title: Nutritional regulation of the anabolic fate of amino acids within the liver in mammals: concepts arising from in vivo studies.
abstract: At the crossroad between nutrient supply and requirements, the liver plays a central role in partitioning nitrogenous nutrients among tissues. The present review examines the utilisation of amino acids (AA) within the liver in various physiopathological states in mammals and how the fates of AA are regulated. AA uptake by the liver is generally driven by the net portal appearance of AA. This coordination is lost when demands by peripheral tissues is important (rapid growth or lactation), or when certain metabolic pathways within the liver become a priority (synthesis of acute-phase proteins). Data obtained in various species have shown that oxidation of AA and export protein synthesis usually responds to nutrient supply. Gluconeogenesis from AA is less dependent on hepatic delivery and the nature of nutrients supplied, and hormones like insulin are involved in the regulatory processes. Gluconeogenesis is regulated by nutritional factors very differently between mammals (glucose absorbed from the diet is important in single-stomached animals, while in carnivores, glucose from endogenous origin is key). The underlying mechanisms explaining how the liver adapts its AA utilisation to the body requirements are complex. The highly adaptable hepatic metabolism must be capable to deal with the various nutritional/physiological challenges that mammals have to face to maintain homeostasis. Whereas the liver responds generally to nutritional parameters in various physiological states occurring throughout life, other complex signalling pathways at systemic and tissue level (hormones, cytokines, nutrients, etc.) are involved additionally in specific physiological/nutritional states to prioritise certain metabolic pathways (pathological states or when nutritional requirements are uncovered).
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, Massey University,Palmerston North,New Zealand.
authors.forename: T J
authors.initials: TJ
authors.lastname: Wester
authors.affiliation: Institut National de la Recherche Agronomique,UMR 1213 INRA-VetAgroSup, Unité Mixte de Recherches sur les Herbivores, 63122 St Genès Champanelle,France.
authors.forename: G
authors.initials: G
authors.lastname: Kraft
authors.affiliation: Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine,BP 10448, F-63000Clermont-Ferrand,France.
authors.forename: D
authors.initials: D
authors.lastname: Dardevet
authors.affiliation: Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine,BP 10448, F-63000Clermont-Ferrand,France.
authors.forename: S
authors.initials: S
authors.lastname: Polakof
authors.affiliation: Institut National de la Recherche Agronomique,UMR 1213 INRA-VetAgroSup, Unité Mixte de Recherches sur les Herbivores, 63122 St Genès Champanelle,France.
authors.forename: I
authors.initials: I
authors.lastname: Ortigues-Marty
authors.affiliation: Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine,BP 10448, F-63000Clermont-Ferrand,France.
authors.forename: D
authors.initials: D
authors.lastname: Rémond
authors.affiliation: Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine,BP 10448, F-63000Clermont-Ferrand,France.
authors.forename: I
authors.initials: I
authors.lastname: Savary-Auzeloux
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002335:Carnivora / Q000378:metabolism; D004435:Eating; D004734:Energy Metabolism; D005502:Food; D005943:Gluconeogenesis; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007328:Insulin; D008099:Liver / Q000378:metabolism*; D009747:Nutritional Physiological Phenomena; D009751:Nutritional Requirements; D010084:Oxidation-Reduction; D014176:Protein Biosynthesis; D012418:Ruminants / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D007328:Insulin
keywords: Amino acids; Gluconeogenesis; Homeostasis; Liver