Role of extracellular vesicles in insulin resistance: Signaling pathways, bioactive substances, miRNAs, and therapeutic potential.

Extracellular vesicles are small lipid bilayer particles that resemble the structure of cells and range in size from 30 to 1000 nm. They transport a variety of physiologically active molecules, such as proteins, lipids, and miRNAs. Insulin resistance (IR) is a pathological disease in which insulin-responsive organs or components become less sensitive to insulin's physiological effects, resulting in decreased glucose metabolism in target organs such as the liver, muscle, and adipose tissue. Extracellular vesicles have received a lot of attention as essential intercellular communication mediators in the setting of IR. This review looks at extracellular vesicles' role in IR from three angles: signaling pathways, bioactive compounds, and miRNAs. Relevant publications are gathered to investigate the induction, inhibition, and bidirectional regulation of extracellular vesicles in IR, as well as their role in insulin-related illnesses. Furthermore, considering the critical function of extracellular vesicles in regulating IR, the study analyzes the practicality of employing extracellular vesicles for medication delivery and the promise of combination therapy for IR.

The C5aR1 complement receptor: A novel immunomodulator of insulin action in skeletal muscle.

The complement system constitutes an integral component of the innate immune system and plays a critical role in adaptive immunity. Activation of this system engenders the production of complement peptide fragments, including C5a, which engage G-protein coupled receptors predominantly expressed in immune-associated cells, such as neutrophils, initiating pro-inflammatory responses. Intriguingly, our investigation has unveiled the presence of C5a receptor 1 (C5aR1) expression within skeletal muscle, a key metabolic tissue and primary target of insulin. Herein, we demonstrate that C5aR1 activation by C5a in differentiated human skeletal muscle cells elicits acute suppression of insulin signalling. This suppression manifests as impaired insulin-dependent association between IRS1 and the p85 subunit of PI3-kinase, a 50% reduction in Akt phosphorylation, and a 60% decline in insulin-stimulated glucose uptake. This impairment in insulin signalling is associated with a three-fold elevation in intramyocellular diacylglycerol (DAG) levels and a two-fold increase in cytosolic calcium content, which promote PKC-mediated IRS1 inhibition via enhanced phosphorylation at IRS1 Ser1101. Significantly, our findings demonstrate that structurally diverse C5aR1 antagonists, along with genetic deletion or stable silencing of C5aR1 by 80% using short-hairpin RNA, effectively attenuate repression of insulin signalling by C5a in LHCN-M2 human skeletal myotubes. These results underscore the potential of heightened C5aR1 activation, characteristic of obesity and chronic inflammatory conditions, to detrimentally impact insulin function within skeletal muscle cells. Additionally, the study suggests that agents targeting the C5a-C5aR axis, originally devised for mitigating complement-dependent inflammatory conditions, may offer therapeutic avenues to ameliorate immune-driven insulin resistance in key peripheral metabolic tissues, including skeletal muscle.

Relationship between ethanol intake and insulin sensitivity metabolism in men with no comorbidities: a systematic review / Relación entre la ingesta de etanol y el metabolismo de la sensibilidad a la insulina en hombres sin comorbilidades: una revisión sistemática

SUMMARY: The association of alcohol consumption with type 2 diabetes has been explained by increased insulin sensitivity, anti-inflammatory effects, or effects of adiponectin. The aim was to launch a consistent relation between alcohol intake and insulin sensitivity. Several databases (MEDLINE, EMBASE, Scopus and Web of Science) were searched from 1990 to April 2020 for studies in English, using MeSH terms and text words involving to alcohol consumption and insulin sensitivity. Protocol registered on PROSPERO CRD42020205107. A total of seven original articles were analyzed, where four collected data through cross-sectional study, two papers with randomized crossover design, and one used a non-randomized study. The protective effect of moderate alcohol consumption on type 2 diabetes has been described, where an improvement on insulin levels has been shown in adults between 26.5-57 years old. Our research shows that alcohol effects on blood insulin levels could vary depending of the type of alcoholic drink ingested; and that alcohol intake increased leptin and adiponectin levels, suggesting that alcohol consumption may increase glucose catabolism promoting insulin sensitivity via leptin and adiponectin. However, original studies should consider time of exposure, age, dosage, ethnicity, and alcohol type in order to conclude right affirmations.

