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1.
Ecotoxicol Environ Saf ; 188: 109875, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31706244

RESUMO

Previous works showed that chronic exposure to Aroclor 1254 disrupted glucose homeostasis and induced insulin resistance in male mice. To further observe the different effects of Aroclor 1254 exposure on the pancreatic α-cells and ß-cells, male mice were exposed to Aroclor 1254 (0, 0.5, 5, 50, 500 µg/kg) for 60 days, the pancreas was performed a histological examination. The results showed that the percentage of apoptosis cell (indicated by TUNEL assay) was increased in both α-cells and ß-cells, as the Aroclor 1254 dose was increased; the proliferation (indicated by PCNA expression) rate of ß-cells was elevated while that of α-cells was not affected, resulting in an increased ß-cell mass and a decreased α-cell mass in a dose-depend manner. The number of Pdx-1 positive ß-cells was significantly increased whereas that of Arx positive α-cells was markedly decreased, indicating an enhanced ß-cell neogenesis and a weakened α-cell neogenesis. The drastically reduction of serum testosterone levels in all the treatments suggested an anti-androgenic potency of Aroclor 1254. The up-regulation of estrogen receptors (ERα and ERß) and androgen receptor in ß-cells might be responsible for the increased ß-cell mass and neogenesis.


Assuntos
Antitireóideos/toxicidade , Células Secretoras de Glucagon/efeitos dos fármacos , Células Secretoras de Insulina/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Secretoras de Glucagon/metabolismo , Células Secretoras de Glucagon/patologia , Proteínas de Homeodomínio/metabolismo , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Masculino , Camundongos , Receptores Androgênicos/metabolismo , Receptores Estrogênicos/metabolismo , Testosterona/sangue , Transativadores/metabolismo , Fatores de Transcrição/metabolismo
2.
Equine Vet J ; 52(1): 126-130, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30980682

RESUMO

BACKGROUND: The hyperglycaemic clamp has been used for measurement of insulin sensitivity (IS) but not for measurement of ß-cell response in the horse. However, the repeatability of this test has not been reported for horses. OBJECTIVES: To determine the repeatability and reliability of measures for IS and ß-cell response to glucose using the hyperglycaemic clamp in horses. STUDY DESIGN: Repeated measures, longitudinal study. METHODS: Six healthy Standardbred mares underwent a 120-min hyperglycaemic clamp on two occasions with a 10-day washout period. Indices of repeatability and reliability were calculated from measures of IS and ß-cell response to glucose derived from each hyperglycaemic clamp. RESULTS: Measures of ß-cell response to glucose, including area under the insulin response curve in the time interval 0-120 min and during steady state (60-120 min), as well as the mean insulin concentration during steady state had coefficient of variations (CV) of 9.5, 10.5 and 9.3 respectively and intraclass correlation coefficients (ICC) of 0.93, 0.93 and 0.95 respectively. The measure of glucose disposal (M) had lower CV (12.4) and ICC (0.71) compared to measure of IS (M/I-index; CV of 17.4 and ICC of 0.89). MAIN LIMITATIONS: The study was conducted in a small number of horses. CONCLUSIONS: The hyperglycaemic clamp is a diagnostic method for assessing ß-cell response to intravenous glucose with high repeatability and reliability. Insulin sensitivity can be determined with the same test but the repeatability for these measurements is lower compared to the measurements for ß-cell response.


Assuntos
Técnica Clamp de Glucose/veterinária , Cavalos/fisiologia , Resistência à Insulina/fisiologia , Células Secretoras de Insulina/efeitos dos fármacos , Animais , Glicemia , Feminino , Cavalos/sangue , Células Secretoras de Insulina/metabolismo
3.
Nat Genet ; 51(11): 1588-1595, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31676868

RESUMO

The early stages of type 1 diabetes (T1D) are characterized by local autoimmune inflammation and progressive loss of insulin-producing pancreatic ß cells. Here we show that exposure to proinflammatory cytokines reveals a marked plasticity of the ß-cell regulatory landscape. We expand the repertoire of human islet regulatory elements by mapping stimulus-responsive enhancers linked to changes in the ß-cell transcriptome, proteome and three-dimensional chromatin structure. Our data indicate that the ß-cell response to cytokines is mediated by the induction of new regulatory regions as well as the activation of primed regulatory elements prebound by islet-specific transcription factors. We find that T1D-associated loci are enriched with newly mapped cis-regulatory regions and identify T1D-associated variants disrupting cytokine-responsive enhancer activity in human ß cells. Our study illustrates how ß cells respond to a proinflammatory environment and implicate a role for stimulus response islet enhancers in T1D.


