RESUMEN

The hypothalamic neuropeptides linked to appetite and satiety were investigated in obese mice treated with cotadutide (a dual receptor agonist of glucagon-like peptide 1 (GLP-1R)/Glucagon (GCGR)). Twelve-week-old male C57BL/6 mice were fed a control diet (C group, n = 20) or a high-fat diet (HF group, n = 20) for ten weeks. Each group was further divided, adding cotadutide treatment and forming groups C, CC, HF, and HFC for four additional weeks. The hypothalamic arcuate neurons were labeled by immunofluorescence, and protein expressions (Western blotting) for neuropeptide Y (NPY), proopiomelanocortin (POMC), agouti-related protein (AgRP), and cocaine- and amphetamine-regulated transcript (CART). Cotadutide enhanced POMC and CART neuropeptides and depressed NPY and AGRP neuropeptides. In addition, gene expressions (RT-qPCR) determined that Lepr (leptin receptor) and Calcr (calcitonin receptor) were diminished in HF compared to C but enhanced in CC compared to C and HFC compared to HF. Besides, Socs3 (suppressor of cytokine signaling 3) was decreased in HFC compared to HF, while Sst (somatostatin) was higher in HFC compared to HF; Tac1 (tachykinin 1) and Mc4r (melanocortin-4-receptor) were lower in HF compared to C but increased in HFC compared to HF. Also, Glp1r and Gcgr were higher in HFC compared to HF. In conclusion, the findings are compelling, demonstrating the effects of cotadutide on hypothalamic neuropeptides and hormone receptors of obese mice. Cotadutide modulates energy balance through the gut-brain axis and its associated signaling pathways. The study provides insights into the mechanisms underlying cotadutide's anti-obesity effects and its possible implications for obesity treatment.

Asunto(s)

Glucagón , Neuropéptidos , Péptidos , Ratones , Animales , Masculino , Proteína Relacionada con Agouti , Glucagón/metabolismo , Ratones Obesos , Proopiomelanocortina/genética , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Ratones Endogámicos C57BL , Neuropéptidos/genética , Hipotálamo/metabolismo , Neuropéptido Y/genética , Péptido 1 Similar al Glucagón/metabolismo

RESUMEN

Prior research demonstrated that glucagon has protective roles against inflammation, but its effect on the resolution of inflammation remains elusive. Using in vitro and in vivo approaches, this study aimed to investigate the pro-resolving potential of glucagon on pulmonary neutrophilic inflammation caused by lipopolysaccharide. Lipopolysaccharide induced an increase in the proportions of neutrophils positives to glucagon receptor (GcgR) in vitro. In addition, lipopolysaccharide induced an increase in the neutrophil accumulation and expression of GcgR by the inflammatory cells in the lungs, however, without altering glucagon levels. Intranasal treatment with glucagon, at the peak of neutrophilic inflammation, reduced the neutrophil number in the bronchoalveolar lavage (BAL), and lung tissue within 24 h. The reduction of neutrophilic inflammation provoked by glucagon was accompanied by neutrophilia in the blood, an increase in the apoptosis rate of neutrophils in the BAL, enhance in the pro-apoptotic Bax protein expression, and decrease in the anti-apoptotic Bcl-2 protein levels in the lung. Glucagon also induced a rise in the cleavage of caspase-3 in the lungs; however, it was not significant. Glucagon inhibited the levels of IL-1ß and TNF-α while increasing the content of pro-resolving mediators transforming growth factor (TGF-ß1) and PGE2 in the BAL and lung. Finally, glucagon inhibited lipopolysaccharide-induced airway hyper-reactivity, as evidenced by the reduction in lung elastance values in response to methacholine. In conclusion, glucagon-induced resolution of neutrophilic inflammation by promoting cessation of neutrophil migration and a rise of neutrophil apoptosis and the levels of pro-resolving mediators TGF-ß1 and PGE2.

Asunto(s)

Glucagón , Lipopolisacáridos , Ratones , Animales , Lipopolisacáridos/farmacología , Glucagón/metabolismo , Factor de Crecimiento Transformador beta1/metabolismo , Dinoprostona/farmacología , Pulmón , Inflamación/metabolismo , Neutrófilos/metabolismo

RESUMEN

BACKGROUND: Enteroendocrine L cells can be found in the entire gastrointestinal tract and their incretins act on glycemic control and metabolic homeostasis. Patients with severe obesity and type 2 diabetes mellitus may have lower density of L cells in the proximal intestine. AIMS: This study aimed to analyze the density of L cells in the segments of the small intestine in the late postoperative of Roux-en-Y gastric bypass in diabetic patients with standardization of 60 cm in both loops, alimentary and biliopancreatic. METHODS: Immunohistochemistry analysis assays were made from intestinal biopsies in three segments: gastrointestinal anastomosis (GIA= Point A), enteroenteral anastomosis (EEA= Point B= 60 cm distal to the GIA) and 60 cm distal to the enteroenteral anastomosis (Point C). RESULTS: A higher density of L cells immunostaining the glucagon-1 peptide was observed in the distal portion (Point C) when compared to the more proximal portions (Points A and B). CONCLUSIONS: The concentration of L cells is higher 60 cm distal to enteroenteral anastomosis when comparing to proximal segments and may explain the difference in intestinal lumen sensitization and enterohormonal response after Roux-en-Y gastric bypass.

