Neuropeptides: Mediators of Behavior in
            <i>Aplysia</i>

Scheller, Richard H.; Kaldany, R R; Kreiner, Thane; Mahon, Anne C.; Nambu, John R.; Schaefer, Mark; Taussig, Ronald

doi:10.1126/science.6474178

Cited by 90 publications

(30 citation statements)

References 26 publications

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“…Neuropeptides most likely represent the greatest diversity of chemical messengers in the nervous system and peripheral tissues (Scheller et al, 1984). Two small neuropeptides with cardioexcitatory actions, termed small cardioactive peptide A (SCP,) and B (SCP,), 11 and 9 amino acids long, respectively, are found in many gastropod species (see review by Lloyd, 1986).…”

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confidence: 99%

Modulation of calcium current and diverse K+ currents in identified Hermissenda neurons by small cardioactive peptide B

Acosta-Urquidi

1988

J. Neurosci.

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The molluscan neuropeptides, small cardioactive peptides A and B (SCPA,B), are known to modulate the responses of many molluscan central and peripheral target cells (see review by Lloyd, 1986), but their full range of physiological actions remains unknown. External application of SCPB (1–10 microM) modified diverse ionic conductances in a set of giant identifiable neurons in the brain of the marine mollusk Hermissenda crassicornis. SCPB caused a transient depolarization and increased input resistance that enhanced or promoted cell firing. Under voltage-clamp, SCPB reduced a “background” residual current (IR), reduced early transient K+ current (IA), reduced a delayed K+ current (IK(V], and enhanced ICa, IBa, and a Ca2+-activated K+ current, IK(Ca). In tetraethylammonium chloride (TEA) saline, SCPB enhanced the amplitude and duration and reduced the threshold of evoked Ca and Ba spikes. Immunocytochemical staining techniques have localized an endogenous SCPB-like peptide in numerous somata and their neurites in the nervous system of Hermissenda (Longley and Longley, 1985; Watson and Willows, 1986). These data are consistent with a role for SCPB as a neurotransmitter/neurohormone modulator of neuronal excitability in Hermissenda. A neurotransmitter role for endogenous SCPs has been proposed for a synaptic pair of cultured neurons in the Aplysia buccal ganglion (Lloyd et al., 1986). SCPB has been implicated in the control of feeding motor output in Aplysia (Sossin et al., 1986) and Tritonia (Willows and Watson, 1986), and in the presynaptic facilitation of sensory neurons mediating the gill and siphon defensive withdrawal reflex in Aplysia (Abrams et al., 1984).

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Modulation of calcium current and diverse K+ currents in identified Hermissenda neurons by small cardioactive peptide B

Acosta-Urquidi

1988

J. Neurosci.

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“…Peptides can be assayed directly for effects on identified neurons (Mayeri et al, 1985) thus making the difficult problem of comprehensive physiological characterization approachable. In addition, the genes encoding several neuropeptide precursors expressed in neurons of the abdominal ganglion have been cloned and characterized (Scheller et al, 1984). By determining the nucleotide sequence of genomic or cDNA clones, we have deduced the amino acid sequence of several peptide precursors, thus defining the potential peptide products.…”

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Proteolytic processing of the Aplysia egg-laying hormone and R3-14 neuropeptide precursors

Newcomb¹,

Scheller²

1987

J. Neurosci.

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A number of animal behaviors are influenced by the actions of neuropeptides that arise from the processing of complex protein precursors. In this report we investigate the proteolytic processing of neuropeptide precursors expressed in the Aplysia californica bag cells, which govern egg-laying, and neurons R3–14, which mediate aspects of cardiac output. Peptides were purified by fractionation on 2 high- pressure liquid chromatography systems followed by determination of amino acid compositions. Most of these compositions are indicative of processing products derived from the egg-laying hormone (ELH) and R3–14 precursors by cleavage at basic residues. We characterized 9 peptides that arise from the ELH precursor by cleavage of the signal sequence, as well as 7 out of 8 dibasic residues and at least 1 single Arg residue. The peptides range in size from 5 to about 60 amino acids. The R3–14 neuropeptide precursor is cleaved at 2 internal dibasic residues in addition to the signal sequence, resulting in 3 peptides. Shortened forms of several peptides probably result from amino- and carboxy- terminal peptidase action. It is likely that the complex mixtures of neuropeptides arising from these single protein precursors are co- secreted.

