Abstract
Background
Opioid abuse is a major problem around the world. Identifying environmental factors that contribute to opioid abuse and addiction is necessary for decreasing this epidemic. In rodents, environmental enrichment protects against the development of low dose stimulant self-administration, but studies examining the effect of enrichment and isolation (compared to standard housing) on the development of intravenous opioid self-administration have not been conducted. The present study investigated the role of environmental enrichment on self-administration of the short-acting μ-opioid remifentanil.
Methods
Rats were raised in an enriched condition (Enr), standard condition (Std), or isolated condition (Iso) beginning at 21 days of age and were trained to lever press for 1 or 3 μg/kg/infusion remifentanil in young adulthood. Acquisition of self-administration and responding during increasing fixed ratio requirements were assessed, and a dose-response curve was generated.
Results
In all phases, Enr rats lever pressed significantly less than Std and Iso rats, with Enr rats pressing between 9 and 40% the amount of Iso rats. Enr rats did not acquire remifentanil self-administration when trained with 1 μg/kg/infusion, did not increase responding over increasing FR when trained at either dose, and their dose-response curves were flattened compared to Std and Iso rats. When expressed as economic demand curves, Enr rats displayed a decrease in both essential value (higher α) and reinforcer intensity (Q0) compared to Std and Iso rats at the 1 μg/kg/infusion training dose.
Conclusion
Environmental enrichment reduced remifentanil intake, suggesting that social and environmental novelty may protect against opioid abuse.
Document Type
Article
Publication Date
12-2017
Digital Object Identifier (DOI)
https://doi.org/10.1007/s00213-017-4734-2
Funding Information
This work was funded by NIH: DA012964, DA016176, DA035200, DA036291, and DA033373.
Repository Citation
Hofford, Rebecca S.; Chow, Jonathan J.; Beckmann, Joshua S.; and Bardo, Michael T., "Effects of Environmental Enrichment on Self-Administration of the Short-Acting Opioid Remifentanil in Male Rats" (2017). Psychology Faculty Publications. 187.
https://uknowledge.uky.edu/psychology_facpub/187
Notes/Citation Information
Published in Psychopharmacology, v. 234, issue 23-24, p. 3499-3506.
© Springer-Verlag GmbH Germany 2017
The copyright holder has granted the permission for posting the article here.
This is a post-peer-review, pre-copyedit version of an article published in Psychopharmacology. The final authenticated version is available online at: https://doi.org/10.1007/s00213-017-4734-2.