Promotive effect of estrogen on hepatocarcinogenesis and estrogen receptor in male rats

Abstract

Male Sprague-Dawley rats were given a single intraperitoneal injection of diethylnitrosamine (DEN, 200mg per kg of body weight). Since 4 weeks after injection the rats were fed diethylstilbestrol (DES, 1.8mg per day) for eight months. Rats given DEN and DES developed grossly visible hepatic hyperplastic nodules. Total area and mean area per foci of γ-glutamyl transpeptidase-positive foci in the liver were significantly larger in the rats given DEN and DES than the rats given DEN or DES alone. Total estrogen receptor (ER) contents in liver cytosol determined by enzyme immunoassay were significantly larger in rats given DES for 3.5 months than those in rats not given DES. However unoccupied ER contents determined by radioreceptor assay were significantly smaller in rats given DES for eight months than those in rats not given DES. It is suggested, therefore, that DES can promote hepatocarcinogenesis mediated by ER in the rat.