Influence of single and concurrent clofibrate and phenobarbital administration on cytochrome P450-dependent mixed function oxidase activities and peroxisome proliferation in male rat liver

Dehydroepiandrosterone sulfate and cytochrome P450 inducers alleviate fatty liver in male rats fed an orotic acid-supplemented diet

The effects of the peroxisome proliferator, dehydroepiandrosterone sulfate (DHEAS), and the typical cytochrome P450 (CYP) inducers phenobarbital (PB) and 3-methylcholanthrene (3-MC) on fatty liver were examined in rats. Treating rats with orotic acid caused marked accumulation of lipid droplets in the liver. This effect of orotic acid was almost eradicated by co-treatment with DHEAS and PB. While DHEAS or PB alone also alleviated fatty liver, treatment with 3-MC caused little effect on a reduction in lipid droplets. Histopathological examinations revealed numerous peroxisomes in the liver of rats treated with DHEAS. In addition, a significant increase in the expression on hepatic CYPs was observed in rats the fatty liver of which was attenuated. Regarding other enzymes associated with hepatic fatty acid oxidation, the expression levels of sirtuin 1, sirtuin 6, and carnitine palmitoyltransferase 1 were also upregulated most markedly by treatment with DHEAS alone. Thus, the attenuation in fatty liver observed in the present study is likely due to peroxisome proliferation and the induction of fatty acid-metabolizing enzymes by DHEAS and typical CYP inducers.

Single and chronic administration of ciprofibrate or of ciprofibrate-glycinate in male Fischer 344 rats: Comparison of the effects on morphological and biochemical parameters in liver and blood

Fibrates lead to a reduction of serum triglycerides and cholesterol in hyperlipidemic patients. Their therapeutic use, however, can be associated with adverse effects like gastrointestinal disorders, myalgia, myositis and hepatotoxicity. Large doses can even cause hepatocellular carcinoma in rodents. Additionally, interactions with the biotransformation of other compounds at the cytochrome P450 (CYP) system have been observed. Thus, the discovery of new derivatives with less of these side effects is of great interest. In the present study a single (10 mg/kg body weight) or a 4-week (1 or 10 mg/kg body weight daily) oral administration of ciprofibrate or of the newly synthesized ciprofibrate-glycinate was investigated in adult male Fischer 344 rats. Serum lipid concentrations were distinctly decreased after single but only slightly after chronic administration of the two fibrates, whereas liver parameters revealed a slight concentration and time dependent hepatotoxicity. Histologically, a hypertrophy, an eosinophilia, a reduced glycogen content and also an apoptosis of the hepatocytes was observed. Effects were more pronounced after chronic treatment and after application of the higher dosage. All CYP enzymes investigated were induced in a time and concentration dependent manner. Resulting CYP mediated monooxygenase and oxidase activities showed a dependency both on enzyme induction and hepatotoxic effects. With no parameter investigated major differences were seen between ciprofibrate and ciprofibrate-glycinate. Thus, the present investigations revealed no noticeable advantages of ciprofibrate-glycinate over its parent compound ciprofibrate.

Prevention of orotic-acid-induced fatty liver in male rats by dehydroepiandrosterone and/or phenobarbital

Dehydroepiandrosterone (DHEA) is a steroid hormone which induces the peroxisome proliferation in rodents. The fatty liver induced by orotic acid and a high sucrose diet in male rats was prevented by the administration of DHEA and/or phenobarbital (PB). A significant increase in the liver weight was induced in the DHEA group (relative weight) and the DHEA + PB group (absolute and relative weight). The liver weight increased more conspicuously in the DHEA + PB group than in the DHEA group. The increase in the liver weight was caused by an increase in the cell size and peroxisome number. In addition, the administration of DHEA alone and the combination of DHEA and PB prevented the lipid droplet accumulation in hepatocytes. The administration of PB alone also prevented the accumulation of lipid droplets without any increase in the liver weight.