56Fe ion irradiation induced apoptosis through Nrf2 pathway in mouse testis

The phenomenon has raised the concerns about the safety of an extended manned mission into deep space due to the high potential for exposure to high-LET radiation during space missions. Heavy ions such as 56Fe are main radiation sources in deep space, which could pose a significant hazard to space flight crews during and after missions. Since the testis is a radiosensitive organ, which may be susceptible to space radiation-induced changes. In this study, we investigated the effect and potential mechanisms of 56Fe irradiation on mouse testis. Pathological characteristics were measured following whole-body irradiation with 0.5 and 1 Gy 56Fe irradiation. Flow cytometry and terminal dUTP nick end-labeling (TUNEL) were performed to detect apoptotic cells. Western blot was applied to identify potential biomarkers. Immunofluorescence was used to investigate protein localization. We found that pathologic changes and apoptosis cells were significantly higher in 1 Gy group than those in 0 Gy groups. In addition, protein expression and localization studies confirmed Nrf2 was involved in this acute injury. Nrf2 and its target genes HO-1 and NQO1 were up-regulated in the irradiated testis in a dose-dependent manner. Nrf2 may be useful molecular markers in radiation-induced cellular responses and is important for detecting abnormal spermatogenesis following exposure to space radiation.