Spinal peroxynitrite contributes to remifentanil-induced postoperative hyperalgesia via enhancement of divalent metal transporter 1 without iron-responsive element-mediated iron accumulation in rats

Anesthesiology. 2015 Apr;122(4):908-20. doi: 10.1097/ALN.0000000000000562.

Abstract

Background: Hyperalgesia is one of the negative consequences following intraoperative analgesia with remifentanil. Peroxynitrite is a critical determinant in nociceptive process. Peroxynitrite inactivates iron-sulfur cluster that results in mitochondrial dysfunction and the release of iron, leading to mitochondrial iron accumulation. Iron accumulation mediated by divalent metal transporter 1 (DMT1) plays a key role in N-methyl-D-aspartate neurotoxicity. This study aims to determine whether peroxynitrite contributes to remifentanil-induced postoperative hyperalgesia via DMT1-mediated iron accumulation.

Methods: Behavior testing was performed in rat model at different time points. Three-nitrotyrosine, nitrated manganese superoxide dismutase, and DMT1 with/without iron-responsive element [DMT1(+)IRE and DMT1(-)IRE] in spinal cord were detected by Western blot and immunohistochemistry. Spinal iron concentration was measured using the Perl stain and atomic absorption spectrophotometer. Hydrogen-rich saline imparting selectivity for peroxynitrite decomposition and iron chelator was applied in mechanistic study on the roles of peroxynitrite and iron, as well as the prevention of hyperalgesia.

Results: Remifentanil induced thermal and mechanical hyperalgesia at postoperative 48 h. Compared with control, there were higher levels of 3-nitrotyrosine (mean ± SD, hyperalgesia vs. control, 1.22 ± 0.18 vs. 0.25 ± 0.05, n = 4), nitrated manganese superoxide dismutase (1.01 ± 0.1 vs. 0.19 ± 0.03, n = 4), DMT1(-)IRE (1.42 ± 0.19 vs. 0.33 ± 0.06, n = 4), and iron concentration (12.87 ± 1.14 vs. 5.26 ± 0.61 μg/g, n = 6) in remifentanil-induced postoperative hyperalgesia, while DMT1(+)IRE was unaffected. Eliminating peroxynitrite with hydrogen-rich saline protected against hyperalgesia and attenuated DMT1(-)IRE overexpression and iron accumulation. Iron chelator prevented hyperalgesia in a dose-dependent manner.

Conclusions: Our study identifies that spinal peroxynitrite activates DMT1(-)IRE, leading to abnormal iron accumulation in remifentanil-induced postoperative hyperalgesia, while providing the rationale for the development of molecular hydrogen and "iron-targeted" therapies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cation Transport Proteins / biosynthesis*
  • Hyperalgesia / chemically induced
  • Hyperalgesia / metabolism*
  • Iron / metabolism
  • Iron-Regulatory Proteins / biosynthesis*
  • Male
  • Pain, Postoperative / metabolism
  • Peroxynitrous Acid / biosynthesis*
  • Piperidines / toxicity*
  • Rats
  • Rats, Sprague-Dawley
  • Remifentanil
  • Spinal Cord / metabolism*

Substances

  • Cation Transport Proteins
  • Iron-Regulatory Proteins
  • Piperidines
  • solute carrier family 11- (proton-coupled divalent metal ion transporters), member 2
  • Peroxynitrous Acid
  • Iron
  • Remifentanil