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EphA5 and ephrin-A2 expression during optic nerve regeneration: a 'two-edged sword'


Symonds, ACE and King, CE and Bartlett, CA and Sauve, Y and Lund, RD and Beazley, LD and Dunlop, SA and Rodger, J, EphA5 and ephrin-A2 expression during optic nerve regeneration: a 'two-edged sword', European Journal of Neuroscience, 25, (3) pp. 744-752. ISSN 0953-816X (2007) [Refereed Article]

Copyright Statement

Copyright 2007 The Authors

DOI: doi:10.1111/j.1460-9568.2007.05321.x


During development, gradients of EphA receptors (nasal(low)-temporal(high)) and their ligands ephrin-As (rostral(low)-caudal(high)) are involved in establishing topography between retinal ganglion cells (RGCs) and the superior colliculus (SC). EphA5-expressing RGC axons are repulsed by ephrin-A2-expressing SC neurones. In adult rats RGCs maintain graded EphA5 expression but ephrin-A2 expression is down-regulated in the SC to a weak gradient. At 1 month after optic nerve transection, EphA5 expression is reduced in the few remaining RGCs and is no longer graded; by contrast, SC ephrin-A2 is up-regulated to a rostral(low)-caudal(high) gradient. Here we examined expression in adult rat 1 month after bridging the retina and SC with a peripheral nerve graft, a procedure that enhances RGC survival and permits RGC axon regeneration. Double labelling with cell markers revealed preservation of a nasal(low)-temporal(high) EphA5 gradient in RGCs and establishment of a rostral(low)-caudal(high) ephrin-A2 gradient within neurones of the SC. The results suggest a potential for guidance cues to restore the topography of RGC axons in the SC. However, high ephrin-A2 levels were also found in astrocytes surrounding the peripheral nerve graft insertion site. The repulsive ephrin-A2 environment offers at least a partial explanation for the observation that only a limited number of RGC axons can exit the graft to enter target central nervous system tissue.

Item Details

Item Type:Refereed Article
Keywords:Eph, ephrin, optic nerve, regeneration
Research Division:Biomedical and Clinical Sciences
Research Group:Neurosciences
Research Field:Neurology and neuromuscular diseases
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:King, CE (Dr Carolyn King)
ID Code:99039
Year Published:2007
Web of Science® Times Cited:26
Deposited By:Health Sciences B
Deposited On:2015-03-11
Last Modified:2015-04-15

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