Este trabalho avaliou o efeito da dieta hiperlipídica em camundongos para o estudo da inflamação cardiovascular. Camundongos C57Bl/6 machos com 8 semanas de vida foram utilizados nos ensaios, sendo divididos nos grupos dieta controle e dieta hiperlipídica. Após 8 semanas foram avaliados: o ganho de peso, a porcentagem de tecido adiposo, pressão arterial sistólica, frequência cardíaca, perfil lipídico e glicêmico séricos. A partir de cortes histológicos de aortas e corações corados com picrossirius foram feitas análises morfométricas. Em cortes histológicos de aorta foram realizadas a análise fibras elásticas e colágenas usando a coloração de Weigert-Van Gieson. Também foram realizadas a quantificação de fibras colágenas em aortas, usando a coloração de picrossirius. Nos tecidos aórticos e cardíacos foram feitos: 1) Ensaios de atividade enzimática para ECA e MPO. 2) Ensaios de Immunoblotting para a detecção proteíca para ECA e TGF-b. Também foram feitos ensaios de imuno-histoquímica para marcação e localização de ECA e TGF-b no tecido aórtico. / This work evaluated the effect of high-fat diet in mice for the study of cardiovascular inflammation. C57BL / 6 mice at 8 weeks of age were used in the tests were divided in groups control diet and high fat diet. After 8 weeks were evaluated: weight gain, percentage of fat, systolic blood pressure, heart rate, serum lipids and glucose levels. From histological aortas and hearts stained with picrosirius morphometric analyzes. Histological sections of the aorta were performed to analyze elastic and collagen fibers using Weigert-Van Gieson staining. Also the quantification of collagen fibers in aortas using picrosirius staining. In aortic and cardiac tissues were made: 1) Enzymatic activity assays for ACE and MPO. 2) Immunoblotting assays to detect proteinous for ACE and TGF-b. Also were peformed Immunohistochemistry assays for marking and localization of ACE and TGF- b in the aortic tissue.

Intervenções ambientais, como a exposição precoce a estressores ou a dietas ricas em calorias, podem alterar a trajetória da maturação neural e influenciar na susceptibilidade a certas patologias a longo-prazo. Neste contexto, o objetivo do presente estudo foi investigar os efeitos de uma exposição ao isolamento social durante o período pré-pubere associado ou não ao consumo precoce e crônico de uma dieta hiperlipídica (HFD) sobre aspectos cognitivos e emocionais, e possíveis mecanismos neuroquímicos associados a essas alterações, no hipocampo, no córtex pré-frontal e no núcleo accumbens de ratos machos na idade adulta. Os resultados mostraram que os dois fatores, estresse e dieta (separadamente), induziram um comportamento do tipo depressivo nos animais na idade adulta. Além disso, os animais isolados apresentaram um déficit cognitivo associado à memória de curta-duração e de trabalho, enquanto que animais com acesso à HFD demonstraram prejuízo somente na memória de curta-duração. Curiosamente, a interação entre os fatores (estresse e dieta) causou uma reversão dos déficits na memória de curta-duração. Em relação às avaliações do comportamento alimentar hedônico, observamos que o grupo com consumo crônico de HFD apresentou uma menor motivação para obter diferentes tipos de alimentos palatáveis doces. Essa redução motivacional não parece ser associada a uma menor palatabilidade e/ou a uma maior saciedade induzida pela HFD. Em relação aos marcadores de plasticidade analisados no córtex pré-frontal, observamos interações entre os fatores estresse e dieta na atividade da enzima Na+K+-ATPase, nos níveis de BNDF e no imunoconteúdo das proteínas AKT e MAPK/ERK, sendo que os fatores quando aplicados isolados diminuem os níveis dos parâmetros analisados, porém quando associados, os níveis retornam ou aumentam em relação aos valores do grupo controle. O hipocampo foi a estrutura mais afetada pelas intervenções ambientais neste trabalho. Observamos que tanto o estresse, como