Assuntos
Cromatina/genética , Citocinas/farmacologia , Diabetes Mellitus Tipo 1/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Redes Reguladoras de Genes , Células Secretoras de Insulina/metabolismo , Transcriptoma , Cromatina/química , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/patologia , Elementos Facilitadores Genéticos , Estudo de Associação Genômica Ampla , Humanos , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/patologia , Fatores de Transcrição
4.
Nat Med ; 25(11): 1739-1747, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31700183

RESUMO

Type 2 diabetes is characterized by insulin resistance and a gradual loss of pancreatic beta cell mass and function1,2. Currently, there are no therapies proven to prevent beta cell loss and some, namely insulin secretagogues, have been linked to accelerated beta cell failure, thereby limiting their use in type 2 diabetes3,4. The adipokine adipsin/complement factor D controls the alternative complement pathway and generation of complement component C3a, which acts to augment beta cell insulin secretion5. In contrast to other insulin secretagogues, we show that chronic replenishment of adipsin in diabetic db/db mice ameliorates hyperglycemia and increases insulin levels while preserving beta cells by blocking dedifferentiation and death. Mechanistically, we find that adipsin/C3a decreases the phosphatase Dusp26; forced expression of Dusp26 in beta cells decreases expression of core beta cell identity genes and sensitizes to cell death. In contrast, pharmacological inhibition of DUSP26 improves hyperglycemia in diabetic mice and protects human islet cells from cell death. Pertaining to human health, we show that higher concentrations of circulating adipsin are associated with a significantly lower risk of developing future diabetes among middle-aged adults after adjusting for body mass index (BMI). Collectively, these data suggest that adipsin/C3a and DUSP26-directed therapies may represent a novel approach to achieve beta cell health to treat and prevent type 2 diabetes.


Assuntos
Complemento C3a/genética , Fator D do Complemento/farmacologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Fosfatases de Especificidade Dupla/genética , Células Secretoras de Insulina/efeitos dos fármacos , Fosfatases da Proteína Quinase Ativada por Mitógeno/genética , Animais , Índice de Massa Corporal , Desdiferenciação Celular/efeitos dos fármacos , Fator D do Complemento/genética , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patologia , Glucose/metabolismo , Humanos , Hiperglicemia/tratamento farmacológico , Hiperglicemia/genética , Hiperglicemia/patologia , Insulina/genética , Resistência à Insulina/genética , Células Secretoras de Insulina/patologia , Camundongos , Camundongos Endogâmicos NOD
5.
Endocrinology ; 160(12): 2959-2968, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31613319

RESUMO

Longitudinal observation of pancreatic ß-cell mass (BCM) remains challenging because noninvasive techniques for determining BCM in vivo have not been established. Such observations would be useful for the monitoring of type 2 diabetes mellitus, a progressive disease involving loss of pancreatic BCM and function. An indium 111 (111In)-labeled exendin-4 derivative ([Lys12(111In-BnDTPA-Ahx)]exendin-4) targeting the glucagon-like peptide-1 receptor has been developed recently as a promising probe for quantifying the BCM noninvasively. In the present study, we used the 111In-exendin-4 single-photon emission CT/CT (SPECT/CT) technique to investigate the efficacy of DS-8500a, a novel G protein-coupled receptor-119 agonist currently under investigation for type 2 diabetes mellitus treatment in prediabetic db/db mice under dietary restriction. During the 8-week study, the treatment of mice with DS-8500a delayed and attenuated the progression of glucose intolerance compared with mice under dietary restriction alone. 111In-exendin-4 SPECT/CT of db/db mice revealed continuously decreasing radioactive isotope (RI) intensity in the pancreas during the 8-week intervention. DS-8500a attenuated this decrease and preserved pancreatic RI accumulation compared with dietary restriction alone at the end of the observation period. This result was corroborated not only by ex vivo pancreatic analysis using the [Lys12(111In-BnDTPA-Ahx)]exendin-4 probe but also by conventional histological BCM analysis. These results indicate that DS-8500a attenuates the progression of BCM loss beyond that of dietary restriction alone in prediabetic db/db mice. These results have shown that 111In-exendin-4 SPECT/CT will be useful for noninvasive longitudinal investigation of BCM in vivo.


Assuntos
Benzamidas/farmacologia , Ciclopropanos/farmacologia , Diabetes Mellitus Experimental/diagnóstico por imagem , Hipoglicemiantes/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Oxidiazóis/farmacologia , Receptores Acoplados a Proteínas-G/agonistas , Animais , Benzamidas/uso terapêutico , Ciclopropanos/uso terapêutico , Diabetes Mellitus Experimental/tratamento farmacológico , Exenatida , Hipoglicemiantes/uso terapêutico , Radioisótopos de Índio , Estudos Longitudinais , Masculino , Camundongos Endogâmicos C57BL , Oxidiazóis/uso terapêutico , Tomografia Computadorizada com Tomografia Computadorizada de Emissão de Fóton Único
6.
J Steroid Biochem Mol Biol ; 195: 105468, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31536768

