Introdução A obesidade está associada a um quadro de inflamação crônica e de baixa intensidade, que predispõe à resistência à ação da insulina e ao desenvolvimento do diabetes mellitus (DM) tipo 2. O aumento da concentração sanguínea de ácidos graxos não esterificados e de citocinas pró-inflamatórias eleva a expressão hepática de quinases (quinase do inibidor do fator nuclear kappa B (IKK)- e a c-jun N-terminal quinase (JNK)) que aumentam a resposta inflamatória e prejudicam a via de sinalização da insulina. A erva-mate (Ilex paraguariensis) contém compostos bioativos que apresentam a capacidade de reduzir a expressão de genes envolvidos na resposta inflamatória. Objetivo Investigar o efeito da ingestão do extrato aquoso de erva-mate (EAEM) sobre a resposta inflamatória e via de sinalização da insulina no fígado de ratos alimentados com ração hiperlipídica (HL). Métodos Ratos Wistar, machos, foram submetidos à dieta controle (CON) (n= 18) ou HL (n= 18) durante 12 semanas. Após esse período, seis animais de cada grupo foram eutanasiados, enquanto o restante dos animais foi distribuído em grupos que receberam, ou não, por gavagem, o EAEM (1 g/kg massa corporal/dia) durante quatro semanas. Após esse período, todos os animais foram eutanasiados e determinou-se as concentrações de glicose, insulina, colesterol total, HDL-colesterol, LDL-colesterol, VLDL-colesterol, triacilgliceróis (TAG), leptina, adiponectina, TNF-, IL-6, inibidor do ativador do plasminogênio-1 (PAI-1) e a MCP-1 e a atividade sérica das enzimas alanina aminotransferase (ALT) e aspartato aminotransferase (AST). Foi realizada análise histológica para verificação da infiltração de lipídios. Foi avaliada também a composição corporal dos animais. Para a análise da expressão das proteínas JNK, IKK-, AKT e IRS-1 nas suas formas totais e fosforiladas, e da proteína NF-B, na sua forma fosforilada, um grupo de animais (n = 36) foi submetido ao mesmo protocolo experimental, porém neste foi realizada a infusão de insulina previamente ao momento da eutanásia. Todos os animais foram submetidos ao teste oral de tolerância à glicose (oGTT) e ao teste de tolerância intraperitoneal à insulina (ipITT) na 1 ª, 12 ª e 16 ª semana do protocolo experimental. Resultados Após 12 semanas de protocolo experimental, os animais submetidos à ração HL apresentaram maior consumo alimentar, no entanto, isocalórico em comparação àquele dos animais do grupo CONBL (p < 0,05). O grupo HLBL teve aumento significativo do ganho de peso; do peso coxim adiposo retroperitoneal e do fígado; da glicemia de jejum; da glicemia quando submetidos ao oGTT, em todos os tempos do teste, e ao ipITT no tempo 0, 5, 30 e 40; da concentração sérica de colesterol total, LDL-colesterol, PAI-1 e PCR, em relação ao grupo CONBL (p < 0,05). Apenas 1/3 dos animais HLBL apresentaram degeneração micro e macrogoticular discreta. O consumo da dieta HL diminuiu a fosforilação da AKT em relação aos animais que consumiram a ração CON (p <0,05). No que se refere aos efeitos do EAEM, observou-se que esta intervenção não alterou o consumo alimentar, sendo que os animais submetidos à ração HL, com ou sem a administração do EAEM, ingeriram significantemente menor quantidade em relação aos seus respectivos grupos controles (p < 0,05), todavia, o consumo energético novamente mostrou-se isocalórico (p < 0,05). A administração do EAEM reverteu o quadro de ganho de peso nos grupos que consumiram a ração HL e, ainda, reduziu o percentual de lipídios da carcaça nos animais que consumiram a ração CON, em relação aos respectivos grupos sem a intervenção (p <0,05). O grupo CONEM apresentou aumento do percentual de massa magra e redução da glicemia no ipITT nos tempos após 5 e 10 minutos do início do tese, quando comparado ao seu grupo controle (p <0,05). O EAEM reduziu as concentrações séricas de colesterol total no grupo alimentado com ração HL em relação ao grupo CON (p < 0,05). O grupo HLEM apresentou menor razão da expressão da IKK- fosforilada pela total, fosforilação do NFB, bem como maior razão da expressão da AKT fosforilada pela total em relação ao grupo HL (p < 0,05). Conclusões O consumo de ração HL induziu no fígado perfil pró-inflamatório e quadro de intolerância à glicose Sendo assim, o consumo de ração HL pode ser considerado um fator relevante na etiologia da obesidade e no desenvolvimento das doenças crônicas não-transmissíveis (DCNT), em especial, do DM tipo 2. A intervenção com o EAEM modulou a resposta inflamatória e diminuiu a intolerância à glicose hepática Todos esse fatores, em conjunto, indicam que a erva-mate possa ter um efeito positivo na redução do risco e tratamento das DCNT. / Introduction Obesity is associated with a chronic low-grade inflammation that predisposes to insulin resistance and to the development of type 2 diabetes. The augmentation of plasmatic nonesterified fatty acids and proinflammatory cytokines increases the hepatic expression of some kinases (inhibitor of kappa B kinase (IKK-) and c-jun N-terminal kinase (JNK)) that increases the inflammatory response and impairs the insulin signaling. Yerba mate (Ilex paraguariensis) contains bioactive compounds, which have the ability to reduce the expression of genes involved in inflammatory response. Objective This aim of this project was to investigate the effect of yerba mate aqueous extract (YMAE) intake on the inflammatory response and insulin signaling regulation in the liver of Wistar rats submitted to adjusted high-fat diet (HFD). Methods Male Wistar rats were fed with a control diet (n=18) or a HFD (n=18) for 12 weeks. After this, six animals of each group were euthanized and the rest of the animals were distributed in groups that received, or not, by gavage, YMAE (1g/kg body weight/day) for four weeks. Then, all the animals were euthanized and was determined the glucose, insulin, total cholesterol, HDL-cholesterol, LDL-cholesterol, VLDL-cholesterol, triacylglycerol (TAG), leptin, adiponectin, TNF-, IL-6, C-reactive protein (CPR), plasminogen activator inhibitor (PAI)-1 and MCP-1 concentration, and the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) plasma activity. Histological analysis was performed for the evaluation of lipid infiltration. The body composition of the animal was also evaluated. To expression evaluation of the JNK, IKK-, NF-B, IRS-1 and AKT, a group of animals (n = 36) underwent the same experimental protocol, however, insulin infusion were done previously to moment of euthanasia. All animal were submitted to the oral glucose tolerance test (oGTT) and the intraperitoneal insulin tolerance test (ipITT) in the first, twelfth and sixteenth weeks of the experimental protocol. Results After 12 weeks