Integration of biphasic synaptic input by electrotonically coupled neuroendocrine caudodorsal cells in the pond snail

1983 ◽  
Vol 49 (6) ◽  
pp. 1392-1409 ◽  
Author(s):  
A. ter Maat ◽  
E. W. Roubos ◽  
J. C. Lodder ◽  
P. Buma
Keyword(s):  
Synaptic Input ◽  
Lymnaea Stagnalis ◽  
Electrical Coupling ◽  
Pond Snail ◽  
Excitatory Postsynaptic Potential ◽  
Postsynaptic Potential ◽  
Electrophysiological Recordings ◽  
Coupled Cells ◽  
Lateral Branches ◽  
Dorsal Cells

The ovulation hormone-producing caudodorsal cells (CDCs) of the pond snail Lymnaea stagnalis form two clusters of electrotonically coupled cells, each containing a few specialized (ventral) cells that connect the clusters. The hormone is secreted during a pacemaker-driven discharge. The CDCs receive a biphasic cholinergic postsynaptic potential (PSP), consisting of a rapid excitatory postsynaptic potential (EPSP) and a slow inhibitory postsynaptic potential (IPSP) that is elicited by stimulation of nerves. The effect of the synaptic input on the discharge of the CDCs is described and the location of the synapse investigated by a combination of electrophysiological recordings and morphological techniques. The PSP interrupts the discharge and hastens its termination. In addition, it causes a reversal of the temporal order of the spikes of ventral cells (that normally lead) and dorsal cells (that lead only after the PSP). Ion-substitution experiments indicate that the ionic mechanism underlying the biphasic PSP is conventional, involving a conductance increase for Na+ (EPSP) and K+ (IPSP). Receptors mediating the inhibitory component occur only on the proximal axons of the ventral cells, both components are larger and reverse more readily in ventral cells. These findings suggest that the PSP is generated in the ventral cells. The biphasic PSP has no effect on electrical coupling, suggesting that it is not generated along the electrical pathways among the cells. Horseradish peroxidase (HRP) staining reveals that the lateral branches emerge from the proximal axons of the ventral cells only. In HRP-filled preparations processed for electron microscopy (EM) acetylcholinesterase is demonstrated at these branches where it occurs associated with synapses. The location on fine branches of the ventral cells explains the absence of an effect on electrotonic transmission, whereas the reluctance of components of the PSP to reverse at the expected potentials is due to the distribution of the synapses over more than one cell. It is concluded that the biphasic PSP is received only by the ventral cells and that it is conveyed electrotonically to the other cells.

Electrically coupled pacemaker neurons respond differently to same physiological inputs and neurotransmitters

1984 ◽  
Vol 51 (6) ◽  
pp. 1362-1374 ◽  
Author(s):  
E. Marder ◽  
J. S. Eisen
Keyword(s):  
Motor Neurons ◽  
Slow Wave ◽  
Lucifer Yellow ◽  
Electrical Coupling ◽  
Excitatory Postsynaptic Potential ◽  
Panulirus Interruptus ◽  
Bursting Neuron ◽  
Postsynaptic Potential ◽  
Pyloric Dilator ◽  
Muscarinic Cholinergic

The two pyloric dilator (PD) motor neurons and the single anterior burster (AB) interneuron are electrically coupled and together comprise the pacemaker for the pyloric central pattern generator of the stomatogastric ganglion of the lobster, Panulirus interruptus. Previous work (31) has shown that the AB neuron is an endogenously bursting neuron, while the PD neuron is a conditional burster. In this paper the effects of physiological inputs and neurotransmitters on isolated PD neurons and AB neurons were studied using the lucifer yellow photoinactivation technique (33). Stimulation of the inferior ventricular nerve (IVN) fibers at high frequencies elicits a triphasic response in AB and PD neurons: a rapid excitatory postsynaptic potential (EPSP) followed by a slow inhibitory postsynaptic potential (IPSP), followed by an enhancement of the pacemaker slow-wave depolarizations. Photoinactivation experiments indicate that the enhancement of the slow wave is due primarily to actions of the IVN fibers on the PD neurons but not on the AB neuron. Bath-applied dopamine dramatically alters the motor output of the pyloric system. Photoinactivation experiments show that 10(-4) M dopamine increases the amplitude and frequency of the slow-wave depolarizations recorded in the AB neurons but hyperpolarizes and inhibits the PD neurons. Bath-applied serotonin increases the frequency and amplitude of the slow-wave depolarizations in the AB neuron but has no effect on PD neurons. Pilocarpine, a muscarinic cholinergic agonist, stimulates slow-wave depolarization production in both PD neurons and the AB neuron, but the waveform and frequency of the slow waves elicited are quite different. These results show that although the electrically coupled PD and AB neurons always depolarize synchronously and act together as the pacemaker for the pyloric system, they respond differently to a neuronal input and to several putative neuromodulators. Thus, despite electrical coupling sufficient to ensure synchronous activity, the PD and AB neurons can be modulated independently.

