Neuroprotective effects of liraglutide for stroke model of rats. Int J Mol Sci. 2013;14:21513-21524. [PMID: 24177570 PMCID: PMC3856019 DOI: 10.3390/ijms141121513]

GLP-1 programs the neurovascular landscape

Readily available nutrient-rich foods exploit our inherent drive to overconsume, creating an environment of overnutrition. This transformative setting has led to persistent health issues, such as obesity and metabolic syndrome. The development of glucagon-like peptide-1 receptor (GLP-1R) agonists reveals our ability to pharmacologically manage weight and address metabolic conditions. Obesity is directly linked to chronic low-grade inflammation, connecting our metabolic environment to neurodegenerative diseases. GLP-1R agonism in curbing obesity, achieved by impacting appetite and addressing associated metabolic defects, is revealing additional benefits extending beyond weight loss. Whether GLP-1R agonism directly impacts brain health or does so indirectly through improved metabolic health remains to be elucidated. In exploring the intricate connection between obesity and neurological conditions, recent literature suggests that GLP-1R agonism may have the capacity to shape the neurovascular landscape. Thus, GLP-1R agonism emerges as a promising strategy for addressing the complex interplay between metabolic health and cognitive well-being.

Peptide OM-LV20 promotes arteriogenesis induced by femoral artery ligature via the miR-29b-3p/VEGFA axis

BACKGROUND AND AIMS

Therapeutic arteriogenesis is a promising direction for the treatment of ischemic disease caused by atherosclerosis. However, pharmacological or biological approaches to stimulate functional collateral vessels are not yet available. Identifying new drug targets to promote and explore the underlying mechanisms for therapeutic arteriogenesis is necessary.

METHODS

Peptide OM-LV20 (20 ng/kg) was administered for 7 consecutive days on rat hindlimb ischemia model, collateral vessel growth was assessed by H&E staining, liquid latex perfusion, and specific immunofluorescence. In vitro, we detected the effect of OM-LV20 on human umbilical vein endothelial cells (HUVEC) proliferation and migration. After transfection, we performed quantitative real-time polymerase chain reaction, in situ-hybridization and dual luciferase reporters to assessed effective miRNAs and target genes. The proteins related to downstream signaling pathways were detected by Western blot.

RESULTS

OM-LV20 significantly increased visible collateral vessels and endothelial nitric oxide synthase (eNOS), together with enhanced inflammation cytokine and monocytes/macrophage infiltration in collateral vessels. In vitro, we defined a novel microRNA (miR-29b-3p), and its inhibition enhanced proliferation and migration of HUVEC, as well as the expression of vascular endothelial growth factor A (VEGFA). OM-LV20 also promoted migration and proliferation of HUVEC, and VEGFA expression was mediated via inhibition of miR-29b-3p. Furthermore, OM-LV20 influenced the protein levels of VEGFR2 and phosphatidylinositol3-kinase (PI3K)/AKT and eNOS in vitro and invivo.

CONCLUSIONS

Our data indicated that OM-LV20 enhanced arteriogenesis via the miR-29b-3p/VEGFA/VEGFR2-PI3K/AKT/eNOS axis, and highlighte the application potential of exogenous peptide molecular probes through miRNA, which could promote effective therapeutic arteriogenesis in ischemic conditions.

The Effect of Liraglutide on Axon Regeneration and Functional Recovery after Peripheral Nerve Lesion

Peripheral nerve injuries inflict severe consequences, necessitating innovative therapeutic strategies. This study investigates the potential of liraglutide, a glucagon-like peptide-1 receptor agonist, in mitigating the consequences of peripheral nerve injury. The existing treatment methods for such injuries underscore the importance of ongoing translational research efforts. Thirty adult Wistar rats underwent sciatic nerve dissection and repair surgery. The nerves were surgically transected using micro scissors at a precise location located 1.5 cm proximal to the trifurcation site. The study included a control group and two experimental groups, one treated with saline (placebo group) and the other with liraglutide (experimental group) for 12 weeks. Motor function, electromyography (EMG), and biochemical and histopathological analyses were performed after 12 weeks of treatment. Electrophysiological assessments revealed that liraglutide improved the compound muscle action potential (CMAP) amplitude and motor function compared to the saline-treated group. Histological and immunohistochemical analyses demonstrated increased NGF expression, total axon number, and diameter and reduced fibrosis in the liraglutide group. Biochemical analyses illustrated liraglutide's antioxidative properties, evidenced by reduced malondialdehyde (MDA) levels. Galectin-3 levels were suppressed and GDF-11 levels were modulated by liraglutide, indicating anti-inflammatory and anti-apoptotic effects. Liraglutide is a promising therapeutic intervention for peripheral nerve injuries, promoting functional recovery and histopathological improvement. Its multifaceted positive impact, beyond glycemic control, suggests constructive effects on the acute and chronic inflammatory processes associated with peripheral neuropathy. These findings warrant further research to elucidate molecular mechanisms and facilitate clinical translation. The study contributes valuable insights to the growing understanding of GLP-1 receptor agonists' neuroprotective properties in the context of peripheral nerve injuries.

Cardiovascular efficacy and safety of antidiabetic agents: A network meta-analysis of randomized controlled trials

AIM

An important characteristic of glucose-lowering therapies (GLTs) is their ability to prevent cardiovascular complications. We aimed to investigate the cardiorenal efficacy and general safety of GLTs.

MATERIALS AND METHODS

Multicentre, randomized, clinical trials that included over 100 participants comparing antidiabetic agents with a placebo or a different antidiabetic agent and reporting major adverse cardiovascular events (MACEs), or primarily reporting heart failure, were searched in the PubMed, Embase and Cochrane databases. Data were extracted independently for random-effects network meta-analyses to calculate the hazard ratio estimates.

RESULTS

Forty-three trials that compared nine types of GLTs were included in the present analysis. The risk of three-point MACE was reduced in the presence of glucagon-like peptide-1 receptor agonists (GLP-1 RAs), sodium-glucose cotransporter-2 inhibitors (SGLT-2is) and thiazolidinedione therapy compared with the placebo, dipeptidyl peptidase-4 inhibitors, or insulin therapy. GLP-1 RAs were favourable for cardiovascular and renal outcomes. SGLT-2is reduced renal outcomes by ~40%, which was superior to other GLTs. Thiazolidinedione therapy increased the risks of hospitalization for heart failure and had no benefits on mortality. Adverse events leading to drug discontinuation were higher with GLP-1 RAs and thiazolidinediones than placebo.

CONCLUSIONS

GLP-1 RAs, SGLT-2is and thiazolidinediones reduced three-point MACE compared with other GLTs. Each drug class had unique advantages and disadvantages.

Neuroprotective effects of glucose-lowering drugs in rat focal brain ischemia-reperfusion model

Background. Ischemic stroke is one of the leading causes of death in patients with type 2 diabetes mellitus (DM). According to the results of clinical and experimental studies, the ability of glucagon-like peptide-1 receptor agonists (GLP-1RA) to reduce the risk and severity of stroke in DM has been proven; data on the sodium-glucose cotransporter-2 inhibitors (SGLT-2i) effect are scarce. There has been no direct comparative study of the GLP-1RA and SGLT-2i neuroprotective effect.

Objective. To evaluate and to compare the effect of GLP-1RA of varying duration of action and SGLT-2i of varying selectivity on the neurological deficit severity and the brain damage volume in a transient focal brain ischemia model in rats without DM.

Design and methods. Male Wistar rats were divided into groups (n = 10 each) depending on the therapy received: “EMPA” (empagliflozin per os 2 mg/kg once daily), “CANA” (canagliflozin per os 25 mg/kg once daily), “LIRA” (liraglutide 1 mg/kg s. c. once daily), “DULA” (dulaglutide 0,12 mg/kg s. c. every 72 hours), “SEMA” (semaglutide 0,012 mg /kg s. c. once daily), “MET” (metformin per os 200 mg/kg once daily — comparison group), “Control” (administration of 0,9 % NaCl solution s. c. once daily). After 7 days, all groups underwent transient focal 30-minute filament middle cerebral artery occlusion. After 48 hours of reperfusion, neurological deficit was assessed using the Garcia scale, then the brain was collected and sections were stained with 1 % triphenyltetrazolium chloride solution to calculate the damage volume.

