Microwave-Assisted Cytochemistry: Accelerated Visualization of Acetylcholinesterase at Motor Endplates

Acetylcholinesterase (AChE) is the modulating enzyme of cholinergic systems. Study of its morphological distribution and its pathophysiological disposition following disease or exposure to anticholinesterase compounds such as pesticides, organophosphates, and chemical (chem) warfare nerve agents, has been through the use of a multitude of specific cytochem reactions which use metal-capturing methods of thiocholine, following hydrolysis of acetylthiocholine by AChE. The first of these methods to be recognized and used in many investigations was the Koelle technique (Koelle and Friedenwald, 1949 ). This in situ procedure used copper (Cu) as a capturing metal which without any further treatment yielded dense precipitates localized at sites of enzyme activity. These precipitates could be visualized at the light-microscopy and electron microscopy (EM) level. The empirical reaction for the primary cytochem Cu- capturing reaction is as follows: Acetylthiocholine iodide + AChE → Thiocholine iodide + Acetate Thiocholine iodide + Cu sulfate → Cu thiocholine iodide