Fentanyl, but not haloperidol, entrains persisting circadian activity episodes when administered at 24- and 31-h intervals

Andrea G. Gillman, Joseph K. Leffel, Ann E.K. Kosobud, William Timberlake

Research output: Contribution to journalArticle

12 Scopus citations


Administration of several drugs of abuse on a 24-h schedule has been shown to entrain both pre-drug (anticipatory) and post-drug (evoked) circadian activity episodes that persist for several days when the drug is withheld. The present study tested the entrainment effects of fentanyl, an opioid agonist with a noted abuse liability, and haloperidol, an anti-psychotic dopamine antagonist without apparent abuse liability. Adult female Sprague-Dawley rats housed under constant light in cages with attached running wheels received repeated low, medium, or high doses of either fentanyl or haloperidol on a 24-h administration schedule followed by a 31-h schedule (Experiment 1) or solely on a 31-h schedule (Experiment 2). The results showed that all three doses of fentanyl entrained both pre-drug and post-drug episodes of wheel running when administered every 24 h, and the combined pre- and post-fentanyl activity episodes persisted for at least 3 days when the drug was withheld during test days. On the 31-h schedule, fentanyl produced an "ensuing" activity episode approximately 24 h post-administration, but failed to produce an anticipatory episode 29-31 h post-administration. In contrast, haloperidol injections failed to produce both pre-drug episodes on the 24-h schedule and circadian ensuing episodes on the 31-h schedule, and post-haloperidol suppression of activity appeared to mask the free-running activity rhythm. Taken together, these results provide additional evidence that drugs of abuse share a common ability to entrain circadian activity episodes.

Original languageEnglish (US)
Pages (from-to)102-114
Number of pages13
JournalBehavioural Brain Research
Issue number1
StatePublished - Dec 14 2009


  • Circadian rhythms
  • Drug abuse
  • Drug addiction
  • Drug anticipation
  • Ensuing activity
  • Fentanyl
  • Haloperidol
  • Locomotor entrainment
  • Wheel running

ASJC Scopus subject areas

  • Behavioral Neuroscience

Fingerprint Dive into the research topics of 'Fentanyl, but not haloperidol, entrains persisting circadian activity episodes when administered at 24- and 31-h intervals'. Together they form a unique fingerprint.

  • Cite this