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- Title
Effects of peripheral nerve injury on parvalbumin expression in adult rat dorsal root ganglion neurons.
- Authors
Medici, Tom; Shortland, Peter J.
- Abstract
<bold>Background: </bold>Parvalbumin (PV) is a calcium binding protein that identifies a subpopulation of proprioceptive dorsal root ganglion (DRG) neurons. Calcitonin gene-related peptide (CGRP) is also expressed in a high proportion of muscle afferents but its relationship to PV is unclear. Little is known of the phenotypic responses of muscle afferents to nerve injury. Sciatic nerve axotomy or L5 spinal nerve ligation and section (SNL) lesions were used to explore these issues in adult rats using immunocytochemistry.<bold>Results: </bold>In naive animals, the mean PV expression was 25 % of L4 or L5 dorsal root ganglion (DRG) neurons, and this was unchanged 2 weeks after sciatic nerve axotomy. Colocalization studies with the injury marker activating transcription factor 3 (ATF3) showed that approximately 24 % of PV neurons expressed ATF3 after sciatic nerve axotomy suggesting that PV may show a phenotypic switch from injured to uninjured neurons. This possibility was further assessed using the spinal nerve ligation (SNL) injury model where injured and uninjured neurons are located in different DRGs. Two weeks after L5 SNL there was no change in total PV staining and essentially all L5 PV neurons expressed ATF3. Additionally, there was no increase in PV-ir in the adjacent uninjured L4 DRG cells. Co-labelling of DRG neurons revealed that less than 2 % of PV neurons normally expressed CGRP and no colocalization was seen after injury.<bold>Conclusion: </bold>These experiments clearly show that axotomy does not produce down regulation of PV protein in the DRG. Moreover, this lack of change is not due to a phenotypic switch in PV immunoreactive (ir) neurons, or de novo expression of PV-ir in uninjured neurons after nerve injury. These results further illustrate differences that occur when muscle afferents are injured as compared to cutaneous afferents.
- Subjects
PERIPHERAL nerve injuries; PARVALBUMINS; LABORATORY rats; NEURONS; NEUROPLASTICITY; AXOTOMY; SPINAL nerve roots; PROPRIOCEPTORS; PROTEIN metabolism; SCIATIC nerve injuries; ANIMAL experimentation; ANIMALS; SENSORY ganglia; LUMBAR vertebrae; RATS; SENSORY neurons; ALBUMINS; SKELETAL muscle; INNERVATION
- Publication
BMC Neuroscience, 2015, Vol 16, p1
- ISSN
1471-2202
- Publication type
journal article
- DOI
10.1186/s12868-015-0232-9