Hypertrehalosaemic and hyperlipaemic responses to adipokinetic hormone in fifth larval instar locusts, Locusta migratoria

Abstract

Abstract--In fifth instar larvae of Locusta migratoria the haemolymph lipid concentration is elevated after injection of adipokinetic hormone (AKH). This hyperlipaemic response in larvae remains substantially lower than in adults; over 75% of the mobilized lipid consists of diacylglycerol. In addition, unlike adult locusts, fifth instar larvae also exhibit a consistent, though moderate, hypertrehalosaemic response to AKH. The increases of both lipid and carbohydrate concentrations in larvae are dose-dependent, showing a significant linear regression on log dose in the range 0.2-20pmol AKH.Glycogen phosphorylase in the fat body of fifth instar larvae as well as young adults is activated on injection of AKH, the percentage active phosphorylase increasing linearly with log dose in the range 0.04-20 pmol AKH. For a given response, a somewhat higher dose of AKH is needed in larvae than in young adults.Fat body glycogen phosphorylase is strongly activated during the period of the larval-adult ecdysis, when active phosphorylase accounts for almost half of the total enzyme, which is approximately ten times more than it is two days before, and two days after the ecdysis.The corpora cardiaca of fifth larval instar locusts already possess the potencies to elevate carbohydrate and lipid concentrations in larval haemolymph, and to activate fat body glycogen phosphorylase.

Topical application of Pya‐AKH stimulates lipid mobilization and locomotion in the flightless bug, Pyrrhocoris apterus (L.) (Heteroptera)

“…The lipid content of the haemolymph was determined by the sulpho‐phosphovanillin test (Zöllner & Kirsch, 1962) as modified by Holwerda et al . (1977) and Van Marrewijk et al . (1984).…”

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

“…The top of antenna was cut off by scissors and a drop of haemolymph was leaked onto a piece of parafilm M. An aliquot of 0.5 pl haemolymph was taken by a micropipette from the drop and used for the determination of lipids. Lipid concentration in the haemolymph samples was determined by a method based on the supho-phosphovanillin test (Zollner & Kirsch, 1962; modified by Holwerda et al, 1977 andVan Marrewijk et al, 1984). The optical densities, recorded at 546 nm in a spectrophotometer (UV-1601 Shimadzu), were converted to mg lipids per ml of haemolymph with the aid of a calibration graph, based on known aliquots of oleic acid, using MS Excel.…”

Crustacean red pigment-concentrating hormone Panbo-RPCH affects lipid mobilization and walking activity in a flightless bug Pyrrhocoris apterus (Heteroptera) similarly to its own AKH-peptides

“…The lipid content of the haemolymph samples was determined by the assay described previously (Kodrík et al, 2000) that is based on the sulpho-phosphovanilin test (Zöllner & Kirsch, 1962;modified by Holwerda et al, 1977 andVan Marrewijk et al, 1984). The haemolymph samples were taken from the cut end of an antenna: a drop of haemolymph was leaked onto a piece of parafilm M and 0.5 µl taken up by a micropipette (Eppendorf Varipipette 4810); the samples were collected just before and 90 min after the hormonal injection and used for the determination of lipids.…”