Exendin-4 Group Research Articles

Exendin-4 promotes ischemia-reperfusion flap survival by upregulating Gpx4 to inhibit ferroptosis

BackgroundEffective drugs for preventing or treating skin flap necrosis remain elusive. In this study, we investigated the potential protective effect of exendin-4 against skin flap ischemia-reperfusion injury (IRI) through the inhibition of ferroptosis. MethodA rat abdomen was constructed with an island skin flap, and the superficial vascular pedicle of the abdominal wall was closed using a vascular clamp, which was removed after 8 h. Before surgery, RSL3 and ferrostatin-1 solutions were intraperitoneally injected. After the surgery, subcutaneous injections of exendin-4 were administered daily. The number of inflammatory cells, mean vascular density, collagen fiber content, and apoptosis and ferroptosis indicators were quantified 24 h after reperfusion. Survival, contraction rate, and blood perfusion of the skin flap were evaluated on days 1, 3, 5, and 7 after reperfusion. ResultsThe flap survival rate was significantly higher in the exendin-4 group than that in the injury group, whereas the contraction rate was lower. Compared with the injury group, the exendin-4 group showed less inflammatory cell infiltration, higher vascular density, and less collagen fiber loss. At the molecular level, the exendin-4 group demonstrated opposite or elevated expression of apoptosis and ferroptosis indicators than those in the injury group, with significantly increased glutathione peroxidase 4 (Gpx4). Ferroptosis inhibitors and agonists enhanced and reversed the protective effects of exendin-4, respectively. ConclusionExendin-4 alleviates skin flap IRI by upregulating Gpx4 expression to inhibit ferroptosis. Therefore, exendin-4 may serve as a novel clinical treatment for skin flap IRI.

Transcriptome analysis reveals the mechanism of stromal cell-derived factor-1 and exendin-4 synergistically promoted periodontal ligament stem cells osteogenic differentiation.

Stromal cell-derived factor-1 (SDF-1) and Exendin-4 (EX-4) play beneficial roles in promoting periodontal ligament stem cells (PDLSCs) osteogenic differentiation, while the detailed mechanism has not been clarified. In this study, we aimed to evaluate the biological mechanism of SDF-1 and EX-4 alone or synergistic application in regulating PDLSCs differentiation by RNA-sequencing (RNA-seq). A total of 110, 116 and 109 differentially expressed genes (DEGs) were generated in osteogenic medium induced PDLSCs treated by SDF-1, EX-4, and SDF-1+EX-4, respectively. The DEGs in SDF-1 group were enriched in signal transduction related signaling pathways; the DEGs in EX-4 group were enriched in metabolism and biosynthesis-related pathways; and the DEGs generated in SDF-1+EX-4 group were mainly enriched in RNA polymerase II transcription, cell differentiation, chromatin organization, protein phosphorylation pathways. Based on Venn analysis, a total of 37 specific DEGs were identified in SDF-1+EX-4 group, which were mainly enriched in negative regulation of autophagy and cellular component disassembly signaling pathways. Short time-series expression miner (STEM) analysis grouped all expressed genes of PDLSCs into 49 clusters according to the dynamic expression patterns and 25 genes, including NRSN2, CHD9, TUBA1A, distributed in 10 gene clusters in SDF-1+EX-4 treated PDLSCs were significantly up-regulated compared with the SDF-1 and EX-4 alone groups. The gene set enrichment analysis indicated that SDF-1 could amplify the role of EX-4 in regulating varied signaling pathways, such as type II diabetes mellitus and insulin signaling pathways; while EX-4 could aggravate the effect of SDF-1 on PDLSCs biological roles via regulating primary immunodeficiency, tight junction signaling pathways. In summary, our study confirmed that SDF-1 and EX-4 combined application could enhance PDLSCs biological activity and promote PDLSCs osteogenic differentiation by regulating the metabolism, biosynthesis and immune-related signaling pathways.

Local administration of high-dose diabetes medicine exendin-4 inhibits orthodontic tooth movement in mice.