RESUMEN: La asociación del consumo de alcohol con la diabetes tipo 2 se ha explicado por una mayor sensibilidad a la insulina, efectos antiinflamatorios o efectos de la adiponectina. El objetivo fue establecer una relación coherente entre la ingesta de alcohol y la sensibilidad a la insulina. Se realizaron búsquedas en varias bases de datos (MEDLINE, EMBASE, Scopus y Web of Science) desde 1990 hasta abril de 2020 en busca de estudios en inglés, utilizando términos MeSH y palabras de textos relacionadas con el consumo de alcohol y la sensibilidad a la insulina. Protocolo registrado en PROSPERO CRD42020205107. Se analizaron un total de siete artículos originales, donde cuatro recopilaron datos a través de un estudio transversal, dos artículos con diseño cruzado aleatorizado y uno utilizó un estudio no aleatorizado. Se ha descrito el efecto protector del consumo moderado de alcohol sobre la diabetes tipo 2, donde se ha demostrado una mejora de los niveles de insulina en adultos entre 26,5 y 57 años. Nuestra investigación muestra que los efectos del alcohol sobre los niveles de insulina en sangre pueden variar según el tipo de bebida alcohólica ingerida; y que la ingesta de alcohol aumenta los niveles de leptina y adiponectina, lo que sugiere que el consumo de alcohol puede aumentar el catabolismo de la glucosa promoviendo la sensibilidad a la insulina a través de la leptina y la adiponectina. Sin embargo, los estudios originales deben considerar el tiempo de exposición, la edad, la dosis, el origen étnico y el tipo de alcohol para concluir afirmaciones correctas.

El páncreas en guerra. Diabetes tipo 1 / No disponible

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Ferriman-Gallwey score correlates with obesity and insulin levels in polycystic ovary syndrome: an observational study / Correlação da escala de Ferriman-Gallwey com a obesidade e níveis de insulina na síndrome dos ovários policísticos: um estudo observacional

BACKGROUND: The Polycystic Ovary Syndrome (PCOS) is the most common endocrinopathy and one of the main causes of infertility in women. OBJECTIVES: This study aimed to evaluate the correlation between clinical hyperandrogenism assessed by modified Ferriman-Gallwey (F-G) score and metabolic parameters in Polycystic Ovary Syndrome women. METHODS: This observational study included fifty Polycystic Ovary Syndrome subjects. Detailed information about body mass index (BMI) and abdominal circumference (AC) were obtained from each subject. F-G score was applied to assess hirsutism through visual method. Serum levels of insulin, glucose and testosterone were measured. RESULTS: A positive correlation was observed between F-G score with body mass index, abdominal circumference and insulin. CONCLUSIONS: Obesity, mainly abdominal adipose tissue, and insulin levels correlate with hyperandrogenism in Polycystic Ovary Syndrome women, analyzed by F-G score. F-G score could be a marker to evaluate metabolic disorders in Polycystic Ovary Syndrome women.

JUSTIFICATIVA: A Síndrome dos Ovários Policísticos (SOP) é a endocrinopatia mais comum e uma das principais causas de infertilidade em mulheres. OBJETIVOS: O presente estudo teve como objetivo avaliar a correlação entre hiperandrogenismo clínico, avaliado pela escala de Ferriman-Gallwey (FG) modificada e parâmetros metabólicos em mulheres com a Síndrome dos Ovários Policísticos. MÉTODOS: Este estudo observacional incluiu cinquenta mulheres com Síndrome dos Ovários Policísticos. Informações detalhadas sobre o índice de massa corporal (IMC) e circunferência abdominal (CA) foram obtidas de cada participante. A escala FG foi aplicada para avaliar o hirsutismo através do método visual. Níveis séricos de insulina, glicose e testosterona foram também avaliados. RESULTADOS: Observou-se uma correlação positiva entre a escala FG e o índice de massa corporal, circunferência abdominal e insulina. CONCLUSÕES: A obesidade, principalmente o tecido adiposo abdominal, e os níveis de insulina se correlacionam com hiperandrogenismo em mulheres com Síndrome dos Ovários Policísticos, analisados por meio da escala FG. Desta forma, esta escala poderia ser um marcador para avaliar distúrbios metabólicos em mulheres com Síndrome dos Ovários Policísticos.