Asunto(s)

Diabetes Mellitus Tipo 2 , Derivación Gástrica , Obesidad Mórbida , Anastomosis en-Y de Roux , Diabetes Mellitus Tipo 2/cirugía , Células Enteroendocrinas/metabolismo , Glucagón/metabolismo , Humanos , Incretinas/metabolismo , Obesidad Mórbida/cirugía , Resultado del Tratamiento

RESUMEN

There are doubts about the impact of non-nutritive sweeteners consumption on lipogenic and glycolytic metabolism. Therefore, the objective was to determine the effects of chronic consumption of sweeteners on the activity levels of the enzymes glucokinase (GK), phosphofructokinase-1 (PFK-1), pyruvate kinase (PKL), acetyl coenzyme A carboxylase (ACC), and fatty acid synthase (FAS) in livers' extracts. Groups of male and female Wistar rats drank solutions of sweeteners for 480 days: Sucrose 10%, glucose 14%, fructose 7%, acesulfame K 0.05%, aspartame:acesulfame mixture 1.55%, sucralose 0.017%, saccharin 0.033%, and a control group. The enzymatic activity in livers' extracts was determined. Likewise, the levels of glucose, triglycerides, insulin, glucagon, and leptin were determined. In both genders, there were significant differences in the levels of enzymatic activity, hormonal, and biochemical parameters due to sweeteners consumption. The highest glycolytic and lipogenic enzyme activity levels were observed in the groups that ingested nutritive sweeteners and saccharin.

Asunto(s)

Edulcorantes no Nutritivos , Sacarina , Animales , Ratas , Femenino , Masculino , Sacarina/metabolismo , Aspartame , Edulcorantes no Nutritivos/farmacología , Leptina , Edulcorantes Nutritivos , Glucoquinasa/metabolismo , Acetil-CoA Carboxilasa/metabolismo , Piruvato Quinasa/metabolismo , Glucagón/metabolismo , Ratas Wistar , Edulcorantes/farmacología , Sacarosa , Glucosa/metabolismo , Insulina/metabolismo , Fructosa , Triglicéridos/metabolismo , Hígado/metabolismo , Ácido Graso Sintasas/metabolismo

RESUMEN

The therapeutic arsenal for treating type 2 diabetes mellitus (T2DM) has been enriched recently with the inclusion of type 1 glucagon-like peptide (GLP-1). GLP-1 receptor agonists (RA) secondarily reduce appetite, decrease gastric emptying, and reduce body weight. This effect has been used to treat overweight/obesity, especially with comorbidities associated with T2DM. However, the first formulations and adverse effects gradually gave way to new formulations with fewer unpleasant effects and a more extended period of action (weekly subcutaneous administration and even oral administration), which improved the acceptance and adherence to the treatment. Therefore, titration of GLP-1RA should be done gradually. Furthermore, when side effects are consistent and intolerable after weeks/months of titration, a lower dose or a combination of antidiabetic therapies should be implemented, avoiding treatment interruption. The effort to produce increasingly powerful molecules with fewer side effects is the driving force behind the pharmaceutical industry. The unimolecular dual agonism GLP-1RA plus glucagon receptor agonism (GRA) represents an updated pharmacological indication for controlling blood glucose levels in treating T2DM and its comorbidities, showing better effects with less adverse impact than mono GLP-1RA. There are currently different proposals in this way by different laboratories. Nevertheless, the experimental results are promising and show that soon, we will have the contribution of new drugs for the treatment of T2DM.

Asunto(s)

Diabetes Mellitus Tipo 2/tratamiento farmacológico , Péptido 1 Similar al Glucagón/agonistas , Receptor del Péptido 1 Similar al Glucagón/agonistas , Glucagón/metabolismo , Hipoglucemiantes/uso terapéutico , Incretinas/uso terapéutico , Obesidad/tratamiento farmacológico , Animales , Diabetes Mellitus Tipo 2/patología , Humanos , Obesidad/fisiopatología

