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α‐Conotoxin BuIA[T5A;P6O]: a novel ligand that discriminates between 06 β4 and 0:6 β2 nicotinic acetylcholine receptors and blocks nicotine‐stimulated norepinephrine release
Author(s) -
Azarn Layla,
Maskos Uwe,
Changeux Jean-Pierre,
Dowell Cheryl D.,
Christensen Sean,
Biasi Mariella De,
McIntosh J. Michael
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.10.166272
Subject(s) - chemistry , nicotinic agonist , acetylcholine receptor , conotoxin , nicotine , dopamine , pharmacology , nicotinic acetylcholine receptor , methyllycaconitine , acetylcholine , receptor , endocrinology , biochemistry , neuroscience , biology , venom
α6* (asterisk indicates the presence of additional subunits) nicotinic acetylcholine receptors (nAChRs) are broadly implicated in catecholamine‐dependent disorders that involve attention, motor movement, and nicotine self‐administration. Different molecular forms of 06 nAChRs mediate catechol‐amine release, but receptor differentiation is greatly hampered by a paucity of subtype selective ligands. 0‐Conotoxins are nAChR‐targeted peptides used by Conus species to incapacitate prey. We hypothesized that distinct conotoxin‐binding kinetics could be exploited to develop a series of selective probes to enable study of native receptor subtypes. Proline6 of 0‐conotoxin BuIA was found to be critical for nAChR selectivity; substitution of proline6 with 4‐hydroyx‐proline increased the IC 50 by 2800‐fold at 06/o3β2β3 but only by 6‐fold at o6/o3β4 nAChRs (to 1300 and 12 nM, respectively). We used conotoxin probes together with subunit‐null mice to interrogate nAChR subtypes that modulate hippocampal norepi‐nephrine release. Release was abolished in 06‐null mutant mice. 0‐Conotoxin BuIA[T5A;P6O] partially blocked norepinephrine release in wild‐type controls but failed to block release in β4 _/_ mice. In contrast, BuIA[T5A;P6O] failed to block dopamine release in the wild‐type striatum known to contain o6β2* nAChRs. BuIA[T5A;P6O] is a novel ligand for distinguishing between closely related 06* nAChRs; o6β4* nAChRs modulate norepinephrine release in hippocampus but not dopamine release in stria‐tum.—Azam, L., Maskos, U., Changeux, J.‐P., Dow‐ell, C. D., Christensen, S., De Biasi, M., McIntosh, J. M. o‐Conotoxin BuIA[T5A;P6O]: a novel ligand that discriminates between o6β4 and o6β2 nAChRs and blocks nicotine‐stimulated norepinephrine release. FASEBJ. 24, 5113–5123 (2010). www.fasebj.org