Effects of resveratrol on the insulin signaling pathway of obese mice

The present study was conducted to investigate the effects of resveratrol on the insulin signaling pathway in the liver of obese mice. To accomplish this, we administered resveratrol to high fat diet-induced obese mice and examined the levels of protein phosphorylation in the liver using an antibody array. The phosphorylation levels of 10 proteins were decreased in the high fat diet and resveratrol (HFR) fed group relative to the levels in the high fat diet (HF) fed group. In contrast, the phosphorylation levels of more than 20 proteins were increased in the HFR group when compared with the levels of proteins in the HF group. Specifically, the phosphorylation levels of Akt (The308, Tyr326, Ser473) were restored to normal by resveratrol when compared with the levels in the HF group. In addition, the phosphorylation levels of IRS-1 (Ser636/Ser639), PI-3K p85-subunit alpha/gamma(Tyr467/Tyr199), PDK1 (Ser241), GSK-3alpha (S21) and GSK-3 (Ser9), which are involved in the insulin signaling pathway, were decreased in the HF group, whereas the levels were restored to normal in the HFR group. Overall, the results show that resveratrol restores the phosphorylation levels of proteins involved in the insulin signaling pathway, which were decreased by a high fat diet.

Taurine ameliorates hyperglycemia and dyslipidemia by reducing insulin resistance and leptin level in Otsuka Long-Evans Tokushima fatty (OLETF) rats with long-term diabetes

This study aimed to determine whether taurine supplementation improves metabolic disturbances and diabetic complications in an animal model for type 2 diabetes. We investigated whether taurine has therapeutic effects on glucose metabolism, lipid metabolism, and diabetic complications in Otsuka Long-Evans Tokushima fatty (OLETF) rats with long-term duration of diabetes. Fourteen 50-week-old OLETF rats with chronic diabetes were fed a diet supplemented with taurine (2%) or a non-supplemented control diet for 12 weeks. Taurine reduced blood glucose levels over 12 weeks, and improved OGTT outcomes at 6 weeks after taurine supplementation, in OLETF rats. Taurine significantly reduced insulin resistance but did not improve beta-cell function or islet mass. After 12 weeks, taurine significantly decreased serum levels of lipids such as triglyceride, cholesterol, high density lipoprotein cholesterol, and low density lipoprotein cholesterol. Taurine significantly reduced serum leptin, but not adiponectin levels. However, taurine had no therapeutic effect on damaged tissues. Taurine ameliorated hyperglycemia and dyslipidemia, at least in part, by improving insulin sensitivity and leptin modulation in OLETF rats with long-term diabetes. Additional study is needed to investigate whether taurine has the same beneficial effects in human diabetic patients.

Impacto de la insulina en el deterioro cognitivo: [revisión] / Impact of insulin of cognitive impairment: [review]

La diabetes, el sobrepeso y la obesidad son enfermedades crónicas no transmisibles que se incrementan paulatinamente por desórdenes alimenticios, disminución de la actividad física y trastornos endocrinológicos. La insulina además de regular el metabolismo de la glucosa es un neuromodulador del sistema nervioso central, interviniendo en los procesos de funcionamiento neuronal y sus alteraciones afectan el desempeño cognitivo. Diversas patologías como el síndrome de resistencia a la insulina, hiperinsulinemia y la diabetes incrementan la respuesta inflamatoria sistémica y el estrés oxidativo. En el presente artículo revisamos la fisiopatología de la insulina y el deterioro cognitivo, sus péptidos relacionados y el rol que tiene la dieta y las enfermedades asociadas.

