Objective        To observe the distributions and expression profiles of stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 in the retinas during repair period after partial optic nerve injury in Long Evans rats.       Methods        A total of 21 adult rats were randomly and equally divided into 7 groups

normal group

the injury group

and the groups in 1

3

5

7

15 and 30 d after optic nerve crushing. Immunofluorescence assay and Western blotting was applied to detect the location and the q

uantity of SDF-1 and CXCR4 expression in the retina.       Results        Immunofluorescence staining revealed that the expression of SDF-1 was co-localized in the activated GFAP-positive astrocytes and Müller cells between the pre-retinal and post-retinal membrane. The amount of SDF-1 positive cells were in a trend of increasing to decreasing with the injury time prolonging

and reached a summit in 5 d after injury. CXCR4 staining was mainly present in the ganglion cell layer

inner nuclear layer and outer nuclear layer of the retina. Western blotting revealed that the expression of SDF-1 protein was increased at the first day and then decreased at the 7th day after injury. The expression of SDF-1 in 1

3

5 and 7 d after optic nerve injuring was increased significantly than normal group (

P

0.05). While

the expression of CXCR4 protein had no change after injury (

P

0.05).       Conclusion        The quantity of SDF-1 is increased first and then decreased in the astrocytes and Müller cells after optic nerve injuring

which is related to the activation of glial cells after injury.