The GLP-1 receptor agonist exendin-4 reduces taurine and glycine in nucleus accumbens of male rats, an effect tentatively involving the nucleus tractus solitarius.

The physiological effects of glucagon-like peptide-1 (GLP-1) are mainly centered on its ability to decrease blood glucose levels and facilitate satiety. Additional physiological functions have been identified by means of GLP-1 agonists such as exenatide (exendin-4; Ex4). In particular, Ex4 reduces the intake of natural and artificial rewards, effects that to some extent involve activation of GLP-1 receptors in the nucleus tractus solitarius (NTS). Although Ex4 acts in the brain, the neurochemical mechanisms underlying this activation are not fully elucidated. Investigating Ex4-induced neurochemical alterations in the nucleus accumbens (NAc) would be valuable for understanding its impact on reward-related behaviors. The aim of the present exploratory in vivo microdialysis study was therefore to study how Ex4, administered either systemically or locally into the NTS, influences classical neurotransmitters like dopamine, serotonin, noradrenaline, glutamate and GABA as well as additional players such as glycine, taurine and serine in NAc of male rats. We showed that Ex4 reduced extracellular levels of serine, taurine and glycine, where the latter two declines appear to involve activation of GLP-1R in the NTS. Besides, after systemic Ex4 injection the metabolites DOPAC, HVA, and 5HIAA are elevated. Where the increase in metabolites related to dopamine, but not serotonin, involves GLP-1 receptors in other areas than the NTS. Although the descriptive nature of the present data does not provide causality, it may however serve as an indication of mechanisms underlying how Ex4 may modulate reward-related behaviors.

The Antiobesity Effect and Safety of GLP-1 Receptor Agonist in Overweight/Obese Adolescents Without Diabetes Mellitus: A Systematic Review and Meta-Analysis.

BACKGROUND: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), particularly semaglutide, have become the leading anti-obesity drugs for adults, and a similar trend may follow in adolescents with its recent approval for this age group. However, there is a lack of comparative analysis on the weight loss effects and safety of GLP-1 RAs in obese or overweight pediatric and adolescent populations, especially those who are non-diabetic. This systematic review and meta-analysis aim to provide current evidence on the efficacy and safety of GLP-1 RAs as an anti-obesity treatment in obese or overweight non-diabetic pediatric and adolescent populations. METHOD:  We searched electronic databases from inception until January 2024 for randomized controlled trials (RCTs) that analyzed the weight loss effect of GLP-1 receptor agonists in adolescents with obesity or overweight without diabetes mellitus. Search results were screened, and eligible studies were included to perform a systematic review and meta-analysis using the Review Manager (RevMan) computer program Version 5.4.1 (The Cochrane Collaboration, 2020) with a random-effects model. The primary efficacy outcomes were changes in body weight, BMI, and BMI Z-score, while the secondary outcomes were the incidence of gastrointestinal adverse events, treatment discontinuation rate due to adverse events, and incidence of serious adverse events. The mean difference, odds ratio, and 95% confidence interval (CI) were used to present the meta-analysis results. Publication bias was visualized using a funnel plot. The quality of the studies was analyzed using Cochrane's Risk of Bias tool (RoB2). RESULTS: A total of seven RCTs with 576 adolescent participants were included in the analysis. GLP-1 RAs significantly achieved greater weight loss than placebo, with a mean difference of -4.98 kg (-8.49, -1.46), I² = 99%, p = 0.006. Subgroup analysis showed that semaglutide had the most pronounced anti-obesity effect (mean difference of -17.70 kg (-18.89, -16.51), p < 0.00001), compared to liraglutide (mean difference of -2.26 kg (-5.17, 0.65), I² = 99%, p = 0.13) and exenatide (mean difference of -3.17 kg (-4.45, -1.90), I² = 0%, p < 0.0001). Similar results were obtained for other efficacy parameters such as BMI and BMI z-score. However, GLP-1 RA was associated with more gastrointestinal adverse events (such as nausea and vomiting) than placebo (3.06 (2.12, 4.42), I² = 0%, p < 0.00001), with incidence comparable among all GLP-1 RAs in the subgroup analysis. The overall risk of bias among included studies was either of 'some concern' or 'high risk.' CONCLUSIONS: Our meta-analysis demonstrated that GLP-1 RAs had a superior anti-obesity effect compared to placebo or lifestyle modification in obese or overweight non-diabetic adolescents, particularly semaglutide, which had a more pronounced anti-obesity effect than liraglutide and exenatide, with tolerable gastrointestinal adverse effects.