Results. Neurological deficit severity in the “LIRA” (14,50 (12,25; 15,25) points) and “SEMA” (14,00 (13,50; 18,00) points) groups was significantly less than in the “Control” group (11.00 (6,75; 12,00) points). The use of both SGLT-2i, as well as metformin, had no effect on the neurological status. At the same time, therapy with all study drugs had an infarct-limiting effect, compared with the “Control” group (damage volume 24,50 (14,69; 30,12) % of the total brain volume). At the same time, the brain damage volume in the “MET” group (12,93 (6,65, 26,66) %) was greater than that in the “EMPA” (6,08 (2,97, 7,63) %), “CANA” (5,11 (3,96; 8,34) %), “LIRA” (3,40 (2,09; 8,08) %), “DULA” (4,37 (2,72; 5,40) %), “SEMA” (5,19 (4,11; 7,83) %) groups.

Conclusions. SGLT-2i of varying selectivity and GLP-1RA of varying duration of action have a similar infarct-limiting effect in acute experimental brain ischemia. At the same time, GLP-1RA neuroprotective potential is higher, as it is characterized by an additional positive effect on the neurological status.

Neuroprotective Peptides and New Strategies for Ischemic Stroke Drug Discoveries

Ischemic stroke continues to be one of the leading causes of death and disability in the adult population worldwide. The currently used pharmacological methods for the treatment of ischemic stroke are not effective enough and require the search for new tools and approaches to identify therapeutic targets and potential neuroprotectors. Today, in the development of neuroprotective drugs for the treatment of stroke, special attention is paid to peptides. Namely, peptide action is aimed at blocking the cascade of pathological processes caused by a decrease in blood flow to the brain tissues. Different groups of peptides have therapeutic potential in ischemia. Among them are small interfering peptides that block protein-protein interactions, cationic arginine-rich peptides with a combination of various neuroprotective properties, shuttle peptides that ensure the permeability of neuroprotectors through the blood-brain barrier, and synthetic peptides that mimic natural regulatory peptides and hormones. In this review, we consider the latest achievements and trends in the development of new biologically active peptides, as well as the role of transcriptomic analysis in identifying the molecular mechanisms of action of potential drugs aimed at the treatment of ischemic stroke.

Synergistic therapeutic effects of intracerebral transplantation of human modified bone marrow-derived stromal cells (SB623) and voluntary exercise with running wheel in a rat model of ischemic stroke

BACKGROUND

Mesenchymal stromal cell (MSC) transplantation therapy is a promising therapy for stroke patients. In parallel, rehabilitation with physical exercise could ameliorate stroke-induced neurological impairment. In this study, we aimed to clarify whether combination therapy of intracerebral transplantation of human modified bone marrow-derived MSCs, SB623 cells, and voluntary exercise with running wheel (RW) could exert synergistic therapeutic effects on a rat model of ischemic stroke.

METHODS

Wistar rats received right transient middle cerebral artery occlusion (MCAO). Voluntary exercise (Ex) groups were trained in a cage with RW from day 7 before MCAO. SB623 cells (4.0 × 105 cells/5 μl) were stereotactically injected into the right striatum at day 1 after MCAO. Behavioral tests were performed at day 1, 7, and 14 after MCAO using the modified Neurological Severity Score (mNSS) and cylinder test. Rats were euthanized at day 15 after MCAO for mRNA level evaluation of ischemic infarct area, endogenous neurogenesis, angiogenesis, and expression of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). The rats were randomly assigned to one of the four groups: vehicle, Ex, SB623, and SB623 + Ex groups.

RESULTS

SB623 + Ex group achieved significant neurological recovery in mNSS compared to the vehicle group (p < 0.05). The cerebral infarct area of SB623 + Ex group was significantly decreased compared to those in all other groups (p < 0.05). The number of BrdU/Doublecortin (Dcx) double-positive cells in the subventricular zone (SVZ) and the dentate gyrus (DG), the laminin-positive area in the ischemic boundary zone (IBZ), and the mRNA level of BDNF and VEGF in SB623 + Ex group were significantly increased compared to those in all other groups (p < 0.05).

CONCLUSIONS

This study suggests that combination therapy of intracerebral transplantation SB623 cells and voluntary exercise with RW achieves robust neurological recovery and synergistically promotes endogenous neurogenesis and angiogenesis after cerebral ischemia, possibly through a mechanism involving the up-regulation of BDNF and VEGF.

Risk of stroke and retinopathy during GLP-1 receptor agonist cardiovascular outcome trials: An eight RCTs meta-analysis

Purpose

To explore the risk of stroke (including ischemic and hemorrhagic stroke) in type 2 diabetes mellitus treated with glucagon-like peptide 1 receptor agonist (GLP-1RA) medication according to data from the Cardiovascular Outcome Trials(CVOT).

Methods

Randomized controlled trials (RCT) on GLP-1RA therapy and cardiovascular outcomes in type 2 diabetics published in full-text journal databases such as Medline (via PubMed), Embase, Clinical Trials.gov, and the Cochrane Library from establishment to May 1, 2022 were searched. We assess the quality of individual studies by using the Cochrane risk of bias algorithm. RevMan 5.4.1 software was use for calculating meta- analysis.

Results

A total of 60,081 randomized participants were included in the data of these 8 GLP-1RA cardiovascular outcomes trials. Pooled analysis reported statistically significant effect on total stroke risk[RR=0.83, 95%CI(0.73, 0.95), p=0.005], and its subtypes such as ischemic Stroke [RR=0.83, 95%CI(0.73, 0.95), p=0.008] from treatment with GLP-1RA versus placebo, and have no significant effect on the risk of hemorrhagic stroke[RR=0.83, 95%CI(0.57, 1.20), p=0.31] and retinopathy [RR=1.54, 95%CI(0.74, 3.23), p=0.25].

Conclusion

GLP-1RA significantly reduces the risk of ischemic stroke in type 2 diabetics with cardiovascular risk factors.

Type 2 diabetes

Type 2 diabetes accounts for nearly 90% of the approximately 537 million cases of diabetes worldwide. The number affected is increasing rapidly with alarming trends in children and young adults (up to age 40 years). Early detection and proactive management are crucial for prevention and mitigation of microvascular and macrovascular complications and mortality burden. Access to novel therapies improves person-centred outcomes beyond glycaemic control. Precision medicine, including multiomics and pharmacogenomics, hold promise to enhance understanding of disease heterogeneity, leading to targeted therapies. Technology might improve outcomes, but its potential is yet to be realised. Despite advances, substantial barriers to changing the course of the epidemic remain. This Seminar offers a clinically focused review of the recent developments in type 2 diabetes care including controversies and future directions.

Protection against stroke with glucagon-like peptide-1 receptor agonists: a comprehensive review of potential mechanisms

Several randomized controlled trials have demonstrated the benefits of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on ischemic stroke in patients with diabetes. In this review, we summarize and discuss the potential mechanisms of stroke protection by GLP-1RAs. GLP-1RAs exert multiple anti-atherosclerotic effects contributing to stroke prevention such as enhanced plaque stability, reduced vascular smooth muscle proliferation, increased nitric oxide, and improved endothelial function. GLP-1RAs also lower the risk of stroke by reducing traditional stroke risk factors including hyperglycemia, hypertension, and dyslipidemia. Independently of these peripheral actions, GLP-1RAs show direct cerebral effects in animal stroke models, such as reduction of infarct volume, apoptosis, oxidative stress, neuroinflammation, excitotoxicity, blood-brain barrier permeability, and increased neurogenesis, neuroplasticity, angiogenesis, and brain perfusion. Despite these encouraging findings, further research is still needed to understand more thoroughly the mechanisms by which GLP-1RAs may mediate stroke protection specifically in the human diabetic brain.

