Korean J Physiol Pharmacol.  2011 Aug;15(4):195-201. 10.4196/kjpp.2011.15.4.195.

Inhibitory Effects of Quercetin on Muscle-type of Nicotinic Acetylcholine Receptor-Mediated Ion Currents Expressed in Xenopus Oocytes

Affiliations
  • 1Department of Physiology, College of Veterinary Medicine and Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea. synah@konkuk.ac.kr
  • 2Department of Clinical Pharmacology and Therapeutics, University of Ulsan College of Medicine, Seoul 138-736, Korea.

Abstract

The flavonoid quercetin is a low molecular weight compound generally found in apple, gingko, tomato, onion and other red-colored fruits and vegetables. Like other flavonoids, quercetin has diverse pharmacological actions. However, relatively little is known about the influence of quercetin effects in the regulation of ligand-gated ion channels. Previously, we reported that quercetin regulates subsets of nicotinic acetylcholine receptors such as alpha3beta4, alpha7 and alpha9alpha10. Presently, we investigated the effects of quercetin on muscle-type of nicotinic acetylcholine receptor channel activity expressed in Xenopus oocytes after injection of cRNA encoding human fetal or adult muscle-type of nicotinic acetylcholine receptor subunits. Acetylcholine treatment elicited an inward peak current (IACh) in oocytes expressing both muscle-type of nicotinic acetylcholine receptors and co-treatment of quercetin with acetylcholine inhibited IACh. Pre-treatment of quercetin further inhibited IACh in oocytes expressing adult and fetal muscle-type nicotinic acetylcholine receptors. The inhibition of IACh by quercetin was reversible and concentration-dependent. The IC50 of quercetin was 18.9+/-1.2 microM in oocytes expressing adult muscle-type nicotinic acetylcholine receptor. The inhibition of IACh by quercetin was voltage-independent and non-competitive. These results indicate that quercetin might regulate human muscle-type nicotinic acetylcholine receptor channel activity and that quercetin-mediated regulation of muscle-type nicotinic acetylcholine receptor might be coupled to regulation of neuromuscular junction activity.

Keyword

Flavonoids; Quercetin; Muscle-type nicotinic acetylcholine receptors; Xenopus oocyte

MeSH Terms

Acetylcholine
Adult
Flavonoids
Fruit
Ginkgo biloba
Humans
Inhibitory Concentration 50
Ligand-Gated Ion Channels
Lycopersicon esculentum
Molecular Weight
Neuromuscular Junction
Onions
Oocytes
Quercetin
Receptors, Nicotinic
RNA, Complementary
Vegetables
Xenopus
Acetylcholine
Flavonoids
Ligand-Gated Ion Channels
Quercetin
RNA, Complementary
Receptors, Nicotinic
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