title: Choline deficient diet enhances the initiating and promoting effects of methapyrilene hydrochloride in rat liver as assayed by the induction of gamma-glutamyltranspeptidase-positive hepatocyte foci.
abstract: Earlier we demonstrated that short-term feeding of methapyrilene hydrochloride (MPH) and of a choline deficient (CD) diet to rats induced peroxidative damage of microsomal membrane lipids of liver cells. In the present study, we investigated whether a CD diet modifies the extent of MPH-induced lipid peroxidation and whether the modifications lead to changes in the initiating and promoting action of these agents using assays of the induction of gamma-glutamyltranspeptidase (GGT)-positive hepatocyte foci. Addition of 0.1% MPH to a CD diet enhanced the extent of microsomal lipid peroxidation induced by a CD diet alone. Feeding a choline supplemented (CS) or a CD diet containing 0.1% MPH for 2 weeks followed by 7 weeks promotion by a CD diet plus phenobarbital was ineffective in inducing GGT-positive foci. Feeding MPH in a CS or a CD diet for 4 weeks, however, resulted in the development of substantial numbers of GGT-positive foci. There was a 3 fold increase in the number of foci in rats initiated with a CD + MPH diet over that in rats initiated with a CS + MPH diet. 0.1% MPH in a CS diet or a CD diet exerted significant promotional effects on the induction of GGT-positive foci in rats initiated with a single injection of diethylnitrosamine. Addition of MPH to a CD diet was additive in inducing GGT-positive foci. The results suggest that lipid peroxidation of the liver may be involved in the carcinogenic and/or promoting effects of MPH and a CD diet.
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D002796:Choline Deficiency / Q000378:metabolism*; D004789:Enzyme Activation; D008054:Lipid Peroxides / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008113:Liver Neoplasms / Q000209:etiology; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism; D008701:Methapyrilene / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
chemical_list: D000631:Aminopyridines; D008054:Lipid Peroxides; D008563:Membrane Lipids; D008701:Methapyrilene; D005723:gamma-Glutamyltransferase