Cholinergic interneurons in the feeding system of the pond snail lymnaea stagnalis. I. cholinergic receptors on feeding neurons

1992 ◽  
Vol 336 (1277) ◽  
pp. 157-166 ◽  
Keyword(s):  
Synaptic Input ◽  
Lymnaea Stagnalis ◽  
Cholinergic Receptors ◽  
Pond Snail ◽  
Feeding System ◽  
Inhibitory Receptor ◽  
Excitatory Response ◽  
Cholinergic Interneurons ◽  
Feeding Rhythm ◽  
Cholinergic Response

All the identified feeding motoneurons of Lymnaea respond to bath or iontophoretically applied acetylcholine (ACh). Three kinds of receptors (one excitatory, one fast inhibitory and one slow inhibitory) were distinguished pharmacologically. The agonist TMA (tetram ethylam m onium ) activates all three receptors, being weakest at the slow inhibitory receptor. PTMA (phenyltrim ethylam monium ) is less potent than TMA and is ineffective at the slow inhibitory receptor, which is the only receptor sensitive to arecoline. At 0.5 mM the antagonists HMT (hexamethonium) and ATR (atropine) selectively block the excitatory response, while PTMA reduces the response to ACh at all three receptors. d-TC (curare) antagonizes only the fast excitatory and the fast inhibitory responses, but MeXCh (methylxylocholine) blocks the fast excitatory and slow inhibitory responses solely. For each of the feeding motoneurons, the sign of the cholinergic response (excitation or inhibition) is the same as the synaptic input received in the N1 phase of the feeding rhythm .

Interneuronal Control of Feeding in the Pond Snail Lymnaea Stagnalis: II. The Interneuronal Mechanism Generating Feeding Cycles

1981 ◽  
Vol 92 (1) ◽  
pp. 203-228
Author(s):  
R. M. ROSE ◽  
P. R. BENJAMIN
Keyword(s):  
Cell Population ◽  
Synaptic Input ◽  
Lymnaea Stagnalis ◽  
Pond Snail ◽  
Feeding Cycle ◽  
Interneuronal Network

The feeding cycle of Lymnaea is generated by a network of three types of interneurone, N1, N2 and N3. This network is driven by the slow oscillator (SO) interneurone described in the previous paper. Interaction between the different interneurones is dependent on both connectivity and endogenous properties, and utilizes such properties as post-inhibitory rebound and self-feedback within electrically-coupled populations. Each of the four components of the interneuronal network (SO, N1, N2 and N3) is responsible for a different phase of synaptic input to the follower cell population which was previously shown to directly control feeding movements.

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.

Esophageal mechanoreceptors in the feeding system of the pond snail, Lymnaea stagnalis

1989 ◽  
Vol 61 (4) ◽  
pp. 727-736 ◽  
Author(s):  
C. J. Elliott ◽  
P. R. Benjamin
Keyword(s):  
Feeding Behavior ◽  
Synaptic Input ◽  
Lymnaea Stagnalis ◽  
Esophageal Wall ◽  
Pond Snail ◽  
Feeding System ◽  
Buccal Ganglia ◽  
Feeding Rhythm ◽  
Feeding Cycle ◽  
Stimulation Of

1. We identify esophageal mechanoreceptor (OM) neurons of Lymnaea with cell bodies in the buccal ganglia and axons that branch repeatedly to terminate in the esophageal wall. 2. The OM cells respond phasically to gut distension. Experiments with a high magnesium/low calcium solution suggest that the OM neurons are primary mechanoreceptors. 3. In the isolated CNS preparation, the OM cells receive little synaptic input during the feeding cycle. 4. The OM cells excite the motoneurons active in the rasp phase of the feeding cycle. 5. The OM cells inhibit each of the identified pattern-generating and modulatory interneurons in the buccal ganglia. Experiments with a saline rich in magnesium and calcium suggest that the connections are monosynaptic. 6. Stimulation of a single OM cell to fire at 5-15 Hz is sufficient to terminate the feeding rhythm in the isolated CNS preparation. 7. We conclude that these neurons play a role in terminating feeding behavior.

