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Kiss T. Do terrestrial gastropods use olfactory cues to locate and select food actively? INVERTEBRATE NEUROSCIENCE 2017; 17:9. [PMID: 28688004 DOI: 10.1007/s10158-017-0202-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 06/29/2017] [Indexed: 10/19/2022]
Abstract
Having been investigated for over 40 years, some aspects of the biology of terrestrial gastropod's olfactory system have been challenging and highly contentious, while others still remain unresolved. For example, a number of terrestrial gastropod species can track the odor of food, while others have no strong preferences toward food odor; rather they find it by random encounter. Here, while assessing the most recent findings and comparing them with earlier studies, the aspects of the food selection based on olfactory cues are examined critically to highlight the speculations and controversies that have arisen. We analyzed and compared the potential role of airborne odors in the feeding behavior of several terrestrial gastropod species. The available results indicate that in the foraging of most of the terrestrial gastropod species odor cues contribute substantially to food finding and selection. The results also suggest, however, that what they will actually consume largely depends on where they live and the species of gastropod that they are. Due to the voluminous literature relevant to this object, this review is not intended to be exhaustive. Instead, I selected what I consider to be the most important or critical in studies regarding the role of the olfaction in feeding of terrestrial gastropods.
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Affiliation(s)
- Tibor Kiss
- Department of Experimental Zoology, Balaton Limnological Institute, MTA Centre for Ecological Research, Klebelsberg Kuno Str. 2-3, Tihany, 8237, Hungary.
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Krajcs N, Hernádi L, Pirger Z, Reglődi D, Tóth G, Kiss T. PACAP Modulates Acetylcholine-Elicited Contractions at Nicotinic Neuromuscular Contacts of the Land Snail. J Mol Neurosci 2015; 57:492-500. [PMID: 26138333 DOI: 10.1007/s12031-015-0605-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 06/17/2015] [Indexed: 12/29/2022]
Abstract
In this study, we investigate the potentiating effect of PACAP27 on cholinergic neuromuscular transmission in the recently discovered flexor muscles of the land snail, Helix pomatia. Using immunohistochemistry, we show that PACAP and PAC1 receptors are present in nerve fibers innervating the flexor muscles but not in the muscle itself. We also observed that PACAP27 exerts both pre- and postsynaptic effects on the cholinergic synapse and performed tests using a broad spectrum of chemicals in order to explore the possible intracellular pathways through which PACAP mediates its stimulatory effect. Our pharmacological data demonstrate that PACAP27 presynaptically enhances the release of acetylcholine by activating the adenylate cyclase-cAMP-PKA pathway. Postsynaptically, PACAP27 was found to enhance muscle contractility by PKC-mediated signaling pathway resulting in an increased Ca(2+) release from intracellular stores. These findings suggest that regulation of Ca(2+) release may contribute to the stimulatory effect of PACAP. Our data are the first demonstration of the potentiating effect of PACAP27 at the molluscan excitatory neuromuscular contact.
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Affiliation(s)
- Nóra Krajcs
- Chemical Ecology and Neurobiology Research Group, Department of Experimental Zoology, Balaton Limnological Institute, Centre for Ecological Research, Hungarian Academy of Sciences, Klebelsberg Kuno u 3, H-8237, Tihany, Hungary
| | - László Hernádi
- Chemical Ecology and Neurobiology Research Group, Department of Experimental Zoology, Balaton Limnological Institute, Centre for Ecological Research, Hungarian Academy of Sciences, Klebelsberg Kuno u 3, H-8237, Tihany, Hungary
| | - Zsolt Pirger
- Chemical Ecology and Neurobiology Research Group, Department of Experimental Zoology, Balaton Limnological Institute, Centre for Ecological Research, Hungarian Academy of Sciences, Klebelsberg Kuno u 3, H-8237, Tihany, Hungary.,Adaptive Neuroethology Research Group, Department of Experimental Zoology, Balaton Limnological Institute, Centre for Ecological Research, Hungarian Academy of Sciences, Klebelsberg Kuno u 3, H-8237, Tihany, Hungary.,MTA-PTE "Momentum" PACAP Research Team, University of Pecs, Pecs, Hungary
| | - Dóra Reglődi
- MTA-PTE "Momentum" PACAP Research Team, University of Pecs, Pecs, Hungary
| | - Gábor Tóth
- Department of Medical Chemistry, University of Szeged, Szeged, Hungary
| | - Tibor Kiss
- Chemical Ecology and Neurobiology Research Group, Department of Experimental Zoology, Balaton Limnological Institute, Centre for Ecological Research, Hungarian Academy of Sciences, Klebelsberg Kuno u 3, H-8237, Tihany, Hungary.
