Abdel-Aziz Nahed, Haroun Riham A-H, Mohamed Hebatallah E
Department of Radiation Biology, National Centre for Radiation Research and Technology (NCRRT), Egyptian Atomic Energy Authority, Cairo, Egypt.
Department of Biochemistry, Faculty of Science, Ain Shams University, Cairo, Egypt.
Dose Response. 2022 Apr 14;20(2):15593258221092365. doi: 10.1177/15593258221092365. eCollection 2022 Apr-Jun.
This work aims to investigate whether the pre-exposure to low dose/low dose rate (40 mGy, 2.2 mGy/hour) γ-radiation as a priming dose can produce a protective effect against the subsequent high one (4 Gy, .425 Gy/minute).
Rats were divided into Group I (control), Group II (L); exposed to 40 mGy, Group III (H); exposed to 4 Gy, and Group IV (L+H); exposed to 40 mGy 24 hours before the exposure to 4Gy. The molecular and biochemical changes related to oxidative stress, DNA damage, apoptosis, and mitochondrial activity in the liver and testis were studied 4 hours after irradiation.
Exposure to 40 mGy before 4 Gy induced a significant increase in the levels of Nrf2, Nrf2 mRNA, TAC, and mitochondrial complexes I & II accompanied by a significant decrease in the levels of LPO, 8-OHdG, DNA fragmentation, TNF-α, caspase-3, and caspase-3 mRNA compared with H group.
Exposure to low-dose γ-radiation before a high dose provides protective mechanisms that allow the body to survive better after exposure to a subsequent high one via reducing the oxidative stress, DNA damage, and apoptosis-induced early after irradiation. However, further studies are required to identify the long-term effects of this low dose.
本研究旨在探讨低剂量/低剂量率（40毫戈瑞，2.2毫戈瑞/小时）γ射线预照射作为启动剂量是否能对后续高剂量（4戈瑞，0.425戈瑞/分钟）照射产生保护作用。
将大鼠分为I组（对照组）、II组（L组），接受40毫戈瑞照射、III组（H组），接受4戈瑞照射，以及IV组（L+H组），在接受4戈瑞照射前24小时接受40毫戈瑞照射。在照射后4小时研究肝脏和睾丸中与氧化应激、DNA损伤、细胞凋亡及线粒体活性相关的分子和生化变化。
与H组相比，4戈瑞照射前接受40毫戈瑞照射可导致Nrf2、Nrf2 mRNA、总抗氧化能力（TAC）以及线粒体复合物I和II水平显著升高，同时丙二醛（LPO）、8-羟基脱氧鸟苷（8-OHdG）、DNA片段化、肿瘤坏死因子-α（TNF-α）、半胱天冬酶-3（caspase-3）及caspase-3 mRNA水平显著降低。
高剂量照射前接受低剂量γ射线照射可提供保护机制，使机体在后续接受高剂量照射后能通过减轻照射后早期产生的氧化应激、DNA损伤和细胞凋亡而更好地存活。然而，需要进一步研究来确定这种低剂量照射的长期影响。
