Protective Effects Of Liraglutide Research Articles

Liraglutide alleviates sepsis-induced acute lung injury by regulating pulmonary surfactant through inhibiting autophagy

Background Pulmonary surfactant (PS) plays an important role in the treatment of sepsis-induced acute lung injury (ALI). Liraglutide, a glucagon-like peptide-1 (GLP-1) analog, improves the secretion and function of PS in ALI, but the underlying mechanism remains unknown. This study aimed to investigate how liraglutide regulates PS secretion in ALI. Methods C57BL/6 mice were injected subcutaneously with normal saline containing different concentrations of liraglutide after the establishment of the ALI model. MLE-12 cells were treated with liraglutide after LPS stimulation. The survival rate of mice, wet/dry weight ratio, inflammatory factors in bronchoalveolar lavage fluid (BALF), pulmonary injury, and apoptosis were analyzed. Cell viability, proliferation, apoptosis, the expression of SP-A, SP-B, and expression of autophagy-related proteins in cells were measured. Results ALI mice showed reduced pulmonary injury, less apoptosis, and less inflammation compared to the controls. Liraglutide prolonged survival, decreased the wet/dry weight ratio, reduced inflammatory responses, and attenuated pulmonary edema compared with the ALI group. Moreover, LPS-induced cell damage and reduction of SP-A and SP-B expression were markedly reversed by liraglutide in MLE-12 cells. Furthermore, the protective effects of liraglutide were reversed by rapamycin. Conclusion Liraglutide alleviate sepsis-induced ALI by inhibiting autophagy and regulating PS.

Exploration on the protective effect of liraglutide on renal injury in diabetic nephropathy rats based on ROS-NLRP3 inflammasomes

Objective: To investigate the effect of liraglutide on diabetic nephropathy in rats and its regulatory mechanism. Methods: The diabetic nephropathy rat model was constructed with high-glucose-high-fat diet in combination with STZ, and was randomly divided into normal saline group and liraglutide group. The rats in liraglutide group were given sc 200 μg/kg of liraglutide, and the rats in normal saline group were given sc 20 mg/kg of normal saline twice a day for 4 weeks. The normal control group was not treated with any treatment. The biochemical indexes such as rat body weight, 24-hour urine total protein quantification (UTP), fasting blood glucose (FPG), triglyceride (TG), cholesterol (TC), blood urea nitrogen (BUN) and serum creatinine (Scr) were measured. HE staining, Masson staining and PAS staining were used to observe the pathologically morphological changes in renal tissues. Western-blot was used to detect the expression of NLRP3 inflammasome-related protein in renal tissues. Elisa was used to measure the serum levels of interleukin-18 (IL-18) and IL-1β. SPSS 26.0 statistical software and Graph Prism 9.0 software were used for analysis and mapping. The t-test was used for the comparison of measurement data between two groups, one-way ANOVA was used for the comparison among multiple groups, and Tukey’s test was used for the comparison in the same group. Results: Compared with the normal saline group, FBG, UTP, BUN, Scr, TC and TG in the liraglutide group were significantly decreased (p < .01), the glomerular basement membrane was slightly thickened, with the tubular lumen slightly dilated and the lesion damage alleviated; the expression levels of NLRP3, ASC and caspase-1 inflammasome-related proteins were decreased (p < .01), and the levels of IL-18 and IL-1β were decreased (p < .01).Conclusion: Liraglutide can inhibit the activation of NLRP3 inflammasome mediated by oxidative stress in renal tissues through ROS-NLRP3 inflammasome pathway, thereby inhibiting the inflammation, and finally playing an anti-diabetic nephropathy renal injury role.

Liraglutide Protects Pancreatic Islet From Ischemic Injury by Reducing Oxidative Stress and Activating Akt Signaling During Cold Preservation to Improve Islet Transplantation Outcomes.

