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Moinard C, Tliba L, Diaz J, Le Plénier S, Nay L, Neveux N, Cynober L, Raynaud-Simon A. Citrulline stimulates locomotor activity in aged rats: Implication of the dopaminergic pathway. Nutrition 2017; 38:9-12. [DOI: 10.1016/j.nut.2017.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/21/2016] [Accepted: 01/01/2017] [Indexed: 12/20/2022]
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Alpha-Ketoglutarate as a Molecule with Pleiotropic Activity: Well-Known and Novel Possibilities of Therapeutic Use. Arch Immunol Ther Exp (Warsz) 2016; 65:21-36. [PMID: 27326424 PMCID: PMC5274648 DOI: 10.1007/s00005-016-0406-x] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 02/22/2016] [Indexed: 12/17/2022]
Abstract
Alpha-ketoglutarate (AKG), an endogenous intermediary metabolite in the Krebs cycle, is a molecule involved in multiple metabolic and cellular pathways. It functions as an energy donor, a precursor in the amino acid biosynthesis, a signalling molecule, as well as a regulator of epigenetic processes and cellular signalling via protein binding. AKG is an obligatory co-substrate for 2-oxoglutarate-dependent dioxygenases, which catalyse hydroxylation reactions on various types of substrates. It regulates the activity of prolyl-4 hydroxylase, which controls the biosynthesis of collagen, a component of bone tissue. AKG also affects the functioning of prolyl hydroxylases, which, in turn, influences the function of the hypoxia-inducible factor, an important transcription factor in cancer development and progression. Additionally, it affects the functioning of enzymes that influence epigenetic modifications of chromatin: ten-eleven translocation hydroxylases involved in DNA demethylation and the Jumonji C domain containing lysine demethylases, which are the major histone demethylases. Thus, it regulates gene expression. The metabolic and extrametabolic function of AKG in cells and the organism open many different fields for therapeutic interventions for treatment of diseases. This review presents the results of studies conducted with the use of AKG in states of protein deficiency and oxidative stress conditions. It also discusses current knowledge about AKG as an immunomodulatory agent and a bone anabolic factor. Additionally, the regulatory role of AKG and its structural analogues in carcinogenesis as well as the results of studies of AKG as an anticancer agent are discussed.
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Moinard C, Le Plenier S, Noirez P, Morio B, Bonnefont-Rousselot D, Kharchi C, Ferry A, Neveux N, Cynober L, Raynaud-Simon A. Citrulline Supplementation Induces Changes in Body Composition and Limits Age-Related Metabolic Changes in Healthy Male Rats. J Nutr 2015; 145:1429-37. [PMID: 26019250 DOI: 10.3945/jn.114.200626] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 04/28/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Aging is associated with profound metabolic disturbances, and citrulline may be of use to limit them. OBJECTIVE The aim of this work was to evaluate the long-term effect of citrulline supplementation on metabolism in healthy aged rats. METHODS Twenty-month-old male rats were randomly assigned to be fed (ad libitum) for 12 wk with either a citrulline-enriched diet (1 g ⋅ kg(-1) ⋅ d(-1)) or a standard diet [rendered isonitrogenous by addition of nonessential amino acids (NEAAs)]. Motor activity and muscle strength were measured, body composition was assessed, and muscle metabolism (protein structure, mitochondrial exploration, and transductional factors) and lipid metabolism (lipoprotein composition and sensitivity to oxidative stress) were explored. RESULTS Compared with the NEAA-treated group, citrulline supplementation was associated with lower mortality (0% vs. 20%; P = 0.05), 9% higher lean body mass (P < 0.05), and 13% lower fat mass (P < 0.05). Compared with the NEAA-treated group, citrulline-treated rats had greater muscle mass (+14-48% depending on type of muscle; P < 0.05 for tibialis, gastrocnemius, and plantaris). Susceptibility to oxidation of lipoproteins, as measured by the maximal concentration of 7-ketocholesterol after copper-induced VLDL and LDL oxidation, was lower in citrulline-treated rats than in NEAA-treated rats (187 ± 8 μmol/L vs. 243 ± 7 μmol/L; P = 0.0005). CONCLUSIONS Citrulline treatment in male aged rats favorably modulates body composition and protects against lipid oxidation and, thus, emerges as an interesting candidate to help prevent the aging process.
