Fração não edulcorante da stevia rebaudiana estimula secreção de insulina, ativa glicólise e melhora a tolerância à glicose

Orientador: Prof.ª Dr.ª Cecília Edna Mareze da CostaDissertação (mestrado em Ciências Fisiológicas)--Universidade Estadual de Maringá, 2017Resumo: A Stevia rebaudiana além de ser uma fonte de adoçantes não calóricos é, também, importante fonte de moléculas bioativas. Este trabalho investigou, primeiramente, o efeito do extrato etanólico (EET) e das frações clorofórmica (FCL) e de acetato de etila (FAE), obtidas das folhas da stevia, na secreção de insulina de ilhotas isoladas de ratos. Os resultados obtidos nestes estudos iniciais e o fato da FAE ser rica em compostos fenólicos, apresentar alto conteúdo protéico e ser praticamente isenta de glicosídeos edulcorantes, determinou que esta fosse a fração selecionada para os testes subsequentes que foram realizados neste trabalho. Este é o primeiro trabalho que avalia os efeitos de uma fração de stevia com tais características na secreção de insulina e possíveis mecanismos, no metabolismo da glicose em hepatócitos isolados e na tolerância à glicose in vivo. Os resultados obtidos com as ilhotas isoladas de ratos normais mostraram que a FAE estimula a secreção de insulina apenas na presença de concentrações altas de glicose e de forma cálcio dependente, por mecanismos não totalmente esclarecidos, mas que parecem envolver canais de potássio sensíveis a ATP e receptores colinérgicos M3 e adrenérgicos a2. No estudo com hepatócitos, isolados de ratos em estado alimentado, foi observado que FAE estimula a glicólise, não interfere na glicogenólise e causa aumento na razão NADH/NAD+. O teste oral de tolerância à glicose mostrou que a FAE melhora a tolerância à glicoseAbstract: Stevia rebaudiana, besides being a source of non-caloric sweeteners, is also an important source of bioactive molecules. This work first investigated the effect of ethanolic extract (ETE), chloroform (CLF) and ethyl acetate (EAF) fractions, obtained from stevia leaves, on the insulin secretion of islets isolated from rats. The results obtained from this study and the fact that FAE is rich in phenolic compounds, present high protein content and practically free of sweetening glycosides, determined that this was the fraction selected for the subsequent tests performed in this work. This is the first work to evaluate the effects of a stevia fraction with such characteristics on insulin secretion mechanisms, glucose metabolism in isolated hepatocytes, and in vivo glucose tolerance. The results obtained with islets isolated from normal rats showed that FAE stimulates insulin secretion only in the presence of high glucose and calcium dependent concentrations, by mechanisms not fully understood, but which seem to involve ATP-sensitive potassium channels and M3 cholinergic receptors and a2 adrenergic receptors. In the study with hepatocytes isolated from fed rats, it was observed that FAE stimulates glycolysis, does not interfere with glycogenolysis, and causes an increase in the NADH/NAD+ ratio. The oral glucose tolerance test has shown that FAE improves glucose toleranc

COVID-19 During Development: A Matter of Concern

A new infectious disease, COVID-19, has spread around the world. The most common symptoms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are cough and fever, but severe cases can develop acute respiratory distress syndrome. The main receptor for SARS-CoV-2 in human tissue is angiotensin-converting enzyme 2, and the lungs, heart, and kidneys are the most affected organs. Besides the inflammatory process and tissue damage, the presence of a cytokine "storm" has been related to a higher mortality rate. Other infectious viral diseases, such as Zika, chikungunya, and influenza, were associated with complications in pregnant women, such as growth restriction, malformation, preterm birth, low birth weight, miscarriage, and death, although they can also cause developmental disorders in infants and adolescents. Evidence points out that stressors during pregnancy and infancy may lead to the development of obesity, diabetes, and cardiovascular disease. Therefore, we hypothesize that COVID-19 infection during the critical phases of development can program the individual to chronic diseases in adulthood. It is important that COVID-19 patients receive proper monitoring as a way to avoid expensive costs to public health in the future

