1
|
Jarzaguet M, Polakof S, David J, Migné C, Joubrel G, Efstathiou T, Rémond D, Mosoni L, Dardevet D. A meal with mixed soy/whey proteins is as efficient as a whey meal in counteracting the age-related muscle anabolic resistance only if the protein content and leucine levels are increased. Food Funct 2019; 9:6526-6534. [PMID: 30475369 DOI: 10.1039/c8fo01903g] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
With aging, skeletal muscle becomes resistant to the anabolic effect of dietary proteins and sarcopenia develops. Animal proteins, which are rich in leucine, are recommended for the elderly, but it is not known whether their replacement by plant proteins would maintain the health and physical independence of this population. Aged rats were fed with animal proteins (casein and whey proteins) with different leucine contents and compared to rats fed with diets in which whey was substituted with soy proteins and by increasing the total protein content or not. Our results clearly showed that the meal with mixed soy/whey proteins allowed the anabolic response of skeletal muscle during aging only if the protein content was increased by 25%. Indeed, if the protein content of the soy/whey diet was decreased to a similar protein content such as a whey diet, i.e. 13%, the anabolic effect decreased. The same observation was recorded if the whey proteins were totally substituted with soy proteins.
Collapse
Affiliation(s)
- Marianne Jarzaguet
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, PFEM, MetaboHUB-Clermont, CRNH Auvergne, F-63000 Clermont-Ferrand, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
2
|
David J, Dardevet D, Mosoni L, Savary-Auzeloux I, Polakof S. Impaired Skeletal Muscle Branched-Chain Amino Acids Catabolism Contributes to Their Increased Circulating Levels in a Non-Obese Insulin-Resistant Fructose-Fed Rat Model. Nutrients 2019; 11:E355. [PMID: 30744017 PMCID: PMC6412955 DOI: 10.3390/nu11020355] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 12/11/2022] Open
Abstract
Elevated plasma branched-chain amino acids (BCAA) levels are often observed in obese insulin-resistant (IR) subjects and laboratory animals. A reduced capacity of the adipose tissues (AT) to catabolize BCAA has been proposed as an explanation, but it seems restricted to obesity models of genetically modified or high fat⁻fed rodents. We aimed to determine if plasma BCAA levels were increased in a model of IR without obesity and to explore the underlying mechanisms. Rats were fed with a standard diet, containing either starch or fructose. BCAA levels, body weight and composition were recorded before and after 5, 12, 30, or 45 days of feeding. Elevated blood BCAA levels were observed in our IR model with unaltered body weight and composition. No changes were observed in the liver or the AT, but instead an impaired capacity of the skeletal muscle to catabolize BCAA was observed, including reduced capacity for transamination and oxidative deamination. Although the elevated blood BCAA levels in the fructose-fed rat seem to be a common feature of the IR phenotype observed in obese subjects and high fat⁻fed animals, the mechanisms involved in such a metabolic phenomenon are different, likely involving the skeletal muscle BCAA metabolism.
Collapse
Affiliation(s)
- Jérémie David
- Université Clermont Auvergne, INRA, Unité de Nutrition Humaine, UMR1019, F-63000 CLERMONT-FERRAND, France.
| | - Dominique Dardevet
- Université Clermont Auvergne, INRA, Unité de Nutrition Humaine, UMR1019, F-63000 CLERMONT-FERRAND, France.
| | - Laurent Mosoni
- Université Clermont Auvergne, INRA, Unité de Nutrition Humaine, UMR1019, F-63000 CLERMONT-FERRAND, France.
| | - Isabelle Savary-Auzeloux
- Université Clermont Auvergne, INRA, Unité de Nutrition Humaine, UMR1019, F-63000 CLERMONT-FERRAND, France.
| | - Sergio Polakof
- Université Clermont Auvergne, INRA, Unité de Nutrition Humaine, UMR1019, F-63000 CLERMONT-FERRAND, France.
| |
Collapse
|
3
|
Dardevet D, Mosoni L, David J, Polakof S. Fructose Feeding during the Postabsorptive State Alters Body Composition and Spares Nitrogen in Protein-Energy-Restricted Old Rats. J Nutr 2018; 148:40-48. [PMID: 29378055 DOI: 10.1093/jn/nxx028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/27/2017] [Indexed: 11/12/2022] Open
Abstract
Background Fructose feeding in the context of high energy intake is recognized as being responsible for metabolic dysregulation. However, its consumption in the postabsorptive state might contribute to reducing the use of amino acids (AAs) as energy substrates and thus spare nitrogen resources, which could be beneficial during catabolic states. Objective We hypothesized that fructose feeding during a catabolic situation corresponding to protein-energy restriction (PER) in older rats would reduce AA utilization for energy purposes, thus slowing down the loss of body weight (BW) and improving body composition. Methods For 45 d, 22-mo-old male Wistar rats (average weight: 716 g) were fed a control ration (13% protein) either at normal (20 g/d), restricted (PER: 10 g/d), or at PER levels supplemented with glucose (3 g/d) or fructose (3 g/d) and then studied in the postabsorptive state. We measured BW, body composition, and enzyme activities and metabolite concentrations related to glucose, fructose, and AA metabolism. Results Both glucose and fructose feeding reduced PER-induced loss of BW and lean mass (-27% compared with PER), but only fructose reduced the loss of fat mass (-28% compared with PER). Fructose feeding prevented the PER-induced loss of muscle and intestinal mass. Fructose feeding also reduced circulating branched-chain AA concentrations by 50% (compared with PER) and increased those of alanine (+65% compared with PER). A reduction in hepatic enzymes related to AA catabolism was also observed during fructose feeding (compared with PER), whereas glycogen concentrations were enhanced in both intestine (+300%) and muscle (+21%). Conclusions We showed that in PER older rats, fructose feeding improved body composition and the weight of several organs by reducing AA catabolism and utilization for energy production and liver autophagy potential. This could be advantageous in sparing body proteins, particularly during catabolic states, such as those related to malnutrition during aging.
Collapse
Affiliation(s)
- Dominique Dardevet
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Laurent Mosoni
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Jérémie David
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Sergio Polakof
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| |
Collapse
|
4
|
Polakof S, Rémond D, David J, Dardevet D, Savary-Auzeloux I. Time-course changes in circulating branched-chain amino acid levels and metabolism in obese Yucatan minipig. Nutrition 2017; 50:66-73. [PMID: 29547796 DOI: 10.1016/j.nut.2017.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/24/2017] [Accepted: 11/01/2017] [Indexed: 12/26/2022]
Abstract
OBJECTIVES High-fat high-sucrose diet (HFHS) overfeeding is one of the main factors responsible for the increased prevalence of metabolic disorders. Elevated levels of branched-chain amino acids (BCAAs) have been associated with metabolic dysfunctions, including insulin resistance (IR). The aim of this study was to elucidate whether elevated BCAA levels are the cause or the consequence of IR and to determine the mechanisms and tissues involved in such a phenotype. METHODS We performed a 2-mo follow-up on minipigs overfed an HFHS diet and focused on kinetics fasting and postprandial (PP) BCAA levels and BCAA catabolism in key tissues. RESULTS The study of the fasting BCAA elevation reveals that BCAA accumulation in the plasma compartment is well correlated with IR markers and body weight. Furthermore, the PP excursion of BCAA levels after the last HFHS meal was exacerbated when compared with that of the first meal, suggesting a reduced amino acid oxidation potential. Although only minor changes in BCAA metabolism were observed in liver, muscle, and the visceral adipose tissue, the oxidative deamination potential of the subcutaneous adipose tissue was blunted after 60 d of HFHS feeding. CONCLUSIONS To our knowledge, the present results demonstrated for the first time in a swine model of obesity and IR, the existence of a phenotype related to high-circulating BCAA levels and metabolic dysregulation. The oxidative BCAA capacity reduction specifically in the subcutaneous adipose tissue emerges, at least in the present swine model, as the more plausible metabolic explanation for the elevated blood BCAA phenotype.
