A high-fructose diet induces insulin resistance but not blood pressure changes in normotensive rats

Rats fed a high-fructose diet represent an animal model for insulin resistance and hypertension. We recently showed that a high-fructose diet containing vegetable oil but a normal sodium/potassium ratio induced mild insulin resistance with decreased insulin receptor substrate-1 tyrosine phosphorylation in the liver and muscle of normal rats. In the present study, we examined the mean blood pressure, serum lipid levels and insulin sensitivity by estimating in vivo insulin activity using the 15-min intravenous insulin tolerance test (ITT, 0.5 ml of 6 µg insulin, iv) followed by calculation of the rate constant for plasma glucose disappearance (Kitt) in male Wistar-Hannover rats (110-130 g) randomly divided into four diet groups: control, 1:3 sodium/potassium ratio (R Na:K) diet (C 1:3 R Na:K); control, 1:1 sodium/potassium ratio diet (CNa 1:1 R Na:K); high-fructose, 1:3 sodium/potassium ratio diet (F 1:3 R Na:K), and high-fructose, 1:1 sodium/potassium ratio diet (FNa 1:1 R Na:K) for 28 days. The change in R Na:K for the control and high-fructose diets had no effect on insulin sensitivity measured by ITT. In contrast, the 1:1 R Na:K increased blood pressure in rats receiving the control and high-fructose diets from 117 ± 3 and 118 ± 3 mmHg to 141 ± 4 and 132 ± 4 mmHg (P<0.05), respectively. Triacylglycerol levels were higher in both groups treated with a high-fructose diet when compared to controls (C 1:3 R Na:K: 1.2 ± 0.1 mmol/l vs F 1:3 R Na:K: 2.3 ± 0.4 mmol/l and CNa 1:1 R Na:K: 1.2 ± 0.2 mmol/l vs FNa 1:1 R Na:K: 2.6 ± 0.4 mmol/l, P<0.05). These data suggest that fructose alone does not induce hyperinsulinemia or hypertension in rats fed a normal R Na:K diet, whereas an elevation of sodium in the diet may contribute to the elevated blood pressure in this animal model.

Simulating the effects of grassland management and grass ensiling on methane emission from lactating cows

A dynamic, mechanistic model of enteric fermentation was used to investigate the effect of type and quality of grass forage, dry matter intake (DMI) and proportion of concentrates in dietary dry matter (DM) on variation in methane (CH(4)) emission from enteric fermentation in dairy cows. The model represents substrate degradation and microbial fermentation processes in rumen and hindgut and, in particular, the effects of type of substrate fermented and of pH oil the production of individual volatile fatty acids and CH, as end-products of fermentation. Effects of type and quality of fresh and ensiled grass were evaluated by distinguishing two N fertilization rates of grassland and two stages of grass maturity. Simulation results indicated a strong impact of the amount and type of grass consumed oil CH(4) emission, with a maximum difference (across all forage types and all levels of DM 1) of 49 and 77% in g CH(4)/kg fat and protein corrected milk (FCM) for diets with a proportion of concentrates in dietary DM of 0.1 and 0.4, respectively (values ranging from 10.2 to 19.5 g CH(4)/kg FCM). The lowest emission was established for early Cut, high fertilized grass silage (GS) and high fertilized grass herbage (GH). The highest emission was found for late cut, low-fertilized GS. The N fertilization rate had the largest impact, followed by stage of grass maturity at harvesting and by the distinction between GH and GS. Emission expressed in g CH(4)/kg FCM declined oil average 14% with an increase of DMI from 14 to 18 kg/day for grass forage diets with a proportion of concentrates of 0.1, and on average 29% with an increase of DMI from 14 to 23 kg/day for diets with a proportion of concentrates of 0.4. Simulation results indicated that a high proportion of concentrates in dietary DM may lead to a further reduction of CH, emission per kg FCM mainly as a result of a higher DM I and milk yield, in comparison to low concentrate diets. Simulation results were evaluated against independent data obtained at three different laboratories in indirect calorimetry trials with COWS consuming GH mainly. The model predicted the average of observed values reasonably, but systematic deviations remained between individual laboratories and root mean squared prediction error was a proportion of 0.12 of the observed mean. Both observed and predicted emission expressed in g CH(4)/kg DM intake decreased upon an increase in dietary N:organic matter (OM) ratio. The model reproduced reasonably well the variation in measured CH, emission in cattle sheds oil Dutch dairy farms and indicated that oil average a fraction of 0.28 of the total emissions must have originated from manure under these circumstances.

