Efecto de la dieta CAF sobre la capacidad de EX4 de modular la expresión de marcadores proteicos de oxidación de ácidos grasos y termogénesis en músculo de ratones / Effect of the CAF diet on the ability of EX4 to modulate the expression of protein markers of fatty acid oxidation and thermogenesis in mouse muscle

El ambiente obesogénico promueve la obesidad al facilitar el acceso y consumo de una amplia variedad de alimentos palatables altos en calorías. La activación del receptor de GLP1 (GLP1R) reduce la ingesta de alimentos, enlentece el vaciamiento gástrico y promueve un balance energético negativo a través de su acción en distintos órganos como el músculo esquelético, disminuyendo así el peso corporal. La obesidad inducida por dieta alta en grasa disminuye el efecto anorexigénico de la administración sistémica vía intra-peritoneal de EX4 (agonista de GLP1R). Sin embargo, se desconoce si la exposición a un ambiente obesogénico previo a la manifestación de obesidad disminuye los efectos anorexigénicos de EX4 o un posible efecto de EX4 sobre marcadores de oxidación de ácidos grasos y termogénesis en músculo esquelético. El objetivo de esta investigación fue determinar el efecto a corto plazo de la dieta CAF, un modelo del ambiente obesogénico humano, sobre la capacidad de EX4 de reducir la ingesta y modular la expresión de marcadores proteicos de oxidación de ácidos grasos y termogénesis (CPT1 y UCP2) en músculo de ratones. Nuestros datos muestran que una inyección intraperitoneal de EX4 a ratones C57BL/6J alimentados con dieta CAF o dieta control durante 10 días no altera la ingesta calórica total, peso corporal, o la expresión de proteínas marcadoras de los procesos de beta-oxidación y de termogénesis (CPT1 y UCP2). Estos datos sugieren que protocolos alternativos de administración de EX4 son necesarios para observar los efectos fisiológicos de la activación de GLP1R.

The obesogenic environment promotes obesity by facilitating access to and consumption of a wide variety of palatable, high-calorie foods. Activation of the GLP1 receptor (GLP1R) reduces food intake, slows gastric emptying, and promotes a negative energy balance by acting on organs such as skeletal muscle, thus decreasing body weight. Obesity induced by a high-fat diet decreased the anorexigenic effect of intraperitoneal systemic administration of EX4 (GLP1R agonist). However, it is unknown whether exposure to an obesogenic environment before the manifestation of obesity diminishes the anorexigenic effects of EX4 or a possible effect of EX4 on markers of fatty acid oxidation and thermogenesis in skeletal muscle. This investigation aimed to determine the short-term effect of the CAF diet, a model of the human obesogenic environment, on the ability of EX4 to reduce intake and modulate the expression of protein markers of fatty acid oxidation and thermogenesis (CPT1 and UCP2) in mouse muscle. Our data show that intraperitoneal injection of EX4 to C57BL/6J mice fed CAF diet or control diet for ten days does not alter total caloric intake, body weight, or expression of proteins markers of beta-oxidation and thermogenesis processes (CPT1 and UCP2). These data suggest that alternative EX4 administration protocols are necessary to observe the physiological effects of GLP1R activation.

Short-term combined treatment with exenatide and metformin for overweight/obese women with polycystic ovary syndrome / 中华医学杂志(英文版)

