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The association of the FMRFamide-related peptide family with the heart of the stick insect, Baculum extradentatum

Authors Calvin A, Lange A

Published 16 March 2010 Volume 2010:2 Pages 1—10


Review by Single anonymous peer review

Peer reviewer comments 2

Amanda Calvin, Angela B Lange

Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada

Abstract: The neural anatomy of the heart of the Vietnamese stick insect, Baculum extradentatum consists of a dorsal vessel with lateral cardiac nerves containing cardiac neurons. It also has nerve projections from the segmental nerves. Some of the nerve processes pass over the alary muscles. Multiple pairs of bipolar neurons with axons in the segmental nerve lie on the dorsal diaphragm either side of the heart. FMRFamide-like immunoreactive staining is present in the peripheral nervous system, including the nerve branches from the segmental nerve that project to the heart. Immunoreactive processes are present over the incurrent and excurrent ostia of the heart and in the lateral cardiac nerves, cardiac neurons and in the paired bipolar neurons. SchistoFLRFamide, a myosuppressin, has a dose-dependent inhibitory effect on dorsal vessel contraction. The minimum sequence required for inhibition was examined using truncated peptides, and found to be HVFLRFamide. The truncated peptide VFLRFamide showed activity reversal, being slightly stimulatory. The nonpeptide, benzethonium chloride, mimicked the effects of SchistoFLRFamide. The localization of FMRFamide-like immunoreactivity within the innervation to the heart, coupled with the cardioinhibitory effect of SchistoFLRFamide, suggests a possible role for this family of peptides as neuromodulators in the cardiac musculature in B. extradentatum.

Keywords: dorsal vessel, peptide, immunohistochemistry, SchistoFLRFamide, cardiac neurons, excurrent ostia

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