Anti‐promoting Effect of Nordihydroguaiaretic Acid on N‐Butyl‐N‐(4‐hydroxybutyl)nitrosamine and Sodium Saccharin‐induced Rat Urinary Bladder Carcinogenesis

The effects of oral administration of nordihydroguaiaretic acid (NDGA), an antioxidant and inhibitor of arachidonic acid metabolism, on rat bladder carcinogenesis were examined. Six‐week‐old male Fischer 344 rats were given drinking watar containing 0.05% N‐butyl‐N‐(4‐hydroxybutyl)nitrosamine for 4 weeks. Following this 4‐week period, diet containing 5% sodium saccharin (SS) with or without 0.1% NDGA supplement was given to the rats for 36 weeks. The incidences of papillary or nodular (PN) hyperplasia and of papilloma in the group treated with SS plus NDGA were significantly lower than those in the group treated with SS alone. The number of PN hyperplasic foci per 10 cm of basement membrane in rats treated with SS plus NDGA was also lower than that in the group treated with SS alone. These results suggest that NDGA has an anti‐tumor‐promoting effect on rat bladder carcinogenesis.