Dominique Dardevet | Institut National de la Recherche Agronomique (original) (raw)

Papers by Dominique Dardevet

Research paper thumbnail of The delayed recovery of the remobilized rat tibialis anterior muscle reflects a defect in proliferative and terminal differentiation that impairs early regenerative processes

Journal of cachexia, sarcopenia and muscle, 2015

The immobilization-induced tibialis anterior (TA) muscle atrophy worsens after cast removal and i... more The immobilization-induced tibialis anterior (TA) muscle atrophy worsens after cast removal and is associated with altered extracellular matrix (ECM) composition. The secreted protein acidic and rich in cysteine (Sparc) is an ECM component involved in Akt activation and in β-catenin stabilization, which controls protein turnover and induces muscle regulatory factors (MRFs), respectively. We hypothesized that ECM alterations may influence these intracellular signalling pathways controlling TA muscle mass. Six-month-old Wistar rats were subjected to hindlimb cast immobilization for 8 days (I8) or not (I0) and allowed to recover for 1 to 10 days (R1-10). The TA atrophy during remobilization correlated with reduced fibre cross-sectional area and thickening of endomysium. mRNA levels for Sparc increased during remobilization until R10 and for integrin-α7 and -β1 at I8 and R1. Integrin-linked kinase protein levels increased during immobilization and remobilization until R10. This was inve...

Research paper thumbnail of Antioxidant Supplementation Restores Defective Leucine Stimulation of Protein Synthesis in Skeletal Muscle from Old Rats1,2

Aging is characterized by a progressive loss of muscle mass that could be partly explained by a d... more Aging is characterized by a progressive loss of muscle mass that could be partly explained by a defect in the anabolic effect of food intake. We previously reported that this defect resulted from a decrease in the protein synthesis response to leucine in muscles from old rats. Because aging is associated with changes in oxidative status, we hypothesized that reactive

Research paper thumbnail of Assessment of protein modifications in liver of rats under chronic treatment with paracetamol (acetaminophen) using two complementary mass spectrometry-based metabolomic approaches

Journal of proteomics, Jan 24, 2015

Liver protein can be altered under paracetamol (APAP) treatment. APAP-protein adducts and other p... more Liver protein can be altered under paracetamol (APAP) treatment. APAP-protein adducts and other protein modifications (oxidation/nitration, expression) play a role in hepatotoxicity induced by acute overdoses, but it is unknown whether liver protein modifications occur during long-term treatment with non-toxic doses of APAP. We quantified APAP-protein adducts and assessed other protein modifications in the liver from rats under chronic (17 days) treatment with two APAP doses (0.5% or 1% of APAP in the diet w/w). A targeted metabolomic method was validated and used to quantify APAP-protein adducts as APAP-cysteine adducts following proteolytic hydrolysis. The limit of detection was found to be 7ng APAP-cysteine/mL hydrolysate i.e. an APAP-Cys to tyrosine ratio of 0.016‰. Other protein modifications were assessed on the same protein hydrolysate by untargeted metabolomics including a new strategy to process the data and identify discriminant molecules. These two complementary mass spec...

Research paper thumbnail of Chronic Intake of Sucrose Accelerates Sarcopenia in Older Male Rats through Alterations in Insulin Sensitivity and Muscle Protein Synthesis

The Journal of nutrition, Jan 25, 2015

Today, high chronic intake of added sugars is frequent, which leads to inflammation, oxidative st... more Today, high chronic intake of added sugars is frequent, which leads to inflammation, oxidative stress, and insulin resistance. These 3 factors could reduce meal-induced stimulation of muscle protein synthesis and thus aggravate the age-related loss of muscle mass (sarcopenia). Our aim was to determine if added sugars could accelerate sarcopenia and assess the capacity of antioxidants and anti-inflammatory agents to prevent this. For 5 mo, 16-mo-old male rats were starch fed (13% sucrose and 49% wheat starch diet) or sucrose fed (62% sucrose and 0% wheat starch diet) with or without rutin (5-g/kg diet), vitamin E (4 times), vitamin A (2 times), vitamin D (5 times), selenium (10 times), and zinc (+44%) (R) supplementation. We measured the evolution of body composition and inflammation, plasma insulin-like growth factor 1 (IGF-I) concentration and total antioxidant status, insulin sensitivity (oral-glucose-tolerance test), muscle weight, superoxide dismutase activity, glutathione conce...

Research paper thumbnail of Contrarily to whey and high protein diets, dietary free leucine supplementation cannot reverse the lack of recovery of muscle mass after prolonged immobilization during ageing

The Journal of physiology, Jan 15, 2012

During ageing, immobilization periods increase and are partially responsible of sarcopaenia by in... more During ageing, immobilization periods increase and are partially responsible of sarcopaenia by inducing a muscle atrophy which is hardly recovered from. Immobilization-induced atrophy is due to an increase of muscle apoptotic and proteolytic processes and decreased protein synthesis. Moreover, previous data suggested that the lack of muscle mass recovery might be due to a defect in protein synthesis response during rehabilitation. This study was conducted to explore protein synthesis during reloading and leucine supplementation effect as a nutritional strategy for muscle recovery. Old rats (22–24 months old) were subjected to unilateral hindlimb casting for 8 days (I8) and allowed to recover for 10–40 days (R10–R40). They were fed a casein (±leucine) diet during the recovery. Immobilized gastrocnemius muscles atrophied by 20%, and did not recover even at R40. Amount of polyubiquitinated conjugates and chymotrypsin- and trypsin-like activities of the 26S proteasome increased. These c...

Research paper thumbnail of Myostatin Gene Inactivation Prevents Skeletal Muscle Wasting in Cancer

Cancer Research, 2014

Cachexia is a muscle-wasting syndrome that contributes significantly to morbidity and mortality o... more Cachexia is a muscle-wasting syndrome that contributes significantly to morbidity and mortality of many patients with advanced cancers. However, little is understood about how the severe loss of skeletal muscle characterizing this condition occurs. In the current study, we tested the hypothesis that the muscle protein myostatin is involved in mediating the pathogenesis of cachexia-induced muscle wasting in tumor-bearing mice. Myostatin gene inactivation prevented the severe loss of skeletal muscle mass induced in mice engrafted with Lewis lung carcinoma (LLC) cells or in Apc Min/þ mice, an established model of colorectal cancer and cachexia. Mechanistically, myostatin loss attenuated the activation of muscle fiber proteolytic pathways by inhibiting the expression of atrophy-related genes, MuRF1 and MAFbx/Atrogin-1, along with autophagyrelated genes. Notably, myostatin loss also impeded the growth of LLC tumors, the number and the size of intestinal polyps in Apc Min/þ mice, thus strongly increasing survival in both models. Gene expression analysis in the LLC model showed this phenotype to be associated with reduced expression of genes involved in tumor metabolism, activin signaling, and apoptosis. Taken together, our results reveal an essential role for myostatin in the pathogenesis of cancer cachexia and link this condition to tumor growth, with implications for furthering understanding of cancer as a systemic disease. Cancer Res; 74(24); 7344-56. Ó2014 AACR.

