Influência de diferentes dietas hipercalóricas sobre o estresse oxidativo cardíaco

Abstract

Oxidative stress has been associated with several cardiometabolic changes, and the involvement of excess glucose and fatty acids has been demonstrated in this process. The purpose of the study was to investigate the effects of different high-calorie diets on cardiac oxidative stress and the pro and antioxidant signaling pathways. Wistar rats (30 days) were randomized into 4 experimental groups: Control (C, n = 5), Hyperglycidic (HG, n = 5), Hyperlipidic (HL, n = 5) and Hyperlipidic with sucrose (HLS, n = 5). Animals C, HG, HL and HLS received standard diet, high sucrose diet, high fat diet with lard and high fat diet with lard and sucrose for 20 weeks, respectively. Body mass and fat deposits, adiposity index, dietary parameters, as well as cardiovascular characteristics and comorbidities were determined. The analysis of cardiac oxidative stress was performed using substances reactive to thiobarbituric acid (TBARS), expressed in levels of malondialdehyde (MDA) and carbonylated proteins by spectrophotometry and the pathways involved determined by Western Blot. The data were expressed as mean and standard error of the mean and submitted to analysis of variance (ANOVA) complemented with Tukey's test. The level of significance adopted was 5%. The initial and final body masses, as well as the body mass gain did not differ between the groups. However, the HL group showed an increase in retroperitoneal, total fat and adiposity index in relation to C, characterizing obesity, while the HG group had a lower adiposity index compared to groups C, HL and HLS. Comparing to HG, the HL group showed an increase in visceral, retroperitoneal and total fat pads. The area under the glycemic curve of the HLS group was greater than that of C (p = 0.04). The levels of MDA showed difference in the groups HL and HLS in relation to C (C = 136 ± 17 vs. HL = 591 ± 103; HLS = 545 ± 104), as well as the carbonylated protein (C = 9.95 ± 2.13 vs. HL = 24.6 ± 3.5; HLS = 27.0 ± 3.8). Proteins related to oxidative and antioxidant signaling pathways did not differ between groups. The HG group obtained a reduction in the angiotensin 1 receptor (AT1) and glutathione peroxidase (GPX) in relation to HL. In conclusion, hyperlipidic and hyperlipidic dietary interventions with sucrose promoted cardiac oxidative stress, in presence or absence of obesity, respectively. However, this process was not mediated by the pro-oxidant AT1 and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (Nox2), as well as by the quantitative reduction of antioxidant enzymes.