DIFFERENTIAL TRACER COUPLING BETWEEN PAIRS OF IDENTIFIED NEURONES OF THE MOLLUSC LYMNAEA STAGNALIS

1994 ◽  
Vol 192 (1) ◽  
pp. 291-297
Author(s):  
N Ewadinger ◽  
N Syed ◽  
K Lukowiak ◽  
A Bulloch
Keyword(s):  
Nervous System ◽  
Normal Saline ◽  
Lymnaea Stagnalis ◽  
Lucifer Yellow ◽  
Electrical Coupling ◽  
Cell Communication ◽  
Pond Snail ◽  
Dye Coupling ◽  
Freshwater Pond ◽  
Weakly Coupled

Electrical coupling is a common means of cell-to-cell communication in both neuronal and non-neuronal tissues (Lowenstein, 1985). Within the nervous system, many electrically coupled neurones exhibit dye coupling (Bennett, 1973; Stewart, 1978; Glantz and Kirk, 1980; Spencer and Satterlie, 1980; Fraser and Heitler, 1993); however, some electrically coupled cells do not dye-couple (Audesirk et al. 1982; Murphy et al. 1983; Berdan, 1987; Robinson et al. 1993; Veenstra et al. 1993). Electrical coupling and dye coupling, often considered in parallel, are in fact two different parameters that can vary independently (e.g. Audesirk et al. 1982; Perez-Armendariz et al. 1991). The giant identified neurones of pulmonate and opisthobranch molluscs have frequently been used for studies of neuronal communication and its plasticity (Winlow and McCrohan, 1987; Bulloch, 1989). In the present study, we explored the relationship between electrical and tracer coupling in both strongly and weakly coupled pairs of molluscan neurones. Specifically, we examined electrically coupled, identified neurones in a freshwater pond snail, Lymnaea stagnalis L., and tested for tracer coupling with Lucifer Yellow CH and biocytin. The cells examined were the strongly electrically coupled neurones, visceral dorsal 1 (VD1) and right parietal dorsal 2 (RPD2) (Boer et al. 1979; Benjamin and Pilkington, 1986), and the weakly coupled neurones, left buccal 1 (LB1) and right buccal 1 (RB1) (Benjamin and Rose, 1979). The use of these particular neurones made it possible to compare electrical coupling with tracer coupling in the molluscan central nervous system (CNS). All experiments were performed on laboratory-bred Lymnaea stagnalis (Mollusca, Pulmonata), maintained as previously described (Ridgway et al. 1991). The CNS was dissected from mature animals (16­18 mm shell length) and pinned to the silicone rubber (RTV 616 GE) base of a recording dish in normal saline (51.3 mmol l-1 NaCl, 1.7 mmol l-1 KCl, 4.1 mmol l-1 CaCl2, 1.5 mmol l-1 MgCl2 and 5 mmol l-1 Hepes, pH 7.9). Following removal of the outer connective tissue sheath, a small Pronase crystal (Sigma, type XIV, P-5147), held by forceps, was carefully applied to specific ganglia; this treatment softened the inner sheath and facilitated microelectrode penetration. The CNS was then rinsed several times at 5 °C in normal saline.

scholarly journals Octopamine: a new feeding modulator in Lymnaea

1998 ◽  
Vol 353 (1375) ◽  
pp. 1631-1643 ◽  
Author(s):  
Á Vehovszky ◽  
C. J. H. Elliott ◽  
E. E. Voronezhskaya ◽  
L. Hiripi ◽  
K. Elekes
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Lymnaea Stagnalis ◽  
Lucifer Yellow ◽  
Electrical Coupling ◽  
Pond Snail ◽  
Double Labelling ◽  
Feeding System ◽  
Morphological Criteria ◽  
Stimulation Of

