Induction of foci of altered, γ-glutamyltranspeptidase-positive hepatocytes in carcinogen-treated rats fed a choline-deficient diet

Abstract

A series of experiments was performed to investigate whether, after exposure of rats to a chemical hepatocarcinogen, feeding a choline-deficient (CD) diet would promote the proliferation of initiated liver cells, and their evolution to foci of altered γ-glutamyltranspeptidase (GGT)-positive hepatocytes, without subjecting the animals to further experimental manipulations. Diethylnitrosamine (DEN), in single doses of 15-150 mg/kg body weight, was injected into male, Sprague-Dawley rats, either intact or 18 h after a partial hepatectomy (PH). The animals were then fed either a CD or a choline-supplemented (CS) diet for 2-8 weeks. Emergence in the liver of foci of altered, GGT+ hepatocytes was studied by histological and histochemical techniques. Foci, in varying numbers, developed in the liver of all rats fed the CD diet. The number of foci induced was larger when DEN was administered after PH rather than to intact rats. Foci developed in none of the livers of rats fed the CS diet, except in one experiment in which 30 mg DEN/kg body weight was injected after a PH. In all cases, foci of altered, GGT+ hepatocytes were shown to be α-foetoprotein after immunofluorescence staining of liver sections. It is concluded that feeding a CD diet exerts a strong promoting action on the proliferation and further evolution of liver cells initiated by a chemical carcinogen, providing the basis for a new and efficient procedure for the induction of foci of altered hepatocytes in rat liver.