Electron microscopic localization of cholinesterase activity in Alzheimer brain tissue.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity was localized by electron microscopic enzyme cytochemistry in cortex from Alzheimer brains and brains from non-demented cases. In the tangle-rich medial temporal cortex of the Alzheimer brain, most of the neuronal AChE was associated with neurofibrillary tangles. These structures also contained BChE activity. In normal neurons AChE activity was found in the rough endoplasmic reticulum, nuclear envelope and Golgi apparatus. Little BChE activity was noted in normal cortex. In neuritic plaques, AChE and BChE activity was associated mostly with the amyloid, but also with the neuritic component.