in PI3K-Akt signaling pathway, abnormal transcription in cancer, mammalian target of Rapamycin (mTOR) receptor signaling pathway, and hypoxia inducible factor 1 (HYPO xia inducible) Factor-1, HIF-1) signaling pathway. It revealed that up-regulated genes related to osteoporosis included Fosl1, Cxcl13, Clec11a, Phex, Fasl, Camk4, Stab1, Zbp1, Adora2a, Igfbp7, Cxcr2, Hp, MTI; while for Down-regulated genes included Nog, Zeb1, Esr1, Igf2bp2, Plxnb3, Rgs14. Conclusions: Exendin-4 can affect the differentiation of precursor cells into osteoblasts by influencing the expression levels of gene related to cell immunity, cell adhesion and proteolysis related genes, and ultimately affect the formation and development of osteoporosis.

Diabetes mellitus (DM) increases the destruction of periodontal tissue and impairs osteogenesis differentiation. Exendin-4 (Ex-4), a glucagon-like peptide-1 (GLP-1) analogue, can be used for treating DM and promotes bone regeneration. The aim of this study was to explore the effect and mechanism of Ex-4 on improving the osteogenesis of periodontal ligament stem cells (PDLSCs) in a high glucose environment. Alkaline phosphatase staining and alizarin red staining were used to detect the osteogenic differentiation of PDLSCs. The results showed that 10 nM Ex-4 could reduce the osteogenesis inhibition of PDLSCs induced by high glucose. RT-PCR and western blot results showed that Ex-4 increased the osteogenesis-related gene expression of ALP, Runx2, and Osx, and upregulated the phosphorylation of P38, JNK, and ERK1/2; the peak effect was observed in the range 0.5–1.0 h. Mitogen-activated protein kinase (MAPK) inhibitors PD98059, SB203580, and SP600125 blocked the effects of Ex-4 on MAPK activation and decreased the expression of ALP, Runx2, and Osx in PDLSCs. Moreover, after Ex-4 treatment, the total βcatenin, p-GSK3β, LEF, and Runx2 protein levels increased under normal or high glucose environments. In conclusion, our results indicated that Ex-4 regulates the MAPK and WNT signaling pathways to alleviate the osteogenic inhibition of PDLSCs in a high glucose environment. [ABSTRACT FROM AUTHOR]

Triple-negative breast cancer (TNBC) cell line MDA-MB-231 is known for Warburg metabolism and defects in mitochondria. On the other hand, dipeptidyl peptidase-IV (DPP-IV) inhibitors such as sitagliptin and vildagliptin and GLP-1 agonist exendin-4 are known to improve mitochondrial functions as well as biogenesis, but no study has evaluated the influence of these drugs on mitochondrial biogenesis on metastatic breast cancer cell line. We have recently reported anticancer effects of 5-aminoimidazole-4-carboxamide riboside on MDA-MB-231 cells via activation of AMP-dependent kinase (AMPK), which activates the downstream transcription factors PGC-1α,PGC-1β, or FOXO1 for mitochondrial biogenesis; above-mentioned incretin-based therapies are also known to activate AMPK. This study evaluated the effects of sitagliptin, vildagliptin, and exendin-4 on MDA-MB-231 cells and the underlying changes in mitochondrial biogenesis, were examined. Treatment with sitagliptin (100 µM), vildagliptin (100 µM), and exendin-4 (10 nM) for 72 h to MDA-MB-231 cells led to a decrease in viability indicated by MTT assay, cell migration by scratch, and transwell migration assays, accompanied with marginal reduction in cell numbers along with the apoptotic appearance, the rate of apoptosis, and decreased lactate content in conditioned medium. These changes in the cancer phenotype were accompanied by an increase in the mitochondrial DNA to nuclear DNA ratio, increased MitoTracker green and red staining, and increased expression of transcription factors PGC-1α, NRF-1, NRF-2, TFAM, and HO-1. Pre-treatment of cells with these incretin-based drugs followed by 48 h treatment with 1 µM doxorubicin increased doxorubicin sensitivity as observed by a decrease in viability by MTT assay. Thus, sitagliptin, vildagliptin, and exendin-4 exert their beneficial effects on TNBC cells via an increase in mitochondrial biogenesis that helps to switch Warburg metabolism into anti-Warburg effect. Therapeutic response was in the order of: sitagliptin > vildagliptin > exendin-4. [ABSTRACT FROM AUTHOR]

