Serotonin-induced muscular activity in Schistosoma mansoni larval stages: importance of 5-HT transport and role in daughter sporocyst production.
Mother sporocysts of Schistosoma mansoni transport exogenously supplied serotonin (5-hydroxytrypamine; 5-HT), and respond to it with increases in motility. In the present study, we investigated the importance of 5-HT transporter activity in the manifestation of these 5-HT-induced motility changes, and further examined the role of 5-HT in the development of daughter sporocysts in vitro. Serotonin-induced motility of in vitro-derived sporocysts is not inhibited by antidepressant compounds, e.g., fluoxetine, that block 5-HT transport, suggesting that the receptors responsible for motility responses to 5-HT are surface exposed. Using a sporocyst in vitro culture system, we show that depletion of larval stores of 5-HT reduces production of daughter sporocysts, the second intramolluscan larval stage. Moreover, we demonstrate a strong correlation between endogenous 5-HT levels and basal mother sporocyst muscle activity. Overall, these data suggest that larval stages of S. mansoni can detect exogenous 5-HT via surface-exposed receptors, and they are consistent with the hypothesis that endogenous stores of 5-HT are important for the proper regulation of muscular contractions in mother sporocysts, and for the successful emergence of daughter sporocysts.
Boyle
Jon P
JP
Department of Microbiology and Immunology, Stanford University, 299 Campus Drive, Stanford, California 94305, USA. boylej@stanford.edu
Yoshino
Timothy P
TP
D000704:Analysis of Variance; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D007814:Larva / Q000187:drug effects / Q000502:physiology; D008562:Membrane Glycoproteins / Q000502:physiology*; D026901:Membrane Transport Proteins / Q000502:physiology*; D051379:Mice; D009068:Movement / Q000187:drug effects / Q000502:physiology; D009132:Muscles / Q000187:drug effects / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000502:physiology*; D012100:Reproduction, Asexual / Q000187:drug effects / Q000502:physiology; D012550:Schistosoma mansoni / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D050486:Serotonin Plasma Membrane Transport Proteins
D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D050486:Serotonin Plasma Membrane Transport Proteins; C493231:Slc6a4 protein, mouse; D012701:Serotonin