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Comparison of 5-HT4 and 5-HT7 receptor expression and function in the circular muscle of the human colon.

Irving, H.R., Tan, Y.Y., Tochon-Danguy, N., Liu, H., Chetty, N., Desmond, P.V., Pouton, C.W. and Coupar, I.M. (2007). Comparison of 5-HT4 and 5-HT7 receptor expression and function in the circular muscle of the human colon. . Life Sciences,80(13):1198-1205.

Document type: Journal Article
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Title Comparison of 5-HT4 and 5-HT7 receptor expression and function in the circular muscle of the human colon.
Author Irving, H.R.
Tan, Y.Y.
Tochon-Danguy, N.
Liu, H.
Chetty, N.
Desmond, P.V.
Pouton, C.W.
Coupar, I.M.
Journal Name Life Sciences
Publication Date 2007
Volume Number 80
Issue Number 13
eISSN 1879-0631
Start Page 1198
End Page 1205
Total Pages 8
Place of Publication United States of America
Publisher Elsevier Inc.
Language English
Field of Research 1115 - Pharmacology and Pharmaceutical Sciences
Abstract Serotonin receptors are potential targets for treating functional bowel disorders. This study investigated the functional roles and expression of the 5-HT4 and the 5-HT7 receptor, which coexist in human colon circular smooth muscle. 5-HT3 receptor expression was also investigated. Part of the relaxant response to 5-HT was due to activation of 5-HT4 receptors as the apparent pKB value of the selective 5-HT4 antagonist, GR 113808, was 9.36. 5-HT4 mRNA levels were low in five tissues and undetectable in four others, but all responded to 5-HT with an EC50 value of 102.54 ± 19.32 nM. The contribution of 5-HT7 receptors to the response was not readily demonstrated using the selective 5-HT7 antagonist, SB-269970, as its apparent pKB value of 7.19 (5-HT4 block with 1 μM GR 113808) was lower than the value obtained using the 5-HT7 guinea pig ileum assay (8.62). Nevertheless, the 5-HT7 receptor was expressed more consistently than the 5-HT4, but at similar levels. The 5-HT3Ashort and 5-HT3B subunits were co-expressed at similar levels, but the 5-HT3Along subunit was detected in only five of the nine samples tested. The findings show that 5-HT4-induced relaxation occurs at low to undetectable levels of tissue mRNA, as measured by qPCR. Although 5-HT7 receptor mRNA is detected at low, but consistent levels, the functional activity of this receptor is not readily identified given the currently available drugs.
Keywords Serotonin receptors
5-HT3 receptors
5-HT4 receptors
5-HT7 receptors
Gastroointestional tract
Human tissue
Colinic smooth muscle
DOI http://dx.doi.org/10.1016/j.lfs.2006.12.025   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
Description for Link Link to publisher's version
URL http://www.sciencedirect.com/science/article/pii/S0024320507000288
 
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Created: Mon, 08 Dec 2014, 14:27:43 CST by Yean Tan