Type 2 diabetes mellitus (T2DM) is a chronic metabolic abnormality leading to microvascular and macrovascular complications. Non-insulin Incretin mimic synthetic peptide exendin-4 was introduced as an anti-diabetic drug which helped diabetic patients with triggering insulin secretion; further researches have revealed an effective role of exendin-4 in treatment of T2DM related diseases. Exendin-4 is approximately similar to Glucagon-like peptide, thus it can bind to the glucagon-like peptide-1 receptor (GLP-1R) and activated different signaling pathways that are involved in various bioactivities such as apoptosis, insulin secretion and inactivation of microglial. In this review, we investigated the interesting role of exendin-4 in various kinds of T2DM related disorders through the activation of different signaling pathways.

• Exendin-4 intervention led to a significant reduction in aortic plaques and body weight in ApoE-/- mice compared to the model group. • Exendin-4 significantly increased the proportion of myeloid-derived suppressor cells (MDSCs) in bone marrow and peripheral blood, while reducing pro-inflammatory cytokines (TNF-α, IFN-γ, IL-6) and increasing anti-inflammatory cytokines (TGF-β, IL-10) in both spleen and plasma. • Exendin-4 regulated lipid levels by decreasing triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C), while increasing high-density lipoprotein cholesterol (HDL-C) in ApoE-/- mice. To investigate the impact of the glucagon-like peptide-1 (GLP-1) receptor agonist Exendin-4 on the proportion of myeloid-derived suppressor cells (MDSCs) in male ApoE-/- mice, and investigate alterations in the concentrations of inflammatory factors in plasma and spleen tissues and assess their correlation with MDSCs. Thirty male ApoE-/- mice were randomly divided into five groups (n = 6 per group): control group (CON), model group (MOD), Exendin-4 intervention group (MOD/Ex-4), Exendin-9-39 intervention group (MOD/Ex-9-39), and Exendin-4 + Exendin-9-39 combined intervention group (MOD/Ex-4 + Ex-9-39). After 4 weeks of drug intervention, changes in aortic plaque were observed using Oil Red O staining and H&E staining. Flow cytometry was employed to detect the content of myeloid-derived suppressor cells (MDSCs) in bone marrow and peripheral blood. ELISA was utilized to measure the concentrations of inflammatory factors in mouse peripheral blood plasma, while RT-qPCR was employed to quantify the expression levels of inflammatory factors in the spleen. Pearson correlation analysis was conducted to assess the relationship between MDSCs and inflammatory factors. Mice in the MOD group had significantly higher body weight compared to the CON group, with a statistically significant difference (P<0.05). Following Exendin-4 intervention, body weight was reduced compared to the MOD group (P<0.05). Additionally, Exendin-4 treatment led to a significant reduction in atherosclerotic plaque compared to the MOD group (P<0.001). After Exendin-4 intervention, the proportion of MDSCs in the bone marrow was higher than in the MOD group (P<0.001), and the proportion of MDSCs in peripheral blood was significantly higher than in the MOD group (P<0.05). Further investigation revealed that Exendin-4 could regulate lipid levels in mice, decreasing concentrations of TG (P<0.01), TC (P<0.0001), and LDL-C (P<0.0001), while increasing HDL-C concentrations (P<0.01). Moreover, after Exendin-4 treatment, the level of the cytokine IL-6 in peripheral plasma was significantly lower compared to the MOD group (P<0.0001), while levels of IL-10 and TGF-β were significantly higher compared to the MOD group (P<0.0001). In the spleen, levels of the cytokines IL-10 (P<0.0001) and TGF-β (P<0.001) were significantly increased compared to the MOD group. Pearson correlation analysis showed that the proportion of MDSCs in peripheral blood was positively correlated with IL-10 and TGF-β levels in both the spleen and peripheral blood. Additionally, the proportion of MDSCs in the bone marrow was positively correlated with IL-10 and TGF-β levels in the spleen and peripheral blood. Exendin-4 alleviates the severity of atherosclerosis. This process may be achieved by promoting the secretion of myeloid-derived suppressor cells (MDSCs) in the bone marrow and peripheral blood of atherosclerotic ApoE-/- mice, regulating the ratio of inflammatory factors in the body, reducing mouse body weight, and lowering blood lipids. [ABSTRACT FROM AUTHOR]