Research paper thumbnail of Postprandial leucine deficiency failed to alter muscle protein synthesis in growing and adult rats

This study examined the effect of a specific acute postprandial leucine deficiency on skeletal mu... more This study examined the effect of a specific acute postprandial leucine deficiency on skeletal muscle protein synthesis in growing and adult rats. Because the anabolic action of dietary leucine supplementation is controversial, except during aging, we hypothesized that the maximum leucine effect might be already achieved for a normal postprandial rise of leucine. Preventing this rise during the 1- to 3-h period after feeding may reveal the leucine regulation. On the day of the experiment, rats were fasted (postabsorptive, PA group) or fed for 1 h a control meal (postprandial, control, PP group) or a leucine-poor meal (postprandial, PP-Leu group). Muscle protein synthesis was assessed in vivo, over the 1- to 3-h period after meal distribution, using the flooding dose method (L-1-(13)C phenylalanine). As expected, the postprandial increase in plasma free leucine was specifically abolished after feeding the leucine-poor meal, whereas all the other plasma free amino acids were roughly at normal postprandial levels. Plasma insulin increased after feeding in young rats but was constant in adult rats. Plasma insulin was similar whatever dietary leucine levels. Rates of muscle protein synthesis were stimulated by feeding in gastrocnemius and soleus muscles from young rats but only in gastrocnemius muscles from adult rats. The PP-Leu group did not differ from the control PP group regarding muscle protein synthesis. The rise in plasma free leucine is not required for the stimulation of muscle protein synthesis during the 1- to 3-h period after feeding young and adult rats, as previously observed in old rats.

Research paper thumbnail of A leucine-supplemented diet restores the defective postprandial inhibition of proteasome-dependent proteolysis in aged rat skeletal muscle

We tested the hypothesis that skeletal muscle ubiquitin-proteasome-dependent proteolysis is dysre... more We tested the hypothesis that skeletal muscle ubiquitin-proteasome-dependent proteolysis is dysregulated in ageing in response to feeding. In Experiment 1 we measured rates of proteasome-dependent proteolysis in incubated muscles from 8-and 22-month-old rats, proteasome activities, and rates of ubiquitination, in the postprandial and postabsorptive states. Peptidase activities of the proteasome decreased in the postabsorptive state in 22-month-old rats compared with 8-month-old animals, while the rate of ubiquitination was not altered. Furthermore, the down-regulation of in vitro proteasome-dependent proteolysis that prevailed in the postprandial state in 8-month-old rats was defective in 22-month-old rats. Next, we tested the hypothesis that the ingestion of a 5% leucine-supplemented diet may correct this defect. Leucine supplementation restored the postprandial inhibition of in vitro proteasome-dependent proteolysis in 22-month-old animals, by down-regulating both rates of ubiquitination and proteasome activities. In Experiment 2, we verified that dietary leucine supplementation had long-lasting effects by comparing 8-and 22-month-old rats that were fed either a leucine-supplemented diet or an alanine-supplemented diet for 10 days. The inhibited in vitro proteolysis was maintained in the postprandial state in the 22-month-old rats fed the leucine-supplemented diet. Moreover, elevated mRNA levels for ubiquitin, 14-kDa ubiquitin-conjugating enzyme E2, and C2 and X subunits of the 20S proteasome that were characteristic of aged muscle were totally suppressed in 22-month-old animals chronically fed the leucine-supplemented diet, demonstrating an in vivo effect. Thus the defective postprandial down-regulation of in vitro proteasome-dependent proteolysis in 22-month-old rats was restored in animals chronically fed a leucine-supplemented diet.

Research paper thumbnail of High Whey Protein Intake Delayed the Loss of Lean Body Mass in Healthy Old Rats, whereas Protein Type and Polyphenol/Antioxidant Supplementation Had No Effects

PLoS ONE, 2014

Our aim was to compare and combine 3 nutritional strategies to slow down the age-related loss of ... more Our aim was to compare and combine 3 nutritional strategies to slow down the age-related loss of muscle mass in healthy old rats: 1) increase protein intake, which is likely to stimulate muscle protein anabolism; 2) use leucine rich, rapidly digested whey proteins as protein source (whey proteins are recognized as the most effective proteins to stimulate muscle protein anabolism). 3) Supplement animals with a mixture of chamomile extract, vitamin E, vitamin D (reducing inflammation and oxidative stress is also effective to improve muscle anabolism). Such comparisons and combinations were never tested before. Nutritional groups were: casein 12% protein, whey 12% protein, whey 18% protein and each of these groups were supplemented or not with polyphenols/antioxidants. During 6 months, we followed changes of weight, food intake, inflammation (plasma fibrinogen and alpha-2-macroglobulin) and body composition (DXA). After 6 months, we measured muscle mass, in vivo and ex-vivo fed and post-absorptive muscle protein synthesis, ex-vivo muscle proteolysis, and oxidative stress parameters (liver and muscle glutathione, SOD and total antioxidant activities, muscle carbonyls and TBARS). We showed that although micronutrient supplementation reduced inflammation and oxidative stress, the only factor that significantly reduced the loss of lean body mass was the increase in whey protein intake, with no detectable effect on muscle protein synthesis, and a tendency to reduce muscle proteolysis. We conclude that in healthy rats, increasing protein intake is an effective way to delay sarcopenia.

