Protein synthesis in skeletal muscle and jejunum is more responsive to feeding in 7-than in 26-day-old pigs

1996 ◽  
Vol 270 (5) ◽  
pp. E802-E809 ◽  
Author(s):  
T. A. Davis ◽  
D. G. Burrin ◽  
M. L. Fiorotto ◽  
H. V. Nguyen
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Plasma Concentrations ◽  
Postnatal Life ◽  
Tissue Protein ◽  
Igf I ◽  
Tissue Protein Synthesis ◽  
Stimulation Of

The study aimed to determine the developmental changes in the response of peripheral and visceral tissue protein synthesis to feeding during early postnatal life and the associated changes in circulating insulin, insulin-like growth factor (IGF-I), and amino acid concentrations. Tissue protein synthesis was measured in vivo with a large dose of L-[4(-3)H]phenylalanine in 7- and 26-day-old pigs that were either fasted for 24 h or refed for 2.75 h after a 24-h fast. Fractional rates of protein synthesis (Ks) in skeletal muscle, heart, and liver were greater in 7-than in 26-day-old pigs. Refeeding stimulated Ks in skeletal muscle, pancreas, jejunum, and liver of both 7-and 26-day-old pigs. The stimulation of skeletal muscle and jejunal Ks by refeeding was greater in 7- than in 26-day-old pigs. Plasma IGF-I concentrations were lower in 7- than in 26-day-old pigs. Plasma concentrations of insulin and amino acids increased with refeeding. The increase in plasma insulin concentrations with refeeding was greater in 7- than in 26-days-old pigs. These results indicate that the stimulation in skeletal muscle and jejunal protein synthesis by feeding is elevated in young compared with older suckling pigs. This enhanced stimulation of protein synthesis by feeding in neonatal pigs is associated with elevated circulating concentrations of insulin but not amino acids or IGF-I.

scholarly journals Acute IGF-I infusion stimulates protein synthesis in skeletal muscle and other tissues of neonatal pigs

2002 ◽  
Vol 283 (4) ◽  
pp. E638-E647 ◽  
Author(s):  
Teresa A. Davis ◽  
Marta L. Fiorotto ◽  
Douglas G. Burrin ◽  
Rhonda C. Vann ◽  
Peter J. Reeds ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Cardiac Muscle ◽  
Liver Protein ◽  
Tissue Protein ◽  
Neonatal Pigs ◽  
Igf I ◽  
Tissue Protein Synthesis ◽  
Insulin Replacement

Studies have shown that protein synthesis in skeletal muscle of neonatal pigs is uniquely sensitive to a physiological rise in both insulin and amino acids. Protein synthesis in cardiac muscle, skin, and spleen is responsive to insulin but not amino acid stimulation, whereas in the liver, protein synthesis responds to amino acids but not insulin. To determine the response of protein synthesis to insulin-like growth factor I (IGF-I) in this model, overnight-fasted 7- and 26-day-old pigs were infused with IGF-I (0, 20, or 50 μg · kg−1 · h−1) to achieve levels within the physiological range, while amino acids and glucose were clamped at fasting levels. Because IGF-I infusion lowers circulating insulin levels, an additional group of high-dose IGF-I-infused pigs was also provided replacement insulin (10 ng · kg−0.66 · min−1). Tissue protein synthesis was measured using a flooding dose ofl-[4-3H]phenylalanine. In 7-day-old pigs, low-dose IGF-I increased protein synthesis by 25–60% in various skeletal muscles as well as in cardiac muscle (+38%), skin (+24%), and spleen (+32%). The higher dose of IGF-I elicited no further increase in protein synthesis above that found with the low IGF-I dose. Insulin replacement did not alter the response of protein synthesis to IGF-I in any tissue. The IGF-I-induced increases in tissue protein synthesis decreased with development. IGF-I infusion, with or without insulin replacement, had no effect on protein synthesis in liver, jejunum, pancreas, or kidney. Thus the magnitude, tissue specificity, and developmental change in the response of protein synthesis to acute physiological increases in plasma IGF-I are similar to those previously observed for insulin. This study provides in vivo data indicating that circulating IGF-I and insulin act on the same signaling components to stimulate protein synthesis and that this response is highly sensitive to stimulation in skeletal muscle of the neonate.

