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Pain. 2016 Sep;157(9):2081-8. doi: 10.1097/j.pain.0000000000000621.

Group II mGluRs suppress hyperexcitability in mouse and human nociceptors.

Author information

1
aDepartment of Anesthesiology, Pain Center, Washington University School of Medicine in St. Louis, St. Louis, MO, USA bSchool of Sciences, University of Texas at Dallas School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA cDepartment of Neuropathology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA dAnaBios Corporation, San Diego, CA, USA. eS. Davidson is now with Pain Research Center, Department of Anesthesiology, University of Cincinnati, College of Medicine, Cincinnati, OH, USA.

Abstract

We introduce a strategy for preclinical research wherein promising targets for analgesia are tested in rodent and subsequently validated in human sensory neurons. We evaluate group II metabotropic glutamate receptors, the activation of which is efficacious in rodent models of pain. Immunohistochemical analysis showed positive immunoreactivity for mGlu2 in rodent dorsal root ganglia (DRG), peripheral fibers in skin, and central labeling in the spinal dorsal horn. We also found mGlu2-positive immunoreactivity in human neonatal and adult DRG. RNA-seq analysis of mouse and human DRG revealed a comparative expression profile between species for group II mGluRs and for opioid receptors. In rodent sensory neurons under basal conditions, activation of group II mGluRs with a selective group II agonist produced no changes to membrane excitability. However, membrane hyperexcitability in sensory neurons exposed to the inflammatory mediator prostaglandin E2 (PGE2) was prevented by (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate (APDC). In human sensory neurons from donors without a history of chronic pain, we show that PGE2 produced hyperexcitability that was similarly blocked by group II mGluR activation. These results reveal a mechanism for peripheral analgesia likely shared by mice and humans and demonstrate a translational research strategy to improve preclinical validation of novel analgesics using cultured human sensory neurons.

PMID:
27218869
PMCID:
PMC4988887
DOI:
10.1097/j.pain.0000000000000621
[Indexed for MEDLINE]
Free PMC Article

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