Tumores neuroendócrinos pancreáticos: revisão histopatológica / Pancreatic neuroendocrine tumors: histopathological review

Introdução: Os tumores neuroendócrinos pancreáticos são considerados raros. Eles são classificados em funcionantes e não funcionantes. Objetivo: Definir e classificar tumores neuroendócrinos pancreáticos de acordo com sua avaliação histopatológica e imunoistoquímica, associado aos critérios diagnósticos. Método: Trata-se de revisão narrativa sobre publicações encontradas no PubMed, SciELO e Google Acadêmico. Resultados: Esses tumores podem ser bem ou pouco diferenciados e apresentam características microscópicas distintas. As células bem diferenciadas têm formato pequeno, núcleos uniformes redondos ou ovais, citoplasma finamente granular indicando forte capacidade secretória e mantêm a estrutura organoide. A presença de necrose tumoral, atividade mitótica aumentada e índice de Ki-67 elevado indicam alta probabilidade de neoplasia neuroendócrina. Cromogranina A e sinaptofisina favorecem o diagnóstico do bem diferenciado. Já a marcação positiva do BCL 10 em conjunto com a ausência de expressão da cromogranina A e da sinaptofisina mostram a precária diferenciação tumoral. A presença de marcação positiva para as expressões hormonais não define o tumor como funcionante. Conclusão: Houve aumento do diagnóstico de tumores neuroendócrinos pancreáticos com o uso de técnicas de imagem e a conscientização sobre a doença. A análise histopatológica com imunoistoquímica, especialmente quando há sintomas consumptivos, podem indicar o tipo do carcinoma e induzir ao mais adequado tratamento.

Introduction: Pancreatic neuroendocrine tumors are considered rare. They are classified into functioning and non-functioning. Objective: To define and classify pancreatic neuroendocrine tumors according to their histopathological and immunohistochemical evaluation, associated with diagnostic criteria. Method: This is a narrative review of publications found in PubMed, SciELO and Google Scholar. \Results: These tumors can be well or poorly differentiated and have distinct microscopic characteristics. Well-differentiated cells are small in shape, have uniform round or oval nuclei, finely granular cytoplasm indicating strong secretory capacity, and maintain the organoid structure. Presence of tumor necrosis, increased mitotic activity and high Ki-67 index indicate a high probability of neuroendocrine neoplasia. Chromogranin A and synaptophysin favor the diagnosis of well-differentiated. The positive staining of BCL 10 together with the absence of expression of chromogranin A and synaptophysin show poor tumor differentiation. The presence of positive staining for hormone expressions does not define the tumor as functioning. Conclusion: There was an increase in the diagnosis of pancreatic neuroendocrine tumors with the use of imaging techniques and awareness of the disease. Histopathological analysis with immunohistochemistry, especially when there are consuming symptoms, can indicate the type of carcinoma and lead to the most appropriate treatment.

Ethanol extract of Cissampelos sympodialis ameliorates lung tissue damage in streptozotocin-induced diabetic rats

Diabetes Mellitus (DM) is a metabolic syndrome characterized by hyperglycemia. Chronic complications affect a number of organs, including the lungs. Cissampelos sympodialis Eichl (Menispermaceae) is a plant used to treat respiratory diseases. The aim of this study was to evaluate the effect of Cissampelos sympodialis extract (CSE) in lungs of diabetic rats. We used 30 Wistar rats divided into three groups: control group (CG), diabetic group (DG) and diabetic Cissampelos sympodialis treatment group (DTG). Diabetes was induced by streptozotocin (40 mg/kg i.v.). The CSE (400 mg/kg, po) was administered daily, during four weeks, beginning one week after the onset of DM. The treatment with CSE was not able to reduce blood glucose levels after streptozotocin injection. However, it was able to decrease cholesterol and triglycerides and prevent damage on pancreatic islets morphology. Additionally, morphological alterations such as alveolar septa loss, inflammatory infiltrate and fibrosis were seen in lung tissue of rats with DM, and treatment with CSE apparently reversed these histopathological findings. Thus, CSE treatment reduced the lipid profile and restored the lung architecture of diabetic animals by a mechanism independent of glycemia and which might be associated with the reduction of the damage on the pancreatic islets.

