Proximate causes for diet-induced obesity in laboratory mice: a case study

Area of Science:

• Metabolic research
• Obesity research
• Animal models

Background:

• Diet-induced obesity (DIO) mechanisms vary between mouse strains.
• AKR/J mice are susceptible to DIO, while SWR/J mice are resistant.
• Proximate mechanisms behind DIO resistance are not fully understood.

Purpose of the Study:

• Investigate energy balance in AKR/J and SWR/J mice.
• Identify metabolic adaptations conferring resistance to DIO.
• Understand strain-specific responses to high-fat diets (HFD).

Main Methods:

• Assessed body mass, composition, metabolizable energy, and energy expenditure (EE) in AKR/J and SWR/J mice on a control diet.
• Investigated immediate metabolic responses to a 3-day HFD.
• Utilized detailed protocols for energy balance assessment in mouse models.

Main Results:

• SWR/J mice exhibited higher EE and fat oxidation than AKR/J mice on a control diet.
• Both strains increased energy intake and EE in response to HFD.
• Catabolic adaptations to HFD opposed positive energy balance, independent of physical activity.

Conclusions:

• Metabolic phenotyping revealed that metabolizable energy and daily energy expenditure (DEE) contribute to DIO.
• Assessing both energy intake and expenditure is essential for identifying DIO mechanisms.
• Guidelines for energy balance assessment are applicable but require adjustments for body composition differences.