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Affiliation(s)
| | | | - Philippe Noirez
- Department of Experimental, Metabolic, and Clinical Biology, EA 4466
| | - Béatrice Morio
- National Institute for Agronomic Research, Mixed Research Unit 1019, Human Nutrition Unit, Human Nutrition Research Center Auvergne and Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine, Clermont-Ferrand, France
| | - Dominique Bonnefont-Rousselot
- Faculty of Pharmaceutical and Biological Sciences, University Paris Descartes, Sorbonne Paris Cité, Paris, France; Public Assistance of Parisian Hospital (AP-HP), Hôpitaux Universitaires Hôpital Pitié-Salpêtrière-Charles Foix, Service de Biochimie Métabolique, Paris, France
| | - Caroline Kharchi
- Animalerie Centrale, Faculté des Sciences Pharmaceutiques et Biologiques de l'Université Paris Descartes, Paris, France
| | - Arnaud Ferry
- National Institute for Medical Research U974, National Scientific Research Center, Mixed Research Unit 7215, Institut de Myologie, Université Pierre et Marie Curie, Université Paris Descartes, Paris, France
| | - Nathalie Neveux
- Department of Experimental, Metabolic, and Clinical Biology, EA 4466, Service Biochimie Interhospitalier Hôtel-Dieu et Cochin, Public Assistance of Parisian Hospital, Paris, France; and
| | - Luc Cynober
- Department of Experimental, Metabolic, and Clinical Biology, EA 4466, Service Biochimie Interhospitalier Hôtel-Dieu et Cochin, Public Assistance of Parisian Hospital, Paris, France; and
| | - Agathe Raynaud-Simon
- Department of Experimental, Metabolic, and Clinical Biology, EA 4466, Département de Gériatrie, Hôpitaux Universitaires Bichat et Beaujon, AP-HP, Faculté de Médecine Paris Diderot, Paris, France
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Jourdan M, Cynober L, Moinard C, Blanc MC, Neveux N, De Bandt JP, Aussel C. Splanchnic sequestration of amino acids in aged rats: in vivo and ex vivo experiments using a model of isolated perfused liver. Am J Physiol Regul Integr Comp Physiol 2007; 294:R748-55. [PMID: 18056986 DOI: 10.1152/ajpregu.00291.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Splanchnic sequestration of amino acids (SSAA) is a process observed during aging that leads to decreased peripheral amino acid (AA) availability. The mechanisms underlying SSAA remain unknown. The aim of the present study was to determine whether a high-protein diet could increase nitrogen retention in aged rats by saturating SSAA and whether SSAA could be explained by dysregulation of hepatic nitrogen metabolism. Adult and aged male Sprague-Dawley rats were housed in individual metabolic cages and fed a normal-protein (17% protein) or high-protein diet (27%) for 2 wk. Nitrogen balance (NB) was calculated daily. On day 14, livers were isolated and perfused for 90 min to study AA and urea fluxes. NB was lower in aged rats fed a normal-protein diet than in adults, but a high-protein diet restored NB to adult levels. Isolated perfused livers from aged rats showed decreased urea production and arginine uptake, together with a release of alanine (vs. uptake in adult rats) and a hepatic accumulation of alanine. The in vivo data suggest that SSAA is a saturable process that responds to an increase in dietary protein content. The hepatic metabolism of AA in aged rats is greatly modified, and urea production decreases. This result refutes the hypothesis that SSAA is associated with an increase in AA disposal via urea production.
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Affiliation(s)
- M Jourdan
- Laboratory of Biological Nutrition, René Descartes Paris 5 University, Paris, France
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