SGLT-2 inhibitors and GLP-1 receptor agonists in metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic condition that affects nearly one billion people globally, characterized by triacylglycerol accumulation in the liver as a consequence of metabolic abnormalities (obesity and impaired glucose regulation). Low-grade inflammation, oxidative stress, mitochondrial dysfunction, and dysbiosis in gut microbiota are involved in the etiology of MAFLD, and both cardiovascular events and hepatic complications are the long-term consequences. In the absence of approved therapies for this condition, sodium-glucose cotransporter 2 inhibitors (SGLT-2 Is) and glucagon-like peptide 1 receptor agonists (GLP-1 RAs) have the specific advantage of lowering body weight and providing cardiovascular benefits. Here, we discuss potential roles for SGLT-2 Is and GLP-1 RAs in the prevention and treatment of intrahepatic triacylglycerol accumulation and associated inflammation and/or fibrosis.

Neuroprotective Mechanisms of Glucagon-Like Peptide-1-Based Therapies in Ischemic Stroke: An Update Based on Preclinical Research

The public and social health burdens of ischemic stroke have been increasing worldwide. Hyperglycemia leads to a greater risk of stroke. This increased risk is commonly seen among patients with diabetes and is in connection with worsened clinical conditions and higher mortality in patients with acute ischemic stroke (AIS). Therapy for stroke focuses mainly on restoring cerebral blood flow (CBF) and ameliorating neurological impairment caused by stroke. Although choices of stroke treatment remain limited, much advance have been achieved in assisting patients in recovering from ischemic stroke, along with progress of recanalization therapy through pharmacological and mechanical thrombolysis. However, it is still necessary to develop neuroprotective therapies for AIS to protect the brain against injury before and during reperfusion, prolong the time window for intervention, and consequently improve neurological prognosis. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are broadly regarded as effective drugs in the treatment of type 2 diabetes mellitus (T2DM). Preclinical data on GLP-1 and GLP-1 RAs have displayed an impressive neuroprotective efficacy in stroke, Parkinson's disease (PD), Alzheimer's disease (AD), Amyotrophic lateral sclerosis (ALS), and other neurodegenerative diseases. Based on the preclinical studies in the past decade, we review recent progress in the biological roles of GLP-1 and GLP-1 RAs in ischemic stroke. Emphasis will be placed on their neuroprotective effects in experimental models of cerebral ischemia stroke at cellular and molecular levels.

Remitting Seronegative Symmetrical Synovitis with Pitting Edema Syndrome Worsen after the Administration of Dulaglutide

Remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome is characterized by symmetrical polyarthritis and limb pitting edema. Although the detailed mechanisms of this syndrome have not been clearly understood, some agents including dipeptidyl peptidase-4 inhibitors have been reported to induce RS3PE syndrome. However, glucagon-like peptide-1 (GLP-1) analogues have not been reported to be associated with this syndrome. A 91-year-old woman was admitted to our hospital with complaints of severe polyarthritis and limb edema. She was diagnosed with RS3PE syndrome. Oral prednisolone improved her symptoms. However, her symptoms worsened after the administration of dulaglutide, with elevated serum inflammatory markers. Discontinuation of dulaglutide without additional treatment improved her symptoms and laboratory findings. This case might indicate the possibility of development and worsening of RS3PE syndrome caused after GLP-1 analogue.

Non-peptide agonists and positive allosteric modulators of glucagon-like peptide-1 receptors: Alternative approaches for treatment of Type 2 diabetes

Glucagon-like peptide-1 (GLP-1) receptors belong to the pharmaceutically important Class B family of GPCRs and are involved in many biologically significant signalling pathways. Its incretin peptide ligand GLP-1 analogues are effective treatments for Type 2 diabetes. Although developing non-peptide low MW drugs targeting GLP-1 receptors remains elusive, considerable progress has been made in discovering non-peptide agonists and positive allosteric modulators (PAMs) of GLP-1 receptors with demonstrated efficacy. Many of these compounds induce biased signalling in GLP-1 receptor-mediated functional pathways. High-quality structures of GLP-1 receptors in both inactive and active states have been reported, revealing detailed molecular interactions between GLP-1 receptors and non-peptide agonists or PAMs. These progresses raise the exciting possibility of developing non-peptide drugs of GLP-1 receptors as alternative treatments for Type 2 diabetes. The insight into the interactions between the receptor and the non-peptide ligand is also useful for developing non-peptide ligands targeting other Class B GPCRs. 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.

Exendin-4 Preserves Blood-Brain Barrier Integrity via Glucagon-Like Peptide 1 Receptor/Activated Protein Kinase-Dependent Nuclear Factor-Kappa B/Matrix Metalloproteinase-9 Inhibition After Subarachnoid Hemorrhage in Rat

In this study, we investigated the role of Exendin-4 (Ex-4), a glucagon-like peptide 1 receptor (GLP-1R) agonist, in blood-brain barrier (BBB) disruption after subarachnoid hemorrhage (SAH) in rats. The endovascular perforation model of SAH was performed in Sprague-Dawley rats. Ex-4 was intraperitoneally injected 1 h after SAH induction. To elucidate the underlying molecular mechanism, small interfering ribonucleic acid (siRNA) for GLP-1R and Dorsomorphin, a specific inhibitor of adenosine monophosphate-activated protein kinase (AMPK), were intracerebroventricularly injected 48 h before induction of SAH correspondingly. Immunofluorescence results supported GLP-1R expressed on the endothelial cells of microvessels in the brain after SAH. Administration of Ex-4 significantly reduced brain water content and Evans blue extravasation in both hemispheres, which improved neurological scores at 24 h after SAH. In the mechanism study, Ex-4 treatment significantly increased the expression of GLP-1R, p-AMPK, IκB-α, Occludin, and Claudin-5, while the expression of p-nuclear factor-kappa B (NF-κB) p65, matrix metalloproteinase-9 (MMP-9), and albumin was significantly decreased. The effects of Ex-4 were reversed by the intervention of GLP-1R siRNA or Dorsomorphin, respectively. In conclusion, Ex-4 could preserve the BBB integrity through GLP-1R/AMPK-dependent NF-κB/MMP-9 inhibition after SAH, which should be further investigated as a potential therapeutic target in SAH.

Liraglutide protects against lethal renal ischemia-reperfusion injury by inhibiting high-mobility group box 1 nuclear-cytoplasmic translocation and release

Liraglutide, a glucagon-like peptide-1 receptor (GLP-1R) agonist, has been reported to exert protective effects against myocardial, hepatic, and gastric ischemia-reperfusion injury (IRI), but whether it can protect against renal IRI remains unknown. Here, a lethal renal IRI model was established with a 100% mortality rate in untreated mice. Treatment with liraglutide involving a regimen of multiple doses resulted in 100% survival, remarkable preservation of renal function, a significant reduction in pathological damage, and blunted upregulation of TNF-α, IL-1β, IL-6, MCP-1, TLR-2, TLR-4, and RAGE mRNA. We found that liraglutide treatment dramatically inhibited ischemia-induced nucleocytoplasmic translocation and release of HMGB1. This inhibition was associated with a marked decrease (~ 60%) in nuclear histone acetyltransferase activity. In addition, the protective effects of liraglutide on renal IRI were largely abolished by the administration of exogenous HMGB1. When the GLP-1R antagonist exendin (9-39) was given to mice before each liraglutide administration, or GLP-1R-/- mice were used for the renal IRI experiments, the protective effect of liraglutide on renal IRI was partially reversed. Moreover, liraglutide pretreatment significantly inhibited HMGB1 nucleocytoplasmic translocation during hypoxic culture of HK-2 cells in vitro, but the addition of exendin (9-39) significantly eliminated this inhibition. We demonstrate here that liraglutide can exert a strong protective effect on lethal renal IRI in mice. This protection appears to be related to the inhibition of HMGB1 nuclear-cytoplasmic translocation and release and partially depends on GLP-1R. Thus, liraglutide may be therapeutically useful for the clinical prevention and treatment of organ IRI.

