Neuropeptides Modulate the Heart of the Stick Insect Baculum extradentatum

Abstract

The dorsal vessel of the stick insect Baculum extradentatum consists of a tubular heart and an aorta that extends anteriorly into the head. Alary muscles, associated with the heart, are anchored to the body wall with attachments to the dorsal diaphragm. Alary muscle contraction draws hemolymph into the heart through incurrent ostia. Hemolymph exits the heart through the excurrent ostia present on the dorsal vessel in thoracic and abdominal segments. FMRFamide-related peptides are present in axons of the segmental nerves that project to the dorsal vessel and in processes extending over the heart and alary muscles. Immunoreactive processes are also localized to the valves of the incurrent ostia and excurrent ostia and to the lateral cardiac nerve and lateral cardiac neurons.

Proctolin in the antennal circulatory system of lower Neoptera: a comparative pharmacological and immunohistochemical study

“…The pentapeptide proctolin (RYLPT‐OH) was the first insect neuropeptide identified from whole body extracts of P. americana where it is associated with myostimulatory action on hindgut visceral muscles (Starratt & Brown, 1975). Proctolin has been identified subsequently in many other insects and other arthropods, and is a highly potent stimulator of a variety of visceral and skeletal muscles, including the dorsal heart (Orchard et al , 1989; Lange & Orchard, 2006; Lange et al , 2009). Moreover, proctolin is the most potent myostimulatory neuropeptide in the antennal circulatory system of P. americana , and its functional relevance as a peptide transmitter acting via a decrease of the K + ‐conductance is demonstrated (Hertel et al , 1997).…”

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

“…26,32 The innervation to B. extradentatum dorsal vessel contains other neuropeptides families, including CCAP and proctolin 16,17 and these peptides accelerate heart beat frequency. The staining pattern for FLI shares some similarity with the staining pattern for proctolin and CCAP in B. extradentatum, 16,18 although at present we do not know which members of the FaRP family are actually present. Thus, CCAP-like, proctolin-like and FLI are present within processes over the incurrent ostia and alary muscles.…”

“…For example, a number of studies have reported the presence of crustacean cardioactive peptide (CCAP), proctolin, and FMRFamiderelated peptides (FaRPs) with the innervation to the dorsal vessel in insects, and have demonstrated effects on heart beat frequency. [16][17][18][19][20][21][22] In addition, the presence of excurrent ostia suggests another form of microcirculatory control, and if these excurrent ostia are controlled (opened and closed) then microcirculatory pathways can be established. This control is suggested by the recent demonstration that the excurrent ostia in B. extradentatum stains with F-actin, indicating the presence of muscle cells.…”

FMRFamide-Related Peptides Signaling Is Involved in the Regulation of Muscle Contractions in Two Tenebrionid Beetles

“…FaLPs signaling has been studied in variety of insect species, including mosquitoes (Hillyer et al, 2014), stick insects (Lange et al, 2009), kissing bugs (Sedra and Lange, 2014), or flies (Merte and Nichols, 2002). However, the receptor for FaLPs was first discovered (Cazzamali and Grimmelikhuijzen, 2002) and very well characterized only in D. melanogaster (Maynard et al, 2013;Milakovic et al, 2014).…”

“…Other known functions of FaLPs include involvement in regulation of circadian rhythm (Pyza and Meinertzhagen, 2003) and synaptic activity (Marques et al, 2003). Most of the research has been performed on different insect species, such as flies (Merte and Nichols, 2002), locusts (Robb and Evans, 1994), stick insects (Lange et al, 2009), or mosquitoes (Hillyer et al, 2014). However, scarce information is available regarding FaLPs in the largest insect order -the beetles.…”