The Effect of Iron and Cholesterol on Neuronal Apoptosis in Dentate Gyrus of Hippocampus in Rabbits Fed with High-Cholesterol Diet

Some of the studies showed that abnormal high level of iron and cholesterol in the brain had neurodegenerative effects such as in Alzheimer's disease. But, the previous studies in this field were not enough and had controversy in results. As the prevalence of Alzheimer's disease is increasing, this study aimed to evaluate the effect of iron and cholesterol on the level of neuronal apoptosis in dentate gyrus of hippocampal formation. Male New Zealand white rabbits were divided into the control, the iron (50 mg/kg; gavage), the high-cholesterol diet (containing 2% cholesterol), and the high-cholesterol diet plus iron groups. Serum levels of total cholesterol, high-density lipoprotein (LDL), and low-density lipoprotein (HDL), before and after the regimen for 6 weeks, were measured. Then, the rabbits for immunohistochemical staining via TUNEL test (Terminal deoxynucleotidyl transferase biotin–dUTP nick end labeling) and evaluation of neuronal apoptosis in dentate gyrus of hippocampal formation were anesthetized and brains were dissected. After the regimens, serum levels of total cholesterol, LDL, and HDL in the cholesterol-receiving groups increased significantly compared to the control group (P < 0.05 for all). Histological results demonstrated that neuronal apoptosis in the dentate gyrus of the high-cholesterol diet group increased significantly (P < 0.05) comparing to the control group. Iron had not significant effect when used alone or with cholesterol on neuronal apoptosis in the dentate gyrus in rabbits. Our recent results showed that high-level cholesterol diet had significant effect on the neuronal apoptosis in the dentate gyrus in rabbits; but use of iron alone or with high-level cholesterol diet had not significant effect on it.