To investigate the effects of exendin-4 on orthodontic tooth movement distance, root resorption, and expression levels of osteoclast-related cytokines in a mouse model. A 10-g NiTi coil spring was placed between the anterior alveolar bone and upper left first molar of 8-week-old male C57BL/6 mice. Twenty microliters of exendin-4 solution (containing 0.2 μg, 4 μg, or 20 μg exendin-4) or phosphate-buffered saline (PBS) were injected on the buccal side of the upper left first molar at 2-day intervals (4 mice per group). Mice were sacrificed on day 12; silicone impressions were taken to record tooth movement distance. The left maxillae of the PBS and 20 μg exendin-4 groups were also excised for histological analysis and quantitative reverse transcription polymerase chain reaction analysis. Orthodontic tooth movement distance was smaller in the 20 μg exendin-4 group than in the PBS group (P < .01). Compared with the PBS group, the 20 μg exendin-4 group showed lower osteoclast number (P < .05), odontoclast number (P < .05), and root resorption surface percentage (P < .05). Relative to maxillae with PBS injections, maxillae with 20 μg exendin-4 injections had lower receptor activator of nuclear factor kappa-B ligand (RANKL) mRNA expression (P < .05), TNF-α mRNA expression (P < .05), and RANKL/osteoprotegerin (OPG) ratio (P < .01). There were no differences in the expression of OPG mRNA. Exendin-4 inhibits orthodontic tooth movement. Therefore, additional attention is needed for orthodontic patients who receive exendin-4 for diabetes treatment. GLP-1 receptor may be a treatment target for patients with severe root resorption.

Effect of Glucose Metabolism-Associated Protein-1 on Exendin-4-Treated Pancreatic Islet Cell Function

Exendin-4 regulates blood sugar. Glucose metabolism-associated protein-1 (GMRP-1) regulates islet cell function. Therefore, this paper intends to analyze the effect of GMRP-1 on Exendin-4treated islet cells. The islet cell MIN6 cells were separated into control group, Exendin-4 group, GMRP-1 overexpressing+ Exendin-4 group, and GMRP-1 siRNA+ Exendin-4 group followed by analysis of the expression of GMRP-1 by quantitative real-time PCR and Western blot, cell proliferation by MTT, cell apoptosis by flow cytometry, Bcl-2, Bax, Fas and Fas-L expression by real-time PCR, as well as caspase-3 activity, reactive oxygen species (ROS) and superoxide dismutase (SOD) activity. Exendin-4 and GMRP-1 overexpression+ Exendin-4 significantly increased GMRP-1 expression and promoted cell proliferation, decreased apoptotic rate and Caspase-3 activity, increased Bcl-2 and Fas-L expression, reduced Fas and Bax expression, as well as decreased ROS generation and increased SOD activity (P &lt; 0 05), and the changes in GMRP-1 overexpression+ Exendin-4 group was more significant (P &lt; 0 01). However, GMRP-1 siRNA+ Exendin-4 group significantly down-regulated GMRP-1 expression, decreased MIN6 cell prolifer- ation, increased cell apoptosis and Caspase-3 activity, decreased Bcl-2 and Fas-L expression, elevated Fas and Bax expression, increased ROS content and decreased SOD activity compared to control group and Exendin-4 group (P &lt; 0 05). Up-regulation of GMRP-1 expression promoted Exendin-4-induced proliferation and inhibited apoptosis of islet cells. Down-regulation of GMRP-1 expression reversed Exendin-4's effect on islet cells.

Exendin-4 Promotes Schwann Cell Proliferation and Migration via Activating the Jak-STAT Pathway after Peripheral Nerve Injury

