title: Alteration of the cell adhesion molecule L1 expression in a specific subset of primary afferent neurons contributes to neuropathic pain.
abstract: The cell adhesion molecule L1 (L1-CAM) plays important functional roles in the developing and adult nervous systems. Here we show that peripheral nerve injury induced dynamic post-transcriptional alteration of L1-CAM in the rat dorsal root ganglia (DRGs) and spinal cord. Sciatic nerve transection (SCNT) changed the expression of L1-CAM protein but not L1-CAM mRNA. In DRGs, SCNT induced accumulation of the L1-CAM into the surface of somata, which resulted in the formation of immunoreactive ring structures in a number of unmyelinated C-fiber neurons. These neurons with L1-CAM-immunoreactive ring structures were heavily colocalized with phosphorylated p38 MAPK. Western blot analysis revealed the increase of full-length L1-CAM and decrease of fragments of L1-CAM after SCNT in DRGs. Following SCNT, L1-CAM-immunoreactive profiles in the dorsal horn showed an increase mainly in pre-synaptic areas of laminae I-II with a delayed onset and colocalized with growth-associated protein 43. In contrast to DRGs, SCNT increased the proteolytic 80-kDa fragment of L1-CAM and decreased full-length L1-CAM in the spinal cord. The intrathecal injection of L1-CAM antibody for the extracellular domain of L1-CAM inhibited activation of p38 MAPK and emergence of ring structures of L1-CAM immunoreactivity in injured DRG neurons. Moreover, inhibition of extracellular L1-CAM binding by intrathecal administration of antibody suppressed the mechanical allodynia and thermal hyperalgesia induced by partial SCNT. Collectively, these data suggest that the modification of L1-CAM in nociceptive pathways might be an important pathomechanism of neuropathic pain.
authors.affiliation: Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamanaka
authors.forename: Koichi
authors.initials: K
authors.lastname: Obata
authors.forename: Kimiko
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Yi
authors.initials: Y
authors.lastname: Dai
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Fukuoka
authors.forename: Koichi
authors.initials: K
authors.lastname: Noguchi
mesh_terms: D000818:Animals; D002452:Cell Count; D005727:Ganglia, Spinal / Q000473:pathology; D005786:Gene Expression Regulation / Q000502:physiology*; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D039842:Neural Cell Adhesion Molecule L1 / Q000378:metabolism*; D009475:Neurons, Afferent / Q000145:classification / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012585:Sciatica / Q000473:pathology* / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D009419:Nerve Tissue Proteins; D039842:Neural Cell Adhesion Molecule L1