Influence of Diet Composition on Serum Triiodothyronine (T3) Concentration, Hepatic Mitochondrial Metabolism and Shuttle System Activity in Rats

Tyzbir, Robert S.; Kunin, Arthur S.; Sims, Nathaniel M.; Danforth, Elliot

doi:10.1093/jn/111.2.252

Cited by 49 publications

(9 citation statements)

References 31 publications

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“…The decreased energetic efficiency observed in growing rats and pigs fed low protein diets is often associated with a marked rise in T 3 concentration , ROTHWELL et al" 1983, GURR et al, 1980, which is frequently interpreted as an adaptive diet-induced thermogenesis. Some energy dissipating Systems such as the hepatic mitochondrial ct-GP Shuttle (TYZBIR et al, 1981, SAWAYA and LUNN, 1985, KEAGY et al, 1987, as well as the thermogenic activity of brown adipose tissue (ROTWELL et al, 1983) are sensitive to the thyroid hormone Status. Because dietary proteins with a lower biological value induce an increase in T 4 levels, we propose that similar to protein deficient diets the excess of dietary energy, which can not be deposited as protein, could also be dissipated as heat through increased thermogenesis.…”

Section: Discussionmentioning

confidence: 99%

Effects of dietary protein quality on energy metabolism and thyroid hormone Status in growing pigs

et al. 2000

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SummaryTo estimate long-term effects of dietary protein quality on energy metabolism and thyroid hormone Status in growing pigs two experiments were carried out, each using 6 growing German Landrace barrows (40 to 90 kg body weight (BW)) per treatment group, which were fed semisynthetic isoenergetic diets based on either casein or soy protein isolate at 1875 kJ ME/(kg BW 062 x d). Casein was tested with (CAS+) amino acid (AA) supplementation (methionine + cystine, threonine, tryptophane) and soy protein isolate was tested without (SPI-) AA supplementation at the recommended protein supply of 100% (normal protein level (NP)) and at a protein supply of 50% of NP. During experiments pigs were housed individually in metabolic cages at 23 ± 1°C. At both protein supply levels, SP1-in comparison to CAS+ caused a lower protein energy retention (PER), which was compensated mainly by an increased fat energy retention (FER). The reduction of the protein supply to 50% caused a lower PER by 30 to 50% in both dietary qualities, which was compensated by a significantly higher FER. However, the heat production (HP) was neither affected by the protein quality nor by the quantity, and resulted in nearly similar values of 60% of ME intake. The thyroid hormone concentrations were dependent primarily on the amount of protein supply, and after decrease of supply to 50% secondly on the dietary protein quality. The increased thyroid hormone concentrations at the 50% protein level were in euthyroid ränge of pigs and obviously not associated with HP.Key Words: protein quality, soy protein isolate, casein, thyroid hormones, energetic efficiency, pigs Zusammenfassung Titel der Arbeit: Effekte der Nahrungsproteinqualität auf den Energieumsatz und den Schilddrüscnhor-monstatus wachsender Schweine Um Langzeiteffekte von Nahrungsproteinqualitäten auf den Energieumsatz und den Schilddrüsenhormonstarus wachsender Schweine zu bestimmen, wurden 2 Versuche mit jeweils 6 wachsenden Borgen der Deutschen Landrasse (40 bis 90 kg LM) je Versuchsgruppe durchgeführt. Die Tiere wurden mit semisynthetischen, isoenergetischen Diäten (1875 kJ ME/(kg BW 1 " x d)) gefüttert, die Casein oder Sojaproteinisolat als alleinige Proteinquelle enthielten. Casein (CAS+) wurde mit Aminosäurenergänzung (Methionin + Cystein, Threonin, Tryptophan) und Sojaproteinisolat (SPI-) ohne AA-Ergänzung auf einer 100 %igen Proteinversorgungsstufe (normal protein level, NP) und einer 50 %igen (low protein level (LP)) getestet. Während der Versuche wurden die Tiere einzeln in Stoffwechselkäfigen bei 23 ± 1°C gehalten. Auf beiden Proteinversorgungsstufen führte die Fütterung von SPI-im Vergleich zu CAS+ zu einer signifikant niedrigeren Proteinenergieretention (PER), die überwiegend durch eine höhere Fettenergieretention (FER) kompensiert wurde. Die Senkung der Proteinversorgung auf 50 % hatte für beide Proteinqualitäten eine 30 bis 50 % niedrigere PER zur Folge, welches durch eine höhere FER kompensiert wurde. Die Wärmeproduktion (WP) wurde weder durch die Proteinqualität noch durch die...