Islet transplantation is a promising therapy for patients with type 1 diabetes. However, ischemic injury to the donor islets during cold preservation leads to reduced islet quality and compromises transplant outcome. Several studies imply that liraglutide, a glucagon-like peptide-1 receptor agonist, has a positive effect on promoting islet survival, but its impact on islet cold-ischemic injury remains unexplored. Therefore, the aim of this study was to investigate whether liraglutide can improve islet transplantation efficacy by inhibiting cold-ischemic injury and to explore the underlying mechanisms. Liraglutide was applied in a mouse pancreas preservation model and a human islets cold-preservation model, and islet viability, function, oxidative stress levels were evaluated. Furthermore, islet transplantation was performed in a syngeneic mouse model and a human-to-nude mouse islet xenotransplantation model. The supplementation of liraglutide in preservation solution improved islet viability, function, and reduced cell apoptosis. Liraglutide inhibited the oxidative stress of cold-preserved pancreas or islets through upregulating the antioxidant enzyme glutathione levels, inhibiting reactive oxygen species accumulation, and maintaining the mitochondrial membrane integrity, which is associated with the activation of Akt signaling. Furthermore, the addition of liraglutide during cold preservation of donor pancreas or donor islets significantly improved the subsequent transplant outcomes in both syngeneic mouse islet transplantation model and human-to-nude mouse islet xenotransplantation model. Liraglutide protects islets from cold ischemia-related oxidative stress during preservation and hence improved islet transplantation outcomes, and this protective effect of liraglutide in islets is associated with the activation of Akt signaling.

Liraglutide ameliorates oxidized LDL-induced endothelial dysfunction by GLP-1R-dependent downregulation of LOX-1-mediated oxidative stress and inflammation

ABSTRACTObjectiveTo investigate the effects of glucagon-like peptide 1 receptor (GLP-1R) agonist liraglutide on endothelial dysfunction in LDL receptor-deficient (LDLR-KO) mice and ox-LDL-challenged human umbilical vein endothelial cells (HUVECs) and its possible mechanism.MethodsLDLR-KO mice were randomly treated with normal saline, liraglutide, or liraglutide plus a GLP-1R antagonist exendin-9 for four weeks. In parallel, HUVECs were cultured with ox-LDL alone or combined with liraglutide, in the presence or absence of lectin-like ox-LDL receptor-1(LOX-1) overexpression or GLP-1R knockdown. Endothelial-dependent relaxation and LOX-1 protein expression of thoracic aorta, circulating levels of oxidative and inflammatory markers in mice, and cell survival, reactive oxygen species production, and expression of adhesion molecules and signal regulators in ox-LDL cultured endothelial cells were measured.Resultsliraglutide effectively enhanced acetylcholine-induced vasodilation, reduced LOX-1 expression in aortas, and decreased circulatory oxidative and inflammatory levels in LDLR-KO mice, which were abolished by cotreatment with exendin-9. HUVECs exposed to ox-LDL exhibited reduced cell viability, increased reactive oxygen species production and apoptosis, and elevated protein expression of ICAM-1, VCAM-1, LOX-1, NOX4, and NF-κB, which were markedly ameliorated by liraglutide treatment. The protective effects of liraglutide against ox-LDL-induced cell injury were abrogated in HUVECs overexpressing LOX-1 or silencing GLP-1R.ConclusionsLiraglutide improved oxidized LDL-induced endothelial dysfunction via GLP-1R-dependent downregulation of LOX-1-mediated oxidative stress and inflammation.

GLP-1 Analog Alleviated Cognitive Dysfunction in Aged Rats Anaesthetized with Sevoflurane.

Postoperative cognitive dysfunction (POCD) in elderly patients undergoing general anesthesia is a major problem in the aging society. Sevoflurane is the most widely applied anesthetic in clinical practice. In this study, we investigated the effects of the GLP-1 analogue liraglutide on cognitive function in aged rats anesthetized by sevoflurane. Specifically, 48 Sprague-Dawley rats were divided into the control (C) group, the liraglutide (L) group, the sevoflurane (S) group, and the sevoflurane+liraglutide (SL) group, each group with 12 rats. In the S group and the SL group, the rats were injected subcutaneously with normal saline and liraglutide after inhalation of a mixture of 3% sevoflurane and pure oxygen. In the C group and the L group, normal saline and liraglutide were injected subcutaneously into the rats after inhalation of pure oxygen. Morris Water Maze Task was applied for the detection of spatial learning and memory in rats; HE and TUNEL for staining; and western blot for quantifying Bax, Bcl-2 expression, and examining caspase-3 activity in hippocampal tissues as well as for revealing the antiapoptotic mechanism. Besides, the accumulation of inflammatory factors NF-κB and IL-1β in the hippocampal tissue was quantitatively studied to reveal the anti-inflammatory mechanism. The protective effect of liraglutide on sevoflurane toxicity was the first to be confirmed in this study. Additionally, this study elucidated the mechanism of the above effect. The results of this study might be helpful to find an effective medical solution for the treatment of POCD caused by sevoflurane anesthesia.

