Colocalization of cholinesterases with beta amyloid protein in aged and Alzheimer's brains.
The colocalization of beta amyloid protein with the enzymes acetyl- and butyrylcholinesterase was assessed using immunocytochemistry for beta amyloid protein and a sensitive histochemical technique for cholinesterases. In non-demented aged and Alzheimer's disease brains, double-stained sections for cholinesterases and thioflavin-S showed that all thioflavin-S-positive plaques were also positive for cholinesterases, indicating the presence of these enzymes in all plaques with beta-pleated amyloid protein. When amyloid angiopathy was present, cholinesterases were also observed in amyloid-laden vessels walls. Comparison of series of adjacent sections alternatively stained for acetylcholinesterase, beta amyloid protein and butyrylcholinesterase, as well as by double histo-immunocytochemical staining, showed either cholinesterase in a proportion of the preamyloid diffuse plaques. These data indicate that cholinesterases are associated with the amyloid protein from very early stages, when the beta-pleated structure is being formed. Novel functions attributed to acetyl- and butyrylcholinesterase, such us their proteolytic activity either by themselves or in association with heparan sulfate proteoglycans, may play a role in the aggregation or the consolidation processes taking place at the early stages of diffuse plaque formation.
Morán
M A
MA
Morphology Department, School of Medicine, Autonomous University of Madrid, Spain.
Mufson
E J
EJ
Gómez-Ramos
P
P
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism* / Q000473:pathology; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D001921:Brain / Q000201:enzymology / Q000473:pathology; D002091:Butyrylcholinesterase / Q000378:metabolism; D002802:Cholinesterases / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry
D016229:Amyloid beta-Peptides; D002091:Butyrylcholinesterase; D002802:Cholinesterases