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Kiss T, Krajcs N, Pirger Z, Hernádi L. Nicotinic acetylcholine receptors containing the α7-like subunit mediate contractions of muscles responsible for space positioning of the snail, Helix pomatia L. tentacle. PLoS One 2014; 9:e109538. [PMID: 25303328 PMCID: PMC4193815 DOI: 10.1371/journal.pone.0109538] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 09/05/2014] [Indexed: 11/19/2022] Open
Abstract
Three recently discovered tentacle muscles are crucial to perform patterned movements of upper tentacles of the terrestrial snail, Helix pomatia. The muscles receive central and peripheral excitatory cholinergic innervation lacking inhibitory innervation. Here, we investigate the pharmacology of acetylcholine (ACh) responses in muscles to determine the properties of the ACh receptor (AChR), the functional availability of which was assessed using isotonic contraction measurement. Using broad spectrum of nicotinic and muscarinic ligands, we provide the evidence that contractions in the muscles are attributable to the activation of nAChRs that contain the α7-like subunit. Contractions could be evoked by nicotine, carbachol, succinylchloride, TMA, the selective α7-nAChR agonist choline chloride, 3-Bromocytisine and PNU-282987, and blocked by nAChR selective antagonists such as mytolon, hexamethonium, succinylchloride, d-tubocurarine, hemicholinium, DMDA (decamethonium), methyllycaconitine, α-Bungarotoxin (αBgTx) and α-Conotoxin IMI. The specific muscarinic agonist oxotremorine and arecoline failed to elicit contractions. Based on these pharmacological properties we conclude that the Na+ and Ca2+ permeable AChRs of the flexor muscle are nicotinic receptors that contain the α7-like subunit. Immunodetection experiments confirmed the presence of α7- or α7-like AChRs in muscle cells, and α4-AChRs in nerves innervating the muscle. These results support the conclusion that the slowly desensitizing αBgTx-sensitive responses obtained from flexor muscles are produced by activation of α7- like AChRs. This is the first demonstration of postsynaptic expression and an obligatory role for a functional α7-like nAChR in the molluscan periphery.
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Affiliation(s)
- Tibor Kiss
- Chemical Ecology and Neurobiology Group, Department of Experimental Zoology, Balaton Limnological Institute, MTA Centre for Ecological Research, Tihany, Hungary
- * E-mail:
| | - Nóra Krajcs
- Chemical Ecology and Neurobiology Group, Department of Experimental Zoology, Balaton Limnological Institute, MTA Centre for Ecological Research, Tihany, Hungary
| | - Zsolt Pirger
- Adaptive Neuroetology MTA-CER, National Brain Project Team, Tihany, Hungary
| | - László Hernádi
- Chemical Ecology and Neurobiology Group, Department of Experimental Zoology, Balaton Limnological Institute, MTA Centre for Ecological Research, Tihany, Hungary
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Hernádi L, Kiss T, Krajcs N, Teyke T. Novel peripheral motor neurons in the posterior tentacles of the snail responsible for local tentacle movements. INVERTEBRATE NEUROSCIENCE 2014; 14:127-36. [PMID: 24821413 DOI: 10.1007/s10158-014-0170-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 05/02/2014] [Indexed: 11/29/2022]
Abstract
Three flexor muscles of the posterior tentacles of the snail Helix pomatia have recently been described. Here, we identify their local motor neurons by following the retrograde transport of neurobiotin injected into these muscles. The mostly unipolar motor neurons (15-35 µm) are confined to the tentacle digits and send motor axons to the M2 and M3 muscles. Electron microscopy revealed small dark neurons (5-7 µm diameter) and light neurons with 12-18 (T1 type) and 18-30 µm diameters (T2 type) in the digits. The diameters of the neurobiotin-labeled neurons corresponded to the T1 type light neurons. The neuronal processes of T1 type motor neurons arborize extensively in the neuropil area of the digits and receive synaptic inputs from local neuronal elements involved in peripheral olfactory information processing. These findings support the existence of a peripheral stimulus-response pathway, consisting of olfactory stimulus-local motor neuron-motor response components, to generate local lateral movements of the tentacle tip ("quiver"). In addition, physiological results showed that each flexor muscle receives distinct central motor commands via different peritentacular nerves and common central motor commands via tentacle digits, respectively. The distal axonal segments of the common pathway can receive inputs from local interneurons in the digits modulating the motor axon activity peripherally without soma excitation. These elements constitute a local microcircuit consisting of olfactory stimulus-distal segments of central motor axons-motor response components, to induce patterned contraction movements of the tentacle. The two local microcircuits described above provide a comprehensive neuroanatomical basis of tentacle movements without the involvement of the CNS.