Liraglutide Attenuates Hepatic Ischemia-Reperfusion Injury by Modulating Macrophage Polarization.

Ischemia-reperfusion injury (IRI) is a common complication associated with liver surgery, and macrophages play an important role in hepatic IRI. Liraglutide, a glucagon-like peptide-1 (GLP-1) analog primarily used to treat type 2 diabetes and obesity, regulates intracellular calcium homeostasis and protects the cardiomyocytes from injury; however, its role in hepatic IRI is not yet fully understood. This study aimed to investigate whether liraglutide can protect the liver from IRI and determine the possible underlying mechanisms. Our results showed that liraglutide pretreatment significantly alleviated the liver damage caused by ischemia-reperfusion (I/R), as evidenced by H&E staining, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, and TUNEL staining. Furthermore, the levels of inflammatory cytokines elicited by I/R were distinctly suppressed by liraglutide pretreatment, accompanied by significant reduction in TNF-α, IL-1β, and IL-6 levels. Furthermore, pretreatment with liraglutide markedly inhibited macrophage type I (M1) polarization during hepatic IRI, as revealed by the significant reduction in CD68+ levels in Kupffer cells (KCs) detected via flow cytometry. However, the protective effects of liraglutide on hepatic IRI were partly diminished in GLP-1 receptor-knockout (GLP-1R-/-) mice. Furthermore, in an in vitro study, we assessed the role of liraglutide in macrophage polarization by examining the expression profiles of M1 in bone marrow-derived macrophages (BMDMs) from GLP-1R-/- and C57BL/6J mice. Consistent with the results of the in vivo study, liraglutide treatment attenuated the LPS-induced M1 polarization and reduced the expression of M1 markers. However, the inhibitory effect of liraglutide on LPS-induced M1 polarization was largely abolished in BMDMs from GLP-1R-/- mice. Collectively, our study indicates that liraglutide can ameliorate hepatic IRI by inhibiting macrophage polarization towards an inflammatory phenotype via GLP-1R. Its protective effect against liver IRI suggests that liraglutide may serve as a potential drug for the clinical treatment of liver IRI.

Renoprotective Effect of Liraglutide Is Mediated via the Inhibition of TGF-Beta 1 in an LLC-PK1 Cell Model of Diabetic Nephropathy.

Background: Recently published research demonstrated direct renoprotective effects of the glucagon-like peptide-1 receptor agonist GLP 1 RA, but the relevant molecular mechanisms are still not clear. The aim of this research was to assess the effects of Liraglutide in a cell culture model of diabetic nephropathy on cell viability, antioxidant (GSH) and transforming growth factor beta 1 (TGF- β1) levels and extracellular matrix (ECM) expression. The metabolic activity in hyperglycemic conditions and the effect of Liraglutide treatment were assessed by measuring Akt, pAkt, GSK3β, pGSK3β, pSTAT3, SOCS3, iNOS and NOX4 protein expression with Western blot. F actin distribution was used to assess the structural changes of the cells upon treatment. Materials and methods: The cells were exposed to high glucose (HG30 mM) followed by 0.5 mM H2O2 and a combination of glucose and H2O2 during 24 h. Subsequently, the cells were treated with different combinations of HG30, H2O2 and Liraglutide. Cell viability was determined by an MTT colorimetric test, and the GSH, TGF-β1 concentration and ECM expression were measured using a spectrophotometric/microplate reader assay and an ELISA kit, respectively. Western blotting was used to detect the protein level of Akt, pAkt, GSK3β, pGSK3β, pSTAT3, SOCS3, iNOS and NOX4. The F-actin cytoskeleton was visualized with Phalloidin stain and subsequently quantified. Results: Cell viability was decreased as well as GSH levels in cells treated with a combination of HG30/H2O2, and HG30 alone (p < 0.001). The addition of Liraglutide improved the viability in cells treated with HG30, but it did not affect the cell viability in the cell treated with the addition of H2O2. GSH increased with the addition of Liraglutide in HG30/H2O2 (p < 0.001) treated cells, with no effect in cells treated only with HG30. TGF-β1 levels (p < 0.001) were significantly increased in HG30 and HG30/H2O2. The addition of Liraglutide significantly decreased the TGF-β1 levels (p < 0.01; p < 0.05) in all treated cells. The synthesis of collagen was significantly increased in HG30/H2O2 (p < 0.001), while the addition of Liraglutide in HG30/H2O2 significantly decreased collagen (p < 0.001). Akt signaling was not significantly affected by treatment. The GSK3b and NOX4 levels were significantly reduced (p < 0.01) after the peroxide and glucose treatment, with the observable restoration upon the addition of Liraglutide suggesting an important role of Liraglutide in oxidative status regulation and mitochondrial activity. The treatment with Liraglutide significantly upregulated STAT3 (p < 0.01) activity, with no change in SOCS3 indicating a selective regulation of the STAT 3 signaling pathway in glucose and the oxidative overloaded environment. A significant reduction in the distribution of F-actin was observed in cells treated with HG30/H2O2 (p < 0.01). The addition of Liraglutide to HG30-treated cells led to a significant decrease of distribution of F-actin (p < 0.001). Conclusion: The protective effect of Liraglutide is mediated through the inhibition of TGF beta, but this effect is dependent on the extent of cellular damage and the type of toxic environment. Based on the WB analysis we have revealed the signaling pathways involved in cytoprotective and cytotoxic effects of the drug itself, and further molecular studies in vitro and vivo are required to elucidate the complexity of the pathophysiological mechanisms of Liraglutide under conditions of hyperglycemia and oxidative stress.

