RESUMEN
Histone deacetylase (HDAC) inhibitors such as butyrate have been reported to reduce diabetes risk and protect insulin-secreting pancreatic ß cells in animal models. However, studies on insulin-secreting cells in vitro have found that butyrate treatment resulted in impaired or inappropriate insulin secretion. Our study explores the effects of butyrate on insulin secretion by BRIN BD-11 rat pancreatic ß cells and examined effects on the expression of genes implicated in ß cell function. Robust HDAC inhibition with 5 mM butyrate or trichostatin A for 24 h in ß cells decreased basal insulin secretion and content, as well as insulin secretion in response to acute stimulation. Treatment with butyrate also increased expression of the disallowed gene hexokinase I, possibly explaining the impairment to insulin secretion, and of TXNIP, which may increase oxidative stress and ß cell apoptosis. In contrast to robust HDAC inhibition (>70% after 24 h), low-dose and acute high-dose treatment with butyrate enhanced nutrient-stimulated insulin secretion. In conclusion, although protective effects of HDAC inhibition have been observed in vivo, potent HDAC inhibition impairs ß cell function in vitro. The chronic low dose and acute high dose butyrate treatments may be more reflective of in vivo effects.
Asunto(s)
Ácido Butírico/efectos adversos , Hexoquinasa/metabolismo , Inhibidores de Histona Desacetilasas/efectos adversos , Células Secretoras de Insulina/enzimología , Estrés Oxidativo/efectos de los fármacos , Animales , Ácido Butírico/farmacología , Proteínas de Ciclo Celular/metabolismo , Células Hep G2 , Inhibidores de Histona Desacetilasas/farmacología , Humanos , Células Secretoras de Insulina/patología , RatasRESUMEN
In the quest to understand lost ß-cells regeneration in the diabetic condition, we have demonstrated successful differentiation of human haematopoietic stem cells (HSCs) to functional ß-like cells. Costus igneus (Ci) leaf extract is known to exhibit anti-diabetic properties by lowering the blood glucose level as demonstrated in mice models. To establish the anti-diabetic properties of Ci leaf extract on human subjects, we studied the effect of Ci on these differentiated ß-like cells. Ci leaf extract showed its anti-diabetic property through elevated glucokinase activity which catalyzes the rate-limiting step of glucose catabolism in ß-like cells and acts as a sensor for insulin production while decreasing the glucose-6-phosphatase activity. Upon increasing the concentrations of Ci leaf extract (25, 65, 105, 145, 185 µg/ml) and glucose concentrations (5.5, 11.1, and 25 mM) Ci leaf extract treated ß-like cells showed enhanced glucokinase and decreased glucose-6-phosphatase activities and an exponential rise in gene expressions of INS and GLUT2 was observed. The present study shows enhanced INS and GLUT2 gene expression and elevated glucokinase activity in ß-like cells differentiated from HSCs upon treatment with Ci leaf extract explain the anti-diabetic property of Ci leaf extract. This extract can be effectively used in the management of diabetes.
Asunto(s)
Diferenciación Celular/efectos de los fármacos , Costus/química , Expresión Génica/efectos de los fármacos , Glucoquinasa/metabolismo , Transportador de Glucosa de Tipo 2/genética , Células Madre Hematopoyéticas/citología , Hipoglucemiantes/farmacología , Células Secretoras de Insulina/enzimología , Insulina/genética , Extractos Vegetales/farmacología , Hojas de la Planta/química , Transducción de Señal/efectos de los fármacos , Donantes de Sangre , Células Cultivadas , Glucosa/metabolismo , Glucosa-6-Fosfatasa/metabolismo , Voluntarios Sanos , Células Madre Hematopoyéticas/efectos de los fármacos , HumanosRESUMEN
Traditional Chinese medicine (TCM) plays an important role in the treatment of type 2 diabetes mellitus (T2DM). However, the lack of adequate and scientifically rigorous evidence has limited its application in this disorder. Sanbai melon seed oil (SMSO) is used in folk medicine to treat DM; however, only few literature reports exist regarding its mechanism. Herein, we aimed to confirm the antidiabetic activity of SMSO in a T2DM model and further elucidate its possible mechanisms. The T2DM rat model was induced by high-fat and sugar diet and streptozocin (STZ, 40 mg/kg). SMSO was administered at doses of 0.7 g/kg, 1.4 g/kg, and 2.8 g/kg. Several biochemical parameters and antioxidant protein levels were measured to evaluate the hyperglycemic and antioxidant activities of SMSO. Western blotting was performed to determine its potential mechanism. Based on the results, SMSO treatment significantly reduced blood glucose levels, increased plasma insulin, and repaired islet tissue injury in diabetic rats (P < 0.05). To add, it markedly reduced MDA levels and increased that of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). Western blot results showed that SMSO induced n-Nrf2 and HO-1 expression and Akt and GSK-3ß phosphorylation in a dose-dependent manner. Further studies showed that LY294002, aPI3K inhibitor, abolished the effects of SMSO on GSK-3ß phosphorylation and Nrf2 nuclear translocation as well as the protective effects on pancreatic ß cells. Together, these results suggest that SMSO regulates the Akt/GSK-3ß/Nrf2 pathway and induces the expression of antioxidant proteins to impede oxidative stress in rats with T2DM.
