Comparative effects of a melatonin agonist on the circadian system in mice and Syrian hamsters

O. Van Reeth*, E. Olivares, Y. Zhang, P. C. Zee, E. Mocaer, R. Defrance, F. W. Turek

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


S-20098 has potent and specific agonist properties on melatonin receptors both in vitro and in vivo. Behavioral studies on rodents already showed that repeated intraperitoneal administration of S-20098 could dose- dependently alter the functioning of the circadian clock. To determine whether single administration of S-20098 could alter the circadian rhythms of rodents, we first used the phase-response curve (PRC) approach in two different species: Syrian hamsters and mice (C3H/HeJ). Our results show that the shape, circadian times and extent of the PRC to S-20098 look very similar in mice and hamsters. In both species, the phase advance portion of the PRC to S-20098 is limited to a 3 h window preceding the onset of locomotor activity, but the magnitude of phase shifts is larger in mice. We also tested the phase shifting effects of increasing doses of S-20098 during the interval of maximal sensitivity to this compound. Treatment with S-20098 induces dose- dependent phase shifts, with maximal shifts observed after injections of 20 and 25 mg/kg S-20098 i.p., respectively, in mice and hamsters. Those results are in agreement with the limited distribution of melatonin-binding sites within the circadian clock of adult Syrian hamsters, as compared to other rodents.

Original languageEnglish (US)
Pages (from-to)185-194
Number of pages10
JournalBrain research
Issue number1-2
StatePublished - Jul 11 1997


  • Agonist
  • Circadian
  • Clock
  • Melatonin
  • Mice
  • Rhythm
  • Syrian hamster

ASJC Scopus subject areas

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


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