Presence of an adipokinetic peptide in the corpus cardiacum of Dermaptera but not in the neurohaemal aorta, and chemical and functional identification of the peptide

Abstract

Corpora cardiaca of the earwigs Labidura riparia and Forficula auricularia contain a substance that causes hyperlipaemia in migratory locusts and hypertrehalosaemia in the American cockroaches. A conspecific bioassay in L. riparia revealed that this factor is lipid‐mobilizing. Isolation of the neuropeptide was achieved by single‐step RP‐HPLC. The primary structure of the earwig adipokinetic peptide was elucidated by automated Edman degradation in combination with matrix‐assisted laser desorption/ionization mass spectrometry. It is a blocked octapeptide, pGlu‐Val‐Asn‐Phe‐Ser‐Thr‐Gly‐Trp‐NH2, previously denoted as Grb‐AKH and first identified in Gryllus bimaculatus ( Gäde & Rinehart 1987). The synthetic peptide co‐chromatographed under various conditions with the native peptide and, in biological assays, resulted in lipid‐mobilization in L. riparia when injected in low concentration.

Changes in the lipid and fatty acid composition of hemolymph and ovaries during the reproductive cycle of Labidura riparia

“…In several insects, neuropeptides belonging to the adipokinetic hormone (AKH) family that are released from the corpora cardiaca, where they are synthesized and stored, induce lipid mobilization from the fat body (Gäde 2004). This has also been demonstrated in the earwig L. riparia (Gäde 1999). The key enzyme during lipid mobilization in the fat body is triacylglycerol lipase (Ryan & van der Horst 2000), which is under the control of AKH in L. migratoria (Auerswald & Gäde 2006).…”

Diel changes in adipokinetic response and walking activity of Pyrrhocoris apterus (Heteroptera) in relation to physiological status and wing dimorphism

“…Many AKHs have been isolated from cor pora cardiaca and characterized in a great number of insect orders (Gade et al, 1997;Gade, 1999;Lorenz et al, 1999), and recently also in the firebug Pyrrhocoris apterus, a representative species of the suborder Heterop tera (Kodrik et al, 2000). Almost all of these hormones are octa-, nona-or decapeptides with characteristic struc tural similarities (Gade et al, 1997), and they are grouped into the AKH/RPCH (Adipokinetic Hormone/Red Pig ment Concentrating Hormone) family.…”