of experimental protocol, HLBL group had higher feed intake, however, isocaloric intake when compared to the CONBL group (p < 0,05). The HLBL group had a significant increase of weight gain; retroperitoneal adipose deposit and liver weight; fasting glycaemia; glycaemia when submitted to oGTT in all times of the test and upon ipITT at time 0, 5, 30 and 40; serum total cholesterol, LDLcholesterol; PAI-1 and CRP in relation to CONBL (p < 0.05). Only one third of the HLBL animals presented micro and macrogoticular discrete degeneration. The consumption of HFD decreased the hepatic AKT phosphorylation compared to animals fed with the CON diet (p < 0,05). As regards to the YMAE effects, it was observed that this intervention did not alters food consumption, because the animals submitted to the HFD, with or without YMAE administration, ingested significantly lower quantity in relation to their respective control groups (p < 0.05). However, energy consumption again proved to be isocaloric (p < 0.05). The administration of YMAE reversed the weight gain in the groups fed with HFD and also reduced the percentage of carcass fat in the animals fed with the CON diet in relation to the respective groups without intervention (p < 0.05). The CONEM group presented an increased percentage of lean mass and reduction in blood glucose concentration in the ipITT after 5 and 10 minutes from the beginning of the test when compared to the control group (p < 0.05). The YMAE reduced serum total cholesterol concentration in the group fed with the HFD compared to CON group (p < 0,05). The HLEM group presented lowest ratio of expression of phosphorylated by total IKK-, NFB phosphorylation, as well as the major ratio of the expression of phosphorylated by total AKT than HFD group (p < 0,05). Conclusions HFD intake induced liver proinflammatory profile and glucose intolerance. Thus, HFD intake can be considered a relevant factor in the etiology of obesity and the development of chronic non-comunicable diseases, in particular, the type 2 diabetes. The intervention with YMAE modulates the inflammatory response and decreased glucose intolerance. All these factors together indicate that yerba mate may have a positive effect on risk reduction and treatment of chronic diseases.

Introdução: Os antirretrovirais (ARV) levam ao desenvolvimento de alterações metabólica, composta por dislipidemias, intolerância à glicose, resistência insulínica, hipertensão e lipodistrofia, associadas ao aumento do risco de doenças cardiovasculares. O cromo é um mineral essencial envolvido no metabolismo dos carboidratos e lipídeos. Ele está relacionado com a melhora da sensibilidade insulínica, das anormalidades metabólicas e da composição corporal. Objetivo: Avaliar o efeito da suplementação com cromo em pessoas HIV-positivo com lipodistrofia em TARV em marcadores do metabolismo da glicose, do metabolismo dos lipídeos, de inflamação e de estresse oxidativo. Materiais e Métodos: Neste estudo de intervenção, duplo-cego, placebo foi avaliado 41 voluntários HIV-positivo com lipodistrofia em TARV. Os voluntários foram randomizados em 2 grupos, 19 no grupo placebo e 22 no grupo cromo. O grupo cromo recebeu 200µg/dia de cromo (Cr3+) quelato 10% por 3 meses. Antes e após intervenção, todos os voluntários foram submetidos às avaliações clínica, nutricional e bioquímica. As variáveis analisadas foram: resistência insulínica, perfil lipídico, composição corporal, marcadores de inflamação e de estresse oxidativo. Resultados: Os participantes tinham idade (média ± DP) de 47,09 ± 8,15 anos. A composição corporal e os marcadores de inflamação e estresse oxidativo não sofreram alterações após intervenção. Glicemia, insulina, triglicerídeos e o colesterol total e frações, também, não sofreram alterações significativas após 3 meses de suplementação com cromo. No entanto, os participantes que apresentam LDL colesterol alterado (>= 130mg/dL), a suplementação com cromo foi capaz de reduzir 31,2 mg/dL (p = 0,049, de 176,6 (43,2) mg/dL para 145,4 (32,10) mg/dL). Apesar de não significativo (p = 0,27, de 244,1 (47,1) mg/dL para 220,8 (32,5) mg/dL), a média do colesterol total reduziu 23,8 mg/dL no grupo cromo com colesterol alterado (CT > 200mg/dL). Conclusão: A suplementação de cromo por 3 meses reduziu os níveis de LDL colesterol nos voluntários com hiperlipidemia. Esses resultados sugerem que o tratamento com cromo pode beneficiar indivíduos HIV-positivo com lipodistrofia, sobretudo, aqueles com LDL colesterol aumentado. / Introduction: Antiretroviral therapy (HAART) leads to the development of metabolic changes, including dyslipidemia, glucose intolerance, insulin resistance, hypertension and lipodystrophy, associated with an increased risk of cardiovascular diseases. Chromium is an essential mineral involved in the metabolism of carbohydrates and lipids. The role of chromium is associated to the improvement of insulin sensitivity, metabolic abnormalities and body composition. Objective: Evaluate the effect of chromium supplementation in HIVpositive peoples with lipodystrophy on HAART in glucose metabolism, lipid metabolism, inflammation and oxidative stress markers. Materials and Methods: The current study is a randomized, double-blind, placebo-controlled trial, with subjects receiving 200 ?g / day of chromium (Cr3+) chelate 10% or placebo for 3 months. Forty-one (n = 41) HIV-positive 41 HIV-positive volunteers with lipodystrophy on HAART were randomized into 02 groups, placebo (n = 19) and Chromium (n = 22). Before and after intervention, all volunteers were submitted to clinical, nutritional and biochemical evaluations. Analyzed variables: insulin resistance, lipid profile, body composition, markers of inflammation and oxidative stress. Results: The volunteers\' average age were 47.09 ± 8.15 (mean ± SD) years. Body composition, inflammatory and oxidative stress markers did not change by the intervention. In addition, glycemia, insulin, triglycerides and total cholesterol and fractions did not change after 3 months of chromium supplementation. Although, in subjects with altered LDL cholesterol (>= 130 mg/dL), chromium supplementation were able to reduce 31.2 mg / dL (P = 0.049, from 176.6 (43.2) mg/dL to 145, 4 (32.10) mg/dL). Even if not significant, mean total cholesterol (p = 0.27, from 244.1 (47.1) mg/dL to 220.8 (32.5) mg/dL) decreased 23.8 mg/dL Chromium group with altered cholesterol (TC > 200 mg/dL). Conclusion: Chromium supplementation for 3 months reduced LDL cholesterol levels in subjects with hyperlipidemia. These results suggest that chromium treatment may benefit HIV-positive individuals with lipodystrophy, especially those with increased LDL cholesterol.