Diabetes, overweight and obesity are chronic non communicable diseases that are increased gradually by eating disorders, decreased physical activity and endocrinological disorders. Insulin besides regulate glucose is a neuromodulator of the central nervous system is involved in processes of neuronal function and its alterations affect cognitive performance. Pathologies such as the syndrome of insulin resistance, hyperinsulinemia and diabetes increase the systemic inflammatory response and oxidative stress. This paper reviews the pathophysiology of insulin and cognitive decline, related peptides and role of diet and associated diseases.

Diferenciação de células-tronco embrionárias murinas (mESCs) em células produtoras de insulina (IPCs) e caracterização funcional do gene Purkinje cell protein 4 (Pcp4) neste processo / Differentiation of murine embryonic stem cells (mESCs) into insulin-producing cells (IPCs) and functional characterization of the Purkinje Cell Protein 4 (Pcp4) gene in this process

Fontes alternativas de células ß têm sido estudadas para o tratamento de Diabetes mellitus tipo 1, dentre as quais a mais promissora consiste das células-tronco diferenciadas em células produtoras de insulina (IPCs). Alguns trabalhos demonstram a capacidade de células-tronco embrionárias murinas (mESCs) de formarem estruturas semelhantes a ilhotas pancreáticas, porém, os níveis de produção de insulina são insuficientes para a reversão do diabetes em camundongos diabetizados. Este trabalho visa desenvolver um protocolo adequado para geração de IPCs e contribuir para a identificação e caracterização funcional de novos genes associados à organogênese pancreática. Logo no início da diferenciação das mESCs em IPCs, foi possível verificar o surgimento de células progenitoras, evidenciado pela expressão de marcadores importantes da diferenciação beta-pancreática. Ao final do processo de diferenciação in vitro, ocorreu a formação de agrupamentos (clusters) semelhantes a ilhotas, corando positivamente por ditizona, que é específica para células ß-pancreáticas. Para avaliar seu potencial in vivo, estes clusters foram microencapsulados em Biodritina® e transplantados em camundongos diabetizados. Apesar dos níveis de insulina produzidos não serem suficientes para estabelecer a normoglicemia, os animais tratados com IPCs apresentaram melhores condições, quando comparados ao grupo controle, tendo melhor controle glicêmico, ganho de massa corpórea e melhor aparência da pelagem, na ausência de apatia. Além disso, análise dos clusters transplantados nestes animais indicou aumento da expressão de genes relacionados à maturação das células ß. Porém, quando estes clusters foram microencapsuladas em Bioprotect® e submetidos à maturação in vivo em animais normais, ocorreu um aumento drástico na expressão de todos os genes analisados, indicando sua maturação completa em células beta. O transplante destas células completamente maturadas em animais diabetizados, tornou-os normoglicêmicos e capazes de responder ao teste de tolerância à glicose (OGTT) de forma semelhante aos animais normais. A segunda parte do trabalho visou analisar genes diferencialmente expressos identificados em estudo anterior do nosso grupo, comparando, através de DNA microarray, mESCs indiferenciadas e diferenciadas em IPCs. Um dos genes diferencialmente expressos é aquele que codifica para a Purkinge cell protein 4 (Pcp4), sendo 3.700 vezes mais expresso em IPCs. Para investigar o possível papel do gene Pcp4 em células ß e no processo de diferenciação ß-pancreática, adotou-se o enfoque de genômica funcional, superexpressando e inibindo sua expressão em células MIN-6 e mESCs. Apesar da alteração na expressão de Pcp4 em células MIN-6 não ter interferido de forma expressiva na expressão dos genes analisados, quando inibido, modificou o perfil da curva de crescimento celular, aumentando seu tempo de dobramento de forma significativa e diminuindo da viabilidade celular em ensaios de indução de apoptose. Já na diferenciação de mESCs em IPCs, a superexpressão de Pcp4 interferiu de forma positiva apresentando uma tendência a aumentar a expressão dos genes relacionado à diferenciaçãoß-pancreática. Concluindo, desenvolvemos um novo protocolo de diferenciação de mESCs em IPCs as quais foram capazes de reverter o diabetes em camundongos diabetizados e descrevemos, pela primeira vez, o gene Pcp4 como sendo expresso em células ß-pancreáticas, podendo estar relacionado à manutenção da viabilidade celular e maturação destas células

