Caspase Activation in an Experimental Model of Retinal Detachment

Abstract

Abstract: : Purpose: To test for apoptotic photoreceptor cell death and caspase activation as a function of time after induction of an experimental retinal detachment. Methods: Retinal detachments were created in Brown-Norway rats by injecting 10% hyaluronic acid into the subretinal space using a transvitreal approach. Light microscopy and TUNEL (terminal dUTP-biotin nick end-label)-staining was performed at 1, 3, 5 and 7 days after detachment to assess for the morphologic features associated with apoptosis. Western blotting of retinal protein extracts was performed using antibodies against caspases 3, 7, 9 and poly-ADP ribose-polymerase (PARP) at 1, 3 and 5 days after detachment. Results: Light microscopic analysis of detached retinas showed the presence of pyknotic nuclei in the outer nuclear layer and disruption of the normal organization of the photoreceptor outer segments. TUNEL-staining was positive in the outer nuclear layer only in the detached portions of the retina. Western blotting confirmed the time-dependent activation of caspase 3, 7, 9 and PARP in the detached retinas. No morphologic stigmata of apoptosis or caspase activation were detected in attached retinas. Conclusions: The apoptotic photoreceptor cell death in experimental retinal detachments is associated with caspase activation.

Keywords: retinal detachment • apoptosis/cell death • neuroprotection