Blood mtDNA Copy Number as a Potential Indicator of X-ray Radiation Exposure in Animals

Abstract

The dangerous effects of ionizing radiation on living organisms are a key problem for many countries, 
including Kazakhstan. The relevance of the study is due to the fact that in some regions of Kazakhstan, there is an 
increased level of background radiation, primarily associated with rich uranium deposits, as well as the presence of 
long-lived radioactive isotopes on the territory of the former Semipalatinsk nuclear test site. Moreover, occupational 
exposure to medical radiation may result in major consequences to human health. Since physical dosimeters have 
limitations in accurately assessing the extent of individual damage, one of the main tasks in radiobiology is the search 
for biomarkers of individual radioresistance. The aim of the study was to investigate the impact of ionizing radiation 
(X-ray) on the level of free circulating mitochondrial DNA. Blood plasma samples were collected from experimental 
rats following exposure to X-ray radiation. Quantitative real-time polymerase chain reaction was used to detect the 
copy number of mitochondrial DNA. On average, the copy number of free-circulating mitochondrial DNA in the 
blood plasma of irradiated rats (4.51x107copies/mL) was 2.7 times higher compared to the control group 
(1.67x107copies/mL). The obtained results indicate the potential role of free-circulating mitochondrial DNA as a 
biomarker for assessing X-ray exposure.