Asunto(s)
Antioxidantes/farmacología , Glucemia/efectos de los fármacos , Citrullus , Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Hipoglucemiantes/farmacología , Células Secretoras de Insulina/efectos de los fármacos , Factor 2 Relacionado con NF-E2/metabolismo , Extractos Vegetales/farmacología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Animales , Antioxidantes/aislamiento & purificación , Apoptosis/efectos de los fármacos , Biomarcadores/sangre , Glucemia/metabolismo , Citrullus/química , Diabetes Mellitus Experimental/sangre , Diabetes Mellitus Experimental/enzimología , Diabetes Mellitus Experimental/patología , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/enzimología , Diabetes Mellitus Tipo 2/patología , Hipoglucemiantes/aislamiento & purificación , Insulina/sangre , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/patología , Masculino , Estrés Oxidativo/efectos de los fármacos , Fosforilación , Extractos Vegetales/aislamiento & purificación , Ratas Sprague-Dawley , Semillas , Transducción de SeñalRESUMEN
BACKGROUND: Rhododendron brachycarpum (RB) is a genus of flowering plants generally used for traditional medicine in Korea to treat hypertension, neuralgia, and sterility. Previous studies have shown that RB extract alleviate inflammation and antimicrobial activity. OBJECTIVE: In this study, the effects of RB and its different fractions (n-hexane, ethyl-acetate and n-butanol) on antioxidant activity, DNA damage prevention and the activity of α-glucosidase were studied. RESULTS: The antioxidant ability of RB was investigated in vitro, including that of DPPH-radical and reducing power. As expected, scavenging effect against DPPH-radical of ethyl acetate fraction (IC50 = 17.7 ± 0.5 µg/ml) of RB had the highest DPPH radical scavenging activity, and it was superior to the positive control, butylated hydroxytoluene (BHT) (IC50 = 80.8 ± 1.5 µg/ml). And the reducing power of RB was 3.18 at 1.0 mg/ml. Meanwhile, the α-glucosidase inhibitory activity and prevention of oxidation stress-induced DNA damage were also highest in the ethyl acetate fraction. Pretreatment of pancreatic ß-cells from Syrian golden hamster (HIT-TI5) with the ethyl acetate fraction at concentrations of 300 µg/ml significantly protected the cells from high glucose-induced cell death. CONCLUSION: Our results indicate that ethyl acetate fraction of RB leaves extract has strong antioxidant, α-glucosidase, and prevention of DNA damage activities, and furthermore, ethyl acetate fraction significantly protected the cells from high glucose-induced cell death.
Asunto(s)
Antioxidantes/farmacología , Inhibidores de Glicósido Hidrolasas/farmacología , Células Secretoras de Insulina/efectos de los fármacos , Extractos Vegetales/farmacología , Rhododendron/química , alfa-Glucosidasas/metabolismo , Animales , Antioxidantes/aislamiento & purificación , Compuestos de Bifenilo/química , Línea Celular , Supervivencia Celular/efectos de los fármacos , Daño del ADN , Inhibidores de Glicósido Hidrolasas/aislamiento & purificación , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/metabolismo , Mesocricetus , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/genética , Picratos/química , Extractos Vegetales/aislamiento & purificación , Hojas de la Planta/químicaRESUMEN
Corydalis edulis Maxim., a widely grown plant in China, had been proposed for the treatment for type 2 diabetes mellitus. In this study, we found that C. edulis extract (CE) is protective against diabetes in mice. The treatment of hyperglycemic and hyperlipidemic apolipoprotein E (ApoE)-/- mice with a high dose of CE reduced serum glucose by 28.84% and serum total cholesterol by 17.34% and increased insulin release. We also found that CE significantly enhanced insulin secretion in a glucose-independent manner in hamster pancreatic ß cell (HIT-T15). Further investigation revealed that CE stimulated insulin exocytosis by a protein kinase C (PKC)-dependent signaling pathway and that CE selectively activated novel protein kinase Cs (nPKCs) and atypical PKCs (aPKCs) but not conventional PKCs (cPKCs) in HIT-T15 cells. To the best of our knowledge, our study is the first to identify the PKC pathway as a direct target and one of the major mechanisms underlying the antidiabetic effect of CE. Given the good insulinotropic effect of this herbal medicine, CE is a promising agent for the development of new drugs for treating diabetes.