The zinc transporter Slc39a5 controls glucose sensing and insulin secretion in pancreatic β-cells via Sirt1- and Pgc-1α-mediated regulation of Glut2

Zinc levels are high in pancreatic β-cells, and zinc is involved in the synthesis, processing and secretion of insulin in these cells. However, precisely how cellular zinc homeostasis is regulated in pancreatic β-cells is poorly understood. By screening the expression of 14 Slc39a metal importer family member genes, we found that the zinc transporter Slc39a5 is significantly down-regulated in pancreatic β-cells in diabetic db/db mice, obese ob/ob mice and high-fat diet-fed mice. Moreover, β-cell-specific Slc39a5 knockout mice have impaired insulin secretion. In addition, Slc39a5-deficient pancreatic islets have reduced glucose tolerance accompanied by reduced expression of Pgc-1α and its downstream target gene Glut2. The down-regulation of Glut2 in Slc39a5-deficient islets was rescued using agonists of Sirt1, Pgc-1α and Ppar-γ. At the mechanistic level, we found that Slc39a5-mediated zinc influx induces Glut2 expression via Sirt1-mediated Pgc-1α activation. These findings suggest that Slc39a5 may serve as a possible therapeutic target for diabetes-related conditions.

Isolation and characterization in vitro and in vivo of pancreatic islets from NOD mice / 中国实验动物学报

Objective This study was conducted to establish a stable and highly efficient method for isolation and purification of pancreatic islets from NOD mice and to evaluate their characteristics in vitro and in vivo. Methods The is-lets were isolated from mouse pancreas using modified collagenase digestion and Ficoll density gradient centrifugation. The endocrine secretory function was assessed by insulin secretion in either low or high dose glucose stimulation. To evaluate the function of the graft,body weight and blood glucose were monitored,and IVGTT was performed. In addition,to assess sur-vival of the implanted islets,Pathology using HE staining and insulin immunostaining of the graft were performed. Results The average islet yield was 116 ± 12 islets/pancreas and purity was higher than 90%. Compared with islets from Kunming mice,the islets isolated from NOD mice were poorly responsive to glucose challenge. Blood glucose levels and body weight changes of the islet-transplanted diabetic mice were significantly improved compared with the sham-operated mice. In addi-tion,blood glucose levels in vivo after an IVGTT also significantly improved. However,these improvements were only main-tained for 2 weeks. Furthermore,HE staining and immunostaining assays demonstrated that there were insulin-positive cell clusters and lymphocyte infiltration in the graft-bearing kidney. Conclusions A large number of quality islets can be isola-ted and purified from NOD mice by using the modified mouse islet isolation method, which can be used to develop thera-peutic strategies to protect transplanted islets from rejection and autoimmune attack.

Gestational diabetes induces pancreatic beta-bells apoptosis in adult rat offspring / Diabetes gestacional induce apoptosis de células beta del páncreas en crías de ratas adultas

Several studies indicated that pancreatic ß-cell death occurs in both type 1 and type 2 diabetes. This experimental study was designed to determine the effect of gestational diabetes on the ß-cells in 16-week-old rat offspring. By this aim, adult Wistar rats aged 10-12 weeks were randomly allocated in control and diabetic groups. The diabetic group received 40 mg/kg/body weight of streptozotocin (STZ) on day zero of gestation. After delivery, diabetic offspring of GDM mothers and controls at the age of 16 weeks were sacrificed and pancreases harvested and fixed. The number of ß-cells and were counted by Gomori's method staining. Also, apoptosis in pancreas tissue of diabetic and control offspring was detected by TUNEL assay. Results showed a significant reduction in ß-cell number in offspring of GDM (p<0.05). TUNEL assay showed that the number of apoptotic cells increased in GDM compared to controls (P<0.05). This study revealed that gestational diabetes induces pancreatic beta-cells apoptosis in 16-week-old rat offspring.

Varios estudios indican que la muerte de las células ß del páncreas se produce tanto en la diabetes Tipo 1 como en la Tipo 2. Este estudio experimental fue diseñado para determinar el efecto de la diabetes gestacional en las células ß del páncreas en crías de ratas de 16 semanas. Para ello, ratas Wistar adultas de entre 10-12 semanas fueron asignadas al azar en dos grupos: control y diabetes. El grupo diabetes recibió 40 mg / kg / peso corporal de estreptozotocina (STZ) en el día cero de la gestación. Después del parto, a las 16 semanas, las crías de las madres diabéticas y controles de madres con diabetes gestacional (MDG), fueron sacrificadas para la extracción del páncreas, el cual posteriormente fue fijado. Se contó el número de células ß del páncreas mediante tinción con el método de Gomori. Además, se detectó apoptosis en el tejido del páncreas de la descendencia diabética y el grupo control mediante un ensayo TUNEL. Los resultados mostraron una reducción significativa en el número de células b en la descendencia de MDG (p <0,05). El ensayo TUNEL mostró que el número de células apoptóticas aumentó en MDG en comparación con los controles (P <0,05). Este estudio reveló que la diabetes gestacional induce apoptosis de células ß en el páncreas de crías de ratas de 16 semanas.

