RESUMEN
The prevalence of type 2 diabetes is rapidly increasing, with severe socioeconomic impacts. Excess lipid deposition in peripheral tissues impairs insulin sensitivity and glucose uptake, and has been proposed to contribute to the pathology of type 2 diabetes. However, few treatment options exist that directly target ectopic lipid accumulation. Recently it was found that vascular endothelial growth factor B (VEGF-B) controls endothelial uptake and transport of fatty acids in heart and skeletal muscle. Here we show that decreased VEGF-B signalling in rodent models of type 2 diabetes restores insulin sensitivity and improves glucose tolerance. Genetic deletion of Vegfb in diabetic db/db mice prevented ectopic lipid deposition, increased muscle glucose uptake and maintained normoglycaemia. Pharmacological inhibition of VEGF-B signalling by antibody administration to db/db mice enhanced glucose tolerance, preserved pancreatic islet architecture, improved ß-cell function and ameliorated dyslipidaemia, key elements of type 2 diabetes and the metabolic syndrome. The potential use of VEGF-B neutralization in type 2 diabetes was further elucidated in rats fed a high-fat diet, in which it normalized insulin sensitivity and increased glucose uptake in skeletal muscle and heart. Our results demonstrate that the vascular endothelium can function as an efficient barrier to excess muscle lipid uptake even under conditions of severe obesity and type 2 diabetes, and that this barrier can be maintained by inhibition of VEGF-B signalling. We propose VEGF-B antagonism as a novel pharmacological approach for type 2 diabetes, targeting the lipid-transport properties of the endothelium to improve muscle insulin sensitivity and glucose disposal.
Asunto(s)
Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Resistencia a la Insulina , Terapia Molecular Dirigida , Factor B de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Factor B de Crecimiento Endotelial Vascular/metabolismo , Animales , Dieta Alta en Grasa , Modelos Animales de Enfermedad , Dislipidemias/tratamiento farmacológico , Dislipidemias/metabolismo , Endotelio Vascular/metabolismo , Femenino , Glucosa/metabolismo , Prueba de Tolerancia a la Glucosa , Islotes Pancreáticos/anatomía & histología , Islotes Pancreáticos/citología , Islotes Pancreáticos/patología , Metabolismo de los Lípidos , Masculino , Síndrome Metabólico/tratamiento farmacológico , Síndrome Metabólico/metabolismo , Ratones , Ratones Endogámicos C57BL , Músculos/metabolismo , Obesidad/metabolismo , Obesidad/patología , Ratas , Ratas Wistar , Transducción de Señal/efectos de los fármacos , Transducción de Señal/inmunología , Factor B de Crecimiento Endotelial Vascular/deficiencia , Factor B de Crecimiento Endotelial Vascular/genéticaRESUMEN
Stroke is the leading cause of adult disability in Westernized societies with increased incidence along ageing and it represents a major health and economical threat. Inactive lifestyle, smoking, hypertension, atherosclerosis, obesity and diabetes all dramatically increase the risk of stroke. While preventive strategies based on lifestyle changes and risk factor management can delay or decrease the likelihood of having a stroke, post stroke pharmacological strategies aimed at minimizing stroke-induced brain damage are highly needed. Unfortunately, several candidate drugs that have shown significant preclinical neuroprotective efficacy, have failed in clinical trials and no treatment for stroke based on neuroprotection is available today. Glucagon-like peptide 1 (GLP-1) is a peptide originating in the enteroendocrine L-cells of the intestine and secreted upon nutrient ingestion. The activation of the GLP-1R by GLP-1 enhances glucose-dependent insulin secretion, suppresses glucagon secretion and exerts multifarious extrapancreatic effects. Stable GLP-1 analogues and inhibitors of the proteolytic enzyme dipeptidyl peptidase 4 (DPP-4) (which counteract endogenous GLP-1 degradation) have been developed clinically for the treatment of type 2 diabetes. Besides their antidiabetic properties, experimental evidence has shown neurotrophic and neuroprotective effects of GLP-1R agonists and DPP-4 inhibitors in animal models of neurological disorders. Herein, we review recent experimental data on the neuroprotective effects mediated by GLP-1R activation in stroke. Due to the good safety profile of the drugs targeting the GLP-1R, we also discuss the high potential of GLP-1R stimulation in view of developing a safe clinical treatment against stroke based on neuroprotection in both diabetic and non-diabetic patients.
Asunto(s)
Receptores de Glucagón/metabolismo , Accidente Cerebrovascular/tratamiento farmacológico , Animales , Inhibidores de la Dipeptidil-Peptidasa IV/uso terapéutico , Péptido 1 Similar al Glucagón , Receptor del Péptido 1 Similar al Glucagón , Humanos , Receptores de Glucagón/agonistas , Accidente Cerebrovascular/metabolismoRESUMEN
Saturated fatty acids like palmitate induce endoplasmic reticulum (ER) stress in pancreatic beta-cells, an event linked to apoptotic loss of ß-cells in type 2 diabetes. Sustained activation of the ER stress response leads to expression of growth arrest and DNA damage-inducible protein 34 (GADD34), a regulatory subunit of protein phosphatase 1. In the present study, we have used small interfering RNA in order to knockdown GADD34 expression in insulin-producing MIN6 cells prior to induction of ER stress by palmitate and evaluated its consequences on RNA-activated protein kinase-like ER-localized eIF2alpha kinase (PERK) signalling and apoptosis. Salubrinal, a specific inhibitor of eukaryotic initiation factor 2α (eIF2α) dephosphorylation, was used as a comparison. Salubrinal treatment augmented palmitate-induced ER stress and increased GADD34 levels. Both GADD34 knockdown and salubrinal treatment potentiated the cytotoxic effects of palmitate as evidenced by increased DNA fragmentation and activation of caspase 3, with the fundamental difference that the former did not involve enhanced levels of GADD34. The data from this study suggest that sustained activation of PERK signalling and eIF2α phosphorylation sensitizes insulin-producing MIN6 cells to lipoapoptosis independently of GADD34 expression levels.
