scholarly journals Protein synthesis during the developmental growth of the small and large intestine of the rat

1984 ◽  
Vol 217 (2) ◽  
pp. 527-534 ◽  
Author(s):  
D F Goldspink ◽  
S E M Lewis ◽  
F J Kelly
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Large Intestine ◽  
Post Partum ◽  
Whole Body ◽  
Fractional Rate ◽  
Body Tissues ◽  
Developmental Growth ◽  
Small And Large Intestine

The developmental growth and associated changes in protein synthesis were measured (in vivo) in the combined small and large intestine from 18 days in utero to 105 weeks post partum. Similar post-natal (3-105 weeks) changes were also studied in the separated large and small intestine, and in the mucosal and muscularis externa + serosal layers of the small intestine. Although the protein and nucleic acid contents of the whole intestine increased throughout both pre- and post-natal life, the maximal (11%) intestinal contribution to whole-body growth occurred 3 weeks after birth; this value declined to only 2.5-3.5% at both extremes of the age range studied. Between the 18-day foetus and old age the fractional rate of protein synthesis decreased from 107 to 61% per day. This developmental decline (43%) was, however, much smaller than that found in most other body tissues over the same period. Similar developmental trends (between weaning and senility) were found in both the small and the large intestine when studied separately, the small intestine in all respects contributing proportionately more than the large intestine to both the combined intestinal and whole-body values. At each age the large intestine possessed significantly lower fractional rates of synthesis and associated ribosomal activities. For the most part, the fractional synthesis rates in the mucosa and serosa of the small intestine were very similar, with each declining slightly with increasing age. These developmental changes are discussed with respect to functional aspects within the gastrointestinal tract.

scholarly journals Contribution of rat liver and gastrointestinal tract to whole-body protein synthesis in the rat

1980 ◽  
Vol 186 (1) ◽  
pp. 381-383 ◽  
Author(s):  
M A McNurlan ◽  
P J Garlick
Keyword(s):  
Protein Synthesis ◽  
Gastrointestinal Tract ◽  
Rat Liver ◽  
Large Intestine ◽  
Whole Body ◽  
Body Protein ◽  
Small And Large Intestine

The rate of protein synthesis was assessed in liver, stomach, small and large intestine and in the whole body of rats by injection of 100 mumol of [14C]leucine/100 g body wt. In each of the tissues turnover was very rapid, so that taken together they accounted for 43% of the protein synthesized by the whole animal.

Gastrointestinal tract protein synthesis and mRNA levels for proteolytic systems in adult fasted rats

1996 ◽  
Vol 271 (2) ◽  
pp. E232-E238 ◽  
Author(s):  
S. E. Samuels ◽  
D. Taillandier ◽  
E. Aurousseau ◽  
Y. Cherel ◽  
Y. Le Maho ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Mrna Levels ◽  
Protein Mass ◽  
Fractional Rate ◽  
Intestinal Protein ◽  
Critical Components ◽  
Fasted Rats

We studied protein turnover in the gastrointestinal tract of adult fasted rats, since the mechanisms responsible for protein wasting in these tissues are poorly understood. Protein mass of stomach, small intestine, and colon decreased by 14-29 and 21-49% after 1 and 5 days of fasting, respectively. The fractional rate of in vivo protein synthesis (ks) was approximately 34% lower in the stomach after 1 and 5 days of fasting due to decreased capacity for protein synthesis (Cs). In small intestine and colon, ks was not different after 1 day, but was approximately 26% lower on day 5, mainly because of a reduction in Cs. Thus protein wasting in the stomach is primarily mediated by decreased protein synthesis but not in small intestine and colon during short-term fasting. To determine which proteolytic systems may be activated in the gut, we measured mRNA levels for critical components of the lysosomal (cathepsins B and D), Ca(2+)-activated (m-calpain), and ubiquitin-dependent (ubiquitin, 14-kDa ubiquitin-conjugating enzyme E2, and C8, and C9 proteasome subunits) proteolytic pathways. mRNA levels for most of these components increased during fasting, suggesting that a coordinated activation of multiple proteolytic systems contributed to intestinal protein wasting.