Research paper thumbnail of Lack of muscle recovery after immobilization in old rats does not result from a defect in normalization of the ubiquitin-proteasome and the caspase-dependent apoptotic pathways

The Journal of Physiology, 2011

Non-technical summary Immobilization periods increase with age because of decreased mobility and/... more Non-technical summary Immobilization periods increase with age because of decreased mobility and/or because of increased pathological episodes that require bed-rest. Then, sarcopaenia might be partially explained by an impaired recovery of skeletal muscle mass after a catabolic state due to an imbalance of muscle protein metabolism, apoptosis and cellular regeneration. Mechanisms involved during muscle recovery have been little studied and in elderly they remain almost unknown. We show, in rats, that a short immobilization period during ageing initiated muscle atrophy that was indeed not recovered after 40 days. Immobilization was associated with an activation of both the ubiquitin-proteasome and the mitochondria-associated apoptotic pathways and the inflammatory and redox processes, and a decrease of cellular regeneration. We show that the lack of muscle recovery during ageing is not due to a defect in proteolysis or apoptosis down-regulation. These observations lead us to hypothesize that muscle protein synthesis activation after immobilization was altered during ageing.

Research paper thumbnail of Leucine supplementation improves muscle protein synthesis in elderly men independently of hyperaminoacidaemia

The Journal of Physiology, 2006

The present study was designed to assess the effects of dietary leucine supplementation on muscle... more The present study was designed to assess the effects of dietary leucine supplementation on muscle protein synthesis and whole body protein kinetics in elderly individuals. Twenty healthy male subjects (70 ± 1 years) were studied before and after continuous ingestion of a complete balanced diet supplemented or not with leucine. A primed (3.6 μmol kg −1 ) constant infusion (0.06 μmol kg −1 min −1 ) of L-[1-13 C]phenylalanine was used to determine whole body phenylalanine kinetics as well as fractional synthesis rate (FSR) in the myofibrillar fraction of muscle proteins from vastus lateralis biopsies. Whole body protein kinetics were not affected by leucine supplementation. In contrast, muscle FSR, measured over the 5-h period of feeding, was significantly greater in the volunteers given the leucine-supplemented meals compared with the control group (0.083 ± 0.008 versus 0.053 ± 0.009% h −1 , respectively, P < 0.05). This effect was due only to increased leucine availability because only plasma free leucine concentration significantly differed between the control and leucine-supplemented groups. We conclude that leucine supplementation during feeding improves muscle protein synthesis in the elderly independently of an overall increase of other amino acids. Whether increasing leucine intake in old people may limit muscle protein loss during ageing remains to be determined.

Research paper thumbnail of The Nature of the Ingested Protein Has No Effect on Lean Body Mass During Energy Restriction in Overweight Rats

Research paper thumbnail of Excessive Energy Intake Does Not Modify Fed-state Tissue Protein Synthesis Rates in Adult Rats

Research paper thumbnail of Dietary n-3 polyUnsaturated fatty acids are capable to enhance protein anabolism response to insulin but not to leucine in old rats

Nutrition, Metabolism and Cardiovascular Diseases, 2013

Research paper thumbnail of Effects of leucine supplementation and resistance exercise on dexamethasone-induced muscle atrophy and insulin resistance in rats

Nutrition, 2012

Objective: We aimed to evaluate the effects of resistance exercise (RE) and leucine (LEU) supplem... more Objective: We aimed to evaluate the effects of resistance exercise (RE) and leucine (LEU) supplementation on dexamethasone (DEXA)-induced muscle atrophy and insulin resistance. Methods: Male Wistar rats were randomly divided into DEXA (DEX), DEXA þ RE (DEX-RE), DEXA þ LEU (DEX-LEU), and DEXA þ RE þ LEU (DEX-RE-LEU) groups. Each group received DEXA 5 mg $ kg À1 $ d À1 for 7 d from drinking water and were pair-fed to the DEX group; LEU-supplemented groups received 0.135 g $ kg À1 $ d À1 through gavage for 7 d; the RE protocol was based on three sessions of squat-type exercise composed by three sets of 10 repetitions at 70% of maximal voluntary strength capacity. Results: The plantaris mass was significantly greater in both trained groups compared with the non-trained groups. Muscle cross-sectional area and fiber areas did not differ between groups. Both trained groups displayed significant increases in the number of intermediated fibers (IIa/IIx), a decreased number of fast-twitch fibers (IIb), an increased ratio of the proteins phospho Ser2448 / total mammalian target of rapamycin and phospho Thr389 /total 70-kDa ribosomal protein S6 kinase, and a decreased ratio of phospho Ser253 /total Forkhead box protein-3a. Plasma glucose was significantly increased in the DEX-LEU group compared with the DEX group and RE significantly decreased hyperglycemia. The DEX-LEU group displayed decreased glucose transporter-4 translocation compared with the DEX group and RE restored this response. LEU supplementation worsened insulin sensitivity and did not attenuate muscle wasting in rats treated with DEXA. Conversely, RE modulated glucose homeostasis and fiber type transition in the plantaris muscle. Conclusion: Resistance exercise but not LEU supplementation promoted fiber type transition and improved glucose homeostasis in DEXA-treated rats.

Research paper thumbnail of Spreading intake of a leucine-rich fast protein in energy-restricted overweight rats does not improve protein mass

Nutrition, 2012

Objective: Energy restriction decreases fat mass and fat-free mass. Our aim was to prevent the la... more Objective: Energy restriction decreases fat mass and fat-free mass. Our aim was to prevent the latter using type and timing of protein nutrition as tools. Methods: Young male Wistar rats were given a high-energy diet for 5 wk and then energy restricted and fed a high-protein diet containing caseins, milk-soluble proteins (MSP), or a casein-MSP mixture (n ¼ 9 per group) as the only source of protein for 3 wk. Food intake was spread over 12 h, whereas in a previous experiment rats consumed their daily ration within 2 to 3 h. Weight and food intake were recorded. The body composition was measured by dual-energy x-ray absorptiometry before and after energy restriction. After 3 wk, the hind-limb muscles, the kidney, intestine, liver, and spleen weights, metabolic plasma parameters, and the liver and extensor digitorum longus muscle protein synthesis rates were measured in the postprandial state. Results: The food intake was similar in all groups. Energy restriction induced a significant decrease in body weight and fat mass (P < 0.001) and stopped the slow growth of lean body mass, with no differences between groups. Among all tissues, a significant effect was detected only for the intestine (P ¼ 0.0012), with a higher weight in the casein group. Postprandial liver and muscle protein synthesis rates were not different between groups. Conclusion: When using a high-protein diet spread over 12 h, the nature of the protein intake has no influence on the sparing of lean body mass during energy restriction in young overweight rats.