Collapse
Affiliation(s)
- Sergio Polakof
- INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Université Clermont Auvergne, Clermont-Ferrand, France.
| | - Didier Rémond
- INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Jérémie David
- INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Dominique Dardevet
- INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Isabelle Savary-Auzeloux
- INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Université Clermont Auvergne, Clermont-Ferrand, France
| |
Collapse
|
5
|
Tessari P. Leucine Transamination Is Lower in Middle-Aged Compared with Younger Adults. J Nutr 2017; 147:2025-2030. [PMID: 28931590 DOI: 10.3945/jn.117.250852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 04/28/2017] [Accepted: 08/22/2017] [Indexed: 11/14/2022] Open
Abstract
Background: Insulin and age affect leucine (and protein) kinetics in vivo. However, to our knowledge, leucine transamination and the effects of insulin have not been studied in participants of different ages.Objective: The aims of the study were to measure whole-body leucine deamination to α-ketoisocaproate (KIC) and KIC reamination to leucine in middle-aged and younger healthy adults, both in the postabsorptive state and after hyperinsulinemia.Methods: Younger (mean ± SE age: 26 ± 2 y) and middle-aged (54 ± 3 y) healthy men and women were enrolled. Isotope dilution methods with 2 independent leucine and KIC tracers, a dual isotope model and the euglycemic, hyperinsulinemic clamp technique, were used.Results: Leucine deamination [expressed as μmol/(kg × min)] was consistently greater than KIC reamination. In middle-aged adults, postabsorptive leucine deamination (0.77 ± 0.05), reamination (0.49 ± 0.04), and net deamination (0.28 ± 0.04) were ∼30% lower than in the younger group (deamination: 1.12 ± 0.07; reamination: 0.70 ± 0.09; net deamination: 0.42 ± 0.04) (P < 0.002, P < 0.05, and P < 0.015, respectively). After the hyperinsulinemic clamp, plasma leucine and KIC concentrations were reduced by ∼50% in both groups. Deamination and reamination also were suppressed by ∼40-50% in both groups (P < 0.001); however, they remained lower [-35% (P = 0.02) and -25% (P = 0.036), respectively] in the middle-aged than in the younger participants. The leucine rate of appearance and its suppression by insulin were similar in the middle-aged and in the younger subjects. By using both the basal and the clamp data, deamination was directly correlated with the plasma leucine concentration (r = 0.61, P < 0.0025) and reamination to that of plasma KIC (r = 0.79, P < 0.00002). Expressing the data relative to lean body mass did not substantially alter the results.Conclusions: Leucine deamination and reamination are lower in middle-aged than in younger adults, both in the postabsorptive and in the insulin-stimulated state. In middle age, a decreased net leucine transamination may represent a mechanism to spare this essential amino acid.
Collapse
Affiliation(s)
- Paolo Tessari
- Department of Medicine, Division of Metabolic Diseases, University of Padova, Padova, Italy
| |
Collapse
|
6
|
Zimmermann M, Sauer U, Zamboni N. Quantification and mass isotopomer profiling of α-keto acids in central carbon metabolism. Anal Chem 2014; 86:3232-7. [PMID: 24533614 DOI: 10.1021/ac500472c] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mass spectrometry has been established as a powerful and versatile technique for studying cellular metabolism. Applications range from profiling of metabolites to accurate quantification and tracing of stable isotopes through the biochemical reaction network. Despite broad coverage of central carbon metabolism, most methods fail to provide accurate assessments of the α-keto acids oxaloacetic acid, pyruvate, and glyoxylate because these compounds are highly reactive and degraded during sample processing and mass spectrometric measurement. We present a derivatization procedure to chemically stabilize these compounds readily during quenching of cellular metabolism. Stable derivatives were analyzed by ultrahigh pressure liquid chromatography coupled tandem mass spectrometry to accurately quantify the abundance of α-keto acids in biological matrices. Eventually, we demonstrated that the developed protocol is suited to measure mass isotopomers of these α-keto acids in tracer studies with stable isotopes. In conclusion, the here described method fills one of the last technical gaps for metabolomics investigations of central carbon metabolism.
Collapse
Affiliation(s)
- Michael Zimmermann
- Institute of Molecular Systems Biology, ETH Zurich , Zurich 8093, Switzerland
| | | | | |
Collapse
|
7
|
Structure-based design and mechanisms of allosteric inhibitors for mitochondrial branched-chain α-ketoacid dehydrogenase kinase. Proc Natl Acad Sci U S A 2013; 110:9728-33. [PMID: 23716694 DOI: 10.1073/pnas.1303220110] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine are elevated in maple syrup urine disease, heart failure, obesity, and type 2 diabetes. BCAA homeostasis is controlled by the mitochondrial branched-chain α-ketoacid dehydrogenase complex (BCKDC), which is negatively regulated by the specific BCKD kinase (BDK). Here, we used structure-based design to develop a BDK inhibitor, (S)-α-chloro-phenylpropionic acid [(S)-CPP]. Crystal structures of the BDK-(S)-CPP complex show that (S)-CPP binds to a unique allosteric site in the N-terminal domain, triggering helix movements in BDK. These conformational changes are communicated to the lipoyl-binding pocket, which nullifies BDK activity by blocking its binding to the BCKDC core. Administration of (S)-CPP to mice leads to the full activation and dephosphorylation of BCKDC with significant reduction in plasma BCAA concentrations. The results buttress the concept of targeting mitochondrial BDK as a pharmacological approach to mitigate BCAA accumulation in metabolic diseases and heart failure.
Collapse
|
8
|
Elia M. The Inter-Organ Flux of Substrates in Fed and Fasted Man, as Indicated by Arterio-Venous Balance Studies. Nutr Res Rev 2007; 4:3-31. [DOI: 10.1079/nrr19910005] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
9
|
Fukuhara D, Kanai Y, Chairoungdua A, Babu E, Bessho F, Kawano T, Akimoto Y, Endou H, Yan K. Protein characterization of NA+-independent system L amino acid transporter 3 in mice: a potential role in supply of branched-chain amino acids under nutrient starvation. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:888-98. [PMID: 17322374 PMCID: PMC1864869 DOI: 10.2353/ajpath.2007.060428] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We recently cloned the human Na(+)-independent system L neutral amino acid transporter LAT3. The aim of the present study was to characterize the molecular nature of mouse LAT3 at the protein level. Isolated mouse LAT3 showed 83% identity to human LAT3. Xenopus oocytes injected with mouse LAT3 cRNA showed the same functional property as human LAT3. Reverse transcriptase-polymerase chain reaction revealed apparent transcripts of mouse LAT3 in the liver, skeletal muscle, and pancreas, an expression pattern identical to that found in humans. Antibody generated against mouse LAT3 detected both approximately 58-kd and 48-kd bands in the sample from liver and only a 48-kd band in skeletal muscle and pancreas. Immunohistochemical study showed its clear localization in the plasma membrane of liver and skeletal muscle, whereas it was only detectable in the endoplasmic reticulum and in crystalline inclusions in pancreatic acinar cells. Starvation induced up-regulation of mouse LAT3 protein and mRNA in both liver and skeletal muscle but not in pancreas. These results suggest that LAT3 may indeed function as an amino acid transporter, transporting branched-chain amino acids from liver and skeletal muscle to the bloodstream and thereby participating in the regulatory system of interorgan amino acid nutrition.
Collapse
MESH Headings
- Amino Acid Transport Systems, Basic/genetics
- Amino Acid Transport Systems, Basic/metabolism
- Amino Acids, Branched-Chain/metabolism
- Animals
- Base Sequence
- Blotting, Western
- Cells, Cultured
- Cloning, Molecular
- Fluorescent Antibody Technique
- Humans
- Immunohistochemistry
- Male
- Mice
- Mice, Inbred ICR
- Microscopy, Confocal
- Microscopy, Electron, Transmission
- Microscopy, Immunoelectron
- Molecular Sequence Data
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Nucleic Acid
- Starvation/metabolism
Collapse
Affiliation(s)
- Daisuke Fukuhara
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Bailey DM, Davies B, Castell LM, Collier DJ, Milledge JS, Hullin DA, Seddon PS, Young IS. Symptoms of infection and acute mountain sickness; associated metabolic sequelae and problems in differential diagnosis. High Alt Med Biol 2004; 4:319-31. [PMID: 14561237 DOI: 10.1089/152702903769192278] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Infections and acute mountain sickness (AMS) are common at high altitude, yet their precise etiologies remain elusive and the potential for differential diagnosis is considerable. The present study was therefore designed to compare clinical nonspecific symptoms associated with these pathologies and basic changes in free radical and amino-acid metabolism. Nineteen males were examined at rest and after maximal exercise at sea level before (SL(1)/SL(2)) and following a 20 +/- 5 day ascent to Kanchenjunga base camp located at 5100 m (HA). Four subjects with symptoms consistent with an ongoing respiratory and recent gastrointestinal infection were also diagnosed with clinical AMS on the evening of day 1 at HA. These and six other subjects recovering from symptoms consistent with a respiratory infection presented with a greater increase (HA minus SL(1)) in AMS scores and resting venous concentration of lipid hydroperoxides (LH) and in total creatine phosphokinase and ratio of free tryptophan/branched chain amino acids, and greater decrease in glutamine (Gln) compared to healthy controls (n = 9, p < 0.05). The decrease in Gln was consistently related to the altitude/exercise-induced increase in LH (r = -0.69/r = -0.45; p < 0.05) and altitude-induced increase in myoglobin (r = -0.73, p < 0.05). These findings highlight the potential for the misdiagnosis of altitude illness due to the similarity of nonspecific constitutional symptoms associated with infection and AMS. Both conditions were characterized by parallel changes in peripheral biomarkers related to free-radical, skeletal muscle damage and amino acid metabolism. While clearly not establishing cause and effect, free radical-mediated changes in peripheral amino acid metabolism known to influence immune and cerebral serotoninergic function may enhance susceptibility to and/or delay recovery from altitude illness.
