purpose. Stress-induced crystallin expression is commonly viewed as activation of the cell survival mechanism. The authors analyzed the expression of αA-and αB-crystallins in a rat optic nerve transection (ONT) model characterized by specific retinal ganglion cell (RGC) degeneration and determined their role in RGC survival.

methods. ONT was performed on adult Wistar rats. Quantitative and spatial expression were examined with Western blot analysis and immunohistochemistry, respectively. Electroporation was used to deliver αA and αB expression constructs to RGCs. Cell-protective effects of αA and αB overexpression after ONT were determined by RGC density analysis.

results. Expression of αA and αB in the retina was observed predominantly in the ganglion cell layer, where most crystallin-positive cells were colocalized with RGCs. Levels of αA and αB proteins after ONT were decreased 1.6-fold. The effect of αA and αB overexpression on RGC survival was evaluated 7 and 14 days after axotomy. At day 7 after ONT, 1426±70 and 1418±81 RGCs/mm 2 were present in retinas electroporated with αA and αB expression constructs, respectively, compared with 1010±121 RGCs/mm 2 in sham-transfected or 1016±88 RGCs/mm 2 in nontransfected retinas. Numbers of surviving RGCs at 14 days were 389±57 and 353.57±60 cells/mm 2 after αA and αB transfection, respectively, compared with 198±29 cells/mm 2 after transfection with the vector alone or 206±60 cells/mm 2 in nontransfected retinas.

conclusions. Increases of approximately 95% and 75% in RGC survival mediated by αA and αB overexpression, respectively, were observed 14 days after ONT. At day 7, the RGC protective effect of αA and αB overexpression was approximately 40%.