Oxycodone self-administration in male and female rats

Maria Mavrikaki, Marco Pravetoni, Sarah Page, David Potter, Elena Chartoff

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

Rationale: Oxycodone is one of the most widely prescribed painkillers in the USA. However, its use is complicated by high abuse potential. As sex differences have been described in drug addiction, the present study tested for sex differences in intravenous oxycodone self-administration in rats. Methods: Male and female Sprague-Dawley rats were implanted with jugular vein catheters and trained to self-administer oxycodone (0.03 mg/kg/infusion) under fixed ratio 1 (FR1), FR2, and FR5 schedules of reinforcement followed by a dose-response study to assess sensitivity to the reinforcing effects of oxycodone. In separate rats, sucrose pellet self-administration was assessed under an FR1 schedule to determine whether sex differences in oxycodone self-administration could be generalized across reinforcers. In separate rats, oxycodone distribution to plasma and brain was measured after intravenous drug delivery. Results: In the first 3 trials under an FR1 schedule of reinforcement, male rats self-administered more oxycodone than females. In contrast, females self-administered more sucrose pellets. Under FR2 and FR5 schedules, no significant sex differences in oxycodone intake were observed, although female rats had significantly more inactive lever presses. Male and female rats showed similar inverted U-shaped dose-effect functions, with females tending to self-administer more oxycodone than males at higher doses. No significant sex differences were observed in plasma or brain oxycodone levels, suggesting that sex differences in oxycodone self-administration behavior were not due to pharmacokinetics. Conclusion: Our results suggest subtle sex differences in oxycodone self-administration, which may influence the abuse liability of oxycodone and have ramifications for prescription opioid addiction treatment.

Original languageEnglish (US)
Pages (from-to)977-987
Number of pages11
JournalPsychopharmacology
Volume234
Issue number6
DOIs
StatePublished - Mar 1 2017

Bibliographical note

Funding Information:
This study was supported by the Brooking Fellowship (MM). We thank Dr. Linda Valerie for the critical assistance with the statistical analysis of the results of this study. We also thank Dr. Maria Carreira for training MM in the jugular vein catheterization and relevant self-administration procedures, Dr. In-Jee You for the recommendations for setting up the drug self-administration paradigm, and Dr. Barak Caine and Dr. Morgane Thomsen for commenting on our data.

Publisher Copyright:
© 2017, Springer-Verlag Berlin Heidelberg.

Keywords

  • Motivation
  • Oxycodone
  • Self-administration
  • Sex differences
  • Sucrose reward

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