title: CRF-like diuretic hormone negatively affects both feeding and reproduction in the desert locust, Schistocerca gregaria.
abstract: Diuretic hormones (DH) related to the vertebrate Corticotropin Releasing Factor (CRF) have been identified in diverse insect species. In the migratory locust, Locusta migratoria, the CRF-like DH (CRF/DH) is localized in the same neurosecretory cells as the Ovary Maturating Parsin (OMP), a neurohormone that stimulates oocyte growth, vitellogenesis and hemolymph ecdysteroid levels in adult female locusts. In this study, we investigated whether CRF-like DH can influence feeding and reproduction in the desert locust, Schistocerca gregaria. We identified two highly similar S. gregaria CRF-like DH precursor cDNAs, each of which also encodes an OMP isoform. Alignment with other insect CRF-like DH precursors shows relatively high conservation of the CRF/DH sequence while the precursor region corresponding to OMP is not well conserved. Quantitative real-time RT-PCR revealed that the precursor transcripts mainly occur in the central nervous system and their highest expression level was observed in the brain. Injection of locust CRF/DH caused a significantly reduced food intake, while RNAi knockdown stimulated food intake. Therefore, our data indicate that CRF-like DH induces satiety. Furthermore, injection of CRF/DH in adult females retarded oocyte growth and caused lower ecdysteroid titers in hemolymph and ovaries, while RNAi knockdown resulted in opposite effects. The observed effects of CRF/DH may be part of a wider repertoire of neurohormonal activities, constituting an integrating control system that affects food intake and excretion, as well as anabolic processes like oocyte growth and ecdysteroidogenesis, following a meal. Our discussion about the functional relationship between CRF/DH and OMP led to the hypothesis that OMP may possibly act as a monitoring peptide that can elicit negative feedback effects.
authors.affiliation: Molecular Developmental Physiology and Signal Transduction, Division of Animal Physiology and Neurobiology, Zoological Institute, K.U. Leuven, Leuven, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Van Wielendaele
authors.forename: Senne
authors.initials: S
authors.lastname: Dillen
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Marchal
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Badisco
authors.forename: Jozef
authors.initials: J
authors.lastname: Vanden Broeck
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence / Q000235:genetics; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D018076:DNA, Complementary / Q000235:genetics; D003889:Desert Climate; D004232:Diuretics / Q000008:administration & dosage / Q000494:pharmacology*; D005247:Feeding Behavior / Q000187:drug effects*; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006110:Grasshoppers / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D007267:Injections; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D009865:Oocytes / Q000187:drug effects; D034622:RNA Interference / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects
chemical_list: D018076:DNA, Complementary; D004232:Diuretics; D019476:Insect Proteins; D012333:RNA, Messenger; D003346:Corticotropin-Releasing Hormone