量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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Influences of heavy ion particle exposure to mature rats were examined to estimate the risk of space radiation. Female Wistar rats, 12 months old, were divided into four groups. Rats of three groups (each group, n=40) were irradiated to the whole body with heavy ion particle (Carbon 290MeV) at doses of 0.75, 1.0 and 5.0Gy. Rats in other group (n=50) were as the control. Rats were bred in a cage until they died and checked tumors and alterations. Histological examination was performed. Bone mineral density, shape and fragility (strength strain index) of tibia were measured by pQCT and the proximal metaphysis was used for histomorphometry. Femur was for strength by three point bending method. The life span after irradiation in each group were 394 +/- 115 days in the 0.75Gy group, 397 +/- 91days in the 1.0Gy group, and 111 +/- 141days in the 5.0Gy group, significantly (p<0.001) shorter than 509 +/-138 days in the control group. Rats in the 0.75 and 1.0Gy groups began to die after 200 days post irradiation, but about half of animals (58%) in the 5.0 Gy group died 7-15 days and the remain died at 62-424 days after irradiation. The congestion or hemorrhage in the gastric mucous membrane was often observed in the rats died early in the 5Gy group. Tumors in ovaries, uterus, liver, lung, pituitary gland, as well as mammary gland were observed in all groups, but particularly, the incidences of ovary tumor 18.9 % in the 0.75Gy group and 21.2% in the 1.0Gy group were higher than that (10.8%) of control group. Trabecular bone mineral density of proximal metaphysis, and strength index of the diaphysis of tibia in radiation groups did not differ from those of control group. The results indicate that exposure of heavy ion particle radiation to mature rats induces the shortening of life span, high incidence of ovary tumor, but no alteration of bone such as bone mineral loss and fragility.
Influence of Heavy Ion Particle Irradiation in Mature Female Rats: the Life Span and Tumors and Bone Damage