Antiobesity Effects of yerba mate Extract (Ilex paraguariensis) in High-fat Diet-induced Obese Mice

Because the potential of yerba mate (Ilex paraguariensis) has been suggested in the management of obesity, the aim of the present study was to evaluate the effects of yerba mate extract on weight loss, obesity-related biochemical parameters, and the regulation of adipose tissue gene expression in high-fat diet-induced obesity in mice. Thirty animals were randomly assigned to three groups. The mice were introduced to standard or high-fat diets. After 12 weeks on a high-fat diet, mice were randomly assigned according to the treatment (water or yerba mate extract 1.0 g/-kg). After treatment intervention, plasma concentrations of total cholesterol, high-density lipoprotein cholesterol, triglyceride, low-density lipoprotein (LDL) cholesterol, and glucose were evaluated. Adipose tissue was examined to determine the mRNA levels of several genes such as tumor necrosis factor-alpha (TNF-alpha), leptin, interleukin-6 (IL-6), C-C motif chemokine ligand-2 (CCL2), CCL receptor-2 (CCR2), angiotensinogen, plasminogen activator inhibitor-1 (PAI-1), adiponectin, resistin, peroxisome proliferator-activated receptor-gamma(2) (PPAR-gamma(2)), uncoupling protein-1 (UCP1), and PPAR-gamma coactivator-1 alpha (PGC-1 alpha). The F4/80 levels were determined by immunoblotting. We found that obese mice treated with yerba mate exhibited marked attenuation of weight gain, adiposity, a decrease in epididymal fat-pad weight, and restoration of the serum levels of cholesterol, triglycerides, LDL cholesterol, and glucose. The gene and protein expression levels were directly regulated by the high-fat diet. After treatment with yerba mate extract, we observed a recovery of the expression levels. In conclusion, our data show that yerba mate extract has potent antiobesity activity in vivo. Additionally, we observed that the treatment had a modulatory effect on the expression of several genes related to obesity.

Effects of a high fat diet on liver mitochondria: increased ATP-sensitive K(+) channel activity and reactive oxygen species generation

High fat diets are extensively associated with health complications within the spectrum of the metabolic syndrome. Some of the most prevalent of these pathologies, often observed early in the development of high-fat dietary complications, are non-alcoholic fatty liver diseases. Mitochondrial bioenergetics and redox state changes are also widely associated with alterations within the metabolic syndrome. We investigated the mitochondrial effects of a high fat diet leading to non-alcoholic fatty liver disease in mice. We found that the diet does not substantially alter respiratory rates, ADP/O ratios or membrane potentials of isolated liver mitochondria. However, H(2)O(2) release using different substrates and ATP-sensitive K(+) transport activities are increased in mitochondria from animals on high fat diets. The increase in H(2)O(2) release rates was observed with different respiratory substrates and was not altered by modulators of mitochondrial ATP-sensitive K(+) channels, indicating it was not related to an observed increase in K(+) transport. Altogether, we demonstrate that mitochondria from animals with diet-induced steatosis do not present significant bioenergetic changes, but display altered ion transport and increased oxidant generation. This is the first evidence, to our knowledge, that ATP-sensitive K(+) transport in mitochondria can be modulated by diet.

Fermentação ruminal de ovinos alimentados com alto concentrado e grãos de girassol ou gordura protegida

Seis ovinos machos, não castrados, da raça Santa Inês, com média de peso de 30kg, fistulados no rúmen, foram distribuídos em delineamento de quadrado-latino duplo (3x3). Três períodos e três dietas, uma controle, sem inclusão de fonte de lipídio, e duas com inclusão de grãos de girassol ou gordura protegida, foram testados quanto aos parâmetros ruminais. Foram verificadas diferenças (P<0,05) entre as dietas quanto à concentração ruminal de amônia (18mg/dL), mas não houve efeito sobre o pH (6,1), a produção total de ácidos graxos de cadeia curta (98mM), a proporção de acetato (66,4%), de propionato (20%) e de butirato (13%) e sobre a razão acetato:propionato (3,2:1). As bactérias sólido-aderidas isoladas do conteúdo ruminal dos animais recebendo a dieta-controle apresentaram maior teor de nitrogênio (10,7%) que as das dietas com gordura protegida (9,8%) ou com grãos de girassol (9,1%). A produção de nitrogênio pelas bactérias sólido-aderidas da dieta-controle (170mg/g) não diferiu da dieta com grãos de girassol (153mg/kg) ou com gordura protegida (160mg/kg). A inclusão de grãos de girassol ou gordura protegida na dieta com alto concentrado para ovinos propiciou ambiente adequado para fermentação ruminal.

