Somatotropin increases protein balance by lowering body protein degradation in fed, growing pigs

2000 ◽  
Vol 278 (3) ◽  
pp. E477-E483 ◽  
Author(s):  
Rhonda C. Vann ◽  
Hanh V. Nguyen ◽  
Peter J. Reeds ◽  
Douglas G. Burrin ◽  
Marta L. Fiorotto ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Growing Pigs ◽  
Whole Body ◽  
Plasma Urea ◽  
Body Protein ◽  
Fed State ◽  
Protein Deposition ◽  
Leucine Oxidation ◽  
Urea Production

Somatotropin (ST) administration enhances protein deposition in well-nourished, growing animals. To determine whether the anabolic effect is due to an increase in protein synthesis or a decrease in proteolysis, pair-fed, weight-matched (∼20 kg) growing swine were treated with porcine ST (150 μg ⋅ kg− 1 ⋅ day− 1, n = 6) or diluent ( n = 6) for 7 days. Whole body leucine appearance (Ra), nonoxidative leucine disposal (NOLD), urea production, and leucine oxidation, as well as tissue protein synthesis (Ks), were determined in the fed steady state using primed continuous infusions of [13C]leucine, [13C]bicarbonate, and [15N2]urea. ST treatment increased the efficiency with which the diet was used for growth. ST treatment also increased plasma insulin-like growth factor I (+100%) and insulin (+125%) concentrations and decreased plasma urea nitrogen concentrations (−53%). ST-treated pigs had lower leucine Ra (−33%), leucine oxidation (−63%), and urea production (−70%). However, ST treatment altered neither NOLD nor Ks in the longissimus dorsi, semitendinosus, or gastrocnemius muscles, liver, or jejunum. The results suggest that in the fed state, ST treatment of growing swine increases protein deposition primarily through a suppression of protein degradation and amino acid catabolism rather than a stimulation of protein synthesis.

Amino acid metabolism after intense exercise

1990 ◽  
Vol 258 (2) ◽  
pp. E249-E255 ◽  
Author(s):  
J. T. Devlin ◽  
I. Brodsky ◽  
A. Scrimgeour ◽  
S. Fuller ◽  
D. M. Bier
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Recovery Period ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein ◽  
Leucine Oxidation

We studied postexercise amino acid metabolism, in the whole body and across the forearm. Seven volunteers were infused with L-[alpha-15N]lysine and L-[1-13C]-leucine twice [one time during 3 h after cycle exercise (75% VO2max), and one time in the resting state]. Whole body protein breakdown was estimated from dilution of L-[alpha-15N]lysine and L-[1-13C]ketoisocaproic acid (KIC) enrichments in plasma. Leucine oxidation was calculated from 13CO2 enrichments in expired air. Whole body protein breakdown was not increased above resting levels during the recovery period. Leucine oxidation was decreased after exercise (postexercise 13 +/- 2.3 vs. resting 19 +/- 3.2 mumol.kg-1.h-1; P less than 0.02), while nonoxidative leucine disposal was increased (115 +/- 6.1 vs. 103 +/- 5.6 micrograms.kg-1.min-1; P less than 0.02). After exercise, forearm net lysine balance was unchanged (87 +/- 25 vs. 93 +/- 28 nmol.100 ml-1.min-1), but there were decreases in forearm muscle protein degradation (219 +/- 51 vs. 356 +/- 85 nmol.100 ml-1.min-1; P less than 0.05) and synthesis (132 +/- 41 vs. 255 +/- 69 nmol.100 ml-1.min-1; P less than 0.01). In conclusion, after exercise 1) whole body protein degradation is not increased, 2) leucine disposal is directed away from oxidative and toward nonoxidative pathways, 3) forearm protein synthesis is decreased. Postexercise increases in whole body protein synthesis occur in tissues other than nonexercised muscle.

