Kappa opioid agonists alter dopamine markers and cocaine-stimulated locomotor activity

S. L. Collins, R. M. Gerdes, C. D. Addario, Sari Izenwasser

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


To better understand the influence of κ-opioid agonists on the effects of cocaine, rats were treated with daily injections of the selective κ-opioid agonist U-69593 or bremazocine. In combination with 10mg/kg cocaine, both compounds, at a dose of 0.32 mg/kg, greatly diminished locomotor activity, and these effects were maintained over a period of 5 days. In addition, the response to a challenge injection of 10mg/kg cocaine several days after the end of κ-opioid agonist treatment with or without cocaine was markedly reduced. When naltrexone was given in combination with U-69593, it blocked the reduction in cocaine-induced locomotor activity after U-69593 treatment alone. However, a single injection of either κ-opioid agonist alone had no effect on cocaine-induced locomotion several days later (i.e. no long-term effects), suggesting that multiple injections of the κ-opioid agonist are needed to reduce the locomotor activating effects of cocaine other than acutely. In addition, treatment with the κ-opioid agonist U-69593 (0.32 mg/kg) over a 5-day period decreased dopamine transporter densities in the caudate putamen, and this was also blocked by co-administration of naltrexone.

Original languageEnglish (US)
Pages (from-to)237-245
Number of pages9
JournalBehavioural Pharmacology
Issue number4
StatePublished - 2001


  • κ-opioid
  • Cocaine
  • Dopamine transporter
  • Locomotor activity
  • Rat
  • Sensitization

ASJC Scopus subject areas

  • Pharmacology
  • Neuroscience(all)


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