The effects of 5-HT on sensory, central and motor neurons driving the abdominal superficial flexor muscles in the crayfish

J. R. Strawn, W. S. Neckameyer, R. L. Cooper

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Serotonin (5-HT) induces a variety of physiological and behavioral effects in crustaceans. However, the mechanisms employed by 5-HT to effect behavorial changes are not fully understood. Among the mechanisms by which these changes might occur are alterations in synaptic drive and efficacy of sensory, interneurons and motor neurons, as well as direct effects on muscles. We investigated these aspects with the use of a defined sensory-motor system, which is entirely contained within a single abdominal segment and consists of a 'cuticular sensory neurons-segmental ganglia-abdominal superficial flexor motor neurons-muscles' circuit. Our studies address the role of 5-HT in altering (1) the activity of motor neurons induced by sensory stimulation; (2) the inherent excitability of superficial flexor motor neurons; (3) transmitter release properties of the motor nerve terminal and (4) input resistance of the muscle. Using en passant recordings from the motor nerve, with and without sensory stimulation, and intracellular recordings from the muscle, we show that 5-HT enhances sensory drive and output from the ventral nerve cord resulting in an increase in the firing frequency of the motor neurons. Also, 5-HT increases transmitter release at the neuromuscular junction, and alters input resistance of the muscle fibers. (C) 2000 Elsevier Science Inc.

Original languageEnglish
Pages (from-to)533-550
Number of pages18
JournalComparative Biochemistry and Physiology - B Biochemistry and Molecular Biology
Issue number4
StatePublished - 2000

Bibliographical note

Funding Information:
Funding was provided by NSF grants IBN-9808631 (RLC), NSF-ILI-DUE 9850907 (RLC) and NSF-IBN 9423616 (WSN) as well as an undergraduate training fellowship from HHMI and an NSF-REU to (JRS). Appreciation is given to Mr Joseph Shearer for editorial comments.

Copyright 2020 Elsevier B.V., All rights reserved.


  • Crayfish
  • Neuromuscular junction
  • Neurotransmission
  • Quantal
  • Serotonin
  • Synapse

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Molecular Biology


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