Low-Dose Radiation Exposure and Protection Against Atherosclerosis in ApoE–/– Mice: The Influence of P53 Heterozygosity

We recently described the effects of low-dose γ-radiation exposures on atherosclerosis in genetically susceptible (ApoE–/–) mice with normal p53 function. Doses as low as 25 mGy, given at either early or late stage disease, generally protected against atherosclerosis in a manner distinctly nonlinear with dose. We now report the influence of low doses (25–500 mGy) on atherosclerosis in ApoE–/– mice with reduced p53 function (Trp53+/–). Single exposures were given at either low or high dose rate (1 or 150 mGy/min) to female C57BL/6J ApoE–/– Trp53+/– mice. Mice were exposed at either early stage disease (2 months of age) and examined 3 or 6 months later, or at late stage disease (7 months of age) and examined 2 or 4 months later. In unirradiated mice, reduced p53 functionality elevated serum cholesterol and accelerated both aortic root lesion growth and severity in young mice. Radiation exposure to doses as low as 25 mGy at early stage disease, at either the high or the low dose rate, inhibited lesion growth...