Introdução: A ingestão de lipídios saturados está relacionada ao aumento da adiposidade, seja em humanos ou em modelos animais. O excesso de gordura corporal promove quadro de inflamação crônica e de baixa intensidade, condição esta associada à alteração no metabolismo da glicose, à resistência a ação da insulina e ao desenvolvimento de doenças crônicas não transmissíveis (DCNT). No tecido muscular, o aumento da atividade das proteínas quinases designadas quinase do inibidor do fator nuclear B (IKK)- e a c-Jun N-terminal quinase (JNK) contribui para o quadro de hiperglicemia por meio da redução da ativação do substrato 1 do receptor de insulina (IRS-1) e da proteína quinase B (Akt/PKB). A administração da erva-mate (EM), que possui compostos bioativos (CBA) com atividade anti-inflamatória, pode atuar na redução do processo inflamatório induzido pela elevada ingestão de ácidos graxos saturados. Objetivo: Investigar os efeitos do consumo isocalórico da ração hiperlipídica e da administração da erva-mate (Ilex paraguariensis) sobre a expressão de proteínas envolvidas na via de sinalização da insulina no músculo sóleo de ratos Wistar. Métodos: O delineamento experimental foi realizado em 2 momentos. Inicialmente, 36 ratos Wistar, machos foram distribuídos em dois grupos, os quais ingeriram ração controle (CON) (n= 18) ou hiperlipídica (HL) (n= 18), durante 12 semanas, caracterizando os grupos baseline CONBL e HLBL, respectivamente. Após esse período, 6 animais de cada grupo sofreram eutanásia, enquanto o restante dos animais de cada grupo foi distribuído em grupos que receberam, ou não, por gavagem, o extrato aquoso de erva-mate (EAEM) na dose de 1 g/kg de massa corporal, durante 4 semanas. Os animais foram submetidos ao teste oral de tolerância à glicose (oGTT) e ao teste intraperitoneal de tolerância à insulina (ipITT) na primeira, décima segunda e décima sexta semana do protocolo experimental. A partir do sangue, foram determinadas as concentrações de glicose, insulina, ácidos graxos não esterificados totais, adiponectina e proteína C reativa. A composição corporal foi avaliada por meio da carcaça dos animais. A partir do músculo sóleo, foi avaliada a expressão das proteínas JNK, IKK-, AKT e IRS1, nas suas formas totais e fosforiladas, e do fator de transcrição nuclear NFB, na sua forma fosforilada. Também foi realizada a avaliação histológica nesse tecido. Resultados: A ingestão isocalórica da ração HL não promoveu aumento de adiposidade, contudo, o grupo HLBL apresentou maior peso do coxim retroperitoneal em relação ao CONBL (p<0,05). O grupo HLBL mostrou hiperglicemia, resistência à ação da insulina, aumento das concentrações plasmáticas de colesterol total, colesterol não-HDL e de proteína C reativa em comparação ao grupo CONBL (p<0,05). No músculo sóleo, verificou-se aumento da razão fosfo:total IKK- no grupo HLBL em comparação ao CONBL (p=0,02). A administração do EAEM promoveu diminuição de 1 por cento (p<0,05) do ganho de peso corporal do grupo HL suplementado (HL+EM) em relação ao HL não suplementado, o qual apresentou 2 por cento de ganho de peso quando comparado ao HL+EM. Nos tempos de 5 e de 10 minutos após a carga insulínica, as glicemias dos animais HL+EM foram menores que as do grupo HL (p<0,05). Conclusão: A ingestão isocalórica da ração HL promoveu alterações metabólicas importantes, sugerindo possível ativação do processo inflamatório inclusive no tecido muscular. A administração da EM reduziu o ganho de peso, melhorou a sensibilidade à insulina e o perfil lipídico, contribuindo para a redução do risco cardiovascular / Introduction: The ingestion of saturated lipids is related to increase adiposity in humans or in animal models. The excess of fat improve the chronic and low grade of inflammation, condition associated with glucose metabolism disorders, insulin resistance and development of non-communicable diseases (NCD). In muscle tissue, the increase of proteins quinases activities, such as kinase inhibitor of B (IKK)- and c-Jun N terminal kinase (JNK) contributes for hyperglycemia thought the reduction of insulin receptor substrate (IRS)-1 and protein quinase B (AKT/PKB) activation. The administration of yerba mate (YM), which contain bioactive compounds with anti-inflammatory activity, can act on the reduction of inflammatory process induced by saturated fatty acid consumption. Objective: To investigate the effects of isocaloric high-fat diet consumption and Yerba mate (Ilex paraguariensis) administration on the expression of proteins involved in the insulin signaling pathway in Wistar rats soleus muscle. Methods: The experimental design was accomplished in 2 moments. Firstly, 36 Wistar rats, male, were distributed into two groups that ingested control (CON) (n=18) or high-fat (HF) (n=18) diets, during 12 weeks, characterizing baseline groups CONBL and HFBL, respectively. After this period, 6 animals from each group were euthanized, while the others were distributed in groups which received, or not, by oral gavage, yerba mate aqueous extract (YMAE) dose of 1 g/Kg of body weight), for 4 weeks. The rats were submitted to the oral glucose tolerance test (oGTT) and to the intraperitoneal insulin tolerance test (ipITT) on the first, twelfth and sixteenth week of experimental protocol. From the blood, were determined the concentrations of glucose, insulin, free fatty acids, adiponectin and C reactive protein. The body composition was available from the animal\'s carcass. From the soleus muscle, it was available the protein expression of JNK, IKK-, AKT and IRS-1, in total and phosphorylated forms and NF-B at the phosphorylated form. Also, it was realized the histology analysis in this tissue. Results: The ingestion of HF diet did not increase adiposity, however, the HFBL group presented retroperitoneal pad weight higher than CONBL (p<0,05). The HFBL group showed hyperglycemia, insulin resistance and elevated plasmatic concentrations of total cholesterol, HDL non-cholesterol and C reactive protein compared to CONBL group (p<0,05). On the soleus muscle, verified increase of phospho:total IKK- ratio in HFBL group in relation to CONBL (p=0,02). The supplementation with AEYM diminished 1 per cent (p<0,05) of weight gain in HL supplemented group in relation to HF not supplemented that presented 2 per cent of weight gain when compared to HF+YM. In times of 5 and 10 minutes after the insulin load, the glycemia of HF+YM were lesser than the HF group (p<0,05). Conclusion: The isocaloric high-fat diet intake promoted important metabolic changes, suggesting a possible activation of inflammatory process including in skeletal muscle. The administration of YM reduced the weight gain, improved the insulin sensibility and the lipid profile, contributing for the reduction of cardiovascular risk

