title: Role of a serotonin precursor in development of gut microvilli.
abstract: Monoamines exert diverse functions in various cells in peripheral organs as well as in the central nervous system. 5-Hydroxy-l-tryptophan (5-HTP) has been simply regarded as a precursor of serotonin, and it is believed that the biological significance of 5-HTP is essentially ascribable to the production of serotonin. Systemic treatment with 5-HTP is often applied to patients with low serotonin levels in the brain. Here we show that endogenous and exogenous 5-HTP but not serotonin induced the development of microvilli in the gut villi epithelium. In contrast, serotonin but not 5-HTP regulated phagocytosis by macrophages. 5-HTP specifically induced actin remodeling and decreased phosphorylation of extracellular signal-regulated kinase (ERK) in the gut, whereas serotonin stimulated actin remodeling and increased ERK phosphorylation in macrophages. Functionally, inhibition of ERK activity promoted the development of microvilli in the gut and ameliorated phagocytosis by macrophages. Thus, 5-HTP and serotonin contribute to distinct cell-type-specific functions via common mediators. Our study might create an opportunity to explore the effects of exogenously applied 5-HTP in humans.
authors.affiliation: Department of Biosciences, Teikyo University of Science and Technology, Uenohara 409-0193, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nakamura
authors.forename: Taku
authors.initials: T
authors.lastname: Sato
authors.forename: Akiko
authors.initials: A
authors.lastname: Ohashi
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Tsurui
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hasegawa
mesh_terms: D006916:5-Hydroxytryptophan / Q000378:metabolism* / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000818:Animals; D000918:Antibody Specificity; D015153:Blotting, Western; D018938:Caco-2 Cells; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism*; D007422:Intestines / Q000276:immunology; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008871:Microvilli / Q000378:metabolism*; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017386:Sequence Homology, Amino Acid; D012701:Serotonin / Q000378:metabolism*; D014365:Tryptophan Hydroxylase / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000199:Actins; D012701:Serotonin; D006916:5-Hydroxytryptophan; D014365:Tryptophan Hydroxylase; D048049:Extracellular Signal-Regulated MAP Kinases