Effects Of Glucagon-like Peptide-1 Receptor Agonists Research Articles

The effect of GLP-1 receptor agonists in pre-clinical rodent models of Parkinson’s disease: A systematic review and meta-analysis

BackgroundParkinson’s Disease (PD) is a progressive neurodegenerative condition associated with significant morbidity. Currently, there are limited pharmacological options and none of the therapies available are disease-modifying. This systematic review and meta-analysis considers a novel drug class through the research question – in pre-clinical rodent models of PD, is GLP-1 receptor agonist therapy neuroprotective when compared to vehicle controls? MethodsA literature search was conducted to locate relevant pre-clinical studies. Two separate outcomes were considered. The primary outcome was indicators of dopaminergic neurotransmission. The secondary outcome was indicators of motor symptoms. Untreated PD models were compared to PD-models treated with GLP-1 receptor agonists. The final meta-analysis was conducted using the Cochrane RevMan software and represented continuous data using the inverse variance statistical method and random effects analysis model. The final study statistic was represented as an SMD value with a p-value < 0.05 considered statistically significant. Study heterogeneity and publication bias was assessed using I2 values and funnel plots respectively. ResultsEleven studies fit the inclusion criteria and were included in the final analysis. For the primary outcome (n = 128), there was a statistically significant relative improvement of dopaminergic neurotransmission (SMD 1.71, 95% CI = 0.74–2.68, p = 0.0005, I2 = 76%). For the secondary outcome (n = 280), there was a statistically significant improvement in motor outcomes (SMD 2.11, 95% CI = 1.14–3.09, p < 0.0001, I2 = 89%). ConclusionsGLP-1 receptor agonist therapy is neuroprotective in pre-clinical models of PD. This study provides the clinical foundation and research support for the design of rigorous clinical trials to further investigate these results in human PD populations.

Cardiovascular effectiveness of glucagon-like peptide 1 receptor agonists versus dipeptidyl peptidase-4 inhibitors in type 2 diabetes: A meta-analysis based on propensity score-matched studies

Glucagon-like peptide 1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-4 inhibitors (DPP-4i) are two novel classes of hypoglycemic agents. The relative cardiovascular effectiveness between these two drug classes in patients with type 2 diabetes (T2D) is unestablished due to the absence of large cardiovascular outcome trials directly comparing DPP-4i with GLP-1RA. We aimed to incorporate large propensity score-matched cohort studies to conduct a meta-analysis, to determine the relative effectiveness of GLP-1RA versus DPP-4i on cardiovascular endpoints in T2D patients. Compared to DPP-4i, GLP-1RA was associated with the significantly lower risks of major adverse cardiovascular events [MACE] (HR 0.76, 95% CI 0.63−0.92), cardiovascular mortality (HR 0.59, 95% CI 0.37−0.95), myocardial infarction (HR 0.89, 95% CI 0.80−0.98), stroke (HR 0.86, 95% CI 0.76−0.96), and all-cause mortality (HR 0.63, 95% CI 0.42−0.96) in T2D patients; whereas these two drug classes had the similar risk of hospitalization for heart failure [HHF] (HR 0.95, 95% CI 0.77–1.16). Meta-regression analyses showed that six factors (i.e., mean age, female proportion, cardiovascular disease proportion, heart failure proportion, and the proportions of receiving metformin and insulin at baseline) did not significantly affect the effects of GLP-1RA on MACE and HHF (P ≥ 0.076). This meta-analysis provides the direct evidence regarding the relative cardiovascular effectiveness of GLP-1RA versus DPP-4i from real-world studies, and its findings suggest that among T2D patients GLP-1RA should be considered in preference to DPP-4i as for preventing atherosclerotic cardiovascular events and death in clinical practice.

L-dopa-Dependent Effects of GLP-1R Agonists on the Survival of Dopaminergic Cells Transplanted into a Rat Model of Parkinson Disease.

