報告書番号

L04004

タイトル（和文）

II型糖尿病モデルマウスにおける低線量率照射の膵臓抗酸化機能増強効果

タイトル（英文）

Stimulation Effects of Low Dose-Rate Irradiation on Pancreatic Antioxidant Activity in 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）

低線量率放射線の連続照射によって抗酸化機能が増強し、より重篤な糖尿病への進行を抑制するという機構仮説を検証する。このため、II型糖尿病モデルマウスに低線量率放射線で連続照射実験を行い、血中インスリン量および膵臓細胞の酸化を防ぐSOD（Superoxide dismutase）の活性度を測定した。本研究により得られた主な成果は以下の通りである。（1）照射群の方が、非照射群に比べて血中インスリン量の経時的な減少を防ぎ、特に照射後30日以降で微増に転じた。また0.70 mGy/hr照射群は高い濃度であった。（2）Cu/Zn-SOD活性は照射に関係なく時間の経過にともない低下した。一方、Mn-SOD活性は照射群で増加する特性を測定し、特に0.70 mGy/hrで有意に高くなった。（3）膵臓の病理解析の結果、0.70 mGy/hr照射群は他の照射群に比べ損傷の程度が低くいことが示された。

概要 （英文）

The effects of low dose-rate gamma irradiation on the type II diabetes mellitus were investigated in BKS.Cg-+Leprdb/+Leprdb/Jcl (DB mice).Ten-week-old female DB mice (5 mice in each group) were irradiated with gamma rays at 0.35, 0.70, or 1.2 mGy/hr. During the course of the 12 weeks the glucose level slightly increased with little difference between the irradiated and the non-irradiated groups. The plasma insulin concentration decreased within the first 4 weeks in all groups. The level was kept low in the non-irradiated mice; while the insulin level in the irradiated groups showed a tendency to increase. In the 0.70 mGy/hr group the increase was statistically significant after 12 weeks of irradiation. Total activity of SOD, one of antioxidative enzymes, decreased both in non-irradiated and irradiated groups; however the decrease was less in the irradiated groups, especially 0.70 mGy/hr group. In the 0.70 mGy/hr group Mn-SOD activity, one of the components of total SOD activity, increased after 12-week irradiation. A pathological examination of the pancreas revealed that damage to βcells responsible for the secretion of insulin was much less in the 0.70 mGy/hr group compared to that in the non-irradiated group.These results indicated that the low dose-rate irradiation increase the antioxidative capacity in the pancreas to protectβcells from oxidative damage, and the to increase the insulin level. This mechanism would lead the mice to the recovery from the disease and the prolongation of the life span as is demonstrated in our previous report.

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