Analysis of the neuroprotective effect of GLP-1 receptor agonist peptide on cerebral ischemia-reperfusion injury by Quantitative Proteomics Mass Spectrometry

OBJECTIVE

The pathological characteristics of cerebral ischemia-reperfusion injury (CIRI) are complex, and the mechanism involved remains unknown. The treatment for CIRI has become an increasingly important challenge in the clinic, prompting us to explore the mechanism of CIRI. It was reported that GLP-1 receptor agonist, Liraglutide, exhibited alleviating effects on CIRI. The previous findings suggested that the administration of Liraglutide in rodents results in the attenuation of the infarct volume following ischemia-reperfusion injury by mediating the reactive oxygen species, apoptotic and necroptotic pathways.

METHODS

Here, a proteomic study was performed aiming to clarify the physiological protection role of GLP-1 receptor agonist during the development of CIRI in MCAO mice. This proteomic investigations is contributed to reveal the mechanism associated with the treatment of GLP-1 receptor agonist in MCAO mice.

RESULTS

The results indicated that the occurrence of ischemia-reperfusion led to complex pathological processes, including inflammation, necroptosis and apoptosis. The treatment of Liraglutide significantly reduced the infract volume resulted from ischemia reperfusion injury. The proteomic data revealed that the administration of Liraglutide in MCAO mice induced the various effects on proteins expression level and phosphorylation.

CONCLUSIONS

The findings in this study was beneficial for identifying the novel therapeutic target for the treatment of ischemia reperfusion.

Association between fasting blood glucose and intracranial cerebral artery stenosis: a secondary analysis based on a retrospective cross-sectional study in Korean adults

AIMS

Diabetes mellitus (DM) is one of the main risk factors for intracranial cerebral artery stenosis (ICAS), and fasting blood glucose (FBG) might be an effective predictor of ICAS. However, there are a few studies revealing the relationship between FBG and ICAS. We aim to identify the association between FBG and ICAS in Koreans.

METHODS

This was a secondary study based on a cross-sectional study. A total of 1011 Korean individuals who were asymptomatic but with high cerebrovascular risk underwent an examination in a Korean medical centre from March 2008 to December 2014. The main measure was FBG, while the main outcome was ICAS. Multivariate logistic regression analyses of FBG in the presence of ICAS were performed to examine the potential association. The author used the data provided by the paper "Association between Serum Alkaline Phosphatase Level and Cerebral Small Vessel Disease" for secondary analysis.

RESULTS

The average age of the participants was 64.2 ± 9.1 years old, and approximately 35% of them were males. There were 24 participants suffering from ICAS in the first FBG tertile (< 5.4 mmol/L), while there were 26 in the second tertile (5.4-7.1 mmol/L) and 50 in the third tertile (≥ 7.1 mmol/L). The non-adjusted relationship between FBG and ICAS was positive. After controlling potential confounders, the association of FPG with ICAS remained positive, as well as in subgroups analysis, such as age, sex, hypertension, diabetes mellitus, hyperlipidaemia and COAD. The association remained unchanged after adjusted sex, age, hypertension, DM, uric acid, hyperlipidaemia, and CAOD (OR = 1.08, 95% CI = 1.02-1.15). The analyses also showed that the positive association was statistically significant (P < 0.05) among individuals without diabetes.

CONCLUSIONS

This study showed a positive relationship between FBG and ICAS, which suggests that clinicians may need to be simultaneously concerned about FBG and ICAS.

Eyeballing stroke: Blood flow alterations in the eye and visual impairments following transient middle cerebral artery occlusion in adult rats

Middle cerebral artery occlusion in rodents remains a widely used model of ischemic stroke. Recently, we reported the occurrence of retinal ischemia in animals subjected to middle cerebral artery occlusion, owing in part to the circulatory juxtaposition of the ophthalmic artery to the middle cerebral artery. In this study, we examined the eye hemodynamics and visual deficits in middle cerebral artery occlusion-induced stroke rats. The brain and eye were evaluated by laser Doppler at baseline (prior to middle cerebral artery occlusion), during and after middle cerebral artery occlusion. Retinal function-relevant behavioral and histological outcomes were performed at 3 and 14 days post-middle cerebral artery occlusion. Laser Doppler revealed a typical reduction of at least 80% in the ipsilateral frontoparietal cortical area of the brain during middle cerebral artery occlusion compared to baseline, which returned to near-baseline levels during reperfusion. Retinal perfusion defects closely paralleled the timing of cerebral blood flow alterations in the acute stages of middle cerebral artery occlusion in adult rats, characterized by a significant blood flow defect in the ipsilateral eye with at least 90% reduction during middle cerebral artery occlusion compared to baseline, which was restored to near-baseline levels during reperfusion. Moreover, retinal ganglion cell density and optic nerve depth were significantly decreased in the ipsilateral eye. In addition, the stroke rats displayed eye closure. Behavioral performance in a light stimulus-mediated avoidance test was significantly impaired in middle cerebral artery occlusion rats compared to control animals. In view of visual deficits in stroke patients, closely monitoring of brain and retinal perfusion via laser Doppler measurements and examination of visual impairments may facilitate the diagnosis and the treatment of stroke, including retinal ischemia.

Glucagon-like peptide-1 receptor agonists as neuroprotective agents for ischemic stroke: a systematic scoping review

Stroke mortality and morbidity is expected to rise. Despite considerable recent advances within acute ischemic stroke treatment, scope remains for development of widely applicable neuroprotective agents. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), originally licensed for the management of Type 2 Diabetes Mellitus, have demonstrated pre-clinical neuroprotective efficacy in a range of neurodegenerative conditions. This systematic scoping review reports the pre-clinical basis of GLP-1RAs as neuroprotective agents in acute ischemic stroke and their translation into clinical trials. We included 35 pre-clinical studies, 11 retrospective database studies, 7 cardiovascular outcome trials and 4 prospective clinical studies. Pre-clinical neuroprotection was demonstrated in normoglycemic models when administration was delayed by up to 24 h following stroke induction. Outcomes included reduced infarct volume, apoptosis, oxidative stress and inflammation alongside increased neurogenesis, angiogenesis and cerebral blood flow. Improved neurological function and a trend towards increased survival were also reported. Cardiovascular outcomes trials reported a significant reduction in stroke incidence with semaglutide and dulaglutide. Retrospective database studies show a trend towards neuroprotection. Prospective interventional clinical trials are on-going, but initial indicators of safety and tolerability are favourable. Ultimately, we propose that repurposing GLP-1RAs is potentially advantageous but appropriately designed trials are needed to determine clinical efficacy and cost-effectiveness.

GLP-1 Receptor Agonists: Beyond Their Pancreatic Effects

Glucagon like peptide-1 (GLP-1) is an incretin secretory molecule. GLP-1 receptor agonists (GLP-1RAs) are widely used in the treatment of type 2 diabetes (T2DM) due to their attributes such as body weight loss, protection of islet β cells, promotion of islet β cell proliferation and minimal side effects. Studies have found that GLP-1R is widely distributed on pancreatic and other tissues and has multiple biological effects, such as reducing neuroinflammation, promoting nerve growth, improving heart function, suppressing appetite, delaying gastric emptying, regulating blood lipid metabolism and reducing fat deposition. Moreover, GLP-1RAs have neuroprotective, anti-infectious, cardiovascular protective, and metabolic regulatory effects, exhibiting good application prospects. Growing attention has been paid to the relationship between GLP-1RAs and tumorigenesis, development and prognosis in patient with T2DM. Here, we reviewed the therapeutic effects and possible mechanisms of action of GLP-1RAs in the nervous, cardiovascular, and endocrine systems and their correlation with metabolism, tumours and other diseases.