Impairment mechanisms of acute hyperglycemia in the first-phase insulin secretion in mouse / 中国实验动物学报

Objective To clarify the impairment mechanisms of acute hyperglycemia in the first-phase insulin se-cretion in mice. Methods The mouse model of acute glucose toxicity was established by glucose infusion through jugular vein catheterization. The glucose and insulin levels were assessed by IPGTT and OGTT in the mice of acute hyperglycemia and control groups. The histology of pancreatic islets was observed using HE staining and the insulin granules and other cy-toplasmic organelles were observed by electron microscopy. Results The mouse model of acute hyperglycemia was suc-cessfully established. The IPGTT showed that the blood glucose level was decreased by 87% ( 10. 3 ± 0. 33 mmol/L vs. 19. 3 ± 1. 66 mmol/L) at 15 min in the acute hyperglycemia group compared with the control group. The OGTT showed that the blood glucose level was decreased by 85% (9. 8 ± 0. 31 mmol/L vs. 18. 16 ± 1. 01 mmol/L) at 30 min in the acute hy-perglycemia group compared with the control group. However, the peak values of insulin secretion were delayed in both IPGTT and OGTT. Insulin levels at 2. 8 and 16. 7 mmol/L glucose stimulation in the acute hyperglycemia group was de-clined by 46% and 67% than the control group, respectively (P<0. 05). Residual insulin content in isletβcells was de-clined by 49% at 2. 8 mmol/L and 94% at 16. 7 mmol/L glucose infusion than the control group (P<0. 05). The histolo-gy showed irregular structure of pancreatic islets in the acute hyperglycemia group. The electron microscopy revealed that the amount of insulin granules was decreased, and more cytoplasmic vacuoles and swollen mitochondria were observed. Conclusions Acute intravenous glucose load decreases insulin content of isletβcells, leading to decrease and delay of the first-phase insulin secretion.

Effect of aerobic exercise on pancreatic islets and explorationof their mechanism in type 2 diabetic rats / 中国比较医学杂志

Objective To explore the effect and mechanism of aerobic exercise on islet β-cells in type 2 diabetic rats.Methods Thirty healthy SPF 8-week old Wistar rats were randomly divided into control group (C, n=10), diabetic control groups (DMC) and diabetic exercise (DME) groups, 10 rats in each group, among which 7 successful rat models were used in the experiment.The diabetic rat model was established by high fat and sugar diet and i.p.injection of streptozotocin in a dose of 50 mg/kg.The rats of group DME were forced to perform 20 m/min running for 30 min, once a day, 6 days in a week, for 8 weeks.Other rats were allowed free movement.At the end of experiment, serum glucose and insulin were measured and homeostasis model assessment (HOMA) was calculated, and pancreatic tissue samples were collected for histopathological examination.The morphology and structure of pancreatic islets were observed under a digital microscope, the perimeter and area of islets were analyzed by image analysis, and shape factor of islets was calculated.The insulin content, glucokinase and ultramicro-ATPase activity in the pancreatic homogenate were determined.Results In the DME group, the perimeter and area of islets were significantly higher than the DMC group (P< 0.05), but still lower than the control group.The shape factor was significantly increased, the cell hypertrophy, vacuolization and nuclear pyknosis were markedly alleviated than those in the DMC group, the insulin content, glucokinase and the trace total ATP activity in the DME group were significantly higher than those in the DMC group (P<0.05), and the SF and HOMA were significantly changed.Conclusions Aerobic exercise can reduce the blood glucose level, improve the morphology of islets and β-cells in the type 2 diabetic rats.It may be due to increase of the activity of glucose kinase and ATP-synthase, and increased insulin sensitivity in the pancreas.

