Pioglitazone rapidly reduces neuropathic pain through astrocyte and nongenomic PPARγ mechanisms

Ryan B. Griggs, Renee R. Donahue, Jenny Morgenweck, Peter M. Grace, Amanda Sutton, Linda R. Watkins, Bradley K. Taylor

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

Repeated administration of peroxisome proliferator-activated receptor gamma (PPARγ) agonists reduces neuropathic pain-like behavior and associated changes in glial activation in the spinal cord dorsal horn. As PPARγ is a nuclear receptor, sustained changes in gene expression are widely believed to be the mechanism of pain reduction. However, we recently reported that a single intrathecal (i.t.) injection of pioglitazone, a PPARγ agonist, reduced hyperalgesia within 30 minutes, a time frame that is typically less than that required for genomic mechanisms. To determine the very rapid antihyperalgesic actions of PPARγ activation, we administered pioglitazone to rats with spared nerve injury and evaluated hyperalgesia. Pioglitazone inhibited hyperalgesia within 5 minutes of injection, consistent with a nongenomic mechanism. Systemic or i.t. administration of GW9662, a PPARγ antagonist, inhibited the antihyperalgesic actions of intraperitoneal or i.t. pioglitazone, suggesting a spinal PPARγ-dependent mechanism. To further address the contribution of nongenomic mechanisms, we blocked new protein synthesis in the spinal cord with anisomycin. When coadministered intrathecally, anisomycin did not change pioglitazone antihyperalgesia at an early 7.5-minute time point, further supporting a rapid nongenomic mechanism. At later time points, anisomycin reduced pioglitazone antihyperalgesia, suggesting delayed recruitment of genomic mechanisms. Pioglitazone reduction of spared nerve injury-induced increases in GFAP expression occurred more rapidly than expected, within 60 minutes. We are the first to show that activation of spinal PPARγ rapidly reduces neuropathic pain independent of canonical genomic activity. We conclude that acute pioglitazone inhibits neuropathic pain in part by reducing astrocyte activation and through both genomic and nongenomic PPARγ mechanisms.

Original languageEnglish (US)
Pages (from-to)469-482
Number of pages14
JournalPain
Volume156
Issue number3
DOIs
StatePublished - Mar 1 2015

Bibliographical note

Funding Information:
Supported by 5R01NS062306 and R01NS045954 to B. K. Taylor; T32NS077889 and F31NS083292 to R. B. Griggs; NIH CTSA UL1TR000117 to the University of Kentucky; NHMRC 1054091 and AAA Sir Keith Murdoch Fellowship to P. M. Grace.

Keywords

  • Astrocyte
  • Neuropathic
  • Nongenomic
  • PPAR gamma
  • Pain
  • Pioglitazone

Fingerprint Dive into the research topics of 'Pioglitazone rapidly reduces neuropathic pain through astrocyte and nongenomic PPARγ mechanisms'. Together they form a unique fingerprint.

Cite this