L’obésité est un état physiopathologique d’origine multifactorielle caractérisé par une accumulation excessive de tissu adipeux (TA). Elle est associée à une augmentation du risque de développer une insulino-résistance (IR), un syndrome métabolique et, à terme, un diabète de type 2. L’altération des fonctions du TA au cours de l’obésité joue un rôle central dans l’apparition des troubles métaboliques, tels qu’une accumulation ectopique de graisse et une IR périphérique, notamment dans le muscle. Dans ce contexte, la qualité des apports énergétiques et plus précisément en lipides pourrait jouer un rôle important dans l’adaptation des tissus au cours de l’obésité. Ainsi le palmitate (PAL), un acide gras saturé (AGS) est pro-lipogénique, pro-inflammatoire et lipotoxique, ce qui favorise l’apparition d’une IR. Les acides gras polyinsaturés oméga-3 (3) auraient des effets antagonistes au PAL et donc potentiellement protecteurs vis-à-vis des perturbations métaboliques associées à l’obésité. Parmi les 3, les effets spécifiques des trois principaux acides gras alimentaires, les acides alpha-linolénique (ALA), éicosapentaénoïque (EPA) et docosahexaénoïque (DHA), ont été très peu décrits.L’objectif principal de ce travail de thèse a été d’étudier les effets propres de l’ALA, de l’EPA et du DHA sur les altérations métaboliques induites en situation d’obésité. Des explorations mécanistiques ont été réalisées sur les cellules musculaires C2C12 dans lesquelles l’IR a été induite par le PAL et sur des adipocytes 3T3-L1 pour étudier l’impact des AGPI 3 sur la différenciation adipocytaire. Les effets des AGPI 3 ont ensuite été étudiés in vivo, en supplémentant des souris C57BL/6 sauvages ou déficientes en leptine (ob/ob) lors de la consommation d’un régime obésogène riche en lipides et en sucrose (mimant un régime occidental).Dans les cellules musculaires C2C12, les trois 3 co-incubés avec le PAL ont induit de façon comparable une diminution du contenu en composés lipotoxiques et une amélioration de la captation du glucose, mais seuls l’EPA et le DHA ont restauré la -oxydation du PAL et l’activation de la voie de signalisation de l’insuline. De plus, l’EPA et le DHA ont eu un effet protecteur supérieur à l’ALA vis-à-vis de l’inflammation induite par le PAL. Dans le modèle in vivo, seul la supplémentation en EPA a amélioré l’homéostasie du glucose en comparaison avec les supplémentations en ALA et en DHA. Alors que l’EPA a réduit la prise de masse grasse, le DHA a induit une hypertrophie des cellules adipeuses associée à une augmentation de la sécrétion de leptine et une baisse de la sécrétion d’adiponectine. Dans un modèle d’adipocytes 3T3-L1 en culture, le DHA a accéléré la différenciation des préadipocytes en comparaison avec l’ALA et l’EPA, pouvant expliquer son effet hypertrophique in vivo.En conclusion et dans nos conditions expérimentales, les 3 ALA, EPA et DHA ont bien des effets communs sur le métabolisme lipidique et glucidique in vitro mais également des effets propres qui ont permis de montrer qu’une supplémentation nutritionnelle en EPA serait plus intéressante pour limiter l’IR in vivo par rapport au DHA ou à l’ALA. Le DHA a quant à lui favorisé l’hypertrophie du TA, perturbant ainsi la sécrétion des adipokines participant à la régulation de la sensibilité à l’insuline des tissus périphériques, comme le muscle squelettique. / Obesity is characterized by an excess of adipose tissue (AT) mass and may be caused by multiple factors. It is associated with an increased risk of the development of insulin-resistance (IR) and metabolic syndrome, leading to type 2 diabetes. The impairment of lipid storage in the AT play a central role in obesity-associated disorders, as it leads to ectopic lipid accumulation and peripheral IR notably in muscles. In this context, the quality of dietary lipids may play a role in the regulation of AT and muscle metabolisms. In fact, palmitic acid (PAL), a saturated fatty acid (SFA) induces lipogenesis, inflammation and lipotoxicity favoring IR in many tissues. On the contrary, omega-3 polyunsaturated fatty acids (3) have protective effect against obesity-associated disorders. Among them, linolenic (ALA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) specific effects remained partially described.This work aimed at exploring the specific effects of 3 on metabolic disorders and the development of obesity. Mechanisms were studied in C2C12 muscle cells during PAL-induced IR and in 3T3-L1 adipocytes to determine the impact of 3 on adipocyte differentiation. In vivo, the effects of 3 were investigated by supplementating C57BL/6 wild-type or leptin-deficient (ob/ob) mice with ALA, EPA or DHA during a high fat / high sucrose diet (mimicking a western diet).In C2C12 muscle cells, co-incubation of 3 with PAL induced a similar decrease in the content of lipotoxic compound and improved glucose uptake, whereas only EPA and DHA restored -oxidation and insulin signaling activation. Furthermore, EPA and DHA were more potent to reduce PAL-induced inflammation compared to ALA. In mice, only EPA improved whole body glucose homeostasis compared to ALA and DHA. While EPA reduced body fat gain, DHA induced hypertrophy in AT, increased leptin secretion and decreased those of adiponectine. In cultured 3T3-L1 adipocytes, preadipocyte differentiation was also induced by DHA compared to ALA and EPA and might explain the hypertrophy observed in mice.In conclusion and in our experimental conditions, ALA, EPA and DHA have common effects on in vitro lipid and glucose metabolism but also specific effects, demonstrating that EPA would be more interesting to limit IR in vivo compared to DHA or ALA. DHA favored hypertrophy of AT and disturbance of adipokine secretion involved in peripheral regulation of insulin sensitivity, notably in muscle.

