Neurotransmitters in coelenterates

Martin, Sarah M.; Spencer, Andrew N.

doi:10.1016/0742-8413(83)90139-1

Cited by 47 publications

(13 citation statements)

References 61 publications

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“…Evidence for the presence of classical neurotransmitters in cnidarian nerves or tissues has accumulated from many mor-phological and functional studies, starting from the early sixties; however, owing to technical difficulties and to contradictory findings, a general disbelief about the occurrence and possible transmitter role of molecules such as acetylcholine, glutamate, GABA and glycine in cnidarians has long prevailed (Martin and Spencer, 1983). By contrast, the abundance of biogenic amines and different neuropeptides found in neurons of many hydrozoan and anthozoan species by histochemical, immunocytochemical, biochemical and molecular studies led to the assumption that in cnidarians neurotransmission was essentially aminergic and/or peptidergic, despite the lack of direct evidence of the involvement of these peptides in neurotransmission or neuromodulation.…”

Section: Classical Neurotransmitters In Hydra: or Absence Of Evidencmentioning

confidence: 99%

Coordinated modulation of cellular signaling through ligand-gated ion channels in Hydra vulgaris (Cnidaria, Hydrozoa)

Pierobon

2012

Int. J. Dev. Biol.

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Cnidarians lack well developed organs, but they have evolved the molecular and cellular components needed to assemble a nervous system. The apparent 'simplicity' of the cnidarian nervous net does not occur at the cellular level, but rather in the organisation of conducting systems. Cnidarian neurons are in fact electrically excitable, show the typical extended morphology and are connected by chemical synapses or gap junctions. They have been regarded as peptidergic, given the wealth of neuropeptides generally distributed along neurites and in cell bodies, supporting the hypothesis of a modulatory role in neurotransmission. However, the presence of clear-cored, as well as dense-cored synaptic vesicles in cnidarian neurons suggests both fast and slow synaptic transmission mechanisms. In fact, biochemical and functional evidence indicates that classical neurotransmitters and their metabolic partners are present in cnidarian tissues, where they are involved in coordinating motility and behavior. We have identified and characterized in Hydra tissues receptors to the inhibitory and excitatory amino acid neurotransmitters, GABA, glycine and NMDA, that are similar to mammalian ionotropic receptors in terms of their biochemical and pharmacological properties. These receptors appear to regulate pacemaker activities and their physiological correlates; in the live animal, they also affect feeding behavior, namely the duration and termination of the response elicited by reduced glutathione, with opposite actions of GABA and glycine or NMDA, respectively. These results suggest that modulation of cellular signaling through ligand-gated-ion channels is an ancient characteristic in the animal kingdom, and that the pharmacological properties of these receptors have been highly conserved during evolution.

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Section: Classical Neurotransmitters In Hydra: or Absence Of Evidencmentioning

confidence: 99%

Coordinated modulation of cellular signaling through ligand-gated ion channels in Hydra vulgaris (Cnidaria, Hydrozoa)

Pierobon

2012

Int. J. Dev. Biol.

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“…Ultrastructural and electrophysiological studies have shown that most synapses in the nervous systems of coelenterates are chemical (for reviews see refs. [1][2][3]. Despite this evidence, however, the nature of neurotransmitter substances in coelenterates has remained unknown.…”

mentioning

confidence: 99%

Isolation of pyroGlu-Gly-Arg-Phe-NH2 (Antho-RFamide), a neuropeptide from sea anemones.

Grimmelikhuijzen¹,

Graff²

1986

Proc. Natl. Acad. Sci. U.S.A.

100

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A radioimmunoassay has been developed for peptides containing the carboxyl-terminal sequence Arg-Phe-NH2 (RFamide). Using this radioimmunoassay and applying cation-exchange chromatography and HPLC, we (2,3,8,9). This paper describes the development of a radioimmunoassay for the coelenterate RFamide-like peptides and the purification and sequencing of such a peptide from the sea anemone Anthopleura elegantissima. METHODSRadioimmunoassay. Four rabbits were immunized with RFamide (Bachem, Bubendorf, Switzerland) that was coupled by carbodiimide to bovine thyroglobulin (Sigma). The antisera were treated overnight at 4°C with bovine thyroglobulin at 1 mg/ml, followed by centrifugation, to remove antibody populations specific for the carrier protein. One antiserum (code 145IV) was selected for the present study.125I-labeled Tyr-Phe-Met-Arg-Phe-NH2 was used as a tracer in the radioimmunoassay. It was prepared by adding 5 1.d (0.5 mCi; 18 MBq) of Na125I (Amersham) to 15 ,ul of 0.2 M sodium phosphate buffer, pH 7.0, containing 0.22 ,ug of Tyr-PheMet-Arg-Phe-NH2 (Peninsula Laboratories, San Carlos, CA), followed by addition of 10 ul of phosphate buffer containing 1.4 ,g of chloramine-T. After mixing, the reaction was stopped after 20 sec with 500 1.l of 0.3% Na2S205. The mixture was immediately loaded on a methanol/watertreated Sep-Pak C18 cartridge (Waters Associates), which was quickly rinsed with 40 ml of twice-distilled water, to remove unreacted 1251. Labeled material was eluted with 2-ml portions of 40%, 60%, 80%, and 90% (vol/vol) methanol and three times with 2-ml portions of 100% methanol. Each fraction was collected in 6 ml ofRIA buffer, consisting of0.05 M sodium phosphate at pH 7.4 and 1% bovine serum albumin (Sigma). The major portion of the tracer was eluted at 90% or 100% methanol. The quality of an aliquot (3000 cpm) of the tracer fractions was tested by overnight incubation, at 40C, in

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“…Not much successful neurochemistry has been done on representatives of this evolutionary stage. There is contradictory evidence for biogenic amines and peptides as neurotransmitters (Martin and Spencer, 1983). By the time one gets to the nematodes (roundworms), however, there are cells large enough for classical electrophysiology (Ascaris) and yet organisms of such short generation time as to expedite neurogenetics (Caenorhabditis elegans).…”

Section: An Outline Of Evolutionmentioning

confidence: 99%

Evolutionary Origin of Electrical Excitability

Hille

1988

Cellular Mechanisms of Conditioning and Behavioral Plasticity

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Neurotransmitters in coelenterates

Cited by 47 publications

References 61 publications

Coordinated modulation of cellular signaling through ligand-gated ion channels in Hydra vulgaris (Cnidaria, Hydrozoa)

Coordinated modulation of cellular signaling through ligand-gated ion channels in Hydra vulgaris (Cnidaria, Hydrozoa)

Isolation of pyroGlu-Gly-Arg-Phe-NH2 (Antho-RFamide), a neuropeptide from sea anemones.

Evolutionary Origin of Electrical Excitability

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