Ueda K, Shinohara S, Yagami T, Asakura K, Kawasaki K
CNS Research Laboratories, Shionogi and Co., Ltd., Osaka, Japan.
J Neurochem. 1997 Jan;68(1):265-71. doi: 10.1046/j.1471-4159.1997.68010265.x.
Amyloid beta protein (A beta), the central constituent of senile plaques in Alzheimer's disease (AD) brain, is known to exert toxic effects on cultured neurons. The role of the voltage-sensitive Ca2+ channel (VSCC) in beta (25-35) neurotoxicity was examined using rat cultured cortical and hippocampal neurons. When L-type VSCCs were blocked by application of nimodipine, beta (25-35) neurotoxicity was attenuated, whereas application of omega-conotoxin GVIA (omega-CgTX-GVIA) or omega-agatoxin IVA (omega-Aga-IVA), the blocker for N- or P/Q-type VSCCs, had no effects. Whole-cell patch-clamp studies indicated that the Ca2+ current density of beta (25-35)-treated neurons is about twofold higher than that of control neurons. Also, beta (25-35) increased Ca2+ uptake, which was sensitive to nimodipine. The 2', 7'-dichlorofluorescin diacetate assay showed the ability of beta (25-35) to produce reactive oxygen species. Nimodipine had no effect on the level of free radicals. In contrast, vitamin E, a radical scavenger, reduced the level of free radicals, neurotoxicity, and Ca2+ uptake. These results suggest that beta (25-35) generates free radicals, which in turn, increase Ca2+ influx via the L-type VSCC, thereby inducing neurotoxicity.
淀粉样β蛋白（Aβ）是阿尔茨海默病（AD）脑内老年斑的主要成分，已知其对培养的神经元具有毒性作用。使用大鼠培养的皮质神经元和海马神经元研究了电压敏感性Ca2+通道（VSCC）在β（25 - 35）神经毒性中的作用。当应用尼莫地平阻断L型VSCC时，β（25 - 35）的神经毒性减弱，而应用ω-芋螺毒素GVIA（ω-CgTX-GVIA）或ω-阿加毒素IVA（ω-Aga-IVA），即N型或P/Q型VSCC的阻滞剂，则没有效果。全细胞膜片钳研究表明，经β（25 - 35）处理的神经元的Ca2+电流密度比对照神经元高约两倍。此外，β（25 - 35）增加了Ca2+摄取，这对尼莫地平敏感。2',7'-二氯荧光素二乙酸酯测定显示β（25 - 35）具有产生活性氧的能力。尼莫地平对自由基水平没有影响。相比之下，自由基清除剂维生素E降低了自由基水平、神经毒性和Ca2+摄取。这些结果表明，β（25 - 35）产生活性氧，进而通过L型VSCC增加Ca2+内流，从而诱导神经毒性。