In horses, a painful and often debilitating disease known as laminitis can result in impaired function and, in severe cases, euthanasia. Equine Metabolic Syndrome (EMS) is a syndrome in horses that results in development of laminitis and is characterized by the presence of general and/or regional adiposity (“cresty neck”), aberrations in blood lipid concentrations, insulin resistance (IR) and/ or hyperinsulinemia. Therapies have focused on improving the state of obesity and insulin resistance with the goal of diminishing the likelihood of laminitis development. A definitive cause for laminitis has not been established, but hyperinsulinemia and IR are likely candidates as experimental states of hyperinsulinemia have been shown to induce laminitis and improvements in insulin sensitivity and obesity have been associated with a decreased risk of laminitis development. This dissertation discusses associations between obesity and IR, as well as potential therapies for alleviating insulin resistance with the ultimate goal of decreasing the risk of developing laminitis. Therapies evaluated included chromium and magnesium, levothyroxine sodium, and metformin hydrochloride. Horses were treated with each supplement for 10 to 36 weeks, depending on the supplement tested, and physical measurements such as body weight, neck circumference, and body condition score were obtained. Throughout each study, blood concentrations of glucose, insulin, and plasma lipids were analyzed. Chromium and magnesium currently do not appear to have any effect on insulin sensitivity, whereas results of levothyroxine administration indicate therapeutic responses, as does metformin, though results indicate further work are required. Research contained in this dissertation focuses on the potential of identifying animals at risk of developing IR and laminitis through measurement of blood biomarkers such as adiponectin and glucagon-like peptide 1. Assays to measure markers included enzyme-linked immunosorbent assays, western blots, and radioimmunoassays. Glucagon-like peptide 1 currently does not appear to differ between healthy and IR animals, but protein band density of high-molecular weight adiponectin does appear to be lower in horses with IR when compared to healthy animals. There is still much to learn about IR in horses, and therapy appears to be dependent on a case by case basis.

Obesity and specifically central obesity is related to insulin resistance, type 2 diabetes and other components of the so-called metabolic syndrome. The aim of this study was to elucidate the interplay between hormones, nutrients and adipose depots in normal and insulin-resistant fat cell metabolism. High levels of free fatty acids (FFAs) induce insulin resistance in muscle and liver in vivo. In the present study, rat adipocytes were treated with high physiological levels of oleic or palmitic acid in vitro for 4-24 h. This treatment had no effect on basal or insulin-stimulated glucose uptake capacity in these cells, neither did it affect the levels of the insulin signalling proteins; insulin receptor substrate (IRS)-1 or –2, phosphatidylinositol 3-kinase (PI3-K), protein kinase B (PKB) or glucose transporter (GLUT) 4, or the regulation of lipolysis rate. Visceral adiposity is considered to be more harmful than peripheral adiposity with respect to metabolic and cardiovascular complications. In adipose biopsies from subjects undergoing abdominal surgery, we found that glucose uptake capacity was elevated in omental as compared to subcutaneous adipocytes. The sensitivity (EC50) or maximum relative response to insulin, measured as % of basal, did however not differ between the depots. In women, subcutaneous adipocytes displayed a higher lipolysis rate following cAMP-stimulation than omental adipocytes, whereas there was a tendency towards the opposite in adipocytes from men. No differences were found between depots or sexes in the ability of insulin to inhibit lipolysis or in the levels of the lipolysis regulating proteins, i.e. protein kinase A (PKA), hormone sensitive lipase (HSL) and perilipin. Glucocorticoids, e.g. cortisol, exert pronounced insulin-antagonistic effects and are associated with redistribution of fat from peripheral to central fat depots in humans. Treatment of human subcutaneous and omental adipocytes in vitro, with the cortisol analogue dexamethasone, resulted in a dose dependent down-regulation of basal and insulin-stimulated glucose uptake capacity in omental, but not in subcutaneous cells. Concomitantly, the levels of IRS-1 and PKB were decreased only in omental adipocytes after dexamethasone treatment. The relative effect of insulin to stimulate glucose uptake was however not altered by dexamethasone treatment. The cAMP-stimulated lipolysis rate was elevated by dexamethasone treatment in cells from the subcutaneous depot in women and tended to be elevated in omental cells from men. No alterations however, were seen in the levels of the assessed lipolysis regulating proteins. Subcutaneous as well as omental fat cell size correlated negatively to insulin action in subcutaneous fat cells in vitro after adjusting for age, sex and body fat parameters in non-diabetic, but not in type 2 diabetic, subjects. Large subcutaneous fat cell size was strongly related to plasma leptin levels in non-diabetic and in type 2 diabetic subjects. We conclude that 1) adipocytes seem to be less vulnerable to elevated levels of fatty acids than muscle and liver cells, 2) the interactions between glucocorticoids and insulin in the regulation of glucose uptake differ between adipose depots, 3) depot specific hormonal lipolysis regulation differs between sexes and 4) fat cell size is related to insulin action in subcutaneous fat cells and to circulating levels of leptin.