Liraglutide ameliorates myocardial damage in experimental diabetic rats by inhibiting pyroptosis via Sirt1/AMPK signaling.

Objective(s):Liraglutide, a well-established drug for treating diabetes mellitus (DM), has recently gained attention for its cardiovascular benefits in diabetes via multiple cellular activities; however, whether liraglutide improves myocardial damage by inhibiting pyroptosis and the mechanisms of these potential effects remain unknown.Materials and Methods:In this study, high-fat diet feeding and low-dose streptozotocin (STZ) injection were used to construct a rat DM model. Rats with fasting blood glucose (FBG) levels >16.7 mmol/l received subcutaneous injections of liraglutide (0.2 mg/kg) for 4 weeks. Metabolic parameters, the heart weight/body weight (HW/BW) ratio, and histopathology were examined. Protein levels of inflammatory, pyroptosis, and NOD-like receptor protein 3 (NLRP3) inflammasome markers were assessed via Western blotting. In in vitro studies, a sirtuin 1 (Sirt1) inhibitor (EX 527, 200 nM) and an AMP-activated protein kinase (AMPK) inhibitor (compound C, 20 µM) were used to inhibit Sirt1 and AMPK pathways, respectively.Results:Liraglutide significantly attenuated cardiac hypertrophy, pathological changes, inflammation, pyroptosis, and NLRP3 inflammasome activation, accompanied by increased Sirt1 and AMPK activation. Consistent with the in vivo results, liraglutide attenuated high glucose (HG)-induced pyroptosis and NLRP3 inflammasome activation along with enhanced Sirt1 and AMPK activation. After blockade of Sirt1 and AMPK signaling, the protective effect of liraglutide was restrained. Notably, EX 527 abolished the stimulatory effect of liraglutide on Sirt1 and AMPK signaling, whereas compound C blunted AMPK signaling without affecting Sirt1 signaling. Conclusion:Liraglutide may protect against myocardial damage by activating the Sirt1/AMPK signaling pathways to inhibit cellular pyroptosis in DM.

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.

Liraglutide ameliorates COCl2-induced oxidative stress and apoptosis in H9C2 cells via regulating cell autophagy.

Protective effects of liraglutide on H9C2 cells cultured using CoCl2 and its mechanism of action were investigated. Hypoxia model was established using CoCl2-treated H9C2 cells. With liraglutide as the treatment factor, apoptosis, changes in nitric oxide (NO) and reactive oxygen species (ROS) activity, mitochondrial membrane potential and change in cell autophagy level were detected via Hoechst staining, enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR) and western blotting (WB), respectively. Liraglutide ameliorated the CoCl2-induced decrease in H9C2 cell viability, the increases in cytotoxicity and percentage of apoptotic cells as well as oxidative stress in cells. Moreover, it stimulated the elevation of cell autophagy level. However, the protective effects of liraglutide on H9C2 cells were attenuated remarkably after adding the cell autophagy inhibitor. Liraglutide can ameliorate the CoCl2-induced oxidative stress and apoptosis in H9C2 cells via regulating cell autophagy.