RESUMO

Clinical glucocorticoid use, and diseases that produce elevated circulating glucocorticoids, promote drastic changes in body composition and reduction in whole body insulin sensitivity. Because steroid-induced diabetes is the most common form of drug-induced hyperglycemia, we investigated mechanisms underlying the recognized phenotypes associated with glucocorticoid excess. Male C57BL/6 J mice were exposed to either 100ug/mL corticosterone (cort) or vehicle in their drinking water. Body composition measurements revealed an increase in fat mass with drastically reduced lean mass during the first week (i.e., seven days) of cort exposure. Relative to the vehicle control group, mice receiving cort had a significant reduction in insulin sensitivity (measured by insulin tolerance test) five days after drug intervention. The increase in insulin resistance significantly correlated with an increase in the number of Ki-67 positive ß-cells. Moreover, the ability to switch between fuel sources in liver tissue homogenate substrate oxidation assays revealed reduced metabolic flexibility. Furthermore, metabolomics analyses revealed a decrease in liver glycolytic metabolites, suggesting reduced glucose utilization, a finding consistent with onset of systemic insulin resistance. Physical activity was reduced, while respiratory quotient was increased, in mice receiving corticosterone. The majority of metabolic changes were reversed upon cessation of the drug regimen. Collectively, we conclude that changes in body composition and tissue level substrate metabolism are key components influencing the reductions in whole body insulin sensitivity observed during glucocorticoid administration.


Assuntos
Corticosterona/farmacologia , Glucocorticoides/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Fígado/efeitos dos fármacos , Locomoção/efeitos dos fármacos , Animais , Composição Corporal/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Dieta Hiperlipídica , Glucose/metabolismo , Glicólise/efeitos dos fármacos , Resistência à Insulina , Fígado/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Peritonite/induzido quimicamente , Peritonite/metabolismo , Tioglicolatos
7.
Cell Physiol Biochem ; 53(3): 573-586, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31529929

RESUMO

BACKGROUND/AIMS: In our recent work, the importance of GSK3ß-mediated phosphorylation of presenilin-1 as crucial process to establish a Ca2+ leak in the endoplasmic reticulum and, subsequently, the pre-activation of resting mitochondrial activity in ß-cells was demonstrated. The present work is a follow-up and reveals the importance of GSK3ß-phosphorylated presenilin-1 for responsiveness of pancreatic islets and ß-cells to elevated glucose in terms of cytosolic Ca2+ spiking and insulin secretion. METHODS: Freshly isolated pancreatic islets and the two pancreatic ß-cell lines INS-1 and MIN-6 were used. Cytosolic Ca2+ was fluorometrically monitored using Fura-2/AM and cellular insulin content and secretion were measured by ELISA. RESULTS: Our data strengthened our previous findings of the existence of a presenilin-1-mediated ER-Ca2+ leak in ß-cells, since a reduction of presenilin-1 expression strongly counteracted the ER Ca2+ leak. Furthermore, our data revealed that cytosolic Ca2+ spiking upon administration of high D-glucose was delayed in onset time and strongly reduced in amplitude and frequency upon siRNA-mediated knock-down of presenilin-1 or the inhibition of GSK3ß in the pancreatic ß-cells. Moreover, glucose-triggered initial insulin secretion disappeared by depletion from presenilin-1 and inhibition of GSK3ß in the pancreatic ß-cells and isolated pancreatic islets, respectively. CONCLUSION: These data complement our previous work and demonstrate that the sensitivity of pancreatic islets and ß-cells to glucose illustrated as glucose-triggered cytosolic Ca2+ spiking and initial but not long-lasting insulin secretion crucially depends on a strong ER Ca2+ leak that is due to the phosphorylation of presenilin-1 by GSK3ß, a phenomenon that might be involved in the development of type 2 diabetes.


Assuntos
Retículo Endoplasmático/metabolismo , Glucose/farmacologia , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Presenilina-1/metabolismo , Animais , Antracenos/farmacologia , Cálcio/metabolismo , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Retículo Endoplasmático/efeitos dos fármacos , Humanos , Secreção de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/efeitos dos fármacos , Ilhotas Pancreáticas/efeitos dos fármacos , MAP Quinase Quinase 4/antagonistas & inibidores , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo
8.
Biol Pharm Bull ; 42(9): 1532-1537, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31474712

RESUMO

Glucose-stimulated insulin secretion is controlled by both exocytosis and endocytosis in pancreatic ß-cells. Although endocytosis is a fundamental step to maintain cellular responses to the secretagogue, the molecular mechanism of endocytosis remains poorly defined. We have previously shown that in response to high concentrations of glucose, guanosine 5'-diphosphate (GDP)-bound Rab27a is recruited to the plasma membrane where IQ motif-containing guanosine 5'-triphosphatase (GTPase)-activating protein 1 (IQGAP1) is expressed, and that complex formation promotes endocytosis of secretory membranes after insulin secretion. In the present study, the regulatory mechanisms of dissociation of the complex were investigated. Phosphorylation of IQGAP1 on serine (Ser)-1443, a site recognized by protein kinase Cε (PKCε), inhibited the interaction of GDP-bound Rab27a with IQGAP1 in a Cdc42-independent manner. Glucose stimulation caused a translocation of PKCε from the cytosol to the plasma membrane. In addition, glucose-induced endocytosis was inhibited by the knockdown of IQGAP1 with small interfering RNA (siRNA). However, the expression of the non-phosphorylatable or phosphomimetic form of IQGAP1 could not rescue the inhibition, suggesting that a phosphorylation-dephosphorylation cycle of IQGAP1 is required for endocytosis. These results suggest that IQGAP1 phosphorylated by PKCε promotes the dissociation of the IQGAP1-GDP-bound Rab27a complex in pancreatic ß-cells, thereby regulating endocytosis of secretory membranes following insulin secretion.


