Determinação do turnover proteico e suplementação com aminoácidos de cadeia ramificada, arginina e ácido docosahexaenóico para controle da sarcopenia em cães idosos
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Data
2022-04-05
Autores
Pacheco, Letícia Graziele [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A fim de se aprofundar estudos acerca do metabolismo proteico, foram comparados quatro métodos para se determinar o fluxo de proteína em cães adultos e idosos, bem como avaliar os efeitos do fornecimento de uma dieta enriquecida com ácido docosaexaenoico (DHA), arginina e aminoácidos de cadeia ramificada (ACR) sobre o metabolismo de proteína. O primeiro experimento teve por objetivo estudar e padronizar os métodos de utilização dos compostos marcados. O segundo experimento comparou os métodos de determinação do turnover proteico com 13C-Leucina, 13C-Fenilalanina e 15N-Glicina em cães adultos e idosos. Para isto foram avaliadas a digestibilidade, balanço de nitrogênio e fluxo proteico em arranjo fatorial 4x2 (4 métodos e 2 faixas etárias). No terceiro experimento foram avaliadas em cães adultos e idosos duas dietas, uma controle e outra suplementada com DHA, arginina e ACR. Foi adotado delineamento cross over e arranjo fatorial 2x2, com duas dietas (Controle x Teste) e duas faixas etárias (adultos x idosos). Na dieta teste a quantidade analisada de DHA, leucina, isoleucina, valina e arginina foram, respectivamente, 100%, 72%, 22%, 18%, e 35% maiores do que na dieta controle. No primeiro estudo os métodos não diferiram em si, obtendo-se resultados semelhantes de síntese e degradação proteica (P>0,05). Após esta experiência, os procedimentos experimentais de aplicação dos métodos foram melhorados para os estudos seguintes. No segundo experimento foi observado efeito de idade no metabolismo de proteína (P<0,05) sem efeito de métodos (P>0,05). Pelos quatro métodos de estudo, em média as taxas de síntese e degradação de proteína foram, respectivamente, 19% e 21% menores nos idosos em comparação aos adultos (P<0,05). Não houve efeito, no entanto, em digestibilidade e balanço de nitrogênio (P>0,05). Estes resultados suportam hipótese que alterações metabólicas sejam uma das causas implicadas no desenvolvimento de sarcopenia em cães. No terceiro experimento foi observado efeito de dieta, sendo que a suplementação nutricional proposta elevou o fluxo de proteína corporal dos cães (P<0,05), tanto em adultos como idosos. Apesar de estatisticamente semelhante, esta elevação foi 42% maior em adultos em comparação com idosos. Adicionalmente, ao final do período de recebimento das dietas experimentais, tendência à maior massa magra corporal (kg) foi observada para idosos alimentados com a dieta teste em comparação à controle (P=0,06). Como conclusão, os quatro métodos avaliados foram equivalentes na determinação de síntese e degradação de proteína. A suplementação alimentar com DHA, ACR e arginina elevou o fluxo proteico, podendo favorecer a desaceleração da perda de massa muscular e controle da sarcopenia, merecendo estudos de longo prazo.
To develop better study protocols to access protein metabolism, four methods to estimate protein flux was compared in adult and old dogs. The dietary supply of docosahexaenoic acid (DHA), branched-chain amino acids (BCA), and arginine was also evaluated. The first study aimed to investigate and standardize methods of study protein metabolism with stable isotopes. The second experiment compared the methods of 13CLeucine, 13C-Phenylalanine, 15N-Glycine in adult and old dogs. Nutrient digestibility, nitrogen balance, and protein flow were evaluated in a 4 (methods) x 2 (ages) factorial arrangement. The third study compared two diets in adult and old dogs, a control and a test diet supplemented with DHA, arginine, and BCA. A cross over design and a 2 (diets) x 2 (ages) factorial arrangement was adopted. The test diet presented analyzed values of DHA, arginine, leucine, isoleucine and valine 100%, 35%, 72%, 22% and 18% higher, respectively, than the control treatment. In the first study, similar results of protein synthesis and degradation was observed for all evaluated methods (P>0.05). After this experience, the protocol of the stable isotopes’ application was improved for the other studies. On study two, an age effect was observed for protein flow (P>0.05), without effect of method (P<0.05). Considering the four methods studied, the mean rates of protein synthesis and breakdown was, respectively, 19% and 21% lower in old than adult dogs (P<0.05). No age effect was observed for nutrient digestibility and nitrogen balance (P>0.05). These results support the hypothesis that metabolic alterations are involved on sarcopenia development in old dogs. On the third study a diet effect was observed: both in adult and old dogs fed the supplemented food higher protein flow was observed than for animals fed the control diet (P>0.05). Although statistically similar, this increase in protein flow was 42% higher for adult than for old dogs. In addition, at the end of the period of diet intake a tendency for higher lean body mass was observed for old dogs fed the supplemented food in comparison to control (P=0.06). As conclusion, the four methods evaluated was adequate with similar results of protein synthesis and degradation. A diet supplementation with DHA, arginine and BCA increased the protein flow rate, possibly reducing sarcopenia development, deserving future studies.
To develop better study protocols to access protein metabolism, four methods to estimate protein flux was compared in adult and old dogs. The dietary supply of docosahexaenoic acid (DHA), branched-chain amino acids (BCA), and arginine was also evaluated. The first study aimed to investigate and standardize methods of study protein metabolism with stable isotopes. The second experiment compared the methods of 13CLeucine, 13C-Phenylalanine, 15N-Glycine in adult and old dogs. Nutrient digestibility, nitrogen balance, and protein flow were evaluated in a 4 (methods) x 2 (ages) factorial arrangement. The third study compared two diets in adult and old dogs, a control and a test diet supplemented with DHA, arginine, and BCA. A cross over design and a 2 (diets) x 2 (ages) factorial arrangement was adopted. The test diet presented analyzed values of DHA, arginine, leucine, isoleucine and valine 100%, 35%, 72%, 22% and 18% higher, respectively, than the control treatment. In the first study, similar results of protein synthesis and degradation was observed for all evaluated methods (P>0.05). After this experience, the protocol of the stable isotopes’ application was improved for the other studies. On study two, an age effect was observed for protein flow (P>0.05), without effect of method (P<0.05). Considering the four methods studied, the mean rates of protein synthesis and breakdown was, respectively, 19% and 21% lower in old than adult dogs (P<0.05). No age effect was observed for nutrient digestibility and nitrogen balance (P>0.05). These results support the hypothesis that metabolic alterations are involved on sarcopenia development in old dogs. On the third study a diet effect was observed: both in adult and old dogs fed the supplemented food higher protein flow was observed than for animals fed the control diet (P>0.05). Although statistically similar, this increase in protein flow was 42% higher for adult than for old dogs. In addition, at the end of the period of diet intake a tendency for higher lean body mass was observed for old dogs fed the supplemented food in comparison to control (P=0.06). As conclusion, the four methods evaluated was adequate with similar results of protein synthesis and degradation. A diet supplementation with DHA, arginine and BCA increased the protein flow rate, possibly reducing sarcopenia development, deserving future studies.
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Palavras-chave
Geriatria, Leucina, Massa corporal magra, Sarcopenia, Isótopos estáveis