Research paper thumbnail of Antioxidant supplementation had positive effects in old rat muscle, but through better oxidative status in other organs

Nutrition, 2010

Objective: Aged muscle is characterized by a defect in the ability of leucine to stimulate protei... more Objective: Aged muscle is characterized by a defect in the ability of leucine to stimulate protein synthesis. We showed previously that antioxidant supplementation improved the anabolic response to leucine of old muscle and reduced inflammation. The aim of the present study was to determine if the positive effects observed in muscle could be related to an improvement of local muscle oxidative status. Methods: Two groups of 20-mo-old male Wistar rats were supplemented or not with rutin, vitamin E, vitamin A, zinc, and selenium during 7 wk. We measured body weight, food intake, oxidative status in muscle and other tissues, gastrocnemius muscle proteolytic activities, and liver glutathione metabolism. Results: Antioxidant supplementation had no effect on muscle antioxidant capacity, superoxide dismutase activities, and myofibrillar protein carbonyl content and induced an increase in muscle cathepsin activities. In other tissues, antioxidant supplementation increased liver glutathione (reduced plus oxidized glutathione) content, reduced oxidative damage in the liver and spleen (as measured by g-keto-aldehyde content), and reduced heart thiobarbituric acid-reactive substances.

Research paper thumbnail of Leucine supplementation in rats induced a delay in muscle IR/PI3K signaling pathway associated with overall impaired glucose tolerance☆

The Journal of Nutritional Biochemistry, 2011

Although activation of the mammalian target of rapamycin complex/p70 S6 kinase (S6K1) pathway by ... more Although activation of the mammalian target of rapamycin complex/p70 S6 kinase (S6K1) pathway by leucine is efficient to stimulate muscle protein synthesis, it can also exert inhibition on the early steps of insulin signaling leading to insulin resistance. We investigated the impact of 5-week leucine supplementation on insulin signaling and sensitivity in 4-month old rats fed a 15% protein diet supplemented (LEU) or not (C) with 4.5% leucine. An oral glucose tolerance test was performed in each rat at the end of the supplementation and glucose transport was measured in vitro using isolated epitrochlearis muscles incubated with 2-deoxy-d-[(3)H]-glucose under increasing insulin concentrations. Insulin signaling was assessed on gastrocnemius at the postabsorptive state or 30 and 60 min after gavage with a nutrient bolus. Tyrosine phosphorylation of IRβ, IRS1 and PI3 kinase activity were reduced in LEU group 30 min after feeding (-36%, -36% and -38% respectively, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.05) whereas S6K1, S6rp and 4EBP1 phosphorylations were similar. Overall glucose tolerance was reduced in leucine-supplemented rats and was associated with accumulation of perirenal adipose tissue (+27%, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.05). Conversely, in vitro insulin-response of muscle glucose transport tended to be improved in leucine-supplemented rats. In conclusion, dietary leucine supplementation in adult rats induced a delay in the postprandial stimulation in the early steps of muscle insulin signaling without muscle resistance on insulin-induced glucose uptake. However, it resulted in overall glucose intolerance linked to increased local adiposity. Further investigations are necessary to clearly define the beneficial and/or deleterious effects of chronic dietary leucine supplementation in healthy subjects.

Research paper thumbnail of Presence of low-grade inflammation impaired postprandial stimulation of muscle protein synthesis in old rats

The Journal of Nutritional Biochemistry, 2010

Aging is characterized by a decline in muscle mass that could be explained by a defect in the reg... more Aging is characterized by a decline in muscle mass that could be explained by a defect in the regulation of postprandial muscle protein metabolism. This study was undertaken to examine a possible link between the development of low-grade inflammation (LGI) in elderly and the resistance of muscle protein synthesis and degradation pathways to food intake. Fifty-five 20-month-old-rats were studied for 5 months; blood was withdrawn once a month to assess plasma fibrinogen and alpha2-macroglobulin. Animals were then separated into two groups at 25 months old according to their inflammation status: a control non-inflamed (NI, n=24) and a low-grade inflamed group (LGI, n=23). The day of the experiment, rats received no food or a meal. Muscle protein synthesis was assessed in vivo using the flooding dose method ([1-(13)C]phenylalanine) and muscle phosphorylation of protein S6 kinase, and protein S6 was measured in gastrocnemius muscle. Muscle proteolysis was assessed in vitro using the epitrochlearis muscle. Postabsorptive muscle protein synthesis and proteolysis were similar in NI and LGI. After food intake, muscle protein synthesis was significantly stimulated in NI but remained unresponsive in LGI. Muscle proteolysis was similar in both groups whatever the inflammation and/or the nutritional status. In conclusion, we showed that development of LGI during aging may be responsible, at least in part, for the defect in muscle protein synthesis stimulation induced by food intake in rats. Our results suggested that the control of LGI development in elderly improve meal effect on muscle protein synthesis and consequently slow down sarcopenia.

Research paper thumbnail of Cysteine fluxes across the portal-drained viscera of enterally fed minipigs: effect of an acute intestinal inflammation

Amino Acids, 2011

Cysteine is considered as a conditionally indispensable amino acid. Its dietary supply should thu... more Cysteine is considered as a conditionally indispensable amino acid. Its dietary supply should thus be increased when endogenous synthesis cannot meet metabolic need, such as during inflammatory diseases. However, studies in animal models suggest a high first-pass extraction of dietary cysteine by the intestine, limiting the interest for an oral supplementation. We investigated here unidirectional fluxes of cysteine across the portal-drained viscera (PDV) of multi-catheterized minipigs, using simultaneous intragastric L-[(15)N] cysteine and intravenous L-[3,3D2] cysteine continuous infusions. We showed that in minipigs fed with an elemental enteral solution, cysteine first-pass extraction by the intestine is about 60% of the dietary supply, and that the PDV does not capture arterial cysteine. Beside dietary cysteine, the PDV release non-dietary cysteine (20% of the total cysteine release), which originates either from tissue metabolism or from reabsorption of endogenous secretion, such as glutathione (GSH) biliary excretion. Experimental ileitis induced by local administration of trinitrobenzene sulfonic acid, increased liver and ileal GSH fractional synthesis rate during the acute phase of inflammation, and increased whole body flux of cysteine. However, cysteine uptake and release by the PDV were not affected by ileitis, suggesting an adaptation of the intestinal sulfur amino acid metabolism in order to cover the additional requirement of cysteine linked to the increased GSH synthesis. We conclude that the small intestine sequesters large amounts of dietary cysteine during absorption, limiting its release into the bloodstream, and that the other tissues of the PDV (colon, stomach, pancreas, spleen) preferentially use circulating methionine or cysteine-containing peptides to cover their cysteine requirement.