Assuntos
Endocitose , Guanosina Difosfato/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/metabolismo , Proteínas rab27 de Ligação ao GTP/metabolismo , Proteínas Ativadoras de ras GTPase/metabolismo , Animais , Sítios de Ligação , Células COS , Membrana Celular/metabolismo , Citosol/metabolismo , Glucose/farmacologia , Proteínas de Fluorescência Verde/genética , Guanosina Difosfato/genética , Imunoprecipitação , Células Secretoras de Insulina/efeitos dos fármacos , Fosforilação , Ligação Proteica , Proteínas rab27 de Ligação ao GTP/genética , Proteínas Ativadoras de ras GTPase/genética
9.
Phytother Res ; 33(10): 2765-2774, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31385371

RESUMO

The purpose of this study was to evaluate the pancreatic beta cell protective and glucose uptake enhancing effect of the water extract of Tinospora cordifolia stem (TCSE) by using rat insulinoma (RIN)-m5F cells and 3 T3-L1 adipocytes. RIN-m5F cells were stimulated with interleukin-1ß and interferon-γ, and the effect of TCSE on insulin secretion and cytokine-induced toxicity was measured by ELISA and MTT assay, respectively. The glucose uptake and protein expression were measured by fluorometry and western blotting. Antidiabetic effect of TCSE was measured using streptozotocin-induced diabetic rats. TCSE dose dependently increased cell viability and insulin secretion in RIN-m5F cells. In addition, TCSE increased both the glucose uptake and glucose transporter 4 translocation in 3 T3-L1 adipocytes via PI3K pathway. Finally, TCSE significantly lowered blood glucose and diet intake and increased body weight in streptozotocin-induced diabetic rats. The level of serum insulin and hepatic glycogen was increased, whereas the level of serum triglyceride, total cholesterol, dipeptidyl peptidase-4, and thiobarbituric acid reactive substances was decreased in TCSE-administered rats. TCSE also increased glucose transporter 4 protein expression in the adipose tissue and liver of TCSE-fed diabetic rats. Our results suggested that TCSE preserved RIN-m5F cells from cytokine-induced toxicity and enhanced glucose uptake in 3 T3-L1 adipocytes, which may regulate glucose metabolism in diabetic rats.


Assuntos
Adipócitos/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Glucose/metabolismo , Células Secretoras de Insulina/efeitos dos fármacos , Extratos Vegetais/farmacologia , Tinospora , Adipócitos/metabolismo , Animais , Células Cultivadas , Diabetes Mellitus Experimental/metabolismo , Masculino , Extratos Vegetais/uso terapêutico , Ratos , Ratos Wistar , Estreptozocina
10.
Life Sci ; 233: 116704, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31369761

RESUMO

AIMS: Doxorubicin, an anticancer drug, has a toxic effect on many tissues such as heart, pancreas, liver, kidney, and testis. The aim of current study is to investigate whether melatonin would be protective in doxorubicin-induced beta (ß) cell toxicity via HMGB1/TLR2/TLR4/MAPK/NF-қB signaling pathway. MAIN METHODS: Human pancreatic ß cell (1.1B4) was used in the present study. Four experimental groups were created as control, melatonin (10 µM), doxorubicin (2 µM) and the combination of melatonin with doxorubicin. Following 24-h treatment, Mitogen-activated protein kinase (MAPKs), Toll like receptors (TLRs) including TLR2 and TLR4, pro-and anti-apoptotic protein expression levels were determined by western blotting. Total antioxidant (TAS), oxidant status (TOS) and oxidative stress index (OSI) of the cells as well as superoxide dismutase (SOD) levels were determined. Active caspase-8 activity was measured and TUNEL staining was performed to study apoptotic pathways. Mitochondrial membrane potential (MMP), some protein expressions and F-actin distribution were analyzed. KEY FINDINGS: Doxorubicin caused to depolarize MMP, resulting in enhancing apoptosis by activation of caspase-8 via MAPKs/NF-кB pathway via elevation of TOS and decreasing TAS. Also, doxorubicin destroyed F-actin distribution and elevated TLR2 and some apoptotic proteins, including Bax. However, co-treatment of melatonin with doxorubicin could reverse depolarization of MMP and inhibition of apoptosis through MAPK/NF-кB signaling by decreasing TOS and increasing TAS. The co-treatment reversed the alternations of TLR2, TLR4, MAPKs and apoptotic protein expressions induced by doxorubicin. SIGNIFICANCE: Melatonin could be a good candidate against pancreatic ß cell toxicity-induced by doxorubicin through TLR2/TLR4/MAPK/NF-кB pathways.


