Transcriptomic Response in the Spleen after Whole-Body Low-Dose X-Ray Irradiation

As the use of medical radiation procedures continues to rise, it is imperative to further our understanding of the effects of this exposure. The spleen is not known as a particularly radiosensitive organ, although its tolerance to radiation is not well understood. Low-dose radiation exposure has been implicated in beneficial responses, particularly in cell death and DNA damage repair. In this study, adult male rats received 2, 20, 200 mGy or 4 Gy whole-body X-ray irradiation and the transcriptional response in the spleen was analyzed at 0.5, 4 and 24 h postirradiation. We analyzed expression of genes involved in apoptosis, cell cycle progression and DNA damage repair. As expected, 4 Gy irradiated animals demonstrated elevated expression of genes related to apoptosis at 0.5, 4 and 24 h postirradiation in the spleen. These animals also showed upregulation of DNA damage repair genes at 24 h postirradiation. Interestingly, the spleens of 20 mGy irradiated animals showed reduced apoptosis and cell cycle arrest compared to the spleens of sham-irradiated animals. These results further reveal that the cellular response in the spleen to whole-body irradiation differs between low- and high-dose irradiation.