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BMC Genomics. 2016 Apr 29;17:313. doi: 10.1186/s12864-016-2634-1.

The multiple PDZ domain protein Mpdz/MUPP1 regulates opioid tolerance and opioid-induced hyperalgesia.

Author information

1
Department of Computer Science, Stanford University, Stanford, CA, USA.
2
Anesthesiology Service, Veterans Affairs Palo Alto Health Care System, 3801 Miranda Ave., Anesthesiology, 112A, Palo Alto, CA, 94304, USA.
3
Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA.
4
Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, USA.
5
Anesthesiology Service, Veterans Affairs Palo Alto Health Care System, 3801 Miranda Ave., Anesthesiology, 112A, Palo Alto, CA, 94304, USA. djclark@stanford.edu.
6
Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA. djclark@stanford.edu.

Abstract

BACKGROUND:

Opioids are a mainstay for the treatment of chronic pain. Unfortunately, therapy-limiting maladaptations such as loss of treatment effect (tolerance), and paradoxical opioid-induced hyperalgesia (OIH) can occur. The objective of this study was to identify genes responsible for opioid tolerance and OIH.

RESULTS:

These studies used a well-established model of ascending morphine administration to induce tolerance, OIH and other opioid maladaptations in 23 strains of inbred mice. Genome-wide computational genetic mapping was then applied to the data in combination with a false discovery rate filter. Transgenic mice, gene expression experiments and immunoprecipitation assays were used to confirm the functional roles of the most strongly linked gene. The behavioral data processed using computational genetic mapping and false discovery rate filtering provided several strongly linked biologically plausible gene associations. The strongest of these was the highly polymorphic Mpdz gene coding for the post-synaptic scaffolding protein Mpdz/MUPP1. Heterozygous Mpdz +/- mice displayed reduced opioid tolerance and OIH. Mpdz gene expression and Mpdz/MUPP1 protein levels were lower in the spinal cords of low-adapting 129S1/Svlm mice than in high-adapting C57BL/6 mice. Morphine did not alter Mpdz expression levels. In addition, association of Mpdz/MUPP1 with its known binding partner CaMKII did not differ between these high- and low-adapting strains.

CONCLUSIONS:

The degrees of maladaptive changes in response to repeated administration of morphine vary greatly across inbred strains of mice. Variants of the multiple PDZ domain gene Mpdz may contribute to the observed inter-strain variability in tolerance and OIH by virtue of changes in the level of their expression.

KEYWORDS:

Drug tolerance; Gene mapping; Opioid analgesics; Synaptic plasticity

PMID:
27129385
PMCID:
PMC4850636
DOI:
10.1186/s12864-016-2634-1
[Indexed for MEDLINE]
Free PMC Article

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