Assuntos
Doxorrubicina/efeitos adversos , Células Secretoras de Insulina/efeitos dos fármacos , Melatonina/farmacologia , Substâncias Protetoras/farmacologia , Receptor 2 Toll-Like/metabolismo , Receptor 4 Toll-Like/metabolismo , Antibióticos Antineoplásicos/efeitos adversos , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Células Cultivadas , Proteína HMGB1/metabolismo , Humanos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , NF-kappa B/metabolismo , Oxidantes/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Receptor 2 Toll-Like/genética , Receptor 4 Toll-Like/genética , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
11.
Biol Res ; 52(1): 44, 2019 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-31426858

RESUMO

BACKGROUND: Free fatty acid receptor 1 (FFAR1) is G-protein coupled receptor predominantly expressed in pancreatic ß-cells that is activated by a variety of free fatty acids (FFAs). Once activated, it promotes glucose-stimulated insulin secretion (GSIS). However, increased levels of FFAs lead to lipotoxicity, inducing loss of ß-cell function. FFAR1 plays a key role in the development of type 2 diabetes (T2D), and previous studies have indicated the importance of developing anti-diabetic therapies against FFAR1, although its role in the regulation of ß-cell function remains unclear. The present study investigated the role of FFAR1 under lipotoxic conditions using palmitic acid (PA). The rat insulinoma 1 clone 832/13 (INS-1 832/13) cell line was used as a model as it physiologically resembles native pancreatic ß-cells. Key players of the insulin signaling pathway, such as mTOR, Akt, IRS-1, and the insulin receptor (INSR1ß), were selected as candidates to be analyzed under lipotoxic conditions. RESULTS: We revealed that PA-induced lipotoxicity affected GSIS in INS-1 cells and negatively modulated the activity of both IRS-1 and Akt. Reduced phosphorylation of both IRS-1 S636/639 and Akt S473 was observed, in addition to decreased expression of both INSR1ß and FFAR1. Moreover, transient knockdown of FFAR1 led to a reduction in IRS-1 mRNA expression and an increase in INSR1ß mRNA. Finally, PA affected localization of FFAR1 from the cytoplasm to the perinucleus. CONCLUSIONS: In conclusion, our study suggests a novel regulatory involvement of FFAR1 in crosstalk with mTOR-Akt and IRS-1 signaling in ß-cells under lipotoxic conditions.


Assuntos
Células Secretoras de Insulina/efeitos dos fármacos , Metabolismo dos Lipídeos/efeitos dos fármacos , Ácido Palmítico/toxicidade , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores Acoplados a Proteínas-G/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Animais , Apoptose , Linhagem Celular , Células Secretoras de Insulina/metabolismo , Ratos , Transdução de Sinais
12.
J Diabetes Res ; 2019: 2813489, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31467926

RESUMO

While the autoimmune character of T1D (type 1 diabetes) is being challenged, it is currently recognized that inflammation plays a key role in its development. We hypothesized that glucotoxicity could contribute to ß-cell mass destruction through participation in islet inflammation. We evaluated the potential of empagliflozin (EMPA) and GABA (gamma-aminobutyric acid) to protect ß-cell mass against glucotoxicity and to increase ß-cell mass after diagnosis of T1D. Empagliflozin is a SGLT2 (sodium-dependent glucose cotransporter) inhibitor which thereby blocks glucose recapture by the kidney and promotes glucose excretion in urine. GABA is an inhibitory neurotransmitter, which stimulates α-to-ß cell transdifferentiation. In streptozotocin-treated mice, empagliflozin and/or GABA were delivered for a period of five days or three weeks. As compared to untreated T1D mice, EMPA-treated T1D mice had decreased FFA (free fatty acid) levels and improved glucose homeostasis. EMPA-treated T1D mice had higher islet density, with preserved architecture, compared to T1D mice, and EMPA-treated T1D mice also differed from T1D mice by the total absence of immune cell infiltration within islets. Islets from EMPA-treated mice were also less subjected to ER (endoplasmic reticulum) stress and inflammation, as shown by qPCR analysis. Glucose homeostasis parameters and islet area/pancreas area ratio improved, as compared to diabetic controls, when T1D mice were treated for three weeks with GABA and EMPA. T1D EMPA+GABA mice had higher glucagon levels than T1D mice, without modifications of glucagon area/islet area ratios. In conclusion, empagliflozin and GABA, used in monotherapy in streptozotocin-induced diabetic mice, have positive effects on ß-cell mass preservation or proliferation through an indirect effect on islet cell inflammation and ER stress. Further research is mandatory to evaluate whether empagliflozin and GABA may be a potential therapeutic target for the protection of ß-cell mass after new-onset T1D.