Somatotropin-induced protein anabolism in hindquarters and portal-drained viscera of growing pigs

2003 ◽  
Vol 284 (2) ◽  
pp. E302-E312 ◽  
Author(s):  
Jill A. Bush ◽  
Douglas G. Burrin ◽  
Agus Suryawan ◽  
Pamela M. J. O'Connor ◽  
Hanh V. Nguyen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Growing Pigs ◽  
Whole Body ◽  
Fed State

To differentiate the effect of somatotropin (ST) treatment on protein metabolism in the hindquarter (HQ) and portal-drained viscera (PDV), growing swine ( n = 20) treated with ST (0 or 150 μg · kg−1 · day−1) for 7 days were infused intravenously with NaH13CO3 and [2H5]phenylalanine and enterally with [1-13C]phenylalanine while in the fed state. Arterial, portal venous, and vena cava whole blood samples, breath samples, and blood flow measurements were obtained for determination of tissue and whole body phenylalanine kinetics under steady-state conditions. In the fed state, ST treatment decreased whole body phenylalanine flux, oxidation, and protein degradation without altering protein synthesis, resulting in an improvement in whole body net protein balance. Blood flow to the HQ (+80%), but not to the PDV, was increased with ST treatment. In the HQ and PDV, ST increased phenylalanine uptake (+44 and +23%, respectively) and protein synthesis (+43 and +41%, respectively), with no effect on protein degradation. In ST-treated and control pigs, phenylalanine was oxidized in the PDV (34–43% of enteral and arterial sources) but not the HQ. In both treatment groups, dietary (40%) rather than arterial (10%) extraction of phenylalanine predominated in gut amino acid metabolism, whereas localized blood flow influenced HQ amino acid metabolism. The results indicate that ST increases protein anabolism in young, growing swine by increasing protein synthesis in the HQ and PDV, with no effect on protein degradation. Differing results between the whole body and the HQ and PDV suggest that the effect of ST treatment on protein metabolism is tissue specific.

scholarly journals Immune System Stimulation Reduces the Efficiency of Whole-Body Protein Deposition and Alters Muscle Fiber Characteristics in Growing Pigs

Animals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 323 ◽  
Author(s):  
Whitney D. McGilvray ◽  
Bradley Johnson ◽  
Hailey Wooten ◽  
Amanda R. Rakhshandeh ◽  
Anoosh Rakhshandeh
Keyword(s):  
Protein Synthesis ◽  
Immune System ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Growing Pigs ◽  
Whole Body ◽  
Repeated Injection ◽  
Body Protein ◽  
Protein Deposition ◽  
Degradation Rates

The effects of immune system stimulation (ISS), induced by repeated injection of Escherichia coli lipopolysaccharide, on the whole-body protein synthesis versus degradation rates, the efficiency of protein deposition (PD), and muscle fiber characteristics in pigs were evaluated. Twelve growing gilts were assigned to two levels of amino acid intake that was predicted based on the potential of each group’s health status for PD and feed intake. Isotope tracer, nitrogen balance, and immunohistochemical staining techniques were used to determine protein turnover, PD, and muscle fiber characteristics, respectively. Protein synthesis, degradation, and PD were lower in immune-challenged pigs than in control pigs (p < 0.05). Strong tendencies for a higher protein synthesis-to-PD ratio (p = 0.055) and a lower protein synthesis-to-degradation ratio (p = 0.065) were observed in immune-challenged pigs. A decrease in muscle cross-sectional area of fibers and a shift from myosin heavy chain (MHC)-II towards MHC-I fibers (p < 0.05) were observed in immune-challenged pigs. These results indicated that ISS reduces PD not only by suppressing the whole-body protein synthesis and degradation rates, but also by decreasing the efficiency of PD in growing pigs. In addition, ISS induces atrophy in skeletal muscles and favors a slow-twitch oxidative fiber type composition.

Somatotropin increases protein balance independent of insulin's effects on protein metabolism in growing pigs

2000 ◽  
Vol 279 (1) ◽  
pp. E1-E10 ◽  
Author(s):  
Rhonda C. Vann ◽  
Hanh V. Nguyen ◽  
Peter J. Reeds ◽  
Norman C. Steele ◽  
Daniel R. Deaver ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Metabolism ◽  
Growing Pigs ◽  
Whole Body ◽  
Metabolic Responses ◽  
Glucose Disposal ◽  
Blood Levels ◽  
Protein Balance ◽  
Protein Deposition ◽  
Leucine Oxidation