Glucagon-Like Peptide-1 Receptor Agonist Use in Pregnancy: A Review.

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are peptide analogues that are used to treat type 2 diabetes mellitus (T2DM) and obesity. The first medication in this class, Exenatide, was approved in 2005, and these medications, specifically Semaglutide, have become more popular in recent years due to their pronounced effects on glycemic control, weight reduction, and cardiovascular health. Due to successful weight loss from these medications, many women previously diagnosed with oligomenorrhea and unable to conceive have experienced unplanned pregnancies while taking the medications. However, there is currently little data for clinicians to use in counseling patients in cases of accidental periconceptional exposure. In some studies examining small animals exposed to GLP-1RAs in pregnancy, there has been evidence of adverse outcomes in the offspring, including decreased fetal growth, skeletal and visceral anomalies, and embryonic death. Although there are no prospective studies in humans, case reports, cohort studies, and population-based studies have not shown a pattern of congenital anomalies in infants. A recent large, observational, population-based cohort study examined 938 pregnancies affected by T2DM and compared outcomes from periconceptional exposure to GLP-1RAs and insulin. The authors concluded there was not a significantly increased risk of major congenital malformations in patients taking GLP-1RAs, although there was no information on maternal glycemic control or diabetic fetopathy. As diabetic embryopathy is directly related to the degree of maternal hyperglycemia and not the diagnosis of diabetes itself, it is not possible to make this conclusion without this information. Furthermore, there is little evidence available regarding fetal growth restriction, embryonic or fetal death, or other potential complications. At this time, patients should be counseled there is not enough evidence to predict any adverse effects, or the lack thereof, of periconceptional exposure of GLP-1RAs during pregnancy. We recommend that all patients use contraception to prevent unintended pregnancy while taking GLP-1RAs.

Medication adherence to sodium-glucose cotransporter-2 inhibitors versus glucagon-like peptide-1 receptor agonists: A meta-analysis.

AIM: To perform a meta-analysis comparing real-world medication adherence to sodium-glucose cotransporter-2 inhibitors (SGLT2is) versus glucagon-like peptide-1 receptor agonists (GLP-1RAs). MATERIALS AND METHODS: A systematic search of Medline and Embase was conducted through October 2023. To meet inclusion criteria, articles had to be published in full text form and directly compare medication adherence to SGLT2is versus GLP-1RAs in adults. Only studies evaluating real-world data and utilizing the proportion of days covered (PDC) to measure adherence were included. Non-adherence, defined as the proportion of patients with a PDC <80%, was the primary outcome. A subgroup analysis evaluating results among studies conducted in the United States was performed. RESULTS: We identified eight studies evaluating 205 103 patients for inclusion. The most common country from which the data was derived was the United States (n = 5 studies). Upon meta-analysis, we observed no difference in non-adherence (i.e. PDC <80%) to SGLT2is versus GLP-1RAs (relative risk = 0.86; 95% confidence interval = 0.72-1.02). In the analysis, including only US studies, SGLT2i use was associated with a 23% lower risk of non-adherence compared with GLP-1RA use (relative risk = 0.77; 95% confidence interval = 0.72-0.82). CONCLUSIONS: In this meta-analysis of eight studies that included approximately 200 000 patients, there was no difference in adherence to SGLT2is versus GLP-1RAs. However, SGLT2i use was associated with higher adherence when the analysis was limited to US studies.

Improved ovarian adiponectin system expression in polycystic ovary syndrome treated with exenatide.

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder that can cause infertility. This experimental study was conducted to elucidate the role of adiponectin signaling in rats with PCOS treated with exenatide. Twenty-eight adult female Wistar rats were divided into four groups of seven. The normal group did not receive any drug. The PCOS+vehicle (Veh) group received estradiol valerate to induce PCOS, then was divided into PCOS +E50 and PCOS+E100 groups and treated with 50 or 100 mg/kg doses of exenatide, respectively. The mRNA expression of adiponectin and adiponectin receptor 1 (Adipo-R1) was evaluated using a semi-quantitative real-time polymerase chain reaction. The results indicated that the level of adiponectin diminished in the PCOS rats while exenatide increased adiponectin expression at both doses. Adiponectin receptor mRNA levels were higher in the PCOS rats than in the normal rats (p<0.05). In addition, exenatide decreased the levels of Adipo-R1 expression. Taken together, our results showed that exenatide may improve PCOS characteristics in rats through the molecular regulation of adiponectin and its receptor.