Níveis do subproduto concentrado da produção de lisina em dietas com alto concentrado para tourinhos Santa Gertrudes em terminação

O experimento foi realizado objetivando-se caracterizar o subproduto concentrado da produção de lisina (SPL) e avaliar o desempenho e as características de carcaça de tourinhos Santa Gertrudes confinados recebendo níveis crescentes desse subproduto na dieta. O SPL resulta do processo de produção de lisina e é parcialmente seco. Apresentou aproximadamente 38% de matéria seca e 85% de proteína bruta na matéria seca, sendo que 79% desse nitrogênio encontrava-se na forma não-protéica. Não foram observados metais pesados em níveis tóxicos. Vinte e sete animais, com dez meses de idade e peso inicial de 242 kg, receberam silagem de milho, 80% de concentrado e 0; 4,5 ou 9,0% de SPL na matéria seca da dieta. O período experimental foi de 115 dias, após 56 dias de adaptação. A inclusão do SPL na dieta determinou efeito quadrático sobre o ganho de peso, o consumo diário de matéria seca, o peso final e o peso de carcaça; efeito linear decrescente sobre a eficiência alimentar e o rendimento de carcaça; e aumento da espessura de gordura de cobertura e do peso do fígado. Não foram observadas diferenças entre tratamentos para a área de olho de lombo. As diferenças no desempenho não foram associadas ao menor consumo de alimentos ou ao teor de enxofre das dietas. O nível de 3,7% de SPL na matéria seca da dieta foi considerado o máximo recomendado para tourinhos em terminação recebendo dietas com alto teor de energia, quando o ganho diário de peso esperado seria de 1,23 kg/animal.

Dried yeast (Saccharomyces cerevisae) as a protein source for horses

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of calcium salts of polyunsaturated fatty acids on productive and reproductive parameters of lactating Holstein cows

Two experiments evaluated milk production, serum progesterone and insulin, and reproductive performance of lactating Holstein cows receiving or not receiving Ca salts of polyunsaturated fatty acids (PUFA), or receiving Ca salts of PUFA at different daily frequencies. In experiment 1, 1,125 cows randomly distributed in 10 freestall barns were enrolled. Barns were assigned randomly to receive a high-concentrate diet containing (PI?) or not containing (control, CON) 1.1% (dry matter basis) Ca salts of PUPA. Diets were offered 6 times daily, whereas the Ca salts of PUFA were included in the PF treatment in the first feeding of the day. In experiment 2, 1,572 cows were randomly distributed in 10 freestall barns, which were assigned randomly to receive a diet similar to PF, but with Ca salts of PUFA included only in the first feeding of the day (PF1X), or equally distributed across all 6 feedings (PF6X). During both experiments, cows were artificially inseminated 12 h after the onset of estrus. Once per month, cows that did not conceive to artificial insemination were assigned to a fixed-time embryo transfer protocol. Pregnancy was determined via transrectal ultrasonography 28 and 60 d after expected ovulation. Pregnancy loss was considered in cows that were pregnant on d 28 but nonpregnant on d 60. During both experiments, feed intake, milk yield, and milk protein and fat content were recorded weekly. Blood samples were collected concurrently with embryo transfer. During experiment 1, feed intake was similar between treatments. Compared with CON, PF cows had greater milk yield (37.8 vs. 35.3 kg/d), and reduced milk fat content (3.41 vs. 3.55%). However, PF cows had reduced pregnancy losses per service compared with CON (12.6 vs. 18.3%). Serum progesterone was greater and serum insulin tended to be greater in primiparous cows receiving PF compared with CON cohorts (4.50 vs. 3.67 ng of progesterone/mL, and 10.4 vs. 7.5 mu UI of insulin/mL). During experiment 2, no treatment effects were detected for feed intake, milk yield, or milk fat, whereas PF1X cows tended to have reduced pregnancy losses per service compared with PF6X (14.4 vs. 18.4%). In summary, feeding Ca salts of PUFA to dairy cows increased milk production, did not alter feed intake, and reduced pregnancy losses per service. Further, the total daily amount of Ca salts of RITA should be fed during the first feeding of the day to optimize its benefits on pregnancy maintenance of dairy cows.

Effects of corn replacement by sorghum in broiler diets on performance and intestinal mucosa integrity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Potencial nutritivo da torta de dendê na alimentação de ruminantes no estado do Pará