Peripheral nerve injury (PNI) is a common clinical disease that causes the partial loss of segmental exercise and sensory and autonomic nervous function, placing a heavy burden on patients and their families. A previous study confirmed that exendin-4 can effectively improve nerve regeneration and functional recovery after PNI. However, the specific mechanisms by which exendin-4-mediates this repair have not been clarified. To explore the mechanism of exendin-4 in the treatment of PNI, we used microarray analysis to detect gene expression in the distal segment of the sciatic nerve after sciatic injury. Bioinformatics analyses were used to predict the roles of differentially expressed genes (DEGs) in nerve damage repair. Schwann cells (SCs) were cultured, and we verified the molecular mechanism of exendin-4 in SCs and the effect of exendin-4 on peripheral nerve regeneration through in vitro molecular biology and cell biology experiments. In vivo, exendin-4 could significantly promote peripheral nerve regeneration. A total of 180 DEGs between the exendin-4 group and the control group were detected. Bioinformatics analysis indicated that these DEGs were mainly enriched in the Jak-STAT signaling pathway. In vitro, exendin-4 could significantly promote the proliferation and migration of SCs by activating the Jak-STAT pathway, which promoted peripheral nerve regeneration. Our results indicate that exendin-4 promotes SC proliferation, migration and nerve regeneration after PNI by activating the Jak-STAT pathway. Our findings provide a basis and direction for further elucidation of the mechanisms of exendin-4 in the repair of PNI and provide a new way to treat PNI.

Antophagy inhibition can decrease AR42J cell apoptosis induced by exendin-4

Objective To explore whether exendin-4 inhibits AR42J cells and its mechanism. Methods AR42J cells were treated with exendin-4 under multiple concentrations(1, 5, 10 pmol/L) at 24, 48, 72, 96, 120 h to assess its cell viability by MTT assay and got the IC-50 and time points. Then checking whether exendin-4 could induce the AR42Jcells apoptosis by setting normal control (NC) group, exendin-4 (Ex-4) group and Ex-4+ z-VAD-fmk (apoptosis inhibitor) group, and exploring whether 3-MA which is autophagy inhibitor could inhibit the AR42J cells apoptosis induced by exendin-4 by setting NC group, Ex-4 group and Ex-4+ 3-MA group. Cell viability was analyzed by MTT and the cells apoptosis was detected by flow cytometry and the protein levels of caspase-3, LC3 and p62 were studied by Western blot. Results Concentration of 10 pmol/L exendin-4 and and time point 72 h were selected for the further study . z-VAD-fmk pretreatment can significantly inhibit the cell viability of exendin-4 by (81.2±3.3)% vs. (49.4±3.0)% (P<0.05). Flow cytometry showed that exendin-4 could induce the AR42J cells apoptosis by (28.2±1.4)% vs. (3.6±0.8)%, and increased the caspase-3 level by Western blot, which both can be reversed by (79.1±2.3)% vs. (49.8±2.5)% (P<0.05) when the cells were treated for 72 h, as was apoptosis ratio by (14.5±2.1)% vs. (29.2±3.2)%. Western blot showed that exendin-4 can upregulate protein levels of LC3B-II, p62和caspase-3 and 3-MA, and pretreatment can inhibit the upregulation of LC3B-II and caspase-3 but further increased the upregulation of p62 induced by exendin-4. Conclusions Exendin-4 can induce AR42J cells apoptosis and 3-MA pretreating can inhibit exendin-4 cytotoxicity through downregulating autophagy. So autophagy inhibitor 3-MA could potentially extenuate the cytotoxicity of exendin-4 in pancreatic acinar cells. Key words: Exendin-4; Pancreatic acinar cell; Apoptosis; Autophagy inhibitor, 3-MA

Exendin-4 improves behaviorial deficits via GLP-1/GLP-1R signaling following partial hepatectomy

Recent studies indicate that glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) agonists exhibit neurotrophic and neuroprotective effects. The aim of this study was to explore whether the GLP-1R agonist exendin-4 can alter surgery-induced behavioral deficits and exert neuroprotective effects via the activation of the hippocampal GLP-1/GLP-1R pathway. 120 male Sprague-Dawley rats (aged 18–20 months old) were randomly divided into four groups: control group, exendin-4 group, surgery group, and surgery + exendin-4 group. The animals received either exendin-4 (5 µg/kg/day) or saline intra-peritoneally for 14 days, and then were subjected to partial hepatectomy 24 h after the last injection. Behavioral changes were evaluated with Morris Water Maze and Open field testing on postoperative days 7 and 14. The levels of IL-1β, NF-κB, Iba-1, Synaptophysin, GLP-1/GLP-1R, GSK-3β, p-GSK-3β (Ser9), p-Tau (Ser396), and p-Tau (Ser202/199) in the hippocampus were measured at the same time point. Surgical trauma induced an exacerbated spatial learning and memory impairment, increased the levels of depressive performance, and enhanced hippocampal NF-κB and IL-1β expression in the aged rats on postoperative day 7. A corresponding decline in GLP-1R was also found following surgical challenge on postoperative day 7. Exendin-4 treatment partly reversed surgery-induced postoperative behavioral impairment, downregulated the levels of NF-κB and IL-1β, ameliorated tau hyperphosphorylation and enhanced the activity of p-GSK-3β (Ser9). Together, the downregulation of GLP-1R exacerbated surgery-induced behavior deficits. Exendin-4 treatment attenuated these effects by inhibiting neuroinflammation and tau hyperphosphorylation. These findings suggest that pretreatment with exendin-4 is a potential adjuvant for preventing surgery-induced behavioral deficits.