Assuntos
Compostos Benzidrílicos/farmacologia , Glicemia/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Glucosídeos/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Ácido gama-Aminobutírico/farmacologia , Animais , Compostos Benzidrílicos/administração & dosagem , Glicemia/metabolismo , Contagem de Células , Proliferação de Células/efeitos dos fármacos , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/patologia , Esquema de Medicação , Quimioterapia Combinada , Intervenção Médica Precoce , Teste de Tolerância a Glucose , Glucosídeos/administração & dosagem , Injeções Intraperitoneais , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/fisiologia , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/fisiologia , Masculino , Camundongos , Estreptozocina , Fatores de Tempo , Ácido gama-Aminobutírico/administração & dosagem
13.
Adv Exp Med Biol ; 1155: 483-495, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31468425

RESUMO

The loss of pancreatic ß-cells plays a central role in the pathogenesis of both type 1 and type 2 diabetes, and many studies have been focused on ways to improve glucose homeostasis by preserving, expanding and improving the function of ß-cell. Elevated levels of free fatty acids such as palmitate might contribute to the loss of ß-cells. A marine squid, Loliolus beka has long been used as a food in Korea, China, Japan and Europe due to its tender meat and high taurine content. Here, we investigated the protective effects of a hot water extract of Loliolus beka meat (LBM) against palmitate toxicity in Ins-1 cells, a rat ß-cell line. Treatment with LBM extract protected against palmitate-induced cytotoxicity and scavenged overproduction of nitric oxide, alkyl, and hydroxyl radicals. In addition, LBM extract protected against palmitate-induced DNA damage and ß-cell dysfunction. These findings suggest that LBM protects pancreatic ß-cells from palmitate-induced damage. LBM could be a potential therapeutic functional food for diabetes.


Assuntos
Extratos Celulares/farmacologia , Dano ao DNA , Decapodiformes/química , Radicais Livres/efeitos adversos , Células Secretoras de Insulina/efeitos dos fármacos , Palmitatos/efeitos adversos , Taurina/farmacologia , Animais , Apoptose , Linhagem Celular , Diabetes Mellitus , Carne , Ratos
14.
Cleve Clin J Med ; 86(7): 494-504, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31291183

RESUMO

In view of new information, we are revising the way we think about and treat diabetes mellitus. In this new view, the insulin-producing beta cells are key, and preserving beta-cell function is paramount. These insights, together with recent outcome studies provide compelling arguments regarding treatments of choice.


Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Hiperglicemia/tratamento farmacológico , Hipoglicemiantes/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Diabetes Mellitus Tipo 2/complicações , Humanos , Hiperglicemia/etiologia , Células Secretoras de Insulina/fisiologia
15.
Life Sci ; 232: 116612, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31260687

RESUMO

AIMS: Accumulating evidence suggest that endoplasmic reticulum (ER) stress is an important mechanism underlying the development of diabetes. We have reported that sustained treatment with N-methyl-d-aspartate (NMDA) results in apoptotic ß-cell death and impairs insulin secretion. However, the molecular mechanism responsible for NMDA-induced ß-cell dysfunction remains largely obscure. Thus, this study aimed to determine whether sustained activation of NMDA receptors (NMDARs) causes ß-cell dysfunction through ER stress. MAIN METHODS: Primary mouse islets and MIN6 mouse pancreatic ß-cells were treated with NMDA for 24 h or high-glucose for 72 h. After the treatment, glucose-stimulated insulin secretion (GSIS) and the expression of ER stress markers were measured, respectively. In vivo, the expression of ER stress markers was measured in the pancreas of diabetic mice treated with or without NMDARs inhibitor Memantine. KEY FINDINGS: NMDA treatment caused an increase in the expression of ER stress markers (ATF4, CHOP, GRP78, and Xbp1s) in primary islets. While, tauroursodeoxycholic acid (TUDCA), an inhibitor of ER stress, significantly attenuated NMDA-induced ß-cell dysfunction, including the loss of glucose-stimulated insulin secretion and reduction of pancreas duodenum homeobox factor-1 (Pdx-1) mRNA expression, a transcription factor regulating insulin synthesis. Besides, NMDA-induced ER stress strongly promoted pro-inflammatory cytokines synthesis (IL-1ß and TNF-α) in ß cells. Interestingly, knockdown of CHOP attenuated ß-cell dysfunction evoked by NMDA. Furthermore, we demonstrated that blockade of NMDARs ameliorated high-glucose-induced ER stress in vitro and in vivo. SIGNIFICANCE: This study confirms that ER stress is actively involved in the activation of NMDARs-related ß-cell dysfunction.


