Does radioadaptive response also apply to the case of heavy-ion irradiations in fetal and adult mice?

Possible induction of adaptive response (AR) by the high LET accelerated heavy ion irradiations (HI) is being attempted both in young adult female mice and in fetal mice of C57BL/6J Jms strain, using growth delay, hematopoietic damage and reduced survival in utero, prenatal growth delay, malformation and death in utero as endpoints. Investigations are to verify if priming dose from low LET X-irradiation could induce an AR against the detrimental effects from the high challenging dose of HI, if priming dose from HI could induce an AR against the high challenging dose from low LET X-irradiations, and if an AR could be induced when both priming and challenging doses are from HI. Three kinds of HI are being examined: carbon, silicon and iron, with the LET values of about 15, 55, and 200 keV/micrometer, respectively. Results show, at whole body level for the first time, that priming dose of low LET X-irradiations could induce AR both in vivo and in utero against the challenging dose from high LET HI, and priming dose from high LET HI could induce AR against the challenging dose from low LET X-irradiations in vivo. The remaining questions that if priming dose from HI could induce an AR against the challenging dose from low LET X-irradiations in ulero, if an AR could be induced both in vivo and in utero when both priming and challenging doses are from HI, and if there is any LET dependency in AR induction at whole body level, are still to be answered by further intensive investigations. (author)