Asunto(s)
Corydalis/química , Células Secretoras de Insulina/enzimología , Insulina/metabolismo , Extractos Vegetales/farmacología , Proteína Quinasa C/metabolismo , Animales , Apolipoproteínas E/deficiencia , Apolipoproteínas E/metabolismo , Glucemia/metabolismo , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Colesterol/metabolismo , Cricetinae , Citosol/efectos de los fármacos , Citosol/metabolismo , Activación Enzimática/efectos de los fármacos , Exocitosis/efectos de los fármacos , Ayuno/sangre , Prueba de Tolerancia a la Glucosa , Insulina/sangre , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Masculino , Ratones , Transporte de Proteínas/efectos de los fármacos , ARN Interferente Pequeño/metabolismo , Transfección , Triglicéridos/metabolismoRESUMEN
INTRODUCTION: The protective effects of grapefruit-derived naringin against HIV-1 Protease Inhibitors (PIs)-associated oxidative damage to pancreatic ß-cells and apoptosis were investigated in RIN-5F cells in culture. METHODS: Cells in culture medium were challenged with 11-25 mM glucose with or without nelfinavir (1-10 µM), saquinavir (1-10 µM) and atazanavir (5-20 µM), respectively for 24 h to determine insulin secretion. The cells were further treated with nelfinavir (10 µM), saquinavir (10 µM), atazanavir (20 µM) with and without naringin or glibenclamide (10 µM) for 24 h to determine insulin secretion, lipid peroxidation, Superoxide Dismutase (SOD) activity, glutathione (GSH) levels, ATP production and caspase-3 and-9 activities, respectively. RESULTS: Glucose-dependent insulin secretion was significantly reduced by PIs in a concentration-dependent manner. Treatment with either naringin or glibenclamide significantly reduced lipid peroxidation, Superoxide Dismutase (SOD) activities and also increased glutathione (GSH) and ATP levels in the cells that were treated with PIs. Furthermore, naringin or glibenclamide significantly reduced caspase-3 and caspase-9 activities in cells that were treated with PIs. CONCLUSIONS: PIs impair ß-cell functions by increasing oxidative stress and apoptosis. Treatment with naringin protected RIN-5F cells from PI-induced oxidative damage and apoptosis. Our results therefore suggest that nutritional supplements with naringin could prevent pancreatic ß-cell dysfunction and the attendant metabolic complications caused by PIs in patients on antiretroviral therapy.
Asunto(s)
Apoptosis/efectos de los fármacos , Citoprotección/efectos de los fármacos , Flavanonas/farmacología , Inhibidores de la Proteasa del VIH/efectos adversos , Proteasa del VIH/metabolismo , Células Secretoras de Insulina/patología , Sustancias Protectoras/farmacología , Adenosina Trifosfato/metabolismo , Animales , Caspasa 3/metabolismo , Caspasa 9/metabolismo , Línea Celular , Supervivencia Celular/efectos de los fármacos , Glucosa/farmacología , Glutatión/metabolismo , Concentración 50 Inhibidora , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/metabolismo , Peroxidación de Lípido/efectos de los fármacos , Malondialdehído/metabolismo , Ratas , Superóxido Dismutasa/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismoRESUMEN
Despite significant advances in our understanding of the biology determining systemic energy homeostasis, the treatment of obesity remains a medical challenge. Activation of AMP-activated protein kinase (AMPK) has been proposed as an attractive strategy for the treatment of obesity and its complications. AMPK is a conserved, ubiquitously expressed, heterotrimeric serine/threonine kinase whose short-term activation has multiple beneficial metabolic effects. Whether these translate into long-term benefits for obesity and its complications is unknown. Here, we observe that mice with chronic AMPK activation, resulting from mutation of the AMPK γ2 subunit, exhibit ghrelin signaling-dependent hyperphagia, obesity, and impaired pancreatic islet insulin secretion. Humans bearing the homologous mutation manifest a congruent phenotype. Our studies highlight that long-term AMPK activation throughout all tissues can have adverse metabolic consequences, with implications for pharmacological strategies seeking to chronically activate AMPK systemically to treat metabolic disease.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/patología , Obesidad/enzimología , Adiposidad/genética , Adulto , Envejecimiento/patología , Proteína Relacionada con Agouti/metabolismo , Animales , Núcleo Arqueado del Hipotálamo/metabolismo , Metabolismo Energético/genética , Activación Enzimática , Conducta Alimentaria , Femenino , Heterocigoto , Humanos , Hiperfagia/complicaciones , Hiperfagia/enzimología , Hiperfagia/genética , Hiperfagia/patología , Hipotálamo/metabolismo , Insulina/metabolismo , Masculino , Ratones , Mitocondrias/metabolismo , Mutación/genética , Neuronas/metabolismo , Obesidad/sangre , Obesidad/complicaciones , Obesidad/patología , Fosforilación Oxidativa , Receptores de Ghrelina/metabolismo , Ribosomas/metabolismo , Transducción de Señal/genética , Transcriptoma/genética , Regulación hacia Arriba/genéticaRESUMEN
