Inhibition of urinary bladder tumors induced by N-butyl-N-(4-hydroxybutyl)-nitrosamine in rats by green tea.
BACKGROUND
Recently, the anticarcinogenic effects of green tea have been studied in sites other than the urinary tract. The present study examined the inhibition by green tea of vesical tumors induced in rats by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN).


METHODS
In the first series of experiments, 0.05% BBN was added to the drinking water of rats and remained present for 5 weeks. In one experiment, six groups of animals received either tap water, green tea, matcha, hojicha, oolong tea or black tea from week 6. In a second experiment, three groups of rats received either tap water, green tea extract or powdered green tea mixed into a pellet diet from week 6. In a third experiment, five groups of rats were fed a pellet diet with addition of either 0, 0.15, 1.5 or 3.0% powdered green tea from week 6. All rats were killed and examined at 40 weeks.


RESULTS
Green tea, particularly green tea leaves, dose-dependently inhibited the growth of BBN-induced urinary bladder tumors when given after the carcinogen.


CONCLUSIONS
Green tea may inhibit bladder tumor growth.
Sato
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Second Department of Urology, Toho University of Medicine, Tokyo, Japan.
D000818:Animals; D001835:Body Weight; D002085:Butylhydroxybutylnitrosamine; D002273:Carcinogens; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000188:drug therapy / Q000473:pathology; D002295:Carcinoma, Transitional Cell / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D002392:Catechin / Q000494:pharmacology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006965:Hyperplasia; D008297:Male; D010212:Papilloma / Q000139:chemically induced / Q000188:drug therapy / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D013662:Tea; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology
D002273:Carcinogens; D013662:Tea; D002085:Butylhydroxybutylnitrosamine; D002392:Catechin