Research paper thumbnail of The delayed recovery of the remobilized rat tibialis anterior muscle reflects a defect in proliferative and terminal differentiation that impairs early regenerative processes

Journal of cachexia, sarcopenia and muscle, 2015

The immobilization-induced tibialis anterior (TA) muscle atrophy worsens after cast removal and i... more The immobilization-induced tibialis anterior (TA) muscle atrophy worsens after cast removal and is associated with altered extracellular matrix (ECM) composition. The secreted protein acidic and rich in cysteine (Sparc) is an ECM component involved in Akt activation and in β-catenin stabilization, which controls protein turnover and induces muscle regulatory factors (MRFs), respectively. We hypothesized that ECM alterations may influence these intracellular signalling pathways controlling TA muscle mass. Six-month-old Wistar rats were subjected to hindlimb cast immobilization for 8 days (I8) or not (I0) and allowed to recover for 1 to 10 days (R1-10). The TA atrophy during remobilization correlated with reduced fibre cross-sectional area and thickening of endomysium. mRNA levels for Sparc increased during remobilization until R10 and for integrin-α7 and -β1 at I8 and R1. Integrin-linked kinase protein levels increased during immobilization and remobilization until R10. This was inve...

Research paper thumbnail of Antioxidant Supplementation Restores Defective Leucine Stimulation of Protein Synthesis in Skeletal Muscle from Old Rats1,2

Aging is characterized by a progressive loss of muscle mass that could be partly explained by a d... more Aging is characterized by a progressive loss of muscle mass that could be partly explained by a defect in the anabolic effect of food intake. We previously reported that this defect resulted from a decrease in the protein synthesis response to leucine in muscles from old rats. Because aging is associated with changes in oxidative status, we hypothesized that reactive

Research paper thumbnail of Assessment of protein modifications in liver of rats under chronic treatment with paracetamol (acetaminophen) using two complementary mass spectrometry-based metabolomic approaches

Journal of proteomics, Jan 24, 2015

Liver protein can be altered under paracetamol (APAP) treatment. APAP-protein adducts and other p... more Liver protein can be altered under paracetamol (APAP) treatment. APAP-protein adducts and other protein modifications (oxidation/nitration, expression) play a role in hepatotoxicity induced by acute overdoses, but it is unknown whether liver protein modifications occur during long-term treatment with non-toxic doses of APAP. We quantified APAP-protein adducts and assessed other protein modifications in the liver from rats under chronic (17 days) treatment with two APAP doses (0.5% or 1% of APAP in the diet w/w). A targeted metabolomic method was validated and used to quantify APAP-protein adducts as APAP-cysteine adducts following proteolytic hydrolysis. The limit of detection was found to be 7ng APAP-cysteine/mL hydrolysate i.e. an APAP-Cys to tyrosine ratio of 0.016‰. Other protein modifications were assessed on the same protein hydrolysate by untargeted metabolomics including a new strategy to process the data and identify discriminant molecules. These two complementary mass spec...

Research paper thumbnail of Chronic Intake of Sucrose Accelerates Sarcopenia in Older Male Rats through Alterations in Insulin Sensitivity and Muscle Protein Synthesis

The Journal of nutrition, Jan 25, 2015

Today, high chronic intake of added sugars is frequent, which leads to inflammation, oxidative st... more Today, high chronic intake of added sugars is frequent, which leads to inflammation, oxidative stress, and insulin resistance. These 3 factors could reduce meal-induced stimulation of muscle protein synthesis and thus aggravate the age-related loss of muscle mass (sarcopenia). Our aim was to determine if added sugars could accelerate sarcopenia and assess the capacity of antioxidants and anti-inflammatory agents to prevent this. For 5 mo, 16-mo-old male rats were starch fed (13% sucrose and 49% wheat starch diet) or sucrose fed (62% sucrose and 0% wheat starch diet) with or without rutin (5-g/kg diet), vitamin E (4 times), vitamin A (2 times), vitamin D (5 times), selenium (10 times), and zinc (+44%) (R) supplementation. We measured the evolution of body composition and inflammation, plasma insulin-like growth factor 1 (IGF-I) concentration and total antioxidant status, insulin sensitivity (oral-glucose-tolerance test), muscle weight, superoxide dismutase activity, glutathione conce...

Research paper thumbnail of Contrarily to whey and high protein diets, dietary free leucine supplementation cannot reverse the lack of recovery of muscle mass after prolonged immobilization during ageing

The Journal of physiology, Jan 15, 2012

During ageing, immobilization periods increase and are partially responsible of sarcopaenia by in... more During ageing, immobilization periods increase and are partially responsible of sarcopaenia by inducing a muscle atrophy which is hardly recovered from. Immobilization-induced atrophy is due to an increase of muscle apoptotic and proteolytic processes and decreased protein synthesis. Moreover, previous data suggested that the lack of muscle mass recovery might be due to a defect in protein synthesis response during rehabilitation. This study was conducted to explore protein synthesis during reloading and leucine supplementation effect as a nutritional strategy for muscle recovery. Old rats (22–24 months old) were subjected to unilateral hindlimb casting for 8 days (I8) and allowed to recover for 10–40 days (R10–R40). They were fed a casein (±leucine) diet during the recovery. Immobilized gastrocnemius muscles atrophied by 20%, and did not recover even at R40. Amount of polyubiquitinated conjugates and chymotrypsin- and trypsin-like activities of the 26S proteasome increased. These c...

Research paper thumbnail of Myostatin Gene Inactivation Prevents Skeletal Muscle Wasting in Cancer

Cancer Research, 2014

Cachexia is a muscle-wasting syndrome that contributes significantly to morbidity and mortality o... more Cachexia is a muscle-wasting syndrome that contributes significantly to morbidity and mortality of many patients with advanced cancers. However, little is understood about how the severe loss of skeletal muscle characterizing this condition occurs. In the current study, we tested the hypothesis that the muscle protein myostatin is involved in mediating the pathogenesis of cachexia-induced muscle wasting in tumor-bearing mice. Myostatin gene inactivation prevented the severe loss of skeletal muscle mass induced in mice engrafted with Lewis lung carcinoma (LLC) cells or in Apc Min/þ mice, an established model of colorectal cancer and cachexia. Mechanistically, myostatin loss attenuated the activation of muscle fiber proteolytic pathways by inhibiting the expression of atrophy-related genes, MuRF1 and MAFbx/Atrogin-1, along with autophagyrelated genes. Notably, myostatin loss also impeded the growth of LLC tumors, the number and the size of intestinal polyps in Apc Min/þ mice, thus strongly increasing survival in both models. Gene expression analysis in the LLC model showed this phenotype to be associated with reduced expression of genes involved in tumor metabolism, activin signaling, and apoptosis. Taken together, our results reveal an essential role for myostatin in the pathogenesis of cancer cachexia and link this condition to tumor growth, with implications for furthering understanding of cancer as a systemic disease. Cancer Res; 74(24); 7344-56. Ó2014 AACR.