Blood-Brain Barrier Damage in Ischemic Stroke and Its Regulation by Endothelial Mechanotransduction

Ischemic stroke, a major cause of mortality in the United States, often contributes to disruption of the blood-brain barrier (BBB). The BBB along with its supportive cells, collectively referred to as the “neurovascular unit,” is the brain’s multicellular microvasculature that bi-directionally regulates the transport of blood, ions, oxygen, and cells from the circulation into the brain. It is thus vital for the maintenance of central nervous system homeostasis. BBB disruption, which is associated with the altered expression of tight junction proteins and BBB transporters, is believed to exacerbate brain injury caused by ischemic stroke and limits the therapeutic potential of current clinical therapies, such as recombinant tissue plasminogen activator. Accumulating evidence suggests that endothelial mechanobiology, the conversion of mechanical forces into biochemical signals, helps regulate function of the peripheral vasculature and may similarly maintain BBB integrity. For example, the endothelial glycocalyx (GCX), a glycoprotein-proteoglycan layer extending into the lumen of bloods vessel, is abundantly expressed on endothelial cells of the BBB and has been shown to regulate BBB permeability. In this review, we will focus on our understanding of the mechanisms underlying BBB damage after ischemic stroke, highlighting current and potential future novel pharmacological strategies for BBB protection and recovery. Finally, we will address the current knowledge of endothelial mechanotransduction in BBB maintenance, specifically focusing on a potential role of the endothelial GCX.

GLP-1R Agonist Liraglutide Attenuates Inflammatory Reaction and Neuronal Apoptosis and Reduces Early Brain Injury After Subarachnoid Hemorrhage in Rats

Liraglutide, one of the glucagon-like peptide 1 receptor (GLP-1R) agonists, has been demonstrated to protect brain damage produced by ischemic stroke. However, it remains unknown whether liraglutide attenuates early brain injury after subarachnoid hemorrhage. The present study was performed to explore the effect of liraglutide on early brain injury after subarachnoid hemorrhage in rats, and further investigate the potential mechanisms. Sprague-Dawley rats underwent subarachnoid hemorrhage (SAH) by endovascular perforation, then received subcutaneous injection with liraglutide (50 or 100 μg/kg) or vehicle after 2 and 12 h of SAH. SAH grading, neurological scores, brain water content, and Evans Blue extravasation were measured 24 h after SAH. Immunofluorescent staining was performed to detect the extent of microglial activation in rat brain 24 h after SAH. TUNEL staining was performed to evaluate neuronal apoptosis in rat brain of SAH. Expression of GLP-1R, cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), Bcl-2, Bax, and cleaved caspase-3 in rat brain were determined by western blot. Expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in rat brain was assessed by ELISA. Neurological dysfunction, brain water content, Evans Blue extravasation, microglial activation, and neuronal apoptosis were significantly reduced by GLP-1R agonist liraglutide. Expression of GLP-1R in rat brain was decreased after SAH, which is significantly elevated by liraglutide. Expression of inflammatory mediates like COX-2, iNOS, TNF-α, and IL-1β was increased after SAH, which were significantly inhibited by liraglutide. Furthermore, SAH caused the elevated expression of pro-apoptotic factors Bax and cleaved caspase-3 in rat brain, both of which were inhibited by liraglutide. In addition, liraglutide reversed the expression of anti-apoptotic protein Bcl-2. Our results demonstrated that liraglutide reduces early brain injury and attenuates inflammatory reaction and neuronal apoptosis in rats of SAH. Liraglutide provides neuroprotection against SAH, which might be associated with the inhibition of inflammation and apoptosis.

Involvement of TGF-β and Autophagy Pathways in Pathogenesis of Diabetes: A Comprehensive Review on Biological and Pharmacological Insights

Despite recent advancements in clinical drugs, diabetes treatment still needs further progress. As such, ongoing research has attempted to determine the precise molecular mechanisms of the disorder. Specifically, evidence supports that several signaling pathways play pivotal roles in the development of diabetes. However, the exact molecular mechanisms of diabetes still need to be explored. This study examines exciting new hallmarks for the strict involvement of autophagy and TGF-β signaling pathways in the pathogenesis of diabetes and the design of novel therapeutic strategies. Dysregulated autophagy in pancreatic β cells due to hyperglycemia, oxidative stress, and inflammation is associated with diabetes and accompanied by dysregulated autophagy in insulin target tissues and the progression of diabetic complications. Consequently, several therapeutic agents such as adiponectin, ezetimibe, GABA tea, geniposide, liraglutide, guava extract, and vitamin D were shown to inhibit diabetes and its complications through modulation of the autophagy pathway. Another pathway, TGF-β signaling pathway, appears to play a part in the progression of diabetes, insulin resistance, and autoimmunity in both type 1 and 2 diabetes and complications in diabetes. Subsequently, drugs that target TGF-β signaling, especially naturally derived ones such as resveratrol, puerarin, curcumin, hesperidin, and silymarin, as well as Propolis, Lycopus lucidus, and Momordica charantia extracts, may become promising alternatives to current drugs in diabetes treatment. This review provides keen insights into novel therapeutic strategies for the medical care of diabetes.

The treament of hyperglycemia in acute ischemic stroke with incretin-based drugs

Stroke is a major cause of mortality and morbidity worldwide. Considerable experimental and clinical evidence suggests that both diabetes mellitus (DM) and post-stroke hyperglycemia are associated with increased mortality rate and worsened clinical conditions in acute ischemic stroke (AIS) patients. Insulin treatment does not seem to provide convincing benefits for these patients, therefore prompting a change of strategy. The selective agonists of Glucagon-Like Peptide-1 Receptors (GLP-1Ras) and the Inhibitors of Dipeptidyl Peptidase-IV (DPP-IVIs, gliptins) are two newer classes of glucose-lowering drugs used for the treatment of DM. This review examines in detail the rationale for their development and the physicochemical, pharmacokinetic and pharmacodynamic properties and clinical activities. Emphasis will be placed on their neuroprotective effects at cellular and molecular levels in experimental models of acute cerebral ischemia. In perspective, an adequate basis does exist for a novel therapeutic approach to hyperglycemia in AIS patients through the additive treatment with GLP-1Ras plus DPP-IVIs.

Stroke in the patient with diabetes (Part 2) - Prevention and the effects of glucose lowering therapies

There is a higher incidence of stroke in both the type 2 diabetic and the non-diabetic insulin resistant patient which is accompanied by higher morbidity and mortality. Stroke primary prevention can be achieved by controlling atrial fibrillation and hypertension, and the utilization of statins and anticoagulant therapies. Utilizing pioglitazone and GLP-1 receptor agonists reduce the risk of stroke while the utilization of metformin, α-glucosidase inhibitors, DPP-4 and SGLT-2 inhibitors have no effect. Insulin use may be a marker of increased risk of stroke, but not necessarily causative. Utilizing intravenous insulin to normalize plasma glucose levels in the acute phase of a stroke does not improve the outcome. Antiplatelet agents are not proven to be of benefit in primary prevention whereas the use of direct-acting oral anticoagulants to avoid stroke and the early use of tpA in the acute phase have been shown to be beneficial.

Liraglutide Protects Against Brain Amyloid-β1-42 Accumulation in Female Mice with Early Alzheimer's Disease-Like Pathology by Partially Rescuing Oxidative/Nitrosative Stress and Inflammation

Alzheimer’s disease (AD) is the most common form of dementia worldwide, being characterized by the deposition of senile plaques, neurofibrillary tangles (enriched in the amyloid beta (Aβ) peptide and hyperphosphorylated tau (p-tau), respectively) and memory loss. Aging, type 2 diabetes (T2D) and female sex (especially after menopause) are risk factors for AD, but their crosslinking mechanisms remain unclear. Most clinical trials targeting AD neuropathology failed and it remains incurable. However, evidence suggests that effective anti-T2D drugs, such as the GLP-1 mimetic and neuroprotector liraglutide, can be also efficient against AD. Thus, we aimed to study the benefits of a peripheral liraglutide treatment in AD female mice. We used blood and brain cortical lysates from 10-month-old 3xTg-AD female mice, treated for 28 days with liraglutide (0.2 mg/kg, once/day) to evaluate parameters affected in AD (e.g., Aβ and p-tau, motor and cognitive function, glucose metabolism, inflammation and oxidative/nitrosative stress). Despite the limited signs of cognitive changes in mature female mice, liraglutide only reduced their cortical Aβ_1–42 levels. Liraglutide partially attenuated brain estradiol and GLP-1 and activated PKA levels, oxidative/nitrosative stress and inflammation in these AD female mice. Our results support the earlier use of liraglutide as a potential preventive/therapeutic agent against the accumulation of the first neuropathological features of AD in females.

