Cnidarian chemical neurotransmission, an updated overview

Kass-Simon, G.; Pierobon, Paola

doi:10.1016/j.cbpa.2006.09.008

Cited by 128 publications

(82 citation statements)

References 160 publications

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“…Glycine is a major inhibitory amino acid neurotransmitter in the vertebrate CNS that works by inducing a hyperpolarising chloride current when bound to a post-synaptic receptor but it can also be a modulator in excitatory ionotropic glutamate receptors. In Hydra, glycine has been identified and localised to the nerve net where it functions in pacemaker activity of peristaltic contractions (elongations and contractions) of the muscle in the body column; it is also involved in the chemosensory response during feeding by inhibiting the closure of the mouth upon stimulation by glutathione (Pierobon et al, 2001;Ruggieri et al, 2004;Kass-Simon and Pierobon, 2006). Similar responses are observed by the application of alanine and taurine in Hydra (Kass-Simon and Pierobon, 2006).…”

Section: Neuroactive Amino Acids In Sponge Tissuementioning

confidence: 80%

Evidence for glutamate, GABA and NO in coordinating behaviour in the sponge, Ephydatia muelleri (Demospongiae, Spongillidae)

Elliott

Leys

2010

Journal of Experimental Biology

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SUMMARYThe view that sponges lack tissue level organisation, epithelia, sensory cells and coordinated behaviour is challenged by recent molecular studies showing the existence in Porifera of molecules and proteins that define cell signalling systems in higher order metazoans. Demonstration that freshwater sponges can contract their canals in an organised manner in response to both external and endogenous stimuli prompted us to examine the physiology of the contraction behaviour. Using a combination of digital timelapse microscopy, high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, immunocytochemistry and pharmacological manipulations, we tested the role of the diffusible amino acids glutamate and g-aminobutyric acid (GABA) and a short-lived diffusible gas, nitric oxide (NO), in triggering or modulating contractions in Ephydatia muelleri. We identified pools of glutamate, glutamine and GABA used to maintain a metabotropic glutamate and GABA receptor signalling system. Glutamate induced contractions and propagation of a stereotypical behaviour inflating and deflating the canal system, acting in a dosedependent manner. Glutamate-triggered contractions were blocked by the metabatropic glutamate receptor inhibitor AP3 and by incubation of the sponge in an allosteric competitive inhibitor of glutamate, Kynurenic acid. Incubation in GABA inhibited glutamate-triggered contractions of the sponge. Nitric oxide synthase, involved in the formation of the diffusible gas NO, was localised using NADPH-diaphorase to mesenchyme cells in the osculum and pinacoderm. A cGMP assay showed the same cells were labelled suggesting that the NO system is functional. Our findings suggest sponges coordinate behaviour using chemical messenger systems common to other animals. Supplementary material available online at

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Section: Neuroactive Amino Acids In Sponge Tissuementioning

confidence: 80%

Evidence for glutamate, GABA and NO in coordinating behaviour in the sponge, Ephydatia muelleri (Demospongiae, Spongillidae)

Elliott

Leys

2010

Journal of Experimental Biology

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“…Similarly, in Hydra, there are also ample immunohistochemical, biochemical and functional data to indicate their presence (Kass-Simon and Pierobon, 2007;Pierobon, 2012) and two putative metabotropic acetylcholine receptors (mAchRs) have been identified (Collin et al, 2013). Ionotropic receptors for small-molecule transmitters have, however, not been studied at the molecular level in Hydra (see below); we will therefore concentrate our discussion of neurotransmitters on neuropeptides.…”

Section: Neurotransmitters In Hydra -Small Molecules and Peptidesmentioning

confidence: 99%

Peptide-gated ion channels and the simple nervous system of Hydra

Gründer

Assmann

2015

Journal of Experimental Biology

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Neurons either use electrical or chemical synapses to communicate with each other. Transmitters at chemical synapses are either small molecules or neuropeptides. After binding to their receptors, transmitters elicit postsynaptic potentials, which can either be fast and transient or slow and longer lasting, depending on the type of receptor. Fast transient potentials are mediated by ionotropic receptors and slow long-lasting potentials by metabotropic receptors. Transmitters and receptors are well studied for animals with a complex nervous system such as vertebrates and insects, but much less is known for animals with a simple nervous system like Cnidaria. As cnidarians arose early in animal evolution, nervous systems might have first evolved within this group and the study of neurotransmission in cnidarians might reveal an ancient mechanism of neuronal communication. The simple nervous system of the cnidarian Hydra extensively uses neuropeptides and, recently, we cloned and functionally characterized an ion channel that is directly activated by neuropeptides of the Hydra nervous system. These results demonstrate the existence of peptide-gated ion channels in Hydra, suggesting they mediate fast transmission in its nervous system. As related channels are also present in the genomes of the cnidarian Nematostella, of placozoans and of ctenophores, it should be considered that the early nervous systems of cnidarians and ctenophores have co-opted neuropeptides for fast transmission at chemical synapses.

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“…Lethal phenotypes associated with scully (D. melanogaster gene homologous to HSD17B10) mutants indicate an essential role of 17β-HSD 10 in β-oxidation of lipids in gonadal and neural tissues (Torroja et al, 1998). Given the generally high lipid content of cnidarian tissue and their relatively sophisticated nervous system (reviewed by Grimmelikhuijzen and Westfall, 1995;Kass-Simon and Pierobon, 2007;Tarrant, 2005), it would be of great interest to determine the roles of 17β-HSD 10 enzymes in cnidarian lipid metabolism and neural function. Two N. vectensis genes clustered with HSD17B12 and formed a sister group to HSD17B3.…”

Section: Discussionmentioning

confidence: 99%

Steroid metabolism in cnidarians: Insights from Nematostella vectensis

Tarrant

Reitzel

Blomquist

et al. 2009

Molecular and Cellular Endocrinology

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Cnidarians occupy a key evolutionary position as a sister group to bilaterian animals. While cnidarians contain a diverse complement of steroids, sterols, and other lipid metabolites, relatively little is known of the endogenous steroid metabolism or function in cnidarian tissues. Incubations of cnidarian tissues with steroid substrates have indicated the presence of steroid metabolizing enzymes, particularly enzymes with 17β-hydroxysteroid dehydrogenase (17β-HSD) activity. Through analysis of the genome of the starlet sea anemone, Nematostella vectensis, we identified a suite of genes in the short chain dehydrogenase/reductase (SDR) superfamily including homologs of genes that metabolize steroids in other animals. A more detailed analysis of Hsd17b4 revealed complex evolutionary relationships, apparent intron loss in several taxa, and predominantly adult expression in N. vectensis. Due to its ease of culture and available molecular tools N. vectensis is an excellent model for investigation of cnidarian steroid metabolism and gene function. KeywordsEvolution, hydroxysteroid dehydrogenase, short chain dehydrogenase/reductase Abbreviations CYP HSD AKR 3

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Cnidarian chemical neurotransmission, an updated overview

Cited by 128 publications

References 160 publications

Evidence for glutamate, GABA and NO in coordinating behaviour in the sponge, Ephydatia muelleri (Demospongiae, Spongillidae)

Evidence for glutamate, GABA and NO in coordinating behaviour in the sponge, Ephydatia muelleri (Demospongiae, Spongillidae)

Peptide-gated ion channels and the simple nervous system of Hydra

Steroid metabolism in cnidarians: Insights from Nematostella vectensis

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