Liraglutide ameliorates obesity-related nonalcoholic fatty liver disease by regulating Sestrin2-mediated Nrf2/HO-1 pathway

Liraglutide, a glucagon-like peptide 1 (GLP-1) analogue, could reverse NAFLD-induced liver damage by improving metabolic profiles, but the exact molecular mechanism has not been elucidated. Sestrin2 is a novel antioxidant protein, essential for regulating metabolic homeostasis. However, whether sestrin2-mediated redox balance participated in the protective effects of liraglutide against NAFLD is still elusive. The aim of the study was to determine whether liraglutide could ameliorate NAFLD by increasing Sestrin2-mediated signaling in obese mice. Following a normal diet or high fat diet (HFD) for 8 weeks, male C57BL/6 mice were treated with or without liraglutide for 4 weeks. Function and histopathology of liver were conducted to evaluate liver injury. Sestrin2-related AMPK and Nrf2/HO-1 pathway were examined. Antioxidative and inflammatory genes and were determined. HFD mice displayed significantly increased body weight, fat mass, lipids levels and impaired glucose homeostasis with reduced glucose tolerance and insulin sensitivity. Metabolic profiles, hepatic injury, and hepatic lipid accumulation from HFD mice were improved by liraglutide treatment. Liraglutide enhanced Sestrin2, phosphorylated AMPK, Nrf2, and HO-1 protein levels. Additionally, Liraglutide treatment increased mRNA levels of Sestrin2, Nrf2, HO-1 and down-stream genes catalase, GCLM and NQO1, but reduced malondialdehyde and TNF-α levels. Our findings indicated that liraglutide ameliorated obesity-related NAFLD through upregulating Sestrin2-mediated Nrf2/HO-1 pathway.

Protective effect of Liraglutide on diabetic retinal neurodegeneration via inhibiting oxidative stress and endoplasmic reticulum stress

Diabetes-induced retinal neurodegeneration occurs before visible microvascular abnormalities. Hyperglycemia-induced endoplasmic reticulum (ER) stress (ERS) and oxidative stress(OS) were considered as the important factors during diabetic retinopathy development. Liraglutide (LIRA), a glucagon-like peptide-1 (GLP-1) analogue, is widely used in the clinic and also proved having protective effect on neurodegenerative diseases. The purpose of this study was to evaluate the neuroprotective effect of LIRA on diabetes-induced retinal neurodegeneration and underlying mechanisms. In vivo, a high-fat diet and streptozotocin (STZ) injection were used inducing diabetes model. Hematoxylin-eosin staining was used for morphological observation and measuring retinal thickness. In vitro, Neuro2a cells were cultured in normal and high-glucose conditions. Flow cytometry was performed to analyze apoptosis. Additionally, Western blotting and Immunohistochemistry were carried out to detect proteins expression. The retinal thickness was decreased in diabetes. However, the retinal thickness reducing was delay after LIRA treatment in diabetes. In vitro, the apoptosis percentage, ROS production and the expression of ERS related protein GRP78, ASK1, p-IRE1α was increased and the expression of Nrf2, p-Erk1/2, Trx was decreased after HG treatment, However, the apoptosis percentage, generation of ROS and the expression of GRP78, ASK1, p-IRE1 were decreased. The expression of Nrf2, p-Erk1/2, Trx was increased significantly after LIRA treatment. Taken together, our results indicated that LIRA can alleviates diabetes-induced retinal neurodegeneration which activated Erk pathway inhibiting OS and regulated the Trx-ASK1complex inhibiting ERS.

