According to the Vital Statistics Report published by the Japanese Ministry of Health and Welfare, heat disease and cerebrovascular disease are the main causes of death in Japan in addition to cancer. The main pathological finding in heart and cerebrovascular disease is atherosclerosis and the main risk factors, besides the patient's age and diathesis, include hyperlipidemia, hypertension, diabetes, obesity and smoking. The main pathological findings in atherosclerosis include abnormal reactions of neutrophils, lymphocytes and monocytes/macrophages, vascular smooth muscle cells and vascular endothelial cells, and the accumulation of cholesterol ester in the arterial wall, which are prevent by lowering the serum total cholesterol (TC) levels. An increasing number of large-scale intervention studies have reported beneficial results of drug treatment (clofibrate, fenofibrate, bezafibrate, niacin, cholestiramine, gemfibrozil) on lipoprotein abnormalities. Their findings have also revealed that statins (simvastatin, pravastatin, lovastatin, fluvastatin, atorvastatin and rosuvastatin) are effective in preventing coronary artery disease. However, these results indicate that lowering TC levels by 25-30% prevents only about 30% of cardiovascular events. Thus, 70% of cardiovascular events are still not prevented, and it is important to find out how to treat such patients. In addition, it remains to be determined which risk factors for atherosclerosis other than high TC levels (such as hypertension, diabetes, obesity, smoking, high serum triglyceride (TG) levels and hypo-HDL-cholesterolemia) warrant the highest priority for treatment in Japan. Eventually, these all risk factors for atherosclerosis other than high TC levels are associated with the excessive uptake of fatty acids into liver. Recently, we have shown that the clock gene, CLOCK:BMAL1 regulated the peroxisome proliferator-activated receptor (PPAR) gene. PPAR is a member of the steroid/thyroid-hormone receptor superfamily. Their ligands were fatty acids, the extents of which were greater in polyunsaturated fatty acids. Here, based on recent studies including our own, we describe the relationships between fatty acids, especially clock gene and PPARs in the molecular mechanisms that govern lipid metabolism in the arteries.
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