New cellular sources for type 1 Diabetes mellitus treatment have been previously investigated, the most promising of which seems to be the insulin producing cells (IPCs), obtained by stem cells differentiation. Some reports show that murine embryonic stem cells (mESCs) are able to form islet-like structures, however, their insulin production is insufficient to render diabetic mice normoglycemic. This work aims at developing an adequate protocol for generation of IPCs and searching for new genes which could be involved in the pancreatic organogenesis process. Early on during mESCs differentiation into IPCs, we observed the presence of progenitor cells, which were able to express pancreatic ß-cell markers. At the end of the differentiation process, the islet-like clusters positively stained for the insulin-specific dithizone. These clusters were microencapsulated in Biodritin® microcapsules, and then transplanted into diabetized mice. Although the levels of insulin production were insufficient for the animals to achieve normoglycemia, those which received IPCs displayed improved conditions, when compared to the control group, as judged by a better glycemic control, body weight gain and healthy fur appearance, in the absence of apathy. In addition, when these transplantated clusters were retrieved, high levels of expression of the genes related to ß-cell maturation were detected. IPCs were also microencapsulated in Bioprotect® and subjected to in vivo maturation in normal animals. A dramatic increase of the analyzed genes expression was observed, indicating complete maturation of the differentiated cells. When these cells were transplanted into diabetized mice, these animals achieved normoglycemia and were able to display glucose tolerance test (OGTT) response very similar to that of normal mice. In the second part of this work, we analyzed upregulated genes described in previous work from our group, comparing undifferentiated mESCs to IPCs using a microarray platform. One of these genes is that coding for the Purkinje cell protein 4 (Pcp4), which is 3,700 more expressed than in undifferentiated mESC cells. We adopted a functional genomics approach to investigate the role played by the Pcp4 gene in ß-cells and in ß-cell differentiation, by inducing overexpression and knocking down this gene in MIN-6 and mESC cells. Although the differential expression of Pcp4 in MIN-6 was not able to interfere with the expression of the genes analyzed, we observed different cell growth rates, with increased doubling time and decreased cell viability when its expression was knocked down. In addition, overexpression of Pcp4 in mESCs subjected to differentiation into IPCs apparently increases the expression of genes related to ß-cell differentiation. In conclusion, we developed a new protocol for ESCs differentiation into IPCs, which is able to revert diabetes in diabetized mice, and we also describe here, for the first time, the Pcp4 gene as being expressed in pancreatic ß-cells and possibly being related to maintenance of cell viability and ß-cell maturation

Cross-talk das vias de sinalização de insulina e angiotensina II: implicações com a associação entre diabetes mellitus e hipertensão arterial e doença cardiovascular / Insulin and angiotensin II signaling pathways cross-talk: implications with the association between diabetes mellitus, arterial hypertension and cardiovascular disease

Insulina (Ins) e Angiotensina II (AII) são fundamentais no controle de dois sistemas vitais e inter-relacionados: o metabólico e o cardiocirculatório, respectivamente. A disfunção de qualquer um desses hormônios pode levar ao desenvolvimento de duas doenças de alta prevalência, muitas vezes concomitantes e, talvez, com fisiopatologia integrada - diabetes mellitus (DM) e hipertensão arterial (HA). Vários estudos mostram que os sistemas de sinalização intracelular de Ins e AII estão conectados e influenciam um ao outro. Esta comunicação molecular ocorre em diferentes etapas da sinalização celular e é importante para vários fenômenos fisiológicos, desde o desenvolvimento de hipertrofia cardíaca e aquisição de energia pelo coração, até a ação de drogas anti-hipertensivas. No nível extracelular, a enzima de conversão de angiotensina regula a síntese de AII e o acúmulo de bradicinina, e ambos desempenham papel regulador sobre a sinalização de Ins. No nível intracelular, a interação dos sinais de Ins e AII ocorre em dois momentos distintos. Inicialmente, em etapas mais precoces da sinalização celular, a AII, atuando através da cascata JAK-2/IRS-1/PI3-quinase, JNK e ERK, provoca a fosforilação em serina e a conseqüente inibição de elementos-chave da via de sinalização da Ins. Finalmente, a AII induz a expressão da proteína regulatória SOCS-3, que impõe um controle mais tardio sobre o sinal de Ins. Esta revisão discute os avanços mais recentes neste campo e a importância dessa interação molecular na fisiopatologia e na associação clínica de DM e HA.

