Molecular characterization, tissue distribution, and ultrastructural localization of adipokinetic hormones in the CNS of the firebug Pyrrhocoris apterus (Heteroptera, Insecta)

Gen Comp Endocrinol. 2015 Jan 1:210:1-11. doi: 10.1016/j.ygcen.2014.10.014. Epub 2014 Oct 31.

Abstract

Adipokinetic hormones (AKHs) are a group of insect metabolic neurohormones, synthesized and released from an endocrine retrocerebral gland, the corpus cardiacum (CC). Small amounts of AKH have also been identified in the brain, although their role in this organ is not clear. To address this gap in the knowledge about insect brain biology, we studied the nucleotide sequence, tissue distribution, and subcellular localization of AKHs in the brain and CC of the firebug Pyrrhocoris apterus. This insect expresses two AKHs; the octapeptides Pyrap-AKH and Peram-CAH-II, the presence of which was documented in the both studied organs. In situ hybridization and quantitative reverse-transcription (q-RT)-PCR revealed the expression of the genes encoding for both AKHs not only in the CC, but also in brain. Electron microscopy analysis of the brain revealed the presence of these hormones in specialized secretory granules localized predominantly in the cellular bodies of neurons. The hormones might be transported from the granules into the axons, where they could play a role in neuronal signaling. Under acute stress induced by the injection of 3μmol KCl, the level of AKHs in the brain increased to a greater extent than that in the CC. These results might indicate an enhanced role of brain-derived AKHs in defence reaction under acute stress situations.

Keywords: AKH; Electron microscopy; Immunoreaction; Insect brain; Pre-pro-hormone; Secretory granule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Central Nervous System / metabolism*
  • Central Nervous System / ultrastructure*
  • Cloning, Molecular
  • Gene Expression
  • Heteroptera* / genetics
  • Heteroptera* / metabolism
  • Heteroptera* / ultrastructure
  • Insect Hormones / genetics*
  • Insect Hormones / metabolism*
  • Molecular Sequence Data
  • Oligopeptides / genetics*
  • Oligopeptides / metabolism*
  • Pyrrolidonecarboxylic Acid / analogs & derivatives*
  • Pyrrolidonecarboxylic Acid / metabolism
  • Sequence Homology, Amino Acid
  • Stress, Physiological / genetics
  • Tissue Distribution

Substances

  • Insect Hormones
  • Oligopeptides
  • adipokinetic hormone
  • Pyrrolidonecarboxylic Acid