Impairment mechanisms of acute hyperglycemia in the first-phase insulin secretion in mouse / 中国实验动物学报

Objective To clarify the impairment mechanisms of acute hyperglycemia in the first-phase insulin se-cretion in mice. Methods The mouse model of acute glucose toxicity was established by glucose infusion through jugular vein catheterization. The glucose and insulin levels were assessed by IPGTT and OGTT in the mice of acute hyperglycemia and control groups. The histology of pancreatic islets was observed using HE staining and the insulin granules and other cy-toplasmic organelles were observed by electron microscopy. Results The mouse model of acute hyperglycemia was suc-cessfully established. The IPGTT showed that the blood glucose level was decreased by 87% ( 10. 3 ± 0. 33 mmol/L vs. 19. 3 ± 1. 66 mmol/L) at 15 min in the acute hyperglycemia group compared with the control group. The OGTT showed that the blood glucose level was decreased by 85% (9. 8 ± 0. 31 mmol/L vs. 18. 16 ± 1. 01 mmol/L) at 30 min in the acute hy-perglycemia group compared with the control group. However, the peak values of insulin secretion were delayed in both IPGTT and OGTT. Insulin levels at 2. 8 and 16. 7 mmol/L glucose stimulation in the acute hyperglycemia group was de-clined by 46% and 67% than the control group, respectively (P<0. 05). Residual insulin content in isletβcells was de-clined by 49% at 2. 8 mmol/L and 94% at 16. 7 mmol/L glucose infusion than the control group (P<0. 05). The histolo-gy showed irregular structure of pancreatic islets in the acute hyperglycemia group. The electron microscopy revealed that the amount of insulin granules was decreased, and more cytoplasmic vacuoles and swollen mitochondria were observed. Conclusions Acute intravenous glucose load decreases insulin content of isletβcells, leading to decrease and delay of the first-phase insulin secretion.

Neoplasia endocrina múltiple tipo 1 A propósito de un caso / Multiple endocrine neoplasia type 1 About a case

La neoplasia endocrina múltiple tipo 1 (NEM1) es un raro síndrome hereditario, autosómico dominante, clásicamente caracterizado por tumores en varias glándulas (paratiroides, adenohipófisis e islotes pancreáticos). La prevalencia del NEM1 es de aproximadamente 2 por 100.000 habitantes.El síndrome de Zollinger Ellison (SZE) es una de las 3 neoplasias que forman parte del NEM1 y corresponde al 20 a 60%. A continuación se presenta el caso clínico de un paciente de sexo masculino, 66 años de edad, con cuadro clínico de síndrome de Zollinger Ellison que, en investigación posterior, evidencia alteración funcional de las glándulas paratiroides, cumpliendo criterios diagnósticos de neoplasia endocrina múltiple tipo 1 (NEM1).(AU)

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant hereditary syndrome, classically characterized by the presence of tumors in several glands (parathyroid, anterior pituitary and pancreatic islets) The prevalence of MEN 1 is approximately 2 per 100,000 inhabitants. The Zollinger Ellison syndrome (ZES) is one of the three neoplasias that form part of the MEN 1, and corresponds to 20 to 60%. The clinical case of a 66-year-old male patient, with a clinical of Zollinger Ellison Syndrome, who in a subsequent investigation shows functional abnormality of the parathyroid glands, fulfilling diagnostic criteria of Multiple Endocrine Neoplasia type 1 (NEM1) (AU)

Sobrevida de los islotes β pancreáticos y uso de hipoglucemiantes orales: un gran reto para el médico actual / Survival of pancreatic islet β and use of oral hypoglycemic agents: a challenge for the current doctor

La célula β no sólo es capaz de fabricar y secretar la insulina, sino además, hace que dicha secreción sea en el momento justo y en la cantidad adecuada. Las elevaciones postprandiales de glucosa generan una respuesta secretora aguda en la célula β, pero en ciertas patologías como la diabética, el escenario cambia radicalmente, resultando en una disfunción caracterizada por un proceso secretor alterado y múltiples cambios fenotípicos. En estos, los nutrientes, glucosa y ácidos grasos, están elevados de forma crónica, convirtiéndose en sustancias tóxicas que pueden llevar a la muerte de la propia célula β. Por lo tanto, cualquier aproximación terapéutica a la cura de esta enfermedad debe afrontar la necesidad de reemplazar o evitar esta disminución celular, siendo imperativo mencionar el papel de los hipoglucemiantes orales como los inhibidores de la DPP-4 y los análogos de la GLP-1 en la protección contra el fracaso de la masa de células β.

