Biochemical and functional identification of GABA receptors in Hydra vulgaris

Pierobon, Paola; Concas, Alessandra; Santoro, G; Marino, G.; Minei, Rosario; Pannaccione, Anna; Mostallino, Maria Cristina; Biggio, Giovanni

doi:10.1016/0024-3205(95)00111-i

Cited by 40 publications

(32 citation statements)

References 32 publications

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“…As predicted from biochemical experiments, GABA A R agonists and positive allosteric modulators mimicked or potentiated these effects of GABA in a dose-dependent manner. The specific GABA B agonist baclofen did not significantly modify duration of the GSH-induced response (Pierobon et al, 1995;Concas et al, 1998).…”

Section: The G-glutamil-cysteinyl-glycine (Gsh) Assaymentioning

confidence: 74%

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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: The G-glutamil-cysteinyl-glycine (Gsh) Assaymentioning

confidence: 74%

“…Receptors to GABA were identified in membrane preparations from Hydra vulgaris (Pierobon et al, 1995). The binding of [ 3 H] GABA was specific (70% specific binding), reversible and saturable.…”

Section: Inhibitory Transmitters and Receptors: Gaba And Glycinementioning

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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“…In Hydra, the classical amino acid neurotransmitters GABA and glutamate exert an inhibitory and excitatory action, respectively, on the pacemaker systems (Kass-Simon et al, 2003). In previous papers, we have shown that the response to GSH is finely tuned by inhibitory and excitatory amino acid neurotransmitters, indicating that the cellular components leading to mouth closure are modulated by the nerve net (Concas et al, 1998;Pierobon et al, 1995Pierobon et al, , 2001Pierobon et al, , 2004aPierobon et al, , 2004b. However, GABA and glycine prolong response duration, while NMDA reduces it; this finding was tentatively explained with the hypothesis of potentiation or inhibition, respectively, of a chain of multiple sequential inhibitory loci, which modulate contraction and relaxation of ectodermal and endodermal myofibrils (reviewed in Pierobon, 2012).…”

Section: Discussionmentioning

confidence: 99%

“…3D). In whole animals, neither baclofen in a 0.05-100 µmol l −1 concentration range, nor 1-100 µmol l −1 phaclofen modified duration of the response to GSH (data not shown; see Pierobon et al, 1995).…”

Section: Gaba Agonists and Antagonistsmentioning

confidence: 94%

“…By using the GSH assay, we have shown that amino acid neurotransmitters, GABA, glycine, NMDA and related ligands, acting through their ionotropic receptors, are able to modulate the duration of the response to GSH by delaying or anticipating, respectively, the time of mouth closure (Concas et al, 1998;Pierobon et al, 1995Pierobon et al, , 2001Pierobon et al, , 2004a. In contrast to glutamate (Bellis et al, 1991), these ligands do not modify times of mouth opening, suggesting that their effect is exerted on the neuromuscular circuitry underlying the feeding behaviour, rather than on the GSH receptor itself (reviewed in Pierobon, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Regional modulation of the response to glutathione in Hydra vulgaris (Pallas, 1766).

Pierobon

2015

Journal of Experimental Biology

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In the presence of prey, or upon exposure to reduced glutathione (GSH), Hydra polyps open a mouth to ingest the captured prey and close it after feeding; at rest the mouth is not evident. In previous papers we have shown that GABA, glycine and NMDA modulate the mechanisms of mouth closure through ligand-gated-ion-channel receptors that are similar to their mammalian analogues in terms of biochemical and pharmacological properties. In order to study the regional distribution of these receptors, we have applied the GSH assay to polyps amputated at different levels of the body column. The response to 1-10 µmol l −1 GSH of polyps lacking either peduncle and foot or the entire body columns (heads) was not different from control, whole animals. In the presence of GABA or muscimol, duration of the response was significantly decreased in heads; the decrease was suppressed by the GABA antagonists gabazine and bicuculline. By contrast, in animals lacking peduncle and foot, duration of the response did not vary upon GABA administration. Conversely, in the presence of glycine, duration of the response in heads preparations was similar to control, whereas in footless polyps, it was significantly reduced. The decrease was mimicked by the glycine agonists taurine and β-alanine, and counteracted by strychnine. These results suggest a regional distribution of receptors to GABA and glycine in the neuromuscular circuitry modulating the feeding behaviour.

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Neurotransmission—Evolving Systems

Anctil¹

2016

The Wiley Handbook of Evolutionary Neuroscience

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Biochemical and functional identification of GABA receptors in Hydra vulgaris

Cited by 40 publications

References 32 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)

Regional modulation of the response to glutathione in Hydra vulgaris (Pallas, 1766).

Neurotransmission—Evolving Systems

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