Effects of the ecdysoneless mutant on synaptic efficacy and structure at the neuromuscular junction in Drosophila larvae during normal and prolonged development

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22 Scopus citations

Abstract

Hormonal regulation in development and maintenance of synaptic transmission involves examination of both the presynaptic and postsynaptic components and a system in which the hormones can be controlled. We used the ecdysoneless heat-sensitive mutation (l(3)ecd1/l(3)ecd1) of Drosophila to provide the ability to regulate endogenous ecdysone production at various larval stages. In conjunction, we used the neuromuscular junctions of Drosophila since they offer the advantage of assessable preparations for both morphological and physiological measures. The growth in the Ib and Is motor nerve terminals and the corresponding muscle 6 in segment 4 of the larval Drosophila throughout the third instar stage in the presence of normal and a much reduced endogenous ecdysone level was investigated. Muscle 6 and the motor nerve terminals parallel in growth throughout the third instar. The nerve terminals increase in length and varicosity number, thus providing an increase in the number of synaptic release sites. The ecdysoneless larvae also show an increase in muscle size, however the Is and Ib motor nerve terminals do not mature to the extent of the wild-type ecdysone producing flies. The motor nerve terminal length is shorter with fewer numbers of varicosities per terminal. In spite of a shorter nerve terminal and fewer varicosities, with an increasing muscle fiber, the compound excitatory junctional potentials of Ib and Is in the ecdysoneless flies are larger, which is suggestive of synaptic structural modification. This study demonstrates ecdysone's role in modifying nerve terminal development and neuromuscular junction function.

Original languageEnglish
Pages (from-to)193-200
Number of pages8
JournalNeuroscience
Volume106
Issue number1
DOIs
StatePublished - Sep 3 2001

Bibliographical note

Funding Information:
Funding was provided by NSF Grants IBN-9808631 (R.L.C.) and NSF-ILI-DUE 9850907 (R.L.C.). We thank Dr. Vincent C. Henrich, University of North Carolina at Charlotte for supplying the ecd 1 flies. We also thank Drs. Doug Harrison and Grace Jones and their laboratory members (University of Kentucky) for helping to maintain the stocks and trouble shooting with maintenance of flies.

Keywords

  • Ecdysone
  • Hormone
  • Insect
  • Neuromuscular junction
  • Neurotransmission
  • Synapse

ASJC Scopus subject areas

  • General Neuroscience

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