title: Fentanyl, but not haloperidol, entrains persisting circadian activity episodes when administered at 24- and 31-h intervals.
abstract: 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 24h, 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 24h post-administration, but failed to produce an anticipatory episode 29-31h 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.
authors: Department of Psychological and Brain Sciences, Indiana University, Bloomington, United States. aggillma@indiana.edu
authors: Andrea G
authors: AG
authors: Gillman
authors: Joseph K
authors: JK
authors: Leffel
authors: Ann E K
authors: AE
authors: Kosobud
authors: William
authors: W
authors: Timberlake
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects*; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage / Q000494:pharmacology*; D006220:Haloperidol / Q000008:administration & dosage / Q000494:pharmacology*; D008027:Light; D008124:Locomotion / Q000187:drug effects*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D018492:Dopamine Antagonists; D006220:Haloperidol; D005283:Fentanyl