Collapse
Affiliation(s)
- Damian M Bailey
- 1998 British Mt. Kanchenjunga Medical Expedition, c/o Health and Exercise Sciences Research Laboratory, School of Applied Sciences, University of Glamorgan, South Wales, UK CF37 1DL.
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Purification and characterization of leucine dehydrogenase from an alkaliphilic halophile, Natronobacterium magadii MS-3. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1381-1177(03)00085-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
12
|
Holecek M, Rysava R, Safranek R, Kadlcikova J, Sprongl L. Acute effects of decreased glutamine supply on protein and amino acid metabolism in hepatic tissue: a study using isolated perfused rat liver. Metabolism 2003; 52:1062-7. [PMID: 12898474 DOI: 10.1016/s0026-0495(03)00107-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Glutamine deficiency, a common finding in severe illness, has a negative influence on immune status, protein metabolism, and disease outcome. In several studies, a close relationship between glutamine, branched-chain amino acid (BCAA), and protein metabolism was demonstrated. The aim of the present study was to investigate the effect of glutamine deficiency on amino acid and protein metabolism in hepatic tissue using a model of isolated perfused rat liver (IPRL). Parameters of protein metabolism and amino acid metabolism were measured using both recirculation and single pass technique with L-[1-(14)C]leucine and [1-(14)C]ketoisocaproate (KIC) as a tracer. Glutamine concentration in perfusion solution was 0.5 mmol/L in control and 0 mmol/L in the glutamine-deficient group. The net release of glutamine (about 11 micromol/g/h) and higher net uptake of most of the amino acids was observed in the glutamine-deficient group. There was an insignificant effect of lack of glutamine on hepatic protein synthesis, proteolysis, and the release of urea. However, significantly lower release of proteins by the liver perfused with glutamine-deficient solution was observed. The lack of glutamine in perfusion solution caused a significant decrease in leucine oxidation (6.66 +/- 1.04 v 13.67 +/- 2.38, micromol/g dry liver/h, P <.05) and an increase in KIC oxidation (163.7 +/- 16.5 v 92.0 +/- 12.9 micromL/g dry liver/h, P <.05). We conclude that decreased delivery of glutamine to hepatic tissue activates glutamine synthesis, decreases resynthesis of essential BCAA from branched-chain keto acids (BCKA), increases catabolism of BCKA, and has an insignificant effect on protein turnover in hepatic tissue.
Collapse
Affiliation(s)
- Milan Holecek
- Department of Physiology, Charles Unviersity Prague, Medical Faculty, Hradec Kralove, Czech Republic
| | | | | | | | | |
Collapse
|
13
|
Holecek M, Safránek R, Rysavá R, Kadlcíková J, Sprongl L. Acute effects of acidosis on protein and amino acid metabolism in perfused rat liver. Int J Exp Pathol 2003; 84:185-90. [PMID: 14632632 PMCID: PMC2517556 DOI: 10.1046/j.1365-2613.2003.00352.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2003] [Accepted: 08/01/2003] [Indexed: 12/27/2022] Open
Abstract
Acidosis is frequently associated with protein wasting and derangements in amino acid metabolism. As its effect on protein metabolism is significantly modulated by other abnormal metabolic conditions caused by specific illnesses, it is difficult to separate out the effects on protein metabolism solely due to acidosis. The aim of the present study was to evaluate, using a model of isolated perfused rat liver, the direct response of hepatic tissue to acidosis. We have compared hepatic response to perfusion with a solution of pH 7.2 and 7.4 (controls). Parameters of protein and amino acid metabolism were measured using both recirculation and single-pass technique with 4,5-[3H]leucine, [1-14C]leucine and [1-14C]ketoisocaproate (ketoleucine) as tracers and on the basis of difference of amino acid levels in perfusion solution at the beginning and end of perfusion. In liver perfused with a solution of pH 7.2, we observed higher rates of proteolysis, protein synthesis, amino acid utilization and urea production. Furthermore, the liver perfused with a solution of pH 7.2 released a higher amount of proteins to perfusate than the liver perfused with a solution of pH 7.4. Enhanced decarboxylation of ketoisocaproate in liver perfused by a solution of a lower pH indicates increased catabolism of branched-chain amino acids (leucine, valine and isoleucine), decreased reamination of branched-chain keto acids to corresponding essential amino acids and increased ketogenesis from leucine.
Collapse
Affiliation(s)
- Milan Holecek
- Department of Physiology, Charles University Prague, Hradec Králové, Czech Republic.
| | | | | | | | | |
Collapse
|
14
|
McGuire J, Ross GL, Price H, Mortensen N, Evans J, Castell LM. Biochemical markers for post-operative fatigue after major surgery. Brain Res Bull 2003; 60:125-30. [PMID: 12725900 DOI: 10.1016/s0361-9230(03)00021-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To establish a link between tryptophan (a precursor for 5-hydroxytryptamine (5-HT) or serotonin, involved in sleep and fatigue) and post-operative fatigue after major surgery. BACKGROUND There is a link between tryptophan (the precursor for the neurotransmitter 5-hydroxytryptamine), and its competitive binding with non-esterified fatty acids (NEFA) to albumin in the blood. An increase in the plasma concentration of free tryptophan can lead to an increased rate of synthesis of 5-HT in the brain. Free tryptophan competes with the branched chain amino acids (BCAA) for the same port of entry across the blood-brain barrier. It is suggested that the plasma concentration of these amino acids could be a marker of post-operative fatigue. In a previous study undertaken in this laboratory on patients undergoing two different types of major surgery, similar post-operative increases were observed in the plasma concentration of free tryptophan and the plasma concentration ratio of free tryptophan to branched chain amino acids. However, the study was retrospective and no measure of fatigue had been made. METHODS In the present study, this deficiency has been addressed by administering a modified Profile of Mood States questionnaire to patients undergoing reconstructive or colorectal surgery. In addition, blood samples were measured for plasma free tryptophan, albumin, NEFA and branched chain amino acids before and on 2 days after surgery. RESULTS There was a significant correlation between fatigue scores and plasma free tryptophan (P<0.000), and the plasma concentration ratio of free tryptophan/BCAA (P<0.016) after surgery in all the patients studied (n=34). This correlation was more marked in the colorectal-surgery patients, in whom surgery was more severe. In the three categories of patients receiving elective reconstructive surgery (n=24), those having breast reductions (n=6) had a lower plasma concentration of NEFA and appeared to recover from fatigue more quickly than those with pre-tibial lacerations or malignant melanoma. CONCLUSIONS These data provide further evidence of a possible biochemical mechanism for central fatigue which involves a precursor of 5-HT. The provision of branched chain amino acids may help to combat the surge in free tryptophan that occurs during stress such as major surgery.
Collapse
Affiliation(s)
- James McGuire
- University Department of Biochemistry, Oxford OX1 3QU, UK
| | | | | | | | | | | |
Collapse
|
15
|
Abstract
The branched-chain amino acids (BCAAs; valine, isoleucine, and leucine) are the major nitrogen source for glutamine and alanine synthesis in muscle. Synthesis of glutamine, alanine, and BCAA use is activated in critical illnesses such as in sepsis, cancer, and trauma. The use of glutamine often exceeds its synthesis, resulting in the lack of glutamine in plasma and tissues. In critical illness, resynthesis of BCAA from branched-chain keto acids is activated, particularly in hepatic tissue. The BCAA released to circulation may be used for protein synthesis or synthesis of alanine and glutamine. Glutamine and/or alanine infusion has an inhibitory effect on the breakdown of body proteins and decreases BCAA catabolism in postabsorptive control, endotoxemic, and irradiated rats. Decreased protein breakdown also was observed when glutamine synthesis was activated by ammonia infusion. In conclusion some favorable effects of BCAA supply can be explained by its role in the synthesis of glutamine and some positive effects of glutamine exogenous supply can be explained by its effect on metabolism of BCAA.
