COMBINED EXPOSURE TO HALOTHANE AND 1 OR 2 Gy IONIZING RADIATION CAUSES A SYNERGISTIC EFFECT IN DNA DAMAGE IN THE BLOOD AND LIVER OF SWISS ALBINO MICE

Patient immobilization by general volatile anesthesia (VA) during medical radiology treatment is sometimes necessary and annual trends are increasing. Ionizing radiation (IR) exposure is known to cause some level of DNA damage since IR is a well-known genotoxic and cytotoxic agent, although the doses used are kept to a minimum, with good localization in order to protect as much healthy tissue and organs as possible from exposure. Recently, a growing number of studies have demonstrated that volatile anesthetics can also cause DNA damage effects in patients, and in occupationally exposed personnel. Since there are no studies on the combined effects of IR and VA, we decided to use an animal model of Swiss albino mice to determine whether there are elevated levels of DNA damage after combined exposure by mimicking real conditions of exposure during radiology treatment. Healthy male mice (5 animals per group) were anaesthetized by inhaling 2.4% halothane for 2 hours and then were exposed to either 1 or 2 Gy of ionizing radiation (60Co source). Groups were examined immediately after exposure, and again after 2, 6 and 24 hours. Blood was taken from the tail, and liver after animal sacrifice. The study was approved by the Ethics Committee of the Faculty of Science, University of Zagreb, Croatia, and designed in accordance with the relevant Croatian guidelines (Animal Protection Act, Ordinance on the protection of animals used for scientific purposes). Duplicate samples were prepared for the alkaline comet assay, and DNA damage of a total of 200 comets per point was assessed with Comet Assay IV software. The results demonstrated that both halothane and IR caused elevated DNA damage levels, and when applied in combined treatment caused synergistic effect additional damaging effect that was not repaired even 24 hours after exposure. These data confirm concerns about the safety of combined VA and IR exposure, and indicate the need for further investigation on the safety and proper use of the type of anesthetic needed during radiotherapy.