| Project/Area Number |
16K19876
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Radiation science
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| Research Institution | National Institutes for Quantum and Radiological Science and Technology |
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Principal Investigator |
Takabatake Masaru 国立研究開発法人量子科学技術研究開発機構, 放射線医学総合研究所 放射線影響研究部, 博士研究員(任常) (30756044)
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| Project Period (FY) |
2016-04-01 – 2018-03-31
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| Project Status |
Completed (Fiscal Year 2017)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2017: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2016: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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| Keywords | 放射線 / 乳がん / ラット / 妊娠・出産 / 被ばく時年齢 |
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| Outline of Final Research Achievements |
The present study investigated whether parity imposes differential protective effects against radiation-induced rat mammary carcinoma (MC) depending on the age at exposure. Pre- and post-pubertal female rats, irradiated (gamma, 4 Gy) or left unirradiated, were mated and allowed to nurse until weaning or left unmated. Appearance of MC was monitored, and serum levels of estradiol (E2) and progesterone (P4) were measured after weaning. MCs were evaluated by immunohistochemistry for ER, PR, and Ki-67. Parity reduced the risk of MC in unirradiated and pre-pubertally irradiated rats but not post-pubertally irradiated rats. Although radiation exposure increased serum P4 level, parity after pre-pubertal exposure significantly decreased the elevated P4 to a normal level. Moreover, parity significantly decreased the proportion of hormone receptor positive MCs after pre-pubertal exposure. Parity was also related to the observed positive association between PR and Ki-67 indices in cancer tissue.
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