Asunto(s)
Apoptosis/efectos de los fármacos , Palmitatos/toxicidad , Proteína Fosfatasa 1/metabolismo , Factor de Transcripción Activador 4/genética , Factor de Transcripción Activador 4/metabolismo , Animales , Caspasa 3/metabolismo , Línea Celular Tumoral , Fragmentación del ADN/efectos de los fármacos , Estrés del Retículo Endoplásmico/efectos de los fármacos , Factor 2 Eucariótico de Iniciación/metabolismo , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Insulinoma/metabolismo , Insulinoma/patología , Ratones , Fosforilación/efectos de los fármacos , Proteína Fosfatasa 1/antagonistas & inhibidores , Proteína Fosfatasa 1/genética , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Transducción de Señal/efectos de los fármacos , Factor de Transcripción CHOP/genética , Factor de Transcripción CHOP/metabolismo , eIF-2 Quinasa/metabolismoRESUMEN
Glucagon-like peptide-1 (GLP-1), secreted from gut L cells upon nutrient intake, forms the basis for novel drugs against type 2 diabetes (T2D). Secretion of GLP-1 has been suggested to be impaired in T2D and in conditions associated with hyperlipidemia and insulin resistance. Further, recent studies support lipotoxicity of GLP-1-producing cells in vitro. However, little is known about the regulation of L-cell viability/function, the effects of insulin signaling, or the potential effects of stable GLP-1 analogs and dipeptidyl peptidase-4 (DPP-4) inhibitors. We determined effects of insulin as well as possible autocrine action of GLP-1 on viability/apoptosis of GLP-1-secreting cells in the presence/absence of palmitate, while also assessing direct effects on function. The studies were performed using the GLP-1-secreting cell line GLUTag, and palmitate was used to simulate hyperlipidemia. Our results show that palmitate induced production of reactive oxygen species and caspase-3 activity and reduced cell viability are significantly attenuated by preincubation with insulin/exendin-4. The indicated lipoprotective effect of insulin/exendin-4 was not detectable in the presence of the GLP-1 receptor (GLP-1R) antagonist exendin (9-39) and attenuated in response to pharmacological inhibition of exchange protein activated by cAMP (Epac) signaling, while protein kinase A inhibition had no significant effect. Insulin/exendin-4 also significantly stimulate acute and long-term GLP-1 secretion in the presence of glucose, suggesting novel beneficial effects of insulin signaling and GLP-1R activation on glycemia through enhanced mass of GLP-1-producing cells and enhanced GLP-1 secretion. In addition, the effects of insulin indicate that not only is GLP-1 important for insulin secretion but altered insulin signaling may contribute to an altered GLP-1 secretion.
Asunto(s)
Células Enteroendocrinas/metabolismo , Regulación de la Expresión Génica/fisiología , Péptido 1 Similar al Glucagón/metabolismo , Insulina/farmacología , Péptidos/farmacología , Ponzoñas/farmacología , Animales , Línea Celular , Proliferación Celular , Supervivencia Celular , Células Enteroendocrinas/citología , Células Enteroendocrinas/efectos de los fármacos , Exenatida , Péptido 1 Similar al Glucagón/genética , Receptor del Péptido 1 Similar al Glucagón , Insulina/administración & dosificación , Ratones , Péptidos/administración & dosificación , Especies Reactivas de Oxígeno , Receptores de Glucagón/genética , Receptores de Glucagón/metabolismo , Factores de Tiempo , Ponzoñas/administración & dosificaciónRESUMEN
Type 2 diabetes impairs adult neurogenesis which could play a role in the CNS complications of this serious disease. The goal of this study was to determine the potential role of galanin in protecting adult neural stem cells (NSCs) from glucolipotoxicity and to analyze whether apoptosis and the unfolded protein response were involved in the galanin-mediated effect. We also studied the regulation of galanin and its receptor subtypes under diabetes in NSCs in vitro and in the subventricular zone (SVZ) in vivo. The viability of mouse SVZ-derived NSCs and the involvement of apoptosis (Bcl-2, cleaved caspase-3) and unfolded protein response [C/EBP homologous protein (CHOP) Glucose-regulated protein 78/immunoglobulin heavy-chain binding protein (GRP78/BiP), spliced X-box binding protein 1 (XBP1), c-Jun N-terminal kinases (JNK) phosphorylation] were assessed in the presence of glucolipotoxic conditions after 24 h. The effect of diabetes on the regulation of galanin and its receptor subtypes was assessed on NSCs in vitro and in SVZ tissues isolated from normal and type 2 diabetes ob/ob mice. We show increased NSC viability following galanin receptor (GalR)3 activation. This protective effect correlated with decreased apoptosis and CHOP levels. We also report how galanin and its receptors are regulated by diabetes in vitro and in vivo. This study shows GalR3-mediated neuroprotection, supporting a potential future therapeutic development, based on GalR3 activation, for the treatment of brain disorders.
