Analysis of energy expenditure in diet-induced obese rats

Abstract

Development of obesity in animals is affected by energy intake, dietary composition, and metabolism. Useful models for studying this metabolic problem are Sprague-Dawley rats fed low-fat (LF) or high-fat (HF) diets beginning at 28 days of age. Through experimental design, their dietary intakes of energy, protein, vitamins, and minerals per kg body weight (BW) do not differ in order to eliminate confounding factors in data interpretation. The 24-h energy expenditure of rats is measured using indirect calorimetry. A regression model is constructed to accurately predict BW gain based on diet, initial BW gain, and the principal component scores of respiratory quotient and heat production. Time-course data on metabolism (including energy expenditure) are analyzed using a mixed effect model that fits both fixed and random effects. Cluster analysis is employed to classify rats as normal-weight or obese. HF-fed rats are heavier than LF-fed rats, but rates of their heat production per kg non-fat mass do not differ. We conclude that metabolic conversion of dietary lipids into body fat primarily contributes to obesity in HF-fed rats.

Dietary supplementation with glutamate precursor α-ketoglutarate attenuates lipopolysaccharide-induced liver injury in young pigs

“…c LPS + AKG group (piglets which were fed the basal diet supplemented with 1 % AKG and challenged with LPS). Normal liver cell cords, mild vacuolation of hepatocytes, limited infiltration of inflammatory leukocytes, and the normal structure of hepatocytes were observed in the LPS + AKG group ◂ (Assaad et al 2014b). At the supplemental dose, dietary AKG can enter the portal circulation and then the liver, as indicated by changes in hepatic concentrations of amino acids (Table 2).…”

Ability of dairy fat in inducing metabolic syndrome in rats

“…Its subsequent studies have demonstrated that high-fat diets cause hyperglycemia and insulin resistance (Assaad et al 2014; Pound et al 2014). Studies have also indicated that high consumption of saturated fat acids and cholesterol leads to increased blood cholesterol and LDL (Pound et al 2014) and increased risk of heart diseases.…”

The impact of a short-term high-fat diet on mitochondrial respiration, reactive oxygen species production, and dynamics in oxidative and glycolytic skeletal muscles of young rats

“…Data collection for oxygen consumption (VO 2 ), carbon dioxide production (VCO 2 ), respiratory exchange ratio (RER), and energy expenditure (kcal/day) were determined by indirect calorimetry, as previously described (Assaad et al. ).…”

“…Rats were single-housed in metabolic measurement cages (CLAMS from Oxymax instrument, Columbus Instruments, OH) for the duration of the experiment. Data collection for oxygen consumption (VO 2 ), carbon dioxide production (VCO 2 ), respiratory exchange ratio (RER), and energy expenditure (kcal/day) were determined by indirect calorimetry, as previously described (Assaad et al 2014).…”