Ultrastructural observation of changes in (hepatic) peroxisomes by 3 to 90 days administration of bezafibrate in male rats.

Although many reports are available to indicate the increase in number and size of peroxisomes by oral administration of hypolipidemic reagents such as clofibrate and bezafibrate, the decrease in number and size of proliferated peroxisomes even during administration of these chemicals has not been well documented. The present study was aimed to detect when the decrease in number and size of peroxisomes would occur. In the present study, ultrastructural changes in hepatocytes of male Wistar rats during 3 to 90 days of oral administration of bezafibrate were analyzed by morphometric and cytochemical methods. By 3-day administration, the weight of the liver and the number and size of peroxisomes were significantly increased. These parameters began to decline from the time 14 days of administration when the weight of the liver and the size of peroxisomes attained the peak. Heterogeneous catalase staining was most remarkable by 7-day administration. Mitochondria were another target cell organelle by bezafibrate. The total area of mitochondria was decreased by 3-day administration. However, by subsequent 7 to 90-day administration, it recovered almost the level of controls. By 90-day administration, many mitochondria had expanded cristae which contained filamentous substances.