Assuntos
Estresse do Retículo Endoplasmático/fisiologia , Células Secretoras de Insulina/metabolismo , Fator de Transcrição CHOP/metabolismo , Fator 4 Ativador da Transcrição/metabolismo , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Diabetes Mellitus Experimental/metabolismo , Modelos Animais de Doenças , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Glucose/metabolismo , Proteínas de Choque Térmico/metabolismo , Insulina/metabolismo , Secreção de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , N-Metilaspartato/farmacologia , Receptores de N-Metil-D-Aspartato/metabolismo , Transdução de Sinais , Proteína 1 de Ligação a X-Box/metabolismo
16.
Georgian Med News ; (290): 144-149, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31322533

RESUMO

There have been presented the results of the histomorphological research of the effect of the beans' thick extract (BTE) on the state of the pancreas on the model of diabetes mellitus type 2 on the background of obesity in the rats in our research. The simulation of type 2 diabetes on the background of obesity in the animals has led to the development of signs of insulin's inhibition of insulin producing apparatus - some different expressions of dystrophy and degeneration of the ß-cells. The consequence of the hyperfunction has been exhaustion and even death of ß-cells, the development of the diabetic condition. The redistribution of pancreatic islet ß-content of cells has contributed to the increase of the small islands and had a compensatory nature. The treatment of the animals by the BTE has fully prevented an excessive negative impact on revenues of carbohydrates insulin producing apparatus, because it improves the morphological status of ß-cells, reduces the part of small pancreatic islets, almost restores medium and large islets to the level of the «Intact control¼ group. The comparison drug - metformin - has a positive effect on the morphological status of the pancreatic ß-cells, but this effect is obviously not enough for improving or restoring the normal % of distribution of islets.


Assuntos
Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/terapia , Hipoglicemiantes/uso terapêutico , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Obesidade/complicações , Extratos Vegetais/uso terapêutico , Sementes/química , Animais , Tamanho Celular/efeitos dos fármacos , Diabetes Mellitus Experimental/metabolismo , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/química , Insulina , Células Secretoras de Insulina/efeitos dos fármacos , Metformina/administração & dosagem , Extratos Vegetais/química , Ratos , Açúcares
17.
Eur J Pharmacol ; 860: 172569, 2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31351037

RESUMO

Type 1 diabetes mellitus (DM) remains an intractable disease with a limited number of therapeutic options. Recently, some studies have reported the role of inflammation in DM-induced ß-cell destruction. Nilotinib hydrochloride, a tyrosine kinase inhibitor is a well-known anticancer with numerous medical benefits. In the present study, DM was induced by single I.P. injection of streptozotocin (STZ) (50 mg/kg). Daily oral nilotinib (10 mg/kg) and (20 mg/kg) for 4 weeks induced a significant attenuation of DM signs in rats and their assessed lab values. Nilotinib induced a dose-dependent significant escalation in serum insulin level with a significant reduction in blood glucose and glucagon levels. Nevertheless, biomarkers of cell injury, tissue necrosis, and apoptosis; caspase-3 were significantly reduced. Moreover, pancreatic antioxidants defenses of which; thioredoxin, superoxide dismutase (SOD) and catalase activities, reduced glutathione (GSH) concentration, and total antioxidant capacity significantly improved with a simultaneous reduction in malondialdehyde (MDA) content. Histopathologically, nilotinib treatment was associated with a minimal pancreatic injury with a significant restoration of insulin content in ß-islets. In addition, nilotinib treatment revealed a significant reduction in infiltration of macrophages in ß-cells. In conclusion: nilotinib's ameliorative impact on DM may be attributed to both nilotinib's mediated protection and preservation of pancreatic ß islets function and the improvement in serum insulin levels and hence the improvement of blood glucose.


Assuntos
Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Pirimidinas/farmacologia , Animais , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Apoptose/efeitos dos fármacos , Glicemia/metabolismo , Peso Corporal/efeitos dos fármacos , Caspase 3/metabolismo , Catalase/metabolismo , Diabetes Mellitus Experimental/sangue , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Glucagon/sangue , Glutationa/metabolismo , Insulina/metabolismo , Células Secretoras de Insulina/efeitos dos fármacos , Masculino , Malondialdeído/metabolismo , Tamanho do Órgão/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase/metabolismo
18.
J Pharmacol Exp Ther ; 370(3): 350-359, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31201216

RESUMO

Glucose-stimulated insulin secretion from pancreatic ß-cells is controlled by ATP-regulated potassium (KATP) channels composed of Kir6.2 and sulfonylurea receptor 1 (SUR1) subunits. The KATP channel-opener diazoxide is FDA-approved for treating hyperinsulinism and hypoglycemia but suffers from off-target effects on vascular KATP channels and other ion channels. The development of more specific openers would provide critically needed tool compounds for probing the therapeutic potential of Kir6.2/SUR1 activation. Here, we characterize a novel scaffold activator of Kir6.2/SUR1 that our group recently discovered in a high-throughput screen. Optimization efforts with medicinal chemistry identified key structural elements that are essential for VU0071063-dependent opening of Kir6.2/SUR1. VU0071063 has no effects on heterologously expressed Kir6.1/SUR2B channels or ductus arteriole tone, indicating it does not open vascular KATP channels. VU0071063 induces hyperpolarization of ß-cell membrane potential and inhibits insulin secretion more potently than diazoxide. VU0071063 exhibits metabolic and pharmacokinetic properties that are favorable for an in vivo probe and is brain penetrant. Administration of VU0071063 inhibits glucose-stimulated insulin secretion and glucose-lowering in mice. Taken together, these studies indicate that VU0071063 is a more potent and specific opener of Kir6.2/SUR1 than diazoxide and should be useful as an in vitro and in vivo tool compound for investigating the therapeutic potential of Kir6.2/SUR1 expressed in the pancreas and brain.


