Abstract
Damage to gastrointestinal (GI) system is one of major problems in exposure to high dose radiation. However, treatment of the GI injuries and its mechanisms are poorly understood, since an in vitro experimental system of GI injury is not established. There are many cell lines derived from intestinal epithelial tissues, but most of these cell lines are transformed and acquired radioresistance. Using the primary culture system of GI epithelial cells from fetal rats (Fukamachi, H., 1992), we studied a mechanism of GI injury caused by radiation. Epithelial cells from forestomach (FS), glandular stomach (GS), and duodenum (D) were obtained from 17.5-day rat fetuses and cultured for three days. The numbers of these cells increased by 5-fold on Day 3. These cells were irradiated with 10 Gy of X-ray on Day 1 (24 hr after spread). Hoechst staining showed that irradiation induced apoptosis in all three kinds of epithelial cells within 24 hr postradiation. On the other hand, the apoptotic indexes varied among these cells; indexes were 5% and 15% in GS, and FS and D epithelial cells, respectively. When irradiated on Day 3, apoptosis was observed in FS and D epithelial cells but not in GS. When D epithelial cells were irradiated at various doses, the apoptotic index increased in a dose-dependent manner, and reached about 20% at 20 Gy. We conclude that this culture system is helpful for analysis of a mechanism for GI injury by irradiation. Further investigation on the different radiosensitivity among three epithelial cells is now in progress.
