Serotonin involvement in the metamorphosis of the hydroid Eudendrium racemosum.
Hydroid planulae metamorphose in response to an inducing external stimulus, usually a bacterial cue. There is evidence that neurotransmitters participate in the signal transduction pathway of hydroid metamorphosis. Eudendrium racemosum is a colonial hydroid common in the Mediterranean Sea. It lacks the medusa stage and the planulae develop on female colonies during the fertile season. In this work, serotonin (5-HT) was localized in some planula ectodermal cells. Co-localization of serotonin and beta-tubulin suggested that 5-HT was present in sensory nervous cells and in different ectodermal cells. To investigate the role of neurotransmitters in metamorphosis, E. racemosum planulae were treated with serotonin and dopamine and with agonists and antagonists of the corresponding receptors. Serotonin and a serotonin receptor agonist induced metamorphosis, while a 5-HT receptor antagonist inhibited it. Dopamine and all dopaminergic drugs used did not show any significant effect on the onset of metamorphosis. Results from this work showed that 5-HT could stimulate metamorphosis in E. racemosum planulae in the presence of a natural inducer. A mechanism by which this neurotransmitter could act in this phase is proposed.
Zega
Giuliana
G
Dipartimento di Biologia, Sez. Zoologia S/N, Universit Statale di Milano, Milan, Italy. giuliana.zega@unimi.it
Pennati
Roberta
R
Fanzago
Arianna
A
De Bernardi
Fiorenza
F
D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004475:Ectoderm / Q000166:cytology / Q000378:metabolism; D005260:Female; D037402:Hydrozoa / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D008675:Metamorphosis, Biological / Q000187:drug effects / Q000502:physiology*; D009475:Neurons, Afferent / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011954:Receptors, Dopamine / Q000187:drug effects* / Q000378:metabolism; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D014404:Tubulin / Q000378:metabolism
D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D018377:Neurotransmitter Agents; D011954:Receptors, Dopamine; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D014404:Tubulin; D012701:Serotonin; D004298:Dopamine