Low protein diet changes the energetic balance and sympathetic activity in brown adipose tissue of growing rats

Abstract Objectives Low protein diet and essential amino acid deficient-diet have an impact on body weight and growth and different studies also showed an impact of lysine intake on bone metabolism. Lysine has been shown to promote the absorption of intestinal calcium and to participate in the collagen synthesis through its involvement in the reticulation process of the tropocollagen beams. The assembly of tropocollagen bundle into mature collagen fibers is essential for bone formation and remodeling (civitelli et al, 1992; Fini et al, 2001). The objective of this study was to characterize the impact of low protein diet and lysine-deficient diet on bone metabolism of growing rats. Methods Study 1: 6 group of growing rats were fed for 3 weeks different diet with different content of milk protein at levels of 3%, 5%, 8%, 12%, 15% or 20% (% total energy). Study 2: 7 group of growing rats were fed diets with different lysine content (as % of lysine requirement), for 3 weeks: 15%, 25%, 40%, 60%, 75%, 100% or 170% (% Lysine requirement). Body weight was measured daily. At the end of the experiment, the body composition was analyzed and tissues were removed for measurements of the expression of genes involved in protein and bone metabolism. Statistical analysis was done by variance analysis. Results Rats fed low protein diet (3% and 5% of milk protein), compared to control have a lower growth, with a lower body weight and naso-anal length. This weak growth was associated with a lower lean body mass, and also had an impact on bone metabolism. There was a decrease in the bone mineral density, bone mineral content and femur size, associated with a decrease of markers of bone turnover and formation. The same results on bone metabolism were observed on rats fed the 85% lysine deficient diet. Conclusions Low protein diet and lysine-deficient diet reduce growth and bone metabolism. The impact of low protein diet could be related to the lysine deficiency, which have an impact on the calcium intestinal absorption and on collagen synthesis. Funding Sources INRA, AgroParisTech. Supporting Tables, Images and/or Graphs

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Sucrose-induced obesity: effect of diet on obesity and brown adipose tissue

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1987.253.1.r158 ◽

1987 ◽

Vol 253 (1) ◽

pp. R158-R166 ◽

Cited By ~ 5

Author(s):

R. B. Kanarek ◽

J. R. Aprille ◽

E. Hirsch ◽

L. Gualtiere ◽

C. A. Brown

Keyword(s):

Adipose Tissue ◽

Weight Gain ◽

Brown Adipose Tissue ◽

Dietary Protein ◽

Feed Efficiency ◽

Protein Diet ◽

Standard Diet ◽

Metabolic Potential ◽

Interscapular Brown Adipose Tissue ◽

Brown Adipose

Adult male Sprague-Dawley rats were divided into three groups and fed diets containing either 10, 20, or 40% protein for 56 days. Half of the rats in each dietary condition were given a 32% sucrose solution plus the standard diet and water. Sucrose intake varied directly as a function of dietary protein levels. Rats fed either the 10 or 20% protein diet and sucrose had higher caloric intakes, gained more weight, were more efficient at using calories for weight gain, and had more adipose tissue than rats given the same diet without sucrose. Rats fed the 40% protein diet and sucrose did not exhibit overeating, excess weight gain, or increased feed efficiency relative to animals fed the 40% diet alone. Animals given sucrose had more interscapular brown adipose tissue (IBAT) and a greater metabolic potential for thermogenesis in IBAT as determined by GDP binding in mitochondria than rats not fed sucrose. These results demonstrate that dietary protein is important in the development of sucrose-induced obesity and that increases in IBAT mass and activity can occur concomitant with increased feed efficiency.

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