Development and validation of stability-indicating assay method and identification of force degradation products of glucagon-like peptide-1 synthetic analog Exenatide using liquid chromatography coupled with Orbitrap mass spectrometer.

Exenatide is a synthetic glucagon-like peptide 1 analog, widely used in the management of type 2 diabetes mellitus. The stability of pharmaceutical products is significantly impacted by various environmental stress conditions. The present study reports the development of a validated reverse-phase high-performance liquid chromatography (RP-HPLC) stability-indicating method for the identification of force degradation products (DPs) of synthetic glucagon-like peptide-1 analog Exenatide using UHPLC-Orbitrap fusionTM mass spectrometer. Force degradation studies were performed by subjecting Exenatide to various stress conditions, such as hydrolytic, oxidative, photolytic and thermal to investigate the stability indicating ability of the method. Significant degradation was observed during acidic, oxidative, photolytic and thermal stress conditions. Exenatide and its major DPs identification and characterization were demonstrated by employing LC-HRMS and MS/MS method. In total, five major stress DPs were characterized, and their fragmentation pathway was proposed using MS/MS studies. Finally, the proposed RP-HPLC method was validated as per ICH guidance.

Drug release profile of a novel exenatide long-term drug delivery system (OKV-119) administered to cats.

Beneficial weight-loss properties of glucagon-like peptide-1 receptor agonists (GLP-1RA) in obese people, with corresponding improvements in cardiometabolic risk factors, are well established. OKV-119 is an investigational drug delivery system that is being developed for the long-term delivery of the GLP-1RA exenatide to feline patients. The purpose of this study was to evaluate the drug release characteristics of subcutaneous OKV-119 implants configured to release exenatide for 84 days. Following a 7-day acclimation period, five purpose-bred cats were implanted with OKV-119 protypes and observed for a 112-day study period. Food intake, weekly plasma exenatide concentrations and body weight were measured. Exenatide plasma concentrations were detected at the first measured timepoint (Day 7) and maintained above baseline for over 84 Days. Over the first 28 days, reduced caloric intake and a reduction in body weight were observed in four of five cats. In these cats, a body weight reduction of at least 5% was maintained throughout the 112-day study period. This study demonstrates that a single OKV-119 implant can deliver the GLP-1RA exenatide for a months long duration. Results suggest that exposure to exenatide plasma concentrations ranging from 1.5 ng/ml to 4 ng/ml are sufficient for inducing weight loss in cats.

Rare cutaneous adverse reactions associated with GLP-1 agonists: a review of the published literature.

Glucagon-like-peptide-1 (GLP-1) agonists are an emerging class of medications used to manage type 2 diabetes mellitus (T2DM) and weight loss, with demonstrated efficacy in reducing hemoglobin A1c levels, body mass index, and adverse cardiovascular events. While previous studies have reviewed notable cutaneous adverse effects with other antidiabetic medications, little is known about GLP-1 agonist-induced cutaneous reactions. Nevertheless, rare but significant cutaneous adverse reactions have been reported, including but not limited to dermal hypersensitivity reactions, eosinophilic panniculitis, bullous pemphigoid, and morbilliform drug eruptions. As GLP-1 induced cutaneous reactions are diverse, diagnosis requires clinical suspicion, thorough history-taking, and supportive histopathological findings when available. Management involves cessation of the offending agent with a tailored regimen to address inflammatory and/or immunogenic etiologies as well as irritative symptoms. This review aims to consolidate available information from case reports and case series regarding rare skin-related adverse outcomes due to GLP-1 use, aiming to provide a comprehensive overview of the presentation, pathogenesis, and management for dermatologists and other clinicians.

Role of LRP5/6/GSK-3ß/ß-catenin in the differences in exenatide- and insulin-promoted T2D osteogenesis and osteomodulation.

