Effects of acute and chronic level of protein supply on metabolic leucine utilization in growing and mature rats

Weijs, P.J.M.; Schreurs, V.V.A.M.; Koopmanschap, R.E.; Grooten, H. N. A.; Schoonman, A.T.; Boekholt, H.A.

doi:10.1079/bjn19930109

Cited by 10 publications

(3 citation statements)

References 18 publications

(30 reference statements)

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“…The recovery of label in breath air of 1‐ 13 C 1 ‐leucine injected lactating mink ( Mustela vison ) was significantly depressed when dietary protein concentration was decreased (Tauson et al., 2001). Weijs et al. (1993) also demonstrated that the 14 CO 2 output was higher in l [1‐ 14 C]leucine‐injected rats fed acutely or chronically with a HP diet compared with those provided with a LP diet.…”

Section: Resultsmentioning

confidence: 85%

Rate of metabolic decarboxylation of leucine as assessed by a l[1‐¹³C₁]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Swennen

Laroye

Janssens

et al. 2007

Animal Physiology Nutrition

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Research has shown that broiler chickens reared on a low-protein diet have a more efficient protein digestion. However, information on the fate of absorbed amino acids in relation to the dietary crude protein level in poultry is sparse. Therefore, this study aimed at developing a methodology for a 1-(13)C(1)-leucine breath test combined with indirect calorimetry, and to apply this technique using broiler diets known to induce differences in protein retention. From 14 days of age onwards, broiler chickens were reared on one of two isocaloric diets with substitutions between fat and protein [low-protein (LP) vs. high-protein (HP) diet: 130.4 vs. 269 g protein/kg; and 101.8 vs. 27.9 g fat/kg]. Every 4 or 5 days, three chickens per diet were placed in the respiratory cells for 48 h. The broilers were intubated with 40 mg 1-(13)C(1)-leucine/kg body weight, followed by breath sampling for 4 h at 15-min intervals and mass spectrometric analysis of the (13)C:(12)C ratio in the samples. The CO(2) level in the respiratory cell air was monitored and excreta samples were collected. The methodology to study l[1-(13)C(1)]leucine decarboxyation in chickens using a breath test combined with indirect calorimetry was accomplished. Results of the nitrogen balance test indicated that the LP broilers had an improved dietary protein retention compared with the HP animals. Moreover, LP chickens decarboxylated a significantly lower percentage of l[1-(13)C(1)]leucine, demonstrating several 'protein- or amino acid-sparing' mechanisms in animals reared on a diet with lower protein level, both at the digestive and at the postabsorptive level.

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Section: Resultsmentioning

confidence: 85%

Rate of metabolic decarboxylation of leucine as assessed by a l[1‐¹³C₁]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Swennen

Laroye

Janssens

et al. 2007

Animal Physiology Nutrition

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“…Although pregnancy is an interesting physiological phenomenon in itself, the primary objective of the present study was to check whether growth during pregnancy had comparable effects on leucine utilization as growth during development. In an earlier study with male rats, growth significantly improved leucine utilization in the fasted state as well as after feeding (Weijs et al 1993). The method used in the present study is identical to that used in the previous study, which is discussed below.…”

Section: Discussionmentioning

confidence: 69%

“…In the present study it was intended to investigate the qualitative effect of pregnancy on the efficiency of leucine utilization during fasting and feeding. For this study the simplest approach was adopted, which had been shown previously to be valuable (Weijs et al 1993). The fate of leucine was traced with [14C]leucine, and the oxidized part was measured continuously.…”

