EFFECTS OF SEX-HORMONES ON INDUCTION OF INTESTINAL METAPLASIA BY X-IRRADIATION IN RATS

The influence of sex hormones on induction of intestinal metaplasia was examined in 5 week old Crj: CD (SD) rats of both sexes. At the age of 4 weeks, the animals were gonadectomized and given testosterone or dimethyl estradiol (DES). One week after operation, they were irradiated with two 1 0 Gy doses of X-rays to the gastric region at a 3 day interval for a total of 20 Gy. At the termination of the experiment, 6 months after the X-irradiation, the incidence of intestinal metaplasia with alkaline phosphatase (ALP) positive foci in males was significantly higher than in females, in orchidectomized males or orchidectomized plus DES treated rats (P < 0.01). On the other hand, the incidence of intestinal metaplasia with ALP-positive foci in normal females appeared lower than in ovariectomized females (P < 0.01), and was increased in rats by treatment with testosterone or decreased by DES. Numbers of foci of intestinal metaplasias with Paneth cells and total numbers appeared to increase in males treated with DES. The results suggested a promoting role for testosterone in the development of ALP positive lesions and indicated considerable heterogeneity between intestinal metaplasia subtypes.