Similarity between the effects of carbon-ion irradiation and X-irradiation on the development of rat brain.
The effects of carbon-ion irradiation and X-irradiation on the development of rat brain were compared. Twenty pregnant rats were injected with bromodeoxyuridine (BrdU) at 9 pm on day 18 of pregnancy and divided into five groups. Three hours after injection (day 19.0) one group was exposed to 290 MeV/u carbon-ion radiation by a single dose of 1.5 Gy. Other groups were exposed to X-radiation by 1.5, 2.0 or 2.5 Gy, or sham-treated, respectively. Fetuses were removed from one dam in each group 8 h after exposure and examined histologically. Extensive cell death was observed in the brain mantle from the irradiated groups. The cell death after 1.5 Gy carbon-ion irradiation was remarkably more extensive than that after 1.5 Gy X-irradiation, but comparable to that after 2.0 Gy or 2.5 Gy X-irradiation. The remaining rats were allowed to give birth and the offspring were sacrificed at 6 weeks of age. All of the irradiated offspring manifested microcephaly. The size of the brain mantle exposed to 1.5 Gy carbon-ion radiation was significantly smaller than that exposed to 1.5 Gy X-radiation and larger than that exposed to 2.5 Gy X-radiation. A histological examination of the cerebral cortex revealed that cortical layers II-IV were malformed. The defect by 1.5 Gy carbon-ion irradiation was more severe than that by the same dose of X-irradiation. Although the BrdU-incorporated neurons were greatly reduced in number in all irradiated groups, these cells reached the superficial area of the cortex. These findings indicated that the effects of both carbon-ion irradiation and X-irradiation on the development of rat brain are similar in character, and the effect of 1.5 Gy carbon-ion irradiation compares to that of 2.0-2.5 Gy X-irradiation.
Inouye
M
M
Department of Teratology and Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan. inouye@riem.nagoya-u.ac.jp
Takahashi
S
S
Kubota
Y
Y
Hayasaka
S
S
Murata
Y
Y
D000818:Animals; D001921:Brain / Q000196:embryology* / Q000528:radiation effects*; D002250:Carbon Radioisotopes; D005314:Embryonic and Fetal Development / Q000528:radiation effects; D005260:Female; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D014965:X-Rays
D002250:Carbon Radioisotopes