The role of octopamine (OA) in the feeding system of the pond snail, Lymnaea stagnalis , was studied by applying behavioural tests on intact animals, and a combination of electrophysiological analysis and morphological labelling in the isolated central nervous system. OA antagonists phentolamine, demethylchlordimeform (DCDM) and 2–chloro–4–methyl–2–(phenylimino)–imidazolidine (NC–7) were injected into intact snails and the sucrose–induced feeding response of animals was monitored. Snails that received 25–50 mg kg -1 phentolamine did not start feeding in sucrose, and the same dose of NC–7 reduced the number of feeding animals by 80–90% 1–3 hours after injection. DCDM treatment reduced feeding by 20–60%. In addition, both phentolamine and NC–7 significantly decreased the feeding rate of those animals that still accepted food after 1–6 hours of injection. In the central nervous system a pair of buccal neurons was identified by electrophysiological and morphological criteria. After double labelling (intracellular staining with Lucifer yellow followed by OA–immunocytochemistry) these neurons were shown to be OA immunoreactive, and electrophysiological experiments confirmed that they are members of the buccal feeding system. Therefore the newly identified buccal neurons were called OC neurons (putative OA containing neurons or OAergic cells). Synchronous intracellular recordings demonstrated that the OC neurons share a common rhythm with feeding neurons either appearing spontaneously or evoked by intracellularly stimulated feeding interneurons. OC neurons also have synaptic connections with identified members of the feeding network: electrical coupling was demonstrated between OC neurons and members of the B4 cluster motoneurons, furthermore, chemically transmitted synaptic responses were recorded both on feeding motoneurons (B1, B2 cells) and the SO modulatory interneuron after the stimulation of OC neurons. However, elementary synaptic potentials could not be recorded on the follower cells of OC neurons. Prolonged (20 to 30 s) intracellular stimulation of OC cells activated the buccal feeding neurons leading to rhythmic activity pattern (fictive feeding) in a way similar to OA applied by perfusion onto isolated central nervous system (CNS) preparations. Our results suggest that OA acts as a modulatory substance in the feeding system of Lymnaea stagnalis and the newly identified pair of OC neurons belongs to the buccal feeding network.

Identification of a putative mechanosensory neuron in Lymnaea: characterization of its synaptic and functional connections with the whole-body withdrawal interneuron

1996 ◽  
Vol 76 (5) ◽  
pp. 3230-3238 ◽  
Author(s):  
T. Inoue ◽  
M. Takasaki ◽  
K. Lukowiak ◽  
N. I. Syed
Keyword(s):  
Sensory Neuron ◽  
Action Potentials ◽  
Synaptic Connection ◽  
Lucifer Yellow ◽  
Whole Body ◽  
Pond Snail ◽  
Mechanosensory Neuron ◽  
Functional Connections ◽  
Freshwater Pond ◽  
Withdrawal Behavior

1. In this study, we identified a putative mechanosensory neuron in the freshwater pond snail Lymnaea stagnalis. This sensory neuron, termed right parietal dorsal 3 (RPD3), mediates part of the whole-body withdrawal behavior via the activation of a withdrawal interneuron. 2. RPD3 is located in the central ring ganglia, where its soma is situated on the dorsal surface of the right parietal ganglion. Intracellular injection of the dye Lucifer yellow revealed that RPD3 has both central and peripheral axonal projections. 3. In isolated-CNS preparations, RPD3 was quiescent. In semi-intact preparations, however, a gentle/moderate mechanical touch (by a pair of blunt forceps) to the mantle cavity or columellar musculature elicited action potentials in RPD3 in the absence of prepotential activity. Furthermore, mechanical stimulus-induced action potentials in RPD3 persisted in the presence of zero Ca2+/ high Mg2+ and high Ca2+/high Mg2+ salines. Together, these data suggest that RPD3 is most likely to be a primary sensory neuron. 4. In both isolated-CNS and semi-intact preparations, intracellular depolarization of RPD3 excited the whole-body withdrawal interneuron right pedal dorsal 11 (RPeD11). This synaptic connection persisted in the presence of high Ca2+ and high Mg2+ saline, suggesting that it is likely to be monosynaptic. Moreover, when stimulated electrically, the interneuron RPeD11 induced an hyperpolarizing response in RPD3. The possibility of this connection being monosynaptic was not tested, however, in the present study. Together, these data demonstrate that RPD3 excites RPeD11, which in turn may inhibit RPD3 activity. 5. In the semi-intact preparation, a mechanical touch to the mantle edge excited RPD3, which in turn generated action potentials in RPeD11. Zero Ca2+ saline blocked this synaptic connection between RPD3 and RPeD11, suggesting that it is chemical. 6. To demonstrate that RPD3 was sufficient to induce the withdrawal response and that the withdrawal behavior was mediated indirectly via RPeD11, we made simultaneous intracellular recordings from these two neurons while monitoring muscle contractions via a tension transducer. Intracellular depolarization of RPD3 elicited action potentials in RPeD11, followed by the contraction of the columellar muscle. Similar stimulation of RPD3 failed to excite a simultaneously hyperpolarized RPeD11 and as a result, no contraction of the columellar muscle occurred. Direct intracellular depolarization of RPeD11, however, induced the contraction of the columellar muscle. These data suggest that RPD3-induced withdrawal behavior is mediated in part via RPeD11.