Research paper thumbnail of Postprandial leucine deficiency failed to alter muscle protein synthesis in growing and adult rats

This study examined the effect of a specific acute postprandial leucine deficiency on skeletal mu... more This study examined the effect of a specific acute postprandial leucine deficiency on skeletal muscle protein synthesis in growing and adult rats. Because the anabolic action of dietary leucine supplementation is controversial, except during aging, we hypothesized that the maximum leucine effect might be already achieved for a normal postprandial rise of leucine. Preventing this rise during the 1- to 3-h period after feeding may reveal the leucine regulation. On the day of the experiment, rats were fasted (postabsorptive, PA group) or fed for 1 h a control meal (postprandial, control, PP group) or a leucine-poor meal (postprandial, PP-Leu group). Muscle protein synthesis was assessed in vivo, over the 1- to 3-h period after meal distribution, using the flooding dose method (L-1-(13)C phenylalanine). As expected, the postprandial increase in plasma free leucine was specifically abolished after feeding the leucine-poor meal, whereas all the other plasma free amino acids were roughly at normal postprandial levels. Plasma insulin increased after feeding in young rats but was constant in adult rats. Plasma insulin was similar whatever dietary leucine levels. Rates of muscle protein synthesis were stimulated by feeding in gastrocnemius and soleus muscles from young rats but only in gastrocnemius muscles from adult rats. The PP-Leu group did not differ from the control PP group regarding muscle protein synthesis. The rise in plasma free leucine is not required for the stimulation of muscle protein synthesis during the 1- to 3-h period after feeding young and adult rats, as previously observed in old rats.

Research paper thumbnail of A leucine-supplemented diet restores the defective postprandial inhibition of proteasome-dependent proteolysis in aged rat skeletal muscle

We tested the hypothesis that skeletal muscle ubiquitin-proteasome-dependent proteolysis is dysre... more We tested the hypothesis that skeletal muscle ubiquitin-proteasome-dependent proteolysis is dysregulated in ageing in response to feeding. In Experiment 1 we measured rates of proteasome-dependent proteolysis in incubated muscles from 8-and 22-month-old rats, proteasome activities, and rates of ubiquitination, in the postprandial and postabsorptive states. Peptidase activities of the proteasome decreased in the postabsorptive state in 22-month-old rats compared with 8-month-old animals, while the rate of ubiquitination was not altered. Furthermore, the down-regulation of in vitro proteasome-dependent proteolysis that prevailed in the postprandial state in 8-month-old rats was defective in 22-month-old rats. Next, we tested the hypothesis that the ingestion of a 5% leucine-supplemented diet may correct this defect. Leucine supplementation restored the postprandial inhibition of in vitro proteasome-dependent proteolysis in 22-month-old animals, by down-regulating both rates of ubiquitination and proteasome activities. In Experiment 2, we verified that dietary leucine supplementation had long-lasting effects by comparing 8-and 22-month-old rats that were fed either a leucine-supplemented diet or an alanine-supplemented diet for 10 days. The inhibited in vitro proteolysis was maintained in the postprandial state in the 22-month-old rats fed the leucine-supplemented diet. Moreover, elevated mRNA levels for ubiquitin, 14-kDa ubiquitin-conjugating enzyme E2, and C2 and X subunits of the 20S proteasome that were characteristic of aged muscle were totally suppressed in 22-month-old animals chronically fed the leucine-supplemented diet, demonstrating an in vivo effect. Thus the defective postprandial down-regulation of in vitro proteasome-dependent proteolysis in 22-month-old rats was restored in animals chronically fed a leucine-supplemented diet.

Research paper thumbnail of High Whey Protein Intake Delayed the Loss of Lean Body Mass in Healthy Old Rats, whereas Protein Type and Polyphenol/Antioxidant Supplementation Had No Effects

PLoS ONE, 2014

Our aim was to compare and combine 3 nutritional strategies to slow down the age-related loss of ... more Our aim was to compare and combine 3 nutritional strategies to slow down the age-related loss of muscle mass in healthy old rats: 1) increase protein intake, which is likely to stimulate muscle protein anabolism; 2) use leucine rich, rapidly digested whey proteins as protein source (whey proteins are recognized as the most effective proteins to stimulate muscle protein anabolism). 3) Supplement animals with a mixture of chamomile extract, vitamin E, vitamin D (reducing inflammation and oxidative stress is also effective to improve muscle anabolism). Such comparisons and combinations were never tested before. Nutritional groups were: casein 12% protein, whey 12% protein, whey 18% protein and each of these groups were supplemented or not with polyphenols/antioxidants. During 6 months, we followed changes of weight, food intake, inflammation (plasma fibrinogen and alpha-2-macroglobulin) and body composition (DXA). After 6 months, we measured muscle mass, in vivo and ex-vivo fed and post-absorptive muscle protein synthesis, ex-vivo muscle proteolysis, and oxidative stress parameters (liver and muscle glutathione, SOD and total antioxidant activities, muscle carbonyls and TBARS). We showed that although micronutrient supplementation reduced inflammation and oxidative stress, the only factor that significantly reduced the loss of lean body mass was the increase in whey protein intake, with no detectable effect on muscle protein synthesis, and a tendency to reduce muscle proteolysis. We conclude that in healthy rats, increasing protein intake is an effective way to delay sarcopenia.

