Dietary Fat and Sugar Differentially Affect β-Adrenergic Stimulation of Cardiac ERK and AKT Pathways in C57BL/6 Male Mice Subjected to High-Calorie Feeding

BACKGROUND: High dietary fat and sugar promote cardiac hypertrophy independently from an increase in blood pressure. The respective contribution that each macronutrient exerts on cardiac growth signaling pathways remains unclear. OBJECTIVE: The goal of this study was to investigate the mechanisms by which high amounts of dietary fat and sugar affect cardiac growth regulatory pathways. METHODS: Male C57BL/6 mice (9 wk old; n = 20/group) were fed a standard rodent diet (STD; kcal% protein-fat-carbohydrate, 29-17-54), a high-fat diet (HFD; 20-60-20), a high-fat and high-sugar Western diet (WD; 20-45-35), a high-sugar diet with mixed carbohydrates (HCD; 20-10-70), or a high-sucrose diet (HSD; 20-10-70). Body composition was assessed weekly by EchoMRI. Whole-body glucose utilization was assessed with an intraperitoneal glucose tolerance test. After 6 wk on diets, mice were treated with saline or 20 mg/kg isoproterenol (ISO), and the activity of cardiac growth regulatory pathways was analyzed by immunoblotting. Data were analyzed by ANOVA with data from the STD group included for references only. RESULTS: Compared with HCD and HSD, WD and HFD increased body fat mass 2.7- to 3.8-fold (P 1.5-fold (P 47%; P 34%; P 64%; P