scholarly journals Primary structure and origin of schistosomin, an anti-gonadotropic neuropeptide of the pond snail Lymnaea stagnalis

1991 ◽  
Vol 279 (3) ◽  
pp. 837-842 ◽  
Author(s):  
P L Hordijk ◽  
H D F H Schallig ◽  
R H M Ebberink ◽  
M de Jong-Brink ◽  
J Joosse
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Primary Structure ◽  
Lymnaea Stagnalis ◽  
Sequence Similarity ◽  
Infected Snail ◽  
Chain Molecule ◽  
Pond Snail ◽  
Single Chain ◽  
The Central Nervous System

In the pond snail Lymnaea stagnalis infected with the schistosome parasite Trichobilharzia ocellata, a peptide called schistosomin is released from the central nervous system, which counteracts the bioactivity of a number of gonadotropic hormones. This leads to inhibition of the reproductive activities of the infected snail. In order to determine the structure of schistosomin, the neuropeptide was purified from the central nervous system using gel-permeation chromatography and reverse-phase h.p.l.c. The complete primary structure of the peptide was determined by N-terminal sequencing and peptide mapping. Schistosomin is a single-chain molecule of 79 amino acids with a molecular mass of 8738 Da. The peptide contains eight cysteine residues which may give rise to four intramolecular disulphide bridges that fold the peptide into a stable globular structure. A database search did not reveal any known peptides that show significant sequence similarity to schistosomin. By means of immunocytochemistry, the peptide was shown to be localized in the growth-controlling neurosecretory light green cells, which are located in the cerebral ganglia of the central nervous system of Lymnaea. In addition to schistosomin, these neurons are known to produce various insulin-related peptides.

Evidence for an enkephalinergic system in the nervous system of the pond snail,Lymnaea stagnalis

1990 ◽  
Vol 531 (1-2) ◽  
pp. 66-71 ◽  
Author(s):  
Michael K. Leung ◽  
Harry H. Boer ◽  
Jan van Minnen ◽  
Jonathan Lundy ◽  
George B. Stefano
Keyword(s):  
Nervous System ◽  
Lymnaea Stagnalis ◽  
Pond Snail

scholarly journals Gap junction coding innexin in Lymnaea stagnalis: sequence analysis and characterization in tissues and the central nervous system

2019 ◽  
Author(s):  
Brittany A. Mersman ◽  
Sonia N. Jolly ◽  
Zhenguo Lin ◽  
Fenglian Xu
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Gene Duplication ◽  
Gap Junction ◽  
Lymnaea Stagnalis ◽  
Expression Patterns ◽  
Genetic Research ◽  
Single Copy ◽  
Pond Snail ◽  
The Central Nervous System

AbstractConnections between neurons called synapses are the key components underlying all nervous system functions of animals and humans. However, important genetic information on the formation and plasticity of one type, the electrical (gap junction-mediated) synapse, is severely understudied, especially in invertebrates. In the present study, we set forth to identify and characterize the gap junction-encoding gene innexin in the central nervous system (CNS) of the mollusc pond snail Lymnaea stagnalis (L. stagnalis). With PCR, 3’ and 5’ RACE, and BLAST searches, we identified eight innexin genes in the L. stagnalis nervous system named Lst Inx1-8. Phylogenetic analysis revealed that the L. stagnalis innexin genes originated from a single copy in the common ancestor of molluscan species by multiple gene duplication events and have been maintained in L. stagnalis since they were generated. The paralogous innexin genes demonstrate distinct expression patterns among tissues. In addition, one paralog, Lst Inx1, exhibits heterogeneity in cells and ganglia, suggesting the occurrence of functional diversification after gene duplication. These results introduce possibilities to study an intriguing potential relationship between innexin paralog expression and cell-specific functional outputs such as heterogenic ability to form channels and exhibit synapse plasticity. The L. stagnalis CNS contains large neurons and a functionally defined network for behaviors; with the introduction of L. stagnalis in the gap junction field, we are providing novel opportunities to combine genetic research with direct investigation of functional outcomes at the cellular, synaptic, and behavioral levels.Summary StatementBy characterizing the gap junction gene innexin in Lymnaea stagnalis, we open opportunities for novel studies on the regulation, plasticity, and evolutionary function of electrical synapses throughout the animal kingdom.

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