a dieta hiperlipídica (separadamente) causaram uma redução da plasticidade sináptica hipocampal, por meio de diferentes mecanismos: o acesso crônico à HFD afeta proteínas relacionadas ao funcionamento das sinapses, enquanto o isolamento social parece afetar mais particularmente a via de sinalização do BDNF. Com relação aos achados neuroquímicos no núcleo accumbens, observamos uma redução dos receptores dopaminérgico-1 (D1) e canabinóide-1 (CB1) com o consumo de HFD, enquanto que os animais isolados na pré-puberdade apresentaram uma redução do metabolismo dopaminérgico nesta estrutura. Em suma, esta tese demonstra que tanto o isolamento social e como o consumo contínuo de HFD causam comportamento do tipo depressivo e outras alterações comportamentais, e reduzem marcadores de plasticidade importantes no córtex prefrontal e hipocampo. O acesso à HFD também causa uma menor motivação para o comportamento alimentar hedônico. Assim, tais eventos precoces podem afetar a plasticidade neural levando a importantes alterações comportamentais, e assim predispor a diferentes patologias durante a vida. / Environmental interventions, such as early exposure to stressors or high calorie-diets, can alter the trajectory of neural maturation and influence the susceptibility to some pathologies throughout life. In this context, the aim of the present study was to investigate the effects of exposure to social isolation, during the pre-pubertal period, associated or not with early and chronic consumption of a hyperlipid diet (HFD) on cognitive and emotional aspects, and possible mechanisms associated with these changes, in the hippocampus, the prefrontal cortex and the nucleus accumbens of male rats in adulthood. The results showed that both pre-pubertal social isolation and chronic access to a hyperlipidic diet induced a depressive-like behavior in animals during adulthood. In addition, isolated animals had a cognitive deficit associated with short-term and working memory, whereas animals with access to HFD demonstrated impairment only in short-term memory. Interestingly, the interaction between the factors (stress and diet) caused a reversal in relation to short-term memory, remaining similar to the control group. Regarding the evaluations of the hedonic eating behavior, we observed that HFD group presented a lower motivation to obtain different sweet palatable foods. This impaired motivation does not appear to be associated with less palatability and/or satiety induced by the high-fat diet. Concerning plasticity markers in the prefrontal cortex, we observed interactions between stress and diet on Na+ K+-ATPase activity, BNDF levels and AKT and MAPK/ERK immunocontents. These interactions follow a similar profile: when applied alone, the levels of the analyzed parameters decrease, but when associated, the levels return or increase in relation to the values of the control group. The hippocampus was the structure most affected by the environmental interventions. Both stress and HFD caused a reduction of hippocampal synaptic plasticity through different mechanisms: chronic access to HFD affects proteins related to synaptic function, while social isolation affects the BDNF signaling pathway more significantly. Regarding the neurochemical findings in the nucleus accumbens, we observed a reduction in dopaminergic-1 (D1) and cannabinoid-1 (CB1) receptors with chronic HFD intake, whereas isolated animals had a reduction of dopaminergic metabolism in this same structure. In summary, this thesis shows that both social isolation and chronic consumption of HFD lead to depressive-like behavior and to other behavioral changes; they reduce plasticity markers in prefrontal cortex and hippocampus. HFD access also induced a lower motivation for hedonic feeding. Therefore, these early interventions may affect neural plasticity, leading to important behavioral changes, and thus, predispose to different pathologies later in life.