Avalia os efeitos da inclusão de torta de dendê na dieta de ovinos em crescimento, criados sob condições tropicais, com ênfase para efeitos sob o consumo, a digestibilidade aparente e o desempenho desses ruminantes. Para o ensaio do consumo e da digestibilidade aparente utilizou-se 16 ovinos da raça Santa Inês, com idade média de 3 meses e peso aproximado de 19 kg, durante 19 dias, sendo 14 de adaptação e cinco dias de coleta de dados e amostras em gaiolas metabólicas. E para o desempenho, 15 machos com 4 meses de idade, da mesma raça, com peso aproximado de 20 kg por 56 dias, distribuídos em um delineamento em blocos ao acaso em quatro tratamentos : 0, 25, 50 e 75% de inclusão da torta de dendê no concentrado, com dietas compostas por 40% (base matéria seca) de silagem de capim-elefante (Pennisetum purpureum Schum) e 60% de concentrado composto por grão de milho, farelo de soja, torta de dendê e minerais. Analisando os dados verificou-se redução linear no consumo de matéria seca com a inclusão da torta de dendê, porém não houve diferença estatística significativa na digestibilidade da matéria seca. Notou-se ainda um aumento da digestibilidade da FDN e FDA em dietas com maior proporção de torta de dendê. No ensaio de desempenho, observou-se redução linear no ganho de peso dos animais conforme se aumentou o teor de torta de dendê na dieta, resultado do menor consumo de matéria seca (p<0,05), piorando a conversão alimentar. A torta de dendê é potencialmente produtiva, com alta disponibilidade de matéria seca e bom valor nutritivo. Constitui uma boa alternativa para ser utilizada como suplemento alimentar para ovinos, porém em níveis mais elevados pode reduzir o desempenho animal, sendo a sua utilização dependente do preço de aquisição e da relação custo: beneficío.

Composição corporal e exigências nutricionais de energia e proteína de tourinhos Santa Gertrudes confinados, recebendo alto concentrado e subproduto da produção de lisina

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Metabolic profile response to administration of epigallocatechin-3-gallate in high-fat-fed mice

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

High sodium intake during postnatal phases induces an increase in arterial blood pressure in adult rats

Coordenadoria de Aperfeiçoamento em Pesquisa (CAPES)

Western diet, but not high fat diet, causes derangements of fatty acid metabolism and contractile dysfunction in the heart of Wistar rats.

Obesity and diabetes are associated with increased fatty acid availability in excess of muscle fatty acid oxidation capacity. This mismatch is implicated in the pathogenesis of cardiac contractile dysfunction and also in the development of skeletal-muscle insulin resistance. We tested the hypothesis that 'Western' and high fat diets differentially cause maladaptation of cardiac- and skeletal-muscle fatty acid oxidation, resulting in cardiac contractile dysfunction. Wistar rats were fed on low fat, 'Western' or high fat (10, 45 or 60% calories from fat respectively) diet for acute (1 day to 1 week), short (4-8 weeks), intermediate (16-24 weeks) or long (32-48 weeks) term. Oleate oxidation in heart muscle ex vivo increased with high fat diet at all time points investigated. In contrast, cardiac oleate oxidation increased with Western diet in the acute, short and intermediate term, but not in the long term. Consistent with fatty acid oxidation maladaptation, cardiac power decreased with long-term Western diet only. In contrast, soleus muscle oleate oxidation (ex vivo) increased only in the acute and short term with either Western or high fat feeding. Fatty acid-responsive genes, including PDHK4 (pyruvate dehydrogenase kinase 4) and CTE1 (cytosolic thioesterase 1), increased in heart and soleus muscle to a greater extent with feeding a high fat diet compared with a Western diet. In conclusion, we implicate inadequate induction of a cassette of fatty acid-responsive genes, and impaired activation of fatty acid oxidation, in the development of cardiac dysfunction with Western diet.

Adaptation and maladaptation of heart and skeletal muscle to different diets in a rodent model of human obesity

Obesity and diabetes are metabolic disorders associated with fatty acid availability in excess of the tissues' capacity for fatty acid oxidation. This mismatch is implicated in the pathogenesis of cardiac contractile dysfunction and also in skeletal muscle insulin resistance. My dissertation will present work to test the overall hypothesis that "western" and high fat diets differentially affect cardiac and skeletal muscle fatty acid oxidation, the expression of fatty acid responsive genes, and cardiac contractile function. Wistar rats were fed a low fat, "western," or high fat (10%, 45%, or 60% calories from fat, respectively) diet for acute (1 day to 1 week), short (4 to 8 weeks), intermediate (16 to 24 weeks), or long (32 to 48 weeks) term. With high fat diet, cardiac oleate oxidation increased at all time points investigated. In contrast, with western diet cardiac oleate oxidation increased in the acute, short and intermediate term, but not in the long term. Consistent with a maladaptation of fatty acid oxidation, cardiac power (measured ex vivo) decreased with long term western diet only. In contrast to the heart, soleus muscle oleate oxidation increased only in the acute and short term with either western or high fat feeding. Transcript analysis revealed that several fatty acid responsive genes, including pyruvate dehydrogenase kinase 4, uncoupling protein 3, mitochondrial thioesterase 1, and cytosolic thioesterase 1 increased in heart and soleus muscle to a greater extent with high fat diet, versus western diet, feeding. In conclusion, the data implicate inadequate induction of a cassette of fatty acid responsive genes in both the heart and skeletal muscle by western diet resulting in impaired activation of fatty acid oxidation, and the development of cardiac dysfunction. ^