title: Injury to retinal ganglion cell axons increases polysialylated neural cell adhesion molecule (PSA-NCAM) in the adult rodent superior colliculus.
abstract: The adult mammalian central nervous system (CNS) exhibits a limited regenerative response to injury. It is well established that polysialylated neural cell adhesion molecule (PSA-NCAM) contributes to nervous system plasticity. In the visual system, PSA-NCAM participates in retinal ganglion cell (RGC) axon growth during development and specifically influences RGC innervation of its principle target tissue, the superior colliculus (SC). The goals of this study were to determine whether PSA-NCAM is expressed in the normal adult mouse SC and to evaluate PSA-NCAM expression following RGC injury. In the normal rostral, but not caudal, SC we find that PSA-NCAM is present in the retinorecipient layers; however, PSA-NCAM and RGC axons do not co-localize. In the deeper collicular layers, PSA-NCAM is observed as several distinct patches that occur at the same depth along the medial-lateral axis throughout the colliculus. RGC axotomy denervates predominantly the contralateral colliculus, where increased PSA-NCAM levels are seen at 7 and 10 days after the injury. Further evaluation of the retinorecipient layers of the partially denervated SC reveals that some intact CTB-traced RGC axons (less than 5%) labeled from the ipsilateral eye do co-localize with PSA-NCAM. This study is the first characterization of PSA-NCAM expression in the normal and partially denervated adult SC and may indicate that PSA-NCAM is involved in attempted visual system remodeling after injury.
authors.affiliation: Neuron Survival and Regeneration Laboratory, Department of Anatomy and Neurobiology, Faculty of Medicine, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5.
authors.forename: J A
authors.initials: JA
authors.lastname: Murphy
authors.forename: P E B
authors.initials: PE
authors.lastname: Nickerson
authors.forename: D B
authors.initials: DB
authors.lastname: Clarke
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism*; D002772:Cholera Toxin; D005260:Female; D007839:Functional Laterality; D005786:Gene Expression Regulation / Q000502:physiology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D039842:Neural Cell Adhesion Molecule L1 / Q000378:metabolism*; D020221:Optic Nerve Injuries / Q000378:metabolism* / Q000473:pathology; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012794:Sialic Acids / Q000378:metabolism*; D013477:Superior Colliculi / Q000378:metabolism*; D013997:Time Factors
chemical_list: D005904:Glial Fibrillary Acidic Protein; D039842:Neural Cell Adhesion Molecule L1; D012794:Sialic Acids; C103469:polysialyl neural cell adhesion molecule; D002772:Cholera Toxin; D010751:Phosphopyruvate Hydratase