Cell therapy is a promising treatment for Parkinson’s disease (PD), however clinical trials to date have shown relatively low survival and significant patient-to-patient variability. Glucagon Like Peptide-1 receptor (GLP-1R) agonists have potential neuroprotective effects on endogenous dopaminergic neurons. This study explores whether these agents could similarly support the growth and survival of newly transplanted neurons. 6-OHDA lesioned Sprague Dawley rats received intra-striatal grafts of dopaminergic ventral mesencephalic cells from embryonic day 14 Wistar rat embryos. Transplanted rats then received either saline or L-dopa (12 mg/kg) administered every 48 h prior to, and following cell transplantation. Peripheral GLP-1R agonist administration (exendin-4, 0.5 μg/kg twice daily or liraglutide, 100 μg/kg once daily) commenced immediately after cell transplantation and was maintained throughout the study. Graft survival increased under administration of exendin-4, with motor function improving significantly following treatment with both exendin-4 and liraglutide. However, this effect was not observed in rats administered with L-dopa. In contrast, L-dopa treatment with liraglutide increased graft volume, with parallel increases in motor function. However, this improvement was accompanied by an increase in leukocyte infiltration around the graft. The co-administration of L-dopa and exendin-4 also led to indicators of insulin resistance not seen with liraglutide, which may underpin the differential effects observed between the two GLP1-R agonists. Overall, there may be some benefit to the supplementation of grafted patients with GLP-1R agonists but the potential interaction with other pharmacological treatments needs to be considered in more depth.

Effects of GLP-1 Receptor Agonists on Cardiovascular Events and Their Clinical Positioning

Effects of GLP-1 Receptor Agonists on Cardiovascular Events and Their Clinical Positioning

Effects of GLP-1RA and SGLT2i, Alone or in Combination, on Mouse Models of Type 2 Diabetes Representing Different Disease Stages.

Glucagon-like peptide-1 receptor agonist (GLP-1RA) and sodium-dependent glucose transporter 2 inhibitor (SGLT2i), in addition to lowering glucose, have pleiotropic effects on the heart, kidneys, and liver. These drugs have thus come into widespread use for treating type 2 diabetes (T2DM). However, mechanistic comparisons and effects of combining these drugs have not been adequately studied. Employing diet-induced obese (DIO) mice and db/db mice as models of the early and advanced stages of T2DM, we evaluated effects of single or combined use of liraglutide (a GLP-1RA) and ipragliflozin (a SGLT2i). Treatments with liraglutide and/or ipragliflozin for 28 days improved glycemic control and reduced hepatic lipid accumulation similarly in DIO mice. In contrast, in db/db mice, despite similar favorable effects on fatty liver, liraglutide exerted no beneficial effects on glycemic control. Improved glycemic control in db/db mice treated with ipragliflozin was accompanied by increased pancreatic β-cell area and insulin content, both of which tended to rise further when ipragliflozin was combined with liraglutide. Our data suggest that liraglutide is more efficient at an earlier stage and ipragliflozin can be effective in both stages. In addition, their combined use is a potential option for treating advanced stage diabetes with fatty liver disease.

Dipeptidyl peptidase-4 inhibitors, glucagon-like peptide 1 receptor agonists and sodium-glucose co-transporter-2 inhibitors for people with cardiovascular disease: a network meta-analysis.

Dipeptidyl peptidase-4 inhibitors, glucagon-like peptide 1 receptor agonists and sodium-glucose co-transporter-2 inhibitors for people with cardiovascular disease: a network meta-analysis.

Cardiovascular protective effects of GLP-1: a focus on the MAPK signaling pathway.