Research paper thumbnail of Lack of muscle recovery after immobilization in old rats does not result from a defect in normalization of the ubiquitin-proteasome and the caspase-dependent apoptotic pathways

The Journal of Physiology, 2011

Non-technical summary Immobilization periods increase with age because of decreased mobility and/... more Non-technical summary Immobilization periods increase with age because of decreased mobility and/or because of increased pathological episodes that require bed-rest. Then, sarcopaenia might be partially explained by an impaired recovery of skeletal muscle mass after a catabolic state due to an imbalance of muscle protein metabolism, apoptosis and cellular regeneration. Mechanisms involved during muscle recovery have been little studied and in elderly they remain almost unknown. We show, in rats, that a short immobilization period during ageing initiated muscle atrophy that was indeed not recovered after 40 days. Immobilization was associated with an activation of both the ubiquitin-proteasome and the mitochondria-associated apoptotic pathways and the inflammatory and redox processes, and a decrease of cellular regeneration. We show that the lack of muscle recovery during ageing is not due to a defect in proteolysis or apoptosis down-regulation. These observations lead us to hypothesize that muscle protein synthesis activation after immobilization was altered during ageing.

Research paper thumbnail of Leucine supplementation improves muscle protein synthesis in elderly men independently of hyperaminoacidaemia

The Journal of Physiology, 2006

The present study was designed to assess the effects of dietary leucine supplementation on muscle... more The present study was designed to assess the effects of dietary leucine supplementation on muscle protein synthesis and whole body protein kinetics in elderly individuals. Twenty healthy male subjects (70 ± 1 years) were studied before and after continuous ingestion of a complete balanced diet supplemented or not with leucine. A primed (3.6 μmol kg −1 ) constant infusion (0.06 μmol kg −1 min −1 ) of L-[1-13 C]phenylalanine was used to determine whole body phenylalanine kinetics as well as fractional synthesis rate (FSR) in the myofibrillar fraction of muscle proteins from vastus lateralis biopsies. Whole body protein kinetics were not affected by leucine supplementation. In contrast, muscle FSR, measured over the 5-h period of feeding, was significantly greater in the volunteers given the leucine-supplemented meals compared with the control group (0.083 ± 0.008 versus 0.053 ± 0.009% h −1 , respectively, P < 0.05). This effect was due only to increased leucine availability because only plasma free leucine concentration significantly differed between the control and leucine-supplemented groups. We conclude that leucine supplementation during feeding improves muscle protein synthesis in the elderly independently of an overall increase of other amino acids. Whether increasing leucine intake in old people may limit muscle protein loss during ageing remains to be determined.

Research paper thumbnail of The Nature of the Ingested Protein Has No Effect on Lean Body Mass During Energy Restriction in Overweight Rats

Research paper thumbnail of Excessive Energy Intake Does Not Modify Fed-state Tissue Protein Synthesis Rates in Adult Rats

Research paper thumbnail of Dietary n-3 polyUnsaturated fatty acids are capable to enhance protein anabolism response to insulin but not to leucine in old rats

Nutrition, Metabolism and Cardiovascular Diseases, 2013

Research paper thumbnail of Effects of leucine supplementation and resistance exercise on dexamethasone-induced muscle atrophy and insulin resistance in rats

Nutrition, 2012

Objective: We aimed to evaluate the effects of resistance exercise (RE) and leucine (LEU) supplem... more Objective: We aimed to evaluate the effects of resistance exercise (RE) and leucine (LEU) supplementation on dexamethasone (DEXA)-induced muscle atrophy and insulin resistance. Methods: Male Wistar rats were randomly divided into DEXA (DEX), DEXA þ RE (DEX-RE), DEXA þ LEU (DEX-LEU), and DEXA þ RE þ LEU (DEX-RE-LEU) groups. Each group received DEXA 5 mg $ kg À1 $ d À1 for 7 d from drinking water and were pair-fed to the DEX group; LEU-supplemented groups received 0.135 g $ kg À1 $ d À1 through gavage for 7 d; the RE protocol was based on three sessions of squat-type exercise composed by three sets of 10 repetitions at 70% of maximal voluntary strength capacity. Results: The plantaris mass was significantly greater in both trained groups compared with the non-trained groups. Muscle cross-sectional area and fiber areas did not differ between groups. Both trained groups displayed significant increases in the number of intermediated fibers (IIa/IIx), a decreased number of fast-twitch fibers (IIb), an increased ratio of the proteins phospho Ser2448 / total mammalian target of rapamycin and phospho Thr389 /total 70-kDa ribosomal protein S6 kinase, and a decreased ratio of phospho Ser253 /total Forkhead box protein-3a. Plasma glucose was significantly increased in the DEX-LEU group compared with the DEX group and RE significantly decreased hyperglycemia. The DEX-LEU group displayed decreased glucose transporter-4 translocation compared with the DEX group and RE restored this response. LEU supplementation worsened insulin sensitivity and did not attenuate muscle wasting in rats treated with DEXA. Conversely, RE modulated glucose homeostasis and fiber type transition in the plantaris muscle. Conclusion: Resistance exercise but not LEU supplementation promoted fiber type transition and improved glucose homeostasis in DEXA-treated rats.

Research paper thumbnail of Spreading intake of a leucine-rich fast protein in energy-restricted overweight rats does not improve protein mass

Nutrition, 2012

Objective: Energy restriction decreases fat mass and fat-free mass. Our aim was to prevent the la... more Objective: Energy restriction decreases fat mass and fat-free mass. Our aim was to prevent the latter using type and timing of protein nutrition as tools. Methods: Young male Wistar rats were given a high-energy diet for 5 wk and then energy restricted and fed a high-protein diet containing caseins, milk-soluble proteins (MSP), or a casein-MSP mixture (n ¼ 9 per group) as the only source of protein for 3 wk. Food intake was spread over 12 h, whereas in a previous experiment rats consumed their daily ration within 2 to 3 h. Weight and food intake were recorded. The body composition was measured by dual-energy x-ray absorptiometry before and after energy restriction. After 3 wk, the hind-limb muscles, the kidney, intestine, liver, and spleen weights, metabolic plasma parameters, and the liver and extensor digitorum longus muscle protein synthesis rates were measured in the postprandial state. Results: The food intake was similar in all groups. Energy restriction induced a significant decrease in body weight and fat mass (P < 0.001) and stopped the slow growth of lean body mass, with no differences between groups. Among all tissues, a significant effect was detected only for the intestine (P ¼ 0.0012), with a higher weight in the casein group. Postprandial liver and muscle protein synthesis rates were not different between groups. Conclusion: When using a high-protein diet spread over 12 h, the nature of the protein intake has no influence on the sparing of lean body mass during energy restriction in young overweight rats.

