KMID : 0606920160240040410
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Biomolecules & Therapeutics 2016 Volume.24 No. 4 p.410 ~ p.417
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Differential Effects of Quercetin and Quercetin Glycosides on Human ¥á7 Nicotinic Acetylcholine Receptor-Mediated Ion Currents
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Lee Byung-Hwan
Choi Sun-Hye Kim Hyeon-Joong Jung Seok-Won Hwang Sung-Hee Pyo Mi-Kyung Rhim Hye-Whon Kim Hyoung-Chun Kim Ho-Kyoung Lee Sang-Mok Nah Seung-Yeol
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Abstract
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Quercetin is a flavonoid usually found in fruits and vegetables. Aside from its antioxidative effects, quercetin, like other flavonoids, has a various neuropharmacological actions. Quercetin-3-O-rhamnoside (Rham1), quercetin-3-O-rutinoside (Rutin), and quercetin-3-(2(G)-rhamnosylrutinoside (Rham2) are mono-, di-, and tri-glycosylated forms of quercetin, respectively. In a previous study, we showed that quercetin can enhance ¥á7 nicotinic acetylcholine receptor (¥á7 nAChR)-mediated ion currents. However, the role of the carbohydrates attached to quercetin in the regulation of ¥á7 nAChR channel activity has not been determined. In the present study, we investigated the effects of quercetin glycosides on the acetylcholine induced peak inward current (IACh) in Xenopus oocytes expressing the ¥á7 nAChR. IACh was measured with a two-electrode voltage clamp technique. In oocytes injected with ¥á7 nAChR copy RNA, quercetin enhanced IACh, whereas quercetin glycosides inhibited IACh. Quercetin glycosides mediated an inhibition of IACh, which increased when they were pre-applied and the inhibitory effects were concentration dependent. The order of IACh inhibition by quercetin glycosides was Rutin¡ÃRham1>Rham2. Quercetin glycosides-mediated IACh enhancement was not affected by ACh concentration and appeared voltage-independent. Furthermore, quercetin-mediated IACh inhibition can be attenuated when quercetin is co-applied with Rham1 and Rutin, indicating that quercetin glycosides could interfere with quercetin-mediated ¥á7 nAChR regulation and that the number of carbohydrates in the quercetin glycoside plays a key role in the interruption of quercetin action. These results show that quercetin and quercetin glycosides regulate the ¥á7 nAChR in a differential manner.
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KEYWORD
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Flavonoids, Quercetin, Quercetin glycosides, ¥á7 nAChR
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