Effects of the oral administration of the products derived from milk fermentation by kefir microflora on immune stimulation

2006 ◽  
Vol 73 (4) ◽  
pp. 472-479 ◽  
Author(s):  
Gabriel Vinderola ◽  
Gabriela Perdigón ◽  
Jairo Duarte ◽  
Edward Farnworth ◽  
Chantal Matar
Keyword(s):  
Small Intestine ◽  
Blood Serum ◽  
Lamina Propria ◽  
Large Intestine ◽  
Milk Fermentation ◽  
Gut Mucosa ◽  
Iga Production ◽  
Fermented Dairy ◽  
Small And Large Intestine

Nutritional status has a major impact on the immune system. Probiotic effects ascribed to fermented dairy products arise not only from whole microorganisms but also from metabolites (peptides, exopolysaccharides) produced during the fermentation. We recently demonstrated the immunomodulating capacity of kefir in a murine model. We now aimed at studying the immunomodulating capacity in vivo of the products derived from milk fermentation by kefir microflora (PMFKM) on the gut. BALB/c mice received the PMFKM for 2, 5 or 7 consecutive days. IgA+ and IgG+ cells were determined on histological slices of the small and large intestine. IL-4, IL-6, IL-10, IL-12, IFNγ and TNFα were determined in the gut, intestinal fluid and blood serum. IL-6 was also determined in the supernatant of a primary culture of small intestine epithelial cells challenged with PMFKM. PMFKM up-regulated IL-6 secretion, necessary for B-cell terminal differentiation to IgA secreting cells in the gut lamina propria. There was an increase in the number of IgA+ cells in the small and large intestine. The increase in the number of IgA+ cells was accompanied by an increase in the number of IL-4+, IL-10+ and IL-6+ cells in the small intestine. Effects of PMFKM in the large intestine were less widely apparent than the ones observed at the small intestine lamina propria. All cytokines that increased in the small intestine lamina propria, also did so in blood serum, reflecting here the immunostimulation achieved in the gut mucosa. We observed that the PMFKM induced a mucosal response and it was able to up and down regulate it for protective immunity, maintaining the intestinal homeostasis, enhancing the IgA production at both the small and large intestine level. The opportunity exists then to manipulate the constituents of the lumen of the intestine through dietary means, thereby enhancing the health status of the host.

scholarly journals Protein turnover and growth in the whole body, liver and kidney of the rat from the foetus to senility

1984 ◽  
Vol 217 (2) ◽  
pp. 507-516 ◽  
Author(s):  
D F Goldspink ◽  
F J Kelly
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Post Partum ◽  
Protein Composition ◽  
Whole Body ◽  
Turnover Rates ◽  
Tissue Mass ◽  
Age Related ◽  
Foetal Life

Changes in the growth and protein turnover (measured in vivo) of the rat liver, kidney and whole body were studied between 16 days of life in utero and 105 weeks post partum. Tissue and whole-body growth were related to changes in both cellular hyperplasia (i.e. changes in DNA) and hypertrophy (protein/DNA values) and to the protein composition within the enlarging tissue mass. The suitability of using a single large dose of phenylalanine for measuring the rates of protein synthesis during both pre- and post-natal life was established. The declining growth rates in the whole animal and the two visceral tissues were then explained by developmental changes in the fractional rates of protein synthesis and breakdown, turnover rates being age-for-age higher in the liver than in the kidney, which in turn were higher than those measured in the whole animal. The declining fractional rates of synthesis in both tissues and the whole body with increasing age were related to changes in the tissues' ribosomal capacity and activity. The fall in the hepatic rate between 18 and 20 days of foetal life (from 134 to 98% per day) corresponded to a decrease in both the ribosomal capacity and the rate of synthesis per ribosome. No significant changes in any of these parameters were, however, found in the liver between weaning (3 weeks) and senility (105 weeks). In contrast, the fractional synthetic (and degradative) rates progressively declined in the kidney (from 95 to 24% per day) and whole body (from 70 to 11% per day) throughout both pre- and post-natal life, mainly as a consequence of a progressive decline in the ribosomal capacity, but with some fall in the ribosomal activity also during foetal life. The age-related contributions of these visceral tissues to the total amount of protein synthesized per day by the whole animal were determined. The renal contribution remained fairly constant at 1.6-2.9%, whereas the hepatic contribution declined from 56 to 11%, with increasing age. Approximate-steady-state conditions were reached at, and between, 44 and 105 weeks post partum, the half-life values of mixed whole-body, kidney and liver proteins being 6.4, 3.0 and 1.5 days, respectively, at 105 weeks.

scholarly journals Tissue and whole-body protein synthesis in immature Zucker rats and their relationship to protein deposition

1982 ◽  
Vol 204 (2) ◽  
pp. 393-398 ◽  
Author(s):  
P J Reeds ◽  
P Haggarty ◽  
K W J Wahle ◽  
J M Fletcher
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Post Partum ◽  
The Body ◽  
Whole Body ◽  
Zucker Rats ◽  
Body Protein ◽  
Protein Deposition ◽  
Fractional Rate ◽  
Obese Rats