The aim of the present thesis was to further increase our understanding of mechanisms contributing to and maintaining cellular insulin resistance in type 2 diabetes (T2D). For this reason, the effects of high glucose and insulin levels on glucose transport capacity and insulin signaling, with emphasis on insulin receptor substrate 1 (IRS-1) were assessed in fat cells. Altered levels of IRS-1 have previously been observed in adipose tissue from insulin-resistant and T2D subjects. A high glucose level (≥15 mM) for 24 h exerted only a minor impairment on glucose transport capacity in human adipocytes, as opposed to rat adipocytes. However, when combined with a high insulin level (104 µU/ml), basal and insulin-stimulated glucose transport was significantly impaired in both human and rat adipocytes. This was associated with a depletion of IRS-1 and IRS-2 protein levels in rat adipocytes, as a result of post-translational changes and altered gene transcription, respectively. In human adipocytes was only IRS-1 protein levels reduced. The high glucose/high insulin setting achieved maximal impairment of glucose transport within 6 h. Subsequent incubations of rat adipocytes under physiological conditions could partially restore insulin sensitivity. Interestingly, in both human and rat fat cells, decreased levels of IRSs occurred after the establishment of impaired glucose transport, suggesting that the observed depletion of IRSs is a consequence rather than a cause of insulin resistance. Nonetheless, IRS depletion is likely to further aggravate insulin resistance. Tyrosine phosphorylation of IRS-1 upon insulin stimulation activates the signaling pathway that mediates glucose transport. Pre-treatment of human adipocytes with high glucose and insulin levels was not associated with any alterations in the total IRS-1 Tyr612 phosphorylation following 10 min insulin stimulation. However, a significant increase in basal Tyr612 phosphorylation was observed. Furthermore, a rise in basal IRS-1 Ser312 phosphorylation was found. This is associated with reduced IRS-1 function and is considered to target IRS-1 to degradation pathways, and thus could potentially explain the observed decrease in IRS-1 protein levels. Our results imply an enhanced activation of insulin’s negative-feedback control mechanism that inhibit IRS-1 function. This could potentially have contributed to the observed impairment of insulin action on glucose transport in these cells. Accordingly, we have also shown that the downstream activation of protein kinase B upon insulin-stimulation is significantly impaired in human adipocytes exposed to the high glucose/high insulin setting, indicating a defect in the signaling pathway mediating glucose transport. We also investigated whether there are humoral factors in the circulation of T2D patients that contribute to peripheral insulin resistance. Human adipocytes cultured for 24 h in medium supplemented with 25% serum from T2D subjects, as compared to serum from non-diabetic subjects, displayed significantly reduced insulin-stimulated glucose uptake capacity. The effect could neither be attributed to glucose, insulin, FFA, TNF-α or IL-6 levels in the serum, but other circulating factor(s) seem to be of importance. In conclusion, chronic conditions of elevated glucose and/or insulin levels all impair insulin action on glucose turnover, but to different extents. A clear distinction between rat and human fat cells in the response to these different milieus was also observed. Alterations in the function of the key insulin signaling protein IRS-1 might be involved in the mechanisms underlying the impaired glucose uptake capacity. IRS-1 reduction however, occurs after but probably aggravates the existing insulin resistance. The effects of high glucose and/or insulin levels may be of importance in T2D, but additional novel factors present in the circulation of T2D patients seem to contribute to cellular insulin resistance.

Die subklinische Klauenrehe ist eine weltweit vorkommende, multifaktorielle und bei Rindern vor allem nach der Abkalbung gehäuft auftretende Erkrankung. Als prädisponierender Faktor für weitere, z. T. sehr schmerzhafte Klauenerkrankungen wie Sohlengeschwüre oder White-Line-Disease besitzt sie nicht nur eine hohe tierschutzrelevante, sondern auch eine große wirtschaftliche Bedeutung. Die Ätiologie und Pathogenese der Klauenrehe sind bis heute nicht hinreichend geklärt. In neuerer Zeit konzentrieren sich die Forschungen auf den peripartalen Zeitraum und den damit verbundenen metabolischen und hormonellen Einflüssen auf das Klauengewebe. In dieser Arbeit wird der Frage nachgegangen, inwieweit eine erhöhte Fettmobilisation bei Kühen in der negativen Energiebilanz nach der Abkalbung sowie eine