Oxylet

After 12 weeks, each rat was housed in an individual metabolic cage with free access to food and water. O₂ and CO₂ analyzers were calibrated with purified gas before measurement [22 (link)]. Oxygen consumption (VO₂) and carbon dioxide production (VCO₂) were determined via indirect calorimetry (Oxylet, Panlab, Barcelona, Spain). VO₂ and VCO₂ data were recorded for 24 h at 3 min intervals using a computer-assisted data acquisition program (Chart 5.2; AD Instrument, Bella Vista, NSW, Australia). Energy expenditure (EE) was obtained according to the following formula: $$\mathrm{EE}\left(\mathrm{kcal}/\mathrm{day}/\mathrm{kg}^0.75\right)=\left(3.815\times {\mathrm{VO}}_2+1.232\times {\mathrm{VCO}}_2\right)\times 1.44.$$

Energy expenditure was measured using an indirect calorimeter (Oxylet, Panlab, Cornella, Spain). The mice were placed in individual metabolic chambers at 25 °C with free access to food and water. O₂ and CO₂ analyzers were calibrated using high-purity gases. O₂ consumption (VO₂) and CO₂ production (VCO₂) were recorded at 3 min intervals using computer-assisted data acquisition software (Chart 5.2; AD Instrument, Sydney, Australia) over a 24 h period, and the data were averaged for each mouse. Energy expenditure (EE) was calculated using the following formula [34 (link)]:

Energy expenditure was measured using an indirect calorimeter (Oxylet; Panlab, Cornella, Spain) in five randomly selected mice per group during final week. The mice were placed into individual metabolic chambers at 25 °C, with free access to food and water. Oxygen and carbon dioxide analyzers were calibrated with high-purity gas. Oxygen consumption and carbon dioxide production were recorded at 3-min intervals, using a computer-assisted data acquisition program, (Chart 5.2; AD Instrument, Sydney, Australia) over a 24-h period, and the data were averaged for each mouse. Energy expenditure (EE) was calculated according to the following formula:

The mice were individually housed in metabolic cages (Oxylet, PanLab, Spain) to measure O₂ consumption (VO₂) and CO₂ production (VCO₂). Spontaneous activities were monitored by activity sensors at the same time. The respiratory quotient (RQ = VCO₂/VO₂) was calculated using Metabolism software.

The HFD-fed and CD-fed mice (n = 5-7) were housed in individual metabolic chambers and were allowed to acclimatize for 24 h before data collection. Energy expenditure of these mice was measured using an indirect open-circuit calorimeter (Oxylet, Panlab, Barcelona, Spain). Data on O₂ consumption (VO₂; ml/min/kg^0.75) and CO₂ production (VCO₂; ml/min/kg^0.75) were collected every 30 min. Locomotor activity was measured by continuously recording spontaneous activity using extensiometric weight transducers placed below the cages, which enabled the detection of activity even without displacement. The respiratory quotient (RQ) was calculated as the ratio of VO₂ to VCO₂, and energy expenditure was determined as (3.815 + 1.232 × RQ) × VO₂ and was expressed as kcal/h/mouse [39 (link)]. The data is normalized to body weight.

Energy expenditure was measured using an indirect calorimeter (Oxylet; Panlab, Cornella, Spain). The mice were placed into individual metabolic chambers at 25 °C, with free access to food and water. O₂ and CO₂ analyzers were calibrated with high-purity gas. Oxygen consumption and carbon dioxide production were recorded at 3 min intervals, using a computer-assisted data acquisition program (Chart 5.2; AD Instrument, Sydney, Australia) over a 24-h period, and the data were averaged for each mouse. Energy expenditure (EE) was calculated according to the following formula:

An indirect open circuit calorimeter (Oxylet, Panlab) was used to monitor O₂ consumption and CO₂ production. Mice were individualized and acclimated to the metabolic chambers for 24 h, and data were collected in each cage for 3 min, every 15 min, for 24 h. Data were taken during the light and dark cycles and were adjusted by body weight.