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Section: Discussionmentioning

confidence: 99%

Effects of dietary protein quality on energy metabolism and thyroid hormone Status in growing pigs

et al. 2000

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“…In particular, a large increase in the activity of brown adipose tissue has been described (4)(5)(6). In keeping with this picture, one of the hormones most directly involved in energy dissipation, norepinephrine (NE), is elevated in rats fed low-protein diets (7,8).…”

Section: Introductionmentioning

confidence: 93%

“…This could be reasonable evidence that hypoalbuminemia is also promoted by increased ß-2 selective agonist activity during consumption of low-protein diets. In addition, to have a better picture of the metabolic changes produced by the present drug treatment, two hormones, T 3 and insulin, known to be associated with plasma albumin levels in rats fed a low-protein diet, were measured (1,4,6,15).…”

Section: Introductionmentioning

confidence: 99%

Increase in skeletal muscle protein content by the ß-2 selective adrenergic agonist clenbuterol exacerbates hypoalbuminemia in rats fed a low-protein diet

Sawaya

Lunn

1998

Braz J Med Biol Res

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This investigation examined how the nutritional status of rats fed a low-protein diet was affected when the animals were treated with the ß-2 selective agonist clenbuterol (CL). Males (4 weeks old) from an inbred, specific-pathogen-free strain of hooded rats maintained at the Dunn Nutritional Laboratory were used in the experiments (N = 6 rats per group). CL treatment (Ventipulmin, Boehringer-Ingelheim Ltd., 3.2 mg/kg diet for 2 weeks) caused an exacerbation of the symptoms associated with protein deficiency in rats. Plasma albumin concentrations, already low in rats fed a low-protein diet (group A), were further reduced in CL rats (A = 25.05 ± 0.31 vs CL = 23.64 ± 0.30 g/l, P<0.05). Total liver protein decreased below the level seen in either pair-fed animals (group P) or animals with free access to the low-protein diet (A = 736.56 ± 26 vs CL = 535.41 ± 54 mg, P<0.05), whereas gastrocnemius muscle protein was higher than the values normally described for control (C) animals (C = 210.88 ± 3.2 vs CL = 227.14 ± 1.7 mg/g, P<0.05). Clenbuterol-treated rats also showed a reduction in growth when compared to P rats (P = 3.2 ± 1.1 vs CL = -10.2 ± 1.9 g, P<0.05). This was associated with a marked decrease in fat stores (P = 5.35 ± 0.81 vs CL = 2.02 ± 0.16 g, P<0.05). Brown adipose tissue (BAT) cytochrome oxidase activity, although slightly lower than in P rats (P = 469.96 ± 16.20 vs CL = 414.48 ± 11.32 U/BAT x kg body weight, P<0.05), was still much higher than in control rats (C = 159.55 ± 11.54 vs CL = 414.48 ± 11.32 U/BAT x kg body weight, P<0.05). The present findings support the hypothesis that an increased muscle protein content due to clenbuterol stimulation worsened amino acid availability to the liver and further reduced albumin synthesis causing exacerbation of hypoalbuminemia in rats fed a low-protein diet. Correspondence

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“…These changes include increased food consumption accompanied by reduced body weight gain (i.e., lower feed efficiency), enhanced oxygen consumption following adrenergic stimulation (21,25), greater quantities of highly oxidative interscapular brown adipose tissue (BAT) (24,25), and increased biochemical activity of BAT (26). A variety of enzymatic and hormonal changes, including increased norepinephrine turnover rates, are also evident (17,25,27). The decreased metabolic efficiency observed among animals fed low-protein diets may involve any or all of these mechanisms (25,28).…”

Section: Introductionmentioning

confidence: 99%

“…Oxygen consumption was measured after 28 days of dietary treatment by closed-circuit respirometry(27). There is negative, linear trend (p < 0.03) with increasing protein intake.…”

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confidence: 99%

Thermogenesis, low‐protein diets, and decreased development of AFB1‐induced preneoplastic foci in rat liver

Horio

et al. 1991

Nutrition and Cancer

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The development of hepatocellular, putatively preneoplastic, gamma-glutamyl transpeptidase positive (GGT+) foci and tumors induced by aflatoxin B1 (AFB1) has been shown to be reduced in male F344 rats fed a diet containing 6% protein (as casein). This reduction occurs despite increased energy intake, when compared with animals fed a diet containing 22% protein. Among its many effects, low protein intake is known to increase the proportion of energy intake expended in the form of heat (thermogenesis); thus, this investigation examined the association between the development of GGT+ foci and alterations in indices of thermogenesis induced by feeding varying levels of dietary protein. Five days following the completion of AFB1 dosing, animals were assigned to groups fed 4%, 8%, 12%, 16%, or 22% dietary protein for 6 weeks. Foci development (% liver volume occupied) was markedly reduced in animals fed the low-protein diet (4%, 8%), yet calorie consumption per 100 g body wt was greater. A modest negative linear trend was observed in oxygen consumption with increasing levels of dietary protein intake. Urinary norepinephrine levels were elevated in the groups fed 4% and 8% protein; urinary dopamine and norepinephrine turnover rates in brown adipose tissue were highest in animals fed 4% protein. These results suggest that GGT+ foci development occurs when a "critical level" (approx 12%) of dietary protein intake is reached. Inhibition of foci development at lower levels of protein intake is associated with several indicators of increased thermogenesis.

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Influence of Diet Composition on Serum Triiodothyronine (T3) Concentration, Hepatic Mitochondrial Metabolism and Shuttle System Activity in Rats

Cited by 49 publications

References 31 publications

Effects of dietary protein quality on energy metabolism and thyroid hormone Status in growing pigs

Effects of dietary protein quality on energy metabolism and thyroid hormone Status in growing pigs

Increase in skeletal muscle protein content by the ß-2 selective adrenergic agonist clenbuterol exacerbates hypoalbuminemia in rats fed a low-protein diet

Thermogenesis, low‐protein diets, and decreased development of AFB1‐induced preneoplastic foci in rat liver

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