TY - JOUR
T1 - 5-Iodo-A-85380, a specific ligand for α4β2 nicotinic acetylcholine receptors, prevents glutamate neurotoxicity in rat cortical cultured neurons
AU - Ueda, Masashi
AU - Iida, Yasuhiko
AU - Kitamura, Youji
AU - Kawashima, Hidekazu
AU - Ogawa, Mikako
AU - Magata, Yasuhiro
AU - Saji, Hideo
N1 - Funding Information:
We thank Professor Akinori Akaike and his laboratory members (Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University) for their technical support and invaluable discussions on the cell culture and neurotoxicity assays. This work was supported in part by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Technology of Japan and a grant from the Smoking Research Foundation.
PY - 2008/3/14
Y1 - 2008/3/14
N2 - 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine (5-iodo-A-85380, 5IA) has very high affinity and selectivity to nicotinic acetylcholine receptor (nAChR) α4β2 subtype, and a relative safe profile. To assess whether 5IA has neuroprotective properties, we examined the effect of 5IA on glutamate (Glu)-induced neurotoxicity using primary cultures of rat cortical neurons. A 10-min exposure of cultures to Glu followed by 2-h incubation with drug-free medium caused a marked loss of viability, as determined by trypan blue exclusion method. Glu-induced neurotoxicity was prevented by 5IA both in a time- and concentration-dependent manner. 5IA-induced neuroprotection required pretreatment of 5IA prior to Glu exposure with an optimal concentration of 10 nM and an optimal pretreatment time of 2 h. Treatment after Glu exposure could not rescue the cultured cells. The neuroprotective effect of 5IA was antagonized by mecamylamine, a nAChR antagonist, but not by scopolamine, a muscarinic acetylcholine receptor antagonist. Dihydro-β-erythroidine, an α4β2 nAChR antagonist, completely inhibited 5IA-induced neuroprotection, whereas α-bungarotoxin, an α7 nAChR antagonist, had no effect. Furthermore, 5IA did not show neuroprotective effects in the absence of extracellular Ca2+. These results suggest that the neuroprotective effects of 5IA are produced by activation of α4β2 nAChRs followed by the influx of extracellular Ca2+. In conclusion, 5IA is possibly not only useful for the treatment and prevention of glutamate neurotoxicity, but also as an available tool for elucidating the mechanism of neuroprotection associated with α4β2 nAChRs.
AB - 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine (5-iodo-A-85380, 5IA) has very high affinity and selectivity to nicotinic acetylcholine receptor (nAChR) α4β2 subtype, and a relative safe profile. To assess whether 5IA has neuroprotective properties, we examined the effect of 5IA on glutamate (Glu)-induced neurotoxicity using primary cultures of rat cortical neurons. A 10-min exposure of cultures to Glu followed by 2-h incubation with drug-free medium caused a marked loss of viability, as determined by trypan blue exclusion method. Glu-induced neurotoxicity was prevented by 5IA both in a time- and concentration-dependent manner. 5IA-induced neuroprotection required pretreatment of 5IA prior to Glu exposure with an optimal concentration of 10 nM and an optimal pretreatment time of 2 h. Treatment after Glu exposure could not rescue the cultured cells. The neuroprotective effect of 5IA was antagonized by mecamylamine, a nAChR antagonist, but not by scopolamine, a muscarinic acetylcholine receptor antagonist. Dihydro-β-erythroidine, an α4β2 nAChR antagonist, completely inhibited 5IA-induced neuroprotection, whereas α-bungarotoxin, an α7 nAChR antagonist, had no effect. Furthermore, 5IA did not show neuroprotective effects in the absence of extracellular Ca2+. These results suggest that the neuroprotective effects of 5IA are produced by activation of α4β2 nAChRs followed by the influx of extracellular Ca2+. In conclusion, 5IA is possibly not only useful for the treatment and prevention of glutamate neurotoxicity, but also as an available tool for elucidating the mechanism of neuroprotection associated with α4β2 nAChRs.
KW - 5-iodo-A-85380 (5IA)
KW - Extracellular calcium ion
KW - Glutamate toxicity
KW - Neuroprotection
KW - Nicotinic acetylcholine receptor
KW - α4β2 subtype
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U2 - 10.1016/j.brainres.2007.10.107
DO - 10.1016/j.brainres.2007.10.107
M3 - Article
C2 - 18269932
AN - SCOPUS:40049111097
VL - 1199
SP - 46
EP - 52
JO - Molecular Brain Research
JF - Molecular Brain Research
SN - 0006-8993
ER -