ABSTRACT
BACKGROUND: G protein-coupled receptor, family C, group 5 (GPRC5B), a retinoic acid-inducible orphan G-protein-coupled receptor (GPCR), is a member of the group C metabotropic glutamate receptor family proteins presumably related in non-canonical Wnt signaling. In this study, we investigated altered GPRC5B expression in the dorsal horn of the spinal cord after spinal nerve injury and its involvement in the development of neuropathic pain. METHODS: After induction of anesthesia by intraperitoneal injection of pentobarbital (35 mg /kg), the left L5 spinal nerve at the level of 2 mm distal to the L5 DRG was tightly ligated with silk and cut just distal to the ligature. Seven days after nerve injury, animals were perfused with 4% paraformaldehyde, and the spinal cords were extracted and post-fixed at 4degrees C overnight. To identify the expression of GPRC5B and analyze the involvement of GPRC5B in neuropathic pain, immunofluorescence was performed using several markers for neurons and glial cells in spinal cord tissue. RESULTS: After L5 spinal nerve ligation (SNL), the expression of GPRC5B was decreased in the ipsilateral part, as compared to the contralateral part, of the spinal dorsal horn. SNL induced the downregulation of GPRC5B in NeuN-positive neurons in the spinal dorsal horn. However, CNPase-positive oligodendrocytes, OX42-positive microglia, and GFAP-positive astrocytes were not immunolabeled with GPRC5B antibody in the spinal dorsal horn. CONCLUSIONS: These results imply that L5 SNL-induced GPRC5B downregulation may affect microglial activation in the spinal dorsal horn and be involved in neuropathic pain.
Subject(s)
Animals , Child , Humans , Anesthesia , Astrocytes , Child, Orphaned , Diagnosis-Related Groups , Down-Regulation , Fluorescent Antibody Technique , Horns , Injections, Intraperitoneal , Ligation , Microglia , Neuralgia , Neuroglia , Neurons , Oligodendroglia , Pentobarbital , Receptors, Metabotropic Glutamate , Silk , Spinal Cord , Spinal NervesABSTRACT
The caudate-putamen is generally referred to as the striatum or neostriatum, which is one of the main components of the basal ganglia and this designation, is especially relevant in the rat. In spite of the fact that it comprises one of the major parts in central nervous system, studies on how seriously vulnerable this area to cerebral ischemia especially in neonates is still remained. In this study, using neonatal (7 days postnatal) rats, we speculated the significance of AIF in the apoptotic neuronal cell death in basal ganglia induced by hypoxic-ischemic injury. For this study, we introduced permanent common carotid artery occlusion and then, exposed to 6% oxygen for 2 hours and the results are as follows: 1. There were tendency of increasing AIF immunoreactivity induced by hypoxic-ischemic insult in neonatal basal ganglia at 12 & 24 hrs after hypoxic-ischemic insult. 2. Western Blotting analysis showed increased AIF expression in basal ganglia at 12 hrs(caudate-putamen) & 24 hrs (globus pallidus) after hypoxic-ischemic insult. 3. Evidence of localization of AIF in glial cells as well as in neurons obtained by double-immunofluorescence staining. Our results seem to provide evidences on the involvement of AIF in the apoptotic neuronal cell loss with hypoxicischemic insult in neonatal rat. Furthermore, localization AIF in glial cells as well as in neurons suggests involvement of neuroglial cells in the apoptotic pathway in neonatal basal ganglia induced by hypoxic-ischemic injury.