A discussão sobre a efetividade da fortificação dos alimentos com ferro como estratégia para o controle e a redução do risco da anemia vem ganhando novo enfoque, a partir da associação, em estudos epidemiológicos, entre excesso de peso e deficiência de ferro. O conhecimento dos mecanismos de regulação da homeostase de Fe pode contribuir para o entendimento das alterações no status de ferro e sua relação com a adiposidade em indivíduos obesos e com sobrepeso. Neste trabalho, o status de ferro de ratos Wistar, machos e recém-desmamados, alimentados com rações hiperlipídicas foi estudado ao longo de 60 dias. Os animais receberam, ad libitum, rações normo e hiperlipídicas. Um grupo pair-feeding foi usado, que consumiu a mesma quantidade de ferro que o grupo hiperlipídico. Foi observada maior excreção de Iipídeos nas fezes dos animais do grupo HL, em todos os períodos avaliados. Observou-se associação positiva da adiposidade com o conteúdo de Fe no baço, após 15 dias, e com o conteúdo de Fe no fígado após 30 dias, demonstrando que esses tecidos são afetados de maneira diferente pelo consumo da ração hiperlipídica, ao longo do tempo. Após 60 dias, o consumo da ração hiperlipídica resultou em diminuição da sensibilidade à insulina e em aumento da gordura corporal. Nesse período, esses animais apresentaram maior excreção de ferro nas fezes do que os controles. Além disso, houve associação negativa e significativa do ferro sérico com a adiposidade, apesar de não terem sido observadas diferenças na concentração de hemoglobina entre os grupos. Como conclusão, o consumo das rações hiperlipídicas resultou em alterações na digestibilidade do Fe na ração e em redistribuição compartimental do mineral, o que sugere interações entre o ferro e os lipídeos no lúmen intestinal ou, ainda, um processo adaptativo à condição de estresse gerada pelo excesso de lipídeos da dieta. / The discussion on the effectiveness of food fortification with iron as a strategy to control and reduce the risk of anemia is gaining new focus, from the association in epidemiological studies between overweight and iron deficiency. Knowledge on mechanisms of regulation of Fe homeostasis may contribute to the understanding of changes in iron status and its relationship with adiposity in obesity and overweight. In this study, the iron status of weanling male Wistar rats fed with high-fat diets was studied during 60 days. The animals received ad libitum normo-and high-fat diets. A pair-feeding group was used, which consumed the same amount of iron as the HF group. Lipid excretion was higher in feces of the HF group, in ali periods. A positive association between fat and spleen Fe content after 15 days, and the liver Fe content only after 30 days, demonstrate that these tissues are affected differently by the high-fat diet consumption over time. After 60 days, the consumption of high-fat diet resulted in decreased insulin sensitivity and increased fat mass. During this period, these animals had higher iron excretion in feces than controls. In addition, there was a significant negative association between serum iron and adiposity, although no differences were observed in hemoglobin concentration between groups. In conclusion, consumption of high-fat diets resulted in changes in the Fe digestibility and compartmental mineral redistribution, suggesting interactions between iron and lipids in the intestinal lumen, or even an adaptive process to the condition of stress generated by excess of dietary Iipids.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / A menopausa está associada a algumas alterações metabólicas como a obesidade, dislipidemia e inflamação, entre outras anomalias presentes na síndrome metabólica humana. Uma dieta hiperlipídica ou high-fat (HF) associada à menopausa piora tais alterações, aumentando ainda mais o risco de doença cardiovascular. A hipótese de que uma dieta HF agrava as complicações relacionadas à ovariectomia foi testada. Foram avaliadas fêmeas C57BL/6 ovariectomizadas (OVX) ou com operação SHAM e alimentados com ração padrão ou Standard Chow (SC, 10% de gordura) ou uma dieta HF (60% de gordura) por 18 semanas. A eficiência alimentar (EA), massa corporal (MC), distribuição regional das massas de gordura e a morfometria dos adipócitos foram estudados. As análises de sangue (colesterol total, CT, triglicerídeos, TG, citocinas e adipocinas) foram realizadas. Camundongas