RESUMEN

Sepsis is one of the most common comorbidities observed in diabetic patients, associated with a deficient innate immune response. Recently, we have shown that glucagon possesses anti-inflammatory properties. In this study, we investigated if hyperglucagonemia triggered by diabetes might reduce the migration of neutrophils, increasing sepsis susceptibility. 21 days after diabetes induction by intravenous injection of alloxan, we induced moderate sepsis in Swiss-Webster mice through cecum ligation and puncture (CLP). The glucagon receptor (GcgR) antagonist des-his1-[Glu9]-glucagon amide was injected intraperitoneally 24h and 1h before CLP. We also tested the effect of glucagon on CXCL1/KC-induced neutrophil migration to the peritoneal cavity in mice. Neutrophil chemotaxis in vitro was tested using transwell plates, and the expression of total PKA and phospho-PKA was evaluated by western blot. GcgR antagonist restored neutrophil migration, reduced CFU numbers in the peritoneal cavity and improved survival rate of diabetic mice after CLP procedure, however, the treatment did no alter hyperglycemia, CXCL1/KC plasma levels and blood neutrophilia. In addition, glucagon inhibited CXCL1/KC-induced neutrophil migration to the peritoneal cavity of non-diabetic mice. Glucagon also decreased the chemotaxis of neutrophils triggered by CXCL1/KC, PAF, or fMLP in vitro. The inhibitory action of glucagon occurred in parallel with the reduction of CXCL1/KC-induced actin polymerization in neutrophils in vitro, but not CD11a and CD11b translocation to cell surface. The suppressor effect of glucagon on CXCL1/KC-induced neutrophil chemotaxis in vitro was reversed by pre-treatment with GcgR antagonist and adenylyl cyclase or PKA inhibitors. Glucagon also increased PKA phosphorylation directly in neutrophils in vitro. Furthermore, glucagon impaired zymosan-A-induced ROS production by neutrophils in vitro. Human neutrophil chemotaxis and adherence to endothelial cells in vitro were inhibited by glucagon treatment. According to our results, this inhibition was independent of CD11a and CD11b translocation to neutrophil surface or neutrophil release of CXCL8/IL-8. Altogether, our results suggest that glucagon may be involved in the reduction of neutrophil migration and increased susceptibility to sepsis in diabetic mice. This work collaborates with better understanding of the increased susceptibility and worsening of sepsis in diabetics, which can contribute to the development of new effective therapeutic strategies for diabetic septic patients.

Asunto(s)

Movimiento Celular/efectos de los fármacos , Diabetes Mellitus Experimental/complicaciones , Susceptibilidad a Enfermedades/etiología , Glucagón/administración & dosificación , Neutrófilos/efectos de los fármacos , Sepsis/etiología , Sepsis/inmunología , Adulto , Animales , Movimiento Celular/inmunología , Quimiotaxis de Leucocito/efectos de los fármacos , Diabetes Mellitus Experimental/inmunología , Diabetes Mellitus Experimental/microbiología , Femenino , Glucagón/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos , Neutrófilos/inmunología

RESUMEN

NEW FINDINGS: What is the central question of this study? Type 1 diabetes mellitus (T1D) leads to hyperglycaemia owing to pancreatic ß-cell destruction by the immune system. Physical exercise has been shown to have potentially beneficial protective roles against cytokine-induced pancreatic ß-cell death, but its benefits are yet to be proved and should be understood better, especially in the islet environment. What is the main finding and its importance? Physical exercise protects against ß-cell loss in a well-described animal model for T1D, induced by multiple low doses of streptozotocin. This seems to be related to reduced cytokine-induced ß-cell death and increased islet cell proliferation. Contributions of islet neogenesis and/or transdifferentiation of pancreatic non-ß-cells into ß-cells cannot be excluded. ABSTRACT: Physical exercise has beneficial effects on pancreatic ß-cell function and survival in a pro-inflammatory environment. Although these effects have been linked to decreased islet inflammation and modulation of pro-apoptotic pathways, little is known about the islet microenvironment. Our aim was to evaluate the effects of physical exercise in islet histomorphology in a mouse model of type 1 diabetes mellitus induced by multiple low doses of streptozotocin. As expected, induction of type 1 diabetes mellitus led to ß-cell loss and, consequently, decreased islet area. Interestingly, although the decrease in islet area was not prevented by physical exercise, this was not the case for the decrease in ß-cell mass. This was probably related to induction of ß-cell regeneration, because we observed increased proliferation and regeneration markers, such as Ki67 and Pcna, in islets of trained mice. These were found in the central and peripheral regions of the islets. An increase in the percentage of α- and δ-cells in these conditions, combined with an increase in proliferation and Pax4 labelling in peripheral regions, suggest that ß-cell regeneration might also occur by transdifferentiation. This agrees with the presence of cells double stained for insulin and glucagon only in islets of diabetic trained mice. In addition, this group had more extra-islet insulin-positive cells and islets associated with ducts than diabetic mice. Physical exercise also decreased nuclear factor-κB activation in islet cells of diabetic trained compared with diabetic untrained mice, indicating a decrease in pro-inflammatory cytokine-induced ß-cell death. Taken together, these findings indicate that preservation of ß-cell mass induced by physical exercise involves an increase in ß-cell replication and decrease in ß-cell death, together with islet neogenesis and islet cell transdifferentiation.

Asunto(s)

Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 1 , Células Secretoras de Insulina , Islotes Pancreáticos , Animales , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 1/metabolismo , Glucagón/metabolismo , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Ratones

RESUMEN

We evaluated whether protein restriction during pregnancy alters the morphometry of pancreatic islets, the intra-islet glucagon-like peptide-1 (GLP-1) production, and the anti-apoptotic signalling pathway modulated by GLP-1. Control non-pregnant (CNP) and control pregnant (CP) rats were fed a 17% protein diet, and low-protein non-pregnant (LPNP) and low-protein pregnant (LPP) groups were fed a 6% protein diet. The masses of islets and ß-cells were similar in the LPNP group and the CNP group but were higher in the CP group than in the CNP group and were equal in the LPP group and the LPNP group. Both variables were lower in the LPP group than in the CP group. Prohormone convertase 2 and GLP-1 fluorescence in α-cells was lower in the low-protein groups than in the control groups. The least PC2/glucagon colocalization was observed in the LPP group, and the most was observed in the CP group. There was less prohormone convertase 1/3/glucagon colocalization in the LPP group than in the CP group. GLP-1/glucagon colocalization was similar in the LPP, CP and CNP groups, which showed less GLP-1/glucagon colocalization than the LPNP group. The mRNA Pka, Creb and Pdx-1 contents were higher in islets from pregnant rats than in islets from non-pregnant rats. Protein restriction during pregnancy impaired the mass of ß-cells and the intra-islet GLP-1 production but did not interfere with the transcription of genes of the anti-apoptotic signalling pathway modulated by GLP-1.

