Serotonin sets the day state in the neurons that control coupling between the optic lobe circadian pacemakers in the cricket Gryllus bimaculatus

A. S.M. Saifullah, Kenji Tomioka

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The bilaterally paired optic lobe circadian pacemakers of the cricket Gryllus bimaculatus mutually exchange photic and circadian information to keep their activity synchronized. The information is mediated by a neural pathway, consisting of the so-called medulla bilateral neurons, connecting the medulla areas of the two optic lobes. We investigated the effects of serotonin on the neural activity in this coupling pathway. Spontaneous and light-induced electrical activity of the neurons in the coupling pathway showed daily variations, being more intense during the night than the day. Microinjection of serotonin or a serotonin-receptor agonist, quipazine, into the optic lobe caused a dose- and time-dependent inhibition of spontaneous and light-induced responses, mimicking the day state. The amount of suppression was greater and the recovery from the suppression occurred faster during the night. Application of metergoline, a non-selective serotonin-receptor antagonist, increased spontaneous activity and light-evoked responses during both the day and the night, with higher effect during the day. In addition, metergoline effectively attenuated the effects of serotonin. These facts suggest that in the cricket's optic lobe, serotonin is released during the daytime and sets the day state in the neurons regulating coupling between the bilaterally paired optic lobe circadian pacemakers.

Original languageEnglish
Pages (from-to)1305-1314
Number of pages10
JournalJournal of Experimental Biology
Volume205
Issue number9
Publication statusPublished - Jan 1 2002
Externally publishedYes

Keywords

  • Circadian rhythm
  • Cricket
  • Gryllus bimaculatus
  • Medulla bilateral neuron
  • Pacemaker coupling
  • Photo-responsiveness
  • Serotonin

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science

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