Abstract
BACKGROUND: Dietary interventions have been shown to attenuate some of the myocardial pathological alterations associated with obesity. This study evaluated the effect of dietary normalization from a fat/fructose/cholesterol-rich diet to chow on left ventricular (LV) myocardial fibrosis, fat infiltration and hypertrophy but also the specific influence of obesity, plasma lipids and glucose metabolism markers on heart morphology in a Göttingen Minipig model of obesity. METHODS: Forty castrated male Göttingen Minipigs were assigned to three groups fed either standard minipig chow (SD, n = 8) for 13 months, fat/fructose/cholesterol-rich diet (FFC, n = 16) for 13 months or fat/fructose/cholesterol-rich diet for 7 months and then changed to standard minipig chow for the remaining 6 months (FFC/SD, n = 16). Body weight, body fat percentage, plasma lipids and glucose metabolism markers were evaluated in all three groups after 6-7 months (prior to diet adjustment for FFC/SD) and again before termination. Further, biochemical quantification of myocardial collagen and triglyceride content, semi-quantitative histological evaluation of fibrosis and fat infiltration and quantitative histological analysis of collagen and cardiomyocyte diameter were performed and heart weight was obtained after termination. Group differences were evaluated using Kruskal-Wallis test and Fisher's exact test for categorical variables. Pearson correlation analysis was performed to test for correlations between myocardial changes and selected explanatory variables. For non-parametric response variables, a Spearman correlation analysis was applied. RESULTS: Myocardial collagen content quantified biochemically was significantly lower in FFC/SD compared to FFC (P = 0.02). Furthermore, dietary normalization from a fat/fructose/cholesterol-rich diet to chow caused stagnation of body weight and body fat percentage, normalized intravenous glucose tolerance index (K(G)) and plasma lipid levels. CONCLUSION: Dietary normalization led to lower LV collagen content in obese Göttingen Minipigs. Despite gross obesity and significant deteriorations in glucose and lipid metabolism, only mild myocardial changes were found in this model of obesity and therefore further model optimization is warranted in order to induce more severe myocardial changes before dietary or pharmacological interventions.