, Volume 235, Issue 4, pp 1245–1255 | Cite as

Resistance exercise decreases heroin self-administration and alters gene expression in the nucleus accumbens of heroin-exposed rats

  • Mark A. Smith
  • Gaylen E. Fronk
  • Jean M. Abel
  • Ryan T. Lacy
  • Sarah E. Bills
  • Wendy J. Lynch
Original Investigation



Preclinical studies consistently report that aerobic exercise decreases drug self-administration and other forms of drug-seeking behavior; however, relatively few studies have examined other types of physical activity.


The purpose of the present study was to examine the effects of resistance exercise (i.e., strength training) on heroin self-administration and mRNA expression of genes known to mediate opioid reinforcement and addictive behavior in the nucleus accumbens (NAc) of heroin-exposed rats.


Female rats were obtained during late adolescence and divided into two groups. Resistance exercise rats were trained to climb a vertical ladder wearing a weighted vest; sedentary control rats were placed repeatedly on the ladder oriented horizontally on its side. All rats were implanted with intravenous catheters and trained to self-administer heroin on a fixed ratio (FR1) schedule of reinforcement. mRNA expression in the NAc core and shell was examined following behavioral testing.


Resistance exercise significantly decreased heroin self-administration, resulting in a downward shift in the dose-effect curve. Resistance exercise also reduced mRNA expression for mu opioid receptors and dopamine D1, D2, and D3 receptors in the NAc core. Resistance exercise increased mRNA expression of dopamine D5 receptors in the NAc shell and increased mRNA expression of brain-derived neurotrophic factor (exons I, IIB, IIC, IV, VI, IX) in the NAc core.


These data indicate that resistance exercise decreases the positive reinforcing effects of heroin and produces changes in opioid and dopamine systems in the NAc of heroin-exposed rats.


Heroin Resistance exercise Strength training Rats Dopamine Nucleus accumbens 



The authors thank the National Institute on Drug Abuse for supplying the study drug.

Author contributions

M.A. Smith developed the model and conceived the project. G.E. Fronk, S.E. Bills, and R.T. Lacy collected the behavioral data and assisted in data analysis and interpretation. J.M. Abel and W.J. Lynch collected the molecular data and assisted in data analysis and interpretation. M.A. Smith, G.E. Fronk, and W.J. Lynch drafted the manuscript. All authors approved the manuscript for submission.

Funding information

This study was funded by NIH Grants DA027485 (MAS), DA031725 (MAS), and DA039093 (WJL). The NIH had no role in the design of the study; in the collection, analysis, and interpretation of the data; in the writing of the manuscript; or in the decision to submit the manuscript for publication.

Compliance with ethical standards

All rats were maintained in accordance with the guidelines of the Animal Care and Use Committee of Davidson College.

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

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Online Resource 1 (PPTX 134 kb)
213_2018_4840_MOESM2_ESM.pptx (40 kb)
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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Mark A. Smith
    • 1
    • 2
  • Gaylen E. Fronk
    • 1
  • Jean M. Abel
    • 3
  • Ryan T. Lacy
    • 4
  • Sarah E. Bills
    • 1
  • Wendy J. Lynch
    • 3
  1. 1.Department of PsychologyDavidson CollegeDavidsonUSA
  2. 2.Program in NeuroscienceDavidson CollegeDavidsonUSA
  3. 3.Department of Psychiatry and Neurobehavioral SciencesUniversity of VirginiaCharlottesvilleUSA
  4. 4.Department of PsychologyFranklin and Marshall CollegeLancasterUSA

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