An aqueous extract of Poncirus fructus activates the prokinetic activity of 5-HT receptor subtype 4 without hERG interaction |
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Authors: | Won-Sik Shim Sang-Won Jung Yongwoo Jang Eun-Kyoung Seo Chang-Koo Shim |
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Institution: | a National Research Laboratory for Transporters Targeted Drug Design & Research Institute of Pharmaceutical Sciences and Department of Pharmaceutics, College of Pharmacy, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul 151-742, Republic of Korea b Pharmacology Team, Department of Drug Discovery, LG Life Sciences, Ltd., Science Town, Moonji 104-1, Yoosung, Taejon 305-380, Republic of Korea c Sensory Research Center, CRI, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea d Natural Products Chemistry Laboratory, College of Pharmacy, Ewha Woman's University, Seoul 120-750, Republic of Korea |
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Abstract: | Aim of the studyPoncirus fructus (PF) - also known as the dried, immature fruit of Poncirus trifoliata (L.) Raf. (Rutaceae) - is a natural substance that has long been used for various gastrointestinal disorders in eastern Asia. An aqueous extract of PF (PF-W) has particularly potent gastroprokinetic effects, but its molecular mechanism was not well understood. Identification of the underlying prokinetic mechanism of PF-W was pursued in the present study.Materials and methodsChanges in in vitro cAMP levels and in vivo intestinal transit rate (ITR) caused by PF-W were measured after pretreatment with GR125487, an antagonist for serotonin receptor subtype 4 (5-HT4R). An 3H] astemizole binding assay and electrophysiology experiments were performed to determine if PF-W has any interaction with the human ether-à-go-go related gene (hERG) potassium channel.ResultsPF-W induced an increase in intracellular cAMP in 5-HT4R-expressing HEK293T cells, indicating that PF-W does activate 5-HT4R. Moreover, pretreatment with GR125487 successfully blocked the increase, suggesting that the response was 5-HT4R-specific. More importantly, pretreatment of GR125487 in rats inhibited the elevation of ITR by PF-W, indicating that the prokinetic effect of PF-W was indeed exerted via 5-HT4R. On the other hand, both 3H]-astemizole binding assay and electrophysiological experiments revealed that PF-W did not interfere at all with the hERG channel.ConclusionIt was found that PF-W exerts its prokinetic activity through a 5-HT4R-mediated pathway, with no interaction with hERG channels. Therefore, PF-W is a good candidate that might be developed as a prokinetic agent with fewer expected cardiac side effects. |
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Keywords: | 5-HT4 hERG Intestine Motility Poncirus fructus Prokinetic |
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