Quercetin Prevents Diastolic Dysfunction Induced by a High‐Cholesterol Diet: Role of Oxidative Stress and Bioenergetics in Hyperglycemic Rats

Figure 1. Quercetin protects against the alteration on plasma cholesterol and glycemia levels and lipid profile induced by high-cholesterol diet. Plasma levels of (a) total cholesterol, (b) glucose, (c) triglycerides, (d) LDL, (e) VLDL, and (f)HDL from 12 h fasted rats, fed for 4 weeks with control diet (C), control diet containing 0.5% quercetin (CQ), high-cholesterol diet (HC), or high-cholesterol diet containing 0.5% quercetin (HCQ). Values are expressed as mean ± SEM. N = 6–8 rats/group. Two-way ANOVA test and Bonferroni posttest. Statistical differences: ∗ p < 0.05, ∗∗ p < 0.01, and ∗∗∗ p < 0.001.

Figure 2. Quercetin protects against cardiac diastolic dysfunction induced by high-cholesterol diet. Ultrasound and Doppler imaging showing (a) A wave (atrial filling velocity) expressed as cm/seg and (b) E:A, expressed as the ratio of peak velocity of early to late filling of mitral inflow, in rats fed for 4 weeks with control diet (C), control diet containing 0.5% quercetin diet (CQ), high-cholesterol diet (HC), and high-cholesterol diet containing 0.5% quercetin (HCQ). Values are expressed as mean ± SEM. N = 6 rats/group. Two-way ANOVA test and Bonferroni posttest. Statistical differences: ∗ p < 0.05, ∗∗ p < 0.01, and ∗∗∗ p < 0.001.

Figure 3. Quercetin protects against composition and morphological alterations induced by high-cholesterol diet. (a) The content of cholesterol and (b) weight of the heart were assessed in rats fed for 4 weeks with control diet (C), control diet containing 0.5% quercetin (CQ), high-cholesterol diet (HC), or high-cholesterol diet containing 0.5% quercetin (HCQ). Values are expressed as mean ± SEM. N = 6–8 rats/group. Two-way ANOVA test and Bonferroni posttest. Statistical differences: ∗ p < 0.05.

Figure 4. Quercetin protects against cardiac wall remodeling induced by high-cholesterol diet. (a) Right ventricle, (b) septum, and (c) left ventricle thicknesses; (d) right ventricle and (e) left ventricle luminal areas. (f) shows representative pictures of each group (millimetric bar: 2 mm). Heart dimensions were assessed in rats fed for 4 weeks with control diet (C), control diet containing 0.5% quercetin (CQ), high-cholesterol diet (HC), or high-cholesterol diet containing 0.5% quercetin (HCQ). Values are expressed as mean ± SEM. N = 6–8 rats/group. Two-way ANOVA test and Bonferroni posttest. Statistical differences: ∗ p < 0.5 and ∗∗ p < 0.01.

Figure 5. Quercetin protects against increased myocyte density induced by high-cholesterol diet. (a) Right ventricle, (b) septum, and (c) left ventricle myocyte densities, assessed in rats fed for 4 weeks with control diet (C), control diet containing 0.5% quercetin (CQ), high-cholesterol diet (HC), or high-cholesterol diet containing 0.5% quercetin (HCQ). Values are expressed as mean ± SEM. N = 6–8 rats/group. Two-way ANOVA test and Bonferroni posttest. Statistical differences: ∗ p < 0.05.

Figure 6. Quercetin protects against the decrease in cardiac antioxidant defenses induced by high-cholesterol diet. Antioxidant defenses (a) GSH/GSSG ratio, (b) nuclear translocation of Nrf2, (c) HO-1 expression, and activities of (d) SOD, (e) catalase, and (f) glutathione peroxidase in the heart from rats fed for 4 weeks with control diet (C), control diet containing 0.5% quercetin diet (CQ), high-cholesterol diet (HC), and high-cholesterol diet containing 0.5% quercetin (HCQ). Values are expressed as mean ± SEM. N = 6–8 rats/group. Two-way ANOVA test and Bonferroni posttest. Statistical differences: ∗ p < 0.05, ∗∗ p < 0.01, ∗∗∗ p < 0.001, and ∗∗∗∗ p < 0.0001.

Figure 7. Quercetin protects against cardiac oxidative stress induced by high-cholesterol diet. (a) TBARS and (b) 8-isoprostane were measured in the heart from 12 h fasting rats fed for 4 weeks with control diet (C), control diet containing 0.5% quercetin diet (CQ), high-cholesterol diet (HC), and high-cholesterol diet containing 0.5% quercetin (HCQ). Values are expressed as mean ± SEM. N = 6–8 rats/group. Two-way ANOVA test and Bonferroni posttest. Statistical differences: ∗ p < 0.05, ∗∗ p < 0.01, ∗∗∗ p < 0.001, and ∗∗∗∗ p < 0.0001.

Figure 8. Quercetin protects against the decrease in ATP levels and the alterations of metabolic gene expression induced by high-cholesterol diet. (a) ATP levels, (b) PGC-1α, and (c) UCP2 expression in the hearts of rats fed for 4 weeks with control diet (C), control diet containing 0.5% quercetin diet (CQ), high-cholesterol diet (HC), and high-cholesterol diet containing 0.5% quercetin (HCQ). Values are expressed as mean ± SEM. N = 6–8 rats/group. Two-way ANOVA test and Bonferroni posttest. Statistical differences: ∗ p < 0.05 and ∗∗∗ p < 0.001.