Whole-body and tissue protein synthesis during brief and prolonged fasting in the rat

Cherel, Yves; Attaix, Didier; Rosołowska-Huszcz, Danuta; Belkhou, Rajaê; Robin, Jean‐Patrice; Arnal, M.; Maho, Yvon Le

doi:10.1042/cs0810611

Cited by 65 publications

(46 citation statements)

References 25 publications

(40 reference statements)

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“…Non-linear responses in whole body ILR may be due to the impact of other tissues, particularly since the contribution of the hind-quarters (≈ 20%) is less important than that of the splanchnic tissues, for example (30-60% [8,[45][46][47]). These are also sensitive to intake [12,48,49] and these values can increase by approximately 40% when intake is raised from 1 to 2 M [49].…”

Section: Discussionmentioning

confidence: 99%

Effect of intake on whole body plasma amino acid kinetics in sheep

Savary-Auzeloux¹,

Hoskin

Lobley³

2003

Reprod. Nutr. Dev.

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-While both the quantity and quality of food ingested are potent regulators of whole body protein metabolism in ruminants, little data are available on responses across a wide range of intakes. The current study examined the responses in whole body protein flux (PrF) to such intake changes and compared these with the responses across the hind-quarters (in a companion study). Six growing sheep (6-8 months, 30-35 kg) received each of four intakes of dried grass pellets (0.5, 1.0, 1.5 and 2.5 times maintenance energy; M) for a minimum of 7 days. At each intake, a mixture of U-13 C amino-acids (AA) was infused intravenously for 10 h. Arterial plasma and blood were obtained over the last 4 h of infusion and the concentrations and the enrichments of thirteen 13 C labelled AA were determined. The absolute values for plasma Irreversible Loss Rate (ILR) but also converted PrF varied between the AA. PrF values were lower for histidine, methionine, aspartate, glycine and proline (range 68 to 174 g·d -1 at 1.5 M) than for isoleucine, leucine, valine and glutamate (range 275 to 400 g·d -1 at 1.5 M). These discrepancies may be explained by (1) the differential AA removal by the splanchnic tissues, (2) the de novo synthesis of the non-essential AA, (3) the transfer of AA from the erythrocytes or plasma to the tissues. The first two assumptions require further investigation whereas recent work has shown a minor role for AA transfers between erythrocytes and tissues. For most AA, ILR and PrF responded linearly to intake but curvilinear responses were observed for phenylalanine, lysine, leucine, isoleucine and tyrosine. These differences were not due to hind-quarter metabolism and may involve the digestive tract and liver.intake / whole body / kinetics / ovine / amino acid Reprod. Nutr. Dev. 43 (2003) 117-129 117

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Section: Discussionmentioning

confidence: 99%

Effect of intake on whole body plasma amino acid kinetics in sheep

Savary-Auzeloux¹,

Hoskin

Lobley³

2003

Reprod. Nutr. Dev.

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“…[59] and on the fact that only 60 % of intestinal luminal arginine is absorbed intact into the portal circulation in the adult rat [191]. Endogenous flux of arginine was calculated on the basis of whole-body protein degradation (8.1 g/day) in the adult rat (394 g) [58] and arginine concentration in the rat (73 mg/g of protein) [57]. 7 Data are from Yu et al [60].…”

Section: Arginine Synthesismentioning

confidence: 99%

Arginine metabolism: nitric oxide and beyond

Morris

1998

Biochemical Journal

2,424

2,036

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Arginine is one of the most versatile amino acids in animal cells, serving as a precursor for the synthesis not only of proteins but also of nitric oxide, urea, polyamines, proline, glutamate, creatine and agmatine. Of the enzymes that catalyse rate-controlling steps in arginine synthesis and catabolism, argininosuccinate synthase, the two arginase isoenzymes, the three nitric oxide synthase isoenzymes and arginine decarboxylase have been recognized in recent years as key factors in regulating newly identified aspects of arginine metabolism. In particular, changes in the activities of argininosuccinate synthase, the arginases, the inducible isoenzyme of nitric oxide synthase and also cationic amino acid transporters play major roles in determining the metabolic fates of arginine in health and disease, and recent studies have identified

