The small intestine is one of the most highly regenerative and radiosensitive tissues in mammals, including humans. Exposure to high doses of ionizing radiation causes serious intestinal damage. Recently, several investigations have been conducted using radioprotective agents to determine ways for reducing intestinal damage caused by radiation exposure. However, a thorough understanding of functional changes occurring in the small intestine of mice exposed to high‑dose radiation is necessary for developing novel and more potent radioprotective agents. In this study, we examined changes in microRNA (miRNA/miR) expressions in the small intestine of mice at 72 h after X‑ray exposure (10 Gy). We identified seven upregulated miRNAs and six downregulated miRNAs in the small intestine of mice following radiation exposure using miRNA microarray analysis. Particularly, miR‑34a‑5p was highly expressed, which was confirmed by reverse transcription-quantitative PCR. Forkhead box P1 (Foxp1) was predicted to be a target of the mRNA of miR‑34a‑5p using OmicsNet. Decreased Foxp1 expression in the small intestine following radiation exposure was confirmed, suggesting that Foxp1 expression recovery may induce the suppression of radiation‑induced enteritis. Therefore, miR‑34a‑5p is a potential target molecule for developing novel radioprotective agents.
Keywords: small intestine; radiation; gene expression; microrna; microrna-34a-5p.