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Neuroanatomical, immunocytochemical, and physiological studies of the pharyngeal retractor muscle and its putative regulatory neurons playing a role in withdrawal and feeding in the snail, Helix pomatia

Neuroanatomical, immunocytochemical, and physiological studies of the pharyngeal retractor muscle and its putative regulatory neurons playing a role in withdrawal and feeding in the snail, Helix pomatia
Neuroanatomical, immunocytochemical, and physiological studies of the pharyngeal retractor muscle and its putative regulatory neurons playing a role in withdrawal and feeding in the snail, Helix pomatia
We describe the neurons regulating two separate functions of the pharyngeal retractor muscle (PRM), namely sustained contraction during body withdrawal and rhythmic phasic contractions during feeding, in the snail, Helix pomatia. The distribution of central neurons innervating the PRM is organized into two main units; one in the buccal-cerebral ganglion complex, the other in the subesophageal ganglion complex. Serotonin- (5-HT-), FMRFamide- (FMRFa-), and tyrosine-hydroxylase-immunostained neurons are present among the PRM neurons that densely innervate the PRM. 5HT both decreases and increases the amplitude of the electrically evoked contraction between concentrations of 0.1 microM and 1 microM. Dopamine (DA) only decreases the amplitude of contraction at a 1-microM threshold concentration. In contrast, FMRFa increases the amplitude of the contraction and slightly elevates the tone of the PRM but requires a higher threshold (10 microM). Assay by high-performance liquid chromatography of 5HT and DA in the PRM has shown that the 5HT level decreases during locomotion but increases during feeding, whereas the DA level increases during locomotion but slightly decreases during feeding. Thus, different segments of the PRM are innervated by neurons from different loci within the central nervous system. The segments of the PRM distal to the pharynx are innervated from loci of the subesophageal ganglion complex suggesting that they mediate withdrawal. The proximal segment of the PRM is innervated from cerebral and buccal loci indicating that these neurons mediate the feeding rhythm produced by buccal and cerebral feeding central pattern generators to induce rhythmic phasic contractions in the PRM during feeding.
pharyngeal retractor muscle, feeding, buccal-cerebral ganglion, subesophageal ganglion, neurotransmitters, helix pomatia (mollusca)
0302-766X
257-271
Hernádi, László
0ea6a648-a22a-4942-bdbe-efa2cdfb11d5
Vehovszky, Ágnes
2fa3cdb7-890b-45cd-a420-06fe67d52816
Hiripi, László
0013bdb0-085f-4c94-acc3-809d554db1e1
Györi, János
5ef6362f-9011-4c84-82a5-1eae6c1982e3
Walker, Robert J.
9368ac2d-f1e9-4bd9-a4b4-4a161c4aa140
Elekes, Károly
ce656fae-456b-4283-be4b-d5c41f369352
Hernádi, László
0ea6a648-a22a-4942-bdbe-efa2cdfb11d5
Vehovszky, Ágnes
2fa3cdb7-890b-45cd-a420-06fe67d52816
Hiripi, László
0013bdb0-085f-4c94-acc3-809d554db1e1
Györi, János
5ef6362f-9011-4c84-82a5-1eae6c1982e3
Walker, Robert J.
9368ac2d-f1e9-4bd9-a4b4-4a161c4aa140
Elekes, Károly
ce656fae-456b-4283-be4b-d5c41f369352

Hernádi, László, Vehovszky, Ágnes, Hiripi, László, Györi, János, Walker, Robert J. and Elekes, Károly (2005) Neuroanatomical, immunocytochemical, and physiological studies of the pharyngeal retractor muscle and its putative regulatory neurons playing a role in withdrawal and feeding in the snail, Helix pomatia. Cell and Tissue Research, 321 (2), 257-271. (doi:10.1007/s00441-005-1144-2). (PMID:15959810)

Record type: Article

Abstract

We describe the neurons regulating two separate functions of the pharyngeal retractor muscle (PRM), namely sustained contraction during body withdrawal and rhythmic phasic contractions during feeding, in the snail, Helix pomatia. The distribution of central neurons innervating the PRM is organized into two main units; one in the buccal-cerebral ganglion complex, the other in the subesophageal ganglion complex. Serotonin- (5-HT-), FMRFamide- (FMRFa-), and tyrosine-hydroxylase-immunostained neurons are present among the PRM neurons that densely innervate the PRM. 5HT both decreases and increases the amplitude of the electrically evoked contraction between concentrations of 0.1 microM and 1 microM. Dopamine (DA) only decreases the amplitude of contraction at a 1-microM threshold concentration. In contrast, FMRFa increases the amplitude of the contraction and slightly elevates the tone of the PRM but requires a higher threshold (10 microM). Assay by high-performance liquid chromatography of 5HT and DA in the PRM has shown that the 5HT level decreases during locomotion but increases during feeding, whereas the DA level increases during locomotion but slightly decreases during feeding. Thus, different segments of the PRM are innervated by neurons from different loci within the central nervous system. The segments of the PRM distal to the pharynx are innervated from loci of the subesophageal ganglion complex suggesting that they mediate withdrawal. The proximal segment of the PRM is innervated from cerebral and buccal loci indicating that these neurons mediate the feeding rhythm produced by buccal and cerebral feeding central pattern generators to induce rhythmic phasic contractions in the PRM during feeding.

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More information

e-pub ahead of print date: June 2005
Published date: August 2005
Keywords: pharyngeal retractor muscle, feeding, buccal-cerebral ganglion, subesophageal ganglion, neurotransmitters, helix pomatia (mollusca)
Organisations: Centre for Biological Sciences

Identifiers

Local EPrints ID: 372594
URI: http://eprints.soton.ac.uk/id/eprint/372594
ISSN: 0302-766X
PURE UUID: baaa0ebe-b837-4ede-9059-3b2fbe3951dc
ORCID for Robert J. Walker: ORCID iD orcid.org/0000-0002-9031-7671

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Date deposited: 09 Dec 2014 13:53
Last modified: 03 Dec 2019 01:23

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Contributors

Author: László Hernádi
Author: Ágnes Vehovszky
Author: László Hiripi
Author: János Györi
Author: Károly Elekes

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