Presence of mRNA of muscle nicotinic acetylcholine receptor subunits and an ɛ-subunit splice variant in the mouse brain

Transcripts encoding for α1, β1, δ, γ and ɛ (and its splice variant ɛs) subunits of the muscle-type nicotinic acetylcholine receptor (nAChR) were assessed using reverse transcription followed by polymerase chain reaction (RT-PCR) assays, with RNA extracted from the mouse skeletal muscle (diaphragm) and brain regions (cortex, hippocampus and cerebellum). The presence of α1, β1, δ, γ, ɛ and ɛs transcripts was confirmed in the diaphragm muscle, used as positive control. mRNAs coding for muscle α1, β1, δ, ɛ, ɛs, but not γ subunits, were detected in adult mouse brain regions. An ɛ-subunit sequence variant, named ɛt, was also detected in all brain regions examined, but not in skeletal muscle. This new ɛ-subunit splice variant lacks a 115 bp cassette corresponding to exon 8 in the first intracellular transmembrane domain of the subunit, leading to a truncated protein. The data provide evidence for the presence of muscle-type nAChR subunits in the mouse central nervous system.