Strain differences in the induction of intestinal metaplasia by X-irradiation in rats.

Strain differences in the susceptibility of rats to induction of intestinal metaplasia by X-irradiation were examined. The gastric regions of 5-week-old males of five inbred strains of rats (F344/NSlc, Copenhagen, Buffalo/NacJcl, and ACI/NHos) and three strains of randomly bred rats (HOS:Donryu, Slc:Wistar, Slc:SD) were irradiated with a total dose of 20 Gy X-ray given in two equal fractions at 3-day interrals. When examined after the rats were killed, 6 months after the last irradiation, the number of intestinal metaplastic crypts positive for alkaline phosphatase (ALP) was highest in the Donryu and lowest in the Copenhagen rats. Morphologically, the number of crypts with intestinal metaplasia in the glandular stomachs of Donryu, Wistar, SD, and Buffalo rats was higher than the number in ACI, F344, and Copenhagen rats. Intestinal metaplasia was more frequently observed in the pyloric than in the fundic glands. These results demonstrate that the induction of intestinal metaplasia by X-irradiation in rats is greatly influenced by the rat strain.