Progression of Obesity‐Related Heart Dysfunction in Two Rat Models

Abstract

The prevalence of obesity in the US has increased substantially over the past decades, with upwards of 33.8% of the population obese and 68% overweight. In childhood, 11.7% – 14.6% of preschoolers in developed countries and 16.4% of adolescents in the US are considered obese. Several animal models have been utilized to study the impact of obesity on the heart. In rats, the most prevalent models are the Zucker Fatty rats (ZF), a genetically modified rat with a leptin receptor deficiency, and normal Sprague Dawley rats (SD) fed a high fat diet. In the present study, we examined echocardiographic indices for each model in order to evaluate heart function. Values for IVRT/HR were significantly higher in ZF rats compared to Zucker Lean rats (0.058±0.010 ms/bpm vs, 0.045±0.009 ms/bpm, p<0.05) at 19 weeks of age, however the values for SD rats were not significantly different after eating a high fat diet for 10 weeks. E/A ratio was not significantly different in ZF rats compared to lean controls, however was significantly decreased in SD rats fed a high fat diet compared to rats fed a normal diet (0.98 vs. 1.11; p<0.05). Diastolic dysfunction was evident in both models, although the values for the ZF rats indicated less relative diastolic impairment than the SD rats fed a high fat diet. Continued work will examine the progression and mechanistic differences in these models, and their relevance to human obesity.