Expression of ephrin-A2 in the superior colliculus and EphA5 in the retina following optic nerve section in adult rat

Authors

  • J. Rodger,

    1. Department of Zoology, The University of Western Australia, Nedlands 6907, Western Australia
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    • *

      J. R. and K. A. L. contributed equally to the work.

  • K. A. Lindsey,

    1. Department of Zoology, The University of Western Australia, Nedlands 6907, Western Australia
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    • *

      J. R. and K. A. L. contributed equally to the work.

  • S. G. Leaver,

    1. Department of Zoology, The University of Western Australia, Nedlands 6907, Western Australia
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  • C. E. King,

    1. Department of Zoology, The University of Western Australia, Nedlands 6907, Western Australia
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  • S. A. Dunlop,

    1. Department of Zoology, The University of Western Australia, Nedlands 6907, Western Australia
    2. West Australian Institute for Medical Research, Hospital Avenue, Nedlands WA 6009, Western Australia
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  • L. D. Beazley

    1. Department of Zoology, The University of Western Australia, Nedlands 6907, Western Australia
    2. West Australian Institute for Medical Research, Hospital Avenue, Nedlands WA 6009, Western Australia
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: Dr J. Rodger, as above.
E-mail: jrodger@cyllene.uwa.edu.au

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.

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