Asunto(s)

Dieta con Restricción de Proteínas/efectos adversos , Péptido 1 Similar al Glucagón/metabolismo , Células Secretoras de Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Animales , Regulación hacia Abajo , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Redes Reguladoras de Genes/efectos de los fármacos , Glucagón/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Islotes Pancreáticos/efectos de los fármacos , Embarazo , Proproteína Convertasa 2/metabolismo , Ratas

RESUMEN

Nutritional recovery of early malnutrition with a soybean diet reduces liver glycogen stores in the fed state and produces liver insulin resistance. We investigated whether nutritional recovery on a soybean flour diet alters hepatic gluconeogenesis in the adult offspring of rats deprived of protein during pregnancy and lactation. Male rats from mothers that were fed either 17% (C) or 6% (L) protein during pregnancy and lactation were maintained on a 17% casein (CC, n = 16 and LC, n = 17), 17% soybean flour (CS, n = 10 and LS, n = 10), or 6% casein (LL, n = 10) diet after weaning. The soybean diet reduced basal serum glucose (soybean diet, 5.6 ± 0.6 mmol/L vs. casein diet, 6.2 ± 0.6 mmol/L; p < 0.05) but increased alanine aminotransferase mRNA/GAPDH (soybean diet, 0.062 ± 0.038 vs. casein diet, 0.024 ± 0.011; p < 0.01), phosphoenolpyruvate carboxykinase mRNA/GAPDH (soybean diet, 1.53 ± 0.52 vs. casein diet, 0.95 ± 0.43; p < 0.05), and glycerokinase protein content (soybean diet, 0.86 ± 0.08 vs. casein diet, 0.75 ± 0.11; p < 0.05). The serum glucose concentration (recovered groups, 5.6 ± 0.5 mmol/L vs. control groups, 6.2 ± 0.7 mmol/L; p < 0.05) and phosphoenolpyruvate carboxykinase activity (recovered groups, 2.8 ± 0.6 µU/mg vs. control groups, 3.6 ± 0.6 µU/mg; p < 0.05) were decreased in rats subjected to protein restriction in early life. The glucose area under the curve during the pyruvate tolerance test did not differ among groups, whereas glucose area under the curve after glucagon infusion was reduced by early malnutrition (recovered groups, 4210 ± 572 mg/dL·40 min vs. control groups, 4493 ± 688 mg/dL·40 min; p < 0.001) and by the soybean diet (soybean diet, 3995 ± 500 mg/dL·40 min vs. casein diet, 4686 ± 576 mg/dL·40 min; p < 0.05). Thus, the soybean diet impaired the response to glucagon but did not alter gluconeogenesis.

Asunto(s)

Alimentación Animal , Glucagón/metabolismo , Gluconeogénesis , Glycine max/metabolismo , Hígado/metabolismo , Efectos Tardíos de la Exposición Prenatal , Desnutrición Proteico-Calórica/dietoterapia , Factores de Edad , Animales , Dieta con Restricción de Proteínas , Modelos Animales de Enfermedad , Femenino , Regulación Enzimológica de la Expresión Génica , Gluconeogénesis/genética , Lactancia , Hígado/enzimología , Masculino , Estado Nutricional , Embarazo , Fenómenos Fisiologicos de la Nutrición Prenatal , Desnutrición Proteico-Calórica/genética , Desnutrición Proteico-Calórica/metabolismo , Desnutrición Proteico-Calórica/fisiopatología , Ratas Wistar

RESUMEN

Gluconeogenesis overstimulation due to hepatic insulin resistance is the best-known mechanism behind elevated glycemia in obese subjects with hepatic steatosis. This suggests that glucose production in fatty livers may differ from that of healthy livers, also in response to other gluconeogenic determinant factors, such as the type of substrate and modulators. Thus, the aim of this study was to investigate the effects of these factors on hepatic gluconeogenesis in cafeteria diet-induced obese adult rats submitted to a cafeteria diet at a young age. The livers of the cafeteria group exhibited higher gluconeogenesis rates when glycerol was the substrate, but lower rates were found when lactate and pyruvate were the substrates. Stearate or glucagon caused higher stimulations in gluconeogenesis in cafeteria group livers, irrespective of the gluconeogenic substrates. An increased mitochondrial NADH/NAD⁺ ratio and a reduced rate of 14CO2 production from [14C] fatty acids suggested restriction of the citric acid cycle. The higher glycogen and lipid levels were possibly the cause for the reduced cellular and vascular spaces found in cafeteria group livers, likely contributing to oxygen consumption restriction. In conclusion, specific substrates and gluconeogenic modulators contribute to a higher stimulation of gluconeogenesis in livers from the cafeteria group.

