Abstract

Atherosclerosis and heart diseases are major causes of morbidity and mortality in adults in industrialized nations. The aim of this study was to assess the potential influence of high-cholesterol diet-induced oxidative stress on composition and properties of red blood cells (RBCs) in rabbits. Thus, percentage of hematocrit, RBCs, white blood cells (WBCs) and platelets counts, total cholesterol (TC), low density lipoprotein (LDL), triglycerides (TG) and high density lipoprotein (HDL), Thiobarbituric acid reactive substances (TBARS) serum level, antioxidant enzymes activity (Superoxide dismutase: SOD; Glutathione peroxidase: GPx), hemoglobin (Hb) and Hb derivatives (oxyhemoglobin: HbO₂; carboxyhemoglobin: HbCO; sulfohemoglobin: SHb; met-hemoglobin: Met-Hb) were measured in control and high fat diet (HFD) rabbits. We found that the TC, LDL, TG and HDL (mg/dl) were significantly (p < 0.001) increased in HFD rabbits compared with control rabbits. A significant (p < 0.05) decrease in Hb (g/dl), percentage of hematocrit and RBCs count was observed in HFD rabbits compared with control rabbits while a significant increase in platelet and WBCs counts was observed. The TBARS was significantly (p < 0.05) increased in HFD rabbits compared with control rabbits while antioxidant enzymes SOD and GPx activity were significantly (p < 0.05) decreased. A significant increase in percentage of Met-Hb, HbCO and SHb was observed in HFD rabbits compared with control rabbits while a significant decrease in percentage of HbO₂ was observed. This study shows that hypercholesterolemia affects the level of Hb and Hb derivatives which causes anemia and may produce reactive oxygen species (ROSs) and other free radicals increasing TBARS and decreasing SOD and GPx enzymes activities. Hypercholesterolemia may promote the conversion of HbO₂ and the fraction of unstable Hb molecules to Met-Hb, SHb and HbCO. Furthermore, increased platelet and WBCs count in HFD rabbits may be of pathophysiological importance for the progression of atherosclerosis and thromboembolic complications. This study suggests that hypercholesterolemia may produce free radicals which promote oxidation of Hb and reduce its concentration and conversion of HbO₂ to Met-Hb and the fractions of unstable Hb molecules to Met-Hb, SHb and HbCO. Furthermore, an imbalance between free radical production and antioxidant enzymes activities may lead to oxidative stress.

Key words: high cholesterol diet; oxidative stress; antioxidant enzyme activates; red blood cells; atherosclerosis