Effect of Different Doses of Radiation on Intestinal Injury in NOD/SCID Mice.

Objective To study the effect of different doses of radiation on intestinal injury,with an attempt to find the optimal radiation dose for establishing intestinal injury models in NOD/SCID mice. Methods Forty healthy male SPF-grade NOD/SCID mice were divided randomly into four groups:blank control group and 4-,5-,6-Gy irradiatio groups,with 10 mice in each group. The irradiation rate was 1 Gy/min. The general conditions,body weight,intestinal bacterial translocation,and histopathologic changes were observed and compared. Results The survival rate was 60%,50%,and 30% in the 4-,5-,and 6-Gy groups 15 days after irradiation,and the intestinal bacterial translocation rate was 20%,50%,and 70%,respectively. The body weights in 5-Gy group (P=0.015) and 6-Gy group (P=0.011) were significantly higher than that in blank control group. The length of small intestinal villi decreased in the 4-Gy group. In the 5-Gy group,the structure of intestinal mucosa villi became wide,flat,and inverted,along with the shedding of epithelial cells,the atrophy of glands,and the damage of recess structures. In the 6-Gy group,the structure of intestinal mucosal villi was damaged,the villi were ruptured and smashed,and the recess structures were missing;meanwhile,there was a large amount of inflammatory cell infiltration between tissues,along with visible spotty bleeding and necrosis. The length of small intestine villi in the blank control group and 4-,5-,and 6-Gy groups were (361.77±22.77),(291.68±32.45),(248.03±51.09),and (195.90±26.39) μm,respectively. In particular,it was significantly shorter in 4-Gy group (P=0.005),5-Gy group (P<0.001),and 6-Gy (P<0.001) than in the blank control group,was significantly shorter in the 5-Gy group (P=0.041) and 6-Gy group (P=0.001) than in the 4-Gy group,and significantly shorter in 6-Gy group than in the 5-Gy group (P=0.020). Conclusion 5-Gy irradiation in mice models can decrease body weight,cause the damage of intestinal mucosa and the shedding of inflammatory cells,with stable survival rate and bacterial translocation rate.