Cardiac, Metabolic and Molecular Profiles of Sedentary Rats in the Initial Moment of Obesity

BACKGROUND: Different types of high-fat and/or high-energy diets have been used to induce obesity in rodents. However, few studies have reported on the effects observed at the initial stage of obesity induced by high-fat feeding on cardiac functional and structural remodelling. OBJECTIVE: To characterize the initial moment of obesity and investigate both metabolic and cardiac parameters. In addition, the role of Ca(2+) handling in short-term exposure to obesity was verified. METHODS: Thirty-day-old male Wistar rats were randomized into two groups (n = 19 each): control (C; standard diet) and high-fat diet (HF, unsaturated high-fat diet). The initial moment of obesity was defined by weekly measurement of body weight (BW) complemented by adiposity index (AI). Cardiac remodelling was assessed by morphological, histological, echocardiographic and papillary muscle analysis. Ca(2+) handling proteins were determined by Western Blot. RESULTS: The initial moment of obesity occurred at the 3(rd) week. Compared with C rats, the HF rats had higher final BW (4%), body fat (20%), AI (14.5%), insulin levels (39.7%), leptin (62.4%) and low-density lipoprotein cholesterol (15.5%) but did not exhibit alterations in systolic blood pressure. Echocardiographic evaluation did not show alterations in cardiac parameters. In the HF group, muscles were observed to increase their +dT/dt (C: 52.6 ± 9.0 g/mm(2)/s and HF: 68.0 ± 17.0 g/mm(2)/s; p < 0.05). In addition, there was no changes in the cardiac expression of Ca(2+) handling proteins. CONCLUSION: The initial moment of obesity promotes alterations to hormonal and lipid profiles without cardiac damage or changes in Ca(2+) handling.