The protective effects of liraglutide on AD-like neurodegeneration induced by oxidative stress in human neuroblastoma SH-SY5Y cells

Glucagon-like peptide 1 (GLP-1) has neuroprotective properties in Alzheimer's disease (AD). In this study, our aim is to explore the neuroprotective effects of liraglutide, a GLP-1 analogue, on AD-like neurodegeneration induced by H2O2 in human neuroblastoma SH-SY5Y cells. Cytotoxicity was determined by MTT assay and lactate dehydrogenase level was monitored by LDH assay. The level of lipid peroxidation and cell apoptosis rate were measured by malondialdehyde (MDA) assay and Annexin V-FITC/propidium iodide (PI) staining. Western blotting was used to assess the expression of Bcl-2, Bax, caspase-3, tau and the Akt/GSK-3β. Liraglutide pre-treatment enhanced cell viability with reduced cytotoxicity, lipid peroxidationand and apoptosis. In addition, pre-treatment of liraglutide displayed that increased the expression of the pro-survival Bcl-2 and reduced pro-apoptotic Bax with ameliorated the hyperphosphorylation of tau and Akt/GSK-3β signaling pathway in H2O2 stressed SH-SY5Y cells. These finding provided evidences that liraglutide protected the H2O2 induced AD-like neurodegeneration through improving Akt/GSK-3β signaling pathway. These results suggest that liraglutide may have potential values for the treatment for AD.

Protective effects of liraglutide on glomerular podocytes in obese mice by inhibiting the inflammatory factor TNF-α-mediated NF-κB and MAPK pathway

ObjectiveTo evaluate the protective effects of Glucagon-like peptide-1(GLP-1) receptor agonist (liraglutide) on glomerular podocytes of obese mice, and explore the possible underlying mechanism. MethodsTwelve of the thirty-four healthy and clean male mice were randomly selected as the normal control group. The remaining twenty-two mice were included in the high-fat diet (HFD) feeding group. After twelve weeks of high-fat diet and normal diet, two mice each from the HFD feeding group and the normal control group were randomly selected and sacrificed to suggested that the modeling was successful in the HFD feeding group. Then, twenty mice were randomly divided into HFD + liraglutide group (liraglutide group, n = 10) and HFD group (n = 10). The morphology and the structure of glomerular podocytes were observed using electron microscopy. Podocyte foot process diameter, glomerular basement membrane thickness were measured. ELISA was performed to determine the serum tumor necrosis factor α (TNF-α) level. The expression levels of TNF-α protein and nuclear factor-kappa B (NF-κB) in kidney tissues, extracellularsignal regulating kinase(ERK), c-Jun N-terminal kinase (JNK) and p38MAPK in the mitogenactivated protein kinases(MAPK) pathway were detected by western blotting. ResultsHFD-feeding caused significant renal injury, podocyte pathological changes, podocyte foot process diameter and glomerular basement membrane thickness were significantly increased compared with the control group. Liraglutide injection significantly alleviated HFD-induced effects on renal functions and podocyte morphology, as 24 h urine protein, urinary albumin and podocyte histomorphology. Moreover, HFD-induced Inflammatory reaction were obviously attenuated by Liraglutide administration, so did the HFD-induced activation of TNF-α-mediated NF-κB and MAPK pathways. ConclusionLiraglutide reduced urinary albumin excretion in obesity-related glomerulopathy model mice, and improved podocyte morphology and structural damage. The mechanism may be partly related to the inhibition of TNF-α-mediated NF-κB and MAPK pathways.

817 - Protective effect of liraglutide on experimental testiculars ischemia reperfusion injury in rats

817 - Protective effect of liraglutide on experimental testiculars ischemia reperfusion injury in rats

Liraglutide improves cognitive impairment via the AMPK and PI3K/Akt signaling pathways in type 2 diabetic rats.

Liraglutide is a type of glucagon‑like‑peptide 1 receptor agonist, which has been reported as a novel type of antidiabetic agent with numerous benefits, including cardiovascular and neuroprotective effects. To the best of our knowledge, few studies to date have reported the potential mechanism underlying the neuroprotective effects of liraglutide on rats with type 2 diabetes mellitus (T2DM). The present study aimed to investigate the neuroprotective actions of liraglutide in diabetic rats and to determine the mechanisms underlying these effects. A total of 30 male T2DM Goto‑Kakizaki (GK) rats (age, 32weeks; weight, 300‑350g) and 10male Wistar rats (age, 32weeks; weight, 300‑350g) were used in the present study. Wistar rats received vehicle treatment, and GK rats randomly received treatment with vehicle, low dose of liraglutide (75µg/kg) or high dose of liraglutide (200µg/kg) for 28days. Cognitive deficits were evaluated using the Morris water maze test. The expression levels of phosphoinositide 3‑kinase (PI3K), protein kinaseB (Akt), phosphorylated (p)‑Akt, AMP‑activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), Beclin‑1, microtubule‑associated protein light chain3 (LC)‑3 II, caspase‑3, B‑cell lymphoma 2 (Bcl‑2)‑associated X protein and Bcl‑2 were assessed by western blot analysis. The results demonstrated that diabetic GK rats exhibited cognitive dysfunction, whereas treatment with liraglutide alleviated the learning and memory deficits, particularly in the high‑dose liraglutide group. The expression levels of Beclin‑1 and LC‑3II were decreased in GK rats; however, this decrease was alleviated in the presence of liraglutide. Liraglutide also reversed T2DM model‑induced increases in mTOR, and decreases in p‑AMPK, PI3K and p‑Akt expression, and modulated the expression of apoptosis‑associated proteins. Furthermore, the administration of liraglutide inhibited apoptosis and exerted a protective effect against cognitive deficits via the activation of autophagy. In conclusion, the protective effects of liraglutide may be associated with increased mTOR expression via activation of the AMPK and PI3K/Akt signaling pathways.