Somatotropin (ST) administration enhances protein deposition and elicits profound metabolic responses, including hyperinsulinemia. To determine whether the anabolic effect of ST is due to hyperinsulinemia, pair-fed weight-matched growing swine were treated with porcine ST (150 μg · kg body wt−1 · day−1) or diluent for 7 days ( n = 6/group, ∼20 kg). Then pancreatic glucose-amino acid clamps were performed after an overnight fast. The objective was to reproduce the insulin levels of 1) fasted control and ST pigs (basal insulin, 5 μU/ml), 2) fed control pigs (low insulin, 20 μU/ml), and 3) fed ST pigs (high insulin, 50 μU/ml). Amino acid and glucose disposal rates were determined from the infusion rates necessary to maintain preclamp blood levels of these substrates. Whole body nonoxidative leucine disposal (NOLD), leucine appearance (Ra), and leucine oxidation were determined with primed, continuous infusions of [13C]leucine and [14C]bicarbonate. ST treatment was associated with higher NOLD and protein balance and lower leucine oxidation and amino acid and glucose disposals. Insulin lowered Ra and increased leucine oxidation, protein balance, and amino acid and glucose disposals. These effects of insulin were suppressed by ST treatment; however, the protein balance remained higher in ST pigs. The results show that ST treatment inhibits insulin's effects on protein metabolism and indicate that the stimulation of protein deposition by ST treatment is not mediated by insulin. Comparison of the protein metabolic responses to ST treatment during the basal fasting period with those in the fully fed state from a previous study suggests that the mechanism by which ST treatment enhances protein deposition is influenced by feeding status.

Leucine metabolism in lactating and dry goats: effect of insulin and substrate availability

1993 ◽  
Vol 265 (3) ◽  
pp. E402-E413 ◽  
Author(s):  
S. Tesseraud ◽  
J. Grizard ◽  
E. Debras ◽  
I. Papet ◽  
Y. Bonnet ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Whole Body ◽  
Initial Slope ◽  
Sensitivity Index ◽  
Early Lactation ◽  
Dry Period ◽  
Body Protein ◽  
Lactating Goats

Early lactating goats show insulin resistance with respect to extramammary glucose utilization. However, much less is known about the two major factors, insulin and plasma amino acid concentration, that regulate protein metabolism in lactating goats. To examine this question, the in vivo effect of acute insulin was studied in goats during early lactation (12-31 days postpartum), midlactation (98-143 days postpartum), and the dry period (approximately 1 yr postpartum). Insulin was infused (at 0.36 or 1.79 nmol/min) under euglycemic and eukaliemic clamps. In addition, appropriate amino acid infusion was used to blunt insulin-induced hypoaminoacidemia or to create hyperaminoacidemia and maintain this condition under insulin treatment. Leucine kinetics were assessed using a primed continuous infusion of L-[1-14C]-leucine, which started 2.5 h before insulin. In all animals the insulin treatments failed to stimulate the nonoxidative leucine disposal (an estimate of whole body protein synthesis) under both euaminoacidemic and hyperaminoacidemic conditions. Thus, in goat as well as humans, infusion of insulin fails to stimulate protein synthesis even when combined with a substantially increased provision of amino acids. In contrast, insulin treatments caused a dose-dependent inhibition of the endogenous leucine appearance (an estimate of whole body protein degradation). Under euaminoacidemia the initial slope from the plot of the endogenous leucine appearance as a function of plasma insulin (an insulin sensitivity index) was steeper during early lactation than when compared with the dry period. A similar trend occurred during midlactation but not to any significant degree. These differences were abolished under hyperaminoacidemia. It was concluded that the ability of physiological insulin to inhibit protein degradation was improved during lactation, demonstrating a clear-cut dissociation between the effects of insulin on protein and glucose metabolism. This adaptation no doubt may provide a mechanism to save body protein.

scholarly journals Fed-state clamp stimulates cellular mechanisms of muscle protein anabolism and modulates glucose disposal in normal men

2009 ◽  
Vol 296 (1) ◽  
pp. E105-E113 ◽  
Author(s):  
Olasunkanmi A. J. Adegoke ◽  
Stéphanie Chevalier ◽  
José A. Morais ◽  
Réjeanne Gougeon ◽  
Scot R. Kimball ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Translation Initiation ◽  
Muscle Protein ◽  
Whole Body ◽  
Glucose Disposal ◽  
Metabolic Clearance ◽  
Cellular Mechanisms ◽  
Body Protein ◽  
Fed State ◽  
Mtorc1 Signaling