Attenuation of High Glucose-Induced Rat Cardiomyocyte Apoptosis by Exendin-4 via Intervention of HO-1/Nrf-2 and the PI3K/AKT Signaling Pathway

Exendin-4, a glucagon-like peptide-1 receptor agonist, demonstrated cytoprotective actions beyond glycemic control in recent studies. The aims of the present study were to investigate the effects of exendin-4 on high glucose (HG)-induced cardiomyocyte apoptosis and the possible mechanisms. Rat cardiomyocytes were divided into 3 groups: normal glucose group (NG group), HG group and HG +exendin-4 group (HG+Ex Group). Cardiomyocyte apoptosis was evaluated by double-staining with annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) and flow cytometry. Intracellular reactive oxygen species (ROS) production was detected by 2’,7’-dichlorodihydrofluorescein diacetate (DCHF-DA) incubation and fluorescence microscopy. LY294002 (LY), a phosphoinositide 3-kinase (PI3K) pathway inhibitor, was added to the medium of the HG+Ex+LY Group for further western blot analysis. The proteins analyzed involved oxidative stress-associated proteins, heme oxygenase-1 (HO-1) and nuclear factor E2-related factor 2 (Nrf-2), and apoptosis-associated proteins, caspase-3, Bax/B-cell lymphoma 2 (Bcl-2) and p-AKT/AKT. HG treatment induced cardiomyocyte apoptosis (P = 0.00) and clearly upregulated ROS production (P = 0.00); exendin-4 co-incubation also ameliorated cardiomyocyte apoptosis (P = 0.004) and decreased ROS (P = 0.00) level significantly. HO-1 and Nrf-2 protein expression levels decreased significantly in the HG group (P < 0.05), but the levels were elevated by exendin-4 intervention (P < 0.05). Furthermore, exendin-4 attenuated HG-induced higher protein expression, including cleaved caspase-3 and Bax, increased the expression of Bcl-2 protein (P < 0.05). However, these impacts of exendin-4 were counteracted significantly by co-incubation with LY294002. In addition, exendin-4 ameliorated HG-induced p-AKT/AKT lower expression, and this impact was also suppressed by LY294002. Exendin-4 ameliorates HG-induced cardiomyocyte apoptosis, and the mechanisms may involve anti-oxidative stress via the HO-1/Nrf-2 system, as well as intervention of the PI3K/AKT signaling pathway.

Effect of exendin-4 on lipid deposition in skeletal muscle of diet-induced obese mice and its underlying mechanism