Liraglutide attenuates the migration of retinal pericytes induced by advanced glycation end products

Retinal pericyte migration represents a novel mechanism of pericyte loss in diabetic retinopathy (DR), which plays a crucial role in the early impairment of the blood-retinal barrier (BRB). Glucagon-like peptide-1 (GLP-1) has been shown to protect the diabetic retina in the early stage of DR; however, the relationship between GLP-1 and retinal pericytes has not been discussed. In this study, advanced glycation end products (AGEs) significantly increased the migration of primary bovine retinal pericytes without influencing cell viability. AGEs also significantly enhanced phosphatidylinositol 3-kinase (PI3K)/Akt activation, and changed the expressions of migration-related proteins, including phosphorylated focal adhesion kinase (p-FAK), matrix metalloproteinase (MMP)-2 and vinculin. PI3K inhibition significantly attenuated the AGEs-induced migration of retinal pericytes and reversed the overexpression of MMP-2. Glucagon-like peptide-1 receptor (Glp1r) was expressed in retinal pericytes, and liraglutide, a GLP-1 analog, significantly attenuated the migration of pericytes by Glp1r and reversed the changes in p-Akt/Akt, p-FAK/FAK, vinculin and MMP-2 levels induced by AGEs, indicating that the protective effect of liraglutide was associated with the PI3K/Akt pathway. These results provided new insights into the mechanism underlying retinal pericyte migration. The early use of liraglutide exerts a potential bebefical effect on regulating pericyte migration, which might contribute to mechanisms that maintain the integrity of vascular barrier and delay the development of DR.

The glucagon-like peptide-1 (GLP-1) analog liraglutide attenuates renal fibrosis

Renal fibrosis is recognized as the common route of all chronic kidney disease (CKD) progressing to end-stage renal disease (ESRD). Additionally, accumulating evidence suggests that epithelial-mesenchymal transition (EMT) plays a significant role in the process of renal fibrogenesis. Liraglutide is a long-acting glucagon-like peptide-1 (GLP-1) analog that has been widely used to treat type 2 diabetes. Recent studies have demonstrated that the GLP-1 analogs could also exert protective effects in cardiac fibrosis models. However, the effects of liraglutide on the progression of CKD remain largely unknown. In the present study, we investigated the effects of liraglutide on the progression to renal fibrosis induced by unilateral ureteral obstruction (UUO) and EMT of rat renal tubular epithelial cells (NRK-52E) induced with recombinant transforming growth factor-beta 1 (TGF-β1).The results indicated that UUO increased collagen deposition and the mRNA expression of fibronectin (FN) and collagen type I alpha 1 (Col1α1) in the obstructed kidney tissues. The effects were blunted in liraglutide-treated UUO mice compared with control mice. The upregulation of Snail1 and alpha smooth muscle actin (α-SMA), and downregulation of E-cadherin revealed that EMT occurred in the UUO kidneys, and these effects were ameliorated following liraglutide treatment. Additionally, liraglutide treatment decreased the expression of TGF-β1 and its receptor (TGF-β1R) and inhibited the activation of its downstream signaling molecules (pSmad3 and pERK1/2). The in vitro results showed that the EMT and extracellular matrix (ECM) secretion of NRK-52E cells were induced by TGF-β1. In addition, the Smad3 and ERK1/2 signaling pathways were highly activated in cells cultured with TGF-β1. All these effects were attenuated by liraglutide treatment. However, the protective effects of liraglutide were abolished by co-incubation of the GLP-1 receptor (GLP-1R) antagonist exendin-3 (9-39).These results suggest that liraglutide attenuates the EMT and ECM secretion of NRK-52E cells induced by TGF-β1 and EMT and renal fibrosis induced by UUO. The potential mechanism involves liraglutide binding to and activating GLP-1R, which prevents EMT by inhibiting the activation of TGF-β1/Smad3 and ERK1/2 signaling pathways, thereby decreasing the ECM secretion and deposition. Therefore, liraglutide is a promising therapeutic agent that may halt the progression of renal fibrosis.