Cardiovascular and related metabolic diseases are significant global health challenges. Glucagon-like peptide 1 (GLP-1) is a brain-gut peptide secreted by the ileal endocrine system and is now an established drug target in type 2 diabetes (T2DM). GLP-1 targeting agents have been shown not only to treat T2DM, but also to exert cardiovascular protective effects by regulating multiple signaling pathways. The mitogen-activated protein kinase (MAPK) pathway, a common signal transduction pathway for transmitting extracellular signals to downstream effector molecules, is involved in regulating diverse cellular physiological processes, including cell proliferation, differentiation, stress, inflammation, functional synchronization, transformation, and apoptosis. The purpose of this review is to highlight the relationship between GLP-1 and cardiovascular disease (CVD) and discuss how GLP-1 exerts cardiovascular protective effects through the MAPK signaling pathway. This review also discusses the future challenges in fully characterizing and evaluating the CVD protective effects of GLP-1 receptor agonists (GLP-1RA) at the cellular and molecular levels. A better understanding of the MAPK signaling pathway that is dysregulated in CVD may aid in the design and development of promising GLP-1RA.

The effect of glucagon-like peptide-1 receptor agonists on 24-hour ambulatory blood pressure: a meta-analysis

Abstract Background Hypertension augments overall cardiovascular risk in patients with type 2 diabetes mellitus (T2DM), constituting a major additional burden for diabetic subjects; however, control rates of hypertension remain suboptimal. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), second-line treatment option for diabetics, have revolutionized the field of T2DM therapeutic management due to their pleiotropic effects, while they seem to hold multiple cardiovascular benefits. A few randomized controlled trials (RCTs) evaluated the effect of GLP-1RAs on ambulatory blood pressure (ABP). Ambulatory blood pressure monitoring (ABPM) provides a better method to predict long-term cardiovascular outcomes than office blood pressure. Purpose We sought to determine the effect of GLP-1RAs on ABPM, pooling data from relevant randomized controlled trials (RCTs). Methods We searched 2 major electronic databases, namely PubMed and Cochrane/CENTRAL, along with grey literature sources, for RCTs assessing the effect of various GLP-1RAs on ABP in patients with T2DM. Results After screening of the potentially eligible records, 7 RCTs were finally included in our meta-analysis (4 parallel-group and 3 cross-over). GLP-1RA treatment compared to placebo or active control resulted in a nonsignificant decrease in 24-h systolic blood pressure (MD=−1.57 mm Hg, 95% CI: −4.12 to 0.98, I2=63%) (Figure 1) and in 24-h diastolic blood pressure (MD=1.28 mmHg, 95% CI: −0.31 to 2.87, I2=49%) (Figure 2). No subgroup differences between the various GLP-1RAs were identified. More specifically, it was demonstrated that liraglutide once daily produced a non-significant decrease in 24-h systolic blood pressure (MD=−1.43 mm Hg, 95% CI: −5.24 to 2.38, I2=72%) and a non-significant increase in 24-h diastolic blood pressure (MD=1.47 mm Hg, 95% CI: −1.12 to 4.05, I2=61%), while data concerning the effect of once weekly dulaglutide and twice daily exenatide on ABPM were pooled from one RCT respectively (Figures 1, 2). Conclusions Antidiabetic treatment with GLP-1RAs does not influence either systolic or diastolic ABP in patients with T2DM. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

Metabolic improvement during short-term treatment with a GLP-1 receptor agonist does not improve cardiac diastolic function in patients type 2 diabetes: a randomized double-blind placebo-controlled trial