Collapse
Affiliation(s)
- Milan Holecek
- Department of Physiology, Charles University School of Medicine, Hradec Králové, Czech Republic.
| |
Collapse
|
16
|
Affiliation(s)
- P R Beckett
- Baylor College of Medicine, Houston, Texas 77030, USA
| |
Collapse
|
17
|
Ono K, Hakozaki M, Suzuki T, Mori T, Hata H, Kochi H. cDNA cloning of the chicken branched-chain alpha-keto acid dehydrogenase complex. Chicken-specific residues of the acyltransferase affect the overall activity and the interaction with the dehydrogenase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:727-36. [PMID: 11168412 DOI: 10.1046/j.1432-1327.2001.01925.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Branched-chain alpha-keto acid dehydrogenase complex is a macromolecule comprising three catalytic components: a dehydrogenase (E1) with alpha(2)beta(2) structure, an acyltransferase (E2) and a dihydrolipoamide dehydrogenase (E3). In the mammalian complex, the E2 component with 24 identical subunits forms a structural core, to which multiple copies of E1 and E3 bind noncovalently. We isolated cDNA clones encoding E1 alpha, E1 beta and E2 subunits from a chicken-liver cDNA library and performed nucleotide sequencing. Amino-acid sequences deduced from the nucleotide sequences revealed that chicken E1 alpha and E1 beta chains had substantially homologous sequences with the corresponding mammalian polypeptides, except for the N-terminus. Chicken E2 conserved three functional domains, a lipoyl-bearing domain, an E1/E3 binding domain and an inner-core domain, but contrasted strongly with mammalian E2 in respect of containing 11 additional residues in two interdomain linkers: nine sequential residues in one linker and two residues in the other. Replacement of many residues was also observed in the chicken linkers. When E2 activity for catalyzing the overall reaction was measured by activity reconstitution in combination with E1 and E3, chicken E2 was markedly less effective than mammalian E2. The capability of chicken E2 for binding E1 was also reduced when determined by the binding assay using sucrose density gradient centrifugation. Chicken E1 was functionally as well as structurally indistinguishable from mammalian E1. Thus the reduced catalytic activity of chicken E2 must arise from its reduced E1-binding capacity, which results from the characteristic structure of interdomain linkers in chicken E2.
Collapse
Affiliation(s)
- K Ono
- Department of Biochemistry, Fukushima Medical University, Japan
| | | | | | | | | | | |
Collapse
|
18
|
Bailey DM, Davies B, Castell LM, Newsholme EA, Calam J. Physical exercise and normobaric hypoxia: independent modulators of peripheral cholecystokinin metabolism in man. J Appl Physiol (1985) 2001; 90:105-13. [PMID: 11133899 DOI: 10.1152/jappl.2001.90.1.105] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of the present investigation was to determine the independent effects of hypoxia and physical exercise on peripheral cholecystokinin (CCK) metabolism in humans. Thirty-two physically active men were randomly assigned in a double-blind manner to either a normoxic (N; n = 14) or hypoxic (H; n = 18) group. During the acute study, subjects in the H group only participated in two tests, separated by 48 h, which involved a cycling test to exhaustion in normobaric normoxia and normobaric hypoxia (inspired O(2) fraction = 0.21 and 0.16, respectively). In the intermittent study, N and H groups cycle-trained for 4 wk at the same relative exercise intensity in both normoxia and hypoxia. Acute normoxic exercise consistently raised plasma CCK during both studies by 290-723%, which correlated with increases in the plasma ratio of free tryptophan to branched chain amino acids (r = 0.58-0.71, P < 0.05). In contrast, acute hypoxic exercise decreased CCK by 7.0 +/- 5.5 pmol/l, which correlated with the decrease in arterial oxygen saturation (r = 0.56, P < 0.05). In the intermittent study, plasma CCK response at rest and after normoxic exercise was not altered after physical training, despite a slight decrease in adiposity. We conclude that peripheral CCK metabolism 1) is more sensitive to acute changes than chronic changes in energy expenditure and 2) is potentially associated with acute changes in tissue PO(2) and metabolic precursors of cerebral serotoninergic activity.
Collapse
Affiliation(s)
- D M Bailey
- Hypoxia Research Unit, Health and Exercise Sciences Research Laboratory, School of Applied Sciences, University of Glamorgan, South Wales, CF37 1DL, United Kingdom.
| | | | | | | | | |
Collapse
|
19
|
KIBA N, SHIMURA G, HAYASHI H, TACHIBANA M, TANI K, KOIZUMI H, HIBINO Y. Simultaneous Determination of L-Phenylalanine and Branched-chain L-Amino Acids in Plasma by Liquid Chromatographic System with a Coimmobilized Enzyme Reactor and Fluorescence Detection. ANAL SCI 2000. [DOI: 10.2116/analsci.16.981] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Nobutoshi KIBA
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University
| | - Goki SHIMURA
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University
| | - Hirofumi HAYASHI
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University
| | - Masaki TACHIBANA
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University
| | - Kazue TANI
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University
| | - Hitoshi KOIZUMI
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University
| | - Yasuo HIBINO
- Institute of Technological Research, Tokyo Branch, Central Glass Co. Ltd
| |
Collapse
|
20
|
Yamamoto T, Castell LM, Botella J, Powell H, Hall GM, Young A, Newsholme EA. Changes in the albumin binding of tryptophan during postoperative recovery: a possible link with central fatigue? Brain Res Bull 1997; 43:43-6. [PMID: 9205793 DOI: 10.1016/s0361-9230(96)00344-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Tryptophan is the precursor of the neurotransmitter 5-hydroxytryptamine (5-HT), known to be involved in sleep and fatigue. In the blood, tryptophan binds to albumin, and that which does not, free tryptophan, competes with branched chain amino acids (BCAA) for entry into the brain. The plasma concentrations of albumin, free tryptophan, total tryptophan, and BCAA were measured before and after major surgery in nine elderly and nine coronary artery bypass graft (CABG) patients. In both the elderly and the CABG patients plasma free tryptophan concentrations were increased after surgery, compared with baseline levels; the plasma free tryptophan/BCAA concentration ratio was also increased significantly after surgery. Plasma albumin concentrations were decreased significantly after surgery in both the elderly and the CABG patients. Plasma BCAA concentrations were not affected by surgery in either group. The effect of exercising to exhaustion on 5-HT and tryptophan were investigated in Nagase analbuminemic rats (NAR). The intrasynaptosomal concentration of tryptophan, 5-hydroxy-tryptophan, and 5-HT was increased by fatigue after exercise. In addition, running time to exhaustion was shortened in NAR. These data suggest that free tryptophan uptake and 5-HT synthesis were enhanced in the nerve terminal. A decrease in plasma albumin may account for the increase in plasma-free tryptophan levels. An increase in plasma free tryptophan, resulting in an enhanced plasma concentration ratio of free tryptophan/BCAA, may lead to a higher 5-HT concentration in some parts of the brain and, consequently, to central fatigue. It is suggested that provision of BCAA as a dietary supplement may counteract the increase in plasma free tryptophan and thus improve the status of some patients after major surgery.
Collapse
Affiliation(s)
- T Yamamoto
- University Department of Biochemistry, Oxford, UK
| | | | | | | | | | | | | |
Collapse
|
21
|
|
22
|
Cowen PJ, Clifford EM, Walsh AE, Williams C, Fairburn CG. Moderate dieting causes 5-HT2C receptor supersensitivity. Psychol Med 1996; 26:1155-1159. [PMID: 8931161 DOI: 10.1017/s003329170003587x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Dieting is a widespread behaviour in developed countries, which in predisposed individuals can lead to the development of clinical eating disorders such as bulimia nervosa and anorexia nervosa. We studied the effect of moderate dieting in healthy women on the prolactin response to the serotonin (5-HT) receptor agonist, m-chlorophenylpiperazine (mCPP), a measure of the sensitivity of post-synaptic 5-HT2C receptors. Dieting significantly increased the prolactin response to mCPP and lowered plasma concentrations of the 5-HT precursor, tryptophan. We propose that dieting in women is associated with the development of functional supersensitivity of 5-HT2C receptors, probably in response to lowered levels of brain 5-HT. Alterations in brain 5-HT neurotransmission could play a part in dieting-induced dysregulation of eating and the development of clinical eating disorders in predisposed individuals.
Collapse
Affiliation(s)
- P J Cowen
- University Department of Psychiatry, Littlemore Hospital, Oxford
| | | | | | | | | |
Collapse
|
23
|
Kiba N, Oyama Y, Kato A, Furusawa M. Postcolumn co-immobilized leucine dehydrogenase-NADH oxidase reactor for the determination of branched-chain amino acids by high-performance liquid chromatography with chemiluminescence detection. J Chromatogr A 1996; 724:355-7. [PMID: 8819797 DOI: 10.1016/0021-9673(95)01041-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A liquid chromatographic system with a co-immobilized leucine dehydrogenase-NADH oxidase reactor is described for the determination of branched-chain amino acids such as I-leucine, I-isoleucine and I-valine. The enzymes were simultaneously immobilized on tresylate-containing poly(vinyl alcohol) beads. The separation was achieved by means of an ODS column with elution with phosphate buffer (pH 7.5). The hydrogen peroxide produced was detected chemiluminometrically via a luminol-hexacyanoferrate(III) reaction. The system gave a linear response from 0.3 to 300 mu M for each amino acid and the detection limit was 0.1 mu M.
