title: Serotonin and its metabolism in basal deuterostomes: insights from Strongylocentrotus purpuratus and Xenoturbella bocki.
abstract: Serotonin (5-HT), an important molecule in metazoans, is involved in a range of biological processes including neurotransmission and neuromodulation. Both its creation and release are tightly regulated, as is its removal. Multiple neurochemical pathways are responsible for the catabolism of 5-HT and are phyla specific; therefore, by elucidating these catabolic pathways we glean greater understanding of the relationships and origins of various transmitter systems. Here, 5-HT catabolic pathways were studied in Strongylocentrotus purpuratus and Xenoturbella bocki, two organisms occupying distinct positions in deuterostomes. The 5-HT-related compounds detected in these organisms were compared with those reported in other phyla. In S. purpuratus, 5-HT-related metabolites include N-acetyl serotonin, gamma-glutamyl-serotonin and 5-hydroxyindole acetic acid; the quantity and type were found to vary based on the specific tissues analyzed. In addition to these compounds, varying levels of tryptamine were also seen. Upon addition of a 5-HT precursor and a monoamine oxidase inhibitor, 5-HT itself was detected. In similar experiments using X. bocki tissues, the 5-HT-related compounds found included 5-HT sulfate, gamma-glutamyl-serotonin and 5-hydroxyindole acetic acid, as well as 5-HT and tryptamine. The sea urchin metabolizes 5-HT in a manner similar to both gastropod mollusks, as evidenced by the detection of gamma-glutamyl-serotonin, and vertebrates, as indicated by the presence of 5-hydroxyindole acetic acid and N-acetyl serotonin. In contrast, 5-HT metabolism in X. bocki appears more similar to common protostome 5-HT catabolic pathways.
authors.affiliation: Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Leah N
authors.initials: LN
authors.lastname: Squires
authors.forename: Stanislav S
authors.initials: SS
authors.lastname: Rubakhin
authors.forename: Andinet Amare
authors.initials: AA
authors.lastname: Wadhams
authors.forename: Kristen N
authors.initials: KN
authors.lastname: Talbot
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakano
authors.forename: Leonid L
authors.initials: LL
authors.lastname: Moroz
authors.forename: Jonathan V
authors.initials: JV
authors.lastname: Sweedler
mesh_terms: D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D003010:Clorgyline / Q000494:pharmacology; D004295:Dihydroxyphenylalanine / Q000494:pharmacology; D004447:Echinodermata / Q000187:drug effects / Q000378:metabolism*; D005453:Fluorescence; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D009928:Organ Specificity / Q000187:drug effects; D011826:Radial Nerve / Q000187:drug effects / Q000378:metabolism; D012701:Serotonin / Q000737:chemistry / Q000378:metabolism*; D047270:Strongylocentrotus purpuratus / Q000187:drug effects / Q000378:metabolism*
chemical_list: D012701:Serotonin; D004295:Dihydroxyphenylalanine; D006916:5-Hydroxytryptophan; D003010:Clorgyline