Carbachol phase shifts the circadian rhythm of locomotor activity in the Djungarian hamster

Beth E.F. Wee*, Fred W. Turek

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The effects of light on the circadian system may involve the neurotransmitter acetylcholine (ACh). The purpose of the present study was to determine whether carbacol, a cholinergic agonist, mimics the phase-shifting effects of light on the circadian rhythm of locomotor activity (CRLA) in the Djungarian hamster. Phase response curves (PRCs) were measured for blind animals injected intracerebroventricularly with either vehicle or carbochol at different circadian times. Carbachol produced significant phase delays in the CRLA when administered at circadian time (CT) 12-16 and small, but significant phase advances when given at CT 8. No consistent phase shifts were observed in response to carbachol injections at other circadian times. Phase shifts produced by carbachol injections at CT 8 and 12 were similar for both sighted and blind animals. Light pulses to sighted hamsters produced phase advances at CT 20 and phase delays at CT 12. Both the carbachol PRC and the PRC for light pulses in the Djungarian hamster have phase delay regions in the early subjective night. However, these two PRCc have different phase advance regions. These results indicate that carbachol mimics some of the effects of light on the circadian system in the Djungarian hamster and support the hypothesis that cholinergic mechanisms may play a role in mediating some of the phase-shifting effects of light on the circadian clock of mammals.

Original languageEnglish (US)
Pages (from-to)209-214
Number of pages6
JournalBrain research
Volume505
Issue number2
DOIs
StatePublished - Dec 29 1989

Keywords

  • Blind
  • Carbachol
  • Circadian rhythm
  • Djungarian hamster
  • Locomotor activity
  • Phase response curve

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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