Endoscopic Observation of N-Methyl-N ’ Nitro-N-Nitrosoguanidine-Induced Gastric Carcinogenesis in Rat Using A Newly-Developed Flexible Endoscope

Endoscopy can be used for sequential observation of gastric carcinogenesis in animal models. In the presentstudy, we applied endoscopic examination and biopsy technique on N-methyl-N'-nitro-N-nitrosoguanidine(MNNG)-induced stomach cancer in rats using a newly-developed flexible 2.5 mm endoscope. A total of 36 ratswere divided into MNNG-treated and non-treated groups, observed on gastric endoscopy every 5 weeks, andsacrificed at week 10, 25, 35, and 50. The sequential growth process of MNNG-induced gastric tumor wasclearly found by the endoscopic examination. Endoscopic appearances including incidence and size of tumorwere well consistent with histological findings. In addition, biopsy specimens could be extracted from gastricmucosa in living rats using a biopsy forceps. These results indicate that the endoscopic technique can be a usefultool for investigating gastric carcinogenesis by sequential observation and collection of biopsy specimens.