OVX-HF apresentaram maior EA e maior MC do que os demais grupos (P<0,05). A gordura visceral (ovariana e retroperitoneal) e a gordura subcutânea (gordura inguinal) tiveram o mesmo padrão de distribuição entre os grupos SHAM-SC, SHAM-HF e OVX-SC, mas o grupo OVX-HF apresentou um padrão diferente de acúmulo de gordura - muito maior do que no rupo SHAM-SC. A associação da ovariectomia com a dieta HF aumentou significativamente o diâmetro dos adipócitos dos animais OVX-HF em comparação aos SHAM-HF (P<0,0001) e também agravou a elevação dos níveis de CT, TG e de leptina nas camundongas OVX-HF, em relação aos OVX-SC (P<0,0001). Os níveis de adiponectina foram maiores nas camundongas OVX-SC comparados com as das camundongas SHAM-SC e OVX-HF (P<0,001). A associação da ovariectomia com a dieta HF agravou o aumento dos níveis séricos de leptina em camundongas OVX-HF, em relação aos OVX-SC (P<0,005). TNF-alfa não foi diferente entre os grupos, mas a IL-6 foi significativamente maior nas camundongas OVX-HF comparados a ambos os grupos SHAM-HF e OVX-SC (P<0,0001). Concluindo, a ingestão de uma dieta hiperlipídica por camundongas ovariectomizadas, leva ao aumento do acúmulo e redistribuição inadequada de gordura, à piora dos níveis de citocinas e adipocinas, assim como à desordem metabólica, o que aumenta os fatores de risco para doenças cardiovasculares. / Menopause is associated with some metabolic disorders as dyslipidemia, obesity and inflammation among others abnormalities present in the human metabolic syndrome. High-fat diet (HFD) is associated with menopause enhanced menopause alterations, increasing the risk of cardiovascular disease. The hypothesis that a high-fat (HF) diet aggravates ovariectomy-related complications was tested. SHAM and ovariectomized (OVX) C57BL/6 mice fed standard chow (SC, 10% fat) or a HF diet (60% fat) for 18 weeks were studied. Feed efficiency (FE), body mass (BM), regional fat pad masses distribution and adipocyte morphometry were studied. Blood analyses (total cholesterol, TC, triglycerides, TG, cytokines and adipokines) were performed. OVX-HF mice had greater FE and BM than all other groups (P<0.05). Visceral fat (ovarian and retroperitoneal fat pads) and the subcutaneous fat (inguinal fat pad) varied with a parallel pattern of fat accumulation in SHAM-SC, SHAM-HF and OVX-SC, but OVX-HF had different pattern of fat accumulation much greater than in SHAM-SC. The association of ovariectomy with HF diet increased significantly the adipocyte diameter in OVX-HF in comparison with SHAM-HF mice (P<0.0001) and also aggravated the increment of TC, TG and leptin levels in OVX-HF mice in comparison to OVX-SC mice (P<0.0001). Adiponectin levels were higher in OVX-SC mice compared to both SHAM-SC and OVX-HF mice (P<0.001). The association of ovariectomy with HF diet aggravated the increase of serum leptin levels in OVX-HF mice in relation to OVX-SC mice (P<0.005). TNF-alpha was not different among the groups, but IL-6 was markedly higher in OVX-HF mice than in both SHAM-HF and OVX-SC mice (P<0.0001). In conclusion, high-fat diet intake worsens, in ovariectomized mice, the fat accumulation and redistribution as well as the cytokines and adipokines levels, and metabolic disorder, which increases risk factors for cardiovascular diseases.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / No presente estudo, foram investigados o mecanismo central e a termogênese pelo tecido adiposo marrom (BAT) envolvidos com a perda de massa corporal (MC) observada com a administração de liraglutida (análoga do hormônio GLP1). Camundongos machos C57BL/6, foram alimentados com dieta padrão e tratados com veículo (SC) ou com liraglutida (SC/Lir) ou com dieta hiperlipídica e tratados com veículo (HF) ou com liraglutida (HF/Lir) Nossos resultados demostram que a administração de liraglutida aumentou o neuropeptídeo anorexigênico pro-opiomelanocortina no hipotálamo e diminuiu a expressão do mRNA da proteína supressora da sinalização de citocinas-3. A administração de liraglutida melhorou os níveis plasmáticos de adiponectina e diminuiu tanto a intolerância à glicose, como a resistência à insulina. Além do mais, tanto o grupo SC como o grupo HF, consumiram a mesma quantidade de comida, já o grupo SC/Lir comeu 17,5 menos comida comparado com o grupo SC e, da mesma forma, o grupo HF/lir diminuiu o consumo alimentar em 22,5% comparado com o grupo HF. A massa corporal final foi 8,5% menor no grupo SC/Lir comparado com o grupo SC e 16% menor no grupo HF comparado com o grupo HF/Lir. Além do mais, a administração de liraglutida aumentou o consumo de oxigênio e a produção de dióxido de carbono, e diminuiu o quociente respiratório. A liraglutida aumentou ainda os níveis do receptor beta 3 adrenérgico, da proteína desacopladora mitocondrial-1, do TC10 e do transportador de glicose estimulado pela insulina (GLUT)-4 no BAT. Em conclusão, a administração de liraglutida em camundongos obesos induzidos por dieta ativou a via anorexigênica, diminuindo o consumo alimentar, atuando sinergicamente com o aumento do gasto energético.