Influência da dieta hiperlipídica saturada sobre a morfologia cardíaca em animais propensos e resistentes à obesidade

Abstract

The prevalence of obesity has grown rapidly and represents one of the main challenges to public health. Excess body mass contributes to the establishment of diseases such as diabetes, arterial hypertension and dyslipidemias. These obesity-associated morbidities can induce Left Ventricular Hypertrophy (LVH) and changes in the levels of interstitial collagen in the Left Ventricle (LV), which may impair myofibrillar movement. However, some animals and humans, even consuming hypercaloric and hyperlipidic diets, have the ability to resist the phenomenon of hyperphagia and body fat gain, a condition that we call obesity resistance. However, few studies have investigated the cardiac morphological effects of Saturated High Fat Diets (DH) based on lard, against the condition of Obesity Resistance. Thus, the purpose of the study was to investigate the influence of DH on cardiac morphology in obesity-prone and resistant animals. The hypothesis of our study is that Obesity-Resistant (ObB) animals present cardioprotection to pathological LVH due to greater sensitivity to insulin and leptin. Wistar rats (n = 71), aged 30 days, were initially randomized into two groups: a) DP: fed a standard diet (n = 35) and b) DH: fed a saturated high fat diet (n = 36). The experimental protocol consisted of two moments: induction (4 weeks) and maintenance of obesity (10 weeks), totaling 14 consecutive weeks. After the obesity induction period, there was a redistribution of groups through the tertile criterion, body mass, thus identifying three groups: Control (C), Obese (Ob) and ROb. The food intake variables evaluated were food intake, caloric intake and food efficiency. Body composition was measured through body mass and fat, in addition to the adiposity index. Metabolic alterations were investigated by the glucose tolerance test, measurements of serum levels of insulin, leptin and the insulin resistance index (HOMA-IR). The total mass of the heart, right and left ventricles, atrium and their respective relationships with the length of the tibia, as well as the cross-sectional area (AST) and LV interstitial collagen were determined in order to identify the absence or presence of pathological LVH. . The pathophysiological damage was measured from the quantification of creatine kinase enzymes (CK) and its MB subunit, in addition to lactate dehydrogenase (LDH). ANOVA (one- and two-way) statistical tests were used, complemented with Tukey's test of multiple comparisons, with a significance level of 5%. The adiposity index, food intake and caloric consumption of the OB group were higher than the other groups, which characterizes them as prone to obesity. The area under the glycemic curve, HOMA-IR, insulin and serum leptin, total cholesterol and HOMAIR and HDL were higher in the groups exposed to DH, regardless of obesity propensity or resistance. No significant difference was observed in relation to the triglyceride index between the groups submitted to PD and DH. The Ob and ROb groups showed statistically higher values of total heart mass, LV, RV and their respective relationships with the length of the tibia, as well as AST and LV interstitial collagen in relation to group C. The cardiac damage biomarker CK- MB was significantly higher in the two experimental groups undergoing DH. In conclusion, the results indicate that DH induced LVH and accumulation of interstitial collagen in the LV, combined with changes in glucose sensitivity and elevation of biomarkers of cardiac damage, regardless of resistance condition or obesity propensity.