Insulin (Ins) and angiotensin II (AII) play pivotal roles in the control of two vital and closely related systems: the metabolic and the circulatory, respectively. A failure in the proper action of each of these hormones results, to a variable degree, in the development of two highly prevalent and commonly overlapping diseases - diabetes mellitus (DM) and hypertension (AH). In recent years, a series of studies has revealed a tight connection between the signal transduction pathways that mediate Ins and AII actions in target tissues. This molecular cross-talk occurs at multiple levels and plays an important role in phenomena that range from the action of anti-hypertensive drugs to cardiac hypertrophy and energy acquisition by the heart. At the extracellular level, the angiotensin-converting enzyme controls AII synthesis but also interferes with Ins signaling through the proper regulation of AII and the accumulation of bradykinin. At an early intracellular level, AII, acting through JAK-2/IRS-1/PI3-kinase, JNK and ERK, may induce the serine phosphorylation and inhibition of key elements of the Ins-signaling pathway. Finally, by inducing the expression of the regulatory protein SOCS-3, AII may impose a late control on the Ins signal. This review will focus on the main advances obtained in this field and will discuss the implications of this molecular cross-talk in the common clinical association between DM and AH.

Insulin 3-like hormone and its role in epididymo-testicular descent

PURPOSE: The role of insulin 3-like (Insl3) hormone signaling in the testicular descent process has been demonstrated. The purpose of the present study was to evaluate epididymal development in Insl3-deficient mice. MATERIALS AND METHODS: Heterozygous and homozygous Insl3 mutants of a mixed CD1 X 129/Sv genetic background were generated by breeding Insl3-/- females with Insl3+/- males, and their genotypes were determined by polymerase chain reaction. On the first postnatal day, newborn males were sacrificed, embedded in paraffin, and cut in 4 µm sections. Sections were stained with hematoxylin/eosin and immunoreacted with anti-± actin antibody. RESULTS: An analysis of stained sections indicated an arrest in the development of the epididymis in all homozygous mice. The cauda and corpus of the epididymis were undersized. Compared to the heterozygous epididymis, the homozygous epididymis had fewer peritubular layers and dwarfish musculature. We confirmed this with immunostaining with monoclonal antibodies against ± -smooth muscle actin. CONCLUSION: Defective development of the smooth musculature in the epididymis of Insl3 homozygous mutant mice, combined with its high intraabdominal undescended position, supports previous observations regarding the importance of intact epididymis morphology and function for descent of the epididymo-testicular unit.

Avaliação morfológica e dos mecanismos de mobilização de Ca2+ pela glicose e acetilcolina em células pancreáticas humanas / Morphologic evaluation and Ca2+ mobilization by glicose and acetylcholine in human pancreatic cells