AIM: To observe the effect of modified Si-Miao-San (mSMS) on advanced glycation end products (AGEs)-induced pancreatic B cell dysfunction, as well as examining the underlying mechanisms. METHOD: Pancreatic B cells (INS-1) were stimulated with advanced glycation end products (AGEs, 200 µg·mL(-1)) for 24 h to produce dysfunction in pancreatic B cells and the effects of mSMS observed on insulin secretion, NF-κB (p65) phosphorylation, reactive oxygen species (ROS) production, mitochondria membrane potential (Δψm), cell apoptosis, phosphorylation of AMP-kinase (AMPK), and caspase 3 activity. RESULTS: The AGEs challenge resulted in increased basal insulin secretion, but decreased insulin secretion in response to high glucose, whereas this situation was reversed by mSMS treatment. AGEs stimulation induced NF-κB (p65) phosphorylation and reactive oxygen species (ROS) production, as well as Δψm collapse and cell apoptosis. mSMS inhibited ROS production and inhibited NF-κB activation by attenuating p65 phosphorylation. Meanwhile, AGEs-induced Δψm collapse and cell apoptosis were also reversed by mSMS treatment. Compound C, an inhibitor of AMP-Kinase (AMPK), abolished the beneficial effects of mSMS on the regulation of B cell function, indicating the involvement of AMPK. CONCLUSION: mSMS ameliorated AGEs-induced B cell dysfunction by suppressing ROS-associated inflammation, and this action was related to its beneficial regulation of AMPK activity.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Medicamentos Herbarios Chinos/farmacología , Inflamación/enzimología , Células Secretoras de Insulina/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Proteínas Quinasas Activadas por AMP/genética , Animales , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Glucosa/metabolismo , Productos Finales de Glicación Avanzada/metabolismo , Humanos , Inflamación/tratamiento farmacológico , Inflamación/genética , Inflamación/metabolismo , Células Secretoras de Insulina/citología , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/metabolismo , Fosforilación , RatasRESUMEN
ß-Cell mitochondrial dysfunction as well as proinflammatory cytokines have been suggested to contribute to reduced glucose-stimulated insulin secretion (GSIS) in type 2 diabetes. We recently demonstrated that Cohen diabetic sensitive (CDs) rats fed a high-sucrose, low-copper diet (HSD) developed hyperglycemia and reduced GSIS in association with peri-islet infiltration of fat and interleukin (IL)-1ß-expressing macrophages, whereas CD resistant (CDr) rats remained normoglycemic on HSD. We examined: 1) the correlation between copper concentration in the HSD and progression, prevention, and reversion of hyperglycemia in CDs rats, 2) the relationship between activity of the copper-dependent, respiratory-chain enzyme cytochrome c oxidase (COX), infiltration of fat, IL-1ß-expressing macrophages, and defective GSIS in hyperglycemic CDs rats. CDs and CDr rats were fed HSD or copper-supplemented HSD before and during hyperglycemia development. Blood glucose and insulin concentrations were measured during glucose tolerance tests. Macrophage infiltration and IL-1ß expression were evaluated in pancreatic sections by electron-microscopy and immunostaining. COX activity was measured in pancreatic sections and isolated islets. In CDs rats fed HSD, GSIS and islet COX activity decreased, while blood glucose and infiltration of fat and IL-1ß-expressing macrophages increased with time on HSD (P < 0.01 vs. CDr-HSD rats, all parameters, respectively). CDs rats maintained on copper-supplemented HSD did not develop hyperglycemia, and in hyperglycemic CDs rats, copper supplementation restored GSIS and COX activity, reversed hyperglycemia and infiltration of fat and IL-1ß-expressing macrophages (P < 0.01 vs. hyperglycemic CDs-HSD rats, all parameters, respectively). We provide novel evidence for a critical role of low dietary copper in diminished GSIS of susceptible CDs rats involving the combined consequence of reduced islet COX activity and pancreatic low-grade inflammation.
