title: Post-feeding physiology in Rhodnius prolixus: the possible role of FGLamide-related allatostatins.
abstract: Allatostatins (ASTs) are neuropeptides that were first identified as inhibitors of juvenile hormone biosynthesis by the corpora allata of some insect species. The FGLamide-related ASTs (FGLa/ASTs) belong to one of three families of insect ASTs. Previously, we showed that Rhodnius prolixus FGLa/ASTs (Rhopr-FGLa/ASTs) are present throughout the R. prolixus central nervous system and are associated with 5 dorsal unpaired median (DUM) neurons in the mesothoracic ganglionic mass. A similar set of neurons contain serotonin which is a diuretic hormone in R. prolixus. Rhopr-FGLa/ASTs inhibit both spontaneous contractions of the anterior midgut and leucokinin-1-induced hindgut contractions. Since these tissues are involved with post-feeding diuresis, these data suggest a possible role for FGLa/ASTs in events associated with feeding, and a possible interaction with serotonin. To investigate this possibility, we have examined the DUM neurons in more detail with regard to their peptide content, examined the potential release of Rhopr-FGLa/ASTs into the haemolymph following feeding, and further investigated the effects of Rhopr-FGLa/ASTs on feeding-related tissues. There are 10 DUM neurons in the abdominal neuromeres, 5 of which express serotonin-like immunoreactivity and the other 5 express FGLa/AST-like immunoreactivity. FGLa/AST-like immunoreactivity is reduced in the 5 DUM neuron cell bodies and their neurohaemal sites on abdominal nerves at 3-5 h post feeding. Rhopr-FGLa/ASTs do not inhibit serotonin-stimulated anterior midgut absorption or Malpighian tubule secretion but do inhibit hindgut contractions induced by an endogenous kinin, suggesting that they may only indirectly affect post-feeding diuresis in R. prolixus.
authors.affiliation: Department of Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada. Electronic address: meet.zandawala@utoronto.ca.
authors.forename: Meet
authors.initials: M
authors.lastname: Zandawala
authors.forename: Ian
authors.initials: I
authors.lastname: Orchard
mesh_terms: D000200:Action Potentials / Q000235:genetics / Q000502:physiology; D000818:Animals; D004231:Diuresis / Q000235:genetics / Q000502:physiology; D007705:Kinins / Q000378:metabolism; D008317:Malpighian Tubules / Q000378:metabolism; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D012239:Rhodnius / Q000378:metabolism*; D012701:Serotonin / Q000235:genetics / Q000378:metabolism
chemical_list: D007705:Kinins; D009479:Neuropeptides; C076523:allatostatin; D012701:Serotonin
keywords: ANOVA; ASTs; ATP; BSA; CA; CC; CNS; CRF/DH; CT/DH; DUM; FGLa/ASTs; FGLamide-related allatostatins; FISH; Immunoreactivity; Insect; JH; MT; MTGM; Malpighian tubule; Myoinhibition; NGS; Neuropeptide; Overshooting action potentials; PBS; adenosine triphosphate; allatostatins; analysis of variance; bovine serum albumin; calcitonin-like diuretic hormone; central nervous system; corpus allatum; corpus cardiacum; corticotropin releasing-factor-related diuretic hormone; dorsal unpaired median; fluorescent in situ hybridization; juvenile hormone; mesothoracic ganglionic mass; normal goat serum; phosphate-buffered saline