活性酸素種の一つスーパーオキシドアニオンを分解する酵素,SODをからだの中に多くもつ動物ほど長生きすると考えられている。金属がこの酵素の中心的な役割を果たしている。「原子核をプローブとするマルチトレーサ法および中性子放射化分析法」を用いて,脳内の金属SOD酵素の生物無機化学的研究を展開してきた。初年度平成10年度は,脳内各部位(大脳皮質,線条体,海馬,橋延髄,小脳)における金属の取込率と金属濃度を決定した。平成11年度は年齢を1日齢〜53週齢に拡大し、Zn、Mnの金属のデータを収集した。平成12年度は、1日齢〜6週齢までに特に注目し、マルチトレーサ法および中性子放射化分析さらにマクロオートラジオグラフ法を適用し、脳局所における代謝について知見を得た。1.Mnの短期間の取込が、若年齢(1日〜21日齢)で極めて高い。一方、Mn濃度はこの期極めて低い。この成長期におけるMn要求度は、脳重量の急激な増加、さらにはSOD濃度の増加と関連しているようであった。2.Znにおける傾向は、Mnほどではないが同様であった。これもやはり成長期におけるSOD濃度の増加と考えられる。SODの生物無機化学の寄与としては成果があった。今後、脳内の酵素そのものの単離と機能発現について探求すべきであろう。
This study was undertaken in order to acquire better understanding of the biobehavior metal superoxide dismutases by the techniques of multitracer and instrumental neutron activation analysis. The followings were found.1) The radioactive multitracer technique was applied to a study on the uptake behavior of trace elements in normal C57BL/6N mice. Comparative uptake behavior of ^<46>Sc, ^<54>Mn, ^<59>Fe, ^<58>Co, ^<65>Zn, ^<75>Se, ^<83>Rb and ^<88>Zr tracers was examined among 11 organs (brain, cardiac muscle, lung, liver, spleen, pancreas, kidneys, bone, muscle, eyeballs and testes) and blood, and evaluated in terms of the "tissue uptake rate (the radioactivity percentage of injected dose per gram of tissue, %dose/g)". The multitracer technique revealed reliable data demonstrating characteristic uptake of the 8 trace elements, Sc, Mn, Fe, Co, Zn, Se, Rb and Zn by the brain and other organs, as well as the distinctive feature of the accumulation and retention of each element in the brai n. According to these results, it is evident that the metal ions examined in this work are easily transported into the brain, in addition, the high retention of Se, Rb, Mn and Zn in the brain during a fairly long time suggests active involvement of these elements in the brain function.2) Brain regional uptakes for ^<46>Sc, ^<54>Mn, ^<58>Co, ^<65>Zn, ^<75>Se, and ^<83>Rb in mice were examined using multitracer under deficient and excessive states of an essential trace elements, manganese, zinc or selenium. Zn-deficient and excessive states, and Se-deficient and excessive states influence the brain regional uptake behaviors of other trace elements except respective elements. On the other hand, in the mouse brain under Mn-deficient and excessive states, few interrelation between Mn and other elements was found from 0.4ppm to 300.4ppm. Multitracer technique was found to be very useful to screen the element-element interrelation in brain.3) Concentrations and uptake behavior of manganese (Mn), zinc (Zn) and selenium (Se) in mouse brain were studied by means of multitracer technique, neutron activation analysis and autoradiography. Comparative concentrations of Mn, Zn and Se and tracer uptake behavior of ^<54>Mn, ^<65>Zn and ^<75>Se were examined in the brain of 1-, 4-, 8-, 21- and 56-day-old mice, and evaluated in terms of brain concentration (part per million, ppm) and brain uptake rate (the radioactivity percentage of injected dose per gram of brain, %dose/g), respectively. As a result, the brain concentrations of Mn was increasing with growth, although those of Se and Zn were hardly changing. On the other hand, the uptakes of the 3 tracers by the brain of 1-day-old mice were much higher than those of other elder ones. Using radioactive ^<54>Mn as a single tracer, autoradiography was examined to known the Mn uptake regional distribution in the brain of 1-, 8- and 21-day-old mice, and observed higher regional uptake of Mn by the cerebral cortex, hippocampus, thalamus and hypothalamus in the young brain.
研究課題/領域番号:10640539, 研究期間(年度):1998-2000
出典：「多元素同時追跡法による脳内金属SOD酵素の生物無機化学の研究」研究成果報告書 課題番号10640539(KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成