Collapse
Affiliation(s)
- N Kiba
- Department of Applied Chemistry and Biotechnology, Yamanashi University, Kofu, Japan
| | | | | | | |
Collapse
|
24
|
Williamson DJ, McTavish SF, Park SB, Cowen PJ. Effect of valine on 5-HT-mediated prolactin release in healthy volunteers, and on mood in remitted depressed patients. Br J Psychiatry 1995; 167:238-42. [PMID: 7582676 DOI: 10.1192/bjp.167.2.238] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Animal experimental studies suggest that the amino acid valine may decrease brain serotonin (5-HT) function by inhibiting the transport of the 5-HT precursor, L-tryptophan, across the blood barrier. The aim of the present study was to assess whether valine could decrease brain 5-HT function in healthy subjects and provoke symptomatic relapse in recently remitted depressed patients taking antidepressant drug treatment. METHOD We studied the effect of valine (30 g) on the prolactin (PRL) response to the 5-HT releasing agent, D-fenfluramine, in healthy male subjects and on the mood of 12 remitted depressed patients taking either selective serotonin re-uptake inhibitors (n = 10) or lithium and amitriptyline (n = 2). RESULTS Valine significantly lowered the PRL response to D-fenfluramine in healthy subjects. In the remitted depressives, valine caused a mild but detectable lowering of mood on a number of measures but only one patient experienced a significant relapse in mood. CONCLUSIONS Valine administration may decrease brain 5-HT neurotransmission in humans. This effect could explain the mild increase in depressive symptoms in patients taking 5-HT-potentiating drugs.
Collapse
Affiliation(s)
- D J Williamson
- Psychopharmacology Research Unit, Littlemore Hospital, Oxford
| | | | | | | |
Collapse
|
25
|
Determination of branched-chain L-amino acids by flow-injection analysis with co-immobilized leucine dehydrogenase/NADH oxidase and chemiluminescence detection. Anal Chim Acta 1995. [DOI: 10.1016/0003-2670(95)00146-q] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
26
|
Schlenzig JS, Poggi-Travert F, Laurent J, Rabier D, Jan D, Wendel U, Sewell AC, Revillon Y, Kamoun P, Saudubray JM. Liver transplantation in two cases of propionic acidaemia. J Inherit Metab Dis 1995; 18:448-61. [PMID: 7494403 DOI: 10.1007/bf00710056] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Orthotopic liver transplantation (OLT) was performed in two patients with propionic acidaemia, a 7-year-old boy and a 9-year-old girl, diagnosed with a severe neonatal form with high risk of metabolic decompensation. In both cases the metabolic liver functions recovered within the 12 postoperative hours; no clinical symptoms of propionic acid toxicity, metabolic acidosis, severe hyperammonaemia, hyperglycinaemia or haematological abnormalities were observed. In both cases insulin-dependent diabetes mellitus occurred early after OLT (persisting in the boy's case). Severe post-transplantation complications were observed (acute rejection and CMV infection in both patients) which did not trigger metabolic decompensation. The boy developed chronic rejection and vanishing bile duct syndrome due to incomplete hepatic arterial thrombosis. He required permanent in-patient care with chronic hyperammonaemia and neurological sequelae involving the basal ganglia and died 15 months after OLT. The girl left hospital after 2 months and is presently leading a normal life with almost no dietary protein restriction (40 g protein per day). Urinary urea excretion and daily protein intake increased after liver transplantation. Propionyl- and tiglylglycine disappeared immediately after OLT. Urinary methylcitrate and 3-hydroxypropionate remained at concentrations corresponding to those before OLT. However, the total of all characteristic metabolites of organic acid analysis was reduced to 50-60% of the values before OLT in both patients. Propionylcarnitine was still detected at significant concentrations. Plasma odd-chain fatty acid concentrations decreased continuously after OLT only in the girl's case. Tissue of both transplanted livers showed increased odd-chain fatty acid concentrations 9 and 15 months after OLT, respectively, in both patients. We consider that at present OLT should only be performed in severe forms of propionic acidaemia.
Collapse
Affiliation(s)
- J S Schlenzig
- Department of Pediatrics, Hôpital Necker Enfants Malades, Paris, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Franklin M, Cowen PJ, Craven RD. The effects of a low tryptophan diet on brain 5 -HT metabolism and 5-HT-mediated neuroendocrine responses in the male rat. J Psychopharmacol 1995; 9:336-41. [PMID: 22298399 DOI: 10.1177/026988119500900408] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The study was undertaken to assess the effects of periods of dietary tryptophan (TRP) depletion on (i) plasma total and free TRP together with brain TRP, 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5- HIAA) and (ii) the prolactin (PRL) responses to the 5-HT releasing agent, D-fenfluramine (FEN), and the 5-HT agonist, m-chlorophenylpiperazine (mCPP). The TRP-deficient diet caused significant reductions in plasma total and free TRP for a short-lived period; however, it caused longer lasting and significant reductions in brain TRP, 5-HT and 5-HIAA content. Following periods of dietary TRP depletion, plasma PRL responses to FEN were significantly reduced for 14 days but had normalised by day 21. In contrast, the PRL responses to mCPP were significantly enhanced after 6 and 21 days, the response at 14 days being similar to control. The result suggests that periods of dietary invoked TRP depletion cause a deficiency of brain TRP content which subsequently leads to a fall in brain 5-HT. This is associated with a reduced PRL response to FEN and an enhanced PRL response to mCPP, the latter possibly resulting from functional up-regulation of post-synaptic 5-HT receptors.
Collapse
Affiliation(s)
- M Franklin
- University of Oxford, Psychopharmacology Research Unit, Department of Psychiatry, Littlemore Hospital, Oxford OX4 4XN
| | | | | |
Collapse
|
28
|
Powell H, Castell LM, Parry-Billings M, Desborough JP, Hall GM, Newsholme EA. Growth hormone suppression and glutamine flux associated with cardiac surgery. CLINICAL PHYSIOLOGY (OXFORD, ENGLAND) 1994; 14:569-80. [PMID: 7820981 DOI: 10.1111/j.1475-097x.1994.tb00415.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Pharmacological doses of growth hormone (GH) in humans and rats increase plasma and muscle glutamine values. As major surgery results in a physiological rise in serum GH concentration, we investigated whether this physiological increase in GH altered glutamine metabolism. Eighteen patients undergoing coronary artery bypass graft (CABG) surgery were randomly assigned to receive somatostatin, 100 micrograms subcutaneously at induction of anaesthesia and 8 hourly for 48 h, or placebo. Somatostatin effectively blocked the physiological surge of GH following injury but did not affect plasma or muscle glutamine concentrations, which fell significantly in both groups. Plasma glutamine decreased by 31% (P < 0.01) and 28% (P < 0.01) in the control and somatostatin groups respectively. Muscle glutamine was reduced 45% (P < 0.001) in the control group and 50% (P < 0.001) in the somatostatin group. There was no difference in muscle or circulating glutamate, alanine or branched chain amino acid concentrations or in metabolite values between the somatostatin-treated patients and the control group. There was no relationship between the GH response to surgery and glutamine metabolism following major surgery.
Collapse
Affiliation(s)
- H Powell
- Department of Anaesthetics, Royal Postgraduate Medical School Hammersmith Hospital, London, UK
| | | | | | | | | | | |
Collapse
|
29
|
López Hellin J, Schwartz S, Garlick PJ, Rosell M, Arbós MA, Andreu AL, García E. Ketoisocaproate contamination errors in protein synthesis determinations using L[1-14C]leucine. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 1993; 27:57-63. [PMID: 8409211 DOI: 10.1016/0165-022x(93)90068-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Protein synthesis rate determinations in vivo using L-[1-14C]-leucine may be underestimated because of contamination by radioactive ketoisocaproate (KIC) resulting from leucine metabolism. The aim of this work was to set up a reliable method to determine the KIC/leucine radioactivity ratio in protein-free homogenates, and to apply it to study the extent of the protein synthesis ratio error due to KIC contamination. Cation-exchange chromatography using Dowex AG 50W-X8 resin was used to separate KIC from leucine, eluting KIC with water and leucine with 4 M ammonia. The errors found in the protein synthesis ratio were 6.20% in liver and 2.34% in jejunum.
