:A Chronological Study

概要

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Experimental MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) carcinogenesis was studied, chronologically, on the glandular stomach of Wistar rats. In male rats, the hypertrophy of lamina muscularis mucosae (l.m.m.) was frequently observed at the 4th month of the experiment when cancer and mucosal atypia were found less frequently. And the incidence of the hypertrophy of l.m.m. decreased with time after the MNNG treatment, while the incidence of cancer and mucosal atypia increased. In female rats, the hypertrophy of l.m.m., cancer and mucosal atypia were very low in their incidence throughout the observation period (4 to 12 months). When estradiol was injected to male rats, the incidence of gastric cancer became lower than that of intact males. When castration was performed on male and female rats, the incidence of gastric cancer of castrated male rats became markedly lower than that of non-castrated males, while gastric cancers were scarcely observed either in castrated females or in non-castrated females.These findings, therefore, suggest that female sex hormones exert a suppressive action on carcinogenesis, while male sex hormones facilitate carcinogenesis.
財団法人日本消化器病学会の論文