Ecdysteroid control of ionic current development in Manduca sexta motoneurons

Bernd Grünewald, Richard B. Levine

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

The steroid hormone 20-hydroxyecdysone (20-HE) regulates several processes during insect metamorphosis. We studied the effects of 20-HE on the development of voltage-sensitive ionic currents of thoracic leg motoneurons of Manduca sexta. The larval leg motoneurons persist throughout metamorphosis but undergo substantial morphological reorganization, which is under the control of 20-HE and accompanied by changes in Ca2+ and K+ current densities. To determine whether 20-HE controls the changes in Ca2+ and K+ current levels during postembryonic development, identified thoracic leg motoneurons isolated from late larval and early pupal stages were taken into primary cell culture. Whole-cell Ca2+ and K+ currents were measured after 1-4 days of steroid hormone incubation. In the presence of 20-HE, peak Ca2+ currents of pupal leg motoneurons increased from day I to day 4 in vitro. Thus, at culture day 4 the pupal Ca2+ current levels were larger in 20-HE- treated than in untreated cells. By contrast, 20-HE did not affect the Ca2+ current amplitudes of larval leg motoneurons. Whole-cell K+ currents, measured at 4 days in pupal motoneurons, consisted of a fast-activating transient current and a sustained, slowly inactivating current. 20-HE did not affect the amplitude of the transient or sustained currents after 4 days in vitro. Thus, a direct steroid hormone effect may control the proper maturation of voltage-sensitive Ca2+ currents in leg motoneurons.

Original languageEnglish (US)
Pages (from-to)211-223
Number of pages13
JournalJournal of Neurobiology
Volume37
Issue number2
DOIs
StatePublished - Nov 5 1998

Keywords

  • Calcium currents
  • Insect
  • Patch clamp
  • Potassium currents
  • Steroid hormone

ASJC Scopus subject areas

  • Neuroscience(all)
  • Cellular and Molecular Neuroscience

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