The rates of protein synthesis in skeletal muscle, intestine, liver and in the whole body of immature (18 and 25 days old) lean and obese male Zucker rats were measured. In addition, the rate of deposition of whole-body and skeletal-muscle protein over the period 16-27 days post partum was measured by comparative slaughter and analysis of the composition of the body. At 16 days post partum, lean and obese rats had similar body protein contents, but thereafter the rate of protein deposition in the body and skeletal-muscle mass was decreased in the obese rats. The decrease was particularly marked before 21 days of age, and between 23 and 27 days post partum the fractional rate of protein deposition was the same in lean and obese rats. Of the tissues that were studied, only skeletal muscle had a lower fractional rate of protein synthesis in the obese rats. At 18 days post partum, the decrease in the absolute rate of protein synthesis in skeletal muscle accounted for at least 80% of the decline in protein synthesis in the whole body. After weaning, phenotypic differences in protein synthesis was less marked than at 18 days of age, and skeletal muscle accounted for only 50% of the difference in body protein synthesis between phenotypes. The possibility that a change in the function of the adrenal cortex contributes to differences in protein metabolism between lean and obese Zucker rats is discussed.

scholarly journals The diurnal response of muscle and liver protein synthesis in vivo in meal-fed rats

1973 ◽  
Vol 136 (4) ◽  
pp. 935-945 ◽  
Author(s):  
P. J. Garlick ◽  
D. J. Millward ◽  
W. P. T. James
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Rat Tissues ◽  
Liver Protein ◽  
Protein Mass ◽  
Fractional Rate

1. The rate of protein synthesis in rat tissues was measured by constant intravenous infusion of [14C]tyrosine. A modification has been developed for the method of calculating the rate of protein synthesis in individual tissues from the specific radioactivity of the free and protein-bound amino acid in tissue at the end of the infusion. This technique gives greater accuracy and allows a greater choice of labelled amino acids. The specific radioactivity of free tyrosine in plasma was used to calculate the plasma tyrosine flux, an index of the rate of protein synthesis in the whole body. 2. Young male Wistar rats were allowed access to food for only 4h in every 24h. The tyrosine flux and the rate of protein synthesis in liver and muscle at different periods of time after a single feed were estimated. 3. The tyrosine flux did not alter after feeding nor even after starvation for 48h. 4. The average fractional rate of protein synthesis in muscle was 7.2%/day, i.e. the proportion of the protein mass which is replaced each day. The rate rose after eating and declined during starvation for 48h. In addition the rate of muscle protein synthesis correlated with the growth rate of the rat. 5. In liver the average fractional rate of protein synthesis was 50%/day. There was no change in the rate after eating nor after starvation for 48h. In contrast with muscle this suggests that the changes in protein mass were accompanied by changes in the rate of protein breakdown rather than synthesis.

scholarly journals Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects

2021 ◽  
pp. 1-9
Author(s):  
Jorn Trommelen ◽  
Andrew M. Holwerda ◽  
Philippe J. M. Pinckaers ◽  
Luc J. C. van Loon
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Stable Isotope ◽  
Dietary Protein ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Human Subjects ◽  
Whole Body ◽  
Body Protein

All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.

Measurement of protein turnover in the small intestine of lambs. 2. Effects of feed intake

1997 ◽  
Vol 128 (2) ◽  
pp. 233-246 ◽  
Author(s):  
S. A. NEUTZE ◽  
J. M. GOODEN ◽  
V. H. ODDY
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Small Intestine ◽  
Experimental Model ◽  
Feed Intake ◽  
Protein Turnover ◽  
Jugular Vein ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Body Protein

