BETA-CAROTENE REDUCES THE DUCTULAR (OVAL) CELL REACTION IN THE LIVER OF WISTAR RATS SUBMITTED TO THE RESISTANT HEPATOCYTE MODEL OF CARCINOGENESIS

The morphology of livers of Wistar rats treated with betacarotene (BC) , vitamin A (VA, retinol acetate) or corn oil (CO, controls) and submi tted to the resistant hepatocyte model of carcinogenesis was studied. Preneoplastic lesions (PNL) were smaller and less numerous in the BC g roup. The latter group also presented fewer placental glutathione-S-tr ansferase (GST-P) positive and hematoxylin and eosin (H&E) distinguish able PNL, with smaller mean areas and smaller mean areas of the liver occupied by PNL. Clear cell foci predominated in BC livers. In picrosi rius-stained liver sections, fibrosis, whether or not accompanying the bile ductular cells, surrounded only 16.67% of PNL in the BC group, a s compared to 35.71% in the VA group and 87.72% in the CO group. Moreo ver, the ductular cell reaction was smaller in the BC group. Smooth mu scle actin-positive cells surrounded some PNL, mostly in CO rats, and less frequently in the VA and BC groups. Examination by transmission e lectron microscopy (TEM) showed that cells with nuclei similar to thos e of perisinusoidal cells, devoid of cytoplasmic fat globules, probabl y represented myofibroblasts derived from Ito cells and accompanied th e ductular cell reaction. On the basis of these results, we suggest th at BC reduced not only the PNL but also the ductular (oval) cell react ion in this experimental model.