Effect of X-ray irradiation on pepsinogen and on induction of intestinal-type crypts in the pyloric mucosa of the Wistar rat stomach.

The effects of X-ray irradiation on the content and isozyme pattern of pepsinogen and on the induction of intestinal-type crypts in the pyloric mucosa of rat stomach were compared with the previously reported effects of chemical carcinogens, N-methyl-N'-nitro-N-nitrosoguanidine, N-ethyl-N'-nitro-N-nitrosoguanidine and N-propyl-N'-nitro-N-nitrosoguanidine. The gastric regions of 6-week-old male Wistar rats were irradiated with X-rays (1,000 rad) twice at an interval of 3 days. A decrease in pepsinogen content in the pyloric mucosa was observed between 2 and 52 weeks after the irradiation, as had been found in the previous experiments using chemical stomach carcinogens. However, in contrast to the latter experiment, in which the isozyme pattern was altered, the pepsinogen isozyme pattern did not change throughout the observation period after irradiation. Morphologically, intestinal-type crypts appeared and increased gradually after irradiation as after the administration of chemical stomach carcinogens. However, Paneth cells were either not observed or only rarely observed in rats treated with carcinogens, whereas they were found in crypts in the stomachs of the irradiated rats.