Collapse
Affiliation(s)
- J López Hellin
- Unitat de Recerques Metabòliques S. Grisolía, Hospital Vall d'Hebron, Barcelona, Spain
| | | | | | | | | | | | | |
Collapse
|
30
|
Rérat A, Simoes-Nuñes C, Mendy F, Vaissade P, Vaugelade P. Splanchnic fluxes of amino acids after duodenal infusion of carbohydrate solutions containing free amino acids or oligopeptides in the non-anaesthetized pig. Br J Nutr 1992; 68:111-38. [PMID: 1390598 DOI: 10.1079/bjn19920071] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Seven non-anaesthetized pigs (mean body-weight 64.6 kg) were used to study the intestinal absorption and hepatic metabolism of glucose and amino acids (AA) using carbohydrate solutions (maltose dextrin; 440 g/2 I), containing 110 g of either an enzymic milk-protein hydrolysate (PEP) with a large percentage of small peptides (about 50% with less than five AA residues) and very few free AA (8%) or a mixture of free AA (AAL) with an identical pattern, infused intraduodenally. Each pig was previously fitted under anaesthesia with electromagnetic flow probes around the portal vein and the hepatic artery, and with permanent catheters in the portal vein, carotid artery, one hepatic vein and the duodenum. Each solution was infused for 1 h after a fasting period (18 h) and each pig received both solutions at 8 d intervals. The observation period lasted 8 h. For most AA (his, lys, phe, thr, arg, tyr, pro) the absorption rate after infusion of PEP was significantly higher than after that of AAL during the 1st hour, but the differences quickly disappeared. After 8 h, the only differences concerned his and tyr (PEP > AAL) and met, glu and asp (AAL > PEP). There was a large uptake of blood AA by gut-wall cells, higher after AAL infusion than after PEP infusion, particularly for branched-chain AA (BCAA). The absorption of ammonia-nitrogen after both infusions was equivalent to two-thirds of urea-N passing from blood to intestinal tissues and lumen. Glucose absorbed within 8 h represented only 76% (PEP) or 69% (AAL) of the infused amounts. The cumulative hepatic total AA (TAA) uptake increased from 13 to 27% of the infused amounts between the 1st and the 8th hour after PEP infusion, and from 8 to 31% after AAL infusion. Most essential AA were largely taken up by the liver, with the exception of met (PEP) and thr and of BCAA, which were poorly retained for both solutions; there was a high uptake of ala and gly, and a release of asp, glu, and gln. Urea-N released by the liver within 8 h was equivalent to 23-25% absorbed amino-N and to around 1.5 times ammonia-N taken up by the liver within 8 h. Glucose was highly taken up by the liver during the first hours then released, the total uptake within 8 h representing about half the absorbed amount.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- A Rérat
- Département de Nutrition, Alimentation et Sécurité Alimentaire, CRJ-INRA, Jouy-en-Josas, France
| | | | | | | | | |
Collapse
|
31
|
Wendel U, Even G, Langenbeck U, Schadewaldt P, Hummel W. Determination of (S)- and (R)-2-oxo-3-methylvaleric acid in plasma of patients with maple syrup urine disease. Clin Chim Acta 1992; 208:85-91. [PMID: 1638756 DOI: 10.1016/0009-8981(92)90024-k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
An enzymatic method for the separate measurement of both chiral 2-oxo-3-methylvaleric acid (OMV) compounds, (S)- and (R)-OMV, by NADH-dependent enantioselective amination using leucine dehydrogenase in the presence of a NADH regenerating system is described. This method allows the quantitative determination of all branched-chain 2-oxo acids, simultaneously. In plasma samples from classical maple syrup urine disease patients under therapy the average (R)-OMV/(S)-OMV ratio was 0.35 and great differences in the transamination equilibria of the diastereomeric branched-chain amino acids L-isoleucine and L-alloisoleucine were demonstrated.
Collapse
Affiliation(s)
- U Wendel
- Kinderklinik, Heinrich-Heine-Universität, Düsseldorf, FRG
| | | | | | | | | |
Collapse
|
32
|
Physiological glucocorticoid levels regulate glutamine and insulin-mediated glucose metabolism in skeletal muscle of the rat. Studies with RU 486 (mifepristone). Biochem J 1991; 274 ( Pt 1):187-92. [PMID: 2001231 PMCID: PMC1149937 DOI: 10.1042/bj2740187] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This study examined the effects of antagonism of the peak level of glucocorticoids in vivo, which occurs as rats enter the feeding/activity (dark) period on glucose and glutamine metabolism in incubated isolated rat soleus muscle preparations. Thus the rats were treated with the potent glucocorticoid antagonist RU 486 2 h before and 1 and 2 h into the dark period. Both the content of glutamine in skeletal muscle in vivo and plasma glucose and glutamine concentrations were elevated midway through the dark period, compared with the beginning of the period. RU 486 prevented the increases in plasma glucose and glutamine and caused a significant decrease in both the rate of release of glutamine in soleus muscle in vitro and the content of glutamine in gastrocnemius muscle. The sensitivity of soleus muscle to insulin in vitro is markedly decreased when isolated midway through the dark period (i.e. at 03:00 h) [Leighton, Kowalchuk, Challiss & Newsholme (1988) Am. J. Physiol. 255, E41-E45]. We now show that the concentrations of insulin required to stimulate lactate formation and glycogen synthesis half-maximally were 95 and 250 muunits/ml respectively, and treatment of rats with RU 486 decreased these values to 55 and 90 muunits of insulin/ml respectively. Thus antagonism of the action of the normal circadian rise in the level of glucocorticoids in rats reverses insulin insensitivity in soleus muscles in vitro.
Collapse
|
33
|
Parry-Billings M, Leighton B, Dimitriadis GD, Curi R, Bond J, Bevan S, Colquhoun A, Newsholme EA. The effect of tumour bearing on skeletal muscle glutamine metabolism. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1991; 23:933-7. [PMID: 1773899 DOI: 10.1016/0020-711x(91)90082-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. The effects of tumour bearing on glutamine metabolism in rat skeletal muscle were examined using the Walker 256 carcinosarcoma. 2. There was a rapid and marked decrease in skeletal muscle glutamine content, which was correlated with the size of the tumour, and a decrease in plasma glutamine concentration. 3. The rate of release of glutamine from EDL muscle in vitro was increased in cachectic, tumour bearing animals, but was unaffected from the soleus muscle of the same animals. 4. It is hypothesized that the increase in the rate of muscle glutamine release during cachexia represents a response of this tissue in order to satisfy the demand for glutamine by the tumour or by cells of the immune system.
Collapse
|
34
|
Hoerr RA, Matthews DE, Bier DM, Young VR. Leucine kinetics from [2H3]- and [13C]leucine infused simultaneously by gut and vein. THE AMERICAN JOURNAL OF PHYSIOLOGY 1991; 260:E111-7. [PMID: 1987785 DOI: 10.1152/ajpendo.1991.260.1.e111] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In amino acid tracer kinetic studies of the fed state, ingested amino acid may be taken up during its initial transit through splanchnic tissues and thus not enter the plasma compartment where tracer is infused. To investigate this possibility, adult human subjects received simultaneous intravenous (iv) and intragastric (ig) leucine tracer infusions, first during a postabsorptive (PA) 4-h primed continuous ig infusion of L-[1-13C]-leucine and L-[5,5,5-2H3]leucine iv, followed on a separate day by a fed infusion, in which an ig infusion of a liquid formula was started 2 h before the tracer infusion and continued throughout the tracer study. Subjects were accustomed to a constant experimental diet supplying 1.5 g protein.kg-1.day-1 and 41-45 kcal.kg-1.day-1 for 7 and 12 days before the PA and fed studies, respectively. For the PA study, plasma enrichment for the ig tracer was 3.34 +/- 0.27 (SE) mol + excess and for the iv tracer it was 4.18 +/- 0.10 (P less than 0.02). Enrichments of alpha-keto-isocaproic acid (KIC) were 3.24 +/- 0.16 (ig) and 3.02 +/- 0.14 (iv), respectively [not significant (NS)]. For the fed study, plasma leucine enrichment for the ig tracer was 2.15 +/- 0.14 and for the iv tracer was 2.84 +/- 0.09 (P less than 0.02). KIC enrichments were 2.02 +/- 0.08 (ig) and 2.24 +/- 0.08 (iv), respectively (NS). In the PA study, the ratio of the plasma leucine enrichments for the ig and iv tracers was 0.80 +/- 0.06 and in the fed experiment, 0.76 +/- 0.05, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- R A Hoerr
- Laboratory of Human Nutrition, School of Science, Massachusetts Institute of Technology, Cambridge 02139
| | | | | | | |
Collapse
|
35
|
Parry-Billings M, Dimitriadis GD, Leighton B, Bond J, Bevan SJ, Opara E, Newsholme EA. Effects of hyperthyroidism and hypothyroidism on glutamine metabolism by skeletal muscle of the rat. Biochem J 1990; 272:319-22. [PMID: 2268261 PMCID: PMC1149701 DOI: 10.1042/bj2720319] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
1. The effects of hyperthyroidism and hypothyroidism on the concentrations of glutamine and other amino acids in the muscle and plasma and on the rates of glutamine and alanine release from incubated isolated stripped soleus muscle of the rat were investigated. 2. Hyperthyroidism decreased the concentration of glutamine in soleus muscle but was without effect on that in the gastrocnemius muscle or in the plasma. Hyperthyroidism also increased markedly the rate of release of glutamine from the incubated soleus muscle. 3. Hypothyroidism decreased the concentrations of glutamine in the gastrocnemius muscle and plasma but was without effect on that in soleus muscle. Hypothyroidism also decreased markedly the rate of glutamine release from the incubated soleus muscle. 4. Thyroid status was found to have marked effects on the rate of glutamine release by skeletal muscle per se, and may be important in the control of this process in both physiological and pathological conditions.
