Isobe I, Michikawa M, Yanagisawa K
Department of Dementia Research, National Institute for Longevity Sciences, Morioka, Obu, Japan.
Neurosci Lett. 1999 May 7;266(2):129-32. doi: 10.1016/s0304-3940(99)00282-7.
The effect of amyloid beta-protein (Abeta) on the cellular reducing activity has been a controversial issue. We determined the cellular reducing activity in cultured astrocytes using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl )-2H-tetrazolium (WST-8) reduction assays following Abeta treatment. MTT reduction was inhibited whereas WST-8 reduction was unaffected by the Abeta treatment. Furthermore, the early extracellular appearance of MTT formazan, a reduced product of MTT, was observed in association with the rapid disappearance of intracellular formazan granules. Notably, similar results were obtained in cultures treated with chloroquine, a perturbant of membrane trafficking. Our results suggest that MTT formazan exocytosis is enhanced in a similar manner by Abeta and chloroquine and that this biological activity of Abeta may underlie the pathogenesis of Alzheimer's disease.
β-淀粉样蛋白（Aβ）对细胞还原活性的影响一直是个有争议的问题。在用Aβ处理后，我们使用3-（4,5-二甲基噻唑-2-基）-2,5-二苯基溴化四氮唑（MTT）和2-（2-甲氧基-4-硝基苯基）-3-（4-硝基苯基）-5-（2,4-二磺酸苯基）-2H-四氮唑（WST-8）还原试验来测定培养的星形胶质细胞中的细胞还原活性。MTT还原受到抑制，而WST-8还原不受Aβ处理的影响。此外，观察到MTT甲臜（MTT的还原产物）在细胞外早期出现，同时细胞内甲臜颗粒迅速消失。值得注意的是，在用氯喹（一种膜转运扰动剂）处理的培养物中也获得了类似的结果。我们的结果表明，Aβ和氯喹以类似的方式增强了MTT甲臜的胞吐作用，并且Aβ的这种生物学活性可能是阿尔茨海默病发病机制的基础。