The beta cell is not only able to produce and secrete insulin, but also makes this secretion is at the right time and in the right amount. Postprandial glucose elevations produce an acute secretory response in the beta cell, but in certain diseases such as diabetes mellitus, the scene changes dramatically, resulting in dysfunction, characterized by an altered secretion process and multiple phenotypic changes. In these, nutrients like glucose and fatty acids are chronically elevated, becoming toxic substances that can lead to death of the beta cell itself. Therefore, any therapeutic approach to cure this disease must face the need to replace or avoid this cell decline, it is imperative to mention the role of oral hypoglycemic agents as inhibitors of DPP-4 and analogs of the GLP-1 in protection against failure of the β cell mass.

Human pancreatic islet transplantation: an update and description of the establishment of a pancreatic islet isolation laboratory

Type 1 diabetes mellitus (T1DM) is associated with chronic complications that lead to high morbidity and mortality rates in young adults of productive age. Intensive insulin therapy has been able to reduce the likelihood of the development of chronic diabetes complications. However, this treatment is still associated with an increased incidence of hypoglycemia. In patients with “brittle T1DM”, who have severe hypoglycemia without adrenergic symptoms (hypoglycemia unawareness), islet transplantation may be a therapeutic option to restore both insulin secretion and hypoglycemic perception. The Edmonton group demonstrated that most patients who received islet infusions from more than one donor and were treated with steroid-free immunosuppressive drugs displayed a considerable decline in the initial insulin independence rates at eight years following the transplantation, but showed permanent C-peptide secretion, which facilitated glycemic control and protected patients against hypoglycemic episodes. Recently, data published by the Collaborative Islet Transplant Registry (CITR) has revealed that approximately 50% of the patients who undergo islet transplantation are insulin independent after a 3-year follow-up. Therefore, islet transplantation is able to successfully decrease plasma glucose and HbA1c levels, the occurrence of severe hypoglycemia, and improve patient quality of life. The goal of this paper was to review the human islet isolation and transplantation processes, and to describe the establishment of a human islet isolation laboratory at the Endocrine Division of the Hospital de Clínicas de Porto Alegre – Rio Grande do Sul, Brazil.

A low-protein diet during pregnancy prevents modifications in intercellular communication proteins in rat islets

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Research on isolation and purification method of pancreatic islets in mice / 器官移植

Objective To investigate a method for isolation and purification of pancreatic islets in mice,aiming to enhance the quantity and activity of pancreatic islets.Methods The pancreas were digested by retrograde common bile duct perfusion of collagenase,discontinuous density gradient centrifugation and the islets were selected and purified by manual method.After overnight culture,the pancreatic islets were incubated by static glucose-stimulated insulin secretion (GSIS)and the islet function was assessed.The subcellular structure of islet βcells was observed under transmission electron microscopy.Results Using the modified method,(200 ±20)islets were collected in each mouse with a mean diameter of (175 ±22)μm. The insulin levels in the stimulation of low (2.8 mmol/L)and high glucose (16.7 mmol/L)were (0.33 ± 0.07)and (1.36 ±0.47 )ng/(islet · 60 min),which were detected by GSIS.Insulin levels in the stimulation of high sugar is 4.12 times of those of low sugar with a statistical significance (P <0.05).It was revealed by transmission electron microscopy that the pancreatic βcell membrane and mitochondrial membrane was intact and insulin granules of different sizes could be seen within βcells.Conclusions Retrograde common bile duct perfusion of collagenase,discontinuous density gradient centrifugation combined with manual selection in vitro is a convenient,fast and stable method for isolating mouse islets,which can get pancreatic islets with relatively high output,intact cellular morphology,and good reactivity of GSIS.

Bloqueadores do sistema renina-angiotensina em ilhotas pancreáticas e fígado na obesidade induzida por dietas em camundongos / Renin-angiotensin system blockers in pancreatic islets and liver on diet-induced obesity in mice

