Opiate self-administration as a measure of chronic nociceptive pain in arthritic rats

F. C. Colpaert, J. P. Tarayre, M. Alliaga, L. A. Bruins Slot, N. Attal, W. Koek

Research output: Contribution to journalArticlepeer-review

102 Scopus citations


The study examined the validity of oral fentanyl self-administration (FSA) as a measure of the chronic nociceptive pain that develops in rats with adjuvant arthritis independently of acute noxious challenges. Arthritic rats self-administered more of a 0.008 mg/ml fentanyl solution (up to 3.4 g/rat per day) than non-arthritic controls (0.5 g/rat per day) and did so with a biphasic time course that reached peak during weeks 3 and 4 after inoculation with Mycobacterium butyricum. The time course paralleled both the disease process and the chronic pain. Continuous infusion of dexamethasone during weeks 3 and 4 via subcutaneous osmotic pumps at 0.0025-0.04 mg/rat per day disrupted the arthritic disease and decreased FSA to a level (i.e. by 65%) similar to that observed in non-arthritic rats. Continuous naloxone (2.5 mg/rat per day) decreased FSA (by 55%) in arthritic but not in non-arthritic animals. Continuous, subcutaneous infusion of fentanyl also decreased arthritic FSA in a manner that varied with dose at 0.04-0.16 mg/rat per day doses, but leveled off at 47% of controls with 0.31 mg/rat per day. The effects of continuous fentanyl on arthritic FSA occurred only with those doses and dose-dependent dynamics with which fentanyl also induced dependence in non-arthritic rats. The findings indicate that pain, rather than the rewarding or dependence-inducing action of fentanyl mediates FSA in arthritic rats. Paralleling patient-controlled analgesic drug intake, FSA offers a specific measure allowing the dynamic effects of neurobiological agents to be studied in this unique animal model of persistent nociceptive pain.

Original languageEnglish (US)
Pages (from-to)33-45
Number of pages13
Issue number1-2
StatePublished - 2001
Externally publishedYes


  • Adjuvant arthritis
  • Animal model
  • Chronic pain
  • Opiate self-administration
  • Pain measurement

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Anesthesiology and Pain Medicine


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