OBJETIVOS: Avaliar a morfologia das organelas e do citoesqueleto em células pancreáticas humanas cultivadas e a mobilização de Ca2+ em resposta à glicose e ACh por medidas fluorimétricas. MATERIAL E MÉTODOS: As células foram semeadas em lamínulas, fixadas e marcadas com uma combinação de fluoróforos: o núcleo foi corado com DAPI e as mitocôndrias, com Mytotracker Red. Foram utilizados faloidina e anticorpos secundários conjugados com Alexa Fluor verde e vermelho fluorescentes (488 e 594) para identificar proteína actina F e receptor muscarínico tipo M3, respectivamente. Para estudar a mobilização de Ca2+, as células foram incubadas com fura-2/AM. RESULTADOS: As células pancreáticas humanas apresentaram morfologia preservada com grande quantidade de mitocôndrias. Na região de maior densidade celular, evidenciou-se as pseudo-ilhotas e os receptores muscarínicos M3. Por meio da elevação da [Ca2+]c, devido à ação da glicose e ACh, mostrou-se preservação da capacidade responsiva a esses estímulos e foi dependente de concentração desses agonistas. A glicose promoveu uma resposta sustentada e a ACh induziu uma resposta bifásica. CONCLUSÃO: As células pancreáticas humanas cultivadas conservaram sua morfologia. A mobilização de Ca2+ em resposta à glicose e a ACh confirma a sua funcionalidade. Os receptores muscarínicos M3 estão presentes nessas células.

AIMS: The proposal of this study was to analyze morphology of the organelles and cytoskeleton in human pancreatic cells cultured and the mobilization of the cytosolic calcium ([Ca2+]c) in response to glucose and ACh by fluorimetry method. MATERIAL AND METHODS: The cells were plated on glass coverslips, fixed and stained with a combination of fluorophores: the nuclei were stained with DAPI and mitochondria with Mytotracker Red. It was used phalloidin and the secondary antibodies Alexa Fluor conjugated green and red-fluorescent (488 and 594) to identify the protein cell actin F and type M3 muscarinic receptor respectively. The cells also were loaded with fura-2/AM to study Ca2+ mobilization. RESULTS: The human pancreatic cells show characteristics morphologically preserved with great amount of mitochondria. In region major cell density was evidenced pseudo-islets and type M3 muscarinic receptors. Through increase of [Ca2+]c due to action of glucose and ACh were shown that the cellsÆ capacity to respond to these stimuli were conserved. The elevation of the [Ca2+]c depended on concentration by glucose-induced promoting sustained phase and ACh-induced a biphasic response. CONCLUSION: The morphologic characteristics of human pancreatic cells cultured were preserved. The Ca2+ mobilization in response to glucose and ACh confirmed its functionality. The expression of the M3 muscarinic receptors in human pancreatic cell cultured was demonstrated.

Exercise type and muscle fiber specific induction of caveolin-1 expression for insulin sensitivity of skeletal muscle

It is well known that exercise can have beneficial effects on insulin resistance by activation of glucose transporter. Following up our previous report that caveolin-1 plays an important role in glucose uptake in L6 skeletal muscle cells, we examined whether exercise alters the expression of caveolin-1, and whether exercise-caused changes are muscle fiber and exercise type specific. Fifity week-old Sprague Dawley (SD) rats were trained to climb a ladder and treadmill for 8 weeks and their soleus muscles (SOL) and extensor digitorum longus muscles (EDL) were removed after the last bout of exercise and compared with those from non-exercised animals. We found that the expression of insulin related proteins and caveolins did not change in SOL muscles after exercise. However, in EDL muscles, the expression of insulin receptor beta (IRbeta) and glucose transporter-4 (GLUT-4) as well as phosphorylation of AKT and AMPK increased with resistance exercise but not with aerobic exercise. Also, caveolin-1 and caveolin-3 increased along with insulin related proteins only in EDL muscles by resistance exercise. These results suggest that upregulation of caveolin-1 in the skeletal muscle is fiber specific and exercise type specific, implicating the requirement of the specific mode of exercise to improve insulin sensitivity.

Crecimiento intrauterino restringido: ¿problema de definición o de contenido? / Restricted intrauterine growth: a problem of definition or content?