Asunto(s)

Dieta/efectos adversos , Ácidos Grasos/metabolismo , Hígado Graso/inducido químicamente , Glucagón/metabolismo , Gluconeogénesis/efectos de los fármacos , Animales , Ingestión de Energía , Conducta Alimentaria , Glucosa/metabolismo , Ácido Láctico/administración & dosificación , Ácido Láctico/farmacología , Masculino , Obesidad/inducido químicamente , Consumo de Oxígeno , Ácido Pirúvico/administración & dosificación , Ácido Pirúvico/farmacología , Ratas , Ratas Wistar

RESUMEN

Glucagon dysregulation is an essential component in the pathophysiology of type 2 diabetes. Studies in vitro and in animal models have shown that zinc co-secreted with insulin suppresses glucagon secretion. Zinc supplementation improves blood glucose control in patients with type 2 diabetes, although there is little information about how zinc supplementation may affect glucagon secretion. The objective of this study was to evaluate the effect of 1-year zinc supplementation on fasting plasma glucagon concentration and in response to intravenous glucose and insulin infusion in patients with type 2 diabetes. A cross-sectional study was performed after 1-year of intervention with 30 mg/day zinc supplementation or a placebo on 28 patients with type 2 diabetes. Demographic, anthropometric, and biochemical parameters were determined. Fasting plasma glucagon and in response to intravenous glucose and insulin infusion were evaluated. Patients of both placebo and supplemented groups presented a well control of diabetes, with mean values of fasting blood glucose and glycated hemoglobin within the therapeutic goals established by ADA. No significant differences were observed in plasma glucagon concentration, glucagon/glucose ratio or glucagon/insulin ratio fasting, after glucose or after insulin infusions between placebo and supplemented groups. No significant effects of glucose or insulin infusions were observed on plasma glucagon concentration. One-year zinc supplementation did not affect fasting plasma glucagon nor response to intravenous glucose or insulin infusion in well-controlled type 2 diabetes patients with an adequate zinc status.

Asunto(s)

Diabetes Mellitus Tipo 2/metabolismo , Suplementos Dietéticos , Glucagón/sangre , Glucosa/administración & dosificación , Hipoglucemiantes/administración & dosificación , Insulina/administración & dosificación , Zinc/administración & dosificación , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/dietoterapia , Femenino , Glucagón/metabolismo , Glucosa/uso terapéutico , Humanos , Hipoglucemiantes/uso terapéutico , Infusiones Intravenosas , Insulina/uso terapéutico , Masculino , Persona de Mediana Edad , Zinc/farmacología , Zinc/uso terapéutico

RESUMEN

Menopausal women are at high risk of developing heart disease. However, physical exercise practice can reverse this scenario. We evaluated the biochemical, morphological, and physiological effects of moderate aerobic physical exercise on the pancreas of knockout mice for LDL receptor with estrogen deprivation by ovariectomy. Animals were divided into six groups (n = 5): sedentary non-ovariectomized control; sedentary ovariectomized control; trained ovariectomized control; sedentary non-ovariectomized LDL-R knockout; sedentary ovariectomized LDL-R knockout; and trained ovariectomized LDL-R knockout. Physical exercise practice promoted improvement in biometric and biochemical parameters analyzed, with reduction of visceral adipose tissue and VLDL, triglycerides, total cholesterol, and blood glucose levels. In addition, physical exercise practice altered the morphology of pancreatic islets and improved their response to the effects of menopause. Thus, physical exercise practice was fundamental to minimize the effects of dyslipidemia associated with ovariectomy in the pancreatic tissue of LDL-R knockout animals, contributing to reduce the risk of developing cardiac diseases in the menopause period.

Asunto(s)

Dislipidemias/fisiopatología , Páncreas/fisiología , Condicionamiento Físico Animal/fisiología , Animales , Estrógenos/metabolismo , Femenino , Glucagón/metabolismo , Insulina/metabolismo , Grasa Intraabdominal/fisiología , Menopausia , Ratones Endogámicos C57BL , Ratones Noqueados , Ovariectomía , Receptores de LDL/genética

RESUMEN

OBJECTIVE: Despite increasing evidence that pharmacologic concentrations of biotin modify glucose metabolism, to our knowledge there have not been any studies addressing the effects of biotin supplementation on glucagon production and secretion, considering glucagon is one of the major hormones in maintaining glucose homeostasis. The aim of this study was to investigate the effects of dietary biotin supplementation on glucagon expression, secretion, and action. METHODS: Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet (1.76 or 97.7 mg biotin/kg diet) for 8 wk postweaning. Glucagon gene mRNA expression was measured by the real-time polymerase chain reaction. Glucagon secretion was assessed in isolated islets and by glucagon concentration in plasma. Glucagon action was evaluated by glucagon tolerance tests, phosphoenolpyruvate carboxykinase (Pck1) mRNA expression, and glycogen degradation. RESULTS: Compared with the control group, glucagon mRNA and secretion were increased from the islets of the biotin-supplemented group. Fasting plasma glucagon levels were higher, but no differences between the groups were observed in nonfasting glucagon levels. Despite the elevated fasting glucagon levels, no differences were found in fasting blood glucose concentrations, fasting/fasting-refeeding glucagon tolerance tests, glycogen content and degradation, or mRNA expression of the hepatic gluconeogenic rate-limiting enzyme, Pck1. CONCLUSIONS: These results demonstrated that dietary biotin supplementation increased glucagon expression and secretion without affecting fasting blood glucose concentrations or glucagon tolerance and provided new insights into the effect of biotin supplementation on glucagon production and action.

