The Food Intake of Young Rats Held at Nearly Constant Body Weight by Restriction of the Dietary Protein

AbstractTo study, in young growing rats, the consequences of different levels of dietary protein deficiency on food intake, body weight, body composition, and energy balance and to assess the role of FGF21 in the adaptation to a low protein diet. Thirty-six weanling rats were fed diets containing 3%, 5%, 8%, 12%, 15% and 20% protein for three weeks. Body weight, food intake, energy expenditure and metabolic parameters were followed throughout this period. The very low-protein diets (3% and 5%) induced a large decrease in body weight gain and an increase in energy intake relative to body mass. No gain in fat mass was observed because energy expenditure increased in proportion to energy intake. As expected, Fgf21 expression in the liver and plasma FGF21 increased with low-protein diets, but Fgf21 expression in the hypothalamus decreased. Under low protein diets (3% and 5%), the increase in liver Fgf21 and the decrease of Fgf21 in the hypothalamus induced an increase in energy expenditure and the decrease in the satiety signal responsible for hyperphagia. Our results highlight that when dietary protein decreases below 8%, the liver detects the low protein diet and responds by activating synthesis and secretion of FGF21 in order to activate an endocrine signal that induces metabolic adaptation. The hypothalamus, in comparison, responds to protein deficiency when dietary protein decreases below 5%.

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Diminished satiation in rats exposed to elevated levels of endogenous or exogenous cholecystokinin

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2001.280.2.r331 ◽

2001 ◽

Vol 280 (2) ◽

pp. R331-R337 ◽

Cited By ~ 47

Author(s):

Mihai Covasa ◽

Jeremy K. Marcuson ◽

Robert C. Ritter

Keyword(s):

Body Weight ◽

Food Intake ◽

Body Fat ◽

Peritoneal Cavity ◽

Dietary Protein ◽

High Protein ◽

High Fat ◽

Low Fat ◽

Osmotic Minipumps ◽

Fat Composition

Rats maintained on a high-fat (HF) diet exhibit reduced sensitivity to the satiation-producing effect of exogenous CCK. Because more CCK is released in response to HF meals than low-fat (LF) meals, we hypothesized that increased circulating CCK associated with ingestion of HF diets contributes to the development of decreased CCK sensitivity. To test this hypothesis, we implanted osmotic minipumps filled with either NaCl or CCK octapeptide into the peritoneal cavity. Subsequently, we examined the effect of intraperitoneal NaCl or CCK (0.5 μg/kg) injection on 30-min food intake. CCK significantly reduced 30-min food intake less in rats implanted with CCK-releasing minipumps compared with those with NaCl-releasing minipumps. Because dietary protein is a potent releaser of endogenous CCK, we hypothesized that rats adapted to a high-protein (HP) diet might also exhibit reduced sensitivity to exogenous CCK. Therefore, in a second experiment, we examined CCK-induced reduction of food intake in rats maintained on LF and rats maintained on HF or HP. Ingestion of LF stimulates very little endogenous CCK secretion, whereas both HF and HP markedly increase plasma CCK concentrations. Both doses of CCK reduced food intake significantly less in HF and HP rats compared with LF rats. There were no differences in 24-h food intake, body weight, or body fat composition among LF-, HF-, and HP-fed rats. These results are consistent with the hypothesis that sustained elevation of CCK either by infusion of exogenous CCK or by dietary-induced elevation of plasma CCK contributes to the development of reduced sensitivity to exogenous CCK.

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Changes in the food intake and body weight of protein-malnourished rats infected with Nippostrongylus brasiliensis (Nematoda)

Parasitology ◽

10.1017/s0031182000041834 ◽

1981 ◽

Vol 82 (1) ◽

pp. 23-38 ◽

Cited By ~ 40

Author(s):

D. W. T. Crompton ◽

D. E. Walters ◽

Susan Arnold

Keyword(s):