Objective: To investigate the effect of exendin-4, a glucagon-like peptide-1 (GLP-1) receptor agonist, on reducing lipid deposition and improving insulin resistance in skeletal muscle and the underlying mechanisms in high-fat diet (HFD)-induced obese mice. Methods: Twelve male C57BL/6J mice were challenged with HFD for 12 weeks to induce obesity and then randomly divided into two groups: exendin-4 group (intraperitoneal injection of 24 nmol·kg-1·d-1 exendin-4 for 4 weeks) and HFD group (intraperitoneal injection of normal saline for 4 weeks), with 6 mice in each group. Additional 6 mice were also selected as control group. Body weight, fasting blood glucose were recorded. Serum triglyceride (TG), total cholesterol (TC), insulin and skeletal muscle triglyceride levels were measured by enzyme-linked immunosobent assay (ELISA). Oil red O staining was used for morphologic changes of frozen sections from skeletal muscle. The protein levels of lipid metabolic pathway mediated by AMP-activated protein kinase (AMPK) and insulin signailing pathway were determined by Western blot. Results: Compared with mice in HFD group, exendin-4 significantly decreased body weight[(37.68±1.80) vs (46.03±5.00) g, P<0.025], fasting blood glucose[(5.40±0.33) vs (7.65±1.92) mmol/L, P<0.025], serum TG[(37.78±7.14) vs (80.76±34.22) mg/dl, P<0.025], TC[(180.13±18.75) vs (217.57±22.52) mg/dl, P<0.025], insulin[(0.58±0.01) vs (1.67±1.23) ng/ml, P<0.025]and skeletal muscle TG levels[(9.84±1.08) vs (19.35±7.44) mg/g, P<0.025]of obese mice. Oil red O staining revealed that exendin-4 alleviated the accumulation of larger lipid droplets in skeletal muscle. The protein expressions of lipolysis and lipid oxidation mediated by AMPK and insulin signailing pathway were up-regulated, and the protein expressions of lipogenesis mediated by AMPK were down-regulated after intervention of exendin-4. Conclusion: Exendin-4 reduces lipid deposition and insulin resistance in skeletal muscle of HFD-induced obese mice via activating AMPK and up-regulating insulin signailing pathway.

Exendin-4 Induces Bone Marrow Stromal Cells Migration Through Bone Marrow-Derived Macrophages Polarization via PKA-STAT3 Signaling Pathway

Background/Aims: The synthesis and degradation processes involved in bone remodeling are critically regulated by osteoblasts and osteoclasts. The GLP-1 receptor agonist Exendin-4 is beneficial for osteoblast differentiation and increases the number of osteoblasts. Methods: We constructed an ovariectomized model to evaluate the impact of Exendin-4 on bone formation in osteoporosis. A macrophage-depleted model was also created to investigate the effect of macrophages on bone formation. Thirty-two female WT C57BL/6 mice (aged 3 months) were randomly assigned to a normal control group and four ovariectomized (OVX) subgroups: OVX + vehicle group, OVX + Exendin-4 (4.2 µg/kg/day) group, OVX + chloride phosphate liposome group and OVX + chloride phosphate liposome + Exendin-4 group. Results: In this study, we found that Exendin-4 not only increased the number of osteoblasts and decreased the number of osteoclasts, but also increased the number of bone marrow stromal cells (BMSCs) at the bone surface. Moreover, we found that OVX mice treated with Exendin-4 increased TGF-β1 levels at the bone surface compared with that in OVX mice. Besides, Exendin-4 promoted the polarization of bone marrow-derived macrophages into M2 subtype and increased TGF-β1 secretion by the M2 subtype. Finally, we found that Exendin-4 induced macrophage polarization via the cAMP-PKA-STAT3 signaling pathway. Conclusion: Exendin-4 promotes bone marrow-derived macrophage polarization to the M2 subtype and induces BMSC migration to the bone surface via PKA-STAT3 signaling.

Influences of exendin-4 on the secretion function of islet beta cells from rats in the early stage of severe scald

