Adaptive Response Induced By Low Dose Microwave On Genetic Damages Of Mice Caused By γ-rays

Objective：To explore the adaptive response induced by low dose microwave on γ-rays-causedgenetic damages in mice.Methods:1. Adult male ICR mice were pre-exposed to900MHz radiofrequency radiationat120μW/cm2power density for4hours/day for1,3,5,7and14days and thensubjected to an acute dose of3Gy γ-radiation. The primary DNA damage in the form ofalkali labile base damage and single strand breaks in the DNA of peripheral bloodleukocytes was determined using the alkaline comet assay.2. Adult male ICR mice were pre-exposed to non-ionizing radiofrequency fields,900MHz at120μW/cm2power density for4h/day for7days and then subjected to anacute whole body dose of3Gy γ-radiation. The classical micronucleus assay was usedto determine the extent of genotoxicity in immature erythrocytes in peripheral blood andbone marrow.3. Adult male ICR mice were pre-exposed to non-ionizing radiofrequency fields,900MHz at120μW/cm2power density for4h/day for7days and then subjected to anacute whole body dose of3Gy γ-radiation. DCFH-DA was used to study the content ofreactive oxygen species. The vitality unite of superoxide dismutase was measured withtotal superoxide dismutase assay Kit.Results:1. The results of alkaline comet assay indicated that the extent of damage in micewhich were pre-exposed to radiofrequency radiation for1day and then subjected toγ-radiation was not significantly different from those exposed to γ-radiation alone.However, mice which were pre-exposed to RF for3,5,7and14days showed progressively decreased damage and was significantly different from those exposed toγ-radiation alone. Thus, the data indicated that radiofrequency radiation pre-exposure iscapable of inducing adaptive response and suggested that the pre-exposure for morethan4hours for1day is necessary to elicit such adaptive response.2. The results of micronucleus assay indicated that in both blood and bonemarrow, the MN indices were similar in un-exposed controls and those exposed toradiofrequency fields alone, a significantly increased MN frequency was observed inmice exposed to γ-rays alone. Exposure of mice to radiofrequency+γ-rays resulted in asignificant decrease in MN indices compared to those exposed to γ-rays alone.3. Compared with control group，levels of reactive oxygen species increased inmice exposed to γ-rays alone and exposed to radiofrequency fields alone, There was asignificantly decrease of reactive oxygen species in radiofrequency+γ-rays comparedto γ-rays alone. The vitality unite of superoxide dismutase increased in radiofrequency+γ-rays compared to γ-rays alone, compared to control group. The vitality unites ofsuperoxide dismutase decreased in mice exposed to γ-rays alone and exposed toradiofrequency fields alone.Conclusions：1. Pre-exposure with120μW/cm2low dose microwave could induce adaptiveresponse on DNA damage caused by γ-rays in mice.2. Pre-exposure with120μW/cm2low dose microwave could induce adaptiveresponse, capable of protecting cells in blood and bone marrow from genotoxic effectsof subsequent γ-radiation.3. Oxidative stress may be involved in the underlying mechanism of adaptiveresponse induced by low dose microwave radiation.