報告書番号

G03016

タイトル（和文）

発症機序の異なる2種類のII型糖尿病モデルマウスに対する低線量率放射線の照射効果の検証

タイトル（英文）

Effects of Low-Dose Rate Irradiation on Two Types of Type II Diabetes Model Mice

概要 （図表や脚注は「報告書全文」に掲載しております）

長期低線量率（0.70 mGy/hr）の照射で発症の成因が異なる2種類のII型糖尿病モデル、dbマウスマウスおよびAKITAマウスに対し、糖尿病の改善効果や長期照射による影響の有無について調べた。（1）dbマウスにのみ放射線を長期間照射すると、照射群の一部に糖尿病の改善効果が示された。（2）糖尿病改善マウスと非改善マウスの間で体重の差はなく、また食餌量や飲水量も関係が認められなかったことから、長期間の低線量率照射は、食欲減退など生命活動に影響を与えないことが分かった。（3）いずれのマウスも照射群は長寿であった。また毛並みの良さなどの照射群の方が老化の所見が認められなかった。以上、長期期間に渡る低線量率照射は照射の影響を与えることなく、肥満型過食性のII型糖尿病モデルマウスに対し糖尿病の改善に有効であることを示した。また死亡率の低下や抗加齢効果もあることが示された。

概要 （英文）

The effects of low-dose rate gamma-irradiation were investigated in two mouse strains - C57BL/KsJ-db/db (db mouse) and AKITA (AKITA mouse) -for type II diabetes mellitus. Both strains develop the developed type II diabetes by about 8 weeks of age due to dysfunction of the insulin/insulin receptor. The ‘db Mouse’ shows obese and exhibits hyperinsulinism, and the onset of Type II diabetes like resembles that for Westerners. On the other hand, the AKITA mouse has exhibits disordered insulin secretion, and the diabetes such as resembles that of Asians.Ten-week old female mice, in groups of 8 or 12, were irradiated at 0.65 mGy/hr in the low-dose rate irradiation facility in the Low Dose Radiation Research Center. The level of urine glucose was measured with test slips. The urine glucose levels of all of the mice were highly elevated the beginning of the irradiation. In the irradiated group of db mice, three mice showed decrease in glucose level compare to the level of non-irradiated diabetes mice after 35, 52 or 80 weeks of irradiation. All had maintained a normal level thereafter. No such improvement in diabetes was ever observed in the 12 mice of in the non-irradiated control group. The AKITA mice, however, did not decrease the glucose level regardless of the irradiation.Both the db mice and AKITA mice had their lives prolonged their life by the irradiation. The survival rate of db mice at the age of 90 weeks was 75 % in the irradiated group, but 50 % in the non-irradiated group. The average life span was 104 weeks in the irradiated group and 87 weeks in the control group. Furthermore, a marked difference was furthermore observed in the appearance of the coat hair, skin, and tail; appearances were well preserved in the irradiated group. The average life span in the irradiated AKITA mice was also longer than that for the non-irradiated mice, 51 weeks and 41 weeks in the irradiated and non-irradiated group respectively.These results suggest that the low-dose irradiation modified some factors of the diabetic mice, leading to improvement of them and but also to the suppression of the aging process. However the different results showed the improvement of diabetes between db mice and AKITA mice. Observed difference in irradiation associated changes between two strains of mice might reflect different genetic mechanisms of two onset of diabetes.

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