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Indivíduos obesos apresentam maior risco de morbidade e mortalidade atribuída às doenças cardiovasculares. A composição da dieta é um fator que prediz o fenótipo cardíaco em resposta a obesidade e, o tipo de ácido graxo pode afetar de forma diferencial a estrutura e a função do miocárdio. Estudos têm mostrado que a disfunção mitocondrial exerce um papel chave na patogênese da insuficiência e hipertrofia cardíaca, e as alterações mitocondriais observadas em falhas cardíacas apontam para defeitos em sítios específicos da cadeia transportadora de elétrons. Desta forma, o objetivo deste estudo foi avaliar a função contrátil ventricular em camundongos, alimentados com dieta hiperlipídica, rica em ácidos graxos poliinsaturados, buscando elucidações através da bioenergética mitocondrial. Após desmame, camundongos machos C57Bl/6 passaram a receber dieta manipulada contendo 7% (C) ou 19% (HF) de óleo de soja, até os 135 dias de idade. A ingestão alimentar e a massa corporal foram monitoradas e foi realizado teste de tolerância à glicose. No final do período experimental, os animais foram anestesiados e submetidos à avaliação da composição corporal por Absortimetria de Raios X de Dupla Energia (DXA), e em seguida, sacrificados por exsanguinação. No plasma foram determinados o perfil lipídico e a insulina. O coração, o tecido adiposo intra-abdominal e o subcutâneo foram coletados, pesados, processados para análise histomorfológica. Fibras cardíacas do ventrículo esquerdo foram utilizadas para análise da respiração mitocondrial através de oxígrafo. O coração também foi utilizado para a técnica de perfusão de coração isolado de Langendorff, e para análise da expressão de proteínas relacionadas à bioenergética de cardiomiócitos, através de Western Blotting. O índice de HOMA e de adiposidade foram calculados. O grupo HF apresentou maior adiposidade, sem alteração na ingestão alimentar. Foi observada intolerância a glicose, hiperinsulinemia e resistência à insulina, além de alterações desfavoráveis no perfil lipídico. Foi observado alteração na morfologia cardíaca e quadro de cardiomiopatia hipertrófica, refletindo em alteração hemodinâmica, determinando maior contratilidade, maior pressão ventricular e função diastólica prejudicada. Em relação à atividade mitocondrial dos cardiomiócitos foi observada menor oxidação de carboidratos (-47%) e de ácidos graxos (-60%). Porém, sem alteração na expressão de proteínas relacionadas à bioenergética de cardiomiócitos, CPT1, UCP2, GLUT1, GLUT4, AMPK e pAMPK. A partir desses resultados, concluímos que o tipo e a quantidade de ácidos graxos predizem o fenótipo cardíaco na obesidade, promovendo alteração na capacidade oxidativa mitocondrial, na morfologia e na hemodinâmica cardíaca / Obese individuals have a higher risk of morbidity and mortality attributed to cardiovascular disease. The diet composition is one factor that predicts the cardiac phenotype in response to obesity and the type of fatty acid differentially influences the myocardial structure and function. Studies have showed that mitochondrial dysfunction is considered to play a key role in the pathogenesis of cardiac hypertrophy and failure, also the mitochondrial alterations present in heart failure indicate to defects at specific sites in electron transport chain. Thus, the aim of the study was evaluated the ventricular contractile function in mice fed high fat diet, rich in polyunsaturated fatty acids, looking through mitochondrial bioenergetics. After weaning, mouse C57Bl/6 received manipulated diet containing 7% (C) or 19% (HF) of soybean oil, until 135 days of age. The food intake and the body mass were monitored, and the glucose tolerance test was realized. At