Epilepsy is a prevalent disorder of the central nervous system. Approximately, one-third of patients show resistance to pharmacological interventions. The pathogenesis of epilepsy is complex, and neuronal apoptosis plays a critical role. Aberrantly reactive astrocytes, induced by cytokine release from activated microglia, may lead to neuronal apoptosis. This study investigated the role of glucagon-like peptide 1 receptor (GLP1R) in microglial activation in epilepsy and its impact on astrocyte-mediated neurotoxicity. We used human hippocampal tissue from patients with temporal lobe epilepsy and a pilocarpine-induced epileptic mouse model to assess neurobiological changes in epilepsy. BV2 microglial cells and primary astrocytes were used to evaluate cytokine release and astrocyte activation in vitro. The involvement of GLP1R was explored using the GLP1R agonist, Exendin-4 (Ex-4). Our findings indicated that reduced GLP1R expression in hippocampal microglia in both epileptic mouse models and human patients, correlated with increased cytokine release and astrocyte activation. Ex-4 treatment restored microglial homeostasis, decreased cytokine secretion, and reduced astrocyte activation, particularly of the A1 phenotype. These changes were associated with a reduction in neuronal apoptosis. In addition, Ex-4 treatment significantly decreased the frequency and duration of seizures in epileptic mice. This study highlights the crucial role of microglial GLP1R in epilepsy pathophysiology. GLP1R downregulation contributes to microglial- and astrocyte-mediated neurotoxicity, exacerbating neuronal death and seizures. Activation of GLP1R with Ex-4 has emerged as a promising therapeutic strategy to reduce neuroinflammation, protect neuronal cells, and control seizures in epilepsy. This study provides a foundation for developing novel antiepileptic therapies targeting microglial GLP1R, with the potential to improve outcomes in patients with epilepsy. GLP1R activation by Exendin-4 is a novel therapeutic approach to attenuate neuroinflammation, prevent neuronal loss in epilepsy, and reduce seizure frequency and severity. [Display omitted] [ABSTRACT FROM AUTHOR]

GLP-1 (Glucagon-like peptide-1) is a peptide that stimulates insulin secretion from the β-cell for glycemic control of the plasma blood glucose level. Its mimetic exenatide (synthetic Exendin-4) with a longer half-life of approximately 3.3–4 h is widely used in clinical application to treat diabetes. Currently, exenatide is chemically synthesized. In this study, we report that the GLP-1 analogue recombinant Exendin-4 (Exdn-4) can be produced at a high level in Nicotiana benthamiana, with an estimated yield of 50.0 µg/g fresh biomass. For high-level expression, we generated a recombinant gene, B:GB1:ddCBD1m:8xHis : Exendin-4 (BGC : Exdn-4), for the production of Exendin-4 using various domains such as the BiP signal peptide, the GB1 domain (B1 domain of streptococcal G protein), a double cellulose binding domain 1 (CBD1), and 8 His residues (8xHis) to the N-terminus of Exendin-4. GB1 was used to increase the expression, whereas double CBD1 and 8xHis were included as affinity tags for easy purification using MCC beads and Ni2+-NTA resin, respectively. BGC : Exdn-4 was purified by single-step purification to near homogeneity using both Ni2+-NTA resin and microcrystalline cellulose (MCC) beads. Moreover, Exdn-4 without any extra residues was produced from BGC : Exdn-4 bound onto MCC beads by treating with enterokinase. Plant-produced Exdn-4 (Exendin-4) was as effective as chemically synthesized Exendin-4 in glucose-induced insulin secretion (GIIS) from mouse MIN6m9 cells a pancreatic beta cell line.

