Combined effect of ethanol and carbon disulphide on cytochrome P-450 mono-oxygenase, lipid peroxidation and ultrastructure of the liver in chronically exposed rats.

A 5-month treatment of rats with ethanol (10% solution in drinking water) stimulated aniline p-hydroxylase and the microsomal ethanol oxidizing system (MEOS) by 140 and 70%, respectively, cytochrome P-450 by 22% and accompanied by lipid peroxidation by 40% in microsomes. It also caused smooth endoplasmic reticulum (SER) proliferation and rough endoplasmic reticulum (RER) degranulation in hepatocytes. Repeated inhalatory exposure of rats to 1.5 g/m3 of CS2, 5 h daily, 5 days a week for 5 months decreased aniline p-hydroxylase and MEOS by 70 and 55% respectively, doubled hexobarbital sleeping time and depressed cytochrome P-450 by 30% and its conversion to cytochrome P-420; these effects were accompanied by the appearance of cytochrome P-420, the intensification of lipid peroxidation in microsomes and some degranulation of RER in hepatocytes. Combined exposure of rats to ethanol and CS2 resulted in a significant potentiation of the inhibitory effects of CS2 on cytochrome P-450 mono-oxygenase and MEOS but with enhancement of CS2 effects on the liver microsomal mono-oxygenase, but CS2 decreased the effect of ethanol on SER proliferation. The interaction both on the biochemical and the morphological level can be explained with the ethanol-stimulated biotransformation of CS2 to reactive electrophilic derivative(s), the subsequent destruction of cytochrome P-450 to cytochrome P-420 and the intensification of lipid peroxidation.