BACKGROUND@#Obesity and insulin resistance (IR) are common features of polycystic ovary syndrome (PCOS). Metformin (MET) increases insulin sensitivity, but it is associated with unsatisfactory weight loss. The glucagon-like peptide-1 receptor agonist exenatide has been shown to reduce weight and IR in patients with diabetes. This study aimed to explore the therapeutic effects of exenatide once-weekly (QW) combined with MET on body weight, as well as metabolic and endocrinological parameters in overweight/obese women with PCOS.@*METHODS@#Fifty overweight/obese women with PCOS diagnosed via the Rotterdam criteria were randomized to one of two treatment groups: MET (500 mg three times a day [TID]) or combination treatment (COM) (MET 500 mg TID, exenatide 2 mg QW) for 12 weeks. The primary outcomes were anthropometric changes associated with obesity, and the secondary outcomes included changes in reproductive hormone levels, glucose and lipid metabolism, and C-reactive protein.@*RESULTS@#Forty (80%) patients completed the study. COM therapy was superior to MET monotherapy in reducing weight (P = 0.045), body mass index (BMI) (P = 0.041), and waist circumference (P = 0.023). Patients in the COM group on an average lost 3.8 ± 2.4 kg compared with 2.1 ± 3.0 kg in the MET group. In the COM group, BMI and waist circumference decreased by 1.4 ± 0.87 kg/m2 and 4.63 ± 4.42 cm compared with 0.77 ± 1.17 kg/m2 and 1.72 ± 3.07 cm in the MET group, respectively. Moreover, levels of fasting glucose, oral glucose tolerance test (OGTT) 2-h glucose, and OGTT 2-h insulin were significantly lower with COM therapy than with MET (P < 0.050). Mild and moderate gastrointestinal reactions were the most common adverse events in both groups.@*CONCLUSIONS@#COM therapy was more effective than MET alone in reducing body weight, BMI, and waist circumference, and improving insulin sensitivity in overweight/obese women with PCOS, with acceptable short-term side effects.@*TRIAL REGISTRATION@#ClinicalTrials.gov, NCT04029272. https://clinicaltrials.gov/ct2/show/NCT04029272.

Comparative study on anorexigenic effect of glucagon-like peptide-1 receptor agonists in rats / 生理学报

Glucagon-like peptide-1 (GLP-1) expression is shared by both intestinal cells and neurons of brainstem, which plays anorexigenic role on food intake. However, the exact source of physiological GLP-1 influencing food intake and pertinent mechanism of GLP-1 receptor agonists (GLP-1RA) remain unelucidated. In this study, the immediate early gene product c-Fos was chosen as the specific antigen for immunohistochemistry to show the certain areas of central nervous system (CNS) activation by the GLP-1RA. Thirty normal SD rats were randomly assigned to 3 groups, which were single intraperitoneally injected with Liraglutide (200 μg/kg), Exenatide (10 μg/kg) and saline, respectively. After injection, the amount of food intake and acute glycemic variation were assessed for comparison. The results showed that acute pharmacological dosage of GLP-1RA (Liraglutide or Exenatide) could significantly influence food intake. However, glycemic change indicated that the anorexic effect was dissociated with change in blood glucose in normal rats. Moreover, c-Fos was expressed significantly higher in major critical nuclei related to food intake in GLP-1RA groups when compared with the control group, and its expression was also found in spinal cord. The results suggested that acute administration of pharmacological doses of GLP-1 influences CNS via circulation and vagal pathways, especially on the arcuate nucleus (ARC) and the nucleus of solitary tract (NTS), and GLP-1 modulates autonomic nervous activities.

Effects of Exendin-4 on the differentiation of neural stem cells from subventricular zone of adult mice in vitro / 中国应用生理学杂志

OBJECTIVE@#To study the effect of exendin-4(Ex-4) on the differentiation of neural stem cells(NSCs) in adult mouse subventricular zone(SVZ)and its mechanism .@*METHODS@#NSCs in the SVZ were derived from 5-week C57BL/6J mice and the expression of nestin was detected by immunofluorescence. The cell morphology was observed after the cells treatmed with 100 nmol/L Ex-4 for 14 days.The expressions of nestin and glucagon-like peptide-1 receptor (GLP-1R) were detected by immunofluorescence. GLP-1R was knocked down by using shRNA and the study was divided into four groups: control group, Ex-4 group, GLP-1R knockdown group, GLP-1R knockdown + Ex-4 group. After treatment with 100 nmol/L Ex-4 for 14 d, β-tublin III and glial fibrillary acidic protein (GFAP) were labeled by immunofluorescence and then the proportion of β-tublin III positive cells were counted. Western blot was used to detect the activation of cAMP-response element binding protein (CREB) in NSCs. In order to further study the effects of Ex-4 on mitogen-activated protein kinase(MAPK) and phosphatidylinositol 3-hydroxy kinase (PI3K) pathways, the cells were pretreated with MAPK inhibitor U0126 at a concentration of 0.07 μmol/L for 30 min or PI3K inhibitor LY294002 at 50 μmol for 2 h, respectively. The study was divided into six groups: control group, Ex-4 group, U0126 group, U0126 + Ex-4 group, LY294002 group, LY294002 + Ex-4 group. The activation of CREB in each group was detected by Western blot. The experiment was repeated three times independently.@*RESULTS@#NSCs were successfully extracted from SVZ of C57BL/6J mice. Immunofluorescence showed that nestin and GLP-1R were positive in NSCs. Compared with the control group, the proportion of neurons differentiated from Ex-4 group was higher. The percentage of neurons in GLP-1R knockdown + Ex-4 group was basically the same as that in control group (P＜0.01). The positive cells of beta-tublin III showed positive activation of GLP-1R and CREB. Western blot showed that CREB was significantly activated in the Ex-4 group, and knockdown of GLP-1R abolished its activation (P＜0.01). U0126 did not affect Ex-4-mediated CERB activation, and LY294002 significantly reduced Ex-4-mediated CREB activation (P＜0.01).@*CONCLUSION@#Ex-4 promotes the differentiation of NSCs into neurons in SVZ of adult mice through GLP-1R receptor, which may be achieved through PI3K/CREB pathway.