Asunto(s)
Cobre/administración & dosificación , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Complejo IV de Transporte de Electrones/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Insulina/metabolismo , Mitocondrias/efectos de los fármacos , Animales , Glucemia/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/prevención & control , Suplementos Dietéticos , Ácidos Grasos no Esterificados/metabolismo , Prueba de Tolerancia a la Glucosa , Hiperglucemia/enzimología , Hiperglucemia/metabolismo , Hiperglucemia/prevención & control , Inmunohistoquímica , Insulina/sangre , Secreción de Insulina , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/ultraestructura , Interleucina-1beta/metabolismo , Masculino , Microscopía Electrónica de Transmisión , Mitocondrias/metabolismo , Ratas , Triglicéridos/metabolismoRESUMEN
Various pancreatic ß-cell stressors, including cytokines, are known to induce oxidative stress, resulting in apoptotic/necrotic cell death and inhibition of insulin secretion. Traditionally, olive leaves or fruits are used for treating diabetes, but the cellular mechanism(s) of their effects are not known. We examined the effects of Olea europea L. (olive) leaf and fruit extracts and their component oleuropein on cytokine-induced ß-cell toxicity. INS-1, an insulin-producing ß-cell line, was preincubated with or without increasing concentrations of olive leaf or fruit extract or oleuropein for 24 hr followed by exposure to a cytokine cocktail containing 0.15 ng/mL interleukin-1ß (IL-1ß), 1 ng/mL interferon-γ (IFN-γ), and 1 ng/mL tumor necrosis factor-α (TNF-α) for 6 hr. The cytotoxicity was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) testing. Apoptosis was quantified by detecting acridine orange/ethidium bromide-stained condensed nuclei under a fluorescent microscope. The cells exposed to cytokines had a higher apoptotic rate, a decreased viability (MTT), and an increased caspase 3/7 activity. Both extracts and oleuropein partially increased the proportion of living cells and improved the viability of cells after cytokines. The protective effects of extracts on live cell viability were mediated through the suppression of caspase 3/7 activity. Oleuropein did not decrease the amount of both apoptotic and necrotic cells, whereas extracts significantly protected cells against cytokine-induced death. Cytokines led to an increase in reactive oxygen species (ROS) generation and inhibited glutathione level, superoxide dismutase activity, and insulin secretion in INS-1. Insulin secretion was almost completely protected by leaf extract, but was partially affected by fruit extract or oleuropein. Neither cytokines nor olive derivatives had a significant effect on cellular cytochrome c release and catalase activity. Moreover, the cells incubated with each extract or oleuropein showed a significant reduction in cytokine-induced ROS production and ameliorated abnormal antioxidant defense. The molecular mechanism by which olive polyphenols inhibit cytokine-mediated ß-cell toxicity appears to be involving the maintenance of redox homeostasis.
Asunto(s)
Citocinas/farmacología , Citoprotección/efectos de los fármacos , Homeostasis/efectos de los fármacos , Células Secretoras de Insulina/patología , Olea/química , Extractos Vegetales/farmacología , Polifenoles/farmacología , Animales , Caspasa 3/metabolismo , Caspasa 7/metabolismo , Muerte Celular/efectos de los fármacos , Línea Celular , Citocromos c/metabolismo , Glutatión/metabolismo , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/metabolismo , Glucósidos Iridoides , Iridoides , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Oxidación-Reducción/efectos de los fármacos , Piranos/farmacología , Ratas , Especies Reactivas de Oxígeno/metabolismo , Superóxido Dismutasa/metabolismoRESUMEN
Oxidative stress plays a pivotal role during the islet transplantation procedure, and antioxidant supplementation may protect grafts against oxidative injury. Chinese bayberry is one of six Myrica species native to China, and we demonstrated here that anthocyanins from Chinese bayberry extract (CBE) protect pancreatic ß cells (INS-1) against hydrogen peroxide (H(2)O(2))-induced necrosis and apoptosis. Anthocyanins time- and dose-dependently upregulated heme oxygenase-1 (HO-1) gene expression in ß cells and primary islets. HO-1 knockdown increased H(2)O(2)-induced cell death and attenuated the cytoprotective effect of anthocyanins. Anthocyanin treatment activated ERK1/2 and PI3K/Akt signaling, and ERK1/2 and PI3K inhibitors partially attenuated anthocyanin-mediated induction of HO-1. Additionally, ß cells pretreated with anthocyanins displayed a decreased extent of apoptosis after transplantation. In summary, these results suggest that anthocyanins in CBE protect ß cells from H(2)O(2)-induced cell injury via ERK1/2- and PI3K/Akt-mediated HO-1 upregulation.
Asunto(s)
Antocianinas/farmacología , Medicamentos Herbarios Chinos/farmacología , Hemo-Oxigenasa 1/genética , Células Secretoras de Insulina/metabolismo , Myrica/química , Estrés Oxidativo/efectos de los fármacos , Sustancias Protectoras/farmacología , Regulación hacia Arriba/efectos de los fármacos , Animales , Línea Celular Tumoral , Hemo-Oxigenasa 1/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/enzimología , Islotes Pancreáticos/citología , Islotes Pancreáticos/efectos de los fármacos , Islotes Pancreáticos/enzimología , Islotes Pancreáticos/metabolismo , Ratones , Ratones Endogámicos ICR , RatasRESUMEN
Pancreatic islets contain low activities of catalase, selenium-dependent glutathione peroxidase 1 (GPX1), and Cu,Zn-superoxide dismutase 1 (SOD1). Thus, enhancing expression of these enzymes in islets has been unquestionably favored. However, such an attempt has produced variable metabolic outcomes. While ß cell-specific overexpression of Sod1 enhanced mouse resistance to streptozotocin-induced diabetes, the same manipulation of catalase aggravated onset of type 1 diabetes in nonobese diabetic mice. Global overexpression of Gpx1 in mice induced type 2 diabetes-like phenotypes. Although knockouts of Gpx1 and Sod1 each alone or together decreased pancreatic ß cell mass and plasma insulin concentrations, these knockouts improved body insulin sensitivity to different extents. Pancreatic duodenal homeobox 1, forkhead box A2, and uncoupling protein 2 are three key regulators of ß cell mass, insulin synthesis, and glucose-stimulated insulin secretion. Phenotypes resulted from altering GPX1 and/or SOD1 were partly mediated through these factors, along with protein kinase B and c-jun terminal kinase. A shifted reactive oxygen species inhibition of protein tyrosine phosphatases in insulin signaling might be attributed to altered insulin sensitivity. Overall, metabolic roles of antioxidant enzymes in ß cells and diabetes depend on body oxidative status and target functions. Revealing regulatory mechanisms for this type of dual role will help prevent potential pro-diabetic risk of antioxidant over-supplementation to humans.