the end of the experimental period, the animals had their body composition evaluated by Dual-energy X-ray Absorptiometry (DXA), after, were sacrificed by exsanguination. In plasma was determined the lipid profile and insulin. The heart, intraabdominal and subcutaneous adipose tissue were collected, weighted and processed to morphological analysis. The left ventricular myocardial fibers were used to analyze mitochondrial respiration by technique of high resolution respirometry. The heart was used to the Langendorff technique of isolated heart perfusion, and to analyze the expression of proteins related to the cardiomyocytes bioenergetics, through of Western Blotting. The HOMA-IR and the adiposity index were calculated. The group HF showed higher adiposity, but did not differ about food intake. Was observed glucose intolerance, hiperinsulinemia, insulin resistance and also unfavorable alterations in lipid profile. Was observed alterations in cardiac morphology and hypertrophic cardiomyopathy, reflecting in hemodinamic alterations with increase of contractility, higher ventricular pressure and impaired diastolic function. About the mitochondrial activity of cardiomyocytes was observed lower oxidation of carbohydrates (-47%) and fatty acids (-60%). However, the expression of proteins related to the cardiomyocytes bioenergetics, CPT1, UCP2, GLUT1, GLUT4, AMPK e pAMPK, did not differ between the groups. From these results, we conclude that the type and amount of fatty acids predict the cardiac phenotype in obesity, promoting the impairment of mitochondrial oxidative capacity, alterations in cardiac morphology and hemodynamics

Ad libitum high-fat diet (HFD)-induced obesity leads to insulin resistance in skeletal muscle, altered gene expression, and altered growth signaling, all of which contributes to pathological changes in metabolism. Liver kinase B1 (LKB1) is an important metabolism regulator. The purpose of this dissertation was to understand how knocking out LKB1 influences HFD induced adaptations in mouse skeletal muscle. To do so, control and skeletal muscle LKB1 knock-out (LKB1-KO) mice were put on either standard diet (STD) or HFD for 1 week or 14 weeks, or put on the HFD for 14 weeks and then switched to STD for 1 week (switched diet). The major differences in adaptation in the LKB1-KO mice include: 1) lower fasting blood glucose levels but impaired glucose tolerance compared to WT mice (although conflicting results are generated if the data is not normalized to fasting blood glucose levels), 2) altered expression of 16 HFD-induced genes, and 3) decreased muscle weight. The lower fasting blood glucose in LKB1-KO mice was likely due to elevated serum insulin levels, and the impaired glucose tolerance was associated with decreased phosphorylation of TBC1D1, an important regulator of insulin stimulated glucose uptake. 16 potential important target genes (metabolism, mitochondrial, cytoskeleton, cell cycle, cell-cell interactions, enzyme, ion channel) were identified in the context of HFD feeding and LKB1-KO. These genes were quantified by RT-PCR and grouped according to changes in their patterns of expression among the different groups. Among several other interesting changes in gene expression, the muscle growth-related protein, Ky was not affected by short-term HFD, but increased after long-term HFD, and did not decrease after switched diet, showing that its expression may be an important long-term adaptation to HFD. LKB1-KO promoted anabolic signaling through increasing t-eIF2α and eIF4E expression, and promoted protein degradation through increasing protein ubiquitination. Because the degradation is the main effect and lead to muscle weight decrease. The effect of HFD and/or LKB1-KO on the LKB1-AMPK system was also determined. The results showed that knocking-out LKB1 decreased AMPK activity, decreased nuclear distribution for AMPK α2 and increased AMPK α1 expression. Long-term HFD increased t-AMPK expression in LKB1-KO mice, decreased the cytoplasm p-AMPK and nuclear p/t-AMPK ratio in CON mice. Together the findings of this dissertation demonstrated HFD induced glucose/insulin tolerance, while LKB1-KO had a controversial effect on glucose/insulin sensitivity. Both HFD and LKB1-KO affect AMPK expression and cellular location, while LKB1-KO also affects AMPK activity. LKB1-KO promoted protein degradation through ubiquitination in skeletal muscle.

