title: A double-labeling method for AChE and fluorescent retrograde tracers.
abstract: Staining for the degradative enzyme acetylcholinesterase (AChE) is an important tool in studying central cholinergic/cholinoceptive systems. AChE staining has also been useful in identifying the projections of AChE-containing neurons and codistribution of AChE with other neurotransmitters. The intensity and opacity of conventional AChE histochemical reaction products, however, pose problems for such double-labeling studies. Here, we have successfully combined a modified version (37) of the Koelle-Friedenwald AChE reaction with retrograde transport of the fluorescent tracer, Fluoro-Gold (FG). By omitting the final intensification steps of the Koelle-Friedenwald reaction, a translucent, light-stable reaction product is created. Viewed under darkfield illumination, this precipitate is of similar intensity and sensitivity to that produced by conventional AChE histochemical processing. Prior administration of an AChE-inhibitor yields preferential staining of AChE-positive neuronal somata. This nonintensified darkfield AChE (NIDA) histochemical method was compatible with visualization of retrogradely transported FG in AChE-positive neurons, allowing unambiguous identification of the projections of AChE-containing neurons.
authors.affiliation: Department of Physiology and Biophysics, University of Cincinnati College of Medicine, OH 45267.
authors.forename: M
authors.initials: M
authors.lastname: Ennis
authors.forename: M T
authors.initials: MT
authors.lastname: Shipley
authors.forename: M M
authors.initials: MM
authors.lastname: Behbehani
mesh_terms: D000110:Acetylcholinesterase / Q000032:analysis*; D000818:Animals; D005456:Fluorescent Dyes; D006651:Histocytochemistry / Q000379:methods*; D051381:Rats; D013266:Stilbamidines
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D013266:Stilbamidines; D000110:Acetylcholinesterase