BACKGROUND AND PURPOSE: Insulin and exenatide are two hypoglycaemic agents that exhibit different osteogenic effects. This study compared the differences between exenatide and insulin in osseointegration in a rat model of Type 2 diabetes (T2D) and explored the mechanisms promoting osteogenesis in this model of T2D. EXPERIMENTAL APPROACH: In vivo, micro-CT was used to detect differences in the peri-implant bone microstructure in vivo. Histology, dual-fluorescent labelling, immunofluorescence and immunohistochemistry were used to detect differences in tissue, cell and protein expression around the implants. In vitro, RT-PCR and western blotting were used to measure the expression of osteogenesis- and Wnt signalling-related genes and proteins in bone marrow mesenchymal stromal cells (BMSCs) from rats with T2D (TBMSCs) after PBS, insulin and exenatide treatment. RT-PCR was used to detect the expression of Wnt bypass cascade reactions under Wnt inactivation. KEY RESULTS: Micro-CT and section staining showed exenatide extensively promoted peri-implant osseointegration. Both in vivo and in vitro experiments showed exenatide substantially increased the expression of osteogenesis-related and activated the LRP5/6/GSK-3ß/ß-catenin-related Wnt pathway. Furthermore, exenatide suppressed expression of Bmpr1a to inhibit lipogenesis and promoted expression of Btrc to suppress inflammation. CONCLUSION AND IMPLICATIONS: Compared to insulin, exenatide significantly improved osteogenesis in T2D rats and TBMSCs. In addition to its dependence on LRP5/6/GSK-3ß/ß-catenin signalling for osteogenic differentiation, exenatide-mediated osteomodulation also involves inhibition of inflammation and adipogenesis by BMPR1A and ß-TrCP, respectively.

Exenatide reduces atrial fibrillation susceptibility by inhibiting hKv1.5 and hNav1.5 channels.

Exenatide, a promising cardioprotective agent, protects against cardiac structural remodeling and diastolic dysfunction. Combined blockade of sodium and potassium channels is valuable for managing atrial fibrillation (AF). Here, we explored whether exenatide displayed anti-AF effects by inhibiting human Kv1.5 and Nav1.5 channels. We used the whole-cell patch-clamp technique to investigate the effects of exenatide on hKv1.5 and hNav1.5 channels expressed in human embryonic kidney 293 cells and studied the effects of exenatide on action potential (AP) and other cardiac ionic currents in rat atrial myocytes. Additionally, an electrical mapping system was used to explore the effects of exenatide on electrical properties and AF activity in isolated rat hearts. Finally, a rat AF model, established using acetylcholine and calcium chloride, was employed to evaluate the anti-AF potential of exenatide in rats. Exenatide reversibly suppressed IKv1.5 with IC50 of 3.08 µM, preferentially blocked the hKv1.5 channel in its closed state, and positively shifted the voltage-dependent activation curve. Exenatide also reversibly inhibited INav1.5 with IC50 of 3.30 µM, negatively shifted the voltage-dependent inactivation curve, and slowed its recovery from inactivation with significant use-dependency at 5 and 10 Hz. Furthermore, exenatide prolonged AP duration and suppressed the sustained K+ current (Iss) and transient outward K+ current (Ito), but without inhibition of L-type Ca2+ current (ICa,L) in rat atrial myocytes. Exenatide prevented AF incidence and duration in rat hearts and rats. These findings demonstrate that exenatide inhibits IKv1.5 and INav1.5in vitro and reduces AF susceptibility in isolated rat hearts and rats.

Attenuating mitochondrial dysfunction and morphological disruption with PT320 delays dopamine degeneration in MitoPark mice.