Abstract Background/Introduction The cardioprotective effect of glucagon-like peptide-1 (GLP-1) receptor agonists in patients with type 2 diabetes is still not well explained. In these patients, diastolic dysfunction is significant and linked to outcome, and the cardioprotective effect of GLP-1 receptor agonists may be by improving diastolic function. Purpose To investigate if short-term treatment of liraglutide a GLP-1 receptor agonist improves left ventricular diastolic function. Methods In an investigator-initiated double-blind randomized placebo-controlled trial the effect of 18 weeks of treatment with liraglutide on diastolic function was assessed in type 2 diabetes patients and echocardiographic signs of diastolic dysfunction (echo-Doppler determined E/e'≥9 or/and lateral e'≤10 cm/sec). Primary outcomes were improved left ventricle filling (the early peak filling rate, ePFR) and left atrium ease of emptying (the passive emptying fraction, LAPEF), assessed by cardiac magnetic resonance imaging at rest and during chronotropic stress (glycopyrrolate 4 mg/kg; a cholinergic receptor antagonist increasing heart rate, and thereby inducing chronotropic stress without also affecting contractility). Secondary outcomes included left ventricular and left atrial volumes and systolic function, measures of aortic stiffness, and echocardiographic diastolic parameters. Results Forty patients were randomized to liraglutide s.c. 1.8 mg/day (n=20) or placebo (n=20). Liraglutide reduced HbA1c (−0.47% 95% CI (−0.88 to −0.06)) and weight (−2.9kg 95% CI (−4.6 to −1.2)), both p&amp;lt;0.03). Liraglutide did not change ePFR at rest −24±60 vs. −6±46 ml/sec, during stress 2±58 vs. −2±38 ml/sec, or the changes from rest and stress 12.9±72.5 vs. 4.7±104.0, all p&amp;gt;0.05. LAPEF decreased with liraglutide during stress (median (Q1, Q3)) −3.1 (−9.0, 1.1) vs. 1.0 (−2.9, 6.1) %, p=0.049, but no changes were evident at rest −4.3 (−7.9, 1.9) vs. −0.6 (−3.1, 2.2) %, p=0.19, or for the changes from rest to stress −1.7±8.4 vs. 0.8±8.2, p=0.4. All secondary outcomes were unchanged by liraglutide. Conclusions Short-term treatment with liraglutide did not improve diastolic function in patients with type 2 diabetes and echocardiographic signs of diastolic dysfunction. This suggests that the cardioprotective effect seen in long-term studies of liraglutide is not related to the improvement of left ventricular diastolic function. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): ASB has received funding from the Danish Heart Association [16-R107-A6790-22002, and 18-R125-A8444-22110]. Novo Nordisk supported the study by an unrestricted grant covering the costs of CMR scans and blood analyses. Novo Nordisk provided free study medication and matching placebo pens. None of the funding sources played any role in the process of conduction, interpretation of results or publishing the study Primary OutcomesSecondary Outcomes

Effect ofglucagon-like peptide-1 receptor agonists, sodium-glucose cotransporter-2 inhibitors and their combination on left atrial strain and arterial function