Assuntos
Ativação do Canal Iônico/efeitos dos fármacos , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Receptores Sulfonilureia/metabolismo , Xantinas/farmacologia , Xantinas/farmacocinética , Animais , Canal Arterial/efeitos dos fármacos , Canal Arterial/fisiologia , Glucose/farmacologia , Células HEK293 , Humanos , Secreção de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Camundongos , Relação Estrutura-Atividade , Vasodilatação/efeitos dos fármacos , Xantinas/química
19.
Artif Cells Nanomed Biotechnol ; 47(1): 2545-2552, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31213095

RESUMO

Tetramethylpyrazine (TMP) is a traditional Chinese medicine with anti-inflammation and immunomodulatory effects. In this context, our purpose was to investigate the associated regulatory mechanisms of TMP against lipopolysaccharide (LPS)-caused pancreatic ß cell Min6 injury. The injury of Min6 cells was induced by 10 µg/mL of LPS. Viability of Min6 cells was detected through CCK-8 assay, apoptosis process through flow cytometry, and the proteins involved in apoptosis through western blot. Insulin secretion was valued through the glucose-stimulated insulin secretion (GSIS) assay. microRNA-101 (miR-101) was measured through qRT-PCR. Mitogen-activated protein kinase phosphatase 1 (MKP-1) and signaling regulators was measured through western blot. We found that, TMP treatment effectively attenuated LPS-induced injury in Min6 cells by suppressing cell apoptosis and promoting insulin secretion. Further investigation revealed that TMP exerted protective effect through down-regulating miR-101, and MKP-1 was demonstrated as a target of miR-101. Moreover, TMP attenuated LPS-triggered inflammation by inactivating the JNK1/2 and NF-κB through the down-regulation of miR-101. In conclusion, our present study revealed that TMP alleviated LPS-induced injury in pancreatic ß-cell Min6 injury via regulation of miR-101/MKP-1 with the bluntness of JNK1/2 and NF-κB pathways.


Assuntos
Fosfatase 1 de Especificidade Dupla/metabolismo , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Lipopolissacarídeos/efeitos adversos , MicroRNAs/genética , Pirazinas/farmacologia , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Citoproteção/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Secreção de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/citologia , Camundongos , Proteína Quinase 8 Ativada por Mitógeno/metabolismo , Proteína Quinase 9 Ativada por Mitógeno/metabolismo , NF-kappa B/metabolismo , Transdução de Sinais/efeitos dos fármacos
20.
Acta Biochim Biophys Sin (Shanghai) ; 51(7): 715-722, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31168600

RESUMO

Peroxisome proliferator-activated receptor-γ (PPAR-γ) is expressed in pancreatic ß cells and is involved in insulin secretion. However, the precise mechanisms remain unclear. Calcium/calmodulin-dependent serine protein kinase (CASK), which plays a vital role in the anchoring of insulin granules on pancreatic ß cell membrane, is probably a downstream of the transcription factor PPAR-γ. The aim of the present study was to investigate the correlation among PPAR-γ, CASK and insulin secretion. We found that rosiglitazone (RSG) had a positive effect on the expression of CASK and PPAR-γ in INS-1 cells as shown by real-time polymerase chain reaction (PCR) and western blot analysis, but did not change the cellular location of CASK as shown by immunofluorescence assay. Knockdown of PPAR-γ significantly attenuated the mRNA and protein expression levels of CASK. ChIP-qPCR and luciferase assays showed that PPAR-γ bound with the Cask promoter, and promoter activity of Cask was elevated by RSG. RSG significantly enhanced the insulin secretion with potassium stimulation, but did not alter the insulin content as shown by potassium-stimulated insulin secretion assay. In addition, with RSG pretreatment, knockdown of Cask did not significantly affect the PPAR-γ activation-mediated insulin secretion. Moreover, electron microscopy demonstrated that with RSG pretreatment, silence of Cask did not change the number of vesicles anchored on the cell membranes compared with those in siCask-treated cells. Overall, the present study identifies that CASK is one of the PPAR-γ downstream targets and PPAR-γ exerts a positive effect on the expression of CASK in INS-1 cells. PPAR-γ activation increases insulin secretion independent of the upregulation of CASK.


Assuntos
Guanilato Quinases/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/metabolismo , PPAR gama/metabolismo , Animais , Linhagem Celular Tumoral , Células Cultivadas , Regulação da Expressão Gênica/efeitos dos fármacos , Guanilato Quinases/genética , Hipoglicemiantes/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Camundongos Endogâmicos C57BL , PPAR gama/agonistas , PPAR gama/genética , Interferência de RNA , Ratos , Rosiglitazona/farmacologia , Fatores de Tempo
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