As associações entre obesidade, doença hepática gordurosa não alcoólica (NAFLD) e diabetes mellitus tipo 2 (DM2) são bem estabelecidas, e o sistema renina-angiotensina (SRA) pode proporcionar uma ligação entre eles. O bloqueio do SRA em diferentes níveis pode estar relacionado a respostas na resistência à insulina, remodelagem do pâncreas e do fígado em um modelo de obesidade induzida por dieta. Camundongos C57BL/6 foram alimentados com uma dieta hiperlipídica (HF) durante oito semanas e depois tratados com alisquireno (50 mg/kg/dia), enalapril (30 mg/kg/dia) ou losartana (10 mg/kg/dia) por um período adicional de seis semanas. As drogas foram incorporadas na dieta. Avaliou-se a massa corporal (MC), pressão arterial, consumo e gasto energético (GE), metabolismo da glicose e lipídico, histopatologia pancreática e hepática, análise hormonal, imunohistoquímica, perfil gênico e/ou proteico do SRA no pâncreas, gliconeogênese hepática, sinalização da insulina, oxidação e acúmulo lipídico. Todos os inibidores do SRA reduziram significativamente o aumento da pressão arterial nos camundongos alimentados com dieta HF. O tratamento com enalapril, mas não alisquireno ou losartana, reduziu o ganho de MC e a ingestão alimentar; aumentou o GE; amenizou a intolerância à glicose e resistência à insulina; melhorou a massa de células alfa e beta; impediu a redução da adiponectina plasmática e restaurou a sensibilidade à leptina. Além disso, o tratamento com enalapril melhorou a expressão proteica nas ilhotas pancreáticas de Pdx1, GLUT2, ECA2 e do receptor Mas. O tratamento com losartana apresentou uma elevação na expressão proteica de AT2R no pâncreas...

The associations between obesity, NAFLD (non-alcoholic fatty liver disease) and diabetes are well established, and the renin–angiotensin system (RAS) may provide a link among them. . The blocking of the RAS at different levels may be related to responses on insulin resistance, remodeling of the pancreas and liver in a model of diet-induced obesity. Mice (C57BL/6) were fed on a high-fat (HF) diet for 8 weeks and then treated with aliskiren (50 mg/kg/day), enalapril (30 mg/kg/day) or losartan (10 mg/kg/day) for an additional 6 weeks. The drugs were incorporated into the diet. We assessed body mass (BM), blood pressure, energy intake and expenditure (EE), glucose and lipid metabolism, pancreatic and hepatic histopathology, hormonal analysis, immunohistochemistry, the expression profile of genes and/or proteins affecting pancreas RAS, hepatic gluconeogenesis, insulin signaling and lipid oxidation and accumulation. All RAS inhibitors significantly attenuated the increased blood pressure in mice fed a HF diet. Treatment with enalapril, but not aliskiren or losartan, significantly attenuated BM gain, increased EE, enhanced the glucose intolerance and insulin resistance; improved the alpha and beta cell mass; prevented the reduction of plasma adiponectin and restored leptin sensibility. Furthermore, enalapril treatment improved the protein expression of the pancreatic islet Pdx1, GLUT2, ACE2 and Mas receptors. Losartan treatment showed the greatest AT2R expression in the pancreas. In the liver, the enalapril administration improved hepatic steatosis, triglycerides and prevented the increase hepatic protein levels of PEPCK, G6Pase and GLUT2...

Anti-diabetic effects of aqueous and ethanol extract of Dendropanax morbifera Leveille in streptozotocin-induced diabetes model / 한국영양학회지

PURPOSE: Dendropanax morifera Leveille(DML) exhibits diverse biological and pharmacological activities, including anti-oxidative effect, anti-cancer activity, hepatoprotection, immunological stimulation, and bone regeneration. As part of the identification for novel functions of DML, we investigated the therapeutic effects of DML on diabetes induced by streptozotocine (STZ) treatment. METHODS: First, the four extracts including the water extract of leaf (DLW), the ethanol extract of leaf (DLE), the water extract of stem (DSW), and the ethanol extract of stem (DSE) were collected from the leaf and stem of DML using a hot water and ethanol solvent. Alterations in body weight, glucose concentration, insulin level, and pancreatic islet structure were investigated in diabetic mice after treatment with extracts of DML for 2 weeks. RESULTS: Among four extracts, the highest level of total polyphenols and total flavonoids was detected in DLW, while the lowest level of these was measured in DSE. The radical scavenging activity was also higher in DLW than in the other three extracts at the concentration of 25-100 microg/mL, although this activity was maintained at a constant level in all groups at the concentration of 500 microg/mL. Based on the results of anti-oxidant activity, DLW and DLE were selected for examination of anti-diabetic effects in a diabetes model. Body weight was gradually decreased in all STZ treated groups compared with the No treated group. However, four STZ/DML treated groups maintained a high level of body weight during 7-14 days, while the STZ/vehicle treated group showed a gradual decrease of body weight during the same period. Also, a significant decrease or increase in the concentration of glucose and insulin in the blood of the diabetes model was detected in a subset of groups, although the highest increase was detected in the STZ/DLE-200 treated group. In addition, the histological structure of pancreatic islet was significantly recovered after treatment with DLW and DLE. CONCLUSION: These results suggest that DLW and DLE may contribute to attenuation of clinical symptoms of diabetes as well as prevent the destruction of pancreatic beta-cells in STZ-induced diabetes mice.

