Effects of carbon-ion microbeam irradiation on locomotion and pharyngeal pumping in

炭素イオンマイクロビーム照射がの全身運動と咽頭ポンピング運動に及ぼす影響

鈴木 芳代; 服部 佑哉; 坂下 哲哉; 舟山 知夫; 横田 裕一郎; 池田 裕子; 小林 泰彦

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

We recently reported that locomotion in the nematode significantly decreased after broad-beam irradiation of the whole body. In addition, the proportion of animals in which pharyngeal pumping motion (chewing and swallowing) had stopped increased after broad-beam irradiation. In the present study, we examined whether or not the effects similar to those observed in the broad-beam irradiated could be induced by region-specific microbeam irradiation. We used energetic carbon ions generated at the HZ1 port of TIARA at JAEA. The "head" region including the pharynx, "middle" region around the intestine, and "tail" region were irradiated independently with 12,000 carbon ions corresponding to 500 Gy at a 20 m micro-aperture region. Microbeam irradiation in each region slightly decreased locomotion, and there were no significant differences in the degrees of the decrease between the irradiation regions. This may relate to the fact that the neural circuit for motor control of whole-body movement exists from the head to the tail. On the other hand, the proportion of animals in which the pumping motion had stopped increased in only the head-irradiated animals. These findings suggested that the stop of the pharyngeal pumping motion after whole-body irradiation reflects radiation effects on the head (including the pharynx).