Abstract:
This chapter describes the current knowledge of the structure of the insect neuroendocrine system, including the distribution of insect neuropeptides (Np) and their receptors, and lists the various Np families and their diverse functions. The Nps are bioactive peptides of neuronal origin that are found throughout the animal kingdom, forming a most structurally and functionally diverse group of compounds. Nps have been well conserved during the course of evolution, indicating their major role as regulators of physiological processes. Nps are extracellular chemical messengers that act as circulating neurohormones, as local co-transmitters or as neuromodulators, and in the hierarchy of entities that regulate endogenous biochemical control functions, the Np messengers rank the highest, regulating almost every aspect of life. In insects, Nps regulate a long list of physiological and behavioral processes during development, reproduction, and senescence, and they maintain growth, homeostasis, osmoregulation, water balance, metabolism, and visceral activities. In the past two decades, many insect Nps have been identified, the basic principles of their action, e.g., biosynthesis, processing, release, transport, activation of the target cell, and degradation have been revealed, and their roles in the physiology of organisms have been determined by means of genome sequencing, peptidomics, gene microarrays, receptor characterization, and targeted gene interference, all combined with physiological, electrophysiological, and behavioral analysis. © 2009 Elsevier Inc. All rights reserved.