Asunto(s)
Supervivencia Celular/fisiología , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patología , Células-Madre Neurales/patología , Células-Madre Neurales/fisiología , Receptor de Galanina Tipo 3/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Apoptosis/efectos de los fármacos , Western Blotting , Supervivencia Celular/efectos de los fármacos , Medios de Cultivo , Proteínas de Unión al ADN/metabolismo , Chaperón BiP del Retículo Endoplásmico , Ácidos Grasos/farmacología , Galanina/metabolismo , Glucosa/farmacología , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , ARN Mensajero/biosíntesis , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptor de Galanina Tipo 3/efectos de los fármacos , Factores de Transcripción del Factor Regulador X , Timidina/metabolismo , Factor de Transcripción CHOP/metabolismo , Factores de Transcripción/metabolismo , Respuesta de Proteína Desplegada/efectos de los fármacos , Respuesta de Proteína Desplegada/fisiología , Proteína 1 de Unión a la X-BoxRESUMEN
Diabetic patients are often treated with an ACEi (angiotensin-converting enzyme inhibitor) or angiotensin receptor antagonist against hypertension or albuminuria. These drugs also have a positive impact on glucose tolerance, but the mechanism for this remains elusive. Hypothesizing a positive non-additive effect, we studied whether the angiotensin receptor antagonist telmisartan or the ACEi ramipril acutely influence insulin secretion and glycaemia in vivo in healthy and Type 2 diabetic rats through effects on islet blood perfusion. Telmisartan and ramipril were injected intravenously into anaesthetized non-diabetic Wistar rats or Type 2 diabetic GK (Goto-Kakizaki) rats. In non-diabetic Wistar rats, neither whole PBF (pancreatic blood flow) nor IBF (islet blood flow) were significantly influenced by telmisartan and ramipril, alone or in combination. Renal blood flow was enhanced significantly by telmisartan and ramipril when used in combination, whereas ABF (adrenal blood flow) was not affected by any of the drugs. Telmisartan and ramipril both significantly increased serum insulin levels, but did not influence glycaemia. In Type 2 diabetic GK rats, both whole PBF and IBF were significantly decreased by telmisartan and ramipril, but only when used in combination. Renal blood flow was enhanced significantly by telmisartan and ramipril alone, but not when used in combination, whereas ABF was not affected by any of the drugs. Telmisartan and ramipril both significantly decreased serum insulin levels, and non-additively elevated blood glucose levels. In conclusion, the present study suggests that a local pancreatic RAS (renin-angiotensin system), sensitive to acute administration of telmisartan and ramipril, controls pancreatic IBF and insulin secretion and thereby has an impact on glucose tolerance. Our findings indicate unexpected significant differences in the effects of these agents on islet microcirculation, in vivo insulin secretion and glycaemia between healthy and Type 2 diabetic rats.
Asunto(s)
Antagonistas de Receptores de Angiotensina/farmacología , Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Bencimidazoles/farmacología , Benzoatos/farmacología , Glucemia/efectos de los fármacos , Diabetes Mellitus Tipo 2/fisiopatología , Islotes Pancreáticos/irrigación sanguínea , Microcirculación/efectos de los fármacos , Ramipril/farmacología , Animales , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Insulina/sangre , Masculino , Páncreas/irrigación sanguínea , Ratas , Ratas Wistar , Flujo Sanguíneo Regional/efectos de los fármacos , Sistema Renina-Angiotensina/efectos de los fármacos , TelmisartánRESUMEN
In addition to peripheral neuropathy of various manifestations, diabetes is also associated with central neuropathy. This can manifest as premature cognitive decline, although the role of hyperglycemia in this process remains ambiguous. Notwithstanding that the link between diabetes and cognitive decline was discovered 100 years ago, and has important clinical implications, this co-morbidity remains relatively unknown. Recent years have seen research that has clarified cerebral insulin resistance and defective insulin signaling as two putative pathogenic factors behind this cognitive impairment. Recently published studies have shown that physical activity may reverse insulin resistance in the brain as well as improve cognitive impairment and pathological appetite regulation. Pharmacological intervention with e.g. nasal insulin and GLP-1 receptor agonists have also shown promising results, but must be further tested in clinical studies.
