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Male and female Wistar strain rats were given 0.05% N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in their drinking water for 6 weeks and then water without BBN for 18 weeks. Diethylstilboestrol and testosterone were implanted subcutaneously into both intact and gonadectomised animals before or after treatment with BBN to evaluate their effects on the development of bladder tumours. Diethylstilboestrol reduced the incidence of bladder tumours significantly in male rats. The incidence was higher in female rats after spaying and administration of testosterone after BBN treatment, than in the intact female.-These results suggest that diethylstilboestrol inhibits carcinogenesis of the urinary bladder induced by BBN and growth of bladder tumours induced by BBN, in male rats. On the other hand, testosterone seems to stimulate the growth of bladder tumours induced by BBN in female rats. [ABSTRACT FROM AUTHOR]

The effects of chronic mechanical stimulation induced by glass balls or paraffin balls on precursor lesions of the urinary bladder of male Wistar strain rats induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in the drinking water were studied. When foreign bodies were present in the bladder, proliferative lesions of the urinary bladder epithelium were found even without administration of carcinogen. When the foreign bodies were implanted into the urinary bladder and then rats were given BBN in the drinking water for the first 4 weeks of the experimental period, a high incidence of tumors of the urinary bladder was observed. The incidence of tumors induced by BBN was increased by the presence of glass balls or paraffin balls in the urinary bladder. These results clearly show that foreign bodies in the urinary bladder have a significant effect in promoting carcinogenesis of the urinary bladder in rats. [ABSTRACT FROM AUTHOR]