Insulin signaling proteins in pancreatic islets of insulin-resistant rats induced by glucocorticoid

Chronic administration of glucocorticoids induces insulin resistance that is compensated by an increase in p-cell function and mass. Since insulin signaling is involved in the control of p-cell function and mass, we investigated the content of insulin pathway proteins in pancreatic islets. Rats were made insulin resistant by daily administration of dexamethasone (1mg/kg, b.w., i.p.) for 5 consecutive days (DEX), whilst control rats received saline (CTL). Circulating insulin and insulin released from isolated islets were measured by radioimmunoassay whereas the content of proteins was analyzed by Western blotting. DEX rats were hyperinsulinemic and exhibited augmented insulin secretion in response to glucose (P < 0.01). The IRa-subunit, IRS-1, Shc, AKT, p-p70S6K, ERK1/2, p-ERK1/2, and glucocorticoid receptor protein levels were similar between DEX and CTL islets. However, the IRp-subunit, p-IRp-subunit, IRS-2, PI3-K, p-AKT and p70S6K protein contents were increased in DEX islets (P < 0.05). We conclude that IRS-2 may have a major role, among the immediate substrates of the insulin receptor, to link activated receptors to downstream signaling components related to islet function and growth in this insulin-resistant rat model.

Transplante de ilhotas pancreáticas humanas: revisão da literatura e implantação de um laboratório de isolamento de ilhotas pancreáticas / Human pancreatic islet transplantation: literature review and establishment of a pancreatic islet isolation laboratory

O diabetes melito tipo 1 (DM1) está associado ao desenvolvimento de complicações crônicas de elevada morbi-mortalidade em indivíduos jovens em idade produtiva. A terapia intensiva com insulina comprovadamente diminui o aparecimento das complicações crônicas da doença. Entretanto, essa terapia ainda está associada ao aumento da incidência de hipoglicemia. Em pacientes com “DM1 lábil”, os quais apresentam hipoglicemias graves sem sintomas de alerta, o transplante de ilhotas pancreáticas humanas é uma das melhores alternativas para restaurar a secreção de insulina e a percepção da hipoglicemia. Cerca de 80% dos pacientes que receberam transplante de ilhotas de mais de um doador, submetidos ao tratamento imunossupressor do protocolo de Edmonton, adquiriram independência de insulina após 1 ano do transplante. Porém, apenas 10% destes pacientes permaneceram livres de insulina após 5 anos. Entretanto, mesmo aqueles pacientes que necessitaram utilizar novamente insulina tiveram a normalização da homeostase glicêmica e da percepção da hipoglicemia, com prevenção da hipoglicemia grave. Sendo assim, o transplante de ilhotas é capaz de diminuir os níveis de glicose plasmática e HbA1c, reduzir a ocorrência de hipoglicemias graves e melhorar a qualidade de vida dos pacientes. O objetivo deste artigo foi fazer uma breve revisão da literatura sobre o isolamento e transplante de ilhotas pancreáticas humanas e relatar a implantação de um laboratório de isolamento de ilhotas humanas no Serviço de Endocrinologia do Hospital de Clínicas de Porto Alegre.

Type 1 diabetes mellitus (DM1) is associated with chronic complications of high morbidity and mortality in young adults in a productive age. Insulin therapy has proved to reduce the chronic complications of diabetes. However, this therapy is still associated to an increased incidence of hypoglycemia. In patients with “brittle DM1”, who have severe hypoglycemia without any symptoms (hypoglycemia unawareness), the pancreatic islet transplantation is one of the best alternatives for restoring insulin secretion and hypoglycemia perception. About 80% of the patients who received islet transplantation from more than one donor, on immunosuppressive treatment with the Edmonton’s protocol, maintained insulin independence 1 year after transplantation. Nevertheless, only 10% of these patients remained free of insulin after 5 years post-transplantation. However, even those patients who returned to insulin treatment had a normalization of the glucose homeostasis and hypoglycemia perception. Therefore, islet transplantation is able to diminish plasmatic glucose and HbA1c levels, to reduce the occurrence of severe hypoglycemia, and to improve the quality of life of the patients. The purpose of this paper is to briefly review islet isolation and transplantation process, and report the establishing of a human islet isolation laboratory in the Endocrine Service at Hospital de Clínicas de Porto Alegre.

