EFFECTS OF LOW-DOSE X-RAY-IRRADIATION ON BIOMEMBRANE IN BRAIN CORTEX OF AGED RATS

We previously found that low-dose X-ray irradiation or radon (weak alp ha-ray) inhalation increases SOD activities and reduces lipid peroxide levels in various organs of 7-week-old rats or rabbits. In this study , we examined how the changes of SOD activity, lipid peroxide level, a nd membrane fluidity of the cerebral cortex in aged male Wistar rats ( 65 and 91 weeks old) were affected by low-dose X-ray irradiation (100 cGy or under) compared with those in 7-week-old rats, to elucidate the mechanism of aging inhibition. The following results were obtained: A lthough radiation sensitivity was observed to decreases with age, low- dose irradiation changed the Mn-SOD activity, lipid peroxide level, an d membrane protein fluidity parameter of the cerebral cortex in the ag ed rats to be closer to those in the youth. These findings suggest tha t the increased SOD activity induced by low-dose irradiation enhances biomembrane functions, and that the decrease of lipid peroxide level e nhances the membrane protein fluidity.