Since maximum anabolism occurs postprandially, we developed a simulated fed state with clamped hyperinsulinemia, physiological hyperglycemia, and hyperaminoacidemia (Hyper-3) and explored muscle cellular mechanisms. Whole body [1-13C]leucine and [3-3H]glucose kinetics in healthy men were compared between hyperinsulinemic, euglycemic, isoaminoacidemic (Hyper-1, n = 10) and Hyper-3 ( n = 9) clamps. In Hyper-3 vs. Hyper-1, nonoxidative leucine Rd [rate of disappearance (synthesis)] was stimulated more (45 ± 4 vs. 24 ± 4 μmol/min, P < 0.01) and endogenous Ra [rate of appearance (breakdown)] was inhibited similarly; hence net balance increased more (86 ± 6 vs. 49 ± 2 μmol/min, P < 0.001). Glucose Rd was similar; thus Hyper-3 metabolic clearance rate (331 ± 23 vs. 557 ± 41 ml/min, P < 0.0005) and Rd/insulin (M, 0.65 ± 0.10 vs. 1.25 ± 0.10 mg·min−1·pmol−1·l, P < 0.001) were less, despite higher insulin (798 ± 74 vs. 450 ± 24 pmol/l, P < 0.005). In vastus lateralis muscle biopsies, phosphorylation of Akt ( P = 0.025), mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (p70S6K1; P = 0.008), S6 ( P = 0.049), and 4E-binding protein 1 (4E-BP1; P = 0.001) increased. With decreased eukaryotic initiation factor-4E (eIF4E)·4E-BP1 complex ( P = 0.01), these are consistent with increased mTOR complex 1 (mTORC1) signaling and translation initiation of protein synthesis. Although mRNA expression of ubiquitin, MAFbx 1, and MuRF-1 was unchanged, total ubiquitinated proteins decreased 20% ( P < 0.01), consistent with proteolysis suppression. The Hyper-3 clamp increases whole body protein synthesis, net anabolism, and muscle protein translation initiation pathways and decreases protein ubiquitination. The main contribution of hyperaminoacidemia is stimulation of synthesis rather than inhibition of proteolysis, and it attenuates the expected increment of glucose disposal.

scholarly journals Anabolic signaling and protein deposition are enhanced by intermittent compared with continuous feeding in skeletal muscle of neonates

2012 ◽  
Vol 302 (6) ◽  
pp. E674-E686 ◽  
Author(s):  
Samer W. El-Kadi ◽  
Agus Suryawan ◽  
Maria C. Gazzaneo ◽  
Neeraj Srivastava ◽  
Renán A. Orellana ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Muscle Protein ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Whole Body ◽  
Signaling Proteins ◽  
Protein Deposition ◽  
Intermittent Bolus ◽  
Continuous Feeding

Orogastric tube feeding is indicated for neonates with impaired ability to ingest and can be administered by intermittent bolus or continuous schedule. Our aim was to determine whether feeding modalities affect muscle protein deposition and to identify mechanisms involved. Neonatal pigs were overnight fasted (FAS) or fed the same amount of food continuously (CON) or intermittently (INT; 7 × 4 h meals) for 29 h. For 8 h, between hours 20 and 28, pigs were infused with [2H5]phenylalanine and [2H2]tyrosine, and amino acid (AA) net balances were measured across the hindquarters. Insulin, branched-chain AA, phenylalanine, and tyrosine arterial concentrations and whole body phenylalanine and tyrosine fluxes were greater for INT after the meal than for CON or FAS. The activation of signaling proteins leading to initiation of mRNA translation, including eukaryotic initiation factor (eIF)4E·eIF4G complex formation in muscle, was enhanced by INT compared with CON feeding or FAS. Signaling proteins of protein degradation were not affected by feeding modalities except for microtubule-associated protein light chain 3-II, which was highest in the FAS. Across the hindquarters, AA net removal increased for INT but not for CON or FAS, with protein deposition greater for INT. This was because protein synthesis increased following feeding for INT but remained unchanged for CON and FAS, whereas there was no change in protein degradation across any dietary treatment. These results suggest that muscle protein accretion in neonates is enhanced with intermittent bolus to a greater extent than continuous feeding, mainly by increased protein synthesis.

The Fed-State Clamp Increases Whole-Body Protein Anabolism by Activation of Plasma and Muscle Protein Synthesis, in Healthy Men

2008 ◽  
Vol 32 (4) ◽  
pp. 341
Author(s):  
Stéphanie Chevalier ◽  
Olasunkanmi A.J. Adegoke ◽  
Linda Wykes ◽  
José A. Morais ◽  
Réjeanne Gougeon ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Body Protein ◽  
Fed State ◽  
Healthy Men
Sign in / Sign up

Export Citation Format

Share Document