Asunto(s)
Antioxidantes/metabolismo , Diabetes Mellitus Tipo 1/enzimología , Células Secretoras de Insulina/enzimología , Animales , Catalasa/metabolismo , Diabetes Mellitus Tipo 1/fisiopatología , Glucosa/metabolismo , Glutatión Peroxidasa/metabolismo , Factor Nuclear 3-beta del Hepatocito/metabolismo , Proteínas de Homeodominio/metabolismo , Humanos , Insulina/metabolismo , Canales Iónicos/metabolismo , Proteínas Mitocondriales/metabolismo , Estrés Oxidativo , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal/fisiología , Superóxido Dismutasa/metabolismo , Transactivadores/metabolismo , Proteína Desacopladora 2 , Glutatión Peroxidasa GPX1Asunto(s)
Hipotálamo/fisiología , Células Secretoras de Insulina/fisiología , Animales , Diferenciación Celular , Ectodermo/citología , Ectodermo/fisiología , Endodermo/citología , Endodermo/fisiología , Metabolismo Energético , Marcación de Gen/métodos , Humanos , Hipotálamo/enzimología , Células Secretoras de Insulina/enzimología , Integrasas/genética , Ratones , Modelos Animales , FenotipoRESUMEN
Functional insulin receptor and its downstream effector PI3K (phosphoinositide 3-kinase) have been identified in pancreatic ß-cells, but their involvement in the regulation of insulin secretion from ß-cells remains unclear. In the present study, we investigated the physiological role of insulin and PI3K in glucose-induced biphasic insulin exocytosis in primary cultured ß-cells and insulinoma Min6 cells using total internal reflection fluorescent microscopy. The pretreatment of ß-cells with insulin induced the rapid increase in intracellular Ca2+ levels and accelerated the exocytotic response without affecting the second-phase insulin secretion. The inhibition of PI3K not only abolished the insulin-induced rapid development of the exocytotic response, but also potentiated the second-phase insulin secretion. The rapid development of Ca2+ and accelerated exocytotic response induced by insulin were accompanied by the translocation of the Ca2+-permeable channel TrpV2 (transient receptor potential V2) in a PI3K-dependent manner. Inhibition of TrpV2 by the selective blocker tranilast, or the expression of shRNA (short-hairpin RNA) against TrpV2 suppressed the effect of insulin in the first phase, but the second phase was not affected. Thus our results demonstrate that insulin treatment induced the acceleration of the exocytotic response during the glucose-induced first-phase response by the insertion of TrpV2 into the plasma membrane in a PI3K-dependent manner.
Asunto(s)
Canales de Calcio/genética , Células Secretoras de Insulina/fisiología , Insulina/fisiología , Canales Catiónicos TRPV/genética , Animales , Secuencia de Bases , Línea Celular , ADN/química , ADN/genética , ADN Complementario/genética , Exocitosis , Hormona del Crecimiento/metabolismo , Homeostasis , Humanos , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Fosfatidilinositol 3-Quinasas/metabolismo , TransfecciónRESUMEN
Human acatalasemia may be a risk factor for the development of diabetes mellitus. However, the mechanism by which diabetes is induced is still poorly understood. The impact of catalase deficiency on the onset of diabetes has been studied in homozygous acatalasemic mutant mice or control wild-type mice by intraperitoneal injection of diabetogenic alloxan. The incidence of diabetes was higher in acatalasemic mice treated with a high dose (180 mg/kg body weight) of alloxan. A higher dose of alloxan accelerated severe atrophy of pancreatic islets and induced pancreatic beta cell apoptosis in acatalasemic mice in comparison to wild-type mice. Catalase activity remained low in the acatalasemic pancreas without the significant compensatory up-regulation of glutathione peroxidase or superoxide dismutase. Furthermore, daily intraperitoneal injection of angiotensin II type 1 (AT1) receptor antagonist telmisartan (0.1 mg/kg body weight) prevented the development of alloxan-induced hyperglycemia in acatalasemic mice. This study suggests that catalase plays a crucial role in the defense against oxidative-stress-mediated pancreatic beta cell death in an alloxan-induced diabetes mouse model. Treatment with telmisartan may prevent the onset of alloxan-induced diabetes even under acatalasemic conditions.