verstärkte Lipolyse bei antepartal verfetteten Kühen zur Entstehung der subklinischen Klauenrehe beitragen. Gleichzeitig soll die Frage beantwortet werden, welche Rolle die postpartale Insulinresistenz und die dadurch verminderte Glucoseaufnahme ins periphere Gewebe bei der Ausbildung der subklinischen Klauenrehe spielen. Außerdem soll untersucht werden, inwiefern sich systemische Einflüsse auf die verstärkte Ausbildung der Sohlenhämorrhagien nach der Abkalbung nachweisen lassen und ob diese anhand ausgewählter Blutparameter vorhersehbar sind. Für die Untersuchung wurden 30 primi- und 44 multipare Milchkühe aus drei Betrieben mit Laufstallhaltung ausgewählt. Die Sohlenflächen aller acht Hauptklauen eines Tieres wurden nach funktionellem Klauenschnitt 1 Woche und 8 Wochen p.p. fotografiert, in fünf Zonen eingeteilt und anhand Anzahl, Größe und Schweregrad der sichtbaren Läsionen beurteilt. Zur weiteren Differenzierung wurden verschiedene Klauenscores gebildet. 2 - 3 Wochen vor der Abkalbung sowie 1 Woche, 4 und 8 Wochen p.p. wurden Blutproben entnommen und die Konzentrationen der Freien Fettsäuren (FFS), ß-Hydroxy-Butyrat (BHB), Glucose, Insulin und Haptoglobin bestimmt. Die IGF-1-Konzentration wurde zur weiteren Einschätzung der Energiebilanz bzw. Energieaufnahme und der Körperkondition gemessen. Die Insulinresistenz wurde anhand basaler Insulin- und Glucose-Konzentrationen bestimmt. Des Weiteren wurde vor und nach der Abkalbungdie Rückenfettdicke sonographisch gemessen und die peripartale Fettmobilisierung über die Rückenfettdickenänderung errechnet. Nahezu alle untersuchten Tiere (96 %) zeigten für die subklinische Klauenrehe typische Veränderungen. Bei über der Hälfte der Kühe waren 8 Wochen p.p. an allen vier Gliedmaßen Sohlenhämorrhagien vorhanden. Es konnten signifikante Korrelationen der Klauenscoreparameter sowohl zwischen den einzelnen Zonen als auch zwischen den Hinter- und Vordergliedmaßen gefunden werden. 8 Wochen p.p. war eine signifikante Verschlechterung der Klauengesundheit im Gegensatz zur ersten Woche p.p. zu verzeichnen. Da diese Hämorrhagien erst nach zwei Monaten an der Fußungsfläche sichtbar werden, sind die ursächlichen Veränderungen in der Lederhaut zum Zeitpunkt der Abkalbung entstanden. Dabei waren die lateralen Klauen der Hintergliedmaße an der Rusterholzstelle am stärksten betroffen. Ein Einfluss auf die Klauengesundheit durch die Fütterung, die Bodenbeschaffenheit der Haltungssysteme, altersbedingt sowie durch peripartale Erkrankungen konnte nicht gefunden werden. Ungefähr zwei Drittel der untersuchten Kühe hatten nach der Abkalbung eine negative Energiebilanz. Sie zeigten signifikant weniger Läsionen an den Sohlenflächen als Kühe mit positiver Energiebilanz. Eine übermäßige Rückenfettmobilisierung führte in diesen Untersuchungen nicht zu einer Verschlechterung der Klauengesundheit. Antepartal unterkonditionierte Tiere mit wenig Fettmobilisierung waren sogar stärker von Klauenläsionen betroffen als normal- oder überkonditionierte Kühe. Bei Tieren mit einem peripartalen Abfall der IGF-1-Konzentration waren signifikant mehr Veränderungen an der Sohlenfläche nachzuweisen. Die IGF-1-Konzentration korrelierte dabei aber, im Gegensatz zu vielen Angaben in der Literatur, hochsignifikant negativ mit der Energiebilanz und zeigte keinen Bezug zur RFD, so dass fraglich ist, ob dieser Parameter alleine überhaupt geeignet wäre, eine Aussage über die Energiebilanz oder die Ausbildung einer subklinischen Klauenrehe zu treffen. Bei insulinresistenten Kühen waren eine signifikante Erhöhung der Klauenläsionen sowie ein signifikanter Abfall der IGF-1-Konzentration zu verzeichnen. Die Bestimmung der Insulinresistenz anhand basaler Blutglucose- und Insulin-Konzentrationen bei Kühen nach der Abkalbung erwies sich jedoch als äußerst fragwürdig. Signifikante Korrelationen zwischen den Konzentrationen der einzelnen Blutparameter und den Klauenscoreparametern bestanden, bis auf die FFSKonzentration 2 - 3 Wochen a.p., ausschließlich 1 Woche p.p.. Allerdings blieben die Korrelationen insgesamt relativ niedrig. Die IGF-1-Konzentration korrelierte am häufigsten sowie am engsten, Insulin und Haptoglobin korrelierten zu keinem Zeitpunkt mit den Klauenscoreparametern. Es kann davon ausgegangen werden, dass es sich bei den gefundenen Hämorrhagien an der Sohlenfläche um die Ausbildung einer subklinischen Klauenrehe aufgrund systemischer Einflüsse im peripartalen Zeitraum handelt. Eine negative Energiebilanz sowie die antepartale Verfettung der Milchkühe stellen nach den vorliegenden Untersuchungen keinen Risikofaktor dar. In dieser Arbeit konnte nicht bestätigt werden, dass Lipidmobilisation oder mangelnde Glucoseversorgung nach der Abkalbung eine Rolle bei der Entstehung der subklinischen Klauenrehe spielen.