GH and IGF-I differentially increase protein synthesis in skeletal muscle and jejunum of parenterally fed rats

1996 ◽  
Vol 271 (5) ◽  
pp. E872-E878 ◽  
Author(s):  
H. C. Lo ◽  
D. M. Ney
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Body Weight Gain ◽  
Serum Insulin ◽  
Jejunal Mucosa ◽  
Tissue Mass ◽  
Tissue Protein ◽  
Igf I ◽  
Tissue Protein Synthesis

Growth hormone (GH) and insulin-like growth factor I (IGF-I) selectively increase tissue mass. We compared the fractional rate of protein synthesis (Ks in skeletal muscle, jejunal mucosa and muscularis, and liver to investigate the differential effects of GH and IGF-I on tissue protein synthesis. Surgically stressed rats were maintained with hypocaloric total parenteral nutrition (TPN) and given recombinant human (rh) GH (rhGH), rhIGF-I, rhGH + rhIGF-I (800 or 800 + 800 micrograms/day, respectively), or TPN alone. After 3 days, a flooding dose of valine (800 mumol with 5.56 MBq L-[3,4-3H]valine) was administered, and rats were killed 20 min later. Body weight gain, nitrogen retention, and serum IGF-I concentrations confirmed that GH plus IGF-I additively increased anabolism. Serum insulin concentrations were significantly increased by GH and decreased by IGF-I. GH significantly increased Ks in skeletal muscle and jejunal muscularis, IGF-I significantly increased Ks in jejunal mucosa and muscularis, and neither GH nor IGF-I altered Ks in liver. GH and IGF-I differentially increase tissue protein synthesis in vivo.

Intrauterine growth restriction does not alter response of protein synthesis to feeding in newborn pigs

1997 ◽  
Vol 272 (5) ◽  
pp. E877-E884 ◽  
Author(s):  
T. A. Davis ◽  
M. L. Fiorotto ◽  
D. G. Burrin ◽  
W. G. Pond ◽  
H. V. Nguyen
Keyword(s):  
Protein Synthesis ◽  
Intrauterine Growth Restriction ◽  
Plasma Insulin ◽  
Growth Restriction ◽  
Tissue Protein ◽  
Intrauterine Growth ◽  
Igf I ◽  
Tissue Protein Synthesis ◽  
Newborn Pigs

This study aimed to determine the effect of intrauterine growth restriction (IUGR) on the acute response of tissue protein synthesis to feeding in newborn pigs. Newborn pigs of sows fed either control or protein-restricted diets throughout gestation were designated C or IUGR, respectively. Both groups were either fasted for 9 h after birth or fed hourly 30 ml colostrum/kg body wt for 2.75 h after a 6-h fast. Fractional rates of tissue protein synthesis (Ks) were measured in vivo with a flooding dose of L-[4-3H]phenylalanine. Birth weight was reduced by 33% in IUGR pigs. IUGR had no effect on Ks in skeletal muscles, heart, liver, jejunum, or pancreas. Feeding stimulated tissue Ks similarly in C and IUGR pigs. Fasting plasma insulin concentrations and their rise with feeding were unaffected by IUGR. Plasma insulin-like growth factor I (IGF-I) concentrations were reduced by 42% in IUGR pigs and were not altered by feeding in either IUGR or C pigs. There were positive nonlinear relationships between tissue Ks and circulating concentrations of insulin. The results indicate that, in newborn pigs, tissue Ks are unaffected by IUGR, despite reduced plasma IGF-I concentrations. The efficiency with which nutrients stimulate tissue Ks is also not altered by IUGR, perhaps because the rise in plasma insulin concentrations with feeding is unaffected by IUGR.

Interaction of amino acids and insulin in the regulation of protein metabolism in growing animals

2003 ◽  
Vol 83 (3) ◽  
pp. 357-364 ◽  
Author(s):  
T. A. Davis ◽  
A. Suryawan ◽  
J. A. Bush ◽  
P. M. J. O’Connor ◽  
M. C. Thivierge
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Intracellular Signaling ◽  
Intracellular Signaling Pathways ◽  
Dietary Amino Acids ◽  
Initiation Of Translation ◽  
Tissue Protein Synthesis ◽  
Key Words Muscle ◽  
Stimulation Of

Young animals utilize their dietary amino acids more efficiently for growth because they are capable of a greater increase in tissue protein synthesis in response to feeding than older animals. This response to feeding is particularly profound in skeletal muscle. The feeding-induced stimulation of protein synthesis in skeletal muscle is uniquely and independently regulated by both insulin and amino acids. In most visceral tissues, the stimulation of protein synthesis by feeding is mediated by amino acids alone and not by insulin. The stimulation of protein synthesis by nutrition and hormones is regulated by alterations in the expression and activity of components of the intracellular signaling pathways that control the initiation of translation. Key words: Muscle, pigs, neonate, protein synthesis, insulin, amino acids

