Environmental enrichment decreases intravenous self-administration of amphetamine in female and male rats

M. T. Bardo, J. E. Klebaur, J. M. Valone, C. Deaton

Research output: Contribution to journalArticlepeer-review

238 Scopus citations

Abstract

Rationale: Previous work has shown that environmental enrichment alters amphetamine-induced locomotor activity and conditioned place preference. Objective: The present study examined the effect of environmental enrichment on amphetamine self-administration. Methods: Female and male rats were raised from 21 days of age in one of three different conditions: an enriched condition (EC) containing novel objects and social partners, a social condition (SC) containing social partners only, or an isolated conditioned (IC) without objects or social partners. Beginning at 51 days of age, rats were then tested for operant responding for a sucrose reinforcer using an incremental fixed ratio (FR) requirement across four sessions. Rats were then implanted with a chronic indwelling intravenous catheter and were allowed to self-administer amphetamine (0.03 or 0.1 mg/kg per infusion) for five FR1 sessions, followed by a progressive ratio (PR) session. Results: EC rats initially showed an increase in sucrose-reinforced responding relative to IC rats and this environment-induced difference was greater in females than in males. However, in both sexes, the environment-induced difference in sucrose-reinforced responding dissipated completely across repeated sessions. With amphetamine self-administration, both EC and SC rats earned fewer infusions than IC rats across repeated FR1 sessions using the low dose of amphetamine (0.03 mg/kg per infusion), but not using the higher dose of amphetamine (0.1 mg/kg per infusion). EC rats also earned fewer self-infusions of the low amphetamine dose on the PR session relative to IC rats. The effects of environmental enrichment on amphetamine self-administration were similar in both females and males. Conclusion: These results suggest that environmental enrichment may serve as a protective factor for reducing amphetamine self-administration.

Original languageEnglish
Pages (from-to)278-284
Number of pages7
JournalPsychopharmacology
Volume155
Issue number3
DOIs
StatePublished - 2001

Bibliographical note

Funding Information:
Acknowledgements We acknowledge the expert assistance of M. Bradley, N. Brown, and T. Segar with the surgical and behavioral procedures. Supported by USPHS grants DA05312 and DA12964.

Keywords

  • Amphetamine
  • Drug reward
  • Environmental enrichment
  • Isolation rearing
  • Self-administration
  • Sex difference
  • Social environment

ASJC Scopus subject areas

  • Pharmacology

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