Protective mechanism of a novel aminothiol compound on radiation-induced intestinal injury.

Purpose: With the development of nuclear technology and radiotherapy, the risk of radiation injury has been increasing. Therefore, it is important to find an effective radiation-protective agent. In this study, we designed and synthesized a novel compound called compound 8, of which the radioprotective effect and mechanism were studied.

Materials and methods: Before being exposed to ionizing radiation, mice were pretreated with compound 8. The 30-day mortality assay, hematoxylin-eosin staining, and immunohistochemistry staining assay were performed to evaluate the anti-radiation effect of the compound 8. TUNEL and immunofluorescence assays were conducted to study the anti-radiation mechanism of compound 8.

Results: Compared to the IR + vehicle group, the 30-day survival rate of mice treated with 25 mg/kg of compound 8 was significantly improved after 8 Gy total body irradiation. In the morphological study of the small intestine, we found that compound 8 could maintain crypt-villus structures in the irradiated mice. Further immunohistochemical staining displayed that compound 8 could improve the survival of Lgr5⁺ cells, ki67⁺ cells, and lysozyme⁺ cells. The results of TUNEL and immunofluorescence assays showed that compound 8 could decrease the expression of apoptosis-related caspase-8/-9, γ-H2AX, Bax, and p53.

Conclusions: These results indicate that compound 8 exerts its effects by maintaining structure and function of small intestine. It also reduces DNA damage, promotes crypt proliferation and differentiation. Moreover, it may enhance the anti-apoptotic ability of small intestinal tissue by inhibiting the activation of p53 and blocking the caspase cascade reaction. Compound 8 can protect the intestinal tract from post-radiation damage, it is thus a new and effective protective agent of radiation.