Orientador: Licio Augusto Velloso / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-07T04:07:10Z (GMT). No. of bitstreams: 1 Bertelli_DanielaFaleiros_D.pdf: 2445017 bytes, checksum: 2a78cdd0f1bc8fc197cb47c83deb0c0b (MD5) Previous issue date: 2006 / Resumo: A enzima fosfatidilinositol 3-quinase (PI3-kinase) exerce uma importante função na transdução dos sinais anorexigênicos e termogênicos enviados pela insulina e leptina em primeira ordem aos neurônios do núcleo arqueado no hipotálamo. A cascata de sinais intracelulares gerados pela ativação da PI3-kinase depende da atividade coordenada de inositol-fosfatases específicas. Neste trabalho, mostramos que a phosphoinositide-specific inositol polyphosphate 5-phosphatase IV (5ptase IV) está altamente expressa em neurônios do núcleo arqueado e lateral do hipotálamo. Submetido ao tratamento intracerebroventricular (ICV) com insulina, a 5ptase IV sofre fosforilação em tirosina de acordo com um padrão tempo-dependente, a qual segue os mesmos moldes da sinalização da insulina através do seu receptor (IR), seu substrato-2 (IRS2) e da PI3-kinase. Para avaliar a participação da 5ptase IV na ação da insulina no hipotálamo, trabalhamos com um oligonucleotídeo antisense específico para esta enzima. O tratamento dos ratos com este oligonucleotídeo durante quatro dias reduziu a expressão hipotalâmica da 5ptase IV em aproximadamente 80%. Tal fato foi acompanhado pela redução de 70% na sua fosforilação induzida pela insulina, e ainda pelo aumento na quantidade basal dos inositóis fosforilados no hipotálamo. Finalmente, a inibição da expressão da 5ptase IV no hipotálamo pelo oligonucleotídeo antisense, resultou na redução da ingestão média diária de alimentos, na perda de massa corporal e ainda na redução da ingestão alimentar em 12 horas. Desta forma, a 5ptase IV é um potente regulador da sinalização através da PI3kinase no hipotálamo e pode tornar-se um alvo interessante para a terapêutica da obesidade e para as desordens relacionadas / Abstract: The enzyme phosphatidylinositol 3-kinase (PI 3-kinase) exerts an important role in the transduction of the anorexigenic and thermogenic signals delivered by insulin and leptin to first-order neurons of the arcuate nucleus in the hypothalamus. The termination of the intracellular signals generated by the activation of PI 3-kinase depends on the coordinated activity of specific inositol phosphatases. Here, we show that phosphoinositide-specific inositol polyphosphate 5-phosphatase IV (5ptase IV) is highly expressed in neurons of the arcuate and lateral nuclei of the hypothalamus. Upon intracerebroventicular (ICV) treatment with insulin, 5ptase IV undergoes a time-dependent tyrosine phosphorylation, which follows the same patterns of canonical insulin signaling through the insulin receptor, IRS-2, and PI 3-kinase. To evaluate the participation of 5ptase IV in insulin action in hypothalamus, we employed a phosphorthioate modified antisense oligonucleotide specific for this enzyme. The treatment of rats with this oligonucleotide for four days reduced the hypothalamic expression of 5ptase IV by ~80%. This was accompanied by a ~70% reduction of insulin-induced tyrosine phosphorylation of 5ptase IV and by an increase in basal accumulation of phosphorylated inositols in the hypothalamus. Finally, inhibition of hypothalamic 5ptase IV expression by the antisense approach resulted in reduced daily food intake, body weight loss and decreased 12 h spontaneous food intake. Thus, 5ptase IV is a powerful regulator of signaling through PI 3-kinase in hypothalamus and may become an interesting target for therapeutics of obesity and related disorders / Doutorado / Biologia Estrutural, Celular, Molecular e do Desenvolvimento / Doutor em Fisiopatologia Medica

