Abdominal fat analyzed by DEXA scan reflects visceral body fat and improves the phenotype description and the assessment of metabolic risk in mice

Clinical studies have demonstrated a strong relationship between visceral fat content with metabolic diseases, such as type 2 diabetes and liver steatosis. Obese mouse models are an excellent tool to study metabolic diseases, however there are limited methods for the non-invasive measurement of fat distribution in mice. Although micro Magnetic Resonance Imaging and micro Computed Tomography are the gold standards in the measurement of fat distribution, more economical and accessible methods are required. Dual Energy X-ray Absorptiometry (Dxa) is an effective method in characterizing fat content however it cannot discriminate between visceral and subcutaneous fat depots. We demonstrate that an evaluation of abdominal fat content measured by Dxa through the selection of one localized abdominal area strongly correlates with visceral fat content in C57Bl6J mice. We found that Dxa is able to measure fat pad volume ex vivo with high accuracy, however, the measurement of visceral fat in vivo shows an overestimation caused by subcutaneous tissue interference. The overestimation is almost constant for a wide range of values and thus it is possible to correct the data for a more accurate estimation of visceral fat content. We demonstrate the utility of this technique in characterizing phenotypes of several obese mouse models (ob/ob, db/db, MC4RKO, DIO) and evaluating the effect of treatments on visceral fat content in longitudinal studies. Additionally, we also establish abdominal obesity as a potential biomarker for metabolic abnormalities (liver fat accumulation, insulin resistance/diabetes) in mice, similar to that described in humans.