BACKGROUND: Mitochondria are essential organelles involved in cellular energy production. Changes in mitochondrial function can lead to dysfunction and cell death in aging and age-related disorders. Recent research suggests that mitochondrial dysfunction is closely linked to neurodegenerative diseases. Glucagon-like peptide-1 receptor (GLP-1R) agonist has gained interest as a potential treatment for Parkinson's disease (PD). However, the exact mechanisms responsible for the therapeutic effects of GLP-1R-related agonists are not yet fully understood. METHODS: In this study, we explores the effects of early treatment with PT320, a sustained release formulation of the GLP-1R agonist Exenatide, on mitochondrial functions and morphology in a progressive PD mouse model, the MitoPark (MP) mouse. RESULTS: Our findings demonstrate that administration of a clinically translatable dose of PT320 ameliorates the reduction in tyrosine hydroxylase expression, lowers reactive oxygen species (ROS) levels, and inhibits mitochondrial cytochrome c release during nigrostriatal dopaminergic denervation in MP mice. PT320 treatment significantly preserved mitochondrial function and morphology but did not influence the reduction in mitochondria numbers during PD progression in MP mice. Genetic analysis indicated that the cytoprotective effect of PT320 is attributed to a reduction in the expression of mitochondrial fission protein 1 (Fis1) and an increase in the expression of optic atrophy type 1 (Opa1), which is known to play a role in maintaining mitochondrial homeostasis and decreasing cytochrome c release through remodeling of the cristae. CONCLUSION: Our findings suggest that the early administration of PT320 shows potential as a neuroprotective treatment for PD, as it can preserve mitochondrial function. Through enhancing mitochondrial health by regulating Opa1 and Fis1, PT320 presents a new neuroprotective therapy in PD.

Exenatide for obesity in children and adolescents: Systematic review and meta-analysis.

Objectives: There is no curative treatment for childhood obesity. We aim to synthesize published Randomized Controlled Trials (RCTs) evidence on the efficacy of exenatide in obese children and adolescents. Methods: We conducted a comprehensive search and analysis of relevant studies in popular databases such as PubMed, Web of Science, Embase, and Cochrane Library. Our focus was on RCTs that examined the effectiveness of exenatide for treating obesity in children. We primarily assessed changes in body weight, body mass index (BMI), fasting plasma glucose (FPG), or HbA1c levels. Additionally, we considered any adverse events reported during the treatment period, with particular attention to hypoglycemia. To evaluate the quality of RCTs included in our study, we employed the Cochrane bias assessment tool. Results: Five studies met the inclusion criteria. A group of 100 children were assigned to receive treatment with exenatide. Compared with controls, exenatide therapy reduced body weight and BMI by -0.6% (95% CI -0.93, -0.27), -1.11% (95% CI -1.91, -0.31), respectively. Undesirable consequences encompass gastrointestinal symptoms, with the majority of instances being characterized by mild severity. Conclusion: Exenatide demonstrates efficacy in the treatment of pediatric and adolescent obesity. Systematic Review Registration: PROSPERO https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=413706.

Long-acting exenatide does not prevent cognitive decline in mild cognitive impairment: a proof-of-concept clinical trial.

PURPOSE: According to preclinical evidence, GLP-1 receptor may be an actionable target in neurodegenerative disorders, including Alzheimer's disease (AD). Previous clinical trials of GLP-1 receptor agonists were conducted in patients with early AD, yielding mixed results. The aim was to assess in a proof-of-concept study whether slow-release exenatide, a long-acting GLP-1 agonist, can benefit the cognitive performance of people with mild cognitive impairment (MCI). METHODS: Thirty-two (16 females) patients were randomized to either slow-release exenatide (n = 17; 2 mg s.c. once a week) or no treatment (n = 15) for 32 weeks. The primary endpoint was the change in ADAS-Cog11 cognitive test score at 32 weeks vs baseline. Secondary endpoints herein reported included additional cognitive tests and plasma readouts of GLP-1 receptor engagement. Statistical analysis was conducted by intention to treat. RESULTS: No significant between-group effects of exenatide on ADAS-Cog11 score (p = 0.17) were detected. A gender interaction with treatment was observed (p = 0.04), due to worsening of the ADAS-Cog11 score in women randomized to exenatide (p = 0.018), after correction for age, scholar level, dysglycemia, and ADAS-Cog score baseline value. Fasting plasma glucose (p = 0.02) and body weight (p = 0.03) decreased in patients randomized to exenatide. CONCLUSION: In patients with MCI, a 32-week trial with slow-release exenatide had no beneficial effect on cognitive performance. TRIAL REGISTRATION NUMBER: NCT03881371, registered on 21 July, 2016.

Glucagon-like peptide-1 receptor agonists modestly reduced blood pressure among patients with and without diabetes mellitus: A meta-analysis and meta-regression.