Lixisenatide Reduced Damage in Hippocampus CA1 Neurons in a Rat Model of Cerebral Ischemia-Reperfusion Possibly Via the ERK/P38 Signaling Pathway

Glucagon-like peptide-1 (GLP-1) is a gut-derived peptide that has various physiological actions. One of its main actions is the regulation of blood glucose level when it is elevated as it potentiates insulin release. It is also known that GLP-1 protects neurons from damage caused by neurodegenerative diseases. Lixisenatide is one of the GLP-1 analogues that has a strong affinity to the GLP-1 receptor. Experimental animal studies have shown that it holds a neuroprotective effect in Parkinson, myocardial, and cerebral ischemic disease animal models. The beneficial effect of lixisenatide on the brain after cerebral ischemia-reperfusion (I/R) is not clarified yet; thus, it needs further explanatory studies. Our research is the first to study the effect of lixisenatide on myeloperoxidase (MPO) and toll-like receptors (TLRs)/mitogen-activated protein kinase (MAPK) pathway in a rat model of cerebral I/R. Lixisenatide with 2 doses 0.7 and 7 nmol/kg was given intraperitoneal in 2 different groups for 14 days; then, the bilateral common carotid artery was occluded for 1 h followed by reperfusion for 1 h. Examination of hippocampus CA1 neurons by Nissl stain showed that the number of intact neurons was elevated in the lixisenatide-treated group related to the control group (I/R group). Lixisenatide exhibited neuroprotection action possibly via downregulation of MPO, TLR2/4, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and pP38 and upregulation of phosphorylated extracellular signal-regulated kinase (pERK1/2); thus, this study gives possible link between lixisenatide and TLR/MAPK pathway following cerebral I/R and supports the use of lixisenatide for neuroprotection against stroke.

Insulin in the Management of Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

OBJECTIVE

The role of tight glycemic control in the management of acute ischemic stroke remains uncertain. Our goal is to evaluate the effects of tight glucose control with insulin therapy after acute ischemic stroke.

METHODS

We searched PubMed, CENTRAL, and Embase for randomized controlled trials (RCTs) that evaluated the effects of tight glycemic control (70-135 mg/dL) in acute ischemic stroke. Analysis was performed using fixed-effects and random-effects models. Outcomes were death, independence, and modified Rankin Scale (mRS) score at ≥90 days follow-up, and symptomatic or severe hypoglycemia during treatment.

RESULTS

Twelve RCTs including 2734 patients were included. Compared with conventional therapy or placebo, tight glycemic control was associated with similar rates of mortality at ≥90 days follow-up (pooled odds ratio [pOR], 0.99; 95% confidence interval [CI], 0.79-1.22]; I² = 0%), independence at ≥90 days follow-up (pOR, 0.95; 95% CI, 0.79-1.14; I² = 0%) and mRS scores at ≥90 days follow-up (standardized mean difference, 0.014; 95% CI, -0.15 to 0.17; I² = 0%). In contrast, tight glycemic control was associated with increased rates of symptomatic or severe hypoglycemia during treatment (pOR, 5.2; 95% CI, 1.7-15.9; I² = 28%).

CONCLUSIONS

Tight glucose control after acute ischemic stroke is not associated with improvements in mortality, independence, or mRS score and leads to higher rates of symptomatic or severe hypoglycemia.

Diabetes drugs and stroke risk: Intensive versus conventional glucose-lowering strategies, and implications of recent cardiovascular outcome trials

People with diabetes mellitus are at higher risk of ischaemic stroke and worse outcomes thereafter. However, whether it is better to prescribe intensive glucose-lowering treatment compared with conventional treatment in people with diabetes to prevent recurrent stroke is debated. It is also crucial to consider whether specific antidiabetic agents are more efficacious and safer than others for prevention of stroke. In this review, we provide an overview of the efficacy of intensive and conventional glucose-lowering treatment in post-stroke management. Our conclusion is that the overall evidence for a beneficial effect of intensive glycaemic control on risk of stroke is limited. We also discuss evidence from recent large clinical trials of thiazolidinediones and new antidiabetic medications, including dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1RAs), and sodium-glucose co-transporter-2 inhibitors. On the basis of the findings of these trials, our conclusion is that pioglitazone and the GLP-1RA class (other than short-acting lixisenatide) are likely to lessen the occurrence of cerebrovascular disease (by mechanisms not dependent on glucose-lowering per se), whereas there is no consistent evidence for other drug classes.

Liraglutide protects against diabetes mellitus complicated with focal cerebral ischemic injury by activating mitochondrial ATP-sensitive potassium channels

Cerebral infarction is a common disease that threatens the health of humankind worldwide. Diabetes is one of the important causes of cerebral ischemic (CI) injury. CI complicated with diabetes has a worse prognosis and lacks effective treatment. Our preliminary study demonstrated that liraglutide mitigates CI injuries in diabetic rats. However, the essential mechanism underlying this effect remained to be fully investigated. Recent research has shown that damaged mitochondrial ATP-sensitive potassium channels (mitoKATP) play a critical role in diabetes-aggravated CI injury. Therefore, we hypothesized that liraglutide may confer therapeutic effects against CI with diabetes by activating mitoKATP channels. In this study, liraglutide, but not insulin, significantly improved ischemia-induced neurological deficits and decreased infarct volumes following CI in diabetic rats, down-regulated the expression of myeloperoxidase and up-regulated the expression of superoxide dismutase and two subunits of the mitoKATP channel (SUR1 and Kir6.2). However, these effects were weakened by the mitoKATP antagonist 5-hydroxydecanoic acid. Our study demonstrated that the neuroprotective effects of liraglutide on CI injury with diabetes, which occurs by reducing oxidative stress and the inflammatory response, are associated with the activation of the mitoKATP channel.

Neuroprotection in Rats Following Ischaemia-Reperfusion Injury by GLP-1 Analogues-Liraglutide and Semaglutide

PURPOSE

A substantial number of ischaemic stroke patients who receive reperfusion therapy in the acute phase do not ever fully recover. This reveals the urgent need to develop new adjunctive neuroprotective treatment strategies alongside reperfusion therapy. Previous experimental studies demonstrated the potential of glucagon-like peptide-1 (GLP-1) to reduce acute ischaemic damage in the brain. Here, we examined the neuroprotective effects of two GLP-1 analogues, liraglutide and semaglutide.

METHODS

A non-diabetic rat model of acute ischaemic stroke involved 90, 120 or 180 min of middle cerebral artery occlusion (MCAO). Liraglutide or semaglutide was administered either i.v. at the onset of reperfusion or s.c. 5 min before the onset of reperfusion. Infarct size and functional status were evaluated after 24 h or 72 h of reperfusion.

RESULTS

Liraglutide, administered as a bolus at the onset of reperfusion, reduced infarct size by up to 90% and improved neuroscore at 24 h in a dose-dependent manner, following 90-min, but not 120-min or 180-min ischaemia. Semaglutide and liraglutide administered s.c. reduced infarct size by 63% and 48%, respectively, and improved neuroscore at 72 h following 90-min MCAO. Neuroprotection by semaglutide was abolished by GLP1-R antagonist exendin(9-39).