Objective: To observe the secretion function changes of islet beta cells isolated from rats in the early stage of severe scald, and to explore the influence of them. Methods: Thirty-six Wistar rats were divided into sham injury (SI) group, sham injury+ exendin-4 (SIE) group, scald (S) group, and scald+ exendin-4 (SE) group according to the random number table, with 9 rats in each group. Rats in groups S and SE were inflicted with 50% total body surface area full-thickness scald by a 12-s immersion of back and a 6-s immersion of abdomen in 94 ℃ hot water. Rats in groups SI and SIE were sham injured through immersion of back and abdomen in 37 ℃ warm water. Rats in groups S and SE were subcutaneously injected with exendin-4 (4 μg/kg) twice a day post injury, while rats in groups SI and SIE were subcutaneously injected with sterile water in the same volume. At post injury hour (PIH) 72, the following detections were performed. Eight rats of each group were respectively selected to measure level of fasting blood glucose with cutting-tail method, and to detect plasma level of glucagon-like peptide 1 (GLP-1) and serum level of insulin by enzyme-linked immunosorbent assay (ELISA). The insulin resistant index (HOMA-IR) was calculated. Six rats of each group were respectively selected for islet isolation. The isolated rat islets were stimulated with RPMI 1640 medium containing 2.8 or 16.7 mmol/L glucose, respectively. Insulin content in supernatant was detected by ELISA, and insulin secretion index was calculated with 6 samples in each group. The isolated islets from 3 rats of each group were selected for the observation of the super-structure of islet beta cells under transmission electron microscope. The number of docked granules in per 10 μm membrane of islet beta cells and the ratio of insulin vesicles to the total insulin granules were calculated with 3 samples in each group. Data were processed with one-way analysis of variance and LSD test. Results: (1) Compared with that in group S, levels of fasting blood glucose of rats in group SI, SIE, and SE were significantly decreased (P 0.05). Under stimulation of 16.7 mmol/L glucose, compared with that in group SI, the insulin secretion content of rats in groups SIE and SE were significantly increased (P<0.05 or P<0.01), while in group S it was significantly decreased (P<0.05). Compared with that in group SE, the insulin secretion content of rats in group S was significantly decreased (P<0.01) . Compared with that in group S, the insulin secretion content of rats in group SE was significantly increased (P<0.01). Compared with that in group SI (2.25±0.20), the insulin secretion index of rats in group SE (2.68±0.24) was significantly increased (P<0.05). Compared with that in group SIE (2.47±0.18), the insulin secretion index of rats in group S (2.11±0.28) was significantly decreased (P<0.05). Compared with that in group S, the insulin secretion index of rats in group SE was significantly increased (P<0.01). (4) Compared with those in group SI, the number of docked granules per 10 μm membrane of islet beta cells in group SE was significantly increased (P<0.05), while the ratio of insulin vesicles of rat islet beta cells in group S was significantly increased (P<0.01). Compared with those in group SE, the number of docked granules per 10 μm membrane of islet beta cells in group S was significantly decreased (P<0.01), while the ratio of insulin vesicles of rat islet beta cells was significantly increased (P<0.05). Compared with those in group S, the number of docked granules per 10 μm membrane of islet beta cells in group SE was significantly increased (P<0.01), while the ratio of insulin vesicles of rat islet beta cells was significantly decreased (P<0.05). Conclusions: In the early stage of severe scald in rats, level of GLP-1 is decreased and the insulin secretion function of islet beta cells is injured. Long-lasting GLP-1 analogous exendin-4 can improve the secretion function of isolated islet beta cells from severely scalded rats.

The influence of exendin-4 intervention on -obese diabetic mouse blood and the pancreatic tissue immune microenvironment.