AIM: The cardiovascular benefits provided by glucagon-like peptide-1 receptor agonists (GLP-1RAs) extend beyond weight reduction and glycaemic control. One possible mechanism may relate to blood pressure (BP) reduction. We aim to quantify the BP-lowering effects of GLP1-RAs. METHODS: A comprehensive database search for placebo-controlled randomized controlled trials on GLP-1RA treatment was conducted until December 2023. Data extraction and quality assessment were carried out, employing a robust statistical analysis using a random effects model to determine outcomes with a mean difference (MD) in mmHg and 95% confidence intervals (CIs). The primary endpoint was the mean difference in systolic BP (SBP) and diastolic BP. Subgroup analyses and meta-regressions were done to account for covariates. RESULTS: Compared with placebo, GLP-1RAs modestly reduced SBP [semaglutide: MD -3.40 (95% CI -4.22 to -2.59, p < .001); liraglutide: MD -2.61 (95% CI -3.48 to -1.74, p < .001); dulaglutide: MD -1.46 (95% CI -2.20 to -0.72, p < .001); and exenatide: MD -3.36 (95% CI -3.63 to -3.10, p < .001)]. This benefit consistently increased with longer treatment durations. Diastolic BP reduction was only significant in the exenatide group [MD -0.94 (95% CI -1.78 to -0.1), p = .03]. Among semaglutide cohorts, mean changes in glycated haemoglobin and mean changes in body mass index were directly associated with SBP reduction. CONCLUSION: Patients on GLP-1RA experienced modest SBP lowering compared with placebo. This observed effect was associated with weight/body mass index reduction and better glycaemic control, which suggests that BP-lowering is an indirect effect of GLP-1RA and unlikely to be responsible for the benefits.

Effects of glucagon-like peptide-1 receptor agonists on spermatogenesis-related gene expression in mouse testis and testis-derived cell lines.

Glucagon-like peptide-1 (GLP-1) is an incretin released into the gastrointestinal tract after food ingestion, and stimulates insulin secretion from the beta cells of the pancreatic islets. Incretins have recently been reported to have extrapancreatic actions, and they are anticipated to have potential efficacy for conditions such as male infertility as well as diabetes. However, the effects of incretins on male reproductive function remain unclear. In this study, GLP-1 receptor expression and the effects of GLP-1 on spermatogenesis-associated genes were investigated using mouse testes and testis-derived cultured cell lines. Glp1r mRNA and GLP-1 protein were expressed in mouse testes at levels comparable to or greater than those in positive control adipose tissue, and the liver and intestine, and also in a Sertoli cell line (TM4) and a Leydig cell line (MA-10) as well as the GC-1 spg and GC-2 spd (ts) germ cell lines. TM4 cells treated with the GLP-1 receptor agonist exenatide showed transiently and significantly upregulated Kitl, Pdgfa, and Glp1r mRNA expression. Furthermore, at 1 hr post-exenatide administration to male mice, Kitl and Glp1r mRNA expression levels were significantly increased, and Pdgfa mRNA expression level also showed a tendency toward increase. TM4 cells were treated with various cell-activating agents, and bucladesine elicited significantly increased Glp1r mRNA expression. We suggest that GLP-1 provides acute stimulation of Sertoli cells in the mouse testis and has a stimulatory effect on the expression of spermatogenesis-related genes.

The GLP-1 receptor agonist exenatide improves recovery from spinal cord injury by inducing macrophage polarization toward the M2 phenotype.

Although a wide variety of mechanisms take part in the secondary injury phase of spinal cord injury (SCI), inflammation is the most important factor implicated in the sequelae after SCI. Being central to the inflammation reaction, macrophages and their polarization are a topic that has garnered wide interest in the studies of SCI secondary injury. The glucagon-like peptide 1 (GLP-1) receptor agonist exenatide has been shown to enhance the endoplasmic reticulum stress response and improve motor function recovery after spinal cord injury (SCI). Since exenatide has also been reported to induce the production of M2 cells in models of cerebral infarction and neurodegenerative diseases, this study was conducted to examine the effects of exenatide administration on the inflammation process that ensues after spinal cord injury. In a rat contusion model of spinal cord injury, the exenatide group received a subcutaneous injection of 10 µg exenatide immediately after injury while those in the control group received 1 mL of phosphate-buffered saline. Quantitative RT-PCR and immunohistochemical staining were used to evaluate the effects of exenatide administration on the macrophages infiltrating the injured spinal cord, especially with regard to macrophage M1 and M2 profiles. The changes in hind limb motor function were assessed based on Basso, Beattie, Bresnahan locomotor rating scale (BBB scale) scores. The improvement in BBB scale scores was significantly higher in the exenatide group from day 7 after injury and onwards. Quantitative RT-PCR revealed an increase in the expression of M2 markers and anti-inflammatory interleukins in the exenatide group that was accompanied by a decrease in the expression of M1 markers and inflammatory cytokines. Immunohistochemical staining showed no significant difference in M1 macrophage numbers between the two groups, but a significantly higher number of M2 macrophages was observed in the exenatide group on day 3 after injury. Our findings suggest that exenatide administration promoted the number of M2-phenotype macrophages after SCI, which may have led to the observed improvement in hind limb motor function in a rat model of SCI.