CONCLUSION

Infarct-limiting and functional neuroprotective effects of liraglutide are dose-dependent. Neuroprotection by semaglutide is at least as strong as by liraglutide and is mediated by GLP-1Rs.

Hypoxia conditioning enhances neuroprotective effects of aged human bone marrow mesenchymal stem cell-derived conditioned medium against cerebral ischemia in vitro

Therapeutic transplantation of autologous bone marrow mesenchymal stem cells (BMSCs) holds great promise for ischemic stroke, yet the efficacy is negatively impacted by aging. Here, we examined whether hypoxia conditioning could enhance aged human BMSCs-induced neuroprotection via secretome action. Primary cultured mouse neurons were exposed to oxygen glucose deprivation (OGD) to mimic ischemic stroke in vitro, then randomized into a hypoxia conditioned aged human BMSCs-conditioned medium (BMSC-hypoCM) versus normoxia conditioned (BMSC-norCM). After 22 h of reperfusion, cell viability was significantly increased in neurons treated with BMSC-hypoCM rather than BMSC-norCM. ELISA revealed that hypoxia conditioning enhanced vascular endothelial growth factor (VEGF) release into BMSC-derived CM. Blocking the VEGF receptor negated BMSC-hypoCM-induced protection for neurons against OGD insult. Altogether, our data indicates that hypoxia conditioning improves aged human BMSCs' therapeutic efficacy for neurons with ischemic challenge, in part via promoting secretion of VEGF.

Of mice and men: incretin actions in the central nervous system

Incretins have risen to the forefront of therapies for obesity and related metabolic complications, primarily because of their efficacy and relatively few side effects. Importantly, their efficacy in altering energy balance and decreasing body weight is apparently through actions in the central nervous system (CNS); the latter may have implications beyond obesity per se, i.e. in other disease states associated with obesity including CNS-related disorders. Here, we first describe the role of the CNS in energy homeostasis and then the current state of knowledge in terms of incretin physiology, pathophysiology and efficacy in preclinical and clinical studies. In the future, more clinical studies are needed to fully map mechanistic pathways underlying incretin actions and outcomes in the human CNS. Additionally, future research will likely lead to the discovery of additional novel incretins and/or more efficacious medications with less side effects through the improvement of current compounds with properties that would allow them to have more favorable pharmacokinetic and pharmacodynamic profiles and/or by combining known and novel incretins into safe and more efficacious combination therapies leading ultimately to more tangible benefits for our patients.

The diabetes drug semaglutide reduces infarct size, inflammation, and apoptosis, and normalizes neurogenesis in a rat model of stroke

Stroke is a condition with few medical treatments available. Semaglutide, a novel Glucagon-like peptide-1 (GLP-1) analogue, has been brought to the market as a treatment for diabetes. We tested the protective effects of semaglutide against middle cerebral artery occlusion injury in rats. Animals were treated with 10 nmol/kg bw ip. starting 2 h after surgery and every second day for either 1, 7, 14 or 21 days. Semaglutide-treated animals showed significantly reduced scores of neurological impairments in several motor and grip strength tasks. The cerebral infarction size was also reduced, and the loss of neurons in the hippocampal areas CA1, CA3 and the dentate gyrus was much reduced. Chronic inflammation as seen in levels of activated microglia and in the activity of the p38 MAPK - MKK - c-Jun- NF-κB p65 inflammation signaling pathway was reduced. In addition, improved growth factor signaling as shown in levels of activated ERK1 and IRS-1, and a reduction in the apoptosis signaling pathway C-raf, ERK2, Bcl-2/BAX and Caspase-3 was observed. Neurogenesis had also been normalized by the drug treatment as seen in increased neurogenesis (DCX-positive cells) in the dentate gyrus and a normalization of biomarkers for neurogenesis. In conclusion, semaglutide is a promising candidate for re-purposing as a stroke treatment.

GLP-1 secretion in acute ischemic stroke: association with functional outcome and comparison with healthy individuals

BACKGROUND

Glucagon-like peptide-1 (GLP-1) treatment has been shown to reduce stroke incidence in diabetes and also to be neuroprotective in experimental stroke models. The prognostic value of endogenous levels of GLP-1 in the recovery phase after stroke remains to be elucidated. The aim of the study was to investigate the potential association between GLP-1 levels and functional outcome after stroke and to determine whether GLP-1 is altered in the acute phase of stroke compared to 3 months post stroke and to healthy controls.

METHODS

Fasting GLP-1 was measured on hospital day 2-4 in patients without previously known diabetes (n = 59) that received recombinant tissue plasminogen activator (rtPA) for ischemic stroke. Fasting GLP-1 was measured again after 3 months and neurologic outcome was measured as modified Rankin Scale (mRS). mRS ≥ 2 was considered as unfavorable outcome. A control group of healthy individuals (n = 27) was recruited and their fasting GLP-1 was measured.

RESULTS

Fasting GLP-1 was higher in the patients that suffered a stroke compared to healthy controls (25.1 vs. 18.0 pmol/L; p = 0.004). The GLP-1 levels did not change significantly at the 3-month follow up OGTT (25.8 vs. 25.6; p = 0.80). There was no significant association between GLP-1 levels and unfavorable mRS (OR 1.03, 95% CI 0.95-1.12, p = 0.50).

CONCLUSIONS

Endogenous GLP-1 levels in patients that recently suffered an ischemic stroke are higher than in healthy controls and remained unchanged at the 3 months follow-up, possibly indicating an elevation of the levels of GLP-1 already pre-stroke. However, no association between endogenous GLP-1 and functional outcome of stroke 3 months post stroke was found.

Effects of Thiazolidinedione and New Antidiabetic Agents on Stroke

Patients with hyperglycemia are at a high risk of cardio- and cerebrovascular diseases. Diabetes patients also have poor outcomes after cerebrovascular disease development. Several classes of drugs are used for diabetes management in clinical practice. Thiazolidinedione (TZD) was introduced in the late 1990s, and new antidiabetic agents have been introduced since 2000. After issues with rosiglitazone in 2007, the U.S. Food and Drug Administration strongly recommended that trials investigating cardiovascular risk associated with new antidiabetic medications should be conducted before drug approval in the United States, to prove the safety of these new drugs and to determine their superiority to previous medications. Currently, results are available from two studies with TZD focusing on cardiovascular diseases, including stroke, and from 12 cardiovascular outcome trials focusing on major adverse cardiovascular events associated with new antidiabetic agents (four with dipeptidyl peptidase-4 inhibitors, three with sodium-glucose cotransporter-2 inhibitors, and five with glucagon-like peptide-1 analogues). These studies showed different results for primary cardiovascular outcomes and stroke prevention. It is important to determine whether prescription of TZD or new antidiabetic medications compared to conventional treatment, such as sulfonylurea or insulin, is better for stroke management. Furthermore, it is unclear whether drugs in the same class show greater safety and efficacy than other drugs for stroke management.

GLP-1's role in neuroprotection: a systematic review

Glucagon-like peptide 1 (GLP-1) is a target for treatment of diabetes; however, its function in the brain is not well studied. In this systematic review, we aimed to analyze the neuroprotective role of GLP-1 and its defined mechanisms. Methods: We searched 'Web of Science' and 'Pubmed' to identify relevant studies using GLP-1 as the keyword. Two hundred and eighty-nine clinical and preclinical studies have been included. Data have been presented by grouping neurodegenerative, neurovascular and specific cell culture models. Results: Recent literature shows that GLP-1 and its agonists, DPP-4 inhibitors and combined GLP-1/GIP molecules are effective in partially or fully reversing the effects of neurotoxic compounds, neurovascular complications of diabetes, neuropathological changes related with Alzheimer's disease, Parkinson's disease or vascular occlusion. Possible mechanisms that provide neuroprotection are enhancing the viability of the neurons and restoring neurite outgrowth by increased neurotrophic factors, increasing subventricular zone progenitor cells, decreasing apoptosis, decreasing the level of pro-inflammatory factors, and strengthening blood-brain barrier. Conclusion: Based on the preclinical studies, GLP-1 modifying agents are promising targets for neuroprotection. On the other hand, the number of clinical studies that investigate GLP-1 as a treatment is low and further clinical trials are needed for a benchside to bedside translation of recent findings.

