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Nociceptor-expressed ephrin-B2 regulates inflammatory and neuropathic pain.

Zhao J, Yuan G, Cendan CM, Nassar MA, Lagerström MC, Kullander K, Gavazzi I, Wood JN - Mol Pain (2010)

Bottom Line: Formalin-induced pain behavior was attenuated in the second phase, and this correlated with diminished tyrosine phosphorylation of N-methyl-D-aspartic acid (NMDA) receptor subunit NR2B in the dorsal horn.Thermal hyperalgesia and mechanical allodynia were significantly reduced in the Seltzer model of neuropathic pain.Presynaptic ephrin-B2 expression thus plays an important role in regulating inflammatory pain through the regulation of synaptic plasticity in the dorsal horn and is also involved in the pathogenesis of some types of neuropathic pain.

View Article: PubMed Central - HTML - PubMed

Affiliation: Molecular Nociception Group, Wolfson Institute for Biomedical Research, Cruciform Building, University College London, London WC1E 6BT, UK.

ABSTRACT

Background: EphB receptors and their ephrin-B ligands play an important role in nervous system development, as well as synapse formation and plasticity in the adult brain. Recent studies show that intrathecal treatment with EphB-receptor activator ephrinB2-Fc induced thermal hyperalgesia and mechanical allodynia in rat, indicating that ephrin-B2 in small dorsal root ganglia (DRG) neurons and EphB receptors in the spinal cord modulate pain processing. To examine the role of ephrin-B2 in peripheral pain pathways, we deleted ephrin-B2 in Nav1.8+ nociceptive sensory neurons with the Cre-loxP system. Sensory neuron numbers and terminals were examined using neuronal makers. Pain behavior in acute, inflammatory and neuropathic pain models was assessed in the ephrin-B2 conditional knockout (CKO) mice. We also investigated the c-Fos expression and NMDA receptor NR2B phosphorylation in ephrin-B2 CKO mice and littermate controls.

Results: The ephrin-B2 CKO mice were healthy with no sensory neuron loss. However, pain-related behavior was substantially altered. Although acute pain behavior and motor co-ordination were normal, inflammatory pain was attenuated in ephrin-B2 mutant mice. Complete Freund's adjuvant (CFA)-induced mechanical hyperalgesia was halved. Formalin-induced pain behavior was attenuated in the second phase, and this correlated with diminished tyrosine phosphorylation of N-methyl-D-aspartic acid (NMDA) receptor subunit NR2B in the dorsal horn. Thermal hyperalgesia and mechanical allodynia were significantly reduced in the Seltzer model of neuropathic pain.

Conclusions: Presynaptic ephrin-B2 expression thus plays an important role in regulating inflammatory pain through the regulation of synaptic plasticity in the dorsal horn and is also involved in the pathogenesis of some types of neuropathic pain.

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Neural marker expression was normal in DRG neurons of ephrin-B2 CKO mice. (A) Whole DRG sections of Efnb2 CKO mutant mice and Efnb2fl/fl littermate controls were labeled with anti-peripherin (green) and anti-neurofilament (red) antibodies. The right panels are merged images of the left and middle panels. (B) DRG sections were also labeled with anti-CGRP (red) and anti-IB4 (red) antibodies, co-labeled with anti-βIII-tubulin (green). The right panels are erged images of the left and middle panels. (C) The proportions of CGRP, IB4 and neurofilament (N52) expressing neurons were normal in Efnb2 CKO animals compared to Efnb2fl/fl littermate controls. (D) Cross section of lumbar spinal cord (L3 - L5) stained with anti-CGRP (green) antibody and anti-IB4 (red) antibody. In laminae I-II, both CGRP positive terminals and IB4 positive terminals were identified in the Efnb2 CKO mutant mice and Efnb2fl/fl littermate controls. Scale bar = 50 μm.
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Figure 2: Neural marker expression was normal in DRG neurons of ephrin-B2 CKO mice. (A) Whole DRG sections of Efnb2 CKO mutant mice and Efnb2fl/fl littermate controls were labeled with anti-peripherin (green) and anti-neurofilament (red) antibodies. The right panels are merged images of the left and middle panels. (B) DRG sections were also labeled with anti-CGRP (red) and anti-IB4 (red) antibodies, co-labeled with anti-βIII-tubulin (green). The right panels are erged images of the left and middle panels. (C) The proportions of CGRP, IB4 and neurofilament (N52) expressing neurons were normal in Efnb2 CKO animals compared to Efnb2fl/fl littermate controls. (D) Cross section of lumbar spinal cord (L3 - L5) stained with anti-CGRP (green) antibody and anti-IB4 (red) antibody. In laminae I-II, both CGRP positive terminals and IB4 positive terminals were identified in the Efnb2 CKO mutant mice and Efnb2fl/fl littermate controls. Scale bar = 50 μm.