Asunto(s)
Disfunción Cognitiva , Diabetes Mellitus , Hiperglucemia , Resistencia a la Insulina , Humanos , Diabetes Mellitus/epidemiología , Insulina/uso terapéutico , Disfunción Cognitiva/etiologíaRESUMEN
PP5 is a ubiquitously expressed Ser/Thr protein phosphatase. High levels of PP5 have been observed in human cancers, and constitutive PP5 overexpression aids tumor progression in mouse models of tumor development. However, PP5 is highly conserved among species, and the roles of PP5 in normal tissues are not clear. Here, to help evaluate the biological actions of PP5, a Cre/loxP-conditional mouse line was generated. In marked contrast to the early embryonic lethality associated with the genetic disruption of other PPP family phosphatases (e.g. PP2A and PP4), intercrosses with mouse lines that ubiquitously express Cre recombinase starting early in development (e.g. MeuCre40 and ACTB-Cre) produced viable and fertile PP5-deficient mice. Phenotypic differences caused by the total disruption of PP5 were minor, suggesting that small molecule inhibitors of PP5 will not have widespread systemic toxicity. Examination of roles for PP5 in fibroblasts generated from PP5-deficient embryos (PP5(-/-) mouse embryonic fibroblasts) confirmed some known roles and identified new actions for PP5. PP5(-/-) mouse embryonic fibroblasts demonstrated increased sensitivity to UV light, hydroxyurea, and camptothecin, which are known activators of ATR (ataxia-telangiectasia and Rad3-related) kinase. Further study revealed a previously unrecognized role for PP5 downstream of ATR activation in a UV light-induced response. The genetic disruption of PP5 is associated with enhanced and prolonged phosphorylation of a single serine (Ser-345) on Chk1, increased phosphorylation of the p53 tumor suppressor protein (p53) at serine 18, and increased p53 protein levels. A comparable role for PP5 in the regulation of Chk1 phosphorylation was also observed in human cells.
Asunto(s)
Proteínas Nucleares/deficiencia , Proteínas Nucleares/genética , Fosfoproteínas Fosfatasas/deficiencia , Fosfoproteínas Fosfatasas/genética , Proteínas Quinasas/metabolismo , Rayos Ultravioleta , Actinas/genética , Alelos , Animales , Blastocisto/metabolismo , Cruzamiento , Línea Celular , Quinasa 1 Reguladora del Ciclo Celular (Checkpoint 1) , Femenino , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Fibroblastos/efectos de la radiación , Células HeLa , Humanos , Hidroxiurea/farmacología , Integrasas/genética , Masculino , Ratones , Proteínas Nucleares/metabolismo , Fenotipo , Fosfoproteínas Fosfatasas/metabolismo , Fosforilación/efectos de los fármacos , Fosforilación/genética , Fosforilación/efectos de la radiación , Regiones Promotoras Genéticas/genética , Proteínas Quinasas/química , Receptores de Neuropéptido Y/metabolismo , Serina/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Fosfatasas cdc25/metabolismoRESUMEN
Pancreatic ß-cells have a well-developed endoplasmic reticulum (ER) and express large amounts of chaperones and protein disulfide isomerases (PDI) to meet the high demand for synthesis of proteins. We have observed an unexpected decrease in chaperone protein level in the ß-cell model INS-1E after exposure to the ER stress inducing agent thapsigargin. As these cells are a commonly used model for primary ß-cells and has been shown to be vulnerable to ER stress, we hypothesize these cells are incapable of mounting a chaperone defense upon activation of ER stress. To investigate the chaperone expression during an ER stress response, induced by thapsigargin in INS-1E cells, we used quantitative mass spectrometry based proteomics. The results displayed a decrease of GRP78/BiP, PDIA3 and PDIA6. Decrease of GRP78/BiP was verified by Western blot and occurred in parallel with enhanced levels of p-eIF2α and CHOP. In contrast to INS-1E cells, GRP78/BiP was not decreased in MIN6 cell or rat and mouse islets after thapsigargin exposure. Investigation of the decreased protein levels of GRP78/BiP indicates that this is not a consequence of reduced mRNA expression. Rather the reduction results from the combined effect of reduced protein synthesis and enhanced proteosomal degradation and possibly also degradation via autophagy. Induction of ER stress with thapsigargin leads to lower protein levels of GRP78/BiP, PDIA3 and PDIA6 in INS-1E cells which may contribute to the susceptibility of ER stress in this ß-cell model.
Asunto(s)
Proteínas de Choque Térmico/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Tapsigargina/farmacología , Animales , Autofagia/efectos de los fármacos , Línea Celular , Regulación hacia Abajo/efectos de los fármacos , Retículo Endoplásmico/efectos de los fármacos , Retículo Endoplásmico/metabolismo , Chaperón BiP del Retículo Endoplásmico , Inhibidores Enzimáticos/farmacología , Proteínas de Choque Térmico/genética , Técnicas In Vitro , Masculino , Ratones , Ratones Endogámicos C57BL , Proteómica , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Estrés Fisiológico/efectos de los fármacos , Factor de Transcripción CHOP/genéticaRESUMEN
BACKGROUND: Evidence is emerging that elevated serum free fatty acids (hyperlipidemia) contribute to the pathogenesis of type-2-diabetes, and lipotoxicity is observed in many cell types. We recently published data indicating lipotoxic effects of simulated hyperlipidemia also in GLP-1-secreting cells, where the antidiabetic drug metformin conferred protection from lipoapoptosis. The aim of the present study was to identify mechanisms involved in mediating lipotoxicity and metformin lipoprotection in GLP-1 secreting cells. These signaling events triggered by simulated hyperlipidemia may underlie reduced GLP-1 secretion in diabetic subjects, and metformin lipoprotection by metformin could explain elevated plasma GLP-1 levels in diabetic patients on chronic metformin therapy. The present study may thus identify potential molecular targets for increasing endogenous GLP-1 secretion through enhanced viability of GLP-1 secreting cells in diabetic hyperlipidemia and obesity. METHODS: We have studied molecular mechanisms mediating lipotoxicity and metformin-induced lipoprotection in GLP-1-secreting L-cells in vitro, using the murine GLUTag cell line as a model. Diabetic hyperlipidemia was simulated in this cell system by addition of the fatty acid palmitate. Caspase-3 activity was used as a measure of GLUTag cell apoptosis. ROS production was determined using a fluorescent probe, and the activation of intracellular signaling pathways was assessed by Western blotting. RESULTS: Palmitate increased ROS production in GLP-1 secreting cells, and the lipotoxic effects of palmitate were abolished in the presence of the antioxidant Trolox. Further, palmitate phosphorylated p38 and inhibition of p38 using the p38 inhibitor SB203580 significantly reduced palmitate-induced caspase-3 activity. Pre-incubation of palmitate with metformin further increased palmitate induced ROS production, while significantly reducing the expression of p38. CONCLUSION: This study demonstrates that palmitate induces ROS production and that the palmitate induced lipotoxicity is the result of increased ROS production, where the ROS sensitive MKK3/6-p38 pathway mediates lipoapoptosis of GLP-1-secreting cells. Further, in the presence of simulated hyperlipidemia, metformin increases ROS production. However, metformin significantly decreases the expression of p38, indicating that metformin mediated lipoprotection involves reduced activity of the p38 signaling pathway.
