Free -radical generation by amyloid p protein and the protective effect by laminin against amyloid β-protein induced toxicity

利用电子顺磁共振（EPR）技术研究了层粘胶蛋白（一种细胞外基质成分）对β -淀粉样蛋白（Aβ）诱导的自由基的抑制作用。DMPO, α-（4-吡啶-1-氧化物）- n -叔丁基硝酮；POBN分别。我们通过两种实验来明确层粘连蛋白对Aβ的保护机制。首先用EPR测定层粘连蛋白是否直接抑制Aβ诱导的自由基，将Aβ与层粘连蛋白混合后加入PC12细胞。其次，通过EPR测定，观察附着层粘连蛋白的细胞的防御功能是否得到增强。Aβ与层粘连蛋白混合后，细胞的自由基生成量减少，细胞活力提高，但与未与层粘连蛋白结合24h的细胞相比，未与层粘连蛋白结合24h的细胞自由基生成量无显著差异。综上所述，层粘连蛋白具有神经保护作用，其对Aβ诱导的自由基产生的保护作用可能与Aβ的直接反应有关。

We investigated the inhibitory effect by laminin, which is one of the extracellular matrix components, against beta amyloid(Aβ) induced free radicals by electron paramagnetic resonance(EPR) using PC12 cells with two kinds of spin trap, 5,5-dimethyl-1-pyrroline-N-oxide ; DMPO, α-(4-pyridyl-1-oxide)-N-tert-butylnitrone ; POBN respectively. We investigated two kinds of experiment to clear the mechanism how laminin shows the protection against Aβ. At first, EPR measurement was performed to see whether or not laminin directly inhibit Aβ induced free radicals, Aβ was mixed with laminin and the solution was added to PC12 cells. The second, EPR measurement was also performed to see whether or not the cells which attached laminin get strengthened their defense function.The free radical production was reduced when Aβ was mixed with laminin and the cell viability also increased compared with Aβ only added to the cells, though there was no difference in generating free radicals between cells which were attached with laminin for 24hrs before Aβ addition and cells which did not attach laminin for 24hrs. Therefore we concluded that laminin has neuroprotective ability and its protective effect against Aβ induced free radical generation is due to possibly direct reaction with Aβ.