Body Weight ◽

Food Intake ◽

Infected Group ◽

Nippostrongylus Brasiliensis ◽

Initial Weight ◽

Daily Food Intake ◽

Young Rats ◽

Daily Food ◽

Long Duration ◽

Ad Libitum

SUMMARYThe daily food intake and related changes in body weight were measured in young rats which were fed on synthetic diets containing 1% (3 experiments), 2% (4 experiments) and 20% (1 experiment) casein respectively. Some rats were infected with Nippostrongylus brasiliensis and allowed to feed ad libitum, some remained uninfected and were allowed to feed ad libitum while others, which were matched by initial weight with rats from the infected group, remained uninfected and were given only the same amount of food as that consumed during the previous 24 h by their infected partners. No significant differences were detected between the rats before the start of the infection. Thereafter, the food intake of the infected undernourished rats was usually found to be significantly lower and the loss of body weight significantly greater than those of the uninfected rats. In infection periods of relatively long duration, the pair-fed uninfected rats did not lose as much weight as their infected partners even though their food intake (1% and 2% casein) was the same. Although the food intake, and consequently the weight, of infected rats fed on the diet containing 20% casein were significantly less than in their uninfected partners, no significant differences were observed between the weights of the infected and pair-fed rats fed on this diet.

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Influence of period length of light/dark cycles on the body weight and food intake of young rats

Physiology & Behavior ◽

10.1016/0031-9384(95)00021-a ◽

1995 ◽

Vol 58 (1) ◽

pp. 9-13 ◽

Cited By ~ 11

Author(s):

J Vilaplana

Keyword(s):

Body Weight ◽

Food Intake ◽

The Body ◽

Period Length ◽

Young Rats

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Severe Protein Restriction Activates Liver Protein Catabolism and ATF4-CHOP-TRB3 Pathway to Comprensate for Amino Acid Deficiency

Current Developments in Nutrition ◽

10.1093/cdn/nzaa049_040 ◽

2020 ◽

Vol 4 (Supplement_2) ◽

pp. 647-647

Author(s):

Joanna Moro ◽

Juliane Calvez ◽

Catherine Chaumontet ◽

Patrick Even ◽

Julien Piedcoq ◽

...

Keyword(s):

Gene Expression ◽

Body Weight ◽

Amino Acid ◽

Food Intake ◽

Dietary Protein ◽

Protein Restriction ◽

Liver Protein ◽

Protein Catabolism ◽

Dietary Protein Restriction ◽

Significant Difference

Abstract Objectives Severely low-protein diets (LP) induce behavioral and metabolic changes including a decrease in body weight, an increase in relative food intake (FI) and alterations in hepatic metabolism. During such protein restriction, changes in hepatic anabolic and catabolic protein pathways could transitory participate to compensate for amino acid (AA) deficiency. In the present study, liver expression of gene involved in proteosynthesis and proteolysis pathways, were related to FI, blood AA levels and body composition in rats fed LP diet. Methods Growing rats were fed for three weeks different diets containing 3-5-8-12-15 or 20% energy of milk protein. Body weight and FI were measured daily. At the end of the experiment, tissues and biological fluids were removed for gene expression measurement and blood AA UPLC analysis. Statistical analysis was done by 1- or 2-factor ANOVA, when data were repeated. Results Despite an increase in relative food intake under P3 and P5% diets, P3, P5 and P8% diets resulted in significant growth retardation compared to other groups. Lean mass was significantly decreased in rats under P3, P5 and P8% compared to P12, P15 and P20% diets, while there was no difference in fat mass between all groups. P3, P5 and P8% diets induced a decrease in essential amino acid concentrations in portal vein, whereas there was no significant difference between groups in veina cava. Severely protein restricted P3% and P5% diets induced an increase in hepatic gene expression involved in proteolysis as calpain 2 and ubiquitin, and an activation of ATF4-CHOP-TRB3 pathway. Conclusions These results suggested that under severe protein restriction, hepatic protein catabolism became a source of plasma amino acid that could partially compensate for the AA not provided by the diet. These observations confirm that liver plays a major role in the adaptation of the body to dietary protein restriction and highlight that severe dietary protein restriction induced liver protein catabolism by inducing an activation of ATF4-CHOP-TRB3 pathway in order to provide amino acids to body tissues. Funding Sources ABIES, AlimH-INRAE.

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