2022 Fiscal Year Final Research Report
Changes in morphology and function of neonatally X-irradiated thyroid gland in rats
| Project/Area Number |
20K08886
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 54040:Metabolism and endocrinology-related
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| Research Institution | Hiroshima University |
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Principal Investigator |
Fujimoto Nariaki 広島大学, 原爆放射線医科学研究所, 准教授 (40243612)
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| Co-Investigator(Kenkyū-buntansha) |
松山 睦美 (松鵜睦美) 長崎大学, 原爆後障害医療研究所, 助教 (00274639)
中島 正洋 長崎大学, 原爆後障害医療研究所, 教授 (50284683)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 小児期甲状腺被曝 |
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| Outline of Final Research Achievements |
Exposure to ionizing radiation in childhood has been recognized as a risk factor for thyroid dysfunction/cancer. Wistar rats were subjected to cervical X-irradiation at different ages of 1-8 weeks old and at different doses of 1.5-12 Gy. For tumor promotion, neonatally X-irradiated rats were fed with an iodine-deficient diet (IDD). In cervically X-irradiated neonatal rats, the colloid size of thyroid follicles decreased, accompanied by an increase in the number of TUNEL-positive cells. Fas and Lgals3 mRNA levels increased, while Mct8 and Lat4 expressions decreased. The co-administration of IDD resulted in thyroid adenoma development. Our data showed that single neonatal X-irradiation induced continuous apoptotic activity in the thyroid with the long-term alternation in Fas, Mct8, Lat4, and Lgals3 mRNA expressions. Some of these changes were similar to those induced by IDD, suggesting that neonatal X-irradiation may partially act as a thyroid tumor promoter.
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| Free Research Field |
内分泌放射線影響
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| Academic Significance and Societal Importance of the Research Achievements |
小児期放射線被曝が甲状腺発癌リスクであることは良く知られ、福島第一原発事故後にもその影響が憂慮された。しかし今日までそのメカニズムに関わる研究はほとんど行われておらず、科学的な知見が不足しておりリスクについての合理的な議論ができなかった。本研究は、小児期甲状腺が放射線高感受性であるメカニズムの一端を明らかにした重要な基礎科学的研究であり、その知見は放射線防護、放射線影響評価、リスクコミュニケーションに有用である。今後も起こりうる原発事故等において科学的根拠をもったリスク分析・判断を行うためには、さらなる発展研究が不可欠と考えるが、本研究の継続を求めた科研費申請は採択に至らなかった。
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