The evolution of the serotonergic nervous system

Hay‐Schmidt, Anders

doi:10.1098/rspb.2000.1111

Cited by 210 publications

(203 citation statements)

References 49 publications

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“…Moreover, serotonin is also present in ciliated cells of the sensory organs of gastropod larvae and ascidian tadpoles (Dickinson et al, 1999;Hay-Schmidt, 2000;Pennati et al, 2001) and for some species its role in the stimulation of metamorphosis has been proved (Couper and Leise, 1996;Zega et al, 2005). The involvement of 5-HT in the metamorphosis of non-homologous larvae of different phyla suggests that serotonin signaling was selected several times for the control of an initial step of the transduction pathway of this process.…”

Section: Comparison Of the Different Effects On Metamorphosis Among 4mentioning

confidence: 99%

Serotonin involvement in the metamorphosis of the hydroid Eudendrium racemosum

Zega

Pennati²,

Fanzago³

et al. 2007

Int. J. Dev. Biol.

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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 β-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.

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Section: Comparison Of the Different Effects On Metamorphosis Among 4mentioning

confidence: 99%

Serotonin involvement in the metamorphosis of the hydroid Eudendrium racemosum

Zega

Pennati²,

Fanzago³

et al. 2007

Int. J. Dev. Biol.

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“…Indeed, immunocytochemistry using an antiserotonin antibody stains this ganglion (data not shown). It is not yet possible to compare the distribution of serotonergic neurons to that described in other hemichordates as such studies have thus far focused on larval stages (Byrne et al, 2007;Hay-Schmidt, 2000;Nakajima et al, 2004). There is no anatomical similarity with the chordate neural tube (Dilly, 1975), but whether the collar ganglion develops using similar genetic mechanisms to the neural tube is a fascinating question.…”

Section: Perspectivesmentioning

confidence: 99%

Developmental biology of pterobranch hemichordates: History and perspectives

Sato

Bishop

Holland

2008

Genesis

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Summary: Hemichordates, like echinoderms and chordates, are deuterostomes, and study of their developmental biology could shed light on chordate origins. To date, molecular developmental studies in hemichordates have been confined to the enteropneusts or acorn worms. Here, we introduce the developmental biology of the other group of hemichordate, the pterobranchs. Pterobranchs generally live in cold, deep waters; this has hampered studies of this group. However, about 40 years ago, the colonial pterobranchs Rhabdopleura compacta and R. normani were discovered from shallow water, which has facilitated their study. Using Rhabdopleura compacta from south-west England, we have initiated molecular developmental studies in pterobranchs. Here, we outline methods for collecting adults, larvae, and embryos and demonstrate culturing of larvae under laboratory conditions. Given that the larval and adult forms differ from enteropneusts, we suggest that molecular developmental studies of pterobranchs may offer new insights into chordate origins. genesis 46:587-591, 2008. V V C 2008 Wiley-Liss, Inc.

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“…Similar to peptidergic sensory-motor cells, serotonergic neurons with sensory morphology also innervate ciliary bands in a wide range of ciliated larvae, both protostome and deuterostome [47]. Serotonin seems to play a general role in the upregulation of ciliary beat frequency (in mollusc [48], echinoderm [49,50] and annelid (G. Jékely unpublished) larvae), and the control of cilia by a sensory-motor serotonergic system may trace back to the common ancestor of protostomes and deuterostomes.…”

Section: The Evolution Of the First Neurons To Regulate Ciliamentioning

confidence: 99%

“…In spiralian larvae the apical organ (a sensory organ specific for the larval stage [58]) generally contains only a few serotonergic cell bodies (about 2-4 [47]) that innervate the ciliary band with multiciliated cells [59]. In larvae that use monociliated cells for locomotion (echinoderms, phoronids, hemichordates), there are many more serotonergic cell bodies (e.g.…”

Section: The Evolution Of Ciliary Bands In Protostomesmentioning

confidence: 99%

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Origin and early evolution of neural circuits for the control of ciliary locomotion

Jékely

2010

Proc. R. Soc. B.

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Behaviour evolved before nervous systems. Various single-celled eukaryotes (protists) and the ciliated larvae of sponges devoid of neurons can display sophisticated behaviours, including phototaxis, gravitaxis or chemotaxis. In single-celled eukaryotes, sensory inputs directly influence the motor behaviour of the cell. In swimming sponge larvae, sensory cells influence the activity of cilia on the same cell, thereby steering the multicellular larva. In these organisms, the efficiency of sensory-to-motor transformation (defined as the ratio of sensory cells to total cell number) is low. With the advent of neurons, signal amplification and fast, long-range communication between sensory and motor cells became possible. This may have first occurred in a ciliated swimming stage of the first eumetazoans. The first axons may have had en passant synaptic contacts to several ciliated cells to improve the efficiency of sensory-to-motor transformation, thereby allowing a reduction in the number of sensory cells tuned for the same input. This could have allowed the diversification of sensory modalities and of the behavioural repertoire. I propose that the first nervous systems consisted of combined sensory-motor neurons, directly translating sensory input into motor output on locomotor ciliated cells and steering muscle cells. Neuronal circuitry with low levels of integration has been retained in cnidarians and in the ciliated larvae of some marine invertebrates. This parallel processing stage could have been the starting point for the evolution of more integrated circuits performing the first complex computations such as persistence or coincidence detection. The sensory-motor nervous systems of cnidarians and ciliated larvae of diverse phyla show that brains, like all biological structures, are not irreducibly complex.

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The evolution of the serotonergic nervous system

Cited by 210 publications

References 49 publications

Serotonin involvement in the metamorphosis of the hydroid Eudendrium racemosum

Serotonin involvement in the metamorphosis of the hydroid Eudendrium racemosum

Developmental biology of pterobranch hemichordates: History and perspectives

Origin and early evolution of neural circuits for the control of ciliary locomotion

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