Immunohistochemical localization of neuronal nicotinic receptors in the rodent central nervous system

Abstract

The distribution of nicotinic acetylcholine receptors (AChR) in the rat and mouse central nervous system has been mapped in detail using monoclonal antibodies to receptors purified from chicken and rat brain. Initial studies in the chicken brain indicate that different neuronal AChRs are contained in axonal projections to the optic lobe in the midbrain from neurons in the lateral spiriform nucleus and from retinal ganglion cells. Monoclonal antibodies to the chicken and rat brain AChRs also label apparently identical regions in all major subdivisions of the central nervous system of rats and mice, and this pattern is very similar to previous reports of 3H-nicotine binding, but quite different from that of alpha-bungarotoxin binding. In several instances, the immunohistochemical evidence has strongly indicated that neuronal AChR undergoes axonal transport. The clearest example of this has been in the visual system, where labeling was observed in the retina, the optic nerve and tract, and in all of the major terminal fields of the optic nerve except the ventral suprachiasmatic nucleus. This was confirmed in unilateral enucleation experiments in the rat, where labeling was greatly reduced in the contralateral optic tract, ventral lateral geniculate nucleus, pretectal nuclei receiving direct visual input, superficial layers of the superior colliculus, and medical terminal nucleus, and was significantly reduced in the dorsal lateral geniculate nucleus. Clear neuronal labeling was also observed in dorsal root ganglion cells and in cranial nerve nuclei containing motoneurons that innervate branchial arch-derived muscles, although the possibility that neuronal AChR undergoes axonal transport in the latter cells was not tested experimentally.(ABSTRACT TRUNCATED AT 250 WORDS)