Mentions: Whole DRG sections were examined to test for effects of ephrin-B2 deletion on neuronal survival. The sections were labeled for neuronal markers peripherin and neurofilament heavy chain. The result shows that most small and medium diameter DRG neurons (nociceptors) were labeled with anti-peripherin antibody in green, large diameter DRG neurons were labeled with anti-neurofilament (N200) in red (Figure 2A). There was no apparent difference between Efnb2fl/fl controls and Efnb2 CKO mutant mice. The DRG sections from L5 were also labeled with neuronal marker IB4, anti-CGRP and anti-neurofilament (N52), and co-labeled with neuron marker βIII tubulin. All the sections from Efnb2 CKO mutants had a normal appearance, with no significant difference from Efnb2fl/fl controls (Figure 2B), and the proportions of IB4, CGRP and neurofilament (N52) positive neurons in Efnb2 CKO mice ware similar to the Efnb2fl/fl controls (Figure 2C). The spinal cord sections from lumber 4-5, labeled with IB4 and anti-CGRP, were used to investigate the distribution of the nociceptive primary afferent terminals from Efnb2 CKO mutant mice. The result shows that no significant difference was found on estimated area of termination or their staining intensity from the IB4 and CGRP labeling (Figure 2D).


Nociceptor-expressed ephrin-B2 regulates inflammatory and neuropathic pain.

Zhao J, Yuan G, Cendan CM, Nassar MA, Lagerström MC, Kullander K, Gavazzi I, Wood JN - Mol Pain (2010)

Neural marker expression was normal in DRG neurons of ephrin-B2 CKO mice. (A) Whole DRG sections of Efnb2 CKO mutant mice and Efnb2fl/fl littermate controls were labeled with anti-peripherin (green) and anti-neurofilament (red) antibodies. The right panels are merged images of the left and middle panels. (B) DRG sections were also labeled with anti-CGRP (red) and anti-IB4 (red) antibodies, co-labeled with anti-βIII-tubulin (green). The right panels are erged images of the left and middle panels. (C) The proportions of CGRP, IB4 and neurofilament (N52) expressing neurons were normal in Efnb2 CKO animals compared to Efnb2fl/fl littermate controls. (D) Cross section of lumbar spinal cord (L3 - L5) stained with anti-CGRP (green) antibody and anti-IB4 (red) antibody. In laminae I-II, both CGRP positive terminals and IB4 positive terminals were identified in the Efnb2 CKO mutant mice and Efnb2fl/fl littermate controls. Scale bar = 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 2: Neural marker expression was normal in DRG neurons of ephrin-B2 CKO mice. (A) Whole DRG sections of Efnb2 CKO mutant mice and Efnb2fl/fl littermate controls were labeled with anti-peripherin (green) and anti-neurofilament (red) antibodies. The right panels are merged images of the left and middle panels. (B) DRG sections were also labeled with anti-CGRP (red) and anti-IB4 (red) antibodies, co-labeled with anti-βIII-tubulin (green). The right panels are erged images of the left and middle panels. (C) The proportions of CGRP, IB4 and neurofilament (N52) expressing neurons were normal in Efnb2 CKO animals compared to Efnb2fl/fl littermate controls. (D) Cross section of lumbar spinal cord (L3 - L5) stained with anti-CGRP (green) antibody and anti-IB4 (red) antibody. In laminae I-II, both CGRP positive terminals and IB4 positive terminals were identified in the Efnb2 CKO mutant mice and Efnb2fl/fl littermate controls. Scale bar = 50 μm.
Mentions: Whole DRG sections were examined to test for effects of ephrin-B2 deletion on neuronal survival. The sections were labeled for neuronal markers peripherin and neurofilament heavy chain. The result shows that most small and medium diameter DRG neurons (nociceptors) were labeled with anti-peripherin antibody in green, large diameter DRG neurons were labeled with anti-neurofilament (N200) in red (Figure 2A). There was no apparent difference between Efnb2fl/fl controls and Efnb2 CKO mutant mice. The DRG sections from L5 were also labeled with neuronal marker IB4, anti-CGRP and anti-neurofilament (N52), and co-labeled with neuron marker βIII tubulin. All the sections from Efnb2 CKO mutants had a normal appearance, with no significant difference from Efnb2fl/fl controls (Figure 2B), and the proportions of IB4, CGRP and neurofilament (N52) positive neurons in Efnb2 CKO mice ware similar to the Efnb2fl/fl controls (Figure 2C). The spinal cord sections from lumber 4-5, labeled with IB4 and anti-CGRP, were used to investigate the distribution of the nociceptive primary afferent terminals from Efnb2 CKO mutant mice. The result shows that no significant difference was found on estimated area of termination or their staining intensity from the IB4 and CGRP labeling (Figure 2D).

