title: Serotonin 5-HT2B Receptor-Stimulated DNA Synthesis and Proliferation Are Mediated by Autocrine Secretion of Transforming Growth Factor-α in Primary Cultures of Adult Rat Hepatocytes.
abstract: The mechanism of serotonin 5-HT2 receptor subtype-stimulated DNA synthesis and proliferation was investigated in primary cultures of adult rat hepatocytes to elucidate the intracellular signal transduction pathways. DNA synthesis and proliferation were detected in hepatocyte parenchymal cells grown in serum-free, defined medium containing 5-HT (10(-6) M) or the selective 5-HT2B receptor agonist BW723C86 (10(-6) M). In addition, exogenous transforming growth factor (TGF)-α (1.0 ng/mL) significantly increased hepatocyte DNA synthesis and proliferation, which reached plateau after 4 h of culture. Use of blocking monoclonal antibodies demonstrated that TGF-α, but not insulin-like growth factor-I, was involved in hepatocyte proliferation mediated by 5-HT or BW723C86. TGF-α levels in the culture medium increased significantly versus baseline within 5 min in response to 5-HT (10(-6) M) or BW723C86 (10(-6) M), and the maximum TGF-α level (30 pg/mL) was reached 10 min after 5-HT or BW723C86 stimulation. Secretion of TGF-α into the culture medium was inhibited by addition of the selective phospholipase C (PLC) inhibitor, U-73122 (10(-6) M), or somatostatin (10(-7) M). These results indicate that the proliferative mechanism of action of 5-HT is mediated mainly through a 5-HT2B receptor/Gq/PLC-stimulated increase in autocrine secretion of TGF-α from primary cultured hepatocytes.
authors.affiliation: Department of Clinical Pharmacology, Faculty of Pharmaceutical Sciences, Josai University.
authors.forename: Kota
authors.initials: K
authors.lastname: Naito
authors.forename: Hajime
authors.initials: H
authors.lastname: Moteki
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Kimura
authors.forename: Hideshi
authors.initials: H
authors.lastname: Natsume
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ogihara
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D004963:Estrenes / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009930:Organic Chemicals / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D017208:Rats, Wistar; D044403:Receptor, Serotonin, 5-HT2B / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology; D058826:Serotonin 5-HT2 Receptor Agonists / Q000494:pharmacology; D058830:Serotonin 5-HT2 Receptor Antagonists / Q000494:pharmacology; D013876:Thiophenes / Q000494:pharmacology; D016211:Transforming Growth Factor alpha / Q000378:metabolism*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
chemical_list: C092430:1-(5-(2-thenyloxy)-1H-indol-3-yl)propan-2-amine; D004963:Estrenes; D007211:Indoles; C118304:LY 272015; D009930:Organic Chemicals; D011760:Pyrrolidinones; D044403:Receptor, Serotonin, 5-HT2B; D058826:Serotonin 5-HT2 Receptor Agonists; D058830:Serotonin 5-HT2 Receptor Antagonists; D013876:Thiophenes; D016211:Transforming Growth Factor alpha; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D012701:Serotonin; D004247:DNA; D010738:Type C Phospholipases