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Methadone increases intracellular calcium in SH‐SY5Y and SH‐EP1‐hα7 cells by activating neuronal nicotinic acetylcholine receptors
Author(s) -
Pakkanen Jukka S.,
Nousiainen Heli,
YliKauhaluoma Jari,
Kylänlahti Irene,
Möykkynen Tommi,
Korpi Esa R.,
Peng JianHong,
Lukas Ronald J.,
Ahtee Liisa,
Tuominen Raimo K.
Publication year - 2005
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2005.03279.x
Subject(s) - methyllycaconitine , epibatidine , mecamylamine , chemistry , pharmacology , nicotinic agonist , acetylcholine receptor , acetylcholine , agonist , nicotine , nicotinic antagonist , patch clamp , competitive antagonist , receptor , nicotinic acetylcholine receptor , biochemistry , biology , neuroscience
(–)‐Methadone acts as an agonist at opioid receptors. Both (+)‐ and (–)‐enantiomers of methadone have been suggested to be potent non‐competitive antagonists of α3β4 neuronal nicotinic acetylcholine receptors (nAChRs). In the present study, we have examined interactions of methadone with nAChRs by using receptor binding assays, patch‐clamp recording and calcium fluorometry imaging with SH‐SY5Y cells naturally expressing α7 and α3* nAChR subtypes and SH‐EP1‐hα7 cells heterologously expressing human α7 nAChRs. Methadone potently inhibited binding of [ 3 H]methyllycaconitine to α7 nAChRs and that of [ 3 H]epibatidine to α3* nAChRs. Methadone pretreatment induced up‐regulation of epibatidine binding sites in SH‐SY5Y cells. Using whole‐cell patch‐clamp recording, both isomers of methadone activated cation currents via mecamylamine‐sensitive nAChRs in SH‐SY5Y cells. Nicotine and both (+)‐ and (–)‐methadone evoked increases in [Ca 2+ ] i in both fluo‐3AM loaded cell lines, and these effects were blocked by mecamylamine and by the α7 selective antagonist methyllycaconitine, suggesting effects of methadone as α7‐nAChR agonist. Sensitivity of sustained nicotine and methadone effects to blockade by CdCl 2 , ryanodine and xestospongin‐c implicates voltage‐operated Ca 2+ channels and intracellular Ca 2+ stores as downstream modulators of elevated [Ca 2+ ] i . Collectively, our results suggest that methadone engages in complex and potentially pharmacologically significant interactions with nAChRs.