SIGNIFICANT INDUCTION OF EPITHELIAL CELL PROLIFERATION IN THE URINARY BLADDERS OF NCI-BLACK-REITER MALE RATS BY N-BUTYL-N-(4-HYDROXYBUTYL) NITROSAMINE

Abstract

The response of the urinary bladder epithelium in NCI-Black-Reiter (NBR) rats to administration of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN), a potent carcinogen in rodents, was examined. Male NBR rats were exposed to 0.05% BBN in the drinking water for 8 weeks, or no added chemical. Microscopically, simple hyperplasia was observed in the urinary bladder epithelium of treated rats sacrificed at the end of week 4. Moreover, after 8 weeks administration of BBN, papillary or nodular (PN) hyperplasia and squamous metaplasia were produced. Levels of DNA synthesis, as indicated by incorporation of 5-bromo-2'-deoxyuridine, areas of simple and PN hyperplasia in rats treated by BBN were significantly increased than in non-treated ones at the end of week 8. These results indicate that the urinary bladder of NBR male rats is very responsive to BBN insult.