Το σύνδρομο των πολυκυστικών ωοθηκών (PCOS) είναι η συχνότερη ενδοκρινοπάθεια σε γυναίκες αναπαραγωγικής ηλικίας, προσβάλλοντας το 6%-10% του πληθυσμού και είναι το κυριότερο αίτιο ανωοθηλακιορηκτικής υπογονιμότητας στις γυναίκες. Χαρακτηρίζεται από υπερτρίχωση, ανωοθηλακιορηξία και υπερανδρογοναιμία και σχετίζεται σε μεγάλο βαθμό με την παχυσαρκία και την αντίσταση στην ινσουλίνη (IR). Ο σκοπός της μελέτης μας ήταν να διερευνήσουμε αν πολυμορφισμοί των γονιδίων τα οποία σχετίζονται με ειδικά χαρακτηριστικά του PCOS συνδέονται με κλινικές παραμέτρους του συνδρόμου, όπως η υπερανδρογοναιμία, ο βασικός μεταβολικός ρυθμός (BMR) και αντίσταση στην ινσουλίνη. Τα υποψήφια γονίδια τα οποία επιλέχθηκαν σε αυτήν την μελέτη ήταν τα γονίδια των αδρενεργικών υποδοχέων α2Β, β3, το γονίδιο της 17β-Υδροξυστεροειδούς Δεϋδρογενάσης τύπος 5 (HSD17B5), το γονίδιο του υποδοχέα της ινσουλίνης (IRS-1) και το γονίδιο PPARγ. Τα γονίδια των αδρενεργικών υποδοχέων α2Β, β3 είχαν συσχετισθεί με χαμηλό μεταβολικό ρυθμό και αύξηση του σωματικού βάρους σε προηγούμενες μελέτες. Καθώς η παχυσαρκία αποτελεί χαρακτηριστικό των γυναικών με PCOS, διερευνήσαμε εάν ο πολυμορφισμός του α2Β βρίσκεται στο PCOS. Το γονίδιο της 17β-Υδροξυστεροειδούς Δεϋδρογενάσης τύπος 5, (HSD17B5) είναι το γονίδιο του ενζύμου για την αναγωγή της ανδροστενεδιόνης σε τεστοστερόνη. Το γονίδιο IRS-1 έχει ένα σημαντικό ρόλο στην ρύθμιση του κυτταρικού αποτελέσματος της ινσουλίνης. Ο πολυμορφισμός της πρωτεΐνης του IRS-1 (Gly972Arg refSNP ID: rs1801278) απαντά στο 5-6% του γενικού πληθυσμού, διαταράσσει την λειτουργία του IRS-1 και σχετίζεται με την αντίσταση στην ινσουλίνη, την υπερλιπιδαιμία και σακχαρώδη διαβήτη τύπου 2. Το γονίδιο PPARγ ρυθμίζει την έκφραση πολλών γονιδίων τα οποία ενέχονται στην ομοιοστασία της γλυκόζης και των λιπιδίων. Εμείς βρήκαμε ότι ο πολυμορφισμός του α2Β (έλλειψη 301-303) δεν επηρεάζει τον βασικό μεταβολικό ρυθμό, την αντίσταση στην ινσουλίνη ή την αύξηση του σωματικού βάρους σε γυναίκες με PCOS και η επίπτωση του δεν διαφέρει από ότι στον γενικό πληθυσμό. Ο πολυμορφισμός του HSD17B5 σχετίσθηκε με αυξημένα επίπεδα τεστοστερόνης ορού και ελαττωμένο τον λόγο ανδροστενεδιόνης (Α)/ τεστοστερόνη (Τ). Η διάγνωση του PCOS βασίσθηκε στην ταυτόχρονη παρουσία βιοχημικής υπερανδρογοναιμίας, η οποία ορίσθηκε ως αυξημένη τεστοστερόνη ορού και/ή αυξημένο δείκτη ελευθέρων ανδρογόνων, χρόνια ανωορρηξία και πολυκυστική μορφολογία ωοθηκών στους υπερηχογραφικό έλεγχο. Τα αποτελέσματα της μελέτης μας επιβεβαιώνουν προηγούμενη αναφορά ότι ο πολυμορφισμός δεν έχει σημαντικό ρόλο στην γενετική παθογένεια του PCOS. Ωστόσο η παρουσία του πολυμορφισμού έχει κλινική σημασία καθώς συμβάλλει στην βαρύτητα της υπερανδρογοναιμίας. Οι συχνότητες των πολυμορφισμών των γονιδίων Pro12Ala στο PPARγ και Gly972Arg στο IRS-1στις γυναίκες με PCOS δεν διαφέρουν από το γενικό πληθυσμό, αν και η παρουσία του πολυμορφισμού Pro12Ala του PPARγ σχετίσθηκε με χαμηλό μεταβολικό ρυθμό (BMR). / Polycystic ovary syndrome (PCOS) is the most common endocrinopathy of reproductive-age women, affecting 6%–10% of the population and is the leading cause of anovulatory infertility in women. It is characterized by hirsutism, anovulation, and hyperandrogenemia and is highly associated with obesity and insulin resistance (IR). The aim of our study was to investigate, whether polymorphisms of genes associated with certain characteristics of PCOS were linked with various clinical parameters of PCOS, such as hyperandogenemia, basic metabolic rate (BMR) and insulin resistance. The candidate genes chosen for this study were the α2Β, β3 adrenergic receptor gene, 17b-Hydroxysteroid dehydrogenase type 5 gene, the IRS-1 gene, and the PPARγ gene. The α2Β, β3 adrenergic receptor gene polymorphisms were associated with low basal metabolic rate and weight gain in previous studies. As obesity is a characteristic of PCOS women, we investigated whether α2Β adrenergic receptor polymorphism is present in PCOS. 17b-Hydroxysteroid dehydrogenase type 5 (HSD17B5) is the enzyme responsible for reduction of androstenedione to testosterone. IRS-1 has an important role in regulating the cellular effect of insulin. (Gly972Arg refSNP ID: rs1801278) the polymorphism of IRS-1 protein which occurs in about 5-6% of the general population, significantly impairs IRS-1 function and is associated with IR, lipid abnormalities, and type 2 diabetes mellitus. PPARγ gene modulates the expression of many genes involved in glucose and lipid homeostasis. We found that α2Β adrenoreceptor 301–303 deletion polymorphism does not influence basal metabolic rate, insulin resistance or weight gain in women with PCOS and its prevalence did not differ from the general population. HSD17B5 variant was associated with increased serum testosterone levels and decreased androstenedione (A)/testosterone (T) ratio. Diagnosis of PCOS was based on the simultaneous presence of biochemical hyperandrogenism, which was defined as increased serum Testosterone and/or increased free androgen index, chronic anovulation, and polycystic ovarian morphology on ultrasound. The results of our study confirm an earlier report that the polymorphism can not play a major role in the genetic pathogenesis of PCOS. However the presence of the polymorphism has a clinical significance as it contributes to the severity of hyperandrogenemia in PCOS patients with biochemical hyperandrogenism. Genotype frequencies of the Pro12Ala in PPARγ2 and the Gly972Arg in IRS-1 gene polymorphisms among PCOS women did not differ from that of the general population, still the presence of Pro12Ala polymorphism of PPARγ2 was associated with lower Basic Metabolic Rate (BMR).

No description available.