DIFFERENTIAL SUSCEPTIBILITY OF FOUR RAT STRAINS TO INDUCTION OF LARGE-BOWEL NEOPLASMA BY 1, 2-DIMETHYL-HYDRAZINE

Abstract

Four strain rat, Fischer, Fonryu, Sprague-Dawley and Wistar, were treated with 1, 2-dimethylhydrazine (DMH) 20mg/kg/week, serially five weeks. Donryu rat was most susceptible in induction of colorectal neoplasms, whereas Wistar rat was most resistant among the four strains.
Concerning to the distribution of induced tumor, cancer in the Sprague-Dawley rat was induced more often in the distal colon. It can be said that it is better to chose appropriate rat strain according to the purpose of each experiment.
One sessile polypoid lesion showed histologically focal severe dysplasia, and this finding seems to suggest that adenoma can be the precursor of colorectal cancer also in experiment.