Heart rate within male crayfish: Social interactions and effects of 5-HT

Laura R. Listerman, Jasson Deskins, Haymo Bradacs, Robin L. Cooper

Research output: Contribution to journalArticlepeer-review

79 Scopus citations


Behaviors, such as those that establish dominant and subordinate social status, are thought to be driven by various neuromodulators and hormones. In crustaceans, the level of serotonin (5-HT) in the hemolymph is correlated with degree of aggressiveness. The crustacean heart is neurogenic and is modulated by neural secretion of 5-HT in the hemolymph, which bathes the cardiac tissue. We discuss and present the results of measuring heart rate (HR) of crayfish during interactions, as an indication of their state of excitability. HR is the result of multiple influences: a cocktail of hormones and modulators. HR was monitored during the periods in which crayfish established aggressive and submissive social status, during sham injections, and following injections of various doses of 5-HT. Crayfish, during an interaction to establish social status, can increase HR. Both the aggressive and submissive crayfish can dampen their HR within seconds during a pause in the interaction, while still posturing in an aggressive or submissive state. Injections of 5-HT to obtain systemic levels of approximately 100 nM-10 μM increase HR substantially for hours. This suggests that aggressive interactions and the establishment of a dominant posture may not be related to large increases in the free concentrations of 5-HT within the circulating hemolymph, since a sustained HR is not observed in aggressive animals. Instead, the results may demonstrate that inhibitory cardiac regulation is present in the aggressors during interactions and that a regulator is possibly 5-HT. Copyright (C) 2000 Elsevier Science Inc.

Original languageEnglish
Pages (from-to)251-263
Number of pages13
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Issue number2
StatePublished - Feb 2000

Bibliographical note

Funding Information:
We are grateful for the fruitful conversations with Dr J.L. Wilkens (University of Calgary, Canada) and Dr J. Mercier (Brock University, Ont., Canada). Appreciation is given to Dr Hilary Lambert Hopper for editorial assistance. Illustrations were provided by the courtesy of Hye Won Cooper. Appreciation is given to Dr Philip Bonner at the University of Kentucky for the use of microscopy equipment. Funding was provided by a Howard Hughes Medical Institute undergraduate training fellowship (L.R. Listerman), NSF-REU (L.R. Listerman), and NSF grants IBN-9808631 and ILI DUE-9850907 (R.L. Cooper).


  • Crayfish
  • Crustacean
  • Heart rate
  • Hemolymph
  • Hormones
  • Interactions
  • Neuromodulators
  • Serotonin
  • Social status

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology


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