Differential Patterns of Synaptic Plasticity in the Nucleus Accumbens Caused by Continuous and Interrupted Morphine Exposure

Emilia M. Lefevre, Elysia A. Gauthier, Lauren L. Bystrom, Jordan Scheunemann, Patrick E. Rothwell

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Opioid exposure and withdrawal both cause adaptations in brain circuits that may contribute to abuse liability. These adaptations vary in magnitude and direction following different patterns of opioid exposure, but few studies have systematically manipulated the pattern of opioid administration while measuring neurobiological impact. In this study, we compared cellular and synaptic adaptations in the nucleus accumbens shell caused by morphine exposure that was either continuous or interrupted by daily bouts of naloxone-precipitated withdrawal. At the behavioral level, continuous morphine administration caused psychomotor tolerance, which was reversed when the continuity of morphine action was interrupted by naloxone-precipitated withdrawal. Using ex vivo slice electrophysiology in female and male mice, we investigated how these patterns of morphine administration altered intrinsic excitability and synaptic plasticity of medium spiny neurons (MSNs) expressing the D1 or D2 dopamine receptor. We found that morphine-evoked adaptations at excitatory synapses were predominately conserved between patterns of administration, but there were divergent effects on inhibitory synapses and the subsequent balance between excitatory and inhibitory synaptic input. Overall, our data suggest that continuous morphine administration produces adaptations that dampen the output of D1-MSNs, which are canonically thought to promote reward-related behaviors. Interruption of otherwise continuous morphine exposure does not dampen D1-MSN functional output to the same extent, which may enhance behavioral responses to subsequent opioid exposure. Our findings support the hypothesis that maintaining continuity of opioid administration could be an effective therapeutic strategy to minimize the vulnerability to opioid use disorders.

Original languageEnglish (US)
Pages (from-to)308-318
Number of pages11
JournalJournal of Neuroscience
Volume43
Issue number2
DOIs
StatePublished - Jan 11 2023

Bibliographical note

Funding Information:
Received Mar. 11, 2022; revised Oct. 14, 2022; accepted Nov. 12, 2022. Author contributions: E.M.L. and P.E.R. designed research; E.M.L., E.A.G., L.L.B., and J.S. performed research; E.M.L. analyzed data; E.M.L. and P.E.R. wrote the paper. This work was supported by the University of Minnesota Discovery, Research, and InnoVation Economy initiative and by National Institutes of Health Grants K99 DA052624 (E.M.L.), R00 DA037279 (P.E.R.), and R01 DA048946 (P.E.R.). We thank David Leipold and Kerry Trotter for technical assistance. The authors declare no competing financial interests. Correspondence should be addressed to Patrick E. Rothwell at rothwell@umn.edu. https://doi.org/10.1523/JNEUROSCI.0595-22.2022 Copyright © 2023 the authors

Publisher Copyright:
© 2023 the authors.

Keywords

  • addiction
  • morphine
  • nucleus accumbens
  • opioid withdrawal
  • synaptic plasticity

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

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