Cellular distribution of the mRNA for the α7 subunit of the nicotinic acetylcholine receptor in the human cerebral cortex

Abstract

AbstractCentral nicotinic acetylcholine receptors (nAChRs) are ligand‐gated cationic channels characterized by a wide pharmacological and molecular diversity depending on the subunits involved. Recently a new type of a nicotinic acetylcholine receptor channel, highly permeable to calcium, consisting of α7 subunits which bear a binding site for the snake venom α‐bungarotoxin has been described. α‐bungarotoxin binding sites have previously been localized in the human and rat brain. Immunohistochemistry has revealed the presence of α7 subunits in the rodent CNS. Presently we have applied digoxigenin‐labeled RNA probes to localize α7 mRNA in human brain using autopsy samples of prefrontal (Area 10) and motor cortex (Area 4). α7 transcripts are expressed in numerous neurons throughout both cortical regions. Mainly pyramidal‐like neurons of layers II/III, V, and VI were labeled. In contrast to our previous studies on the localization of α3 and α4 transcripts, only a few giant pyramidal neurons in A4 but a rather high number of layer I neurons in A4 and A10 expressed α7 mRNA. The study shows that nicotinic receptor subunit mRNAs are distributed in a subunit‐ and area‐specific manner in the human cerebral cortex. These findings will be of importance as to the selective, ligand‐mediated stimulation of nicotinic receptor subtypes as a possible tool to improve cholinergic transmission in neurodegenerative disorders like Alzheimer's disease. © 1995 Wiley‐Liss, Inc.