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“…However, there are relatively few systems in which peptidergic regulation of a discrete behavior appears amenable to physiological and anatomical analyses at the level of identified neurons. Certain invertebri systems (4)(5)(6), and especially neuronal systems controlling feeding in gastropod molluscs, may allow such analyses (7,8).…”

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Peptidergic modulation of patterned motor activity in identified neurons of Helisoma

Murphy¹,

Lukowiak²,

Stell

1985

Proc. Natl. Acad. Sci. U.S.A.

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The neuroaftive peptides SCPB (small cardioactive peptide B) and FMRFamide (Phe-Met-Arg-Phe-NH2), both originally isolated from molluscs, have potent modulatory effects upon the production of patterned motor activity in identified neurons (e.g., B5 and B19) in the buccal ganglia of the snail Helisoma. Such patterned motor activity has previously been shown to underlie feeding behavior. (7,8).Several aspects of the neural basis of feeding in the snail Helisoma trivolvis have been described. Cyclical activity of many identified effector neurons and elements of the central pattern generator has been characterized (9-11). In addition, the monoamines serotonin (12) and dopamine (13) have been shown to activate or modulate such patterned motor activity (PMA) associated with feeding and generated by neurons in the buccal ganglia. As a first step in characterizing the potential roles of neuroactive peptides in regulating feeding behavior in Helisoma, we report here that two neuroactive peptides, originally discovered in molluscs, have profound effects on the production of PMA (which apparently represents "fictive feeding") by buccal ganglion neurons. Small cardioactive peptide B (SCPB, Met-Asn-Tyr-Leu-Ala-PhePro-Arg-Met-NH2; ref. 14) has stimulatory effects upon the generation of PMA that resemble, at least superficially, those described for serotonin (5-hydroxytryptamine) and dopamine. In contrast, FMRFamide (Phe-Met-Arg-Phe-NH2; ref.15) inhibits and, at a sufficient concentration (10-5 M), effectively suppresses PMA in the buccal ganglia. SCP has been indicated, by chromatographic techniques, to occur in Helisoma central nervous system (see table 1 in ref. 14). We show here that the buccal ganglion ofHelisoma contains both neurons with SCPB-like immunoreactivity and neurons with anti-FMRFamide immunoreactivity.MATERIALS AND METHODS Albino specimens of Helisoma trivolvis were used; they were obtained from stocks maintained in the laboratory of A. G. M. Bulloch (University of Calgary) and derived from the Oregon Red stock of S. B. Kater's laboratory (University of Iowa). The dissection, the physiological saline, and the electrophysiological recording and display techniques have been described (16,17). For these experiments, either isolated buccal ganglia or buccal ganglia attached to the central ring of ganglia via the cerebrobuccal connectives were used. There was no detectable difference in the effects of peptides upon PMA whether or not the central ganglia were attached, but the rate of spontaneous PMA varies considerably and tends to be higher in isolated buccal ganglia. Once it had been determined that SCPB was excitatory and FMRFamide was inhibitory, relatively quiescent preparations were used for SCPB experiments and relatively active preparations were used for FMRFamide experiments. The synthetic peptides, SCPB (Peninsula Laboratories, San Carlos, CA) and FMRFamide (Sigma), were used. Saline volume (<0.5 ml) in the recording chamber was maintained by suction from the surface, and solutions were changed ...

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Neuropeptides: Mediators of Behavior in Aplysia

Cited by 90 publications

References 26 publications

Modulation of calcium current and diverse K+ currents in identified Hermissenda neurons by small cardioactive peptide B

Modulation of calcium current and diverse K+ currents in identified Hermissenda neurons by small cardioactive peptide B

Proteolytic processing of the Aplysia egg-laying hormone and R3-14 neuropeptide precursors

Peptidergic modulation of patterned motor activity in identified neurons of Helisoma

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