Journal article
Spinal Nerve Ligation Decreases γ-Aminobutyric AcidB Receptors on Specific Populations of Immunohistochemically Identified Neurons in L5 Dorsal Root Ganglion of the Rat
Journal of comparative neurology (1911), Vol.520(8), pp.1663-1677
06/01/2012
DOI: 10.1002/cne.23005
PMCID: PMC3902039
PMID: 22120979
Abstract
This study examined the distribution of γ-aminobutyric acid (GABA)
B
receptors on immunohistochemically identified neurons, and levels of GABA
B(1)
and GABA
B(2)
mRNA, in the L4 and L5 dorsal root ganglia (DRG) of the rat in the absence of injury and 2 weeks after L5 spinal nerve ligation. In uninjured DRG, GABA
B(1)
immunoreactivity colocalized exclusively with the neuronal marker (NeuN) and did not colocalize with the satellite cell marker S-100. The GABA
B(1)
subunit colocalized to >97% of DRG neurons immunoreactive (IR) for neurofilament 200 (N52) or calcitonin gene-related peptide (CGRP), or labeled by isolectin B4 (IB4). Immunoreactivity for GABA
B(2)
was not detectable. L5 spinal nerve ligation did not alter the number of GABA
B(1)
-IR neurons or its colocalization pattern in the L4 DRG. However, ligation reduced the number of GABA
B(1)
-IR neurons in the L5 DRG by ≈38% compared with sham-operated and naïve rats. Specifically, ligation decreased the number of CGRP-IR neurons in the L5 DRG by 75%, but did not decrease the percent colocalization of GABA
B(1)
in those that remained. In the few IB4-positive neurons that remained in the L5 DRG, colocalization of GABA
B(1)
-IR decreased to 75%. Ligation also decreased levels of GABA
B(1)
and GABA
B(2)
mRNA in the L5, but not the L4 DRG compared with sham-operated or naïve rats. These findings indicate that the GABA
B
receptor is positioned to presynaptically modulate afferent transmission by myelinated, unmyelinated, and peptidergic afferents in the dorsal horn. Loss of GABA
B
receptors on primary afferent neurons may contribute to the development of mechanical allodynia after L5 spinal nerve ligation.
Details
- Title: Subtitle
- Spinal Nerve Ligation Decreases γ-Aminobutyric AcidB Receptors on Specific Populations of Immunohistochemically Identified Neurons in L5 Dorsal Root Ganglion of the Rat
- Creators
- Mitchell P Engle - Department of Pharmacology, University of Iowa, Iowa City, Iowa 52242Michelle A Merrill - Department of Anesthesia, University of Iowa, Iowa City, Iowa 52242Blanca Marquez de Prado - Department of Anesthesia, University of Iowa, Iowa City, Iowa 52242Donna L Hammond - Department of Pharmacology, University of Iowa, Iowa City, Iowa 52242
- Resource Type
- Journal article
- Publication Details
- Journal of comparative neurology (1911), Vol.520(8), pp.1663-1677
- DOI
- 10.1002/cne.23005
- PMID
- 22120979
- PMCID
- PMC3902039
- NLM abbreviation
- J Comp Neurol
- ISSN
- 0021-9967
- eISSN
- 1096-9861
- Grant note
- R01 DA016430 || DA / National Institute on Drug Abuse : NIDA
- Language
- English
- Date published
- 06/01/2012
- Academic Unit
- Iowa Neuroscience Institute; Nursing; Anesthesia; Neuroscience and Pharmacology
- Record Identifier
- 9984007167002771
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