P78: Longitudinal Micro-Ultrasound assessment of the OB/OB Mouse Model: Evaluation of Cardiovascular, Renal and Hepatic Parameters

Abstract

Purpose/Background/Objectives

Obesity is associated with increased risk factors for cardiovascular disease (CVD). Leptin-deficient mice (ob/ob) are widely employed to investigate obesity. This study is aimed at providing a micro-ultrasound (mUS) longitudinal evaluation of the ob/ob mouse in terms of cardiovascular effects, consequences for renal microcirculation and liver fat accumulation.

Methods

Sixteen wild-type (wt) and eleven ob/ob male mice were studied at 8 (T₀) and 25 (T₁) weeks of age with a mUS system (Vevo2100). Cardiac output (CO), ejection fraction (EF), stroke volume (SV), fractional shortening (FS) and E/A ratio were measured from cardiac images. Mean diameter (Dm_abd, Dm_car), relative distension (relD_abd, relD_car) and pulse wave velocity (PWV_abd, PWV_car) were obtained for both abdominal aorta and common carotid. Renal resistivity and pulsatility index (RI, PI) were assessed. The ratio between grey-levels related to liver and kidney (Steato-Score) was used as index of hepatic steatosis.

Results: At T₀, ob/ob mice showed reduced SV, EF, CO and relD_abd values and increased LVmass, PWV_abd, RI, PI and Steato-score. Similar results for SV, EF, CO, RI, PI and Steato-Score were found at T₁; furthermore, obese mice showed reduced Dm_abd and Dm_car measurements in comparison with lean controls. The longitudinal analysis showed an increase in LVmass and Dm_abd and a reduction of FS, EF, CO, relD_abd and relD_car for wt animals and no differences for the ob/ob one.

Conclusions

ob/ob mice presented a premature cardiac dysfunction without a further age-related deterioration and a reduction in the abdominal aorta and carotid artery mean diameter in adult age.