MnO粉末による低線量放射線被曝はラットの精巣と前立腺の遺伝子発現を変化させる

Low-Dose Radiation Exposure with MnO Powder Changes Gene Expressions in the Testes and the Prostate in Rats.

• Nariaki Fujimoto
• Gaukhar Amantayeva
• Nailya Chaizhunussova
• Dariya Shabdarbayeva
• Zhaslan Abishev
• Bakhyt Ruslanova
• Yersin Zhunussov
• Almas Azhimkhanov
• Kassym Zhumadilov
• Aleksey Petukhov
• Valeriy Stepanenko
• Masaharu Hoshi

抄録

原爆爆発後の土壌中の主要放射性同位体ダストである放射性MnO粉末の内部被曝が雄性生殖機能に及ぼす生物学的影響を調べるために、精巣及び前立腺の遺伝子発現を調べた。10週齢のWistar雄性ラットに、放射性MnO粉末(全身投与で41-100mGy)、安定MnO粉末、外部Coγ線(2Gy)の3種類の放射線を照射した。被曝後３日目と６１日目に動物を壊死させた。精巣マーカー蛋白質遺伝子と前立腺分泌蛋白質遺伝子の mRNA 発現を Q-RT-PCR により定量した。3 日目には、ステロイド産生関連酵素 Cyp17a1 と Hsd3b1 の精巣遺伝子発現が MnO 被験群で減少した。生殖細胞特異的Spag4およびZpbp mRNAレベルも減少した。曝露後 61 日目には、最高線量の MnO 曝露群では Cyp11a1 遺伝子の発現が精巣で有意に減少し、Co γ線曝露群では別のステロイド生成関連 StAR 遺伝子の mRNA レベルが減少した。61日目のSpag4およびZpbp mRNAレベルにはグループ間で差はなかった。どのグループにおいても、曝露後の精巣に病理組織学的変化は観察されなかった。CRP1、KS3及びPSP94を含む前立腺蛋白質遺伝子の発現は、MnO照射群及びCoγ線照射群で有意に減少した。これらのデータから、100mGy以下のMnO粉末の内部被ばくは精巣及び前立腺の遺伝子発現に影響を与え、2Gyの外部γ線照射は効果が低いことが示唆された。

To investigate the biological effects of internal exposure of radioactive MnO powder, the major radioisotope dust in the soil after atomic bomb explosions, on male reproductive function, the gene expression of the testes and the prostate was examined. Ten-week-old male Wistar rats were exposed to three doses of radioactive MnO powder (41-100 mGy in whole body doses), stable MnO powder, or external Co γ-rays (2 Gy). Animals were necropsied on Days 3 and 61 postexposure. The mRNA expressions of testicular marker protein genes and prostatic secretory protein genes were quantified by Q-RT-PCR. On Day 3 postexposure, the testicular gene expressions of steroidogenesis-related enzymes, Cyp17a1 and Hsd3b1, decreased in MnO-exposed groups. Germ cell-specific Spag4 and Zpbp mRNA levels were also reduced. On postexposure Day 61, the Cyp11a1 gene expression became significantly reduced in the testes in the group exposed to the highest dose of MnO, while another steroidogenesis-related StAR gene mRNA level reduced in the Co γ-rays group. There were no differences in Spag4 and Zpbp mRNA levels among groups on Day 61. No histopathological changes were observed in the testes in any group following exposure. Expression in the prostatic protein genes, including CRP1, KS3, and PSP94, significantly decreased in MnO-exposed groups as well as in the Co γ-rays group on Day 61 postexposure. These data suggest that the internal exposure to MnO powder, at doses of less than 100 mGy, affected the gene expressions in the testis and the prostate, while 2 Gy of external γ-irradiation was less effective.