Abstract Background We investigated the effects of insulin, glucagon-like peptide-1 receptor agonists (GLP-1RA), sodium-glucose cotransporter-2 inhibitors (SGLT-2i) and their combination on left atrial function of patients with type 2 diabetes mellitus and we searched for a relation with arterial function. Methods A total of 213 patients (59,5±9,1 year old, 161 male) with type 2 diabetes mellitus treated with metformin were randomized to insulin (n=46 served as controls), liraglutide (n=40), empagliflozin (n=46) or their combination (GLP-1RA + SGLT-2i) (n=50) as add-on. We measured at baseline and 6 months posttreatment: (a) perfused boundary region of the sublingual arterial microvessels (marker of endothelial glycocalyx thickness), (b) pulse wave velocity (PWV) and central systolic blood pressure, (c) global left ventricular Longitudinal strain, (d) left atrial strain. Results Six months after intervention, all patients improved left atrial reservoir strain (GLP1RA 30,7±9,3 vs 33,9±9,7%, p=0,011 / SGLT2i 30±8,3 vs 32,3±7,3%, p=0,04 / GLP1 &amp; SGLT2i 29,1±8,7 vs 31,3±8,2, p=0,007) in comparison with controls (33±8,3% vs 32,8±7,4, p=0,829). Also, patients treated with GLP1RA and their combination improved left atrial conduction strain (p&amp;lt;0.05). GLP-1RA or GLP-1RA + SGLT-2i provided a greater improvement in GLS compared with insulin or SGLT-2i (controls −18,5±3,9% vs −19,1±3%, p=0,202 / GLP1RA −18,2±4,1% vs −19,1±3,5%, p=0,03 / SGLT2i −19±4,1% vs −19,1±3,8%, p=0,764 / GLP1 &amp; SGLT2i −16,7±3,9% vs −17,5±4,3%, p=0,026). SGLT-2i or GLP-1RA and SGLT-2i showed a greater decrease of PWV (Controls 12,06±3,02 vs 11,62±2,79 m/sec, p=0,142 / GLP1 11,54±2,91 vs 11,45±2,52 m/sec, p=0,822 / SGLT2 11,86±2,51 vs 11,33±2,28 m/sec, p=0,047 / GLP1 &amp; SGLT2 12,01±2,46 vs 10,85±1,79 m/sec, p=0,021) and central and brachial systolic blood pressure than insulin or GLP-1RA. At baseline, there was a correlation of LA reservoir strain with PWV (r=−0,209, p=0,008), central SBP (r=−0,151, p=0,030), EF (r=0,214, p=0,004), GLS (r=−0,279, p=0,009). At 6 months follow up, there was a correlation of LA reservoir strain with PWV (r=0,217, p=0,003), central SBP (r=0,214, p=0,004), EF (r=−0,221, p=0,049), GLS (r=0,275, p=0,014). Conclusions Treatment with GLP-1RA, SGLT-2i, and their combination for 6 months showed a greater improvement of left atrial function compared to insulin treatment in parallel with improvement arterial and myocardial function. Funding Acknowledgement Type of funding sources: None.

A Novel Anti-Inflammatory Renoprotective Effect of GLP-1 Receptor Agonists in Type 1 Diabetes: Shifting Macrophage Polarization

A Novel Anti-Inflammatory Renoprotective Effect of GLP-1 Receptor Agonists in Type 1 Diabetes: Shifting Macrophage Polarization

Effect of GLP-1 receptor agonist, liraglutide, on muscle in spontaneously diabetic torii fatty rats

This study investigated the effect of liraglutide, a glucagon-like peptide-1 receptor agonist, on skeletal muscles in rats with type 2 diabetes. Male SDT fatty rats (8-week-old) were provided liraglutide, or insulin-hydralazine for 8 weeks; control SDT fatty rats and SD rats were administered a vehicle. At 16 weeks of age, muscle strength of limbs was significantly lower in all SDT fatty rats compared to SD rats. While cross-sectional areas of type IIb muscle fibers in extensor digitorum longus muscle were significantly lower in SDT fatty rats than in SD rats, those of type I muscle fibers in soleus were similar in all rats. In the soleus of SDT fatty rats, liraglutide led to greater citrate synthase activity and cytochrome c oxidase subunit 5 B protein expression, independently of blood glucose and blood pressure levels. Liraglutide may contribute to preservation of mitochondrial content on soleus muscle in type 2 diabetes.

Reno-Protective Effect of GLP-1 Receptor Agonists in Type1 Diabetes: Dual Action on TRPC6 and NADPH Oxidases.

Diabetic kidney disease (DKD), a serious diabetic complication, results in podocyte loss and proteinuria through NADPH oxidases (NOX)-mediated ROS production. DUOX1 and 2 are NOX enzymes that require calcium for their activation which enters renal cells through the pivotal TRPC channels. Hypoglycemic drugs such as liraglutide can interfere with this deleterious mechanism imparting reno-protection. Herein, we aim to investigate the reno-protective effect of GLP1 receptor agonist (GLP1-RA), via its effect on TRPC6 and NADPH oxidases. To achieve our aim, control or STZ-induced T1DM Sprague–Dawley rats were used. Rats were treated with liraglutide, metformin, or their combination. Functional, histological, and molecular parameters of the kidneys were assessed. Our results show that treatment with liraglutide, metformin or their combination ameliorates DKD by rectifying renal function tests and protecting against fibrosis paralleled by restored mRNA levels of nephrin, DUOX1 and 2, and reduced ROS production. Treatment with liraglutide reduces TRPC6 expression, while metformin treatment shows no effect. Furthermore, TRPC6 was found to be directly interacting with nephrin, and indirectly interacting with DUOX1, DUOX2 and GLP1-R. Our findings suggest that treatment with liraglutide may prevent the progression of diabetic nephropathy by modulating the crosstalk between TRPC6 and NADPH oxidases.