Background: Central nervous system (CNS) control of metabolism plays a pivotal role in maintaining energy balance. In the brain, Glucagon-like peptide 1 (GLP-1), encoded by the proglucagon 'Gcg' gene, produced in a distinct population of neurons in the nucleus tractus solitarius (NTS), has been shown to regulate feeding behavior leading to the suppression of appetite. However, neuronal networks that mediate endogenous GLP-1 action in the CNS on feeding and energy balance are not well understood. Results: We analyzed the distribution of GLP-1R-expressing neurons and axonal projections of NTS GLP-1-producing neurons in the mouse brain. GLP-1R neurons were found to be broadly distributed in the brain and specific forebrain regions, particularly the hypothalamus, including the arcuate nucleus of the hypothalamus (ARC), a brain region known to regulate energy homeostasis and feeding behavior, that receives dense NTSGcg neuronal projections. The impact of GLP-1 signaling in the ARC GLP-1R-expressing neurons and the impact of activation of ARC GLP-1R on food intake was examined. Application of GLP-1R specific agonist Exendin-4 (Exn-4) enhanced a proportion of the ARC GLP-1R-expressing neurons and pro-opiomelanocortin (POMC) neuronal action potential firing rates. Chemogenetic activation of the ARC GLP-1R neurons by using Cre-dependent hM3Dq AAV in the GLP-1R-ires-Cre mice, established that acute activation of the ARC GLP-1R neurons significantly suppressed food intake but did not have a strong impact on glucose homeostasis. Conclusions: These results highlight the importance of central GLP-1 signaling in the ARC that express GLP-1R that upon activation, regulate feeding behavior. [ABSTRACT FROM AUTHOR]

Hypoxic-ischemic encephalopathy is brain injury resulting from the loss of oxygen and blood supply around the time of birth. It is associated with a high risk of death or disability. The only approved treatment is therapeutic hypothermia. Therapeutic hypothermia has consistently been shown to significantly reduce the risk of death and disability in infants with hypoxic-ischemic encephalopathy. However, approximately 29% of infants treated with therapeutic hypothermia still develop disability. Recent preclinical and clinical studies have shown that there is still persistent neuroinflammation even after treating with therapeutic hypothermia, which may contribute to the deficits seen in infants despite treatment. This suggests that potentially targeting this persistent neuroinflammation would have an additive benefit in addition to therapeutic hypothermia. A potential additive treatment is Exendin-4, which is a glucagon-like peptide 1 receptor agonist. Preclinical data from various in vitro and in vivo disease models have shown that Exendin-4 has anti-inflammatory, mitochondrial protective, anti-apoptotic, anti-oxidative and neurotrophic effects. Although preclinical studies of the effect of Exendin-4 in perinatal hypoxic-ischemic brain injury are limited, a seminal study in neonatal mice showed that Exendin-4 had promising neuroprotective effects. Further studies on Exendin-4 neuroprotection for perinatal hypoxic-ischemic brain injury, including in large animal translational models are warranted to better understand its safety, window of opportunity and effectiveness as an adjunct with therapeutic hypothermia. [ABSTRACT FROM AUTHOR]

Epidemiological analyses indicate that type 2 diabetes mellitus (T2DM) is a risk factor for Alzheimer's disease (AD). They share common pathophysiological mechanisms. Thus, it has been increasingly suggested that several anti-T2DM drugs may have therapeutic potential in AD. Exendin-4, as a glucagon-like peptide-1 (GLP-1) receptor agonist, is an approved drug used to treat T2DM. In this research, the neuroprotective effect of Exendin-4 was investigated for the first time using transgenic Caenorhabditis elegans. Our results demonstrated that Exendin-4 attenuated the amyloid-β (1-42) (Aβl-42) toxicity via multiple mechanisms, such as depressing its expression on protein and mRNA and reducing Aβ (1-42) accumulation. Exendin-4 at 0.5 mg/ml had been shown to extend life by 34.39% in CL4176 and delay the onset of paralysis in CL4176 and CL2006 which were increased by 8.18 and 8.02%, respectively. With the treatment of Exendin-4, the nuclear translocation of DAF-16 in the transgenic nematode TJ356 was enhanced. Superoxide dismutase-3 (SOD-3), as a downstream target gene regulated by DAF-16, was upregulated on mRNA level and activity. The reactive oxygen species (ROS) level was decreased. In contrast, we observed that the ability of Exendin-4 to regulate SOD was decreased in CL4176 worms with the DAF-16 gene silenced. The activity of SOD and the mRNA level of sod-3 were downregulated by 30.45 and 43.13%, respectively. Taken together, Exendin-4 attenuated Aβ (1-42) toxicity in the C. elegans model of AD via decreasing the expression and the accumulation of Aβ (1-42). Exendin-4 exhibited the ability of antioxidant stress through DAF-16. With continuous research, Exendin-4 would become a potential therapeutic strategy for treating AD. [ABSTRACT FROM AUTHOR]

