Effects of inhibiting hepatocarcinogenesis upon the early fine structural changes induced in rat hepatocytes by 3'-methyl-4-dimethylaminoazobenzene.

Young adult male Leeds strain rats were fed for up to 10 weeks on diets containing either 0.06% 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) or 0.06% 3'-MeDAB together with 0.0067% 3-methylcholanthrene (MeCh), which is known to inhibit the induction of hepatocarcinogenesis by the azo dye. Controls received either MeCh alone or a normal diet. Animals were killed at 10 days, 4 weeks and 10 weeks and their liver tissues examined by electron microscopy. Although MeCh did not prevent the induction of some non-specific fine structural changes such as glycogen depletion and proliferation of the smooth endoplasmic reticulum (ER), it did prevent the early dislocation and dispersal of the rough ER that was elicited by 3'-MeDAB. This provides further evidence indicating the importance to liver tumorigenesis of this rough ER change, which appears to be induced by all classes of chemical hepatocarcinogens and which, in comparative studies with carcinogen/non-carcinogen pairs of related chemicals, also appears to be specific to carcinogens.