Asunto(s)
Apoptosis/fisiología , Citoprotección , Ácidos Grasos no Esterificados/toxicidad , Péptido 1 Similar al Glucagón/metabolismo , Hiperlipidemias/metabolismo , Hipoglucemiantes/farmacología , Metformina/farmacología , Animales , Antioxidantes/farmacología , Apoptosis/efectos de los fármacos , Caspasa 3/metabolismo , Línea Celular , Cromanos/farmacología , MAP Quinasa Quinasa 3/metabolismo , MAP Quinasa Quinasa 4/metabolismo , MAP Quinasa Quinasa 6/metabolismo , Ratones , Ratones Transgénicos , Palmitatos/toxicidad , Especies Reactivas de Oxígeno , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Exendin-4, a stable GLP-1 receptor agonist, has been shown to stimulate insulin secretion. It has also been shown to exert beneficial effects on endothelial function that are independent of its glycemic effects. The molecular mechanisms underlying the protective actions of exendin-4 against diabetic glucolipotoxicity in endothelial cells largely remain elusive. We have investigated the long-term in vitro effect of palmitate or high glucose (simulating the diabetic milieu) and the role of exendin-4 on gene expression in human coronary artery endothelial cells. Gene expression profiling in combination with Western blotting revealed that exendin-4 regulates expression of a number of genes involved in angiogenesis, inflammation and thrombogenesis under glucolipotoxic conditions. Our results indicate that exendin-4 may improve endothelial cell function in diabetes through regulating expression of the genes, whose expression was disrupted by glucolipotoxicity. As endothelial dysfunction appears to be an early indicator of vascular damage, and predicts both progression of atherosclerosis and incidence of cardiovascular events, exendin-4 and possibly other incretin-based strategies may confer additional cardiovascular benefit beyond improved glycemic control.
Asunto(s)
Vasos Coronarios/efectos de los fármacos , Endotelio Vascular/efectos de los fármacos , Expresión Génica/efectos de los fármacos , Glucosa/toxicidad , Palmitatos/toxicidad , Péptidos/farmacología , Receptores de Glucagón/agonistas , Ponzoñas/farmacología , Células Cultivadas , Vasos Coronarios/metabolismo , Endotelio Vascular/metabolismo , Exenatida , Perfilación de la Expresión Génica , Receptor del Péptido 1 Similar al Glucagón , HumanosRESUMEN
BACKGROUND: Type 2 diabetes (T2D) is a strong risk factor for developing neurodegenerative pathologies. T2D patients have a deficiency in the intestinal incretin hormone GLP-1, which has been shown to exert neuroprotective and anti-inflammatory properties in the brain. METHODS: Here we investigate potential sources of GLP-1 in the CNS and the effect of diabetic conditions on the proglucagon mRNA expression in the CNS. The obese mouse model ob/ob, characterized by its high levels of free fatty acids, and the microglia cell line BV-2 were used as models. mRNA expression and protein secretion were analyzed by qPCR, immunofluorescence and ELISA. RESULTS: We show evidence for microglia as a central source of GLP-1 secretion. Furthermore, we observed that expression and secretion are stimulated by cAMP and dependent on microglial activation state. We also show that insulin-resistant conditions reduce the central mRNA expression of proglucagon. CONCLUSION: The findings that microglial mRNA expression of proglucagon and GLP-1 protein expression are affected by high levels of free fatty acids and that both mRNA expression levels of proglucagon and secretion levels of GLP-1 are affected by inflammatory stimuli could be of pathogenic importance for the premature neurodegeneration and cognitive decline commonly seen in T2D patients, and they may also be harnessed to advantage in therapeutic efforts to prevent or treat such disorders.