Asunto(s)
Diabetes Mellitus Experimental/metabolismo , Acatalasia/metabolismo , Aloxano , Bloqueadores del Receptor Tipo 1 de Angiotensina II/uso terapéutico , Animales , Apoptosis , Bencimidazoles/uso terapéutico , Benzoatos/uso terapéutico , Glucemia/efectos de los fármacos , Glucemia/metabolismo , Peso Corporal , Catalasa/metabolismo , Muerte Celular , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/prevención & control , Glutatión Peroxidasa/metabolismo , Homocigoto , Hiperglucemia/enzimología , Hiperglucemia/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/patología , Células Secretoras de Insulina/fisiología , Masculino , Ratones , Ratones Endogámicos C3H , Ratones Noqueados , Ratones Mutantes , Superóxido Dismutasa/metabolismo , TelmisartánAsunto(s)
Benzoquinonas/farmacología , Glucosa/farmacología , Inhibidores de la Proteasa del VIH/toxicidad , Insulina/metabolismo , Estrés Oxidativo/efectos de los fármacos , Sustancias Protectoras/farmacología , Animales , Línea Celular , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/metabolismo , Nigella sativa/química , Aceites de Plantas/farmacología , RatasRESUMEN
The highly active anti-retroviral therapy (HAART) regimen has considerably reduced the mortality rate in HIV-1 positive patients. However, long-term exposure to HAART is associated with a metabolic syndrome manifesting cardiovascular dysfunction, lipodystrophy, and insulin resistance syndrome (IRS). The inclusion of HIV-1 protease inhibitors (PIs) in HAART has been linked to the induction of IRS. Although several molecular mechanisms of PI-induced effects on insulin action have been postulated, the deleterious effects of PIs on insulin production by pancreatic beta-cells have not been fully investigated and therapeutic strategies to ameliorate insulin dysregulation at this level have not been targeted. The present study showed that exposure to several different PIs, nelfinavir (5-10 microM), saquinavir (5-10 microM) and atazanavir (8-20 microM), decreases glucose stimulated insulin secretion from rat pancreatic beta-cells (INS-1). Nelfinavir significantly increased reactive oxygen species (ROS) generation and suppressed cytosolic, but not mitochondrial superoxide dismutase (SOD) levels. Nelfinvair also decreased both glutathione and ATP and increased UCP2 levels in these cells. Simultaneous treatment with thymoquinone (TQ) (2.5 microM), an active ingredient of black seed oil, significantly inhibited the effect of nelfinavir on augmented ROS production and suppressed SOD levels. Both TQ and black seed oil exposure increased glucose stimulated insulin secretion and ameliorated the suppressive effect of nelfinavir. The present findings imply a direct role of ROS in PI induced deleterious effects on pancreatic beta-cells. Our findings also suggest that TQ may be used as a potential therapeutic agent to normalize the dysregulated insulin production observed in HAART treated patients.
Asunto(s)
Benzoquinonas/farmacología , Glucosa/farmacología , Inhibidores de la Proteasa del VIH/toxicidad , Insulina/metabolismo , Estrés Oxidativo/efectos de los fármacos , Sustancias Protectoras/farmacología , Adenosina Trifosfato/metabolismo , Animales , Sulfato de Atazanavir , Línea Celular , Citosol/efectos de los fármacos , Citosol/enzimología , Glutatión/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/enzimología , Células Secretoras de Insulina/metabolismo , Canales Iónicos/metabolismo , Mitocondrias/efectos de los fármacos , Mitocondrias/enzimología , Proteínas Mitocondriales/metabolismo , Nelfinavir/toxicidad , Nigella sativa/química , Oligopéptidos/toxicidad , Aceites de Plantas/farmacología , Piridinas/toxicidad , Ratas , Especies Reactivas de Oxígeno/metabolismo , Saquinavir/toxicidad , Semillas/química , Superóxido Dismutasa/metabolismo , Proteína Desacopladora 2RESUMEN
Hepatic GK (glucokinase) plays a key role in maintaining glucose homoeostasis. Many stimuli regulate GK activity by controlling its gene transcription. We hypothesized that endogenous lipophilic molecules modulate hepatic Gck expression. Lipophilic molecules were extracted from rat livers, saponified and re-constituted as an LE (lipophilic extract). LE synergized with insulin to induce primary hepatocyte, but not beta-cell, Gck expression in an SREBP-1c (sterol-regulatory-element-binding protein-1c)-independent manner. The dramatic induction of Gck mRNA resulted in a significant increase in GK activity. Subsequently, the active molecules were identified as retinol and retinal by MS after the purification of the active LE fractions. Retinoids synergized with insulin to induce Gck expression by the activation of both RAR [RA (retinoic acid) receptor] and RXR (retinoid X receptor). Inhibition of RAR activation completely abolished the effect of retinal. The hepatic GK specific activity and Gck mRNA levels of Zucker lean rats fed with a VAD [VA (vitamin A)-deficient] diet were significantly lower than those of rats fed with VAS (VA-sufficient) diet. Additionally, the hepatic Gck mRNA expression of Sprague-Dawley rats fed with a VAD diet was lower than that of rats fed with VA-marginal, -adequate or -supplemented diets. The reduced expression of Gck mRNA was increased after an intraperitoneal dose of RA in VAD rats. Furthermore, an intravenous injection of RA rapidly raised hepatic Gck expression in rats fed with a VAS control diet. Understanding the underlying mechanism that mediates the synergy may be helpful for developing a treatment strategy for patients with diabetes.