Asunto(s)

Biotina/administración & dosificación , Glucagón/metabolismo , Glucagón/farmacología , Animales , Dieta , Suplementos Dietéticos , Expresión Génica/efectos de los fármacos , Glucagón/genética , Gluconeogénesis/efectos de los fármacos , Glucógeno/metabolismo , Islotes Pancreáticos/química , Islotes Pancreáticos/metabolismo , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , Fosfoenolpiruvato Carboxiquinasa (GTP)/genética , ARN Mensajero/análisis

RESUMEN

Patients with pancreatic-insufficient cystic fibrosis (PI-CF) are at increased risk for developing diabetes. We determined ß-cell secretory capacity and insulin secretory rates from glucose-potentiated arginine and mixed-meal tolerance tests (MMTTs), respectively, in pancreatic-sufficient cystic fibrosis (PS-CF), PI-CF, and normal control subjects, all with normal glucose tolerance, in order to identify early pathophysiologic defects. Acute islet cell secretory responses were determined under fasting, 230 mg/dL, and 340 mg/dL hyperglycemia clamp conditions. PI-CF subjects had lower acute insulin, C-peptide, and glucagon responses compared with PS-CF and normal control subjects, indicating reduced ß-cell secretory capacity and α-cell function. Fasting proinsulin-to-C-peptide and proinsulin secretory ratios during glucose potentiation were higher in PI-CF, suggesting impaired proinsulin processing. In the first 30 min of the MMTT, insulin secretion was lower in PI-CF compared with PS-CF and normal control subjects, and glucagon-like peptide 1 and gastric inhibitory polypeptide were lower compared with PS-CF, and after 180 min, glucose was higher in PI-CF compared with normal control subjects. These findings indicate that despite "normal" glucose tolerance, adolescents and adults with PI-CF have impairments in functional islet mass and associated early-phase insulin secretion, which with decreased incretin responses likely leads to the early development of postprandial hyperglycemia in CF.

Asunto(s)

Fibrosis Quística/metabolismo , Fibrosis Quística/patología , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patología , Páncreas/metabolismo , Páncreas/patología , Adolescente , Adulto , Péptido C/metabolismo , Insuficiencia Pancreática Exocrina/metabolismo , Femenino , Polipéptido Inhibidor Gástrico/metabolismo , Glucagón/metabolismo , Péptido 1 Similar al Glucagón/metabolismo , Glucosa/metabolismo , Prueba de Tolerancia a la Glucosa , Humanos , Incretinas/metabolismo , Insulina/metabolismo , Masculino , Persona de Mediana Edad , Proinsulina/metabolismo , Adulto Joven

RESUMEN

Neuromedin B (NB) and gastrin-releasing peptide (GRP) are bombesin-like peptides, found in the gastrointestinal tube and pancreas, among other tissues. Consistent data proposed that GRP stimulates insulin secretion, acting directly in pancreatic cells or in the release of gastrointestinal hormones that are incretins. However, the role of NB remains unclear. We examined the glucose homeostasis in mice with deletion of NB receptor (NBR-KO). Female NBR-KO exhibited similar fasting basal glucose with lower insulinemia (48.4%) and lower homeostasis model assessment of insulin resistance index (50.5%) than wild type (WT). Additionally, they were more tolerant to oral glucose, demonstrated by a decrease in the area under the glucose curve (18%). In addition, 15 min after an oral glucose load, female and male NBR-KO showed lower insulin serum levels (45.6 and 26.8%, respectively) than WT, even though blood glucose rose to similar levels in both groups. Single injection of NB, one hour before the oral glucose administration, tended to induce higher serum insulin in WT (28.9%, p=0.3), however the same did not occur in NBR-KO. They showed no changes in fasting insulin content in pancreatic islets by immunohistochemistry, however, the fasting serum levels of glucagon-like peptide, a potent incretin, exhibited a strong trend to reduction (40%, p=0.07). Collectively, mice with deletion of NB receptor have lower insulinemia, especially in response to oral glucose, and females also exhibited a better glucose tolerance, suggesting the involvement of NB and its receptor in regulation of insulin secretion induced by incretins, and also, in insulin sensitivity.