Asunto(s)
Sistema Nervioso Central/metabolismo , Sistema Nervioso Central/patología , Péptido 1 Similar al Glucagón/metabolismo , Microglía/metabolismo , Obesidad/patología , Animales , Arginasa/metabolismo , Antígeno CD11b/genética , Antígeno CD11b/metabolismo , Línea Celular Transformada , Quitinasas/metabolismo , AMP Cíclico/farmacología , Modelos Animales de Enfermedad , Regulación de la Expresión Génica/genética , Péptido 1 Similar al Glucagón/genética , Resistencia a la Insulina/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Palmitatos/farmacología , Proteínas de Plantas , Polisacáridos/farmacología , Proglucagón/genética , Proglucagón/metabolismo , ARN Mensajero/metabolismo , Estadísticas no Paramétricas , Transfección , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Diabetes and obesity are characterized by hyperlipidemia and represent risk factors for premature neurological disorders. Diabetic/obese animals have impaired adult neurogenesis. We hypothesize that lipotoxicity leading to neurogenesis impairment plays a role in the development of neurological complications. If so, normalizing neurogenesis in diabetes/obesity could be therapeutically useful in counteracting neurological dysfunction. The goal of this study was to determine the potential of pituitary adenylate cyclase-activating polypeptide (PACAP) to protect adult neural stem cells (NSCs) from lipotoxicity and to study the expression of PACAP receptors in NSCs under lipotoxic conditions in vitro and in the subventricular zone in vivo. The viability of NSCs isolated from the adult mouse brain subventricular zone was assessed in the presence of a high-fat milieu, as mimicked by palmitate, which characterizes diabetic lipotoxicity. Regulation studies of PACAP receptors were performed by quantitative PCR on NSCs in vitro or on subventricular tissues isolated from obese ob/ob mice and their lean littermates. We show that palmitate impairs NSC viability by promoting lipoapoptosis. We also show that PACAP counteracts lipotoxicity via PAC-1 receptor activation. Studies on PACAP receptor expression revealed that PAC-1 and VPAC-2 are expressed by NSC in vitro and are upregulated by palmitate treatment and that PAC-1, VPAC-1, and VPAC-2 are expressed in the subventricular zone/striatum in vivo and are upregulated in ob/ob mice. The present study reveals a previously uncharacterized role of PACAP to protect NSC from lipotoxicity and suggests a potential therapeutic role for PACAP receptor agonists in the treatment of neurological complications in obesity and diabetes.
Asunto(s)
Células Madre Adultas/efectos de los fármacos , Neurotransmisores/farmacología , Palmitatos/efectos adversos , Polipéptido Hipofisario Activador de la Adenilato-Ciclasa/farmacología , Adenosina Trifosfato/metabolismo , Análisis de Varianza , Animales , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/metabolismo , Relación Dosis-Respuesta a Droga , Ácidos Grasos/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Ventrículos Laterales/citología , Ratones , Ratones Endogámicos C57BL , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2 , ARN Mensajero/metabolismo , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/genética , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/metabolismo , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/genética , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/metabolismo , Receptores de Tipo II del Péptido Intestinal Vasoactivo/genética , Receptores de Tipo II del Péptido Intestinal Vasoactivo/metabolismo , Receptores de Tipo I del Polipéptido Intestinal Vasoactivo/genética , Receptores de Tipo I del Polipéptido Intestinal Vasoactivo/metabolismo , Timidina/metabolismo , Tritio/metabolismoRESUMEN
BACKGROUND: Patients with type 1 diabetes have a substantial risk of developing cardiovascular complications early in life. We aimed to explore the role of insulin sensitivity (Si) as an early factor of atherosclerosis in young type 1 diabetes vs. non-diabetic subjects. METHODS: Forty adolescent and young adult individuals (20 type 1 diabetics and 20 non-diabetics), age 14-20 years, without characteristics of the metabolic syndrome, participated in this cross-sectional study. After an overnight fast, Si was measured by hyperinsulinemic euglycemic clamp (40 mU/m2) and calculated by glucose infusion rate (GIR). Carotid intima-media thickness (cIMT) was measured in the common carotid artery with high-resolution ultrasonography. Risk factors of atherosclerosis (Body mass index [BMI], waist circumference, systolic blood pressure [sBP], triglycerides, low HDL-cholesterol and HbA1c) were also investigated. RESULTS: cIMT was increased (0.52 ± 0.1 vs. 0.47 ± 0.1 mm, P < 0.01), whereas GIR was decreased (5.0 ± 2.1 vs. 7.1 ± 2.2 mg/kg/min, P < 0.01) in type 1 diabetics vs. non-diabetics. The differences in cIMT were negatively associated with Si (r = -0.4, P < 0.01) and positively associated with waist circumference (r = 0.34, P = 0.03), with no such associations between BMI (r = 0.15, P = 0.32), sBP (r = 0.09, P = 0.58), triglycerides (r = 0.07, P = 0.66), HDL-cholesterol (r = 0.10, P = 0.55) and HbA1c (r = 0.24, P = 0.13). In a multivariate regression model, between cIMT (dependent) and group (explanatory), only adjustment for Si affected the significance (ß = 0.08, P = 0.11) vs. (ß = 0.07, P < 0.01) for the whole model. No interaction between cIMT, groups and Si was observed. CONCLUSIONS: cIMT is increased and associated with insulin resistance in adolescent, non-obese type 1 diabetic subjects. Although, no conclusions toward a causal relationship can be drawn from current findings, insulin resistance emerges as an important factor reflecting early signs of atherosclerosis in this small cohort.
