Abstract
Abstract: :
Purpose: The purpose of this study was to determine whether Fas-receptor death complex formation is involved in the apoptotic death of the retinal ganglion cells after optic nerve crush in the rat. Methods: Male Brown-Norway rats were subjected to right (OD) optic nerve crush (3mm posterior to the globe). The left eye (OS) served as a control. Rats were sacrificed 1 and 3 days after optic nerve crush. Retinal protein was collected for Western Blots and probed with polyclonal antibodies specific for Fas and procaspase 8. Alpha-tubulin was used as a loading control. Immunoprecipitation was performed with an anti-Fas antibody and the immunoprecipitated protein was probed with an anti-procaspase 8 antibody. Results were analyzed by densitometry. The amount of procaspase 8, Fas and Fas/proscaspase 8 death receptor compex were expressed as a ratio of the crush eye to the control eye (OD/OS). Results: Total retinal procaspase 8 levels remained unchanged up to 3 days after optic nerve crush (p ≷ 0.05, n = 6 at 1 and 3 days). There was a significant increase, however, in Fas levels 3 days after optic nerve crush (day 1: OD/OS = 0.76 ± 0.12; day 3: OD/OS = 5.83 ± 2.6; p < 0.05, n = 6 at each time point). In addition, immunoprecipitation studies showed a 1.8 ± 0.5 fold increase in the association of Fas and procaspase 8 one day after optic nerve crush (n = 4, p < 0.05). Conclusion: Our data suggest that optic nerve crush induces the formation of a death-receptor signaling complex, which may participate in caspase 8 activation with subsequent caspase-3 cleavage and apoptosis.
Keywords: 323 apoptosis/cell death • 415 ganglion cells