Identification of a new neuropeptide precursor reveals a novel source of extrinsic modulation in the feeding system of Aplysia.

TitleIdentification of a new neuropeptide precursor reveals a novel source of extrinsic modulation in the feeding system of Aplysia.
Publication TypeJournal Article
Year of Publication2005
AuthorsProekt A, Vilim FS, Alexeeva V, Brezina V, Friedman A, Jing J, Li L, Zhurov Y, Sweedler JV, Weiss KR
JournalJ Neurosci
Date Published2005 Oct 19
KeywordsAmino Acid Sequence, Animals, Aplysia, Feeding Behavior, Ganglia, Invertebrate, Molecular Sequence Data, Neuropeptides, Protein Precursors

The Aplysia feeding system is advantageous for investigating the role of neuropeptides in behavioral plasticity. One family of Aplysia neuropeptides is the myomodulins (MMs), originally purified from one of the feeding muscles, the accessory radula closer (ARC). However, two MMs, MMc and MMe, are not encoded on the only known MM gene. Here, we identify MM gene 2 (MMG2), which encodes MMc and MMe and four new neuropeptides. We use matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to verify that these novel MMG2-derived peptides (MMG2-DPs), as well as MMc and MMe, are synthesized from the precursor. Using antibodies against the MMG2-DPs, we demonstrate that neuronal processes that stain for MMG2-DPs are found in the buccal ganglion, which contains the feeding network, and in the buccal musculature including the ARC muscle. Surprisingly, however, no immunostaining is observed in buccal neurons including the ARC motoneurons. In situ hybridization reveals only few MMG2-expressing neurons that are mostly located in the pedal ganglion. Using immunohistochemical and electrophysiological techniques, we demonstrate that some of these pedal neurons project to the buccal ganglion and are the likely source of the MMG2-DP innervation of the feeding network and musculature. We show that the MMG2-DPs are bioactive both centrally and peripherally: they bias egestive feeding programs toward ingestive ones, and they modulate ARC muscle contractions. The multiple actions of the MMG2-DPs suggest that these peptides play a broad role in behavioral plasticity and that the pedal-buccal projection neurons that express them are a novel source of extrinsic modulation of the feeding system of Aplysia.

Alternate JournalJ. Neurosci.
PubMed ID16237168
Grant ListDA13330 / DA / NIDA NIH HHS / United States
MH35564 / MH / NIMH NIH HHS / United States
NS31609 / NS / NINDS NIH HHS / United States
P30DA18310 / DA / NIDA NIH HHS / United States
RR10294 / RR / NCRR NIH HHS / United States