報告書番号

G03015

タイトル（和文）

低線量率放射線照射したII型糖尿病モデルマウスの糖代謝に及ぼす影響

タイトル（英文）

Effects on the Glucose Metabolism in Type II Diabetes Model Mice Treated with Dose-Rates Irradiation

概要 （図表や脚注は「報告書全文」に掲載しております）

II型糖尿病モデルマウスに1.2 mGy/hr、0.65 mGy/hr、あるいは0.35 mGy/hrの線量率で24日間照射し、血糖値、血中インスリン量の変化について調べた。 主な成果は、（1）今回の実験の範囲では、照射による血糖値の減少は認められなかったが、加齢による血中インスリン量の減少を防ぎ、インスリン抵抗性を改善する傾向が示された、（2）糖負荷試験、インスリン負荷試験を行ったときにもインスリン受容体の改善を示唆できる結果が得られた、（3）いずれの実験においても24日間の照射では線量率の違いは見出せなかったが、非照射群に比べ照射群でインスリン抵抗性の改善する傾向が認められ、照射時間を掛けると線量率効果が生じることが示唆された。 以上の結果より、低線量率放射線の照射は、インスリン受容体が機能不全であるII型糖尿病モデルマウスに対し、インスリン代謝機能の改善効果があることを示した。

概要 （英文）

The effects of low-dose rate gamma-irradiation on the type II diabetes mellitus were investigated in C57BL/KsJ-db/db (db mouse). This mouse develops the type II diabetes within 8 weeks of the birth due to a dysfunction of the insulin receptors. As a result, the db mouse shows obese and exhibits hyperinsulinism.Ten-week old female mice (12 mice in each group) were irradiated with gamma-rays at 0.35 mGy/hr, 0.65 mGy/hr or 1.2 mGy/hr in the low-dose rate irradiation facility in the Low Dose Radiation Research Center. The level of plasma glucose and insulin was measured. After 2 weeks irradiation, the glucose level slightly increased, however the difference between the irradiated mice and non-irradiated groups was not significant. The plasma insulin concentration decreased in the non-irradiated group to half of the initial level. In the irradiated group, it also decreased but in the group of 0.65 mGy/hr and 0.35 mGy/hr, it was significantly differed from that in the non-irradiated group.In the glucose tolerance test, plasma glucose level increased shortly after 0.1 mg/head glucose injection by mouth and reached to a peak at 90-120 min after the injection. The glucose level of the non-irradiated mice was slightly higher than that of irradiated mice. The plasma insulin level of non-irradiated group was enhanced after the injection and maintained the level during the test. However the levels of irradiated mice were decreased at 30 ‐ 60 min after the injection. Both the level of non-irradiated and irradiated was almost same but the non-irradiated one was a little high.In all of mice, the plasma insulin level was highly elevated right after the 0.05 units/head insulin injection by i.p. and the levels were also gradually decreased. The level of the non-irradiated group was slowly decreased and was higher than the irradiated mice. The plasma glucose levels of all mice did not change after the test; however, the levels of irradiated mice were slightly lower than that of non-irradiated mice. The dose rates effect was not observed, because the exposed time might be shorter than the appearances of effects under these experimental conditions. These results suggest that the low dose rates irradiation modified the function of insulin in the diabetic mice. The mechanisms of metabolism of glucose might activate after the decreased of insulin resistance.

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