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“…During the initial phase of fasting the rate of weight loss is high but then declines to a minimum until the final, moribund phase with more rapid weight loss sets in (18,19). Based on whole-body energy expenditure, these three phases of weight loss were interpreted as reflecting successively the postabsorptive utilization of glycogen reserves, oxidation of fat (with a protein-sparing effect), and eventually the selfdestructive consumption of cell proteins (18,20).…”

Section: The Data Discussed In This Publication Have Been Deposited Imentioning

confidence: 99%

Interorgan Coordination of the Murine Adaptive Response to Fasting

Hakvoort

Moerland

Frijters

et al. 2011

Journal of Biological Chemistry

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Starvation elicits a complex adaptive response in an organism.No information on transcriptional regulation of metabolic adaptations is available. We, therefore, studied the gene expression profiles of brain, small intestine, kidney, liver, and skeletal muscle in mice that were subjected to 0 -72 h of fasting. Functional-category enrichment, text mining, and network analyses were employed to scrutinize the overall adaptation, aiming to identify responsive pathways, processes, and networks, and their regulation. The observed transcriptomics response did not follow the accepted "carbohydrate-lipid-protein" succession of expenditure of energy substrates. Instead, these processes were activated simultaneously in different organs during the entire period. The most prominent changes occurred in lipid and steroid metabolism, especially in the liver and kidney. They were accompanied by suppression of the immune response and cell turnover, particularly in the small intestine, and by increased proteolysis in the muscle. The brain was extremely well protected from the sequels of starvation. 60% of the identified overconnected transcription factors were organ-specific, 6% were common for 4 organs, with nuclear receptors as protagonists, accounting for almost 40% of all transcriptional regulators during fasting. The common transcription factors were PPAR␣, HNF4␣, GCR␣, AR (androgen receptor), SREBP1 and -2, FOXOs, EGR1, c-JUN, c-MYC, SP1, YY1, and ETS1. Our data strongly suggest that the control of metabolism in four metabolically active organs is exerted by transcription factors that are activated by nutrient signals and serves, at least partly, to prevent irreversible brain damage.Adapting to starvation requires an interorgan integration of the activity of metabolic pathways to protect the body from an irreversible loss of resources (1, 2), but how the organism integrates these reactions remains largely unknown. Numerous studies on humans, who fasted for 3-6 weeks, have shown that glycogen stores are depleted within a day (3). The decline in circulating glucose and insulin during the next few days (4) induces a transient increase in plasma (essential) amino acids and a concomitant decline in plasma alanine levels due to an increased hepatic extraction for gluconeogenesis (5, 6). Muscle catabolism is a major source of amino acids in this phase. When fasting is continued, muscle protein catabolism declines, and hepatic uptake of amino acids decreases, which is reflected in a decline of endogenous glucose production (6) and urinary nitrogen excretion (4, 7). Lipid catabolism and the (hepatic) production of ketone bodies also increases rapidly and is quantitatively similar after 3 days and 5-6 weeks of starvation (8), but plasma levels increase only gradually to plateau after 4 weeks (4, 9). The associated increase in urinary ketone body (organic-acid) excretion requires a compensatory increase in ammonia production and urinary excretion (4, 7, 10), which is met by an increased renal amino acid uptake and gluconeogenesis (5, 6)...

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Whole-body and tissue protein synthesis during brief and prolonged fasting in the rat

Cited by 65 publications

References 25 publications

Effect of intake on whole body plasma amino acid kinetics in sheep

Effect of intake on whole body plasma amino acid kinetics in sheep

Arginine metabolism: nitric oxide and beyond

Interorgan Coordination of the Murine Adaptive Response to Fasting

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