Endocrine peptides and insect reproduction (original) (raw)
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Insect gonadotropic peptide hormones: some recent developments
Journal of Peptide Science, 2006
Gonadotropic peptides are a new generation of peptide hormone regulators of insect reproduction. They have been isolated from ovaries, oviducts, or brains of insects. The subject of this paper is insect peptides that exert stimulatory or inhibitory effects on ovarian development and oocyte maturation. On the basis of the literature data and the results of our investigations, the structure and biological properties of different groups of peptides are presented.
Current Opinion in Insect Science, 2019
The physiological control of reproduction in insects depends on a combination of environmental and internal cues. In the adult stage, insects become sexually mature and generate gametes. In females, the latter process is designated as oogenesis. Peptides are a versatile class of extracellular signalling molecules that regulate many processes, including oogenesis. At present, the best documented physiological control mechanism of insect oogenesis is the insulin-related peptide signalling pathway. It regulates different stages of the process and provides a functional link between nutritional status and reproduction. Several other peptides have been shown to exert gonadoregulatory activities, but in most cases their exact mode of action still has to be unravelled and their effects on oogenesis could be direct or indirect. Some regulatory peptides, such as the Drosophila sex peptide, are being transferred from the male to the female during the mating process.
Neuroendocrinological and Molecular Aspects of Insect Reproduction
Journal of Neuroendocrinology, 2004
This review summarizes recent advances and novel concepts in the area of insect reproductive neuroendocrinology. The role of ÔclassicÕ hormones, such as ecdysteroids and juvenoids, to control reproduction is well documented in a large variety of insect species. In adult gonads, ecdysteroids appear to induce a cascade of transcription factors, many of which also occur during the larval molting response. Recent molecular and functional data have created opportunities to study an additional level of regulation, that of neuropeptides, growth factors and their respective receptors. As a result, many homologs of factors playing a role in vertebrate reproductive physiology have been discovered in insects. This review highlights several neuropeptides controlling the biosynthesis and release of the ÔclassicÕ insect hormones, as well as various peptides and biogenic amines that regulate behavioural aspects of the reproduction process. In addition, hormone metabolizing enzymes and second messenger pathways are discussed with respect to their role in reproductive tissues. Finally, we speculate on future prospects for insect neuroendocrinological research as a consequence of the recent ÔGenomics RevolutionÕ.
Role of Endocrine System in the Regulation of Female Insect Reproduction
Biology, 2021
The proper synthesis and functioning of ecdysteroids and juvenile hormones (JHs) are very important for the regulation of vitellogenesis and oogenesis. However, their role and function contrast among different orders, and even in the same insect order. For example, the JH is the main hormone that regulates vitellogenesis in hemimetabolous insect orders, which include Orthoptera, Blattodea, and Hemiptera, while ecdysteroids regulate the vitellogenesis among the insect orders of Diptera, some Hymenoptera and Lepidoptera. These endocrine hormones also regulate each other. Even at some specific stage of insect life, they positively regulate each other, while at other stages of insect life, they negatively control each other. Such positive and negative interaction of 20-hydroxyecdysone (20E) and JH is also discussed in this review article to better understand the role of these hormones in regulating the reproduction. Therefore, the purpose of the present review is to deeply understand th...
Hormonal regulation in insects: facts, gaps, and future directions
Physiological Reviews, 1997
There are two main classes of hormones in insects: 1) the true hormones produced by epithelial glands and belonging to the ecdysteroids or juvenile hormones and 2) the neuropeptide hormones produced by neurosecretory cells. Members of these classes regulate physiological, developmental, and behavioral events in insects. Detailed accounts are given on isolation, identification, structure-activity relationships, mode of action, biological function, biosynthesis, inactivation, metabolism, and feedback for hormones involved in 1) metabolic regulation such as the adipokinetic/hypertrehalosemic peptides and the diuretic and antidiuretic peptides; 2) stimulation or inhibition of muscle activity such as the myotropic peptides; 3) control of reproduction, growth, and development such as allatotropins, allatostatins, juvenile hormones, ecdysteroids, folliculostimulins and folliculostatins, ecdysis-triggering and eclosion hormones, pheromone biosynthesis activating neuropeptides, and diapause ...
