Cholinergic neuromuscular synapses in Aplysia have low endogenous acetylcholinesterase activity and a high-affinity uptake system for acetylcholine

Lloyd, PE; Church, PJ

doi:10.1523/jneurosci.14-11-06722.1994

Cited by 16 publications

(13 citation statements)

References 35 publications

(57 reference statements)

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“…The reason for these contradictory interpretations remains obscure, but could be confounded in part by the use of diVerent techniques to visualize early neural elements. SpeciWcally, the cholinesterase staining lacks the resolution aVorded by modern confocal microscopy and cholinesterase activity has also been found in glial-like cells, muscle cells and ciliary organs in molluscs (Lloyd and Church 1994). However, it should also be noted that an earlier description of the nervous system in veligers of M. edulis (Koolakovsky and Phlyachinskaya 1993) based on cholinesterase activity staining generally corresponds to our data and contradicts the description by Raineri (1995).…”

Section: Novel Features Of Neural Developmentcontrasting

confidence: 63%

Neuronal development in larval mussel Mytilus trossulus (Mollusca: Bivalvia)

et al. 2008

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Although our understanding of neuronal development in Trochozoa has progressed substantially in recent years, relatively little attention has been paid to the bivalve molluscs in this regard. In the present study, the development of FMRFamide-, serotonin-and catecholamine-containing cells in the mussel, Mytilus trossulus, was examined using immunocytochemical and histoXuorescent techniques. Neurogenesis starts during the trochophore stage at the apical extreme with the appearance of one FMRFamide-like immunoreactive (lir) and one serotonin-lir sensory cell. Later, Wve FMRFamide-lir and Wve serotonin-lir apical sensory cells appear, and their basal Wbres form an apical neuropil. Fibres of two lateral FMRFamide-lir apical cells grow posteriorly and at the time that they reach the developing foot, the Wrst FMRFamide-lir neurons of the pedal ganglia also appear. Subsequently, FMRFamide-lir Wbres grow further posteriorly and reach the caudal region where neurons of the developing visceral ganglia then begin to appear. In contrast, the Wve apical serotonin-lir neurons do not appear to project outside the apical neuropil until the late veliger stage. Catecholamine-containing cells are Wrst detected in the veliger stage where they appear above the oesophagus, and subsequently in the velum, foot, and posterior regions. Though neural development in M. trossulus partly resembles that of polyplacophorans in the appearance of the early FMRFamidergic elements, and of scaphopods in the appearance of the early serotonergic elements, the scenario of neural development in M. trossulus diVers considerably from that of other Trochozoa (bivalves, gastropods, polyplacophorans, scaphopods and polychaetes) studied to date.

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Section: Novel Features Of Neural Developmentcontrasting

confidence: 63%

Neuronal development in larval mussel Mytilus trossulus (Mollusca: Bivalvia)

et al. 2008

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“…Thus, release of classical transmitter correlates with contraction amplitude that in turn correlates with peptide cotransmitter release. In addition, release of ACh appears to be frequency-dependent (Lloyd and Church, 1994) as is peptide cotransmitter release. Hence, peptide cotransmitter and classical transmitter release appear to be functionally coupled in this system.…”

Section: Discussionmentioning

confidence: 99%

Peptide Cotransmitter Release from Motorneuron B16 inAplysia californica: Costorage, Corelease, and Functional Implications

et al. 2000

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Many neurons contain multiple peptide cotransmitters in addition to their classical transmitters. We are using the accessory radula closer neuromuscular system of Aplysia, which participates in feeding in these animals, to define the possible consequences of multiple modulators converging on single targets. How these modulators are released onto their targets is of critical importance in understanding the outcomes of their modulatory actions and their physiological role. Here we provide direct evidence that the partially antagonistic families of modulatory peptides, the myomodulins and buccalins, synthesized by motorneuron B16 are costored and coreleased in fixed ratios. We show that this release is calcium-dependent and independent of muscle contraction. Furthermore, we show that peptide release is initiated at the low end of the physiological range of motorneuron firing frequency and that it increases with increasing motorneuron firing frequency. The coordination of peptide release with the normal operating range of a neuron may be a general phenomenon and suggests that the release of peptide cotransmitters may exhibit similar types of regulation and plasticity as have been observed for classical transmitters. Stimulation paradigms that increase muscle contraction amplitude or frequency also increase peptide release from motor neuron B16. The net effect of the modulatory peptide cotransmitters released from motorneuron B16 would be to increase relaxation rate and therefore allow more frequent and/or larger contractions to occur without increased resistance to antagonist muscles. The end result of this modulation could be to maximize the efficiency of feeding.

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“…The ARC is a nonspiking muscle that contracts in response to ACh released from motorneuron terminals (Cohen et al, 1978;Lloyd and Church, 1994). The amplitude of contractions is related to muscle depolarization and the resulting inward calcium current (Brezina et al, 1994;Kozak et al, 1996).…”

Section: Stimulation Paradigm and Its Rationalementioning

confidence: 99%

Release of Peptide Cotransmitters inAplysia: Regulation and Functional Implications

et al. 1996

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To gain insights into the physiological role of cotransmission, we measured peptide release from cell B15, a motorneuron that utilizes ACh as its primary transmitter but also contains putative peptide cotransmitters, the small cardioactive peptides (SCPs) and the buccalins (BUCs). All stimulation parameters used were in the range in which B15 fires in freely moving animals. We stimulated neuron B15 in bursts and systematically varied the interburst interval, the intraburst frequency, and burst duration. Both peptides were preferentially released when B15 was stimulated at higher intra- or interburst frequencies or with longer burst durations. Across stimulation patterns, the amount of peptide released depended on the mean frequency of stimulation and was independent of the specific pattern of stimulation. The parameters of stimulation that produce a larger release of peptides correspond to those that evoke larger contractions. Large and frequent contractions are likely to fuse or summate, thus disrupting the rhythmic behavior mediated by the muscle innervated by motorneuron B15. Because the combined effect of the SCPs and BUCs is to accelerate the relaxation and shorten the duration of muscle contractions, these peptides reduce the probability of the disruptive fusion or summation of muscle contractions. Because these cotransmitters regulate an aspect of muscle contractions that is not controlled by acetylcholine (ACh), the primary transmitter of B15, we suggest that peptides and ACh form parallel but functionally distinct lines of transmission at the neuromuscular junction. Both types of transmission may be necessary to ensure that behavior remains efficient over a wide range of conditions.

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Cholinergic neuromuscular synapses in Aplysia have low endogenous acetylcholinesterase activity and a high-affinity uptake system for acetylcholine

Cited by 16 publications

References 35 publications

Neuronal development in larval mussel Mytilus trossulus (Mollusca: Bivalvia)

Neuronal development in larval mussel Mytilus trossulus (Mollusca: Bivalvia)

Peptide Cotransmitter Release from Motorneuron B16 inAplysia californica: Costorage, Corelease, and Functional Implications

Release of Peptide Cotransmitters inAplysia: Regulation and Functional Implications

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