Effect of Age on Protein Conservation during Very‐Low‐Energy Diet in Obese Sprague‐Dawley Rats

Johnson, Julia A.; Yu, Choon-Hie; Yang, Mei‐Uih; Pi‐Sunyer, F. Xavier

doi:10.1002/j.1550-8528.1998.tb00377.x

Cited by 4 publications

(2 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We also observed that the most marked decrease in tissue protein masses concerned the splanchnic organs (small intestine, liver) and cardiac muscle, while only little or no difference was observed in the skeletal muscles. A previous study in rodents has already shown that during CR, the liver and heart are more prone to protein loss than skeletal muscles [32]. As the use of AA for protein synthesis in muscles is preserved during CR on a high-protein diet [33,34,35], the moderate decrease in protein mass likely resulted from an increase in proteolysis and AA allocation to oxidation.…”

Section: Discussionmentioning

confidence: 99%

Natural Isotope Abundances of Carbon and Nitrogen in Tissue Proteins and Amino Acids as Biomarkers of the Decreased Carbohydrate Oxidation and Increased Amino Acid Oxidation Induced by Caloric Restriction under a Maintained Protein Intake in Obese Rats

et al. 2019

View full text Add to dashboard Cite

A growing body of evidence supports a role for tissue-to-diet 15N and 13C discrimination factors (Δ15N and Δ13C), as biomarkers of metabolic adaptations to nutritional stress, but the underlying mechanisms remain poorly understood. In obese rats fed ad libitum or subjected to gradual caloric restriction (CR), under a maintained protein intake, we measured Δ15N and Δ13C levels in tissue proteins and their constitutive amino acids (AA) and the expression of enzymes involved in the AA metabolism. CR was found to lower protein mass in the intestine, liver, heart and, to a lesser extent, some skeletal muscles. This was accompanied by Δ15N increases in urine and the protein of the liver and plasma, but Δ15N decreases in the proteins of the heart and the skeletal muscles, alongside Δ13C decreases in all tissue proteins. In Lys, Δ15N levels rose in the plasma, intestine, and some muscles, but fell in the heart, while in Ala, and to a lesser extent Glx and Asx, Δ13C levels fell in all these tissues. In the liver, CR was associated with an increase in the expression of genes involved in AA oxidation. During CR, the parallel rises of Δ15N in urine, liver, and plasma proteins reflected an increased AA catabolism occurring at the level of the liver metabolic branch point, while Δ15N decreases in cardiac and skeletal muscle proteins indicated increased protein and AA catabolism in these tissues. Thus, an increased protein and AA catabolism results in opposite Δ15N effects in splanchnic and muscular tissues. In addition, the Δ13C decrease in all tissue proteins, reflects a reduction in carbohydrate (CHO) oxidation and routing towards non-indispensable AA, to achieve fuel economy.

show abstract

Section: Discussionmentioning

confidence: 99%

Natural Isotope Abundances of Carbon and Nitrogen in Tissue Proteins and Amino Acids as Biomarkers of the Decreased Carbohydrate Oxidation and Increased Amino Acid Oxidation Induced by Caloric Restriction under a Maintained Protein Intake in Obese Rats

et al. 2019

View full text Add to dashboard Cite

show abstract

“…However, one of the most important goals of restricted diets for obese individuals is the maintenance of their body protein mass [12], because skeletal muscle is a key contributor to the adjustments in energy and amino acid metabolism during long periods of reduced dietary energy consumption [13].…”

Section: Introductionmentioning

confidence: 99%

Responses to Dietary Macronutrient Distribution of Overweight Rats under Restricted Feeding