Growth hormone acutely stimulates forearm muscle protein synthesis in normal humans

1991 ◽  
Vol 260 (3) ◽  
pp. E499-E504 ◽  
Author(s):  
D. A. Fryburg ◽  
R. A. Gelfand ◽  
E. J. Barrett
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Igf I ◽  
Normal Humans

The short-term effects of growth hormone (GH) on skeletal muscle protein synthesis and degradation in normal humans are unknown. We studied seven postabsorptive healthy men (age 18-23 yr) who received GH (0.014 micrograms.kg-1.min-1) via intrabrachial artery infusion for 6 h. The effects of GH on forearm amino acid and glucose balances and on forearm amino acid kinetics [( 3H]Phe and [14C]Leu) were determined after 3 and 6 h of the GH infusion. Forearm deep vein GH rose to 35 +/- 6 ng/ml in response to GH, whereas systemic levels of GH, insulin, and insulin-like growth factor I (IGF-I) were unchanged. Forearm glucose uptake did not change during the study. After 6 h, GH suppressed forearm net release (3 vs. 6 h) of Phe (P less than 0.05), Leu (P less than 0.01), total branched-chain amino acids (P less than 0.025), and essential neutral amino acids (0.05 less than P less than 0.1). The effect on the net balance of Phe and Leu was due to an increase in the tissue uptake for Phe (71%, P less than 0.05) and Leu (37%, P less than 0.005) in the absence of any significant change in release of Phe or Leu from tissue. In the absence of any change in systemic GH, IGF-I, or insulin, these findings suggest that locally infused GH stimulates skeletal muscle protein synthesis. These findings have important physiological implications for both the role of daily GH pulses and the mechanisms through which GH can promote protein anabolism.

scholarly journals Amino acid requirement for the growth-hormone stimulation of incorporation of precursors into protein and nucleic acids of liver slices

1970 ◽  
Vol 119 (4) ◽  
pp. 629-634 ◽  
Author(s):  
M. J. Clemens ◽  
A. Korner
Keyword(s):  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Mechanism Of Action ◽  
Plasma Concentrations ◽  
Liver Slices ◽  
Hypophysectomized Rats ◽  
Stimulation Of

1. Incorporation of [14C]leucine into protein in rat liver slices, incubated in vitro, increased as the concentration of unlabelled amino acids in the incubation medium was raised. A plateau of incorporation was reached when the amino acid concentration was 6 times that present in rat plasma. Labelling of RNA by [3H]orotic acid was not stimulated by increased amino acid concentration in the incubation medium. 2. When amino acids were absent from the medium, or present at the normal plasma concentrations, no effect of added growth hormone on labelling of protein or RNA by precursor was observed. 3. When amino acids were present in the medium at 6 times the normal plasma concentrations addition of growth hormone stimulated incorporation of the appropriate labelled precursor into protein of liver slices from normal rats by 31%, and into RNA by 22%. A significant effect was seen at a hormone concentration as low as 10ng/ml. 4. Under the same conditions addition of growth hormone also stimulated protein labelling in liver slices from hypophysectomized rats. Tissue from hypophysectomized rats previously treated with growth hormone did not respond to growth hormone in vitro. 5. No effect of the hormone on the rate or extent of uptake of radioactive precursors into acid-soluble pools was found. 6. Cycloheximide completely abolished the hormone-induced increment in labelling of both RNA and protein. 7. It was concluded that, in the presence of an abundant amino acid supply, growth hormone can stimulate the synthesis of protein in rat liver slices by a mechanism that is more sensitive to cycloheximide than is the basal protein synthesis. The stimulation of RNA labelling observed in the presence of growth hormone may be a secondary consequence of the hormonal effect on protein synthesis. 8. The mechanism of action of growth hormone on liver protein synthesis in vitro was concluded to be similar to its mechanism of action in vivo.

