Refinement Measure Using NMR for Subcutaneous Fat Mass Determination in Rats

Area of Science:

• Physiology
• Biomedical Engineering
• Animal Science

Background:

• White adipose tissue (WAT) is crucial for metabolic health and is categorized into subcutaneous and visceral depots.
• Nuclear magnetic resonance (NMR) is a technique for measuring adipose tissue, but in-vivo application can be stressful for research animals like rats.
• Validating alternative methods for WAT assessment is essential for improving animal welfare and research efficiency.

Purpose of the Study:

• To evaluate the validity of using NMR on sacrificed rats to determine subcutaneous white adipose tissue (WAT) weight.
• To compare WAT measurements obtained via NMR in vivo and ex vivo.
• To assess the reliability of NMR for quantifying WAT across different dietary conditions and adiposity levels.

Main Methods:

• Rats were subjected to in-vivo NMR measurements for WAT assessment.
• Following sacrifice, carcass WAT was measured using ex-vivo NMR.
• Adipose tissue depots (subcutaneous and visceral WAT) were dissected and weighed post-sacrifice for comparison.
• Rats were fed either a standard diet or diets including a cafeteria diet to induce varying adiposity.

Main Results:

• In rats fed a standard diet, in-vivo and ex-vivo NMR measurements of WAT showed similar results.
• Across three dietary groups with differing adiposity levels, the percentage of subcutaneous and visceral WAT measured by ex-vivo NMR and dissection remained consistent.
• NMR measurements of carcass WAT (predominantly subcutaneous) correlated well with dissected visceral WAT, indicating a reliable assessment of WAT distribution.

Conclusions:

• Determining subcutaneous white adipose tissue (WAT) weight via NMR in sacrificed rats is a valid and reliable approach.
• This ex-vivo NMR method provides a non-invasive and less stressful alternative to in-vivo measurements for WAT assessment in research settings.
• The findings support the use of NMR for accurate WAT quantification, irrespective of the animal's adiposity level or dietary background.