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 present study, 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 rats were divided into MNNG-treated and non-treated groups, observed on gastric endoscopy every 5 weeks, and sacrificed at week 10, 25, 35, and 50. The sequential growth process of MNNG-induced gastric tumor was clearly found by the endoscopic examination. Endoscopic appearances including incidence and size of tumor were well consistent with histological findings. In addition, biopsy specimens could be extracted from gastric mucosa in living rats using a biopsy forceps. These results indicate that the endoscopic technique can be a useful tool for investigating gastric carcinogenesis by sequential observation and collection of biopsy specimens.