Crustacean cardioactive peptide (CCAP)-related molluscan peptides (M-CCAPs) are potential extrinsic modulators of the buccal feeding network in the pond snail Lymnaea stagnalis.
We combine electrophysiological and immunocytochemical analyses in the snail Lymnaea stagnalis of M-CCAP1 and M-CCAP2, two molluscan peptides with structure similar to crustacean cardioactive peptide CCAP, originally isolated from the snail Helix pomatia. Both M-CCAP peptides (M-CCAP1 and M-CCAP2, 1 microM) had an excitatory effect, depolarizing all the identified neurons of the buccal feeding network (including motoneurons: B1, B2, B4 and modulatory interneurons SO, OC: 62 neurons in 33 preparations). Additionally, in 67% of preparations, rhythmic activity (fictive feeding) was recorded with a mean rate of 7 cycles/min. No significant difference in the proportion of preparations showing fictive feeding or mean feeding rate was found between M-CCAP1 and M-CCAP2. The extrinsic feeding modulator, the serotonergic CGC neuron, responds by increase of the spontaneous activity after M-CCAP application (9 of 18 preparations). Crustacean CCAP (1 microM) evokes a slight membrane depolarization in 3 out of 8 preparations but never evokes fictive feeding. Immunostaining revealed no cell bodies in the buccal ganglia, but a dense network of CCAP immunopositive fibers arborizing in the buccal neuropil. Many of these fibers originate from a symmetrical pair of CCAP-immunoreactive cerebro-buccal interneurons, which are the most likely candidates for extrinsic modulatory interneurons in the buccal feeding network. Our data are the first results suggesting that M-CCAP-peptides exist as effective modulators in mollusc.
Vehovszky
Agnes
A
Department of Experimental Zoology, Balaton Limnological Research Institute, Hungarian Academy of Sciences, P.O. Box 35, 3 Klebelsberg, Tihany H-8237, Hungary. agnes@tres.blki.hu
Agricola
Hans-Jürgen
HJ
Elliott
Christopher J H
CJ
Ohtani
Masahiro
M
Kárpáti
Levente
L
Hernádi
László
L
D000818:Animals; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D008195:Lymnaea / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*; D009061:Mouth Mucosa / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*; D009415:Nerve Net / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*; D009479:Neuropeptides / Q000235:genetics / Q000494:pharmacology* / Q000502:physiology
D009479:Neuropeptides; C058620:crustacean cardioactive peptide