Hirobe Tomohisa, Eguchi-Kasai Kiyomi, Murakami Masahiro
Radiation Hazards Research Group, National Institute of Radiological Sciences, Anagawa, Inage-ku, Chiba, Japan.
Radiat Res. 2004 Nov;162(5):580-4. doi: 10.1667/rr3248.
Pregnant female C57BL/10JHir mice were irradiated whole-body at 9 days of gestation with a single acute dose of carbon-ion radiation. The average linear energy transfer (LET) of the carbon ions was 50 keV/microm within a spread-out Bragg peak (SOBP). The effects were studied by scoring changes in the postnatal development of the mice as well as in the pigmentation of the cutaneous coats and tail tips of their offspring 22 days after birth. The percentage of live births was reduced in mice exposed to carbon ions at doses greater than 0.5 Gy. The survival to day 22 was also reduced in mice exposed to carbon ions at doses greater than 0.75 Gy. Moreover, the body weight at day 22 was reduced in mice exposed to carbon ions at doses greater than 0.1 Gy. A comparison of the survival to day 22 after exposure to carbon ions with our previous results for 60Co gamma rays indicated that carbon ions were twice as effective as gamma rays. White spots were found in the mid-ventrum as well as in the tail tips of offspring exposed to carbon ions in utero. The frequency and the size of the white spots in the mid-ventrum and in the tail tips increased as the dose increased. Carbon ions appear to be slightly more effective than the gamma rays used in our previous study. In the ventral white spots, no melanocytes were observed in the epidermis, dermis and hair follicles. These results indicate that prenatal exposure to carbon ions has a greater effect on the postnatal development and survival of mice than does exposure to gamma rays, and that the relative biological effectiveness is greater than that for effects on melanocyte development.
怀孕的雌性C57BL/10JHir小鼠在妊娠第9天接受单次急性剂量的碳离子全身照射。在扩展布拉格峰（SOBP）内，碳离子的平均线能量转移（LET）为50 keV/微米。通过对小鼠出生后发育变化以及出生22天后其后代皮肤和尾尖色素沉着的变化进行评分来研究其影响。暴露于大于0.5 Gy碳离子的小鼠活产百分比降低。暴露于大于0.75 Gy碳离子的小鼠到第22天的存活率也降低。此外，暴露于大于0.1 Gy碳离子的小鼠在第22天的体重降低。将暴露于碳离子后到第22天的存活率与我们之前60Coγ射线的结果进行比较表明，碳离子的效果是γ射线的两倍。在子宫内暴露于碳离子的后代的腹中部以及尾尖发现了白斑。腹中部和尾尖白斑的频率和大小随着剂量增加而增加。碳离子似乎比我们之前研究中使用的γ射线略有效。在腹侧白斑中，在表皮、真皮和毛囊中未观察到黑素细胞。这些结果表明，产前暴露于碳离子对小鼠出生后的发育和存活的影响比暴露于γ射线更大，并且相对生物效能大于对黑素细胞发育的影响。
