Targeted Overexpression of Astrocytic Endothelin-1 Attenuates Neuropathic Pain by Upregulating Spinal Excitatory Amino Acid Transporter-2

J Mol Neurosci. 2015 Sep;57(1):90-6. doi: 10.1007/s12031-015-0581-y. Epub 2015 May 21.

Abstract

We previously demonstrated that endogenous endothelin-1 (ET-1) inhibits pathological pain in a transgenic mouse model with astrocyte-specific ET-1 overexpression (GET-1 mice); however, the underlying mechanism is unclear. ET-1 regulates excitatory amino acid transporter-2 (EAAT-2), a predominant subtype of glutamate transporters that plays critical role in pain modulation in spinal astrocytes. We hypothesized that astrocytic ET-1 overexpression alleviates neuropathic pain through modulating EAAT-2. GET-1 or nontransgenic (NTg) mice either received sham operation or sciatic nerve ligation (SNL) with or without ceftriaxone (CEF, an EAAT-2 inducer, for 4 days before termination). In GET-1 mice, mRNA and protein expressions of EAAT-2, but not EAAT-1, were upregulated associated with reduced SNL-induced neuropathic pain. Despite that SNL induced a significant reduction of EAAT-2 mRNA expression in both genotypes of mice, post-SNL EAAT-2 mRNA expression was higher in GET-1 mice than that in NTg mice. EAAT-2 induction by CEF reduced SNL-induced neuropathic pain in both NTg and GET-1 mice. In cultured rat astrocytic cell line, overexpression of ET-1 mRNA expression also elevated EAAT-2 mRNA expression, which was reversed by ET receptor antagonists. In conclusion, overexpressed astrocytic ET-1 suppressed neuropathic pain by upregulating spinal EAAT-2 expression via ET receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / metabolism
  • Cell Line
  • Endothelin-1 / genetics
  • Endothelin-1 / metabolism*
  • Excitatory Amino Acid Transporter 2 / genetics
  • Excitatory Amino Acid Transporter 2 / metabolism*
  • Male
  • Mice
  • Neuralgia / metabolism*
  • Rats
  • Sciatic Nerve / metabolism
  • Sciatic Nerve / pathology
  • Up-Regulation

Substances

  • Endothelin-1
  • Excitatory Amino Acid Transporter 2