Early exposure to restraint stress enhances chemical carcinogenesis in rat liver

This study examines the effect uf a stress-associated condition on chemical hepatocarcinogenesis in the rat. Rats were given diethylnitrosamine (200 mg/kg. b.w., i.p.), followed, 1 week later, by three cycles of immobilization at room tempera ture. Two weeks after the last cycle they were treated according to the resistant hepatocyte protocol.;At 4 weeks after selection. mean size of glutathione-S-transferase: 7-7 positive foci/nodules was increased in the immobilized group (0.82 +/-0.22 vs. 0.25 +/-0.04 mm(2) in controls). Furthermore. at the end of 1 year 10/13 animals (77%) developed hepatocellular carcinoma in the former group, while only 6/14 (43%) incidence of cancer was found in controls. These results indicate that exposure to restraint stress early during carcinogenesis enhances the development of chemically-induced hepatocellular carcinoma in the rat. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.