Understanding insect endocrine systems: molecular approaches*
Entomologia Experimentalis et Applicata, 2000
Molecular approaches have led to spectacular improvement of our knowledge of insect endocrinology. The present review focuses on two major classes of insect lipidic hormones, ecdysteroids and juvenile hormones. Although the ecdysteroid biosynthetic pathway is not yet fully elucidated, several new steps have been recently characterized, and molecular studies of biosynthetic enzymes are now beginning. It is expected that, thanks to suitable biological models (e.g., ecdysteroid-defective mutants of Drosophila), the entire biosynthetic pathway will be elucidated in the near future. The understanding of the ecdysteroid mode of action has benefited from studies with Drosophila and major developments relate to the cascades of gene activation and the molecular basis for the stage-and tissuespecificity of hormonal effects. The biosynthetic pathway of juvenile hormones is fully known, but molecular studies of enzymes are still in their infancy, and there is some controversy about the nature of juvenile hormone receptors. Within the forthcoming years, molecular tools will allow to characterize all the enzymes involved in hormone biosynthesis and then to analyze the fine regulation of hormone titers. They will also allow comparative studies aimed at investigating the presence of related molecules (hormone biosynthetic enzymes and receptors) among other Invertebrates (Arthropods and non-Arthropods), and thus to propose evolutionary scenarios for their endocrine systems.
Journal of Insect Physiology, 1999
Previous studies demonstrate that virgin female adult Helicoverpa armigera (Lepidoptera: Noctuidae) moths exhibit calling behaviour and produce sex pheromone in scotophase from the day after emergence, and that mating turns off both of these pre-mating activities. In the fruit fly Drosophila melanogaster, a product of the male accessory glands, termed sex peptide (SP), has been identified as being responsible for suppressing female receptivity after transfer to the female genital tract during mating. Juvenile hormone (JH) production is activated in the D. melanogaster corpus allatum (CA) by SP in vitro. We herein demonstrate crossreactivity of D. melanogaster SP in the H. armigera moth: JH production in photophase virgin female moth CA in vitro is directly activated in a dose-dependent manner by synthetic D. melanogaster SP, and concurrently inhibits pheromone biosynthesis activating neuropeptide (PBAN)-activated pheromone production by isolated pheromone glands of virgin females. Control peptides (locust adipokinetic hormone, AKH-I, and human corticotropin, ACTH) do not inhibit in vitro pheromone biosynthesis. Moreover, SP injected into virgin H. armigera females, decapitated 24 h after eclosion, or into scotophase virgin females, suppresses pheromone production. In the light of these results, we hypothesize the presumptive existence of a SP-like factor among the peptides transmitted to female H. armigera during copulation, inducing an increased level of JH production and depressing the levels of pheromone produced thereafter.
Gonadotropins in insects: An overview
Archives of Insect Biochemistry and Physiology, 2001
Control of gonad development in insects requires juvenile hormone, ecdysteroids, and a peptidic brain gonadotropin(s). Compared to vertebrates, the situation in insects with respect to the molecular structure of gonadotropins is far less uniform. Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) of vertebrates are glycoproteins that are synthezised in the hypothalamus and released from the anterior pituitary. They stimulate gonad development, the production of progesterone or of sex steroids (estrogens, androgens). None of the known insect gonadotropins is a glycoprotein, neither can they be grouped into a single peptide family. In Drosophila, two G-protein coupled receptors, structurally related to the mammalian glycoprotein hormone receptors, have been identified. Nothing is known about their natural ligands. The sex-steroids of insects are likely to be ecdysteroids (20E in females, E in males of some species). Some of the identified gonadotropins speed up vitellogenesis (locust OMP and some -PF/-RFamide peptides) or stimulate ecdysteroid production by the ovaries (locust-OMP and Aedes- OEH) or testis (testis ecdysiotropin of Lymantria). In flies, the only as yet identified gonadotropin is the cAMP-generating peptide of Neobellieria. The seeming absence of uniformity in gonadotropins in insects might be due to a multitude of factors that can stimulate ecdysteroid production and/or to the use of different bioassays. Arch. Insect Biochem. Physiol. 47:129–138, 2001. © 2001 Wiley-Liss, Inc.
“Insects Do Not Have Sex Hormones”: A Myth?
General and Comparative Endocrinology, 1998
Mammals have two genes (SRYandDMT1) for testis formation–androgenesis, an anti-testis gene,DAX1,an anti-Müllerian duct hormone, and steroid sex hormones.Drosophilauses thesex-lethal, transformer,anddoublesexgenes for sexual differentation and is supposed to lack sex hormones. However, the statement that insects do not have sex hormones loses much of its credibility if one considers (1) the classical endocrinological work on sexual differentiation in the fireflyLampyrisand in the hevea tussock mothOrgyia;(2) the recent identification of an androgenic hormone and its role in sex determination in the isopodArmadillidium;(3) the similarity between steroidogenic factor 1 (SF-1) of mammals and fushi tarazu factor 1 (FTZ-F1) ofDrosophila;and (4) the steroidogenic effect of gonadotropins secreted by the brain of female locusts and mosquitoes and of male gypsy moth. In our model, based on data from the literature, ecdysone, when present in high concentrations, might function as an androgenic sex steroid. It is also the precursor of 20-OH-ecdysone, which is the moulting hormone of insects, and in vitellogenic females of many species, the counterpart of estrogens as well. Other gender-specific hormones are likely to exist in the brain–gonad axis.