Diabetic cardiomyopathy characterized by left ventricular hypertrophy predisposes diabetic and obese individuals to development of cardiac dysfunction and subsequently to heart failure. Whether hyperinsulinemia has an underlying role in development and or progression of diabetic heart disease is not well understood. We therefore studied the effects of acute hyperinsulinemia on cardiac function in euglycemic states. Acute hyperinsulinemia neither affected baseline nor inotropic response to β-adrenergic stimulation. Previous studies from our laboratory have indicated a potential role for GRK2, a serine threonine kinase in development of cardiac dysfunction in diabetic states in humans as well as in mice. To assess whether GRK2 mediates the detrimental effects of chronic hyperinsulinemia on cardiac dysfunction in mouse model of diet induced obesity, we utilized cardiomyocyte knockout of GRK2. Our results suggested lack of cardiac functional impairments in high fat fed wildtype mice, which hindered our attempts to ascertain the role of GRK2 in diabetic cardiomyopathy. Mouse models of diet induced obesity have been routinely used to study the effects of obesity and diabetes on cardiac dysfunction but recent evidence from multiple research groups has emphasized the need for evaluation of the utility and relevance of the murine diet induced obesity model for studying cardiovascular abnormalities associated with hyperinsulinemic states, including T2DM and obesity. We therefore studied the effect of chronic fat feeding (>20 weeks) alone or in combination with concomitant hypertension on cardiac function in C57BL/6J mice. Different diets were formulated with either lard (32% saturated fat, 68% unsaturated fat) or hydrogenated coconut oil (95% saturated fat) as the source of fat and fatty acids, which contributed 60% of total calories. Insulin resistance and glucose intolerance were readily observed in mice fed a high fat diet in each of the studies. HFD resulted in the development of cardiac hypertrophy; however cardiac function as measured by B-mode echocardiography and LV catheterization was unaffected in high fat diet groups compared to their respective control diet groups. Further, dietary fat feeding regardless of the source of fat modestly altered the gene expression of a few pathological hypertrophic markers or of fibrosis related genes. However, there was an increase in expression of PPARa target genes such as Pdk4 and fatty acid metabolism genes including CD36, AcadL and Cpt1b. Cardiac mitochondrial function as assessed by oxygen consumption rates, ATP synthesis rates and reactive oxygen species production rates were unaltered in high fat diet fed mice. These results suggest that while chronic fat feeding in mice causes cardiac hypertrophy and potentially cardiometabolic remodeling, it might not be sufficient to activate pathological hypertrophic mechanisms that impair cardiac function and cause cardiac fibrosis.

Syftet med denna pilotstudie var att studera om man hos pediatriska patienter som lider av sjuklig fetma kan se förändringar i metabolismen genom att ersätta den traditionella kosten med en kost bestående av hög andel fett och låg andel kolhydrater. De frågeställningar som används är om den förändrade kosten leder till en gynnsam förändring av metabola markörer samt hur patientupplevelsen av de nya kostråden är. Studien har både en kvantitativ och kvalitativ design. Totalt ingår 4 barn i åldern 4-17 år. Två av dessa har under fyra veckor ätit en kost bestående av hög andel fett (50-60E%) och låg andel kolhydrater (15-20E%). Efter avslutad intervention undersöktes hur metabola parametrar förändrats (blodprov) samt hur patienterna upplevt kosten (frågeformulär). Resultatet visar på att kostråden leder till en sänkning av triglycerider, glukos, HDL, total kolesterol och ASAT. Bland kontrollpatienterna ser man en ökning av triglycerider, HDL och total kolesterol. Upplevelsen av kostråden beskrivs som positiva, trots att nackdelar finns. Det finns en positiv attityd till att fortsätta med kostråden.