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Class of 2016 Abstract and Report / Objectives: To describe the effect of time spent in pneumatic tube system on the concentrations of bags of regular insulin. Methods: Twelve intravenous bags of regular insulin in normal saline with a concentration of one unit per milliliter were prepared, with six bags acting as the control group and six bags as the experimental group. Bags in the experimental group were transported to stations labeled X, Y, and Z which were at varying distances from the pharmacy. Bags in the control group were walked the same tube stations. Three samples from each bag were analyzed using the ValiMed™ medication validation system before and after transport and the standard deviations (SDs) from the mean were recorded. Results: At baseline there were no statistically significant differences in the standard deviations (SDs) between the control and experimental group (p = 0.1008). SDs after transport compared to baseline SDs produced statistically significant differences (p < 0.005) except for the control group transported to tube station Z (p = 0.0867). Conclusions: The SDs after either transport produced a statistically significant difference when compared to baseline except for one group of insulin bags. This indicates that concentration may not be affected by method of delivery, since statistically significant difference occurred regardless of transport method. It appears to be safe to transport insulin IV infusion bags by pneumatic tube system.

Ageing and obesogenic diets are two prominent problems in the developed world, as both lead to an increase in body mass and insulin resistance, which can then result in further pathophysiologies, such as type 2 diabetes, cancer and cardiovascular disease. Protein tyrosine phosphatase 1B (PTP1B) contributes to development of body weight gain and insulin resistance through negatively regulating leptin and insulin signalling, respectively. Liver-specific ptp1b deletion from birth improves insulin sensitivity, lipid metabolism and decreases endoplasmic reticulum (ER) stress. However, as a therapy in humans, PTP1B inhibition would target pre-diabetic and diabetic adults; therefore, we investigated the effects of liver-specific inhibition of PTP1B in adult, insulin resistant, obese mice. Restricting the amount of the essential amino acid, methionine, five-fold in the diet, decreases body weight, adiposity and improves insulin sensitivity in young mice. In order to delineate if this would be a feasible treatment in adulthood, we administered the diet to 12-month-old mice with age-induced obesity and insulin resistance and compared its effects to those in 2-month-old mice. As hepatic ptp1b deletion and methionine restriction (MR) both improve hepatic insulin signalling, we investigated if the combined treatment could have additive effects compared to MR alone on whole-body glucose homeostasis. To examine if the effects of MR are methionine-specific or if they would occur with restriction of other EAAs, we compared leucine restriction (LR) to MR in adult mice. Overall, hepatic PTP1B inhibition in adult mice reversed high-fat diet (HFD) -induced glucose intolerance, hepatic lipid accumulation and ER stress. MR administered to 12-month-old adult mice reversed the metabolic effects of ageing back to levels measured in healthy, young, 2-month-old mice. The combination of MR and hepatic ptp1b deletion from birth had no further beneficial effect in male mice, but possibly an additional effect in female mice. MR produced stronger beneficial metabolic effects than LR in mice, suggesting methionine-specific mechanisms may play a role.

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Type 2 diabetes mellitus results from a combination of insulin resistance and impaired insulin secretion. The aim of this study is to investigate the effect of endogenous and exogenous cannabinoids on insulin resistant cell lines, viz skeletal muscle (C2C12) and fat (3T3-L1), and to investigate the effects of these cannabinoids on insulin secretion in pancreatic β-cells (INS 1). Insulin resistance was induced in the cells using 20 ng/mL TNF-α (3T3-L1) and 100 nM insulin (C2C12). Insulin resistant cells were exposed to cannabinoids for 48 hours after which glucose uptake, RT-PCR and Western blot analysis was performed. Additionally, adipokine assays were performed on the 3T3-L1 cells. The insulin resistant 3T3-L1 and C2C12 cells had reduced glucose uptake, decreased IRS-1 and Glut-4 expression indicative of an insulin resistant state. The extract and THC significantly enhanced glucose uptake, IRS-1 and Glut-4 in 3T3-L1 and C2C12 cells. The extract and THC thus have the potential to be an insulin sensitizing agent. Interleukin-6 was significantly decreased by THC. INS 1 cells, cultured under normoglycemic conditions, were exposed to cannabinoids for 48 hours after which glucose-stimulated insulin secretion, radioimmunoassay, oxygen consumption, RT-PCR and Western blot analysis was performed. Insulin stimulatory index was not significantly affected after cannabinoid exposure, except by THC. The cannabinoids decreased insulin content, in a concentration dependent manner, but the inhibition mechanism remains elusive. The cannabinoid Treated cells showed insulin gene expression levels similar to the control, while only THC proved effective in significantly stimulating Glut-2 gene expression. Oxygen consumption studies showed levels lower than the control cells. Most of the cannabinoids inhibited insulin secretion under normoglycemia except THC, while the cannabinoids exhibited the potential to improve insulin resistant adipocyte and myocytes response to glucose and gene regulation.

