Truncated mu opioid GPCR variant involvement in opioid-dependent and opioid-independent pain modulatory systems within the CNS Journal Article


Authors: Marrone, G. F.; Grinnell, S. G.; Lu, Z.; Rossi, G. C.; Le Rouzic, V.; Xu, J.; Majumdar, S.; Pan, Y. X.; Pasternak, G. W.
Article Title: Truncated mu opioid GPCR variant involvement in opioid-dependent and opioid-independent pain modulatory systems within the CNS
Abstract: The clinical management of severe pain depends heavily on opioids acting through mu opioid receptors encoded by the Oprm1 gene, which undergoes extensive alternative splicing. In addition to generating a series of prototypic seven transmembrane domain (7TM) G protein-coupled receptors (GPCRs), Oprm1 also produces a set of truncated splice variants containing only six transmembrane domains (6TM) through which selected opioids such as IBNtxA (3′-iodobenzoyl- 6β-naltrexamide) mediate a potent analgesiawithout many undesirable effects. Although morphine analgesia is independent of these 6TM mu receptor isoforms, we now show that the selective loss of the 6TM variants in a knockout model eliminates the analgesic actions of delta and kappa opioids and of α2-adrenergic compounds, but not cannabinoid, neurotensin, or muscarinic drugs. These observations were confirmed by using antisense paradigms. Despite their role in analgesia, loss of the 6TM variants were not involved with delta opioid-induced seizure activity, aversion to the kappa drug U50,488H, or α2-mediated hypolocomotion. These observations support the existence of parallel opioid and nonopioid pain modulatory systems and highlight the ability to dissociate unwanted delta, kappa1, and α2 actions from analgesia.
Keywords: morphine; analgesia; mu opioid receptor; gpcr; truncation
Journal Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 113
Issue: 13
ISSN: 0027-8424
Publisher: National Academy of Sciences  
Date Published: 2016-03-29
Start Page: 3663
End Page: 3668
Language: English
DOI: 10.1073/pnas.1523894113
PROVIDER: scopus
PMCID: PMC4822618
PUBMED: 26976581
DOI/URL:
Notes: Article -- Export Date: 2 May 2016 -- Source: Scopus
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MSK Authors
  1. Yingxian Pan
    132 Pan
  2. Zhigang Lu
    11 Lu
  3. Gavril W Pasternak
    414 Pasternak
  4. Gina   Marrone
    14 Marrone
  5. Jin   Xu
    60 Xu