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Enfermedades de las Arterias Carótidas/etiología , Arteria Carótida Común/patología , Diabetes Mellitus Tipo 1/complicaciones , Resistencia a la Insulina , Adolescente , Factores de Edad , Biomarcadores/sangre , Glucemia/análisis , Presión Sanguínea , Índice de Masa Corporal , Enfermedades de las Arterias Carótidas/diagnóstico , Enfermedades de las Arterias Carótidas/patología , Arteria Carótida Común/diagnóstico por imagen , Grosor Intima-Media Carotídeo , Estudios Transversales , Diabetes Mellitus Tipo 1/sangre , Diabetes Mellitus Tipo 1/diagnóstico , Diagnóstico Precoz , Femenino , Técnica de Clampeo de la Glucosa , Hemoglobina Glucada/análisis , Humanos , Lípidos/sangre , Masculino , Análisis Multivariante , Valor Predictivo de las Pruebas , Medición de Riesgo , Factores de Riesgo , Circunferencia de la Cintura , Adulto JovenRESUMEN
BACKGROUND: The leading cause of death for patients suffering from diabetes is macrovascular disease. Endothelial dysfunction is often observed in type 2 diabetic patients and it is considered to be an important early event in the pathogenesis of atherogenesis and cardiovascular disease. Many drugs are clinically applied to treat diabetic patients. However, little is known whether these agents directly interfere with endothelial cell proliferation and apoptosis. This study therefore aimed to investigate how anti-diabetic and cardioprotective agents affect human coronary artery endothelial cells (HCAECs). METHODS: The effect of anti-diabetic and cardioprotective agents on HCAEC viability, proliferation and apoptosis was studied. Viability was assessed using Trypan blue exclusion; proliferation in 5 mM and 11 mM of glucose was analyzed using [3H]thymidine incorporation. Lipoapoptosis of the cells was investigated by determining caspase-3 activity and the subsequent DNA fragmentation after incubation with the free fatty acid palmitate, mimicking diabetic lipotoxicity. RESULTS: Our data show that insulin, metformin, BLX-1002, and rosuvastatin improved HCAEC viability and they could also significantly increase cell proliferation in low glucose. The proliferative effect of insulin and BLX-1002 was also evident at 11 mM of glucose. In addition, insulin, metformin, BLX-1002, pioglitazone, and candesartan significantly decreased the caspase-3 activity and the subsequent DNA fragmentation evoked by palmitate, suggesting a protective effect of the drugs against lipoapoptosis. CONCLUSION: Our results suggest that the anti-diabetic and cardioprotective agents mentioned above have direct and beneficial effects on endothelial cell viability, regeneration and apoptosis. This may add yet another valuable property to their therapeutic effect, increasing their clinical utility in type 2 diabetic patients in whom endothelial dysfunction is a prominent feature that adversely affect their survival.
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Apoptosis/efectos de los fármacos , Cardiotónicos/farmacología , Proliferación Celular/efectos de los fármacos , Vasos Coronarios/citología , Vasos Coronarios/efectos de los fármacos , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Hipoglucemiantes/farmacología , Bencimidazoles/farmacología , Compuestos de Bifenilo , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Fluorobencenos/farmacología , Glucosa/farmacología , Humanos , Insulina/farmacología , Metformina/farmacología , Pioglitazona , Pirimidinas/farmacología , Rosuvastatina Cálcica , Sulfonamidas/farmacología , Tetrazoles/farmacología , Tiazolidinedionas/farmacologíaRESUMEN
GLP-1 (glucagon-like peptide 1) and its mimetic exendin-4 are used against Type 2 diabetes. C-peptide has also proven promising to enhance insulin action. Since insulin secretion in vivo can be rapidly tuned by changes in islet microcirculation, we evaluated the influence of GLP-1, exendin-4 and C-peptide on pancreatic IBF (islet blood flow), and dynamic changes in insulin secretion and glycaemia in the rat. Adult male Wistar rats were divided into four groups given intravenous saline, GLP-1, exendin-4 or C-peptide respectively and administered either saline or 30% glucose. Furthermore, we investigated the effect of intravenous infusion of different doses of exendin-4 into either the femoral vein or the portal vein on islet microcirculation. A non-radioactive microsphere technique was adopted to measure the regional blood flow. Both GLP-1 and exendin-4 prevented the glucose-induced PBF (pancreatic blood flow) redistribution into the islets. Infusion of exendin-4 into the portal vein did not alter pancreatic islet microcirculation, while infusion of exendin-4 into femoral vein significantly decreased basal IBF. C-peptide increased basal IBF and the proportion of IBF out of total PBF, but did not affect the islet microcirculation after glucose administration. GLP-1, exendin-4 and C-peptide stimulated insulin secretion and significantly decreased glycaemia. Blocking NO formation did not prevent the decreased IBF and post-load glycaemia evoked by exendin-4, but further decreased IBF and KBF (kidney blood flow) and increased basal glycaemia. Blocking the vagus nerve enhanced pancreatic IBF and further decreased post-load glycaemia and KBF and increased basal glycaemia. The vascular modulatory effect on pancreatic islet microcirculation described herein, with subsequent effects on in vivo insulin secretion and glycaemia, might be one of the mechanisms underlying the anti-diabetic actions of GLP-1 and its long acting mimetic exendin-4, as well as that of C-peptide.
