Effect of cholic acid on tumor in the Egyptian toad

Egyptian toads, Bufo regularis, were fed with cholic acid (sodium salt) 3 times/week for 12 weeks at different dose levels (2.5, 5, and 10 mg/toad). Results obtained showed only 1 case in both the 5 and 10 mg/toad doses that gave a tumor. Toads receiving N-methyl-N-nitrosourea (MNU) 1 mg/toad, 3 times/week for 12 weeks had 36% ileum tumors (18 toads out of 50, without mortality). On the other hand, a higher dose of MNU (5 mg/toad) caused 50% mortality in the experimental animals. Toads treated with MNU at a dose level of 1 mg/toad were subjected to CA at dose levels of 2.5, 5, 10 mg/toad. They showed a 48, 66 and 76% higher incidence of ileum tumors at the three different dose levels, respectively. It is concluded that cholic acid has a promoting effect on ileum tumor evoked by MNU in toads as in mammals.