The GLP-1 receptor is expressed in vivo by human metastatic prostate cancer.

Objectives: The glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide, reduces human prostate cancer incidence, and similar GLP-1 receptor agonists reduce in vitro proliferation and in vivo growth of prostate cancer cell lines. Primary human prostate cancer expresses the GLP-1 receptor (GLP-1R) in vitro. Cancer evolves with stage, and whether advanced-stage human prostate cancer expresses GLP-1R is unknown. We hypothesised and aimed to prove that human metastatic castrate-resistant prostate cancer (mCRPC) expresses the GLP-1R in vivo. We hypothesised that mCRPC would thus be detectable by positron emission tomography/computed tomography (PET/CT) using a radiotracer bound to a GLP-1R ligand, as in exendin PET/CT. Materials and methods: Men with mCRPC, with more than one prostate-specific membrane antigen (PSMA)-avid lesion on PET/CT scanning (pathognomic in that setting for prostate cancer lesions), were approached to undergo PET/CT with gallium68-Dota-exendin-4. We documented PET/CT PSMA-avid lesions, which were also PET/CT exendin avid, as evidence of in vivo GLP-1R expression. Results: Out of the 24 men referred, three did not meet the inclusion criteria. Seventeen declined, largely because the study offered them no therapeutic benefit. Among the four men imaged, three had no exendin-avid lesions, while one had six osseous PSMA-avid lesions, three of which were also exendin avid. Conclusions: We demonstrated in vivo GLP-1R expression by human mCPRC, detecting PET/CT lesions avid for both PSMA and exendin, in one of four participants. GLP-1R expression may thus occur even in advanced-stage prostate cancer. Our data contribute to growing evidence supporting the testing of GLP-1 receptor agonists for therapeutic benefit in prostate cancer.

The role of partial area under the curve and maximum concentrations in assessing the bioequivalence of long-acting injectable formulation of exenatide_A sensitivity analysis.

To ensure therapeutic equivalence between the long-acting injectable (LAI) products, additional PK metrics other than Cmax and AUC were considered necessary. However, regarding the selection of additional PK metrics for bioequivalence (BE) assessment of exenatide LAI, a discrepancy existed between EMA's and USFDA's product-specific guidance. The EMA recommends that both the maximum plasma concentration in the initial-release phase (Cmax,1) and the extended-release phase (Cmax,2) should be determined. Nevertheless, the USFDA recommends the use of the partial area under the curve (i.e., the area under the curve from week 4 to the last sampling point; pAUC4w-t). The focus of this study was to compare the sensitivity of different PK metrics, including Cmax,1, Cmax,2, pAUC4w-t, early and late pAUC metrics truncated at different time points (three, four, five, six and seven weeks), to formulation-related parameters and pharmacodynamic (PD) markers of glycemic control. A sensitivity analysis was conducted using the published PK/PD model of exenatide LAI. The results indicated that Cmax,1 and Cmax,2 exhibited comparable sensitivities. AUC4w-t was sensitive to changes in detecting the differences in formulation-related parameters and PD markers of glycemic control, but did not provide superior sensitivity performance compared to Cmax,1 and Cmax,2. Among all tested PK metrics, AUC7w-t was found to be the most sensitive. The optimal cut-off time point for the pAUC should be set at the time of maximum plasma concentration in the extended-release phase (approximately 6-7 weeks). These results may provide useful insights into the selection of appropriate PK metrics for BE determination of exenatide LAI.