Maternal protein restriction induce skeletal muscle changes without altering the MRFs MyoD and myogenin expression in offspring.

Stimuli during pregnancy, such as protein restriction, can affect morphophysiological parameters in the offspring with consequences in adulthood. The phenomenon known as fetal programming can cause short- and long-term changes in the skeletal muscle phenotype. We investigated the morphology and the myogenic regulatory factors (MRFs) MyoD and myogenin expression in soleus, SOL; oxidative and slow twitching and in extensor digitorum longus, EDL; glycolytic and fast twitching muscles in the offspring of dams subjected to protein restriction during pregnancy. Four groups of male Wistar offspring rats were studied. Offspring from dams fed a low-protein diet (6 % protein, LP) and normal protein diet (17 % protein, NP) were euthanized at 30 and 112 days old, and their muscles were removed and kept at -80 °C. Muscles histological sections (8 µm) were submitted to a myofibrillar adenosine triphosphatase histochemistry reaction for morphometric analysis. Gene and protein expression levels of MyoD and myogenin were determined by RT-qPCR and western blotting. The major findings observed were distinct patterns of morphological changes in SOL and EDL muscles in LP offspring at 30 and 112 days old without changes in MRFs MyoD and myogenin expression. Our results indicate that maternal protein restriction followed by normal diet after birth induced morphological changes in muscles with distinct morphofunctional characteristics over the long term, but did not alter the MRFs MyoD and myogenin expression. Further studies are necessary to better understand the mechanisms underlying the maternal protein restriction response on skeletal muscle.

Dieta hiperlipídica com farinha de soja como fonte proteica: utilização na seleção de ratos propensos e resistentes à obesidade / High-fat diet using soybean meal as protein source: use for selecting rats prone and resistant to obesity

OBJETIVO: Desenvolver uma dieta hiperlipídica de baixo custo, tendo farinha de soja como fonte proteica, que seja eficiente na seleção de ratos propensos e resistentes à obesidade e que permita alcançar fenótipo obeso nos animais propensos. Além desses requisitos, a dieta deve ser palatável e não rejeitada a curto prazo pelo animal. MÉTODOS: A dieta proposta foi obtida misturando-se leite condensado (15,5 por cento), amendoim (18,5 por cento), farinha de soja (20,0 por cento), óleo de milho (6,0 por cento), ração Bio Tec (30,0 por cento) e bolacha wafer de chocolate (10,0 por cento). A mistura foi peletizada e submetida à análise bromatológica. A dieta foi ofertada a ratos Wistar durante uma semana; posteriormente, os animais foram divididos em três grupos, de acordo com o ganho de peso. O terço superior foi considerado propenso à obesidade e o terço inferior, resistente à obesidade. Após 80 dias de oferta da dieta, os animais foram sacrificados e foram quantificados o peso corpóreo, consumo alimentar, gorduras retroperitoneal, periepididimal, de carcaça e gorduras totais. RESULTADOS: Verificou-se que a dieta apresentava 5,31kcal/g, com a seguinte composição: 22,3 por cento de gordura, 22,2 por cento de proteína, 15,9 por cento de fibra, estimando-se 35,7 por cento de carboidrato. Ratos propensos à obesidade, alimentados por 87 dias com a dieta hipercalórica, apresentaram peso corpóreo, gorduras retroperitoneal, periepididimal e totais significativamente maiores do que animais resistentes à obesidade (p<0,05). O consumo de alimentos também foi maior em animais propensos (p<0,05). Verificou-se também que a substituição da caseína pela farinha de soja, como componente proteico da ração, levou à diminuição de 96,0 por cento no custo do estudo. CONCLUSÃO: A dieta formulada com farinha de soja apresentou custo reduzido e foi capaz de desenvolver o fenótipo obeso em ratos propensos, à semelhança do observado na literatura com outras dietas.

OBJECTIVE: The objective was to develop a high-fat, low cost diet, using soybean meal as protein source. This diet should effectively discriminate between rats prone and resistant to obesity and allow the obese phenotype to be achieved in the animals that are prone to obesity. Furthermore, the diet must be palatable and not be rejected by the animal in the short run. METHODS: The chow was obtained by mixing the following ingredients: condensed milk (15.5 percent), peanuts (18.5 percent), soybean meal (20.0 percent), corn oil (6.0 percent), Bio Tec chow (30.0 percent) and chocolate wafer cookies (10.0 percent). In order to make it appropriate for rats, the mixture was pelleted and subjected to food analysis. The chow was offered to Wistar rats for a week. The animals were subsequently separated according to weight gained. The upper third group was considered prone to obesity and the lower third group was considered resistant to obesity. The animals were sacrificed 80 days later to determine body weight, food intake, retroperitoneal, periepididymal and carcass fats and total fats. RESULTS: Food analysis found that the chow had an energy density of 5.31 Kcal/g, 22.3 percent fat, 22.2 percent protein, 15.9 percent fiber and 35.7 percent carbohydrates. After being fed for 87 days with the high-fat diet, obesity-prone rats had higher body weight and retroperitoneal, periepididymal and total fats than obesity-resistant animals (p<0.05). Food intake was also higher among obesity-prone rats (p<0.05). The replacement of casein by soybean meal as protein source reduced the cost of the study by 96.0 percent. CONCLUSION: The substitution of casein by soybean meal in a high-fat diet allows cost reduction and the identification of obese-prone rats. Continuous use of this high-fat diet resulted in the development of the obese phenotype, as seen with other diets used in the literature.