Effect of partial substitution of dietary protein by a single gluconeogenic dispensable amino acid on hepatic glucose metabolism in rainbow trout (Oncorhynchus mykiss).
Our objective was to understand the influence of dietary gluconeogenic amino acids on hepatic glucose metabolism in rainbow trout (Oncorhynchus mykiss). We analyzed the effects of partial substitution of dietary protein by a single gluconeogenic dispensable amino acid (DAA: alanine, aspartic acid or glutamic acid), on the regulation of hepatic glycolytic and gluconeogenic enzymes. We fed juvenile rainbow trout with isonitrogenous and isoenergetic diets in which part of nitrogen from fishmeal was replaced by nitrogen from one of the three DAA. Fish were fed over 9 weeks and samples withdrawn 6 h after feeding or 5 days after food deprivation. Our data did not show a clear effect of an excess of DAA on activities of glycolytic enzymes (glucokinase and pyruvate kinase) compared to the control diet. In contrast, feeding caused a significant repression of gluconeogenic enzyme activities (glucose-6-phosphatase, fructose-1,6-bisphosphatase and mitochondrial phosphoenolpyruvate carboxykinase) only in fish fed the three DAA substituted diets. However, these differences were insufficient to affect postprandial glycemia significantly. In conclusion, an excess of dietary DAA tested does not seem to modify glycemia or to have a negative impact on dietary carbohydrate utilization in rainbow trout.
Kirchner
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Laboratory of Fish Nutrition, INRA-IFREMER, 64310, St-Pée-sur-Nivelle, France.
Kaushik
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Panserat
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D000409:Alanine / Q000008:administration & dosage; D000596:Amino Acids / Q000008:administration & dosage*; D000818:Animals; D001224:Aspartic Acid / Q000008:administration & dosage; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage*; D019587:Dietary Supplements; D005508:Food Deprivation / Q000502:physiology; D006597:Fructose-Bisphosphatase / Q000378:metabolism; D005941:Glucokinase / Q000378:metabolism; D005943:Gluconeogenesis; D005947:Glucose / Q000378:metabolism*; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D018698:Glutamic Acid / Q000008:administration & dosage; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000201:enzymology; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
D000596:Amino Acids; D004044:Dietary Proteins; D012333:RNA, Messenger; D001224:Aspartic Acid; D018698:Glutamic Acid; D005941:Glucokinase; D011770:Pyruvate Kinase; D006597:Fructose-Bisphosphatase; D005952:Glucose-6-Phosphatase; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D005947:Glucose; D000409:Alanine