Abstract
We have demonstrated that low dose-rate irradiation at around 1 mGy/hr suppressed the incidence of methylcholanthrene-induced skin tumor and radiation-induced thymic lymphoma in mice. We also found some of bio-protective functions, including anti-oxidative capacity and immune functions, were enhanced. To examine the possibility that the enhanced protective capacity may have some other effects in addition to the tumor suppression, we investigated the effects of low dose irradiation on disease model mice. In Type II diabetic C57BL/KsJ-db/db (db) mice the urine glucose level was improved in some of the mice irradiated at 0.70 mGy/hr, but not in non-irradiated control mice. In severe autoimmune MRL-lpr/lpr (lpr) mice immunological status was kept better in the mice irradiated at 0.35 or 1.2 mGy/hr. The incidence of a number of symptoms, including lymphadenopathy and proteinuria, was suppressed by the irradiation. For both of the strains, furthermore, the low dose-rate irradiation prolonged the life span of the irradiated mice.The studies on db mice and lpr mice were done by Takaharu Nomura and Yasuhiro Ina in our Research Center, respectively. [J Radiat Res 44:376-377 (2003)]