Collapse
|
36
|
Anderson IM, Parry-Billings M, Newsholme EA, Poortmans JR, Cowen PJ. Decreased plasma tryptophan concentration in major depression: relationship to melancholia and weight loss. J Affect Disord 1990; 20:185-91. [PMID: 2148339 DOI: 10.1016/0165-0327(90)90143-v] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Plasma total tryptophan (TRP) concentration was significantly lower in 31 patients with major depression compared to a healthy control group. The ratio of plasma TRP concentration to that of other branch chain amino acids (the TRP:BCAA ratio) was also decreased. Further analysis revealed that the decrease in plasma TRP and TRP:BCAA ratio was most apparent in patients with major depression and melancholia. Overall, women but not men had significantly decreased plasma tryptophan concentrations, perhaps because of a contributory effect of weight loss; this latter effect, however, could not be distinguished clearly from a diagnosis of melancholia. Our data suggest that in some depressed patients, reductions in plasma tryptophan availability may contribute to abnormalities in brain 5-hydroxytryptamine function.
Collapse
Affiliation(s)
- I M Anderson
- MRC Unit of Clinical Pharmacology, Littlemore Hospital, Oxford, U.K
| | | | | | | | | |
Collapse
|
37
|
Anderson IM, Parry-Billings M, Newsholme EA, Fairburn CG, Cowen PJ. Dieting reduces plasma tryptophan and alters brain 5-HT function in women. Psychol Med 1990; 20:785-791. [PMID: 2284387 DOI: 10.1017/s0033291700036473] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A three week low calorie diet significantly reduced both total plasma tryptophan and the ratio of tryptophan to competing amino acids in a group of 15 healthy volunteers. Despite a similar percentage weight loss the reduction in plasma tryptophan was greater in women than men. In addition, only in women was dieting associated with increased prolactin secretion following intravenous tryptophan, a measure of brain 5-hydroxytryptamine (5-HT) function. These results suggest that dieting reduces the availability of circulating tryptophan for brain 5-HT synthesis. Women appear more vulnerable than men both to this effect and to its consequences for brain 5-HT function. Altered brain 5-HT function may play a part in some of the psychological consequences of dieting, including the development of clinical eating disorders.
Collapse
Affiliation(s)
- I M Anderson
- University of Oxford, Department of Biochemistry
| | | | | | | | | |
Collapse
|
38
|
Affiliation(s)
- M Walser
- Johns Hopkins School of Medicine, Department of Pharmacology and Molecular Science, Baltimore, Maryland
| |
Collapse
|
39
|
Parry-Billings M, Leighton B, Dimitriadis GD, Bond J, Newsholme EA. Effects of physiological and pathological levels of glucocorticoids on skeletal muscle glutamine metabolism in the rat. Biochem Pharmacol 1990; 40:1145-8. [PMID: 2390110 DOI: 10.1016/0006-2952(90)90505-f] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effects of physiological and pathological concentrations of glucocorticoids were investigated using the glucocorticoid antagonist RU486 and the synthetic glucocorticoid dexamethasone, respectively. The effects of these treatments on the concentrations of glutamine and other amino acids in skeletal muscle and plasma and on the rates of release of glutamine and alanine from incubated preparations of skeletal muscle of the rat were investigated. Dexamethasone treatment increased the concentration of glutamine and the rate of release of this amino acid from incubated soleus muscle preparations. This treatment decreased the concentration of glutamine in both gastrocnemius and EDL muscles, but was without effect on the rate of glutamine release from EDL muscles. In contrast, administration of the glucocorticoid antagonist RU486 decreased the rate of glutamine release from muscle. It is concluded that glucocorticoids have marked effects on the metabolism of glutamine by skeletal muscle per se and that these hormones may be important in the control of the rate of glutamine release from muscle in both physiological and pathological conditions.
Collapse
|
40
|
Kiba N, Muto M, Furusawa M. High-performance liquid chromatographic determination of branched-chain alpha-keto acids in serum using immobilized leucine dehydrogenase as post-column reactor. JOURNAL OF CHROMATOGRAPHY 1989; 497:236-42. [PMID: 2625460 DOI: 10.1016/0378-4347(89)80023-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- N Kiba
- Department of Chemistry, Faculty of Engineering, Yamanashi University, Kofu, Japan
| | | | | |
Collapse
|
41
|
Schadewaldt P, Hummel W, Trautvetter U, Wendel U. A convenient enzymatic method for the determination of 4-methyl-2-oxopentanoate in plasma: comparison with high performance liquid chromatographic analysis. Clin Chim Acta 1989; 183:171-82. [PMID: 2507201 DOI: 10.1016/0009-8981(89)90333-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A simple and rapid spectrophotometric method for the estimation of 4-methyl-2-oxopentanoate in plasma samples by use of NAD+-dependent D-2-hydroxyisocaproate dehydrogenase from Lactobacillus casei ssp. pseudoplantarum is described. It is based on the kinetic measurement of the decrease of NADH absorbance at 334 nm. Applicability is demonstrated by comparative measurement of 4-methyl-2-oxopentanoate content in plasma of patients with maple syrup urine disease by the enzymatic and a reversed phase high performance liquid chromatographic method.
Collapse
Affiliation(s)
- P Schadewaldt
- Diabetes Forschungsinstitut, Universität Düsseldorf, FRG
| | | | | | | |
Collapse
|
42
|
Anderson IM, Crook WS, Gartside SE, Parry-Billings M, Newsholme EA, Cowen PJ. Effect of moderate weight loss on prolactin secretion in normal female volunteers. Psychiatry Res 1989; 29:161-7. [PMID: 2508140 DOI: 10.1016/0165-1781(89)90030-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sleep-related prolactin secretion and prolactin responses to the infusion of low doses of the dopamine antagonist, metoclopramide, and thyrotropin-releasing hormone were measured in 11 female volunteers before and after undertaking a diet in which they lost a mean of 3.1 kg in weight in 3 weeks. No effect of weight loss on these measures was found, but there was a significant, although modest, reduction in fasting plasma tryptophan concentration without any change in the concentration of competing amino acids.
Collapse
|
43
|
Blomstrand E, Perrett D, Parry-Billings M, Newsholme EA. Effect of sustained exercise on plasma amino acid concentrations and on 5-hydroxytryptamine metabolism in six different brain regions in the rat. ACTA PHYSIOLOGICA SCANDINAVICA 1989; 136:473-81. [PMID: 2473602 DOI: 10.1111/j.1748-1716.1989.tb08689.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sustained exercise to fatigue elicits no major differences either in plasma amino acid levels or in brain 5-hydroxytryptamine (5-HT) metabolism between sedentary and endurance-trained animals. Furthermore, 11 weeks of endurance training did not influence the maximal activity of the enzyme monoamine oxidase in the brain areas which were studied. In both sedentary and endurance-trained rats, sustained running to fatigue caused an increase in the plasma concentration ratio of free tryptophan/other large neutral amino acids and an increase in the concentration of tryptophan in the six brain areas that were studied. The increase was similar in the different regions of the brain and averaged 36%. Exercise caused an increase in the levels of 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in the brain stem (14 and 44% respectively) and hypothalamus (16 and 17% respectively) and an increase in the level of 5-HIAA in the hippocampus (21%) and striatum (28%). Exercise also caused an increase in the level of dopamine in the brain stem (56%) and hypothalamus (46%) and of nor adrenaline in the striatum (59%). Since the levels of 5-HT and dopamine were both increased in the brain stem and hypothalamus, it is possible that these changes may play important roles in the central effects of exercise, including both physical and mental fatigue and effects on mood.