Research paper thumbnail of Antioxidant supplementation had positive effects in old rat muscle, but through better oxidative status in other organs

Nutrition, 2010

Objective: Aged muscle is characterized by a defect in the ability of leucine to stimulate protei... more Objective: Aged muscle is characterized by a defect in the ability of leucine to stimulate protein synthesis. We showed previously that antioxidant supplementation improved the anabolic response to leucine of old muscle and reduced inflammation. The aim of the present study was to determine if the positive effects observed in muscle could be related to an improvement of local muscle oxidative status. Methods: Two groups of 20-mo-old male Wistar rats were supplemented or not with rutin, vitamin E, vitamin A, zinc, and selenium during 7 wk. We measured body weight, food intake, oxidative status in muscle and other tissues, gastrocnemius muscle proteolytic activities, and liver glutathione metabolism. Results: Antioxidant supplementation had no effect on muscle antioxidant capacity, superoxide dismutase activities, and myofibrillar protein carbonyl content and induced an increase in muscle cathepsin activities. In other tissues, antioxidant supplementation increased liver glutathione (reduced plus oxidized glutathione) content, reduced oxidative damage in the liver and spleen (as measured by g-keto-aldehyde content), and reduced heart thiobarbituric acid-reactive substances.

Research paper thumbnail of Leucine supplementation in rats induced a delay in muscle IR/PI3K signaling pathway associated with overall impaired glucose tolerance☆

The Journal of Nutritional Biochemistry, 2011

Although activation of the mammalian target of rapamycin complex/p70 S6 kinase (S6K1) pathway by ... more Although activation of the mammalian target of rapamycin complex/p70 S6 kinase (S6K1) pathway by leucine is efficient to stimulate muscle protein synthesis, it can also exert inhibition on the early steps of insulin signaling leading to insulin resistance. We investigated the impact of 5-week leucine supplementation on insulin signaling and sensitivity in 4-month old rats fed a 15% protein diet supplemented (LEU) or not (C) with 4.5% leucine. An oral glucose tolerance test was performed in each rat at the end of the supplementation and glucose transport was measured in vitro using isolated epitrochlearis muscles incubated with 2-deoxy-d-[(3)H]-glucose under increasing insulin concentrations. Insulin signaling was assessed on gastrocnemius at the postabsorptive state or 30 and 60 min after gavage with a nutrient bolus. Tyrosine phosphorylation of IRβ, IRS1 and PI3 kinase activity were reduced in LEU group 30 min after feeding (-36%, -36% and -38% respectively, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.05) whereas S6K1, S6rp and 4EBP1 phosphorylations were similar. Overall glucose tolerance was reduced in leucine-supplemented rats and was associated with accumulation of perirenal adipose tissue (+27%, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.05). Conversely, in vitro insulin-response of muscle glucose transport tended to be improved in leucine-supplemented rats. In conclusion, dietary leucine supplementation in adult rats induced a delay in the postprandial stimulation in the early steps of muscle insulin signaling without muscle resistance on insulin-induced glucose uptake. However, it resulted in overall glucose intolerance linked to increased local adiposity. Further investigations are necessary to clearly define the beneficial and/or deleterious effects of chronic dietary leucine supplementation in healthy subjects.

Research paper thumbnail of Presence of low-grade inflammation impaired postprandial stimulation of muscle protein synthesis in old rats

The Journal of Nutritional Biochemistry, 2010

Aging is characterized by a decline in muscle mass that could be explained by a defect in the reg... more Aging is characterized by a decline in muscle mass that could be explained by a defect in the regulation of postprandial muscle protein metabolism. This study was undertaken to examine a possible link between the development of low-grade inflammation (LGI) in elderly and the resistance of muscle protein synthesis and degradation pathways to food intake. Fifty-five 20-month-old-rats were studied for 5 months; blood was withdrawn once a month to assess plasma fibrinogen and alpha2-macroglobulin. Animals were then separated into two groups at 25 months old according to their inflammation status: a control non-inflamed (NI, n=24) and a low-grade inflamed group (LGI, n=23). The day of the experiment, rats received no food or a meal. Muscle protein synthesis was assessed in vivo using the flooding dose method ([1-(13)C]phenylalanine) and muscle phosphorylation of protein S6 kinase, and protein S6 was measured in gastrocnemius muscle. Muscle proteolysis was assessed in vitro using the epitrochlearis muscle. Postabsorptive muscle protein synthesis and proteolysis were similar in NI and LGI. After food intake, muscle protein synthesis was significantly stimulated in NI but remained unresponsive in LGI. Muscle proteolysis was similar in both groups whatever the inflammation and/or the nutritional status. In conclusion, we showed that development of LGI during aging may be responsible, at least in part, for the defect in muscle protein synthesis stimulation induced by food intake in rats. Our results suggested that the control of LGI development in elderly improve meal effect on muscle protein synthesis and consequently slow down sarcopenia.

Research paper thumbnail of Cysteine fluxes across the portal-drained viscera of enterally fed minipigs: effect of an acute intestinal inflammation

Amino Acids, 2011

Cysteine is considered as a conditionally indispensable amino acid. Its dietary supply should thu... more Cysteine is considered as a conditionally indispensable amino acid. Its dietary supply should thus be increased when endogenous synthesis cannot meet metabolic need, such as during inflammatory diseases. However, studies in animal models suggest a high first-pass extraction of dietary cysteine by the intestine, limiting the interest for an oral supplementation. We investigated here unidirectional fluxes of cysteine across the portal-drained viscera (PDV) of multi-catheterized minipigs, using simultaneous intragastric L-[(15)N] cysteine and intravenous L-[3,3D2] cysteine continuous infusions. We showed that in minipigs fed with an elemental enteral solution, cysteine first-pass extraction by the intestine is about 60% of the dietary supply, and that the PDV does not capture arterial cysteine. Beside dietary cysteine, the PDV release non-dietary cysteine (20% of the total cysteine release), which originates either from tissue metabolism or from reabsorption of endogenous secretion, such as glutathione (GSH) biliary excretion. Experimental ileitis induced by local administration of trinitrobenzene sulfonic acid, increased liver and ileal GSH fractional synthesis rate during the acute phase of inflammation, and increased whole body flux of cysteine. However, cysteine uptake and release by the PDV were not affected by ileitis, suggesting an adaptation of the intestinal sulfur amino acid metabolism in order to cover the additional requirement of cysteine linked to the increased GSH synthesis. We conclude that the small intestine sequesters large amounts of dietary cysteine during absorption, limiting its release into the bloodstream, and that the other tissues of the PDV (colon, stomach, pancreas, spleen) preferentially use circulating methionine or cysteine-containing peptides to cover their cysteine requirement.