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Activin Induces Tactile Allodynia and Increases Calcitonin Gene-Related Peptide after Peripheral Inflammation
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| Zeitschriftentitel: | The Journal of Neuroscience |
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| Personen und Körperschaften: | , , , |
| In: | The Journal of Neuroscience, 25, 2005, 40, S. 9227-9235 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
Society for Neuroscience
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| Schlagwörter: |
| Zusammenfassung: | <jats:p>Calcitonin gene-related peptide (CGRP) is a sensory neuropeptide important in inflammatory pain that conveys pain information centrally and dilates blood vessels peripherally. Previous studies indicate that activin A increases CGRP-immunoreactive (IR) sensory neurons<jats:italic>in vitro</jats:italic>, and following wound, activin A protein increases in the skin and more neurons have detectable CGRP expression in the innervating dorsal root ganglion (DRG). These data suggest some adult sensory neurons respond to activin A or other target-derived factors with increased neuropeptide expression. This study was undertaken to test whether activin contributes to inflammatory pain and increased CGRP and to learn which neurons retained plasticity. After adjuvant-induced inflammation, activin mRNA, but not NGF or glial cell line-derived neurotrophic factor, increased in the skin. To examine which DRG neurons increased CGRP immunoreactivity, retrograde tracer-labeled cutaneous neurons were characterized after inflammation. The proportion and size of tracer-labeled DRG neurons with detectable CGRP increased after inflammation. One-third of CGRP-IR neurons that appear after inflammation also had isolectin B4 binding, suggesting that some mechanoreceptors became CGRP-IR. In contrast, the increased proportion of CGRP-IR neurons did not appear to come from RT97-IR neurons. To learn whether central projections were altered after inflammation, CGRP immunoreactivity in the protein kinase Cγ-IR lamina IIi was quantified and found to increase. Injection of activin A protein alone caused robust tactile allodynia and increased CGRP in the DRG. Together, these data support the hypothesis that inflammation and skin changes involving activin A cause some sensory neurons to increase CGRP expression and pain responses.</jats:p> |
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| Umfang: | 9227-9235 |
| ISSN: |
0270-6474
1529-2401 |
| DOI: | 10.1523/jneurosci.3051-05.2005 |