A neuropharmacological analysis of the pacemakers and conducting tissues ofHydra attenuata

Kass-Simon, G.; Passano, L. M.

doi:10.1007/bf00668375

Cited by 46 publications

(23 citation statements)

References 16 publications

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“…We reasoned that the CB system should be in the ectoderm because ectodermal neurons innervate the longitudinal (vertical) muscle fibers of the ectodermal skin cells in order to cause body wall longitudinal contractions. In addition, previous studies showed that the rhythmic potentials exist in the endodermal nerve net [10] and cause longitudinal contractions of the endoderm [12] which has been interpreted as producing elongation of the body column of the animal [11], because endodermal muscle cells are arranged circularly (horizontally). However, if rhythmic potentials were generated by the endodermal nerve net, they would not be able to interact with CB neurons (as shown in Figure 3D) which are in the ectoderm.…”

Section: Resultsmentioning

confidence: 99%

“…These two networks (RP1 and RP2) are located in the ectoderm and endoderm of the animal respectively. A previous study reported that rhythmic potentials are only generated in the endoderm [10] by showing their absence in an area where the endoderm had been surgically removed. However, in that study the authors reported having recorded in rare instances rhythmic potentials in the ectoderm but they attributed this signal to an incomplete removal of the endoderm in the recorded region.…”

Section: Discussionmentioning

confidence: 99%

“…activity in the apparent absence of any external stimulus and, sometimes, also in the absence of any clear behavior. One example of this are the rhythmic electrical potentials [6,9], which have been thought to propagate in the endoderm of the animal [10] and to increase in frequency during elongation of the body column [6]. Activation of the endoderm by rhythmic potentials is thought to cause radial contraction (reduction of the radius of the animal) and therefore elongation [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…Extracellular studies have provided detailed descriptions of electrical signals but could not link them to a particular cell type. In fact, whether rhythmic potentials and longitudinal contraction bursts are conducted by neurons or by the muscle/epithelial cells is still under debate [10,20,21], and surgical isolations indicate that they can propagate along both axes of the epithelium [8]. Also, extracellular recordings, which could be more akin to electromyograms, can be disrupted by the motion of the animal [9], and therefore cannot be carried out in certain types of behavior.…”

Section: Introductionmentioning

confidence: 99%

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Non-overlapping Neural Networks in Hydra vulgaris

2017

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Summary To understand the emergent properties of neural circuits it would be ideal to record the activity of every neuron in a behaving animal and decode how it relates to behavior. We have achieved this with the cnidarian Hydra vulgaris, using calcium imaging of genetically engineered animals to measure the activity of essentially all of its neurons. While the nervous system of Hydra is traditionally described as a simple nerve net, we surprisingly find instead a series of functional networks that are anatomically non-overlapping and are associated with specific behaviors. Three major functional networks extend through the entire animal and are activated selectively during longitudinal contractions, elongations in response to light and radial contractions, while an additional network is located near the hypostome and is active during nodding. These results demonstrate the functional sophistication of apparently simple nerve nets, and the potential of Hydra and other basal metazoans as a model system for neural circuit studies.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non-overlapping Neural Networks in Hydra vulgaris

2017

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“…Neurotransmission in Hydra has been considered to be essentially peptidergic, owing to the presence of several neuropeptides [5,6]. Progress in identifying nonpeptidergic neurotransmitters in cnidarians has been slow, and the results confusing or even contradictory [7][8][9]. On the other hand, recent evidence has been obtained of the occurrence of dopamine in Hydra tissues [10].…”

mentioning

confidence: 99%

Arachidonic acid as an endogenous signal for the glutathione-induced feeding response in Hydra

Pierobon¹,

Petrocellis²,

Minei³

et al. 1997

CMLS, Cell. mol. life sci.

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Phospholipase A 2 -derived arachidonic acid (AA) and related metabolic products represent an important pathway involved in the regulation of growth and morphogenesis as well as in oxidative processes in cnidarian tissues. Here we present data on the participation of AA in the glutathione (GSH)-induced feeding response in Hydra 6ulgaris. Under conditions in which it produces the feeding response (which consists mainly of mouth opening followed by mouth closure), GSH dose-dependently induced the release of free arachidonic acid from live polyps. Phospholipase A 2 inhibitors blocked this release and enhanced the duration of GSH-induced Hydra mouth opening. Accordingly, AA and, to a smaller extent, h-linolenic acid, were found to reduce the duration of the feeding response in a 10 -100 mM concentration range, and this effect resulted mainly from earlier times of mouth closure. 11-(R)-hydroxy-eicosa-5Z,8Z,12E,14Z-tetraenoic acid, a lipoxygenase metabolite of AA in H. 6ulgaris, reproduced the effects of its precursor fatty acid at lower concentrations. The kinetics of GSH-induced arachidonate release and GSH-induced feeding response were correlated, suggesting that AA might modulate the mechanisms controlling mouth closure. Finally, the role of AA in the facilitation of the mouth-closing phase of the feeding response was further supported by the finding that: (1) exogenous AA reversed the effect on the feeding response of k-aminobutyric acid, which normally delays the times of mouth closure, and (2) endogenous AA was also released in the absence of GSH from live polyps stimulated with antho-RFamide, a neuropeptide abundant in hydrozoans. We suggest that in Hydra AA may act as a second messenger following chemical stimulation.Abbreviations. AA= arachidonic acid; BPB = 4-bromophenacyl bromide; cGMP=guanosine 3%:5%-cyclic monophosphate; CNS = central nervous system; DMSO = dimethyl sulfoxide; GABA =k-aminobutyric acid; GTP = guanosine 5%-triphosphate; (11-R)-HETE= 11-(R)-hydroxy-eicosa-5Z,8Z,12E,14Z-tetraenoic acid; (9-R)-HOTrE =9-(R)-hydroxy-octadeca-10E,12Z,15Z-trienoic acid; (11-R)-HPETE= 11-(R)-hydroperoxy-eicosa-5Z,8Z,12E,14Z-tetraenoic acid; HPLC= high-pressure liquid chromatography; (9-R)-HPOTrE =9-(R)-hydroperoxy-octadeca-10E,12Z,15Z-trienoic acid; h-LA= h-linolenic acid; OOPC= oleyloxyethylphosphorylcholine; PLA 2 = phospholipase A 2 ; PUFAs = polyunsaturated fatty acids; TBPS= t-butylbicyclophosphorothionate.The nerve net of the freshwater polyp Hydra (Cnidaria, Hydrozoa) is currently regarded as one of the most primitive nervous systems to have evolved [1]. Neurons are dispersed in the epithelia and are interconnected by neurites into a functional network, or to non-neuronal effectors by uni-and bidirectional synapses (see ref. 2 for a concise review). The nervous net spreads homogeneously over the entire body except in the head region, where the fibres are condensed to form a circular ring, possibly representing a rudimentary cephalization of the system [3]. This seemingly simple, two-dimensional nervous syste...

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Nervous System

and¹,

Hufnagel²

2015

Diseases of Coral

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A neuropharmacological analysis of the pacemakers and conducting tissues ofHydra attenuata

Cited by 46 publications

References 16 publications

Non-overlapping Neural Networks in Hydra vulgaris

Non-overlapping Neural Networks in Hydra vulgaris

Arachidonic acid as an endogenous signal for the glutathione-induced feeding response in Hydra

Nervous System

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