Il Veneto tra dati pandemici, immagini satellitari e social-media nell’analisi del contagio e del lockdown

Veneto, one of the most densely populated, industrialized and tourist regions in Italy, also has the sad distinction of being one of the first to have seen Covid-19 arrival in its territory. The maps and reflections produced for the Veneto region have brought out some aspects related to the analysis of the pandemic and the consequences of the lockdown that affected our region and which we want to highlight in this contribution. On the side of the pandemic, the poor availability of statistics on the infection at the municipal level, which is the smaller scale to draw any consideration of the relationships between the spread of the infection and the anisotropy of the territories, also introduced in our work the discussion launched by the #datibenecomune campaign for ask the government for open, up-to-date and machine-readable data. Together with the maps on the infection, produced mainly with information obtained from the mass media, which highlight the peculiar situations of the municipalities of Vo’ Euganeo and Merlara, the location of the hospitals and Covid hospitals is presented. Regarding to the lockdown, we highlight its main effects on mobility, pollution, economy and tourism, obtaining maps from statistical data and experimenting with the analysis of spatial information from a volunteered geographic information approach through the processing of geo-localized tweets, as well as the study of satellite images with remote sensing techniques

Stevia Nonsweetener Fraction Displays an Insulinotropic Effect Involving Neurotransmission in Pancreatic Islets

Stevia rebaudiana (Bert.) Bertoni besides being a source of noncaloric sweeteners is also an important source of bioactive molecules. Many plant extracts, mostly obtained with ethyl acetate solvent, are rich in polyphenol compounds that present insulinotropic effects. To investigate whether the nonsweetener fraction, which is rich in phenolic compounds isolated from Stevia rebaudiana with the solvent ethyl acetate (EAF), has an insulinotropic effect, including interference at the terminals of the autonomic nervous system of the pancreatic islets of rats. Pancreatic islets were isolated from Wistar rats and incubated with EAF and inhibitory or stimulatory substances of insulin secretion, including cholinergic and adrenergic agonists and antagonists. EAF potentiates glucose-stimulated insulin secretion (GSIS) only in the presence of high glucose and calcium-dependent concentrations. EAF increased muscarinic insulinotropic effects in pancreatic islets, interfering with the muscarinic receptor subfamily M3. Adrenergic inhibitory effects on GSIS were attenuated in the presence of EAF, which interfered with the adrenergic α2 receptor. Results suggest that EAF isolated from stevia leaves is a potential therapy for treating type 2 diabetes mellitus by stimulating insulin secretion only in high glucose concentrations, enhancing parasympathetic signal transduction and inhibiting sympathetic signal transduction in beta cells

Anti-Diabetic Effects of the Ethyl-Acetate Fraction of Trichilia catigua in Streptozo-tocin-Induced Type 1 Diabetic Rats

Background/Aims: Trichilia catigua A. Juss., known as “catuaba” in Brazil, has been popularly used as a tonic for fatigue, impotence and memory deficits. Previously, our group demonstrated that the ethyl-acetate fraction (EAF) of T. catigua has antioxidant and anti-inflammatory effects. The present study evaluated the anti-diabetic activity of EAF in type 1 diabetic rats. Methods: Male Wistar rats were divided into four groups (N: non-diabetic group, D: type 1 diabetic group, NC: non-diabetic + EAF group and DC: type 1 diabetic + EAF group). The latter two groups were treated with 200 mg/kg EAF. Type 1 diabetes was induced by intravenous streptozotocin (STZ) injection (35 mg/kg). Starting two days after STZ injection, EAF was administered daily by gavage for 8 weeks. Results: EAF attenuated body mass loss and reduced food and water intake. EAF improved hyperglycaemia and other biochemical parameters, such as alkaline phosphatase (ALP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Furthermore, the number of pancreatic β-cells and the size of the islets had increased by β-cell proliferation in the DC group. EAF promoted reduction in kidney tissue damage in STZ-induced diabetic rats by reduction of renal fibrosis. Conclusion: The present study showed that EAF improves glucose homeostasis and endocrine pancreas morphology and inhibits the development of diabetic nephropathy in STZ-induced diabetic rats