Exendin-4 alleviates oxidative stress and liver fibrosis by activating Nrf2/HO-1 in streptozotocin-induced diabetic mice / 南方医科大学学报

OBJECTIVE@#To investigate the effects of exendin-4 on hepatic lipid metabolism, fibrosis and oxidative stress in mice with streptozotocin (STZ)-induced diabetes and explore the underlying mechanisms.@*METHODS@#C57BL/6J mice were fed with high-fat diet (HFD) for 4 weeks and received intraperitoneal injections of 120 mg/kg STZ to induce diabetes. After successful modeling, the mice were randomized into diabetic control group and exendin-4 treatment group (DM+E4), and in the latter group, the mice were given a daily dose of 1 nmol/kg of exendin-4 for 8 weeks. The changes in the body weight (BW) and random blood glucose (RBG) in the mice were recorded. The mRNA expressions of the genes related with liver lipid metabolism, fibrosis and oxidative stress were analyzed using RT-PCR, and the structural changes of the liver tissues were observed with HE, Sirius red and oil red O staining; the expressions of TGF-β1, Nrf2 and HO-1 proteins in the liver tissues were detected using Western blotting.@*RESULTS@#The diabetic mice showed significantly higher RBG levels and BW with obvious lipid deposition, fibrosis and oxidative stress in the liver as compared with the normal control mice ( < 0.001). Exendin-4 treatment of the diabetic mice did not significantly lessened liver lipid deposition but obviously reduced the levels of RBG and TG ( < 0.05), lowered the expression levels of liver fibrosis-related genes TGF-β, -SMA and Col-Ⅰ ( < 0.05), increased the expression levels of the antioxidant genes Nrf2, HO-1 and GPX4 ( < 0.01), and enhanced the protein expressions of Nrf2 and HO-1 in the liver tissues ( < 0.01).@*CONCLUSIONS@#Exendin-4 improves liver fibrosis and oxidative stress in diabetic mice by activating Nrf2/HO-1 pathway without significantly reducing liver lipid deposition.

An experimental study of exenatide effects on renal injury in diabetic rats

Abstract Purpose: To investigate the effects of exenatide on renal injury in streptozotocin-induced diabetic rats. Methods: Fifty SD rats were randomly divided into normal control, model, exenatide-1, exenatide-2 and exenatide-3 groups, 10 rats in each group. The diabetic nephropathy model was constructed in later 4 groups. Then, the later 3 groups were treated with 2, 4 and 8 μg/kg exenatide for 8 weeks, respectively. The serum and urine biochemical indexes and oxidative stress and inflammatory indexes in renal tissue were determined. Results: Compared to the model group, in exenatide-3 group the serum fasting plasma glucose and hemoglobin A1c levels were significantly decreased, the fasting insulin level was significantly increased, the renal index and blood urea nitrogen, serum creatinine and 24 h urine protein levels were significantly decreased, the renal tissue superoxide dismutase and glutathione peroxidase levels were significantly increased, the malondialdehyde level was significantly decreased, and the renal tissue tumor necrosis factor alpha, interleukin 6, hypersensitive C-reactive protein and chemokine (C-C motif) ligand 5 levels were significantly decreased P<0.05). Conclusions: Exenatide can mitigate the renal injury in diabetic rats. The mechanisms may be related to its resistance of oxidative stress and inflammatory response in renal tissue.