Asunto(s)

Eliminación de Gen , Glucosa/administración & dosificación , Glucosa/farmacología , Insulina/metabolismo , Receptores de Bombesina/metabolismo , Administración Oral , Animales , Ayuno , Femenino , Glucagón/metabolismo , Péptido 1 Similar al Glucagón/metabolismo , Prueba de Tolerancia a la Glucosa , Homeostasis/efectos de los fármacos , Islotes Pancreáticos/efectos de los fármacos , Islotes Pancreáticos/patología , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Neuroquinina B/administración & dosificación , Neuroquinina B/análogos & derivados , Neuroquinina B/farmacología , Receptores de Bombesina/deficiencia

RESUMEN

PURPOSE: This study evaluates whether the daily practice of an exercise routine might protect from endocrine pancreas damage in cola drinking rats. METHODS: Forty-eight Wistar rats were randomly assigned to 4 groups depending on a) beverage consumption ad libitum, water (W) or cola beverage (C), and b) physical activity, sedentary (S) or treadmill running (R). Accordingly, 4 groups were studied: WS (water sedentary), WR (water runner), CS (cola sedentary) and CR (cola runner). Body weight, nutritional data, plasma levels of glucose, creatinine, total cholesterol and cholesterol fractions, and triglycerides (enzymocolorimetry), and systolic blood pressure (plethysmography) were measured. After 6 months, euthanasia was performed (overdose sodium thiopental). Pancreatic tissue was immediately excised and conventionally processed for morphometrical and immunohistochemical determinations. RESULTS: The effects of running and chronic cola drinking on pancreas morphology showed interaction (p<0.001) rather than simple summation. Cola drinking (CS vs WS) reduced median pancreatic islet area (-30%, 1.8 10(4) µm2 vs 2.58 10(4) µm2, p<0.0001) and median ß-cell mass (-43%, 3.81 mg vs 6.73 mg, p<0.0001), and increased median α/ß ratio (+49%, 0.64 vs 0.43, p< 0.001). In water drinking rats (WR vs WS), running reduced median α-cell mass (-48%, 1.48 mg vs 2.82 mg, p<0.001) and α/ß ratio (-56%, 0.19 vs 0.43, p<0.0001). Differently, in cola drinking rats (CR vs CS), running partially restored median islet area (+15%, 2.06 10(4) µm2 vs 1.79 10(4) µm2, p<0.05), increased median ß-cell mass (+47%, 5.59 mg vs 3.81 mg, p <0.0001) and reduced median α/ß ratio (-6%, 0.60 vs 0.64, p<0.05). CONCLUSION: This study is likely the first reporting experimental evidence of the beneficial effect of exercise on pancreatic morphology in cola-drinking rats. Presently, the increase of nearly 50% in ß cells mass by running in cola drinking rats is by far the most relevant finding. Moderate running, advisably indicated in cola consumers and patients at risk of diabetes, finds here experimental support.

Asunto(s)

Bebidas Gaseosas/efectos adversos , Ingestión de Líquidos , Islotes Pancreáticos/efectos de los fármacos , Islotes Pancreáticos/metabolismo , Condicionamiento Físico Animal , Animales , Biomarcadores , Peso Corporal/efectos de los fármacos , Glucagón/metabolismo , Inmunohistoquímica , Insulina/metabolismo , Islotes Pancreáticos/patología , Ratas

RESUMEN

Amylin is a pancreatic hormone cosecreted with insulin that exerts unique roles in metabolism and glucose homeostasis. The therapeutic restoration of postprandial and basal amylin levels is highly desirable in diabetes mellitus. Protein conjugation with the biocompatible polymer polyethylene glycol (PEG) has been shown to extend the biological effects of biopharmaceuticals. We have designed a PEGylated human amylin by using the aminoreactive compound methoxylpolyethylene glycol succinimidyl carbonate (mPEGsc). The synthesis in organic solvent resulted in high yields of monoPEGylated human amylin, which showed large stability against aggregation, an 8 times increase in half-life in vivo compared to the non-conjugated amylin, and pharmacological activity as shown by modulation of cAMP production in MCF-7 cell line, decrease in glucagon and modulation of glycemia following subcutaneous administration in mice. Altogether these data reveal the potential use of PEGylated human amylin for the restoration of fasting amylin levels.

Asunto(s)

Polipéptido Amiloide de los Islotes Pancreáticos/química , Polietilenglicoles/química , Animales , Glucemia/efectos de los fármacos , AMP Cíclico/metabolismo , Glucagón/metabolismo , Homeostasis/efectos de los fármacos , Humanos , Hipoglucemiantes/química , Hipoglucemiantes/farmacología , Polipéptido Amiloide de los Islotes Pancreáticos/metabolismo , Polipéptido Amiloide de los Islotes Pancreáticos/farmacología , Cinética , Células MCF-7 , Masculino , Ratones , Polietilenglicoles/farmacología , Solventes/química

RESUMEN

Several hormones are regulated by circadian rhythms to adjust the metabolism to the light/dark cycles and feeding/activity patterns throughout the day. Circadian rhythms are mainly governed by the central clock located in the suprachiasmatic nucleus but also by clocks present in peripheral organs, like the endocrine pancreas. Plasma glucose levels and the main pancreatic hormones insulin and glucagon also exhibit daily variations. Alterations in circadian rhythms are associated with metabolic disturbances and pathologies such as obesity and diabetes. The molecular components of central and peripheral clocks and their regulatory mechanisms are well established. Among the different clock genes, Rev-erbα is considered one of the key links between circadian rhythms and metabolism. Rev-erbα is a critical part of a negative feedback loop in the core circadian clock and modulates the clock oscillatory properties. In addition, Rev-erbα plays an important role in the regulation of lipid and glucose metabolism, thermogenesis, adipocyte and muscle differentiation as well as mitochondrial function. In the endocrine pancreas, Rev-erbα regulates insulin and glucagon secretion and pancreatic ß-cell proliferation. In the present review, we discuss all these subjects and, particularly, the role of the clock gene Rev-erbα in the endocrine pancreas.

