title: Differential localization of 5-hydroxytryptamine3 and 5-hydroxytryptamine4 receptors in the human rectum.
abstract: The functions of the 5-hydroxytryptamine3 (5-HT3) and 5-hydroxytryptamine4 (5-HT4) receptors in gastrointestinal tract are complex depending on the species and anatomical regions, and the localization of these receptors in the human rectum was unclear. We examined the localization of the 5-HT3 and 5-HT4 receptors in human rectum by in vitro receptor autoradiography using [125I](S)iodozacopride and [125I] SB207710 as a ligand, respectively. Specific [125I](S)iodozacopride binding sites were clearly evident in the myenteric plexus, whereas, low levels of [125I]SB207710 binding sites were distributed over the muscle but not to the myenteric plexus. The 5-HT3 receptor located on the myenteric plexus and the 5-HT4 receptor on the smooth muscle may participate in contractility and relaxation of human rectum, respectively.
authors.affiliation: Department of Pharmacology, Nagasaki University School of Medicine, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Sakurai-Yamashita
authors.forename: K
authors.initials: K
authors.lastname: Yamashita
authors.forename: M
authors.initials: M
authors.lastname: Yoshimura
authors.forename: K
authors.initials: K
authors.lastname: Taniyama
mesh_terms: D000368:Aged; D001345:Autoradiography; D001549:Benzamides / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D006801:Humans; D007457:Iodine Radioisotopes; D008875:Middle Aged; D010880:Piperidines / Q000494:pharmacology; D019275:Radiopharmaceuticals / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D044406:Receptors, Serotonin, 5-HT3; D044422:Receptors, Serotonin, 5-HT4; D012007:Rectum / Q000187:drug effects / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology
chemical_list: D001549:Benzamides; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004146:Dioxanes; D007457:Iodine Radioisotopes; D010880:Piperidines; D019275:Radiopharmaceuticals; D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; C088873:SB 207710; D012702:Serotonin Antagonists; D044422:Receptors, Serotonin, 5-HT4; C055971:zacopride