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 Integration of Wing Proprioceptive and Descending Exteroceptive Sensory Inputs by Thoracic Interneurones of the Locust

1987 ◽  
Vol 128 (1) ◽  
pp. 193-217
Author(s):  
ROBERT C. ELSON
Keyword(s):  
Synaptic Input ◽  
Head Movements ◽  
Excitatory Postsynaptic Potential ◽  
Directional Selectivity ◽  
Campaniform Sensilla ◽  
Postsynaptic Potential ◽  
Qualitative Dynamics ◽  
Instantaneous Frequencies ◽  
Flight Motor ◽  
Aerodynamic Lift

1. The campaniform sensilla on the wings of the locust are strain-sensitive mechanoreceptors that provide proprioceptive feedback about wing forces, particularly aerodynamic lift, experienced during flight. They can be excited by imposed deformations of the wing, including those caused by imposed wing twisting. The afferents of the single subcostal group of sensilla on the hindwing had the same directional selectivity for supinating twist and shared the properties of a dynamic sensitivity and adaptation. A group of strain-sensitive mechanoreceptors with similar properties, presumably campaniform sensilla, is also found in the forewings. 2. Four types of thoracic interneurones influenced by these factors were recorded and stained intracellularly. The response of interneurone 5AA to imposed deformations of the hindwing ipsilateral to its soma is determined by excitatory chemical synaptic input from the campaniform sensilla. Interneurone and sensilla have a common directional selectivity and optimal stimulus, and similar qualitative dynamics of response. Each spike of individual afferents is followed at short, constant latency by an excitatory postsynaptic potential (EPSP) in the interneurone, even at instantaneous frequencies of about 90 Hz. Physiological evidence is consistent with direct, chemically mediated synaptic inputs from campaniform sensilla afferents. 3. Interneurone 5AA is also excited by a short-latency, chemical synaptic input from the ocelli when lights are turned off. EPSPs could be elicited by light-off stimuli to the median and contralateral, but not the ipsilateral, ocelli. In addition, the interneurone is excited when the head is moved relative to the thorax. 4. The other three interneurones respond to strains in more than one wing. Inputs are derived from specific combinations of wings, with the sign of response depending on the neurone and the particular wing. Interneurones 3AA and 1AA are also phasically excited by light-off stimuli. In 1AA this response was shown to originate from the ocelli. Median and contralateral, but not ipsilateral, ocelli could evoke EPSPs. This neurone was also excited by imposed head movements. 5. It is argued that the interneurones described here at suited to monitor lift production in particular wings and its pattern among several wings. Convergence of ocellar and head-motion inputs implies a function in the exteroceptive detection and correction of flight instability. It is inferred that these thoracic interneurones may act as the nexus for several different feedback pathways, proprioceptive and exteroceptive, which modulate flight motor output.

scholarly journals A survey of miRNAs involved in biomineralization and shell repair in the freshwater gastropod Lymnaea stagnalis

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Nicolas Cerveau ◽  
Daniel John Jackson
Keyword(s):  
Matrix Protein ◽  
Lymnaea Stagnalis ◽  
Sequence Similarity ◽  
Mature Mirnas ◽  
Pond Snail ◽  
Mrna Levels ◽  
Forming Process ◽  
Rna Molecules ◽  
Freshwater Gastropod ◽  
Shell Matrix

AbstractMicroRNAs (miRNAs) are a deeply conserved class of small, single stranded RNA molecules that post-transcriptionally regulate mRNA levels via several targeted degradation pathways. They are involved in a wide variety of biological processes and have been used to infer the deep evolutionary relationships of major groups such as the Metazoa. Here we have surveyed several adult tissues of the freshwater pulmonate Lymnaea stagnalis (the Great Pond Snail) for miRNAs. In addition we perform a shell regeneration assay to identify miRNAs that may be involved in regulating mRNAs directly involved in the shell-forming process. From seven mature tissues we identify a total of 370 unique precursor miRNAs that give rise to 336 unique mature miRNAs. While the majority of these appear to be evolutionarily novel, most of the 70 most highly expressed (which account for 99.8% of all reads) share sequence similarity with a miRBase or mirGeneDB2.0 entry. We also identify 10 miRNAs that are differentially regulated in mantle tissue that is actively regenerating shell material, 5 of which appear to be evolutionarily novel and none of which share similarity with any miRNA previously reported to regulate biomineralization in molluscs. One significantly down-regulated miRNA is predicted to target Lst-Dermatopontin, a previously characterized shell matrix protein from another freshwater gastropod. This survey provides a foundation for future studies that would seek to characterize the functional role of these molecules in biomineralization or other processes of interest.

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