Type 2 diabetes mellitus (T2DM) is rapidly emerging as one of the greatest global health issues of the 21st century. Insulin-resistance is a condition associated with T2DM and in the cell it is defined as the inadequate strength of insulin signalling from the insulin receptor downstream to the final substrates of insulin action involved in multiple metabolic, gene expression, and mitogenic aspects of cellular function. To investigate the potential mechanisms involved in the development of insulin-resistance, two in vitro liver cell models were established using palmitate or a combination of insulin and fructose as inducers. The development of insulin-resistance was determined via the capacity of the hepatocytes to maintain normal glucose metabolism functionality by measuring hepatic gluconeogenesis and glycogenolysis. It was established that the treatments induced the development of insulinresistance after 24 hours chronic exposure. Previous studies have investigated the potential of Sutherlandia frutescens extracts as therapeutic agents for insulin-resistance. The aim of this study was thus to investigate the ability of a hot aqueous extract of S. frutescens to reverse the insulin-resistant state, via measuring gluconeogenesis and glycogenolysis, the associated changes in cellular physiology (lipid accumulation, oxidative stress, and acetyl- CoA levels), and changes in mRNA expression. The results showed that S. frutescens had a significant effect on reversing the insulin-resistant state in both models of insulin-resistance. Furthermore, S. frutescens was capable of reducing lipid accumulation in the form of triacylglycerol in the high insulin/fructose model, while this was unaffected in the palmitate model. However, S. frutescens did reduce the accumulation of diacylglycerol in the palmitate model. Oxidative stress, seen to be associated with the insulin-resistant state, was successfully treated using the extract, as indicated by a reduction in reactive oxygen species. However no change was seen in the nitric oxide levels, in either model. Interestingly, although S. frutescens had no effect on the level of acetyl-CoA in the insulin/fructose model, it was found to increase this in the palmitate model. It is suggested that this may be due to increased β-oxidation and metabolic activity induced by the extract. The analysis of mRNA expression gave some insight into possible mechanisms by which insulin-resistance develops, although the results were inconclusive due to high variability in samples and the possibility of the RNA being compromised. Future studies will address this issue. The results of this study reflect different proposed clinical causes of insulin-resistance through the responses seen in the two cell models. These indicate that liver steatosis and insulin-resistance are induced by high palmitate as well as high insulin and fructose levels, and reversed by S. frutescens. Therefore the potential of S. frutescens to be used as a therapeutic agent in the treatment of insulin-resistance is indicated by this study.

Bibliography: pages 133-155. / Insulin regulates cellular gene expression and modulates specific mRNA levels in liver cells. As yet, the mechanism of this control is still unclear. The effects are initiated following the binding of insulin to the plasma membrane receptor. Although several mediators of the signal from the plasma membrane to the nucleus have been proposed, none has proved capable of eliciting all of the effects of insulin on gene expression. Therefore, the possibility that insulin itself may directly regulate transcription at the level of the nucleus, was investigated.

In May 1992, Banting and Best, working in the Physiology Department of the University of Toronto, obtained the first active extracts from pancreas. The credit for the preparation of such extracts capable of effecting a lowering of the blood and urinary sugar, and serviceable in mitigating the symptoms of experimental diabetes in animals, and o human diabetes, therefore, belongs to these two workers, to Waoleod and Collip. Improvements in the methods of extraction and purification of insulin followed quickly. Accompanying this were the investigations of the physiological, chemical and physical properties of the hormone. Since that time a mass of evidence relating to the above and produce by a host of workers has accumulated.