[Short-term assay of colon carcinogen--induction of micronuclei and apoptosis by dimethylhydrazine in the mouse colon crypt cells].

The frequencies of micronuclei and apoptosis in the colon crypt cells of mice treated with colon carcinogen were studied. Two strains of mice, inbred C57BL and close colony Kun-ming mice were used in this experiment. The mice were killed at 24 hr after intraperitoneal injection of dimethylhydrazine (DMH) at doses of 10, 20 and 40 mg/kg body weight. The results indicated that the frequencies of micronuclei and apoptosis in the colon crypt cells of both C57BL and Kun-ming mice were positively correlated quantitatively with the doses of DMH. Our results are similar to that of Heddle obtained in C57BL mice. We propose that the assay of micronuclei and apoptosis in mouse colon crypt cells might be a rapid and sensitive test and useful as a screening method for potential colon carcinogens. Kun-ming mice may be used as the test animal for detecting nuclear anomalies in this assay in lieu of C57BL mice.