Effects of GLP-1 Receptor Agonists on Bone Mineral Density in Patients with Type 2 Diabetes Mellitus: A 52-Week Clinical Study.

Introduction Hypoglycemic drugs affect the bone quality and the risk of fractures in patients with type 2 diabetes mellitus (T2DM). We aimed to investigate the effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and insulin on bone mineral density (BMD) in T2DM. Methods In this single-blinded study, a total of 65 patients with T2DM were randomly assigned into four groups for 52 weeks: the exenatide group (n = 19), dulaglutide group (n = 19), insulin glargine group (n = 10), and placebo (n = 17). General clinical data were collected, and BMD was measured by dual-energy X-ray absorptiometry. Results Compared with baseline, the glycosylated hemoglobin (HbA1c) decreased significantly in the exenatide (8.11 ± 0.24% vs. 7.40 ± 0.16%, P = 0.007), dulaglutide (8.77 ± 0.37% vs. 7.06 ± 0.28%, P < 0.001), and insulin glargine (8.57 ± 0.24% vs. 7.23 ± 0.25%, P < 0.001) groups after treatment. In the exenatide group, the BMD of the total hip increased. In the dulaglutide group, only the BMD of the femoral neck decreased (P = 0.027), but the magnitude of decrease was less than that in the placebo group; the BMD of L1-L4, femoral neck, and total hip decreased significantly (P < 0.05) in the placebo group, while in the insulin glargine group, the BMD of L2, L4, and L1-4 increased (P < 0.05). Compared with the placebo group, the BMD of the femoral neck and total hip in the exenatide group and the insulin glargine group were increased significantly (P < 0.05); compared with the exenatide group, the BMD of L4 in the insulin glargine group was also increased (P = 0.001). Conclusions Compared with the placebo, GLP-1RAs demonstrated an increase of BMD at multiple sites of the body after treatment, which may not exacerbate the consequences of bone fragility. Therefore, GLP-1RAs might be considered for patients with T2DM. This trial is registered with ClinicalTrials.gov NCT01648582.

Glucagon-like peptide-1 in diabetes care: Can glycaemic control be achieved without nausea and vomiting?

Introduced less than two decades ago, glucagon-like peptide-1 receptor agonists rapidly reshaped the field of Type 2 diabetes mellitus (T2DM) care by providing glycaemic control in tandem with weight loss. However, FDA-approved GLP-1 receptor agonists are often accompanied by nausea and emesis and, in some lean T2DM patients, by undesired anorexia. Importantly, the hypophagic and emetic effects of GLP-1 receptor agonists are caused by activation of central GLP-1 receptors. This review summarizes two different approaches to mitigate the incidence and severity of nausea and emesis related to GLP-1 receptor agonists: conjugation with vitamin B12 , or related corrin ring-containing compounds ('corrination'), and development of dual agonists of GLP-1 receptors with glucose-dependent insulinotropic polypeptide (GIP). Such approaches could lead to the generation of GLP-1 receptor agonists with improved therapeutic efficacy, thus decreasing treatment attrition, increasing patient compliance and extending treatment to a broader population of T2DM patients. The data reviewed show that it is possible to pharmacologically separate the emetic effects of GLP-1 receptor agonists from their glucoregulatory action. LINKED ARTICLES: This article is part of a themed issue on GLP1 receptor ligands (BJP 75th Anniversary). To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.4/issuetoc.