This study used an experimental model, described in a companion paper, to examine the effects of feed intake on protein turnover in the small intestine of lambs. Ten male castrate lambs (∼ 10 months old) were offered, via continuous feeders, either 400 (n = 5) or 1200 (n = 5) g/day lucerne chaff, and mean experimental liveweights were 28 and 33 kg respectively. All lambs were prepared with catheters in the cranial mesenteric vein (CMV), femoral artery (FA), jugular vein and abomasum, and a blood flow probe around the CMV. Cr-EDTA (0·139 mg Cr/ml, ∼ 0·2 ml/min) was infused abomasally for 24 h and L-[2,6-3H]phenylalanine (Phe) (420±9·35 μCi into the abomasum) and L-[U-14C]phenylalanine (49·6±3·59 μCi into the jugular vein) were also infused during the last 8 h. Blood from the CMV and FA was sampled during the isotope infusions. At the end of infusions, lambs were killed and tissue (n = 4) and digesta (n = 2) samples removed from the small intestine (SI) of each animal. Transfers of labelled and unlabelled Phe were measured between SI tissue, its lumen and blood, enabling both fractional and absolute rates of protein synthesis and gain to be estimated.Total SI mass increased significantly with feed intake (P < 0·05), although not on a liveweight basis. Fractional rates of protein gain in the SI tended to increase (P = 0·12) with feed intake; these rates were −16·2 (±13·7) and 23·3 (±15·2) % per day in lambs offered 400 and 1200 g/day respectively. Mean protein synthesis and fractional synthesis rates (FSR), calculated from the mean retention of 14C and 3H in SI tissue, were both positively affected by feed intake (0·01 < P < 0·05). The choice of free Phe pool for estimating precursor specific radioactivity (SRA) for protein synthesis had a major effect on FSR. Assuming that tissue free Phe SRA represented precursor SRA, mean FSR were 81 (±15) and 145 (±24) % per day in lambs offered 400 and 1200 g/day respectively. Corresponding estimates for free Phe SRA in the FA and CMV were 28 (±2·9) and 42 (±3·5) % per day on 400 g/day, and 61 (±2·9) and 94 (±6·0) on 1200 g/day. The correct value for protein synthesis was therefore in doubt, although indirect evidence suggested that blood SRA (either FA or CMV) may be closest to true precursor SRA. This evidence included (i) comparison with flooding dose estimates of FSR, (ii) comparison of 3H[ratio ]14C Phe SRA in free Phe pools with this ratio in SI protein, and (iii) the proportion of SI energy use associated with protein synthesis.Using the experimental model, the proportion of small intestinal protein synthesis exported was estimated as 0·13–0·27 (depending on the choice of precursor) and was unaffected by feed intake. The contribution of the small intestine to whole body protein synthesis tended to be higher in lambs offered 1200 g/day (0·21) than in those offered 400 g/day (0·13). The data obtained in this study suggested a role for the small intestine in modulating amino acid supply with changes in feed intake. At high intake (1200 g/day), the small intestine increases in mass and CMV uptake of amino acids is less than absorption from the lumen, while at low intake (400 g/day), this organ loses mass and CMV uptake of amino acids exceeds that absorbed. The implications of these findings are discussed.

scholarly journals Comparison of different techniques for estimating rates of protein synthesis in vivo in healthy and bacteraemic rats

1985 ◽  
Vol 226 (1) ◽  
pp. 37-42 ◽  
Author(s):  
J J Pomposelli ◽  
J D Palombo ◽  
K J Hamawy ◽  
B R Bistrian ◽  
G L Blackburn ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Rectus Muscle ◽  
Stochastic Modelling ◽  
Whole Body ◽  
Constant Infusion ◽  
Second Phase ◽  
Sprague Dawley ◽  
Body Protein ◽  
To Receive

Previous studies have reported that use of a flooding dose of radiolabelled amino acid is a more precise technique than the constant infusion of tracer quantities for determining rates of protein synthesis in rapidly turning-over tissues in the rat. However, there has been little direct investigation comparing different methods under comparable conditions. Initially, 12 healthy male Sprague-Dawley rats, weighing approx. 100 g, were randomized to receive either a bolus intravenous injection of 100 mumol of L-leucine (containing 30 microCi of [1-14C]leucine)/100 g body wt., or a continuous 2 h tracer infusion of [14C]leucine. In the second phase of the experiment, 12 additional rats were intravenously injected with 1 × 10(8) colony-forming units of Pseudomonas aeruginosa and 16 h later randomized to receive one of two infusions described above. Total protein synthesis as well as fractional synthesis rates were determined in liver, rectus muscle and whole body. Synthesis rates measured in liver, muscle and whole body were significantly higher in bacteraemic rats than in healthy rats. The flooding-dose methodology gave significantly higher estimates of protein synthesis in the liver, skeletal muscle and whole body than did the continuous-infusion method using direct measurement of the acid-soluble fraction from the respective tissue. Indirect estimates of whole-body protein synthesis based on plasma enrichments and stochastic modelling gave the lowest values.

Chronic effects of β2 agonists on body composition and protein synthesis in the rat

1984 ◽  
Vol 4 (1) ◽  
pp. 83-91 ◽  
Author(s):  
P. W. Emery ◽  
N. J. Rothwell ◽  
M. J. Stock ◽  
P. D. Winter
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Binding Capacity ◽  
Body Weight Gain ◽  
Muscle Protein Synthesis ◽  
Body Protein ◽  
Fractional Rate ◽  
Brown Adipose ◽  
Β2 Agonists

Chronic treatment of rats with the β2-adrenergic agonists clenbuterol and fenoterol over 16–19 d raised energy intake, expenditure, and body weight gain but did not affect fat or energy deposition, and body protein gain was increased by 50 and 18%, respectively. Both drugs increased the protein content and mitochondrial GDP-binding capacity of brown adipose tissue. Clenbuterol did not affect plasma insulin, growth hormone, or triiodothyronine levels, although insulin levels were reduced by fenoterol. Both drugs caused hypertrophy of skeletal muscle (gastrocnemius), and muscle protein synthesis in vivo (fractional rate) was elevated by 34 and 26% in clenbuterol and fenoteroltreated rats, respectively.

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