title: Identification and functional expression of a family of nicotinic acetylcholine receptor subunits in the central nervous system of the mollusc Lymnaea stagnalis.
abstract: We described a family of nicotinic acetylcholine receptor (nAChR) subunits underlying cholinergic transmission in the central nervous system (CNS) of the mollusc Lymnaea stagnalis. By using degenerate PCR cloning, we identified 12 subunits that display a high sequence similarity to nAChR subunits, of which 10 are of the alpha-type, 1 is of the beta-type, and 1 was not classified because of insufficient sequence information. Heterologous expression of identified subunits confirms their capacity to form functional receptors responding to acetylcholine. The alpha-type subunits can be divided into groups that appear to underlie cation-conducting (excitatory) and anion-conducting (inhibitory) channels involved in synaptic cholinergic transmission. The expression of the Lymnaea nAChR subunits, assessed by real time quantitative PCR and in situ hybridization, indicates that it is localized to neurons and widespread in the CNS, with the number and localization of expressing neurons differing considerably between subunit types. At least 10% of the CNS neurons showed detectable nAChR subunit expression. In addition, cholinergic neurons, as indicated by the expression of the vesicular ACh transporter, comprise approximately 10% of the neurons in all ganglia. Together, our data suggested a prominent role for fast cholinergic transmission in the Lymnaea CNS by using a number of neuronal nAChR subtypes comparable with vertebrate species but with a functional complexity that may be much higher.
authors.affiliation: Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognition Research, Faculty of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands.
authors.forename: Pim
authors.initials: P
authors.lastname: van Nierop
authors.forename: Sonia
authors.initials: S
authors.lastname: Bertrand
authors.forename: David W
authors.initials: DW
authors.lastname: Munno
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Gouwenberg
authors.forename: Jan
authors.initials: J
authors.lastname: van Minnen
authors.forename: J David
authors.initials: JD
authors.lastname: Spafford
authors.forename: Naweed I
authors.initials: NI
authors.lastname: Syed
authors.forename: Daniel
authors.initials: D
authors.lastname: Bertrand
authors.forename: August B
authors.initials: AB
authors.lastname: Smit
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D008195:Lymnaea / Q000145:classification / Q000502:physiology*; D008969:Molecular Sequence Data; D009424:Nervous System Physiological Phenomena; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D021122:Protein Subunits / Q000502:physiology; D051381:Rats; D011978:Receptors, Nicotinic / Q000145:classification / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D021122:Protein Subunits; D011978:Receptors, Nicotinic; D011994:Recombinant Proteins