Objective: To assess the response of cellular infiltration in wounds treated with Exendin-4. Method: In this study, 16 mice were used. On each mouse, two wounds were produced, one above the other, in order to study the effects of the various treatments carried out. The wounds then received an intradermal injection of either saline (20μl; Group 1) or Exendin-4 (Exe4, 62ng; Group 2) in the upper and lower wounds, respectively. The mice were euthanised in order to collect the wounds at time of abrasion (T0), at 48 hours (T1), 96 hours (T2) and 144 hours (T3). The expression of the glucagon-like peptide-1 receptor (GLP-1R) was evaluated by Western blot in wound lysates. Histological and histochemistry methods were applied in cryosections. Results: In T2 and T3 treated wounds, the mast cells degranulation index increased while GLP-1R expression, tumour necrosis factor (TNF)-α, or heat shock protein (HSP)47 antigens were detected in their cytoplasm. These cells interacted with dendritic cells, vessels or granulocytes. The density of dendritic cells increased progressively, and intercellular connections were found between these cells and vessels. Among the dendritic cells at T2, only M2 macrophages increased. However, M1 cells expressed transforming growth factor (TGF)-β and both interacted with either fibroblasts or with vessels. The number of plasmacytoid dendritic cells increased and established close contacts with regulatory T cells. Conclusion: We propose that after treatment with Exe4, early activation of mast cells is critical in wound healing acceleration. This is crucial in understanding the potential effect of this drug for viable clinical therapies. [ABSTRACT FROM AUTHOR]

Background: Effective drugs for preventing or treating skin flap necrosis remain elusive. In this study, we investigated the potential protective effect of exendin-4 against skin flap ischemia-reperfusion injury (IRI) through the inhibition of ferroptosis., Method: A rat abdomen was constructed with an island skin flap, and the superficial vascular pedicle of the abdominal wall was closed using a vascular clamp, which was removed after 8 h. Before surgery, RSL3 and ferrostatin-1 solutions were intraperitoneally injected. After the surgery, subcutaneous injections of exendin-4 were administered daily. The number of inflammatory cells, mean vascular density, collagen fiber content, and apoptosis and ferroptosis indicators were quantified 24 h after reperfusion. Survival, contraction rate, and blood perfusion of the skin flap were evaluated on days 1, 3, 5, and 7 after reperfusion., Results: The flap survival rate was significantly higher in the exendin-4 group than that in the injury group, whereas the contraction rate was lower. Compared with the injury group, the exendin-4 group showed less inflammatory cell infiltration, higher vascular density, and less collagen fiber loss. At the molecular level, the exendin-4 group demonstrated opposite or elevated expression of apoptosis and ferroptosis indicators than those in the injury group, with significantly increased glutathione peroxidase 4 (Gpx4). Ferroptosis inhibitors and agonists enhanced and reversed the protective effects of exendin-4, respectively., Conclusion: Exendin-4 alleviates skin flap IRI by upregulating Gpx4 expression to inhibit ferroptosis. Therefore, exendin-4 may serve as a novel clinical treatment for skin flap IRI., Competing Interests: Declaration of Competing Interest All authors disclosed no relevant relationships., (Copyright © 2024. Published by Elsevier B.V.)