The change in the rate of muscle protein metabolism of rats from weaning to 90 days of age

Siebrits, F.K.; Barnes, Penelope M.

doi:10.1016/0300-9629(89)90353-8

Cited by 7 publications

(2 citation statements)

References 11 publications

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“…Nevertheless, the variability among experimental values is large and increases with BW. In rats, this rate decreased from 29% at 23 d of age to 5% at 330 d (Millward et al, 1975), and from 30% at 25 d to 7% at 90 d (Siebrits and Barnes, 1989). In suckling piglets, it decreased from 58% at 7 d of age to 30% at 26 d (Wray-Cahen et al, 1998).…”

Section: Discussionmentioning

confidence: 93%

Modeling homeorhetic and homeostatic controls of pig growth1

Lovatto¹,

Sauvant²

2003

Journal of Animal Science

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A dynamic mechanistic model of homeorhetic and homeostatic controls of pig growth was developed. The homeorhetic principles were based on changes in time of fractional rates of anabolism and catabolism of tissues. A minimum number of homeostatic principles integrated current data on plasma kinetics and the partitioning of nutrients between anabolism and catabolism of body tissues, and endogenous losses with integument and into the gut. The major features of the model are two levels of organization (tissue and plasma) and three body tissues (carcass proteins, visceral proteins, and body lipids). The protein tissues and plasma amino acids were subdivided into lysine, methionine and cystine, threonine, tryptophan, other essential AA, and nonessential AA compartments. Plasma glucose and fatty acids were also considered. Adenosine triphosphate and adenosine diphosphate were used to represent energy transformations, although these energy transformations were not included in the homeostatic control of pig growth. The mass variations within each of the 23 basic compartments were described with a specific deterministic, dynamic differential equation. The simulated metabolic rates of the protein and lipid tissues were similar to published data. The principal outputs from the model (protein and lipid gain, body weight, chemical body constituents, plasma parameters) showed that the proposed homeorhetic and homeostatic controls provide a mechanistic approach to modeling growth.

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Section: Discussionmentioning

confidence: 93%

Modeling homeorhetic and homeostatic controls of pig growth1

Lovatto¹,

Sauvant²

2003

Journal of Animal Science

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“…Old rats seem better suited for DIO due to a significant decline in protein anabolism compared with young animals. 55 Provision of excess energy is therefore likely to induce obesity rather than growth in old rats, especially in females due to their relatively lower growth rates. Indeed, supplying a high fat diet to 15-month-old female Wistar rats for 10 weeks produced significantly obese and hyper-leptinemic animals.…”

Section: Animal Modelsmentioning

confidence: 99%

Treatment of Obesity Using GH

Johansen

Malmlöf²

2006

Metabolic Syndrome and Related Disorders

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The obesity epidemic calls for complementary treatment possibilities in addition to lifestyle changes. One of the important regulators of lipid homeostasis is growth hormone (GH). Clinical trials have tested if GH can reduce obesity in humans. The mechanisms underlying the response to GH administration have also been investigated in animal models of human obesity. A literature search yielded 19 randomized placebo-controlled clinical studies and several animal studies investigating chronic GH treatment of obesity. Significant effects were found in some of the larger trials. One clinical trial showed significantly increased weight loss due to GH treatment, and in seven trials, a significant reduction of fat mass was found. The improvements observed were modest, but even minor improvements have been shown to be beneficial, especially if the reduction in fat mass includes visceral adipose tissue, as was reported in three of six trials. In principle, animal data support the clinical observations although the reduction of fat mass was more dramatic than observed in humans. The mechanisms resulting in lipid mobilization most likely include adipose tissue lipo-protein lipase (LPL) inhibition and antagonization of the anti-lipolytic activity of insulin. By feeding a restricted amount of a high fat diet to GH exposed rats hyper-insulinemia was avoided, loss of body fat was accelerated and metabolic markers were improved. Provision of a diet suitable for the metabolic conditions during GH treatment shows promise for improving metabolic control and can perhaps increase the efficacy and/or widen the therapeutic window of GH.

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Growth equations for skeletal muscle derived from the cytonuclear ratio and growth constraining supplementary functions

Roux

1999

Anim. Sci.

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For purely hypertrophic muscle it is postulated that the growth rate in number of nuclei is proportional to the cytoplasmic mass per nucleus multiplied by a growth constraining supplementary function. Growth constraint depends on the distance from any one of the limit number of nuclei, the limit muscle mass or the limit cytoplasmic mass per nucleus. Furthermore, theory and evidence are presented for a power (allometric) relationship between total number of nuclei (n) and muscle mass (m) given by the equation n = gmh. Evidence points to two clusters of values for h, one in the vicinity of h = 2/3 and the other h = 1/2. Both may depend on a linear relationship between number of nuclei inside muscle fibre and fibre cross-sectional area. The difference between the two situations can be derived from basic assumptions on either local or systemic diffusion mediated control of the number or division of satellite cell nuclei, leading directly to values of h either equal to 2/3 or V2. For likely values of h and suitable choices of growth constraints, almost all well known growth functions in the literature are derived as potentially applicable to total number of nuclei, or muscle mass or their ratio. Muscle mass growth will show a sigmoidal form for h = 1. This explains sigmoidal growth in body mass as it is mostly dominated by muscle mass. A possible linear growth phase before maturity is explicable from the cessation of either length (h = 1) or nuclear (h = 0) growth in muscle fibres, while cytoplasmic growth continues to maturity. Furthermore, two rat examples indicate that whole body protein growth can be described by the equations derived for muscle mass growth.

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The change in the rate of muscle protein metabolism of rats from weaning to 90 days of age

Cited by 7 publications

References 11 publications

Modeling homeorhetic and homeostatic controls of pig growth1

Modeling homeorhetic and homeostatic controls of pig growth1

Treatment of Obesity Using GH

Growth equations for skeletal muscle derived from the cytonuclear ratio and growth constraining supplementary functions

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