Liraglutide-induced reduction of myocardial ischemiareperfusion injury in rats via ERK1/2 signaling pathway

Purpose: To investigate the protective effect of liraglutide on myocardial ischemia reperfusion (I/R) injury and its molecular mechanism. Methods: Ischemia reperfusion model male Sprague-Dawley (SD) rats were randomly divided into negative control group, I/R group (saline), liraglutide group (liraglutide) and PD group (liraglutide + PD98059). The weight of myocardium in ischemic and infarction areas of the heart, myocardial injury biomarker, oxidative stress, as well as expressions of mRNA molecules of apoptosis were determined. Results: The myocardial mass of ischemic and infarcted areas of the heart (relative to left ventricular mass) of I/R group were significantly higher ( p ˂ 0.05) than those of negative control group, but significantly lower in liraglutide group than in I/R group ( p > 0.05). However, the parameters were significantly higher in PD group than in liraglutide group ( p ˂ 0.05). CK, CK-MB and LDH activities, as well as levels of cTnI and cTnT in I/R group were significantly higher ( p ˂ 0.05) than those of negative control group. However, the parameters were significantly lower ( p ˂ 0.05) in liraglutide group than in I/R group, but higher in PD group ( p ˂ 0.05) than in liraglutide group. Serum SOD, GSH-Px, CAT activities and tBcl-2 mRNA expression were significantly lower in I/R group than those of negative control group ( p ˂ 0.001), while those PD group were significantly lower than those of liraglutide group ( p ˂ 0.001). Conclusion: Liraglutide alleviates myocardial ischemia-reperfusion injury and inhibits oxidative stress and apoptosis via ERK1/2 signaling pathway in rats, but further studies are required to ascertain the clinical efficacy and safety of the compound. Keywords: Ischemia-reperfusion injury, Liraglutide, ERK1/2 signal pathway, Oxidative stress, Apoptosis

Liraglutide ameliorates cardiotoxicity induced by doxorubicin in rats through the Akt/GSK-3β signaling pathway.

Doxorubicin (Dox)-induced cardiotoxicity constitutes the major adverse effect that limited its use. We investigated the possible protective effects of liraglutide on Dox-induced cardiotoxicity in rats. Rats were divided into the following groups: control group rats received normal saline [1ml/kg, intraperitoneal (i.p.)]; doxorubicin group rats received doxorubicin (1.25mg/kg, i.p.), four times per week for 4weeks; and liraglutide group rats received doxorubicin (1.25mg/kg, i.p.) four times per week for 4weeks then received liraglutide (100μg/kg, i.p) daily for 4weeks. At the end of the study, animals were sacrificed and serum creatine kinase-MB (CK-MB) and troponin I levels were determined. Malondialdehyde (MDA), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and caspase-3 levels of the heart were determined. Cardiac AMPK, phosphorylated-Akt, tissue growth factor-β1 (TGF-β1), and GSK3-β levels of the heart were determined. Hematoxylin and eosin (H&E) stained sections form the heart were examined as well as immunohistochemical sections for detection of Bcl-2 expression. Dox treatment increased serum level of troponin I and CK-MB while decreased SOD activity, decreased AMPK, and p-Akt cardiac levels with increased in MDA, IL-6, TNF-α,GSK-3b, TGFB1, and caspase-3 levels in the heart with inflammation and necrosis in cardiac histopathology with decreased Bcl-2. Treatment with liraglutide decreased troponin I and CK-MB while increased SOD activity, AMPK, p-Akt with decrements in MDA, IL-6, TNF-α, GSK-3β, TGF-β1, and caspase-3 levels with attenuation of inflammation and necrosis while increased Bcl-2 expression. Liraglutide may thus represent a new clinical tool for the treatment of Dox-induced cardiotoxicity.