Thiazolidinediones and Glucagon-Like Peptide-1 Receptor Agonists and the Risk of Nonalcoholic Fatty Liver Disease: A Cohort Study.

Background and AimsThiazolidinediones (TZDs) and glucagon‐like peptide‐1 (GLP‐1) receptor agonists are potential pharmacological treatment options for patients at risk of NAFLD. Therefore, we examined the association between the risk of NAFLD and the use of TZDs and GLP‐1 receptor agonists compared with the use of sulfonylureas (SUs) and insulins. Additionally, we calculated the incidence of HCC in users of TZDs and GLP‐1 receptor agonists.Approach and ResultsWe conducted a population‐based cohort study using primary care data from the Clinical Practice Research Datalink database (2007‐2018). All patients aged ≥18 with a prescription of an oral glucose‐lowering agent or GLP‐1 receptor agonist were included. The first prescription defined the start of follow‐up. The primary outcome was a new diagnosis of NAFLD. Cox proportional hazards regression was used to estimate HRs and 95% CIs of the primary outcome. Incidence rates of HCC were determined per 1,000 person‐years for all exposures. The study identified 207,367 adults with a prescription for a glucose‐lowering agent. The risk of NAFLD was lower in patients prescribed a TZD than in those prescribed an SU (adjusted HR [aHR], 0.32; 95% CI, 0.20‐0.51). No difference in risk of NAFLD was observed comparing GLP‐1 receptor agonist use with insulin use (aHR, 1.22; 95% CI, 0.91‐1.63).ConclusionsResults of our study endorse the use of TZDs for selected patients at risk of NAFLD but do not support previous findings regarding the beneficial effect of GLP‐1 receptor agonists. The low number of events in several subgroups may affect the generalizability of the current findings.

Renoprotective Effects of Incretin-Based Therapy in Diabetes Mellitus.

Glucagon-like peptide-1 (GLP-1) receptor agonists are recently discovered antidiabetic drugs with potent hypoglycemic effects. Among different mechanisms of activity, these compounds were shown to reduce blood glucose by suppression of glucagon secretion and stimulation of glucose-dependent insulin secretion. These antidiabetic agents have a minor risk of hypoglycemia and have been suggested as a second-line therapy to be added to metformin treatment to further optimize glycemic control in diabetes. More recently, scientific evidence suggests that GLP-1 receptor agonists may particularly afford protection from diabetic nephropathy through modulation of the molecular pathways involved in renal impairment and so improve renal function. This additional benefit adds further weight for these compounds to become promising drugs not only for glycemic control but also to prevent diabetic complications. In this review, we have updated evidence on the beneficial effects of GLP-1 receptor agonists on diabetic nephropathy and detailed the underlying pathophysiological mechanisms.

Effects of GLP-1 receptor agonists on myokine levels and pro-inflammatory cytokines in patients with type 2 diabetes mellitus

Background and aimsTo evaluate the change in circulating serum irisin and interleukin-6 (IL-6), in patients with type 2 diabetes mellitus (T2DM) after 6 and 12 months of GLP-1 treatment. Methods and resultsEighty-five patients with T2DM inadequately controlled with insulin or other hypoglycaemic drugs were added to dulaglutide (N° = 44) and liraglutide (N° = 41) treatment.After 6 months of GLP-1 analogues a significant decrease in BMI (p < 0.001), waist circumference (WC) (p < 0.001), fasting blood glucose (p < 0.001), HbA1c (p < 0.001), total cholesterol (p < 0.001), LDL-cholesterol (p = 0.003), triglycerides (p = 0.017), IL-6 (p = 0.045) and a significant increase in serum irisin (p < 0.001) were observed compared to baseline. After 12 months of treatment no significant differences were found compared to the levels at 6 months. The change in irisin from baseline (Δ_irisin) was significantly related to the changes in total-cholesterol (Δ_total-cholesterol) (r = −0.293; p = 0.020), while the change in IL-6 (Δ_IL-6) was significantly related to the changes in WC (Δ_WC) (r = 0.347; p = 0.006). ConclusionsAdditive treatment with GLP1-analogues results in an increase in serum circulating irisin levels and a decrease in IL-6. The post-treatment change in irisin was correlated with a decrease in total cholesterol, while the change in IL-6 was correlated with a decrease in WC.

