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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Existence of adaptive response (AR) was previously demonstrated in C57BL/6J mice. Irradiations were
performed by delivering a priming low dose of X-rays (0.50 Gy) in combination with a challenge high dose
of accelerated carbon or neon ion particles. AR was characterized by significantly decreased mortality in
the 30-day survival test. This mouse AR model (Yonezawa Effect) was originally established by using X-rays
as both the priming and challenge irradiations. The underlying mechanism was due to radio-resistance oc-
curring in blood-forming tissues. In this study, we verified the existence of AR and further investigated re-
sidual damage in the hematopoietic system in surviving animals. Results showed that the priming low dose
of X-rays could relieve the detrimental effects on the hematopoietic system. We observed both an improve-
ment in the blood platelet count and the ratio of polychromatic erythrocytes (PCEs) to the sum of PCEs and
normochromatic erythrocytes (NCEs) and a marked reduction of the incidences of micronucleated PCEs
and micronucleated NCEs. These findings suggest that the priming low dose of low linear energy transfer
(LET) X-rays induced a protective effect on the hematopoietic system, which may play an important role in
both rescue from acute lethal damage (mouse killing) and prevention of late detrimental consequences (re-
sidual anhematopoiesis and delayed genotoxic effects) caused by exposure to a high challenge dose from
low-LET (X-ray) or high-LET (carbon and neon ion) irradiations. These findings provide new knowledge
of the characterization of the Yonezawa Effect by providing new insight into the mechanistic study of AR
in vivo.
Relieved residual damage in the hematopoietic system of mice rescued by radiation-induced adaptive response (Yonezawa Effect)
