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Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation

BACKGROUND: Spinal reactive astrocytes and microglia are known to participate to the initiation and maintenance of neuropathic pain. However, whether reactive astrocytes and microglia in thalamic nuclei that process sensory-discriminative aspects of pain play a role in pain behavior remains poorly i...

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Autores principales: Blaszczyk, Lucie, Maître, Marlène, Lesté-Lasserre, Thierry, Clark, Samantha, Cota, Daniela, Oliet, Stéphane H. R., Fénelon, Valérie S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6302506/
https://www.ncbi.nlm.nih.gov/pubmed/30572902
http://dx.doi.org/10.1186/s12974-018-1378-z
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author Blaszczyk, Lucie
Maître, Marlène
Lesté-Lasserre, Thierry
Clark, Samantha
Cota, Daniela
Oliet, Stéphane H. R.
Fénelon, Valérie S.
author_facet Blaszczyk, Lucie
Maître, Marlène
Lesté-Lasserre, Thierry
Clark, Samantha
Cota, Daniela
Oliet, Stéphane H. R.
Fénelon, Valérie S.
author_sort Blaszczyk, Lucie
collection PubMed
description BACKGROUND: Spinal reactive astrocytes and microglia are known to participate to the initiation and maintenance of neuropathic pain. However, whether reactive astrocytes and microglia in thalamic nuclei that process sensory-discriminative aspects of pain play a role in pain behavior remains poorly investigated. Therefore, the present study evaluated whether the presence of reactive glia (hypertrophy, increased number and upregulation of glial markers) in the ventral posterolateral thalamic nucleus (VPL) correlates with pain symptoms, 14 and 28 days after unilateral L5/L6 spinal nerve ligation (SNL) in rats. METHODS: Mechanical allodynia and hyperalgesia (von Frey filament stimulation) as well as ambulatory pain (dynamic weight bearing apparatus) were assessed. Levels of nine glial transcripts were determined by quantitative real-time PCR on laser microdissected thalamic nuclei, and levels of proteins were assessed by Western blot. We also studied by immunohistofluorescence the expression of glial markers that label processes (GFAP for astrocytes and iba-1 for microglia) and cell body (S100β for astrocytes and iba-1 for microglia) and quantified the immunostained surface and the number of astrocytes and microglia (conventional counts and optical dissector method of stereological counting). RESULTS: Differential, time-dependent responses were observed concerning microglia and astrocytes. Specifically, at day 14, iba-1 immunostained area and number of iba-1 immunopositive cells were decreased in the VPL of SNL as compared to naïve rats. By contrast, at day 28, GFAP-immunostained area was increased in the VPL of SNL as compared to naïve rats while number of GFAP/S100β immunopositive cells remained unchanged. Using quantitative real-time PCR of laser microdissected VPL, we found a sequential increase in mRNA expression of cathepsin S (day 14), fractalkine (day 28), and fractalkine receptor (day 14), three well-known markers of microglial reactivity. Using Western blot, we confirmed an increase in protein expression of fractalkine receptor at day 14. CONCLUSIONS: Our results demonstrate a sequential alteration of microglia and astrocytes in the thalamus of animals with lesioned peripheral nerves. Furthermore, our data report unprecedented concomitant molecular signs of microglial activation and morphological signs of microglial decline in the thalamus of these animals.
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spelling pubmed-63025062018-12-31 Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation Blaszczyk, Lucie Maître, Marlène Lesté-Lasserre, Thierry Clark, Samantha Cota, Daniela Oliet, Stéphane H. R. Fénelon, Valérie S. J Neuroinflammation Research BACKGROUND: Spinal reactive astrocytes and microglia are known to participate to the initiation and maintenance of neuropathic pain. However, whether reactive astrocytes and microglia in thalamic nuclei that process sensory-discriminative aspects of pain play a role in pain behavior remains poorly investigated. Therefore, the present study evaluated whether the presence of reactive glia (hypertrophy, increased number and upregulation of glial markers) in the ventral posterolateral thalamic nucleus (VPL) correlates with pain symptoms, 14 and 28 days after unilateral L5/L6 spinal nerve ligation (SNL) in rats. METHODS: Mechanical allodynia and hyperalgesia (von Frey filament stimulation) as well as ambulatory pain (dynamic weight bearing apparatus) were assessed. Levels of nine glial transcripts were determined by quantitative real-time PCR on laser microdissected thalamic nuclei, and levels of proteins were assessed by Western blot. We also studied by immunohistofluorescence the expression of glial markers that label processes (GFAP for astrocytes and iba-1 for microglia) and cell body (S100β for astrocytes and iba-1 for microglia) and quantified the immunostained surface and the number of astrocytes and microglia (conventional counts and optical dissector method of stereological counting). RESULTS: Differential, time-dependent responses were observed concerning microglia and astrocytes. Specifically, at day 14, iba-1 immunostained area and number of iba-1 immunopositive cells were decreased in the VPL of SNL as compared to naïve rats. By contrast, at day 28, GFAP-immunostained area was increased in the VPL of SNL as compared to naïve rats while number of GFAP/S100β immunopositive cells remained unchanged. Using quantitative real-time PCR of laser microdissected VPL, we found a sequential increase in mRNA expression of cathepsin S (day 14), fractalkine (day 28), and fractalkine receptor (day 14), three well-known markers of microglial reactivity. Using Western blot, we confirmed an increase in protein expression of fractalkine receptor at day 14. CONCLUSIONS: Our results demonstrate a sequential alteration of microglia and astrocytes in the thalamus of animals with lesioned peripheral nerves. Furthermore, our data report unprecedented concomitant molecular signs of microglial activation and morphological signs of microglial decline in the thalamus of these animals. BioMed Central 2018-12-20 /pmc/articles/PMC6302506/ /pubmed/30572902 http://dx.doi.org/10.1186/s12974-018-1378-z Text en © The Author(s). 2018 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Blaszczyk, Lucie
Maître, Marlène
Lesté-Lasserre, Thierry
Clark, Samantha
Cota, Daniela
Oliet, Stéphane H. R.
Fénelon, Valérie S.
Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation
title Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation
title_full Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation
title_fullStr Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation
title_full_unstemmed Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation
title_short Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation
title_sort sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6302506/
https://www.ncbi.nlm.nih.gov/pubmed/30572902
http://dx.doi.org/10.1186/s12974-018-1378-z
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