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Secreçäo da insulina: efeito autócrito da insulina e modulaçäo por ácidos graxos / Insulin secretion: insulin autocrinous effect and modulation by fatty acids

A insulina exerce um papel central na regulação da homeostase da glicose e atua de maneira coordenada em eventos celulares que regulam os efeitos metabólicos e de crescimento. A sub-unidade 13 do receptor de insulina possui atividade tirosina quinase intrínseca. A autofosforilação do receptor, induzida pela insulina, resulta na fosforilação de substratos protéicos intracelulares, como o substrato-l do receptor de insulina (IRS-1). O IRS-1 fosforilado associa-se a domínios SH2 e SH3 da enzima PI 3-quinase, transmitindo, desta maneira, o sinal insulínico. A insulina parece exercer feedback positivo na sua secreção, pela interação com seu receptor em células B pancreáticas. Alterações nos mecanismos moleculares da via de sinalização insulínica sugerem uma associação entre resistência à insulina e diminuição da secreção deste hormônio, semelhante ao observado em diabetes mellitus tipo 2. Uma das anormalidades associadas à resistência à insulina é a hiperlipidemia. O aumento do pool de ácidos graxos livres circulantes pode modular a atividade de enzimas e de proteínas que participam na exocitose da insulina. Essa revisão descreve também os possíveis mecanismos de modulação da secreção de insulina pelos ácidos graxos em ilhotas pancreáticas.

Gordura visceral, subcutânea ou intramuscular: onde está o problema? / Visceral, subcutaneous or intramuscular fat: where is the problem?

O tecido adiposo é um órgão dinâmico que secreta vários fatores, denominados adipocinas. Eles estão relacionados, direta ou indiretamente, em processos que contribuem na aterosclerose, hipertensão arterial, resistência insulínica e diabetes tipo 2, dislipidemias, ou seja, representam o elo entre adiposidade, síndrome metabólica e doenças cardiovasculares. Na obesidade, os depósitos de gordura corporal estão aumentados, apresentando conseqüente elevação na expressão e secreção das adipocinas, proporcionalmente ao maior volume das células adiposas. Os diferentes depósitos de gordura, a saber: tecidos adiposos visceral, subcutâneo abdominal, subcutâneo glúteo-femural e intramuscular, possuem grau metabólico e endócrino diferenciados, podendo estar, portanto, interferindo de forma específica nos processos inerentes à adiposidade corporal em obesos e diabéticos. O presente trabalho visa discutir sobre o papel endócrino e metabólico de cada compartimento de tecido adiposo, de modo a avaliar a contribuição dos mesmos nas complicações inerentes à obesidade.

Chronotopic and blood pressure response to oral glucose load in Chagas' disease

Neste estudo foram avaliados 16 pacientes chagásicos e 28 indivíduos normais, em termos de respostas pressórica e cronotrópica pós sobrecarga oral de glicose. Essas respostas foram apreciadas através das medidas de pressäo arterial e frequência de pulso. A resposta cardiovascular foi correlacionada com os níveis de insulinemia e glicemia. O experimento detectou um subgrupo de chagásicos (N=8) com padräo hipoinsulinêmico com atividades cronotrópicas e pressórica deprimidas quando comparadas ao grupo controle, o que indica um possível déficit nas atividades insulínicas e/ou disfunçäo autonômica precoce neste subgrupo

Métodos de medición de la sensibilidad a la insulina y otros parámetros relacionados: correlación con la clínica / Methods to measure insulin sensitivity in the clinical setting: an update

Insulin resistance appears in several pathological conditions but unfortunately a simple, low cost, reproducible and easy to perform method to measure it isstill lacking. This method should resemble as closely as possible the physiological response to insulin and should be able to evaluate the sensitivity to the hormone of different tissues and systems. We herein analyze the factors that modify basal insulin determinations and the different methods available to measure insulin resistance.

Tizolidinadionas: una nueva familia de Hipoglicemiantes Orales / Thizolidinediones: a new family of oral hypoglycemic agents

A partir de un estudio de la literatura más actualizada se presenta una revisión bibliográfica de una nueva serie de compuestos conocidos como tiazolidinadionas. Se consultaron las bases de datos Medline (1989-8/96), Excerpta Médica (1990-7/96), Predicast (1992-6/96), Medical Research Division (1991) y Life Science (1993-95). Se resumen los resultados obtenidos en los estudios preclínicos y clínicos de los derivados de esta familia conocidos hasta el momento