The aim of the study was to determine the influence of exendin-4 intervention on non-obese diabetic (NOD) mouse blood and the pancreatic tissue immune microenvironment. A total of 40 clean NOD mice were used in the study and randomly divided into 4 groups (n=10/group). The first group was blank control group D with normal saline intervention, and with different doses of exendin, i.e.,-4 2, 4 and 8 µg/kg/day. The three remaining groups were: i) Low-dose group A; ii) medium-dose group B; and iii) high-dose group C. Mice in the four groups went through intervention for 8 weeks. Their mass and blood glucose levels were tested each week. After 8 weeks, the mice were sacrificed, and mouse serum samples were reserved. The ELISA method was used to test peripheral blood (PB), IL-2, IFN-γ and IL-10 levels. Pancreatic samples were created. Immunohistochemistry was used to observe the infiltration degree of mouse pancreatitis and the local expression state of pancreatic IL-10. Mouse pancreatic tissues were suspended in pancreatic cell suspension. Flow cytometry was used to test the state of T-cell subsets CD4 and CD25. Mouse pancreatitis in control group D was mainly at grade 2and 3. Under a light microscope, it was observed that pancreatic cell morphology was in disorder, and the size and quantity of the pancreas was small. Mouse pancreatitis in the exendin-4 low-dose group A, medium-dose group B and high-dose group C was mainly at grade 0 and 1. Under a light microscope, it was observed that pancreatic cell morphology improved, the infiltration degree of lymphocyte was improved and pancreatic islet size was restored somewhat. Additionally, a few brownish granules were identified within the pancreatic sample cells in control group D. There were many brownish granules with deep color within the pancreatic sample cells in exendin-4 low-dose group A, medium-dose group B and high-dose group C. IL-10 immunohistochemistry scores in the low-dose group A, medium-dose group B and high-dose group C were 3.82±0.72, 4.34±0.86 and 4.81±0.94, respectively, and were higher than the score of 2.25±0.63 in control group D. CD4+CD25+T-cell proportions in mouse pancreatic tissues of low-dose group A, medium-dose group B and high-dose group C were 5.31, 5.53 and 5.74%, respectively, which were higher than that of the CD4+CD25+T-cell proportion (1.62% in control group D). The CD4+CD25high T-cell proportion in CD4+T-cells in group A, B and C increased. Compared with control group D, serum IL-10 levels in the exendin-4 low-dose group A, medium-dose group B and high-dose group C increased (P<0.05), while levels of IL-2 and IFN-γ decreased (P<0.05). Additionally, the difference of serum IL-10, IL-2 and IFN-γ levels in the low-dose group A, medium-dose group B and high-dose group C was of statistical significance (P<0.05). Exendin-4 intervention can increase quantities of CD4 and CD8+T cells in NOD mouse pancreases, with PB IL-10 expression and local expression of IL-10 in pancreatic tissues. It also can inhibit the expression of serum IL-2 and IFN-γ, regulate the organism immune microenvironment and prevent diabetes. CD4+CD25high T cells increase in NOD tumor infiltration lymphocytes mediated by exendin-4 intervention, which may be related to the fact that exendin-4 inhibits the lethal effect of CD8+T cells through contact among cells and eventually exerts immunosuppressive effect.

EFFECTS OF C -PEPTIDE AND GLUCAGON-LIKE PEPTIDE-1 ON DIABETIC MALE ALBINO RATS WITH AND WITHOUT ANTIOXIDANTS

Background: Diabetes mellitus is a major health problem with long-term complications responsible for its mortality and morbidity. Administration of C-peptide improves nervous and renal functions in diabetic patients and animals. Glucagon like peptide-1 is secreted in response to meal. It is able to increase the disposal of glucose under hyperglycemic conditions independent of its effect on insulin or glucagon. An interesting analog is exendin-4. Objective: Determination of the effects of C-peptide and glucagon-like peptide-1 analogue exendin-4 with and without antioxidants on blood and plasma levels of glucose, insulin, glucagon, lipid profile and malondialdehyde (MDA) in diabetic model of adult male albino rats. Material and Methods: Seventy adult male albino rats of local strain weighed 150-180 g were used in this study. They were divided into seven equal groups: Control group (C): Rats received saline i.p. daily for 4 weeks, Diabetes group (D1): After overnight fasting, rats received a single subcutaneous injection of alloxan monohydrate with glucose by gastric intubation to avoid fatal hypoglycemia, Diabetes with C-peptide (D2) were given alloxan and C-peptide by intraperitoneal injection for 4 weeks, Diabetes with exendin-4 (D3) were given alloxan and glucagon-like peptide -1 (GLP-1) analog exendin-4 i.p. for 4 weeks, Diabetes with C–peptide and exendin-4 (D4) were given combined intraperitoneal injection of C-peptide and exendin-4 with alloxan for 4 weeks, Diabetes with antioxidants (vitamins C & E) (D5) received alloxan, vitamin C and vitamin E by gastric intubation for 4 weeks, Diabetes with C–peptide, exendin-4 and antioxidants (vitamins C & E) (D6) received combined C-peptide, exendin-4 and vitamins C and E in by gastric intubation with alloxan for 4 weeks. Blood samples were taken from all groups. Blood glucose, plasma insulin, plasma glucagon, plasma lipid profile, and plasma level of malondialdehyde (MDA) with their relationships to C–peptide and exendin-4 (D4) treatment with and without antioxidants (vitamins C & E) supplementation were investigated. Results: Treatment of diabetic rats by C-peptide and exendin-4 caused significant reduction in total cholesterol, triglycerides, LDL, MDA and glucose with elevated insulin and HDL. Treatment of diabetic rats by C-peptide and exendin-4 with antioxidants (vitamins C & E) showed reduction of glucose, cholesterol, LDL and triglycerides with significantly elevated insulin in comparison to diabetic group. Conclusion: Adding C–peptide to exendin-4 caused significant reduction in total triglycerides, cholesterol, and more reduction of LDL than exendin-4 group. Vitamins C & E improved serum lipid profile and level of MDA as an oxidative stress indicator.

