Effects of oral administration of bezafibrate on peroxisomes and carnitine acetyltransferase in rat hepatocytes.

Changes in fine structure of peroxisomes and mitochondria were examined by electron microscopy in the hepatocyte of rats administered with bezafibrate, a hypolipidemic reagents. Peroxisomes increased to approximately 4.8 times in number one week after oral administration of bezafibrate in male rats. Newly induced peroxisomes showed paler matrix with frequent absence of core structure at two weeks after administration, peroxisomes further increased in number, 5.8 times in males, and were mostly devoid of core structure. Mitochondrial cristae were occasionally arranged along the long axis of mitochondria. Activity of carnitine acetyltransferase (CAT), one of the enzymes involved in beta oxidation of fatty acids, increased significantly after oral administration of bezafibrate. At two weeks after administration, it increased up to 12.0 times in males, 8.4 times in castrated males, 3.8 times in females and 5.5 times in castrated females, respectively. Cytochemically, CAT was localized in the outer compartment and inner membrane of mitochondria. CAT activity was also detected in the matrix of peroxisomes at two weeks after oral administration of bezafibrate.