Effects of region-specific microbeam irradiation on locomotion and pharyngeal pumping motion in

Suzuki, Michiyo; Hattori, Yuya; Sakashita, Tetsuya; Funayama, Tomoo; Yokota, Yuichiro; Kobayashi, Yasuhiko

Using , we recently investigated the radiation effects, and found that whole-body irradiation significantly reduced locomotion. Furthermore, we found that the proportion of pumping-motion arrest increased after whole-body irradiation. As the next step, we aimed to examine whether or not the effects observed after whole-body irradiation could be induced by region-specific microbeam irradiation. To investigate the effects of region-specific microbeam irradiation, we used energetic carbon ions generated at TIARA (JAEA-Takasaki). To inhibit free motion during irradiation an animal was enclosed in a ditch of a polydimethylsiloxane device with buffer solution. The "head" region, "middle" region, and "tail" region were targeted independently; these regions were irradiated with 12,000 carbon ions. Microbeam irradiation in each region did not decrease locomotion. On the other hand, the proportion of pumping-motion arrest increased only in the head-irradiated animals, suggesting that an increase of the proportion of pumping-motion arrest after whole-body irradiation reflects radiation effects on the head region. Main findings in this study are the following: (1) effects of the region-specific microbeam irradiation differ depending on types of motion, and (2) effects of whole-body irradiation tend to be more effective than those of the region-specific microbeam irradiation at the same irradiation dose.