Adipokinetic Hormones: Coupling between Biosynthesis and Release

Abstract

During long-distance flight of migratory locusts, the dramatic energy demand of the flight muscles is controlled by three adipokinetic hormones (AKHs). These peptide hormones regulate the mobilization of lipid and carbohydrate stored in the fat body to serve as energy substrates for the flight muscles. Despite the relatively huge quantities of the three AKHs that are stored in the corpora cardiaca, flight induces a differential 2-4-fold increase in the mRNAs for the three hormones. Moreover, newly synthesized AKHs can be released only during a restricted period of time, suggesting that by far most of the stored hormones are physiologically inactive. This raises the question of how the biosynthetic activity in the AKH-producing cells is coupled to their secretory activity. The present review discusses the potential mechanisms by which generation and release of mixtures of bioactive neurohormones are controlled and how peptidergic neuroendocrine cells cope with variations in physiological stimulation, with the AKH-producing cells serving as a model system.

Fat body glycogen serves as a metabolic safeguard for the maintenance of sugar levels in Drosophila

“…We showed that the fat body glycogen is almost completely consumed after 4 h of starvation. Akh derived from the CC has been described to play a crucial role in the mobilization of energy sources, including glycogen, in a broad range of insects (Oudejans et al, 1999;Arrese and Soulages, 2010). Despite the accumulating evidence showing the contribution of CC-derived hormones to glycogen mobilization, we did not observe a significant impact of CC, Akh or AkhR on the mobilization of fat body glycogen during the larval period.…”

Peptidomics of the pars intercerebralis–corpus cardiacum complex of the migratory locust, Locusta migratoria

“…AKHs are insect neurohormones, which regulate the mobilization of lipids and carbohydrates stored in the fat body to serve as energy substrates for the flight muscles [23]. The synthesis and release of AKHs by the intrinsic neuroendocrine cells of the CC has been known for some time, and a single short HPLC‐run also allows the identification of AKH‐I and II in a single CC [24].…”

The neuroendocrine system of invertebrates: a developmental and evolutionary perspective

“…The corresponding structures in arthropods would be the PI/PL and their peripheral targets, the CC/CA respectively. The main hormone produced by the CC, adipokinetic hormone (AKH), mobilizes lipids and carbohydrates from the fat body (O'Shea & Rayne 1992, Oudejans et al 1999, Van der Horst et al 2001, Diederen et al 2002 and thereby resembles vertebrate glucagon that is produced in endocrine cells of the pancreas, as well as peptidergic neurons in the brain (Han et al 1986). AKH also shows some sequence similarity with the N-terminus of glucagons (Scarborough et al 1984).…”

“…The glandular lobe of the CC produces several hormones, including AKH, certain glycemic factors, cardiac-accelerating factors, and melanin-inducing factor. The AKH hormones are the major products of the CC, which are secreted into the hemolymph to mobilize lipids and carbohydrates during flight (O'Shea & Rayne 1992, Noyes et al 1995, Veelaert et al 1998, Nassel 1999, Oudejans et al 1999.…”