Favorable Effects of GLP-1 Receptor Agonist against Pancreatic β-Cell Glucose Toxicity and the Development of Arteriosclerosis: “The Earlier, the Better” in Therapy with Incretin-Based Medicine

Fundamental pancreatic β-cell function is to produce and secrete insulin in response to blood glucose levels. However, when β-cells are chronically exposed to hyperglycemia in type 2 diabetes mellitus (T2DM), insulin biosynthesis and secretion are decreased together with reduced expression of insulin transcription factors. Glucagon-like peptide-1 (GLP-1) plays a crucial role in pancreatic β-cells; GLP-1 binds to the GLP-1 receptor (GLP-1R) in the β-cell membrane and thereby enhances insulin secretion, suppresses apoptotic cell death and increase proliferation of β-cells. However, GLP-1R expression in β-cells is reduced under diabetic conditions and thus the GLP-1R activator (GLP-1RA) shows more favorable effects on β-cells at an early stage of T2DM compared to an advanced stage. On the other hand, it has been drawing much attention to the idea that GLP-1 signaling is important in arterial cells; GLP-1 increases nitric oxide, which leads to facilitation of vascular relaxation and suppression of arteriosclerosis. However, GLP-1R expression in arterial cells is also reduced under diabetic conditions and thus GLP-1RA shows more protective effects on arteriosclerosis at an early stage of T2DM. Furthermore, it has been reported recently that administration of GLP-1RA leads to the reduction of cardiovascular events in various large-scale clinical trials. Therefore, we think that it would be better to start GLP-1RA at an early stage of T2DM for the prevention of arteriosclerosis and protection of β-cells against glucose toxicity in routine medical care.

Does intervention with GLP-1 receptor agonist semaglutide modulate perception of sweet taste in women with obesity: study protocol of a randomized, single-blinded, placebo-controlled clinical trial

BackgroundPreclinical studies demonstrated that glucagon-like peptide 1 (GLP-1) is locally synthesized in taste bud cells and that GLP-1 receptor exists on the gustatory nerves in close proximity to GLP-1-containing taste bud cells. This local paracrine GLP-1 signalling seems to be specifically involved in the perception of sweets. However, the role of GLP-1 in taste perception remains largely unaddressed in clinical studies. Whether any weight-reducing effects of GLP-1 receptor agonists are mediated through the modulation of taste perception is currently unknown.Methods and analysisThis is an investigator-initiated, randomized single-blind, placebo-controlled clinical trial. We will enrol 30 women with obesity and polycystic ovary syndrome (PCOS). Participants will be randomized in a 1:1 ratio to either semaglutide 1.0 mg or placebo for 16 weeks. The primary endpoints are alteration of transcriptomic profile of tongue tissue as changes in expression level from baseline to follow-up after 16 weeks of treatment, measured by RNA sequencing, and change in taste sensitivity as detected by chemical gustometry. Secondary endpoints include change in neural response to visual food cues and to sweet-tasting substances as assessed by functional MRI, change in body weight, change in fat mass and change in eating behaviour and food intake.DiscussionThis is the first study to investigate the role of semaglutide on taste perception, along with a neural response to visual food cues in reward processing regions. The study may identify the tongue and the taste perception as a novel target for GLP-1 receptor agonists.Ethics and disseminationsThe study has been approved by the Slovene National Medical Ethics Committee and will be conducted in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. Results will be submitted for publication in an international peer-reviewed scientific journal.Trial registrationClinicalTrials.govNCT04263415. Retrospectively registered on 10 February 2020