Type II diabetes mellitus (T2DM) has been associated with the onset of diet-induced obesity, which is currently on the rise worldwide. T2DM is typically characterized by insulin resistance in peripheral tissues such as adipose tissue, liver, and skeletal muscle. In skeletal muscle it is widely accepted that the defective insulin action is due to the inability of the cell to sufficiently activate the insulin signalling pathway and promote systemic glucose uptake. The sarcolipin-null (KO) mouse is a potential novel model for diet-induced obesity and diabetes. KO mice become significantly more obese and display a greater glucose intolerance than wildtype (WT) mice following an 8-week high-fat diet (HFD; 42% calories from fat) but the underlying mechanisms are still unknown. In this study the role of defective skeletal muscle insulin signalling in the development of the impaired glucose tolerance in KO mice was investigated. It was hypothesized that the HFD fed KO mice would exhibit greater reductions in IRS1 tyr628 and Akt ser473 phosphorylation (i.e. decreased activation of the insulin signalling pathway) than controls. Furthermore, it was believed that KO mice would display increased phosphorylation of IRS1 ser307, which is commonly associated with insulin resistance. At 16-weeks of age KO mice and littermates were subdivided into two groups and placed on either a HFD (n=30) or chow diet (n=24) for an 8-week period. Changes in body weight, glucose tolerance, and insulin tolerance were assessed pre- and post-diet period. Following the completion of the diet intervention mice were treated with an intraperitoneal injection of insulin (0.75U/kg) or vehicle solution and sacrificed for tissue collection. Epididymal/inguinal and retroperitoneal fat pads were removed for assessment of whole body adiposity. Whole gastrocnemius muscle was excised and homogenized for Western blot analysis of several key proteins of the insulin signalling cascade. Following completion of the HFD KO mice (48.6 ± 1.6 g) weighed significantly more than HFD fed wildtype (WT) mice (41.5 ± 1.6 g), and all chow fed mice (KO: 36.8 ± 1.5 g; WT: 35.2 ± 1.2 g; p<0.001). Glucose tolerance testing showed that KO mice exhibited significantly greater glucose intolerance compared to control mice post-HFD (p<0.001). Insulin tolerance testing, however, revealed no change in insulin sensitivity in KO or WT mice post-HFD (p>0.05). The HFD fed KO mice (0.73 ± 0.06 g) had an elevated retroperitoneal fat pad weight than HFD fed WT (0.49 ± 0.05 g) and all chow fed mice (KO: 0.28 ± 0.04 g; WT: 0.24 ± 0.04 g; p<0.01). Western blot analysis revealed a similar reduction in insulin receptor substrate-1 (IRS1) tyr628 phosphorylation in both KO and WT mice following the HFD (Con WT: 2.82 ± 0.69; Con KO: 3.06 ± 0.73; HFD WT: 1.71 ± 0.28; HFD KO: 1.28 ± 0.11 fold increase over non-insulin stimulated mice; p<0.02). IRS1 ser307 phosphorylation was elevated in both genotypes post-HFD (HFD WT: 2.97 ± 1.19; HFD KO: 2.17 ± 0.59 fold increase over standard chow fed control mice; p<0.03). Insulin treatment did not stimulate phosphorylation of Akt ser473 in KO or WT mice regardless of diet (p>0.05). In summary there was no difference between KO and WT mice in skeletal muscle insulin sensitivity as assessed by the phosphorylation of insulin signalling intermediates. An increase in IRS1 ser307 phosphorylation appears to be the primary mechanism for the reduced activation of IRS1 following the HFD in both KO and WT mice. However, the results from the current investigation did not support the notion that impaired skeletal muscle insulin signalling is responsible for the more pronounced diet-induced glucose intolerance observed in KO mice. Future studies investigating the viability of skeletal muscle GLUT4 translocation and glucose uptake as well as the glucose-induced insulin secretion of pancreatic β-cells following consumption of a HFD would help elucidate the mechanism of glucose intolerance in KO mice.