title: Enhancement of MTT, a tetrazolium salt, exocytosis by amyloid beta-protein and chloroquine in cultured rat astrocytes.
abstract: 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.
authors.affiliation: Department of Dementia Research, National Institute for Longevity Sciences, Morioka, Obu, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Isobe
authors.forename: M
authors.initials: M
authors.lastname: Michikawa
authors.forename: K
authors.initials: K
authors.lastname: Yanagisawa
mesh_terms: D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D002738:Chloroquine / Q000494:pharmacology*; D004396:Coloring Agents; D005089:Exocytosis / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013778:Tetrazolium Salts / Q000378:metabolism*; D013844:Thiazoles / Q000378:metabolism*
chemical_list: D016229:Amyloid beta-Peptides; D004396:Coloring Agents; D013778:Tetrazolium Salts; D013844:Thiazoles; D002738:Chloroquine; C022616:thiazolyl blue