Abstract
It is well known that stress and hyperlipidemia are risk factors of atherosclerotic diseases. It has been reported that various types of stress accelerate the progress of atherosclerosis. However, there have been no reports on the correlation between stress due to sonic exposure alone and stress due to abnormal lipid metabolism. Therefore, many problems on the subject remain to be solved. The aim of this study is to clarify these problems. In the present study, We divided rabbits on a high-cholesterol diet into two groups—sonic stress (+) and sonic stress (-) groups. Each group was examined for fluctuations in the serum lipid levels, pathological changes, and the effects of γ-Oryzanol.
High values of serum TG were observed in the sonic stress (+) group, compared with the sonic stress (-) group, but no differences were observed in TC, HDL-C, and LDL-C. Next, pathological studies demonstrated that sonic stress promoted atherosclerotic changes in the aorta of the rabbit.
As a result, it was assumed that blood pressure was elevated and platelet aggregation was accelerated by sonic stress.
Atrophy of thymus gland observed as an influence of sonic stress exerted on the weight of the various organs. This phenomenon is considered to be interesting in thinking about immuno-reaction and progress of atherosclerosis.
In the following study, as a result of the effect of γ-Oryzanol, as anti-stress agent which improved lipid metabolism in the stress (+) group and (-) group, it was found that the agent had a stronger anti-atherosclerotic activity in the sonic stress (+) group.
The results of these studies, therefore suggested that sonic stress accelerates atherosclerosis.
