Inhibition by putrescine of experimental carcinogenesis in rat colon induced by azoxymethane

The effects of putrescine on the incidence and number of colon tumors induced by azoxymethane, and on the labelling index and the activity of ornithine decarboxylase (ODC) in the colon mucosa were investigated in Wistar rats. Rats received 10 weekly injections of 7.4 mg/kg body weight of azoxymethane and i.p. injections of 300 mumol/kg body weight of putrescine every 2 days until the end of the experiment at week 40. This prolonged treatment with putrescine significantly reduced the incidence and number of colon tumors. Administration of putrescine also significantly decreased the labelling index and the ODC activity in the colon mucosa during, but not after, treatment with the carcinogen. These last effects may be related to the action of putrescine in inhibiting the development of colonic tumors.