Bottom Line: Formalin-induced pain behavior was attenuated in the second phase, and this correlated with diminished tyrosine phosphorylation of N-methyl-D-aspartic acid (NMDA) receptor subunit NR2B in the dorsal horn.Thermal hyperalgesia and mechanical allodynia were significantly reduced in the Seltzer model of neuropathic pain.Presynaptic ephrin-B2 expression thus plays an important role in regulating inflammatory pain through the regulation of synaptic plasticity in the dorsal horn and is also involved in the pathogenesis of some types of neuropathic pain.

View Article: PubMed Central - HTML - PubMed

Affiliation: Molecular Nociception Group, Wolfson Institute for Biomedical Research, Cruciform Building, University College London, London WC1E 6BT, UK.

ABSTRACT

Background: EphB receptors and their ephrin-B ligands play an important role in nervous system development, as well as synapse formation and plasticity in the adult brain. Recent studies show that intrathecal treatment with EphB-receptor activator ephrinB2-Fc induced thermal hyperalgesia and mechanical allodynia in rat, indicating that ephrin-B2 in small dorsal root ganglia (DRG) neurons and EphB receptors in the spinal cord modulate pain processing. To examine the role of ephrin-B2 in peripheral pain pathways, we deleted ephrin-B2 in Nav1.8+ nociceptive sensory neurons with the Cre-loxP system. Sensory neuron numbers and terminals were examined using neuronal makers. Pain behavior in acute, inflammatory and neuropathic pain models was assessed in the ephrin-B2 conditional knockout (CKO) mice. We also investigated the c-Fos expression and NMDA receptor NR2B phosphorylation in ephrin-B2 CKO mice and littermate controls.

Results: The ephrin-B2 CKO mice were healthy with no sensory neuron loss. However, pain-related behavior was substantially altered. Although acute pain behavior and motor co-ordination were normal, inflammatory pain was attenuated in ephrin-B2 mutant mice. Complete Freund's adjuvant (CFA)-induced mechanical hyperalgesia was halved. Formalin-induced pain behavior was attenuated in the second phase, and this correlated with diminished tyrosine phosphorylation of N-methyl-D-aspartic acid (NMDA) receptor subunit NR2B in the dorsal horn. Thermal hyperalgesia and mechanical allodynia were significantly reduced in the Seltzer model of neuropathic pain.

Conclusions: Presynaptic ephrin-B2 expression thus plays an important role in regulating inflammatory pain through the regulation of synaptic plasticity in the dorsal horn and is also involved in the pathogenesis of some types of neuropathic pain.

Show MeSH
Related in: MedlinePlus