Role of eIF4E in stimulation of protein synthesis by IGF-I in perfused rat skeletal muscle

2000 ◽  
Vol 278 (1) ◽  
pp. E58-E64 ◽  
Author(s):  
Thomas C. Vary ◽  
Leonard S. Jefferson ◽  
Scot R. Kimball
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Initiation Factor ◽  
Translational Efficiency ◽  
Rat Skeletal Muscle ◽  
Phosphorylation State ◽  
Factor I ◽  
Igf I ◽  
Stimulation Of

Insulin-like growth factor I (IGF-I) promotes anabolism by stimulating protein synthesis in skeletal muscle. In the present study, we have examined mechanisms by which IGF-I stimulates protein synthesis in skeletal muscle with a perfused rat hindlimb preparation. IGF-I (10 nM) stimulated protein synthesis over 2.7-fold. Total RNA content was unaffected, but translational efficiency was increased by IGF-I. We next examined the effect of IGF-I on eukaryotic initiation factor (eIF) 4E as a mechanism regulating translation initiation. IGF-I did not alter either the amount of eIF4E associated with the eIF4E binding protein 4E-BP1 or the phosphorylation state of 4E-BP1. Likewise, the phosphorylation state of eIF4E was unaltered by IGF-I. In contrast, the amount of eIF4E bound to eIF4G was increased threefold by IGF-I. We conclude that IGF-I regulates protein synthesis in skeletal muscle by enhancing formation of the active eIF4E ⋅ eIF4G complex.

Interactions of deoxynivalenol and lipopolysaccharides on tissue protein synthesis in pigs

2013 ◽  
Vol 6 (2) ◽  
pp. 185-197 ◽  
Author(s):  
K. Kullik ◽  
B. Brosig ◽  
S. Kersten ◽  
H. Valenta ◽  
A.-K. Diesing ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Control Diet ◽  
Live Weight ◽  
The Body ◽  
Tissue Protein ◽  
Fusarium Toxin ◽  
Synthesis Parameters ◽  
Tissue Protein Synthesis

Possible interactions between the Fusarium toxin deoxynivalenol and lipopolysaccharides on in vivo protein synthesis were investigated in selected porcine tissues. A total of 36 male castrated pigs (initial weight of 26 kg) were used. 24 pigs were fed a control diet and 12 a Fusarium-contaminated diet (chronic oral deoxynivalenol, 3.1 mg/kg diet) for 37 days. Tissue protein synthesis was measured in pigs fed control diet after intravenous infusion of deoxynivalenol (100 µg/kg live weight/h), lipopolysaccharides (7.5 µg/kg live weight/h) or a combination of both compounds on the day of the measurements, while six pigs from the chronic oral deoxynivalenol group were intravenously treated with lipopolysaccharides (7.5 µg/kg live weight/h). Deoxynivalenol challenge alone failed to alter protein synthesis parameters. Fractional protein synthesis rates were exclusively reduced in liver, spleen and small intestine of lipopolysaccharides-treated pigs. Intravenous deoxynivalenol co-exposure enhanced the impacts of lipopolysaccharides on protein synthesis parameters in the spleen and the small intestine to some extent, while a chronic oral pre-exposure with deoxynivalenol relieved its effects in the spleen. Whether these interactions occur in other tissues and under other study conditions, especially toxin doses and route of entry into the body, needs to be examined further.

Anaesthetic Agents and Their Effect on Tissue Protein Synthesis in the Rat

1989 ◽  
Vol 77 (6) ◽  
pp. 651-655 ◽  
Author(s):  
S. D. Heys ◽  
A. C. Norton ◽  
C. R. Dundas ◽  
O. Eremin ◽  
K. Ferguson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Young Male ◽  
Male Rats ◽  
Liver Protein ◽  
Arterial Blood Gas ◽  
Anaesthetic Agents ◽  
Arterial Blood ◽  
Tissue Protein Synthesis

1. Rates of protein synthesis were measured, in vivo, in lung, liver, heart and skeletal muscle of young male rats. Groups of rats were exposed for 1 h duration to one of the following anaesthetic regimens: 1.4% halothane, 2.2% halothane, 1.4% halothane in 66% nitrous oxide, intravenous pentobarbitone (20 mg/kg) and intravenous midazolam (18 mg/kg) combined with fentanyl (2 μg/kg). Fractional rates of protein synthesis were determined by injecting [3H]phenylalanine (150 μmol/100 g body weight) 2. Liver protein synthesis was depressed significantly by all regimens, except midazolam/fentanyl, by up to 37.7% of control values. Lung protein synthesis was significantly reduced by all the anaesthetic agents by up to 30% of control rates 3. The effects of the anaesthetic agents on skeletal muscle and heart were small and not statistically significant 4. There was no evidence of ventilatory depression as manifested by changes in arterial blood gas partial pressures of CO2 and O2, except in the group treated with 2.2% halothane.

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