Cetaben is an exceptional type of peroxisome proliferator.

1. Cetaben in contrast to fibrates affect differently peroxisomal constituents. 2. Changes in large scale of liver non-peroxisomal parameters were compared after 10 days administration of equal doses (200 mg/kg/day) of cetaben and clofibric acid to male Wistar rats. 3. Clofibric acid treatment increased markedly the activities of FAD-glycerol-3-P dehydrogenase, beta-hydroxyacyl-CoA dehydrogenase, cytochrome-c oxidase, malic enzyme, NAD-glycerol-3-P dehydrogenase, ethoxycoumarin deethylase, p-nitroanisole demethylase and amounts of cytochrome P-450 and b5. 4. However no analogical changes were observed after cetaben treatment in the livers of experimental animals. 5. Both drugs increased the activities of alanine-glyoxylate aminotransferase-1 and acetylcarnitine transferase--enzymes with proven mitochondrial and peroxisomal location. 6. Cetaben contrary to clofibric acid does not increase solubilization of peroxisomal enzymes. 7. Enhanced acetylcarnitine transferase and alanine-glyoxylate aminotransferase-1 activities were distributed in mitochondria as well as in peroxisomes after clofibric acid treatment, however, only peroxisomes were enriched after cetaben administration. 8. The results obtained suggest that cetaben represents an exceptional type of peroxisome proliferator, specifically affecting peroxisomes, without having a negative influence on the processes of peroxisome biogenesis.

Cetaben and fibrates both influence the activities of peroxisomal enzymes in different ways.

The effects of cetaben and clofibric acid were compared on the activities of peroxisomal enzymes in the liver and kidney of male Wistar rats. Cetaben at 200 mg/kg body wt increased the activities of all of the enzymes in the liver that were studied two to eight times, whereas the changes induced by the same dose of clofibric acid increased some of the enzymes and decreased others. In the kidney, cetaben increased the activities of all investigated peroxisomal enzymes, while clofibric acid only increased the activity of palmitoyl-CoA oxidase. The data obtained in the dose-response study of cetaben revealed a significant rise in the activities of peroxisomal enzymes in both the liver and kidney at doses of 50-100 mg/kg body wt administered over 10 days, but the maximal effect was observed at 250 mg/kg. Palmitoyl-CoA oxidase and D-amino acid oxidase respond most markedly to cetaben. Cetaben could represent an atypical peroxisomal proliferator, since it increased the activities of all peroxisomal enzymes investigated. The fact that the individual components localized in the peroxisomes do not change markedly could be of importance with respect to the function and physical properties of peroxisomes.