title: Expression of ephrin-A2 in the superior colliculus and EphA5 in the retina following optic nerve section in adult rat.
abstract: The vertebrate retina projects topographically to visual brain centres. In the developing visual system, gradients of ephrins and Eph receptors play a role in defining topography. At maturity, ephrins but not Ephs are downregulated. Here we show that optic nerve section in adult rat differentially regulates the expression of ephrin-A2 in the superior colliculus (SC) and of EphA5 in the retina. Expression was quantified immunohistochemically; ephrin-A2 levels were also estimated by semiquantitative reverse transcriptase polymerase chain reaction. In the normal SC, ephrin-A2 was expressed at low levels. At 1 month, levels of protein and of mRNA were upregulated across the contralateral SC giving rise to an increasing rostro-caudal gradient. At 6 months, levels had fallen but a gradient remained. In the retina of normal animals, EphA5 was expressed as an increasing naso-temporal gradient. By 1 month, expression was decreased in far temporal retina, resulting in a uniform expression across the naso-temporal axis. We suggest that denervation-induced plastic changes within the SC modify expression of these molecules.
authors.affiliation: Department of Zoology, The University of Western Australia, Nedlands 6907, Western Australia. jrodger@cyllene.uwa.edu.au
authors.forename: J
authors.initials: J
authors.lastname: Rodger
authors.forename: K A
authors.initials: KA
authors.lastname: Lindsey
authors.forename: S G
authors.initials: SG
authors.lastname: Leaver
authors.forename: C E
authors.initials: CE
authors.lastname: King
authors.forename: S A
authors.initials: SA
authors.lastname: Dunlop
authors.forename: L D
authors.initials: LD
authors.lastname: Beazley
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D036383:Ephrin-A2; D036386:Ephrin-A5; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009416:Nerve Regeneration / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D020221:Optic Nerve Injuries / Q000378:metabolism* / Q000503:physiopathology; D051381:Rats; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000378:metabolism; D013477:Superior Colliculi / Q000166:cytology / Q000378:metabolism*; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D036383:Ephrin-A2; D036386:Ephrin-A5; D008565:Membrane Proteins; D014157:Transcription Factors