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Affiliation(s)
- László Hernádi
- Department of Experimental Zoology, Balaton Limnological Institute, MTA Centre for Ecological Research, P.O. Box 35, 8237, Tihany, Hungary,
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Excitatory neurotransmitters in the tentacle flexor muscles responsible for space positioning of the snail olfactory organ. INVERTEBRATE NEUROSCIENCE 2013; 14:59-69. [PMID: 24185528 DOI: 10.1007/s10158-013-0164-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 10/15/2013] [Indexed: 10/26/2022]
Abstract
Recently, three novel flexor muscles (M1, M2 and M3) in the posterior tentacles of the snail have been described, which are responsible for the patterned movements of the tentacles of the snail, Helix pomatia. In this study, we have demonstrated that the muscles received a complex innervation pattern via the peritentacular and olfactory nerves originating from different clusters of motoneurons of the cerebral ganglia. The innervating axons displayed a number of varicosities and established neuromuscular contacts of different ultrastructural forms. Contractions evoked by nerve stimulation could be mimicked by external acetylcholine (ACh) and glutamate (Glu), suggesting that ACh and Glu are excitatory transmitters at the neuromuscular contacts. Choline acetyltransferase and vesicular glutamate transporter immunolabeled axons innervating flexor muscles were demonstrated by immunohistochemistry and in Western blot experiments. Nerve- and transmitter-evoked contractions were similarly attenuated by cholinergic and glutamatergic antagonists supporting the dual excitatory innervation. Dopamine (DA, 10⁻⁵ M) oppositely modulated thin (M1/M2) and thick (M3) muscle responses evoked by stimulation of the olfactory nerve, decreasing the contractions of the M1/M2 and increasing those of M3. In both cases, the modulation site was presynaptic. Serotonin (5-HT) at high concentration (10⁻⁵ M) increased the amplitude of both the nerve- and the ACh-evoked contractions in all muscles. The relaxation rate was facilitated suggesting pre- and postsynaptic site of action. Our data provided evidence for a DAergic and 5-HTergic modulation of cholinergic nerves innervating flexor muscles of the tentacles as well as the muscles itself. These effects of DA and 5-HT may contribute to the regulation of sophisticated movements of tentacle muscles lacking inhibitory innervation.
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Hernádi L, Teyke T. Novel triplet of flexor muscles in the posterior tentacles of the snail, Helix pomatia. ACTA BIOLOGICA HUNGARICA 2012; 63 Suppl 2:123-8. [PMID: 22776484 DOI: 10.1556/abiol.63.2012.suppl.2.16] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The anatomy of three novel flexor muscles in the posterior tentacles of Helix pomatia is described. The muscles originate from the ventral side of the sensory pad and are anchored at different sites in the base of the tentacle stem. The muscles span the tentacle and always take the length of the stem which depends on the rate of tentacle protrusion indicating that the muscles are both contractile and extremely stretchable. The three anchoring points at the base of the stem determine three space axes along which the contraction of a muscle or the synchronous contraction of the muscles can move the tentacle in space.
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Affiliation(s)
- L Hernádi
- MTA Centre for Ecological Research, Balaton Limnological Institute, Department of Experimental Zoology, P.O. Box 35, H-8237 Tihany, Hungary.
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