Crosstalk between nonalcoholic fatty liver disease and cardiometabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is a chronic condition characterized by fat accumulation combined with low-grade inflammation in the liver. A large body of clinical and experimental data shows that increased flux of free fatty acids from increased visceral adipose tissue and de novo lipogenesis can lead to NAFLD and insulin resistance. Thus, individuals with obesity, insulin resistance, and dyslipidaemia are at the greatest risk of developing NAFLD. Conversely, NAFLD is a phenotype of cardiometabolic syndrome. Notably, researchers have discovered a close association between NAFLD and impaired glucose metabolism and focused on the role of NAFLD in the development of type 2 diabetes. Moreover, recent studies provide substantial evidence for an association between NAFLD and atherosclerosis and cardiometabolic disorders. Even if NAFLD can progress into severe liver disorders including nonalcoholic steatohepatitis (NASH) and cirrhosis, the majority of subjects with NAFLD die from cardiovascular disease eventually. In this review, we propose a potential pathological link between NAFLD/NASH and cardiometabolic syndrome. The potential factors that can play a pivotal role in this link, such as inflammation, insulin resistance, alteration in lipid metabolism, oxidative stress, genetic predisposition, and gut microbiota are discussed.

Liraglutide and its Neuroprotective Properties-Focus on Possible Biochemical Mechanisms in Alzheimer's Disease and Cerebral Ischemic Events

Liraglutide is a GLP-1 analog (glucagon like peptide-1) used primarily in the treatment of diabetes mellitus type 2 (DM2) and obesity. The literature starts to suggest that liraglutide may reduce the effects of ischemic stroke by activating anti-apoptotic pathways, as well as limiting the harmful effects of free radicals. The GLP-1R expression has been reported in the cerebral cortex, especially occipital and frontal lobes, the hypothalamus, and the thalamus. Liraglutide reduced the area of ischemia caused by MCAO (middle cerebral artery occlusion), limited neurological deficits, decreased hyperglycemia caused by stress, and presented anti-apoptotic effects by increasing the expression of Bcl-2 and Bcl-xl proteins and reduction of Bax and Bad protein expression. The pharmaceutical managed to decrease concentrations of proapoptotic factors, such as NF-κB (Nuclear Factor-kappa β), ICAM-1 (Intercellular Adhesion Molecule 1), caspase-3, and reduced the level of TUNEL-positive cells. Liraglutide was able to reduce the level of free radicals by decreasing the level of malondialdehyde (MDA), and increasing the superoxide dismutase level (SOD), glutathione (GSH), and catalase. Liraglutide may affect the neurovascular unit causing its remodeling, which seems to be crucial for recovery after stroke. Liraglutide may stabilize atherosclerotic plaque, as well as counteract its early formation and further development. Liraglutide, through its binding to GLP-1R (glucagon like peptide-1 receptor) and consequent activation of PI3K/MAPK (Phosphoinositide 3-kinase/mitogen associated protein kinase) dependent pathways, may have a positive impact on Aβ (amyloid beta) trafficking and clearance by increasing the presence of Aβ transporters in cerebrospinal fluid. Liraglutide seems to affect tau pathology. It is possible that liraglutide may have some stem cell stimulating properties. The effects may be connected with PKA (phosphorylase kinase A) activation. This paper presents potential mechanisms of liraglutide activity in conditions connected with neuronal damage, with special emphasis on Alzheimer's disease and cerebral ischemia.

GLP-1RAs in type 2 diabetes: mechanisms that underlie cardiovascular effects and overview of cardiovascular outcome data

Patients with type 2 diabetes (T2DM) have a substantial risk of developing cardiovascular disease. The strong connection between the severity of hyperglycaemia, metabolic changes secondary to T2DM and vascular damage increases the risk of macrovascular complications. There is a challenging demand for the development of drugs that control hyperglycaemia and influence other metabolic risk factors to improve cardiovascular outcomes such as cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, hospitalization for unstable angina and heart failure (major adverse cardiovascular events). In recent years, introduction of the new drug class of glucagon-like peptide-1 receptor agonists (GLP-1RAs) has changed the treatment landscape as GLP-1RAs have become well-established therapies in T2DM. The benefits of GLP-1RAs are derived from their pleiotropic effects, which include appetite control, glucose-dependent secretion of insulin and inhibition of glucagon secretion. Importantly, their beneficial effects extend to the cardiovascular system. Large clinical trials have evaluated the cardiovascular effects of GLP-1RAs in patients with T2DM and elevated risk of cardiovascular disease and the results are very promising. However, important aspects still require elucidation, such as the specific mechanisms involved in the cardioprotective effects of these drugs. Careful interpretation is necessary because of the heterogeneity across the trials concerning the definition of cardiovascular risk or cardiovascular disease, baseline characteristics, routine care and event rates. The aim of this review is to describe the main clinical aspects of the GLP-1RAs, compare them using data from both the mechanistic and randomized controlled trials and discuss potential reasons for improved cardiovascular outcomes observed in these trials. This review may help clinicians to decide which treatment is most appropriate in reducing cardiovascular risk in patients with T2DM.

Stand alone or join forces? Stem cell therapy for stroke

INTRODUCTION

Stroke is a major cause of mortality and disability with a narrow therapeutic window. Stem cell therapy may enhance the stroke recovery.

AREAS COVERE

Regenerative medicine via stem cells stands as a novel therapy for stroke. In particular, bone marrow-derived mesenchymal stem cells (MSCs) have neuroprotective and anti-inflammatory properties that improve brain function after stroke. Here, we discuss the safety, efficacy, and mechanism of action underlying the therapeutic effects of bone marrow-derived MSCs. We also examine the discrepant transplant protocols between preclinical studies and clinical trials. Laboratory studies show the safety and efficacy of bone marrow-derived MSCs in stroke models. However, while safe, MSCs remain to be fully evaluated as effective in clinical trials. Furthermore, recognizing the multiple cell death processes associated with stroke, we next discuss the potential therapeutic benefits of a combination therapy. With preliminary results and on-going clinical trials, a careful assessment of dosing, timing, and delivery route regimens will further direct the future of stem cell therapy for neurological disorders, including stroke.

EXPERT OPINION

Bone marrow-derived MSCs appear to be the optimal stem cell source for stroke therapy. Optimizing dosing, timing, and delivery route should guide the clinical application of bone marrow-derived MSCs.

Neuroprotective effect of glucagon-like peptide-1 receptor agonist is independent of glycaemia normalization in type two diabetic rats

OBJECTIVE

Stroke is a severe complication of type 2 diabetes mellitus. Glucagon-like peptide-1 receptor agonists have been shown to have a neuroprotective effect in experimental diabetes. The aim of this study was to determine if their neuroprotective effect is an independent property of the drug independent of glycaemic control.

METHODS

This two-phase study used male Wistar rats. In the first phase, experimental animals were pretreated with liraglutide, while controls received only vehicle. After transient focal brain ischaemia modelling, neurological deficit and brain infarct volume were measured. In the second phase, the first and the second groups of experimental animals with type 2 diabetes mellitus received liraglutide and metformin, respectively, while control animals with diabetes received only vehicle. After transient focal brain ischaemia modelling, neurological deficit and brain infarct volume were evaluated.

RESULTS

Pretreatment with liraglutide in diabetic and non-diabetic animals reduced infarct size as compared to controls, while only non-diabetic liraglutide-treated rats presented neurologic deficit decreases. Despite glycaemia normalization, metformin-treated diabetic rats had no differences in stroke outcome when compared to the control group.

CONCLUSION

The neuroprotective effect of liraglutide is not associated with glycaemic control amelioration in experimental type 2 diabetes mellitus.