An atlas of α‐bungarotoxin binding sites and structures containing acetylcholinesterase in the mouse central nervous system

Abstract

Abstract Alpha‐bungarotoxin (α‐BGT) has been established as a specific ligand for peripheral nicotinic acetylcholine receptors (nAChRs). To demonstrate the distribution of possible nAChRs in the mouse central nervous system, detailed maps of α‐BGT binding sites were made by light microscopic autoradiography. Cryostat sections fixed with 4% paraformaldehyde were incubated with [ 125 I]α‐BGT and were processed for autoradiographic visualization of bound radioactivity. Systematic observations of the autoradiographs revealed extensive but uneven distributions of α‐BGT binding sites throughout the brain and spinal cord. The highest level of toxin binding occurred in the nucleus (nuc.) dorsalis tegmenti (von Gudden) as well as in the nuc. subthalamicus, nuc. amygdaloideus medialis posterior, nuc. centrum medianum‐parafascicularis thalami, nuc. interpeduncularis pars lateralis, nuc. parabigeminalis, colliculus posterior, and nuc. dorsalis nervi vagi. The distribution patterns of acetylcholinesterase (AChE) activity were also mapped histochemically and were correlated to those of α‐BGT binding sites. Most of the regions with significant levels of α‐BGT binding also showed significant staining reaction of AChE.