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.

miR-375-3p is a highly expressed microRNA in pancreatic β cells. We have previously reported that when mice were exposed to 7 Gy X-ray irradiation, miR-375-3p was increased in the serum and there was cytotoxicity in pancreatic β cells. However, it was unknown whether miR-375-3p is then released from injured pancreatic β cells to the extracellular space. The present study investigated the effect of ionizing radiation and streptozotocin (STZ) treatment on the expression of extracellular miR-375-3p into culture supernatants using the rat pancreatic β cell line RIN-5F. Cell growth was reduced, and cell death was increased at 24 h following exposure to 7 Gy irradiation as well as 24 h following treatment with 30 mM STZ compared with the control. Expression levels of miR-375-3p were significantly increased 24 h after 30 mM STZ treatment, yet this was only observed at 48 h following exposure to 7 Gy compared with the control. This suggests that the mechanism of cell death in RIN-5F is different between 7 Gy irradiation and 30 mM STZ treatment. The results of the present study suggest that injured pancreatic β cells enhance the release of miR-375-3p from cells into extracellular space.