Asunto(s)

Relojes Circadianos/genética , Ritmo Circadiano/fisiología , Islotes Pancreáticos/metabolismo , Miembro 1 del Grupo D de la Subfamilia 1 de Receptores Nucleares/fisiología , Adipocitos/metabolismo , Glucemia/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Retroalimentación Fisiológica , Glucagón/metabolismo , Células Secretoras de Glucagón/metabolismo , Humanos , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/metabolismo , Metabolismo de los Lípidos/genética , Mitocondrias/fisiología , Músculo Esquelético/metabolismo , Termogénesis/genética

RESUMEN

Taurine (Tau) regulates ß-cell function and glucose homeostasis under normal and diabetic conditions. Here, we assessed the effects of Tau supplementation upon glucose homeostasis and the morphophysiology of endocrine pancreas, in leptin-deficient obese (ob) mice. From weaning until 90-day-old, C57Bl/6 and ob mice received, or not, 5% Tau in drinking water (C, CT, ob and obT). Obese mice were hyperglycemic, glucose intolerant, insulin resistant, and exhibited higher hepatic glucose output. Tau supplementation did not prevent obesity, but ameliorated glucose homeostasis in obT. Islets from ob mice presented a higher glucose-induced intracellular Ca(2+) influx, NAD(P)H production and insulin release. Furthermore, α-cells from ob islets displayed a higher oscillatory Ca(2+) profile at low glucose concentrations, in association with glucagon hypersecretion. In Tau-supplemented ob mice, insulin and glucagon secretion was attenuated, while Ca(2+) influx tended to be normalized in ß-cells and Ca(2+) oscillations were increased in α-cells. Tau normalized the inhibitory action of somatostatin (SST) upon insulin release in the obT group. In these islets, expression of the glucagon, GLUT-2 and TRPM5 genes was also restored. Tau also enhanced MafA, Ngn3 and NeuroD mRNA levels in obT islets. Morphometric analysis demonstrated that the hypertrophy of ob islets tends to be normalized by Tau with reductions in islet and ß-cell masses, but enhanced δ-cell mass in obT. Our results indicate that Tau improves glucose homeostasis, regulating ß-, α-, and δ-cell morphophysiology in ob mice, indicating that Tau may be a potential therapeutic tool for the preservation of endocrine pancreatic function in obesity and diabetes.

Asunto(s)

Suplementos Dietéticos , Glucagón/metabolismo , Insulina/metabolismo , Islotes Pancreáticos/efectos de los fármacos , Taurina/administración & dosificación , Taurina/metabolismo , Animales , Glucemia/metabolismo , Calcio/metabolismo , Homeostasis/efectos de los fármacos , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Islotes Pancreáticos/citología , Islotes Pancreáticos/metabolismo , Leptina/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Obesidad/metabolismo , Taurina/sangre

RESUMEN

In this study, we examined the effect glucagon-induced hyperglycemia on tumor growth as well as the role of the hypoxia-inducible factor 1 (HIF-1)-vascular endothelial growth factor (VEGF) pathway in this condition. A high concentration of glucose (HG) was utilized to treat HeLa cells under hypoxic or normoxic conditions, and transcriptional levels of HIF-1, VEGF, and basic fibroblast growth factor (bFGF) were evaluated. Moreover, the ability of an HIF-1 inhibitor to block the effect induced by HG was examined. By contrast, hyperglycemia was induced in nude mice by glucagon released from an osmotic pump, and microvessel density was determined with CD31 staining. Thus, the relationship among hyperglycemia, microvessel density, tumor growth, and the HIF-1 inhibitor were analyzed. We found that HG increased transcription of the VEGF gene, which is downstream of HIF-1. Moreover, HG impaired the function of HIF-1 inhibitors [HIF-1 small interfering RNA (siRNA) and berberine] to affect the VEGF transcription level in tumor cells. By contrast, hyperglycemia increased tumor microvessel density and promoted tumor growth, which was inhibited by the HIF-1 inhibitor. However, hyperglycemia attenuated the effect of the HIF-1 inhibitor. Glucagon-induced hyperglycemia influenced tumor microenvironments through the HIF-1-VEGF-dependent pathway and promoted tumor growth and resistance to HIF-1 inhibition treatments.

Asunto(s)

Glucagón/metabolismo , Factor 1 Inducible por Hipoxia/metabolismo , Neoplasias/metabolismo , Neoplasias/patología , Neovascularización Patológica/metabolismo , Transducción de Señal , Factor A de Crecimiento Endotelial Vascular/metabolismo , Animales , Línea Celular Tumoral , Modelos Animales de Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica , Glucagón/farmacología , Xenoinjertos , Humanos , Hiperglucemia/inducido químicamente , Factor 1 Inducible por Hipoxia/genética , Ratones , Ratones Desnudos , Ratones Obesos , Neoplasias/genética , Neovascularización Patológica/genética , Carga Tumoral/efectos de los fármacos , Microambiente Tumoral/efectos de los fármacos , Factor A de Crecimiento Endotelial Vascular/genética