Collapse
Affiliation(s)
- E Blomstrand
- Department of Biochemistry, University of Oxford, UK
| | | | | | | |
Collapse
|
44
|
Abumrad NN, Williams P, Frexes-Steed M, Geer R, Flakoll P, Cersosimo E, Brown LL, Melki I, Bulus N, Hourani H. Inter-organ metabolism of amino acids in vivo. DIABETES/METABOLISM REVIEWS 1989; 5:213-26. [PMID: 2656153 DOI: 10.1002/dmr.5610050302] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- N N Abumrad
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
May ME, Buse MG. Effects of branched-chain amino acids on protein turnover. DIABETES/METABOLISM REVIEWS 1989; 5:227-45. [PMID: 2656154 DOI: 10.1002/dmr.5610050303] [Citation(s) in RCA: 92] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Amino acid availability rapidly regulates protein synthesis and degradation. Increasing amino acid concentrations above the levels found in post-absorptive plasma stimulates protein synthesis in a dose-dependent manner at the level of mRNA translation-initiation and inhibits protein degradation by inhibiting lysosomal autophagy. The anabolic effects of insulin on protein synthesis and protein degradation are exerted at the same sites (i.e., peptide chain initiation and lysosomal stabilization) allowing for a rapid synergistic response when both amino acids and insulin increase after a protein-containing meal. In perfused liver preparations, protein anabolic effects are exerted by a group of amino acids acting in concert. The BCAA are among the amino acids required for stimulation of hepatic protein synthesis, but there is no evidence that BCAA or leucine alone are effective. Leucine alone is an important inhibitor of hepatic protein degradation, but maximal inhibition requires in addition several other regulatory amino acids. In heart and skeletal muscle in vitro, increasing the concentration of the three BCAA or of leucine alone reproduces the effects of increasing the supply of all amino acids in stimulating protein synthesis and inhibiting protein degradation. Skeletal muscle is the largest repository of metabolically active protein and a major contributor to total body nitrogen balance. Supplying energy alone (i.e., carbohydrate and lipids) cannot prevent negative nitrogen balance (net protein catabolism) in animals or humans; only provision of amino acids allows the attainment of nitrogen balance. In rats and in humans nourished parenterally, provision of balanced amino acid solutions or of only the three BCAA cause similar improvements in nitrogen balance for several days. There is some evidence that infusions of leucine alone can stimulate muscle protein synthesis in vivo; the effect may be transitory and was not observed by all investigators; provisions of excess leucine alone does not seem to affect total body or muscle protein degradation in vivo. In postabsorptive rats, in vivo, infusion of the three BCAA together stimulates muscle protein synthesis as much as the infusion of a complete amino acid mixture or of a mixture of essential amino acids; the in vivo effect requires coinfusion of glucose or of small (physiological) doses of insulin, suggesting synergism between insulin and amino acids.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- M E May
- Department of Internal Medicine, Vanderbilt University, Nashville, Tennessee 37203
| | | |
Collapse
|
46
|
Baranyai JM, Blum JJ. Quantitative analysis of intermediary metabolism in rat hepatocytes incubated in the presence and absence of ethanol with a substrate mixture including ketoleucine. Biochem J 1989; 258:121-40. [PMID: 2930501 PMCID: PMC1138332 DOI: 10.1042/bj2580121] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hepatocytes isolated from livers of fed rats were incubated with a mixture of glucose (10 mM), ribose (1.0 mM), acetate (1.25 mM), alanine (3.5 mM), glutamate (2.0 mM), aspartate (2.0 mM), 4-methyl-2-oxovaleric acid (ketoleucine) (3.0 mM), and, in paired flasks, 10 mM-ethanol. One substrate was 14C-radiolabelled in any given incubation. Incorporation of 14C into glucose, glycogen, CO2, lactate, alanine, aspartate, glutamate, acetate, urea, lipid glycerol, fatty acids and the 1- and 2,3,4-positions of ketone bodies was measured after 20 and 40 min of incubation under quasi-steady-state conditions. Data were analysed with the aid of a realistic structural metabolic model. In each of the four conditions examined, there were approx. 77 label incorporation measurements and several measurements of changes in metabolite concentrations. The considerable excess of measurements over the 37 independent flux parameters allowed for a stringent test of the model. A satisfactory fit to these data was obtained for each condition. There were large bidirectional fluxes along the gluconeogenic/glycolytic pathways, with net gluconeogenesis. Rates of ureagenesis, oxygen consumption and ketogenesis were high under all four conditions studied. Oxygen utilization was accurately predicted by three of the four models. There was complete equilibration between mitochondrial and cytosolic pools of acetate and of CO2, but for several of the metabolic conditions, two incompletely equilibrated pools of mitochondrial acetyl-CoA and oxaloacetate were required. Ketoleucine was utilized at a rate comparable to that reported by others in perfused liver and entered the mitochondrial pool of acetyl-CoA directly associated with ketone body formation. Ethanol, which was metabolized at rates comparable to those in vivo, caused relatively few changes in overall flux patterns. Several effects related to the increased NADH/NAD+ ratio were observed. Pyruvate dehydrogenase was completely inhibited and the ratio of acetoacetate to 3-hydroxybutyrate was decreased; flux through glutamate dehydrogenase, the citric acid cycle, and ketoleucine dehydrogenase were, however, only slightly inhibited. Net production of ATP occurred in all conditions studied and was increased by ethanol. Futile cycling was quantified at the glucose/glucose 6-phosphate, glycogen/glucose 6-phosphate, fructose 6-phosphate/fructose 1,6-bis-phosphate, and phosphoenolpyruvate/pyruvate/oxaloacetate substrate cycles. Cycling at these four loci consumed about 22% of cellular ATP production in control hepatocytes and 14% in ethanol-treated cells.
Collapse
Affiliation(s)
- J M Baranyai
- Department of Pharmacology, Duke University Medical Center, Durham, NC 27710
| | | |
Collapse
|
47
|
Beggs M, Shaw JM, Randle PJ. Longer-term regulation of branched-chain-2-oxoacid dehydrogenase complex studied in rat hepatocytes in culture. Biochem J 1989; 257:271-5. [PMID: 2920017 PMCID: PMC1135566 DOI: 10.1042/bj2570271] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of protein-free diet to decrease liver activity of branched-chain (-2-oxoacid) dehydrogenase (BCD) complex (active form) and increase BCD kinase activity was unaffected by preparation of hepatocytes, but partially reversed by 25 h of culture of hepatocytes in medium 199. Activation of BCD complex preceded loss of BCD kinase. The effect of culture on BCD complex was completely prevented by omission of branched-chain amino acids and partially prevented by 1 mM-alpha-cyano-4-hydroxycinnamate or 0.2 mM-pyruvate/2 mM-lactate. Protein-free diet decreased plasma branched-chain amino and oxo ('keto') acids and increased plasma pyruvate and lactate. It is concluded: (1) that branched-chain amino acids are involved directly in regulation of activities of BCD complex and BCD kinase; (2) that mitochondrial uptake of branched-chain oxo acids is necessary for regulation of BCD complex activity; and (3) that the stable increase in BCD kinase may function as a hysteresis mechanism.
Collapse
Affiliation(s)
- M Beggs
- Nuffield Department of Clinical Biochemistry, University of Oxford, U.K
| | | | | |
Collapse
|
48
|
Kiba N, Hori S, Furusawa M. Flow-injection determination of branched-chain L-amino acids with immobilized leucine dehydrogenase. Anal Chim Acta 1989. [DOI: 10.1016/s0003-2670(00)80295-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
49
|
Abstract
Total plasma tryptophan was significantly lower in 12 depressed patients than in 12 normal controls. The ratio of total tryptophan to neutral amino acids was also decreased in the depressed patients suggesting that tryptophan availability to the brain might be reduced. There was no correlation between basal tryptophan concentrations in the depressed subjects and the subsequent neuroendocrine response to intravenous tryptophan.
Collapse
Affiliation(s)
- P J Cowen
- University Department of Psychiatry, Littlemore Hospital, Oxford, U.K
| | | | | |
Collapse
|
50
|
Indo Y, Akaboshi I, Nobukuni Y, Endo F, Matsuda I. Maple syrup urine disease: a possible biochemical basis for the clinical heterogeneity. Hum Genet 1988; 80:6-10. [PMID: 3417306 DOI: 10.1007/bf00451447] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Nine patients with maple syrup urine disease (MSUD), of whom eight were detected by mass-screening of neonates for inherited metabolic disease, were studied to determine possible relationships between clinical features and properties of the branched-chain alpha-keto acid dehydrogenase complex (BCKDH) in cultured lymphoblastoid cells. Based on their tolerance for leucine and on the clinical manifestations observed after 2 years of age, most could be classified into three types; classical (tolerate less than 600 mg of leucine per day, N = 2), intermediate (N = 3) and intermittent (N = 3) types. In the other patient two of these three phenotypes were present. The BCKDH activities measured at a lower alpha-ketoisovaleric acid concentration (0.054 mM) were 0.026 +/- 0.015 in classical, 0.118 +/- 0.016 in intermediate and 0.625 +/- 0.139 in intermittent types and 7.052 +/- 0.779 (nmol/h per milligram of protein) in two controls, respectively; the differences being statistically significant (P less than 0.01, classical vs intermediate types; P less than 0.01, intermediate vs intermittent types; P less than 0.01, intermittent vs control). Kinetic and immunochemical analyses of the BCKDH revealed that, although there are a few exceptions, classical, intermediate and intermittent types correspond to the enzyme properties of sigmoidal kinetics with E1 beta subunit deficiency, near-sigmoidal kinetics with E1 beta subunit deficiency and hyperbolic kinetics with E2 subunit deficiency of the BCKDH, respectively.
Collapse
Affiliation(s)
- Y Indo
- Department of Pediatrics, Kumamoto University Medical School, Japan
| | | | | | | | | |
Collapse
|