Section: On the Methodsmentioning

confidence: 99%

Meal feeding and leucine utilization in pregnant rats

Weijs¹,

Schreurs²,

Grooten³

1995

Br J Nutr

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During pregnancy a higher amino acid requirement may be expected, but the increase in food intake does not match the increased growth rate during pregmmcy. It is hypothesizes that amino acid ulilization can be increased during both fasting and feeding in order to pccoullt for the increased requirement. Therefore mature female rats (20 weeks old) were investigated before and at day 18 of pregnancy. Rats were fed on a high-protein (HP) diet (210 g casein/kg diet) for 3 weeks and fasted overnight. Rats were then subjected to an 8 h constant infusion of ~-[l-'~C]leucine with continuous measurement of expired "CO, (as a percentage of the infused dose). After 3 h infusion a 5 g HP or low-protein (LP; 75 g casein/kg diet) meal was offered for 30 min. Pregnant rats had a significantly lower percentage leucine oxidation in the fasted state (12.5 (SE 0.7) Y. 159 (SE 1-1)%; P c 0.05), which suggests improved reutilization of leucine. Meal ingestion resulted in a fast increase in "C02 expiration. After the LP meal the level of I4CO2 expiration decreesed again pfter the acute response ( U . 5 h), but this was not the case after the HP meal. After the HP meal (average 1.5-5 h), no difference was observed between pregnant and nonpregnant status (36-8 (SE 1.6) Y. 350 (SE 2.3%). After the L P meal (average 1-54 h), however, the percentage leucine oxidation tended to be lower in pregnant rats but this difference did not reach statistical significance (19.7 (SE 1.1) Y. 258 (SE 2-8) %). In conclusion, pregnancy improved leucine utilization in the fasted state, and tended to improve it after marginal protein feeding.

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Measurements of substrate oxidation using 13CO2-breath testing reveals shifts in fuel mix during starvation

McCue

Pollock

2013

J Comp Physiol B

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Most fasting animals are believed to sequentially switch from predominantly utilizing one metabolic substrate to another from carbohydrates, to lipids, then to proteins. The timing of these physiological transitions has been estimated using measures of substrate oxidation including changes in respiratory exchange ratios, blood metabolites, nitrogen excretion, or enzyme activities in tissues. Here, we demonstrate how (13)CO2-breath testing can be used to partition among the oxidation of distinct nutrient pools in the body (i.e., carbohydrates, lipids, and proteins) that have become artificially enriched in (13)C. Seventy-two Swiss Webster mice were raised to adulthood on diets supplemented with (13)C-1-L-leucine, (13)C-1-palmitic acid, (13)C-1-D-glucose, or no tracer. Mice were then fasted for 72 h during which [Formula: see text], [Formula: see text], δ(13)C of exhaled CO2, body temperature, body mass, and blood metabolites (i.e., glucose, ketone bodies, and triacylglycerols) were measured. The fasting mice exhibited reductions in body mass (29 %), body temperature (3.3 °C), minimum observed metabolic rates (24 %), and respiratory exchange ratio (0.18), as well as significant changes in blood metabolites; but these responses were not particularly indicative of changes in oxidative fuel mixture. Measurements of endogenous nutrient oxidation by way of (13)CO2-breath testing revealed a decrease in the rate of oxidation of carbohydrates from 61 to 10 % of the total energy expenditure during the first 6 h without food. This response was mirrored by a coincidental increase in rate of endogenous lipid oxidation from 18 to 64 %. A transient peak in carbohydrate oxidation occurred between 8 and 14 h, presumably during increased glycogen mobilization. A well-defined period of protein sparing between 8 and 12 h was observed where endogenous protein oxidation accounted for as little as 8 % of the total energy expenditure. Thereafter, protein oxidation continually increased accounting for as much as 24 % of the total energy expenditure by 72 h. This study demonstrates that (13)CO2-breath testing may provide a complementary approach to characterizing the timing and magnitude of sequential changes in substrate oxidation that occur during prolonged fasting and starvation.

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Effects of acute and chronic level of protein supply on metabolic leucine utilization in growing and mature rats

Cited by 10 publications

References 18 publications

Rate of metabolic decarboxylation of leucine as assessed by a l[1‐¹³C₁]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Rate of metabolic decarboxylation of leucine as assessed by a l[1‐¹³C₁]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Meal feeding and leucine utilization in pregnant rats

Measurements of substrate oxidation using 13CO2-breath testing reveals shifts in fuel mix during starvation

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Effects of acute and chronic level of protein supply on metabolic leucine utilization in growing and mature rats

Cited by 10 publications

References 18 publications

Rate of metabolic decarboxylation of leucine as assessed by a l[1‐13C1]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Rate of metabolic decarboxylation of leucine as assessed by a l[1‐13C1]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Meal feeding and leucine utilization in pregnant rats

Measurements of substrate oxidation using 13CO2-breath testing reveals shifts in fuel mix during starvation

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Product

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Rate of metabolic decarboxylation of leucine as assessed by a l[1‐¹³C₁]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Rate of metabolic decarboxylation of leucine as assessed by a l[1‐¹³C₁]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio