Journal of Molecular Neuroscience

, Volume 54, Issue 1, pp 78–91

Changes in Thyroid Hormone Receptors After Permanent Cerebral Ischemia in Male Rats

Authors

  • Athanasios Lourbopoulos
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
  • Iordanis Mourouzis
    • Laboratory of Pharmacology, Medical SchoolUniversity of Athens
  • Theodoros Karapanayiotides
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
  • Evangelia Nousiopoulou
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
  • Stavros Chatzigeorgiou
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
  • Theodoros Mavridis
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
  • Ioannis Kokkinakis
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
  • Olga Touloumi
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
  • Theano Irinopoulou
    • Institut National de la Santé et de la Recherche Médicale (INSERM)
  • Konstantinos Chouliaras
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
  • Constantinos Pantos
    • Laboratory of Pharmacology, Medical SchoolUniversity of Athens
  • Dimitris Karacostas
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
    • B’ Department of Neurology, Laboratory of Experimental Neurology and NeuroimmunologyAHEPA University Hospital
Article

DOI: 10.1007/s12031-014-0253-3

Cite this article as:
Lourbopoulos, A., Mourouzis, I., Karapanayiotides, T. et al. J Mol Neurosci (2014) 54: 78. doi:10.1007/s12031-014-0253-3

Abstract

Thyroid hormones (TH) and receptors (TRs) may play an important role in the pathophysiology of acute cerebral ischemia. In the present study, we sought to determine whether serum triodothyronine (T3)/thyroxine (T4) and brain TRs (TRα1, TRβ1) might change after experimental stroke. Male adult Wistar rats were subjected to permanent middle cerebral artery occlusion (group P) and compared to sham-operated controls (group S). Animals were followed clinically for 14 days until brain collection for Western blot (WB) or neuropathological analysis of TRs in three different brain areas (infarcted tissue, E1; noninfarcted ipsilateral hemisphere, E2; and contralateral hemisphere, E3). Analysis of serum TH levels showed a reduction of T4 in group P (p = 0.002) at days 2 to 14, while half of the animals also displayed “low T3” values (p = 0.012) on day 14. This T4 reduction was inversely correlated to the clinical severity of stroke and the concomitant body weight loss (p < 0.005). WB analysis of TRα1 and TRβ1 protein expression showed heterogenic responses at day 14: total and nuclear TRα1 were similar between the two groups, while total TRβ1 decreased 7.5-fold within E1 (p ≤ 0.001) with a concomitant 1.8-fold increase of nuclear TRβ1 in E2 area (p = 0.03); TRβ1 expression did not differ in E3. Neuropathological analysis revealed that activated macrophages/microglia exclusively expressed nuclear TRα1 within the infarct core. Astrocytes mildly expressed nuclear TRα1 in and around the infarct, along with a prominent TRβ nuclear signal restricted in the astrocytic scar. Neurons around the infarct expressed mainly TRα1 and, to a milder degree, TRβ. Surprisingly enough, we detected for the first time a TRβ expression in the paranodal region of Ranvier nodes, of unknown significance so far. Our data support that cerebral ischemia induces a low TH response, associated with significant and heterogenic changes in brain TR expression. These findings could imply an important role of TH signaling in cerebral ischemia.

Keywords

ThyroxinCerebral ischemiaBrain remodelingThyroid receptorPlasticityAstrocytic scarMCAO

Supplementary material

12031_2014_253_MOESM1_ESM.tif (475 kb)
Supplementary FigureRepresentative cortical high magnification fields from the pre-absorption assays for the TRβ antibody. Panel (A) indicates a clear, nodal, TRβ signal using the regular immunofluorescent (IF) staining protocol, without pre-absorption; panel (B) indicates a complete absence of the specific nodal TRβ signal with mild non-specific tissue background, after antibody-peptide pre-absorption IF; panel (C) indicates no fluorescent signal after incubation of the tissue with the secondary antibody as an internal control (Biotium 488). Inserts display higher magnification details of the corresponding optical fields (small white blocks). (TIFF 475 kb)
12031_2014_253_Fig9_ESM.jpg (7 kb)

High resolution image (JPEG 6 kb)

Copyright information

© Springer Science+Business Media New York 2014