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Péptido C/fisiología , Péptido 1 Similar al Glucagón/fisiología , Islotes Pancreáticos/irrigación sanguínea , Microcirculación , Péptidos/fisiología , Animales , Exenatida , Prueba de Tolerancia a la Glucosa , Insulina/sangre , Insulina/metabolismo , Secreción de Insulina , Islotes Pancreáticos/metabolismo , Masculino , NG-Nitroarginina Metil Éster , Óxido Nítrico Sintasa/antagonistas & inhibidores , Ratas , Ratas Wistar , Circulación Renal , Circulación Esplácnica , PonzoñasRESUMEN
Diabetes is a strong risk factor for premature and severe stroke. The GLP-1R (glucagon-like peptide-1 receptor) agonist Ex-4 (exendin-4) is a drug for the treatment of T2D (Type 2 diabetes) that may also have neuroprotective effects. The aim of the present study was to determine the efficacy of Ex-4 against stroke in diabetes by using a diabetic animal model, a drug administration paradigm and a dose that mimics a diabetic patient on Ex-4 therapy. Furthermore, we investigated inflammation and neurogenesis as potential cellular mechanisms underlying the Ex-4 efficacy. A total of seven 9-month-old Type 2 diabetic GotoKakizaki rats were treated peripherally for 4 weeks with Ex-4 at 0.1, 1 or 5 µg/kg of body weight before inducing stroke by transient middle cerebral artery occlusion and for 24 weeks thereafter. The severity of ischaemic damage was measured by evaluation of stroke volume and by stereological counting of neurons in the striatum and cortex. We also quantitatively evaluated stroke-induced inflammation, stem cell proliferation and neurogenesis. We show a profound anti-stroke efficacy of the clinical dose of Ex-4 in diabetic rats, an arrested microglia infiltration and an increase of stroke-induced neural stem cell proliferation and neuroblast formation, while stroke-induced neurogenesis was not affected by Ex-4. The results show a pronounced anti-stroke, neuroprotective and anti-inflammatory effect of peripheral and chronic Ex-4 treatment in middle-aged diabetic animals in a preclinical setting that has the potential to mimic the clinical treatment. Our results should provide strong impetus to further investigate GLP-1R agonists for their neuroprotective action in diabetes, and for their possible use as anti-stroke medication in non-diabetic conditions.
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Isquemia Encefálica/tratamiento farmacológico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Fármacos Neuroprotectores/uso terapéutico , Péptidos/uso terapéutico , Receptores de Glucagón/agonistas , Accidente Cerebrovascular/tratamiento farmacológico , Ponzoñas/uso terapéutico , Animales , Isquemia Encefálica/patología , Proliferación Celular/efectos de los fármacos , Diabetes Mellitus Tipo 2/complicaciones , Evaluación Preclínica de Medicamentos , Exenatida , Receptor del Péptido 1 Similar al Glucagón , Hiperglucemia/tratamiento farmacológico , Masculino , Microglía/efectos de los fármacos , Neurogénesis/efectos de los fármacos , Ratas , Volumen Sistólico/efectos de los fármacosRESUMEN
Diabetes classification is not as defined as it used to be. A patient with one type of diabetes can have diagnostic criteria of another type, which may affect the course of the disease. Clinicians need to consider that when dealing with patients who do not fit the exact description of their diagnosed type of diabetes.
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Introduction: Insulin and its analogues have so far been the only approved treatment for type 1 diabetes in Europe, while in the US, the amylin analog pramlintide is approved for adjuvant use with insulin. However, in clinical practice, various drugs against type 2 diabetes have been used off label with insulin for type 1 diabetes. Recently, the EMA approved the SGLT inhibitors dapagliflozin and sotagliflozin as adjuvant treatments to insulin for type 1 diabetes in adults.Areas covered: This article is a survey of adjuvant treatments used against type 1 diabetes, focusing on SGLT inhibitors.Expert opinion: While GLP-1 R agonists and metformin may reduce weight gain associated with insulin therapy and possibly also confer non-glycemic benefits, only the SGLT inhibitors dapagliflozin and sotagliflozin have been approved in Europe as adjunctive to insulin for type 1 diabetes. Since these drugs act independently of insulin, they are very valuable additions to the armamentarium against type 1 diabetes. However, they should be used judiciously in select patients to mitigate the risk of diabetic ketoacidosis. Patients should be instructed to avoid risk situations and be taught to measure blood ketones themselves.
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Diabetes Mellitus Tipo 1 , Diabetes Mellitus Tipo 2 , Cetoacidosis Diabética , Adulto , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Humanos , Hipoglucemiantes/uso terapéutico , InsulinaRESUMEN
Different dysglycemic states precede overt type 2 diabetes. Prediabetic dysglycemia also carries an increased cardiovascular risk per se. Prediabetic dysglycemia may be divided into impaired fasting glycemia, impaired glucose tolerance and intermediate hyperglycemia. Mixed forms of these are very common. Dysglycemia develops insidiously for many years and usually produces no symptoms until very late. It is possible to prevent prediabetic dysglycemia from progressing to manifest type 2 diabetes and it can also be made to return to normoglycemia. The importance of lifestyle interventions, pharmacological treatment, surgical treatment and community efforts are discussed.