Reduced pancreatic β-cell mass is associated with decreased FoxO1 and Erk1/2 protein phosphorylation in low-protein malnourished rats

A low-protein diet leads to functional and structural pancreatic islet alterations, including islet hypotrophy. Insulin-signaling pathways are involved in several adaptive responses by pancreatic islets. We determined the levels of some insulin-signaling proteins related to pancreatic islet function and growth in malnourished rats. Adult male Wistar rats (N = 20 per group) were fed a 17 percent protein (normal-protein diet; NP) or 6 percent protein (low-protein diet; LP), for 8 weeks. At the end of this period, blood glucose and serum insulin and albumin levels were measured. The morphometric parameters of the endocrine pancreas and the content of some proteins in islet lysates were determined. The β-cell mass was significantly reduced (≅65 percent) in normoglycemic but hypoinsulinemic LP rats compared to NP rats. Associated with these alterations, a significant 30 percent reduction in insulin receptor substrate-1 and a 70 percent increase in insulin receptor substrate-2 protein content were observed in LP islets compared to NP islets. The phosphorylated serine-threonine protein kinase (pAkt)/Akt protein ratio was similar in LP and NP islets. The phosphorylated forkhead-O1 (pFoxO1)/FoxO1 protein ratio was decreased by 43 percent in LP islets compared to NP islets (P < 0.05). Finally, the ratio of phosphorylated-extracellular signal-related kinase 1/2 (pErk1/2) to total Erk1/2 protein levels was decreased by 71 percent in LP islets compared to NP islets (P < 0.05). Therefore, the reduced β-cell mass observed in LP rats is associated with the reduction of phosphorylation in mitogenic-related signals, FoxO1 and Erk proteins. The cause/effect basis of this association remains to be determined.

Isolation and purification of pig islet cells / 国际外科学杂志

Objective To establish effective method for large-scale purification of islet cells from pig pan-cress. Methods Pig pancreas tissue was digested with collagenase P followed by purification in a HCA-Fi-coil dis continuous gradient using Cobe2991 cell separator. After isolation, the islet cell yield and purity were evaluated with light microscope with DTZ staining, and the islet function assessed by insulin release as-say in vitro. Results The number of the islets coll ected from each pancreas averaged (275 000±20 895)islet equivalents (IEQ) before purification, and (230 350±26 679) IEQ after the purification with discon-tinuous gradient centrifugation. From each gram of the pancreatic tissue, (2710±229) IEQ were obtained with an average purity of (50.2±1.95) %. The purified islets responded well to high-concentration (16.7 mmol/L) glucose stimulation with a 4. 74-fold increase of insulin secretion over the basal level (3.3 mmol/L, P <0.001). Conclusion The established method can be applicable for large-scale purifi-cation of fully functional islet cells from pig pancreas.

Research on primary culture model of pancreatic islets in rats / 中国临床药理学与治疗学

AIM: To develop a simple, convenience, and inexpensive method on primary culture model of pancreatic islets in rats for the study of anti-diabetic drugs. METHODS: The pancreases of SD rats were separated from the pancreatic duct with cold Hank' s solution and picked. Then the pancreases were cut into pieces and repeatedly digested by collagenase at 37℃ for the short durations of the experiment. The isolated islets were identified by dithizone staining and the viability was evaluated by trypan blue staining. Pancreatic islets were incubated in RPMI 1640 or DMEM for 14 - 16 h, then they were transferred to new culture plates with the same medium mentioned above. Determination of insulin content of su-pernate and cell lysate and the experiment of insulin secretion by stimulation of glucose and implantation of micewith STZ-induced diabetes were used for evaluated the function of islets. RESULTS: The viability of isolated pancreatic islets was more than 95% and the purity of cultured islets was about 85% . The insulin synthesis, secretion and sensitivity of islets stimulate by glucose which were cultured in RPMI 1640 were higher than that in DMEM. The levels of blood glucose recovered to normal in type 1 diabetic mice after islets implantation. CONCLUSION : The islets got in this study have higher purity and viability with the normal biological activity for about 7 days by this method and they can be used as a cell model for the study of diabetes in vitro .