Effects of exendin-4 on GFAP and IL-1βexpression in hippocampi of aged rats

Objective To evaluate the effects of exendin-4 on glial brillary acidic protein （GFAP ） and interleukin-1β（IL-1β） expression in hippocampi of aged rats .Methods Forty-eight healthy male Sprague-Dawley rats ,aged 22-24 weeks ,weighing 500-700 g ,were randomly divided into 4 groups （n=12 each） using a random number table：control group （group C ） ,exendin-4 group （group E ） ,operation group （group O ） and exendin-4 plus operation group （group OE） .The rats were anesthetized with intraperitoneal fentanyl and droperidol .Groups C and E did not receive anesthesia or splenectomy .In O and OE groups ,splenectomy was carried out .In E and OE groups , exendin-4 5 μg/kg was injected intraperitoneally at 30 min before skin incision and 12 h after operation .C and O groups received the equal volume of normal saline instead of exendin-4 .Learning and memory function was assessed using Morris water maze test （escape latency （EL） and total swimming distance （TSD） at 1 day before operation （T0 ） .The fasting blood glucose was measured after anesthesia （T1 ） ,at the end of operation （T2 ） and on postoperative day 1 （T3 ） .The rats were sacrificed after assessment of the cognitive function at T 3 and the hippocampi were removed for determination of the expression of GFAP （by immuno-histochemistry ） and IL-1β（by Western blot ） .Results There was no significant difference in the EL and TSD at T0 between the four groups＆nbsp;（ P〉0.05） .Compared with group C ,the EL and TSD were significantly prolonged at T3 and fasting blood glucose was increased at T2 ,3 ,and the expression of IL-1βand GFAP was up-regulated at T3 in O and OE groups （ P〈0.05） .Compared with group O ,the EL and TSD were significantly prolonged at T3 and fasting blood glucose was decreased at T2 ,3 ,and the expression of IL-1βand GFAP was down-regulated at T3 in group OE （ P〈0.05） . Conclusion Exendin-4 can improve the postoperative cognitive function of aged rats by inhibiting inflammatory responses in hippocampi and maintaining stable perioperative blood glucose . Key words: Glucagon-like peptide 1; Cognition disorders; Hippocampus; Inflammation; Blood glucose

Exendin-4, a Glucagon-Like Peptide-1 Receptor Agonist, Provides Neuroprotection in Mice Transient Focal Cerebral Ischemia

Glucagon-like peptide-1 (GLP-1) is an incretin hormone known to stimulate glucose-dependent insulin secretion. The GLP-1 receptor agonist, exendin-4, has similar properties to GLP-1 and is currently in clinical use for type 2 diabetes mellitus. As GLP-1 and exendin-4 confer cardioprotection after myocardial infarction, this study was designed to assess the neuroprotective effects of exendin-4 against cerebral ischemia–reperfusion injury. Mice received a transvenous injection of exendin-4, after a 60-minute focal cerebral ischemia. Exendin-4-treated vehicle and sham groups were evaluated for infarct volume, neurologic deficit score, various physiologic parameters, and immunohistochemical analyses at several time points after ischemia. Exendin-4 treatment significantly reduced infarct volume and improved functional deficit. It also significantly suppressed oxidative stress, inflammatory response, and cell death after reperfusion. Furthermore, intracellular cyclic AMP (cAMP) levels were slightly higher in the exendin-4 group than in the vehicle group. No serial changes were noted in insulin and glucose levels in both groups. This study suggested that exendin-4 provides neuroprotection against ischemic injury and that this action is probably mediated through increased intracellular cAMP levels. Exendin-4 is potentially useful in the treatment of acute ischemic stroke.