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Title: In vivo relationship between thalamic nicotinic acetylcholine receptor occupancy rates and antiallodynic effects in a rat model of neuropathic pain: persistent agonist binding inhibits the expression of antiallodynic effects.
Authors: Ueda, Masashi
Iida, Yasuhiko
Yoneyama, Tomoki
Kawai, Tomoki
Ogawa, Mikako
Magata, Yasuhiro
Saji, Hideo  kyouindb  KAKEN_id
Author's alias: 上田, 真史
佐治, 英郎
Keywords: thalamus
5-[125I]iodo-A-85380 ([125I]5IA)
desensitization
Issue Date: Jan-2011
Publisher: Wiley-Blackwell
Journal title: Synapse
Volume: 65
Issue: 1
Start page: 77
End page: 83
Abstract: We have recently clarified that nicotinic acetylcholine receptors (nAChRs) expressed in the thalamus play an important role in antiallodynic effects produced by the nAChR agonist, 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine (5IA). This study aimed to reveal the in vivo relationship between thalamic nAChR occupancy rates and antiallodynic effects using 5IA and [¹²⁵I]5IA. We partially ligated the sciatic nerve of a rat to induce neuropathic pain. Antiallodynic effects were evaluated at 15, 30, 60, and 90 min after intracerebroventricular (i.c.v.) administration of multiple doses (1-100 nmol) of 5IA by the von Frey filament test. Receptor occupancy rates were measured by autoradiography at 15 and 90 min after administration. Antiallodynic effects of repetitive treatment of 5IA (5 and 50 nmol) were also examined. A significant and dose-dependent antiallodynic effect was observed 15 min after administration. It showed a good correlation with receptor occupancy rates (r = 0.97), indicating the binding of 5IA to nAChRs expressed in the thalamus involved in the antiallodynic effect. Five, 50, and 100 nmol of 5IA occupied the thalamic nAChRs until 90 min after administration, while the antiallodynic effect diminished. Five nanomoles of 5IA (which occupied 40% of thalamic nAChRs) showed a significant antiallodynic effect (percentage of the maximal possible effect (%MPE): 35 ± 7) after the second administration, while 50 nmol of 5IA (which occupied 80% of thalamic nAChRs) did not (%MPE: 7 ± 1). These findings suggest that not clearance of 5IA but desensitization of nAChRs caused by persistent binding of 5IA is responsible for the disappearance of antiallodynic effects.
Rights: © 2010 Wiley-Liss, Inc.
This is the pre-peer reviewed version of the following article : FULL CITE, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/syn.20819/pdf
This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
URI: http://hdl.handle.net/2433/139437
DOI(Published Version): 10.1002/syn.20819
PubMed ID: 20506320
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