Exenatide ameliorates hepatic steatosis and attenuates fat mass and FTO gene expression through PI3K signaling pathway in nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a common disease associated with metabolic syndrome and can lead to life-threatening complications like hepatic carcinoma and cirrhosis. Exenatide, a glucagon-like peptide-1 (GLP-1) receptor agonist antidiabetic drug, has the capacity to overcome insulin resistance and attenuate hepatic steatosis but the specific underlying mechanism is unclear. This study was designed to investigate the underlying molecular mechanisms of exenatide therapy on NAFLD. We used in vivo and in vitro techniques to investigate the protective effects of exenatide on fatty liver via fat mass and obesity associated gene (FTO) in a high-fat (HF) diet-induced NAFLD animal model and related cell culture model. Exenatide significantly decreased body weight, serum glucose, insulin, insulin resistance, serum free fatty acid, triglyceride, total cholesterol, low-density lipoprotein, aspartate aminotransferase, and alanine aminotransferase levels in HF-induced obese rabbits. Histological analysis showed that exenatide significantly reversed HF-induced lipid accumulation and inflammatory changes accompanied by decreased FTO mRNA and protein expression, which were abrogated by PI3K inhibitor LY294002. This study indicated that pharmacological interventions with GLP-1 may represent a promising therapeutic strategy for NAFLD.

Injection of submandibular gland with recombinant Exendin-4 and adeno-associated virus for the treatment of diabetic rats / 中南大学学报(医学版)

OBJECTIVE@#To evaluate the therapeutic effects of recombinant Exendin-4 and double-stranded adeno-associated virus (Exendin-4/dsAAV) on SD rats with type 2 diabetes (T2DM) through injecting it into submandibular gland (SG).
@*METHODS@#The Exendin-4/dsAAV was injected into submandibular gland of diabetic rat. The insulin and α-amylase were detected by real-time PCR at the 2nd, 4th and 8th weeks. The immunohistochemisty was used to detect the insulin contents in SG at the 8th week. The concentration of blood glucose and levels of insulin secretion were detected after pancreatectomy.
@*RESULTS@#The SG gland was bigger in Exendin-4/dsAAV group than that in the control group, but the changes in α-amylase were not significant. The Exendin-4 and insulin gene expression was increased in the Exendin-4/dsAAV group (P<0.05). The Exendin-4 and insulin were positive in the SG. The blood glucose was lower and insulin concentration was higher in the Exendin-4/dsAAV group than those in the control group after pancreatectomy (P<0.05), and the insulin content was also increased in the dsAAV groups.
@*CONCLUSION@#Continuous expression of Exendin-4 in SG may improve glucose control and insulin secretion in T2DM rats through inducing expression of insulin.

Biological activity studies of the novel glucagon-like peptide-1 derivative HJ07 / 中国天然药物

AIM@#To identify the glucose lowering ability and chronic treatment effects of a novel coumarin-glucagon-like peptide-1 (GLP-1) conjugate HJ07.@*METHOD@#A receptor activation experiment was performed in HEK 293 cells and the glucose lowering ability was evaluated with hypoglycemic duration and glucose stabilizing tests. Chronic treatment was performed by daily injection of exendin-4, saline, and HJ07. Body weight and HbA1c were measured every week, and an intraperitoneal glucose tolerance test was performed before treatment and after treatment.@*RESULTS@#HJ07 showed well-preserved receptor activation efficacy. The hypoglycemic duration test showed that HJ07 possessed a long-acting, glucose-lowering effect and the glucose stabilizing test showed that the antihyperglycemic activity of HJ07 was still evident at a predetermined time (12 h) prior to the glucose challenge (0 h). The long time glucose-lowering effect of HJ07 was better than native GLP-1 and exendin-4. Furthermore, once daily injection of HJ07 to db/db mice achieved long-term beneficial effects on HbA1c lowering and glucose tolerance.@*CONCLUSION@#The biological activity results of HJ07 suggest that HJ07 is a potential long-acting agent for the treatment of type 2 diabetes.