et al. 2002

View full text Add to dashboard Cite

Changes in protein and amino acid balance after energy-restricted feeding have scarcely been studied, although it has been suggested that protein utilization may depend on the macronutrient composition of the restricted diet. The aim of this study is to investigate the influence of dietary fat quality and content, during an energy-restricted regime, on body composition and protein metabolism. Therefore, diet-induced overweight rats were divided into three dietary groups: one group was fed on a control diet ad libitum (control) and the other two groups were fed energy-restricted diets (about 60% of control group), which provided a standard amount (20%) of fat (SFR), based on olive oil, or a high amount (60%) of saturated fat (HFR), based on coconut oil. Measurements of body weight, body composition, serum biochemical parameters and the assessment of the hepatic and muscular protein response were performed. Similar results were found comparing weight losses and serum parameters in both deprived groups, although the high-fat-restricted rats (HFR group) showed a greater reduction in the subcutaneous fat depot and of total body fat. After both energy-restricted treatments, the serum amino acid concentration was reduced while the urinary amino acid excretion increased. Muscle and liver protein metabolism was affected by energy restriction, which produced a decrease in protein synthesis capacity (RNA content) in both tissues and a higher muscle proteolysis (catepsin activity), more marked in the SFR group, while no changes were found in liver protein breakdown. Hepatic glycogen and glycogenic amino acid were also altered, reaching significant differences in the HFR group. Thus, dietary macronutrient composition during energy restriction seems to be involved in the metabolic adaptative response.

show abstract

Prolonged Decrease of Adipocyte Size after Rosiglitazone Treatment in High‐ and Low‐Fat‐Fed Rats

Johnson

Trasino

Ferrante

et al. 2007

Obesity

Self Cite

View full text Add to dashboard Cite

JOHNSON, JULIA A., STEVEN E. TRASINO, ANTHONY W. FERRANTE, JR., AND JOSEPH R. VASSELLI. Prolonged decrease of adipocyte size after rosiglitazone treatment in high-and low-fat-fed rats. Obesity. 2007;15:2653-2663. Objective: The anti-diabetic thiazolidinediones (TZDs) stimulate adipocyte differentiation and decrease mean adipocyte size. However, whether these smaller, more insulinsensitive adipocytes maintain their size after TZD therapy is discontinued has not been studied. Research Methods and Procedures:Adult female SpragueDawley rats were fed a low-fat (10% fat) diet or, to elevate body weight (BW), a high-fat (HF) diet (45% fat) for 6 weeks. Rats were initially randomized to groups (n ϭ 12) fed either low-fat or HF diets, with or without the TZD rosiglitazone (ROSI; 5 mg/kg per day), for 6 weeks. ROSI was then discontinued, and all animals were fed HF for another 6 weeks before sacrifice. Retroperitoneal (RP) adipose tissue morphology was determined from tissue collected by serial biopsies before and after 6 weeks of ROSI treatment and at sacrifice. Results: Measures of BW and adiposity did not differ among groups 6 weeks after stopping ROSI treatment. However, during treatment, ROSI in both diets significantly decreased RP adipocyte size and increased RP DNA content, and these effects continued to be observed after discontinuing treatment. ROSI administration also decreased circulating insulin, leptin, and triglycerides and increased circulating adiponectin levels; however, these effects were reversed on stopping treatment. Discussion: These results demonstrated that TZD-induced effects on adipocyte size and number were maintained after discontinuing treatment, even with consumption of an obesigenic diet. However, additional studies are needed to determine whether TZD-treated animals eventually achieve an adipocyte size similar to that of untreated animals at the expense of a higher BW.

show abstract

Effect of Age on Protein Conservation during Very‐Low‐Energy Diet in Obese Sprague‐Dawley Rats

Cited by 4 publications

References 33 publications

Natural Isotope Abundances of Carbon and Nitrogen in Tissue Proteins and Amino Acids as Biomarkers of the Decreased Carbohydrate Oxidation and Increased Amino Acid Oxidation Induced by Caloric Restriction under a Maintained Protein Intake in Obese Rats

Natural Isotope Abundances of Carbon and Nitrogen in Tissue Proteins and Amino Acids as Biomarkers of the Decreased Carbohydrate Oxidation and Increased Amino Acid Oxidation Induced by Caloric Restriction under a Maintained Protein Intake in Obese Rats

Responses to Dietary Macronutrient Distribution of Overweight Rats under Restricted Feeding

Prolonged Decrease of Adipocyte Size after Rosiglitazone Treatment in High‐ and Low‐Fat‐Fed Rats

Contact Info

Product

Resources

About