Asunto(s)
Glucoquinasa/biosíntesis , Insulina/farmacología , Hígado/efectos de los fármacos , Hígado/enzimología , Retinoides/farmacología , Animales , Células Cultivadas , Fraccionamiento Químico , Inducción Enzimática/efectos de los fármacos , Glucoquinasa/genética , Hepatocitos/efectos de los fármacos , Hepatocitos/enzimología , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/enzimología , Estabilidad del ARN/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores de Ácido Retinoico/metabolismo , Retinaldehído/farmacología , Receptor alfa de Ácido Retinoico , Receptores X Retinoide/metabolismo , Retinoides/administración & dosificación , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/genética , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo , Extractos de Tejidos/metabolismo , Vitamina A/farmacología , Deficiencia de Vitamina A/metabolismoRESUMEN
Protandim is an antioxidant supplement that consists of five ingredients, namely, ashwagandha, bacopa extract, green tea extract, silymarin, and curcumin, each with known therapeutic properties. Protandim was formulated with the objective of combining multiple phytochemicals at low nontoxic doses to gain synergy among them. A recent clinical study demonstrated the in vivo antioxidant effects of Protandim (S.K. Nelson et al., 2006, Free Radic. Biol. Med. 40, 341-347). The objective of the present study was to determine if the components of Protandim induce heme oxygenase-1 (HO-1) in a synergistic manner in cultured MIN6 cells, a mouse beta-cell line, and in SK-N-MC cells, a human neuroblastoma cell line. When the components of Protandim were tested alone at low doses, curcumin showed minimal induction, whereas the others were unable to induce the HO-1 promoter, assayed by transient transfection. All components together, however, produced a strongly synergistic induction of around three- to ninefold in a dose-dependent manner, greatly exceeding the sum of the parts. Similar findings were obtained for the expression of HO-1 at the mRNA and protein levels. Protandim-mediated HO-1 induction involved the presence of ARE sites in the HO-1 promoter and nuclear translocalization of the transcription factor Nrf2, which binds to ARE sites. The involvement of multiple signaling pathways, including PI3-kinase/Akt, p38MAPK, and PKCdelta, in HO-1 induction seems to be the probable mechanism of synergy between the components of Protandim. There were significant increases in the levels of total glutathione in Protandim-treated cells. These findings suggest that the use of a combination of phytochemicals may be an efficient method for the induction of antioxidant enzymes.
Asunto(s)
Antioxidantes/farmacología , Inducción Enzimática/efectos de los fármacos , Hemo-Oxigenasa 1/metabolismo , Factor 2 Relacionado con NF-E2/metabolismo , Transporte Activo de Núcleo Celular/efectos de los fármacos , Animales , Antioxidantes/química , Línea Celular , Núcleo Celular/metabolismo , Curcumina/farmacología , Relación Dosis-Respuesta a Droga , Sinergismo Farmacológico , Medicamentos Herbarios Chinos/química , Medicamentos Herbarios Chinos/farmacología , Glutatión/genética , Glutatión/metabolismo , Hemo-Oxigenasa 1/genética , Humanos , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/enzimología , Ratones , Factor 2 Relacionado con NF-E2/genética , Preparaciones Farmacéuticas/química , Fosfatidilinositol 3-Quinasas/metabolismo , Regiones Promotoras Genéticas , Proteína Quinasa C-delta/metabolismo , Elementos de Respuesta/efectos de los fármacos , Transducción de Señal , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Obesity promotes insulin resistance and chronic inflammation. Disrupting any of several distinct steps in lipid synthesis decreases adiposity, but it is unclear if this approach coordinately corrects the environment that propagates metabolic disease. We tested the hypothesis that inactivation of FAS in the hypothalamus prevents diet-induced obesity and systemic inflammation. Ten weeks of high-fat feeding to mice with inactivation of FAS (FASKO) limited to the hypothalamus and pancreatic beta cells protected them from diet-induced obesity. Though high-fat fed FASKO mice had no beta-cell phenotype, they were hypophagic and hypermetabolic, and they had increased insulin sensitivity at the liver but not the periphery as demonstrated by hyperinsulinemic-euglycemic clamps, and biochemically by increased phosphorylated Akt, glycogen synthase kinase-3beta, and FOXO1 compared with wild-type mice. High-fat fed FASKO mice had decreased excretion of urinary isoprostanes, suggesting less oxidative stress and blunted tumor necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) responses to endotoxin, suggesting less systemic inflammation. Pair-feeding studies demonstrated that these beneficial effects were dependent on central FAS disruption and not merely a consequence of decreased adiposity. Thus, inducing central FAS deficiency may be a valuable integrative strategy for treating several components of the metabolic syndrome, in part by correcting hepatic insulin resistance and suppressing inflammation.